U.S. Department of the Interior

Bureau of Ocean Energy Management, 

 Regulation and Enforcement 

Gulf of Mexico OCS Region 

OCS EIS/EA 

BOEMRE 2011-027 

Gulf of Mexico OCS 

Oil and Gas Lease Sale: 2012 

Central Planning Area Lease Sale 216/222 

Draft Supplemental Environmental Impact Statement 
U.S. Department of the Interior

Bureau of Ocean Energy Management, 

 Regulation and Enforcement 

Gulf of Mexico OCS Region 

OCS EIS/EA 

BOEMRE 2011-027 

Gulf of Mexico OCS 

Oil and Gas Lease Sale: 2012 

Central Planning Area Lease Sale 216/222 

Draft Supplemental Environmental Impact Statement 

Author 

Bureau of Ocean Energy Management, 

 Regulation and Enforcement 

Gulf of Mexico OCS Region 

Published by 

New Orleans

June 2011 

v 

COVER SHEET 

Supplemental Environmental Impact Statement 

for 

Proposed Central Planning Area OCS Oil and Gas Lease Sale 216/222 

Draft (x) Final ( ) 

Type of Action: Administrative (x) Legislative ( ) 

Area of Potential Impact: Offshore Marine Environment and Coastal Counties/Parishes of 

Louisiana, Mississippi, and Alabama 

Agency Washington Contact Region Contacts 

U.S. Department of the Interior 

Bureau of Ocean Energy Management, 

Regulation and Enforcement 

Gulf of Mexico OCS Region 

MS 5410 

1201 Elmwood Park Boulevard 

New Orleans, LA 70123-2394 

Keely Hite (MS 4042) 

U.S. Department of the Interior 

Bureau of Ocean Energy Management, 

Regulation and Enforcement 

381 Elden Street 

Herndon, VA 20170-4817 

(703) 787-1662 

Casey Rowe 

(504) 736-2781 

Gary Goeke 

(504) 736-3233 

ABSTRACT 

This Supplemental Environmental Impact Statement (EIS) covers the proposed Gulf of Mexico OCS 

oil and gas consolidated Lease Sale 216/222 in the Central Planning Area. 

This Supplemental EIS tiers from the following EIS’s: the Outer Continental Shelf Oil and Gas 

Leasing Program: 2007-2012, Final Environmental Impact Statement (5-Year Program EIS; USDOI, 

MMS, 2007a), which defined the national program; the Gulf of Mexico OCS Oil and Gas Lease Sales: 

2007-2012; Western Planning Area Sales 204, 207, 210, 215, and 218; Central Planning Area Sales 205, 

206, 208, 213, 216, and 222, Final Environmental Impact Statement (Multisale EIS; USDOI, MMS, 

2007b), which defined the 5-Year Program in the GOM; and the Gulf of Mexico OCS Oil and Gas Lease 

Sales: 2009-2012; Central Planning Area Sales 208, 213, 216, and 222; Western Planning Area Sales 

210, 215, and 218, Final Supplemental Environmental Impact Statement (2009-2012 Supplemental EIS; 

USDOI, MMS, 2008), which was required after passage of the Gulf of Mexico Energy Security Act of 

2006. 

This Supplemental EIS was prepared because of the potential changes to baseline conditions of the 

environmental, socioeconomic, and cultural resources that may have occurred as a result of (1) the 

Deepwater Horizon event between April 20 and July 15, 2010 (the period when oil flowed from the 

Macondo well in Mississippi Canyon Block 252); (2) the acute impacts that have been reported or 

surveyed since that time; and (3) any new information that may be available. The environmental 

resources include sensitive coastal environments, offshore benthic resources, marine mammals, sea 

turtles, coastal and marine birds, endangered and threatened species, and fisheries. This Supplemental 

EIS analyzes the potential impacts of the proposed action on the marine, coastal, and human 

environments. 

The proposed action is a major Federal action requiring an EIS. This document provides the 

following information in accordance with the National Environmental Policy Act and its implementing 

regulations, and it will be used in making decisions on the proposal. This document includes the purpose 

and background of the proposed action, identification of the alternatives, description of the affected 

environment, and an analysis of the potential environmental impacts of the proposed action, alternatives, 

and associated activities, including proposed mitigating measures and their potential effects. Potential 

contributions to cumulative impacts resulting from activities associated with the proposed action are also 

analyzed. 
vi 

Hypothetical scenarios were developed on the levels of activities, accidental events (such as oil 

spills), and potential impacts that might result if the proposed action is adopted. Activities and 

disturbances associated with the proposed action on biological, physical, and socioeconomic resources are 

considered in the analyses. 

Additional copies of this Supplemental EIS, the Multisale EIS, the 2009-2012 Supplemental EIS, and 

the other referenced publications may be obtained from the BOEMRE, Gulf of Mexico OCS Region, 

Public Information Office (MS 5034), 1201 Elmwood Park Boulevard, New Orleans, Louisiana 70123-

2394, or by telephone at 504-736-2519 or 1-800-200-GULF. 
Summary vii

SUMMARY 

Under the Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012 (5-Year Program; 

USDOI, MMS, 2007a), six annual areawide lease sales were scheduled for the Central Planning Area 

(CPA) and five annual areawide lease sales are scheduled for the Western Planning Area (WPA) of the 

Gulf of Mexico (GOM) Outer Continental Shelf (OCS). Those 11 CPA and WPA sales were analyzed in 

the Gulf of Mexico OCS Oil and Gas Lease Sales: 2007-2012; Western Planning Area Sales 204, 207, 

210, 215, and 218; Central Planning Area Sales 205, 206, 208, 213, 216, and 222, Final Environmental 

Impact Statement (Multisale EIS; USDOI, MMS, 2007b) and are hereby incorporated by reference. 

The Gulf of Mexico Energy Security Act (GOMESA) of 2006 (P.L. 109-432, December 20, 2006) 

repealed the Congressional moratorium on certain areas of the Gulf of Mexico, placed a moratorium on 

other areas in the Gulf of Mexico, and increased the distribution of offshore oil and gas revenues to 

coastal States. The remaining seven CPA and WPA sales were analyzed in the Gulf of Mexico OCS Oil 

and Gas Lease Sales: 2009-2012; Central Planning Area Sales 208, 213, 216, and 222; Western 

Planning Area Sales 210, 215, and 218, Final Supplemental Environmental Impact Statement (2009-2012 

Supplemental EIS; USDOI, MMS, 2008a) and are hereby incorporated by reference. 

This Supplemental environmental impact statement (EIS) supplements the Multisale EIS and the 

2009-2012 Supplemental EIS. This Supplemental EIS analyzes the potential environmental effects of oil 

and natural gas leasing, exploration, development, the effects of the Deepwater Horizon (DWH) event, 

and all new information available for the CPA since the publication of the Multisale EIS and the 2009-

2012 Supplemental EIS. 

The purpose of this Supplemental EIS is to determine if new information is substantial enough to alter 

conclusions stated in the Multisale EIS and the 2009-2012 Supplemental EIS and, if so, to disclose those 

changes. This includes all new information and not just that acquired since the DWH event. It must be 

understood that this Supplemental EIS analyzes the proposed action and alternatives for a CPA proposed 

lease sale. This is not an EIS on the DWH event, although information on this event will be analyzed as it 

applies to resources in the CPA. Proposed consolidated CPA Lease Sale 216/222 is the Federal action 

addressed in this Supplemental EIS and is the remaining areawide oil and gas lease sale in the CPA. 

In the National Environmental Policy Act’s (NEPA) implementing regulations (40 CFR 1508.28), 

“tiering” refers to the coverage of general matters in a broader EIS (such as national program), with 

subsequent narrower statements of environmental analyses (such as regional action). Tiering is 

appropriate in this instance because broader program issues have already been subjected to analysis and 

because this Supplemental EIS is more narrowly focused on the site-specific statement or analysis for 

proposed CPA Lease Sale 216/222. This Supplemental EIS tiers from the following EIS’s: the Outer 

Continental Shelf Oil and Gas Leasing Program: 2007-2012, Final Environmental Impact Statement

(5-Year Program EIS; USDOI, MMS, 2007c), which defined the national program; the Multisale EIS, 

which defined the 5-Year Program in the GOM; and the 2009-2012 Supplemental EIS, which was 

required after the passage of GOMESA. 

This summary section is only a brief overview of the proposed lease sale, alternatives, significant 

issues, potential environmental and socioeconomic effects, and proposed mitigating measures contained 

in this Supplemental EIS. To obtain the full perspective and context of the potential environmental and 

socioeconomic impacts discussed, it is necessary to read the entire analyses. Relevant discussions can be 

found in the chapters of this Supplemental EIS as described below. 

 Chapter 1, The Proposed Action, describes the purpose of and need for the proposed 

lease sale and describes the prelease process. 

 Chapter 2, Alternatives Including the Proposed Action, describes the environmental 

and socioeconomic effects of the proposed lease sale and alternatives. Also 

discussed are potential mitigating measures to avoid or minimize impacts. 

 Chapter 3, Impact-Producing Factors and Scenario, describes activities associated 

with the proposed lease sale and the OCS Program, and other foreseeable activities 

that could potentially affect the biological, physical, and socioeconomic resources of 

the Gulf of Mexico. 
viii Central Planning Area Supplemental EIS

Chapter 3.1, Impact-Producing Factors and Scenario—Routine Events, 

describes offshore infrastructure and activities (impact-producing factors) 

associated with the proposed lease sale that could potentially affect the 

biological, physical, and socioeconomic resources of the Gulf of Mexico.

Chapter 3.2, Impact-Producing Factors and Scenario—Accidental Events, 

discusses potential accidental events (i.e., oil spills, losses of well control, 

vessel collisions, and spills of chemicals or drilling fluids) that may occur as 

a result of activities associated with the proposed lease sale. 

Chapter 3.3, Cumulative Activities Scenario, describes past, present, and 

reasonably foreseeable future human activities, including non-OCS activities, 

as well as all OCS activities, that may affect the biological, physical, and 

socioeconomic resources of the Gulf of Mexico. 

 Chapter 4, Description of the Environment and Impact Analysis, describes the 

affected environment and provides analysis of the routine, accidental, and cumulative 

impacts of the CPA proposed action and the alternatives on environmental and 

socioeconomic resources of the Gulf of Mexico. 

Chapter 4.1, Alternatives Including the Proposed Action, describes the 

impacts of the proposed action and three alternatives to the CPA proposed 

action on the biological, physical, and socioeconomic resources of the Gulf 

of Mexico. 

Chapter 4 also includes Chapter 4.2, Unavoidable Adverse Impacts of the 

Proposed Action; Chapter 4.3, Irreversible and Irretrievable Commitment of 

Resources; and Chapter 4.4, Relationship Between the Short-term Use of 

Man’s Environment and the Maintenance and Enhancement of Long-Term 

Productivity. 

 Chapter 5, Consultation and Coordination, describes the consultation and 

coordination activities with Federal, State, and local agencies and other interested 

parties that occurred during the development of this Supplemental EIS. 

 Chapter 6, References Cited, is a list of literature cited throughout this 

Supplemental EIS. 

 Chapter 7, Preparers, is a list of names of persons who were primarily responsible 

for preparing and reviewing this Supplemental EIS. 

 Chapter 8, Glossary, is a list of specialized words with brief definitions used in this 

document. 

Proposed Action and Alternatives 

The following alternatives were included for analysis in the Multisale EIS. No new alternatives were 

proposed for proposed CPA Lease Sale 216/222. 

Alternatives for Proposed Central Planning Area Lease Sale 216/222 

Alternative A—The Proposed Action: This alternative would offer for lease all unleased blocks 

within the CPA for oil and gas operations (Figure 2-1), except for the following: 
Summary ix

(1) blocks directly south of Florida and within 100 miles (mi) (161 kilometers [km])of 

the Florida coast (north of the easternmost portion of the proposed CPA lease sale 

area as shown on Figure 1-1); and 

(2) blocks that are beyond the U.S. Exclusive Economic Zone in the area known as the 

northern portion of the Eastern Gap. 

The CPA sale area encompasses about 63 million acres (ac) of the CPA’s 66.3 million ac. 

Approximately 37.1 million ac (59%) of the CPA sale area is currently unleased. The estimated amount 

of natural resources projected to be developed as a result of the proposed CPA lease sale is 0.801-1.624 

billion barrels of oil (BBO) and 3.332-6.560 trillion cubic feet (Tcf) of gas. 

Alternative B—The Proposed Action Excluding the Unleased Blocks Near Biologically Sensitive 

Topographic Features: This alternative would offer for lease all unleased blocks in the CPA, as 

described for the proposed action (Alternative A), with the exception of any unleased blocks subject to 

the Topographic Features Stipulation. 

Alternative C—The Proposed Action Excluding the Unleased Blocks within 15 Miles of the Baldwin 

County, Alabama, Coast: This alternative would offer for lease all unleased blocks in the CPA, as 

described for the proposed action (Alternative A), with the exception of any unleased blocks within 15 mi 

(24 km) of the Baldwin County, Alabama, coast. 

Alternative D—No Action: This alternative is the cancellation of the proposed CPA lease sale. The 

opportunity for development of the estimated 0.801-1.624 BBO and 3.332-6.560 Tcf of gas that could 

have resulted from the proposed CPA lease sale would be precluded or postponed. Any potential 

environmental impacts resulting from the proposed lease sale would not occur or would be postponed. 

This is also analyzed in the EIS for the 5-Year Program on a nationwide programmatic level. 

Mitigating Measures 

The proposed action includes existing regulations and proposed lease stipulations designed to reduce 

environmental risks, potential multiple-use conflicts between OCS operations and U.S. Department of 

Defense activities. Eight lease stipulations are proposed for the proposed CPA lease sale—the 

Topographic Features Stipulation, the Live Bottom Stipulation, the Military Areas Stipulation, the 

Evacuation Stipulation, the Coordination Stipulation, the Blocks South of Baldwin County, Alabama, 

Stipulation, the Protected Species Stipulation, and the Law of the Sea Convention Royalty Payment 

Stipulation 

Application of lease stipulations will be considered by the Assistant Secretary of the Interior for Land 

and Minerals (ASLM). The analysis of the stipulations as part of the proposed action does not ensure that 

the ASLM will make a decision to apply the stipulations to leases that may result from the proposed lease 

sale, nor does it preclude minor modifications in wording during subsequent steps in the prelease process 

if comments indicate changes are necessary or if conditions warrant. Any stipulations or mitigation 

requirements to be included in the lease sale will be described in the Final Notice of Sale. Mitigation 

measures in the form of lease stipulations are added to the lease terms and are therefore enforceable as 

part of the lease. 

Scenarios Analyzed 

Offshore activities are described in the context of scenarios for the proposed action (Chapter 3.1) and 

for the OCS Program (Chapter 3.3). The Bureau of Ocean Energy Management, Regulation and 

Enforcement’s (BOEMRE’s) Gulf of Mexico OCS Region developed these scenarios to provide a 

framework for detailed analyses of potential impacts of the proposed lease sale. The scenarios are 

presented as ranges of the amounts of undiscovered, unleased hydrocarbon resources estimated to be 

leased and discovered as a result of the proposed action. The analyses are based on an assumed range of 

activities (e.g., the installation of platforms, wells, and pipelines, and the number of helicopter operations 

and service-vessel trips) that would be needed to develop and produce the amount of resources estimated 

to be leased. 
x Central Planning Area Supplemental EIS

The cumulative analysis (Chapter 4.1) considers environmental and socioeconomic impacts that may 

result from the incremental impact of the lease sale when added to all past, present, and reasonably 

foreseeable future human activities, including non-OCS activities such as import tankering and 

commercial fishing, as well as all OCS activities (OCS Program). The OCS Program scenario includes 

all activities that are projected to occur from past, proposed, and future lease sales during the 40-year 

analysis period. This includes projected activity from lease sales that have been held, but for which 

exploration or development has not yet begun or is continuing. In addition to human activities, impacts 

from natural occurrences, such as hurricanes, are analyzed. 

Significant Issues 

The major issues that frame the environmental analyses in this Supplemental EIS are the result of 

concerns raised during years of scoping for the Gulf of Mexico OCS Program. Issues related to OCS 

exploration, development, production, and transportation activities include oil spills, wetlands loss, air 

emissions, discharges, water quality degradation, trash and debris, structure and pipeline emplacement 

activities, platform removal, vessel and helicopter traffic, multiple-use conflicts, support services, 

population fluctuations, demands on public services, land-use planning, tourism, aesthetic interference, 

cultural impacts, environmental justice, and consistency with State coastal zone management programs. 

Environmental resources and activities identified during the scoping process to warrant an environmental 

analysis include air quality, water quality, coastal barrier beaches and associated dunes, wetlands, 

seagrass communities, live bottoms (Pinnacle Trend and low relief), topographic features, Sargassum,

deepwater benthic communities, marine mammals, sea turtles, beach mice, coastal and marine birds, Gulf 

sturgeon, fish resources and essential fish habitat, commercial and recreational fishing, recreational 

resources, archaeological resources, socioeconomic conditions, soft bottoms, and diamondback terrapins. 

Other issues include impacts from the DWH event and from past and future hurricanes on 

environmental and socioeconomic resources, and on coastal and offshore infrastructure. During the past 

few years, the Gulf Coast States and Gulf of Mexico oil and gas activities have been impacted by major 

hurricanes. Appendix A.3 of the Multisale EIS provides detailed information on Hurricanes Lili (2002), 

Ivan (2004), Katrina (2005), and Rita (2005), which are discussed in Chapter 4. The description of the 

affected environment (Chapter 4.1) includes impacts from these storms, as well as Hurricanes Gustav 

(2008) and Ike (2008), on the physical environment, biological environment, and socioeconomic activities 

and OCS-related infrastructure. Baseline data are considered in the assessment of impacts from the 

proposed action to the resources and the environment (Chapter 4.1). 

Impact Conclusions 

The BOEMRE has reexamined the analysis presented in the Multisale EIS and the 2009-2012 

Supplemental EIS, based on the additional information available since the publication of the Multisale 

EIS and the 2009-2012 Supplemental, and the DWH event. No substantial new information, with the 

exception of archaeological resources, was found that would alter the impact conclusions as presented in 

the Multisale EIS and the 2009-2012 Supplemental EIS for a CPA lease sale. In some cases, new 

information that supported these conclusions was found. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the proposed action and the proposed action’s incremental contribution to the cumulative impacts are 

described in Chapter 4.1. A summary of the potential impacts from the CPA proposed action on each 

environmental and socioeconomic resource and the conclusions of the analyses can be found below. 

Air Quality: Emissions of pollutants into the atmosphere from the routine activities associated with 

the CPA proposed action are projected to have minimal impacts to onshore air quality because of the 

prevailing atmospheric conditions, emission heights, emission rates, and the distance of these emissions 

from the coastline, and are expected to be well within the National Ambient Air Quality Standards 

(NAAQS). While regulations are in place to reduce the risk of impacts from H2S and while no 

H2S-related deaths have occurred on the OCS, accidents involving high concentrations of hydrogen 

sulfide (H2S) could result in deaths as well as environmental damage. These emissions from routine 

activities and accidental events associated with the proposed action are not expected to have 

concentrations that would change onshore air quality classifications. 
Summary xi

Coastal and Offshore Waters: Impacts from routine activities associated with the CPA proposed 

action would be minimal if all existing regulatory requirements are met. Coastal water impacts associated 

with routine activities include increases in turbidity resulting from pipeline installation and navigation 

canal maintenance, discharges of bilge and ballast water from support vessels, and run-off from shorebased facilities. Offshore water impacts associated with routine activities result from the discharge of 

drilling muds and cuttings, produced water, residual chemicals used during workovers, structure 

installation and removal and pipeline placement. The discharge of drilling muds and cuttings cause 

temporary increased turbidity and changes in sediment composition. The discharge of produced water 

results in increased concentrations of some metals, hydrocarbons, and dissolved solids within an area of 

about 100 meters (m) (328 feet [ft]) adjacent to the point of discharge. Structure installation and removal 

and pipeline placement disturbs the sediments and causes increased turbidity. In addition, offshore water 

impacts result from supply and service-vessel bilge and ballast water discharges. 

Small spills (<1,000 bbl) are not expected to significantly impact water quality in coastal or offshore 

waters. Large spills (1,000 bbl), however, could impact water quality in coastal waters. Accidental 

chemical spills, release of synthetic-based fluid (SBF), and blowouts would have temporary localized 

impacts on water quality. 

Coastal Barrier Beaches and Associated Dunes: Routine activities in the CPA such as increased 

vessel traffic, maintenance dredging of navigation canals, and pipeline installation would cause negligible 

impacts and would not deleteriously affect barrier beaches and associated dunes. Indirect impacts from 

routine activities are negligible and indistinguishable from direct impacts of onshore activities. The 

potential impacts from accidental events, primarily oil spills, associated with the CPA proposed action are 

anticipated to be minimal. 

Wetlands: Routine activities in the CPA such as pipeline emplacement, navigational channel use, 

maintenance dredging, disposal of OCS wastes, and construction and maintenance of OCS support 

infrastructure in coastal areas are expected to result in low impacts. Indirect impacts from wake erosion 

and saltwater intrusion are expected to result in low impacts that are indistinguishable from direct impacts 

from inshore activities. The potential impacts from accidental events, primarily oil spills, are anticipated 

to be minimal. 

Seagrass Communities: Turbidity impacts from pipeline installation and maintenance dredging 

associated with the proposed action would be temporary and localized. The increment of impacts from 

service-vessel transit associated with the proposed action would be minimal. Should an oil spill occur 

near a seagrass community, impacts from the spill and cleanup would be considered short term in 

duration and minor in scope. Close monitoring and restrictions on the use of bottom-disturbing 

equipment to clean up the spill would be needed to avoid or minimize those impacts. 

Live Bottoms (Pinnacle Trend and Low Relief): The combination of its depth (200-400 ft; 60-120 m), 

separation from sources of impacts as mandated by the Live Bottoms (Pinnacle Trend and Low Relief) 

Stipulation, and a community adapted to sedimentation makes damage to the ecosystem unlikely from 

routine activities associated with a CPA proposed action. In the unlikely event that oil from a subsurface 

spill would reach the biota of these communities, the effects would be primarily sublethal for adult sessile 

biota and there would be limited incidences of mortality. 

Topographic Features: The routine activities associated with the CPA proposed action that would 

impact topographic feature communities include anchoring, infrastructure and pipeline emplacement, 

infrastructure removal, drilling discharges, and produced-water discharges. However, adherence to the 

proposed Topographic Features Stipulation would make damage to the ecosystem unlikely. Contact with 

accidentally spilled oil would cause lethal and sublethal effects in benthic organisms, but the oiling of 

benthic organisms is not likely because of the small area of the banks, the scattered occurrence of spills, 

the depth of the features, and because the proposed Topographic Features Stipulation would keep 

subsurface sources of spills away from the immediate vicinity of topographic features. 

Sargassum: The impacts to Sargassum that are associated with the proposed action are expected to 

have only minor effects to a small portion of the Sargassum community as a whole. The Sargassum

community lives in pelagic waters with generally high water quality and would be resilient to the minor 

effects predicted. It has a yearly cycle that promotes quick recovery from impacts. No measurable 

impacts are expected to the overall population of the Sargassum community from the CPA proposed 

action. 
xii Central Planning Area Supplemental EIS

Chemosynthetic and Nonchemosynthetic Deepwater Benthic Communities: Chemosynthetic and 

nonchemosynthetic communities are susceptible to physical impacts from structure placement, anchoring, 

and pipeline installation associated with the CPA proposed action; however, the provisions of Notice to 

Lessees and Operators (NTL) 2009-G40 greatly reduce the risk of these physical impacts by requiring 

avoidance of potential chemosynthetic communities and by consequence avoidance of other hard-bottom 

communities. Even in situations where substantial burial of typical benthic infaunal communities 

occurred, recolonization from populations from widespread, neighboring, soft-bottom substrate would be 

expected over a relatively short period of time for all size ranges of organisms. Potential accidental 

events associated with the proposed action are expected to cause little damage to the ecological function 

or biological productivity of the widespread, low-density chemosynthetic communities and the 

widespread, typical, deep-sea benthic communities. 

Marine Mammals: Routine events related to the CPA proposed action, particularly when mitigated as 

required by BOEMRE, are not expected to have long-term adverse effects on the size and productivity of 

any marine mammal species or population endemic to the northern Gulf of Mexico. Characteristics of 

impacts from accidental events depend on chronic or acute exposure resulting in harassment, harm, or 

mortality to marine mammals, while exposure to dispersed hydrocarbons is likely to result in sublethal 

impacts. 

Sea Turtles: The routine activities of the CPA proposed action are unlikely to have significant 

adverse effects on the size and recovery of any sea turtle species or population in the Gulf of Mexico. 

Accidental events associated with the proposed action have the potential to impact small to large numbers 

of sea turtles. Populations of sea turtles in the northern Gulf of Mexico would be exposed to residuals of 

oils spilled as a result of the proposed action during their lifetimes. While chronic or acute exposure from 

accidental events may result in the harassment, harm, or mortality to sea turtles, in most foreseeable cases, 

exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick would result in 

sublethal impacts. 

Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice: An impact from the 

consumption of beach trash and debris associated with a CPA proposed action on the Alabama, 

Choctawhatchee, St. Andrew, and Perdido Key beach mice is possible but unlikely. While potential spills 

that could result from a CPA proposed action are not expected to contact beach mice or their habitats, 

large-scale oiling of beach mice could result in extinction, and if not properly regulated, oil-spill response 

and cleanup activities could have a significant impact to the beach mice and their habitat. 

Coastal and Marine Birds: The majority of effects resulting from routine activities associated with 

the CPA proposed action on endangered/threatened and nonendangered/nonthreatened coastal and marine 

birds are expected to be sublethal. These effects include behavioral effects, exposure to or intake of OCSrelated contaminants or discarded debris, temporary disturbances, and displacement of localized groups 

from impacted habitats. Impacts from potential oil spills associated with the proposed action and oil-spill 

cleanup on birds are expected to be negligible; however, small amounts of oil can affect birds, and there 

are possible delayed impacts on their food supply. 

Gulf Sturgeon: Routine activities in the CPA such as installation of pipelines, maintenance dredging, 

potential vessel strikes, and nonpoint-source runoff from onshore facilities would cause negligible 

impacts and would not deleteriously affect Gulf sturgeon. Indirect impacts from routine activities to 

inshore habitats are negligible and indistinguishable from direct impacts of inshore activities. The 

potential impacts from accidental events, mainly oil spills associated with a CPA proposed action, are 

anticipated to be minimal. Because of the floating nature of oil and the small tidal range of the Gulf of 

Mexico, oil spills alone would typically have very little impact on benthic feeders such as the Gulf 

sturgeon. 

Fish Resources and Essential Fish Habitat: Fish resources and essential fish habitat could be 

impacted by coastal environmental degradation, marine environmental degradation, pipeline trenching, 

and offshore discharges of drilling discharges and produced waters associated with routine activities. The 

impact of coastal and marine environmental degradation is expected to cause an undetectable decrease in 

fish resources or in essential fish habitat. Impacts of routine discharges are localized in time and space 

and are regulated by U.S. Environmental Protection Agency permits and would have minimal impact. 

Accidental events that could impact fish resources and essential fish habitat include blowouts and oil or 

chemical spills. A subsurface blowout would have a negligible effect on Gulf of Mexico fish resources. 

If spills due to the proposed action were to occur in open waters of the OCS proximate to mobile adult 
Summary xiii

finfish or shellfish, the effects would likely be nonfatal, and the extent of damage would be reduced due 

to the capability of adult fish and some adult shellfish to avoid a spill. 

Commercial Fishing: Routine activities in the CPA, such as seismic surveys and pipeline trenching, 

would cause negligible impacts and would not deleteriously affect commercial fishing activities. Indirect 

impacts from routine activities to inshore habitats are negligible and indistinguishable from direct impacts 

of inshore activities on commercial fisheries. The potential impacts from accidental events, a well 

blowout or an oil spill, associated with the CPA proposed action are anticipated to be minimal. 

Commercial fishermen are anticipated to avoid the area of a well blowout or an oil spill. Any impact on 

catch or value of catch would be insignificant compared with natural variability. 

Recreational Fishing: Routine activities in the CPA, such as seismic surveys and pipeline trenching, 

would cause negligible impacts and would not deleteriously affect recreational fishing activities. Indirect 

impacts to inshore habitats are negligible and indistinguishable from direct impacts of inshore activities 

on recreational fisheries. Temporary localized impacts to recreational fishermen from oil spills are 

anticipated as a result of the CPA proposed action, and possibly some loss of revenue to facilities 

supported by recreational fishermen such as boat launches and bait shops. 

Recreational Resources: While marine debris and nearshore operations, either individually or 

collectively, may adversely affect the quality of some recreational experiences, they are unlikely to reduce 

the number of recreational visits to Gulf Coast beaches. Except for a catastrophic spill such as the DWH 

event, it is unlikely that a spill would be a major threat to recreational beaches because any impacts would 

be short term and localized, and should have no long-term effect on tourism. 

Historic and Prehistoric Archaeological Resources: The greatest potential impact to an 

archaeological resource as a result of routine activities associated with the CPA proposed action would 

result from direct contact between an offshore activity (e.g., platform installation, drilling rig 

emplacement, and dredging or pipeline project) and a historic or prehistoric site. The archaeological 

survey and archaeological clearance of sites required prior to an operator beginning oil and gas activities 

on a lease are expected to be highly effective at identifying possible offshore archaeological sites; 

however, should such contact occur, there would be damage to or loss of significant and/or unique 

archaeological information. It is expected that coastal archaeological resources would be protected 

through the review and approval processes of the various Federal, State, and local agencies involved in 

permitting onshore activities. 

It is not very likely that a large oil spill would occur and contact coastal prehistoric or historic 

archaeological sites from accidental events associated with the proposed action. Should a spill contact a 

prehistoric archaeological site, damage might include loss of radiocarbon-dating potential, direct impact 

from oil-spill cleanup equipment, and/or looting resulting in the irreversible loss of unique or significant 

archaeological information. The major effect from an oil-spill impact on coastal historic archaeological 

sites would be visual contamination, which would be temporary and reversible. 

Land Use and Coastal Infrastructure: The CPA proposed action would not require additional coastal 

infrastructure, with the exception of possibly one new gas processing facility and one new pipeline 

landfall, and it would not alter the current land use of the analysis area. The existing oil and gas 

infrastructure is expected to be sufficient to handle development associated with the proposed action. 

There may be some expansion at current facilities, but the land in the analysis area is sufficient to handle 

such development. There is also sufficient land to construct a new gas processing plant in the analysis 

area, should it be needed. Accidental events such as oil or chemical spills, blowouts, and vessel collisions 

would have no effects on land use. Coastal or nearshore spills, as well as vessel collisions, could have 

short-term adverse effects on coastal infrastructure requiring cleanup of any oil or chemicals spilled. 

Demographics: The CPA proposed action is projected to minimally affect the demography of the 

analysis area. Population impacts from the proposed action are projected to be minimal (<1% of total 

population) for any economic impact area in the Gulf of Mexico region. The baseline population patterns 

and distributions, as projected and described in Chapter 3.3.5.4 of the Multisale EIS, are expected to 

remain unchanged as a result of the proposed action. The increase in employment is expected to be met 

primarily with the existing population and available labor force with the exception of some in-migration 

(some of whom may be foreign), which is projected to move into focal areas such as Port Fourchon. 

Accidental events associated with the proposed action, such as oil or chemical spills, blowouts, and vessel 

collisions, would have likely no effects on the demographic characteristics of the Gulf coastal 

communities. 
xiv Central Planning Area Supplemental EIS

Economic Factors: The CPA proposed action is expected to generate less than a 1 percent increase in 

employment in any of the coastal subareas, even when the net employment impacts from accidental 

events are included. Most of the employment related to the proposed action is expected to occur in Texas 

and Louisiana. The demand would be met primarily with the existing population and labor force.

Environmental Justice: Environmental justice implications arise indirectly from onshore activities 

conducted in support of OCS exploration, development, and production. Because the onshore 

infrastructure support system for OCS-related industry (and its associated labor force) is highly 

developed, widespread, and has operated for decades within a heterogeneous Gulf of Mexico population, 

the proposed action is not expected to have disproportionately high or adverse environmental or health 

effects on minority or low-income people. The CPA proposed action would help to maintain ongoing 

levels of activity rather than expand them. With the exception of a catastrophic accidental event, such as 

the DWH event, the impacts of oil spills, vessel collisions, and chemical/drilling fluid spills are not likely 

to be of sufficient duration to have adverse and disproportionate long-term effects for low-income and 

minority communities in the analysis area. 

Soft-Bottom Habitat: The routine activities associated with the CPA proposed action that would 

impact soft bottoms generally occur within a few hundred meters of platforms, and the greatest impacts 

are seen close to the platform communities. Although localized impacts to comparatively small areas of 

the soft-bottom benthic habitats would occur, the impacts would be on a relatively small area of the 

seafloor compared with the overall area of the seafloor of the CPA (268,922 square kilometers [km2

]; 

103,831 square miles [mi2

]). The CPA proposed action is not expected to adversely impact the entire 

soft-bottom environment because the local impacted areas are extremely small compared with the entire 

seafloor of the Gulf of Mexico. 

Diamondback Terrapins: The routine activities of the CPA proposed action are unlikely to have 

significant adverse effects diamondback terrapins. Accidental events associated with the proposed action 

have the potential to impact small to large numbers of terrapins. Due to the extended distance from shore, 

impacts associated with activities occurring as a result of the CPA proposed action are not expected to 

impact terrapins or their habitat. 
Table of Contents xv

TABLE OF CONTENTS 

Page 

SUMMARY................................................................................................................................................vii

LIST OF FIGURES .................................................................................................................................xxiii

LIST OF TABLES....................................................................................................................................xxv

ABBREVIATIONS AND ACRONYMS ................................................................................................xxix

1. THE PROPOSED ACTION ................................................................................................................1-3

1.1. Purpose of and Need for the Proposed Action.........................................................................1-3

1.2. Description of the Proposed Action .........................................................................................1-4

1.3. Regulatory Framework ............................................................................................................1-4

1.3.1. Rule Changes following the Deepwater Horizon Event ...........................................1-6

1.4. Prelease Process .....................................................................................................................1-11

1.5. Postlease Activities ................................................................................................................1-13

1.6. Other OCS-Related Activities................................................................................................1-30

2. ALTERNATIVES INCLUDING THE PROPOSED ACTION ..........................................................2-3

2.1. Supplemental EIS NEPA Analysis ..........................................................................................2-3

2.2. Alternatives, Mitigating Measures, and Issues ........................................................................2-3

2.2.1. Alternatives ...............................................................................................................2-3

2.2.1.1. Alternatives for Proposed Central Planning Area Lease 

Sale 216/222.............................................................................................2-3

2.2.1.2. Alternatives Considered but Not Analyzed..............................................2-4

2.2.2. Mitigating Measures..................................................................................................2-5

2.2.2.1. Proposed Mitigating Measures Analyzed ................................................2-5

2.2.2.2. Existing Mitigating Measures ..................................................................2-6

2.2.3. Issues .........................................................................................................................2-6

2.2.3.1. Issues to be Analyzed...............................................................................2-7

2.2.3.2. Issues Considered but Not Analyzed .......................................................2-7

2.3. Proposed Central Planning Area Lease Sale 216/222..............................................................2-8

2.3.1. Alternative A—The Proposed Action .......................................................................2-8

2.3.1.1. Description...............................................................................................2-8

2.3.1.2. Summary of Impacts ................................................................................2-8

2.3.1.3. Mitigating Measures ..............................................................................2-26

2.3.1.3.1. Topographic Features Stipulation .......................................2-26

2.3.1.3.2. Live Bottoms (Pinnacle Trend and Low Relief) 

Stipulation ...........................................................................2-26

2.3.1.3.3. Military Areas Stipulation...................................................2-27

2.3.1.3.4. Evacuation Stipulation ........................................................2-27

2.3.1.3.5. Coordination Stipulation .....................................................2-27

2.3.1.3.6. Blocks South of Baldwin County, Alabama, 

Stipulation ...........................................................................2-27

2.3.1.3.7. Protected Species Stipulation ..............................................2-27

2.3.1.3.8. Law of the Sea Convention Royalty Payment 

Stipulation ...........................................................................2-28
xvi Central Planning Area Supplemental EIS

2.3.2. Alternative B—The Proposed Action Excluding the Unleased Blocks Near 

the Biologically Sensitive Topographic Features....................................................2-28

2.3.2.1. Description.............................................................................................2-28

2.3.2.2. Summary of Impacts ..............................................................................2-28

2.3.3. Alternative C—The Proposed Action Excluding the Unleased Blocks within 

15 Miles of the Baldwin County, Alabama, Coast..................................................2-28

2.3.3.1. Description.............................................................................................2-28

2.3.3.2. Summary of Impacts ..............................................................................2-28

2.3.4. Alternative D—No Action ......................................................................................2-29

2.3.4.1. Description.............................................................................................2-29

2.3.4.2. Summary of Impacts ..............................................................................2-29

3. IMPACT-PRODUCING FACTORS AND SCENARIO ....................................................................3-3

3.1. Impact-Producing Factors and Scenario—Routine Operations ...............................................3-3

3.1.1. Offshore Impact-Producing Factors and Scenario ....................................................3-3

3.1.1.1. Exploration and Delineation ....................................................................3-5

3.1.1.1.1. Seismic Surveying Operations ..............................................3-5

3.1.1.1.2. Exploration and Delineation Drilling....................................3-7

3.1.1.2. Development and Production...................................................................3-8

3.1.1.2.1. Development and Production Drilling ..................................3-8

3.1.1.2.2. Infrastructure Presence........................................................3-10

3.1.1.2.2.1. Anchoring ......................................................3-10

3.1.1.2.2.2. Offshore Production Systems ........................3-10

3.1.1.2.2.3. Space-Use Requirements ...............................3-11

3.1.1.2.2.4. Aesthetic Quality ...........................................3-12

3.1.1.2.2.5. Workovers and Abandonments......................3-12

3.1.1.3. Major Sources of Oil Inputs in the Gulf of Mexico ...............................3-13

3.1.1.4. Offshore Transport.................................................................................3-16

3.1.1.4.1. Pipelines ..............................................................................3-16

3.1.1.4.2. Barges..................................................................................3-17

3.1.1.4.3. Oil Tankers..........................................................................3-18

3.1.1.4.4. Service Vessels....................................................................3-18

3.1.1.4.5. Helicopters ..........................................................................3-19

3.1.1.5. Operational Wastes and Discharges.......................................................3-19

3.1.1.6. Safety Issues...........................................................................................3-22

3.1.1.6.1. Hydrogen Sulfide and Sulfurous Petroleum........................3-22

3.1.1.6.2. Shallow Hazards..................................................................3-23

3.1.1.6.3. New and Unusual Technology ............................................3-24

3.1.1.7. Decommissioning and Removal Operations..........................................3-24

3.1.2. Coastal Impact-Producing Factors and Scenario.....................................................3-26

3.1.2.1. Service Bases .........................................................................................3-27

3.1.2.2. Gas Processing Plants ............................................................................3-29

3.1.2.3. Coastal Pipelines ....................................................................................3-30

3.1.2.4. Disposal Facilities for Offshore Operations...........................................3-30

3.2. Impact-Producing Factors and Scenario—Accidental Events ...............................................3-31

3.2.1. Oil Spills..................................................................................................................3-31

3.2.1.1. Risk Analysis for Offshore Spills 1,000 bbl ........................................3-33

3.2.1.2. Risk Analysis for Offshore Spills <1,000 bbl ........................................3-36

3.2.1.3. Risk Analysis for Coastal Spills.............................................................3-36

3.2.1.4. Risk Analysis by Resource.....................................................................3-37
Table of Contents xvii

3.2.1.5. Spill Response........................................................................................3-37

3.2.1.5.1. BOEMRE Spill-Response Requirements and 

Initiatives.............................................................................3-37

3.2.1.5.2. Offshore Response and Cleanup Technology .....................3-39

3.2.1.5.3. Oil-Spill-Response Assumptions Used in the Analysis 

of a Most Likely Spill 1,000 bbl Incident Related to 

the Proposed Action ............................................................3-43

3.2.1.5.4. Onshore Response and Cleanup..........................................3-43

3.2.2. Losses of Well Control............................................................................................3-45

3.2.3. Pipeline Failures......................................................................................................3-52

3.2.4. Vessel Collisions.....................................................................................................3-52

3.2.5. Chemical and Drilling-Fluid Spills .........................................................................3-53

3.3. Cumulative Activities Scenario .............................................................................................3-54

3.3.1. OCS Program ..........................................................................................................3-56

3.3.2. State Oil and Gas Activity.......................................................................................3-56

3.3.3. Other Major Factors Influencing Offshore Environments ......................................3-59

3.3.4. Other Major Factors Influencing Coastal Environments.........................................3-67

3.3.5. Natural Events or Processes ....................................................................................3-75

3.3.5.1. Hurricanes ..............................................................................................3-75

3.3.5.2. Currents as Transport Agents.................................................................3-75

4. DESCRIPTION OF THE ENVIRONMENT AND IMPACT ANALYSIS ........................................4-3

4.1. Proposed Central Planning Area Lease Sale 216/222..............................................................4-3

4.1.1. Alternative A—The Proposed Action .......................................................................4-6

4.1.1.1. Air Quality ...............................................................................................4-6

4.1.1.1.1. Description of the Affected Environment .............................4-6

4.1.1.1.2. Impacts of Routine Events ....................................................4-9

4.1.1.1.3. Impacts of Accidental Events..............................................4-13

4.1.1.1.4. Cumulative Impacts.............................................................4-16

4.1.1.2. Water Quality.........................................................................................4-19

4.1.1.2.1. Coastal Waters.....................................................................4-20

4.1.1.2.1.1. Description of the Affected Environment......4-20

4.1.1.2.1.2. Impacts of Routine Events.............................4-25

4.1.1.2.1.3. Impacts of Accidental Events ........................4-26

4.1.1.2.1.4. Cumulative Impacts .......................................4-28

4.1.1.2.2. Offshore Waters ..................................................................4-30

4.1.1.2.2.1. Description of the Affected Environment......4-30

4.1.1.2.2.2. Impacts of Routine Events.............................4-35

4.1.1.2.2.3. Impacts of Accidental Events ........................4-38

4.1.1.2.2.4. Cumulative Impacts .......................................4-41

4.1.1.3. Coastal Barrier Beaches and Associated Dunes.....................................4-43

4.1.1.3.1. Description of the Affected Environment ...........................4-44

4.1.1.3.2. Impacts of Routine Events ..................................................4-49

4.1.1.3.3. Impacts of Accidental Events..............................................4-51

4.1.1.3.4. Cumulative Impacts.............................................................4-54

4.1.1.4. Wetlands.................................................................................................4-60

4.1.1.4.1. Description of the Affected Environment ...........................4-60

4.1.1.4.2. Impacts of Routine Events ..................................................4-65

4.1.1.4.3. Impacts of Accidental Events..............................................4-70

4.1.1.4.4. Cumulative Impacts.............................................................4-74
xviii Central Planning Area Supplemental EIS

4.1.1.5. Seagrass Communities ...........................................................................4-79

4.1.1.5.1. Description of the Affected Environment ...........................4-80

4.1.1.5.2. Impacts of Routine Events ..................................................4-82

4.1.1.5.3. Impacts of Accidental Events..............................................4-84

4.1.1.5.4. Cumulative Impacts.............................................................4-86

4.1.1.6. Live Bottoms..........................................................................................4-87

4.1.1.6.1. Live Bottoms (Pinnacle Trend) ...........................................4-87

4.1.1.6.1.1. Description of the Affected Environment......4-88

4.1.1.6.1.2. Impacts of Routine Events.............................4-92

4.1.1.6.1.3. Impacts of Accidental Events ........................4-99

4.1.1.6.1.4. Cumulative Impacts .....................................4-109

4.1.1.6.2. Live Bottoms (Low Relief) ...............................................4-113

4.1.1.6.2.1. Description of the Affected Environment....4-113

4.1.1.6.2.2. Impacts of Routine Events...........................4-117

4.1.1.6.2.3. Impacts of Accidental Events ......................4-124

4.1.1.6.2.4. Cumulative Impacts .....................................4-133

4.1.1.7. Topographic Features...........................................................................4-137

4.1.1.7.1. Description of the Affected Environment .........................4-138

4.1.1.7.2. Impacts of Routine Events ................................................4-146

4.1.1.7.3. Impacts of Accidental Events............................................4-151

4.1.1.7.4. Cumulative Impacts...........................................................4-160

4.1.1.8. Sargassum ............................................................................................4-163

4.1.1.8.1. Description of the Affected Environment .........................4-163

4.1.1.8.2. Impacts of Routine Events ................................................4-166

4.1.1.8.3. Impacts of Accidental Events............................................4-167

4.1.1.8.4. Cumulative Impacts...........................................................4-169

4.1.1.9. Chemosynthetic Deepwater Benthic Communities..............................4-171

4.1.1.9.1. Description of the Affected Environment .........................4-172

4.1.1.9.2. Impacts of Routine Events ................................................4-180

4.1.1.9.3. Impacts of Accidental Events............................................4-181

4.1.1.9.4. Cumulative Impacts...........................................................4-183

4.1.1.10. Nonchemosynthetic Deepwater Benthic Communities........................4-186

4.1.1.10.1. Description of the Affected Environment .........................4-186

4.1.1.10.2. Impacts of Routine Events ................................................4-188

4.1.1.10.3. Impacts of Accidental Events............................................4-189

4.1.1.10.4. Cumulative Impacts...........................................................4-191

4.1.1.11. Marine Mammals .................................................................................4-194

4.1.1.11.1. Description of the Affected Environment .........................4-194

4.1.1.11.2. Impacts of Routine Events ................................................4-197

4.1.1.11.3. Impacts of Accidental Events............................................4-200

4.1.1.11.4. Cumulative Impacts...........................................................4-202

4.1.1.12. Sea Turtles............................................................................................4-204

4.1.1.12.1. Description of the Affected Environment .........................4-204

4.1.1.12.2. Impacts of Routine Events ................................................4-208

4.1.1.12.3. Impacts of Accidental Events............................................4-210

4.1.1.12.4. Cumulative Impacts...........................................................4-211

4.1.1.13. Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach 

Mice .....................................................................................................4-213

4.1.1.13.1. Description of the Affected Environment .........................4-213

4.1.1.13.2. Impacts of Routine Events ................................................4-216
Table of Contents xix

4.1.1.13.3. Impacts of Accidental Events............................................4-216

4.1.1.13.4. Cumulative Impacts...........................................................4-217

4.1.1.14. Coastal and Marine Birds.....................................................................4-219

4.1.1.14.1. Description of the Affected Environment .........................4-219

4.1.1.14.2. Impacts of Routine Events ................................................4-225

4.1.1.14.3. Impacts of Accidental Events............................................4-229

4.1.1.14.4. Cumulative Impacts...........................................................4-234

4.1.1.15. Gulf Sturgeon.......................................................................................4-242

4.1.1.15.1. Description of the Affected Environment .........................4-243

4.1.1.15.2. Impacts of Routine Events ................................................4-247

4.1.1.15.3. Impacts of Accidental Events............................................4-249

4.1.1.15.4. Cumulative Impacts...........................................................4-254

4.1.1.16. Fish Resources and Essential Fish Habitat...........................................4-259

4.1.1.16.1. Description of the Affected Environment .........................4-260

4.1.1.16.2. Impacts of Routine Events ................................................4-263

4.1.1.16.3. Impacts of Accidental Events............................................4-265

4.1.1.16.4. Cumulative Impacts...........................................................4-268

4.1.1.17. Commercial Fishing.............................................................................4-271

4.1.1.17.1. Description of the Affected Environment .........................4-271

4.1.1.17.2. Impacts of Routine Events ................................................4-275

4.1.1.17.3. Impacts of Accidental Events............................................4-277

4.1.1.17.4. Cumulative Impacts...........................................................4-279

4.1.1.18. Recreational Fishing.............................................................................4-282

4.1.1.18.1. Description of the Affected Environment .........................4-282

4.1.1.18.2. Impacts of Routine Events ................................................4-285

4.1.1.18.3. Impacts of Accidental Events............................................4-286

4.1.1.18.4. Cumulative Impacts...........................................................4-288

4.1.1.19. Recreational Resources ........................................................................4-289

4.1.1.19.1. Description of the Affected Environment .........................4-290

4.1.1.19.2. Impacts of Routine Events ................................................4-294

4.1.1.19.3. Impacts of Accidental Events............................................4-297

4.1.1.19.4. Cumulative Impacts...........................................................4-299

4.1.1.20. Archaeological Resources....................................................................4-301

4.1.1.20.1. Historic..............................................................................4-301

4.1.1.20.1.1. Description of the Affected Environment....4-301

4.1.1.20.1.2. Impacts of Routine Events...........................4-303

4.1.1.20.1.3. Impacts of Accidental Events ......................4-306

4.1.1.20.1.4. Cumulative Impacts .....................................4-307

4.1.1.20.2. Prehistoric..........................................................................4-310

4.1.1.20.2.1. Description of the Affected Environment....4-310

4.1.1.20.2.2. Impacts of Routine Events...........................4-311

4.1.1.20.2.3. Impacts of Accidental Events ......................4-313

4.1.1.20.2.4. Cumulative Impacts .....................................4-313

4.1.1.21. Human Resources and Land Use .........................................................4-315

4.1.1.21.1. Land Use and Coastal Infrastructure .................................4-315

4.1.1.21.1.1. Description of the Affected Environment....4-316

4.1.1.21.1.2. Impacts of Routine Events...........................4-318

4.1.1.21.1.3. Impacts of Accidental Events ......................4-321

4.1.1.21.1.4. Cumulative Impacts .....................................4-323
xx Central Planning Area Supplemental EIS

4.1.1.21.2. Demographics....................................................................4-325

4.1.1.21.2.1. Description of the Affected Environment....4-326

4.1.1.21.2.2. Impacts of Routine Events...........................4-327

4.1.1.21.2.3. Impacts of Accidental Events ......................4-328

4.1.1.21.2.4. Cumulative Impacts .....................................4-329

4.1.1.21.3. Economic Factors..............................................................4-330

4.1.1.21.3.1. Description of the Affected Environment....4-330

4.1.1.21.3.2. Impacts of Routine Events...........................4-334

4.1.1.21.3.3. Impacts of Accidental Events ......................4-335

4.1.1.21.3.4. Cumulative Impacts .....................................4-336

4.1.1.21.4. Environmental Justice .......................................................4-337

4.1.1.21.4.1. Description of the Affected Environment....4-338

4.1.1.21.4.2. Impacts of Routine Events...........................4-341

4.1.1.21.4.3. Impacts of Accidental Events ......................4-344

4.1.1.21.4.4. Cumulative Impacts .....................................4-349

4.1.1.22. Additional Resources Considered due to the Deepwater Horizon 

Event ....................................................................................................4-355

4.1.1.22.1. Soft Bottoms......................................................................4-355

4.1.1.22.1.1. Description of the Affected Environment....4-355

4.1.1.22.1.2. Impacts of Routine Events...........................4-364

4.1.1.22.1.3. Impacts of Accidental Events ......................4-371

4.1.1.22.1.4. Cumulative Impacts .....................................4-378

4.1.1.22.2. Diamondback Terrapins ....................................................4-382

4.1.1.22.2.1. Description of the Affected Environment....4-382

4.1.1.22.2.2. Impacts of Routine Events...........................4-383

4.1.1.22.2.3. Impacts of Accidental Events ......................4-383

4.1.1.22.2.4. Cumulative Impacts .....................................4-384

4.1.2. Alternative B—The Proposed Action Excluding the Unleased Blocks Near 

Biologically Sensitive Topographic Features........................................................4-385

4.1.3. Alternative C—The Proposed Action Excluding Unleased Blocks within 

15 Miles of the Baldwin County, Alabama, Coast................................................4-387

4.1.4. Alternative D—No Action ....................................................................................4-388

4.2. Unavoidable Adverse Impacts of the Proposed Action .......................................................4-392

4.3. Irreversible and Irretrievable Commitment of Resources....................................................4-394

4.4. Relationship between the Short-term Use of Man’s Environment and the Maintenance 

and Enhancement of Long-term Productivity......................................................................4-395

5. CONSULTATION AND COORDINATION .....................................................................................5-3

5.1. Development of the Proposed Action ......................................................................................5-3

5.2. Notice of Preparation of the Supplemental EIS .......................................................................5-3

5.3. Development of the Draft Supplemental EIS...........................................................................5-3

5.3.1. Summary of Scoping Comments...............................................................................5-4

5.3.2. Summary of Written Comments Received in Response to the Notice of Intent .......5-4

5.3.3. Cooperating Agency..................................................................................................5-4
Table of Contents xxi

5.4. Distribution of the Draft Supplemental EIS for Review and Comment ..................................5-5

5.5. Public Hearings........................................................................................................................5-7

5.6. Coastal Zone Management Act................................................................................................5-7

5.7. Endangered Species Act...........................................................................................................5-8

5.8. Magnuson-Stevens Fishery Conservation and Management Act ............................................5-8

5.9. National Historic Preservation Act ..........................................................................................5-9

6. REFERENCES CITED........................................................................................................................6-3

7. PREPARERS .......................................................................................................................................7-3

8. GLOSSARY ........................................................................................................................................8-3

APPENDICES 

Appendix A Figures and Tables ...................................................................................................A-3

Appendix B Catastrophic Spill Event Analysis............................................................................ B-3

Appendix C BOEMRE-OSRA Catastrophic Run ........................................................................ C-3

Appendix D Deepwater Horizon Event Chronology....................................................................D-3

Appendix E Recent Publications of the Environmental Studies Program, Gulf of Mexico 

OCS Region, 2006—Present.................................................................................... E-3

Appendix F Agency-Funded Hurricane Research and Studies .................................................... F-3

KEYWORD INDEX.....................................................................................................................Keyword-3 
List of Figures xxiii

LIST OF FIGURES 

Page 

Figure 1-1. Gulf of Mexico Outer Continental Shelf Planning Areas, Proposed Lease Sale Area, 

and Locations of Major Cities..............................................................................................A-3

Figure 1-2. Location of the Macondo Well in the Gulf of Mexico’s Central Planning Area. ................A-3

Figure 2-1. Location of Proposed Stipulations and Deferrals.................................................................A-4

Figure 2-2. Economic Impact Areas in the Gulf of Mexico. ..................................................................A-5

Figure 2-3. Military Warning Areas and Eglin Water Test Areas Located in the Gulf of Mexico. .......A-6

Figure 3-1. Offshore Subareas in the Gulf of Mexico. ...........................................................................A-7

Figure 3-2. Pipelines Transitioning from Federal OCS and Louisiana State Waters. ............................A-8

Figure 3-3. Air Quality Jurisdiction........................................................................................................A-8

Figure 3-4. OCS-Related Service Bases in the Gulf of Mexico. ............................................................A-9

Figure 3-5. Major Ports and Domestic Waterways in the Gulf of Mexico...........................................A-10

Figure 3-6. Oil-Spill Events (2008) in the Central Planning Area (Dickey, personal 

communication, 2010). ......................................................................................................A-11

Figure 4-1. Status of Ozone Attainment in Coastal Counties and Parishes of the Central and 

Western Planning Areas (USEPA, 2011)...........................................................................A-12

Figure 4-2. Coastal and Marine Waters of the Gulf of Mexico with Selected Rivers and Water 

Depths. ...............................................................................................................................A-12

Figure 4-3. Seagrass Locations of the Northern Gulf of Mexico..........................................................A-13

Figure 4-4. Live Bottoms (Low Relief and Pinnacle Trend) in the Central and Eastern Planning 

Areas. .................................................................................................................................A-14

Figure 4-5. Perspective Sketch of the Submerged Landscape of a Pinnacle Province as 

Visualized from Sidescan Sonar and Remotely Operated Vehicle Information 

(Brooks and Giammona, 1990)..........................................................................................A-15

Figure 4-6. Sketch of a Submerged Ridge (Brooks and Giammona, 1990). ........................................A-16

Figure 4-7. Location of the 36 Fathom Ridge within the Alabama Alps Formation (A & B) 

(Gardner et al., 2002) and Oblique View of the 36 Fathom Ridge within the 

Alabama Alps (C) (Weaver et al., 2002)............................................................................A-17

Figure 4-8. Location of Roughtongue Reef (A & B) (Gardner et al., 2002) and Oblique View of 

Roughtongue Reef (C) (Weaver et al., 2002). ...................................................................A-18

Figure 4-9. Location of Some Mapped Low-Relief, Hard-Bottom Areas and Pinnacles on the 

Alabama-Florida Continental Shelf (Schroeder et al., 1988).............................................A-19

Figure 4-10. Block-Like, Hard-Bottom Substrate North of the Head of De Soto Canyon (Shipp 

and Hopkins, 1978)............................................................................................................A-20

Figure 4-11. Location of Topographic Features in the Gulf of Mexico. ................................................A-21

Figure 4-12. Location of Known Chemosynthetic Communities in the Gulf of Mexico. ......................A-22

Figure 4-13. Summary of Sea Turtles Collected by Date Obtained from the Consolidated 

Numbers of Collected Fish and Wildlife That Have Been Reported to the Unified 

Area Command from the U.S. Fish and Wildlife Service, National Oceanic and 

Atmospheric Administration, Incident Area Commands, Rehabilitation Centers, and 
xxiv Central Planning Area Supplemental EIS

Other Authorized Sources Operating within the Deepwater Horizon/BP Incident 

Impact Area through November 2, 2010............................................................................A-23

Figure 4-14. Summary of Avian Species Collected by Date Obtained from the U.S. Fish and

Wildlife Service (FWS) as Part of the NRDA Process through November 30, 2010........A-24

Figure 4-15. Locations of Oil- and Gas-Related Infrastructure and the Distribution of LowIncome Residents across Counties and Parishes in Texas and Louisiana based on 

U.S. Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in 

preparation). .......................................................................................................................A-25

Figure 4-16. Locations of Oil- and Gas-Related Infrastructure and the Distribution of LowIncome Residents across Counties in Mississippi, Alabama, and Florida based on 

U.S. Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in 

preparation). .......................................................................................................................A-26

Figure 4-17. Locations of Oil- and Gas-Related Infrastructure and the Distribution of Minority 

Residents across Counties and Parishes in Texas and Louisiana based on U.S. 

Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in preparation). .....A-27

Figure 4-18. Locations of Oil- and Gas-Related Infrastructure and the Distribution of Minority 

Residents across Counties in Mississippi, Alabama, and Florida based on U.S. 

Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in preparation). .....A-28

Figure 4-19. Location of All Deepwater Horizon Waste Disposal Sites (USDOC, NOAA, 2011; 

USEPA and British Petroleum, 2010; British Petroleum, 2011a and 2011b)....................A-29

Figure 4-20. Distribution of the Gulf Coast Claims Facility’s Claimants and the Average Amount 

Paid to Each Claimant across Gulf of Mexico Counties and Parishes (Gulf Coast 

Claims Facility, 2011)........................................................................................................A-30

Figure C-1. Location of Five Hypothetical Oil-Spill Launch Points for OSRA within the Study 

Area......................................................................................................................................C-8

Figure C-2. Locations of Parishes, Counties, and Coastlines Examined in the Special OSRA 

Run Conducted in Order to Estimate the Impacts of a Possible Future Catastrophic 

Spill......................................................................................................................................C-8

Figure C-3. Estimated Square Area of Launch Point One (LP 1) for 3, 10, 30, and 120 Days in 

Winter, Spring, Summer, and Fall. ......................................................................................C-9

Figure C-4. Estimated Square Area of Launch Point Two (LP 2) for 3, 10, 30, and 120 Days in 

Winter, Spring, Summer, and Fall. ....................................................................................C-10

Figure C-5. Estimated Square Area of Launch Point Three (LP 3) for 3, 10, 30, and 120 Days in 

Winter, Spring, Summer, and Fall. ....................................................................................C-11

Figure C-6. Estimated Square Area of Launch Point Four (LP 4) for 3, 10, 30, and 120 Days in 

Winter, Spring, Summer, and Fall. ....................................................................................C-12

Figure C-7. Estimated Square Area of Launch Point Five (LP 5) for 3, 10, 30, and 120 Days in 

Winter, Spring, Summer, and Fall. ....................................................................................C-13

Figure D-1. Deepwater Drilling Activity, Total Wells Drilling, and Total Rigs Working from 

mid-April to December 2010. ............................................................................................D-30
List of Tables xxv

LIST OF TABLES 

 Page 

Table 1-1. Emergency 30 CFR 250 Subpart D Interim Final Rule Provisions. ..................................A-31

Table 2-1. Presidential and Secretarial Inquiries Resulting from the Deepwater Horizon Event 

and Spill. ............................................................................................................................A-35

Table 3-1. Projected Oil and Gas in the Gulf of Mexico OCS............................................................A-36

Table 3-2. Offshore Scenario Information Related to a Proposed Action in the Central 

Planning Area.....................................................................................................................A-36

Table 3-3. Deepwater Rig Counts, Day Rates, and Annual Drill Rates in the Gulf of Mexico. .........A-37

Table 3-4. Oil Spilled from Pipelines on the Federal OCS, 2002-2009..............................................A-37

Table 3-5. Mean Number and Sizes of Spills Estimated to Occur in OCS Offshore Waters 

from an Accident Related to Activities Supporting the Proposed Action Over a 

40-Year Time Period..........................................................................................................A-37

Table 3-6. Properties and Persistence by Oil Component Group........................................................A-38

Table 3-7. Estimated Number of Spills that Could Happen in Gulf Coastal Waters from an 

Accident Related to Activities Supporting a Proposed Action. .........................................A-39

Table 3-8. Primary Cleanup Options Used during the Deepwater Horizon Response........................A-39

Table 3-9. Pipelines Damaged after 2004-2008 Hurricanes Passing through the WPA and 

CPA....................................................................................................................................A-40

Table 3-10. Causes of Hurricane-Related Pipeline Spills Greater Than 50 Barrels..............................A-40

Table 3-11. Total Producing Wells, Total Oil, and Total Gas Production in the Nine Coastal 

Parishes of Louisiana in 2009. ...........................................................................................A-41

Table 3-12. Designated Ocean Dredged-Material Disposal Sites in the Cumulative Impact Area.......A-42

Table 3-13. Projected OCS Sand Borrowing Needs for Planned Restoration Projects.........................A-44

Table 3-14. Vessel Calls at U.S. Gulf Coast Ports in 2004 and 2009. ..................................................A-44

Table 3-15. Designated Louisiana Service Bases Identified in Applications for Pipelines, 

Exploration, and Development Plans between 2003 and 2008 and Miles of 

Navigation Canal Bordered by Saline, Brackish Water, and Freshwater Wetlands. ........A-45

Table 3-16. Coastal Impact Assistance Program Allocations for all Eligible States ($).......................A-46

Table 3-17. Coastal Impact Assistance Program Grants Status for Gulf of Mexico States ($).............A-46

Table 3-18. Hurricane Landfalls in the Northern Gulf of Mexico from 1995 to 2010.........................A-47

Table 3-19. OCS Facility Damage after the 2004-2008 Hurricanes in the WPA and CPA. .................A-47

Table 4-1. National Ambient Air Quality Standards...........................................................................A-48

Table 4-2. Estimated Abundance of Cetaceans in the Northern Gulf of Mexico Oceanic 

Waters. ...............................................................................................................................A-49

Table 4-3. Sea Turtle Taxa of the Northern Gulf of Mexico...............................................................A-50

Table 4-4. Comparison of Oil Spills by Type, Location, Year, and Volume (in U.S. gallons) 

and Their Relative Impacts to Birds based on Surveys and Modeling. .............................A-51
xxvi Central Planning Area Supplemental EIS

Table 4-5. Relative Oiling Ranks for Various Avian Species Groupings Collected PostDeepwater Horizon Event in the Gulf of Mexico.............................................................A-53

Table 4-6. Birds Collected and Summarized by the U.S. Fish and Wildlife Service PostDeepwater Horizon Event in the Gulf of Mexico.............................................................A-54

Table 4-7. Mississippi Department of Marine Resources: Summary of Fish Kills Observed 

along the Gulf Coast. .........................................................................................................A-58

Table 4-8. Economic Significance of Commercial Fishing in the Gulf of Mexico.............................A-58

Table 4-9. Top Species Caught by Recreational Fishers in the Gulf Coast States..............................A-59

Table 4-10. Percentage of Species Landings that are Ocean Based......................................................A-60

Table 4-11. Recreational Fishing Participation 2009. ...........................................................................A-61

Table 4-12. Angler Trips in the Gulf of Mexico during Certain Months of 2009 and 2010.................A-62

Table 4-13. Angler trips in the Gulf of Mexico by Location and Mode in 2009. .................................A-63

Table 4-14. Economic Impact of Recreational Fishing in the Gulf of Mexico in 2008. .......................A-64

Table 4-15. Fish Species Caught by Recreational Anglers during Certain Months of 2009 and 

2010....................................................................................................................................A-65

Table 4-16. Employment in the Leisure/Hospitality Industry in Selected Geographic Regions...........A-66

Table 4-17. Total Wages Earned by Employees in the Leisure/Hospitality Industry in Selected 

Geographic Regions...........................................................................................................A-67

Table 4-18. Total Tourism Spending in Gulf Coast States....................................................................A-68

Table 4-19. Coastal Travel, Tourism, and Recreation Estimates in 2004. ............................................A-68

Table 4-20. Number of Beaches and Beach Participation in Gulf States..............................................A-68

Table 4-21. Shipwrecks in the Gulf of Mexico Central Planning Area.................................................A-69

Table 4-22. OCS and Non-OCS Program Spill Rates...........................................................................A-70

Table 4-23. Classification of the Gulf Economic Impact Areas............................................................A-71

Table 4-24. Demographic and Employment Baseline Projections for Economic Impact Area 

TX-1...................................................................................................................................A-73

Table 4-25. Demographic and Employment Baseline Projections for Economic Impact Area 

TX-2...................................................................................................................................A-75

Table 4-26. Demographic and Employment Baseline Projections for Economic Impact Area 

TX-3...................................................................................................................................A-77

Table 4-27. Demographic and Employment Baseline Projections for Economic Impact Area 

LA1. ...................................................................................................................................A-79

Table 4-28. Demographic and Employment Baseline Projections for Economic Impact Area 

LA-2...................................................................................................................................A-81

Table 4-29. Demographic and Employment Baseline Projections for Economic Impact Area 

LA-3...................................................................................................................................A-83

Table 4-30. Demographic and Employment Baseline Projections for Economic Impact Area 

LA-4...................................................................................................................................A-85

Table 4-31. Demographic and Employment Baseline Projections for Economic Impact Area 

MS-1. .................................................................................................................................A-87
List of Tables xxvii

Table 4-32. Demographic and Employment Baseline Projections for Economic Impact Area 

AL-1...................................................................................................................................A-89

Table 4-33. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-1....................................................................................................................................A-91

Table 4-34. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-2....................................................................................................................................A-93

Table 4-35. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-3....................................................................................................................................A-95

Table 4-36. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-4....................................................................................................................................A-97

Table 4-37. Baseline Population Projections (in thousands) by Economic Impact Area. .....................A-99

Table 4-38. Baseline Employment Projections (in thousands) by Coastal Subarea............................A-100

Table 4-39. Liquid Waste Collected from the Deepwater Horizon Event. .........................................A-101

Table 4-40. Solid Waste Collected from the Deepwater Horizon Event. ...........................................A-102

Table 4-41. Deepwater Horizon Waste Destination Communities. ....................................................A-103

Table 4-42. Gulf Coast Claims Facility—Deepwater Horizon Claimant Data by State. ....................A-104

Table 5-1. Scoping Comments. .........................................................................................................A-107

Table C-1. Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at 

Launch Point One Will Contact a Certain Parish, County, or Coastline within 120 

Days. ..................................................................................................................................C-14

Table C-2. Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at 

Launch Point Two Will Contact a Certain Parish, County, or Coastline within 120 

Days. ..................................................................................................................................C-15

Table C-3. Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at 

Launch Point Three Will Contact a Certain Parish, County, or Coastline within 120 

Days. ..................................................................................................................................C-16

Table C-4. Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at 

Launch Point Four Will Contact a Certain Parish, County, or Coastline within 120 

Days. ..................................................................................................................................C-17

Table C-5. Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at 

Launch Point Five Will Contact a Certain Parish, County, or Coastline within 120 

Days. ..................................................................................................................................C-18

Table D-1. Largest Marine Blowouts Prior to the Deepwater Horizon Event.....................................D-31

Table D-2. Largest Oil Spills from Tankers.........................................................................................D-31

Table D-3. Personnel, Vessels, Aircraft, and Containment Boom Deployed for Deepwater 

Horizon Spill Response Activity........................................................................................D-32

Table D-4. Cumulative Totals for Oiled and Nonoiled Animals Collected as Part of Deepwater 

Horizon Spill Response Activity........................................................................................D-33
Abbreviations and Acronyms xxix 

ABBREVIATIONS AND ACRONYMS 

C degree Celsius 

F degree Fahrenheit 

2009-2012 Gulf of Mexico OCS Oil and Gas Lease Sales: 2009-2012; 

Supplemental EIS Central Planning Area Sales 208, 213, 216, and 222; 

 Western Planning Area Sales 210, 215, and 218; 

 Final Supplemental Environmental Impact Statement

2D two-dimensional 

3D three-dimensional 

4D four-dimensional 

5-Year Program Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012

ac acre 

ACP Area Contingency Plans 

AL Alabama 

ANPR Advance Notice of Proposed Rulemaking 

APD Application for Permit to Drill 

APE area of potential effect 

API American Petroleum Institute 

ASLM Assistant Secretary of the Interior for Land and Minerals 

BAST best available and safest technology 

bbl barrel 

BBO billion barrels of oil 

Bcf billion cubic feet 

BOEMRE Bureau of Ocean Energy Management, Regulation and Enforcement 

BOP blowout preventer 

B.P. before present 

BP British Petroleum 

BTEX benzene, ethylbenzene, toluene, and xylene 

CAA Clean Air Act of 1970 

CAAA Clean Air Act Amendments of 1990 

CD Consistency Determination 

CDP common-depth-point (seismic surveying) 

CEEDS Complete Economic and Demographic Data Source

CEI Coastal Environments, Inc. 

CEQ Council on Environmental Quality 

CER categorical exclusion review 

CFR Code of Federal Regulations 

CG Coast Guard (also: USCG) 

CH4 methane 

CIAP Coastal Impact Assistance Program 

cm centimeter 

CMP Coastal Management Plans 

CO carbon monoxide 

CO2 carbon dioxide 

COE Corps of Engineers (U.S. Army) 

COF covered offshore facilities 

CPA Central Planning Area 

CPS coastal political subdivisions 

CRS Congressional Research Service 

CSA Continental Shelf Associates 

CWPPRA Coastal Wetlands Protection, Planning & Restoration Act 

CZM Coastal Zone Management 

CZMA Coastal Zone Management Act 
xxx Central Planning Area Supplemental EIS 

dB decibel 

DOCD development operations coordination document 

DOD Department of Defense (U.S.) 

DOE Department of Energy (U.S.) (also: USDOE) 

DOI Department of the Interior (U.S.) (also: USDOI) 

DOT Department of Transportation (U.S.) (also: USDOT) 

DPP development and production plan 

DWH Deepwater Horizon

DWOP deepwater operations plan 

EA environmental assessment 

EEZ Exclusive Economic Zone 

EFH Essential Fish Habitat 

e.g. for example 

Eh oxidation reduction potential 

EIA Economic Impact Area 

EIS environmental impact statement 

EP exploration plan 

EPA Eastern Planning Area 

EPAct Energy Policy Act of 2005 

ERCO Energy Resources Co., Inc. 

ESA Endangered Species Act of 1973 

ESI Environmental Sensitivity Indexes 

ESP Environmental Studies Program 

ESPIS Environmental Studies Program Information System 

et al. and others 

et seq. and the following 

EWTA Eglin Water Test Area 

FAA Federal Aviation Administration 

FEMA Federal Emergency Management Agency 

FERC Federal Energy Regulatory Commission 

FL Florida 

FPSO floating production, storage, and offloading system 

FR Federal Register

ft feet 

FWS Fish and Wildlife Service 

FY fiscal year 

G&G geological and geophysical 

gal gallon 

GAO Government Accountability Office (U.S.) 

GCCF Gulf Coast Claims Facility 

GERG Geochemical and Environmental Research Group 

GIWW Gulf Intracoastal Waterway 

GMAQS Gulf of Mexico Air Quality Study 

GMFMC Gulf of Mexico Fishery Management Council 

GOADS Gulfwide Offshore Activities Data System 

GOM Gulf of Mexico 

GOMESA Gulf of Mexico Energy Security Act of 2006 

GS Geological Survey (also: USGS) 

H2S hydrogen sulfide 

ha hectare 

hr hour 

i.e. specifically 

IATAP Interagency Alternative Technology Assessment Program 

in inch 

ITOPF International Tanker Owners Pollution Federation Limited 
Abbreviations and Acronyms xxxi 

ITS Incidental Take Statement 

JIP Joint Industry Project 

kg kilogram 

km kilometer 

kn knot 

LA Louisiana 

LA Hwy 1 Louisiana Highway 1 

LACPR Louisiana Coastal Protection and Restoration 

lb pound 

LC50 lethal concentration for 50 percent of the test population 

LCA Louisiana Coastal Area 

LMA labor market area 

LMRP lower marine riser package 

LNG liquefied natural gas 

m meter 

MARAD U.S. Department of Transportation Maritime Administration 

MARPOL International Convention for the Prevention of Pollution from Ships 

Mcf thousand cubic feet 

mg milligram 

mg/L milligrams per liter 

mi mile 

ml/L milliliter per liter 

mm millimeter 

MMbbl/d million barrels per day 

MMcf million cubic feet 

MMPA Marine Mammal Protection Act of 1972 

MMS Minerals Management Service 

MOA Memorandum of Agreement 

MODU mobile offshore drilling unit 

MOU Memorandum of Understanding 

mph miles per hour 

MS Mississippi 

Multisale EIS Gulf of Mexico OCS Oil and Gas Lease Sales: 2003-2007; 

 Central Planning Area Sales 185, 190, 194, 198, and 201; 

 Western Planning Area Sales 187, 192, 196, and 200; 

 Final Environmental Impact Statement; Volumes I and II

MWCC Marine Well Containment Company 

N. north 

n.d. no date 

NAAQS National Ambient Air Quality Standards 

NACE National Association of Corrosion Engineers 

NASA National Aeronautics and Space Administration 

NEPA National Environmental Policy Act 

NGMCS Northern Gulf of Mexico Continental Slope Study 

NHPA National Historic Preservation Act 

NMFS National Marine Fisheries Service 

nmi nautical-mile 

NO2 nitrogen dioxide 

NOx nitrogen oxides 

NOA Notice of Availability 

NOAA National Oceanic and Atmospheric Administration 

NOI Notice of Intent to Prepare an EIS 

NOS National Ocean Service 

NPDES National Pollutant and Discharge Elimination System 

NPR Notice of Proposed Rulemaking 
xxxii Central Planning Area Supplemental EIS 

NPS National Park Service 

NRC National Research Council 

NRDA Natural Resource Damage Assessment 

NTL Notice to Lessees and Operators 

NUT new or unusual technology 

O3 ozone 

OBF oil-based fluids 

OBM oil-based muds 

OCD Offshore and Coastal Dispersion Model 

OCS Outer Continental Shelf 

OCSLA Outer Continental Shelf Lands Act 

ODMDS ocean dredged-material disposal sites 

OIG Office of the Inspector General 

OPA Oil Pollution Act of 1990 

OSFR oil-spill financial responsibility 

OSHA Occupational Safety and Health Administration 

OSRA Oil Spill Risk Analysis 

OSRP oil-spill response plans 

OSV offshore supply/service vessels 

P.L. Public Law 

PAH polycyclic aromatic hydrocarbon 

pH potential of hydrogen 

PINC Potential Incident of Noncompliance 

PM particulate matter 

ppb part per billion 

ppm parts per million 

ppt parts per thousand 

PSD Prevention of Significant Deterioration 

psu practical salinity unit 

QOCSR qualified OCS revenues 

ROD Record of Decision 

ROTAC Regional Operations Technology Assessment Committee 

ROV remotely operated vehicle 

RP Recommended Practice 

RPM reasonable and prudent measure 

RRT Regional Response Team 

RTR Rigs-to-Reef 

S. south 

SAV submerged aquatic vegetation 

SBF synthetic-based fluids 

SBM synthetic-based muds 

SCAT Shoreline Cleanup and Assessment Team 

Secretary Secretary of the Interior 

SEMS Safety and Environmental Management System 

SO2 sulphur dioxide 

SOx sulphur oxides 

sp. species 

spp. multiple species 

Stat. Statute 

STOF-THPO Seminole Tribe of Florida-Tribal Historic Preservation Officer 

TA&R Technology Assessment & Research Program 

Tcf trillion cubic feet 

TX Texas 

U.S. United States 

U.S.C. United States Code 
Abbreviations and Acronyms xxxiii 

UIC Unified Incident Command 

USCG U.S. Coast Guard (also: CG) 

USDOC U.S. Department of Commerce 

USDOD U.S. Department of Defense 

USDOE U.S. Department of the Energy (also: DOE) 

USDOI U.S. Department of the Interior (also: DOI) 

USDOT U.S. Department of Transportation 

USEPA U.S. Environmental Protection Agency 

USGS United States Geological Survey (also: GS) 

VOC volatile organic compounds 

VSP vertical seismic profiling 

W. west 

WAF water accommodated fraction 

WBF water-based fluids 

WPA Western Planning Area 

WSF water soluble fraction 

yd yard 

yr year 
CHAPTER 1 

THE PROPOSED ACTION
The Proposed Action 1-3 

1. THE PROPOSED ACTION 

1.1. PURPOSE OF AND NEED FOR THE PROPOSED ACTION

The purpose of the proposed Federal action is to offer for lease certain Outer Continental Shelf (OCS) 

blocks located in the Central Planning Area (CPA) in the Gulf of Mexico (GOM) (Figure 1-1) that may 

contain economically recoverable oil and gas resources. Under the Outer Continental Shelf Oil and Gas 

Leasing Program: 2007-2012 (5-Year Program; USDOI, MMS, 2007a), it was proposed that two GOM 

sales would be held each year—one in the WPA and one in the Central Planning Area (CPA). Proposed 

consolidated Lease Sale 216/222 in the CPA is the last sale in this planning area of the 5-Year Program 

and will provide qualified bidders the opportunity to bid on blocks in the Gulf of Mexico OCS in order to 

explore, develop, and produce oil and natural gas. 

This Supplemental Environmental Impact Statement (EIS) was prepared because of the potential 

changes to baseline conditions of the environmental, socioeconomic, and cultural resources that may have 

occurred as a result of (1) the Deepwater Horizon (DWH) event between April 20 and July 15, 2010 (the 

period when oil flowed from the Macondo well in Mississippi Canyon Block 252 [Figure 1-2]); (2) the 

acute impacts that have been reported or surveyed since that time; and (3) any new information that may 

be available. The environmental resources include sensitive coastal environments, offshore benthic 

resources, marine mammals, sea turtles, coastal and marine birds, endangered and threatened species, and 

fisheries. This Supplemental EIS analyzes the potential impacts of the proposed action on the marine, 

coastal, and human environments. 

The need for the proposed action is to further the orderly development of OCS resources. Oil serves 

as the feedstock for liquid hydrocarbon products; among them gasoline, aviation and diesel fuel, and 

various petrochemicals. Oil from the CPA would help reduce the Nation’s need for oil imports and lessen 

a growing dependence on foreign oil. The United States (U.S.) consumed 18.7 million barrels (bbl) of oil 

per day in 2009 (USDOE, Energy Information Administration, 2010a). Altogether, net imports of crude 

oil and petroleum products (imports minus exports) accounted for 51 percent of our total petroleum 

consumption in 2009. The U.S. crude oil imports stood at 9.0 million bbl per day in 2009. Petroleum 

product imports were 2.7 million bbl per day in 2009. Exports totaled 2.0 million bbl per day in 2009, 

mainly in the form of distillate fuel oil, petroleum coke, and residual fuel oil. Our biggest supplier of 

crude oil and petroleum product imports was Canada (21.2%), with countries in the Persian Gulf being 

the second largest source (17%) in 2009 (USDOE, Energy Information Administration, 2010b). Oil 

produced from the CPA would reduce the environmental risks associated with transoceanic oil tankering 

from sources overseas. 

In 2009, the U.S. consumed approximately 22.8 trillion cubic feet (Tcf) of natural gas from all 

sources (USDOE, Energy Information Administration, 2011a). In 2009, the Gulf Coast States used 

approximately 6.4 Tcf of natural gas (USDOE, Energy Information Administration, 2011a). In 2008, 

11.7 percent of U.S. natural gas resources were imported, mostly from Canada (USDOE, Energy 

Information Administration, 2010c). In 2009, 88 percent of net imports came by pipeline, primarily from 

Canada, and 12 percent came by liquefied natural gas (LNG) tankers carrying gas from five different 

countries (USDOE, Energy Information Administration, 2010d). Natural gas is generally considered to 

be an environmentally preferable alternative to oil, especially when used to generate electricity or for 

residential and industrial heating. Natural gas is an important feedstock for domestic industries engaged 

in the manufacture or formulation of fertilizers, pharmaceuticals, plastics, and packaging. 

The Outer Continental Shelf Lands Act of 1953 (OCSLA), as amended (43 U.S.C. 1331 et seq. 

(2008)), established Federal jurisdiction over submerged lands seaward of State boundaries. Under the 

OCSLA, the Department of the Interior (DOI) is required to manage the leasing, exploration, 

development, and production of oil and gas resources on the Federal OCS. The Secretary of the Interior 

(Secretary) oversees the OCS oil and gas program and is required to balance orderly resource 

development with protection of the human, marine, and coastal environments while simultaneously 

ensuring that the public receives an equitable return for these resources and that free-market competition 

is maintained. The OCSLA empowers the Secretary to grant leases to the highest qualified responsible 

bidder(s) on the basis of sealed competitive bids and to formulate such regulations as necessary to carry 

out the provisions of the Act. The Secretary has designated the Bureau of Ocean Energy Management, 
1-4 Central Planning Area Supplemental EIS 

Regulation and Enforcement (BOEMRE) as the agency responsible for the mineral leasing of submerged 

OCS lands and for the supervision of offshore operations after lease issuance, in accordance with the 

provisions of the OCSLA. 

At the completion of the National Environmental Policy Act (NEPA) process, the Secretary will 

decide if proposed CPA Lease Sale 216/222 will be carried out. In the NEPA implementing regulations 

(40 CFR 1508.28), “tiering” refers to the coverage of general matters in a broader EIS (such as national 

program) with subsequent narrower statements of environmental analyses (such as regional action). 

Tiering is appropriate in this instance as broader program issues have already been subjected to analysis, 

and this Supplemental EIS is more narrowly focused on the site-specific statement or analysis for 

proposed CPA Lease Sale 216/222. This Supplemental EIS tiers from the following EIS’s: the Outer 

Continental Shelf Oil and Gas Leasing Program: 2007-2012, Final Environmental Impact Statement

(5-Year Program EIS; USDOI, MMS, 2007c), which defined the national program; the Gulf of Mexico 

OCS Oil and Gas Lease Sales: 2007-2012; Western Planning Area Sales 204, 207, 210, 215, and 218; 

Central Planning Area Sales 205, 206, 208, 213, 216, and 222, Final Environmental Impact Statement

(Multisale EIS; USDOI, MMS, 2007b), which defined the 5-Year Program in the GOM; and the Gulf of 

Mexico OCS Oil and Gas Lease Sales: 2009-2012; Central Planning Area Sales 208, 213, 216, and 222; 

Western Planning Area Sales 210, 215, and 218, Final Supplemental Environmental Impact Statement

(2009-2012 Supplemental EIS; USDOI, MMS, 2008a), which was required after passage of the Gulf of 

Mexico Energy Security Act of 2006 (GOMESA). 

1.2. DESCRIPTION OF THE PROPOSED ACTION

The proposed action is BOEMRE’s holding of the two remaining oil and gas lease sales in the CPA, 

consolidated as Lease Sale 216/222, as scheduled under the current 5-Year Program. Federal regulations 

allow for several related or similar proposals to be analyzed in one EIS (40 CFR 1502.4). The BOEMRE 

has decided to prepare a Supplemental EIS for the remaining CPA lease sales in the 5-Year Program. 

Proposed CPA Lease Sale 216/222 

Proposed CPA Lease Sale 216/222 is scheduled to be held in 2012. The CPA sale area encompasses 

about 63 million acres (ac) of the CPA’s 66.3 million ac located 3 nautical miles (nmi) (3.4 miles [mi]; 

5.5 kilometers [km]) offshore Louisiana, Mississippi, and Alabama and extends seaward to the limits of 

the Exclusive Economic Zone (EEZ) in water depths up to 3,458 meters (m) (11,345 feet [ft]) 

(Figure 1-1). This proposed CPA lease sale would offer for lease all unleased blocks in the CPA for oil 

and gas operations, with the following exceptions: 

(1) blocks directly south of Florida and within 100 mi (161 km) of the Florida coast 

(north of the easternmost portion of the proposed CPA lease sale area as shown on 

Figure 1-1); and 

(2) blocks that are beyond the U.S. Exclusive Economic Zone in the area known as the 

northern portion of the Eastern Gap. 

The estimated amount of resources projected to be developed as a result of this proposed CPA lease 

sale is 0.801-1.624 billion barrels of oil (BBO) and 3.332-6.560 Tcf of gas. The proposed CPA lease sale 

includes proposed lease stipulations designed to reduce environmental risks and is discussed in 

Chapter 2.3. 

1.3. REGULATORY FRAMEWORK

Federal laws mandate the OCS leasing program (i.e., Outer Continental Shelf Lands Act) and the 

environmental review process (i.e., NEPA). Several Federal statutes and their implementing regulations 

establish specific consultation and coordination processes with Federal, State, and local agencies (i.e., 

Coastal Zone Management Act [CZMA], National Historic Preservation Act [NHPA], Endangered 

Species Act [ESA], the Magnuson-Stevens Fishery Conservation and Management Act, and the Marine 

Mammal Protection Act [MMPA]). In addition, the OCS leasing process and all activities and operations 
The Proposed Action 1-5 

on the OCS must comply with other Federal, State, and local laws and regulations. On December 20, 

2006, President Bush signed into law GOMESA, which made available two new areas in the GOM for 

leasing, placed a moratorium on other areas in the GOM, and increased the distribution of offshore oil and 

gas revenues to coastal States. The following major, applicable Federal laws and regulations are 

summarized in OCS Regulatory Framework for the Gulf of Mexico Region (Matthews and Cameron, 

2010): 

Regulation or Law Citation 

Outer Continental Shelf Lands Act 43 U.S.C. 1331 et seq.

National Environmental Policy Act of 1969 42 U.S.C. 4321-4347 

40 CFR 1500-1508 

Coastal Zone Management Act of 1972 16 U.S.C. 1451 et seq., 

15 CFR 930.76

Endangered Species Act of 1973 16 U.S.C. 1631 et seq. 

Magnuson-Stevens Fishery Conservation and Management Act 16 U.S.C. 1251 et seq. 

Essential Fish Habitat 

1996 reauthorization of the 

Magnuson-Stevens Fishery 

Conservation and Management 

Act 

Essential Fish Habitat Consultation 50 CFR 600.905-930 

Marine Mammal Protection Act 16 U.S.C. 1361 et seq. 

Clean Air Act 42 U.S.C. 7401 et seq., 

40 CFR 55 

Clean Water Act Amendment to Federal Water 

Pollution Control Act of 1972 

Clean Water Act—National Pollutant Discharge Elimination System Section 316(b) of the Clean Water 

Act 

Harmful Algal Bloom and Hypoxia Research and Control Act P.L. 105-383 

Oil Pollution Act of 1990 33 U.S.C. 2701 et seq., 

Executive Order 12777 

Comprehensive Environmental Response, Compensation, and Liability Act 

of 1980 42 U.S.C. 9601 et seq. 

Resource Conservation and Recovery Act 42 U.S.C. 6901 et seq. 

Marine Plastic Pollution Research and Control Act 33 U.S.C. 1901 et seq. 

National Fishing Enhancement Act of 1984 33 U.S.C. 2601 et seq. 

Fishermen’s Contingency Fund 43 U.S.C. 1841-1846 

Ports and Waterways Safety Act of 1972 33 U.S.C. 1223 et seq. 

Marine and Estuarine Protection Acts 33 U.S.C. 1401 et seq. 

Marine Protection, Research, and Sanctuaries Act of 1972 P.L. 92-532 

National Estuarine Research Reserves 16 U.S.C. § 1461, Section 315 

National Estuary Program P.L. 104-4 

Coastal Barrier Resources Act 16 U.S.C. 3501 et seq. 

National Historic Preservation Act 16 U.S.C. 470 et seq. 

Rivers and Harbors Act of 1899 33 U.S.C. 401 et seq. 

Occupational Safety and Health Act of 1970 29 U.S.C. 651-678q 

Energy Policy Act of 2005 P.L. 109-58 

Gulf of Mexico Energy Security Act of 2006 P.L. 109-432 
1-6 Central Planning Area Supplemental EIS 

Marine Debris Research, Prevention, and Reduction Act P.L. 109-449 

American Indian Religious Freedom Act of 1978 P.L. 95-341, 

42 U.S.C. 1996 and 1996a 

Federal Aviation Act of 1958 

Federal Aviation Act of 1958 was 

repealed by the recodification of 

49 U.S.C. (P.L. 103-272) 

Migratory Bird Treaty Act of 1918 16 U.S.C. 703-712; Ch. 128; 

07/13/1918; 40 Stat. 755 

Submerged Lands Act of 1953 43 U.S.C. §§ 1301-1315 (2002) 

49 U.S.C. 44718: Structures Interfering with Air Commerce 49 U.S.C. 44718 

U.S. Coast Guard Regulations 

Marking of Obstructions 

Executive Order 11988: Floodplain Management 42 FR 26951 (1977), amended by 

Executive Order 12148 (7/20/79) 

Executive Order 11990: Protection of Wetlands 42 FR 26961 (1977), amended by 

Executive Order 12608 (9/9/87) 

Executive Order 12114: Environmental Effects Abroad 44 FR 1957 (1979) 

Executive Order 12898: Environmental Justice 59 FR 5517 (1994) 

Executive Order 13007: Indian Sacred Sites 61FR26771-26772(1996) 

Executive Order 13089: Coral Reef Protection 63FR32701-32703(1998) 

Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments 65 FR 67249-67252 (2000) 

Executive Order 13186: Responsibilities of Federal Agencies to Protect 

Migratory Birds 66 FR 3853 (2001) 

1.3.1. Rule Changes following the Deepwater Horizon Event 

In the aftermath of the DWH event on April 20, 2010, President Obama directed the Secretary of the 

Interior (“Secretary”) to report within 30 days on what, if any, additional precautions, technologies, and 

procedures should be required on the OCS to improve the safety of oil and gas development on the OCS. 

In response to this directive, the Department of the Interior (DOI) prepared the report, Increased Safety 

Measures for Energy Development on the Outer Continental Shelf. The “30-Day Report” or “Safety 

Measures Report” was delivered to the Secretary and made public on May 27, 2010 (USDOI, 2010). 

On a separate track and beginning long before the DWH event, this Agency published an Advanced 

Notice of Proposed Rulemaking (ANPR) (Federal Register, 2006a) on May 22, 2006, to solicit ideas for 

adoption of the American Petroleum Institute (API) Recommended Practice (RP) 75 containing 

recommended practice for development of a Safety and Environmental Management System (SEMS) for 

OCS operations and facilities (API, 2004). This Agency published a Notice of Proposed Rulemaking 

(NPR) on June 17, 2009 (Federal Register, 2009a), based on comments received on the 2006 ANPR. The 

Agency was in the process of finalizing the rule when the DWH event took place. The final rule (Federal 

Register, 2010a) was published on October 15, 2010, requiring full implementation of a SEMS program 

as recommended by API RP 75. 

On May 28, 2010, the Secretary directed this Agency to exercise its authority under the OCSLA to 

suspend certain drilling activities in water depths of 500 ft (152 m) and deeper for a period of up to 

6 months. The May 28th suspension was intended to provide sufficient time to (1) ensure that drilling 

operations similar to conditions that apply to the DWH event operate in a safe manner when drilling 

resumes, (2) account for the expected timeline for killing the Macondo well so that the extensive spill 

response resources directed toward the spill would start to become available for other spill events, and (3) 

provide adequate time to obtain input from ongoing investigations of the accident and to develop and 

promulgate regulations that address issues described in the Safety Measures Report. 

On June 22, 2010, the United States Federal District Court in the Eastern District of Louisiana 

enjoined enforcement of the May 28th suspension. On July 12, 2010, the Secretary issued a decision 
The Proposed Action 1-7 

memorandum rescinding the May 28th suspension and imposing a second suspension of certain drilling 

operations in deep water that was originally announced to be effective until November 30, 2010. In 

particular, the July 12th suspension applied, with certain exceptions, to the drilling of wells using a subsea 

blowout preventer (BOP) or a surface BOP on a floating facility. Three primary issues supported this 

temporary pause in drilling operations. The suspension (1) allowed time for BOEMRE to implement 

appropriate workplace and drilling safety measures; (2) was intended to provide BOEMRE, the industry, 

and others time to develop strategies and methods of containment of wild wells in deep water; and (3) was 

necessary to ensure that appropriate and sufficient response resources would be available in the event of 

another major oil spill. 

The BOEMRE reduced the duration of the July 12, 2010, suspension insofar as it applies to 

deepwater development drilling operations using a subsea BOP or a surface BOP on a floating facility and 

wrote an environmental assessment with a Finding of No Significant Impact (USDOI, BOEMRE, 2010a). 

On October 12, 2010, the July 12 suspension was lifted in its entirety. After October 12, 2010, BOEMRE 

began to review and potentially approve pending and future applications for permits to drill deepwater 

development wells using a subsea BOP or a surface BOP on a floating facility. Operators are still 

required to complete the documentation required to certify to BOEMRE that they are ready to re-initiate 

their projects. 

The BOEMRE has addressed the three issues posed in the July 12, 2010, activity suspension through 

multiple venues. The BOEMRE has collected a large amount of information through public hearings and 

other meetings held specifically on the DWH event and through public comments on rulemaking efforts. 

The information collection, review, and analysis efforts resulted in new regulations, planned Notices to 

Lessees and Operators (NTL’s) and BOEMRE procedures that address drilling safety, oil-spill response, 

and enhanced inspection procedures. These regulations, NTL’s, and procedures were not in effect at the 

time of the DWH event, but they will apply to all future applicable drilling activities. The regulations, 

NTL’s, and procedures include the following: 

 NTL 2010-N05, “Increased Safety Measures for Energy Development,” effective 

June 8, 2010 (“Safety NTL”). 

 NTL 2010-N06, “Information Requirements for Exploration Plans, Development and 

Production Plans, and Development Operations Coordination Documents on the 

OCS,” effective June 18, 2010 (“Plans NTL”). 

 NTL 2010-N10, “Statement of Compliance with Applicable Regulations and 

Evaluation of Information Demonstrating Adequate Spill Response and Well 

Containment Resources,” effective November 8, 2010 (“Certification NTL”). 

 The Drilling Safety Rule, Interim Final Rule to Enhance Safety Measures for Energy 

Development on the Outer Continental Shelf (“Drilling Safety Rule”) (Federal 

Register, 2010b). This rule strengthens requirements for safety equipment, well 

control systems, and blowout prevention practices on offshore oil and gas operations. 

 The Workplace Safety Rule on Safety and Environmental Management Systems 

(“SEMS Rule”) (Federal Register, 2010a). This rule requires operators to develop 

and implement a comprehensive SEMS for identifying, addressing, and managing 

operational safety hazards and impacts; promoting both human safety and 

environmental protection; and improving workplace safety by reducing the risk of 

human error. 

 Enhanced Inspection Procedures. The BOEMRE is developing plans and schedules 

for conducting safety inspections of all deepwater drilling facilities. These plans and 

schedules will be implemented upon the recommencement of deepwater drilling 

operations. 
1-8 Central Planning Area Supplemental EIS 

Drilling Safety Rule 

The BOEMRE determined issuance of an interim rule was needed; this rule would implement the 

recommendations from the 30-Day Report considered by the Secretary to be the most important for safe 

resumption of offshore drilling operations. On October 14, 2010, the interim final rule was published in 

the Federal Register (2010b) together with a discussion of the comments that had been received by the 

Secretary in the period leading up to promulgation of the rule. The interim rulemaking revises selected 

sections of 30 CFR 250 Subparts D, E, F, O, and Q. Only a portion of the proposed changes in Subpart D 

will add material capital or operating costs (some of which will be significant). For example, identical 

costly new requirements for subsea function testing of remotely operated vehicle (ROV) intervention 

during drill operations (Subpart D) also apply to well completion (Subpart E) and workover (Subpart F) 

operations. 

Table 1-1 compares the previous 30 CFR 250 Subpart D requirements with the new regulations. 

Those changes that will impose significant costs include (1) seafloor function testing of ROV intervention 

and deadman systems (30 CFR 250.449(j) and (k), 30 CFR 250.516(d) and 250.616(h)); (2) negative 

pressure testing of individual casing strings (30 CFR 250.423(c)); (3) use of dual mechanical barriers for 

the final casing string (30 CFR 250.420(b)); (4) professional engineer certification that the well design is 

appropriate for expected wellbore conditions (30 CFR 250.420(a)); (5) retrieval and testing of BOP after a 

shear ram has been activated in a well-control situation (30 CFR 250.451(i)); and (6) third-party 

certification that the shear rams will shear drill pipe under maximum anticipated pressure (30 CFR 

250.416(e)). 

Subsea ROV and Deadman Function Testing—Drilling 

Previous regulations at 30 CFR 250.449(b) required a stump test of the subsea BOP system. In a 

stump test, the subsea BOP system is placed on a simulated wellhead (the stump) on the rig floor. The 

BOP system is tested on the stump to ensure that the BOP is functioning properly. The new regulatory 

section at 30 CFR 250.449(j) requires that all ROV intervention functions on the subsea BOP stack must 

be tested during the stump test and one set of rams must be tested by an ROV on the seafloor. 

Autoshear and deadman control systems activate during an accidental disconnect or loss of power, 

respectively. The new regulatory section at 30 CFR 250.449(k) requires that the autoshear and deadman 

systems be function-tested during the stump test, and the deadman system tested during the initial test on 

the seafloor. The initial test on the seafloor is performed as soon as the BOP is attached to the subsea 

wellhead. 

These new requirements will confirm that a well will be secured in an emergency situation and 

prevent a possible loss of well control. The ROV test requirement will ensure that the dedicated ROV has 

the capacity to close the BOP functions on the seafloor. The deadman-switch test on the seafloor verifies 

that the wellbore closes automatically if both hydraulic pressure and electrical communication are lost 

with the rig. 

The initial test on the seafloor for one set of rams and the deadman system is not currently an industry 

standard practice and will incur lost rig time. The addition of autoshear and deadman systems stump 

testing will incur additional rig time, but we do not expect the ROV intervention function stump testing to 

significantly increase testing time. Some operators currently simulate the hydraulic flow of an ROV to 

function test the BOP stack, while others use an actual ROV to test the BOP stack; this regulation will 

require the use of an ROV during the stump test. 

The BOEMRE conducted a survey to investigate the potential impact of subsea ROV testing. Several 

drilling contractors, lease operators, and equipment manufacturers were asked: “How long would it take 

to function test the ROV to verify that the ROV could be used to close one set of blind-shear rams, one 

set of pipe rams, and disconnect the lower marine riser package (LMRP)?” Results averaged about 

24 hours of lost rig time to perform these subsea tests. However, the interim regulation only requires one 

set of rams and the deadman system to be tested on the seafloor, not disconnecting the LMRP. The 

LMRP disconnect is estimated to require more time than testing the deadman system alone. We did not 

ask about the autoshear and deadman stump test requirements in our survey. We estimate that performing 

both the autoshear and deadman stump tests take close to the same time required to test the LMRP 
The Proposed Action 1-9 

seafloor disconnect. The regulation will not affect platform rigs or shallow wells since they do not use 

subsea BOP’s or ROV’s. 

Subsea ROV Function Testing—Workover/Completions

Previous regulations did not require subsea ROV function testing of the BOP during workover or 

completions operations. The new regulatory sections 30 CFR 250.516(d)(8) and 250.616(h)(1) require 

testing of ROV intervention functions and the autoshear/deadman systems during the stump test, and a 

function test of at least one set of rams and the deadman system on the seafloor. These sections extend 

the requirements added to deepwater drilling operations (discussed in the previous section) to well 

completion operations and workover operations using a subsea BOP stack. Successful exploratory wells 

are typically temporarily abandoned until additional equipment is installed to produce the reservoir. 

When the operator is preparing to produce the well, it is often completed using a different rig or 

redeployment of the original rig. The BOEMRE data show that two-thirds of deepwater wells drilled are 

exploratory wells, and approximately 23 percent of exploratory wells are completed. 

Negative Pressure Tests

Previous regulation at 30 CFR 250.423 required a positive pressure test for each string of casing, 

except for the drive or structural casing string. This test confirms that fluid from the casing string is not 

flowing into the formation. The new regulatory section at 30 CFR 250.423(c) requires that a negative 

pressure test be conducted for all intermediate and production casing strings. This test will reveal 

whether gas or fluid from outside the casing is flowing into the well and ensures that the casing and 

cement provide a seal. Maintenance of pressure under both tests ensures proper casing installation and 

the integrity of the casing and cement. Based on in-house expertise, we estimate each new negative 

pressure test will take approximately 90 minutes for each casing string. We also estimate that, on 

average, deepwater wells use one production and four intermediate casing strings and that shallow wells 

use one production and two intermediate casing strings. 

Installation of Dual Mechanical Barriers

Previous regulations did not require the installation of dual mechanical barriers. The new regulatory 

section at 30 CFR 250.420(b)(3) requires the operator install dual mechanical barriers in addition to 

cement barriers for the final casing string. These barriers prevent hydrocarbon flow in the event of 

cement failure at the bottom of the well. The operator must document the installation of the dual 

mechanical barriers and submit this documentation to BOEMRE within 30 days after installation. These 

new requirements will ensure that the best casing and cementing design will be used for a specific well. 

Dual mechanical barriers may include two float valves or one float valve and one mechanical plug. Based 

on in-house expertise, BOEMRE estimates that all wells will require a second mechanical barrier. 

Professional Engineer Certification for Well Design

Previous regulations at 30 CFR 250.420(a) specified well casing and cementing requirements but did 

not require verification by a Registered Professional Engineer. The new regulatory section at 30 CFR 

250.420(a)(6) (modified October 14, 2010) requires that well casing and cementing specifications must be 

certified by a Registered Professional Engineer. The Registered Professional Engineer will verify that the 

well casing and cementing design is appropriate for the purpose for which it is intended under expected 

wellbore conditions. This verification will add assurance that the appropriate design is used for the well, 

thus decreasing the likelihood of a blowout. 

Emergency Cost of Activated Shear Rams 

Previous regulations did not address BOP inspection following use of the blind-shear ram or casing 

shear ram. The new regulatory section at 30 CFR 250.451(i) requires that, if a blind-shear ram or casing 

shear ram is activated in a well control situation where the pipe is sheared, the BOP stack must be 

retrieved, fully inspected, and tested. This provision will ensure the integrity of the BOP and that the 
1-10 Central Planning Area Supplemental EIS 

BOP will still function and hold pressure after the event. This activity, when triggered, will add about 

13 days to drilling time. According to a Det Norske Veritas study, out of 5,611 deepwater wells, there 

were 12 situations where either the blind-shear or casing shear ram was activated; this implies one 

activation for every 515 wells drilled. 

Third-Party Shearing Verification

Regulation 30 CFR 250.416(e) requires information verifying that BOP blind-shear rams are capable 

of cutting through any drill pipe in the hole under maximum anticipated conditions. This regulation has 

been modified to require the BOP verification be conducted by an independent third party. The 

independent third party provides an objective assessment that the blind-shear rams can shear any drill 

pipe in the hole if the shear rams are functioning properly. This confirmation will be required for both 

subsea and surface BOP’s. NTL 2010-N10, “Statement of Compliance with Applicable Regulations and 

Evaluation of Information Demonstrating Adequate Spill Response and Well Containment Resources,” 

clarifies how the regulations apply to operators conducting operations using subsea BOP’s or surface 

BOP’s on floating facilities. The NTL informs these operators that a statement, signed by an authorized 

company official stating that the operator will conduct all authorized activities in compliance with all 

applicable regulations, including the increased safety measures regulations, should be submitted with each 

application for a well permit. 

30 CFR 250 Subpart S—Safety and Environmental Management System (SEMS) 

Following the DWH event, BOEMRE promulgated a final rule that requires operators to develop and 

implement a SEMS for OCS operations (Federal Register, 2010a). As explained in a BOEMRE fact 

sheet (USDOI, BOEMRE, 2010b), a SEMS is a comprehensive management program for identifying, 

addressing, and managing operational safety hazards and impacts, with the goal of promoting both human 

safety and environmental protection. The SEMS program rule is a workplace safety program rule 

covering all offshore oil and gas operations in Federal waters and makes mandatory the previously 

voluntary practices in the API RP 75. A mandatory oil and gas SEMS program is intended to enhance the 

safety and environmental protection of oil and gas drilling operations on the OCS. The SEMS Rule is 

implemented in the new Subpart S of 30 CFR 250.1900-1915. The Final Rule became effective on 

November 15, 2010, and needs to be implemented by November 15, 2011. 

This Agency was preparing to finalize the SEMS Workplace Safety Rule before the DWH event. 

During the DWH event, BOEMRE continued to carefully analyze the proposed rule, which proposed 

making mandatory the essential components of API RP 75. The BOEMRE has determined that it agrees 

with comments from some reviewers urging BOEMRE to incorporate all of API RP 75. The BOEMRE 

intends to address additional safety management system provisions considered appropriate in light of the 

DWH event in additional future rulemakings. 

The BOEMRE believes that finalizing the Workplace Safety Rule has the following benefits. It will 

(1) provide oversight and enforcement of SEMS provisions (Although many large operators on the OCS 

currently have a SEMS program, the voluntary nature of the programs limits their effectiveness.); (2) 

impose the requirement for a SEMS program on all OCS operators; (3) address human factors behind 

accidents not reached by previous regulations; and (4) provide a flexible approach to systematic safety 

that can keep up with evolving technologies. 

The 13 elements of API RP 75 that 30 CFR 250 Subpart S now make mandatory are as follows: 

 defining the general provisions for implementation, planning and management 

review, and approval of the SEMS program; 

 identifying safety and environmental information needed for any facility such as 

design data, facility process such as flow diagrams, and mechanical components such 

as piping and instrument diagrams; 

 requiring a facility-level risk assessment; 

 addressing any facility or operational changes including management changes, shift 

changes, contractor changes; 
The Proposed Action 1-11 

 evaluating operations and written procedures; 

 specifying safe work practices, manuals, standards, and rules of conduct; 

 training, safe work practices, and technical training, including contractors; 

 defining preventive maintenance programs and quality control requirements; 

 requiring a pre-startup review of all systems; 

 responding to and controlling emergencies, evacuation planning, and oil-spill 

contingency plans in place and validated by drills; 

 investigating incidents, procedures, corrective action, and follow-up; 

 requiring audits every 4 years, to an initial 2-year reevaluation and then subsequent 

3-year audit intervals; and 

 specifying records and documentation that describes all elements of the SEMS 

program. 

1.4. PRELEASE PROCESS

Scoping for this Supplemental EIS was conducted in accordance with Council Environmental Quality 

(CEQ) regulations implementing NEPA. Scoping provides those with an interest in the OCS Program an 

opportunity to provide comments on the proposed action. In addition, scoping provides BOEMRE an 

opportunity to update the Gulf of Mexico OCS Region’s environmental and socioeconomic information 

base. The public scoping process for this Supplemental EIS began November 10, 2010, with publication 

of the Notice of Intent to Prepare a Supplemental EIS (NOI) and an announcement for three scoping 

meetings (Federal Register, 2010c). A 45-day comment period was established. A subsequent NOI was 

published in the Federal Register on November 16, 2010, to correct clerical errors in the first notice, and 

it established January 3, 2011, for the closing of the comment period (Federal Register, 2010d). Between 

the first and second NOI’s, the dates and locations for scoping meetings announced on November 10, 

2010, did not change. 

Although the scoping process for the current 5-Year Program was formally initiated on March 7, 

2006, with the publication of the NOI in the Federal Register, scoping efforts and other coordination 

meetings have proceeded and will continue to proceed throughout this NEPA process. Scoping and 

coordination opportunities are available during BOEMRE’s requests for information, comments, input, 

and review on other BOEMRE NEPA documents. 

The Area Identification decision was made for all proposed lease sales in the current 5-Year Program 

on August 10, 2006. The Area Identification is an administrative prelease step that describes the 

geographical area of the proposed action (proposed lease sale area) and identifies the alternatives, 

mitigating measures, and issues to be analyzed in the appropriate NEPA document. As mandated by 

NEPA, this Supplemental EIS analyzes the potential impacts of the proposed action on the marine, 

coastal, and human environments. 

Scoping meetings were held on November 16 in New Orleans at the Louis Armstrong Airport Hilton, 

on November 17 in Houston at the George Bush Airport Marriott, and on November 18 in Mobile at the 

Battle House Renaissance Mobile Hotel. Public notices were published on November 12 and 13, 2010, 

the weekend before the meetings, in these local papers: the Times Picayune; the Houston Chronicle; and 

the Mobile Register. Announcements were sent by U.S. mail to addressees on BOEMRE’s Gulf of 

Mexico mailing list and were posted on the Internet. Letters were sent to the Governor’s of the five Gulf 

Coast States announcing the scoping process on November 10, 2010. Federal, State, and local 

governments, along with other interested parties, were invited to send written comments to the Gulf of 

Mexico OCS Region on the scope of the Supplemental EIS. Comments were received in response to the 

NOI, and testimony was provided at the scoping meetings from Federal, State, local government agencies, 

interest groups, industry, businesses, and the general public on the scope of the Supplemental EIS, 

significant issues that should be addressed, alternatives that should be considered, and mitigation 
1-12 Central Planning Area Supplemental EIS 

measures. All scoping meeting comments received were considered in the preparation of this 

Supplemental EIS. The comments (both verbal and written) have been summarized in Chapter 5.3. 

The BOEMRE also conducted early coordination with appropriate Federal and State agencies and 

other concerned parties to discuss and coordinate the prelease process for the proposed lease sale and this 

Supplemental EIS. Key agencies and organizations included the U.S. Department of Commerce, National 

Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service (NMFS); U.S. 

Department of Defense (USDOD or DOD); U.S. Coast Guard (USCG or CG); U.S. Environmental 

Protection Agency (USEPA); State Governors’ offices; and industry groups. 

The BOEMRE is providing copies of this Draft Supplemental EIS for review and comment to public 

and private agencies, interest groups, and local libraries. To initiate the public review and comment 

period on this Draft Supplemental EIS, BOEMRE will publish a Notice of Availability (NOA) in the 

Federal Register. Additionally, public notices will be mailed with this Draft Supplemental EIS and 

placed on the BOEMRE, Gulf of Mexico OCS Region’s Internet website. In accordance with 30 CFR 

256.26, BOEMRE will hold public hearings to solicit comments on this Draft Supplemental EIS. The 

hearings provide the Secretary with information from interested parties to help in the evaluation of 

potential effects of the proposed lease sale. Notices of the public hearings will be included in the NOA, 

posted on the BOEMRE, Gulf of Mexico OCS Region’s Internet website, and published in the Federal 

Register and local newspapers. 

A consistency review will be performed and a Consistency Determination (CD) will be prepared for 

each affected State prior to the proposed lease sale. To prepare the CD’s, BOEMRE reviews each State’s 

Coastal Management Program (CMP) and analyzes the potential impacts as outlined in this Supplemental 

EIS, new information, and applicable studies as they pertain to the enforceable policies of each CMP. 

Based on the analyses, the BOEMRE Director makes an assessment of consistency, which is then sent to 

each State with the Proposed Notice of Sale (NOS). If a State objects with BOEMRE’s CD, the State is 

required to do the following under CZMA: (1) indicate how BOEMRE’s presale proposal is inconsistent 

with specific enforceable policies of the CMP (specify the enforceable policy with citation); (2) describe 

alternative measures (if they exist) to bring BOEMRE’s proposal into consistency with their CMP; or (3) 

describe the nature of the information requested and the necessity of such information to determine the 

consistency of the Federal agency activity with the enforceable policies of the management program. 

Unlike the consistency process for specific OCS plans and permits, there is not a procedure for 

administrative appeal to the Secretary of Commerce for a Federal CD for presale activities. In the event 

of a serious disagreement between a Federal agency and the State CMP regarding consistency of the 

proposed lease sale, either BOEMRE or the State may request mediation. The regulations provide for an 

opportunity to resolve any differences with the State, but CZMA allows BOEMRE to proceed with the 

lease sale despite any unresolved disagreements if the Federal agency clearly describes, in writing, to the 

State CMP how the activity is consistent to the maximum extent practicable. 

The Final Supplemental EIS will be published approximately 5 months prior to the proposed lease 

sale. To initiate the public review and 30-day minimum comment period on the Final Supplemental EIS, 

BOEMRE will publish a NOA in the Federal Register. The BOEMRE will provide copies of the Final 

Supplemental EIS for review and comment to public and private agencies, interest groups, and local 

libraries. Additionally, public notices will be mailed with the Final Supplemental EIS and placed on the 

BOEMRE, Gulf of Mexico OCS Region’s Internet website. 

After the end of the comment period, DOI will review the Supplemental EIS in consideration of all 

comments received on the Final Supplemental EIS. The Supplemental EIS is not a decision document. A 

Record of Decision (ROD), which is the last step in this Supplemental EIS process, will be published 

before the sale is scheduled. The ROD will summarize the proposed action and the alternatives evaluated 

in the Supplemental EIS, the conclusions of the impact analyses, and other information considered in 

reaching the decision. All comments received on the Final Supplemental EIS will be addressed in the 

ROD. 

A Proposed NOS will become available to the public 4-5 months prior to the proposed lease sale. A 

notice announcing the availability of the Proposed NOS appears in the Federal Register, initiating a

60-day comment period. Comments received will be analyzed during preparation of the decision 

documents that are the basis for the Final NOS, including proposed lease sale configuration and terms and 

conditions. 
The Proposed Action 1-13 

If the decision by the Assistant Secretary of the Interior for Land and Minerals (ASLM) is to hold the 

proposed lease sale, a Final NOS will be published in its entirety in the Federal Register at least 30 days 

prior to the sale date, as required by the OCSLA. If the ASLM determines that the proposed lease sale 

will not move forward, then the Final NOS will not be published. 

1.5. POSTLEASE ACTIVITIES

The BOEMRE is responsible for managing, regulating, and monitoring oil and natural gas 

exploration, development, and production operations on the Federal OCS to promote orderly development 

of mineral resources and to prevent harm or damage to, or waste of, any natural resource, any life or 

property, or the marine, coastal, or human environment. Regulations for oil, gas, and sulphur lease 

operations are specified in 30 CFR 250, 30 CFR 251, and 30 CFR 254. 

Measures to mitigate potential impacts are an integral part of the OCS Program. These measures are 

implemented through lease stipulations, operating regulations, NTL’s, and project-specific requirements 

or approval conditions. Mitigating measures address concerns such as endangered and threatened species, 

geologic and manmade hazards, military warning and ordnance disposal areas, archaeological sites, air 

quality, oil-spill response planning, chemosynthetic communities, artificial reefs, operations in hydrogen 

sulfide (H2S) prone areas, and shunting of drill effluents in the vicinity of biologically sensitive features. 

Standard mitigation measures in the Gulf of Mexico OCS include 

 limiting the size of explosive charges used for structure removals; 

 requiring placement explosive charges at least 15 ft (5 m) below the mudline; 

 requiring site-clearance procedures to eliminate potential snags to commercial fishing 

nets; 

 establishment of No Activity and Modified Activity Zones around high-relief live 

bottoms; 

 requiring remote-sensing surveys to detect and avoid biologically sensitive areas such 

as low-relief live bottoms, pinnacles, and chemosynthetic communities; and 

 requiring coordination with the military to prevent multiuse conflicts between OCS 

and military activities. 

The BOEMRE issues NTL’s to provide clarification, description, or interpretation of a regulation; 

guidelines on the implementation of a special lease stipulation or regional requirement; or convey 

administrative information. A detailed listing of current Gulf of Mexico OCS Region NTL’s is available 

through the BOEMRE, Gulf of Mexico OCS Region’s Internet website or through the Region’s Public 

Information Office at (504) 736-2519 or 1-800-200-GULF. 

Formal plans must be submitted to BOEMRE for review and approval before any project-specific 

activities, except for ancillary activities (such as geological and geophysical activities or studies that 

model potential oil and hazardous substance spills), can begin on a lease. Conditions of approval are 

mechanisms to control or mitigate potential safety or environmental problems associated with proposed 

operations. Conditions of approval are based on BOEMRE technical and environmental evaluations of 

the proposed operations. Comments from Federal and State agencies (as applicable) are also considered 

in establishing conditions. Conditions may be applied to any OCS plan, permit, right-of-use of easement, 

or pipeline right-of-way grant. 

Some BOEMRE-identified mitigation measures are implemented through cooperative agreements or 

coordination with the oil and gas industry and Federal and State agencies. These measures include the 

NOAA Fisheries Service Observer Program to protect marine mammals and sea turtles when OCS 

structures are removed using explosives, labeling of operational supplies to track sources of accidental 

debris loss, development of methods of pipeline landfall to eliminate impacts to barrier beaches, and 

semiannual beach cleanup events. 

The following postlease activity descriptions apply to the proposed lease sale area in the CPA. 
1-14 Central Planning Area Supplemental EIS 

Geological and Geophysical Activities 

A geological and geophysical (G&G) permit must be obtained from BOEMRE prior to conducting 

off-lease geological or geophysical exploration or scientific research on unleased OCS lands or on lands 

under lease to a third party (30 CFR 251.4 (a) and (b)). Geological investigations include various seafloor 

sampling techniques to determine the geochemical, geotechnical, or engineering properties of the 

sediments. 

Ancillary activities are defined in 30 CFR 250.105 with regulations outlined in 30 CFR 250.207 

through 250.210. Ancillary activities are activities conducted on-lease and include G&G exploration and 

development G&G activities; geological and high-resolution geophysical, geotechnical, archaeological, 

biological, physical oceanographic, meteorological, socioeconomic, or other surveys; or various types of 

modeling studies. This Agency issued NTL 2009-G34, “Ancillary Activities,” to provide updated 

guidance and clarification on conducting ancillary activities in BOEMRE’s Gulf of Mexico OCS Region. 

Operators should notify the BOEMRE, Gulf of Mexico OCS Region, Regional Supervisor, Field 

Operations in writing 30 days in advance before conducting any of the following types of ancillary 

activities: 

 involving the use of an airgun or airgun array in water depths 200 m (656 ft) or 

greater, or in the Eastern Planning Area (EPA) of the GOM in any water depth; 

 independent of water depth, involving the use of explosives as an energy source; and 

 independent of water depth, including ocean-bottom cable surveys, node surveys, and 

time-lapse (4D) surveys. 

Additionally, NTL 2009-G34 clarifies that the Gulf of Mexico OCS Region, Regional Supervisor, 

Field Operations should be notified in writing 15 days in advance before conducting the following types 

of ancillary activities: 

 involving the use of an airgun or airgun array in water depths 200 m (656 ft) or 

greater, or in the EPA of the GOM in any water depth; 

 involving bottom disturbance, independent of water depth, including ocean-bottom 

cable surveys, node surveys, and time-lapse (4D) surveys; and 

 a geotechnical evaluation involving piston-/gravity-coring or the recovery of 

sediment specimens by grab-sampling or similar technique and/or any dredging or 

other ancillary activity that disturbs the seafloor (including deployment and retrieval 

of bottom cables, anchors, or other equipment). 

This NTL also provides guidance for each type of ancillary activity, the type and level of BOEMRE 

review, and follow-up, post-survey report requirements. 

Seismic surveys are performed to obtain information on surface and near-surface geology and on 

subsurface geologic formations. Low-energy, high-resolution seismic surveys collect data on surficial 

geology used to identify potential shallow geologic or manmade hazards (e.g., faults or pipelines) for 

engineering and site planning for bottom-founded structures. The high-resolution surveys are also used to 

identify environmental and archaeological resources such as low-relief live-bottom areas, pinnacles, 

chemosynthetic community habitat, and shipwrecks. High-energy, deep-penetration, common-depthpoint (CDP) seismic surveys obtain data about geologic formations thousands of feet below the seafloor. 

The two-dimensional (2D) and three-dimensional (3D) CDP data are used to map structure features of 

stratigraphically important horizons in order to identify potential hydrocarbon traps. They can also be 

used to map the extent of potential habitat for chemosynthetic communities. In some situations, a set of 

3D surveys can be run over a time interval to produce a four-dimensional (4D), or “time-lapse,” survey 

that could be used to characterize production reservoirs. 

This Agency completed a programmatic environmental assessment (EA) on Geological and 

Geophysical Exploration for Mineral Resources on the Gulf of Mexico OCS (CSA, 2004a). Upon 

receiving a complete G&G permit application, BOEMRE conducts a categorical exclusion review (CER), 
The Proposed Action 1-15 

an EA, or an EIS in accordance with the G&G Programmatic EA’s conclusions, NEPA guidelines, and 

other applicable BOEMRE policies. When required under an approved coastal management program, 

proposed G&G permit activities must receive State concurrence prior to BOEMRE permit approval. 

Exploration and Development Plans 

To ensure conformance with the OCSLA, other laws, applicable regulations, and lease provisions, 

and to enable BOEMRE to carry out its functions and responsibilities, formal plans (30 CFR 250.211 and 

250.241) with supporting information must be submitted for review and approval by BOEMRE before an 

operator may begin exploration, development, or production activities on any lease. Supporting 

environmental information, archaeological reports, biological reports (monitoring and/or live-bottom 

survey), and other environmental data determined necessary must be submitted with an OCS plan. This 

information provides the basis for an analysis of both offshore and onshore impacts that may occur as a 

result of the activities. The BOEMRE may require additional specific supporting information to aid in the 

evaluation of the potential environmental impacts of the proposed activities. The BOEMRE can require 

amendment of an OCS plan based on inadequate or inaccurate supporting information. The 30 CFR 250 

Subpart B regulations were revised to update the information that must be submitted and were published 

in the Federal Register on August 30, 2005 (70 FR 167). 

The OCS plans are reviewed by geologists, geophysicists, engineers, biologists, archaeologists, air 

quality specialists, oil-spill specialists, NEPA coordinators, and/or environmental scientists. The plans 

and accompanying information are evaluated to determine whether any seafloor or drilling hazards are 

present; that air and water quality issues are addressed; that plans for hydrocarbon resource conservation, 

development, and drainage are adequate; that environmental issues and potential impacts are properly 

evaluated and mitigated; and that the proposed action is in compliance with NEPA, CZMA, BOEMRE 

operating regulations, and other requirements. Federal agencies, including the U.S. Fish and Wildlife 

Service (FWS), NOAA Fisheries Service, USEPA, the U.S. Navy, the U.S. Air Force, and the USCG, 

may be consulted if the proposal has the potential to impact areas under their jurisdiction. Each Gulf 

Coast State has a designated CZM agency that takes part in the review process. The OCS plans are also 

made available to the general public for comment through the BOEMRE, Gulf of Mexico OCS Region’s 

Public Information Office. 

In response to increasing deepwater activities in the GOM, BOEMRE developed a comprehensive 

strategy to address NEPA compliance and environmental issues in the deepwater areas. A key component 

of that strategy was the completion of a Programmatic EA to evaluate the potential effects of the 

deepwater technologies and operations (USDOI, MMS, 2000). As a supplement to the Programmatic EA, 

this Agency prepared a series of technical papers that provide a summary description of the different 

types of structures that may be employed in the development and production of hydrocarbon resources in 

the deepwater areas of the GOM (Regg et al., 2000). The Programmatic EA and technical papers were 

used in the preparation of this Supplemental EIS. 

On the basis of the BOEMRE reviews of the OCS plan, the findings of the proposal-specific CER, 

EA, or EIS, and other applicable BOEMRE studies and NEPA documents, the OCS plan is approved or 

disapproved by BOEMRE, or modified and resubmitted. Although very few OCS plans are ultimately 

disapproved, many must be amended prior to approval to fully comply with BOEMRE operating 

regulations and requirements, or other Federal laws, to address reviewing agencies’ concerns, or to avoid 

potential hazards or impacts to environmental resources. 

On May 12, 2008, this Agency issued NTL 2008-G06, “Remotely Operated Vehicle (ROV) Surveys 

in Deepwater.” The NTL provides guidance for ROV surveys and reports in water depths greater than 400 

m (1,312 ft). Twenty-one grid areas have been developed to ensure a broad and systematic analysis of 

deep water and to depict areas of biological similarity, primarily on the basis of benthic communities. 

The grid areas cover the WPA and CPA. Grids 18, 19, 20, and 21 have been designated as deepwater and 

ultra-deepwater grids (Figure 1-3). 

Operators must submit a ROV survey plan with each Exploration Plan (EP) submitted in each grid 

area and with the Development Operations Coordination Document (DOCD) for the first surface structure 

proposed in each grid area. The DOCD is a document that must be prepared by the operator and 

submitted to BOEMRE for approval before any development or production activities are conducted on a 

lease in the Western Gulf. The following information must be included in a ROV survey plan: 
1-16 Central Planning Area Supplemental EIS 

 a statement that the operator is familiar with the ROV survey and reporting 

provisions outlined in the NTL; 

 a brief description of the survey the operator plans to conduct, including timeframes, 

proposed transects, and the equipment that will be used; and 

 a statement that the operator will make biological and physical observations as 

described in the NTL and the ROV survey form during two periods of operations—

pre-spudding (survey performed from the facility) and post-drilling (prior to facility 

removal). 

A minimum of five surveys will be required for each grid area. The BOEMRE will notify the 

operator whether or not to conduct the proposed ROV survey based on whether the grid area has already 

received adequate ROV survey coverage (as documented at http://www.gomr.boemre.gov/homepg/

regulate/environ/ea_grid/ea_grid.asp). 

Exploration Plans 

An EP must be submitted to BOEMRE for review and decision before any exploration activities, 

except for preliminary activities (such as hazard surveys or geophysical surveys), can begin on a lease. 

The EP describes exploration activities, drilling rig or vessel, proposed drilling and well-testing 

operations, environmental monitoring plans, and other relevant information, and includes a proposed 

schedule of the exploration activities. Guidelines and environmental information requirements for lessees 

and operators submitting an EP are addressed in 30 CFR 250.211 and are further explained in NTL’s 

2008-G04, “Shallow Hazards Program,” and 2009-G27, “Submitting Exploration Plans and Development 

Operations Coordination Documents.” The NTL 2008-G04 provides guidance on information 

requirements and establishes the contents for OCS plans required by 30 CFR 250 Subpart B. The NTL 

2010-N06, “Information Requirements for Exploration Plans, Development and Production Plans, and 

Development Operations Coordination Documents on the OCS,” effective June 18, 2010, rescinded the 

limitations set forth in NTL 2008-G04 regarding a blowout and worse-case discharge scenarios and 

provided national guidance regarding the content of information in a blowout and worse-case discharge 

scenario descriptions. The NTL 2009-G27 clarifies guidance for submitting OCS plans and DOCD’s to 

the BOEMRE, Gulf of Mexico OCS Region.

After receiving an EP, BOEMRE determines if the plan is complete and adequate before technical 

and environmental reviews. The BOEMRE evaluates the proposed exploration activities for potential 

impacts relative to geohazards and manmade hazards (including existing pipelines), archaeological 

resources, endangered species, sensitive biological features, water and air quality, oil-spill response, State 

CZMA requirements, and other uses (e.g., military operations) of the OCS. The EP is reviewed for 

compliance with all applicable laws and regulations. 

A CER or EA is prepared as documentation of the environmental review of the EP. The CER or EA 

is based on available information, which may include the geophysical report (for determining the 

potential for the presence of deepwater benthic communities); archaeological report; air emissions data; 

live-bottom survey and report; biological monitoring plan; and recommendations by the affected State(s), 

DOD, FWS (for selected plans under provisions of a DOI agreement), NOAA Fisheries Service, and/or 

internal BOEMRE offices. As part of the review process, each EP must contain a certification of 

consistency and the necessary data and information for the State to determine that the proposed activities 

comply with the enforceable policies of the States’ approved CMP and that such activities will be 

conducted in a manner that is consistent with the CMP (16 U.S.C. 1456 (c)(3)(A) and 15 CFR 930.76). 

If the EP is approved, and prior to conducting drilling operations, the operator is required to submit 

and obtain approval for an Application for Permit to Drill (APD) (see Wells under Permits and 

Applications below). 

Deepwater Operations Plans 

In 1992, this Agency formed an internal Deepwater Task Force to address technical issues and 

regulatory concerns relating to deepwater (>1,000 ft; 305 m) operations and projects utilizing subsea 
The Proposed Action 1-17 

technology. Based on the Deepwater Task Force’s recommendation, an NTL (2000-N06) was at first 

developed that was incorporated into 30 CFR 250 Subpart B. The revisions to Subpart B were finalized 

August 30, 2005, and required operators to submit a Deepwater Operations Plan (DWOP) for all 

operations in deep water (400 m [1,312 ft] or greater) and all projects using subsea technology. DeepStar, 

an industry-wide cooperative workgroup focused on deepwater regulatory issues and critical technology 

development issues, worked closely with this Agency’s Deepwater Task Force to develop the initial 

guidelines for the DWOP. The DWOP was established to address regulatory issues and concerns that 

were not addressed in the existing BOEMRE regulatory framework, and it is intended to initiate an early 

dialogue between BOEMRE and industry before major capital expenditures on deepwater and subsea 

projects are committed. Deepwater technology has been evolving faster than BOEMRE’s ability to revise 

OCS regulations; the DWOP was established through the NTL process, which provides for a more timely 

and flexible approach to keep pace with the expanding deepwater operations and subsea technology. 

The DWOP is intended to address the different functional requirements of production equipment in 

deep water, particularly the technological requirements associated with subsea production systems, and 

the complexity of deepwater production facilities. The DWOP provides BOEMRE with information 

specific to deepwater equipment issues to demonstrate that a deepwater project is being developed in an 

acceptable manner as mandated in the OCSLA, as amended, and the BOEMRE operating regulations at 

30 CFR 250. The BOEMRE reviews deepwater development activities from a total system perspective, 

emphasizing operational safety, environmental protection, and conservation of natural resources. The 

DWOP process is a phased approach that parallels the operator’s state of knowledge about how a field 

will be developed. A DWOP outlines the design, fabrication, and installation of the proposed 

development/production system and its components. A DWOP will include structural aspects of the 

facility (fixed, floating, subsea); station-keeping (includes mooring system); wellbore, completion, and 

riser systems; safety systems; product removal or offtake systems; and hazards and operability of the 

production system. The DWOP provides BOEMRE with the information to determine that the operator 

has designed and built sufficient safeguards into the production system to prevent the occurrence of 

significant safety or environmental incidents. The DWOP, in conjunction with other permit applications, 

provides BOEMRE the opportunity to assure that the production system is suitable for the conditions in 

which it will operate. 

This Agency recently completed a review of several industry-developed, recommended practices that 

address the mooring and risers for floating production facilities. The recommended practices address 

such things as riser design, mooring system design (station-keeping), and hazard analysis. Hazard 

analyses allow BOEMRE to be assured that the operator has anticipated emergencies and is prepared to 

address them, either through their design or through the operation of the equipment in question. This 

Agency released these clarifications of its requirements in recent NTL’s: NTL 2009-G03, “Synthetic 

Mooring Systems”; NTL 2009-G11, “Accidental Disconnect of Marine Drilling Risers”; and NTL 

2009-G13, “Guidelines for Tie-downs on OCS Production Platforms for Upcoming Hurricane Seasons.” 

Conservation Reviews 

One of BOEMRE’s primary responsibilities is to ensure development of economically producible 

reservoirs according to sound conservation, engineering, and economic practices as cited in 30 CFR 

250.202(c), 250.203, 250.204, 250.205, 250.210, 250.296, 250.297, 250.298, 250.299, and 250.1101. 

Operators should submit the necessary information as part of their EP, initial and supplemental DOCD, 

and Conservation Information Document. Conservation reviews are performed to ensure that economic 

reserves are fully developed and produced, and that there is no harm to the ultimate recovery. 

Development Operations and Coordination Documents 

Before any development operations can begin on a lease in the proposed lease sale area, a DOCD 

must be submitted to BOEMRE for review and decision. A DOCD describes the proposed development 

activities, drilling activities, platforms or other facilities, proposed production operations, environmental 

monitoring plans, and other relevant information, and it includes a proposed schedule of development and 

production activities. Requirements for lessees and operators submitting a DOCD are addressed in 

30 CFR 250.241-250.242, and information guidelines for DOCD’s are provided in NTL’s 2008-G04, 

2009-G27, and 2010-N06. 
1-18 Central Planning Area Supplemental EIS 

After receiving a DOCD, BOEMRE performs technical and environmental reviews. The BOEMRE 

evaluates the proposed activity for potential impacts relative to geohazards and manmade hazards 

(including existing pipelines), archaeological resources, endangered species, sensitive biological features, 

water and air quality, oil-spill response, State CZMA requirements, and other uses (e.g., military 

operations) of the OCS. The DOCD is reviewed for compliance with all applicable laws and regulations. 

A CER, EA, and/or EIS are prepared as documentation of the environmental review of a DOCD. The 

CER, EA, and/or EIS are based on available information, which may include the geophysical report (for 

determining the potential for the presence of deepwater benthic communities); archaeological report; air 

emissions data; live-bottom survey and report; biological monitoring plan; and recommendations by the 

affected State(s), DOD, FWS (for selected plans under provisions of a DOI agreement), NOAA Fisheries 

Service, and/or internal BOEMRE offices. 

As part of the review process, the DOCD and related environmental analysis may be sent to the 

affected State(s) for a consistency review under the States’ federally approved coastal management 

program. The OCSLA (43 U.S.C. 1345(a) through (d) and 43 U.S.C. 1351(a)(3)) and CZMA (16 U.S.C. 

1456 (c)(3)(A) and 15 CFR 930.76) provide for this coordination and consultation with the affected State 

and local governments concerning a DOCD. 

New or Unusual Technologies 

Technologies continue to evolve to meet the technical, environmental, and economic challenges of 

deepwater development. New or unusual technologies (NUT’s) may be identified by the operator in its 

EP, DWOP, and DOCD or through BOEMRE’s plan review processes. Some of the technologies 

proposed for use by the operators are actually extended applications of existing technologies and interface 

with the environment in essentially the same way as well-known or conventional technologies. These 

technologies are reviewed by BOEMRE for alternative compliance or departures that may trigger 

additional environmental review. Some examples of new technologies that do not affect the environment 

differently and that are being deployed in the OCS Program are synthetic mooring lines, subsurface safety 

devices, and multiplex subsea controls. 

Some new technologies differ in how they function or interface with the environment. These include 

equipment or procedures that have not been installed or used in Gulf of Mexico OCS waters. Having no 

operational history, they have not been assessed by BOEMRE through technical and environmental 

reviews. New technologies may be outside the framework established by BOEMRE regulations and, 

thus, their performance (safety, environmental protection, efficiency, etc.) has not been addressed by 

BOEMRE. The degree to which these new technologies interface with the environment and the potential 

impacts that may result are considered in determining the level of NEPA review that would be initiated. 

The BOEMRE has developed a NUT’s matrix to help facilitate decisions on the appropriate level of 

engineering and environmental review needed for a proposed technology. Technologies will be added to 

the NUT’s matrix as they emerge, and technologies will be removed from the matrix as sufficient 

experience is gained in their implementation. From an environmental perspective, the matrix 

characterizes new technologies into three components: technologies that may affect the environment; 

technologies that do not interact with the environment any differently than “conventional” technologies; 

and technologies that BOEMRE does not have sufficient information to determine its potential impacts to 

the environment. In this later case, BOEMRE will seek to gain the necessary information from operators 

or manufacturers regarding the technologies to make an appropriate determination on its potential effects 

on the environment. 

Alternative Compliance and Departures: The BOEMRE’s project-specific engineering safety review 

ensures that equipment proposed for use is designed to withstand the operational and environmental 

condition in which it would operate. When an OCS operator proposes the use of technology or 

procedures not specifically addressed in established BOEMRE regulations, the operations are evaluated 

for alternative compliance or departure determination. Any new technologies or equipment that represent 

an alternative compliance or departure from existing BOEMRE regulation must be fully described and 

justified before it would be approved for use. For BOEMRE to grant alternative compliance or departure 

approval, the operator must demonstrate an equivalent or improved degree of protection as specified in 

30 CFR 250.141. Comparative analysis with other approved systems, equipment, and procedures is one 

tool that BOEMRE uses to assess the adequacy of protection provided by alternative technology or 
The Proposed Action 1-19 

operations. Actual operational experience is necessary with alternative compliance measures before 

BOEMRE would consider them as proven technology. 

Emergency Plans 

Criteria, models, and procedures for shutdown operations and the orderly evacuation for a pending 

hurricane have been in place in the Gulf of Mexico OCS for more than 30 years. (Such emergency plans 

are different from the oil-spill response plans described later in this chapter.) Operating experience from 

extensive drilling activities and more than 4,000 platforms during the 30-plus years of the Gulf of Mexico 

OCS Program have demonstrated the effectiveness and safety of securing wells and evacuating a facility 

in advance of severe weather conditions. Preinstallation efforts, historical experience with similar 

systems, testing, and the actual operating experience (under normal conditions and in response to 

emergency situations) are used to formulate the exact time needed to secure the wells and production 

facility and to evacuate it as necessary. Operators develop site-specific curtailment, securing, and 

evacuation plans that vary in complexity and formality by operator and type of activity. In general terms, 

all plans are intended to make sure the facility (or well) is secured in advance of a pending storm or 

developing emergency. The operating procedures developed during the engineering, design, and 

manufacturing phases of the project, coupled with the results (recommended actions) from hazard 

analyses performed, will be used to develop the emergency action and curtailment plans. Evacuation and 

production curtailment must consider a combination of factors, including the well status (drilling, 

producing, etc.) and the type and mechanics of wellbore operations. These factors are analyzed onsite 

through a decisionmaking process that involves onsite facility managers. The emphasis is on making 

real-time, situation-specific decisions and forecasting based on available information. Details of the shutin criteria and various alerts are addressed on a case-by-case basis. 

Plans for shutting in production from the subsea wells are addressed as part of the emergency 

curtailment plan. The plan specifies the various alerts and shutdown criteria linked to both weather and 

facility performance data, with the intent to have operations suspended and the wells secured in the event 

of a hurricane or emergency situation. Ensuring adequate time to safely and efficiently suspend 

operations and secure the well is a key component of the planning effort. Clearly defined responsibilities 

for the facility personnel are part of the successful implementation of the emergency response effort. 

For a severe weather event such as a hurricane, emergency curtailment plans would address the 

criteria and structured procedures for suspending operations and ultimately securing the wellbore(s) prior 

to weather conditions that could exceed the design operating limitations of the drilling or production unit. 

For drilling operations, the plan might also address procedures for disconnecting and moving the drilling 

unit off location after the well has been secured, should the environmental conditions exceed the floating 

drilling unit’s capability to maintain station. Curtailment of operations consists of various stages of 

“alerts” indicating the deterioration of meteorological, oceanographic, or wellbore conditions. Higher 

alert levels require increased monitoring, the curtailment of lengthy wellbore operations, and, if 

conditions warrant, the eventual securing of the well. If conditions improve, operations could resume 

based on the limitations established in the contingency plan for the known environmental conditions. The 

same emergency curtailment plans would be implemented in an anticipated or impending emergency 

situation, such as the threat of a terrorist attack. 

Neither BOEMRE nor USCG mandates that an operator must evacuate a production facility for a 

hurricane; it is a decision that rests solely with the operator. The USCG does require the submittal of an 

emergency evacuation plan that addresses the operator’s intentions for evacuation of nonessential 

personnel, egress routes on the production facility, lifesaving and personnel safety devices, firefighting 

equipment, etc. As activities move farther from shore, it may become safer to not evacuate the facility 

because helicopter operations become inherently more risky with greater flight times. Severe weather 

conditions also increase the risks associated with helicopter operations. The precedent for leaving a 

facility manned during severe weather is established in the North Sea and other operating basins. 

Redundant, fail-safe, automatic shut-in systems located inside the wellbore and at the sea surface, and 

in some instances at the seafloor, are designed to prevent or minimize pollution. These systems are 

designed and tested to ensure proper operation should a production facility or well be catastrophically 

damaged. Testing occurs at regular intervals with predetermined performance limits designed to ensure 

functioning of the systems in case of an emergency. After the DWH event, the testing requirements for 
1-20 Central Planning Area Supplemental EIS 

well control systems came under immediate scrutiny in the DOI Secretary’s “Safety Measures Report” 

that was delivered to him on May 27, 2010. The Safety Measures Report included a recommendation of a 

program of immediate recertification of BOP’s. As stated above, the new regulatory section at 30 CFR 

250.451(i) requires that, if a blind-shear ram or casing shear ram is activated in a well-control situation 

where the pipe is sheared, the BOP stack must be retrieved, fully inspected, and tested (Federal Register, 

2010b). This and other new regulations that improve safety in the event of an emergency are described 

above in Chapter 1.3.1. 

Permits and Applications 

After EP or DOCD approval, the operator submits applications for specific activities to BOEMRE for 

approval. These applications include those for drilling wells; well-test flaring; temporary well 

abandonment; installing a well protection structure, production platforms, satellite structures, subsea 

wellheads and manifolds, and pipelines; installation of production facilities; commencing production 

operations; platform removal and lease abandonment; and pipeline decommissioning. 

Wells 

The BOEMRE requirements for the drilling of wells can be found at 30 CFR 250 Subpart D. Lessees 

are required to take precautions to keep all wells under control at all times. The lessee must use the best 

available and safest technology to enhance the evaluation of abnormal pressure conditions and to 

minimize the potential for uncontrolled well flow. 

Prior to conducting drilling operations, the operator is required to submit and obtain approval for an 

APD. The APD requires detailed information—including project layout at a scale of 24,000:1, design 

criteria for well control and casing, specifications for blowout preventers, a mud program, cementing 

program, directional drilling plans, etc.—to allow evaluation of operational safety and pollutionprevention measures. The APD is reviewed for conformance with the engineering requirements and other 

technical considerations. 

The BOEMRE is responsible for conducting technical and safety reviews of all drilling, workover, 

and production operations on the OCS. These detailed analyses determine if the lessee’s proposed 

operation is in compliance with all regulations and all current health, safety, environmental, and classical 

engineering standards. 

The BOEMRE regulations at 30 CFR 250.1710-1717 address the requirements for permanent 

abandonment of a well on the OCS. A permanent abandonment includes the isolation of zones in the 

open wellbore, plugging of perforated intervals, plugging the annular space between casings (if they are 

open), setting a surface plug, and cutting and retrieving the casing at least 15 ft (5 m) below the mudline. 

All plugs must be tested in accordance with the regulations. There are no routine surveys of permanently 

abandoned well locations. If a well were found to be leaking, BOEMRE would require the operator of 

record to perform an intervention to repair the abandonment. If a well is temporarily abandoned at the 

seafloor, an operator must provide BOEMRE with an annual report summarizing plans to permanently 

abandon the well or to bring the well into production. 

Platforms and Structures 

The BOEMRE does a technical review of all proposed structure designs and installation procedures. 

All proposed facilities are reviewed for structural integrity. These detailed engineering reviews entail an 

evaluation of all operator proposals for fabrication, installation, modification, and repair of all mobile and 

fixed structures. The lessee must design, fabricate, install, use, inspect, and maintain all platforms and 

structures on the OCS to assure their structural integrity for the safe conduct of operations at specific 

locations. Applications for platform and structure approval are filed in accordance with 30 CFR 250.901. 

Design requirements are presented in detail at 30 CFR 250.904 through 250.909. The lessee evaluates 

characteristic environmental conditions associated with operational functions to be performed. Factors 

such as waves, wind, currents, tides, temperature, and the potential for marine growth on the structure are 

considered. In addition, pursuant to 30 CFR 250.902 and 250.903, a program has been established by 

BOEMRE to assure that new structures meeting the conditions listed under 30 CFR 250.900(c) are 

designed, fabricated, and installed using standardized procedures to prevent structural failures. This 
The Proposed Action 1-21 

program facilitates review of such structures and uses third-party expertise and technical input in the 

verification process through the use of a Certified Verification Agent. After installation, platforms and 

structures are required to be periodically inspected and maintained under 30 CFR 250.912. 

Pipelines 

Regulatory processes and jurisdictional authority concerning pipelines on the OCS and in coastal 

areas are shared by several Federal agencies, including DOI, Department of Transportation (DOT), U.S. 

Army Corps of Engineers (COE), the Federal Energy Regulatory Commission (FERC), and the USCG. 

Aside from pipeline regulations, these agencies have the responsibility of overseeing and regulating the 

following areas: the placement of structures on the OCS and pipelines in areas that affect navigation; the 

certification of proposed projects involving the transportation or sale of interstate natural gas, including 

OCS gas; and the right of eminent domain exercised by pipeline companies onshore. In addition, DOT is 

responsible for promulgating and enforcing safety regulations for the transportation in interstate 

commerce of natural gas, liquefied natural gas (LNG), and hazardous liquids by pipeline. This includes, 

for the most part, offshore pipelines on State lands beneath navigable waters and on the OCS that are 

operated by transmission companies. The regulations are contained in 49 CFR 191 through 193 and 195. 

In a Memorandum of Understanding (MOU) between DOT and DOI dated December 10, 1996, each 

party’s respective regulatory responsibilities are outlined. The DOT is responsible for establishing and 

enforcing design, construction, operation, and maintenance regulations, and for investigating accidents for 

all OCS transportation pipelines beginning downstream of the point at which operating responsibility 

transfers from a producing operator to a transporting operator. The DOI’s responsibility extends 

upstream from the transfer point described above. 

The BOEMRE is responsible for regulatory oversight of the design, installation, and maintenance of 

OCS producer-operated oil and gas pipelines. The BOEMRE operating regulations for pipelines found at 

30 CFR 250 Subpart J are intended to provide safe and pollution-free transportation of fluids in a manner 

that does not unduly interfere with other users of the OCS. Pipeline applications are usually submitted 

and reviewed separately from DOCD’s. Pipeline applications may be for on-lease pipelines or rights-ofway for pipelines that cross other lessees’ leases or unleased areas of the OCS. Pipeline permit 

applications to BOEMRE include the pipeline location drawing, profile drawing, safety schematic 

drawing, pipe design data, a shallow hazard survey report, and an archaeological report, if applicable. 

The DOI has regulatory responsibility for all producer-operated pipelines. The DOI’s responsibility 

extends downstream from the first production well to the last valve and associated safety equipment on 

the last OCS-related production system along the pipeline. The DOT’s regulatory responsibility extends 

shoreward from the last valve on the last OCS-related production facility. 

The BOEMRE evaluates the design, fabrication, installation, and maintenance of all OCS pipelines. 

Proposed pipeline routes are evaluated for potential seafloor or subsea geologic hazards and other natural 

or manmade seafloor or subsurface features or conditions (including other pipelines) that could have an 

adverse impact on the pipeline or that could be adversely impacted by the proposed operations. Routes 

are also evaluated for potential impacts on archaeological resources and biological communities. A 

NEPA review is conducted in accordance with applicable policies and guidelines. The BOEMRE 

prepares an EA on all pipeline rights-of-way that go ashore. For Federal consistency, applicants must 

comply with the regulations as clarified in NTL 2007-G20, “Coastal Zone Management Program 

Requirements for OCS Right-of-way Pipeline Applications.” All Gulf States require consistency review 

of right-of-way pipeline applications as described in the clarifying NTL.

The design of the proposed pipeline is evaluated for an appropriate cathodic protection system to 

protect the pipeline from leaks resulting from the effects of external corrosion of the pipe; an external 

pipeline coating system to prolong the service life of the pipeline; measures to protect the inside of the 

pipeline from the detrimental effects, if any, of the fluids being transported; the submersibility of the line 

(i.e., that the pipeline will remain in place on the seafloor and not have the potential to float, even if 

empty or filled with gas rather than liquids); proposed operating pressure of the line; and protection of 

other pipelines crossing the proposed route. Such an evaluation includes the following: (1) reviewing the 

calculations used by the applicant in order to determine whether the applicant properly considered such 

elements as the grade of pipe to be used, the wall thickness of the pipe, derating factors (the practice of 

operating a component well inside its normal operating limits to reduce the rate at which the component 
1-22 Central Planning Area Supplemental EIS 

deteriorates), related to the submerged and riser portions of the pipeline, the pressure rating of any valves 

or flanges to be installed in the pipeline, the pressure rating of any other pipeline(s) into which the 

proposed line might be tied, and the required pressure to which the line must be tested before it is placed 

in service; (2) protective safety devices such as pressure sensors and remotely operated valves, the 

physical arrangement of those devices proposed to be installed by the applicant for the purposes of 

protecting the pipeline from possible overpressure conditions and for detecting and initiating a response to 

abnormally low-pressure conditions; and (3) the applicant’s planned compliance with regulations 

requiring that pipelines installed in water depths less than 200 ft (61 m) be buried to a depth of at least 3 ft 

(1 m). In addition, pipelines crossing fairways require a COE permit and must be buried to a depth of at 

least 10 ft (3 m) and to 16 ft (5 m) if crossing an anchorage area. 

Operators are required to periodically inspect pipeline routes. Monthly overflights are conducted to 

inspect pipeline routes for leakage. 

Applications for pipeline decommissioning must also be submitted for BOEMRE review and 

approval. Decommissioning applications are evaluated to ensure they will render the pipeline inert and/or 

to minimize the potential for the pipeline becoming a source of pollution by flushing and plugging the 

ends and to minimize the likelihood that the decommissioned line will become an obstruction to other 

users of the OCS by filling it with water and burying the ends. 

Inspection and Enforcement 

The OCSLA authorizes and requires BOEMRE to provide for both an annual scheduled inspection 

and a periodic unscheduled (unannounced) inspection of all oil and gas operations on the OCS. The 

inspections are to assure compliance with all regulatory constraints that allowed commencement of the 

operation. 

The primary objective of an initial inspection is to assure proper installation of mobile drilling units 

and fixed structures, and proper functionality of their safety and pollution prevention equipment. After 

operations begin, additional announced and unannounced inspections are conducted. Unannounced 

inspections are conducted to foster a climate of safe operations, to maintain a BOEMRE presence, and to 

focus on operators with a poor performance record. These inspections are also conducted after a critical 

safety feature has previously been found defective. Poor performance generally means that more 

frequent, unannounced inspections may be conducted on a violator’s operation. 

The annual inspection examines all safety equipment designed to prevent blowouts, fires, spills, or 

other major accidents. These annual inspections involve the inspection for installation and performance 

of all facilities’ safety-system components. 

The inspectors follow the guidelines as established by the regulations, API RP 14C, and the specific 

BOEMRE-approved plan. The BOEMRE inspectors perform these inspections using a national checklist 

called the Potential Incident of Noncompliance (PINC) list. This list is a compilation of yes/no questions 

derived from all regulated safety and environmental requirements. 

The BOEMRE administers an active civil penalties program (30 CFR 250 Subpart N). A civil 

penalty in the form of substantial monetary fines may be issued against any operator that commits a 

violation that may constitute a threat of serious, irreparable, or immediate harm or damage to life, 

property, or the environment. The BOEMRE may make recommendations for criminal penalties if a 

willful violation occurs. In addition, the regulation at 30 CFR 250.173(a) authorizes suspension of any 

operation in the GOMR if the lessee has failed to comply with a provision of any applicable law, 

regulation, or order or provision of a lease or permit. Furthermore, the Secretary may invoke his authority 

under 30 CFR 250.185(c) to cancel a nonproductive lease with no compensation. Exploration and 

development activities may be canceled under 30 CFR 250.182 and 250.183. 

Pollution Prevention, Oil-Spill Response Plans, and Financial Responsibility 

Pollution Prevention 

Pollution prevention is addressed through proper design and requirements for safety devices. The 

BOEMRE regulations at 30 CFR 250.400 require that the operator take all necessary precautions to keep 

its wells under control at all times. The lessee is required to use the best available and safest drilling 

technology in order to enhance the evaluation of conditions of abnormal pressure and to minimize the 
The Proposed Action 1-23 

potential for the well to flow or kick. Redundancy is required for critical safety devices that will shut off 

flow from the well if loss of control is encountered. A complete description of rule changes implemented 

as a result of the DWH event is detailed in Chapter 1.3.1. 

In addition, BOEMRE regulations at 30 CFR 250 Subparts E, F, and H require that the lessee assure 

the safety and protection of the human, marine, and coastal environments during completion, workover, 

and production operations. All production facilities, including separators, treaters, compressors, headers, 

and flowlines are required to be designed, installed, tested, maintained, and used in a manner that 

provides for efficiency, safety of operations, and protection of the environment. Wells, particularly 

subsea wells, include a number of sensors that help in detecting pressures and the potential for leaks in the 

production system. Safety devices are monitored and tested frequently to ensure their operation, should 

an incident occur. To ensure that safety devices are operating properly, BOEMRE incorporates the API 

RP 14C into the operating regulations. The API RP 14C incorporates the knowledge and experience of 

the oil and gas industry regarding the analysis, design, installation, and testing of the safety devices used 

to prevent pollution. The API RP 14C presents proven practices for providing these safety devices for 

offshore production platforms. Proper application of these practices, along with good design, 

maintenance, and operation of the entire production facility, should provide an operationally safe and 

pollution-free production platform. 

Also, BOEMRE regulations at 30 CFR 250 Subpart J require that pipelines and associated valves, 

flanges, and fittings be designed, installed, operated, and maintained to provide safe and pollution-free 

transportation of fluids in a manner that does not unduly interfere with other uses on the OCS. 

The BOEMRE regulation at 30 CFR 250.300(a) requires that lessees not create conditions that will 

pose an unreasonable risk to public health, life, property, aquatic life, wildlife, recreation, navigation, 

commercial fishing, or other uses of the ocean during offshore oil and gas operations. The lessee is 

required to take measures to prevent the unauthorized discharge of pollutants into the offshore waters. 

Control and removal of pollution is the responsibility and at the expense of the lessee. Immediate 

corrective action to an unauthorized release is required. All hydrocarbon-handling equipment for testing 

and production, such as separator and treatment tanks, are required to be designed, installed, and operated 

to prevent pollution. Maintenance and repairs that are necessary to prevent pollution are required to be 

taken immediately. Drilling and production facilities are required to be inspected daily or at intervals 

approved or prescribed by the BOEMRE District Supervisor to determine if pollution is occurring. 

Operators are required to install curbs, gutters, drip pans, and drains on platform and rig deck areas in 

a manner necessary to collect all greases, contaminants, and debris not authorized for discharge. The 

rules also explicitly prohibit the disposal of equipment, cables, chains, containers, or other materials into 

offshore waters. Portable equipment, spools or reels, drums, pallets, and other loose items must be 

marked in a durable manner with the owner’s name prior to use or transport over offshore waters. 

Smaller objects must be stored in a marked container when not in use. Operational discharges such as 

produced water and drilling muds and cuttings are regulated by USEPA through the National Pollutant 

Discharge Elimination System (NPDES) permit program. The BOEMRE may restrict the rate of drilling 

fluid discharge or prescribe alternative discharge methods. No petroleum-based substances, including 

diesel fuel, may be added to the drilling mud system without prior approval of the BOEMRE District 

Supervisor. 

Blowout Preventers 

A blowout preventer (BOP) is a complex of choke lines and hydraulic rams mounted atop the well 

head that can seal off the casing of a well by remote control at the surface. There are different types of 

BOP’s. A pipe ram closes on the drill pipe by pinching it, but it cannot seal on open hole. A blind ram is 

a straight-edged rams used to close an open hole. The BOP’s were invented in the early-1920’s and have 

been instrumental in ending dangerous, costly, and environmentally damaging oil gushers. The BOP’s 

have been required for OCS oil and gas operations from the time offshore drilling began in the late 

1940’s. There are two types: ram and annular (also called spherical). Rams were deployed in the 1920’s 

and annular preventers in the 1950’s. Rams are designed to seal an open hole by closing the wellbore 

with a sharp horizontal motion that may cut through casing or tool strings, as a last resort. An annular 

BOP closes around the drill string in a smooth simultaneous upward and inward motion. Both types are 

usually used together to create redundancy in a BOP stack. Because BOP’s are important for the safety of 
1-24 Central Planning Area Supplemental EIS 

the drilling crew, as well as the rig and the wellbore itself, BOP’s are regularly inspected, tested, and 

refurbished. The BOP’s are actuated as a last resort upon imminent threat to the integrity of the well or 

the surface rig (Chapter 3.2.2). New regulations for BOP’s were published on October 14, 2010, as 

described in Chapter 1.3.1 (Federal Register, 2010b). 

Oil-Spill Response Plans 

The BOEMRE’s responsibilities under the Oil Pollution Act of 1990 (OPA) include spill prevention, 

review, and approval of oil-spill response plans (OSRP’s); inspection of oil-spill containment and cleanup 

equipment; and ensuring oil-spill financial responsibility for facilities in offshore waters located seaward 

of the coastline or in any portion of a bay that is connected to the sea either directly or through one or 

more other bays. The BOEMRE regulations (30 CFR 254) require that all owners and operators of oilhandling, storage, or transportation facilities located seaward of the coastline submit an OSRP for 

approval. The term “coastline” means the line of ordinary low water along that portion of the coast that is 

in direct contact with the open sea and the line marking the seaward limit of inland waters. The term 

“facility” means any structure, group of structures, equipment, or device (other than a vessel), which is 

used for one or more of the following purposes: exploring for; drilling for; producing; storing; handling; 

transferring; processing; or transporting oil. A mobile offshore drilling unit (MODU) is classified as a 

facility when engaged in drilling or downhole operations. 

The regulation at 30 CFR 254.2 requires that an OSRP must be submitted and approved before an 

operator can use a facility. The BOEMRE can grant an exception to this requirement during the 

BOEMRE review of an operator’s submitted OSRP. In order to be granted this exception during this time 

period, an owner/operator must certify in writing to BOEMRE that it is capable of responding to a “worstcase” spill or the substantial threat of such a spill. To continue operations, the facility must be operated in 

compliance with the approved OSRP or the BOEMRE-accepted “worst-case” spill certification. Owners 

or operators of offshore pipelines are required to submit an OSRP for any pipeline that carries oil, 

condensate, or gas with condensate; pipelines carrying essentially dry gas do not require an OSRP. 

Current OSRP’s are required for abandoned facilities until they are physically removed or dismantled. 

The OSRP describes how an operator intends to respond to an oil spill. The OSRP may be sitespecific or regional (30 CFR 254.3). The term “regional” means a spill response plan that covers multiple 

facilities or leases of an owner or operator, including affiliates, which are located in the same BOEMRE 

GOM region. The subregional plan concept is similar to the regional concept, which allows leases or 

facilities to be grouped together for the purposes of (1) calculating response times, (2) determining 

quantities of response equipment, (3) conducting oil-spill trajectory analyses, (4) determining worst-case 

discharge scenarios, and (5) identifying areas of special economic and environmental importance that may 

be impacted and the strategies for their protection. The number and location of the leases and facilities 

allowed to be covered by a subregional OSRP will be decided by BOEMRE on a case-by-case basis 

considering the proximity of the leases or facilities proposed to be covered. NTL 2006-G21 includes 

guidance on the preparation and submittal of subregional OSRP’s. 

The Emergency Response Action Plan within the OSRP serves as the core of the BOEMRE-required 

OSRP. In accordance with 30 CFR 254, the Emergency Response Action Plan requires identification of 

(1) the qualified individual and the spill-response management team, (2) the spill-response operating 

team, (3) the oil-spill cleanup organizations under contract for response, and (4) the Federal, State, and 

local regulatory agencies that an owner/operator must notify or that they must consult with to obtain sitespecific environmental information when an oil spill occurs. The OSRP is also required to include an 

inventory of appropriate equipment and materials, their availability, and the time needed for deployment, 

as well as information pertaining to dispersant use, in situ burning, a worst-case discharge scenario, 

contractual agreements, and training and drills. The response plan must provide for response to an oil 

spill from their facility and the operator must immediately carry out the provisions of the plan whenever 

an oil spill from the facility occurs. The OSRP must be in compliance with the National Contingency 

Plan and the Area Contingency Plan(s) (ACP). The operator is also required to carry out the training, 

equipment testing, and periodic drills described in the OSRP. All BOEMRE-approved OSRP’s must be 

reviewed at least every 2 years. In addition, revisions must be submitted to BOEMRE within 15 days 

whenever 
The Proposed Action 1-25 

(1) a change occurs that appreciably reduces an owner/operator’s response capabilities; 

(2) a substantial change occurs in the worst-case discharge scenario or in the type of oil 

being handled, stored, or transported at the facility; 

(3) there is a change in the name(s) or capabilities of the oil-spill removal organizations 

cited in the OSRP; or 

(4) there is a change in the applicable ACP’s. 

As a result of the DWH event, although BOEMRE is not requiring the submission of revised OSRP’s 

at this time, the Agency will provide guidance regarding additional information that operators should 

submit regarding spill response and surface containment in light of the “worst case” discharge 

calculations that are now required by the regulations and as clarified in NTL 2010-N06, “Information 

Requirements for Exploration Plans, Development and Production Plans, and Development Operations 

Coordination Documents on the OCS,” which became effective on June 18, 2010. This NTL provides 

clarification of the regulations requiring a lessee or operator to submit supplemental information for new 

or previously submitted EP’s, development and production plans (DPP’s), or DOCD’s. The required 

supplemental information includes the following: (1) a description of the blowout scenario as required by 

30 CFR 250.213(g) and 250.243(h); (2) a description of their assumptions and calculations used in 

determining the volume of the worst-case discharge required by 30 CFR 250.219(a)(2)(iv) (for EP’s) or 

30 CFR 250.250(a)(2)(iv) (for DPP’s and DOCD’s); and (3) a description of the measures proposed that 

would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct 

effective and early intervention in the event of a blowout, including the arrangements for drilling relief 

wells and any other measures proposed. The early intervention methods could actually include the 

surface and subsea containment resources that BOEMRE announced in NTL 2010-N10, which states that 

BOEMRE will begin reviewing to ensure that the measures are adequate to promptly respond to a 

blowout or other loss of well control. 

Additionally, to address new improved containment systems, NTL 2010-N10, “Statement of 

Compliance with Applicable Regulations and Evaluation of Information Demonstrating Adequate Spill 

Response and Well Containment Resources,” became effective on November 8, 2010. This NTL applies 

only to operators conducting operations using subsea or surface BOP’s on floating facilities. It clarifies 

the regulations that lessees and operators submit a statement signed by an authorized company official 

with each application for a well permit, indicating that they will conduct all of their authorized activities 

in compliance with all applicable regulations, including the Increased Safety Measures Regulations at 

75 FR 63346. The NTL also informs lessees that BOEMRE will be evaluating whether or not each 

operator has submitted adequate information demonstrating that it has access to and can deploy surface 

and subsea containment resources that would be adequate to promptly respond to a blowout or other loss 

of well control. Although the NTL does not provide that operators submit revised Oil Spill Response 

Plans (OSRP’s) that include this containment information at this time, operators were notified of 

BOEMRE’s intention to evaluate the adequacy of each operator to comply in the operator’s current 

OSRP; therefore, there is an incentive for voluntary compliance. 

Financial Responsibility 

The responsible party for covered offshore facilities (COF’s) may have to demonstrate oil spill 

financial responsibility (OSFR), as required by 30 CFR 253. These regulations implement the OSFR 

requirements of Title I of OPA, as amended. Penalties for noncompliance with these requirements are 

covered at 30 CFR 250.51 and in NTL 2008-N05, “Guidelines for Oil Spill Financial Responsibility for 

Covered Facilities.” A COF, as defined in 30 CFR 253.3, is any structure and all of its components 

(including wells completed at the structure and the associated pipelines), equipment, pipeline, or device 

(other than a vessel or other than a pipeline or deepwater port licensed under the Deepwater Port Act of 

1974) used for exploring, drilling, or producing oil, or for transporting oil from such facilities. The 

BOEMRE ensures that each responsible party has sufficient funds for removal costs and damages 

resulting from the accidental release of liquid hydrocarbons into the environment for which the 

responsible party is liable. 
1-26 Central Planning Area Supplemental EIS 

Air Emissions 

The OCSLA (43 U.S.C. 1334(a)(8)) requires the Secretary of the Interior to promulgate and 

administer regulations that comply with the National Ambient Air Quality Standards (NAAQS), pursuant 

to the Clean Air Act (CAA) (42 U.S.C. 7401 et seq.), to the extent that authorized activities significantly 

affect the air quality of any State. Under provisions of the CAA Amendments (CAAA) of 1990, the 

USEPA Administrator has jurisdiction and, in consultation with the Secretary of the Interior and the 

Commandant of the Coast Guard, established the requirements to control air pollution in OCS areas of the 

Pacific, Atlantic, Arctic, and eastward of 87.5o W. longitude in the GOM. Air quality in the OCS area 

westward of 87.5o W. longitude in the Gulf is under BOEMRE jurisdiction. 

For OCS air emission sources located east of 87.5o W. longitude and within 25 mi (40 km) of the 

States’ seaward boundaries, the requirements are the same as would be applicable if the source were 

located in the corresponding onshore area. The USEPA requirements for these OCS areas are at 40 CFR 

55, Appendix A. For air emission sources located east of 87.5o W. longitude and more than 25 mi 

(40 km) from the States’ seaward boundaries, sources are subject to Federal requirements for Prevention 

of Significant Deterioration (PSD). The USEPA regulations also establish procedures that allow the 

USEPA Administrator to exempt any OCS source from an emissions control requirement if it is 

technically infeasible or poses unreasonable threat to health or safety. 

The BOEMRE issued NTL 2009-N11 to clarify that BOEMRE’s regulatory authority and the 

implementing regulations in 30 CFR Subpart C apply only to those air emission sources in the Gulf of 

Mexico westward of 87.5o W. longitude. The regulated pollutants include carbon monoxide, suspended 

particulates, sulphur dioxide, nitrogen oxides, total hydrocarbons, and volatile organic compounds. All 

new or supplemental EP’s and DOCD’s must include air emissions information sufficient to determine 

whether an air quality review is required (30 CFR 250.218 and 250.49). The BOEMRE regulations can 

require a review of air quality emissions to determine if the projected emissions from a facility result in 

onshore ambient air concentrations above BOEMRE significance levels and to identify appropriate 

emissions controls to mitigate potential onshore air quality degradation. 

The BOEMRE uses a two-level hierarchy of evaluation criteria to evaluate potential impacts of 

offshore emission sources to onshore areas. The evaluation criteria are the exemption level and the 

significance level. If the proposed activities exceed the criteria at the first (exemption) level, the 

evaluation moves to the significance level criteria. The initial evaluation compares the worst-case 

emissions to the BOEMRE exemption criteria. This corresponds to the USEPA screening step, where the 

proposed activity emissions are checked against the screening thresholds or “exemption levels.” If the 

proposed activity emissions are below the exemption levels, the proposed action is exempt from further 

air quality review. 

If exemption levels are exceeded, then the second step requires refined modeling using the Offshore 

and Coastal Dispersion (OCD) Model. The results from the OCD Model, the modeled potential onshore 

impacts, are compared with BOEMRE significance levels. If the significance levels are exceeded in an 

attainment area, an area that meets the NAAQS, the operator would be required to apply best available 

control technology to the emissions source. If the affected area is classified as nonattainment, further 

emission reductions or offsets may be required. Projected contributions to onshore pollutant 

concentrations are also subject to the same limits as USEPA applies to the onshore areas under their PSD 

program. 

Flaring/Venting 

Flaring is the controlled burning of natural gas, and venting is releasing gas directly into the 

atmosphere without burning. Flaring/venting may be necessary to remove potentially damaging 

completion fluids from the wellbore and to provide sufficient reservoir data for the operator to evaluate 

reservoir development options during unloading/testing operations and/or in emergency situations. The 

BOEMRE regulates flaring/venting to minimize the loss of revenue producing natural gas resources. The 

BOEMRE regulations (30 CFR 250.1160) allow, without prior BOEMRE approval, flaring or venting of 

natural gas on a limited basis under certain specified conditions. Regulations permit more extensive 

flaring/venting with prior approval from BOEMRE. Records must always be prepared by the operator for 

all flaring/venting, and justification must be provided for flaring/venting not expressly authorized by 

BOEMRE regulations. 
The Proposed Action 1-27 

Hydrogen Sulfide Contingency Plans 

The operator of a lease must request a BOEMRE area classification for the presence of hydrogen 

sulfide (H2S) gas. The BOEMRE classifies areas for proposed operations as (1) H2S absent, (2) H2S 

present, or (3) H2S unknown. 

All OCS operators concerned with the production of sour (contains H2S) hydrocarbons that could 

result in atmospheric H2S concentrations above 20 parts per million are required to file an H2S 

contingency plan with BOEMRE. This plan must include the 30 CFR 250 requirements that are intended 

to ensure workers safety at the production facility and provide contingencies for; simultaneous drilling, 

well-completion, well-workovers, and production operations. The NTL 2009-G31, “Hydrogen Sulfide 

(H2S) Requirements,” provides clarification, guidance, and information regarding BOEMRE’s H2S 

regulations at 30 CFR 250. 

Archaeological Resources Regulation 

Bottom-disturbing operations such as well placement, anchoring, and pipelaying activities can lead to 

damage to any resources that reside on the seabed, particularly archaeological resources such as historic 

shipwrecks. The archaeological resources regulation at 30 CFR 250.194 grants authority in certain cases 

to each BOEMRE Regional Director to require that archaeological reports be submitted with the EP, 

DOCD, or DPP where deemed necessary. The technical requirements of the archaeological resource 

reports are detailed in NTL 2005-G07, “Archaeological Resource Surveys and Reports.” If the evidence 

from the operator’s geophysical survey and/or archaeological report suggests that an archaeological 

resource may be present, the lessee must either locate the site of any operation so as not to adversely 

affect the area where the archaeological resource may be, demonstrate that an archaeological resource 

does not exist, or demonstrate that archaeological resources will not be adversely affected by operations. 

If the lessee discovers any archaeological resource while conducting approved operations, operations 

must be immediately stopped and the discovery reported to the BOEMRE Regional Supervisor, Office of 

Leasing and Environment, within 48 hours of its discovery. 

High-resolution surveys provide an effective tool that analysts use to identify and help protect 

archaeological resources; however, such survey coverage is often not available for all areas of the GOM, 

particularly in deeper water where oil and gas activities are increasing and where more shipwrecks are 

being identified. As part of the environmental reviews conducted for postlease activities, available 

information will be evaluated regarding the potential presence of archaeological resources within the 

proposed action area to determine if mitigation is warranted. 

Coastal Zone Management Consistency Review and Appeals for Plans 

The Coastal Zone Management Act (CZMA) places requirements on any applicant for an OCS plan 

that describes in detail Federal license or permit activities affecting any coastal use or resource, in or 

outside of a State’s coastal zone. The applicant must provide in the OCS plan submitted to BOEMRE a 

certification and necessary data and information for the State to determine that the proposed activities 

comply with the enforceable policies of the States’ approved coastal management program, and that such 

activities will be consistent to the maximum extent practicable (16 U.S.C. 1456(c)(3)(A) and 15 CFR 

930.76). 

Except as provided in 15 CFR 930.60(a), State agency review of the consistency certification begins 

when the State receives the certification and information required pursuant to 15 CFR 930.76(a) and (b). 

Only missing information can be used to delay the commencement of State agency review, and a request 

for information and data that are not required by 15 CFR 930.76 will not extend the date of 

commencement of review (15 CFR 930.58). Under the CZMA, each State with an approved CMP may 

require information that is different from that specifically outlined in these regulations. All of the Gulf 

States have approved CMP’s. Requirements for the CZM consistency information for Texas, Louisiana, 

Mississippi, Alabama, and Florida are found at 30 CFR 250.226 and 250.260, and are given in NTL’s 

2006-G21, “Regional and Subregional Oil Spill Response Plans”; 2007-G20, “Coastal Zone Management 

Program Requirements for OCS Right-of-way Pipeline Applications;” 2008-G04, “Information 

Requirements for Exploration Plans and Development Operations Coordination Documents”; and 

2009-G27, “Submitting Exploration Plans and Development Coordination Documents.” In accordance 
1-28 Central Planning Area Supplemental EIS 

with the requirements of 15 CFR 930.76, BOEMRE’s Gulf of Mexico OCS Region sends copies of an 

OCS plan, including the consistency certification and other data and necessary information, to the 

designated State CMP agency by receipted mail or other approved communication. If no State-agency 

objection is submitted by the end of the consistency review period, BOEMRE shall presume consistency 

concurrence by the State (15 CFR 930.78 (b)). The BOEMRE can require modification of a plan if the 

operator has agreed to certain requirements requested by the State. 

If BOEMRE receives a written consistency objection from the State, BOEMRE will not approve any 

activity described in the OCS plan unless (1) the operator amends the OCS plan to accommodate the 

objection, concurrence is subsequently received or conclusively presumed; (2) upon appeal, the Secretary 

of Commerce, in accordance with 15 CFR 930 Subpart H, finds that the OCS plan is consistent with the 

objectives or purposes of the CZMA or is necessary in the interest of national security; or (3) the original 

objection is declared invalid by the courts. 

Best Available and Safest Technologies 

To assure that oil and gas exploration, development, and production activities on the OCS are 

conducted in a safe and pollution-free manner, 43 U.S.C. 1347(b) of the OCSLA, as amended, requires 

that all OCS technologies and operations use the best available and safest technology (BAST) whenever 

practical. The Director may require additional BAST measures to protect safety, health, and the 

environment, if it is economically feasible and the benefits outweigh the costs. Conformance to the 

standards, codes, and practices referenced in or required under the authority of 30 CFR 250 is considered 

the application of BAST. These standards, codes, and practices include requirements for state-of-the-art 

drilling technology, production safety systems, oil and gas well completions, oil-spill response plans, 

pollution-control equipment, and specifications for platform/structure designs. The BOEMRE conducts 

periodic offshore inspections, and continuously and systematically reviews OCS technologies to ensure 

that the best available and safest technologies are applied to OCS operations. The BAST is not required 

when BOEMRE determines that the incremental benefits are clearly insufficient to justify increased costs; 

however, it is the responsibility of an operator of an existing operation to demonstrate why application of 

a new technology would not be feasible. This requirement is applicable to equipment and procedures 

that, if failed, would have a significant effect on safety, health, or the environment, unless benefits clearly 

do not justify the cost (30 CFR 250.107(c) and (d)). 

The BAST concept is addressed in the BOEMRE, Gulf of Mexico OCS Region by a continuous effort 

to locate and evaluate the latest technologies and to report on these advances at periodic Regional 

Operations Technology Assessment Committee (ROTAC) meetings. A part of the BOEMRE staff has an 

ongoing function to evaluate various vendors and industry representatives’ innovations and improvements 

in techniques, tools, equipment, procedures, and technologies applicable to oil and gas operations 

(drilling, producing, completion, and workover operations). This information is provided to BOEMRE 

district personnel at ROTAC meetings. The requirement for the use of BAST has been, for the most part, 

an evolutionary process whereby advances in equipment, technologies, and procedures have been 

integrated into OCS operations over a period of time. Awareness by both BOEMRE inspectors and the 

OCS operators of the most advanced equipment and technologies has resulted in the incorporation of 

these advances into day-to-day operations. An example of such an equipment change that evolved over a 

period of time would be the upgrading of diverter systems on drilling rigs from the smaller diameter 

systems of the past to the large-diameter, high-capacity systems found on drilling rigs operating on the 

OCS today. 

Production Facilities 

The BOEMRE’s regulations governing oil and gas production safety systems are found in 30 CFR 

250 Subpart H. Production safety equipment used on the OCS must be designed, installed, used, 

maintained, and tested in a manner to assure the safety and protection of the human, marine, and coastal 

environments. All tubing installations open to hydrocarbon-bearing zones below the surface must be 

equipped with safety devices that will shut off the flow from the well in the event of an emergency, unless 

the well is incapable of flowing. Surface- and subsurface-controlled safety valves and locks must 

conform to the requirements of 30 CFR 250.801. All surface production facilities, including separator 

and treatment tanks, compressors, headers, and flowlines must be designed, installed, and maintained in a 
The Proposed Action 1-29 

manner that provides for efficiency, safety of operations, and protection of the environment. Production 

facilities also have stringent requirements concerning electrical systems, flowlines, engines, and 

firefighting systems. The safety-system devices are tested by the lessee at specified intervals and must be 

in accordance with API RP 14 C Appendix D and other measures. 

Personnel Training and Education 

An important factor in ensuring that offshore oil and gas operations are carried out in a manner that 

emphasizes operational safety and minimizes the risk of environmental damage is the proper training of 

personnel. Under 30 CFR 250.Subpart O, BOEMRE has outlined well control and production safety 

training program requirements for lessees operating on the OCS. The goal of the regulation (30 CFR 

250.1501) is safe and clean OCS operations. Lessees must ensure that their employees and contract 

personnel engaged in well control or production safety operations understand and can properly perform 

their duties. To accomplish this, the lessee must establish and implement a training program so that all of 

their employees are trained to competently perform their assigned well control and production safety 

duties. The lessee must also verify that their employees understand and can perform the assigned duties. 

The mandatory Drilling Well-Control Training Program was instituted by this Agency in 1979. In 

1983, the mandatory Safety Device Training Program was established to ensure that personnel involved 

in installing, inspecting, testing, and maintaining safety devices are qualified. As a preventive measure, 

all offshore personnel must be trained to operate oil-spill cleanup equipment, or the lessee must retain a 

trained contractor(s) to operate the equipment for them. In addition, BOEMRE offers numerous technical 

seminars to ensure that personnel are capable of performing their duties and are incorporating the most 

up-to-date safety procedures and technology in the petroleum industry. In 1994, the Office of Safety 

Management created this Agency’s Offshore Training Institute to develop and implement an inspector 

training program. The Institute introduced state-of-the-art multimedia training to the inspector work force 

and has produced a series of interactive computer training modules. 

Structure Removal and Site Clearance 

During exploration, development, and production operations, temporary and permanent equipment 

and structures are often required to be embedded into or placed onto the seafloor around activity areas. In 

compliance with Section 22 of BOEMRE’s Oil and Gas Lease Form (MMS-2005) and OCSLA 

regulations (30 CFR 250.1710—Wellheads/Casings and 30 CFR 250.1725—Platforms and Other 

Facilities), operators need to remove seafloor obstructions from their leases within 1 year of lease 

termination or after a structure has been deemed obsolete or unusable. These regulations also require the 

operator to sever bottom-founded objects and their related components at least 5 m (15 ft) below the 

mudline (30 CFR 250.1716(a)—Wellheads/Casings and 30 CFR 250.1728(a)—Platforms and Other 

Facilities). The severance operations are generally categorized as explosive or nonexplosive. 

Chapter 1.5 of the Multisale EIS describes regulations, reporting guidelines, and specific mitigation 

measures developed through consultation, pursuant to Section 7 of the ESA and the MMPA, concerning 

potential impacts on endangered and threatened species associated with explosive severance activities 

conducted during the structure-removal operations. All of the current terms and conditions of structure 

and well removal activities are outlined in NTL 2010-G05, “Decommissioning Guidance for Wells and 

Platforms,” which became effective on October 15, 2010.

Marine Protected Species NTL’s 

Three NTL’s that were issued in 2007 advise operators in measures designed to reduce impacts to 

Marine Protected Species: NTL 2007-G02, “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program”; NTL 2007-G03, “Marine Trash and Debris Awareness and 

Elimination”; and NTL 2007-G04, “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting.” The provisions outlined in these NTL’s apply to all existing and future oil and gas operations 

in the Gulf of Mexico OCS. 

The NTL 2007-G02, “Implementation of Seismic Survey Mitigation Measures and Protected Species 

Observer Program,” provides guidance to protect marine mammals and sea turtles during seismic 

operations. This NTL clarifies how operators should implement seismic survey mitigation measures, 
1-30 Central Planning Area Supplemental EIS 

including ramp-up procedures, the use of a minimum sound source, airgun testing. and protected species 

observation and reporting. The measures contained in this NTL apply to all on-lease surveys conducted 

under 30 CFR 250 and to all off-lease surveys conducted under 30 CFR 251. 

The NTL 2007-G03, “Marine Trash and Debris Awareness and Elimination,” provides guidance to 

prevent intentional and/or accidental introduction of debris into the marine environment. Operators are 

prohibited from deliberately discharging containers and other similar materials (i.e., trash and debris) into 

the marine environment (30 CFR 250.300(a) and (b)(6)) and are required to make durable identification 

markings on equipment, tools, containers (especially drums), and other material (30 CFR 250.300(c)). 

The intentional jettisoning of trash has been the subject of strict laws such as the International Convention 

for the Prevention of Pollution from Ships (MARPOL) Annex V and the Marine Plastic Pollution 

Research and Control Act, and regulations imposed by various agencies including USCG and USEPA. 

These USCG and USEPA regulations require that operators become more proactive in avoiding the 

accidental loss of solid-waste items by developing waste management plans, posting informational 

placards, manifesting trash sent to shore, and using special precautions such as covering outside trash bins 

to prevent accidental loss of solid waste. The NTL 2007-G03 states that marine debris placards must be 

posted in prominent places on all fixed and floating production facilities that have sleeping or food 

preparation capabilities and on mobile drilling units. Operators must also ensure that all of their offshore 

employees and those contractors actively engaged in their offshore operations complete annual training 

that includes (1) viewing a training video or slide show (specific options are outlined in the NTL) and (2) 

receiving an explanation from the lessee company’s management that emphasizes their commitment to 

the NTL’s provisions. An annual report that describes the marine trash and debris awareness training 

process and certifies that the training process has been followed for the previous calendar year is to be 

provided to BOEMRE by January 31 of each year. 

The NTL 2007-G04, “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting,” 

explains how operators must implement measures to minimize the risk of vessel strikes to protected 

species and must report observations of injured or dead protected species. Vessel operators and crews 

must maintain a vigilant watch for marine protected species and slow down or stop their vessel to avoid 

striking protected species. Crews must report sightings of any injured or dead protected species (marine 

mammals and sea turtles) immediately, regardless of whether the injury or death is caused by their vessel, 

to the Marine Mammal and Sea Turtle Stranding Hotline or the Marine Mammal Stranding Network. In 

addition, if it was the operator’s vessel that collided with a protected species, BOEMRE must be notified 

within 24 hours of the strike. 

Rigs-to-Reefs 

Rigs-to-Reefs (RTR) is a term for converting obsolete, nonproductive offshore oil and gas platforms 

to designated artificial reefs (Dauterive, 2000). Disposal of obsolete offshore oil and gas platforms is not 

only a financial liability for the oil and gas industry but it can be a loss of productive marine habitat. The 

use of obsolete oil and gas platforms for reefs has proven to be highly successful. Their availability, 

design profile, durability, and stability provide a number of advantages over the use of traditional 

artificial reef materials. To capture this valuable fish habitat, the States of Louisiana, Texas, and 

Mississippi, in 1986, 1989, and 1999, respectively, passed enabling legislation and signed into law a RTR 

program to coincide with their respective States’ Artificial Reef Plan. Alabama and Florida have no RTR 

legislation. The State laws set up a mechanism to transfer ownership and liability of the platform from oil 

and gas companies to the State when the platform ceases production and the lease is terminated. The 

company (donor) saves money by donating a platform to the State (recipient) for a reef rather than 

scrapping the platform onshore. The industry then donates 50 percent of the savings to the State, which is 

put toward the State’s artificial reef program. Since the inception of the RTR program, more than 300 

retired platforms have been donated and used as reefs in the GOM. 

1.6. OTHER OCS-RELATED ACTIVITIES

The BOEMRE has programs and activities that are OCS related but not specific to the oil and gas 

leasing process or to the management of exploration, development, and production activities. These 

programs include both environmental and technical studies, and cooperative agreements with other 
The Proposed Action 1-31 

Federal and State agencies for NEPA work, joint jurisdiction over cooperative efforts, inspection 

activities, and regulatory enforcement. The BOEMRE also participates in industry research efforts and 

forums. 

Environmental Studies Program 

The Environmental Studies Program (ESP) was established in 1973 in accordance with Section 20 of 

the OCSLA. The goals of the ESP are to obtain environmental and socioeconomic information that can 

be used to assess the potential and real effects of the GOM OCS natural gas and oil program. As a part of 

the ESP, the Gulf of Mexico OCS Region has funded more than 350 completed or ongoing environmental 

studies. The types of studies funded include 

 literature reviews and baseline studies of the physical, chemical, and biological 

environment of the shelf; 

 literature review and studies of the physical, chemical, and biological environment of 

deep water (>300 m or 1,000 ft); 

 studies of the socioeconomic impacts along the Gulf Coast; and 

 studies of the effects of oil and gas activities on the marine environment. 

A list of the Gulf of Mexico OCS Region’s studies published from 2006 to the present is presented in 

Appendix C. Studies completed since 1974 are available on the BOEMRE, Gulf of Mexico OCS 

Region’s Internet website under “Environmental Program.” The BOEMRE’s Environmental Studies 

Program Information System (ESPIS) provides immediate access to all completed BOEMRE studies. 

The ESPIS is a searchable, web-based, full-text retrieval system allowing users to view online or to 

download the complete text of any completed ESP report. A complete list of all ongoing Gulf of Mexico 

OCS Region studies is available on the BOEMRE Internet website. Each listing not only describes the 

research being conducted but also shows the institution performing the work, the cost of the effort, 

timeframe, and any associated publications, presentations, or affiliated websites. 

The ESP funds studies to obtain information needed for NEPA assessment and the management of 

environmental and socioeconomic impacts on the human, marine, and coastal environments that may be 

affected by OCS oil and gas development. The ESP studies were used by BOEMRE’s Gulf of Mexico 

OCS Region analysts to prepare this document. While not all of the Gulf of Mexico OCS Region’s 

studies are specifically referenced in this document, they were used by analysts as input into their 

analyses. The information in ESP studies is also used by decisionmakers to manage and regulate 

exploration, development, and production activities on the OCS. 

Technology Assessment & Research Program 

The Technology Assessment & Research (TA&R) Program supports research associated with 

operational safety and pollution prevention as well as oil-spill response and cleanup capabilities. The 

TA&R Program is comprised of two functional research activities: (1) operational safety and engineering 

research (topics such as air quality, decommissioning, and mooring and anchoring); and (2) oil-spill 

research (topics such as behavior of oil, chemical treating agents, and in situ burning of oil). The TA&R 

Program has four primary objectives. 

 Technical Support—Providing engineering support in evaluating industry operational 

proposals and related technical issues and in ensuring that these proposals comply 

with applicable regulations, rules, and operational guidelines and standards. 

 Technology Assessment—Investigating and assessing industry applications of 

technological innovations and ensuring that governing BOEMRE regulations, rules, 

and operational guidelines ensure the use of BAST (Chapter 1.5, New and Unusual 

Technology). 
1-32 Central Planning Area Supplemental EIS 

 Research Catalyst—Promoting and participating in industry research initiatives in the 

fields of operational safety, engineering research, and oil-spill response and cleanup 

research. 

 International Regulations—Supporting international cooperative efforts for research 

and development initiatives to enhance the safety of offshore oil and natural gas 

activities and the development of appropriate regulatory program elements 

worldwide. 

Interagency Agreements 

Memorandum of Understanding under NEPA 

Section 1500.5(b) of the CEQ implementing regulations (40 CFR 1500.5(b)) encourages agency 

cooperation early in the NEPA process. A Federal agency can be a lead, joint lead, or cooperating 

agency. A lead agency manages the NEPA process and is responsible for the preparation of an EIS; a 

joint lead Agency shares these responsibilities; and a cooperating agency that has jurisdiction by law and 

has special expertise with respect to any environmental issue shall participate in the NEPA process upon 

the request of the lead agency. 

When an agency becomes a Cooperating Agency, the cooperating and lead agencies usually enter into 

an MOU, previously called a Cooperating Agency Agreement. The Agreement details the responsibilities 

of each participating agency. The BOEMRE, as lead agency, has requested other Federal agencies to 

become cooperating agencies while other agencies have requested BOEMRE to become a cooperating 

agency (e.g., the Ocean Express Pipeline project). Some projects, such as major gas pipelines across 

Federal waters and projects under the Deepwater Port Act of 1974, can require cooperative efforts by 

multiple Federal and State agencies. 

The NOI included an invitation to other Federal agencies and State, tribal, and local governments to 

consider becoming cooperating agencies in the preparation of this Supplemental EIS. 

Memorandum of Understanding and Memoranda of Agreements between MMS 

(BOEMRE) and USCG 

Since BOEMRE and USCG have closely related jurisdiction over different aspects of safety and 

operations on the OCS, the agencies have established a formal MOU that delineates lead responsibilities 

for managing OCS activities in accordance with the OCSLA, as amended, and OPA. The latest MOU, 

dated September 30, 2004, supersedes the August 1989 and December 1998 versions of the interagency 

agreement. The MOU is designed to minimize duplication and promote consistent regulation of facilities 

under the jurisdiction of both agencies. A Memorandum of Agreement (MOA), OCS No. 1—Agency 

Responsibilities, between BOEMRE and USCG, dated September 30, 2004, further clarifies the technical 

and process section of the BOEMRE/USCG MOU. The MOA requires the participating agencies to 

review their internal procedures and, where appropriate, revise them to accommodate the provisions of 

the September 2004 MOA. To facilitate coordination with USCG, BOEMRE has established a full-time 

position within the Office of Offshore Regulatory Programs to provide liaison between the agencies. 

Generally, the MOU identifies BOEMRE as the lead agency for matters concerning the equipment 

and operations directly involved in the production of oil and gas. These include, among others, design 

and operation of risers, permanent mooring foundations of the facility, drilling and well production and 

services, inspection and testing of all drilling-related equipment, and platform decommissioning. Issues 

regarding certain aspects of safe operation of the facility, its systems, and equipment generally fall under 

the jurisdiction of USCG. These include, among others, design of vessels, their sea-keeping 

characteristics, propulsion and dynamic positioning systems, supply and lightering procedures and 

equipment, utility systems, safety equipment and procedures, and pollution prevention and response 

procedures. In 2002, this Agency was authorized to inspect USCG-related safety items on fixed facilities 

on the OCS. 

Generally, the MOA identifies agency responsibilities (i.e., agency representatives for the purpose of 

keeping each other informed of issues, relevant applications, routine policy determinations and to 

coordinate joint activities), civil penalties (i.e., USCG refers civil penalty cases to BOEMRE), OSFR (i.e., 
The Proposed Action 1-33 

BOEMRE determines and provides OSFR-related information to USCG upon request), oil-spill 

preparedness and response planning (i.e., BOEMRE requires responsible parties to maintain approved oilspill-response plans consistent with Area Contingency Plans and the National Contingency Plan), oil-spill 

response (i.e., reporting all spills to the National Response Center and direct measures to abate sources of 

pollution from an OCS facility), accident investigations (i.e., BOEMRE and USCG responsible for 

investigating and preparing report of fires, spillage, injury, fatality and blowouts and collisions and 

allisions), and offshore facility system/subsystem responsibility matrix (identifies lead agency responsible 

for MODU, fixed, and floating systems and subsystems, and coordinates with other agencies as 

appropriate). 

On April 18, 2005, this Agency and USCG met to identify MOA’s that needed to be developed and to 

prioritize work. The following subject areas were selected: (a) civil penalties; (b) incident investigations; 

(c) offshore security; (d) oil-spill planning, preparedness, and response; (e) deepwater ports; (f) digital 

databases; (g) MODU’s; (h) fixed platforms; (i) floating platforms; (j) floating, production, storage, and 

offloading units (FPSO’s); and (k) incident reporting. Joint agency teams have been established to 

develop the MOA’s for the first five subject areas. In addition, an MOA is also being pursued to address 

renewable energy and alternate use of the OCS. The Civil Penalties MOA-OCS-02 was approved on 

September 12, 2006. The Oil Discharge Planning, Preparedness, and Response MOA-OCS-03 became 

effective on May 23, 2009, and the Incident Investigation MOA-OCS-05 became effective on March 27, 

2009. 
CHAPTER 2 

ALTERNATIVES INCLUDING THE PROPOSED ACTION
Alternatives Including the Proposed Action 2-3 

2. ALTERNATIVES INCLUDING THE PROPOSED ACTION 

This Supplemental EIS addresses one areawide oil and gas lease sale in the CPA of the Gulf of 

Mexico OCS (Figure 1-1), as scheduled in the current Outer Continental Shelf Oil and Gas Leasing 

Program: 2007-2012 (5-Year Program; USDOI, MMS, 2007a). The proposed action (proposed lease 

sale) includes regulations in place at the time a Record of Decision is made for this Supplemental EIS and 

lease stipulations. As a result of the DWH event, there are multiple groups and bodies that have been 

impaneled to offer recommendations on how OCS regulations may be changed (Table 2-1). Some of 

these inquiries have concluded their business and some have not. On October 14, 2010, the new interim 

final rules for OCS operations were published in the Federal Register (2010b). On October 15, 2010, the 

final rule for OCS safety and environmental management systems was published in the Federal Register

(2010a). Chapter 1.3.1 explains these regulatory changes, which are part of the proposed action and all 

alternatives. 

2.1. SUPPLEMENTAL EIS NEPA ANALYSIS

This Supplemental EIS tiers from the Multisale EIS and the 2009-2012 Supplemental EIS. Its 

purpose is to determine if new information is substantial enough to alter the conclusions stated in the 

Multisale EIS and the 2009-2012 Supplemental EIS and, if so, to disclose those changes. This includes 

all new information and not just that acquired since the DWH event. This Agency utilized the best 

information available derived from ongoing and past research to determine if the baseline condition for 

resources had changed since the Multisale EIS and the 2009-2012 Supplemental EIS due to the DWH 

event or any other factor. This Supplemental EIS presents an impartial analysis of new information that is 

available through sources open to Agency experts. 

This Supplemental EIS was prepared in consideration of the potential changes to the baseline 

conditions of the environmental, socioeconomic, and cultural resources that may have occurred as a result 

of the DWH event. These environmental resources include sensitive coastal environments and offshore 

benthic resources, marine mammals, sea turtles, coastal and marine birds, endangered and threatened 

species, and fisheries. This Supplemental EIS also considered the DWH event in the analysis of the 

potential alternatives of the proposed action. 

It must be understood that this Supplemental EIS analyzes the proposed action and alternatives for the 

proposed CPA lease sale. This is not an EIS on the DWH event, although information on this event will 

be analyzed as it applies to resources in the CPA. 

In regards to the DWH event, on March 8, 2011, BOEMRE was invited to be a Cooperating Agency 

by NOAA in the preparation of a Programmatic EIS to support development of a suite of preferred 

restoration alternatives to compensate for natural resource injuries resulting from the DWH event and the 

resulting oil spill. The Programmatic EIS is a separate action under the Natural Resource Damage 

Assessment (NRDA) process that will aid the Trustees in the effective planning for use of DWH 

restoration funds. The restoration planning process will be used to solicit public and agency comment to 

aid in restoration planning. The invitation was due to BOEMRE’s unique expertise or jurisdiction over 

activities and/or resources that may be impacted by restoration activities undertaken under the 

Programmatic EIS. The Programmatic EIS is a separate action that is not related to this Supplemental 

EIS. 

2.2. ALTERNATIVES, MITIGATING MEASURES, AND ISSUES

2.2.1. Alternatives 

2.2.1.1. Alternatives for Proposed Central Planning Area Lease Sale 216/222 

The following alternatives were included for analysis in the Multisale EIS and the 2009-2012 

Supplemental EIS and are described in detail in Chapter 2.4. As explained in Chapter 2.2.1.3., the Use 

of a Nomination and Tract Selection Leasing System Alternative was not included for analysis in this 

Supplemental EIS because of an ongoing BOEMRE study on alternative approaches to leasing. 
2-4 Central Planning Area Supplemental EIS 

Alternative A—The Proposed Action: This alternative would offer for lease all unleased blocks 

within the CPA for oil and gas operations (Figure 2-1), except for the following: 

(1) blocks directly south of Florida and within 100 mi of the Florida coast (north of the 

easternmost portion of the proposed CPA lease sale area as shown on Figure 1-1); 

and 

(2) blocks that are beyond the U.S. Exclusive Economic Zone in the area known as the 

northern portion of the Eastern Gap. 

The CPA sale area encompasses about 63 million ac of the CPA’s 66.3 million ac. Approximately 

37.1 million ac (59%) of the CPA sale area is currently unleased. The estimated amount of resources 

projected to be developed as a result of the proposed CPA lease sale is 0.801-1.624 BBO and 3.332-6.560 

Tcf of gas. 

Alternative B—The Proposed Action Excluding the Unleased Blocks Near Biologically Sensitive 

Topographic Features: This alternative would offer for lease all unleased blocks in the CPA, as 

described for the proposed action (Alternative A), with the exception of any unleased blocks subject to 

the Topographic Features Stipulation. 

Alternative C—The Proposed Action Excluding the Unleased Blocks within 15 Miles of the Baldwin 

County, Alabama, Coast: This alternative would offer for lease all unleased blocks in the CPA, as 

described for the proposed action (Alternative A), with the exception of any unleased blocks within 15 mi 

(24 km) of the Baldwin County, Alabama, coast. 

Alternative D—No Action: This alternative is the cancellation of the proposed CPA lease sale. The 

opportunity for development of the estimated 0.801-1.624 BBO and 3.332-6.560 Tcf of gas that could 

have resulted from the proposed CPA lease sale would be precluded or postponed. Any potential 

environmental impacts resulting from the proposed lease sale would not occur or would be postponed. 

This is also analyzed in the EIS for the 5-Year Program on a nationwide programmatic level. 

2.2.1.2. Alternatives Considered but Not Analyzed 

Alternatives to Areawide Leasing 

The Multisale EIS forecasted a future analysis for Use of a Nomination and Tract Selection Leasing 

System Alternative for both a WPA and CPA proposed lease sale. Since the publication of the Multisale 

EIS, this Agency has contracted a study of leasing policy alternatives that may serve to further the many 

goals of the OCSLA. 

The study began in October 2007 and at that time was expected to take about 18 months to complete. 

This Agency received a final version of the original study in the third quarter of FY 2009. The study 

evaluated different leasing options, some pertaining to the alternative size of areas offered for leasing and 

some pertaining to alternative lease terms and conditions. Options for alternative sizes included areawide 

annual, areawide every other year, or 5 percent of areawide as a proxy for nomination scale. Options for 

alternative lease terms and conditions included different royalty rates, minimum bid or rental amounts, 

profit shares, work commitments, multi-round bidding, and shorter primary terms. No combination of 

options was provisionally found superior to the current system on all performance measures. The 

performance measures against which the alternatives were evaluated included expeditious and orderly 

development of resources, fair return for leased resources, promotion of competition, equitable sharing of 

the costs and benefits of offshore leasing, facilitation of regional planning, minimizing environmental 

risks, and maximizing social value. 

In January 2010, this Agency modified the original contract to have an additional scenario (growth in 

resource size from the most current estimates) run through the original contractor’s model. Then, after 

the DWH event, BOEMRE did a second contract modification to address scenarios involving a drilling 

pause and a delay in future lease sales such as is occurring now. When this additional work is delivered, 

BOEMRE will reconsider alternative leasing scenarios. Informed by this study and recent events, future 

leasing decisions could result in fewer sales, smaller sale sizes, or higher fees, any of which would more 

simply and directly serve many of the same purposes as tract nomination sales. The recommendations 

from multiple Secretarial and Presidential inquiries (Table 2-1) are likely to include stricter drilling and 
Alternatives Including the Proposed Action 2-5 

safety requirements that would need to be considered in conjunction with leasing system alternatives. It 

is possible that future leasing decisions could result directly or indirectly in fewer blocks leased per sale 

or fewer sales held per year, leading ultimately to fewer blocks drilled and developed. 

Pending completion of the revised scope of work for the alternative leasing system analysis within the 

wider context of possible or likely regulatory changes, BOEMRE believes that it is not appropriate to 

include the Use of a Nomination and Tract Selection Leasing System Alternative in this Supplemental 

EIS. 

2.2.2. Mitigating Measures 

The NEPA process is intended to help public officials make decisions that are based on their 

understanding of environmental consequences and to take actions that protect, restore, and enhance the 

environment. Agencies are required to identify and include in the proposed action all relevant and 

reasonable mitigation measures that could improve the action. In 1978, Section 1508.20 of CEQ defined 

mitigation as 

 Avoidance—Avoiding an impact altogether by not taking a certain action or part of 

an action. 

 Minimization—Minimizing impacts by limiting the intensity or magnitude of the 

action and its implementation. 

 Restoration—Rectifying the impact by repairing, rehabilitating, or restoring the 

affected environment. 

 Maintenance—Reducing or eliminating the impact over time by preservation and 

maintenance operations during the life of the action. 

 Compensation—Compensating for the impact by replacing or providing substitute 

resources or environments. 

2.2.2.1. Proposed Mitigating Measures Analyzed 

The potential mitigating measures included for analysis in this Supplemental EIS were developed as 

the result of scoping efforts over a number of years for the continuing OCS Program in the Gulf of 

Mexico. Eight lease stipulations (described in Chapter 2.3.1.3) are proposed for the CPA Lease Sale 

216/222—the Topographic Features Stipulation; the Live Bottom Stipulation; the Military Areas 

Stipulation; the Evacuation Stipulation; the Coordination Stipulation; the Blocks South of Baldwin 

County, Alabama, Stipulation; the Protected Species Stipulation; and the Law of the Sea Convention 

Royalty Payment Stipulation. The Law of the Sea Convention Royalty Payment Stipulation is applicable 

to the CPA lease sale even though it is not an environmental or military stipulation. 

These measures will be considered for adoption by the ASLM, under authority delegated by the 

Secretary of the Interior. The analysis of any stipulations as part of Alternative A does not ensure that the 

ASLM will make a decision to apply the stipulations to leases that may result from any proposed lease 

sale nor does it preclude minor modifications in wording during subsequent steps in the prelease process 

if comments indicate changes are necessary or if conditions change. 

Any stipulations or mitigation requirements to be included in a lease sale will be described in the 

ROD for that lease sale. Mitigating measures in the form of lease stipulations are added to the lease terms 

and are therefore enforceable as part of the lease. In addition, each exploration and development plan, as 

well as any pipeline applications that may result from the lease sale, will undergo a NEPA review, and 

additional project-specific mitigations are routinely applied as conditions of plan approval. The 

BOEMRE has the authority to monitor and enforce these conditions, and under 30 CFR 250 Subpart N, 

may seek remedies and penalties from any operator that fails to comply with the conditions of permit 

approvals, including stipulations and other mitigating measures. 
2-6 Central Planning Area Supplemental EIS 

2.2.2.2. Existing Mitigating Measures 

This section discusses only mitigating measures that would be applied by BOEMRE. Mitigating 

measures have been proposed, identified, evaluated, or developed through previous BOEMRE lease sale 

NEPA review and analysis. Many of these mitigating measures have been adopted and incorporated into 

regulations and/or guidelines governing OCS exploration, development, and production activities. All 

plans for OCS activities (e.g., exploration and development plans, pipeline applications, and structureremoval applications) go through rigorous BOEMRE review and approval to ensure compliance with 

established laws and regulations. Existing mitigating measures must be incorporated and documented in 

plans submitted to BOEMRE. Operational compliance of these mitigating measures is enforced through 

BOEMRE’s onsite inspection program. 

Mitigating measures that are a standard part of BOEMRE’s program ensure that the operations are 

always conducted in an environmentally sound manner (with an emphasis on minimizing any adverse 

impact of routine operations on the environment). For example, mitigating measures ensure site clearance 

procedures that eliminate potential snags to commercial fishing nets and that, as appropriate, may require 

surveys to detect and avoid archaeological sites and biologically sensitive areas such as pinnacles, 

topographic features, and chemosynthetic communities. 

Some BOEMRE-identified mitigating measures are incorporated into OCS operations through 

cooperative agreements or efforts with industry and various State and Federal agencies. These mitigating 

measures include NMFS’s Observer Program to protect marine mammals and sea turtles during explosive 

removals, development of methods of pipeline landfall to eliminate impacts to beaches or wetlands, and 

beach cleanup events. 

Site-specific mitigating measures are also applied by BOEMRE during plan and permit reviews. The 

BOEMRE realized that many of these site-specific mitigations were recurring and developed a list of 

“standard” mitigations. There are currently over 120 standard mitigations. The wording of a standard 

mitigation is developed by BOEMRE in advance and may be applied whenever conditions warrant. 

Standard mitigation text is revised as often as is necessary (e.g., to reflect changes in regulatory citations, 

agency/personnel contact numbers, and internal policy). Site-specific mitigation “categories” include the 

following: air quality; archaeological resources; artificial reef material; chemosynthetic communities; 

Flower Garden Banks; topographic features; hard bottoms/pinnacles; military warning areas and Eglin 

Water Test Areas (EWTA’s); Naval mine warfare areas; hydrogen sulfide; drilling hazards; remotely 

operated vehicle surveys; geophysical survey reviews; and general safety concerns. Site-specific 

mitigation “types” include the following: advisories; conditions of approval; hazard survey reviews; 

inspection requirements; notifications; post-approval submittals; reminders; and safety precautions. In 

addition to standard mitigations, BOEMRE may also apply nonrecurring mitigating measures that are 

developed on a case-by-case basis. 

The BOEMRE is continually revising applicable mitigations to allow the Gulf of Mexico Region to 

more easily and routinely track mitigation compliance and effectiveness. A primary focus of this effort is 

requiring post-approval submittal of information within a specified timeframe after a triggering event that 

is tracked by BOEMRE (e.g., end of operations reports for plans, construction reports for pipelines, and 

removal reports for structure removals). 

2.2.3. Issues 

Issues are defined by CEQ to represent those principal “effects” that an EIS should evaluate in-depth. 

Scoping identifies specific environmental resources and/or activities rather than “causes” as significant 

issues (CEQ Guidance on Scoping, April 30, 1981). The analysis in the EIS can then show the degree of 

change from present conditions for each issue due to the relevant actions related to the proposed action. 

Selection of environmental and socioeconomic issues to be analyzed was based on the following 

criteria: 

 issue is identified in CEQ regulations as subject to evaluation; 

 the relevant resource/activity was identified through agency expertise, through the 

scoping process, or from comments on past EIS’s; 
Alternatives Including the Proposed Action 2-7 

 the resource/activity may be vulnerable to one or more of the impact-producing 

factors associated with the OCS Program; a reasonable probability of an interaction 

between the resource/activity and impact-producing factor should exist; or 

 information that indicates a need to evaluate the potential impacts to a 

resource/activity has become available. 

2.2.3.1. Issues to be Analyzed 

Like the Multisale EIS and the 2009-2012 Supplemental EIS, this Supplemental EIS addresses issues 

related to potential impact-producing factors and the environmental and economic resources and activities 

that could be affected by OCS exploration, development, production, and transportation activities. A 

reevaluation of affected environmental resources based on the effects of the DWH event is warranted. 

The baseline condition of some resources has been changed, some to a greater degree than others, and 

preparation of this Supplemental EIS was judged by BOEMRE to be appropriate for this evaluation of the 

one remaining CPA lease sale in the 5-Year Program 

2.2.3.2. Issues Considered but Not Analyzed 

As previously noted, the CEQ regulations for implementing NEPA instruct agencies to adopt an early 

process (termed “scoping”) for determining the scope of issues to be addressed and for identifying 

significant issues related to a proposed action. As part of this scoping process, agencies shall identify and 

eliminate from detailed study the issues that are not significant to the proposed action or have been 

covered by prior environmental review. 

Through our scoping efforts, numerous issues and topics were identified for consideration in the 

Multisale EIS, the 2009-2012 Supplemental EIS, and this Supplemental EIS. After careful evaluation and 

study, the following categories were considered not to be significant issues related to the proposed action 

or that have been covered by prior environmental review. 

Program and Policy Issues 

Comments and concerns that relate to program and policy are issues under the direction of the 

Department of the Interior and/or BOEMRE, and their guiding regulations, statutes, and laws. The 

comments and concerns related to program and policy issues are not considered to be specifically related 

to the proposed action. Such comments are forwarded to the appropriate program offices for their 

consideration. Programmatic issues including expansion of the sale area, administrative boundaries, and 

royalty relief have been considered in the preparation of the EIS for the 5-Year Program. 

Revenue Sharing 

A number of comments were received on previous EIS’s from State and local governments, interest 

groups, and the general public stating that locally affected communities should receive an increased share 

of revenues generated by the OCS oil and gas leasing program. This increased revenue would act as 

mitigation of OCS-related impacts to coastal communities including impacts to Louisiana Highway 1 

(LA Hwy 1) and Lafourche Parish, Louisiana, from OCS-related activity at Port Fourchon. Comments 

and concerns that relate to the use and distribution of revenues are issues under the direction of the U.S. 

Congress or the Department of the Interior, and their guiding regulations, statutes, and laws. 

The BOEMRE distributes revenues collected from Federal mineral leases to special-purpose funds 

administered by Federal agencies; to States; and to the General Fund of the U.S. Department of the 

Treasury. Legislation and regulations provide formulas for the disbursement of these revenues. The 

distribution of revenues is discussed in Chapter 3.3.5.2 of the Multisale EIS. 

With the enactment of GOMESA, the Gulf producing States (i.e., Texas, Louisiana, Mississippi, and 

Alabama) and their coastal political subdivisions (CPS’s) were granted an increased share of offshore oil 

and gas revenue. Beginning in FY 2007, and thereafter, Gulf producing States and their CPS’s received 

37.5 percent of the qualified OCS revenue from new leases issued in the 181 Area in the EPA and the 

181 South Area. Beginning in FY 2016, and thereafter, Gulf producing States and their CPS’s will 
2-8 Central Planning Area Supplemental EIS 

receive 37.5 percent and the Land and Water Conservation Fund will receive 12.5 percent of qualified 

OCS revenue from new leases in the existing areas available for leasing, subject to a $500 million cap. 

The remaining 50 percent of qualified OCS revenues and revenues exceeding the $500 million cap will be 

distributed to the U.S. Treasury. 

The socioeconomic benefits and impacts to local communities are analyzed in Chapter 4 of this 

Supplemental EIS. 

2.3. PROPOSED CENTRAL PLANNING AREA LEASE SALE 216/222 

The following four alternatives were included for analysis in the Multisale EIS and 2009-2012 

Supplemental EIS. As explained in Chapter 2.2.3.2, the Use of a Nomination and Tract Selection 

Leasing System Alternative was not included for analysis in this Supplemental EIS because of an ongoing 

BOEMRE study on alternative approaches to leasing. 

2.3.1. Alternative A—The Proposed Action 

2.3.1.1. Description 

Alternative A would offer for lease all unleased blocks within the CPA (4.3 million ac) for oil and gas 

operations (Figure 1-1), except the following: 

(1) blocks directly south of Florida and within 100 mi of the Florida coast (north of the 

easternmost portion of the proposed CPA lease sale area as shown on Figure 1-1); 

and 

(2) blocks that are beyond the U.S. Exclusive Economic Zone in the area known as the 

northern portion of the Eastern Gap. 

The CPA sale area encompasses about 63 million ac of the CPA’s 66.3 million ac. Approximately 

37.1 million ac (59%) of the CPA sale area is currently unleased. The estimated amount of resources 

projected to be developed as a result of the proposed CPA lease sale is 0.801-1.624 BBO and 3.332-6.560 

Tcf of gas. 

The analyses of impacts summarized below and described in detail in Chapter 4 are based on the 

development scenario, which is a set of assumptions and estimates on the amounts, locations, and timing 

for OCS exploration, development, and production operations and facilities, both offshore and onshore. 

A detailed discussion of the development scenario and major related impact-producing factors is included 

in Chapter 3. 

2.3.1.2. Summary of Impacts 

Air Quality (Chapter 4.1.1.1) 

Emissions of pollutants into the atmosphere from the routine activities associated with the CPA 

proposed action are projected to have minimal impacts to onshore air quality because of the prevailing 

atmospheric conditions, emission heights, emission rates, and the distance of these emissions from the 

coastline. As indicated in the Gulf of Mexico Air Quality Study and other modeling studies, the proposed 

action would have only a small effect on ozone levels in ozone nonattainment areas and would not 

interfere with the States’ schedule for compliance with the National Ambient Air Quality Standards 

(NAAQS). Regulations, monitoring, mitigation, and the development of emissions-related technologies 

would ensure these levels stay within the NAAQS. 

Accidental events associated with the CPA proposed action that could impact air quality include spills 

of oil, natural gas, condensate, and refined hydrocarbons; H2S release; fire; and NAAQS air pollutants 

(i.e., SOx, NOx, VOC’s, CO, PM10, and PM2.5). Response activities that could impact air quality include 

emergency response vehicles, in-situ burning, the use of flares to burn gas and oil, and the use of 

dispersants applied from aircraft. Measurements taken during an in-situ burning show that a major 

portion of compounds was consumed in the burn; therefore, pollutant concentrations would be expected 
Alternatives Including the Proposed Action 2-9 

to be within the NAAQS. In a recent analysis of air in coastal communities, low levels of dispersants 

were identified. These response activities are temporary in nature and occur offshore; therefore, there are 

little expected impacts from these actions to onshore air quality. Accidents involving high concentrations 

of H2S could result in deaths as well as environmental damage. Regulations and NTL’s are in place to 

protect workers from H2S releases. Other emissions of pollutants into the atmosphere from accidental 

events as a result of the CPA proposed action are not projected to have significant impacts on onshore air 

quality because of the prevailing atmospheric conditions, emissions height, emission rates, and the 

distance of these emissions from the coastline. These emissions are not expected to have concentrations 

that would change onshore air quality classifications. 

Overall, since loss of well-control events and blowouts are rare and are of short duration, potential 

impacts to air quality are not expected to be significant, except in the rare case of a catastrophic event. 

The summary of vast amounts of data collected and additional studies will provide more information in 

the future. 

Although BOEMRE regulates the air emissions and air quality in the Gulf of Mexico region, at 

present, BOEMRE does not have an air quality model for the estimate of air concentrations from the 

distance of the OCS emission sources. Thus, BOEMRE relies on other government agencies for air 

quality assessment; their air quality models may not be appropriate for the assessment of air quality from 

the OCS emission sources. 

Water Quality (Chapter 4.1.1.2) 

Coastal Waters (Chapter 4.1.1.2.1) 

The primary impacting sources to water quality in coastal waters are point-source and storm-water 

discharges from support facilities, vessel discharges, and nonpoint-source runoff. These activities are not 

only highly regulated but are localized and temporary in nature. The impacts to coastal water quality 

from routine activities associated with the CPA proposed action should be minimal as long as all existing 

regulatory requirements are met. 

Accidental events associated with the CPA proposed action that could impact coastal water quality 

include spills of oil and refined hydrocarbons, releases of natural gas and condensate, and spills of 

chemicals or drilling fluids. The loss of well control, pipeline failures, collisions, or other malfunctions 

could also result in such spills. Although response efforts may decrease the amount of oil in the 

environment, the response efforts may also impact the environment. Natural degradation processes would 

also decrease the amount of spilled oil over time. For coastal spills, two additional factors that must be 

considered are the shallowness of the area and the proximity of the spill to shore. Over time, natural 

processes can physically, chemically, and biologically degrade oil. Chemicals used in the oil and gas 

industry are not a significant risk in the event of a spill because they are either nontoxic, used in minor 

quantities, or are only used on a noncontinuous basis. Spills from collisions are not expected to be 

significant because collisions occur infrequently. 

Offshore Waters (Chapter 4.1.1.2.2) 

During exploratory activities, the primary impacting sources to offshore water quality are discharges 

of drilling fluids and cuttings. During platform installation and removal activities, the primary impacting 

sources to water quality are sediment disturbance and temporarily increased turbidity. Impacting 

discharges during production activities are produced water and supply-vessel discharges. Existing 

regulations impose limits on the level of contaminants in these discharges. Pipeline installation can also 

affect water quality by sediment disturbance and increased turbidity. Service-vessel discharges might 

include water with oil concentration of approximately 15 ppm as established by regulatory standards. 

Any disturbance of the seafloor would increase turbidity in the surrounding water, but the increased 

turbidity should be temporary and restricted to the area near the disturbance. There are multiple Federal 

regulations and permit requirements that would decrease the magnitude of these activities. Impacts to 

offshore waters from routine activities associated with the CPA proposed action should be minimal as 

long as regulatory requirements are followed. 

Accidental events associated with the CPA proposed action that could impact offshore water quality 

include spills of oil and refined hydrocarbons, releases of natural gas and condensate, spills of chemicals 
2-10 Central Planning Area Supplemental EIS 

or drilling fluids, and loss of well control, pipeline failures, collisions, or other malfunctions that would 

result in such spills. Spills from collisions are not expected to be significant because collisions occur 

infrequently. Overall, loss of well control events and blowouts are rare events, and of short duration, so 

potential impacts to offshore water quality are not expected to be significant except in the rare case of a 

catastrophic event. Although response efforts may decrease the amount of oil in the environment, the 

response efforts may also impact the environment. Natural physical, chemical, and biological processes 

would decrease the amount of spilled oil over time through dilution, weathering, and degradation of the 

oil (NRC, 2003). Chemicals used in the oil and gas industry are not a significant risk for a spill because 

they are either nontoxic, used in minor quantities, or are only used on a noncontinuous basis. Although 

there is the potential for accidental events, the CPA proposed action would not significantly change the 

water quality of the Gulf of Mexico over a large spatial or temporal scale. 

Coastal Barrier Beaches and Associated Dunes (Chapter 4.1.1.3) 

Effects to coastal barrier beaches and associated dunes from pipeline emplacements, navigation 

channel use and dredging, and construction or continued use of infrastructure in support of the CPA 

proposed action are expected to be restricted to temporary and localized disturbances. The 0-1 pipeline 

landfall projected in support of the proposed action is not expected to cause significant impacts to barrier 

beaches because of the use of nonintrusive installation methods and regulations. New processing plants 

would not be expected to be constructed on barrier beaches. The proposed action may contribute to the 

continued use of existing facilities, which can add to erosion. Erosion control structures installed to 

protect a facility as attended may also accelerate erosion elsewhere in the vicinity. 

Maintenance dredging of barrier inlets and bar channels is expected to occur, which combined with 

channel jetties, causes minor and localized impacts on adjacent barrier beaches. This is due to permit 

regulations and mitigation efforts. The worst of these situations is found on the sediment-starved coasts 

of Louisiana, where sediments are largely organic. Despite the fact that maintenance dredging of barrier 

inlets and bar channels is required due to natural coastal sediment transport processes, the proposed action 

would account for a small percentage of these impacts. 

The CPA proposed action is not expected to adversely alter barrier beach configurations significantly 

beyond existing, ongoing impacts in localized areas. Strategic placement of dredged material from 

channel maintenance, channel deepening, and related actions can mitigate adverse impacts upon those 

localized areas. 

Because of the proximity of inshore spills to barrier islands and beaches, inshore spills pose the 

greatest threat. Such spills may result from either vessel collisions that release fuel and lubricants or from 

pipelines that rupture. Impacts of a nearshore spill would be considered short term in duration and minor 

in scope because the size of such a spill is projected to be small (coastal spills are assumed to be 5 bbl; 

Table 4-13 of the Multisale EIS). Offshore-based crude oil would be less in toxicity when it reaches the 

coastal environments. This is due to the distance from shore, the weather, the time oil remains offshore, 

and the dispersant used. Equipment and personnel used in cleanup efforts can generate the greatest direct 

impacts to the area. Close monitoring and restrictions on the use of bottom-disturbing equipment would 

be needed to avoid or minimize those impacts. 

Although the most current information did reveal that some of the barrier islands had experienced 

storm-induced reductions in beach shoreline elevations and erosion, the significance of this loss of 

protection is small in comparison with the overriding climatic forces. Therefore, this information would 

not alter the overall conclusion that impacts on barrier islands and beaches from accidental impacts 

associated with the CPA proposed action would be minimal. Should a spill other than a catastrophic spill 

contact a barrier beach, oiling is expected to be light and sand removal during cleanup activities 

minimized. No significant long-term impacts to the physical shape and structure of barrier beaches and 

associated dunes are expected to occur as a result of the CPA proposed action. The current lease sale 

would not pose a significant increase in risk to barrier island or beach resources. 

Wetlands (Chapter 4.1.1.4) 

The 0-2 km (0-1.2 mi) of onshore pipeline that could result from the proposed action would cause the 

loss of 0-8 ha (0-20 ac) of wetlands habitat. It is expected that these impacts would be reduced through 

mitigation, such as horizontal, directional (trenchless) drilling techniques to avoid damages to these 
Alternatives Including the Proposed Action 2-11 

sensitive wetland habitats. Although maintenance dredging of navigation channels and canals in the CPA 

is expected to occur, the proposed action is expected to contribute minimally to the need for this dredging. 

Alternative dredged-material disposal methods can be used to enhance and create wetlands. Secondary 

impacts to wetlands from the CPA proposed action would result from OCS-related vessel traffic 

contributing to the erosion and widening of navigation channels and canals. This would cause 

approximately 1 ha (3 ac) of landloss per year. Overall, the impacts to wetlands from routine activities 

associated with the CPA proposed action are expected to be low due to the small length of projected 

onshore pipelines, the minimal contribution to the need for maintenance dredging, and because of the 

mitigation measures that would be used to further reduce these impacts. 

In summary, effects to coastal wetlands from the primary impact-producing activities associated with 

the CPA proposed action are expected to be low. Loss of 0-8 ha (0-20 ac) of wetlands habitat is estimated 

as a result of 0-2 km (0-1.2 mi) of new pipelines projected as a result of the proposed action. 

Maintenance dredging of navigation channels and canals is expected to occur with minimal impacts. The 

proposed action is expected to contribute minimally to the need for this dredging. Alternative dredgedmaterial disposal methods can be used to enhance and create coastal wetlands. Vessel traffic associated 

with the proposed action is expected to contribute minimally to the erosion and widening of navigation 

channels and canals. Overall, impacts from these sources are expected to be low and are further reduced 

through mitigation, such as horizontal, directional (trenchless) drilling techniques, to avoid damages to 

these sensitive habitats. Secondary impacts to wetlands would be primarily from vessel traffic corridors 

and would continue to cause approximately 1 ha (3 ac) of landloss per year. 

Offshore oil spills resulting from the CPA proposed action are not expected to significantly damage 

any wetlands along the Gulf Coast. This is because of the distance from the spill to the coast and because 

wetlands are generally protected by barrier islands, peninsulas, sand spits, and currents. Although the 

probability of occurrence is low, the greatest threat from an oil spill to wetland habitat is from an inland 

spill as a result of a vessel accident or pipeline rupture. Wetlands in the northern Gulf of Mexico are 

either in moderate- to high-energy environments; therefore, sediment transport and tidal stirring should 

reduce the chances for oil persisting in the event that these areas are oiled. While a resulting slick may 

cause minor impacts to wetland habitat and surrounding seagrass communities, the equipment, chemical 

treatments, and personnel used to clean up can generate the greatest impacts to the area. Associated foot 

traffic may work oil farther into the sediment than would otherwise occur. Close monitoring and 

restrictions on the use of bottom-disturbing equipment would be needed to avoid or minimize those 

impacts. In addition, an assessment of the area covered, oil type, and plant composition of the wetland 

oiled should be made prior to choosing remediation treatment. These treatments could include 

mechanical and chemical techniques with onsite technicians. Overall, impacts to wetland habitats from 

an oil spill associated with activities related to the CPA proposed action would be expected to be low and 

temporary because of the nature of the system, regulations, and specific cleanup techniques. 

Seagrass Communities (Chapter 4.1.1.5) 

Routine OCS activities in the CPA are not expected to significantly increase in occurrence and range 

in the near future. Mitigation reduces undesirable effects on submerged vegetation beds from dredging 

activities. Permit requirements should ensure that pipeline routes avoid high-salinity beds and maintain 

water clarity and quality. Local programs decrease the occurrence of prop scarring in grass beds, and 

channels utilized by OCS vessels are generally away from exposed submerged vegetation beds. Because 

of these requirements, natural flushing, and implemented programs, any potential effects from routine 

activities on submerged vegetation in the CPA are expected to be localized and not significantly adverse. 

Although the probability of their occurrence is low, the greatest threat to inland, submerged 

vegetation communities would be from an inland spill resulting from a vessel accident or pipeline rupture. 

The resulting slick may cause short-term and localized impacts to the bed. There is also the remote 

possibility of an offshore spill to such an extent that it could also affect submerged vegetation beds, and 

this would have similar effects to an inshore spill. Because prevention and cleanup measures can have 

negative effects on submerged vegetation, close monitoring and restrictions on the use of bottomdisturbing equipment would be needed to avoid or minimize those impacts. The floating nature of 

nondispersed crude oil, the regional microtidal range, dynamic climate with mild temperatures, and the 

amount of microorganisms that consume oil would alleviate prolonged effects on submerged vegetation 
2-12 Central Planning Area Supplemental EIS 

communities. Also, safety and spill-prevention technologies continue to improve and would decrease 

detrimental effects to submerged vegetation from the proposed action. 

Live Bottoms (Chapter 4.1.1.6) 

Live Bottoms (Pinnacle Trend) (Chapter 4.1.1.6.1) 

Oil and gas operations discharge drilling muds and cuttings that generate turbidity, potentially 

smothering benthos near the drill sites. Deposition of drilling muds and cuttings in the Pinnacle Trend 

area would not greatly impact the biota of the live bottoms because the biota surrounding the pinnacle 

features are adapted to turbid (nepheloid) conditions and high sedimentation rates associated with the 

outflow of the Mississippi River. The pinnacles themselves are coated with a veneer of sediment. 

Regional surface currents and water depth would largely dilute any effluent. Additional deposition and 

turbidity caused by a nearby well are not expected to adversely affect the pinnacle environment because 

such fluids would be dispersed upon discharge. Mud contaminants measured in the Pinnacle Trend 

region reached background levels within 1,500 m (4,921 ft) of the discharge point. Toxic impacts on 

benthos are limited to within 100-200 m (328-656 ft) of a well, and NPDES permit requirements limit 

discharge. The drilling of a well from the proposed action, therefore, would have localized impacts on the 

benthos nearby the well, which should be located away from live-bottom features. 

The toxicity of the produced waters has the potential to adversely impact the live-bottom organisms 

of the Pinnacle Trend; however, as previously stated, the proposed Live Bottom (Pinnacle Trend) 

Stipulation would prevent the placement of oil and gas facilities upon (and consequently would prevent 

the discharge of produced water directly over) the Pinnacle Trend live-bottom areas. 

Platform removals have the potential to impact nearby habitats. As previously discussed, the 

platforms are unlikely to be constructed directly on the pinnacles or low-relief areas because of the 

restraints placed by the Live Bottom (Pinnacle Trend) Stipulation, distancing blasts from sensitive 

habitats. Benthic organisms on live bottoms should also have limited impact because they are resistant to 

blasts, tolerant of turbidity, can physically remove some suspended sediment, and may be located above 

or be tall enough to withstand limited sediment deposition. Live bottoms, however, may be impacted by 

heavy sediment deposition layers. The implementation of the Live Bottom (Pinnacle Trend) Stipulation 

would help to prevent such a smothering event. The proposed Live Bottom (Pinnacle Trend) Stipulation 

could prevent most of the potential impacts on live bottoms from bottom-disturbing activities (structure 

emplacement and removal) and operational discharges associated with the CPA proposed action in the 

CPA. Any contaminants that reach live-bottom features would be diluted from their original 

concentration and impacts that do occur should be sublethal. 

Live-bottom features represent a small fraction of the continental shelf area in the CPA. The fact that 

the live-bottom features are widely dispersed, combined with the probable random nature of oil-spill 

locations, serves to limit the extent of damage from any given oil spill to the live-bottom features. 

The proposed Live Bottom (Pinnacle Trend) Stipulation (Chapter 2.4.1.3.2) would prevent most of 

the potential impacts from oil and gas operations, including accidental oil spills and blowouts, on the 

biota of live-bottoms features. However, operations outside the proposed buffer zones around sensitive 

habitats (including blowouts and oil spills) may affect live-bottom features. 

The depth below the sea surface to which many live-bottom features rise helps to protect them from 

surface oil spills. Some pinnacles may rise to within 40 m (130 ft) of the sea surface; however, many 

features have much less relief or are in deeper water depths. Any oil that might contact pinnacle features 

would probably be at low concentrations because the depth to which surface oil can mix down into the 

water column is less than the peak of the tallest pinnacles, and this would result in little effect to these 

features. 

A subsurface spill or plume may impact sessile biota of live-bottom features. Oil or dispersed oil 

may cause sublethal impacts to benthic organisms if a plume reaches these features. Impacts may include 

loss of habitat, biodiversity, and live coverage; change in community structure; and failed reproductive 

success. The Live Bottom (Pinnacle Trend) Stipulation would limit the potential impact of such 

occurrences by keeping the sources of such adverse events geographically removed from the sensitive 

biological resources of live-bottom features. 

Sedimented oil or sedimentation as a result of a blowout may impact benthic organisms. However, 

because the Live Bottom (Pinnacle Trend) Stipulation places petroleum-producing activity at a distance 
Alternatives Including the Proposed Action 2-13 

from live-bottom features, this would result in reduced turbidity and sedimentation. Furthermore, any 

sedimented oil should be well dispersed, resulting in a light layer of deposition that would be easily 

removed by the organism and have low toxicity. 

The proposed Live Bottom (Pinnacle Trend) Stipulation would assist in preventing most of the 

potential impacts on live-bottom communities from blowouts, surface, and subsurface oil spills and the 

associated effects. Any contact with spilled oil would likely cause sublethal effects to benthic organisms 

because the distance of activity would prevent contact with concentrated oil. In the unlikely event that oil 

from a subsurface spill would reach the biota of a live-bottom feature, the effects would be primarily 

sublethal and impacts would be at the community level. Any turbidity, sedimentation, and sedimented oil 

would also be at low concentrations by the time the live-bottom features were reached, resulting in 

sublethal impacts. 

Live Bottoms (Low Relief) (4.1.1.6.2) 

Oil and gas operations discharge drilling muds and cuttings that generate turbidity, potentially 

smothering benthos near the drill sites. Deposition of drilling muds and cuttings near low-relief areas 

would not greatly impact the biota of the live bottoms because the biota surrounding the low-relief 

features in or near the CPA are adapted to turbid (nepheloid) conditions and high sedimentation rates 

associated with the outflow of the Mississippi River. Regional surface currents and water depth would 

largely dilute any effluent. Additional deposition and turbidity caused by a nearby well are not expected 

to adversely affect the low-relief environment because such fluids would be dispersed upon discharge. 

Mud contaminants measured in the region reached background levels within 1,500 m (4,900 ft) of the 

discharge point. Toxic impacts on benthos are limited to within 100-200 m (328-656 ft) of a well, and 

NPDES permit requirements limit discharge. The drilling of a well, therefore, would have localized 

impacts on the benthos near the well, which should be located away from live-bottom features according 

to the drilling stipulations. 

The toxicity of produced waters has the potential to adversely impact the live-bottom organisms; 

however, as previously stated, many of the low-relief areas are not in the area to be offered in the CPA 

proposed action, and the proposed Live Bottom (Low Relief) Stipulation would prevent the placement of 

oil and gas facilities upon (and consequently would prevent the discharge of produced water directly 

over) low-relief, live-bottom habitats. 

Platform removals have the potential to impact nearby habitats. As previously discussed, the 

platforms would not be constructed directly on low-relief areas because these areas are either not included 

in the area to be offered in the CPA proposed action or are protected by the Live Bottom (Low Relief) 

Stipulation, distancing blasts from sensitive low-relief habitats. Benthic organisms on live bottoms 

should also have limited impact because they are resistant to blasts, tolerant of turbidity, can physically 

remove some suspended sediment, and may be located above or be tall enough to withstand limited 

sediment deposition. The implementation of the Live Bottom (Low Relief) Stipulation would help to 

prevent smothering events. Since the live-bottom areas are either not included in the area to be offered in 

the CPA proposed action or are protected by the Live Bottom (Low Relief) Stipulation, most of the 

potential impacts on live bottoms from bottom-disturbing activities (structure emplacement and removal) 

and operational discharges associated with the CPA proposed action would be prevented. Any 

contaminants that reach live-bottom features would be diluted from their original concentration, so 

impacts that do occur should be sublethal. 

Live-bottom features represent a small fraction of the continental shelf area in the CPA. The fact that 

the live-bottom features are widely dispersed, combined with the probable random nature of oil-spill 

locations, serves to limit the extent of damage from any given oil spill to the live-bottom features. 

The depth below the sea surface to which many live-bottom features rise helps to protect them from 

surface oil spills. Because the concentration of oil becomes diluted as it physically mixes with the 

surrounding water and as it moves into the water column, any oil that might be driven to 10 m (33 ft) or 

deeper would probably be at concentrations low enough to reduce impact to these features. Features in 

water shallower than 10 m (33 ft) would be far from the source of activities in the CPA proposed action. 

A subsurface spill or plume may impact sessile biota of live-bottom features. Oil or dispersed oil 

may cause sublethal impacts to benthic organisms if a plume reaches these features. Impacts may include 

loss of habitat, biodiversity, and live coverage; change in community structure; and failed reproductive 
2-14 Central Planning Area Supplemental EIS 

success. The distance of proposed activities from low-relief live bottoms provides considerable 

protection for the habitats. The Live Bottom (Low Relief) Stipulation would limit the potential impact of 

any activities that may approach low-relief habitats (such as pipeline right-of-ways) because the 

stipulation keeps the sources of such adverse events geographically removed from the sensitive biological 

resources of live-bottom features. The distance would serve to reduce turbidity and sedimentation, and 

any sedimented oil should be well dispersed, resulting in a light layer of deposition that would have low 

toxicity and be easily removed by the organism. 

The proposed Live Bottom (Low Relief) Stipulation would assist in preventing most of the potential 

impacts on live-bottom communities from blowouts, surface, and subsurface oil spills and the associated 

effects. Any contact with spilled oil would likely cause sublethal effects to benthic organisms because the 

distance of activity would prevent contact with concentrated oil. In the unlikely event that oil from a 

subsurface spill would reach the biota of a live-bottom feature, the effects would be primarily sublethal 

and impacts would be at the community level. Any turbidity, sedimentation, and sedimented oil would 

also be at low concentrations by the time the live-bottom features were reached, resulting in sub-lethal 

impacts. 

Topographic Features (Chapter 4.1.1.7) 

The proposed Topographic Features Stipulation would prevent most of the potential impacts on 

topographic features from bottom-disturbing activities (structure removal and emplacement) and 

operational discharges associated with the CPA proposed action. Because of the No Activity Zone, 

permit restrictions, and the high-energy environment associated with topographic features, if any 

contaminants reach topographic features, they would be diluted from their original concentration and 

impacts that do occur would be minimal. 

The proposed Topographic Features Stipulation would assist in preventing most of the potential 

impacts on topographic feature communities from blowouts, surface, and subsurface oil spills and the 

associated effects by increasing the distance of such events from the topographic features. Any contact 

with spilled oil would likely cause sublethal effects to benthic organisms because the distance of activity 

would prevent contact with concentrated oil. In the unlikely event that oil from a subsurface spill would 

reach the biota of a topographic feature, the effects would be primarily sublethal and the impacts would 

be at the community level. Any turbidity, sedimentation, and oil adsorbed to sediments would also be at 

low concentrations by the time the topographic features were reached, also resulting in sublethal impacts. 

Impacts from an oil spill on topographic features are also lessened by the distance of the spill to the 

features, the depth of the features, and the currents that surround the features. 

Sargassum (Chapter 4.1.1.8) 

Sargassum, as pelagic algae, is a widely distributed resource that is ubiquitous throughout the GOM 

and northwest Atlantic. Considering its ubiquitous distribution and occurrence in the upper water column 

near the sea surface, it would be contacted by routine discharges from oil and gas operations. All types of 

discharges including drill muds and cuttings, produced water, and operational discharges (e.g., deck 

runoff, bilge water, sanitary effluent, etc.) would contact Sargassum algae. However, the quantity and 

volume of these discharges is relatively small compared with the pelagic waters of the CPA 

(268,922 km2

; 103,831 mi2). Therefore, although discharges would contact Sargassum, they would only 

contact a very small portion of the Sargassum population. Because these discharges are highly regulated 

for toxicity and because they would continue to be diluted in the Gulf water, concentrations of any toxic 

components would be reduced; therefore, produced water impacts on Sargassum would be minimum. 

Likewise, impingement effects by service vessels and working platforms and drillships would contact 

only a very small portion of the Sargassum population. The impacts to Sargassum that are associated 

with the proposed action are expected to have only minor effects to a small portion of the Sargassum

community as a whole. The Sargassum community lives in pelagic waters with generally high water 

quality and would be resilient to the minor effects predicted. It has a yearly cycle that promotes quick 

recovery from impacts. No measurable impacts are expected to the overall population of the Sargassum

community. 

Considering its ubiquitous distribution and occurrence in the upper water column near the sea surface, 

Sargassum would contact potential accidental spills from oil and gas operations. All types of spills 
Alternatives Including the Proposed Action 2-15 

including surface oil and fuel spills, underwater well blowouts, and chemical spills would contact 

Sargassum algae. The quantity and volume of most of these spills would be relatively small compared 

with the pelagic waters of the CPA (268,922 km2

 [103,831 mi2] of the CPA). Therefore, most spills 

would only contact a very small portion of the Sargassum population. The impacts to Sargassum that are 

associated with the proposed action are expected to have only minor effects to a small portion of the 

Sargassum community as a whole unless a catastrophic spill occurs. In the case of a very large spill, the 

Sargassum algae community could suffer severe impacts to a sizable portion of the population in the 

northern GOM. No measurable impacts are expected to the overall population of the Sargassum

community unless a catastrophic spill occurs. 

Chemosynthetic Deepwater Benthic Communities (Chapter 4.1.1.9) 

Chemosynthetic communities are susceptible to physical impacts from structure placement (including 

templates or subsea completions), anchoring, and pipeline installation. Because of the avoidance policies 

described in NTL 2009-G40, the risk of these physical impacts are greatly reduced by requiring the 

avoidance of potential chemosynthetic communities. 

Chemosynthetic communities could be susceptible to physical impacts from a blowout depending on 

bottom-current conditions. The guidance provided in NTL 2009-G40 greatly reduces the risk of these 

physical impacts. It clarifies the requirement to avoid potential chemosynthetic communities identified 

on the required geophysical survey records or photodocumentation to establish the absence of 

chemosynthetic communities prior to approval of the structure emplacement. 

Studies indicate that periods as long as hundreds of years are required to reestablish a seep 

community once it has disappeared (depending on the community type). There is evidence that 

substantial impacts on these communities could permanently prevent reestablishment, particularly if hard 

substrate required for recolonization was buried by resuspended sediments from a blowout. 

Potential accidental impacts from the CPA proposed action are expected to cause little damage to the 

ecological function or biological productivity of widespread, low-density chemosynthetic communities. 

The rarer, widely scattered, high-density, Bush Hill-type chemosynthetic communities located at more 

than 610 m (2,000 ft) away from a blowout could experience minor impacts from resuspended sediments. 

However, the possibility of oil from a surface spill reaching a depth of 300 m (984 ft) or greater in any 

measurable concentration is very small. If dispersants are applied to an oil spill, oil would mix into the 

water column, be carried by underwater currents, and eventually contact the seafloor where it may impact 

patches of chemosynthetic community habitat in its path. 

The BOEMRE has reexamined the analysis for impacts to chemosynthetic communities presented in 

the Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented 

above. No substantial new information was found to indicate that accidental impacts associated with the 

CPA proposed action would result in more than minimal impacts to chemosynthetic communities because 

of the NTL 2009-G40 guidelines. One exception would be in the case of a catastrophic spill combined 

with the application of dispersant, producing the potential to cause devastating effects on local patches of 

habitat in the path of subsea plumes where they contact the seafloor. 

Nonchemosynthetic Deepwater Benthic Communities (Chapter 4.1.1.10) 

Some impact to soft-bottom benthic communities from drilling and production activities would occur 

as a result of physical impact from drilling discharges, structure placement (including templates or subsea 

completions), anchoring, and installation of pipelines regardless of their locations. However, even in 

situations where the substantial burial of typical benthic infaunal communities occurred, recolonization 

from populations from widespread neighboring soft-bottom substrate would be expected over a relatively 

short period of time for all size ranges of organisms. 

Impacts to other hard-bottom communities are expected to be avoided as a consequence of the 

application of the existing NTL 2009-G40 guidelines for chemosynthetic communities. The same 

geophysical conditions associated with the potential presence of chemosynthetic communities also results 

in the potential occurrence of hard carbonate substrate and nonchemosynthetic communities. Because of 

the NTL 2009-G40 guideline, these are generally avoided in exploration and development planning. 

Accidental events resulting from the CPA proposed action are expected to cause little damage to the 

ecological function or biological productivity of widespread, typical, deep-sea benthic communities. 
2-16 Central Planning Area Supplemental EIS 

Some impact to benthic communities would occur as a result of impact from an accidental blowout. 

Megafauna and infauna communities at or below the sediment/water interface would be impacted by the 

physical disturbance of a blowout or by burial from resuspended sediments. However, even in situations 

where the substantial burial of typical soft benthic communities occurred, recolonization by populations 

from neighboring substrate would be expected over a relatively short period of time. For all size ranges 

of organisms, this can be in a matter of hours to days for bacteria and about 1-2 years for most all 

macrofauna species. 

Impacts to deepwater coral habitats and other potential hard-bottom communities would likely be 

avoided as a consequence of the application of the policies described in NTL 2009-G40. The rare, widely 

scattered, high-density, Bush Hill-type nonchemosynthetic communities located at more than 610 m 

(2,000 ft) away from a blowout could experience minor impacts from resuspended sediments. If 

dispersants are applied to an oil spill oil would mix into the water column, be carried by underwater 

currents, and eventually contact the seafloor where it may impact patches of sensitive deepwater 

community habitat in its path. These potential impacts would be localized due to the directional 

movement of oil plumes by the water currents and because the sensitive habitats have a scattered, patchy 

distribution. 

The BOEMRE has reexamined the analysis for impacts to nonchemosynthetic communities presented 

in the Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented 

above. No substantial new information was found that would alter the overall conclusion that impacts on 

nonchemosynthetic communities from routine activities associated with the CPA proposed action would 

be minimal to none. 

Marine Mammals (Chapter 4.1.1.11) 

In this Supplemental EIS, BOEMRE has reexamined the analysis for marine mammals presented in 

the Multisale EIS and the 2009-2012 Supplemental EIS and has considered the recent reports cited in 

Chapter 4.1.1.11 and other new information. The extent and scope of the spill resulting from the DWH 

event represents new information not assessed in the existing ESA Section 7 consultation in the GOM on 

the current 5-Year Program. As a result of this new information, BOEMRE reinitiated ESA Section 7 

consultation on the existing GOM Multisale EIS with NMFS and FWS on July 30, 2010. The NMFS 

responded with a letter to BOEMRE on September 24, 2010; FWS responded with a letter to BOEMRE 

on September 27, 2010. However, NMFS and FWS have placed this consultation on hold given the 

environmental baseline needing to be updated by the results of the NRDA process. The NRDA data have 

yet to be released. The existing consultations will remain in effect until the reinitiated consultations are 

completed. The existing consultation recognizes that BOEMRE-required mitigations and other 

reasonable and prudent measures should reduce the likelihood of impacts from BOEMRE-authorized 

activities. 

Mysticetes, as low-frequency hearing specialists, are the species groups most likely to be susceptible 

to impacts from nonpulse sound (intermittent or continuous), given that their hearing ranges overlap most 

closely with the noise frequencies produced from drilling. However, most mysticete species that may 

occur in the GOM (i.e., North Atlantic right, blue, fin, sei, humpback, and minke whales) are considered 

either “extralimital,” “rare,” or “uncommon”; however, a small population of Bryde’s whales are common 

in the eastern GOM. Because of the geographic scope of the proposed action, the presence of these 

species within the action area is unlikely. 

The remaining marine mammal species in the GOM (e.g., sperm whales, dwarf or pygmy sperm 

whales, and dolphins) are considered mid-frequency hearing specialists, with hearing ranges that slightly 

overlap with sound frequencies produced from drilling noise. It is expected that there would be some 

overlap in the frequencies of the drill source and the hearing thresholds of the marine mammals present in 

the GOM. The broadband frequencies of semisubmersible drill vessels are estimated to be from 80 to 

4,000 Hz, with an estimated source level of 154 dB re 1μPa at 1 m. Tones of 60 Hz had source levels of 

149 dB, 181 Hz was 137 dB, and 301 Hz was 136 dB. Bottlenose dolphins have hearing thresholds 

ranging from less than 5 kHz to over 100 kHz. Through auditory brainstem analysis, it was found that 

pygmy sperm whales have thresholds from 90 to 150 kHz. A stranded sperm whale was found to have 

lower hearing limits at around 100 Hz, while a sperm whale calf was found to have had best hearing 

sensitivity between 5 and 20 kHz. Since there is some overlap in the sound levels produced and the 
Alternatives Including the Proposed Action 2-17 

hearing thresholds of marine mammals, there is potential for the drilling noise produced to cause auditory 

and nonauditory effects, permanent threshold shift, temporary threshold shift, behavioral changes, or 

masking; but it is expected to be limited. However, these levels are under the NMFS 160-dB level B 

harassment under the MMPA. 

The NMFS sets the 180-dB, root-mean-squared (rms) isopleth where on-set of auditory injury or 

mortality (level A harassment) to cetaceans may occur. It is suggested that this level should rather be at 

230 dB rms for a nonpulsed sound, such as drilling noise. Drilling from semisubmersible vessels have 

estimated broadband frequencies from 80 to 4,000 Hz, with an estimated source level of 154 dB re 

1microPa at 1 m. Tones of 60 Hz have source levels of 149 dB, while 181 Hz have source levels of 137 

dB, and 301 Hz have source levels of 136 dB. These source levels all fall below the 180-dB level A 

harassment isopleths. 

Because of the mitigations described in Chapter 4.1.1.11, routine activities (e.g., operational 

discharges, noise, vessel traffic, and marine debris) related to the proposed CPA lease sale are not 

expected to have long-term adverse effects on the size and productivity of any marine mammal species or 

population in the northern GOM. Lethal effects are most likely to be from chance collisions with OCS 

service vessels or ingestion of any accidentally released plastic materials. Most routine OCS activities are 

expected to have sublethal effects. In conclusion, the scope, timing, and transitory nature of the proposed 

action and the mitigation and monitoring requirements in place, the noise related to the CPA proposed 

action is not expected to result in permanent threshold shift, temporary threshold shift, behavioral change, 

masking, or nonauditory effects to marine mammals in the GOM that would rise to the level of 

significance. 

In the event of a catastrophic spill similar to the DWH event, any substantive impact to marine 

mammals is very unlikely because the potential impacts from a catastrophic spill would be similar to the 

routine and accidental issues described in Chapters 4.1.1.11.2 and 4.1.1.11.3, respectively. However, 

despite the recent DWH event, historical trends in the GOM indicate that catastrophic spill events are not 

likely to occur as a result of drilling and temporary abandonment. 

Sea Turtles (Chapter 4.1.1.12) 

In this Supplemental EIS, BOEMRE has reexamined the analysis for sea turtles presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS and has considered the recent reports cited in 

Chapter 4.1.1.12 and other new information. The extent and scope of the spill resulting from the DWH 

event represents new information not assessed in the existing ESA Section 7 consultation in the GOM 

under the current 5-Year Program. As a result of this new information, BOEMRE reinitiated ESA 

Section 7 consultation on the existing GOM Multisale EIS with NMFS and FWS on July 30, 2010. The 

NMFS responded with a letter to BOEMRE on September 24, 2010; FWS responded with a letter to 

BOEMRE on September 27, 2010. However, NMFS and FWS have placed this consultation on hold 

given the environmental baseline needing to be updated by the results of the NRDA process. The NRDA 

data have yet to be released. The existing consultations will remain in effect until the reinitiated 

consultations are completed. In the interim, BOEMRE will continue to comply with all Reasonable and 

Prudent Measures and the Terms and Conditions under these existing consultations, along with 

implementing the current BOEMRE-imposed mitigation, monitoring, and reporting requirements. Based 

on the most recent and best available information at the time, BOEMRE will also continue to closely 

evaluate and assess risks to listed species and designated critical habitat in upcoming environmental 

compliance documentation under NEPA and other statutes. 

Because of the mitigations described in Chapter 4.1.1.12, routine activities (e.g., operational 

discharges, noise, vessel traffic, and marine debris) related to the proposed CPA lease sale are not 

expected to have long-term adverse effects on the size and productivity of any sea turtle species or 

populations in the northern GOM. Lethal effects are most likely to be from chance collisions with OCS 

service vessels or ingestion of accidentally-released plastic materials. Most OCS activities are expected 

to have sublethal effects. 

With current regulations, mitigation, and the low probability of an accidental event, effects on turtle 

populations from a CPA proposed action are expected to be small. In the event of a catastrophic spill 

similar to the DWH event, any substantive impact to sea turtles is very unlikely because the potential 

impacts from a catastrophic spill would be similar to the routine and accidental issues described in 
2-18 Central Planning Area Supplemental EIS 

Chapters 4.1.1.12.2 and 4.1.1.12.3, respectively. However, despite the recent DWH event, historical 

trends in the GOM indicate that catastrophic spill events are not likely to occur as a result of drilling and 

temporary abandonment associated with the CPA proposed action. 

Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice (4.1.1.13) 

An impact from the CPA proposed action on the Alabama, Choctawhatchee, St. Andrew, and Perdido 

Key beach mice is possible but unlikely. Impact may result from consumption of beach trash and debris. 

Because the proposed action would deposit only a small portion of the total debris that would reach the 

habitat, the impacts would be minimal. Unless all personnel are adequately trained, efforts undertaken for 

the removal of marine debris may temporarily scare away beach mice or destroy their food resources such 

as sea oats. However, their burrows are about 1-3 m (3-10 ft) long and involve a plugged escape tunnel, 

which would function after the main burrow entrance was trampled by foot traffic of insufficiently trained 

debris cleanup personnel. 

The oiling of beach mice could result in local extinction. Oil-spill-response and cleanup activities 

could also have a substantial impact to the beach mice and their habitat if not properly regulated. 

However, potential spills that could result from the proposed action are not expected to contact beach 

mice or their habitats (<0.5% probability). Also, inshore facilities related to the proposed action are 

unlikely to be located on beach mouse habitat. 

Within the last 20-30 years, the combination of habitat loss due to beachfront development, isolation 

of remaining beach mouse habitat areas and populations, and destruction of remaining habitat by tropical 

storms and hurricanes has increased the threat of extinction of several subspecies of beach mice. 

Destruction of the remaining habitat due to a catastrophic spill and cleanup activities would increase the 

threat of extinction, but the potential for a catastrophic spill that would affect beach mice habitat is low. 

Coastal and Marine Birds (Chapter 4.1.1.14) 

The majority of effects resulting from routine activities with the CPA proposed action on endangered/

threatened and nonendangered/nonthreatened coastal and marine birds are expected to be sublethal. 

These effects include behavioral effects, exposure to or intake of OCS-related contaminants or discarded 

debris, temporary disturbances, and displacement of localized groups from impacted habitats. Chronic 

sublethal stress, however, is often undetectable in birds. As a result of stress, individuals may weaken, 

facilitating infection and disease; migratory species may then not have the energetic reserves necessary to 

complete their migration. Nocturnal circulation around platforms, under certain circumstances, may 

create acute sublethal stress from energy loss and increase the risks of collision, while stopovers on 

platforms would reduce energy loss. Because of regulatory standards for air and water quality as 

discussed in Chapters 4.1.1.1, 4.1.1.2.1, and 4.1.1.2.2, emissions or produced waters should have a small 

effect on birds. No significant habitat impacts are expected to occur directly from routine activities 

resulting from the CPA proposed action because of the distance of these activities from shore. Secondary 

impacts from pipeline and navigation canals to coastal habitats would occur over the long term and may 

ultimately displace members of some species. These activities would occur whether the proposed action 

was implemented or not; therefore, the proposed action itself would not increase these secondary impacts 

to birds. 

Oil spills have the greatest impact on coastal and marine birds. Small amounts of oil can affect birds, 

and mortality from oil spills is often related to numerous symptoms of toxicity. Data from actual spills 

strongly suggest that impacts on their food supply are delayed after initial impacts from direct oiling. 

Mechanisms of toxic oil effects other than direct oiling of plumage have seldom been confirmed. Oilspill impacts on birds from the CPA proposed action are expected to be negligible because oil spills 

would only affect a small portion of a bird group. Impacts of oil-spill cleanup from the proposed action 

are also expected to be negligible. 

Gulf Sturgeon (Chapter 4.1.1.15) 

Potential routine impacts on Gulf sturgeon and their designated critical habitat may occur from 

drilling and produced-water discharges, bottom degradation of estuarine and marine water quality by 

nonpoint runoff from estuarine OCS-related facilities, vessel traffic, explosive removal of structures, and 
Alternatives Including the Proposed Action 2-19 

pipeline installation. Because of the permitted discharge limits mandated and enforced in the Federal and 

State regulatory process, the dilution and low toxicity of this pollution is expected to result in negligible 

impact of the CPA proposed action on Gulf sturgeon. Vessel traffic would generally only pose a risk to 

Gulf sturgeon when leaving and returning to port. Major navigation channels are excluded from critical 

habitat. Also, the Gulf sturgeon characteristics of bottom-feeding and general avoidance of disturbance 

make the probability of vessel strike extremely remote. Explosive removal of structures as a result of the 

proposed action would occur well offshore of Gulf sturgeon’s critical habitat and the riverine, estuarine, 

and shallow Gulf habitats where sturgeon are generally located. If any pipeline is installed nearshore as a 

result of the proposed action, regulatory permit requirements governing pipeline placement and dredging, 

as well as recent noninvasive techniques for locating pipelines, would result in very minimal impact to the 

Gulf sturgeon’s critical habitat. Due to regulations, mitigations, and the distance of routine activities from 

known Gulf sturgeon habitats, impacts from routine activities of the CPA proposed action would be 

expected to have negligible effects on Gulf sturgeon and their designated critical habitat. 

The Gulf sturgeon could be impacted by oil spills resulting from the CPA proposed action. If there is 

contact with spilled oil, it could have detrimental physiological effects. The juvenile and subadult Gulf 

sturgeon, at a minimum, seasonally use the nearshore coastal waters and could potentially be at risk from 

both coastal and offshore spills. Due to the distance of the activity from shore and Gulf sturgeon critical 

habitat, there is a minimal risk of any oil coming in contact with Gulf sturgeon. The probability of a spill 

of a size and duration to persist long enough in the environment to impact the sturgeon or the sturgeon’s 

estuarine habitats is small (≤10%; Figure 3-10 of the 2009-2012 Supplemental EIS) unless it is 

catastrophic in nature such as the DWH event. In the rare event contact with oil occurs, this could cause 

nonlethal effects including fish temporarily migrating from the affected area, irritation of gill epithelium, 

and an increase of liver function in a few adults, and possibly interference with reproductive activity. 

The formal consultation with NMFS was concluded with the Biological Opinion dated June 29, 2007, 

and received by BOEMRE on July 3, 2007. The Biological Opinion concludes that the proposed lease 

sales and associated activities in the GOM in the 5-Year Program, which includes the current leasing area 

concurred with BOEMRE that the proposed actions would not adversely impact the endangered Gulf 

sturgeon or its critical habitat. Following the DWH event, BOEMRE requested reinitiation of ESA 

consultation with both NMFS and FWS on July 30, 2010. The NMFS responded with a letter to 

BOEMRE on September 24, 2010. The FWS responded with a letter to BOEMRE on September 27, 

2010. The reinitiated consultations are not complete at this time; however, BOEMRE is in discussions 

with both agencies. 

Fish Resources and Essential Fish Habitat (Chapter 4.1.1.16) 

It is expected that any possible coastal and marine environmental degradation from the CPA proposed 

action would have little effect on fish resources or EFH. The impact of coastal and marine environmental 

degradation is not expected to cause a detectable decrease in fish resources or in EFH. Routine activities 

such as pipeline trenching and OCS discharge of drilling muds and produced water would cause 

negligible impacts and would not deleteriously affect fish resources or EFH. This is because mitigation 

reduces undesirable effects on coastal habitats from dredging and other construction activities. Permit 

requirements should ensure pipeline routes either avoid different coastal habitat types or certain 

techniques are used to decrease impacts. At the expected level of impact, the resultant influence on fish 

resources would cause minimal changes in fish populations or EFH. That is, if there are impacts, they 

would be short-term and localized; therefore, they would only affect small portions of fish populations 

and selected areas of EFH. As a result, there would be little disturbance to fish resources or EFH. In 

deepwater areas, many of the EFH’s are protected under stipulations and regulations currently set in 

place. 

The BOEMRE has reexamined the analysis for impacts to fish resources and EFH presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information described in 

Chapter 4.1.1.16.2. No substantial new information was found that would alter the overall conclusion 

that impacts to fish resources and EFH from routine activities associated with the CPA proposed action 

would be minimal to none. The CPA proposed action is expected to result in a minimal decrease in fish 

resources and/or standing stocks or in EFH. It would require a short time for fish resources to recover 

from most of the impacts, but the loss of wetlands as EFH could be permanent. 
2-20 Central Planning Area Supplemental EIS 

Additional hard substrate habitat provided by structure installation in areas where natural hard bottom 

is rare would tend to increase fish populations. The removal of these structures would eliminate that 

habitat, except when decommissioned platforms are used as artificial reef material. This practice is 

expected to increase over time. 

Accidental events that could impact fish resources and EFH include blowouts and oil or chemical 

spills. Subsurface blowouts, although highly unlikely, have the potential to adversely affect fish 

resources. If spills due to the CPA proposed action were to occur in open waters of the OCS proximate to 

mobile adult finfish or shellfish, the effects would likely be nonfatal and the extent of damage would be 

reduced due to the capability of adult fish and shellfish to avoid a spill, to metabolize hydrocarbons, and 

to excrete both metabolites and parent compounds. Fish populations may be impacted by an oil spill, but 

they would be primarily affected if the oil reaches the productive shelf and estuarine areas; this 

probability is generally low. Also, much of the coastal northern Gulf of Mexico is a moderate- to highenergy environment; therefore, sediment transport and tidal stirring should reduce the chances for oil 

persisting in these habitats if they are oiled. Early life stages of animals are usually more sensitive to 

environmental stress than adults. Oil can be lethal to fish, especially in larval and egg stages, depending 

on the time of the year that the event happened. The extent of the impacts of the oil would depend on the 

properties of the oil and the time of year of the event. 

Fisheries closures may result from a large spill event. These closures may have a negative effect on 

short-term fisheries catch and/or marketability. In the long term, they may have a positive impact on 

species populations. 

The effect of proposed-action-related oil spills on fish resources is expected to cause a minimal 

decrease in standing stocks of any population because most spill events would be localized; therefore, 

they would affect a small portion of fish populations. Historically, there have been no oil spills of any 

size that have had a long-term impact on fishery populations. Although many potential effects of the 

DWH event on the fish populations of the Gulf of Mexico have been alleged, the actual effects are at this 

time unknown, and the total impacts are likely to be unknown for several years. 

Commercial Fishing (Chapter 4.1.1.17) 

Routine activities such as seismic surveys and pipeline trenching in the CPA would cause negligible 

impacts and would not deleteriously affect commercial fishing activities. Because seismic surveys are 

temporary events, they are not expected to cause long-term or permanent displacement of any listed 

species from critical/preferred habitat or to result in the destruction or adverse modification of critical 

habitat or EFH. Operations such as production platform emplacement, underwater OCS impediments, 

and explosive platform removal would cause slightly greater impacts on commercial fishing, but their 

effects are localized to a small percentage of area fished and are temporary in nature. 

Commercial catches by species and by State have been updated in Chapter 4.1.1.17.1, as have the 

impacts of the 2005 and 2008 hurricanes on fish and fish habitat from recent reports. The new 

information presented in this Supplemental EIS does not alter the conclusion presented in the Multisale 

EIS and the 2009-2012 Supplemental EIS that impacts on commercial fisheries from routine activities 

associated with the CPA proposed action would be minimal. 

The BOEMRE has reexamined the analysis for impacts to commercial fish resources presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, based on updated information obtained through the 

peer-reviewed data, Internet sources, and conversations with Gulf Coast State agencies, Federal agencies, 

and professors at local academic institutions. No substantial newly published, peer-reviewed information 

was found that would alter the overall conclusion that impacts to commercial fish resources from 

accidental activities associated with the CPA proposed action would be minimal. In summary, the 

impacts of the CPA proposed action from accidental events (i.e., a well blowout or an oil spill) are 

anticipated to be minimal because the potential for oil spills is very low. 

Fish populations may be impacted by an oil-spill event should it occur, but they would be primarily 

affected if the oil reaches the productive shelf and estuarine areas. The probability of an offshore spill 

impacting these nearshore environments is also low, and oil would generally be volatilized or dispersed 

by currents in the offshore environment. Extent of the impacts of the oil would depend on the properties 

of the oil and the time of year of the event. 
Alternatives Including the Proposed Action 2-21 

Commercial fishermen are anticipated to avoid the area of a well blowout or an oil spill. Fisheries 

closures may result from a large spill event. These closures may have a negative effect on short term 

fisheries catch and/or marketability. In the long term, they may have a positive impact on annually 

harvested because there was a decrease in fishing pressure on the stocks. 

Recreational Fishing (Chapter 4.1.1.18) 

There could be minor and short-term, space-use conflicts with recreational fishermen during the 

initial phases of the CPA proposed action. The proposed action could also lead to low-level 

environmental degradation of fish habitat (Chapter 4.1.1.16.2), which would also negatively impact 

recreational fishing activity. However, these minor negative effects would likely be outweighed by the 

beneficial role that oil rigs serve as artificial reefs for fish populations. Each structure placed during the 

CPA proposed action has the potential to function as a de facto artificial reef. The degree to which oil 

platforms would become a part of a particular State’s rigs-to-reefs program would be an important 

determinant of the degree to which the proposed action would impact recreational fishing activity in the 

long term. 

An oil spill would likely lead to recreational fishing closures in the vicinity of the oil spill. Smallscale spills should not affect recreational fishing to a large degree due to the likely availability of 

substitute fishing sites in neighboring regions. A rare large spill such as the one associated with the DWH 

event can have more noticeable effects because of the larger potential closure regions and because of the 

wider economic implications such closures can have. However, the longer-term implications of a large 

oil spill would primarily depend on the extent to which fish ecosystems recover after the spill has been 

cleaned. Because offshore spills have a small probability of contacting estuarine habitats that serve as 

nurseries for many recreational species and because inshore spills would have localized impacts to an 

area, oil spills would have a small effect on recreational fisheries. 

Recreational Resources (Chapter 4.1.1.19) 

Routine OCS actions in the CPA could cause minor disturbances to recreational resources, 

particularly beaches, through increased levels of noise, debris, and rig visibility. Because offshore spills 

have a small probability of contacting estuarine habitats that serve as nurseries for many recreational 

species and because inshore spills would have localized impacts to an area, oil spills would have a small 

effect on recreational fisheries. Routine activities could also cause minor changes to the composition of 

local economies through changes in employment, land-use, and recreation demand. The CPA proposed 

action has the potential to directly and indirectly impact recreational resources along the coastal areas 

adjacent to the CPA. However, the small scale of OCS activities relative to the scale of the existing oil 

and gas industry is such that these potential impacts on recreational resources are likely to be minimal. 

Spills most likely to result from the CPA proposed action would be small, of short duration, and not 

likely to impact Gulf Coast recreational resources. Should an oil spill occur and contact a beach area or 

other recreational resource, it would cause some disruption during the impact and cleanup phases of the 

spill. However, these effects are also likely to be small in scale and of short duration. This is because the 

size of a coastal spill is projected to be small (coastal spills are assumed to be 5 bbl; Table 4-13 of the 

Multisale EIS), and the probability of an offshore spill contacting most beaches is small. In the unlikely 

event that a spill occurs that is sufficiently large to affect large areas of the coast and, through public 

perception, have effects that reach beyond the damaged area, effects to recreation and tourism could be 

significant. The DWH event was such a case; the resulting spill damaged some coastal resources but had 

economic effects in a much larger area. The role of perceptions on tourism activity was a particularly 

important feature of the DWH event, one that should become better understood as the aftermath of the 

spill unfolds. 

Archaeological Resources (Chapter 4.1.1.20) 

The BOEMRE has reexamined the analysis for archaeological resources presented in the Multisale 

EIS and the 2009-2012 Supplemental EIS. This Supplemental EIS is based upon additional information 

available since the publication of these two documents and in consideration of the DWH event. 

Substantial new information that alters the impact conclusion for archaeological resources presented in 
2-22 Central Planning Area Supplemental EIS 

the Multisale EIS and the 2009-2012 Supplemental EIS has come to light as a result of BOEMREsponsored studies and industry surveys; specifically, reports of damage to significant cultural resources 

(i.e., historic shipwrecks) have been confirmed in lease areas >200 m (656 ft) deep where no survey data 

was available. Although the exact cause of this damage is unknown, it may be linked to postlease, 

bottom-disturbing activities. As part of the environmental reviews conducted for postlease activities, 

available information will be evaluated regarding the potential presence of archaeological resources 

within the proposed action area to determine if mitigation is warranted. 

Historic (4.1.1.20.1) 

The greatest potential impact to an archaeological resource as a result of the CPA proposed action 

would result from direct contact between an offshore activity (i.e., platform installation, drilling rig 

emplacement, and dredging or pipeline project) and a historic site. Archaeological surveys, where 

required prior to an operator beginning oil and gas activities on a lease, are expected to be effective at 

identifying possible archaeological sites. The technical requirements of the archaeological resource 

reports are detailed in NTL 2005-G07, “Archaeological Resource Surveys and Reports.” Under 30 CFR 

250.194(c) and 30 CFR 250.1010(c), lessees are required to notify this Agency immediately of the 

discovery of any potential archaeological resources. 

Offshore oil and gas activities resulting from the proposed action could impact an archaeological 

resource because of incomplete knowledge on the location of these sites in the Gulf. The risk of contact 

to archaeological resources is greater in instances where archaeological survey data is unavailable. Such 

an event could result in the disturbance or destruction of important archaeological information. 

Archaeological surveys, where required, would provide the necessary information to develop avoidance 

strategies that would reduce the potential for impacts on archaeological resources. 

Except for the projected 0-1 new gas processing plants and 0-1 new pipeline landfall, the CPA 

proposed action would require no new oil and gas coastal infrastructure. It is expected that archaeological 

resources would be protected through the review and approval processes of the various Federal, State, and 

local agencies involved in permitting onshore activities. 

Accidental events producing oil spills may threaten archaeological resources along the Gulf Coast. 

Should a spill contact an historic archaeological site (including submerged sites), damage might include 

direct impact from oil-spill cleanup equipment, contamination of materials, and/or looting. The major 

effect from an oil-spill impact would be visual contamination of a historic coastal site, such as a historic 

fort or lighthouse. It is expected that any spill cleanup operations would be considered a Federal action 

for the purposes of Section 106 of the NHPA and would be conducted in such a way as to cause little or 

no impacts to historic archaeological resources. Recent research suggests the impact of direct contact of 

oil on historic properties may be long term and not easily reversible without risking damage to fragile 

historic materials. Previously unrecorded sites could be impacted by oil-spill cleanup operations on 

beaches. As indicated in Chapter 4.3.1.8 of the Multisale EIS, it is not very likely for an oil spill to occur 

and contact submerged, coastal, or barrier island historic sites as a result of the CPA proposed action. 

The potential for spills is low, the effects would generally be temporary and localized, and the cleanup 

efforts would be regulated. 

The proposed action is not expected to result in impacts to historic archaeological sites; however, 

should such an impact occur, unique or significant archaeological information could be lost and this 

impact could be irreversible. 

Prehistoric (Chapter 4.1.1.20.2) 

The greatest potential impact to an archaeological resource as a result of the CPA proposed action 

would result from direct contact between an offshore activity (i.e., platform installation, drilling rig 

emplacement, and dredging or pipeline project) and a prehistoric site. Prehistoric archaeological sites are 

thought potentially to be preserved shoreward of the 45-m (148-ft) bathymetric contour, where the Gulf of 

Mexico continental shelf was subaerially exposed during the Late Pleistocene. The archaeological survey 

and archaeological clearance of sites required prior to an operator beginning oil and gas activities on a 

lease are expected to be somewhat effective at identifying submerged landforms that could support 

possible archaeological sites. The NTL 2005-G07 provides guidance for establishing a 300-m (984-ft) 

linespacing for remote-sensing surveys of leases within areas having a high potential for prehistoric sites. 
Alternatives Including the Proposed Action 2-23 

While the survey and clearance provide a reduction in the potential for a damaging interaction between an 

impact-producing factor and a prehistoric archaeological site, there is a possibility of an OCS activity 

contacting an archaeological site because of an insufficiently dense survey grid. Should such contact 

occur, there would be damage to or loss of significant and/or unique archaeological information. Except 

for the projected 0-1 new gas processing plants and 0-1 new pipeline landfall, the CPA proposed action 

would require no new oil and gas coastal infrastructure. It is expected that archaeological resources 

would be protected through the review and approval processes of the various Federal, State, and local 

agencies involved in permitting onshore activities. 

Accidental events producing oil spills may threaten archaeological resources along the Gulf Coast. 

Should a spill contact a prehistoric archaeological site, damage might include loss of radiocarbon-dating 

potential, direct impact from oil-spill cleanup equipment, and/or looting. Previously unrecorded sites 

could be impacted by oil-spill cleanup operations on beaches. As indicated in Chapter 4.3.1.8 of the 

Multisale EIS, it is not very likely for an oil spill to occur and contact coastal and barrier island 

prehistoric sites as a result of the CPA proposed action. The proposed action, therefore, is not expected to 

result in impacts to prehistoric archaeological sites. 

Human Resources and Land Use (Chapter 4.1.1.21) 

Land Use and Coastal Infrastructure (Chapter 4.1.1.21.1) 

The impacts of routine events associated with the CPA proposed action are uncertain due to the postDWH event environment, lingering effects of the drilling suspensions, changes in Federal requirements 

for drilling safety, and temporary interruption of the permit approval process. The BOEMRE projects 0-1 

new gas processing facilities and 0-1 new pipeline landfalls for the proposed action. However, based on 

the most current information available, there is a very slim chance that either would result from the CPA 

proposed action, and if a new gas processing facility or pipeline landfall were to result, it would likely 

occur toward the end of the 40-year analysis period. The likelihood of a new gas processing facility or 

pipeline landfall is much closer to zero than to one. The BOEMRE anticipates that there would be 

maintenance dredging of navigation channels and an increase in activity at services bases as a result of the 

CPA proposed action. If drilling activity recovers post-DWH event and increases, there could be new 

increased demand for a waste disposal services as a result of the CPA proposed action. Because of the 

current near zero estimates for pipeline landfalls and processing facility construction, the routine activities 

associated with the CPA proposed action would have little effect on land use. 

As a result of the DWH event, it is too early to determine substantial, long-term changes in routine 

event impacts to land use and infrastructure. The BOEMRE anticipates these changes would become 

apparent over time. Therefore, BOEMRE recognizes the need to continue monitoring all resources for 

changes that are applicable for land use and infrastructure. From the information that is currently 

available, in regard to land use and infrastructure, it does not appear that there would be adverse impacts 

from routine events associated with the CPA proposed action. 

Many of the impacts of the DWH event to land use and infrastructure have been temporary and shortterm, such as the ship decontamination sites and the waste staging areas established in the immediate 

aftermath of the DWH event. The indirect effects on infrastructure use are still rippling through the 

industry, but this should be resolved as issues with the suspensions, permitting, etc. are resolved. With 

regards to land use and infrastructure, the post-DWH event environment remains somewhat dynamic, and 

BOEMRE will continue to monitor these resources over time and to document short- and long-term DWH 

event impacts. In the future, the long-term impacts of the DWH event will be clearer as time allows the 

production of peer-reviewed research and targeted studies that determine those impacts. The DWH event 

was a low-probability, high-impact catastrophic event. For the reasons set forth in the analysis above, the 

kinds of accidental events that are likely to result from the CPA proposed action are not likely to 

significantly affect land use and coastal infrastructure. This is because accidental events offshore would 

have a small probability of impacting onshore resources. Also, if an accident occurs nearshore, it would 

be most probably be near a facility; therefore, the impacts would be temporary and localized because of 

the decrease in response time. 
2-24 Central Planning Area Supplemental EIS 

Demographics (Chapter 4.1.1.21.2) 

The CPA proposed action is projected to minimally affect the demography of the analysis area. 

Population impacts from the proposed action are projected to be minimal (<1% of the total population) 

for any economic impact area (EIA) in the Gulf of Mexico region (Figure 2-2). The baseline population 

patterns and distributions, as projected and described in Chapter 4.1.1.21.2.1, are expected to remain 

unchanged as a result of the CPA proposed action. The increase in employment is expected to be met 

primarily with the existing population and available labor force, with the exception of some in-migration 

projected to occur in focal areas, such as Port Fourchon. 

Accidental events associated with the CPA proposed action, such as oil or chemical spills, blowouts, 

and vessel collisions, would likely have no effects on the demographic characteristics of the Gulf coastal 

communities. This is because net employment impacts from a spill are not expected to exceed 1 percent 

of baseline employment for any EIA in any given year, even if they are included with employment 

associated with routine oil and gas development activities associated with the CPA proposed action and if 

population changes are derived from employment changes. 

Economic Factors (Chapter 4.1.1.21.3) 

Should the CPA proposed action occur, there would be only minor economic changes in the Texas, 

Louisiana, Mississippi, Alabama, and Florida EIA’s. This is because the demand would be met primarily 

with the existing population and labor force. The CPA proposed action is expected to generate less than a 

1 percent increase in employment in any of these subareas. Most of the employment related to the CPA 

proposed action is expected to occur in Texas (EIA TX-3) and Louisiana (EIA’s LA-2, LA-3, and LA-4). 

The short-term social and economic consequences for the Gulf coastal region should a spill 

≥1,000 bbl occur includes the opportunity cost of employment and expenditures that could have gone to 

production or consumption rather the spill cleanup efforts. Nonmarket effects such as traffic congestion, 

strains on public services, shortages of commodities or services, and disruptions to the normal patterns of 

activities or expectations are also expected to occur in the short term. These negative, short-term social 

and economic consequences of a spill are expected to be modest in terms of projected cleanup 

expenditures and the number of people employed in cleanup and remediation activities. Negative, longterm economic and social impacts may be more substantial if fishing, shrimping, oystering, and/or 

tourism were to suffer or were to be perceived as having suffered because of the spill or if there were 

substantial changes to the energy industries in the region as a result of the spill. Net employment impacts 

from a spill are not expected to exceed 1 percent of baseline employment for any EIA in any given year 

even if they are included with employment associated with routine oil and gas development activities 

associated with the CPA proposed action. 

Environmental Justice (Chapter 4.1.1.21.4) 

Because of the existing extensive and widespread support system for OCS-related industry and 

associated labor force, the effects of the CPA proposed action are expected to be widely distributed and to 

have little impact. This is because the proposed action is not expected to significantly change most of the 

existing conditions such as traffic or the amount of infrastructure. In general, who would be hired and 

where new infrastructure might be located is impossible to predict but, in any case, it would be very 

limited. Because of Louisiana’s extensive oil-related support system, that State is likely to experience 

more employment effects related to the CPA proposed action than are the other coastal states, and 

because of the concentration of this system in Lafourche Parish, that parish is likely to experience the 

greatest benefits from employment benefits and burdens from traffic and infrastructure demand. 

Similarly, impacts related to the CPA proposed action are expected to be economic and to have a limited 

but positive effect on low-income and minority populations, particularly in Louisiana and Lafourche 

Parish. However, given the low levels of expected effects and given the existing distribution of the 

industry and the limited concentrations of minority and low-income peoples, the CPA proposed action is 

not expected to have a disproportionate effect on these populations even in Lafourche Parish. 

Future changes in activity levels would most likely be caused by fluctuations in oil prices and 

imports, and not by activities related to the proposed action. The CPA proposed action is not expected to 

have disproportionate high/adverse environmental or health effects on minority or low-income people. 
Alternatives Including the Proposed Action 2-25 

Chemical and drilling-fluid spills may be associated with exploration, production, or transportation 

activities that result from the CPA proposed action. Low-income and minority populations might be 

more sensitive to oil spills in coastal waters than is the general population because of their dietary reliance 

on wild coastal resources, their reliance on these resources for other subsistence purposes such as sharing 

and bartering, their limited flexibility in substituting wild resources with purchased ones, and their 

likelihood of participating in cleanup efforts and other mitigating activities. With the exception of a 

catastrophic accidental event, such as the DWH event, the impacts of oil spills, vessel collisions, and 

chemical/drilling fluid spills are not likely to be of sufficient duration to have adverse and 

disproportionate long-term effects for low-income and minority communities in the analysis area. 

An event like the DWH event could have adverse and disproportionate effects for low-income and 

minority communities in the analysis area. Many of the long-term impacts of the DWH event to lowincome and minority communities are unknown. While economic impacts have been partially mitigated 

by employers retaining employees for delayed maintenance or through the Gulf Coast Claims Facility 

Program’s emergency funds, the physical and mental health effects to both children and adults within 

these communities could potentially unfold for many years. As studies of past oil spills have highlighted, 

different cultural groups can possess varying capacities to cope with these types of events. Likewise, 

some low-income and/or minority groups may be more reliant on natural resources and/or less equipped 

to substitute contaminated or inaccessible natural resources with private market offerings. Because 

lower-income and/or minority communities may live near and directly involved with spill cleanup efforts, 

the vectors of exposure can be higher for them than for the general population, increasing the potential 

risks of long-term health affects. To date, there have been no longitudinal epidemiological studies of 

possible long-term health effects for oil-spill cleanup workers. The post-DWH event human environment 

remains dynamic, and BOEMRE will continue to monitor these populations over time and to document 

short- and long-term DWH event impacts. In the future, the long-term impacts of the DWH event will be 

clearer as time allows the production of peer-reviewed research and targeted studies that determine those 

impacts. 

The DWH event was a low-probability, high-impact catastrophic event. For the reasons set forth in 

the analysis above, the kinds of accidental events (smaller, shorter time scale) that are likely to result from 

the CPA proposed action may affect low-income and/or minority more than the general population, at 

least in the shorter term. These higher risk groups may lack the financial or social resources and may be 

more sensitive and less equipped to cope with the disruption these events pose. These smaller events, 

however, are not likely to significantly affect minority and low-income communities in the long term. 

Additional Resources Considered due to the Deepwater Horizon Event (Chapter 4.1.1.22) 

Soft Bottoms (Chapter 4.1.1.22.1) 

Although localized impacts to comparatively small areas of the soft-bottom benthic habitats would 

occur, the routine impacts of the proposed action would be on a relatively small area of the seafloor 

compared with the overall area of the seafloor of the CPA (268,922 km2

; 103,831 mi2). The greatest 

impact is the alteration of benthic communities as a result of smothering, chemical toxicity, and substrate 

change. Communities that are smothered by cuttings repopulate, and populations that are eliminated as a 

result of sediment toxicity or organic enrichment would be taken over by more tolerant species. The 

community alterations are not so much the introduction of a new benthic community as a shift in species 

dominance. These localized impacts generally occur within a few hundred meters of platforms, and the 

greatest impacts are seen close to the platform. These patchy habitats within the Gulf of Mexico are 

probably not very different from the early successional communities that predominate throughout areas of 

the Gulf of Mexico that are frequently disturbed. 

Only a very small portion of the seafloor of the Gulf of Mexico would experience lethal impacts as a 

result of blowouts, surface, and subsurface oil spills and the associated effects. This is because of the 

small amount of proportional space that OCS activities occupy on the seafloor. The greatest impacts 

would be closest to the spill, and impacts would decrease with distance from the spill. Contact with 

spilled oil at a distance from the spill would likely cause sublethal to immeasurable effects to benthic 

organisms because the distance of activity would prevent contact with concentrated oil. Oil from a 

subsurface spill that reaches benthic communities would be primarily sublethal and impacts would be at 

the local community level. Any sedimentation and sedimented oil would also be at low concentrations by 
2-26 Central Planning Area Supplemental EIS 

the time it reaches benthic communities far from the location of the spill, also resulting in sublethal 

impacts. Also, any local communities that are lost would be repopulated fairly rapidly. Although an oil 

spill may have some detrimental impacts, especially closest to the occurrence of the spill, the impacts may 

be no greater than natural biological fluctuations, and impacts would be to an extremely small portion of 

the overall Gulf of Mexico. 

Diamondback Terrapins (Chapter 4.1.1.22.2) 

Routine activities resulting from the CPA proposed action is possible but unlikely. Because of the 

greatly improved handling of waste and trash by industry and the annual awareness training required by 

the marine debris mitigations, the plastics in the ocean are decreasing and the devastating effects on 

offshore and coastal marine life are being minimized. The routine activities of the CPA proposed action 

are unlikely to have significant adverse effects on the size and recovery of any terrapin species or 

population in the GOM. 

Habitat destruction, road construction, and drowning in crab traps are the most recent threats to 

diamondback terrapins. In the 1800’s, populations declined due to overharvesting for meat. Tropical 

storms, hurricanes, and beach erosion threaten their preferred nesting habitats. Destruction of the 

remaining habitat due to a catastrophic spill and response efforts could drastically affect future population 

levels and reproduction. However, there is not expected to be a significant increase to infrastructure, and 

the probability of a spill large enough to impact the diamondback terrapins or their habitat is low with the 

CPA proposed action. 

No substantial information was found at this time that would alter the overall conclusion that 

accidental impacts on diamondback terrapins associated with the CPA proposed action would be minimal. 

2.3.1.3. Mitigating Measures 

The following eight environmental and military mitigations, referred to as lease stipulations, were 

included for analysis in the Chapter 2.4.1.3 of the Multisale EIS and in Chapter 2.2.1.3.of the 2009-2012 

Supplemental EIS. Any stipulations or mitigation requirements to be included in the lease sale will be 

described in detail in the Final NOS. Stipulations or mitigation requirements in addition to the those 

analyzed in this Supplemental EIS can also be developed and applied, and will also be described in detail 

in the Final NOS. 

2.3.1.3.1. Topographic Features Stipulation 

The Topographic Features Stipulation protects the biota of the topographic features from adverse 

effects due to routine oil and gas activities, including physical damage from anchoring and rig 

emplacement and the potential toxic and smothering effects from muds and cuttings discharges. The 

Topographic Features Stipulation has been included in leases since 1973 and has effectively prevented 

damage to the biota of these banks from routine oil and gas activities such as anchoring. Monitoring 

studies have demonstrated that the shunting requirements of the stipulation are effective in preventing the 

drilling mud and cuttings from impacting the biota of the banks. The topographic highs on and near these 

blocks are often associated with salt domes, which are attractive areas for hydrocarbon exploration. 

Instead, blocks on the topographic features have been offered for lease with a stipulation that has proven 

effective in protecting sensitive biological resources. The location of the blocks affected by the 

Topographic Features Stipulation is shown on Figure 2-1. 

2.3.1.3.2. Live Bottoms (Pinnacle Trend and Low Relief) Stipulation 

The Live Bottom (Pinnacle Trend) Stipulation covers a small portion of the northeastern CPA lease 

sale area that is characterized by a pinnacle trend, which is classified as a live bottom under the 

stipulation. The Live Bottom (Low Relief) Stipulation defines low-relief areas as seagrass communities, 

areas that contain biological assemblages consisting of sessile invertebrates living upon and attached to 

naturally occurring hard or rocky formations with rough, broken, or smooth topography; and areas where 

a hard substrate and vertical relief may favor the accumulation of turtles, fish, or other fauna. This 

Agency developed the stipulation to protect biological resources in the Pinnacle Trend and low relief in 
Alternatives Including the Proposed Action 2-27 

response to concerns that disturbing any of the series of topographic irregularities might adversely affect 

biological communities that have developed on the surfaces of the features and affect the habitat they 

provide for pelagic fishes. The stipulation requires avoidance of the features during the placement of oil 

and gas structures and the laying of pipelines. The stipulation has been adopted in CPA lease sales since 

1990 and has been effective in protecting the features and resident biological communities from damage. 

The location of the blocks affected by the Live Bottom (Pinnacle Trend and Low Relief) Stipulation is 

shown on Figure 2-1. 

2.3.1.3.3. Military Areas Stipulation 

The Military Areas Stipulation has been applied to all blocks leased in military areas since 1977 and 

reduces potential impacts, particularly in regards to safety; but it does not reduce or eliminate the actual 

physical presence of oil and gas operations in areas where military operations are conducted. The 

stipulation contains a “hold harmless” clause (holding the U.S. Government harmless in case of an 

accident involving military operations) and requires lessees to coordinate their activities with appropriate 

local military contacts. Figure 2-3 shows the military warning areas in the Gulf of Mexico. 

2.3.1.3.4. Evacuation Stipulation 

The Evacuation Stipulation would apply to any lease in the easternmost portion of the CPA lease sale 

area. This stipulation was developed in consultation with the U.S. Department of Defense (DOD) to 

address specific potential use conflict issues between oil and gas operations and military operations in the 

GOM. An evacuation stipulation has been applied to all blocks leased in this area since 2001. This 

stipulation would provide for the evacuation of personnel and the shut-in of operations during any events 

conducted by the military that could pose a danger to ongoing oil and gas operations. It is expected that 

these measures would serve to eliminate dangerous conflicts between oil and gas operations and military 

operations. 

2.3.1.3.5. Coordination Stipulation 

The Coordination Stipulation would apply to any lease in the easternmost portion of the CPA lease 

sale area. This stipulation was developed in consultation with DOD to address specific potential use 

conflict issues between oil and gas operations and military operations in the GOM. A coordination 

stipulation has been applied to all blocks leased in this area since 2001. This stipulation would provide 

for the review of pending oil and gas operations by military authorities and could result in delaying oil 

and gas operations if military activities have been scheduled in the area that may put oil and gas 

operations, equipment, and personnel at risk. 

2.3.1.3.6. Blocks South of Baldwin County, Alabama, Stipulation 

The Blocks South of Baldwin County, Alabama, Coast Stipulation would be included only on leases 

south of and within 15 mi (24 km) of Baldwin County, Alabama (Figure 2-1). For several years, the 

Governor of Alabama has continually indicated opposition to new leasing south and within 15 mi (24 km) 

of Baldwin County but has requested that, if the area is offered for lease, a lease stipulation to reduce the 

potential for visual impacts be applied to all new leases in this area. Prior to the decision in 1999 on the 

Final Notice of Sale for Sale 172, the Gulf of Mexico OCS Regional Director, in consultation with the 

Geological Survey of Alabama/State Oil and Gas Board, developed a lease stipulation to be applied to 

any new leases within the 15-mi (24-km) area to mitigate potential visual impacts. The stipulation 

specifies requirements for consultation that lessees must follow when developing plans for fixed 

structures. The stipulation has been continually adopted in annual CPA lease sales since 1999. 

2.3.1.3.7. Protected Species Stipulation 

The Protected Species Stipulation has been applied to all blocks leased in the GOM since December 

2001. This stipulation was developed in consultation with the Department of Commerce, NOAA, NMFS, 
2-28 Central Planning Area Supplemental EIS 

and the Department of the Interior, FWS in accordance with Section 7 of the ESA and is designed to 

minimize or avoid potential adverse impacts to federally protected species. 

2.3.1.3.8. Law of the Sea Convention Royalty Payment Stipulation 

The Law of the Sea Convention Royalty Payment Stipulation applies to blocks or portions of blocks 

beyond the U.S. Exclusive Economic Zone (generally greater than 200 nmi [230 mi; 370 km] from the 

U.S. coastline). Leases on these blocks may be subject to special royalty payments under the provisions 

of the 1982 Law of the Sea Convention (consistent with Article 82), if the U.S. becomes a party to the 

Convention prior to or during the life of the lease. 

2.3.2. Alternative B—The Proposed Action Excluding the Unleased Blocks Near 

the Biologically Sensitive Topographic Features 

2.3.2.1. Description 

Alternative B differs from Alternative A by not offering the blocks that are possibly affected by the 

proposed Topographic Features Stipulation (Chapter 2.3.1.3.1 and Figure 2-1). All of the assumptions 

(including the seven other potential mitigating measures) and estimates are the same as for Alternative A. 

A description of Alternative A is presented in Chapter 2.3.1.1. 

2.3.2.2. Summary of Impacts 

The analyses of impacts summarized in Chapter 2.3.1.2 and described in detail in Chapter 4 are 

based on the development scenario, which is a set of assumptions and estimates on the amounts, 

locations, and timing for OCS exploration, development, and production operations and facilities, both 

offshore and onshore. A detailed discussion of the development scenario and major related impactproducing factors is included in Chapter 3. 

The difference between the potential impacts described for Alternative A and those under 

Alternative B is that under Alternative B no oil and gas activity would take place in the blocks subject to 

the Topographic Features Stipulation (Figure 2-1). The number of blocks that would not be offered 

under Alternative B represents only a small percentage of the total number of blocks to be offered under 

Alternative A; therefore, it is assumed that the levels of activity for Alternative B would be essentially the 

same as those projected for the proposed action. As a result, the impacts expected to result from 

Alternative B would be very similar to those described under the proposed action (Chapter 4). 

Therefore, the regional impact levels for all resources, except for the topographic features, would be 

similar to those described under the proposed action. This alternative, if adopted, would prevent any oil 

and gas activity whatsoever in the affected blocks; thus, it would eliminate any potential direct impacts to 

the biota of those blocks from oil and gas activities, which otherwise would be conducted within the 

blocks. 

2.3.3. Alternative C—The Proposed Action Excluding the Unleased Blocks 

within 15 Miles of the Baldwin County, Alabama, Coast 

2.3.3.1. Description 

Alternative C differs from Alternative A by not offering any unleased blocks within 15 mi (24 km) of 

the Baldwin County, Alabama, coast. All of the assumptions (including the seven other potential 

mitigating measures) and estimates are the same as for Alternative A (Chapters 2.3.1.3 and 4.1). A 

description of Alternative A is presented in Chapter 2.3.1.1. The coastal region adjacent to the area 

considered under Alternative C is designated as EIA AL-1 (Figure 2-2). 

2.3.3.2. Summary of Impacts 

The analyses of impacts summarized in Chapter 2.3.1.2 and described in detail in Chapter 4.1 are 

based on the development scenario, which is a set of assumptions and estimates on the amounts, 
Alternatives Including the Proposed Action 2-29 

locations, and timing for OCS exploration, development, and production operations and facilities, both 

offshore and onshore. A detailed discussion of the development scenario and major related impactproducing factors is included in Chapter 3. 

The difference between the potential impacts described for Alternative A and those under 

Alternative C is that under Alternative C no oil and gas activity would take place in blocks within 15 mi 

(24 km) of the Baldwin County coast (Figure 2-1). The assumption that the levels of activity for 

Alternative C are essentially the same as those projected for the proposed action leads to the conclusion 

that the impacts expected to result from Alternative C would be very similar to those described under the 

proposed action (Chapter 4). Therefore, the regional impact levels for all resources, except the visual 

impact from recreational beaches, would be similar to those described under the proposed action. This 

alternative, if adopted, would reduce the potential aesthetic impacts to recreational beaches along the 

Baldwin County coast. 

2.3.4. Alternative D—No Action 

2.3.4.1. Description 

Alternative D is the cancellation of the proposed CPA lease sale. The opportunity for development of 

the estimated 0.801-1.624 BBO and 3.332-6.560 Tcf of gas that could have resulted from the proposed 

lease sale would be precluded or postponed. Any potential environmental impacts resulting from the 

proposed lease sale would not occur or would be postponed. 

2.3.4.2. Summary of Impacts 

Canceling the lease sale would eliminate the effects described for Alternative A (Chapter 4.1). The 

incremental contribution of the proposed lease sale to cumulative effects would also be avoided, but 

effects from other activities, including other OCS lease sales, would remain. 

If the lease sale would be canceled, the resulting development of oil and gas would most likely be 

postponed to a future sale; therefore, the overall level of OCS activity in the CPA would only be reduced 

by a small percentage, if any. Therefore, the cancellation of the proposed lease sale would not 

significantly change the environmental impacts of overall OCS activity. However, the cancellation of the 

lease sale may result in direct economic impacts to the individual companies. Revenues collected by the 

Federal Government (and thus revenue disbursements to the States) would be adversely affected also. 

Other sources of energy may substitute for the lost production. Principal substitutes would be 

additional imports, conservation, additional domestic production, and switching to other fuels. These 

alternatives, except conservation, have significant negative environmental impacts of their own. 
CHAPTER 3 

IMPACT-PRODUCING FACTORS AND SCENARIO
Impact-Producing Factors and Scenario 3-3 

3. IMPACT-PRODUCING FACTORS AND SCENARIO 

In order to describe the level of activity that could reasonably result from the proposed action (i.e., 

proposed lease sale), BOEMRE developed exploration and development activity scenarios. These 

scenarios provide a framework for analyses of potential environmental and socioeconomic impacts of the 

proposed lease sale that could potentially affect the biological, physical, and socioeconomic resources of 

the Gulf of Mexico. The offshore and coastal impact-producing factors and scenario can be found in 

Chapters 4.1.1 and 4.1.2 of the Multisale EIS, respectively, and in Chapters 3.1.1 and 3.1.2 of the 2009-

2012 Supplemental EIS, respectively. The following is a summary of offshore and coastal impactproducing factors with activity scenarios from the Multisale EIS and the 2009-2012 Supplemental EIS, 

and new information that has become available since both documents were prepared. 

The potential impacts of the offshore and coastal activities associated with proposed CPA Lease Sale 

216/222 are considered in the environmental analysis sections in Chapter 4. 

3.1. IMPACT-PRODUCING FACTORS AND SCENARIO—ROUTINE OPERATIONS

3.1.1. Offshore Impact-Producing Factors and Scenario 

Chapter 4.1.1 of the Multisale EIS and Chapter 3.1.1 of the 2009-2012 Supplemental EIS describe the 

infrastructure and activities (impact-producing factors) that would occur offshore as a result of a proposed 

action. Those discussions are incorporated by reference. 

Offshore is defined here as the OCS portion of the GOM that begins 10 mi (16 km) offshore Florida; 

3 nmi (3 mi; 6 km) offshore Louisiana, Mississippi, and Alabama; it extends seaward to the limits of the 

U.S. Exclusive Economic Zone (Figure 1-1). The projections used to develop the offshore proposed 

action scenarios are based on resource estimates as summarized in the Planning Area Resources 

Addendum to Assessment of Undiscovered Technically Recoverable Oil and Gas Resources of the 

Nation’s Outer Continental Shelf, 2006 (USDOI, MMS, 2006a), current industry information, and 

historical trends. 

The proposed action scenarios are based on the following factors: 

 recent trends in the amount and location of leasing, exploration, and development 

activity; 

 estimates of undiscovered, unleased, conventionally recoverable oil and gas resources 

in the planning area; 

 existing offshore and onshore oil and/or gas infrastructure; 

 industry information; and 

 oil and gas technologies, and the economic considerations and environmental 

constraints of these technologies. 

In order to present the best reasonable projections possible, BOEMRE continually updates models 

and formulas used to develop these scenarios. The experience of subject matter experts is incorporated 

into this process, along with the latest industry trends and historical data. 

The proposed lease sale is represented by bounded ranges for resource estimates, projected 

exploration and development activities, and impact-producing factors. The proposed lease sale is 

expected to be within the scenario ranges. The scenarios used in this Supplemental EIS represent the best 

assumptions and estimates of a set of future conditions that are considered reasonably foreseeable after 

the DWH event and suitable for presale impact analyses. These scenarios do not represent a BOEMRE 

recommendation, preference, or endorsement of any level of leasing or offshore operations, or of the 

types, numbers, and/or locations of any onshore operations or facilities. 
3-4 Central Planning Area Supplemental EIS

Analysis Period 

The BOEMRE assumes fields discovered as a result of a proposed action will reach the end of their 

economic life within 40 years of the lease sale. Activity levels are not projected beyond 40 years. This is 

based on averages for time required for exploration, development, production life, and decommissioning 

for leases in the GOM. 

Deepwater Horizon Event 

This Supplemental EIS is being prepared because of the potential changes to baseline conditions of 

the environmental, socioeconomic, and cultural resources that may have occurred as a result of (1) the 

DWH event between April 20 and July 15, 2010 (the period when oil flowed from the Macondo well in 

Mississippi Canyon Block 252 [Figure 1-2]); (2) the acute impacts that have been reported or surveyed 

since that time; and (3) any new information that may be available. The environmental resources include 

sensitive coastal environments, offshore benthic resources, marine mammals, sea turtles, coastal and 

marine birds, endangered and threatened species, and fisheries. This Supplemental EIS analyzes the 

potential impacts of the proposed action on the marine, coastal, and human environments. 

The BOEMRE, Gulf of Mexico OCS Region, Resource and Evaluation Office’s Modeling and 

Forecasting Team has reevaluated the exploration and development activity scenario for a CPA proposed 

action because of the DWH event. 

Resource Estimate and Timetables 

The resource estimates for a proposed action are based on two factors: (1) the conditional estimates 

of undiscovered, unleased, conventionally recoverable oil and gas resources in the proposed lease sale 

areas; and (2) the estimates of the portion or percentage of these resources assumed to be leased, 

discovered, developed, and produced as a result of a proposed action. The estimates of undiscovered, 

unleased, conventionally recoverable oil and gas resources are based upon a comprehensive appraisal of 

the conventionally recoverable petroleum resources of the Nation as of January 1, 2003. Because of the 

inherent uncertainties associated with an assessment of undiscovered resources, techniques were 

employed and the results were reported as a range of values corresponding to different probabilities of 

occurrence. 

A summarized discussion of the methodologies employed and the results obtained in the assessment 

are presented in this Agency’s brochure entitled, Planning Area Resources Addendum to Assessment of 

Undiscovered Technically Recoverable Oil and Gas Resources of the Nation’s Outer Continental Shelf, 

2006 (USDOI, MMS, 2006a). The estimates of the portion of the resources projected to be leased, 

discovered, developed, and produced as a result of a proposed action are based upon logical sequences of 

events that incorporate past experience, current conditions, and foreseeable development strategies. A 

wealth of historical databases and information derived from oil and gas exploration and development 

activities are available to BOEMRE and were used extensively. The undiscovered, unleased, 

conventionally recoverable resource estimates for a proposed action are expressed as ranges, from low to 

high. This range provides a reasonable expectation of oil and gas production anticipated from typical 

lease sales held as a result of the proposed actions based on an actual range of historic observations. 

Table 3-1 presents the projected ranges for oil and gas production resulting from the proposed CPA 

lease sale. Major impact-producing factors, including the number of exploration and delineation wells, 

production platforms, and development wells projected to develop and produce the estimated resources 

for the CPA proposed action, are given in Table 3-2. Table 3-2 shows the distribution of these factors by 

offshore subareas in the proposed lease sale area. The proposed lease sale area was divided into offshore 

subareas based upon water-depth range (Figure 3-1) that reflect the technological requirements and 

related physical and economic impacts. 

For purposes of analysis, the life of the leases resulting from the proposed action is assumed to not 

exceed 40 years because, historically, the entire life of a well from beginning to end is encompassed 

within a 40-year period. Following the proposed action (lease sale), areawide exploratory drilling activity 

would take place over an 8-year period, beginning within 1 year after the lease sale. Final 

decommissioning and removal activities occur from the 15th year to the 40th year. 
Impact-Producing Factors and Scenario 3-5 

Activity as the result of a lease sale is assumed to be staggered over time. A recently published 

Agency study estimated physical and economic performance measures to characterize lease sales and 

development in the GOM (Iledare and Kaiser, 2007). It was used to further refine the scenario presented 

in the Multisale EIS. The average lag of exploration and production from leases issued from 1983 to 

1999 increased by water depth and decreased over time as shown in the Tables 3-4 and 3-5 in the 2009-

2012 Supplemental EIS. Because of variation by water depth, exploration and production activity is 

staggered over time, taking on average 1.9-4.5 years after a lease sale before exploration begins and 

3.4-8.3 years before first production. 

3.1.1.1. Exploration and Delineation 

Chapter 4.1.1.2.2 of the Multisale EIS and Chapter 3.1.1.1 of the 2009-2012 Supplemental EIS 

describe the impacting factors arising from exploration and delineation drilling in the GOM resulting 

from a proposed action in the CPA. The discussion in this Supplemental EIS tiers from the discussion in 

the Multisale EIS and the 2009-2012 Supplemental EIS. 

3.1.1.1.1. Seismic Surveying Operations 

Prelease surveys are comprised of seismic work performed on or off leased areas, focused most 

commonly (but not always) on deeper targets and collectively authorized under BOEMRE’s geological 

and geophysical permitting process. Postlease, high-resolution seismic surveys collect data on surficial 

geology used to identify potential shallow geologic hazards for engineering and site planning for bottomfounded structures. They are also used to identify environmental resources such as chemosynthetic 

community habitat, gas hydrates, and archaeological resources. High-resolution surveys are conducted as 

authorized under the terms and conditions of the lease agreement. Other postlease surveys include 

downhole seismic surveying (vertical seismic profiling [VSP]) and time-lapse, deep-focused, 

3D surveying (4D surveys) used for reservoir monitoring. 

All seismic surveying constitutes a type of remote sensing. Typical prelease seismic surveying 

operations for exploring deep geologic formations typically are two- or three-dimensional (2D or 3D) 

surveys. A tow vessel pulls an array of airguns and streamers (acoustic receiver cable) behind the vessel 

5-10 m (16-33 ft) below the sea surface. The airgun array produces underwater sound by releasing 

compressed air into the water column, creating an acoustical energy pulse the echoes of which are 

detected by hydrophones towed on streamers behind the vessel. Streamer arrays are 3-8 mi (5-12 km) or 

greater in length, depending on survey specifications. Tow vessel speed is typically 3-5 knots (kn) (about 

4-6 miles per hour [mph]) with gear deployed. 

The 3D surveys carried out by seismic vendors can consist of a few to several hundred OCS blocks. 

Multiple source and multiple-streamer technologies are often used for 3D seismic surveys. For a typical 

3D survey, air in a closed chamber of the air gun is quickly discharged through a port, creating a pressure 

pulse and air bubble in the water. To release more energy into the pressure pulse and to offset the 

deleterious effects of bubble oscillations on the pressure pulse, multiple airguns with various chamber 

sizes are used. These individual airgun chamber sizes vary from 20 to 380 in3

 (327 to 6,227 cm3). In 

some cases, two or three airguns are placed in a cluster to increase the effective chamber size. The 

individual airguns are suspended in the water from a float system referred to as a sub-array. Each subarray contains six or seven individual airguns spaced from 2.5 to 3 m (7.5 to 10 ft) apart, making the total 

sub-array length 14-17 m (46-56 ft) long. Typically, three (sometimes four) sub-arrays are combined to 

form an array. When three sub-array elements are used, the spacing is 8 m (26 ft) between sub-arrays; 

when four sub-arrays are used, the spacing is 12 m (39 ft). Thus, the overall width of the array is 

generally 16-36 m (52-118 ft). The array is towed at a depth of 5-7 m (16-23 ft). 

A 4D or time-lapse survey is used to monitor reservoir production to optimize the amount of 

hydrocarbon recovered. These surveys consist of a series of 3D surveys collected over time under the 

same acquisition and receiving parameters. 

Vertical seismic profiling (VSP) is usually done by placing a receiver down a wellbore at different 

depths and with an external acoustic source near the wellbore (zero-offset VSP) or on a vessel at different 

distances from the wellbore (a walk-away VSP). These surveys are used to obtain information about the 

nature of the seismic signal, as well as more information about the geology surrounding the vertical array 

of sensors. The VSP data can be cross-correlated with ship-towed seismic survey datasets to refine 
3-6 Central Planning Area Supplemental EIS

identification of lithologic changes and the content of formation fluids. Zero offset and walk-away VSP 

surveys are the most common VSP surveys conducted in the GOM. 

Ocean-Bottom Surveys 

Ocean-bottom cable surveys were originally designed to enable seismic surveys in congested areas, 

such as producing fields, with their many platforms and producing facilities. Autonomous nodes, 

deployed and retrieved by either cable or ROV’s, are now used as an alternative to cables. The oceanbottom cable surveys have been found to be useful for obtaining multicomponent (i.e., seismic pressure, 

vertical, and the two horizontal motions of the water bottom, or seafloor) information. 

The ocean-bottom cable surveys and nodal acquisition require the use of multiple ships (i.e., usually 

two ships for cable or node layout/pickup, one ship for recording, one ship for shooting, and two utility 

boats). These ships are generally smaller than those used in streamer operations, and the utility boats can 

be very small. Operations are conducted “around the clock” and begin by dropping the cables off the 

back of the layout boat or by deployment of the nodal receivers by ROV’s. Cable length or the numbers 

of nodes depend upon the survey demands; it is typically 2.6 mi (4.2 km) but can be up to 7.5 mi (12 km). 

However, depending on spacing and surveys size, hundreds of nodes can be deployed and re-deployed 

over the span of the survey. Groups of seismic detectors, usually hydrophones and vertical motion 

geophones, are attached to the cable in intervals of 82-164 ft (25-50 m) or autonomous nodes are spaced 

similarly. Multiple cables/nodes are laid parallel to each other using this layout method, with a 164-ft 

(50-m) interval between cables/nodes. Typically, dual airgun arrays are used on a single source vessel. 

When the cable/node is in place, a ship towing an airgun array (which is the same airgun array used for 

streamer work) passes between the cables/ nodes, firing every 82 ft (25 m). Sometimes a faster source 

ship speed of 7 mph (6 kn), instead of the normal speed of 5.2 mph (4.5 kn), is used with a decrease in 

time between gun firings. After a source line is shot, the source ship takes about 10-15 minutes to turn 

around and pass down between the next two cables or line of nodes. When a cable/node is no longer 

needed to record seismic data, it is picked up by the cable pickup ship and is moved over to the next 

position where it is needed. The nodes are retrieved by an ROV. A particular cable/node can lay on the 

bottom anywhere from 2 hours to several days, depending on operation conditions. Normally, a cable 

will be left in place about 24 hours. However, nodes may remain in place until the survey is completed or 

recovered and then re-deployed by an ROV. 

Location of the cables/nodes on the bottom is done by acoustic pingers located at the detector groups 

and by using the time of first arrival of the seismic pulse at the detector group. A detector group is a node 

or group of nodes that enable the seismic ship to accurately determine node location. To obtain more 

accurate first arrival times, the seismic data are recorded with less electronic filtering than is normally 

used. This detailed location is combined with normal global positioning system (GPS) navigational data 

collected on the source ship. In deep water, the process of accurately locating bottom cables/nodes is 

more difficult because of the effects of irregular water bottoms and the thermal layers, which affect travel 

times and travel paths, thus causing positioning errors. 

As part of the environment impact analysis required with the EP, DOCD, or DPP, 30 CFR 

250.227(b)(6) and 30 CFR 250.261(b)(6) require the applicant to submit archaeological information. In 

certain circumstances, the Regional Director may require the preparation of an archaeological report to 

accompany the EP, DOCD, or DPP, under 30 CFR 250.194. The requirements for archaeological reports 

are clarified in NTL 2005-G07, “Archaeological Resource Surveys and Reports.” If the archaeological 

report required under 30 CFR 250.194 indicates that an archaeological resource may be present, the lessee 

must either locate the site of any operation so as not to adversely affect the area where the archaeological 

resource may be, demonstrate that an archaeological resource does not exist, or demonstrate that 

archaeological resources will not be adversely affected by operations. If the lessee discovers any 

archaeological resource while conducting approved operations, operations must be immediately stopped 

and the discovery reported to the BOEMRE Regional Supervisor, Office of Leasing and Environment, 

within 48 hours of its discovery. 

CPA Proposed Action Scenario: The repetitive, cyclical nature of seismic surveys can afford 

potential lessees with a prelease seismic survey attributable to lease sales held up to 7-9 years after the 

acquisition of that survey. This area may or may not be resurveyed based on new technology, subsurface 

geological trends, or production from other reservoirs. The BOEMRE projects that the CPA proposed 
Impact-Producing Factors and Scenario 3-7 

action would result in 1,500-2,500 mi (2,400-4,000 km) of 2D deep seismic and 1,500-2,000 OCS blocks 

surveyed annually by 3D deep seismic. For postlease seismic surveys, BOEMRE projects the CPA 

proposed action would result in about 3-6 VSP operations and about 3,000-4,000 miles (4,828-6,437 km) 

surveyed by high-resolution seismic during the life of the proposed action.

OCS Program Scenario: Seismic surveys are projected to follow the trends of exploration activities 

until 2027 and to remain relatively steady throughout the second half of the 40-year analysis period. 

During the first 2-4 years of the analysis period, BOEMRE projects that annually there would be 5-10 

VSP operations, 12,500-16,500 lines miles (20,117-24.945 km) surveyed by high-resolution seismic, 

8,000-10,000 mi (12,900-16,000 km) of 2D deep seismic, and 2,500-3,000 OCS blocks surveyed by 3D 

deep seismic. During the second half of the analysis period, it is projected that annually there would be 

510 VSP operations, 6,200-8,300 mi (9,978-13,356 km) surveyed by high-resolution seismic, 6,000-8,000 

mi (9,650-12,900 km) of 2D deep seismic, and 1,500-2,500 OCS blocks surveyed by 3D deep seismic, 

reflecting continuous improvement of data acquisition (or other future technology that may replace this). 

3.1.1.1.2. Exploration and Delineation Drilling 

Oil and gas operators use drilling terms that represent stages in the discovery and exploitation of 

hydrocarbon resources. An exploration well generally refers to the first well drilled on a prospective 

geologic structure to confirm that a resource exists and to validate how much resource can be expected. If 

a resource is discovered in quantities appearing to be economically viable, one or more follow-up 

delineation wells help define the amount of resource or the extent of the reservoir. Following a discovery, 

an operator will often temporarily plug and abandon a discovery to allow time for a development scenario 

to be generated and for equipment to be built or procured. 

In the GOM, exploration and delineation wells are typically drilled with MODU’s; e.g., jack-up rigs, 

semisubmersible rigs, submersible, platform rigs, or drill ships. Non-MODU drilling units, such as inland 

barges, are also used. The type of rig chosen to drill a prospect depends primarily on water depth. 

Because the water-depth ranges for each type of drilling rig overlap to a degree, other factors such as 

availability and daily rates play a large role when an operator decides upon the type of rig to contract. 

The depth ranges for exploration rigs used in this analysis for Gulf of Mexico MODU’s are indicated 

below. 

MODU or Drilling Rig Type Water Depth Range 

Jack-up, submersible, and inland barges ≤100 m 

Semisubmersible and platform rig 100-3,000 m 

Drillship ≥600 m 

Table 3-3 shows GOM deepwater rig counts and average day rates for contracting the typical rig 

types used for OCS exploration, although some operators have discounted prices for multiyear contracts. 

The scenarios for the proposed actions presented in the Multisale EIS assumed that an average 

exploration/delineation well will require 30-45 days to drill. The actual time required for each well 

depends on a variety of factors, including the depth below mudline of the prospect’s potential target zone, 

the complexity of the well design, and the directional offset of the wellbore needed to reach a particular 

zone. 

The cost of an ultra-deepwater well (>6,000 ft; >1,829 m water depth) can be $30-$50 million or 

more, without certainty that objectives can be reached or if the objective ultimately produces 

hydrocarbon. Some recent ultra-deepwater exploration wells in the GOM have been reported to have cost 

upwards of $100 million. The BOEMRE regulations require that operators conduct their offshore 

operations in a safe manner. Subpart D of BOEMRE’s regulations (30 CFR 250) specifies requirements 

for drilling activities. See Chapter 1.3.1 and Table 1-1, which provide a summary of new safety 

requirements. 
3-8 Central Planning Area Supplemental EIS

Exploration Plans 

The regulation at 30 CFR 250 Subpart B specifies the requirements for the exploration plans (EP’s) 

that operators must submit to BOEMRE for approval prior to deploying an exploration program. An EP 

must be submitted to BOEMRE for review and decision before any exploration activities, except for 

preliminary activities, can begin on a lease. The EP describes exploration activities, drilling rig or vessel, 

proposed drilling and well-testing operations, environmental monitoring plans, oil-spill response plans, 

and other relevant information, and it includes a proposed schedule of the exploration activities. 

Guidelines and environmental information requirements for lessees and operators submitting an EP are 

addressed in 30 CFR 250.211 and are further explained in NTL 2010-N06, “Information Requirements 

for Exploration Plans, Development and Production Plans, and Development Operations Coordination 

Documents on the OCS” and NTL 2009-G27, “Submitting Exploration Plans and Development 

Operations Coordination Documents.” The requirements for archaeological and shallow hazard surveys 

and their reports are clarified in NTL 2005-G07, “Archaeological Resource Surveys and Reports” and 

NTL 2008-G05, “Shallow Hazards Program.” 

In addition, the regulations at 30 CFR 250.227(b)(6) and 30 CFR 250.261(b)(6) require the lessee to 

include an archaeological report with an EP or DOCD. If the evidence suggests that an archaeological 

resource may be present, the lessee must either locate the site of any operation so as not to adversely 

affect the area where the archaeological resource may be, demonstrate that an archaeological resource 

does not exist, or demonstrate that archaeological resources will not be adversely affected by operations. 

If the lessee discovers any archaeological resource while conducting approved operations, operations 

must be immediately stopped and the discovery reported to the BOEMRE Regional Supervisor, Office of 

Leasing and Environment, within 48 hours of its discovery. 

Historically, drilling rig availability has been a limiting factor for activity in the Gulf and is assumed 

to be a limiting factor for activity projected as a result of the proposed lease sale. A search on the 

Rigzone website in December 2010 (Rigzone, 2010) showed that operators in the GOM currently had 

commitments for the following rig classes: 83 jack-ups; 25 semisubmersibles; 6 submersibles; 60 inland 

barges; and 10 drillships. Operators had a rig utilization rate of about 68 percent, which means that 

approximately 68 percent of the rigs in the GOM available for contract are contracted and operating. The 

Rigzone website indicates the total worldwide deployment capability for the various rig classes is 523 

jack-ups, 222 semisubmersibles, 6 submersibles, 76 inland barges, and 91 drillships. 

Table 3-2 shows the estimated range of exploration and delineation wells by water depth subarea for 

the CPA proposed action. 

CPA Proposed Action Scenario: The BOEMRE estimates that 65-121 exploration and delineation 

wells would be drilled as a result of the CPA proposed action. Table 3-2 shows the estimated range of 

exploration and delineation wells by water-depth range. Approximately 31-40 percent of the projected 

wells are expected to be on the continental shelf (0-200 m [0-656 ft] water depth) and 60-69 percent are 

expected in the intermediate water-depth ranges and deeper (>200 m; 656 ft). 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. The BOEMRE estimates that 5,010-6,569 exploration and 

delineation wells would be drilled in the CPA as a result of the OCS Program. Tables 4-4, 4-5, and 4-6 of 

the Multisale EIS show the estimated range of exploration and delineation wells by water-depth range. 

Of these wells, 69-71 percent are expected to be on the continental shelf (0-200 m [0-656 ft] water depth) 

and 29-31 percent are expected in intermediate water-depth ranges and deeper (>200 m; 656 ft). 

3.1.1.2. Development and Production 

Chapter 4.1.1.3 of the Multisale EIS and Chapter 3.1.1.2 of the 2009-2012 Supplemental EIS describe 

impacting factors arising from development and production drilling activity in the GOM. The discussion 

in this Supplemental EIS tiers from the discussion in the Multisale EIS and the 2009-2012 Supplemental 

EIS. 

3.1.1.2.1. Development and Production Drilling 

Delineation and production wells are sometimes collectively termed development wells. 

Development wells may be drilled from movable structures, such as jack-up rigs, fixed bottom-supported 
Impact-Producing Factors and Scenario 3-9 

structures, floating vertically moored structures, floating production facilities, and drillships (either 

anchored or dynamically positioned drilling vessels). The type of production structure installed at a site 

depends mainly on water depth, but the total facility lifecycle, the type and quantity of hydrocarbon 

production expected, the number of wells to be drilled and produced, and the number of anticipated 

tiebacks from other fields can also influence an operator’s development facility procurement decision. 

The number of wells per structure varies according to the type of production structure used, the prospect 

size, and the drilling/production strategy deployed for the drilling program and for resource conservation. 

Production systems can be fixed, floating, or subsea, which has shown an increasing trend in deep water. 

This Agency has described and characterized production structures in its deepwater reference 

document (Regg et al., 2000) and descriptions are summarized in Chapter 3.3.5.7.1 of the Multisale EIS 

and in Chapter 3.1.1.2.2.1 of the 2009-2012 Supplemental EIS. In water depths up to 400 m (1,312 ft), 

the scenarios assume that conventional, fixed platforms that are rigidly attached to the seafloor will be the 

type of structure preferred by operators. In water depths of <200 m (656 ft), 20 percent of the platforms 

are expected to be manned (defined as having sleeping quarters on the structure). In depths between 200 

and 400 m (656 and 1,312 ft), all structures are assumed to be manned. It is also assumed that helipads 

will be located on 66 percent of the structures in water depths <60 m (197 ft), on 94 percent of the 

structures in water depths between 60 and 200 m (656 ft), and on 100 percent of the structures in water 

depths >200 m (656 ft). At water depths >400 m (1,312 ft), platform designs based on rigid attachment to 

the seafloor are not expected to be used. The 400-m (1,312-ft) isobath appears to be the current economic 

limit for this type of structure. 

Deepwater Operations Plans 

A Deepwater Operations Plan (DWOP) is required for all deepwater development projects in water 

depths ≥1,000 ft (305 m) and for all projects proposing subsea production technology. A DWOP is 

designed to address industry and BOEMRE concerns by allowing an operator to know, well in advance of 

significant spending, that their proposed methods of dealing with situations not specifically addressed in 

the regulations are acceptable to BOEMRE. The DWOP provides BOEMRE with information specific to 

deepwater/subsea equipment issues to demonstrate that a deepwater project is being developed in an 

acceptable manner with regard to engineering specifics, safety, and the environment. The BOEMRE 

reviews deepwater development activities from a total system perspective, emphasizing the operational 

safety, environmental protection, and conservation of natural resources. A DWOP is required initially 

and is usually followed by a DOCD. 

Development Operations and Coordination Document 

The chief planning document that lays out an operator’s specific intentions for development is the 

DOCD. The range of postlease development plans is discussed in Chapter 1.5. Table 3-2 shows the 

estimated range of development wells and production structures by water depth subarea for the CPA 

proposed action. The BOEMRE estimates that 87-89 percent of development wells would become 

producing wells. 

CPA Proposed Action Scenario: The BOEMRE estimates that 338-576 development wells will be 

drilled as a result of the CPA proposed action. Table 3-2 shows the estimated range of development 

wells by water-depth range. Approximately 20-25 percent of the projected wells are expected to be on the 

continental shelf (0-200 m [656 ft] water depth) and 75-80 percent are expected in intermediate waterdepth ranges and deeper (>200 m; 656 ft). For oil development wells (149-263), the water-depth range of 

200-400 m (656-1,312 ft) has the largest portion of projected wells, about 25-26 percent. For gas 

development wells (144-237), the continental shelf (0-60 m [0-200 ft] water depth) has the largest portion 

of projected wells, about 23-28 percent. 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. The BOEMRE estimates that 23,181-26,243 development wells 

will be drilled in the CPA as a result of the OCS Program. Tables 4-4, 4-5, and 4-6 in the Multisale EIS 

show the estimated range of development wells by water-depth range. 
3-10 Central Planning Area Supplemental EIS

3.1.1.2.2. Infrastructure Presence 

Chapter 4.1.1.3.3 of the Multisale EIS and Chapter 3.1.1.2.2 of the 2009-2012 Supplemental EIS 

describe the impacting factors arising from the presence of OCS facilities in the GOM as a result of a 

proposed action. These impacting factors include (1) anchoring, (2) offshore production systems, (3) 

space-use requirements, (4) aesthetic quality, and (5) trash and debris. 

3.1.1.2.2.1. Anchoring 

Chapter 4.1.1.3.1.1 of the Multisale EIS discusses the impacting factors arising from anchoring in the 

GOM as a result of the proposed action. Most exploration drilling, platform, and pipeline emplacement 

operations on the OCS require anchors to hold the rig, topside structures, or support vessels in place. 

Anchors disturb the seafloor and sediments in the area where dropped or emplaced. Anchoring can cause 

physical compaction beneath the anchor and chains or lines, as well as resuspend sediment. A disturbed 

area on the sea bottom forms by the swing arc formed by anchor lines scraping across bottom within the 

range allowed by the anchoring system configuration. Dynamically positioned rigs, production 

structures, and vessels are held in position by four or more propeller jets and do not cause anchoring 

impacts. Conventional pipelaying barges use an array of eight 9,000-kg (19,842-lb) anchors to position 

the barge and to move it forward along the pipeline route. These anchors are continually moved as the 

pipelaying operation proceeds. The area actually affected by these anchors depends on water depth, wind, 

currents, chain length, and the size of the anchor and chain. Mooring buoys may be placed near drilling 

rigs or platforms so that service vessels need not anchor, or cannot anchor (in deeper water). These 

temporarily installed anchors will most likely be smaller and lighter than those used for vessel anchoring 

and, thus, will have less impact on the sea bottom. Moreover, installing one buoy will preclude the need 

for numerous individual vessel-anchoring occasions. Service vessel anchoring is assumed not to occur in 

water depths >150 m (492 ft) and only occasionally in shallower waters (vessels would always tie up to a 

platform or buoy in water depths >150 m [492 ft]). Barges are assumed to always tie up to a production 

system rather than anchor. Barges and other vessels are also used for both installing and removing 

structures. Barge vessels use anchors placed away from their location of work. 

3.1.1.2.2.2. Offshore Production Systems 

Chapters 3.3.5.7.1 and 4.1.1.3.3 of the Multisale EIS and Chapter 3.1.1.2.2.1 of the 2009-2012 

Supplemental EIS discuss the impacting factors arising from offshore production systems in the GOM as 

a result of a proposed action. Table 3-2 shows the estimated number of production structures by waterdepth range for the CPA proposed action. 

Spar 

A spar structure is a deep-draft, floating caisson that may consist of a large-diameter (27.4-36.6 m; 

90-120 ft) cylinder or a cylinder with a lower tubular steel trellis-type component (truss spar, a second 

generation design) that supports a conventional production deck. A third generation of spar design is the 

cell spar. The cell spar’s hull is composed of several identically sized cylinders surrounding a center 

cylinder. The cylinder or hull may be moored via a chain catenary or semi-taut line system connected to 

6-20 anchors on the seafloor. Spars are now used in water depths up to 900 m (2,952 ft) and may be used 

in water depths 3,000 m (9,842 ft) or deeper (NaturalGas.org, 2010a; USDOI, MMS, 2006b; Oynes, 

2006). 

Semisubmersibles 

Semisubmersible production structures (semisubmersibles) resemble their drilling rig counterparts 

and are the most common type of offshore drilling rig (NaturalGas.org, 2010a). Semisubmersibles are 

partially submerged with pontoons that provide buoyancy. Their hull contains pontoons below the 

waterline and vertical columns that connect to the hull box/deck. The structures keep on station with 

conventional, catenary or semi-taut, line mooring systems connected to anchors in the seabed. 

Semisubmersibles can be operated in a wide range of water depths. Floating production systems are 
Impact-Producing Factors and Scenario 3-11 

suited for deepwater production in depths up to 8,000 ft (2,438 m) (NaturalGas.org, 2010a; USDOI, 

MMS, 2006b; Oynes, 2006). 

Subsea Production Systems 

For some development programs, especially those in deep- and ultra-deepwater, an operator may 

choose to use a subsea production system instead of a floating production structure. Although the use of 

subsea systems has recently increased as development has moved into deeper water, subsea systems are 

not new to the GOM and they are not used exclusively for deepwater development. Unlike wells from 

conventional fixed structures, subsea wells do not have surface facilities directly supporting them during 

their production phases. A subsea production system has various bottom-founded components. Among 

them are well templates, well heads, “jumper” connections between well heads, flow control manifolds, 

in-field pipelines and their termination sleds, and umbilicals and their termination assemblies. A subsea 

production system can range from a single-well template connected to a nearby manifold or pipeline, and 

then to a riser system at a distant production facility; or a series of wells that are tied into the system. 

Subsea systems rely on a “host” facility for support and well control. Centralized or “host” production 

facilities in deep water or on the shelf may support several satellite subsea developments. A drilling rig 

must be brought on location to provide surface support to reenter a well for workovers and other types of 

well maintenance activities. In addition, should the production/safety system fail and a blowout result, 

surface support must be brought on location to regain control of the well. 

Floating Production, Storage, and Offloading Systems 

This Agency prepared an EIS on the potential use of floating production, storage, and offloading 

(FPSO) systems on the Gulf of Mexico OCS (USDOI, MMS, 2001a). In accordance with the scenario 

provided by industry, the FPSO EIS addresses the proposed use of FPSO’s in the deepwater areas of the 

CPA and WPA only. In January 2002, this Agency announced its decision to accept applications for 

FPSO’s after a rigorous environmental and safety review. On June 12, 2007, this Agency received a 

DOCD from Petrobras Americas Inc. proposing to use an FPSO in Walker Ridge to develop two different 

CPA prospects: Cascade and Chinook. This is the first and only proposal, at this time, to use an FPSO in 

the GOM. The Cascade Prospect (Walker Ridge Block 206 Unit) is located approximately 250 mi (402 

km) south of New Orleans, Louisiana, and about 150 mi (241 km) from the Louisiana coastline in 

approximately 8,200 ft (2,499 m) of water. The Chinook Prospect (Walker Ridge Block 425 Unit) is 

located about 16 mi (26 km) south of the Cascade Prospect. The FPSO was approved in 2011, but it has 

yet to be deployed. 

3.1.1.2.2.3. Space-Use Requirements 

Chapter 4.1.1.3.3.2 of the Multisale EIS and Chapter 3.1.1.2.2.2 of the 2009-2012 Supplemental EIS 

discuss impacting factors arising from space requirements in the GOM as a result of a CPA proposed 

action. Leasing on the OCS results in operations that temporarily occupy sea bottom and water surface 

area for dedicated uses. The OCS operations include the deployment of seismic vessels, bottom surveys, 

and the installation of surface or subsurface bottom-founded production structures with anchor cables and 

safety zones. While in use, these areas become unavailable to commercial fishermen or any other 

competing use. 

CPA Proposed Action Scenario: A maximum of 264 ha (660 ac) (44 production structures of 

approximately 6 ha [15 ac]) of surface area will be lost to commercial fishing and other uses as a result of 

the CPA proposed action. 

The net effect on total area available for commercial trawling and other uses will also be affected by 

structure removals. Structures removed in water depths <200 m (656 ft) in most cases would be taken to 

shore, resulting in trawl area being opened up. Approximately 10 percent of eligible structures removed 

are eventually used for rigs-to-reef. Those structures that may become artificial reef would open space 

where removed and take space where reefed. Even when platforms are transported to designated artificial 

reef planning areas, which already effectively prevent trawling, the net effect would again be additional 

trawling area. If platform removals are set against those installed, the effective net area taken for 
3-12 Central Planning Area Supplemental EIS

temporary OCS use because of additional platforms is two platforms added to the CPA representing a net 

area taken of 11.5 ha (28 ac). 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. Total number of production structure installations in the CPA has 

been estimated through the years 2007-2046 in Table 4-6 of the Multisale EIS. The total number of 

production structure installations projected for the OCS Program over this period is shown in Table 4-4 of 

the Multisale EIS for both the WPA and CPA as 2,958-3,262 for all depth ranges. The total number of 

structure removals through the years 2007-2046 in the WPA and CPA are 5,997-6,097. With nearly 

double the amount of platform removals as installations, there would be no net OSC Program area taken 

over the 40-year analysis period by additional platforms. Because of structure removals, the net effect 

over this time is that more OCS space would become available for other uses. Cleared areas would once 

again be available for commercial fishing or any other competing use in depth ranges where the activities 

are practiced. 

3.1.1.2.2.4. Aesthetic Quality 

Chapter 4.1.1.3.3.3 of the Multisale EIS and Chapter 3.1.1.2.2.3 of the 2009-2012 Supplemental EIS 

describe the impacting factors arising from aesthetic interference in the GOM as a result of a proposed 

action. The presence of drilling and production platforms visible from land, increased vessel and air 

traffic, and noise are aesthetic inferences associated with the proposed action and routine events. The 

aesthetics for industrialized infrastructure is a subjective judgment, but it is usually regarded as a negative 

aesthetic if facilities of this type are visible. Visibility of industrial structures on an open horizon that 

may be frequented by people precisely for the open horizon is a net negative aesthetic and a conflict in 

space use. The potential visibility of fixed structures in local GOM waters could be of concern to 

business operators, local chambers of commerce, and organizations promoting tourism. Installed 

facilities and increased vessel and air traffic add a component of additional noise as well as their physical 

presence on the seascape. 

The natural curvature of the Earth renders a 60-ft (18-m) tall ship invisible to a person at sea level 

when >12 mi (19 km) from shore. The formula for the distance to the horizon is given as your eye height 

above sea level, plus the height of the object under view, then square root of that sum, multiplied by 1.5 

(WikiHow, 2010). Rasmussen (2008) includes a calculator. A structure 250 ft (76 m) above sea level, 

such as an oil platform, would not be visible to 6-ft-tall beach goers if it is >24 mi (38 km) from shore. 

The CPA is 3 nmi (3 mi; 6 km) from Louisiana, Mississippi, and Alabama. In the CPA, there are already 

nearly 1,000 platforms within 10 mi (16 km) of the coast (34% of the structures are in water depths <60 m 

[197 ft]), and for people living or visiting there, the presence of infrastructure on a “working coast” has 

been accepted. 

CPA Proposed Action Scenario: Of the structures projected to be installed in water 0-60 m (0-197 ft) 

deep as a result of the CPA proposed action (Table 3-2), 20-25 would be located within 10 mi (16 km) of 

the coast and would be visible from the shore at sea level.

OCS Program Scenario: Of the structures projected to be installed in water 0-60 m (0-197 ft) deep as 

a result of the OCS Program in the CPA (Table 4-6 of the Multisale EIS), 612-645 would be located 

within 10 mi (16 km) of the coast and would be visible from the shore at sea level. 

3.1.1.2.2.5. Workovers and Abandonments 

Chapter 4.1.1.3.4 of the Multisale EIS and Chapter 3.1.1.2.2.4 of the 2009-2012 Supplemental EIS 

discuss the impacting factors arising from workovers and abandonments in the GOM as a result of a 

proposed action. Completed and producing wells may require periodic reentry that is designed to 

maintain or restore a desired product flow rate. These procedures are referred to as a well “workover.” 

Workover operations are also carried out to evaluate or reevaluate a geologic formation or reservoir 

(including recompletion to another formation) or to permanently abandon a part or all of a well. 

Workovers on subsea completions require that a rig be moved on location to provide surface support. 

Workovers can take from 1 day to several months to complete, depending on the complexity of the 

operations, with a median of about 7 days. Based on historical data, BOEMRE projects a producing well 

may expect to have seven workovers or other well activities during its lifetime. There are two types of 

well abandonment operations—temporary and permanent. The operator must meet specific requirements 
Impact-Producing Factors and Scenario 3-13 

to decommission and abandon a well under guidelines provided in the new NTL 2010-G05 (Chapter 

3.1.1.7). The projected number of workovers is a function of producing wells, including one permanent 

abandonment operation per well. 

CPA Proposed Action Scenario: As a result of the proposed action, there are 2,000-2,849 workovers 

and other well activities estimated to be completed within the CPA. 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. There are 190,778-218,555 workovers and other well activities in 

this class estimated to be completed within the OCS Program through the years 2007-2046. 

3.1.1.3. Major Sources of Oil Inputs in the Gulf of Mexico 

Petroleum hydrocarbons can enter the GOM from a wide variety of sources. The major sources of oil 

inputs in the GOM are natural seepage, produced waters, land-based discharges, and spills. These sources 

are discussed in detail in Chapter 4.1.3.4 of the Multisale EIS and in Chapter 3.1.1.3 of the 2009-2012 

Supplemental EIS. Numerical estimates of the contributions for these sources to the GOM coastal and 

offshore waters are shown in Tables 4-11 and 4-12 of the Multisale EIS, respectively. The information 

presented in the Multisale EIS is based on the National Research Council’s Oil in the Sea III: Inputs, 

Fates, and Effects (NRC, 2003) and is summarized below. 

The GOM comprises one of the world’s most prolific offshore oil-producing provinces as well as 

having heavily traveled tanker routes. Nevertheless, inputs of petroleum from onshore sources far 

outweigh the contribution from offshore activities. Human use of petroleum hydrocarbons is generally 

concentrated in major municipal and industrial areas situated along coasts or large rivers that empty into 

coastal waters. 

Natural Seepage 

Natural seeps provide the largest petroleum input to the offshore GOM, about 95 percent of the total. 

Mitchell et al. (1999) estimated a range of 280,000-700,000 bbl per year (40,000-100,000 tonnes per 

year), with an average of 490,000 bbl (70,000 tonnes) for the northern GOM, excluding the Bay of 

Campeche. Using this estimate and assuming seep scales are proportional to surface area, the NRC 

(2003) estimated annual seepage for the entire GOM at ~980,000 bbl (140,000 tonnes) per year, or about 

3 times the estimated amount of oil spilled by the 1989 Exxon Valdez event (~270,000 bbl) (Steyn, 2010) 

or a quarter of the amount released by the DWH event (4.9 million bbl of oil) (Lubchenco et al., 2010). 

As seepage is a natural occurrence, the rate of ~980,000 bbl (140,000 tonnes) per year is expected to 

remain unchanged throughout the 40-year cumulative analysis period. 

Produced Water 

During OCS operations, small amounts of oil are routinely discharged in produced water, which is 

treated and discharged overboard according to USEPA regulations. Based on the volume of produced 

water generated, an average of about 17,500 bbl of oil is discharged in the Gulf of Mexico OCS each year 

(Etkin, 2009). 

Land-based Discharges 

Land-based sources provide the largest petroleum input to the coastal waters of the GOM. Landbased sources include residual petroleum hydrocarbons in municipal and industrial wastewater treatment 

facility discharges as well as urban runoff. The Mississippi River carries the majority of petroleum 

hydrocarbons into GOM waters from land-based drainage that occurs far upriver. With increased 

urbanization, particularly in coastal areas, the amount of impervious paved surface increases, and oil 

contaminants deposited on these roads and parking lot surfaces are washed into adjacent streams and 

waterbodies. 
3-14 Central Planning Area Supplemental EIS

Spills 

Oil spills occur during the production, transportation, and consumption of oil. The composition of 

spilled hydrocarbons includes crude oil, refined fuels such as diesel during transport and storage and spills 

during consumption. Chapter 4.1.3.4.4 of the Multisale EIS and Chapter 3.1.1.3 of the 2009-2012 

Supplemental EIS, which discuss offshore and coastal spills and spills related to and not related to OCS 

activity, are summarized below. Chapter 3.2.1 of this Supplemental EIS discusses potential spills 

associated with the proposed action, specifically. Appendix D discusses the Deepwater Horizon event. 

At the national level, tankers and tank barges were responsible for 45 percent of the total spillage in 

the years 1969 through 2008 (U.S. Dept. of Homeland Security, CG, 2010a). The type of oil spilled 

nationally was as follows: 46 percent crude oil; 17 percent heavy fuel oil; 16 percent intermediate fuel 

oil; and 9 percent gasoline. Other petroleum and non-petroleum oils make up the remaining 11 percent 

(U.S. Dept. of Homeland Security, CG, 2010a). In the GOM, spills will vary according to activities 

conducted in the area. Spills from pipelines are the largest spill source of oil to the coastal waters of the 

western GOM. Spills from tankers are the largest spill source to coastal waters of the eastern GOM. 

Spills could happen because of an accident associated with future OCS operations. Table 4-13 of the 

Multisale EIS provides the estimated number of all spill events (OCS and non-OCS) that BOEMRE 

projects will occur within coastal and offshore waters of the GOM area for a representative future year 

(around 15 years after the proposed action). Table 4-13 of the Multisale EIS distinguishes spill 

occurrence risk by likely operation or source and the estimated size of spills and shows the estimated 

number of annual OCS spills rather than for the 40-year program. 

Spills as the Result of Hurricanes 

Chapter 4.1.3.4.4.2 of the Multisale EIS and Chapter 3.1.1.3 of the 2009-2012 Supplemental EIS 

discuss the cause and volume of spills that resulted from the 2002-2005 hurricanes. When spills related to 

hurricane damage are first reported, the amount of spilled crude oil and fuel products are estimated. Once 

safety issues are resolved and a more accurate accounting of lost material is made, the volumes often are 

corrected downwards. Therefore, this Agency updates and publishes these estimates in the years 

following the hurricanes. This Supplemental EIS revises the Multisale EIS and the 2009-2012 

Supplemental EIS estimates. The most recent revision of petroleum spills from Federal OCS facilities 

caused by major hurricanes in 2002-2008 is available (USDOI, MMS, 2009a). 

Table 3-4 indicates that spills caused by hurricane-damaged pipelines result in the vast majority of 

total oil spilled in the GOM. The BOEMRE reports production and spills in barrels; 1 bbl equals 42 U.S. 

gallons (gal). The USCG reports spills in gallons and classifies spills as minor, medium, or major. The 

table below presents the USCG volumes associated with spill size categories. The USCG’s offshore spill 

size classifications are based solely on spill size, not impacts. 

Spill Size Volume of Oil Spilled 

Minor <238 bbl (<10,000 gal) 

Medium 238-2,380 bbl (10,000-99,999 gal) 

Major ≥2,381 bbl (≥100,000 gal) 

 There were 231 spills totaling about 25,600 bbl identified as having occurred during 

or soon after the storms: 8 (totaling 1,631 bbl) from Hurricane Lili; 36 (totaling 

4,645 bbl) from Hurricane Ivan; 73 (totaling 4,729 bbl) from Hurricane Katrina; 56 

(totaling 8,734 bbl) from Hurricane Rita; and 58 (totaling 5,857 bbl) from Hurricanes 

Gustav and Ike. 

 There were no major spills caused by any of the 2002-2008 hurricanes. The USCG 

defines a major offshore spill as a spill 100,000 gal (2,381 bbl) (based solely on 

size, not impacts). 

 Of the 231 spills, 206 (89%) were minor, <238 bbl in size. These minor spills totaled 

<7,600 bbl, or about 30 percent of the spillage. 
Impact-Producing Factors and Scenario 3-15 

 There were a total of 25 medium spills, 238-2,380 bbl in size, totaling about 18,000 

bbl (70% of the spillage): 3 from Hurricane Lili; 6 from Hurricane Ivan; 5 from 

Hurricane Katrina; 6 from Hurricane Rita; and 5 from Hurricanes Gustav and Ike. 

Only five of these medium spills were 1,000 bbl: 1 from Hurricane Ivan (1,720 

bbl); 3 from Hurricane Rita (2,000 bbl, 1,572 bbl, and 1,494 bbl); and 1 from 

Hurricanes Gustav and Ike (1,316 bbl). 

 Platforms and rigs were the source of 111 (48%) of the spills, totaling 16,838 bbl 

(66% of the spillage). 

 Pipelines were the source of 120 (52%) of the spills identified, totaling 8,758 bbl 

(34% of the spillage). 

 There were 80 spills of 50 bbl. 

There were no accounts of environmental consequences resulting from spills from OCS facilities that 

occurred during these major hurricanes from 2002 through 2008. Impacts included the following 

(USDOI, MMS, 2009a): 

 no spill contacts to the shoreline; 

 no oiling of marine mammals, birds, or other wildlife; 

 no large volumes of oil on the ocean surface to be collected or cleaned up; and 

 no identified environmental impacts from any OCS spills from these hurricanes. 

Offshore Spills 

The OCS-related offshore spills and non-OCS-related offshore spills are addressed in Chapters 

4.1.3.4.4.4 and 4.1.3.4.4.5 of the Multisale EIS, respectively, and in Chapter 3.1.1.3 of the 2009-2012 

Supplemental EIS. One OCS-related offshore spill of 1,000 bbl per year because of a pipeline release is 

anticipated. Besides spills occurring from facilities and during pipeline transport offshore spills could 

occur because of future FPSO operation or from shuttle tankers transporting OCS crude oil into ports. 

Table 4-13 of the Multisale EIS includes the likelihood of a spill from a shuttle-tanker accident carrying 

OCS-produced crude oil. The scenario with the highest risk of spill occurrence is the high-case resource 

estimate for the OCS Program in the CPA, which assumes some shuttle-tanker transport of OCSproduced oil. Under that scenario, there is a 63 percent chance that a spill 1,000 bbl and a 29 percent 

chance that a spill 10,000 bbl would occur from an OCS-related shuttle tanker during the 40-year 

cumulative analysis period. Offshore spill sizes were estimated based on historical records for a 

representative future year (Anderson and LaBelle, 2000). 

Offshore OCS Program spills <1,000 bbl were estimated based on historical records collected from 

1985 to 2001, and about 450-500 spills <1,000 bbl occurred from OCS offshore sources yearly. Less 

documentation is available for spills <1,000 bbl because they are more routine, they do not persist on the 

water as long, and they are likely to pose less of an environmental threat than larger spills. Additionally, 

many of the reported spills are of an unknown origin. 

Non-OCS-related offshore spills 1,000 will occur from the extensive maritime barging and tankering 

operations that occur in offshore waters of the GOM. The analysis of spills from tankers and barges 

1,000 bbl is based on data obtained from USCG and analyzed by BOEMRE. Less than one spill 1,000 

bbl is projected to occur in the offshore GOM for a typical future year from the extensive tanker and 

barge operations (Table 4-13 of the Multisale EIS). 

Coastal Spills 

Table 4-13 of the Multisale EIS provides BOEMRE’s projections of the number of spills that are 

projected to occur in the coastal waters of the GOM (State offshore and inland coastal waters) in a typical 

future year as a result of operations that support the OCS Program. 
3-16 Central Planning Area Supplemental EIS

The OCS-related coastal spills are addressed in Chapter 4.1.3.4.4.6 of the Multisale EIS and in 

Chapter 3.1.1.3 of the 2009-2012 Supplemental EIS. The OCS-related coastal spills primarily occur from 

pipeline ruptures. An OCS-related spill in coastal waters of 1,000 bbl and related to the proposed 

activity will occur less than once per year—about once every 6 years. An OCS-related spill 1,000 bbl 

would likely be from a pipeline accident for OCS coastal spills 1,000 bbl, where a spill size of 4,200 bbl 

is assumed. Smaller spills occur more regularly. Roughly 40-50 spills per year of <1,000 bbl related to 

the proposed activity on the OCS are estimated to occur in coastal waters. It is assumed that the spill risk 

would be widely distributed in the coastal zone, but it would primarily be within the Houston/Galveston 

area of Texas and the deltaic area of Louisiana due to the high proportion of oil being piped into these 

areas. Based on a BOEMRE analysis of USCG data on all U.S. coastal spills by volume, 42 percent of 

the spills will occur in State offshore waters, 1.5 percent will occur in Federal offshore waters, and 57 

percent will occur in inland waters. It is assumed all coastal spills will contact land and proximate 

resources. For OCS-related coastal spills <1,000 bbl, a spill size of 5 bbl is assumed. 

Non-OCS-related coastal spills are addressed in Chapter 4.1.3.4.4.7 of the Multisale EIS and in 

Chapter 3.1.1.3 of the 2009-2012 Supplemental EIS. Non-OCS-related coastal spills primarily occur 

from vessel accidents. Other sources include spills during the pipeline transport of petroleum products; 

crude oil; State oil and gas facilities; petrochemical refinery accidents; and storage tanks at terminals. A 

non-OCS-related coastal spill 1,000 bbl occurred roughly once every 2 years in the 1985-2001 USCG 

records. This is a very rough estimate because of the infrequent occurrence of a spill of this size in 

coastal waters. Non-OCS-related coastal spills <1,000 bbl occurred annually at a rate of 400-600 per year 

in the 1996-2001 USCG data. Many of the reported spills are from an unknown source. Based on a 

BOEMRE analysis of U.S. spill data maintained by USCG (U.S. Dept. of Homeland Security, CG, 

2010a), the historical percentages of coastal spill occurrences in different waterbody types were 

calculated to be as follows: 47 percent have occurred in rivers and canals; 19 percent in bays and sounds; 

and 34 percent in harbors. 

3.1.1.4. Offshore Transport 

Chapter 4.1.1.8 of the Multisale EIS and Chapter 3.1.1.4 of the 2009-2012 Supplemental EIS describe 

the impact-producing factors arising from the transportation of products, supplies, and personnel in the 

GOM for a proposed action. The discussion in this Supplemental EIS tiers from the discussions in the 

Multisale EIS and the 2009-2012 Supplemental EIS. 

3.1.1.4.1. Pipelines 

Chapter 4.1.1.8.1 of the Multisale EIS and Chapter 3.1.1.4.1 of the 2009-2012 Supplemental EIS 

describe the existing pipeline network in the GOM, installation trends, installation methods, pipeline 

burial, and issues related to deep water. A mature pipeline network exists in the GOM to transport oil and 

gas production from the OCS to shore. There are currently 106 OCS-related pipeline landfalls (pipelines 

that have at one time or another carried hydrocarbon product from the OCS) in the Louisiana Coastal 

Area (LCA) (USDOI, MMS, 2007b, Table 3-38). Included in this figure is a subset of 47 pipeline 

systems under DOT jurisdiction originating in Federal waters and terminating onshore or in Louisiana 

State waters (Gobert, 2010) (Figure 3-2). The BOEMRE and DOT share responsibility for pipeline 

regulation on the OCS in the transition between Federal and State waters. The BOEMRE has jurisdiction 

over producer-operated pipelines that extend upstream from the wellbore to the point downstream (the 

last valve on production infrastructure) on the OCS at which responsibility transfers from a producing 

operator to a transporting operator. The DOT’s jurisdiction lies with transporter-operated pipelines that 

tend to be larger diameter trunk lines that service multiple facilities or pipeline tie-ins from offshore. 

The OCS-related pipelines nearshore and onshore may merge with pipelines carrying materials 

produced in State lands for transport to processing facilities or to connections with pipelines located 

farther inland (Figure 3-2). At present, all gas production and >99 percent of oil production from the 

offshore GOM is transported to shore by pipeline. 

The BOEMRE’s minimum cathodic protection design criteria for pipeline external corrosion 

protection is 20 years. For the most part, pipelines have a designed life span greater than 20 years and, if 

needed, can be retrofitted to increase the life span. As for internal corrosion mitigation, operators are 
Impact-Producing Factors and Scenario 3-17 

required to monitor products transported through the pipelines for corrosiveness. Based on the type of 

production, a company then enhances the pipeline internal corrosion protection by injecting appropriate 

corrosion inhibitors and monitoring effectiveness to prevent pipeline failures, thus extending the life of a 

pipeline. It should be noted that different products have different corrosive characteristics. Should a 

pipeline need to be replaced because of integrity issues, a replacement pipeline is installed or alternate 

routes are used to transport the products, or a combination of the two. Besides replacement because of 

integrity issues, a pipeline may also be required to be replaced as a result of storm or other damages. The 

BOEMRE estimates that the overall pipeline replacement over the past few years is about 1 percent of the 

total installed. Natural gas transportation by means other than pipelines, for example as LNG, is possible, 

but is not part of the proposed action or the OCS Program scenario. 

Newer installation methods have allowed the pipeline infrastructure to extend farther into deep water. 

At present, the deepest pipeline in the Gulf is in water 2,700 m (8,858 ft) deep. More than 500 pipelines 

reach water depths of 400 m (1,312 ft) or more, and over 400 of those pipelines reach water depths of 800 

m (2,625 ft) or more. These technical challenges are described in more detail in Deepwater Gulf of 

Mexico 2006: America’s Expanding Frontier (USDOI, MMS, 2006b). 

Pipeline Landfalls 

Up to one (i.e., 0-1) new pipeline landfall is projected per OCS lease sale (USDOI, MMS, 2007d, 

p. 1). The BOEMRE anticipates that pipelines from most of the new offshore production facilities will tie 

in to the existing pipeline infrastructure offshore or in State waters, which will result in few new pipeline 

landfalls. Production from the CPA proposed action will contribute to the capacity of existing and future 

pipelines and pipeline landfalls. According to BOEMRE regulations (30 CFR 250.1003(a)(1)), pipelines 

with diameters ≥85⁄8 inches (in) (22 centimeters [cm]) that are installed in water depths <60 m (200 ft) are 

to be buried to a depth of at least 3 ft (1 m) below mudline. The regulations also provide for the burial of 

any pipeline, regardless of size, if BOEMRE determines that the pipeline may constitute a hazard to other 

uses of the OCS in the GOM. The BOEMRE has determined that all pipelines installed in water depths 

<60 m (200 ft) must be buried. The purposes of these requirements are to (1) reduce the movement of 

pipelines during high sea states by storm currents and waves, (2) protect the pipeline from the external 

damage that could result from anchors and fishing gear, (3) reduce the risk of fishing gear becoming 

snagged, and (4) minimize interference with the operations of other users of the OCS. Where pipeline 

burial is necessary, a jetting sled would be used. Jetting disperses sediments over the otherwise 

undisturbed water bottom that flanks the jetted trench. The area covered by settled sediment and the 

thickness of the settled sediment depends upon variations in sea bottom grain size, bottom topography, 

sediment density, and currents. Sediment displacement due to pipeline burial is further explained in 

Chapter 4.1.1.3.2.2 of the Multisale EIS. 

CPA Proposed Action Scenario: The BOEMRE projects 130-1,700 km (81-1,056 mi) of new 

pipelines as a result of the CPA proposed action (Table 3-2). For the CPA proposed action, about half of 

the new pipeline length would be in water depths <60 m (197 ft), requiring burial. For the CPA proposed 

action, 0-1 new pipeline landfalls are projected. The length of new pipelines was estimated using the 

amount of production, the number of structures projected as a result of the proposed action, and the 

location of the existing pipelines. The range in length of pipelines projected is because of the uncertainty 

of the location of new structures, which existing or proposed pipelines would be used, and where they tie 

in to existing lines. Many factors would affect the actual transport system, including company 

affiliations, amount of production, product type, and system capacity. 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. Table 4-4 of the Multisale EIS projected that 9,470-66,550 km 

(5,884-41,352 mi) of new pipelines in support of the OCS Program during the years 2007-2046 would be 

built. 

3.1.1.4.2. Barges 

Chapters 3.3.5.8.9 and 4.1.1.8.2 of the Multisale EIS and Chapter 3.1.1.4.2 of the 2009-2012 

Supplemental EIS describe the use of barges and oil barging. Barges may be used offshore to transport 

oil and gas, supplies such as chemicals or drilling mud, or wastes between shore bases and offshore 
3-18 Central Planning Area Supplemental EIS

platforms in shallow waters (<60 m; <200 ft) of the GOM. A small amount (<1%) of oil production is 

barged in shallow water (<60 m; <200 ft). 

CPA Proposed Action Scenario: The BOEMRE projects that barging will continue to account for 

≤1 percent of the oil transported for the CPA proposed action. 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS; that the current rate of barging would continue during the years 

2007-2046 at about that same level as today or slightly less as production on the GOM tapers off in the 

second half of the 40-year production period. 

3.1.1.4.3. Oil Tankers 

Chapter 4.1.1.8.3 of the Multisale EIS and Chapter 3.1.1.4.3 of the 2009-2012 Supplemental EIS 

discuss the use of FPSO’s and shuttle tankers for the transportation of OCS oil. 

Shuttle tanker transport of Gulf of Mexico OCS-produced oil in a purpose-built FPSO system has not 

yet occurred; however, Petrobras had planned the Cascade-Chinook fields’ first production from an FPSO 

and shuttle tanker system in mid-2010; however, delays following the DWH event has made scheduling 

difficult to predict. An FPSO was approved in 2011 but has yet to be deployed. Tankering is projected 

for some future OCS operations located in deep water beyond the existing pipeline network. The FPSO’s 

store crude oil in tanks in the hull of the vessel and periodically offload the crude to shuttle tankers or 

oceangoing barges for transport to shore. The FPSO’s may be used to develop marginal oil fields or used 

in areas remote from the existing OCS pipeline infrastructure, especially development in the Lower 

Eocene Wilcox trend (Walker Ridge leasing area) that is far from most existing pipeline networks. As a 

result of the CPA proposed action, the use of FPSO’s and shuttle tankering are only projected in water 

depths >800 m (2,625 ft). Shuttle tankers would be used to transport crude oil from FPSO production 

systems to Gulf Coast refinery ports or to offshore deepwater ports such as the Louisiana Offshore Oil 

Port. 

Safety features, such as marine break-away offloading hoses and emergency shut-off valves, would 

minimize the potential for, and size of, an oil spill. In addition, weather and sea-state limitations would 

be established to further ensure that hook-up and disconnect operations will not lead to accidental oil 

release. A vapor recovery system between the FPSO and shuttle tanker will be employed to minimize the 

release of fugitive emissions from cargo tanks during offloading operations. The FPSO systems are 

suitable for the light and intermediate oils of the GOM, as well as heavier oil, such as the heavy oil Brazil 

plans to produce offshore in deep water. The number of shuttle-tanker trips to port in a given year is 

primarily a function of the FPSO production rate and the capacity of supporting shuttle tankers. 

CPA Proposed Action Scenario: There is one FPSO system ready to operate in the deepwater Gulf. 

The BOEMRE projects 0-1 FPSO systems could result from the CPA proposed action. For an FPSO 

operating at a peak production of 150,000 bbl/day, offloading would occur once every 3.3 days by a 

shuttle tanker with a 500,000-bbl cargo capacity transporting an upper-bound estimate of 54.75 MMbbl 

with 110 offloading events and shuttle tanker transits to offshore ports annually per FPSO system. 

OCS Program Scenario: The OCS Program scenario did not offer a projection for shuttle tanker 

transport in the Multisale EIS because no FPSO system was then proposed in the GOM. As industry 

continues to explore the Eocene Wilcox trend, industry’s interest level in the potential for the trend 

remains high, but flow assurance in these reservoirs remains a concern. 

3.1.1.4.4. Service Vessels 

Chapter 4.1.1.8.4 of the Multisale EIS and Chapter 3.1.1.4.4 of the 2009-2012 Supplemental EIS 

discuss the use of service vessels for transportation. Service vessels are one of the primary modes of 

transporting personnel between service bases and offshore platforms, drilling rigs, derrick barges, and 

pipeline construction barges. In addition to offshore personnel, service vessels carry cargo (i.e., 

freshwater, fuel, cement, barite, liquid drilling fluids, tubulars, equipment, and food) offshore. A trip is 

considered the transportation from a service base to an offshore site and back, in other words a round trip. 

Based on BOEMRE calculations, each vessel makes an average of eight round trips per week for 42 days 

in support of drilling an exploration well and six round trips per week for 45 days in support of drilling a 

development well. A platform in shallow water (<400 m; 1,312 ft) is estimated to require one vessel trip 

every 10 days over its 25-year production life. A platform in deep water (>400 m; 1,312 ft) is estimated 
Impact-Producing Factors and Scenario 3-19 

to require one vessel trip every 1.75 days over its 25-year production life. All trips are assumed to 

originate from the designated service base. 

CPA Proposed Action Scenario: The CPA proposed action is estimated to generate 137,000-220,000 

service-vessel trips over the 40-year period (Table 3-2) or 3,250-5,500 trips annually. Table 3-36 of the 

Multisale EIS indicates over 1.52 million service-vessel trips occurred on Federal navigation channels, 

ports, and OCS-related waterways in 2004. The number of service-vessel trips projected annually for the 

CPA proposed action would represent <1 percent of the total annual traffic on these OCS-related 

waterways. 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. The projected number of service-vessel trips for the OCS 

Program is 6.71-8.6 million trips during the years 2007-2046 (Table 4-4 of the Multisale EIS). 

3.1.1.4.5. Helicopters 

Chapters 3.3.5.7.2.4 and 4.1.1.8.5 of the Multisale EIS and Chapter 3.1.1.4.5 of the 2009-2012 

Supplemental EIS discuss the use of helicopters for the transportation of OCS crews and materials in 

support of OCS activities. The proposed action and OCS Program scenarios below use the current level 

of activity as a basis for projecting future helicopter operations. Helicopters are one of the primary modes 

of transporting personnel between service bases and offshore platforms, drilling rigs, derrick barges, and 

pipeline construction barges. Helicopters are routinely used for normal crew changes and at other times 

to transport management and special service personnel to offshore exploration and production sites. In 

addition, equipment and supplies are sometimes transported by helicopter. The Federal Aviation 

Administration (FAA) regulates helicopter flight patterns. Because of noise concerns, FAA Circular 91-

36C encourages pilots to maintain higher than minimum altitudes near noise sensitive areas. Corporate 

policy (for all helicopter companies) states that helicopters should maintain a minimum altitude of 700 ft 

(213 m) while in transit offshore and 500 ft (152 m) while working between platforms and drilling rigs. 

When flying over land, the specified minimum altitude is 1,000 ft (305 m) over unpopulated areas and 

coastlines, and 2,000 ft (610 m) over populated areas and sensitive areas including national parks, 

recreational seashores, and wildlife refuges. In addition, guidelines and regulations issued by NMFS 

under the authority of the MMPA include provisions specifying helicopter pilots to maintain an altitude of 

1,000 ft (305 m) within 100 yd (91 m) of marine mammals. According to the Helicopter Safety Advisory 

Conference (2009), from 1996 to 2009, helicopter operations (take offs and landings) in support of 

Gulfwide OCS operations have averaged, annually, about 1.4 million operations, over 3.0 million 

passengers, and 430,000 flight hours. There has been a decline in helicopter operations from 1,668,401 in 

1996 to 1,397,508 in 2009 (Helicopter Safety Advisory Conference, 2009). 

CPA Proposed Action Scenario: There are 1,000,000-2,200,000 helicopter trips projected over the 

40-year period for the CPA proposed action (Table 3-2), or 25,100-55,025 trips annually.

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. Table 4-4 of the Multisale EIS projects 38-60 million helicopter 

trips for the OCS Program for the years 2007-2046. 

3.1.1.5. Operational Wastes and Discharges 

Chapter 4.1.1.4 of the Multisale EIS describes the impacting factors arising from operational wastes 

and discharges in the GOM resulting from a proposed action. The discussion in this Supplemental EIS 

tiers from the discussion in the Multisale EIS. Because these wastes and discharges are USEPApermitted routine wastes types and volumes, they are also discussed under water quality as an impact of 

routine events (Chapter 4.1.2.2.2). Aside from the reissuance of expiring general NPDES permits by 

USEPA, there has been very little change in the topic of wastes and discharges. Volumes or wastes and 

discharges are dependant upon the level of activity, and hence, operations in the GOM. 

The USEPA, through general permits issued by the Region that has jurisdictional oversight, regulates 

all waste streams generated from offshore oil and gas activities. Each USEPA Region has promulgated 

general permits for discharges that incorporate the 1993 and 2001 effluent limitations guidelines as a 

minimum. Figure 3-3 shows the areas of the GOM where BOEMRE and USEPA have jurisdiction for 

air emissions. Within USEPA Region 6, BOEMRE has air emission jurisdiction on the OCS west of 

87.5o W. longitude. The current Region 6 general permit (GMG290000) was issued on June 7, 2007, and 
3-20 Central Planning Area Supplemental EIS

expires September 30, 2012 (USEPA, 2007a). In accordance with BOEMRE’s air quality regulations, 

BOEMRE applies defined criteria to determine which OCS plans require an air quality review and 

performs an impact analysis on the selected plans to determine whether the emission source would 

potentially cause a significant onshore impact. 

Drilling Muds and Cuttings 

Drilling mud and cuttings are described in Chapter 4.1.1.4.1 of the Multisale EIS. Drilling fluid is 

used during the drilling of exploration and development wells. These fluids are very dense and are 

circulated down the wellbore to pick up and remove drill bit cuttings, after which the mixture of entrained 

cuttings and fluid is referred to as drilling mud. 

The composition of drilling fluids is complex. Drilling fluids used on the OCS are divided into two 

categories: water based and nonaqueous based, in which the continuous phase is not soluble in water. 

Clays, barite, and other chemicals are added to the base fluid, which can be freshwater or saltwater in 

water-based fluids (WBF’s), mineral or diesel oil-based fluids (OBF’s), or synthetic-based fluids (SBF’s). 

Additional chemicals may be added to improve the performance of the drilling fluid (Boehm et al., 2001). 

Drilling mud is reconditioned and recirculated at the surface. The OBF’s are rarely used in GOM 

operations, while SBF’s may be preferred for certain deepwater prospects. If used, OBF’s and SBF’s 

must be recovered and taken to shore for recycling. Only water-based drill mud meeting USEPA’s 

NPDES permit requirements may be discharged to the sea. Barite is a major mineral component of all 

drilling fluid types. Barite is used to “heavy up” drilling mud because of the high specific gravity of 

barite. Adding barite makes drilling mud denser and heavier. Many other products are added to improve 

and condition the drilling fluid. Drilling mud that is discharged must meet USEPA’s NPDES permit 

requirements that include limits on trace metal concentrations, free oil, and toxicity. The USEPA 

regulates the NPDES permit program in the WPA. 

Cuttings are the chipped and fragmented rock that is broken and removed by the rotating drilling bit 

and brought to the surface entrained in drilling fluid. Cuttings may be discharged if they meet the 

USEPA’s NPDES permit requirements that include limits on adhered synthetic mud, if used, as well as 

limits on trace metals, toxicity, polycyclic aromatic hydrocarbons, and free oil. 

Produced Waters 

Produced waters are described in Chapter 4.1.1.4.2 of the Multisale EIS. Produced water is water that 

originates from or passes through the hydrocarbon-bearing geological strata and is brought to the surface 

with oil and gas during production. This waste stream can include formation water; injection water; well 

treatment, completion, and workover compounds added downhole; and compounds used during the oil 

and water separation process. Formation water, also called connate water or fossil water, originates in the 

permeable sedimentary rock strata and is brought up to the surface commingled with the oil and gas. 

Injection water is water that was injected to enhance oil production and in secondary oil recovery. 

Produced water is the largest volume byproduct associated with oil and gas exploration and 

production (Clark and Veil, 2009). The vast majority of OCS produced water is treated to remove oil and 

grease to a concentration below 29 milligrams/liter (mg/L) monthly average and discharged. In the OCS 

waters off the State of Texas, less produced water is generated because these wells tend to be gas. The oil 

wells in the OCS waters off the State of Louisiana generated greater volumes of produced water. Clark 

and Veil (2009) have determined the ratio of produced water to oil and gas on the OCS to be 1.04 bbl 

produced water to 1 bbl oil, and 86.0 bbl produced water to 1 million cubic feet (MMcf) of gas, 

respectively. The USEPA general permits allow the discharge of produced water on the OCS provided 

they meet discharge criteria. 

Well-Treatment, Workover, and Completion Fluids 

Well-treatment, workover, and completion fluids are described in Chapter 4.1.1.4.3 of the Multisale 

EIS. Completion fluids are used to displace the drilling fluid and protect formation permeability. 

Workover fluids are used to maintain or improve existing well conditions and production rates on wells 

that have been in production. These fluids include mixtures of seawater with various salts, such as 
Impact-Producing Factors and Scenario 3-21 

calcium chloride and calcium bromide, and may include defoamers and corrosion inhibitors or acids to 

increase formation permeability. 

Production treatment fluids are chemicals applied during the oil and gas extraction process. 

Production chemicals are used to dehydrate produced oil or treat the associated produced water for reuse 

or disposal. Both USEPA Regions 4 and 6 allow the discharge of well-treatment, completion, and 

workover fluids that meet the specified guidelines. Production chemicals consist of corrosion and scale 

inhibitors, bactericides, paraffin solvents, demulsifiers, foamers, defoamers, and water treatment 

chemicals. 

The USEPA Regions 4 and 6 allow the discharge of well-treatment, completion, and workover fluids 

that meet the specified guidelines; although if recoverable in concentration, they may be collected and 

recycled at an onshore facility. 

Production Solids and Equipment 

Production solids are described in Chapter 4.1.1.4.5 of the Multisale EIS. Produced sands are 

entrained particles that surface after hydraulic fracturing, and sand disassociated from the formation, 

along with other particles including pipe scale that are produced. Production solids may not be 

discharged overboard and are collected on the production platform, stored, and ultimately transported to 

shore for disposal. The solids are disposed of as nonhazardous oil-field waste according to individual 

State regulations. 

Deck Drainage 

Deck drainage is described in Chapter 4.1.1.4.5 of the Multisale EIS. Deck drainage includes all 

wastewater resulting from platform washings, deck washings, rainwater, and runoff from curbs, gutters, 

and drains, including drip pans and work areas, that is collected in separators that can remove oils and 

greases before overboard discharge. The USEPA’s general guidelines for deck drainage require that no 

free oil be discharged, as determined by visual sheen. 

Domestic and Sanitary Wastes 

Domestic and sanitary wastes are described in Chapter 4.1.1.4.6 of the Multisale EIS. As with the 

waste streams discussed above, domestic and sanitary wastes may be discharged when they are treated to 

meet USEPA-regulated parameters. Most service and crew vessels use a marine sanitation device Type 

III that stores sanitary wastes in tanks aboard ship until transferred to treatment facilities onshore at the 

service base. 

Vessel Operational Wastes 

Vessel operational wastes are described in Chapter 4.1.1.4.8 of the Multisale EIS. Vessel regulations 

come under the jurisdiction of USCG. The USCG and USEPA have cooperatively set regulatory limits 

for wastes, such as sanitary waste, which both agencies regulate, depending upon vessel type and 

location. Regulated wastes include bilge and ballast waters, trash and debris, and sanitary and domestic 

wastes.

Trash and Debris 

Trash and debris are described in Chapter 4.1.1.5 of the Multisale EIS. The OCS oil and gas 

operations generate trash and debris materials made of paper, plastic, wood, glass, and metal. Most of 

this trash is associated with galley and offshore food service operations and with operational supplies 

such as shipping pallets, containers used for drilling muds and chemical additives (sacks, drums, and 

buckets), and protective coverings used on mud sacks and drilling pipes (shrink wrap and pipe-thread 

protectors). Trash is collected and stored on the lower deck near the loading dock in large receptacles 

resembling dumpsters. These large containers are generally covered with netting to avoid loss and are 

returned to shore by service vessels for disposal in landfills. Drilling operations require the most 
3-22 Central Planning Area Supplemental EIS

supplies, equipment, and personnel; therefore, drilling operations generate more solid trash than 

production operations. 

Noise 

Noise is described in Chapter 4.1.1.7 of the Multisale EIS. Coastal noise associated with OCS oil and 

gas development results from helicopter and service-vessel traffic. Sound generated from these activities 

can be transmitted through both air and water, and may be continuous or transient. Service vessels 

transmit noise through both air and water. The primary sources of vessel noise are propeller cavitation, 

propeller singing, and propulsion; other sources include auxiliaries, flow noise from water dragging along 

the hull, and bubbles breaking in the wake (Richardson et al., 1995). Propeller cavitation is usually the 

dominant noise source. The intensity of noise from service vessels is roughly related to ship size and 

speed. Large ships tend to be noisier than small ones, and ships underway with a full load (or towing or 

pushing a load) produce more noise than unladen vessels. Noise increases with ship speed; ship speeds 

are often reduced in restricted coastal waters and navigation channels. 

Air Emissions 

Air emissions are described in Chapter 4.1.1.6 of the Multisale EIS. In 1990, pursuant to Section 328 

of the Clean Air Act Amendments and following consultation with the Commandant of the U.S. Coast 

Guard and the Secretary of the Interior, USEPA assumed air quality responsibility for the OCS waters 

east of 87.5o W. longitude and this Agency retained National Ambient Air Quality Standards (NAAQS) 

air quality jurisdiction for OCS operations west of 87.5o W longitude in the GOM. 

Air pollutants are emitted from the OCS emission sources that include any equipment that combusts a 

fuel, transports and/or transfers hydrocarbons, or results in accidental releases of petroleum hydrocarbons 

or chemicals, causing air emissions of pollutants. Some of these pollutants are precursors to ozone, which 

is formed by complex photochemical reactions in the atmosphere. Air pollutants are generated during 

exploration and production activities when fuels are combusted to run drilling equipment, power 

generators, and run engines. During production, fugitive emissions, including volatile organic 

compounds, escape from valves and flanges. Criteria air pollutants are also generated along routes from 

shore bases to OCS leases by vessels transporting supplies and workers. 

The air pollutants are also released during both venting and flaring. A combustion flare or cold vent 

is a specially designed boom or stack used to dispose of hydrocarbon vapors or natural gas. Unlike cold 

vents, the hydrocarbons are ignited during flaring. Flares can be used routinely to control emissions as 

part of unloading/testing operations that are necessary to remove potentially damaging completion fluids 

from the wellbore and to provide sufficient reservoir data for the operator to evaluate a reservoir and 

development options; they can also be used during emergency process upsets. The BOEMRE regulations 

provide for some limited volume, short duration flaring or venting of oil and natural gas upon approval by 

BOEMRE (2-14 days, typically). Through 30 CFR 250.1162, BOEMRE may allow operators to burn 

liquid hydrocarbons if they can demonstrate that transporting them to market or re-injecting them into the 

formation is not technically feasible or poses a significant risk of harm to the environment. During the 

DWH event, BP received permission from BOEMRE to burn oil and flare gas because the lessee initiated 

an action which, when completed, will eliminate the need for flaring. In this case the action was a relief 

well to kill the Macondo spill. 

3.1.1.6. Safety Issues 

This chapter describes safety issues arising in the GOM resulting from the proposed action. These 

issues include (1) hydrogen sulfide and sulfurous petroleum, (2) shallow hazards, and (3) new and 

unusual technologies. 

3.1.1.6.1. Hydrogen Sulfide and Sulfurous Petroleum 

Chapter 4.1.1.9 of the Multisale EIS and Chapter 3.1.1.5.1 of the 2009-2012 Supplemental EIS 

describe the impacting factors arising from hydrogen sulfide (H2S) and sulfurous petroleum in the GOM 

resulting from a CPA proposed action. Sulfur may be present in oil as elemental sulfur, within gas as 
Impact-Producing Factors and Scenario 3-23 

H2S, or within organic molecules, all three of which vary in concentration independently. Safety and 

infrastructure concerns include the following: irritation, injury, and lethality from leaks; exposure to 

sulfur oxides produced by flaring; equipment and pipeline corrosion; and outgassing and volatilization 

from spilled oil. 

Sour oil and gas occur sporadically throughout the Gulf of Mexico OCS, primarily off the Louisiana, 

Mississippi, and Alabama coasts. Sour hydrocarbon tends to originate in carbonate source or reservoir 

rocks that may not have abundant clay minerals that serve as a binder for elemental sulfur. If not bound 

in clay minerals, it remains free and can become a part of any hydrocarbon produced or sourced from that 

rock. 

Deep gas reservoirs on the GOM continental shelf are likely to have high corrosive content, including 

H2S. There is some evidence that petroleum from deepwater areas may be sulfurous, but exploration 

wells have not identified deepwater areas that are extraordinarily high in H2S concentration. 

The BOEMRE reviews all exploration and development plans in the Gulf of Mexico OCS to account 

for the possible presence of H2S in the area(s) identified for exploration and development activities. 

Activities determined to be associated with a presence of H2S are subjected to further review and 

requirements. Federal regulations at 30 CFR 250.490 require all lessees, prior to beginning exploration or 

development operations, to request a classification of the potential for encountering H2S. The 

classification is based on previous drilling and production experience in the areas surrounding the 

proposed operations, as well as other factors. 

All operators on the OCS involved in production of sour gas or oil (i.e., >20 ppm) are also required to 

file an H2S Contingency Plan. This plan lays out procedures to ensure the safety of the workers on the 

production facility. In addition, all operators are required under 30 CFR 250.198 to adhere to the 

National Association of Corrosion Engineers’ (NACE) Standard Material Requirements—Methods for 

Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments (NACE 

MR0175-2003) (NACE, 2003) as best available and safest technology. These engineering standards 

preserve the integrity of infrastructure through specifying equipment to be constructed of materials with 

metallurgical properties that resist or prevent sulfide stress cracking and stress corrosion cracking in the 

presence of sour gas. This Agency issued a final rule (30 CFR 250.490; Federal Register, 1997a) 

governing requirements for preventing hydrogen sulfide releases, detecting and monitoring hydrogen 

sulfide and sulfur dioxide, protecting personnel, providing warning systems and signage, and establishing 

requirements for hydrogen sulfide flaring and venting. 

3.1.1.6.2. Shallow Hazards 

The Multisale EIS did not contain a discrete discussion about shallow hazards. Pre-drill seismic 

assessment of drilling hazards is an essential part of the well planning process. The type of highresolution seismic surveys that are deployed to collect the data used for shallow hazards analyses are 

described in Chapter 3.1.1.1.1. 

Shallow hazard assessments are required by BOEMRE regulations (30 CFR 250.214 and 30 CFR 

250.244); NTL 2008-G05, “Shallow Hazards Program,” explains the requirements for these surveys and 

their reports. Included in shallow hazard assessment is a structural and stratigraphic interpretation of 

seismic data to qualitatively delineate abnormal pressure zones, shallow free gas, seafloor instability, 

shallow water flow, and gas hydrates. 

The objective of the shallow hazard assessment is to identify, map, and delineate seafloor, shallow 

subsurface geologic features, and man-caused obstructions that may impact proposed oil and gas 

operations, which include the following: 

 seafloor geologic hazards such as fault scarps, gas vents, unstable slopes, and reefs; 

 shallow subsurface geologic hazards such as faults, gas hydrates and gas-charged 

sediments, buried channels, and abnormal pressure zones; and 

 synthetic hazards such as pipelines, wellheads, shipwrecks, military ordnance 

(offshore disposal sites), and debris from oil and gas operations. 
3-24 Central Planning Area Supplemental EIS

The shallow hazards survey is also used to identify and map geologic features in the vicinity of 

proposed wells, platforms, anchors and anchor chains, mounds or knolls, acoustic void zones, gas- or oilcharged sediments, or seeps associated with surface faulting that may be indicative of ocean-bottom 

chemosynthetic communities. 

Since 1987, operators have reported shallow waterflow events to this Agency. These events are a 

phenomenon encountered in water depths exceeding 600 ft (183 m). Reported waterflows are between a 

few hundred feet to more than 4,000 ft (1,219 m) below the seafloor. Water flowing up and around the 

well casing and annulus may deposit sand or silt on the seafloor within a few hundred feet of the 

wellhead. Although in most cases there is no gas content in the waterflow, in these water depths a stream 

of gas bubbles may form frozen gas hydrates at the sea bottom and on flat surfaces of seafloor drilling 

equipment. Shallow waterflows can result from buried channels filled with more permeable sediment. 

Abnormally pressured shallow sands may result from either rapid slumping or rotating faults or from 

reworked cut-and-fill channels sealed by impermeable mud or clay. In rare cases, hydrates below the 

mudline could be a source of shallow waterflow by melting down hydrates during oil production. 

Shallow waterflow events can cause additional expenditure of time and money for the driller to maintain 

well control and can lead to drilling difficulty up to and including a decision to permanently plug and 

abandon the well. Unanticipated shallow hazards can lead to downhole pressure kicks that range from 

minor and controllable to significant and uncontrollable; up to and including a serious blowout condition. 

3.1.1.6.3. New and Unusual Technology 

Chapter 4.1.1.10 of the Multisale EIS discusses the impacting factors arising from the environmental 

and engineering safety review processes for new and unusual technology in the GOM resulting from a 

proposed action. The discussion in this Supplemental EIS tiers from the discussion in the Multisale EIS. 

Operators must identify new and unusual technology in exploration and development plans. The new 

and unusual technologies are reviewed by BOEMRE for alternative compliance with permits or 

departures that may trigger additional environmental review. 

In addition to new and unusual technology for drilling, as a result of the DWH event, many 

technologies or applications were developed in attempting to stop the spill and kill the well. The NTL 

2010-N10, “Statement of Compliance with Applicable Regulations and Evaluation of Information 

Demonstrating Adequate Spill Response and Well Containment Resources,” applies to operators 

conducting operations using subsea BOP’s or surface BOP’s on floating facilities. The BOEMRE will 

now assess whether each lessee has submitted adequate information demonstrating that it has access to 

and can deploy surface and subsurface containment resources that would be adequate to promptly respond 

to a blowout or other loss of well control. Containment resources could consist of, but are not limited to, 

subsea containment and capture equipment including containment domes and capping stacks, subsea 

utility equipment including hydraulic power, hydrate control, and dispersion injection equipment. 

3.1.1.7. Decommissioning and Removal Operations 

Chapter 4.1.1.11 of the Multisale EIS and Chapter 3.1.1.6 of the 2009-2012 Supplemental EIS 

describe impacting factors arising from decommissioning and removal operations in the GOM. The 

discussion in this Supplemental EIS tiers from the discussion in the Multisale EIS and in the 2009-2012 

Supplemental EIS. 

The BOEMRE’s regulations for wellheads/casing (30 CFR 250.1710) platforms and other facilities 

(30 CFR 250.1725) require operators to remove all seafloor obstructions from their leases within 1 year of 

lease termination or relinquishment. These regulations require lessees to sever bottom-founded structures 

and their related components at least 5 m (15 ft) below the mudline to ensure that nothing would be 

exposed that could interfere with future lessees and other activities in the area. 

In 2008, this Agency conducted an Alternative Internal Control Review of idle structures and wells 

on active leases on the Gulf of Mexico OCS. This review evaluated the presence of idle infrastructure 

and a process of identifying, tracking, and decommissioning idle wells and structures. Findings indicated 

that there are a significant number of idle platforms that have not been removed and idle wells that have 

not been permanently plugged. Idle infrastructure poses a potential threat to the OCS environment and is 

a financial liability to operators and the Federal Government if it is subsequently destroyed or damaged in 

a future event, such as a hurricane. The cost and time to permanently plug wells and remove storm-
Impact-Producing Factors and Scenario 3-25 

damaged infrastructure (including pipelines) is significantly higher than decommissioning assets that are 

not damaged when decommissioned. Increased costs to deal with idle but damaged infrastructure has 

potential ramifications on the operators’ financial security requirements to operate on the OCS or even 

their financial viability. 

On September 15, 2010, BOEMRE launched plans to clear the GOM of “idle iron;” requiring 

companies to dismantle deserted platforms and permanently plug thousands of abandoned oil and gas 

wells, including some that are decades old (Dloughy, 2010). The mandate will affect nearly 3,500 

nonproducing wells and require the decommissioning of about 650 unused oil and gas production 

platforms. The new NTL 2010-G05, “Decommissioning Guidance for Wells and Platforms,” became 

effective on October 15, 2010, and clarifies the operator’s procedures for abandoning platforms and wells. 

Until now, the decommissioning and removal of infrastructure and the plugging and abandoning of 

nonproducing wells was required within a year after an operator’s offshore oil and gas lease expired. 

Historically, that policy gave companies plenty of time and freedom to use once-abandoned platforms and 

other infrastructure to support future wells and other projects. The NTL 2010-G05 explains the approach 

to ensure that idle infrastructure on active leases is decommissioned in a timely manner. It also provided 

definitions for the following: (1) capable of production in paying quantities; (2) downhole zonal 

isolation; (3) no longer useful for operations; and (4) toppled platform. The NTL also clarified, 

described, and interpreted many other issues regarding decommissioning that have arisen since 

publication of 30 CFR 250 Subpart Q in 2002. The NTL 2010-G05 now clarifies the regulations that 

require the operator to plug any well that has been idle for the past 5 years, along with any associated 

platforms and pipelines serving it, even if they are part of an active offshore lease. 

A well that is no longer useful for operations is defined as one that 

 has not been used in the past 5 years for operations associated with the exploration 

for or the development and production of oil, gas, sulphur, or other mineral resource 

or as infrastructure to support such operations; and 

 has no plans for operations associated with the exploration for or the development 

and production of oil or gas, or as infrastructure to support such operations. 

A platform or structure that is no longer useful for operations is defined as one that 

 has been toppled or otherwise destroyed; or 

 has not been used in the past 5 years for operations associated with the exploration 

for or the development and production of oil or gas, sulfur, or other mineral resource 

or as infrastructure to support such operations. 

Programmatic Environmental Assessment 

This Agency prepared Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf: 

Programmatic Environmental Assessment (Programmatic EA) (USDOI, MMS, 2005) to evaluate the full 

range of potential environmental impacts of structure-removal activities in all water depths in the CPA 

and WPA and in the areas of the EPA then open for leasing. The activities analyzed in the Programmatic 

EA include vessel and equipment mobilization, structure preparation, nonexplosive- and explosiveseverance activities, post-severance lifting and salvage, and site-clearance verification. The impactproducing factors of structure removals considered in the Programmatic EA include seafloor disturbances, 

air emissions, water discharges, pressure and acoustic energy from explosive detonations, and space-use 

conflicts with other OCS users. No potentially significant impacts were identified for air and water 

quality; marine mammals and sea turtles; fish, benthic communities, and archaeological resources; or 

other OCS pipeline, navigation, and military uses. 

On the basis of the Programmatic EA, this Agency determined that an EIS was not required and 

prepared a Finding of No Significant Impact on February 15, 2005. On February 28, 2005, this Agency 

submitted the new structure-removal Programmatic EA and a petition for new Incidental-Take 

Regulations under the MMPA to NMFS. After review of the petition and Programmatic EA, NMFS 

published a Notice of Receipt of the Agency’s Petition in the Federal Register on August 24, 2005. Only 
3-26 Central Planning Area Supplemental EIS

one comment was received by NMFS during the public comment period. On April 7, 2006, NMFS 

published the Proposed MMPA Rule for the Incidental Take of marine mammals in the Federal Register 

and the subsequent public comment period ended May 22, 2006. In addition, NMFS conducted a 

Section 7 ESA Consultation on their MMPA rulemaking efforts. The consultation was completed and 

this Agency received a new Biological Opinion and Incidental Take Statement (ITS) on August 28, 2006, 

which superseded the previous “generic” and “de-minimus” Biological Opinions/ITS’s. On June 19, 

2008, NMFS finalized their MMPA rulemaking efforts and published the Final Rule for take-regulations 

for explosive severance, which are located in Subpart S of the MMPA regulations at 50 CFR 216.211-

219. 

Removal of Bottom Debris 

Chapter 4.1.1.3.3.4 of the Multisale EIS and Chapter 3.1.1.6 of the 2009-2012 Supplemental EIS 

discuss bottom debris, which is defined as material resting on the seabed (such as cable, tools, pipe, 

drums, anchors, and structural parts of platforms, as well as objects made of plastic, aluminum, wood, 

etc.) that are accidentally lost (e.g., during hurricanes) or swept overboard from fixed or floating facilities. 

The maximum quantity of bottom debris per operation is estimated to be several tons. The BOEMRE 

requires site clearance over the assumed areal extent over which debris will fall. It is assumed that lost 

debris will be removed from the seafloor during the structure decommissioning, site clearance, and 

verification process. 

Explosive and Nonexplosive Removals 

A varied assortment of severing devices and methodologies has been designed to cut structural targets 

during the course of decommissioning activities. These devices are generally grouped and classified as 

either nonexplosive or explosive. Which severing tool the operators and contractors use takes into 

consideration the target size and type, water depth, economics, environmental concerns, tool availability, 

and weather conditions. The BOEMRE anticipates that multiple appurtenances will not be removed from 

the seafloor if placed in waters exceeding 800 m (2,625 ft). No explosive removals are projected in water 

depths >800 m (2,625 ft) because OCS regulations would offer the lessees in those water depths the 

option to avoid any severance/removal work by requesting alternate removal depths for well 

abandonments (30 CFR 250.1716(b)(3)) and facilities (30 CFR 250.1728(b)(3)). Above mudline cuts 

would be allowed with reporting requirements on the remnant’s description and height off of the seafloor 

to BOEMRE. These data are necessary for subsequent reporting to the U.S. Navy. In most cases, 

industry has indicated that it would use the alternate removal depth options, coupled with quickdisconnect equipment (i.e., detachable risers, mooring disconnect systems, etc.) to fully abandon in-place 

wellheads, casings, and other minor subsea equipment in deep water without the need for any severing 

devices. 

CPA Proposed Action Scenario: Table 3-2 reports platform removals by water-depth range as a 

result of the CPA proposed action. Of the 30-42 total production structures estimated to be removed as a 

result of the CPA proposed action, 15-20 production structures (installed landward of the 800-m [2,625-

ft] isobath) are likely to be removed using explosives.

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. Table 4-4 of the Multisale EIS reports that the number of 

production structures estimated to be removed during the years 2007-2046 is about twice the number of 

production structures estimated to be installed during the same time period. 

3.1.2. Coastal Impact-Producing Factors and Scenario 

Chapter 4.1.2 of the Multisale EIS and Chapter 3.1.2 of the 2009-2012 Supplemental EIS describe the 

coastal impacting factors arising from OCS-related infrastructure and its use during a proposed action in 

the GOM. The discussion in this Supplemental EIS tiers from the discussion in the Multisale EIS and the 

2009-2012 Supplemental EIS. 

Coastal impacting factors include (1) service bases and navigation channels, (2) gas processing plants, 

(3) coastal pipelines, and (4) disposal facilities for offshore operations. The Multisale EIS also discussed 

topical headings of helicopter hubs, construction facilities, terminals, and coastal barging. These 
Impact-Producing Factors and Scenario 3-27 

elements of OCS-related infrastructure as coastal impacting factors have not appreciably changed since 

the 2009-2012 Supplemental EIS and those discussions are hereby incorporated by reference into this 

Supplemental EIS. 

Chapter 4.1.2.1 of the Multisale EIS and Chapter 3.1.2 of the 2009-2012 Supplemental EIS describe 

the potential need for construction of new facilities and existing facility expansions that may result from a 

proposed lease sale and the OCS Program. Projected new coastal infrastructure as a result of the OCS 

Program is shown by State in Table 4-9 of the Multisale EIS. The following information summarizes the 

scenario analysis incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS and provides 

new information collected since these documents were prepared. 

The BOEMRE has reexamined the scenario analysis presented in the Multisale EIS and in the 2009-

2012 Supplemental EIS in light of the DWH event. To date, there has been an influx of much new 

information related to the oil spill. However, it is too early to determine conclusively whether or not the 

scenario analysis should be modified, and if it were, what these changes would encompass. The presence 

of coastal infrastructure is not subject to rapid fluctuations. Infrastructure projections reflect long-term 

industry trends, and changes to these trends cannot be determined from the few months of post-DWH data 

that are available. While changes (if any) to the current scenario analysis due to the DWH event and its 

aftermath are not expected, BOEMRE will continue to collect new data and to monitoring of changes in 

infrastructure demands in order to support scenario projections that reflect current and future industry 

conditions. 

According to the scenario analysis in the Multisale EIS and in the 2009-2012 Supplemental EIS, the 

construction of 0-1 new gas processing facilities would be expected to occur near the end of the 40-year 

life of a single lease sale. Most of the projected new pipelines would be offshore and would tie into the 

existing offshore pipeline infrastructure, with 0-1 new pipeline landfalls expected to occur toward the end 

of the 40-year lifespan of a lease sale. The lingering effects of the drilling moratorium and changes in 

Federal requirements for drilling safety has depressed demand for gas processing facilities and pipeline 

landfalls. Given this uncertain environment post-DWH, the likelihood is diminished that any new gas 

processing facility or pipeline landfall would result from a single lease sale and, hence, the likelihood of 

new facilities or pipeline landfalls has moved closer to zero and farther from one (Dismukes, personal 

communication, 2010a). Maintenance dredging of existing navigation channels is still expected, but no 

new navigation channels are expected to be dredged as a result of the proposed action. The analyses of 

coastal infrastructure presented in the Multisale EIS concluded that no new solid-waste facilities would be 

built as a result of a single lease sale or as a result of the OCS Program. Recent research further supports 

these past conclusions that existing solid-waste disposal infrastructure is adequate to support both existing 

and projected offshore oil and gas drilling and production needs. The volume of OCS waste generated is 

closely correlated with the level of offshore drilling and production activity. Demand for waste disposal 

facilities is influenced by the volume of waste generated (Dismukes et al., 2007). At this time, it is 

unclear how long this temporary interruption in activity will continue or how it might affect later years. 

Until OCS drilling activity recovers, the potential for a new waste facility as a result of the proposed 

action is highly unlikely; however, such a conclusion remains tentative at this early date post-DWH. 

The source of the majority of the information on coastal infrastructure and activities presented in the 

Multisale EIS is this Agency’s study, OCS-Related Infrastructure in the Gulf of Mexico Fact Book (The 

Louis Berger Group, Inc., 2004). An update of this fact book, OCS-Related Infrastructure Fact Book: 

Post-Hurricane Impact Assessment (Volume I) and Communities in the Gulf of Mexico (Volume II), is 

nearly complete (Dismukes, in preparation-a). Within the last 4 years, this Agency analyzed historical 

data and validated past scenario projections of new pipeline landfalls and new onshore waste disposal 

sites (USDOI, MMS, 2007d and 2007e). 

The following coastal infrastructure types are highlighted for discussion because new general 

information is available, new facilities are projected to be constructed as a result of the proposed action, 

and/or new information relevant to discussions of the DWH event is available. 

3.1.2.1. Service Bases 

Chapter 4.1.2.1 of the Multisale EIS and Chapter 3.1.2.1 of the 2009-2012 Supplemental EIS describe 

the coastal impacting factors arising from service bases in the GOM. A service base is a community of 

businesses that load, store, and supply equipment, supplies, and personnel that are needed at offshore 
3-28 Central Planning Area Supplemental EIS

work sites. Chapters 3.3.5.8.1 and 4.1.2.1.1 of the Multisale EIS present a detailed description of OCSrelated service bases. While no proposed action is projected to significantly change existing OCS-related 

service bases or require any additional service bases, a proposed action would contribute to the use of 

existing service bases. Figure 3-4 shows the 50 service bases the industry currently uses to service the 

OCS. These facilities were identified as the primary service bases from plans received by BOEMRE. 

The ports of Fourchon, Cameron, Venice, and Morgan City, Louisiana, are the primary service bases for 

GOM mobile rigs. Major platform service bases are Galveston, Freeport, and Port O’Connor, Texas; 

Cameron, Fourchon, Intracoastal City, Morgan City, and Venice, Louisiana; Pascagoula, Mississippi; and 

Theodore, Alabama. 

Exploration and development plans received by BOEMRE identify primary and secondary service 

bases for three types of support: supply vessel; crewboat; and helicopter. Supply vessel bases are loading 

points and provide temporary storage for supply vessels that transport pipe and bulk supplies. Crewboats 

transport personnel and small supplies. Collectively, supply vessels and crewboats are known as offshore 

supply vessels (OSV’s). Approximately 1,200 OSV’s are operating in the GOM. Important drivers for 

the OSV market include the level of offshore exploration and drilling activities, current oil and gas prices, 

expectations for future oil and gas prices, and customer assessments of offshore prospects (Dismukes, in 

preparation-b). Helicopters transport personnel and small supplies, and they may also patrol pipelines to 

spot signs of damage or leakage. Helicopters service drilling rigs, production platforms, and pipeline 

terminals, as well as specialized vessels such as jack-up barges. The OCS activity levels and offshore oil 

and gas industry transportation needs substantially influence the demand for and profitability of helicopter 

services (Dismukes, in preparation-b). A service base may support one or more of these activities, while 

an offshore facility may utilize one service base for all three uses or different service bases for each. 

Because of changing weather or operational conditions, small amounts of vessel and helicopter traffic 

may be dispatched from alternative bases. However, such shifts are expected to be only temporary and 

vessel traffic and helicopter transport generally returns to primary and secondary bases as soon as 

possible. 

As OCS operations have progressively moved into deeper waters, larger vessels with deeper drafts 

have been phased into service, mainly for their greater range, faster speed, and larger carrying capacity. 

Service bases with the greatest appeal for deepwater activity have several common characteristics: strong 

and reliable transportation systems; adequate depth and width of navigation channels; adequate port 

facilities; existing petroleum industry support infrastructure; location central to OCS deepwater activities; 

adequate worker population within commuting distance; and insightful strong leadership. Typically, 

deeper draft service vessels require channels with depths of 20-26 ft (6-8 m). 

Port Fourchon is usually the primary service base identified in exploration and development plans for 

deepwater activities; however, some operator plans identify other bases instead of Port Fourchon for 

either crew or helicopter use, or as a backup to Port Fourchon. Because of the limited amount of land 

available at Port Fourchon, the port may face boat docking capacity constraints in the long term. 

Operators looking to diversify risk from shutdowns (such as those shutdowns after major hurricanes) are 

also likely to look to other ports. Thus, in the longer term, other deepwater access ports such as Theodore 

and Mobile, Alabama, and Pascagoula, Mississippi, may also support OCS deepwater activities in the 

CPA. The majority of deepwater activity to date has been located south of Port Fourchon or southeast of 

New Orleans. The Agency-funded study, Fact Book: OCS-Related Energy Infrastructure and PostHurricane Impact Assessment (Dismukes, in preparation-a), should be published in 2011 and includes an 

in-depth hurricane impact analysis for each type of coastal infrastructure. 

CPA Proposed Action Scenario: The proposed action contributes to the continued need for 

maintenance of existing service bases. However, no new service bases are expected to develop as a direct 

result of the CPA proposed action. 

OCS Program Scenario: Newer geologic trends being exploited by today’s operators may lead to 

development of capability or the relocation of facilities to a new service base along the Texas Gulf Coast 

during the years 2007-2046. 

Navigation Channels 

Chapter 4.1.2.9 of the Multisale EIS and Chapter 3.1.2.1 of the 2009-2012 Supplemental EIS describe 

the coastal impacting factors arising from navigation channels in the GOM. Navigation channels undergo 
Impact-Producing Factors and Scenario 3-29 

maintenance dredging that is essential for sustaining proper water depths to allow ships to move safely 

through the waterways to ports, services bases, and terminal facilities. In the northern GOM, the existing 

system of navigation channels is projected to be adequate to allow proper accommodation for vessel 

traffic that will occur as a result of a single proposed action. The Gulf-to-port channels and the Gulf 

Intracoastal Waterway (GIWW) that support prospective OCS ports are maintained by regular dredging 

and are generally sufficiently deep and wide to handle OCS-related traffic (Figure 3-5). The COE is the 

Federal agency responsible for the regulation and oversight of navigable waterways. The maintained 

depth for each waterway is shown in Table 3-36 of the Multisale EIS. All single lease sales contribute to 

the level of demand for offshore supply vessel support; hence, they also contribute to the level of vessel 

traffic that travels through the navigation channels to support facilities. While maintenance dredging is 

essential for vessels to safely reach support facilities, it is a controversial process because it necessarily 

occurs in or near environmentally sensitive areas such as valuable wetlands, estuaries, and fisheries 

(Dismukes, in preparation-b). 

CPA Proposed Action Scenario: The proposed action contributes to the continued need for 

maintenance dredging of existing navigation channels. However, no additional maintenance dredging is 

expected to be scheduled or new navigation channels are expected to be constructed as a direct result of 

the CPA proposed action. 

OCS Program Scenario: There is no current expectation for new navigation channels to be 

authorized and constructed during the years 2007-2046 as a direct result of the OCS Program. One major 

Federal channel, the Mississippi River Gulf Outlet, was taken out of service and sealed with a rock dike in 

2009. 

3.1.2.2. Gas Processing Plants 

Chapter 4.1.2.1.4.2 of the Multisale EIS and Chapter 3.1.2.2 of the 2009-2012 Supplemental EIS 

describe the coastal impacting factors arising from gas processing plants and the potential for new 

facilities and/or expansion at existing facilities in the GOM. As of January 1, 2007, there were 278 gas 

processing plants in the Gulf States, representing 56 percent of U.S. gas processing capacity (Dismukes, 

in preparation-a). 

Over the past 5 years, there has been a substantial decrease in offshore natural gas production, 

partially as a result of increasing emphasis on onshore shale gas development, which is less expensive to 

produce, is closer to consumption sources, and provides larger per well production opportunities and 

reserve growth. Also, there has been a trend toward more efficient gas processing facilities with greater 

processing capacities (Dismukes, personal communication, 2010b). In Alabama, Mississippi, and the 

eastern portion of South Louisiana, plant capacity increased significantly as plant expansions occurred 

and new larger plants were built in response to offshore production (USDOE, Energy Information 

Administration, 2006). While natural gas production on the OCS shelf (shallow water) has been rapidly 

declining, deepwater gas production has been increasing, but not quickly enough to make up the 

difference. Increasing onshore shale gas development, declining offshore gas production, and the 

increasing efficiency and capacity of existing gas processing facilities are trends that have combined to 

lower the need for new gas processing facilities along the Gulf Coast in the past 5 years. Combined with 

this, existing facilities that were already operating at about 50 percent of capacity prior to the 2005 

hurricane season are operating at even lower capacity utilization levels now. Spare capacity at existing 

facilities should be sufficient to satisfy new gas production for many years, although there remains a slim 

chance that a new gas processing facility may be needed by the end of the 40-year life of the proposed 

action (Dismukes, personal communication, 2010b). 

CPA Proposed Action Scenario: The BOEMRE projects that 0-1 new gas processing facility may be 

constructed as a result of the CPA proposed action. However, the likelihood of a new gas processing 

facility has moved closer to zero and farther from one (Dismukes, personal communication, 2010b). 

OCS Program Scenario: Expectations for new gas processing facilities being built during the period 

2007-2046 as a direct result of the OCS Program are dependent on long-term market trends that are not 

easily predicable over the next 40 years. Existing facilities will experience equipment switch-outs or 

upgrades during this time. 
3-30 Central Planning Area Supplemental EIS

3.1.2.3. Coastal Pipelines 

Chapters 3.3.5.8.8 and 4.1.2.1.7 of the Multisale EIS and Chapter 3.1.2.2 of the 2009-2012 

Supplemental EIS describe the coastal impacting factors arising from OCS pipelines in coastal waters 

(State offshore and inland waters) and coastal onshore areas. The OCS pipelines near shore and onshore 

may join pipelines carrying production from State waters or territories for transport to processing facilities 

or to distribution pipelines located farther inland. In the Multisale EIS, this Agency assumed that the 

majority of new Federal OCS pipelines would connect to the existing pipelines in Federal and State 

waters and that very few would result in new pipeline landfalls. Therefore, this Agency projected 0-1 

pipeline landfalls per lease sale (USDOI, MMS, 2007b). Between the Multisale EIS and the 2009-2012 

Supplemental EIS, this Agency tested this assumption by analyzing past lease sale outcomes and 

determined that it is unlikely that even one pipeline landfall will result from an individual proposed action 

(USDOI, MMS, 2007d). Oil and gas companies have a strong financial incentive to reduce costs by 

utilizing the existing mature pipeline network that already exists in the GOM to the fullest extent possible. 

Economies of scale are a factor in pipeline transportation, and maximization of the amount of product 

moved through an already existing pipeline decreases the long-term average cost of production. 

Additional considerations include mitigation costs for any new wetland and environmental impacts and 

various landowner issues at the landfall point. These are strong incentives to move new production into 

existing systems and to avoid creating new landfalls (USDOI, MMS, 2007d). Therefore, BOEMRE 

projects that the majority of new pipelines constructed as a result of a CPA proposed action would 

connect to the existing pipeline infrastructure. In the rare instance that a new pipeline would need to be 

constructed, it will likely be because there are no existing pipelines reasonably close and it is more cost 

effective to construct a pipeline to shore; although for an operator to choose this contingency is thought to 

be highly unlikely (Dismukes, personal communication, 2010c). 

CPA Proposed Action Scenario: The Multisale EIS and the 2009-2012 Supplemental EIS project that 

0-1 new landfalls are projected for a CPA proposed action. This scenario projection stands, although the 

likelihood of a new pipeline landfall has moved closer to zero and farther from one (Dismukes, personal 

communication, 2010a). 

OCS Program Scenario: The Multisale EIS projected that from 2007 to 2046, 80-118 new pipelines 

were projected to be built in State waters as a result of the OCS Program. Of those pipelines, 32-47 were 

projected to make landfall. However, the reassessment of this scenario between the Multisale EIS and the 

2009-2012 Supplemental EIS resulted in a more conservative projection that even one pipeline landfall as 

a result of each lease sale during the OCS Program is unlikely (USDOI, MMS, 2007d). Therefore, the 

OCS Program from 2007 to 2046 is unlikely to result in more than 11 new pipeline landfalls (see also 

Chapter 3.1.1.4.1). 

3.1.2.4. Disposal Facilities for Offshore Operations 

Chapters 3.3.5.8.7 and 4.1.2.1.6 of the Multisale EIS and Chapter 3.1.2.4 of the 2009-2012 

Supplemental EIS describe the coastal impacting factors arising from the infrastructure network needed to 

manage the spectrum of waste generated by OCS activity and disposal onshore in the GOM. The 

analyses of coastal infrastructure presented in the Multisale EIS concluded that no new solid-waste 

facilities would be built as a result of a single lease sale or as a result of the OCS Program. Between the 

Multisale EIS and the 2009-2012 Supplemental EIS additional research was conducted that further 

supports past conclusions that existing solid-waste disposal infrastructure is adequate to support both 

existing and projected offshore oil and gas drilling and production needs (Dismukes et al., 2007). 

Recently, there is a trend toward incorporating more innovative methods for waste handling in an attempt 

to reduce the chance of adverse environmental impacts. Some of these innovative methods include 

hydrocarbon recovery/recycling programs, slurry fracture injection, treating wastes for re-use as road base 

or levee fill, and segregating waste streams to reduce treatment time and improve oil recovery (Dismukes, 

in preparation-a). 

Before the DWH event, this Agency’s analyses indicated that there was an abundance of solid-waste 

capacity in the GOM region and, thus, it is highly unlikely that any new waste facilities would be 

constructed. Recent research shows that the volume of OCS waste generated is closely correlated with 

the level of offshore drilling and production activity (Dismukes, in preparation-a). If offshore activities 

increase to the extent that a need for more capacity develops, it will probably be met by expansion of 
Impact-Producing Factors and Scenario 3-31 

existing facilities. However, it is now unclear whether this will remain true; therefore, more research is 

needed (Dismukes, personal communication, 2010d). Due to the temporary suspensions (no longer in 

effect) on deepwater drilling, there has been some reduction in offshore drilling activity. Given this 

situation, the demand for waste disposal facilities may not be likely to increase. However, at this time, 

BOEMRE cannot predict how long this temporary interruption will continue or how long it will take for 

activity levels to recover. Since there is not enough information at this time to draw a solid conclusion, 

BOEMRE will continue to monitor waste disposal demands and activity in the post-DWH environment. 

Chapter 4.1.1.18.4.2 provides a discussion of environmental justice issues related to waste disposal 

facilities. 

CPA Proposed Action Scenario: Existing onshore facilities will continue to be used to dispose of 

wastes generated offshore. However, no new disposal facilities are expected to be licensed as a direct 

result of the proposed action. 

OCS Program Scenario: There is no current expectation for new onshore waste disposal facilities to 

be authorized and constructed during the 2007-2046 period as a direct result of the OCS Program. 

Existing facilities are likely to undergo expansion, but no definitive projections can be made. 

Summary 

In response to the DWH event, BOEMRE has reexamined the scenario analysis presented in the 

Multisale EIS and in the 2009-2012 Supplemental EIS. According to the scenario analysis in the 2009-

2012 Supplemental EIS, the construction of 0-1 new gas processing facilities and 0-1 new pipeline 

landfalls would be expected to occur near the end of the 40-year life of a single lease sale. Given the 

uncertain environment post-DWH, the CPA proposed action is very conservative since the likelihood is 

diminished further that any new gas processing facility or pipeline landfall would result from a single 

lease sale (Dismukes, personal communication, 2010a). New information on the DWH event continues to 

be developed. The BOEMRE recognizes the need for, and is currently conducting continuous monitoring 

of, changes in infrastructure demands in order to adequately determine scenario projections for current 

and future environmental assessments. 

3.2. IMPACT-PRODUCING FACTORS AND SCENARIO—ACCIDENTAL EVENTS

The NEPA requires Federal agencies to consider potential environmental impacts of a proposed 

action as part of agency planning and decisionmaking. Actions that could result in impact are analyzed; 

including those that have a very low probability of occurring, but that the public considers important, are 

controversial, or may have severe consequences. The accidental events that fall into this category and 

that are addressed in this section are (1) oil spills, (2) losses of well control, (3) pipeline failures, (4) 

vessel collisions, and (5) chemical or drilling fluid spills. 

The OCS Program pollution-prevention requirements include features such as redundant safety 

systems, and periodic inspection and testing protocols. Although the likelihood for spills of the 

magnitude of the DWH event are rare, when they do occur the affects on physical, biological, and 

socioeconomic resources can be dramatic and potentially severe. 

3.2.1. Oil Spills 

Oil spills are unplanned, accidental events but their frequency and volume can be estimated from past 

occurrences. Chapter 4.3.1 of the Multisale EIS analyzes the risk of spills that could occur as a result of 

activities associated with a CPA proposed action. Chapter 4.3.1.1 of the Multisale EIS discusses spill 

prevention. 

Chapter 4.3.1.2 of the Multisale EIS provides an overview of spill risk analysis including more 

information about the inputs to the spill scenario and the trajectory and weathering modeling. Chapter 

4.3.1.3 of the Multisale EIS discusses past OCS spills. Oil also enters the GOM by pathways and sources 

other than spills, including natural seeps, permitted discharges, and sources related to human activities; 

these are discussed in Chapter 4.1.3.4 of the Multisale EIS and in Chapter 3.1.1.3 of this Supplemental 

EIS. 

Chapter 4.3.1.4 of the Multisale EIS discusses the physical and chemical properties of oil. The 

properties of the spilled oil can influence the persistence of the spill on the water’s surface and the success 
3-32 Central Planning Area Supplemental EIS

of spill cleanup efforts. The fate of oil in the environment depends on many factors, such as the source 

and composition of the oil, as well as its persistence (NRC, 2003). Persistence can be defined and 

measured in different ways (Davis et al., 2004), but the National Research Council generally defined 

persistence as how long oil remains in the environment (NRC, 2003, p. 89). Once oil enters the 

environment, it begins to change through physical, chemical, and biological weathering processes (NRC, 

2003). These processes may interact and affect the properties and persistence of the oil, including the 

following: 

 evaporation (volatilization); 

 emulsification (the formation of a mousse); 

 dissolution; 

 oxidation; and 

 transport processes (NRC, 2003; Scholz et al., 1999). 

Horizontal transport takes place via spreading, advection, dispersion, and entrainment while vertical 

transport takes place via dispersion, entrainment, Langmuir circulation, sinking, overwashing, 

partitioning, and sedimentation (NRC, 2003). The persistence of an oil slick is influenced by the 

effectiveness of oil-spill-response efforts and affects the resources needed for oil recovery (Davis et al., 

2004). The persistence of an oil slick may also affect the severity of environmental impacts. 

Crude oils are not a single chemical, but instead are complex mixtures with varied compositions. 

Thus, the behavior of the oil and the risk the oil poses to natural resources depends on the composition of 

the specific oil encountered (Michel, 1992). Generally, oils can be divided into three groups of 

compounds: (1) light-weight; (2) medium-weight; and (3) heavy-weight components. 

Of the oil reservoirs sampled in the Gulf of Mexico OCS, the majority fall within the light-weight 

category, while less than one-quarter are considered medium-weight and a small portion are considered 

heavy-weight. Oil with an API gravity of 10.0 or less would sink and has not been encountered in the 

Gulf of Mexico OCS (USDOI, BOEMRE, 2010c). 

Heavy-weight oil may persist in the environment longer than the other two types of oil, but the 

medium-weight components within oil present the greatest risks to organisms because, with the exception 

of the alkanes, these medium-weight components are persistent, bioavailable, and toxic (Michel, 1992). 

An experiment in the North Sea, Deep Spill, indicated that the majority of oil released during a 

deepwater blowout would quickly rise to the surface and form a slick (Johansen et al., 2001). In such a 

case, impacts from a deepwater oil spill would occur at the surface where the oil is likely to be mixed into 

the water and dispersed by wind and waves. The oil would undergo natural physical, chemical, and 

biological degradation processes including weathering. However, data and observations from the DWH 

event challenged the previously prevailing thought that most oil from a deepwater blowout would quickly 

rise to the surface. While analyses are in their preliminary stages, it appears that measurable amounts of 

hydrocarbons (dispersed or otherwise) are being detected in the water column as subsurface plumes 

(Chapter 4.2.1.2.2.1) and perhaps on the seafloor in the vicinity of the release. After the Ixtoc blowout in 

1979, which was located 50 mi (80 km) offshore in the Bay of Campeche, Mexico, some subsurface oil 

also was observed dispersed within the water column (Boehm and Fiest, 1982); however, the scientific 

investigations were limited (Reible, 2010). 

As spill size increases, the occurrence rate decreases and so does the number of spills estimated to 

occur (Table 3-5) (also see Anderson and LaBelle, 2000). In general terms, coastal waters adjacent to the 

CPA are expected to be impacted by many frequent small spills (≤1 bbl); few, infrequent, moderatelysized spills (>1 and <1,000 bbl); and rarely a large spill (≥1,000 bbl) as a result of activities associated 

with the CPA proposed action. 

The following discussion provides separate risk information for offshore spills ≥1,000 bbl, offshore 

spills <1,000 bbl, and coastal spills that may result from the proposed action. 
Impact-Producing Factors and Scenario 3-33 

Past Spill Projections and Future Trends 

Comments on prior EIS’s questioned the validation between the actual number of spills that resulted 

from a proposed lease sale to the projected number of spills in the NEPA document. This Agency has not 

performed this validation. When spills are reported to USCG, the location of the spill, the type of vessel, 

and the volume and the material spilled is identified. The USCG does not attribute a spill back to a 

BOEMRE lease sale. More information is available about the larger spills than the small spills, and some 

of them can be matched with a particular lease sale. In other cases, it is more difficult to nearly 

impossible to link a spill to a lease sale because, for example, a fuel spill could occur from a vessel that 

services multiple facilities leased during different sales, or a pipeline spill could release oil combined 

from multiple production locations that were leased during different sales. Many of the small spills do 

not have a known source and so cannot be linked to a lease sale. An attempt was made in Canada to 

determine the accuracy of the predicted oil spills from several projects (Fraser and Ellis, 2008). In their 

investigation of spills of <50 bbl from projects in Nova Scotia and Newfoundland, they found that 

predicted spills underestimated the number of observed spills. 

The U.S. consumption of oil is predicted to rise. The percentage of oil imported has been rising over 

time. Most imports, with the exception of Canadian oil, are transported by vessel. Fifty-three percent of 

oil imports, the majority as crude oil, arrive via the Gulf Coast (Ramseur, 2010). Nationally, of the oil 

spills in coastal and marine areas that are within USCG jurisdiction, 50 percent of both the incidents and 

the volume spilled occur in the GOM and its shoreline states, making the Gulf Coast an area of 

concentrated use. 

The decline in spill incidents is attributable to implementation of the Act to Prevent Pollution from 

Ships. This Act reflects U.S. implementation of Annex I of the 1973 International Convention for the 

Prevention of Pollution from Ships, as modified by the Protocol of 1987 (MARPOL 73/78), which 

requires vessels to have equipment that minimizes oil discharges, such as oil-water separators, and a 

shipboard oil-pollution emergency plan. The decline in spill volume is attributable to a decline in volume 

spills by oil tankers and barges regulated by the OPA, which increased liability (Ramseur, 2010). 

3.2.1.1. Risk Analysis for Offshore Spills 1,000 bbl 

Methods 

Chapter 4.3.1.5 of the Multisale EIS addresses the risk of offshore spills ≥1,000 bbl that could occur 

from accidents associated with activities resulting from a proposed action. Spill rates (Table 4-16 of the 

Multisale EIS) were calculated based on the assumption that spills occur in direct proportion to the 

volume of oil handled and are expressed as number of spills per billion barrels of oil handled. Anderson 

and LaBelle (2000) provide more information on OCS spill-rate methodologies and trends. A discussion 

of how the range of resource estimates was developed is provided in Chapter 4.1.1.1 of the Multisale EIS 

and in Chapter 3.1.1 of this Supplemental EIS. In addition, BOEMRE is in the process of updating these 

spill rates, which will include the recent DWH event; however, significant changes to the spill rates for 

the entire OCS are not anticipated (Anderson, written communication, 2010). 

The mean number of future offshore spills ≥1,000 bbl is calculated by multiplying the spill 

occurrence rate for spills ≥1,000 bbl (1.51) by the volume of oil estimated to be produced as a result of 

the proposed action (Anderson and LaBelle, 2000). The median size of spills ≥1,000 bbl that occurred 

during 1985-1999 is 4,551 bbl, and the median size for spills ≥10,000 bbl is 15,000 bbl (Table 4-16 of the 

Multisale EIS). 

Estimates of Spill Numbers 

As shown on Table 3-5, the mean number of spills estimated for the CPA proposed action is 

1-3 spills 1,000 bbl. 

Fate 

Offshore spills ≥1,000 bbl are the most likely to persist long enough on the water’s surface to impact 

the shoreline. The fate of an oil spill is influenced by many variables. Aspects that influence spill 
3-34 Central Planning Area Supplemental EIS

persistence are discussed in Chapter 4.3.2.5.4 of the Multisale EIS and in Chapter 3.2.1 of this 

Supplemental EIS, as related to oil type, and they are summarized below (see also Table 3-6). 

Table 4-37 of the Multisale EIS provides a mass balance over time for a hypothetical spill related to a 

CPA proposed action, respectively, which are considered in this Supplemental EIS. Weathering 

processes include evaporation of volatile hydrocarbons into the atmosphere, dissolution of soluble 

components, dispersion of oil droplets into the water column, emulsification and spreading of the slick on 

the surface of the water, chemo- or photooxidation, biodegradation, and in some cases sedimentation 

(sinking) (ITOPF, 2010a; NRC, 2003). 

Over time, if the slick is not completely dissipated, a tar-like residue may be left; this residue breaks 

up into smaller tar lumps or tarballs that usually sink below the sea surface but not necessarily to the 

seafloor. Not all oils form tarballs. 

The BOEMRE used the SINTEF model to numerically model weathering processes (Prentki et al., 

2004). Model results from the SINTEF weathering model for the CPA are presented in Table 4-36 of the 

Multisale EIS. 

Movement into the deep waters of the Gulf of Mexico increasingly relies on subsea production 

infrastructure, possibly increasing the risk of seafloor releases. As noted in Chapter 3.2.1, the behavior 

of a spill depends on many things, including the characteristics of the oil being spilled as well as 

oceanographic and meteorological conditions. An experiment in the North Sea indicated that the majority 

of oil released during a deepwater blowout would quickly rise to the surface and form a slick (Johansen et 

al., 2001). In such a case, impacts from a deepwater oil spill would occur at the surface where the oil is 

likely to be mixed into the water and dispersed by wind and waves. The oil would undergo natural 

physical, chemical, and biological degradation processes including weathering. However, data and 

observations from the DWH event challenged the previously prevailing thought that most oil from a 

deepwater blowout would quickly rise to the surface. While analyses are in their preliminary stages, it 

appears that measurable amounts of hydrocarbons (dispersed or otherwise) were detected in the water 

column as subsurface plumes (Chapter 4.2.1.2.2.1) and perhaps on the seafloor in the vicinity of the 

release. After the Ixtoc blowout in 1979, which was located 50 mi (80 km) offshore in the Bay of 

Campeche, Mexico, some subsurface oil also was observed dispersed within the water column (Boehm 

and Fiest, 1982); however, the scientific investigations were limited (Reible, 2010). The water quality of 

marine waters would be affected by the dissolved components and oil droplets that are small enough so 

that they do not rise to the surface or are mixed downward by surface turbulence. Subsurface oil plumes 

would be affected by subsurface currents and could be diluted over time. Even in the subsurface, oil 

would undergo natural physical, chemical, and biological degradation processes including weathering. 

Chapter 4.3.1.5.6 of the Multisale EIS provides an estimate of the length of coastline affected by 

offshore spills ≥1,000 bbl. The maximum length of shoreline affected by a CPA representative spill 

≥1,000 bbl is estimated to be 50 km (31 mi) of shoreline, assuming such a spill were to reach land within 

12 hours (Table 4-36 of the Multisale EIS). Some oil could become redistributed because of longshore 

currents, and further smearing of the slick from its original landfall could also occur. 

Likelihood of Occurring and Contacting Environmental Resources 

The BOEMRE uses the Oil Spill Risk Analysis (OSRA) model to estimate the likely trajectories of 

hypothetical offshore spills ≥1,000 bbl. The trajectories, combined with estimated spill occurrence, are 

used to estimate the risk of future spills occurring and contacting environmental features. Chapter 

4.3.1.5.5 of the Multisale EIS briefly summarized the OSRA model, while Ji et al. (2007) provides a 

detailed description of the OSRA model. The probability of spill occurring as a result of the proposed 

CPA action and contacting environmental resources of concern is provided in Figures 4-14 through 4-31 

of the Multisale EIS. 

All proposed GOM sales for the 5-Year Program were considered in the OSRA run for the Multisale 

EIS. The scenario for the CPA proposed action has been revised and is discussed in Chapter 3.1.1. A 

new OSRA run based on just the last CPA proposed lease sale in this Supplemental EIS scenario would 

not be expected to substantially affect probabilities in comparison with those obtained from the previous 

OSRA run. 
Impact-Producing Factors and Scenario 3-35 

Summary of the Catastrophic Spill OSRA Run 

After the DWH event, BOEMRE worked to develop an OSRA model run to adequately assess a 

hypothetical oil spill that spills continuously at a fixed rate from an assigned location over an assigned 

duration. Preliminary model runs were conducted to track oil-spill trajectories for 90 days in order to 

simulate a long-duration spill from a given point. The model tracked the oil-spill trajectories throughout 

the 90 days (simulated spilling) and stopped the spill after the 90th day to simulate the point at which well 

control was reestablished and after an additional 30 days after capping to simulate the behavior of oil at 

sea. 

The probability estimates for land contact were tabulated as 90-day groupings corresponding to each 

quarter of a year (Q1, Q2, Q3, and Q4). These 3-month probabilities can be used to estimate the average 

number of land segments contacted during a spill event within the designated quarter. The groupings by 

quarter capture the differences in meteorological and oceanographic conditions in the GOM as they vary 

over the years from 1993 to 1998 (the most recent GOM data available to BOEMRE). Five launch points 

were selected for five independent model runs to assess the probably of oil contacting the shoreline from 

each given hypothetical launch point. The five launch points for the simulated spill corresponded to the 

following OCS areas in the WPA and CPA: 

 LP1—CPA shelf area, west of the Mississippi River Delta, offshore south-central 

Louisiana, deepwater; 

 LP2—CPA shelf edge area, east of the Mississippi River Delta, south of the 

Alabama-Mississippi border, deepwater; 

 LP3—CPA slope area, west of the Mississippi River Delta, due south of New 

Orleans, ultra-deepwater; 

 LP4—WPA shelf area, deepwater; and 

 LP5—WPA slope area, ultra-deepwater. 

The following first-order results were obtained for a spill of 90 days duration: 

 LP1—moderate probability of contacting coastal parishes in south-central Louisiana 

to counties in north-central Gulf Coast Texas during all quarters of the year, greatest 

probability in Q3 and Q4; 

 LP2—moderate to large probability of contacting Mississippi delta and coastal 

counties of Alabama and Mississippi in all quarters, greatest probability in Q1, Q2 

and Q4; 

 LP3—small probability of contacting parishes in east-central Louisiana, greatest 

probability in Q2; 

 LP4—moderately-large probability of contacting the counties of south-central Gulf 

Coast Texas, greatest probability in Q2; and 

 LP5—small probability of a spill contacting the coastal counties of mid-Gulf Coast 

Texas, greatest probability in Q2. 

This exercise is a first of its kind because, although this Agency’s OSRA model accounts for an 

instantaneous spill, it was not designed specifically to model a spill over a given duration. This approach 

is still under review and development. Preliminary model runs were conducted and only preliminary data 

are currently available; however, this effort will continue to be developed and advanced to ensure that the 

most conservative estimates of environmental impacts are available and that all impacts are disclosed. 

Appendix C contains a greater explanation of the catastrophic spill OSRA run. 
3-36 Central Planning Area Supplemental EIS

3.2.1.2. Risk Analysis for Offshore Spills <1,000 bbl 

A description of accidental events, including offshore spills <1,000 bbl can be found in Chapter 

4.3.1.6 of the Multisale EIS and in Chapter 3.2.1.2 of the 2009-2012 Supplemental EIS. The following 

information describes spills <1,000 bbl. To discuss spills <1,000 bbl, information is broken into size 

groups, as shown in Table 4-16 of the Multisale EIS. 

Analysis of historical data shows that most offshore OCS oil spills have been 1 bbl (Figure 4-32 of 

the Multisale EIS). Although spills of 1 bbl have made up 94 percent of all OCS-related spill 

occurrences, spills of this size have contributed very little (5%) to the total volume of OCS oil that has 

been spilled. Most of the total volume of OCS oil spilled (95%) has been from spills 10 bbl. 

The number of offshore spills <1,000 bbl estimated to occur over the next 40 years as a result of the 

proposed action is provided in Table 3-5, which has been updated from Table 4-35 of the Multisale EIS

and from Table 3-6 of the 2009-2012 Supplemental EIS. The number of spills is estimated by 

multiplying the oil-spill rate for each of the different spill size groups by the projected oil production as a 

result of the proposed action. The number of spills >500 and <1,000 bbl estimated to occur is <1 to 1 for 

the CPA proposed action. In the spill size range of >50-500 bbl, 5-11 spills are estimated to occur from 

activities related to the CPA proposed action. Multiplying the estimated number of spills by the median 

or average spill sizes for each size group yields the volume of oil estimated to be spilled as a result of the 

proposed action over the 40-year analysis period. A total of 1,070-2,920 bbl of oil is estimated from 

spills <1,000 bbl in size as a result of the CPA proposed action. 

3.2.1.3. Risk Analysis for Coastal Spills 

Chapter 4.3.1.7 of the Multisale EIS addresses the risk of coastal spills of all sizes that could occur 

from accidents associated with activities resulting from a proposed action. Chapter 3.2.1.3 of the 2009-

2012 Supplemental EIS provides an update to the Multisale EIS. 

Spills in coastal waters could occur as a result of transportation and handling of OCS-produced oil as 

it passes through State waters and along navigation channels, rivers, and through coastal bays. The 

BOEMRE projects that almost all (>99%) oil produced in waters <800 ft (244 m) deep as a result of the 

proposed action will be brought ashore by pipelines, while 50-100 percent of oil produced in waters 

>800 ft (244 m) deep will be brought ashore by tanker. Because piped oil is commingled at shore bases 

and cannot be directly attributed to a particular lease sale, this analysis of coastal spills addresses spills 

that could occur prior to the oil arriving at the initial shoreline facility. It is also possible that non-OCS 

oil may be commingled with OCS oil at these facilities or during subsequent secondary transport. 

The coastal spill rate is based on historical spills and the projected amount of oil production. Because 

the majority of oil production from the CPA proposed action is projected to be brought to shore in eastern 

Louisiana, from Atchafalaya Bay to east of the Mississippi River, it is assumed the majority of coastal 

spills from the CPA proposed action will also occur in this area. 

Several USCG resources were used to estimate the number of coastal oil spills attributable to the 

proposed action, including the USCG Polluting Incident Compendium and data obtained directly from 

USCG. The Multisale EIS used a version of the Oil Spill Compendium containing data through 2000, 

and the 2009-2012 Supplemental EIS used a version of the Oil Spill Compendium containing data 

through 2004. At present, Polluting Incidents In and Around U.S. Waters, A Spill/Release Compendium: 

1969-2008 is available (U.S. Dept. of Homeland Security, CG, 2010a). The database available from 

USCG covers through 2008 as well. Figure 3-6 illustrates, for the year 2008, the location and size range 

of the spills in both coastal and offshore areas of the CPA. 

The number of GOM coastal spills from eight sources associated with State or Federal offshore 

production and international importation was determined. The sources that were counted are (1) fixed 

platforms, (2) mobile offshore drilling units, (3) offshore marine facilities, (4) offshore supply/service 

vessels, (5) offshore pipelines, (6) tank barges, (7) tank ships, and (8) unknown sources. In 2001, a total 

of 270 spills occurred in coastal GOM, of which roughly half were from the source types associated with 

State or Federal offshore oil production, oil importation, and unknown sources. All spills of unknown 

origin were counted as OCS in origin, which would not be the case in reality. Three billion barrels of 

total oil, including condensate, was transported to shore from Federal and State offshore production and 

by importation. Federal OCS production comprised 19 percent of the oil transported to the coast and, 
Impact-Producing Factors and Scenario 3-37 

therefore, is assumed to account for 19 percent of the spills. The amounts of various fuel oils transported 

for the purpose of consumption are not counted in this volume. Thus, the OCS production spill rate in 

coastal waters was determined to be in the range of 57-74 spills per billion barrels of oil. 

CPA Proposed Action Scenario: The volume of oil production projected has been updated 

(Table 3-1) to 0.801-1.624 BBO. Given an estimated spill rate of 57-74 spills per billion barrels of oil, it 

is estimated that 49-126 spills of OCS oil will occur in the CPA coastal area (Table 3-7). 

OCS Program Scenario: The OCS Program scenario remains the same as the originally forecasted 

program scenario in the Multisale EIS. Table 4-1 of the Multisale EIS shows the estimated range of the 

volume of oil production projected. 

3.2.1.4. Risk Analysis by Resource 

Chapter 4.3.1.8 of the Multisale EIS summarizes this Agency’s information on the risk to resources 

from oil spills and oil slicks that could occur as a result of a CPA proposed action. The risk results are 

based on BOEMRE’s estimates of likely spill locations, sources, sizes, frequency of occurrence, and 

probable transport. For offshore spills, the analysis presents combined probabilities, which include both 

the likelihood of a spill from the proposed action, as defined in the Multisale EIS, occurring and the 

likelihood of the oil slick reaching areas where known environmental resources occur. The analysis of 

the likelihood of direct exposure and interaction of a resource with an oil slick and the sensitivity of a 

resource to the oil is provided for environmental and socioeconomic resources in Chapter 4 of this 

Supplemental EIS. The coastal spill risk is estimated based on the historic spill rate.(Chapter 4.3.1.7.1 of 

the Multisale EIS). 

3.2.1.5. Spill Response 

3.2.1.5.1. BOEMRE Spill-Response Requirements and Initiatives 

As a result of the Oil Pollution Act of 1990, BOEMRE was tasked with a number of oil-spill-response 

duties and planning requirements. According to BOEMRE’s regulations at 30 CFR parts 250 and 254, 

BOEMRE implements these requirements as follows: 

 requires immediate notification for spills >1 bbl—all spills require notification to 

USCG and BOEMRE receives notification from the USCG of all spills 1 bbl; 

 conducts investigations to determine the cause of a spill; 

 assesses civil and criminal penalties, if needed; 

 oversees spill source control and abatement operations by industry; 

 sets requirements and reviews and approves oil-spill-response plans for offshore 

facilities; 

 conducts unannounced drills to ensure compliance with oil-spill-response plans; 

 requires operators to ensure that their spill-response operating and management 

teams receive appropriate spill-response training; 

 conducts inspections of oil-spill-response equipment; 

 requires industry to show financial responsibility to respond to possible spills; and 

 provides research leadership to improve the capabilities for detecting and responding 

to an oil spill in the marine environment. 

The BOEMRE also issued NTL’s and guidance documents that clarify additional oil-spill 

requirements after the DWH event occurred. Specifics of the DWH event are more fully described within 

Appendix D. The spill-response-related NTL’s and guidance documents issued by BOEMRE include the 

following NTL’s. 
3-38 Central Planning Area Supplemental EIS

NTL 2010-N10 “Statement of Compliance with Applicable Regulations and Evaluation of 

Information Demonstrating Adequate Spill Response and Well Containment Resources” 

This NTL, effective November 8, 2010, applies only to operators conducting operations using subsea 

or surface BOP’s on floating facilities. It explains that lessees and operators submit a statement signed by 

an authorized company official with each application for a well permit indicating that they will conduct 

all of their authorized activities in compliance with all applicable regulations, including the Increased 

Safety Measures Regulations at 75 FR 63346. The NTL also informs lessees that BOEMRE will be 

evaluating whether or not each operator has submitted adequate information demonstrating that it has 

access to and can deploy surface and subsea containment resources that would be adequate to promptly 

respond to a blowout or other loss of well control. The NTL notifies the operator that BOEMRE intends 

to evaluate the adequacy of each operator to comply in the operator’s current Oil Spill Response Plans 

(OSRP); therefore, there is an incentive for voluntary compliance. The NTL lists the type of information 

that BOEMRE will review as follows: 

 subsea containment and capture equipment, including containment domes and 

capping stacks; 

 subsea utility equipment, including hydraulic power, hydrate control, and dispersant 

injection equipment; 

 riser systems; 

 remotely operated vehicles; 

 capture vessels; 

 support vessels; and 

 storage facilities. 

NTL 2010-N06 “Information Requirements for Exploration Plans, Development and 

Production Plans, and Development Operations Coordination Documents on the OCS” 

This NTL, effective June 18, 2010, explains the procedures for the lessee or operator to submit 

supplemental information for new or previously submitted EP’s, DPP’s, or DOCD’s. The required 

supplemental information includes the following: (1) a description of the blowout scenario as required by 

30 CFR 250.213(g) and 250.243(h); (2) a description of their assumptions and calculations used in 

determining the volume of the worst-case discharge required by 30 CFR 250.219(a)(2)(iv) (for EP’s) or 

30 CFR 250.250(a)(2)(iv) (for DPP’s and DOCD’s); and (3) a description of the measures proposed that 

would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct 

effective and early intervention in the event of a blowout, including the arrangements for drilling relief 

wells and any other measures proposed. The early intervention methods of the third requirement could 

actually include the surface and subsea containment resources that BOEMRE announced in NTL 2010-

N10, which states that BOEMRE will begin reviewing to ensure that the measures are adequate to 

promptly respond to a blowout or other loss of well control. 

On December 13, 2010, BOEMRE issued a press release and a guidance document to provide a clear 

path forward for the safe resumption of deepwater drilling operations (USDOI, BOEMRE, 2010d). This 

guidance clarifies, in part, that although operators are not required to amend their OSRP’s to include 

additional subsea containment information, they may do so voluntarily. The guidance further indicates 

that BOEMRE will review for the following specific information relating to subsea containment, in 

addition to that listed in NTL 2010-N10: 

 source abatement through direct intervention; 

 relief wells; 

 debris removal; and 
Impact-Producing Factors and Scenario 3-39 

 if a capping stack is the single containment option offered, the operator must provide 

the reasons that the well design is sufficient to allow shut-in without broach to the 

seafloor. 

An operator can comply with this guidance by submitting a Containment Plan as part of their OSRP. 

In evaluating the sufficiency of subsea containment information submitted by an operator, BOEMRE will 

examine the Mudline Shut-in Pressure for the proposed well. The BOEMRE will also evaluate factors 

such as debris removal from the site. 

3.2.1.5.2. Offshore Response and Cleanup Technology 

In the event of a spill, particularly a loss of well control, there is no single method of containment and 

removal that would be 100 percent effective. Spill cleanup is a complex and evolving technology. There 

are many situations and environmental conditions that necessitate different approaches. New 

technologies constantly evolve, but they provide only incremental benefits. Each new tool then becomes 

part of the spill-response tool kit. Each spill-response technique/tool has its specific uses and benefits 

(Fingas, 1995). Removal and containment efforts to respond to an ongoing spill offshore would likely 

require multiple technologies, including source containment, mechanical cleanup, in-situ burning of the 

slick, and chemical dispersants (Table 3-8). Even with the deployment of all of these spill-response 

technologies, it is likely that, with the operating limitations of today’s spill-response technology, not all of 

the oil can be contained and removed offshore. 

Because no single spill-response method is 100 percent effective, it is likely that larger spills under 

the right conditions will require the simultaneous use of all available cleanup methods (i.e., source 

containment, mechanical cleanup, dispersant application, and in-situ burning). Accordingly, the response 

to the DWH event employed all of these options simultaneously. The cleanup technique chosen for a spill 

response will vary depending upon the unique aspects of each situation. The selected mix of 

countermeasures will depend upon the shoreline and natural resources that may be impacted; the size, 

location, and type of oil spilled; weather; and other variables. The overall objective of on-water recovery 

is to minimize the risk of impact by preventing the spread of free-floating oil. The physical and chemical 

properties of crude oil can greatly affect the effectiveness of containment and recovery equipment, 

dispersant application, and in-situ burning. It is expected that oil found in the majority of the proposed 

lease sale areas could range from medium weight oil to condensate. The variety of standard cleanup 

protocols that were used for removing DWH oil from beaches, shorelines, and offshore water are 

identified in Chapter 3.2.1.5.4.

Most oil-spill-response strategies and equipment are based upon the simple principle that oil floats. 

However, as evident during the DWH event, this is not always true. Sometimes it floats and sometimes it 

suspends within the water column or sinks to the seafloor. Oil suspended in the water column and 

moving with the currents is difficult to track, and therefore recover, using standard visual survey methods 

(Coastal Response Research Center, 2007). 

The National Commission on the British Petroleum (BP) Deepwater Horizon Oil Spill and Offshore 

Drilling’s staff working paper 7 (Oil Spill Commission, 2011a), entitled “Response/Clean-Up Technology 

Research & Development and the BP Deepwater Horizon Oil Spill,” has initially indicated that, since the 

Exxon Valdez spill occurred, both the industry and government have underfunded spill-response research 

and development and, as a result, cleanup technology used during the DWH event was outdated and 

inadequate. This draft report also makes the recommendation that the Commission consider the fact that 

future improvements in spill prevention and source containment should not replace the need to provide 

incentives and funding for spill-response research and development for slick containment and removal, in 

part, because an exclusive focus on prevention and subsea containment is not an in-depth defense to an oil 

spill and it would preclude a valuable redundancy in response capability. As a result of this report, the 

Commission is presently considering various measures that could serve to advance improvements in the 

present-day, spill-response technology (Oil Spill Commission, 2011a). 
3-40 Central Planning Area Supplemental EIS

Source Containment 

To address the new improved containment systems’ expectations to rapidly contain a spill as a result 

of a loss of well control from a subsea well addressed in NTL 2010 N-10, several oil and gas industry 

majors initiated the development of a new, rapid response system. This system is designed to fully 

contain oil flow in the event of a potential future underwater blowout and to address a variety of 

scenarios. The system would consist of specially designed equipment constructed, tested, and available 

for rapid response. It is envisioned that this system could be fully operational within days to weeks after a 

spill event occurs. The system is designed to operate in up to 10,000-ft (3,048-m) water depth and adds 

containment capability of 100,000 bbl of oil/day (4.2 million gallons/day). This new $1 billion 

investment can be expanded and adapted for new technologies. This equipment should be available by 

the end of 2011 or by early 2012. The companies that originated this system are forming a nonprofit 

organization, the Marine Well Containment Company (MWCC), to operate and maintain the system 

(MWCC, 2010a). The MWCC will provide fully trained crews to operate the system, will ensure the 

equipment is operational and ready for rapid response, and will conduct research on new containment 

technologies. At present, MWCC plans to offer this equipment to member companies and to rent it to 

nonmember companies. Until this equipment is available, industry has worked out a deal with BP to 

utilize the subsea containment equipment purpose built for the DWH event response (MWCC, 2010b). It 

is anticipated that this equipment will be available by early 2011. 

Another option for source control and containment is through the use of the equipment stockpiled by 

Helix Energy Solutions Group, Inc (Driver, 2010). The Helix initiative involves more than 20 smaller 

energy companies and supplements the MWCC response effort. Helix has stockpiled the equipment that 

it found useful in the DWH event response and is offering it to oil and gas producers for use. This system 

focuses on three vessels—the Helix Producer I, the Q4000, and the Express deepwater construction 

vessel, all of which played a role in the DWH event response and which continually work in the GOM. 

Together, the ships and related equipment can accommodate up to 55,000 bbl of oil/day, 70,000 bbl of 

liquid natural gas, and 95 MMcf of natural gas at depths up to 8,000 ft (2,438 m). In January 2011, the 

Helix system will provide only capping capability; however, cap and flow capability is supposed to be 

online by Spring 2011. 

Mechanical Cleanup 

Generally, mechanical containment and recovery is the primary oil-spill-response method used 

(33 CFR 153.305(a)). Mechanical recovery is the process of using booms and skimmers to pick up oil 

from the water surface. It is expected that the oil-spill-response equipment needed to respond to an 

offshore spill in the proposed CPA sale area could be called out from one or more of the following oilspill equipment base locations: Corpus Christi, Aransas Pass, Houston, La Porte, Ingleside, Port Arthur, 

and Galveston, Texas; Lake Charles, New Iberia, Belle Chase, Cameron, Cocodrie, Morgan City, New 

Orleans, Sulphur, Houma, Fourchon, Fort Jackson, and Venice, Louisiana; Pascagoula, Mississippi; 

Theodore and Mobile, Alabama; or Pensacola, Fort Lauderdale, Panama City, and Tampa, Florida. 

Response times for any of this equipment would vary, dependent on the location of the equipment, the 

staging area, and the spill site; and on the transport requirements for the type of equipment procured. It is 

anticipated that equipment would be procured from the closest available oil-spill equipment bases. 

In rough seas, a large spill of low viscosity oil, such as a light or medium crude oil, can be scattered 

over many square kilometers within just a few hours. Oil recovery systems typically have swath widths 

of only a few meters and move at slow speeds while recovering oil. Therefore, even if this equipment can 

become operational within a few hours, it would not be feasible for them to encounter more than a 

fraction of a widely spread slick (ITOPF, 2010b). For this reason, it is assumed that a maximum of 10-30 

percent of an oil spill in an offshore environment can be mechanically removed from the water prior to 

the spill making landfall (U.S. Congress, Office of Technology Assessment, 1990). Some newer oil 

skimming equipment procured internationally displayed faster recovery speed during the response to the 

DWH event, and some changes were also made in the logistics of how skimmers and booms were 

positioned offshore during this response that increased the equipment’s swath width. However, for the 

DWH event, it was estimated that only 3 percent of the total oil spilled was picked up by mechanical 

equipment offshore (Lubchenco et al., 2010). 
Impact-Producing Factors and Scenario 3-41 

A common difficulty when deploying booms and skimmers to recover oil is coordinating vessel 

activities to work the thickest areas of oil (ITOPF, 2010b). It is a rule of thumb that 90 percent of the oil 

is in 10 percent of the area. The 10 percent of the oil that makes up 90 percent of a slick is typically 

sheen. For this reason, containment and recovery operations on water require extensive logistical support 

to direct the response effort. Additionally, the limitations that poor weather and rough seas impose on 

spill-response operations offshore are seldom fully appreciated. Handling wet, oily, slippery equipment 

on vessels that are pitching and rolling is difficult and can raise safety considerations. Winds, wave 

action, and currents can drastically reduce the ability of a boom to contain and a skimmer to recover oil. 

It is important to select equipment for a response that is suitable for the type of oil and the prevailing 

weather and sea conditions for a region. Efforts should generally be made to target the heaviest oil 

concentrations and areas where collection and removal of the oil will reduce the likelihood of oil reaching 

sensitive resources and shorelines. As oil weathers and increases in viscosity, cleanup techniques and 

equipment should be reevaluated and modified (ITOPF, 2010b). 

Practical limitations of strength, water drag, and weight mean that generally only relatively short 

lengths of boom (tens to a few hundred meters) can be deployed and maintained in a working 

configuration. Towing booms at sea (e.g., in U or J configurations, which increase a skimmers swath 

width) is a difficult task requiring specialized vessels and trained personnel (ITOPF, 2010b). Additional 

boom limitations are discussed in Chapter 3.2.1.5.4. Because skimmers float on the water surface, they 

experience many of the operational difficulties that apply to booms, particularly those posed by wind, 

waves, and currents (ITOPF, 2010b). The effectiveness of any skimmer depends upon a number of 

factors, in addition to the ambient weather and sea conditions, including the type of oil, the thickness of 

the oil, the presence of debris in the oil or in the water, and the location of the spill (Fingas, 1995). Even 

moderate wave motion can greatly reduce the effectiveness of most skimmer designs (ITOPF, 2010b). In 

high sea-state conditions, many skimmers, especially weir and suction skimmers, take up more water than 

oil (Fingas, 1995). Because of the various constraints placed upon skimmers in the field, their design 

capacities are rarely realized. Experience from numerous spills has consistently shown that skimmer 

recovery rates reported under test conditions cannot be sustained during a spill response (ITOPF, 2010b). 

The availability of sufficient oil-storage facilities is necessary to ensure continuous oil-spill recovery. 

This storage needs to be easy to handle and easy to empty once full so that it can be used repeatedly with 

the least interruption in recovery activity (ITOPF, 2010b). 

There are no proven methods for the containment of submerged oil, and methods for recovery of 

submerged oils have limited effectiveness. Efforts to mechanically contain and/or recover suspended oil 

have focused on different types of nets, either the ad hoc use of fishing nets or specially designed trawl 

nets. There has been some research conducted on the design of trawl nets for the recovery of emulsified 

fuels. However, the overall effectiveness for large spills is expected to be very low. The suspended oil 

can occur as liquid droplets or semisolid masses in sizes ranging from millimeters to meters in diameter 

(Coastal Response Research Center, 2007). 

If an oil spill occurs during a storm, spill response from shore would occur following the storm. Spill 

response would not be possible while storm conditions continued, given the sea-state limitations for 

skimming vessels and containment boom deployment. However, oil released onto the ocean surface 

during a storm event would be subject to accelerated rates of weathering and dissolution (i.e., oil and 

water would be agitated, forcing oil into smaller droplets and facilitating dissolution of the high end 

aromatic compounds present). 

Dispersants 

When dispersants are applied to spilled crude oil, the surface tension of the oil is reduced, allowing 

wind and wave action to break the oil into tiny droplets that are dispersed into the upper portion of the 

water column. Oil that is chemically dispersed at the surface will move into the top 20 ft (6 m) of the 

water column where it will mix with surrounding waters and begin to biodegrade (U.S. Congress, Office 

of Technology Assessment, 1990, p. 19). Dispersant use, in combination with natural processes, breaks 

up the oil into smaller components that allows them to dissipate into the water and degrade more rapidly 

(Nalco, 2010). Dispersion increases the likelihood that the oil will be biodegraded, both in the water 

column and at the surface. While there is more analysis to be done to quantify the rate of biodegradation 

in the GOM after the DWH event, early observations and preliminary research results seemed to indicate 
3-42 Central Planning Area Supplemental EIS

that the oil biodegraded quickly; however, there are still ongoing studies assessing this issue. Bacteria 

that break down the dispersed and weathered surface oil are abundant in the GOM in large part because of 

the warm water, the favorable nutrient and oxygen levels, and the fact that oil enters the GOM through 

natural seeps regularly (Lubchenco et al., 2010). 

Dispersant use must be in accordance with the Regional Response Team’s (RRT) Preapproved 

Dispersant Use Manual and with any conditions outlined within a RRT’s site-specific, dispersant 

approval given after a spill event. Consequently, dispersant use would be in accordance with the 

restrictions for specific water depths, distances from shore, or monitoring requirements. At this time, this 

manual does not give preapproval for the application of dispersant use subsea. However, USEPA is 

presently revisiting these RRT preapprovals in light of the dispersant issues, such as subsea application, 

that arose during the DWH response. For a deepwater (>1,000 ft; >305 m water depth) spill 1,000 bbl, 

dispersant application may be a preferred response in the open-water environment to prevent oil from 

reaching a coastal area, in addition to mechanical response. However, the window of opportunity for 

successful dispersant application may be somewhat narrower for some deepwater locations that are 

dependent upon the physical and chemical properties of oil, which tend to be somewhat heavier than 

those found closer to shore. A significant reduction in the window of opportunity for dispersant 

application may render this response option ineffective. 

Based on the present location of dispersant stockpiles and dispersant application equipment in the 

GOM, it is expected that the dispersant application aircraft initially called out for an oil-spill response to 

an offshore spill in the proposed lease sale area will come from Houma, Louisiana; Stennis, Mississippi; 

or Coolidge, Arizona. The dispersants will come from locations primarily in Texas and Louisiana. 

Response times for this equipment would vary, depending on the spill site and on the transport time for 

additional supplies of dispersants to arrive at a staging location. Based on historic information, this 

Supplemental EIS assumes that dispersant application will be effective on 20-50 percent (S.L. Ross 

Environmental Research Ltd., 2000) of the treated oil. 

If an oil spill occurs during a storm, the dispersant application would occur following the storm. 

Aerial and vessel dispersant application would not be possible while storm conditions continued. 

However, oil released onto the ocean surface during a storm event would be subject to accelerated rates of 

weathering and dissolution (i.e., oil and water would be agitated, forcing oil into smaller droplets and 

facilitating dissolution of the high-end aromatic compounds present). 

In-situ Burning 

In-situ burning is an oil-spill cleanup technique that involves the controlled burning of the oil at or 

near a spill site. The use of this spill-response technique can provide the potential for the removal of large 

amounts of oil over an extensive area in less time than other techniques. In-situ burning involves the 

same oil collection process used in mechanical recovery, except instead of going into a skimmer, the oil is 

funneled into a fire boom, which is a specialized boom that has been constructed to withstand the high 

temperatures from burning oil. While in-situ burning is another method for disposing of oil that has been 

collected in a boom, this method is typically more effective than skimmers when the oil is highly 

concentrated. In-situ burning was successfully used in 411 burns during the DWH spill response, 

successfully eliminating between 220,000 and 300,000 bbl of oil from the water surface (Allen, 2010), 

approximately 5 percent of the Macondo oil spilled (Lubchenco et al., 2010). 

Response times for bringing a fire-resistant boom onsite would vary, depending on the location of the 

equipment, the staging area, and the spill site. If an oil spill occurs during a storm, in-situ burning would 

occur following the storm. In-situ burning would not be possible while storm conditions continued. 

Natural Dispersion 

Depending upon environmental conditions and spill size, the best response to a spill may be to allow 

the natural dispersion of a slick to occur. Natural dispersion may be a preferred option for smaller spills 

of lighter nonpersistent oils and condensates that form slicks that are too thin to be removed by 

conventional methods and that are expected to dissipate rapidly, particularly if there are no identified 

potential impacts to offshore resources and a potential for shoreline impact is not indicated. In addition, 

natural dispersion may also be a preferred option in some nearshore environments, such as a marsh 
Impact-Producing Factors and Scenario 3-43 

habitat, when the potential damage caused by a cleanup effort could cause more damage than the spill 

itself.

3.2.1.5.3. Oil-Spill-Response Assumptions Used in the Analysis of a Most Likely Spill 

1,000 bbl Incident Related to the Proposed Action 

Tables 4-36 and 4-37 and Chapter 4.3.5.3 of the Multisale EIS present the estimated amounts of oil 

that will either be removed by the application of dispersants or mechanically recovered for the 4,600-bbl 

pipeline spill scenarios analyzed in the Multisale EIS. The scenarios assumed oils of 30o

 and 35o API. 

3.2.1.5.4. Onshore Response and Cleanup 

Offshore response and cleanup is preferable to shoreline cleanup; however, if an oil slick reaches the 

coastline, it is expected that the specific shoreline cleanup countermeasures identified and prioritized in 

the appropriate Area Contingency Plans (ACP’s) for various habitat types would be used. The sensitivity 

of the contaminated shoreline is the most important factor in the development of cleanup 

recommendations. Shorelines of low productivity and biomass can withstand more intrusive cleanup 

methods such as pressure washing. Shorelines of high productivity and biomass are very sensitive to 

intrusive cleanup methods and, in many cases, the cleanup is more damaging than allowing natural 

recovery. 

Oil-spill-response planning in the U.S. is accomplished through a mandated set of interrelated plans. 

The ACP’s cover subregional geographic areas and represent the third tier of the National Response 

Planning System mandated by OPA. The ACP’s are a focal point of response planning, providing 

detailed information on response procedures, priorities, and appropriate countermeasures. The Gulf 

coastal area that falls within USCG District 8 is covered by the One Gulf Plan ACP, which includes 

separate Geographic Response Plans for areas covered by USCG Sector Corpus Christi, Sector Houston/

Galveston, Sector Port Arthur, Sector Morgan City, Sector New Orleans, and Sector Mobile. The Miami 

ACP covers the remaining Gulf coastal area. The ACP’s are written and maintained by Area Committees 

assembled from Federal, State, and local governmental agencies that have pollution response authority; 

nongovernmental participants may attend meetings and provide input. The coastal Area Committees are 

chaired by respective Federal On-Scene Coordinators from the appropriate USCG Office and are 

comprised of members from local or area-specific jurisdictions. Response procedures identified within an 

ACP or its Geographic Response Plan(s) reflect the priorities and procedures agreed to by members of the 

Area Committees. 

If an oil slick reaches the coastline, the responsible party will be required to use the specific shoreline 

cleanup countermeasures identified and prioritized for the various habitat types potentially impacted in 

the appropriate ACP’s that cover these areas. However, due to the lack of specific and detailed response 

information in the existing Gulf of Mexico ACP’s, the response to the DWH event required that separate, 

more detailed plans be developed for protection of these shoreline areas after much additional 

consultation between the Unified Command and local government agencies. The detailed plans 

developed during the DWH response are being incorporated into the geographic response plans as 

appropriate for the One Gulf Plan/ACP(s). 

The single, most-frequently recommended, spill-response strategy for the areas identified for 

protection in all of the applicable ACP’s or its Geographic Response Plans is the use of a shoreline boom 

to deflect oil away from coastal resources such as seagrass beds, marinas, resting areas for migratory 

birds, bird and turtle nesting areas, etc. Since oil spilled at sea tends to move and spread rapidly into very 

thin layers, boom is deployed to corral the oil on the water to enhance recovery effectiveness of skimmers 

and other response technologies. Boom is also used to protect shoreline areas and to minimize the 

consequences of an oil spill reaching shore. There are tradeoffs in deciding where and when to place 

boom because, once deployed, boom is time consuming to tend and to relocate. For example, booming 

operations are sensitive to wind, wave, and currents and need to be tethered and secured to keep them 

from moving. Rough seas can tear, capsize, or shred boom. Currents over 1.5 kn (1.7 mph) or even a 

wake from a boat can send oil over or under a boom. Untended boom can become a barricade to wildlife 

and to ship traffic. Boom anchors can damage some habitats. During the DWH event, it was discovered 
3-44 Central Planning Area Supplemental EIS

that hard boom often did more damage in the marsh it was intended to protect than anticipated after 

weather conditions ended up stranding the boom back into the marsh (USDOC, NOAA, 2010a). 

If a shoreline is oiled, the selection of the type of shoreline remediation to be used will depend on the 

following: (1) the type and amount of oil on the shore; (2) the nature of the affected coastline; (3) the 

depth of oil penetration into the sediments; (4) the accessibility and the ability of vehicles to travel along 

the shoreline; (5) the possible ecological damage of the treatment to the shoreline environment; (6) 

weather conditions; (7) the current state of the oil; and (8) jurisdictional considerations. To determine 

which cleanup method is most appropriate during a spill response, decisionmakers must asses the severity 

and nature of the injury using Shoreline Cleanup Assessment Team survey observations. These onsite 

decisionmakers must also estimate the time it will take for an area to recover in the absence of cleanup 

(typically considering short term to be 1-3 years, medium term to be 3-5 years, and long term greater than 

5 years (National Response Team, 2010). 

Shoreline Cleanup Countermeasures 

The following assumptions regarding the clean up of spills that contact coastal resources in the area 

of consideration reflect a generalization of the site-specific guidance provided in the ACP’s or its 

Geographic Response Plans applicable to the GOM. As stated in Chapter 4.3.1.4, it is expected that a 

typical oil spilled as a result of an accident associated with the CPA proposed action would be within the 

range of 30-35° API. Since the following discussion is intended to address the most likely spill scenario 

discussed in Chapter 3.2.1.5.3, cleanup countermeasures for medium-weight oil are all that are included 

in the following discussion. The ACP’s applicable to the Gulf coastal area cover a vast geographical area. 

The differences in the response priorities and procedures among the various ACP’s or its Geographic 

Response Plans reflect the differences in the identified resources needing spill protection in the area 

covered by each ACP or the Geographic Response Plans. 

 Barrier Island/Fine Sand Beaches Cleanup: After the oiling of a barrier island/fine 

sand beach with a medium-weight oil, applicable cleanup options are manual 

removal, trenching (recovery wells), sediment removal, cold-water deluge flooding, 

shore removal/replacement, and warm-water washing. Other possible shoreline 

countermeasures include low-pressure cold-water washing, burning, and nutrient 

enhancement. Responders are requested to avoid the following countermeasures: no 

action; passive collection (sorbents); high-pressure, cold-water washing; hot-water 

washing; slurry sand blasting; vacuum; and vegetation cutting. 

 Fresh or Salt Marsh Cleanup: In all cases, cleanup options that avoid causing 

additional damage to the marshes will be selected. After the oiling of a fresh or salt 

marsh with medium-weight oil, a preferred cleanup option would be to take no 

action. Another applicable alternative would be trenching (recovery wells). Shore 

removal/replacement, vegetation cutting, or nutrient enhancement could be used. 

The option of using vegetation cutting as a shoreline countermeasure will depend 

upon the time of the year and will be considered generally only if the re-oiling of 

birds is possible. Chemical treatment, burning, and bacterial addition are 

countermeasures under consideration. Responders are advised to avoid manual 

removal, passive collection, debris removal/heavy equipment, sediment removal, 

cold-water flooding, high- or low-pressure cold-water washing, warm-water washing, 

hot-water washing, slurry sand blasting, and shore removal/replacement. 

 Coarse Sand/Gravel Beaches Cleanup: After the oiling of coarse sand/gravel beach 

with medium-weight oil, applicable cleanup options are manual removal, trenching 

(recovery wells), sediment removal, cold-water deluge flooding, and shore removal/

replacement. Other possible shoreline countermeasures include low-pressure, coldwater washing; burning; warm-water washing; and nutrient enhancement. 

Responders are requested to avoid the following countermeasures: no action; passive 

collection (sorbents); high-pressure, cold-water washing; hot-water washing; slurry 

sand blasting; vacuum; and vegetation cutting. 
Impact-Producing Factors and Scenario 3-45 

 Exposed or Sheltered Tidal Flats Cleanup: After the oiling of an exposed or 

sheltered tidal flat with medium-weight oil, the preferred cleanup option is no action. 

Other applicable shoreline countermeasures for this resource include trenching 

(recovery wells) and cold-water deluge flooding. Other possible shoreline 

countermeasures listed include low-pressure, cold-water washing; vacuum; 

vegetation cutting; and nutrient enhancement. Responders are requested to avoid 

manual removal; passive collection; debris removal/heavy equipment; sediment 

removal; high-pressure, cold-water washing; warm-water washing; hot-water 

washing; slurry sand blasting; and shore removal replacement. 

 Seawall/Pier Cleanup: After the oiling of a seawall or pier with a medium-weight 

oil, the applicable cleanup options include manual removal; cold-water flooding; 

low- and high-pressure, cold-water washing; warm-water washing; hot-water 

washing; slurry sand blasting; vacuum; and shore removal replacement. Other 

possible shoreline countermeasures listed include burning and nutrient enhancement. 

Responders are requested to avoid no action, passive collection (sorbents), trenching, 

sediment removal, and vegetation cutting. 

3.2.2. Losses of Well Control 

The BOEMRE requires that all losses of well control be reported to BOEMRE. Effective July 17, 

2006, this Agency revised the regulations for loss of well control incident reporting, which were further 

clarified in NTL 2010-N05, “Increased Safety Measures for Energy Development on the OCS,” effective 

June 8, 2010. Operators are required to document any loss of well control event, even if temporary, and 

the cause of the event by mail or email to the addressee indicated in the NTL. The operator does not have 

to include kicks that were controlled but should include the release of fluids through a flow diverter (a 

conduit used to direct fluid flowing from a well away from the drilling rig). 

The current definition for loss of well control is as follows: 

 uncontrolled flow of formation or other fluids (the flow may be to an exposed 

formation [an underground blowout] or at the surface [a surface blowout]); 

 uncontrolled flow through a diverter; and/or 

 uncontrolled flow resulting from a failure of surface equipment or procedures. 

Not all loss of well control events result in blowouts; defined as any of the 3 loss of well control 

events above, but most commonly thought of as a release to the human environment. A loss of well 

control can occur during any phase of development, i.e., exploratory drilling, development drilling, well 

completion, production, or workover operations. A loss of well control can occur when improperly 

balanced well pressure results in sudden, uncontrolled releases of fluids from a wellhead or wellbore 

(PCCI Marine and Environmental Engineering, 1999; Neal Adams Firefighters, Inc., 1991). From 2006 

to 2009, of the 23 loss of well control events reported in the GOM, 6 (26%) resulted in loss of fluids at 

the surface or underground (USDOI, BOEMRE, 2010e). In addition to spills, the loss of well control can 

resuspend and disperse bottom sediments. Historically, since 1971, most OCS blowouts have resulted in 

the release of gas; blowouts resulting in the release of oil have been rare. 

The most recent blowout occurred on April 20, 2010, at the Macondo well in Mississippi Canyon 

Block 252 (DWH event) (Appendix D). Although this is statistically a rare event, the blowout resulted in 

the release of 4.9 million bbl of oil (Lubchenco et al., 2010) and large quantities of gas to the subsea 

environment. To date, a gas volume release for Macondo has not been officially calculated as a 

Government estimate, but BOEMRE has made an estimate of 15 Bcf of gas released by Macondo, in 

absence of any other attempt at quantifying the release (DeCort, personal communication, 2010). A 

multi-agency Government estimate for the oil released by Macondo was made by Lubchenco et al. (2010) 

in early August 2010 and has not been revised to date. 

Prior to the DWH event, two of the largest spills resulting from blowouts on the Gulf of Mexico OCS 

occurred in 1970, releasing 30,000 and 40,000 bbl of oil, respectively. Since 1970 there has been a total 
3-46 Central Planning Area Supplemental EIS

of 13 losses of well control events that have resulted in >50 bbl of oil being spilled. Most of these losses 

of well control were of short duration, more than one-half lasting less than a day (USDOI, BOEMRE, 

2010e). In contrast, the DWH event continued uncontained for 87 days, between April 20 and July 15, 

2010. 

As shown by the DWH event, the loss of well control in deep water has presented obstacles and 

challenges that would not be encountered during a loss of well control in shallow waters. Although many 

of the same techniques used for wild well control efforts in shallow water were used to attempt to control 

the Macondo well, these well control efforts were hindered by water depth, which required reliance solely 

upon the use of ROV’s for all well intervention efforts. This is a concern in deep water because the 

inability to quickly regain control of a well increases the size of a spill, as occurred during the DWH 

event. The DWH event required that the operator attempt well-control efforts at the seabed in very deep 

water depths (over 5,000 ft; 1,524 m), and after the explosions and fire that sunk the Deepwater Horizon, 

key personnel were missing who could have accessed surface switches to shut down the well if a 

functional BOP was installed. 

As indicated by Neal Adams Firefighters, Inc. (1991) and by the DWH event, there are several 

options that could be attempted to control a well blowout. Common kill techniques include (1) bridging, 

(2) capping/shut-in, (3) capping/diverting, (4) surface stinger, (5) vertical intervention, (6) offset kill, and 

(7) relief wells (Neal Adams Firefighters, Inc. 1991). Although much has been learned about well control 

in deep water as a result of the DWH event, if a deepwater subsea blowout occurs in the future, it is likely 

that an operator would be required to immediately begin to drill one or more relief wells to gain control of 

the well. This may be required whether or not this is the first choice for well control because the relief 

well is typically considered the ultimate final solution for regaining well control in such circumstances. 

Although it can take months, the actual amount of time required to drill the relief well depends upon 

the following: (1) depth of formation below mudline; (2) complexity of the intervention; (3) location of a 

suitable rig; (4) type of operation that must be terminated in order to release the rig (e.g., may need to 

complete a casing program before releasing the rig); and (5) any problems mobilizing personnel and 

equipment to the location. 

The major differences between a blowout during the drilling phase versus the completion or workover 

phases is the drilling well tendency to “bridge off.” Bridging is a phenomenon that occurs when severe 

pressure differentials are imposed at the well/reservoir interface and the formation around the wellbore 

collapses and seals the well. Deepwater reservoirs are susceptible to collapse under “high draw down” 

conditions. However, a completed well may not have the same tendency to passively bridge off as would 

a drilling well involving an uncased hole. Bridging would have a beneficial effect for spill control by 

slowing or stopping the flow of oil from the well (PCCI Marine and Environmental Engineering, 1999). 

There is a difference of opinion among blowout specialists regarding the likelihood of deepwater wells 

bridging naturally in a short period of time. Completed wells, or those in production, present more severe 

consequences in the event of a blowout due to the hole being fully cased down to the producing 

formation, which lowers the probability of bridging (PCCI Marine and Environmental Engineering, 

1999). Therefore, the potential for a well to bridge is greatly influenced by the phase of a well. See 

Chapter 3.2.1.5 for a discussion of planned well-source containment options that were designed to 

address an ongoing loss of well control event. 

In 2007, this Agency (Izon et al., 2007) looked at the occurrences of blowouts during a 15-year 

period. From 1992 to 2006, 39 blowouts occurred at a rate of one blowout for every 387 wells drilled. 

These numbers are down from the previous 15-year period where 87 blowouts occurred at a rate of one 

blowout for every 246 wells drilled. The majority of blowouts (84%) occurred at water depths <500 ft 

(152 m), which corresponds to where most of the wells in the GOM have been drilled. Forty-one percent 

of the blowouts lasted 1-7 days, and cementing problems were associated with 18 of the 39 blowouts. 

Flow diverters, which channel drilling fluid under normal circumstances but during a blowout would 

channel oil or gas, were used in 20 of the 39 blowouts with success reported in 16 out of 20. The 

occurrence of loss of well control events has improved over the last 25 years, and most loss of well 

control events are recoverable onsite and result in no environmental releases. Industry challenges remain 

as operators move into ultra-deepwater areas and seek deeper geologic prospects with little knowledge of 

the subsurface environment and with the use of new technologies in both familiar and unfamiliar 

environments. 
Impact-Producing Factors and Scenario 3-47 

Blowout Preventers 

A BOP is a device with a complex of choke lines and hydraulic rams mounted atop a wellhead 

designed to close the wellbore with a sharp horizontal motion that may cut through or pinch shut casing 

and sever tool strings. Depending on how it is configured, a BOP could weigh 250 tons and cost from 

$25 to $35 million, and higher. The BOP’s were invented in the early 1920’s and have been instrumental 

in ending dangerous, costly, and environmentally damaging oil gushers on land and in water. The BOP’s 

have been required for OCS oil and gas operations from the time offshore drilling began in the late 

1940’s. 

The BOP’s are actuated as a last resort upon imminent threat to the integrity of the well or the surface 

rig. For cased wells, the normal situation, the hydraulic ram may be closed if oil or gas from an 

underground zone enters the wellbore to destabilize it. By closing a BOP, usually by redundant surfaceoperated and hydraulic actuators, the drilling crew can prevent explosive pressure release and allow 

control of the well to be regained by balancing the pressure exerted by a column of drilling mud with 

formation fluids or gases from below. 

Surface BOP’s typically differ from subsea BOP’s by the reduced redundancy in the stack. This is in 

part due to the ease of maintenance and repair to the stack at the surface in comparison to the subsea 

BOP, which may have to be retrieved for these issues. As there are typically less components, the surface 

BOP stacks are lighter as a result. The differences in typical configuration between surface BOP’s and 

subsea BOP’s are shown below, from the top to the bottom of typical BOP stacks. 

Subsea BOP Surface BOP 

Upper Annular Preventer Annular Preventer 

Lower annular Preventer NE 

Blind Shear Ram NE 

Upper Pipe Ram Upper Pipe Ram 

Choke Valves Middle Pipe Ram 

Middle Pipe Ram Choke Valves 

Lower Pipe Ram Lower Pipe Ram 

Subsea Isolation Device NE 

NE = no equivalent 

Source: MCS Advanced Subsea Engineering (2010, Table 3.2). 

Both annular and shear rams are typically configured together in the subsea BOP stack to create 

redundancy. Because BOP’s are important for the safety of the drilling crew, as well as the rig and the 

wellbore itself, BOP’s are regularly inspected, tested, and refurbished. The post-DWH event regulations 

and inspection program required for BOP’s is discussed below and in Chapter 1.3.1. Among the changes 

are new provisions for BOP testing. 

The most important components of the BOP for regaining control of a wild well are rams. There are 

four types of rams: pipe ram; annular preventer; shear ram; and blind shear ram (MCS Advanced Subsea 

Engineering, 2010, pp. 17-20). 

Pipe Ram 

A pipe ram is an element that acts as a seal in the BOP. There are rams for high-pressure and lowpressure applications. Pipe rams were historically comprised of two half circles that were designed to 

seal around the drill pipe; however, there are newer styles of rams that are variable and that fit a range of 

pipe sizes. 

Annular Preventer 

The annular preventer is a component of the pressure control system in the BOP that is usually 

situated at the top of the stack. It is a device that can form a seal in the annular space around any object in 

the wellbore or upon itself, enabling well control operations to commence. A reinforced elastomer 

packing element is compressed by hydraulic pressure to affect the seal. 
3-48 Central Planning Area Supplemental EIS

Blind Ram and Blind Shear Ram 

A blind ram is used to seal an open hole when there are no tools or drill string in the bore. Blind 

shear rams have a cutting edge that is designed to shear drill string, casing, or production tubing that may 

be in the hole, allowing the blind rams to seal the hole. Blind rams are intended to seal against each other 

to effectively close the hole; they are not intended to seal against any drill pipe or casing. 

Subsea Isolation Device 

A subsea isolation device allows a well to be sealed below the BOP stack to allow the rig or drillship 

to move off location in case of an emergency disconnect situation, such as an approaching hurricane. 

Where there is the need to disconnect from the wellhead in a blowout or other well control situation, a 

subsea isolation device may be used. The subsea isolation device is placed at the mudline with riser and 

wellhead connectors set up to allow emergency disconnect if needed. The subsea isolation devices have 

different names depending on the operator and manufacturer. They can be called a subsea isolation 

device, environmental safety guard, surface disconnect system, or subsea shut-off device, just to name a 

few. The subsea isolation device is not designed for typical well control and is not considered a BOP. It 

is designed to seal the well and disconnect the riser from the seafloor if required, allowing safe well 

abandonment and the possibility to enter the well at a later point. The subsea isolation devices are 

typically activated with an acoustic trigger or from an ROV control panel. 

Choke Valves 

Choke valves are the means of controlling the BOP or subsea isolation device functions. They can 

either be fixed or adjustable. An adjustable valve has the advantage of allowing more control over fluid 

control parameters; however, under prolonged use, they may be more susceptible to erosion than fixed 

valves. 

This Agency’s role during the efforts to actuate the BOP after the sinking of the DWH event was 

evaluated in staff working paper 6 for the National Commission on the BP Deepwater Horizon Oil Spill 

and Offshore Drilling (Oil Spill Commission, 2011b, pp. 4-7). The staff’s evaluation described limited 

supervision by this Agency in the early spill containment effort, but it was in line with [this Agency’s] 

established role in overseeing deepwater drilling in general. The Commission staff attributed this 

Agency’s role to stem from a lack of resources and absence of important operational expertise (Oil Spill 

Commission, 2011b, pp. 7-8). 

Blowout Preventer Effectiveness 

The Technology Assessment & Research (TA&R) Program is a research element within BOEMRE’s 

Regulatory Program. The TA&R Program supports research associated with operational safety and 

pollution prevention, as well as oil-spill response and cleanup capabilities. The TA&R Program was 

established in the 1970’s to ensure that industry operations on the OCS incorporated the use of the best 

available and safest technologies, subsequently required through the 1978 OCSLA amendments and 

Energy Policy Act of 2005 (EPAct). The TA&R Program is comprised of three functional research 

activities: operational safety and engineering research; oil-spill-response research; and renewable energy 

research. There is no automatic connection between TA&R research outputs and changes to BOEMRE 

requirements. Management discretion is involved between the research outputs produced by TA&R and 

how or if they lead to a change in regulation. 

The studies carried out by this Agency on the effectiveness of BOP’s over the last 12 years have 

resulted in a mixed assessment of their effectiveness. An unavoidable condition involved in any BOP 

study to sample unit effectiveness is that a test is destructive for the casing or drill string components 

elected as representative and is also unique to the conditions under which the test was deployed. Tests 

should be as realistic as possible of in situ conditions and materials used. As a review of the TA&R 

studies that have been undertaken shows (below), this is not often the case. This Agency has never 

required destructive testing; such a program has not been proposed in recent BOEMRE, post-DWH 

regulations (Chapter 1.3.1). Routine destructive testing of equipment like a BOP may diminish its 

lifespan making such a test program costly. 
Impact-Producing Factors and Scenario 3-49 

Another train of assumption that underpins effectiveness testing would be (1) that other BOP units 

from a manufacturer are assumed to be representative of the same type and design, (2) that units are 

maintained according to specification, and (3) that all modifications or maintenance for BOP units 

available for deployment have been carried out under a system of design control and configuration 

management so that rig crews know that a properly maintained or modified unit is deployed, and so that if 

a crew has occasion to actuate a BOP in an emergency, they have access to accurate drawings for any 

modification that may have been made to it. For example, there were apparently modifications made to 

the Macondo BOP in a maintenance overhaul. The spill response engineers seeking to activate the BOP 

with ROV’s did not understand what modifications had been made and did not have accurate drawings of 

its modified configuration (Webb, 2010). 

Tetrahedron, Inc. (1996) conducted a study using data provided by the oil industry to determine BOP 

failure rates when tested at 7- and 14-day time intervals. The regulation 30 CFR 250.57 at that time 

required that a BOP must be tested when 

 installed; 

 before drilling each string of casing or before continuous operations in cases where 

the cement is not drilled out; and 

 at least once a week, but not exceeding 7 days between pressure tests, alternating 

between control stations. A period of more than 7 days between BOP tests is allowed 

when there is a stuck pipe or there are pressure control operations and remedial 

efforts are being performed, provided that the pressure tests are conducted as soon as 

possible and before normal operation resumes. 

When a unit is deployed on a well site and installed, BOEMRE requires a pressure-up and hold time 

test for the ram components without actually actuating the rams in the field. Tests succeed or fail on the 

ability for the system to hold specified pressures at intervals from 3 to 5 minutes. Tetrahedron, Inc. 

(1996) used the data to look at BOP component failures as well as failure rates between surface BOP’s 

and subsea BOP’s. For this study, a test of BOP failure was reported when any piece of equipment had to 

be physically repaired or sent to the shop for repairs for both initial and subsequent tests. Data was 

collected from 155 BOP (surface and subsea) tests, from which 63 were reported as failures (41%). 

When looking at surface versus subsea BOP’s, 22 out of 50 surface tests failed (44%) and 12 out of 56 

subsea tests failed (21%). 

As a result of this study, this Agency proposed a rule change to lengthen the pressure testing interval 

to not exceed 14 days (Federal Register, 1997b) and expanded on how testing was to be carried out for 

BOP’s in general. This Agency concluded that no statistical difference existed in failure rates for BOP’s 

tested between 0- to 7-day intervals and 8- to 14-day intervals (Federal Register, 1998, p. 29604). That is 

to say, the testing interval was not a controlling factor. This Agency, in effect, accepted that whether 

tested every 7 days or every 14 days, equivalent marginal test results were obtained. The rule was 

finalized (Federal Register, 1998), amending 30 CFR 250.406, 250.407, and 250.516 in line with the 

proposed changes to expand required BOP testing to the longer interval. 

Holand (1999) conducted a study on the reliability of subsea BOP’s for deepwater applications 

reported for 83 wells drilled in the years 1997 and 1998. He looked at the number of days the BOP’s 

were in service and the number of hours lost due to reported BOP failures. The failures were also 

classified as safety noncritical and safety critical. Safety noncritical failures are failures that occur on the 

rig during operation and testing of the BOP, whereas safety critical failures occur after testing and during 

a period in which the BOP is acting as a barrier. There were 117 BOP safety critical failures reported 

during 4,009 BOP service days, with a total of 3,637.5 hours lost. The failure rate for safety critical 

systems, the point at which the BOP was preventing a gas or fluid release, was 57 percent. The main 

cause of BOP failures were the ram preventers and the main control systems. 

Holand and Skalle (2001) conducted a study looking at BOP performance and deepwater kicks. This 

study ties back to the Holand (1999) study that reported 117 BOP failures for 83 wells drilled in the years 

1997 and 1998. There were 48 pressure kicks reported during the drilling of the 83 wells. There are 

various techniques used to suppress and equalize pressure kicks (kick-killing operations), and Holand and 

Skalle concluded that kick killing operations were a likely contributor to four of the BOP failures. 
3-50 Central Planning Area Supplemental EIS

West Engineering Services (2002) conducted a study on the shearing capability of the BOP shear ram 

based on results of fully actuated BOP’s from operator-provided effectiveness tests. Data was provided 

from seven rigs that conducted tests without hydrostatic pressure and from six rigs that tested with 

hydrostatic pressure. This study looked at both operational and nonoperational conditions. Five of seven 

tests passed (71%) the test without the hydrostatic pressure, but only three of six passed (50%) the test 

that accounted for increased hydrostatic pressure. The study acknowledged that different grades of casing 

were not tested. 

When shear tests are conducted, operational parameters, such as the increased hydrostatic pressure at 

deepwater depths or the complete range of casing steel or pipe thicknesses, are rarely factored in. If a 

BOP is actuated at a casing joint, the casing is greatly over thickened at that point. Barstow et al. (2010) 

reported that pipe joints can make up almost 10 percent of the drill pipe’s length. Should the shear ram be 

opposite the threading or upset (the thickening of the pipe to compensate for the threads that may be 

externally or internally expressed on the pipe wall) of a pipe joint, the ram would be trying to shear a pipe 

overthickened perhaps beyond its design specifications. However, if two rams are part of the BOP 

configuration, at least one ram is likely to be opposite pipe without a joint at all times. The BOP’s 

account for such a condition by using both pipe and annular rams at different levels in the BOP stack; the 

assumption being that redundant system would be failsafe. Double ram configurations, however, were 

not required by this Agency or by current post-DWH event BOEMRE regulations (Chapter 1.3.1). 

West Engineering Services (2004) conducted a study to evaluate if a rig’s BOP equipment could 

shear pipe to be used in a given drilling program at the most demanding condition to be expected. The 

study was prompted by the advances in drilling pipe metallurgy combined with larger and heavier pipe 

sizes used in deepwater drilling programs. West Engineering Services’ (2004, p. 3-1) evaluation followed 

their 2002 study that referred to the 2002 results as “a grim snapshot” of industry’s preparedness. West 

reported that the latest generation of high-ductility drilling pipe has been seen in some cases to double the 

shearing pressures required to sever the pipe compared with lower ductility pipe of the same weight, 

diameter, and grade through which only careful record keeping aboard the rig can determine which pipe is 

of what specification. West Engineering Services (2004) concluded that pressures that should be 

considered when predicting successful pipe shear often are not, such as net hydrostatic pressure at water 

depth (combined pressure effects of seawater, BOP hydraulic fluid, and drilling mud) and closing rams 

against the pressure in a wellbore kick. The following are among West Engineering Services’ 

recommendations: (1) design BOP stack for drilling programs using the worst-case information, such as 

maximum anticipated drilling pipe specifications, and compensatory pressures at depth acting to require a 

higher shear strength to separate pipe; (2) establish a maximum length for tool joints and upsets; (3) stop 

designating drill pipe weight per foot in favor of actual pipe wall thickness; (4) establish an industry-wide 

database of shear forces/pressures in materials tests carried out by prescribed procedure with prescribed 

test parameters and material test specifications; and (5) encouraging industry to share data, a role for this 

Agency. Part of the post-DWH event, spill regulatory changes for 30 CFR 250.416(e) is that third-party 

verification is required for all BOP’s that the blind-shear rams installed in the BOP stack are capable of 

shearing the drill pipe in the hole under maximum anticipated surface pressure. 

West Engineering Services (2006) conducted a study to assess the acceptability and safety of using 

equipment, particularly BOP’s and wellhead components, at pressures in excess of rated working 

pressure. Running equipment in excess of the maximum operating pressure is considered a poor practice 

and is rarely seen except for accidental or emergency use. If equipment is damaged during operation over 

maximum working pressure, the study implied that a downgrade would be a temporary remedy until the 

system is removed from service or until repaired. 

Melendez et al. (2006) wrote his Master’s Thesis at Texas A&M on the risk assessment of surface 

versus subsea BOP’s on MODU’s. Melendez et al. determined that the reliability of the surface BOP 

system compared with the subsea BOP system was nearly equal. This was the case even as the subsea 

BOP system used more redundant components than the surface BOP system. Melendez et al. (2006) also 

determined that the addition of a subsea isolation device improved the system reliability and 

recommended subsea isolation devices be used for deepwater operations in the GOM. 

MCS Advanced Subsea Engineering (2010) conducted a risk analysis on the use of surface BOP’s. 

MCS Advanced Subsea Engineering concluded that a surface BOP carries more potential risk to the 

vessel and personnel, but it may not increase the overall risk of the operation. Although the BOP is closer 

to the vessel and allows easy access by rig personnel, the crew exposure time during a wild well condition 
Impact-Producing Factors and Scenario 3-51 

is lessened because of a simpler and cleaner kill operation at the surface. Proper inspections and 

maintenance is critical because the BOP is the only barrier between the vessel and personnel during a 

catastrophic blowout condition. 

Conclusions 

Izon et al. (2007) indicate that approximately 10 percent of all wells drilled experienced some loss of 

well control incidents over the years 1992-2006, an improvement from 35 percent in the previous 15-year 

period. Most loss of well control events are recoverable and result in no environmental releases. 

Despite a mixed assessment of BOP effectiveness over the last 12 years, this Agency has made no 

changes in regulation for BOP’s in the face of such ambiguous results. The need for redundant well 

control systems was recognized and judged desirable in TA&R studies. The TA&R studies conclude that 

the failure rate for surface BOP’s was worse than for subsea BOP’s (Tetrahedron, Inc., 1996) but that 

both types of units approached 50 percent failure rates in effectiveness studies. No TA&R study was 

carried out under strictly controlled conditions that simultaneously accounted for different BOP ram 

types, rig mount locations, the metallurgy and thickness of casing steel, or deepwater pressure and 

temperature conditions. 

The new post-DWH event safety requirements put in place on October 14, 2010 (Federal Register, 

2010b), included several added regulations to improve the safety of well control systems (Chapter 1.3.1). 

These regulations include the following: (1) seafloor function testing of ROV intervention and deadman 

systems—30 CFR 250.516(d), 30 CFR 250.616(h), and 30 CFR 250.449(j) and (k); (2) third-party 

certification that the shear rams will shear drill pipe under maximum anticipated pressure—30 CFR 

250.416(e); (3) registered professional engineer certification that the well design is appropriate for 

expected wellbore conditions—30 CFR 250.420(a); (4) use of dual mechanical barriers for the final 

casing string—30 CFR 250.420(b); (5) negative pressure testing of individual casing strings—30 CFR 

250.423(c); and (5) retrieval and testing of BOP after a shear ram has been activated in a well control 

situation—30 CFR 250.451(i). 

The BOEMRE released NTL 2010-N10, “Statement of Compliance with Applicable Regulations and 

Evaluation of Information Demonstrating Adequate Spill Response and Well Containment Resources,” 

effective November 8, 2010, to address the use of BOP’s and well containment resources in the aftermath 

of the DWH event. The NTL only applies to operators using BOP’s subsea or at the surface on floating 

facilities. It explains that lessees and operators submit a statement signed by an authorized company 

official with each application for a well permit, indicating that they will conduct all of their authorized 

activities in compliance with all applicable regulations, including the Increased Safety Measures 

Regulations (Federal Register, 2010b). The NTL also informs lessees that BOEMRE will be evaluating 

whether or not each operator has submitted adequate information demonstrating that it has access to and 

can deploy surface and subsea containment resources that would be adequate to promptly respond to a 

blowout or other loss of well control. The NTL does not require that operators submit revised OSRP’s 

that include this containment information at this time, the operator was notified of BOEMRE’s intention 

to evaluate the adequacy of each operator’s capability to comply in the operator’s current OSRP; 

therefore, there is an incentive for voluntary compliance. The type of information that BOEMRE will 

review pursuant to this NTL includes, but is not limited to, 

 subsea containment and capture equipment, including containment domes and 

capping stacks; 

 subsea utility equipment, including hydraulic power, hydrate control, and dispersant 

injection equipment; 

 riser systems; 

 remotely operated vehicles; 

 capture vessels; 

 support vessels; and 

 storage facilities. 
3-52 Central Planning Area Supplemental EIS

3.2.3. Pipeline Failures 

Significant sources of damages to OCS pipeline infrastructure are mass sediment movements and 

mudslides that can exhume or push the pipelines into another location, impacts from anchor drops or boat 

collisions, and accidental excavation or breaching because the exact whereabouts for a pipeline is 

uncertain. 

The uncertain location of pipelines is an ongoing safety and environmental hazard. On October 23, 

1996, in Tiger Pass, a channel through the Mississippi River Delta into the Gulf of Mexico near Venice, 

Louisiana, the crew of the Bean Horizon Corporation dredge Dave Blackburn dropped a stern spud (a 

large steel shaft that is dropped into the river bottom to serve as an anchor and a pivot during dredging 

operations) into the bottom of the channel in preparation for continued dredging operations. The spud 

struck and ruptured a 12-in diameter, submerged natural gas steel pipeline owned by Tennessee Gas 

Pipeline Company. The pressurized natural gas (about 930 psig) released from the pipeline enveloped the 

stern of the dredge and an accompanying tug, the G.C. Linsmier. Within seconds of reaching the surface, 

the natural gas ignited. The resulting fire destroyed the dredge and the tug. Twenty-eight crew members 

from the dredge vessel and tug boat abandoned ship or boarded nearby vessels (USDOT, National 

Transportation Safety Board, 1998). A description of the incident in a National Transportation and Safety 

Board safety recommendation (USDOT, National Transportation Safety Board, 1998) indicates that lack 

of awareness of the precise location of the pipeline was a major contributing factor to this accident. 

On December 5, 2003, this Agency received an incident report that a cutterhead dredge barge 

ruptured a 20-in diameter condensate pipeline in Eugene Island Block 39. Dredging operations by COE 

were taking place in Atchafalaya Channel. No injuries were reported, but a small condensate spill and 

subsequent fire damaged the dredge barge. The incident was apparently caused by inaccurate knowledge 

of the pipeline’s location. The global positioning system beacon was located on the barge tug rather than 

on the bow of the dredge barge where the suction cutterhead operated. Therefore, the true position of the 

pipeline relative to the suction cutterhead was in error by at least the length of the dredge barge (about 

400 ft; 121 m). Lack of awareness of the precise location of the pipeline was the major contributing 

factor to this accident as well. 

Following the 2004, 2005, and 2008 hurricane seasons, this Agency commissioned studies to examine 

the failure mechanisms of offshore pipelines (Atkins et al., 2007; Energo Engineering 2010; Atkins et al., 

2006). Table 3-9 shows pipelines damaged after the 2004-2008 hurricanes passing through the CPA and 

WPA. Much of the reported damage is riser or platform-associated damage, which typically occurs when 

a platform is toppled or otherwise damaged. 

Table 3-10 shows the hurricane-associated spills from pipelines >50 bbl. The largest spills are 

typically due to pipeline movements, mudslides, anchor drops, and collisions of one type or another. 

Most pipeline damage occurs in shallow (<200 ft; 61 m) water because of the potential for increasing 

impacts of the storm on the seabed in shallow water, the relative density of pipelines, or the age and 

design standards of the pipeline or the platforms to which the pipelines are connected. 

The future impact of hurricanes on damage to pipelines is uncertain. As oil production shifts from 

shallow to deeper water, there may be a consolidation of pipeline utilization that increases the risk of a 

large spill, but might allow a focus on the safety of a smaller number of critical pipelines. 

An OCS-related spill 1,000 bbl would likely be from a pipeline accident for OCS coastal spills 

1,000 bbl; where a spill size of 4,200 bbl is assumed. An OCS-related spill in coastal waters of 1,000 

bbl and related to the proposed activity will occur less than once per year; about once every 6 years. 

3.2.4. Vessel Collisions 

Chapter 4.3.3 of the Multisale EIS and Chapter 3.2.2 of the 2009-2012 Supplemental EIS describes 

the impacting factors arising from vessel collisions in the GOM resulting from a proposed action. The 

discussion in this Supplemental EIS tiers from the discussion in the Multisale EIS and the 2009-2012 

Supplemental EIS. 

This Agency revised operator incident reporting requirements in a final rule effective July 17, 2006 

(Federal Register, 2006b). The new incident reporting rule more clearly defines what incidents must be 

reported, broadens the scope to include incidents that have the potential to be serious, and requires the 

reporting of standard information for both oral and written reports. As part of the incident reporting rule, 
Impact-Producing Factors and Scenario 3-53 

this Agency’s regulations at 30 CFR 250.188(a)(6) requires an operator to report all collisions that result 

in property or equipment damage greater than $25,000. “Collision” is defined as 

 the act of a moving vessel (including an aircraft) striking another vessel, or striking a 

stationary vessel or object (e.g., a boat striking a drilling rig or platform); and 

 all collisions that result in property or equipment damage greater than $25,000 must 

be reported. 

This Agency’s data show that, from 1996 to 2009, there were 226 OCS-related collisions. Most 

collision mishaps are the result of service vessels colliding with platforms or vessel collisions with 

pipeline risers. Approximately 10 percent of vessel collisions with platforms in the OCS caused diesel 

spills. Fires resulted from hydrocarbon releases in several of the collision incidents. To date, the largest 

diesel spill associated with a collision occurred in 1979 when an anchor-handling boat collided with a 

drilling platform in the Main Pass leasing area, spilling 1,500 bbl. Diesel fuel is the product most 

frequently spilled while oil, natural gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been 

released as the result of a vessel collision. Human error accounts for approximately half of all reported 

vessel collisions from 2006 to 2009. 

Safety fairways, traffic separation schemes, and anchorages are the most effective means of 

preventing vessel collisions with OCS structures. In addition, OCS-related vessels could collide with 

marine mammals, turtles, and other marine animals during transit. To limit or prevent such collisions, 

NOAA Fisheries provides all boat operators with “Whale-watching Guidelines,” which is derived from 

the Marine Mammal Protection Act. These guidelines suggest safe navigational practices based on speed 

and distance limitations when encountering marine mammals. The frequency of vessel collisions with 

marine mammals, turtles, or other marine animals may vary as a function of spatial and temporal 

distribution patterns of the living resources, the pathways of maritime traffic (coastal traffic is more 

predictable than offshore traffic), and as a function of vessel speed, the number of vessel trips, and the 

navigational visibility. 

3.2.5. Chemical and Drilling-Fluid Spills 

Chapter 4.3.4 of the Multisale EIS and Chapter 3.2.4 of the 2009-2012 Supplemental EIS describe the 

impacting factors arising from chemical and drilling fluid spills in the GOM resulting from a proposed 

action. The discussion in this Supplemental EIS tiers from the discussion in the Multisale EIS and the 

2009-2012 Supplemental EIS. 

The USCG’s size categories for coastal and offshore waters and are based solely on spill volume. 

Minor Medium Major 

<238 bbl (<10,000 gal) 238-2,380 bbl (10,00-99,999 gal) ≥2,381 bbl (100,000 gal) 

1 bbl = 42 U.S. gallons. 

Chemical Spills 

Chemicals are stored and used to condition drill muds and during production and in well completions, 

stimulation, and workover procedures. The relative quantity of their use is reflected in the largest 

volumes spilled. Completion fluids are the largest quantity used and are largest releases. Between 5 and 

15 chemical spills are anticipated each year, with the majority being <50 bbl in size. The most common 

chemicals spilled are methanol, ethylene glycol, and zinc bromide. Additional production chemicals are 

needed in deepwater operations where gas hydrates tend to form. Spill volumes are anticipated to remain 

about the same, but spill frequency can be expected to improve because of advances in subsea processing. 

Spills of chemicals were within the range considered normal in 2006 and 2007. Hurricanes Gustav 

and Ike in 2008 caused an increase in the number of chemical spills. In 2008, there were 32 chemical 

spills; 22 of those spills occurred because of Hurricane Ike on September 13, 2008. The largest spill was 

a 713-bbl spill of calcium chloride brine (USDOI, BOEMRE, 2010f). 
3-54 Central Planning Area Supplemental EIS

Synthetic-based Fluid Spills 

Synthetic-based fluids (SBF’s) have been used since the mid 1990’s. In deepwater drilling, syntheticbased muds (SBM’s) can be preferred over petroleum oil-based muds (OBM’s) because of the SBM’s 

superior performance properties. The synthetic oils used in SBM’s are relatively nontoxic to the marine 

environment and have the potential to biodegrade (USEPA, 2000a). Three SBF spills of 1,000 bbl 

occurred between 2001 and 2004. Between 5 and 20 SBF releases are anticipated each year, with the 

majority being <50 bbl in size. The volume of the synthetic portion of the drill fluid rather than the total 

volume of the drill fluid is now used to describe spill size. Accidental riser disconnects could result in the 

release of large quantities of drilling fluids and are of particular concern when SBF’s are in use. The 

study report, Environmental Impacts of Synthetic-Based Drilling Fluids (Neff et al., 2000), described in 

the 2009-2012 Supplemental EIS, was initiated, but suffered a major equipment malfunction. Because 

the frequency of these spills has been decreasing, additional funding was not applied to continue this 

study. 

In 2007, a SBF spill of 1,061 bbl occurred in Green Canyon Block 726. A crack in a joint on the riser 

was the cause of the spill (USDOI, BOEMRE, 2010f). In 2008, an SBF spill of 1,718 bbl occurred in 

Mississippi Canyon Block 941 because of a valve not closing properly (USDOI, BOEMRE, 2010g). 

3.3. CUMULATIVE ACTIVITIES SCENARIO

The cumulative impact of a proposed action under 40 CFR 1508.7 is defined as “the impact on the 

environment which results from the incremental impact of the action when added to other past, present, 

and reasonably foreseeable future actions regardless of what agency (Federal or non-Federal) or persons 

undertake such acts.” A cumulative impacts analysis considers the resources and impact-producing 

factors that are part of the proposed action and OCS Program; however, it also requires (1) identification 

of other activities affecting the resources, ecosystems, and human environment other than the proposed 

actions, (2) establishment of the geographic scope for the analysis, and (3) establishment of the timeframe 

for the analysis. 

The activities, or factors, producing impacts that are part of the CPA proposed action and that are also 

part of the cumulative activities scenario are described in Chapters 3.1 and 3.2. 

Some affected resources susceptible to impacts from the proposed action described in Chapters 4.1

also represent activities that are part of this cumulative scenario. Some of these resources are commercial 

fishing, recreational fishing, recreational resources, and human resources and land use. 

Activities that are part of the cumulative activities scenario, but that are not part of the proposed 

action, include both human-induced and natural phenomena. Some of these activities are as follows: 

 State Oil and Gas Activity 

 Texas 

 Louisiana 

 State pipeline infrastructure 

 Other Major Factors Influencing Offshore Environments 

 dredge material disposal 

 OCS sand borrowing 

 marine transportation 

 military activities 

 artificial reefs and rigs-to-reefs development 

 offshore liquefied natural gas projects and deepwater ports 

 development of gas hydrates 

 renewable energy and alternative use 

 Other Major Factors Influencing Coastal Environments 

 sea-level rise and subsidence 

 formation extraction and subsidence 
Impact-Producing Factors and Scenario 3-55 

 Mississippi River hydromodification 

 maintenance dredging and navigation channels 

 coastal restoration programs 

 Coastal Impact Assistance Program 

 Gulf Coast Ecosystem Restoration Task Force 

 Natural Events or Processes 

 hurricanes 

 currents as transport agents 

The timeframe for the analysis first requires definition of a point from which measurements begin 

(baseline) and a point to which the future effects will be analyzed. The baseline for impact-producing 

factors for this cumulative analysis is 2010 and the 40 years leading up to it, and the future limit is the 

next 40 years. The 40-year time period is selected because it is the approximate longest life span of 

activities conducted on an individual lease. Therefore, the next 40 years is the period of time during 

which the activities and impacting factors that follow as a consequence of proposed CPA Lease 

Sale 216/222 would be influencing the environment. This analysis of cumulative effects is activity based; 

i.e., it focuses on the aggregate effects of the past activities that have taken place within the geographic 

area of the CPA without itemizing the historical details of each individual past action. 

The geographic scope for the analysis ultimately lies within the area where impacts can be identified, 

but as a general concept are defined as the CPA out to the EEZ and landward to the border of each State’s 

coastal zone, but will vary depending on the resource. The proposed action takes place within an area of 

the Gulf of Mexico where current competition for OCS space is moderately intense. Competition for 

OCS space in the CPA is not expected to become any more intense during the next 40 years of the 

cumulative activities scenario, and possibly it may become slightly less intense as oil and gas production 

ramps down as a result of reservoir depletion. 

Space-Use Conflict Intensity 

Of the activities included in the cumulative activities scenario, most of them involve temporary and 

exclusive use of relatively small areas of the OCS over their lifetimes. Lifetimes for these activities can 

be days or decades, but few of them permanently or temporarily compete directly for large areas of OCS 

on a semi-continuous basis. Exceptions include (1) commercial fishing, (2) military uses, and (3) marine 

transportation activities. All of these activities spatially coexist with OCS Program activities but differ in 

their potential for space-use conflict by their degree of permanence or frequency. 

Commercial fishing is a semi-permanent, space-use conflict for the OCS. Essentially, commercial 

fishing can potentially occur anywhere OCS infrastructure does not present an obstruction. Virtually all 

commercial trawl fishing in the GOM is performed in water depths less than 200 m (656 ft). Ninety-three 

to 95 percent of the 2,128-2,340 production structures projected to be installed in the CPA between the 

years 2007 and 2046 are project to be in water depths 200 m (656 ft) (Table 4-6 of the Multisale EIS). 

Assuming all structures are major production structures that each displace approximately 6 ha (15 ac) of 

OCS space without safety zones, between 12,768 and 14,040 ha (31,550 and 34,693 ac) of OCS area 

would be displaced over 40 years (page 4-359 of the Multisale EIS); less than 1 percent of OCS area 

would be converted to temporary, but dedicated, OCS use and would not be available to trawl fishing. 

Military activities are temporary space-use conflicts for the OCS. The CPA includes all or part of the 

following Eglin Water Test Areas: EWTA-1, EWTA-3, and EWTA-5; and all or part of the following 

military warning areas: W-59, W-92, W-156, and W-453. The proposed Military Areas Stipulation 

would reduce potential impacts, particularly in regards to safety, but military and OCS activities 

essentially coexist except under prearranged circumstances. The reduction in potential impacts resulting 

from this stipulation makes multiple-use conflicts most unlikely, but without it some potential conflict 

with respect to safety issues is likely. The best indicator of the overall effectiveness of the stipulation 

may be that there has never been an accident involving a conflict between military operations and oil and 

gas activities in the GOM. 

Marine transportation is a transitory but persistent space-use conflict over the OCS. Commercial 

vessels can range across the entire GOM, but higher traffic areas are generally self-restricted to transit 
3-56 Central Planning Area Supplemental EIS

corridors. The Gulf Intracoastal Waterway is a designated transit corridor with speed controls where it 

crosses open navigable GOM waters. The USCG has not yet determined a navigational safety zone 

during offloading operations for FPSO facilities. Other deepwater facilities may require up to a 500-m 

(1,640-ft) radius safety zone or 78 ha (193 ac) of space (USCG regulations, 33 CFR Chapter 1, Part 

147.15). Otherwise the USCG or BOEMRE have no officially designated safety zones requiring activity 

set-backs from OCS facilities, although 500 m (1,640 ft) is a generally recognized safety buffer set-back 

from floating structures. 

3.3.1. OCS Program 

Chapter 4.1 of the Multisale EIS and Chapter 3.1 and 3.2 of the 2009-2012 Supplemental EIS 

describe the scenario from a proposed action and future OCS lease sales (OCS Program). Chapters 3.1 

and 3.2 of this Supplemental EIS describe the impacting factors and scenario for routine and accidental 

events, respectively, for the proposed action in this Supplemental EIS and future OCS lease sales (OCS 

Program). 

The OCS Program scenario includes all activities that are projected to occur from past, proposed, and 

future lease sales during the 40-year activity period. Projected reserve/resource production for the OCS 

Program is from 28.562 to 32.570 BBO and from 142.366 to 162.722 Tcf of gas. Tables 4-4, 4-5, and 4-6 

of the Multisale EIS present projections of the major activities and impact-producing factors related to 

future Gulfwide OCS Program activities. Projected new coastal infrastructure as a result of the OCS 

Program is shown in Table 4-9 of the Multisale EIS. 

For this Supplemental EIS, the BOEMRE, Gulf of Mexico OCS Region, Resource and Evaluation 

Office’s Modeling and Forecasting Team has reevaluated the exploration and development activity 

scenario for the OCS Program that was presented in the Multisale EIS and 2009-2012 Supplemental EIS. 

For purposes of the cumulative activities scenario for this Supplemental EIS, the judgment was made that 

the scenario published in the Multisale EIS and the 2009-2012 Supplemental EIS remain valid. 

The level of OCS activity is connected to oil prices, resource potential, cost of development, and rig 

availability rather than just, or even primarily to, the amount of acreage leased. In addition to these 

historically recurrent factors, the effect of new regulations for OCS activity enacted after the DWH event 

(Chapter 1.3.1) have been taken into account for estimates of future activity. The impacts of activities 

associated with the OCS Program on biological, physical, and socioeconomic resources are analyzed in 

the cumulative impacts analysis sections of Chapter 4.1. 

3.3.2. State Oil and Gas Activity 

Chapter 4.1.3.1 of the Multisale EIS and Chapter 3.3.2 of the 2009-2012 Supplemental EIS discuss 

the activities involving State oil and gas exploration and development programs. All of the five Gulf 

Coast States have had some historical oil and gas exploration activity, and with the exception of Florida 

and Mississippi, all currently produce oil and gas in State waters. The coastal infrastructure that supports 

the OCS Program also supports State oil and gas activities. 

State oil and gas infrastructure consists of the wells that extract hydrocarbon resources, facilities that 

produce and treat the raw product, pipelines that transport the product to refineries and gas plants for 

further processing, and additional pipelines that transport finished product to points of storage and final 

consumption. The type and size of infrastructure that supports production depends upon the size, type, 

and location of the producing field, the time of development, and the life cycle stage of operations. 

Louisiana 

Louisiana has been the second most important oil- and gas-producing state after Alaska. Oil 

production in Louisiana began in 1902, with the first oil production in the coastal zone in 1926. The State 

of Louisiana issued its first offshore oil and gas lease in 1936, and in 1937 the Pure Oil Company 

discovered the first Louisiana oil field 1.2 mi (1.9 km) offshore of Cameron Parish using a platform built 

on timber pilings in water 15 ft (4.6 m) deep. Most oil is produced in southern Louisiana and most gas is 

produced in northern Louisiana. 

The nine contiguous parishes of the coastal zone produced more than 50 percent of the State’s oil 

during the 1950’s. Oil production peaked at 513 million bbl in 1970 and gas production peaked at 
Impact-Producing Factors and Scenario 3-57 

7.8 MMcf in 1969 (Ko and Day, 2004a, p. 398). For the nine contiguous coastal zone parishes in 2009, 

the Louisiana Dept. of Natural Resources’ SONRIS lite database (Louisiana Dept. of Natural Resources, 

2010) showed a total of 4,266 producing wells, 43 million bbl of oil production, and 0.43 MMcf of gas 

production (Table 3-11). 

Louisiana’s leasing procedure is carried out by the Petroleum Lands Division of the Office of Mineral 

Resources and proceeds along the following procedural steps (McKeithen, 2007): (1) industry nominates 

acreage for leasing every month (By law, nominated tracts cannot exceed 5,000 ac [2,023 ha], but by 

Mineral Board policy, the size limit of a nominated tract is further limited to only 2,500 ac [1,012 ha]); 

(2) the nominated tracts are then advertised in official State and parish journals; (3) competitive, sealed 

bidding then takes place on bonus, royalty, and rental to be received by the State (The sealed bids are 

opened and read into the record at a public meeting of the Louisiana Mineral Board at the time and place 

advertised.); and (4) if it determines that the bids are sufficient, the Louisiana Mineral Board awards the 

leases to the highest bidder after evaluating data provided from the staff geologists from the Geology and 

Engineering Division of the Office of Mineral Resources. The term of the lease is limited to 3 years for 

inland tracts and 5 years for offshore tracts. 

The most recent oil and gas lease sale occurred on April 14, 2010. Sixty-three (63) parcels containing 

19,386 ac (7,845 ha) of State lands were offered for oil and gas leasing by the Office of Mineral 

Resources on behalf of the State Mineral Board for Louisiana (Digital Petrodata, 2010). The number of 

acres offshore was unspecified. The BOEMRE expects that Louisiana will conduct regular oil and gas 

lease sales during the 40-year cumulative activities scenario for OCS activity, although their regularity 

could differ from current practices. 

Mississippi 

Mississippi has only an onshore oil and gas leasing program and does not issue leases for offshore 

activity in State waters. The BOEMRE does not expect Mississippi to institute a lease sale program in the 

near future, although there is at least a possibility for a change in policy with respect to leasing in State 

waters during the 40-year cumulative activities scenario for OCS activity following the CPA proposed 

action. 

Alabama 

The first oil test in offshore Alabama was made in Mobile Bay in 1951. The first discovery in State 

waters offshore Alabama was made in 1979. By 2005, a total of 80 wells were drilled in State waters. 

Production, mostly gas, in Alabama waters provided 154 MMcf per year, which is half the State’s 

production (Wikipedia, 2010). Since 1980, the number of producing wells increased from 1,000 to nearly 

6,000 in 2005. Over $2.4 billion worth of oil and gas are produced annually in Alabama. In 2008, there 

were 384 fields in Alabama with 6,710 producing wells. 

Alabama has no established schedule of lease sales. The limited number of tracts in State waters has 

resulted in the State not holding regularly scheduled lease sales. The last lease sale was held in 1997. 

The BOEMRE does not expect Alabama to institute a lease sale program in the near future, although there 

is at least a possibility of a lease sale in State waters during the 40-year cumulative activities scenario for 

OCS activity following the CPA proposed action. 

Florida 

Gulf Oil drilled the first offshore exploration wells in Florida in 1947; these wells were in Florida Bay

south of Cape Sable in Monroe County. In 1956, Humble Oil drilled an exploration well in the State 

waters of Pensacola Bay in Santa Rosa County. All wells drilled in State waters were dry holes. Florida 

banned drilling in State waters in 1992. In 2005, Florida’s Governor Jeb Bush and the Florida Cabinet 

signed a historic settlement agreement to buy out any existing leases in State waters and to eliminate the 

potential for oil drilling there. Between 1987 and 1995, Chevron made commercial gas discoveries on the 

Destin Dome on the OCS, 25 mi (40 km) south of the western end of the Florida Panhandle in Federal 

OCS waters. The discovery extended eastward the highly productive Jurassic Norphlet trend from 

Mobile Bay. The State of Florida objected to plans to produce the discovery, however, and in May 2002, 
3-58 Central Planning Area Supplemental EIS

the U.S. Government agreed to buy back seven leases from Chevron, Conoco, and Murphy Oil for 

$115 million and to hold in abeyance any further development of the Destin Dome discovery until 2012. 

In April 2009, three committees of the Florida House of Representatives approved a bill that would 

allow offshore drilling in State waters >3 mi (4.8 km) from the eastern Gulf shore. The bill passed the 

Florida House in April 2009 but died soon after in the Florida Senate. 

The BOEMRE does not expect Florida to institute a lease sale program in the near future, although 

there is at least a possibility of a change in policy that could lead to leasing on the OCS or in State waters 

during the 40-year cumulative activities scenario for OCS activity following the CPA proposed action. 

Pipeline Infrastructure 

The existing pipeline network in the Gulf Coast States is the most extensive in the world and has 

unused capacity (USDOI, MMS, 2007b, p. 4-63). The network carries oil and gas onshore and inland to 

refineries and terminals, and a network of pipelines distribute finished products such as diesel fuel or 

gasoline to and between refineries and processing facilities onshore (Peele et al., 2002, Figure 4.1). 

Expansion of this network is projected to be primarily small-diameter pipelines to increase the 

interconnectivity of the existing network and a few major interstate pipeline expansions. Any new largerdiameter pipelines would likely be constructed to support onshore and offshore LNG terminals. 

However, as discussed in Chapter 3.3.3, there is spare capacity in the existing pipeline infrastructure to 

move regasified natural gas to market, and deepwater ports can serve onshore facilities including 

intrastate as well as interstate pipelines. 

There are currently 106 OCS-related (pipelines that have at one time or another carried hydrocarbon 

product from the OCS) pipeline landfalls in the LCA (Table 3-38 of the Multisale EIS). Included in that 

figure is a subset of 47 pipeline systems under DOT jurisdiction; these systems originate in Federal 

waters and terminate onshore or in Louisiana State waters (Gobert, 2010) (Figure 3-2). 

Pipelines that are constructed to serve the OCS and that are located in the LCA between now and 

2046 could result in direct impacts by displacing wetlands, but new construction would likely be along 

existing pipeline corridors and emplaced under wetlands using amphibious vehicles and required route 

backfilling. Pipelines International (2010) explained the procedures recently used by builders of a 30-indiameter onshore pipeline in near Hackberry, Louisiana, and a 24-in-diameter pipeline near Lottie, 

Louisiana. The following 10 steps for modern pipeline construction in wetlands used for the 30-indiameter pipeline were explained (Pipelines International, 2010): 

(1) move in equipment and personnel to establish and prepare right-of-way for 

continuous access; 

(2) identify and mark sensitive areas; 

(3) determine logistics for pipe, material, and personnel movement; 

(4) backhoe equipment trenches a ditch with sufficient depth and width to accommodate 

pipe installation; 

(5) crews perform welding, coating, and quality control functions and then install 

sufficient floats for buoyancy purposes; 

(6) equipment then guides different sections into final position before removing floats; 

(7) equipment and personnel are dispatched to remote locations to weld all sections in 

advance of backfilling; 

(8) after substantial backfill and all welding is completed, the entire line is subjected to 

hydrostatic testing to confirm suitability for intended use; 

(9) after hydrotest, tie-ins are completed; and 

(10) final cleanup and restoration, and move out equipment and personnel construction. 

As discussed in Chapter 4.1.3.2.6 of the Multisale EIS, the existing pipeline network in the Gulf 

Coast States is developed and extensive, with spare capacity in the existing pipeline infrastructure. Any 
Impact-Producing Factors and Scenario 3-59 

new larger diameter pipelines would likely be constructed to support onshore and offshore LNG 

terminals. The spare pipeline capacity is able to move the regasified natural gas to market, and deepwater 

ports can serve onshore facilities, including intrastate as well as interstate pipelines. Any expansions are 

projected to be primarily small diameter pipelines to increase the interconnectivity of the existing network 

and a few major interstate pipeline expansions. 

CPA Proposed Action Scenario: As reported is Chapter 3.1.1.4.1 for the CPA proposed action, 0-1 

new landfalls are projected. Any pipeline built as the result of the proposed action is most likely to be a 

subsea tie-in located in State waters; therefore, landloss projected to result from pipeline installations is 

not anticipated. New pipelines that landfall now call for mitigations that result in “no net loss” of 

wetland, no new direct wetland losses are projected over the cumulative activities scenario from OCSrelated pipeline construction. 

OCS Program Scenario: Pipeline landfalls in the GOM peaked in the 1970’s (Figure 3-2 ). The total 

length of OCS-related pipeline built would be partially based on future OCS leasing activity. For the 

OCS Program between the years 2007 and 2046, Table 4-5 of the Multisale EIS reported that a range of 

2,340 to 9,580 km (1,454 to 5,983 mi) of pipeline are projected to be built in the CPA in water depths of 

≤60 ft (18 m). 

3.3.3. Other Major Factors Influencing Offshore Environments 

Natural and man-caused influencing factors occur in the offshore areas of Gulf States while OCS 

activity takes place at the same time. Some of these factors are (1) dredged material disposal, (2) OCS 

sand borrowing, (3) marine transportation, (4) military activities, (5) artificial reefs and rigs-to-reefs 

development, (6) offshore LNG projects, (7) characterization of gas hydrates, and (8) renewable energy 

and alternative use. 

Dredged Material Disposal 

Chapter 4.1.3.2.1 of the Multisale EIS discusses offshore disposal of dredged material. Dredged 

material is described at 33 CFR 324 as any material excavated or dredged from navigable waters of the 

United States. Materials from maintenance dredging are primarily disposed of offshore on existing 

dredged-material disposal banks and in ocean dredged-material disposal sites (ODMDS), which are 

regulated by USEPA. Additional dredged-material disposal areas for maintenance or new-project 

dredging are developed as needed and must be evaluated and permitted by COE and relevant State 

agencies prior to construction. 

Dredged materials disposed offshore are not available for potential beneficial uses to restore and 

create habitat, beach nourishment projects, and industrial and commercial development; a use called the 

beneficial use of dredge materials program by COE (Chapter 3.3.4). Virtually all ocean dumping that 

occurs today is maintenance dredging of sediments from the bottom of channels and waterbodies in order 

to maintain adequate channel depth for navigation and berthing. There are four small ODMDS’s offshore 

Louisiana and Mississippi along open-water stretches of the main GIWW between Louisiana and 

Mississippi: in Louisiana ODMDS 66 (1,593 ac; 645 ha); and in Mississippi ODMDS 65A (1,962 ac; 

794 ha), 65B (815 ac; 330 ha), and 65C (176 ac; 71 ha) (U.S. Dept of the Army, COE, 2008, Table 1). 

Dredged materials from GIWW are sidecast at these ODMDS locations. The ODMDS’s designated by 

USEPA for general-purpose, continuing use in the cumulative activities area include those shown in 

Table 3-12. Maps show the locations for the ODMDS’s in Louisiana (USEPA and U.S. Dept. of the 

Army, COE, 2003, Appendix D). 

The COE’s Ocean Disposal Database reports the amount of dredged material disposed in ODMDS’s 

by district (U.S. Dept. of the Army, COE, 2011a). 

Current figures vary for how much of the average annual 70 million yd3

 (53,518,840 m3) that is 

dredged by the New Orleans District is available for the beneficial use of dredge materials program; from 

15 million yd3

 (11,468,320 m3) (U.S. Dept. of the Army, COE, 2009a, p. 26) to 30 million yd3

(22,936,650 m3

) (Green, 2006, p. 6), or between 21 and 43 percent of the total. The remaining 79 to 57 

percent of the total material dredged yearly by COE New Orleans District is disposed of in ODMDS’s or 

is stored in temporary staging areas located inland (e.g., the Pass a Loutre Hopper Dredge Disposal Site at 

the head of the Mississippi River’s main “birdfoot” distributary channel system). 
3-60 Central Planning Area Supplemental EIS

Between 2000 and 2009, the New Orleans District disposed of the following quantities of dredged 

materials in ODMDS’s (U.S. Dept. of the Army, COE, 2011a). 

New Orleans District 

Quantities of Dredged Materials Disposed of in ODMDS, 2000-2009 

Amount Disposed of in ODMDS Year yd3 m3

2000 16,377,800 12,522,466 

2001 23,272,300 17,794,001 

2002 57,643,200 44,073,991 

2003 22,546,200 17,238,825 

2004 21,156,300 16,176,107 

2005 21,403,200 16,364,887 

2006 13,493,400 10,317,054 

2007 17,550,700 13,419,265 

2008 16,800,900 12,845,968 

2009 16,295,000 12,459,157 

Average per year 22,653,900 17,321,172 

Cumulative Activities Scenario: The BOEMRE anticipates that over the next 40 years the amount of 

dredged material disposed at ODMDS’s will fluctuate generally within the trends established by the New 

Orleans District. The New Orleans District has averaged about 22 million yd3

 of material dredged per 

year disposed at ODMDS’s over the last 10 years. Quantities may decrease slightly as more beneficial 

uses of dredged material onshore are identified. The 1972 Convention on the Prevention of Marine 

Pollution by Dumping of Wastes and Other Matter (the London Convention), to which the U.S. is a 

signatory, requires annual reporting of are amount of materials disposed at sea. The COE prepares the 

dredged material disposed portion of the report to the International Maritime Organization, the yearly 

reports for which are posted on COE’s Ocean Disposal Database (U.S. Dept. of the Army, COE, 2011b). 

OCS Sand Borrowing 

Chapter 4.1.3.2.2 of the Multisale EIS discusses in detail this Agency’s Marine Minerals Program, 

which provides policy direction for the development of marine mineral resources on the OCS. If OCS 

sand is desired for coastal restoration or beach nourishment, BOEMRE uses the following two types of 

lease conveyances: a noncompetitive negotiated agreement that can only be used for obtaining sand and 

gavel for public works projects funded in part or whole by a Federal, State, or local government agency; 

and a competitive lease sale in which any qualified person may submit a bid. The BOEMRE has issued 

29 noncompetitive negotiated agreements but has never had a competitive lease sale for OCS sand and 

gravel resources. The OCS Program continues to focus on identifying sand resources for coastal 

restoration, investigating the environmental implications of using those resources, and processing 

noncompetitive use requests. 

This Agency has participated in the multi-agency Louisiana Sand Management Working Group since 

2003 to identify, prioritize, and define a pathway for accessing sand resources in the near-offshore OCS 

of Louisiana, an area where competitive space use mainly involves OCS oil and gas infrastructure such as 

wells, platforms, and pipelines. Table 3-13 shows the projected OCS sand uses for coastal restoration 

projects over approximately the next 5 years. Approximately 76 million yd3 are expected to be needed for 

coastal restoration projects as reported by the Louisiana Office of Coastal Protection and Restoration. To 

visualize such a dimension, it is equivalent to a volume of sand that could fit on a National Football 

League field (300 x 160 ft) to a height of 2.71 mi (4.3 km) high.

This Agency received earmarked funds in 2005 to conduct offshore sand studies to investigate 

available sources of OCS sand for restoring coastal areas in Louisiana, Texas, Alabama, and Mississippi 

that were damaged by Hurricanes Katrina and Rita. Sand sources identified through this Agency’s 

cooperative effort with Louisiana will likely serve as the major source of material for the restoration of 

the barrier islands planned as part of the LCA ecosystem restoration study (U.S. Dept. of the Army, COE, 
Impact-Producing Factors and Scenario 3-61 

2004a). The Louisiana Office of Coastal Protection and Restoration and Louisiana State University have 

undertaken joint efforts, funded in part through BOEMRE, to identify potential sand resources in the 

Trinity and Tiger Shoal complex, located in the Vermilion and South Marsh Island leasing areas, and to 

examine the long-term effects of dredging sand on Ship Shoal, a large potential borrow area about 15 mi 

(24 km) offshore Isle Dernieres, south central Louisiana. Meanwhile, the General Land Office in Texas is 

collecting new geologic and geophysical data to identify and characterize potential resources in buried 

Pleistocene Sabine and Colorado River paleochannels, located offshore Jefferson and Brazoria Counties. 

Since the dredging of OCS sand and the associated activities of oceangoing dredge vessels could 

present some use conflicts on blocks also leased for oil and/gas extraction, this Agency initiated a 

regional offshore sand management program in Louisiana in 2003, which over the course of 7 years and 

several meetings has developed options and recommendations for an orderly process to manage the 

competing use of OCS sand resources in areas of existing OCS infrastructure. With input from the Sand 

Management Working Group, BOEMRE has developed guidelines for sand resource allocations, 

maintaining a master schedule of potential sand dredging projects, developing procedures for accessing 

sand under emergency conditions, and establishing environmental requirements for the use of offshore 

borrow areas. 

The following five leases for OCS sand have been issued in the CPA: (1) Holly Beach, Cameron 

Parish, Louisiana; (2) the South Pelto test area, Terrebonne Parish, Louisiana; (3) Pelican Island shoreline 

restoration, Plaquemines Parish, Louisiana; (4) Raccoon Island marsh creation, Terrebonne Parish, 

Louisiana, and (5) St. Bernard Shoals, St. Bernard and Plaquemines Parish, Louisiana. 

In May 2002, this Agency completed a negotiated lease with the U.S. Dept. of Agriculture’s Natural 

Resource Conservation Service and the Louisiana Dept. of Natural Resources for the Holly Beach project 

(CWPPRA Project CS-31) in Cameron Parish, Louisiana. The project goals were as follows: (1) to 

reestablish a more historical shoreline configuration, as well as improve the effectiveness of the existing 

segmented breakwater system, and protect approximately 8,000 ac (3,237 ha) of low-energy intermediate 

and brackish marsh wetlands; and (2) to create and protect roughly 300 ac (121 ha) of beach dune and 

coastal chenier habitat from erosion and degradation. The project also protected a wooded chenier that 

serves as a sanctuary for Neotropical migratory birds. The project involved the use of approximately 

1,762,583 yd3

 (1,347,600 m3) of OCS sand from Sabine Bank and the buried Peveto paleochannel 

approximately 5 mi (8 km) south of Holly Beach. Construction was completed in March 2003. 

In December 2002, this Agency completed a negotiated lease with the Louisiana Dept. of Natural 

Resources to use a hopper dredge to extract approximately 3,000 yd3

 (2,294 m3) of sand from Ship Shoal 

within South Pelto Block 12 to determine the loading characteristics and “overfill factor” of the sand from 

the eastern end of Ship Shoal. The sand was determined to be high-quality sand for barrier island 

restorations. The test was completed in December 2002. 

In June 2008, this Agency completed a 3-party noncompetitive negotiated agreement with NOAA and 

the Louisiana Dept. of Natural Resources for the Barataria Barrier Island Complex Project: Pelican Island 

and Pass La Mer to Chaland Pass Restoration (CWPPRA Project BA-38) in Plaquemines Parish, 

Louisiana. The project’s objectives are as follows: (1) preventing the breaching of the barrier shoreline 

by increasing barrier width and height; (2) increasing back-barrier, emergent marsh area by some 220 ac 

(89 ha) to maintain the barrier shoreline; (3) restoration and creation of about 180 ac (73 ha) of dune, 

beach, and berm; and (4) creating emergent marsh suitable for tidal aquatic habitats. This project will use 

approximately 5,523,000 yd3

 of OCS sediment from the buried Sandy Point paleochannels (West Delta 

Blocks 26, 27, and 49). The project was authorized in 2002 by CWPPRA, and the lease was requested in 

July 2003. It is anticipated that construction will begin in 2011. 

In May 2009, this Agency completed a 3-party negotiated agreement with the U.S. Dept. of 

Agriculture’s Natural Resource Conservation Service and the Louisiana Dept. of Natural Resources for 

the Raccoon Island Protection/Marsh Creation Phase B project (CWPPRA Project TE-48) in Terrebonne 

Parish, Louisiana. Raccoon Island is the westernmost barrier island in the Isles Dernieres chain and is a 

project that has been separated into two construction phases. Phase A includes the construction of eight 

additional segmented breakwaters Gulfward of the island. Phase B involves the construction of a 

retention dike along the northern shore at the westernmost end of the island to create a back bay enclosure 

of approximately 60 ac (24 ha) to create back-barrier marsh habitat that protects and enhances an 

important rookery for seabirds. The project plans for the use of approximately 750,000 yd3

 (573,400 m3) 
3-62 Central Planning Area Supplemental EIS

of OCS sediment from a borrow area 4 mi (6 km) south of Raccoon Island in Ship Shoal Blocks 64 and 

71. It is anticipated that construction will begin in 2011. 

Part of the DWH event response by the State of Louisiana involved the construction of artificial sand 

berms seaward of existing barrier island shorelines to protect fragile coastal marsh and estuarine 

environments from the landfall of oil. The details of this project are discussed in Appendix D. Of the 

101 mi (163 km) of berm originally contemplated in the State’s berm program, 45 mi (72 km) were 

approved by COE and UIC, for which BP would pay $360 million. On May 14, 2010, the Louisiana 

Office of Coastal Protection and Restoration requested a BOEMRE lease to use OCS sand from 

St. Bernard Shoals for construction of the emergency sand berms, and on July 16, 2010, an emergency 

negotiated agreement was executed. However, no OCS sand was used during the construction of the 

emergency berms because (1) the use of hopper dredges in the Gulf was not allowed after excessive 

nonlethal and lethal turtle takes occurred during the first week of dredging in State waters and (2) the 

Federal On-Scene Coordinator for the DWH event notified the State that their request for concurrence for 

dredging activity at St Bernard Shoals was denied. The berms were completed in March 2011. A total of 

approximately 10,300,000 yd3

 of sand was placed to construct 20.5 mi (4 km) of berm, of which 8.8 mi 

(14.2 km) was constructed along the E-4 segment along the northern Chandeleur Islands in St. Bernard 

Parish and 11.7 mi (18.8 km) were constructed along the W-8, W-9, and W-10 segments in Plaquemines 

Parish. All sand used to construct the berm was mined from Hewes Point north of the Chandeleur Islands 

(Louisiana State waters) and from the lower Mississippi River. 

The BOEMRE is currently working with Louisiana on two negotiated agreements for upcoming 

projects: Cameron Parish Beach Restoration and Caminada Headland Restoration. The Cameron Parish 

project proposes to utilize sand from Sabine Bank (West Cameron Blocks 114 and 117), and the 

Caminada Headland project proposes to use sand from Ship Shoal (South Pelto Blocks 12, 13, 14, 18, and 

19). 

Cumulative Activities Scenario: Great uncertainty exists for how much OCS sand offshore the State 

of Louisiana will eventually be sought for future coastal restoration projects. The CWPPRA projects that 

are authorized may seek to access it, but other future programs that intend to use OCS sand include the 

Louisiana Coastal Protection and Restoration Authority’s Annual Plan and the coastal restoration and 

flood protection projects that are part of COE’s plan (U.S. Dept. of the Army, COE, 2009c, Figures 17-1, 

17-2, and 17-3). 

Marine Transportation 

Chapter 4.1.3.2.3 of the Multisale EIS and Chapter 3.3.3 of the 2009-2012 Supplemental EIS discuss 

the extensive maritime industry that exists in the northern GOM. Freight and cruise ship passenger 

marine transportation within the analysis area should continue to grow at a modest rate or remain 

relatively unchanged based on historical freight traffic statistics under current conditions. The Port of 

New Orleans was the sixth largest port in the United States in terms of tonnage handled in 2008. Tankers 

carrying mostly petrochemicals account for about 40 percent of the vessel calls. Dry-bulk vessels 

carrying coal, coke, grain, etc., account for another 40 percent of vessel calls. New Orleans is a popular 

port for cruises. The Port of New Orleans supports year-round operations at the Julia Street and Erato 

Street cruise terminals that, in 2009, saw 101 cruise ship departures (Chambers, 2010). 

Trends for use of all Gulf Coast ports show an increase from 31.2 to 34.1 percent of total U.S. port 

use (USDOT, MARAD, 2009) between 2004 and 2009 (Table 3-14), an increase of about 3 percent over 

the past decade. The estimated number of vessel trips that would occur as a result of the CPA proposed 

action is presented in Table 3-2. Use by the OCS Program represents a small percentage of total marine 

transportation in the GOM, <1 percent of reported usage for Federal channels (Chapter 3.1.1.4.4). 

Cumulative Activities Scenario: The BOEMRE anticipates that, over the next 40 years, the total 

amount of Gulf Coast port usage will be bounded by a lower limit of the approximate levels of current use 

and a higher limit consisting of a steady increase of approximately 3 percent each decade. 

Military Activities 

Chapter 4.1.3.2.4 of the Multisale EIS and Chapter 3.3.3 of the 2009-2012 Supplemental EIS discuss 

in detail the extensive use of the offshore GOM for military activities. Twelve military warning areas and 

six Eglin Water Test Areas (EWTA’s) are located within the Gulf (Figure 2-3). The CPA includes all or 
Impact-Producing Factors and Scenario 3-63 

part of the following Eglin Water Test Areas: EWTA-1, EWTA-3, and EWTA-4; and all or part of the 

following military warning areas: W-59, W-92, W-147 W-155 and W-453. The air space over the CPA 

is used by the DOD for conducting various air-to-air and air-to-surface operations. These warning and 

water test areas are multiple-use areas where military operations and oil and gas development have 

coexisted without conflict for many years. Several military stipulations are planned for leases issued 

within identified military areas. 

Cumulative Activities Scenario: The BOEMRE anticipates that, over the next 40 years, the military 

use areas currently designated in the CPA will remain the same and that none of them would be released 

for nonmilitary use. Over the cumulative activities scenario, BOEMRE expects to continue to require 

military coordination stipulations in these areas. The intensity of the military’s use of these areas, or the 

type of activities conducted in them, is anticipated to fluctuate with the military mission needs. 

Artificial Reefs and Rigs-to-Reefs Development 

Chapter 4.1.3.2.5 and Appendix A.4 of the Multisale EIS and Chapter 3.3.3 of the 2009-2012 

Supplemental EIS discuss in detail artificial reefs and rigs-to-reefs development in the GOM. Artificial 

reefs have been used along the coastline of the U.S. since the early 19th century. Stone (1974) 

documented that the use of obsolete materials to create artificial reefs has provided valuable habitat for 

numerous species of fish in areas devoid of natural hard bottom. Stone et al. (1979) found reefs in marine 

waters not only attract fish, but in some instances also enhance the production of fish. All of the five Gulf 

Coast States—Texas, Louisiana, Mississippi, Alabama, and Florida—have artificial reef programs and 

plans. 

Most OCS platforms have the potential to serve as artificial reefs. Offshore oil and gas platforms 

began providing artificial reef substrate in the GOM with the first platform’s installation in 1942. 

Historically, approximately 9 percent of the platforms decommissioned in the Gulf OCS have been used 

in the Rigs-to-Reefs Program. It is anticipated that approximately 10 percent of platforms installed as a 

result of the CPA proposed action would be converted to a reef after decommissioning. This factor is 

prompting increased public attention on the ecologic value of oil and gas structures for their reef effects. 

Ongoing studies aim at evaluating the ecology of offshore structures and may lead to a greater emphasis 

on creation of artificial reefs through the Rigs-to-Reefs Program. At present, Texas, Louisiana, and 

Mississippi participate in the Rigs-to-Reefs Program. 

CPA Proposed Action Scenario: The number of platforms projected for the proposed action in the 

CPA is 32-44 (Table 3-2). The number of rigs-to-reefs anticipated as a result of the CPA proposed action 

is approximately 10 percent of the projected removals, or 3-4 in the CPA. 

OCS Program Scenario: For the OCS Program from the years 2007-2046, a total of 4,925-4,949 

platforms in the CPA are projected to be removed during the 40-year cumulative activities scenario 

(Table 4-6 of the Multisale EIS). If approximately 10 percent of these structures are accepted into the 

Rigs-to-Reefs Program, there may be as many as 492-495 additional artificial reefs installed in the CPA 

or elsewhere. 

Offshore Liquefied Natural Gas Projects and Deepwater Ports 

Chapter 4.1.3.2.6 of the Multisale EIS discusses in detail offshore LNG terminals projected, 

approved, and existing in the GOM. One LNG terminal is presently operating on the OCS in the GOM: 

the Gulf Gateway Energy Bridge. Brought into service in March 2005, the Gulf Gateway Energy Bridge 

is located in 280 ft (85.3 m) of water in West Cameron, South Addition Block 603, approximately 116 mi 

(187 km) offshore the Texas-Louisiana border. The Gulf Gateway Energy Bridge is capable of delivering 

natural gas at a baseload rate of 500 Bcf per day. The license for the Gulf Gateway Energy Bridge 

operation was issued by DOT’s Maritime Administration (MARAD) on May 24, 2004. 

Exxon-Mobile’s Golden Pass LNG terminal on the Sabine Pass waterway in Jefferson County near 

the Texas-Louisiana border and Port Arthur, Texas, was scheduled to open in 2009, but it was severely 

damaged by Hurricane Ike in September 2008. At full operation, Golden Pass will be able to deliver the 

equivalent of 2 Bcf per day of natural gas. Golden Pass received its first shipment of super-cooled LNG 

on October 28, 2010, at which time (Gonzalez, 2010) reported that it arrived in the midst of a domestic 

gas surplus. 
3-64 Central Planning Area Supplemental EIS

“Shale gas” is a new source of onshore natural gas that is easy to reach, and it is throwing plans for 

LNG terminals into turmoil. Recent technological improvement in fracing tight geologic formations has 

opened the shale gas frontier. Shale gas is held in fine-grain formations, such as shale, that is difficult to 

produce without introducing artificial fractures (fracing) through which gas can flow to a wellbore and be 

produced. The prospect of a larger, more accessible, domestic gas supply acts to depress gas prices and 

affects the economics for heavily capitalized LNG installations. The Henry Hub price of natural gas 

between 2002 and 2007 fluctuated between $5.00 and $8.00 Mcf. The price spiked to $15.00 Mcf after 

the 2005 GOM hurricanes, and a speculative bubble peak high price of $13.00 Mcf was reached in July 

2008. With aggressive discovery and production of shale gas and the Great Recession, the Henry Hub 

price of natural gas in 2009 and 2010 collapsed to fluctuate between $2.00 and $5.00 Mcf for most of this 

period. The LNG or deepwater port facilities below are now in some stage of the permitting process 

(USDOT, MARAD, 2010). 

Alabama 

Bienville Offshore Energy Terminal. TORP Technology LP filed an application on January 12, 2006, 

for an LNG facility to be located in the GOM, 63 mi (101 km) south of Mobile Point, Alabama. The 

proposed facility will consist of a HiLoad Unit, which is a floating structure connecting directly to the 

LNG carrier hull. The MARAD and USCG stopped the regulatory timeline for processing the application 

on August 21, 2007, after determining that additional information was needed to effectively process the 

application. On October 9, 2008, the applicant elected to withdraw its application in order to consider 

technical modifications to its proposed project. A revised application was submitted on June 30, 2009, 

featuring a redesigned terminal using “closed loop” ambient air technology for LNG vaporization, and a 

Notice of Amended Application and Notice of Intent to produce a supplemental EIS was published in the 

Federal Register on August 5, 2009. A public hearing was held in Mobile, Alabama, on December 9, 

2009. On September 14, 2010, the Governor of Alabama approved the Bienville Offshore Energy 

Terminal application with conditions. The USCG is working with MARAD to prepare the Record of 

Decision.

Louisiana 

Main Pass Energy Hub. Freeport McMoran filed a notice of revised application on June 22, 2006, to 

convert a sulphur/brine mining facility into an LNG terminal for regasification. An EIS was prepared and 

the Governor of Louisiana issued an approval letter on November 20, 2007. The Main Pass Energy Hub 

would be located 16 mi (26 km) offshore Louisiana in Main Pass Block 299. As of May 27, 2009, the 

Federal Energy Regulatory Commission granted a 1-year extension to Freeport McMoran to build a 

pipeline associated with the facility, and Freeport McMoran is in the process of seeking gas suppliers. 

Development of Gas Hydrates 

The DOE and cooperating agencies are in the middle of a multiyear characterization program of 

naturally occurring methane hydrates (gas hydrates) in the GOM. The first cruise for characterizing 

GOM gas hydrates took place in 2005, and the second took place in 2009. A third cruise is in the 

planning stages. Gas hydrates are a unique, energy-rich, and poorly understood class of chemical 

substances in which molecules of one material (in this case solid-state water—ice) form an open lattice 

that physically encloses molecules of a certain size (in this case—methane) in a cage-like structure 

without chemical bonding (Berecz and Balla-Achs, 1983; Henriet and Mienert, 1998; Collett, 2002). 

Studying gas hydrates poses unique technical challenges because they occur only in remote and hostile 

environments—arctic landmasses and deepwater continental shelves. Moreover, they are only stable in 

high-pressure and low-temperature environments, and they are difficult to extract from their natural 

setting for laboratory study. 

The Methane Hydrate Research and Development Act of 2000 (P.L. 106-193; May 2, 2000) promoted 

the research, identification, assessment, exploration, and development of methane hydrate resources in the 

United States as the work of a joint effort between seven Federal agencies. The DOE is the coordinating 

agency and participants include the USGS, this Agency, BLM, the Naval Research Laboratory, NOAA, 
Impact-Producing Factors and Scenario 3-65 

and the National Science Foundation. The Methane Hydrate Research and Development Act of 2000 was 

reauthorized for 2005-2010 in Section 968 of the EPAct. 

The Methane Hydrate Research and Development Act of 2000 allows DOE to enter into awards, 

contracts, and cooperative agreements with institutions of higher education or industrial enterprises for 

the purposes of (1) conducting basic and applied research to identify, explore, assess, and develop 

methane hydrate as a source of energy; (2) developing technologies required for efficient and 

environmentally sound development of methane hydrate resources; (3) undertaking research programs to 

provide safe means of transport and storage of methane produced from gas hydrates; (4) promoting 

education and training in methane hydrate resource research and resource development; (5) conducting 

basic and applied research to assess and mitigate the environmental impacts of hydrate degassing 

(including both natural degassing and degassing associated with commercial development); (6) 

developing technologies to reduce the risks of drilling through naturally occurring methane hydrates; and 

(7) drilling in support of authorized activities. 

Seismic evidence for gas hydrates typically consists of a bottom simulating reflector at relatively 

shallow depths below mudline; shallow at least in comparison with conventional oil and gas exploration 

wells. The bottom simulating reflector is caused by the large acoustic impedance contrast at the base of 

the gas hydrate stability zone that separates sediments containing gas hydrate above with sediments 

containing free gas below. 

In the Gulf of Mexico a Joint Industry Project (JIP) was formed to carry out an assessment of gas 

hydrates. Members of the 2009 JIP included ChevronTexaco (operator); this Agency; ConocoPhillips; 

Halliburton; Total; Schlumberger; Reliance Industries Limited; Japanese Oil, Gas, and Metals National 

Corporation; Korea National Oil Company; and StatoilHydro. Three legs to the total JIP were planned. 

For the first leg in 2005, JIP carried out a test drilling program to sample gas hydrates on the Gulf of 

Mexico OCS at eight locations in three blocks (Atwater Valley Blocks 13 and 14, and Keathley Canyon 

Block 151) in the CPA where hydrates were thought to occur. The results of the 2005 JIP were published 

in the DOE newsletter Fire in the Ice (Birchwood et al., 2008). 

For the second leg in 2009, the JIP was permitted by this Agency to carry out a test drilling program 

to sample gas hydrates on the Gulf of Mexico OCS at multiple locations in two blocks; Green Canyon 

Block 955 and Walker Ridge Block 313 in the CPA and Alaminos Canyon Blocks 775, 818, and 819 in 

the WPA. JIP modified the WPA drilling program to include two boreholes in Alaminos Canyon Block 

21 instead of the originally permitted blocks (Fire in the Ice, 2009) and deployed for Leg II in April 2009 

using a dynamically-positioned drillship. The test wells were 8.5-in-diameter that penetrated shallow 

sediment up to 3,680 ft (1,122 m) below mudline to allow geophysical logging followed by abandonment 

procedures. All wells were geophysically logged while drilling with resistivity, borehole imaging, 

gamma ray, density, neutron porosity, and magnetic resonance logs. Unlike the 2005 JIP program in the 

GOM, the 2009 JIP did not retrieve pressurized cores of gas hydrate from the sampled holes. Technical 

reports resulting from the 2009 JIP include Boswell et al. (2009), Kou (2010), and Zhang and McConnell 

(2011). 

This Agency released the results of a systematic geological and statistical assessment of gas hydrates 

resources in the GOM (USDOI, MMS, 2008b). This assessment incorporates the latest science with 

regard to the geological and geochemical controls on gas hydrate occurrence. It indicated that a mean 

volume of 607 trillion m3

 (21,444 Tcf) of methane was in-place in hydrate form. The assessment has 

determined that a mean of 190 trillion m3

 (6,710 Tcf) of this resource occurs as relatively highconcentration accumulations within sand reservoirs that may some day be produced. The remainder 

occurs within clay-dominated sediments from which methane probably would never be economically or 

technically recoverable. 

Cumulative Activities Scenario: The BOEMRE anticipates that, over the next 40 years, JIP will 

complete the third leg of their characterization project for GOM gas hydrates in the cumulative impacts 

area. Within 40 years, it is likely that the first U.S. domestic production from hydrates may occur in 

Alaska, where gas obtained from onshore hydrates will either support local oil and gas field operations or 

be available for commercial sale if and when a gas pipeline is constructed to the lower 48 states. 

However, Moridis et al. (2008, p. 4) stated that it is not possible to discount the possibility that first U.S. 

domestic production of gas hydrates could occur in the GOM. Despite the substantially increased 

complexity and cost of offshore operations, there is a mature network of available pipeline capacity and 

easier access to markets in the GOM. 
3-66 Central Planning Area Supplemental EIS

Renewable Energy and Alternative Use 

Chapter 4.1.3.3.5 of the Multisale EIS and Chapter 3.3.6 of the 2009-2012 Supplemental EIS discuss 

the renewable (sometimes called “alternative”) energy projects as they are developing in the GOM. On 

August 8, 2005, President George W. Bush signed into law the EPAct of 2005. Section 388 (a) of EPAct 

amended Section 8 of the OCSLA (43 U.S.C. 1337) to authorize DOI to grant leases, easements, or 

rights-of-way on the OCS for the development and support of energy resources other than oil and gas and 

to allow for alternate uses of existing structures on OCS lands. 

A final programmatic EIS for the OCS renewable energy program was published by this Agency in 

October 2007 (USDOI, MMS, 2007f) and a Record of Decision was published in the Federal Register on 

January 10, 2008 (Federal Register, 2008). The Act authorized this Agency to develop a comprehensive 

program and regulations to implement the new authority. Final rules for the renewable energy program 

were published on April 29, 2009, as 30 CFR 285 (Federal Register, 2009b). 

The two primary categories of renewable energy that have potential for development in the coastal 

and OCS waters of the U.S. are (1) wind turbines and (2) marine hydrokinetic systems. The first and 

most technologically mature renewable energy is wind energy, a popular source of clean and renewable 

energy that has been in use for centuries. At present, 45 offshore wind farms are in operation, all of 

which are located off the coast of the United Kingdom and mainland Europe in waters generally 

shallower than 30 m (100 ft), and 10 more offshore wind farms are currently under construction in this 

area (European Wind Energy Association, 2011). China and Japan also have offshore wind farms and 

plan to expand their offshore wind power (Feldman, 2009; Schwartz, 2010; Singh, 2010; 

offshoreWIND.biz, 2010). 

Ocean wind energy has emerged as a promising renewable energy resource for a number of reasons: 

(1) the strength and consistency of winds on the ocean are roughly proportional to distance from shore, 

the farther from shore the stronger and more persistent; (2) offshore wind generating facilities (wind 

parks) can therefore be located in proximity to major load centers in the energy-constrained northeastern 

U.S.; (3) long-term potential for the over-the-horizon siting and undersea transmission lines counters the 

aesthetics and land-use concerns associated with onshore wind installations and those that can be seen 

easily from shore; and (4) as a fuel, wind is both cost-free and emission free (Massachusetts Technology 

Collaborative, 2005). 

The DOE released a predecisional strategic plan for creating an offshore wind industry in the U.S. 

(USDOE, 2010). In this plan, DOE determined that offshore wind energy can help the Nation reduce its 

greenhouse gas emissions, diversify its energy supply, provide cost-competitive electricity to key coastal 

regions, and stimulate economic revitalization of key sectors of the economy. However, if the Nation is 

to realize these benefits, key barriers to the development and deployment of offshore wind technology 

must be overcome, including the relatively high cost of energy, technical challenges surrounding 

installation and grid interconnection, and the untested permitting processes governing deployment in both 

Federal and State waters. There are two critical objectives to realize the strategic plan’s goals: (1) reduce 

the cost of offshore wind energy; and (2) reduce the timeline for deploying offshore wind energy 

(USDOE, 2010, p. 1). Since April 29, 2009, when the regulations governing renewable energy on the 

OCS were promulgated, no wind park developments have been proposed in OCS waters of the GOM. 

The second category of offshore renewable energy is marine hydrokinetic systems, which are in a 

more developmental stage relative to wind turbines. The marine hydrokinetic systems consist of devices 

capable of capturing energy from ocean waves and currents. There has been no interest expressed in 

wave or current technologies in the GOM because the conditions necessary for their deployment are not 

suitable to the Gulf. The marine hydrokinetic current technologies are actively being considered for the 

east coast of Florida where the Gulf Stream provides a strong and continuous source of energy to turn 

underwater turbines. 

The EPAct clarifies the Secretary’s authority to allow the existing oil and gas structures on OCS lands 

to remain in place after production activities have ceased and to transfer liability and extend the life of 

these facilities for non-oil and gas purposes, such as research, renewable energy production, aquaculture, 

etc., before being removed. With approximately 1,900 bottom-founded platform structures located in 

OCS waters, the GOM would seem to have some potential for the reuse of these facilities. Although 

BOEMRE has had conversations with developers about conceptual ideas for alternative use projects, no 

developer has stepped forward with an application to actualize one.
Impact-Producing Factors and Scenario 3-67 

Cumulative Activities Scenario: The BOEMRE anticipates that, over the next 40 years, at least one 

alternative use project would be brought to the Agency for action. It is also likely that at least one wind 

park project will be proposed offshore Louisiana in the cumulative impact area. A project could consist 

of a combination of integrated existing GOM infrastructure with new-built facilities. Such a projection is 

made because this type of project was vetted to this Agency in 2004, before the EPAct was passed to set 

up the framework to permit and regulate renewable energy projects on the OCS. 

3.3.4. Other Major Factors Influencing Coastal Environments 

Natural and man-caused factors influence the coastal areas of the Gulf States while OCS activity 

takes place at the same time. Some of these factors are (1) sea-level rise and subsidence; (2) Mississippi 

Delta hydromodifications; (3) maintenance dredging activities; (4) Coastal Impact Assistance Program 

activities; and (5) coastal restoration programs. 

Sea-Level Rise and Subsidence 

Chapter 4.1.3.3.1 of the Multisale EIS and Chapter 3.3.4 of the 2009-2012 Supplemental EIS discuss 

wetland submergence in the LCA. The Delta Plain and Chenier Plain of the LCA are experiencing 

relatively high subsidence rates as part of the Mississippi River’s delta system. All coastlines of the 

world have been experiencing a gradual absolute rise of sea level that is based on measurements across 

the globe and that extends across the influence of a single sedimentary basin. There are two aspects of 

sea-level rise during the most geologically recent 10,000 years (Holocene Epoch): absolute rise and 

relative rise. Absolute sea-level rise refers to a net increase in the volume of water in the world’s oceans. 

Relative sea-level rise refers to the appearance of sea-level rise, a circumstance where subsidence of the 

land is taking place at the same time that an absolute sea-level change may be occurring. Geologists tend 

to consider all sea-level rise as relative because the influence of one or the other is difficult to separate 

over geologic time frames. 

An absolute sea-level rise would be caused by the following two main contributors to the volume of 

ocean water on the Earth’s surface: (1) change in the volume of ocean water based on temperature; and 

(2) change in the amount of ice locked in glaciers, mountain ice caps, and the polar ice sheets. For the 

period 1961-2003, thermal expansion of the oceans accounts for only 23 ± 9 percent of the observed rate 

of sea-level rise (Intergovernmental Panel on Climate Change, 2007a, Chapter 5 and Table 5.3), the 

remainder is water added to the oceans by melting glaciers, ice caps, and the polar ice sheets. The 

contribution of thermal expansion is between 14 and 32 percent of the total absolute sea level rise over 

this 42-year period. The remainder, approximately 75 percent, of sea-level rise is attributed to melt water. 

Measurement of sea-level rise over the last century is based on tidal gauges and, more recently, 

satellite observations, that are not model-dependent. Projections for future sea-level rise are dependent on 

temperature. As determined by analysis of air bubbles trapped in Antarctic ice cores, today’s atmospheric 

concentration of CO2 is the highest it has ever been over the last 800,000 years (Karl et al., 2009, p. 13). 

Although the measured data for atmospheric CO2 concentration or temperatures measurements since the 

Industrial Revolution are generally not in dispute, proxy data for climates of the geologic past are a source 

of debate and the models constructed to make projections for how climate may change remain 

controversial. Climate models are very sophisticated, but they may not account for all variables that are 

important or may not assign to modeled variables the weight of their true influence. 

The Intergovernmental Panel on Climate Change reported that, since 1961, global average sea level 

(mean sea level) has risen at an average rate of 1.8 millimeter/year (mm/yr) (0.07 in/yr) and, since 1993, 

at 3.1 mm/yr (0.12 in/yr) (Intergovernmental Panel on Climate Change, 2007a). Whether the faster rate 

for 1993-2003 reflects decadal variability or an increase in the longer-term trend is unclear. In the 

structured context used by the Intergovernmental Panel on Climate Change, there is high confidence that 

the observed sea-level rise rate increased from the 19th to the 20th century. The average global rate for the 

20th century was determined by Bindoff et al. (2007, Section 5.5.2.1) to be 1.7 ± 0.5 mm/yr and the total 

20th-century average rise is estimated to be 0.17 m (0.55 ft) (Intergovernmental Panel on Climate Change, 

2007a). The U.S. Global Change Research Program reported that over the last 50 years sea-level has 

risen up to 8 in (203 mm) along parts of the Atlantic and Gulf Coasts that included Louisiana (Karl et al., 

2009, p. 37), and that global sea level is currently rising at an increasing rate. 
3-68 Central Planning Area Supplemental EIS

Although absolute sea-level rise is a contributor to the total amount of sea-level rise along the Gulf 

Coast, subsidence is the most important contributor to the total. In comparison to other areas along the 

Gulf Coast, Louisiana’s Mississippi Delta and Chenier Plains are built of young sediments deposited over 

the last 7,000 years. These deltaic sediments have been undergoing compaction and subsidence since 

they were deposited. The land is sinking at the same time that sea level is rising, contributing to high 

rates of relative sea-level rise along the Louisiana coast. Blum and Roberts (2009) posited three scenarios 

for subsidence and sea-level rise, and they concluded sediment starvation alone would cause ~2,286 mi2

(592,071 ha) of the modern delta plain to submerge by 2050, without any other impacting factors 

contributing to landloss. 

A general value of ~6 mm/yr (0.23 in) of subsidence from sediment compaction, dewatering and 

oxidation of organic matter (Meckel et al., 2006; Dokka, 2006) is a reasonable rate to attribute to the 

Louisiana coastal area, with the understanding that subsidence rates along the Louisiana coast are 

spatially variable and influenced by subsurface structure and the timing and manner that the delta was 

deposited. Applied to the entire coast, it is an oversimplification of a complex system, but it is an 

estimate that is reasonable based on recent data. 

Stephens (2009 and 2010a) reported that the influence of subsurface structure has not been taken into 

account in subsidence assessments in the LCA and along the Gulf Coast (Stephens, 2009, p. 747). Most 

workers studying the affects of subsidence along the LCA have focused on surficial or near-surface 

geologic data sources and have made no attempt to integrate basin analysis into planning for coastal 

restoration or flood control project planning. 

The BOEMRE anticipates that, over the next 40 years, the LCA will likely experience a total of 

relative sea-level rise of ~45 cm (18 in), or approximately 9 mm/yr (0.35 in). This estimate is made by 

combining the estimated rate for subsidence (~6 mm/yr) (0.23 in) and the estimated rate for absolute sealevel rise (~3 mm/yr) (0.12 in). 

Formation Extraction and Subsidence 

Extracting fluids and gas from geologic formations can lead to localized subsidence at the surface. 

Morton et al. (2005) examined localized areas or “hot spots” corresponding to fields in the LCA where 

oil, gas, and brine were extracted at known rates. Morton et al. (2005, Figure 26) shows measured 

subsidence along transects across these fields that range from 18 to 4 mm/yr (0.7 to 0.15 in), with the 

greatest rates tending to coincide with the surface footprints of oil or gas fields. Mallman and Zoback 

(2007) interpreted downhole pressure data in several Louisiana oil fields in Terrebonne Parish and found 

localized subsidence over the fields; however, they could not link these localized rates to the subsidence 

measured and observed on a regional scale. 

Down-to-the-basin faulting, also called listric or growth faulting, is a long recognized structural style 

along deltaic coastlines, and the Mississippi Delta is no exception (Dokka et al., 2006; Gagliano, 2005a). 

There is currently disagreement in the literature regarding the primary cause of modern fault movement in 

the Mississippi Delta region, and the degree to which it is driven by fluid withdrawal or sediment 

compaction resulting from the sedimentary pile pressing down on soft, unconsolidated sediments that 

causes downward and toward the basin movement along surfaces of detachment in the shallow and deep 

subsurface. 

Berman (2005) discussed the conclusions of Morton et al. (2005) and believed that they failed to 

make the case that hydrocarbon extraction caused substantial subsidence over the broader area of coastal 

Louisiana, a conclusion also reached by Gagliano (2005b). 

Cumulative Activities Scenario: Oil production on the LCA peaked at 513 million bbl in 1970 and 

gas production peaked at 7.8 MMcf in 1969 (Ko and Day, 2004b). From peak the level of activity is 

slowly decreasing. The magnitude of subsidence caused by formation extraction is a function of how 

pervasive the activity is across the LCA. The oil and gas field maps in Turner and Cahoon (1988, 

Figure 4) and Ko and Day (2004b, Figure 1) seem an adequate basis to estimate the LCA’s oil- and gasfield footprint at ~20 percent of the land area. The amount of subsidence from formation extraction is 

also occurring on a delta platform that is experiencing natural subsidence and sea-level rise. Fluid and 

gas extraction may lead to high local subsidence on the scale of individual oil and gas fields, but not as a 

pervasive contributor to regional subsidence across the LCA. 
Impact-Producing Factors and Scenario 3-69 

Mississippi River Hydromodification 

Chapter 4.1.3.3.2 of the Multisale EIS and Chapter 3.3.4 of the 2009-2012 Supplemental EIS discuss 

river development and flood control projects on the Mississippi River. The Mississippi River has been 

anchored in place by engineered structures built in the 20th century and has been hydrologically isolated 

from the delta it built. The natural processes that allowed the river to flood and distribute alluvial 

sediments across the delta platform and channels to meander have been shut down. Hydromodifying 

interventions include construction of (1) levees along the river and distributary channel systems, (2) 

upstream dams and flood control structures that impound sediment and meter the river flow rate, and (3) 

channelized channels with earthen or armored banks. Once the natural processes that act to add sediment 

to the delta platform to keep it emergent are shut down, subsidence begins to outpace deposition of 

sediment. 

Of total upstream-to-downstream flow, the Old River Control Structure (built 1963) diverts 70 

percent of flow down the levee-confined channels of the Mississippi River and 30 percent down the 

unconfined Atchafalaya River, which has been actively aggrading its delta plain since 1973 (LaCoast.gov, 

2011). Blum and Roberts reported that the time-averaged sediment load carried by the Mississippi and 

Atchafalaya Rivers pre-Old River Control Structure was ~400-500 million tons per year and that the 

average suspended load available to either river after the Old River Control Structure was ~205 million 

tons per year (Blum and Roberts, 2009, Figure 2). Modern sediment loads are, therefore, less than half 

that required to build and maintain the modern delta plain, a figure largely in agreement with previous 

work reporting decreases in suspended sediment load of nearly 60 percent since the 1950’s (Turner and 

Cahoon, 1987, Figure 3-8; Tuttle and Combe, 1981). 

Blum and Roberts (2009, Figure 3b) posited three scenarios for subsidence and sea-level rise, and 

concluded sediment starvation alone would cause ~2,286 mi2

 (592,071 ha) of the modern delta plain to 

submerge by 2050 without any other impacting factors contributing to landloss. The use of sediment 

budget modeling, a relatively new tool for landloss assessment, appears to indicate that hydrographic 

modification of the Mississippi River has been the most profound man-caused influence on landloss in the 

LCA. Sediment starvation of the deltaic system is allowing rising sea level and subsidence to outpace the 

constructive processes building and maintaining the delta. 

Cumulative Activities Scenario: The BOEMRE anticipates that, over the next 40 years, there might 

be minor sediment additions resulting from new and continuing freshwater diversion projects managed by 

COE. Of the 179 projects in the CWPPRA program (LaCoast.gov, 2010a), 27 involve introduction of 

sediment or reestablishment of natural water and sediment flow regimes to allow the delta plain to 

replenish and build up 10 are freshwater diversion projects, 5 are outfall management, 1 is sediment 

diversion, and 16 are marsh creations. Insofar as these projects represent land additions to the LCA, they 

are already accounted for in the discussion below under coastal restoration programs. 

Maintenance Dredging and Federal Channels 

Chapter 4.1.3.3.3 of the Multisale EIS and Chapter 3.3.4 of the 2009-2012 Supplemental EIS discuss 

maintenance dredging. 

There are 10 Federal navigation channels in the LCA, ranging in depth from 4 to 14 m (12 to 45 ft) 

and in width from 38 to 300 m (125 and 1,000 ft) that were constructed as public works projects 

beginning in the 1800’s (Good et al., 1995, Table 1). The combined length of the Federal channels in 

Good et al. was reported as 2,575 mi (1,600 km) with three canals considered deep-draft and seven as 

shallow (Good et al., 1995, p. 9). The Multisale EIS (USDOI, MMS, 2007b, p. 4-316) reported 1,243 mi 

(2,000 km) of OCS-related navigation channels. The Federal navigation channels in Louisiana identified 

by Good et al. (1995, Table 1) are as follows: (1) GIWW East of Mississippi River; (2) Mississippi River 

Gulf Outlet; (3) GIWW between the Atchafalaya and Mississippi Rivers; (4) GIWW West of Atchafalaya 

River; (5) Barataria Bay Waterway; (6) Bayou Lafourche; (7) Houma Navigation Canal; (8) Mermentau 

Navigation Channel; (9) Freshwater Bayou; and (10) Calcasieu River Ship Channel. 

Turner and Cahoon (1987, Table 4-1) and DOI (USDOI, MMS, 2007b, Table 3-36) identified OCSrelated channels that bore traffic supporting the OCS Program. Between these works and Good et al. 

(1995, Table 1) channel names do not well agree and a comparison is difficult. No channel is exclusively 

used by OCS Program traffic and only a fraction of total traffic is attributable to OCS use; approximately 

12 percent (USDOI, MMS, 2007b, p. 4-316). The BOEMRE staff compiled Table 3-15 using the 
3-70 Central Planning Area Supplemental EIS

information in industry plans to show that, between 2003 and 2008, the vast majority (80-90%) of OCS 

service vessels used service-base facilities in the LCA that are located along rivers or that lie within 

wetlands that are already saline or brackish. Table 3-15 shows that the contribution of OCS Program 

traffic to bank degradation and freshwater wetland loss is minimal. 

The GIWW is a Federal, shallow-draft navigation channel constructed to provide a domestic 

connection between Gulf ports after the discovery of oil in East Texas in the early 1900’s, as well as the 

growing need for interstate transport of steel and other manufacturing materials. It extends approximately 

1,400 mi (2,253 km) along the Gulf Coast from St. Marks in northwestern Florida to Brownsville, Texas, 

with the Louisiana part reported to be 994 mi (1,600 km) in length (Good et al., 1995, p. 9). With the 

exception of the east-west GIWW in Louisiana, Federal channels are sub-perpendicular with the GOM 

shoreline or saltwater bays, making them vulnerable to saltwater intrusion during storms. 

Direct cumulative impacts include the displacement of wetlands by original channel excavation and 

disposal of the dredged material. Good et al. (1995, Table 1) estimated that direct impacts from the 

construction of Federal navigation channels were between 58,000 and 96,000 ac (23,472 and 38,850 ha). 

Indirect cumulative landlosses resulted from hydrologic modifications, saltwater intrusion, or bank 

erosion from vessel wakes (Wang, 1988). Once cut, navigation canals tend to widen as banks erode and 

subside, depending on the amount of traffic using the channel. Good et al. (1995, Table 1) estimated 

indirect impacts on wetland loss from bank erosion at 35,000 ac (14,164 ha). 

The COE reported that the New Orleans District has the largest channel maintenance dredging 

program in the U.S., with an annual average of 70 million yd3

 of material dredged (U.S. Dept. of the 

Army, COE, 2009a, p. 26). Of that total, COE’s Ocean Disposal Database indicates that about 16 million 

yd3

 were disposed at ODMDS sites by the New Orleans District (U.S. Dept. of the Army, COE, 2011a) 

(Chapter 3.3.3). Federal channels and canals are maintained throughout the onshore cumulative impact 

area by COE, State, county, commercial, and private interests. Proposals for new and maintenance 

dredging projects are reviewed by COE, State, and local agencies as well as by private and commercial 

interests to identify and mitigate adverse impacts upon social, economic, and environmental resources. 

Maintenance dredging is performed on an as-needed basis. Typically, COE schedules surveys every 

2 years on each navigation channel under its responsibility to determine the need for maintenance 

dredging. Dredging cycles may be from 1 to as many as 11 years from channel to channel and from 

channel segment to channel segment. The COE is charged with maintaining all larger navigation 

channels in the cumulative activities area. The COE dredges millions of cubic meters of material per year 

in the cumulative activities area, most of which is under the responsibility of the New Orleans District. 

Some shallower port-access channels may be deepened over the next 10 years to accommodate deeper 

draft vessels. Vessels that support deepwater OCS activities may include those with drafts to about 7 m 

(23 ft). 

Construction and maintenance dredging of rivers, navigation channels, and pipeline access canals can 

furnish sediment for beneficial purpose, a practice the COE calls beneficial use of dredge materials 

program. Drilling, production activity, and maintenance at most coastal well sites in Louisiana require 

service access canals that undergo some degree of aperiodic maintenance dredging to maintain channel 

depth, although oil and gas production on State lands peaked in 1969-1970 (Ko and Day, 2004b, p. 398). 

In recent years, dredged materials have been sidecast to form new wetlands using the beneficial use of 

dredge materials program. Potential areas suited for beneficial use of dredged material are considered 

most feasible within a 10-mi (16-km) boundary around authorized navigation channels in the New 

Orleans District, but the potential for future long distance pipelines for disposal of dredged material could 

increase the potential area available for the beneficial use of dredge materials program considerably 

(U.S. Dept. of the Army, COE, 2009a, p. 27). 

Current figures vary for how much of the average annual 70 million yd3

 (53,518,840 m3) that is 

dredged by the New Orleans District is available for the beneficial use of dredge materials program: from 

15 million yd3

 (11,468,320 m3) (U.S. Dept. of the Army, COE, 2009a, p. 26) to 30 million yd3

(22,936,650 m3

) (Green, 2006, p. 6), or between 21 and 43 percent of the total. The COE reported that, 

over the last 20 years, approximately 10,117 ha (25,000 ac) of wetlands have been created with dredged 

materials, most of which are located on the LCA delta plain (U.S. Dept. of the Army, COE, 2009c, p. 8). 

Cumulative Activities Scenario: The construction of Federal channels is not a growth industry and at 

least one Louisiana channel (Mississippi River Gulf Outlet) has been decommissioned and sealed with a 

rock barrier as of July 2009 (Shaffer et al., 2009, p. 218). The DOI has used a widening rate for OCS-
Impact-Producing Factors and Scenario 3-71 

related channels of 1.5 m/yr (4.9 ft/yr) (USDOI, MMS, 2007b, p. 4-316). Using DOI’s estimate of 

2,000,000 m (1,243 mi) of OCS-related channel length (USDOI, MMS, 2007b, p. 4-316) and the 

estimated bank widening rate of 1.5 m/yr (5 ft/yr) for OCS-related channels, an annual landloss of 

~741 ac/yr (300 ha/yr) may be estimated. During the 40-year cumulative activities scenario, landloss 

from indirect impacts on Federal navigation channels could be ~29,653 ac (12,000 ha). The use of 

Federal channels by OCS-related traffic is ~12 percent of total capacity, and an estimate may be made for 

the OCS Program’s contribution to bank erosion over the 40 year cumulative scenario of 355 ha (877 ac). 

The BOEMRE anticipates that, over the next 40 years, if current trends in use of dredged sand and 

sediment for the beneficial use of dredge materials program are simply projected based on past land 

additions and if there is no change in the average annual rate of wetland creation or protection with this 

program, approximately ~50,000 ac (20,234 ha) may be created or protected in the LCA. Subtracting 

projected land added from land lost, an estimated net landloss of ~9,419 ha (23,274 ac) between the years 

2007-2046 could occur between land lost by bank degradation and channel widening and land added 

using the beneficial use of dredge materials program. 

Coastal Restoration Programs 

Chapter 4.1.3.3.4 of the Multisale EIS and Chapter 3.3.5 of the 2009-2012 Supplemental EIS discuss 

coastal restoration. The Mississippi Delta sits atop a pile of Mesozoic and Tertiary-aged sediments up to 

7.5 mi (12.2 km) thick at the coast and it may be as much as 60,000 ft (18,288 m) or 11.4 mi (18.3 km) 

thick offshore (Gagliano, 1999). Five major lobes are generally recognized within about the uppermost 

50 m (164 ft) of sediments (Britsch and Dunbar, 1993; Frazier, 1967, Figure 1). The oldest lobe contains 

peat deposits dated as 7,240 years old (Frazier, 1967, p. 296). The youngest delta lobe of the Mississippi 

Delta is the Plaquemines-Balize lobe that has been active since the St. Bernard lobe was abandoned about 

1,000 years ago. The lower Mississippi River has shifted its course to the Gulf of Mexico every thousand 

years or so, seeking the most direct path to the sea while building a new deltaic lobe. Older lobes were 

abandoned to erosion and subsidence as the sediment supply was shut off. Because of the dynamics of 

delta building and abandonment, the Louisiana coastal area (U.S. Dept. of the Army, COE, 2004a) 

experiences relatively high rates of subsidence relative to more stable coastal areas eastward and 

westward. 

The first systematic program authorized for coastal restoration in the LCA was the 1990 Coastal 

Wetlands Planning, Protection and Restoration Act (CWPPRA), otherwise known as the “Breaux Act.” 

Individual CWPPRA projects are designed to protect and restore between 10 and 10,000 ac (4 and 4,047 

ha), require an average of 5 years to transition from approval to construction, and are funded to operate 

for 20 years (U.S. Government Accountability Office, 2007, p. 2), a typical expectation for project 

effectiveness (Campbell et al., 2005, p. 245). 

The 1990 CWPPRA introduced an ongoing program of relatively small projects to partially restore 

the coastal ecosystem. As the magnitude of Louisiana’s coastal landlosses and ecosystem degradation 

became more apparent, so too appeared the need for a more systematic approach to integrate smaller 

projects with larger projects to restore natural geomorphic structures and processes. The Coast 2050 

report (Louisiana Dept. of Natural Resources, 1998) combined previous restoration planning efforts with 

new initiatives from private citizens, local governments, State and Federal agency personnel, and the 

scientific community to converge on a shared vision to sustain the coastal ecosystem. The LCA 

Ecosystem Restoration Study (U.S. Dept. of the Army, COE, 2004a) built upon the Coast 2050 Report. 

The LCA’s restoration strategies generally fell into one of the following categories: (1) freshwater 

diversion; (2) marsh management; (3) hydrologic restoration; (4) sediment diversion; (5) vegetative 

planting; (6) beneficial use of dredge material; (7) barrier island restoration; (8) sediment/nutrient 

trapping; and (9) shoreline protection, as well as other types of projects (Louisiana Coastal Wetlands 

Conservation and Restoration Task Force, 2006, Table 1). 

Following Hurricanes Katrina and Rita in 2005, an earlier emphasis on coastal or ecosystem 

restoration of the LCA was reordered to at least add an equal emphasis on hurricane flood protection. In 

late 2005, the Department of Defense Appropriations Act of 2006 authorized COE to develop a 

comprehensive hurricane protection analysis to present a full range of flood control, coastal restoration, 

and hurricane protection measures for south Louisiana (U.S. Dept. of the Army, COE, 2009b). The 

Appropriations Act required Louisiana to create a State organization to sponsor the hurricane protection 
3-72 Central Planning Area Supplemental EIS

and restoration projects that resulted. The State legislature established the Coastal Protection and 

Restoration Authority and charged it with coordinating the efforts of local, State, and Federal agencies to 

achieve long-term, integrated flood control and wetland restoration. The Coastal Protection and 

Restoration Authority produced a comprehensive master plan for a sustainable coast (State of Louisiana, 

2007) as their vision of an integrated program of what had been separate areas of activity—flood 

protection and coastal restoration. The Coastal Protection and Restoration Authority’s Annual Plans 

prioritize the types of projects undertaken each fiscal year. It is not entirely clear how coordination 

between the State and Federal authorities is undertaken in order to develop the range of projects selected 

for the State’s Coastal Protection and Restoration Authority’s Annual Plan and COE’s plan (U.S. Dept. of 

the Army, COE, 2009a, Figures 17-1, 17-2, and 17-3). 

The U.S. Government Accountability Office (GAO) recently audited the CWPPRA Program (U.S. 

Government Accountability Office, 2007). The GAO reported 74 completed CWPPRA projects between 

1994 and 2007 that resulted in 58,781 “anticipated total acres” (23,788 ha) and 16 projects under 

construction as of mid-2007 that are reported to result in 20,860 anticipated total acres (8,442 ha) (U.S. 

Government Accountability Office, 2007, Tables 2 and 3). Of the 74 projects constructed since 1994, 

more than half were one of two types—shoreline protection or hydrologic restoration. Of the 179 

CWPPRA priority projects listed on LaCoast.gov (2010b), 55 projects with 31,187 ac (12,621 ha) “total 

net acres” (defined as the sum of reestablished and protected acres present at the end of 20 years) are not 

found on GAO’s completed or underway lists (U.S. Government Accountability Office, 2007, Tables 2 

and 3), leading to a conclusion that these projects are in line for completion before 2019. 

Cumulative Activities Scenario: The BOEMRE’s anticipates that, over the next 40 years, ~12,621 ha 

(31,187 ac) of land would be added, or 316 ha/yr (781 ac/yr) between now and 2019. This estimate is 

based in the assumption that the full menu of 179 CWPPRA projects now anticipated (LaCoast.gov, 

2010b) are completed by the end of the authorization period in 2019. 

There is no simple way to anticipate what projects under the protection of the State’s Coastal 

Protection and Restoration Authority are admitted to its Annual Plan and completed. There is also no 

simple way to anticipate what projects are undertaken for COE’s comprehensive range of flood control, 

coastal restoration, and hurricane protection measures for the LCA will feed into the Coastal Protection 

and Restoration Authority’s Annual Plan for authorization and which ones will be ultimately completed. 

Because these projects are chosen on the basis of annual appropriations, there is no simple way to 

establish projections for land added or preserved over the cumulative activities scenario.

Coastal Impact Assistance Program 

The Energy Policy Act of 2005 was signed into law by President Bush on August 8, 2005. Section 

384 of EPAct amended Section 31 of the OCSLA (43 U.S.C. 1356(a)) to establish the Coastal Impact 

Assistance Program (CIAP). The authority and responsibility for the management of CIAP is vested in 

the Secretary of the Interior; the Secretary delegated this authority and responsibility to this Agency. 

Under EPAct Section 384, this Agency was directed to disburse $250 million for each of the fiscal years 

(FY) 2007 through 2010 to eligible OCS oil- and gas-producing States and coastal political subdivisions 

(CPS’s). 
Impact-Producing Factors and Scenario 3-73 

Eligible CIAP States Eligible CIAP Coastal Political Subdivisions 

Alabama Baldwin and Mobile Counties 

Alaska Municipality of Anchorage and Bristol Bay, Kenai Peninsula, Kodiak Island, Lake 

and Peninsula, Matanuska-Susitna, North Slope, and Northwest Arctic Boroughs 

California 

Alameda, Contra Costa, Los Angeles, Marin, Monterey, Napa, Orange, San Diego, 

San Francisco, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, 

Solano, Sonoma, and Ventura Counties 

Louisiana 

Assumption, Calcasieu, Cameron, Iberia, Jefferson, Lafourche, Livingston, Orleans, 

Plaquemines, St. Bernard, St. Charles, St. James, St. John the Baptist, St. Martin, St. 

Mary, St. Tammany, Tangipahoa, Terrebonne, and Vermilion Parishes 

Mississippi Hancock, Harrison, and Jackson Counties 

Texas 

Aransas, Brazoria, Calhoun, Cameron, Chambers, Galveston, Harris, Jackson, 

Jefferson, Kenedy, Kleberg, Matagorda, Nueces, Orange, Refugio, San Patricio, 

Victoria, and Willacy Counties 

The funds allocated to each State are based on the proportion of qualified OCS revenues (QOCSR) 

offshore the individual State to total QOCSR from all States. The EPAct requires a minimum allocation 

of 1 percent to each State and provides that 35 percent of each State’s allocation be shared by its CPS’s. 

Table 3-16 shows the allocation of CIAP funds by fiscal year to each of the six eligible States and 67 

eligible CPS’s. 

A State, in cooperation with its CPS’s, must submit to BOEMRE for approval a CIAP State Plan 

(Plan) that describes how it will spend its CIAP funds. A State or CPS shall use all amounts received 

under CIAP for one or more of the following purposes: (1) projects and activities for the conservation, 

protection, or restoration of coastal areas, including wetland; (2) mitigation of damage to fish, wildlife, or 

natural resources; (3) planning assistance and the administrative costs of complying with this section; (4) 

implementation of a federally approved marine, coastal, or comprehensive conservation management 

plan; and (5) mitigation of the impact of OCS activities through funding of onshore infrastructure projects 

and public service needs. 

Once a Plan is approved, a State and its CPS’s are eligible to submit grant applications for the 

projects described in its Plan. All six States have approved Plans. Currently, Alaska, California, 

Louisiana, and Mississippi have approved FY 2007-2010 Plans and are eligible to submit grant 

applications for their FY 2007-2010 allocated funds. Alabama has an approved FY 2007-2008 Plan and 

therefore may only submit grant applications for its FY 2007-2008 funds, while Texas has an approved 

FY 2007 Plan and may only submit grant applications for its FY 2007 funds. From total allocated funds, 

Table 3-17 shows the dollar amount of CIAP funds applied for, awarded, under review, and remaining 

for each Gulf State and CPS. 

The Gulf Coast Ecosystem Restoration Task Force 

The Gulf Coast Ecosystem Restoration Task Force was set up by an Executive Order signed by 

President Obama on October 5, 2010 (The White House, 2010). The Task Force stated the Federal 

Government’s desire to address longstanding ecological decline and begin moving toward a more resilient 

Gulf Coast ecosystem, especially in the aftermath of the DWH event. The Executive Order expressed the 

Federal Government’s commitment to help residents conserve and restore resilient and healthy GOM 

ecosystems that support and sustain the diverse economies, communities, and cultures of the region and 

the important national missions carried out in the GOM. 

The specific goals of the Task Force are to support economic vitality, enhance human health and 

safety, protect infrastructure, enable communities to better withstand impact from storms and climate 

change, sustain safe seafood and clean water, provide recreational and cultural opportunities, protect and 

preserve sites that are of historical and cultural significance, and contribute to the overall resilience of 

coastal communities. To support and enable these goals, the Task Force’s role is to coordinate 

intergovernmental responsibilities, planning, and exchange of information so as to better implement 

ecosystem restoration and to facilitate appropriate accountability and support throughout the restoration 

process. The Executive Order directed Federal efforts to be efficiently integrated with those of local 
3-74 Central Planning Area Supplemental EIS

stakeholders, and that particular focus should be toward innovative solutions for complex, large-scale 

restoration projects. The Executive Order seeks science-based and well-coordinated solutions that 

minimize duplication and ensure effective delivery of services. 

The Executive Order explicitly identified the following Federal agencies and groups as participating 

in Task Force: (1) Department of Defense; (2) Department of Justice; (3) Department of the Interior; (4) 

Department of Agriculture; (5) Department of Commerce; (6) Department of Transportation; (7) 

Environmental Protection Agency; (8) Office of Management and Budget; (9) Council on Environmental 

Quality; (10) Office of Science and Technology Policy; (11) Domestic Policy Council; and (12) other 

executive departments, agencies, and offices as the President may, from time to time, designate. In 

addition to these designated Federal participants, representatives of the five Gulf Coast States may be 

appointed by the President upon recommendation of the Governors of each state. These representatives 

are to be elected officers of State governments (or their designated employees with authority to act on 

their behalf) acting in their official capacities. The Task Force may include representatives from affected 

tribes, who are elected officers of those tribes (or their designated employees with authority to act on their 

behalf) acting in their official capacities. The Task Force shall, in collaboration with affected tribes, 

determine an appropriate structure for tribal participation in matters within the scope of the Task Force’s 

responsibilities. No State or tribal representatives have yet been identified for the Task Force. 

The Task Force held its inaugural meeting on November 8, 2010, at the Pensacola Civic Center in 

Pensacola, Florida. Attendees were reported as numbering approximately 250. The meeting was chaired 

by Ms. Lisa Jackson, USEPA Administrator, for whom the Task Force serves. The agency 

representatives for the federally designated agencies and groups introduced themselves as did the staff 

director for the Task Force. Pre-meeting materials provided to participants who had responded to an open 

and widely distributed announcement and invitation were provided with the two orders of business that 

Ms. Jackson wished the first meeting to focus upon. 

(1) How in the coming months can the Task Force best enable the widest possible 

participation in this process? How can the Task Force best connect to keep everyone 

informed and to ensure good two-way communication? 

(2) Which of the many critical substantive issues about restoration should the Task Force 

focus on first? Which ones rise to the top for immediate attention knowing that all of 

them will be eventually have to be addressed? 

Assistant Secretary for Fish and Wildlife and Parks (at that time Thomas Strickland) was the point of 

contact for DOI’s involvement in the Task Force. Mr. Strickland reported that, as of November 8, 2010, 

9,000 people were still employed in spill cleanup activity; 3,000 DOI staff had, at one time or another, 

been involved in spill response or cleanup activity; and 580 mi (933 km) of shoreline were still 

undergoing cleaning activities. The BOEMRE sent six staff scientists to attend the November 8 meeting, 

but this Agency is not now identified as a participant. 

Some of the insights gathered at the first Task Force meeting are as follows: (1) the Task Force 

wanted to receive as much bottoms-up input as they could so that they could formulate how they think the 

Task Force would operate; (2) there is no current budget for the Task Force and the staff conducting the 

work supported by their host agencies, and (3) the outputs are not yet defined. At this early point, the 

Task Force appears to view their role as coordination and information sharing for already approved or 

established planning efforts, such as coastal restoration projects administrated by COE and the State of 

Louisiana, or the CIAP administered by BOEMRE. 

Ms. Jackson’s closing remarks stated that Task Force members and staff were now obligated to 

answer the many questions elicited from the inputs requested by Ms. Jackson’s two orders of business for 

the first meeting. Much useful input was received on Ms. Jackson’s question, “How can the Task Force 

best connect to keep everyone informed and to ensure good two-way communication?” The inputs 

received on question 2, “What should the Task Force focus on first?” was very general and conceptual 

and did not seem to elicit as much useful information for the Task Force’s next steps. The Task Force has 

a website (www.restorethegulf.com) to keep observers aware of its activities. 
Impact-Producing Factors and Scenario 3-75 

3.3.5. Natural Events or Processes 

3.3.5.1. Hurricanes 

Chapter 3.3.5.7.3 of the Multisale EIS and Chapter 3.1.1.5.3 of the 2009-2012 Supplemental EIS 

discuss damage to infrastructure from recent hurricanes. Climatic cycles in tropical latitudes typically last 

20-30 years, or even longer (USDOC, NOAA, 2005). As a result, North Atlantic experiences alternating 

periods of above-normal or below-normal hurricane seasons. There is a two- to three-fold increase in 

hurricane activity during eras of above-normal activity. The hurricane activity from 1995 to 2007 is 

representative of an era of above-normal hurricane activity (Elsner et al., 2008, p. 1,210). 

Seventeen hurricanes made landfall in the WPA or CPA during the 1995-2009 hurricane seasons, 

disrupting OCS oil and gas activity in the GOM (Table 3-18). Half of these hurricanes reached a 

maximum strength of Category 1 or 2 while in the CPA or WPA, while the other half were powerful 

hurricanes reaching maximum strengths of Categories 4 or 5. The current era of heightened Atlantic 

hurricane activity began in 1995; therefore, the GOM could expect to see a continuation of above-normal 

hurricane activity during the first 10-20 years of the 40-year analysis period and below-normal activity 

during the remaining 20-30 years of the 40-year analysis period. 

Hurricanes Ivan, Katrina, Rita, Gustav, and Ike caused extensive damage to OCS platforms, topside 

facilities, and pipeline systems (Table 3-19). During Hurricanes Ivan, Katrina, and Rita, 9 jack-up rigs 

and 19 moored rigs were either toppled or torn from their mooring systems. Sixty platforms were 

destroyed as a result of Hurricanes Gustav and Ike in 2008. 

After the 2005 hurricanes, this Agency set forth guidance to ensure compliance with 30 CFR 250.417 

and to improve performance in the area of jack-up and moored rig station-keeping during the 

environmental loading that may be experienced during hurricanes. Industry, USCG, and this Agency 

worked together to develop interim recommended practices for the use of jack-up and moored rigs during 

the future hurricane seasons to potentially decrease the amount of failures during hurricanes. This 

Agency issued NTL 2006-G10, “Moored Drilling Rig Fitness Requirements for the 2006 Hurricane 

Season,” and NTL 2006-G09, “Jack-up Drilling Rig Fitness Requirements for the 2006 Hurricane 

Season.” These NTL’s provide guidance on the information operators must submit with the application 

for permit to drill to demonstrate the fitness of any jack-up or moored drilling rig to conduct drilling, 

workover, or completion operations in the Gulf of Mexico OCS during the 2006 hurricane season, and 

beyond, that remain applicable until revised. These NTL’s represent a small part of the response to 

review and provide guidance to operators for MODU requirements and reporting in light of the recent 

experiences from damage caused by recent hurricanes. 

3.3.5.2. Currents as Transport Agents 

Physical oceanographic processes in the GOM contributing to the distribution of spilled oil include 

the Loop Current, Loop Current eddies, and whirlpool-like features underneath the LC and LCE’s that 

interact with the bottom. Infrequently observed processes include a limited number of high-speed current 

events, at times approaching 100 cm/s (39 in/s). These events were observed at depths exceeding 1,500 m 

(4,921 ft) in the northern GOM (Hamilton and Lugo-Fernandez, 2001; Hamilton et al., 2003) and as very 

high-speed currents in the upper portions of the water column observed in deep water by several oil and 

gas operators. All of these processes are described in Appendix A.2 of the Multisale EIS. Generally, 

current speed in the deep GOM has been observed to decrease with depth. Mean deep flow around the 

edges of the GOM circulates in a counterclockwise direction at ~2,000 m (6,562 ft) (Sturges et al., 2004) 

and at ~900 m (2,953 ft) (Weatherly, 2004). 

Mean seasonal circulation patterns of inner-shelf and outer-shelf currents on the Louisiana-Texas 

continental shelf, the northeastern GOM shelf, and the West Florida shelf are described in Appendix A.2 

of the Multisale EIS. These currents are primarily wind driven and are also influenced by riverine 

outflow. Cold water from deeper off-shelf regions moves onto and off the continental shelf by cross-shelf 

flow associated with upwelling and downwelling processes in some locations (Collard and LugoFernandez, 1999). Wind events such as tropical cyclones (especially hurricanes), extratropical cyclones, 

and cold-air outbreaks can result in extreme waves and cause currents with speeds of 100-150 cm/s 

(39-59 in/s) over continental shelves. Wave heights of 91 ft (28 m) were measured during the passage of 

Hurricane Ivan through the northern GOM (Wang et al., 2005). 
3-76 Central Planning Area Supplemental EIS

The physical oceanography of the GOM, and the natural processes that may influence the cumulative 

activities scenario, was discussed in Chapter 3.3.7.1 of the 2009-2012 Supplemental EIS. Since that time, 

several new reports on circulation of the Gulf’s deep waters have been completed. The main findings 

from such studies are as follows: (1) the deep Gulf can be approximated as a two-layer system with an 

upper layer about 800- to 1,000-m (2,625- to 3,281-ft) thick that is dominated by the Loop Current and 

associated clockwise whirlpools (Cox et al., in press; Welsh et al., 2009; Inoue et al., 2008); (2) the lower 

layer below ~1,000 m (3,281 ft) has near uniform currents (Cox et al., in press; Welsh et al., 2009; Inoue 

et al., 2008); (3) the coupling between these two layers is generally absent, but it seems that motions of 

the layer interface are needed to transmit the energy from the Loop Current and eddies downward (Cox et 

al., in press; Welsh et al., 2009; Inoue et al., 2008, Donohue et al., 2008); (4) there is a wealth of 

secondary whirlpools with smaller diameters (50-100 km; 31-62 mi) that affect the exchange between the 

shelf and deepwater, and these smaller whirlpools interact with the larger Loop eddies (Donohue et al., 

2008); and (5) the ocean’s response to tropical storms and hurricanes is similar to that reported 

previously, but a new mode was found to transport the hurricane’s energy downward related to the sealevel rise near the storm eye (Welsh et al., 2009; Cole and DiMarco, 2010). 

Caribbean Sea waters colliding with the Yucatan Peninsula turn northward and enter the Yucatan 

Channel as a strong flow called the Yucatan Current. This current exhibits two basic arrangements inside 

the GOM. First, the Yucatan Current enters the Gulf and turns immediately eastward, exiting the Gulf 

towards the Atlantic Ocean via the Florida Straits to become the Gulf Stream. The second arrangement 

consist of a northward penetration of the Yucatan Current into the Gulf reaching to 26o-28oN latitudes, 

then curls clockwise turning south, and exiting via the Florida Straits into the Atlantic Ocean to become, 

again, the Gulf Stream. The stream inside the Gulf is called the Loop Current. The Loop Current 

transports warm and salty water year round into the GOM at a rate of 25-30 million cubic meters per 

second, and it is the main energy source for oceanographic processes inside the Gulf. At its climatic 

northern position, the Loop becomes unstable, breaks, and sheds a large (200- to 400-km diameter 

[124- to 248-mi diameter]) clockwise whirlpool that travels southwestwards at speeds of 4-8 km/day 

(2-5mi/day). The southwest trip of Loop Current eddies continues until colliding with the Texas and 

Mexico continental slope in the western GOM, where they disintegrate. This sequence connects the 

eastern with the western Gulf, which otherwise appear disconnected. 
CHAPTER 4 

DESCRIPTION OF THE ENVIRONMENT

AND IMPACT ANALYSIS
Description of the Environment and Impact Analysis 4-3 

4. DESCRIPTION OF THE ENVIRONMENT AND IMPACT ANALYSIS 

The impacts of 11 WPA and CPA sales were analyzed in the Gulf of Mexico OCS Oil and Gas Lease 

Sales: 2007-2012; Western Planning Area Sales 204, 207, 210, 215, and 218; Central Planning Area 

Sales 205, 206, 208, 213, 216, and 222, Final Environmental Impact Statement (Multisale EIS; USDOI, 

MMS, 2007b). An analysis of the routine, accidental, and cumulative impacts of a WPA or CPA 

proposed action on the environmental and socioeconomic resources of the Gulf of Mexico can be found in 

Chapters 4.2, 4.4, and 4.5 of the Multisale EIS, respectively. The Multisale EIS was supplemented by the 

Gulf of Mexico OCS Oil and Gas Lease Sales: 2009-2012; Central Planning Area Sales 208, 213, 216, 

and 222; Western Planning Area Sales 210, 215, and 218; Final Supplemental Environmental Impact 

Statement (2009-2012 Supplemental EIS; USDOI, MMS, 2008a) and included an analysis on the 181 

South Area that was made available for leasing through the Gulf of Mexico Energy Security Act of 2006. 

An analysis of the routine, accidental, and cumulative impacts of a CPA or WPA proposed action on the 

environmental and socioeconomic resources of the Gulf of Mexico can be found in Chapter 4 of the 2009-

2012 Supplemental EIS. The Multisale EIS and the 2009-2012 Supplemental EIS are hereby 

incorporated by reference. 

The purpose of this Supplemental EIS is to determine if new information is substantial enough to alter 

the conclusions stated in the Multisale EIS and the 2009-2012 Supplemental EIS and, if so, to disclose 

those changes. This includes all new information and not just that acquired since the DWH event. This 

Supplemental EIS was prepared in consideration of the potential changes to the baseline conditions of the 

environmental, socioeconomic, and cultural resources that may have occurred as a result of the DWH

event. The environmental resources include sensitive coastal environments, offshore benthic resources, 

marine mammals, sea turtles, coastal and marine birds, endangered and threatened species, and fisheries. 

This Supplemental EIS also considered the DWH event in the analysis of the potential alternatives of the 

proposed action. 

It must be understood that this Supplemental EIS analyzes the proposed action and alternatives for the 

proposed CPA lease sale. This is not an EIS on the DWH event, although information on this event is 

being analyzed as it applies to resources in the CPA. 

4.1. PROPOSED CENTRAL PLANNING AREA LEASE SALE 216/222 

Proposed CPA Lease Sale 216.222 is scheduled to be held in 2012. The CPA lease sale area 

encompasses about 63 million ac of the CPA’s 66.3 million ac located 3 nmi offshore Louisiana, 

Mississippi, and Alabama and extends seaward to the limits of the EEZ in water depths up to 3,458 m 

(11,345 ft) (Figure 1-1). This proposed CPA lease sale would offer for lease all unleased blocks in the 

CPA for oil and gas operations (Figure 1-1), with the following exceptions: 

(1) blocks directly south of Florida and within 100 mi of the Florida coast (north of the 

easternmost portion of the CPA sale area as shown on Figure 1-1); 

(2) blocks that are beyond the U.S. Exclusive Economic Zone in the area known as the 

northern portion of the Eastern Gap. 

Chapter 4.1 presents baseline data for the physical, biological, and socioeconomic resources that 

would potentially be affected by proposed CPA Lease Sale 216/222 or the alternatives, and it presents 

analyses of the potential impacts of routine events, accidental events, and cumulative activities on these 

resources. Baseline data are considered in the assessment of impacts from proposed CPA Lease Sale 

216/222 on these resources. 

During the past few years, the Gulf Coast States and GOM oil and gas activities have been impacted 

by several major storms and hurricanes. Appendix A.3 of the Multisale EIS provides information on 

Hurricanes Lili (2002), Ivan (2004), Katrina (2005), and Rita (2005). In 2008, Hurricanes Gustav and Ike 

also impacted OCS infrastructure (Chapter 3.3.7.2). The description of the affected environment below 

includes impacts from these storms on the physical, biological, and socioeconomic resources. 
4-4 Central Planning Area Supplemental EIS 

The DWH event off the Louisiana coast resulted in the largest oil spill in U.S. history. 

Approximately 4.9 million barrels flowed into the Gulf over a period of 87 days. An event such as this 

has the potential to adversely affect multiple resources over a large area. The level of adverse effect 

depends on many factors, including the sensitivity of the resource. All effects may not initially be seen 

and some could take years to fully develop. The analyses of impacts from the DWH event on the 

physical, biological, and socioeconomic resources below are based on information known at this time. 

However, the effects of proposed CPA Lease Sale 216/222 on these resources are expected to be 

substantially the same as those presented in the Multisale EIS, even when considered in the context of the 

DWH event. The BOEMRE will continue to monitor these resources for effects caused by the DWH 

event. 

Chapter 4.1.3.4.4 of the Multisale EIS provides information on accidental spills that could result from 

all operations conducted under the OCS Program, as well as information on the number and sizes of spills 

from non-OCS sources. The number of spills ≥1,000 bbl and >10,000 bbl estimated to occur as a result 

of the CPA proposed action is provided in Table 3-5. The mean number of spills estimated for the 

proposed action in the CPA is 1-3 spills (≥1,000 bbl) and <1-1 spill (10,000 bbl). Figure 4-12 of the 

Multisale EIS provides the probability of a particular number of offshore spills ≥1,000 bbl occurring from 

facility or pipeline operations in the CPA. Spill rates for all of the spill-size categories are provided in 

Table 4-16 of the Multisale EIS. The probabilities of a spill ≥1,000 bbl occurring and contacting modeled 

environmental resources are described in Chapter 4.3.1.5.7 and Figures 4-14 through 4-31 of the 

Multisale EIS. 

The potential impacts of a low-probability, large oil-spill event, such as the DWH event, to the 

environmental resources and socioeconomic conditions listed above are fully addressed in the 

“Catastrophic Spill Event Analysis” (Appendix B). The reader is referred to Appendix B for the analysis 

of a potential effect of a catastrophic event for each resource. 

The following cumulative analyses consider impacts to physical, biological, and socioeconomic 

resources that may result from the incremental impact of proposed CPA Lease Sale 216/222 when added 

to all past, present, and reasonably foreseeable future human activities, including non-OCS activities, as 

well as all OCS activities (OCS Program). Non-OCS activities include, but are not limited to, import 

tankering; State oil and gas activity; recreational, commercial, and military vessel traffic; offshore LNG 

activity; recreational and commercial fishing; onshore development; and natural processes. The OCS 

Program scenario includes all activities that are projected to occur from past, proposed, and future lease 

sales during the 40-year analysis period (2007-2046). This includes projected activity from lease sales 

that have been held, but for which exploration or development has not yet begun or is continuing. 

Analytical Approach 

The analyses of potential effects to the wide variety of physical, environmental, and socioeconomic 

resources in the vast area of the GOM and adjacent coastal areas is very complex. Specialized education, 

experience, and technical knowledge are required, as well as familiarity with the numerous impactproducing factors associated with oil and gas activities and other activities that can cause cumulative 

impacts in the area. Knowledge and practical working experience of major environmental laws and 

regulations such as NEPA, the Clean Water Act, CAA, CZMA, ESA, MMPA, the Magnuson-Stevens 

Fishery Conservation and Management Act, and others is also required. 

In order to accomplish this task, BOEMRE has assembled a multidisciplinary staff with hundreds of 

years of experience. The vast majority of this staff has advanced degrees with a high level of knowledge 

related to the particular resources discussed in this chapter. This staff prepares the input to BOEMRE’s 

lease sale EIS’s, a variety of subsequent postlease NEPA reviews, and are also involved with ESA, EFH, 

and CZMA consultations. In addition, this same staff is also directly involved with the development of 

studies conducted by BOEMRE’s Environmental Studies Program. The results of these studies feed 

directly into our NEPA analyses. To date, since 1973, approximately $251 million has been spent on 

physical, environmental, and socioeconomic studies in the Gulf of Mexico OCS Region. There are 

currently 96 ongoing studies in the Gulf of Mexico OCS Region, at a cost of about $46 million. A great 

deal of baseline knowledge about the GOM and the potential effects of oil and gas activities are the direct 

result of these studies. In addition to the studies staff, BOEMRE also has a Scientific Advisory 
Description of the Environment and Impact Analysis 4-5 

Committee consisting of recognized experts in a wide variety of disciplines. The Scientific Advisory 

Committee has input to the development of the Environmental Studies Program on an ongoing basis. 

For each lease sale EIS, a set of assumptions and a scenario are developed, and impact-producing 

factors that could occur from routine oil and gas activities, as well as accidental events, are described. 

This information is discussed in detail in Chapter 3. Using this information, the multidisciplinary staff 

described above applies their knowledge and experience to conduct their analyses of the potential effects 

of the proposed lease sale. 

The conclusions developed by the subject-matter experts regarding the potential effects of the 

proposed lease sale for most resources are necessarily qualitative in nature; however, they are based on 

the expert opinion and judgment of highly trained subject-matter experts. This staff approaches this effort 

in good faith utilizing the best information available to them. Over the years, a suite of lease stipulations 

and mitigation measures has been developed to eliminate or ameliorate potential environmental effects. 

In many instances, these were developed in coordination with other natural resource agencies such as 

NOAA and FWS. It must also be emphasized that, in arriving at the overall conclusions for certain 

environmental resources (e.g., coastal and marine birds, fisheries, and wetlands), the conclusions are not 

based on impacts to individuals, small groups of animals, or small areas of habitat, but on impacts to the 

resources/populations as a whole. 

The BOEMRE has made conscientious efforts to comply with the spirit and intent of NEPA, to avoid 

being arbitrary and capricious in its analyses of potential environmental effects, and to use adaptive 

management to respond to new developments related to the OCS Program. 

Incomplete or Unavailable Information 

In the following analyses of physical, environmental, and socioeconomic resources, there are 

numerous references to incomplete or unavailable information, especially in relation to the DWH event 

and the associated oil spill. The subject-matter experts for each resource used the best information that 

was publicly available at the time this Supplemental EIS was written to prepare the descriptions of the 

affected environment and impact analyses, and to develop conclusions regarding the various resources. 

Since this is a supplemental document tiered from the Multisale EIS and the 2009-2012 Supplemental 

EIS, the subject-matter experts were tasked with determining if the conclusions made in the Multisale EIS 

and the 2009-2012 Supplemental EIS had changed based upon new information. 

Although there has been considerable speculation in media reports regarding the impacts of the DWH 

event, credible scientific data regarding the potential short-term and long-term impacts is incomplete and 

it could be many years before this information becomes available via the NRDA process, the BOEMRE 

Environmental Studies Program, and numerous studies by academia. Information will become available 

on a continuing basis for years via the NRDA process, the BOEMRE Environmental Studies Program, 

and numerous studies by academia. 

The data obtained to support the conclusions within this Supplemental EIS indicate that, even though 

the environmental baseline in the CPA was changed by the DWH event, the expected level of impacts to 

the physical, environmental, and socioeconomic resources due to proposed CPA Lease Sale 216/222 are 

substantially the same as those presented in the Multisale EIS and the 2009-2012 Supplemental EIS, the 

documents from which this Supplemental EIS is tiered. There is no reason to believe that any additional 

information would alter the conclusions. 

In accordance with NEPA Section 1502.22, “Incomplete or Unavailable Information,” when an 

agency is evaluating reasonably foreseeable, significant adverse effects on the human environment in an 

EIS and there is incomplete or unavailable information, the agency shall always make it clear that such 

information is lacking. It must be emphasized that BOEMRE is unaware of any missing data that are key 

to the overall analyses and conclusions regarding the potential impacts of proposed CPA Lease Sale 

216/222. 

Four previous CPA lease sales in the current 5-Year OCS Program (2007-2012) have already been 

held based on the information and analyses presented in the EIS’s from which this Supplemental EIS is 

tiered. The conclusions of this Supplemental EIS are fundamentally the same as the conclusions upon 

which those lease sales were based. 

There is no incomplete or unavailable information that is deemed relevant to making a determination 

regarding reasonably foreseeable, significant adverse impacts or that is essential to a reasoned choice 
4-6 Central Planning Area Supplemental EIS 

among alternatives. As noted previously, new information will become available for years. The 

BOEMRE is a strong advocate of adaptive management. If new, unforeseen information that would 

require changes in the manner in which BOEMRE regulates and manages oil and gas operations that may 

result from the proposed lease sale becomes available in the future, appropriate adjustments will be made 

at that time. However, based on the information known at this time, there is no reason to believe that the 

conclusions reached in the Multisale EIS and the 2009-2012 Supplemental EIS, which included proposed 

CPA Lease Sale 216/222, have been altered or changed due to the DWH event. 

This chapter has thoroughly examined the existing, credible scientific evidence that is relevant to 

evaluating the reasonably foreseeable, significant adverse impacts of proposed CPA Lease Sale 216/222 

on the human environment. The subject-matter experts that prepared this Supplemental EIS conducted a 

diligent search for pertinent information, and BOEMRE’s evaluation of such impacts is based upon 

theoretical approaches or research methods generally accepted in the scientific community. All 

reasonably foreseeable impacts were considered, including impacts that could have catastrophic 

consequences, even if their probability of occurrence is low. The analysis of impacts contained herein is 

supported by credible scientific evidence; it is not based on pure conjecture, media reports, or public 

perception; and it is within the rule of reason. 

4.1.1. Alternative A—The Proposed Action 

4.1.1.1. Air Quality 

The BOEMRE has reexamined the analysis for air quality presented in the Multisale EIS and the 

2009-2012 Supplemental EIS based on the additional information presented below and in consideration of 

the DWH event. No substantial new information was found that would alter the impact conclusion for air 

quality presented in the Multisale EIS and the 2009-2012 Supplemental EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. 

Emissions of pollutants into the atmosphere from the routine activities associated with the CPA proposed 

action are projected to have minimal impacts to onshore air quality because of the prevailing atmospheric 

conditions, emission heights, emission rates, and the distance of these emissions from the coastline, and 

the emissions are expected to be well within the National Ambient Air Quality Standards (NAAQS). 

While regulations are in place to reduce the risk of impacts from H2S and while no H2S-related deaths 

have occurred on the OCS, accidents involving high concentrations of H2S could result in deaths as well 

as environmental damage. These emissions from routine activities and accidental events associated with 

the proposed action are not expected to have concentrations that would change onshore air quality 

classifications. The total impact from all onshore and offshore emissions (such as roads, power 

generation, and industrial activities) would continue to significantly affect the ozone nonattainment areas 

in southeast Texas and the parishes near Baton Rouge, Louisiana. The proposed action would have an 

insignificant contribution to ozone levels in the nonattainment areas and would not interfere with the 

States’ schedule for compliance with the NAAQS. 

4.1.1.1.1. Description of the Affected Environment 

A detailed description of air quality can be found in Chapter 3.1.1 of the Multisale EIS. Additional 

information for the 181 South Area and any new information since the publication of the Multisale EIS is 

presented in Chapter 4.1.1 of the 2009-2012 Supplemental EIS. The following information is a summary 

of the resource description incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and 

new information that has become available since both documents were prepared. 

The Clean Air Act (CAA) established the NAAQS. The primary standards are to protect public 

health, and the secondary standards are set to protect public welfare, such as visibility or to protect 

vegetation, as shown in Table 4-1. The current NAAQS addresses six pollutants: carbon monoxide, 

lead, nitrogen dioxide (NO2), particulate matter (PM), ozone (O3), and sulfur dioxide (SO2) (Table 4-1). 

Particulate material is presented as two categories according to size. Coarse particulate matter is between 

2.5 m and 10 m (PM10), and fine particulate matter is less than 2.5 m in size (PM2.5). Under the CAA, 
Description of the Environment and Impact Analysis 4-7 

USEPA is periodically required to review and, as appropriate, modify the criteria based on the latest 

scientific knowledge. Several revisions to the NAAQS have occurred since the publication of the 

Multisale EIS, as more is understood about the effects of the pollutants. 

Effective December 17, 2006, USEPA revoked the annual PM10 standard and revised the 24-hour 

PM2.5 from 65 g/3

 to 35 g/3. In early 2008, USEPA promulgated a new, more restrictive NAAQS 

8-hour O3 standard of 0.075 ppm, which has been fully implemented. An additional revision to the 2008 

revision of the 8-hour O3 standard was proposed in January 2010. A value within the range of 0.060 to 

0.070 ppm was recommended. As of November 2010, a final O3 standard has not been issued. With the 

introduction of a new lower standard, additional Gulf Coast counties/parishes that are presently in 

attainment may become in nonattainment for ozone. Such an occurrence would likely generate renewed 

interest in OCS sources to mitigate the OCS contribution to ozone nonattainment. In turn, this would 

likely require BOEMRE to conduct additional air quality studies to more accurately determine the OCS 

contribution. 

The USEPA also issued revisions to other NAAQS standards during 2010. Effective April 23, 2010, 

USEPA revised the NO2 NAAQS standard to a new 1-hour standard of 100 ppb (0.100 ppm). Effective 

August 23, 2010, USEPA revised the SO2 NAAQS standard to a 1-hour standard of 75 ppb (0.075 ppm) 

and revoked the 24-hour and the annual SO2 standard. 

In response to the recent DWH event, USEPA and the affected States conducted extensive air quality 

monitoring along the Gulf Coast. The air monitoring conducted to date has found that the levels of ozone 

and particulates were at levels well below those that would cause short-term health problems (USEPA, 

2010a). The air monitoring also did not find any pollutants at levels expected to cause long-term harm. 

However, it has been reported in the news that people along the coastal areas felt the effect of the toxic 

chemicals released from the DWH event and the sprayed dispersant. 

Attainment 

Air quality depends on multiple variables—the location and quantity of emissions; dispersion rates; 

distances from receptors; and local meteorology. Meteorological conditions and topography may confine, 

disperse, or distribute air pollutants in a variety of ways. 

The Clean Air Act Amendments of 1990 (CAAA) established classification designations based on 

regional monitored levels of ambient air quality. These designations impose mandated timetables and 

other requirements necessary for attaining and maintaining healthful air quality in the U.S. based on the 

seriousness of the regional air quality problem. 

When measured concentrations of regulated pollutants exceed standards established by the NAAQS, 

an area may be designated as a nonattainment area for a regulated pollutant. The number of exceedances 

and the concentrations determine the nonattainment classification of an area. The CAAA establishes five 

classifications of nonattainment status—marginal, moderate, serious, severe, and extreme. 

The Federal OCS waters’ attainment status is unclassified. The OCS areas are not classified because 

there is no provision for any classification in the CAA for waters outside of the boundaries of State 

waters. Only areas within State boundaries are to be classified as either attainment, nonattainment, or 

unclassifiable. 

Operations west of 87.5o W. longitude fall under BOEMRE jurisdiction for enforcement of the Clean 

Air Act (42 U.S.C. 7401 et seq.). The OCS waters east of 87.5o W. longitude are under the jurisdiction of 

USEPA. 

Figure 4-1 presents the air quality status in the Gulf Coast as of April 2011. All air-quality 

nonattainment areas reported in Figure 4-1 are for ozone nonattainment. As of May 27, 2008 (effective 

day), the new 8-hour ozone standard NAAQS of 0.075 ppm has been fully implemented (USEPA, 2011a). 

As of January 22, 2010, the new 1-hour nitrogen dioxide standard of 100 ppb has been fully implemented. 

The attainment or nonattainment status for criteria pollutants (i.e., CO, SO2, NO2, PM, and O3) for the 

Gulf Coast States adjacent to the CPA are stated below (USEPA, 2011b). 

Louisiana is in attainment for CO, SO2, NO2, and PM, and nonattainment for O3. The nonattainment 

parishes in Louisiana include Ascension, East Baton Rouge, Iberville, Livingston, and West Baton Rouge 

Parishes (USEPA, 2011b). More recent monitoring data collected in the period 2006-2009 indicated that 

the Baton Rouge nonattainment area has not had any violations of the 8-hour ozone standard. The State is 

in the process of submitting the needed information so that USEPA can redesignate the area to attainment 
4-8 Central Planning Area Supplemental EIS 

(Federal Register, 2010e). A steady decline over the last two decades is a result of deliberate actions to 

reduce ozone precursor emissions, as well as research and regulatory work done to understand the causes 

of ozone formation in the area (Louisiana Dept. of Environmental Quality, 2004). The average number of 

ozone exceedances in the area has declined, as has the number of air-pollution monitors recording 

exceedances. 

The PSD Class I air quality areas, designated under the Clean Air Act, are afforded the greatest 

degree of air quality protection and are protected by stringent air quality standards that allow for very 

little deterioration of their air quality. The PSD maximum allowable pollutant increase for PSD Class I 

areas are as follows: 2.5 g/3

 annual increment for NO2; 25 g/3 3-hour increment, 5 g/3 24-hour 

increment, and 2 g/3

 annual increment for SO2; and 8 g/3 24-hour increment and 4 g/3 annual 

increment for PM10. The CPA includes the Breton National Wildlife Refuge and National Wilderness 

Area (BNWA) south of Mississippi, which is designated as a PSD Class I area. The FWS has 

responsibility for protecting wildlife, vegetation, visibility, and other sensitive resources called airquality-related values in this area. The FWS has expressed concern that the NO2 and SO2 increments for 

the Breton National Wilderness Area have been consumed. The BOEMRE has addressed FWS concerns 

with scientific study to determine the pollutant increment status at BNWA. The results obtained from this 

study show that the maximum 3-hour, 24-hour, and annual SO2 increments were not exceeded within the 

BNWA, but a portion of the increment was consumed (Wheeler et al., 2008). Likewise, the maximum 

annual NO2 increment was not exceeded within the BNWA, but a portion of the increment was 

consumed. The exact effect of the DWH event on the BNWA is not known. However, it is expected that 

the effect of the DWH event on the air quality at the BNWA would be small since the air emissions from 

the DWH are temporary sources. 

Jurisdiction 

The responsibilities of BOEMRE are described in the OCSLA (43 U.S.C. 1334(a)(8)), which requires 

the Secretary of the Interior to promulgate and administer regulations that comply with the NAAQS, 

pursuant to the CAA (42 U.S.C. 7401 et seq.) and to the extent that authorized activities significantly 

affect the air quality of any State. In 1990, pursuant to Section 328 of the CAAA and following 

consultation with the Commandant of the USCG and the Secretary of the Department of the Interior, the 

OCS waters east of 87.5o W. longitude were transferred to within the jurisdiction of USEPA. Operations 

west of 87.5o W longitude in the GOM remain under BOEMRE jurisdiction for enforcement of the 

NAAQS. 

The USEPA promulgated OCS air quality regulations at 40 CFR 55 to implement the statutory 

objectives. Over the past several years, BOEMRE has leased some blocks that are east of 87.5o W. 

longitude. These lessees are working with USEPA to obtain permits for air emissions (USEPA, 2010b). 

Emission Inventories 

The CAAA requires BOEMRE to coordinate air-pollution control activities with USEPA. Thus, 

there will be a continuing need for emission inventories and modeling in the future. The following is a 

summary of new information available since publication of the Multisale EIS and the 2009-2012 

Supplemental EIS. 

The BOEMRE has completed two air emissions inventory studies for calendar years 2008 (Wilson et 

al., 2010) and 2005 (Wilson et al., 2007). These studies estimated emissions for all OCS oil and gas 

production-related sources in the Gulf of Mexico, including nonplatform sources, as well as other 

non-OCS-related emissions. The inventories included carbon monoxide (CO), nitrogen oxides (NOx), 

sulfur dioxide (SO2), PM10, PM2.5, and VOC’s, as well as greenhouse gases―carbon dioxide (CO2), 

methane (CH4), and nitrous oxide (N2O). The widespread damage in the Gulf of Mexico caused by 

Hurricanes Katrina and Rita impacted the inventory results for September through December 2005. Due 

to the impacts of the hurricanes on OCS facilities in 2005, an updated Gulfwide emissions inventory 

study was funded for calendar year 2008, and more inventory data have been collected. At present, the 

2008 study is finished, but it is only available in draft form. In the summer of 2010, BOEMRE funded 

another cycle of this air emissions inventory to be conducted during 2011. These emissions inventories 
Description of the Environment and Impact Analysis 4-9 

will be used in air quality modeling to determine the potential impacts of offshore sources to onshore 

areas. 

The USEPA implemented the new ozone standard of 75 ppb in 2008. As a result, additional Gulf 

Coast counties/parishes have become nonattainment for ozone, which would likely generate renewed 

interest in OCS sources to mitigate the OCS contribution to ozone nonattainment areas. In turn, this 

would likely require BOEM to conduct additional air quality studies to more accurately determine the 

OCS contribution. 

Greenhouse Gas Reporting 

In response to the FY 2008 Consolidated Appropriations Act, USEPA issued 40 CFR 98, which 

requires reporting of greenhouse gas emissions. On November 8, 2010, Subpart W of the Greenhouse 

Gas Reporting Rule was finalized. Subpart W requires petroleum and natural gas facilities that emit 

25,000 metric tons or more of CO2 equivalents per year to report emissions from equipment leaks and 

venting. The USEPA has determined that the activity data (Gulfwide Offshore Activities Data System 

[GOADS]) that has been collected to fulfill BOEMRE’s emissions inventory may be used to comply with 

Subpart W of the USEPA Greenhouse Gas Reporting Rule. Subpart C of the Greenhouse Gas Reporting 

Rule requires operators to report greenhouse gas emissions from general stationary fuel combustion 

sources to USEPA. At this time, BOEMRE’s GOAD’s activity data may not be used to comply with 

Subpart C; therefore, affected operators will have to perform some additional efforts in order to comply 

with Subpart C (USEPA, 2010c). 

4.1.1.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine events on air quality in the Gulf of Mexico can be found in Chapter 

4.2.2.1.1 of the Multisale EIS. Additional information for the 181 South Area and any new information 

since the publication of the Multisale EIS is presented in Chapter 4.1.1.2 of the 2009-2012 Supplemental 

EIS. The following information is a summary of the resource description incorporated from the Multisale 

EIS, the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

The following routine activities associated with the CPA proposed action would potentially affect air 

quality: platform construction and emplacement; platform operations; drilling activities; flaring; seismicsurvey and support-vessel operations; pipeline laying and burial operations; evaporation of volatile 

petroleum hydrocarbons during transfers and fugitive emissions. Supporting materials and discussions 

are presented in Chapter 4.1.1.1.1 of this Supplemental EIS, in Chapter 4.1.1.6 and Appendix A-3 of the 

Multisale EIS, and in Chapter 3.1.1.5.1 of the 2009-2012 Supplemental EIS. The impact analysis is based 

on four parameters—emission rates, surface winds, atmospheric stability, and the mixing height. 

Emissions of certain air pollutants are known to be detrimental to public health and welfare. Some of 

these pollutants are directly emitted into the air, while others are formed in the atmosphere through 

chemical reactions. Nitric oxide and nitrogen dioxide constitute nitrogen oxide (NOx) emissions. 

Nitrogen oxide, a by-product of all combustion processes, is emitted from sources such as internal 

combustion engines, natural gas burners, and flares. Nitrogen dioxide is a precursor pollutant involved in 

photochemical reactions that yield ozone. Nitrogen dioxide is an irritating gas that may increase 

susceptibility to infection and may constrict the airways of people with respiratory problems. Further, 

nitrogen dioxide can react with water to form nitric acid, which is harmful to vegetation, animals and 

materials, as a result of increased acidity in precipitation (i.e., acid rain). 

Carbon monoxide (CO) is a by-product of incomplete combustion, primarily contained in engine 

exhaust. Carbon monoxide is readily absorbed into the body through the lungs, where it reacts with 

hemoglobin in the blood, reducing the transfer of oxygen within the body. Carbon monoxide particularly 

affects people with cardiovascular and chronic lung diseases. 

Sulfur dioxide (SO2) may cause constriction of the airways and particularly affects individuals with 

respiratory diseases. Sulfur dioxide reacts in the atmosphere, principally with water vapor and oxygen, 

producing sulfuric acid, which along with nitric acid are the major constituents of acid rain. Acid rain can 

be harmful to animals, vegetation, and materials. The flaring of natural gas containing hydrogen sulfide 
4-10 Central Planning Area Supplemental EIS 

(H2S) and the burning of liquid hydrocarbons containing sulfur (Chapter 4.1.1.9 of the Multisale EIS) 

result in the formation of SO2. The amount of SO2 produced is directly proportional to the sulfur content 

of the hydrocarbons being flared or burned. 

The concentration of the H2S varies substantially from formation to formation and even varies to 

some degree within the same reservoir. Natural gas from the Norphlet Formation in the northeastern 

portion of the CPA, just south of Alabama and Mississippi, tends to range between 40 and 140 ppm on 

the OCS. Nevertheless, two wells are known to have H2S concentrations of 1.8 and 2.5 percent (18,000 

and 25,000 ppm, respectively) in the OCS. Higher concentrations do occur within the Norphlet 

Formation farther north under State territorial waters and below land. 

Additionally, the area around the Mississippi River Delta is a known sulfur-producing area. The 

natural gas in deepwater reservoirs has been mainly sweet (i.e., low in sulfur content), but the oil averages 

between 1 and 4 percent sulfur content by weight. By far, most of the documented production of sour gas 

(i.e., high sulfur content) lies within 150 km (93 mi) of the Breton National Wilderness Area. 

Flaring of gas containing H2S (sour gas) is of concern because it could significantly impact onshore 

areas, particularly when considering the short-duration averaging periods (1 and 24 hours) for SO2. The 

combustion of liquid hydrocarbon fuel is the primary source of sulfur oxides (SOx), when considering the 

annual averaging period; however, impacts from high-rate well cleanup operations can generate 

significant SO2 emissions. To prevent inadvertently exceeding established criteria for SO2 for the 1-hour 

and 24-hour averaging periods, all incinerating events involving H2S or liquid hydrocarbons containing 

sulfur are evaluated individually during the postlease process. 

The VOC’s are precursor pollutants involved in a complex photochemical reaction with NOx in the 

atmosphere to produce ozone. The primary sources of VOC’s result from venting and evaporative losses 

that occur during the processing and transporting of natural gas and petroleum products. A more 

concentrated source of VOC’s is the vents on glycol dehydrator units. 

Particulate matter, also known as particle pollution or PM, is a complex mixture of extremely small 

particles and liquid droplets. Particle pollution is made up of a number of components, including acids 

(such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles. The size of particles 

is directly linked to their potential for causing health problems. Once inhaled, these particles can affect 

the heart and lungs and cause serious health effects. The USEPA groups particle pollution into two 

categories. “Coarse particles,” such as those found near roadways and dusty industries, range in size from 

2.5 to 10 μm in diameter. The PM10 (particulate matter of 10 μm) can also affect visibility, primarily 

because of the scattering of light by the particles and, to a lesser extent, light absorption by the particles. 

This analysis considers mainly total suspended particulate (PM10) matter. “Fine particles,” such as those 

found in smoke and haze, have diameters smaller than 2.5 μm. These particles can be directly emitted 

from sources such as forest fires, or they can form when gases emitted from power plants, industries, and 

automobiles react in the air. In general, particles with a diameter of 2.5 m are more harmful to people 

because they pass through the throat and nose and enter the lungs (USEPA, 2010d). 

Ozone is a nearly colorless gas with a faint but distinctive odor, somewhat similar to chlorine. It is 

formed in the troposphere (i.e., lower level of the atmosphere) from complex chemical reactions 

involving VOC’s and NOx in the presence of sunlight. At ground level, ozone can cause or aggravate 

respiratory problems, interfere with photosynthesis, damage vegetation, and crack rubber. Children, the 

elderly, and healthy people who work or exercise strenuously outdoors are particularly sensitive to 

elevated ozone concentrations. 

Emissions of air pollutants would occur during exploration, development, and production activities. 

The profile of typical emissions for exploratory and development drilling activities (Chapter 4.1.1.6 of the 

Multisale EIS) shows that emissions of NOx are the most prevalent pollutant of concern. Emissions 

during exploration are higher than emissions during development due to power requirements for drilling a 

deeper hole. 

Platform emission rates for the GOM region (Chapter 4.1.1.6 of the Multisale EIS) are provided from 

the 2008 emission inventory of OCS sources (Wilson et al., 2010). This compilation was based on 

information from a survey of 3,304 platforms from 103 companies, which represented an 85 percent 

response rate. Since these responses included all the major oil and gas production facilities, they were 

deemed representative of the type of emissions to be associated with a platform. The NOx and VOC’s are 

the primary pollutants of concern since both are considered to be precursors to ozone. Emission factors 
Description of the Environment and Impact Analysis 4-11 

for other activities such as support vessels, helicopters, tankers, and loading and transit operations were 

taken from the OCS emission inventory (Wilson et al., 2010). 

Flaring is the venting and/burning of natural gas from a specially designed boom. Flaring systems are 

also used to vent gas during well testing or during repair/of production equipment. The BOEMRE 

operating regulations provide for some limited volume, short duration flaring or venting of some natural 

gas volumes upon approval by BOEMRE. These operations may occur for short periods of time 

(typically 2-14 days) as part of unloading/operations that are necessary to remove potentially damaging 

completion fluids from the wellbore, to provide sufficient reservoir data for the operator to evaluate a 

reservoir and development options, and in emergency situations. Accidents, such as oil spills, blowouts 

and pipeline ruptures, are another source of emissions related to OCS operations. The potential impacts 

from these accidental events are discussed in Chapter 4.1.1.1.3. 

Once pollutants are released into the atmosphere, atmospheric transport and dispersion processes 

begin circulating the emissions. Transport processes are carried out by the prevailing net wind 

circulation. During summer, the wind regime in the CPA is predominantly onshore at mean speeds of 

3-5 m/sec (6.7-11.2 mph). Average winter winds are predominantly offshore at speeds of 4-8 m/sec 

(8.9-17.9 mph) (Appendix A.3 of the Multisale EIS). 

Dispersion depends on emission height, atmospheric stability, mixing height, exhaust gas temperature 

and velocity, and wind speed. For emissions within the atmospheric boundary layer, the vertical heat 

flux, which includes effects from wind speed and atmospheric stability (via air-sea temperature 

differences), is a good indicator of turbulence available for dispersion (Lyons and Scott, 1990). Heat flux 

calculations in the CPA (Florida A&M University, 1988) indicate an upward flux year-round, being 

highest during winter and lowest in summer. 

The mixing height is very important because it determines the vertical space available for spreading 

the pollutants. The mixing height is the height above the surface of the earth through which vigorous 

vertical mixing occurs. Vertical mixing is most vigorous during unstable conditions and is suppressed 

during stable conditions resulting in the worst periods of air quality. Although mixing height information 

throughout the GOM is scarce, measurements near Panama City, Florida (Hsu, 1979), show that the 

mixing height can vary between 400 and 1,300 m (1,312 and 4,265 ft), with a mean of 900 m (2,953 ft). 

The mixing height tends to be higher in the afternoon, more so over land than over water. Further, the 

mixing height tends to be lower in winter, with daily changes smaller than in summer. 

Proposed Action Analysis 

The OCS emissions in tons per year for the criteria pollutants for the CPA proposed action are 

indicated in Table 4-25 of the Multisale EIS. The major pollutant emitted is NOx, while PM10 is the least 

emitted pollutant. Combustion-intensive operations such as platform operations, well drilling, and 

service-vessel activities contribute mostly NOx; platform operations are also the major contributors of 

VOC emissions. Platform construction emissions contribute appreciable amounts of all pollutants over 

the life of the proposed action. These emissions are temporary in nature and generally occur for a period 

of 3-4 months. Typical construction emissions result from the derrick barge placing the jacket and 

various modular components and from various service vessels supporting this operation. The drilling 

operations contribute considerable amounts of all pollutants. These emissions are temporary in nature 

and typically occur over a 40-day drilling period. Support activities for OCS activities include crew and 

supply boats, helicopters, and pipeline vessels; emissions from these sources consist mainly of NOx and 

CO. These emissions are directly proportional to the number and type of OCS operations requiring 

support activities. Most emissions from these support activities occur during transit between the port and 

the offshore facilities; a smaller percentage of the emissions occur during idling at the platform. Platform 

and well emissions were calculated using the integration of projected well and platform activities over 

time. 

The total pollutant emissions per year are not uniform. At the beginning of the proposed activities, 

emissions would be the largest. Emissions peak early on, as development and drilling start relatively 

quickly, followed by production. After reaching a maximum, emissions would decrease as wells are 

depleted and abandoned, platforms are removed, and service-vessel trips and other related activities are 

no longer needed. 
4-12 Central Planning Area Supplemental EIS 

The BOEME regulations (30 CFR 250.303) establish 1-hour and 8-hour significance levels for CO. 

A comparison of the projected emission rate to BOEMRE’s exemption level would be used to assess CO 

impacts. The formula to compute the emission rate in tons/for CO is 3,400•D2⁄3; D represents distance in 

statute miles from the shoreline to the source. This formula is applied to each facility. 

The VOC emissions are best addressed as their corresponding ozone impacts, which were studied in 

the GOM Air Quality Study (GMAQS) (Systems Applications International, et al., 1995). The GMAQS 

indicated that OCS activities have little impact on ozone exceedance episodes in coastal nonattainment 

areas, including the Houston/Beaumont, Port Arthur/Lake Charles, and Baton Rouge areas. Total OCS 

contributions to the exceedance (greater than 120 ppb) episodes studied were less than 2 ppb. In the 

GMAQS, the model was also run using double emissions from OCS petroleum development activities, 

and the resulting attributable ozone concentrations, during modeling exceedance episodes, were still 

small, ranging 2-4 ppb. The activities under the proposed action would not result in a doubling of the 

emissions, and because the proposed activities are substantially smaller than this worst-case scenario, it is 

logical to conclude that their impact would be substantially smaller as well (Systems Applications 

International et al., 1995). Additionally, 30 CFR 250.303(g)(2) requires that, if a facility would 

significantly impact (defined as exceeding BOEMRE’s significance levels) an onshore nonattainment 

area, then it would have to reduce its impact fully through the application of the best available control 

technology and possibly through offsets as well. The new 8-hour ozone standard (0.075 ppm) has been 

fully implemented as of May 27, 2008. It is more stringent than the previous 1-hour standard as well as 

the old 8-hour standard. In response to the 1997 ozone standard (0.08 ppm), the updated ozone modeling 

was performed using a preliminary Gulfwide emissions inventory for the year 2000 to examine the O3

impacts with respect to the new 8-hour ozone standard. Two modeling studies were conducted. One 

modeling study focused on the coastal areas of Louisiana extending eastward to Florida (Haney et al., 

2004). This study showed that the impacts of OCS emissions on onshore O3 levels were very small, with 

the maximum contribution of 1 ppb or less at locations where the standard was exceeded. The other 

modeling effort dealt with O3 levels in southeast Texas (Yarwood et al., 2004). The results of this study 

indicated a maximum contribution of 0.2 ppb or less to areas exceeding the standard. 

Current industry practice is to transport OCS-produced oil and gas via pipeline whenever feasible. It 

is estimated that over 99 percent of the gas and oil would be piped to shore terminals. Thus, fugitive 

emissions associated with tanker and barge loadings and transfer would be small, as would the associated 

exhaust emissions. Safeguards to ensure minimum emissions from any offloading and loading operations 

of OCS crude oil production from surface vessels at ports have been adopted by the State of Louisiana 

(Marine Vapor Recovery Act, 2010, LAC 33:III.2108 [Louisiana Dept. of Environmental Quality, 2010]). 

The BOEMRE studied the impacts of offshore emissions using the Offshore and Coastal Dispersion 

(OCD) Model. Three large areas in the CPA were modeled. The limiting factor on the size of each area 

was the run time needed to process the number of sources. The three areas modeled were a 150-km 

(93-mi) radius centered over Breton Island, a 100-km (62-mi) radius centered over the Grand Isle area, 

and a 241-km (150-mi) radius over the Vermilion area. Receptors were set along the coastline and also a 

short distance inland in order to capture coastal fumigation. Circular areas were chosen to reduce edge 

effect. The Breton area was chosen to capture the PSD Class I area. The other two areas were selected to 

best capture most of the offshore sources and to focus on the highly concentrated areas of development. 

Ratios between these two sets of total emission rates were developed and applied to the 2008 inventory; 

this modified inventory was then used as the database for the sources for the OCD modeling. Only the 

onshore maximum concentrations reported for all of the runs are discussed. The results of the runs are 

reported in Tables 4-26 and 4-27 of the Multisale EIS. The results are also compared with the federally 

allowable increases in ambient concentrations as regulated by 30 CFR 250.303 and 40 CFR 52.21. 

Tables 4-26 and 4-27 of the Multisale EIS list the highest predicted contributions to onshore pollutant 

concentrations from OCS activities, as well as the maximum allowable increases over a baseline 

concentration established under the air quality regulations. While these tables show that the proposed 

lease sale alone would result in concentration increases that are well within the maximum allowable limits 

for PSD Class I and Class II areas, a direct comparison between the two sets of figures is not possible. 

This is because the actual maximum allowable increase depends on the net change in emissions from all 

other sources in the area, both offshore and onshore, since the date the baseline level was established. 

Sources that were already in place at the applicable baseline date are included in the establishment of the 

baseline and corresponding concentration and do not count in the determination of the maximum 
Description of the Environment and Impact Analysis 4-13 

allowable increment. The PM10 are emitted at a substantially smaller rate than NO2 and SO2; hence, 

impacts from PM10 would be expected to be small. Since the proposed action would represent 

approximately 4-5 percent of OCS activities in the CPA, emissions from activities resulting from the 

proposed action would be substantially below the maximum allowable limits for a PSD Class II area. 

Suspended particulate matter is important because of its potential in degrading the visibility in 

national wildlife refuges or recreational parks designated as PSD Class I areas. The impact depends on 

emission rates and particle size. Particle size represents the equivalent diameter (diameter of a sphere) 

that would have the same settling velocity as the particle. Particle distribution in the atmosphere has been 

characterized as being largely trimodal (Godish, 1991), with two peaks located at diameters smaller than 

2 μm and a third peak with a diameter larger than 2 μm. Particles with diameters of 2 μm or larger settle 

very close to the source (residence time of approximately 1⁄2 day, Lyons and Scott, 1990). For particles 

smaller than 2 μm, which do not settle fast, wind transport determines their impacts. Projected PM10

concentrations are expected to have a low impact on the visibility of PSD Class I areas. 

Gaseous and fine particulate matter in the atmosphere can potentially degrade the atmospheric 

visibility. The visibility degradation is primarily due to the presence of particulates with the size in the 

range of 1 to 2 microns (micrometers). The sources of these particulates may come from fuel burning and 

the chemical transformation of the atmospheric constituents. The chemical transformation of NO2, SO2, 

and VOC may produce nitrates, sulfates, and carbonaceous particles. High humidity also may contribute 

to the visibility impairment in the Gulf coastal areas. Visibility is considered an important resource in the 

Breton National Wilderness Area, a Federal Class I area. Since future air emission from all sources in the 

area are expected to be about the same level or less, it is expected that the impact on visibility due to the 

presence of fine particulates would be minor. 

The Breton National Wilderness Area is a Class I air quality area administered by FWS. Under the 

Clean Air Act, BOEMRE would notify FWS and the National Park Service if emissions from proposed 

projects may impact the Breton Class I area. Mitigating measures and stricter air emissions monitoring 

and reporting requirements are required for sources that are located within 100 km (62 mi) of the Breton 

Class I Area and that exceed emission levels agreed upon by the administering agencies. 

Summary and Conclusion 

Emissions of pollutants into the atmosphere from the routine activities associated with the CPA 

proposed action are projected to have minimal impacts to onshore air quality because of the prevailing 

atmospheric conditions, emission heights, emission rates, and the distance of these emissions from the 

coastline. As indicated in the GMAQS and other modeling studies, the proposed action would have only 

a small effect on ozone levels in ozone nonattainment areas and would not interfere with the States’ 

schedule for compliance with the NAAQS. Regulations, monitoring, mitigation, and developing 

emissions-related technologies would ensure these levels stay within the NAAQS. 

4.1.1.1.3. Impacts of Accidental Events 

Background/Introduction 

A description of impacts of accidental events can be found in Chapter 4.4.1 of the Multisale EIS and 

an update to include the 181 South Area can be found in Chapter 4.1.1.3 of the 2009-2012 Supplemental 

EIS. 

The accidental release of hydrocarbons related to the CPA proposed action would result in the 

emission of air pollutants. The OCS accidents would include the release of oil, condensate, or natural gas 

or chemicals used offshore or pollutants from the burning of these products. The air pollutants include 

criteria NAAQS pollutants, volatile and semi-volatile organic compounds, hydrogen sulfide, and 

methane. These pollutants are discussed in Chapter 4.1.1.1.2 above. If a fire was associated with the 

accidental event, it would produce a broad array of pollutants, including all NAAQS-regulated primary 

pollutants, including NO2, CO, SOx, VOC, PM10, and PM2.5. The discussion below addresses a 

15,000-bbl spill. In the spill size category of >10,000 bbl, the average of the largest historical spills is 

15,000 bbl and is the average volume of two pipeline spills that occurred (Anderson and LaBelle, 2000). 

A catastrophic event is a high-volume, long-duration oil spill or a “spill of national significance.” An 

analysis of the impact of a catastrophic spill is included in Appendix B. Many Federal and State agencies 
4-14 Central Planning Area Supplemental EIS 

and companies participate in a catastrophic event such as the DWH event. Response-worker air quality 

onshore and on-water was monitored by the Occupational Safety and Health Administration (OSHA), 

USCG, and the responsible party to ensure a safe work environment. Coastal community air quality was 

monitored by USEPA and State environmental agencies. The results from these efforts are available on 

DWH event websites such as http://www.epa.gov/bpspill/air.html. 

Proposed Action Analysis 

The accidental release of hydrocarbons or chemicals from the CPA proposed action would cause the 

emission of air pollutants. Some of these pollutants are precursors to ozone, which is formed by complex 

photochemical reactions in the atmosphere. Accidents, such as oil spills and blowouts, are a source of 

emissions related to OCS operations. Typical emissions from OCS accidents consist of hydrocarbons; 

only fires produce a broad array of pollutants, including all NAAQS-regulated primary pollutants. The 

criteria pollutants considered here are NO2, CO, SOx, VOC, PM10, and PM2.5. 

NAAQS Pollutants 

Some of the NAAQS pollutants, the VOC’s and NOx, are precursors to ozone, which is formed by 

complex photochemical reactions in the atmosphere. Human exposure to ground-level ozone exposure 

causes a variety of health problems including airway irritation, aggravation of asthma, and increased 

susceptibility to respiratory illnesses. Ozone levels could increase, especially if the oil spill were to occur 

on a hot, sunny day with sufficient concentrations of NOx present in the lower atmosphere. An accidental 

spill would possibly have a temporary localized adverse effect due to NAAQS pollutant concentrations. 

Due to the distance from shore and an assumed accidental spill size of 15,000 bbl, an oil spill would not 

affect onshore ozone concentrations. 

The VOC emissions from the evaporation of oil spill can contribute to the formation of particulate 

matter (PM2.5). In-situ burning also generates particulate matter. Particulate matter can cause adverse 

human respiratory effects and can also result in a haze. The PM2.5 concentrations in a plume could have 

the potential to temporarily degrade visibility in any affected PSD Class I areas (i.e., National Wilderness 

Areas and National Parks) such as the Breton National Wilderness Area in the CPA and other areas where 

visibility is important. 

Hydrocarbons 

Oil is a mixture of many different chemical compounds, some of which are hazardous to health. 

Toxic chemicals can cause headache or eye irritation and some other symptoms. Benzene can cause 

cancer at high levels and long exposures. The benzene, ethylbenzene, toluene, and xylene (BTEX 

fraction) of oil is light and volatilizes into air. The BTEX level is commonly measured to provide an 

indication of the level air quality. During an accidental spill, the levels of BTEX in the immediate area 

could exceed safe levels. In hazardous conditions, OSHA and USCG regulations require workers to use 

breathing protection. An accidental spill would possibly result in temporary localized elevated levels of 

hydrocarbons. Due to the distance to shore and an assumed accidental spill size of 15,000 bbl, an 

accidental spill would not result in elevated onshore BTEX concentrations. An analysis of the impact of a 

catastrophic spill, of far greater size, is included in Appendix B. 

Hydrogen Sulfide (H2S) 

The presence of H2S within formation fluids occurs sporadically throughout the Gulf of Mexico OCS 

and may be released during an accident. The concentrations of H2S found to date are generally greatest in 

the eastern portion of the CPA. There has been some evidence that petroleum from deep water contain 

significant amounts of sulfur. The H2S concentrations in the OCS vary from as low as a fraction of a ppm 

to as high as 650,000 ppm. Hydrogen sulfide can cause acute symptoms, including headaches, nausea, 

and breathing problems. During an accidental event, H2S concentrations could be high enough in the 

immediate area to be life threatening. The BOEMRE’s regulations (30 CFR 250.490(a)(1)) and the 

clarifying Hydrogen Sulfide NTL (NTL 2009-G31) requires a Contingency Plan, as well as sensors and 

alarms (30 CFR 250.490(d)) to alert and protect workers from H2S releases. 
Description of the Environment and Impact Analysis 4-15 

In-situ Burning 

In-situ burning of a spill results in emissions of NO2, SO2, CO, and PM10, and would generate a 

plume of black smoke. Fingas et al. (1995) describes the results of a monitoring program of a burn 

experiment at sea. The program involved extensive ambient measurements during two experiments in 

which approximately 300 bbl of crude oil were burned. It found that during the burn, CO, SO2, and NO2

were measured only at background levels and were frequently below detection levels. Ambient levels of 

VOC were high within about 100 m (328 ft) of the fire but were significantly lower than those associated 

with a nonburning spill. Measured concentrations of polycyclic aromatic hydrocarbons (PAH’s) were 

low. It appeared that a major portion of these compounds was consumed in the burn. In measurements 

taken from the NOAA WP-3D aircraft, lofted plumes from the controlled burns rose above the marine 

boundary layer of 2,000 ft (610 m) (Ravishankara and Goldman, 2010). 

McGrattan et al. (1995) modeled smoke plumes associated with in-situ burning. The results showed 

that the surface concentrations of particulate matter did not exceed the health criterion of 150 μg/3

 beyond 

about 5 km (3 mi) downwind of an in-situ burn. This is quite conservative since this health standard is 

based on a 24-hour average concentration rather than a 1-hour average concentration. This appears to be 

supported by field experiments conducted off of Newfoundland and in Alaska. In summary, the impacts 

from in-situ burning are temporary. Pollutant concentrations would be expected to be within the 

NAAQS. The air quality impacts from in-situ burning would therefore be minor. 

Dioxins and furans are a family of extremely persistent chlorinated compounds that magnify in the 

food chain. During an in-situ burn, the conditions exist (i.e., incomplete hydrocarbon combustion and the 

presence of chlorides in seawater) for dioxins and furans to potentially form. Measurements of dioxins 

and furans during the DWH event in-situ burning were made (Aurell and Gullett, 2010). The estimated 

levels of dioxins and furans produced by the in-situ burns were similar to those from residential 

woodstove fires and slightly lower than those from forest fires, according to USEPA researchers (Schaum 

et al., 2010) and, thus, concerns about bioaccumulation in seafood were alleviated. 

Flaring 

Flaring may be conducted to manage excess gas during an accidental event such as damage to a 

pipeline. For the DWH event, a flare that burned both oil and gas was employed. Flaring would result in 

the release of NOx emissions from the flare. The SO2 emissions would be dependent on the sulfur content 

of the crude oil. 

Particulate matter from the flare would also affect visibility. Flaring or burning activities upwind of a 

PSD Class I area, e.g., the Breton National Wilderness Area in the CPA, could adversely affect air quality 

through increased SO2 concentrations and reduced visibility. More information about the DWH event 

flaring is available in Appendix B. 

In-situ burning and flaring are temporary efforts to limit environmental impact during an accidental 

spill. Flaring needs to be approved by the Regional Director. The appropriate agencies will monitor for 

worker safety. Pollutant concentrations onshore would be expected to be within the NAAQS and not to 

have onshore impacts. 

Dispersants 

Dispersants may be applied to break up surface and subsurface oil following an accidental spill. In 

surface application, aircraft fly over the spill, similar to crop dusting on land, and spray dispersants on the 

visible oil. Dispersant usage is usually reserved for offshore locations. There is the possibility that the 

dispersant mist can drift from the site of application to a location where workers or the community are 

exposed by both skin contact and inhalation. Following the DWH event, USEPA provided the TAGA 

bus, a mobile laboratory, to perform instantaneous analysis of air in coastal communities. Two 

ingredients in the Corexit dispersant were measured. Very low levels of dispersants were identified. Due 

to the distance to shore and an assumed accidental spill size of 15,000 bbl, it is unlikely that dispersants 

would be carried to onshore areas. 
4-16 Central Planning Area Supplemental EIS 

Odors 

An accidental spill could result in odors (USEPA, 2010e). The low levels of pollutants may cause 

temporary eye, nose, or throat irritation, nausea, or headaches, but the doses are not thought to be high 

enough to cause long-term harm (USEPA, 2010e). Due to the distance to shore and an assumed 

accidental spill size of 15,000 bbl, it is unlikely that applied dispersants would drift to onshore areas. 

Summary and Conclusion 

Accidental events associated with the CPA proposed action that could impact air quality include spills 

of oil, natural gas, condensate, and refined hydrocarbons; H2S release; fire; and NAAQS air pollutants 

(i.e., SOx, NOx, VOC’s, CO, PM10, and PM2.5). Response activities that could impact air quality include 

in-situ burning, the use of flares to burn gas and oil, and the use of dispersants applied from aircraft. 

Measurements taken during an in-situ burning show that a major portion of compounds was consumed in 

the burn; therefore, pollutant concentrations would be expected to be within the NAAQS. In a recent 

analysis of air in coastal communities, low levels of dispersants were identified. These response activities 

are temporary in nature and occur offshore; therefore, there are little expected impacts from these actions 

to onshore air quality. Accidents involving high concentrations of H2S could result in deaths as well as 

environmental damage. Regulations and NTL’s are in place to protect workers from H2S releases. Other 

emissions of pollutants into the atmosphere from accidental events as a result of the CPA proposed action 

are not projected to have significant impacts on onshore air quality because of the prevailing atmospheric 

conditions, emissions height, emission rates, and the distance of these emissions from the coastline. 

These emissions are not expected to have concentrations that would change onshore air quality 

classifications. 

During the DWH event, a huge number of air samples were collected. Analyses included BETX, PM, 

H2S, NAAQS criteria pollutants, and dioxin. According to USEPA, in coastal communities air pollutants 

from the DWH event were at levels well below those that would cause short-term health problems. The 

air monitoring conducted to date has not found any pollutants at levels expected to cause long-term harm 

(USEPA, 2010a). However, serious questions have been raised concerning the effects of the DWH event 

on public health and the workers, resulting from the releases of particles and toxic chemicals due to 

evaporation from oil spill, flaring, oil burn, and the applications of dispersants (Rotkin-Ellman et al., 

2010). Air quality impacts include the emission of pollutants from the oil and the fire emissions that are 

hazardous to human health and that can possibly be fatal (Appendix B). 

Overall, since loss of well-control events and blowouts are rare events and of short duration, potential 

impacts to air quality are not expected to be significant except in the rare case of a catastrophic event. 

The summary of vast amounts of data collected and additional studies will provide more information in 

the future. 

Although BOEMRE regulates the air emissions and air quality in the Gulf of Mexico region, at 

present, BOEMRE does not have an air quality model for the estimate of air concentrations from the 

distance OCS emission sources. Thus, BOEMRE relies on other government agencies for air quality 

assessment; their air quality models may not be appropriate for the assessment of air quality from the 

OCS emission sources. 

4.1.1.1.4. Cumulative Impacts 

Background/Introduction 

An impact analysis for cumulative impacts in the WPA and CPA on air quality can be found in 

Chapter 4.5.1 of the Multisale EIS and was updated in Chapter 4.1.1.4 of the 2009-2012 Supplemental 

EIS. The following is a summary of the information presented in the Multisale EIS and the 2009-2012 

Supplemental EIS. This cumulative analysis summary considers OCS and non-OCS activities that could 

occur and adversely affect onshore air quality and the Breton National Wilderness Area from OCS 

sources during the 40-year analysis period. 

The activities in the cumulative scenario that could potentially impact onshore air quality include the 

proposed action and the OCS Program, State oil and gas programs, other major factors influencing 
Description of the Environment and Impact Analysis 4-17 

offshore environments, onshore non-OCS activities, accidental releases from oil spills, accidental releases 

from hydrogen sulfide, natural events (e.g., hurricanes), and a catastrophic oil spill. 

The activities for the OCS Program include the drilling of exploration, delineation, and development 

wells; platform installation; service-vessel trips; flaring; and fugitive emissions. Emissions of pollutants 

into the atmosphere from the activities associated with the OCS Program are not projected to have 

significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates 

and heights, and the resulting pollutant concentrations. Onshore impacts on air quality from emissions 

from OCS activities are estimated to be within PSD Class II allowable increments. In an Agency-funded 

study, the modeling results indicate that the cumulative impacts to the Breton Wilderness Class I Area are 

well within the PSD Class I allowable increment (Wheeler et al., 2008). The OCS contribution to the air 

quality problem in the coastal areas is small. 

State oil and gas programs onshore, in territorial seas, and in coastal waters also generate emissions 

that affect onshore air quality. These emissions are regulated by State agencies and/or USEPA. 

Reductions in emissions have been achieved through the use of low sulfur fuels, catalytic reduction, and 

other efforts and, as a result, constitute minor impacts to onshore air quality. 

Other major factors influencing offshore environments, such as sand borrowing and commercial 

transportation, also generate emissions that can affect air quality. These emissions are regulated by State 

agencies and/or USEPA. Reductions have been achieved through the use of low sulfur fuels and catalytic 

reduction and as a result, constitute minor impacts to onshore air quality. 

Other major onshore emission sources from non-OCS activities include power generation, industrial 

processing, manufacturing, refineries, commercial and home heating, and motor vehicles. The total 

impact from the combined onshore and offshore emissions would be significant to the ozone 

nonattainment areas in southeast Texas and the parishes near Baton Rouge, Louisiana. 

Portions of the Gulf Coast have ozone levels that exceed the Federal air quality standard. Ozone 

levels are on a declining trend because of air-pollution control measures that have been implemented by 

the States. This downward trend is expected to continue as a result of local as well as nationwide airpollution control efforts. However, more stringent air quality standards have recently been implemented 

by USEPA, which may result in increasing the number of parishes/counties in the coastal states that are in 

violation of the Federal ozone standard. There is also a proposal to further decrease the ozone standard. 

If the ozone standard was lowered, although OCS emissions from the proposed action would not vary, the 

OCS emissions in those newly designated areas would have an incrementally larger contribution to the 

onshore ozone levels. Although air quality is improving, the number of areas in nonattainment has 

increased due to the more stringent standard. 

The Gulf Coast has significant visibility impairment from anthropogenic emission sources. Area 

visibility is expected to improve somewhat as a result of regional and national programs to reduce 

emissions. 

Impacts from oil spills for the cumulative scenario would be similar to those described for the 

proposed 2007-2012 leasing program. The spill could be crude oil, crude oil with a mixture of natural 

gas, or refined fuel. Air quality would be affected by the additional response vessel traffic, volatization of 

components of the oil, and natural gas if released. Impacts from individual spills would be localized and 

temporary. 

The scenario of an accidental release of hydrogen sulfide is described in Chapter 3.1.1.5.1. The 

same safety precautions and regulations described in the proposed action are applicable to the cumulative 

scenario. That is, a typical safety zone of several kilometers is usually established in an area with the 

concentration of hydrogen sulfide greater than 20 ppm from the source or a platform. In the event of 

hydrogen sulfide releases, a Contingency Plan is required. 

The effects of hurricanes on the offshore infrastructures are described in Chapters 3.1.1.5.3 and 

3.3.7.2. Hurricanes mainly cause damage to offshore infrastructures and pipelines, which may result in an 

oil spill. A hurricane would cause minor effects on the onshore air quality since air emissions in the event 

of a hurricane are temporary sources. For the cumulative scenario, the emissions from oil-spill and repair 

activities are expected to be the same as the proposed action and to have minimum effects on the onshore 

air quality. 

The accidental impacts from the DWH event are briefly described in Chapter 4.1.1.1.3 and 

Appendix B. The DWH event may have the potential to cause effects on air quality and public health 
4-18 Central Planning Area Supplemental EIS 

and the environment, which may occur from the application of dispersants to an oil spill, in-situ oil 

burning, evaporation of toxic chemicals from oil spill, and cleanup activities. 

These events will release and transport the particulate matter to the onshore environment and increase 

the ozone concentration or the amount of toxic chemicals in the onshore environment. The onshore 

residents and cleanup workers may be exposed to toxic chemicals, particulate matter, or ozone, and they 

may experience short-term or long-term health effects. 

Modeling tools for the transport and dispersion of air pollutants such as ozone, carbon monoxide, 

nitrogen dioxide, and PAH’s are required to determine the fate and pollutant concentrations in the 

environment and subsequently, for the assessment of environmental impacts. It appears that these tools 

are currently not available for the application to the offshore environment, which is needed to be 

developed, especially for the long-range transport of air pollutants. 

In a catastrophic spill, dispersants may be sprayed to break up the slick. The dispersant mist would 

temporarily degrade the air quality. Health complaints were received from workers on adjacent rigs 

following dispersant application during the DWH event. 

In a catastrophic spill, oil may be burned to prevent it from entering sensitive habitats. The USEPA 

released two peer-reviewed reports concerning dioxins emitted during the controlled burns of oil during 

the DWH event (Aurell and Gullet, 2010; Schaum et al., 2010). Dioxins is a category that describes a 

group of hundreds of potentially cancer-causing chemicals that can be formed during combustion or 

burning. The reports found that, while small amounts of dioxins were created by the burns, the levels that 

workers and residents would have been exposed to were below USEPA’s levels of concern. 

However, at present, a number of scientists, doctors, and health care experts are concerned with the 

potential public health effects as a result of the DWH event in the Gulf of Mexico, and they found that the 

VOC’s benzene, a cancer-causing agent, has been found to be above Louisiana’s ambient air quality 

standards. 

The effects of the DWH event on public health and the environment can be classified as the shortterm and long-term effects. The short-term effects includes watery and irritated eyes, skin itching and 

redness, coughing, and shortness of breath or wheezing. As yet, little is know about the long-term health 

effects of direct exposure to oil from the DWH event. Past accidental oil-spill events do not provide 

guidance for the assessment of the long-term impact of the DWH event on public health. 

A survey of large oil-spill events in the past indicates that the long-term effects of an oil spill on 

human health and the environment are still unknown. Several previous large oil spills are described 

below. 

The large oil-spill incidents include the Ixtoc I oil spill in the Bay of Campeche in the Gulf of Mexico 

on June 3, 1979; Exxon Valdez oil spill in Prince William Sound, Alaska, in 1989; the Prestige oil spill in 

the Atlantic Ocean near Spain in 2002; and the DWH event in the Gulf of Mexico in 2010. 

The Ixtoc oil-spill accident occurred in the Bay of Campeche of the Gulf of Mexico on June 3, 1979. 

This oil spill became one of the largest oil spills in history at that time (Jernelöv and Linden, 1981). It 

was estimated that an average of approximately 10,000-30,000 bbl of oil per day were discharged into the 

Gulf of Mexico. It was finally capped on March 23, 1980. Ocean currents carried the oil, which reached 

as far as the Texas coastline. There is no study of the long-term impact of air quality from this oil spill on 

the human health. 

The DWH event occurred in 2010. To assess the effects of the DWH event on human health and the 

environment, the Institute of Medicine held a workshop, “Assessing the Human Health Effects of the Gulf 

of Mexico Oil Spill,” in New Orleans, Louisiana, on June 22-23, 2010. It was reported that people in the 

coastal areas show the stresses and strains of living with the effects of the spill on their livelihood and 

their way of life (McCoy and Salerno, 2010). Due to the volatile chemicals that evaporated from the oil 

spill into the atmosphere, people in the coastal areas have been experiencing sickness, fever, coughing, 

and lethargy. Some of these very dangerous compounds can remain in the air for a long period of time; 

therefore, no one can say with certainty that people will not have long-term effects from the DWH event. 

In summary, there are few studies of the long-term air quality related health effects on humans in the 

assessments of historic oil spills. Although there are minimal studies, some lessons can be learned from 

the 1991 Kuwaiti oil-field fires and the effects of oil burning to the DWH event. In the Kuwaiti event, 

600 oil wells were set in flame. These burnings produced a composite smoke plume of gaseous 

constituents (e.g., NOx, SOx, and CO2, etc.), acid aerosols, VOC’s, metal compounds, PAH’s, and 

particulate matter. Military personnel deployed to the Persian Gulf War have reported a variety of 
Description of the Environment and Impact Analysis 4-19 

symptoms attributed to their exposures, including asthma and bronchitis (Lange et al., 2002). In addition, 

Lange et al. (2002) did not find that exposures to oil fire smoke caused respiratory symptoms among 

veterans. 

Summary and Conclusion 

Emissions of pollutants into the atmosphere from the activities associated with the OCS Program are 

not projected to have significant effects on onshore air quality because of the prevailing atmospheric 

conditions, emission rates and mixing heights, and the resulting pollutant concentrations. Reductions in 

emissions have been achieved through the use of low sulfur fuels, catalytic reduction, and other efforts, 

and as a result, constitute minor impacts to onshore air quality. Onshore impacts on air quality from 

emissions from OCS activities are estimated to be within PSD Class II allowable increments. The 

modeling results indicate that the cumulative impacts to the Breton Wilderness Class I Area are well 

within the PSD Class I allowable increment (Wheeler et al., 2008). 

The Gulf Coast States’ ozone levels are declining because of air-pollution control measures that they 

have implemented. This downward trend is expected to continue as a result of local as well as nationwide 

air-pollution control efforts. The Gulf Coast has significant visibility impairment from anthropogenic 

emission sources. Area visibility is expected to improve somewhat as a result of regional and national 

programs to reduce emissions. 

The incremental contribution of the proposed action (as analyzed in Chapter 4.2.2.1.1 of the Multisale 

EIS) to the cumulative impacts is not significant and is not expected to alter onshore air quality 

classifications because of the prevailing atmospheric conditions, emission rates and mixing heights, and 

the resulting pollutant concentrations. Portions of the Gulf Coast onshore areas have ozone levels that 

exceed the Federal air quality standard, but the incremental contribution from the proposed action is very 

small. The cumulative contribution to visibility impairment from the proposed action is also expected to 

remain very small. Area visibility is expected to improve somewhat as a result of regional and national 

programs to reduce emissions. The proposed action would have an insignificant effect on ozone levels in 

ozone nonattainment areas and would not interfere with the States’ schedule for compliance with the 

NAAQS. More stringent air quality standards have recently been implemented by USEPA; these 

standards may result in increasing the number of parishes/counties in the coastal states that will be in 

violation of the Federal air quality standards, but they would also increase air quality regulations. 

There are few studies on the long-term impact of air quality on human health and the environment in 

the history of oil spills. Each incident is different and exposure factors vary. Therefore, the long-term 

effects on human health and the environment are still unknown. 

4.1.1.2. Water Quality 

For the purposes of this Supplemental EIS, water quality is the ability of a waterbody to maintain the 

ecosystems it supports or influences. In the case of coastal and marine environments, the quality of the 

water is influenced by the rivers that drain into the area, the quantity and composition of wet and dry 

atmospheric deposition, and the influx of constituents from sediments. Besides the natural inputs, human 

activity can contribute to diminished water quality through discharges, run-off, dumping, air emissions, 

burning, and spills. Also, mixing or circulation of the water can either improve the water through 

flushing or be the source of factors contributing to the decline of water quality. 

Evaluation of water quality is done by the measurement of factors that are considered important to the 

health of an ecosystem. The primary factors influencing coastal and marine environments are 

temperature, salinity, dissolved oxygen, nutrients, potential of hydrogen (pH), oxidation reduction 

potential (Eh), pathogens, and turbidity or suspended load. Trace constituents such as metals and organic 

compounds can affect water quality. The water quality and sediment quality may be closely linked. 

Contaminants, which are associated with the suspended load, may ultimately reside in the sediments 

rather than the water column. 

The region under consideration is divided into coastal and offshore waters for the following 

discussion. Coastal waters, as defined by BOEMRE, include all the bays and estuaries from the Rio 

Grande River to Florida Bay (Figure 4-2). Offshore waters, as defined in this Supplemental EIS, include 

both State offshore water and Federal OCS waters, which includes everything outside any barrier islands 

to the Exclusive Economic Zone. The inland extent is defined by the Coastal Zone Management Act. 
4-20 Central Planning Area Supplemental EIS 

The BOEMRE has reexamined the analysis for water quality presented in the Multisale EIS and the 

2009-2012 Supplemental EIS (addition of 181 South Area), based on the additional information presented 

below and in consideration of the DWH event. No substantial new information was found that would 

alter the impact conclusion for water quality presented in the Multisale EIS and the 2009-2012 

Supplemental EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. 

Impacts from routine activities associated with the proposed action would be minimal if all existing 

regulatory requirements are met. Coastal water impacts associated with routine activities include 

increases in turbidity resulting from pipeline installation and navigation canal maintenance, discharges of 

bilge and ballast water from support vessels, and run-off from shore-based facilities. Offshore water 

impacts associated with routine activities result from the discharge of drilling muds and cuttings, 

produced water, residual chemicals used during workovers, structure installation and removal, and 

pipeline placement. The discharge of drilling muds and cuttings causes temporary increased turbidity and 

changes in sediment composition. The discharge of produced water results in increased concentrations of 

some metals, hydrocarbons, and dissolved solids within an area of about 100 m (328 ft) adjacent to the 

point of discharge. Structure installation and removal and pipeline placement disturbs the sediments and 

causes increased turbidity. In addition, offshore water impacts result from supply and service-vessel bilge 

and ballast water discharges. 

Small spills (<1,000 bbl) are not expected to significantly impact water quality in coastal or offshore 

waters. Large spills (1,000 bbl), however, could impact water quality in coastal waters. Accidental 

chemical spills, release of SBF, and blowouts would have temporary localized impacts on water quality. 

The activity associated with the proposed action would contribute a small percentage of the existing 

and future OCS energy industry. The specific discharges, drill muds, cuttings and produced water, and 

accidents resulting in spills would occur in proportion to production and, therefore, could add a small 

increase to the anticipated impacts. Furthermore, the vessel traffic and related discharges associated with 

the proposed action are a fraction of the ongoing commercial shipping and military activity in the Gulf. 

The impacts of discharges, sediment disturbances, and accidental releases are a small percentage of the 

overall activity and the overall impacts to coastal and offshore waters. 

4.1.1.2.1. Coastal Waters 

4.1.1.2.1.1. Description of the Affected Environment 

A detailed description of coastal water quality can be found in Chapter 3.1.2.1 of the Multisale EIS. 

Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.2.1 of the 2009-2012 Supplemental EIS. The following 

information is a summary of the resource description incorporated from the Multisale EIS and the 2009-

2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

The Gulf of Mexico is the ninth largest waterbody in the world (USDOC, NOAA, 2008a). The 

description of the physical oceanography of the Gulf of Mexico is described in Appendix A.2 of the 

Multisale EIS. The United States portion of the Gulf of Mexico region follows the coastline of five states 

from the southern tip of Texas moving eastward through Louisiana, Mississippi, Alabama, and ending in 

the Florida Keys (Figure 4-2). The combined coastline of these states totals over 47,000 mi (75,639 km) 

(when including the shores of all barrier islands, wetlands, inland bays, and inland bodies of water) 

(USDOC, NOAA, 2008a). The Gulf’s coastal areas contain half the wetlands in the United States 

(USDOC, NOAA, 2008a). Wetlands are discussed in further detail in Chapter 4.1.1.4. According to 

USEPA (2008a), the Gulf Coast coastal area comprises over 750 bays, estuaries, and sub-estuary systems 

that are associated with larger estuaries. Gulf Coast estuaries and wetlands provide important spawning, 

nursery, and feeding areas for a wide array of fish wildlife as well as being the home for a wide range of 

indigenous flora and fauna (USEPA, 2008a). The coastal waters of the Gulf Coast are an extremely 

productive natural system (USEPA, 2008a), which is also important to the Gulf Coast economy as the 

major commercial fishing ports in the region yield over 1.2 billion pounds of seafood on an annual basis 
Description of the Environment and Impact Analysis 4-21 

(USDOC, NOAA, 2008a). The natural resources of the Gulf of Mexico are also important for tourism 

and recreation. 

Over 150 rivers empty out of North America into the Gulf of Mexico (Gore, 1992, p. 127). The river 

deltas emptying into the Gulf bring freshwater and sediment into coastal waters (Gore, 1992, 

pp. 127-131), which affect the water quality of these waters. Rivers carry excess nutrients (e.g., nitrogen 

and phosphorus), as well as other possible inputs such as contaminants from industrial wastewater 

discharge, downstream; and this effect is cumulative as the river reaches an estuary (Gore, 1992, pp. 280 

and 291). Overenrichment of nutrients may lead to eutrophication that can eventually cause algal blooms 

and fish kills (Gore, 1992, p. 280) (see below for more information on nutrient enrichment and its effects; 

also see the wetlands and seagrasses discussions in Chapters 4.1.1.4 and 4.1.1.5, respectively). The 

emptying of rivers into the GOM is part of the hydrologic cycle or water cycle (USDOI, GS, 2010a); 

understanding this cycle not only explains the movement of water on Earth but also how water quality 

might be affected by both natural and anthropogenic sources. The water cycle may introduce chemical 

and physical factors that alter the condition of the natural water, such as the addition of waterborne 

pollutants, or the addition of warmer water, into the GOM through waterbodies emptying into the GOM, 

runoff, groundwater discharge, or precipitation. Water quality in coastal waters of the northern Gulf of 

Mexico is highly influenced by season. Seasonality influences salinity and dissolved oxygen; nutrient 

content; temperature; pH and Eh; pathogens; turbidity; metals; and organic compounds. Salinity in open 

water near the coast may vary between 29 and 32 practical salinity units (psu) during fall and winter, but 

it may decline to 20 psu during spring and summer due to increased runoff (USDOI, MMS, 2000). 

Oxygen and nutrient concentrations also vary seasonally. 

The priority water quality issues identified by the Gulf of Mexico Alliance are (1) reducing risk of 

exposure to disease-causing pathogens, (2) minimizing occurrence and effects of harmful algal blooms, 

(3) identifying sources of mercury in Gulf seafood, and (4) improving the monitoring of Gulf water 

resources (Gulf of Mexico Alliance, 2009a). In addition to water quality itself, nutrients and nutrient 

impacts are also a regional priority issue for the organization (Gulf of Mexico Alliance, 2009b). 

The leading source of contaminants that impair coastal water quality is urban runoff. Urban runoff 

can include suspended solids, heavy metals and pesticides, oil and grease, and nutrients. Urban runoff 

increases with population growth, and the Gulf Coast region has experienced a 103 percent population 

growth since 1970 (USDOC, NOAA, 2008a). Other pollutant source categories include (1) agricultural 

runoff, (2) municipal point sources, (3) industrial sources, (4) hydromodification (e.g., dredging), and (5) 

vessel sources (e.g., shipping, fishing, and recreational boating). 

The National Research Council (NRC, 2003, Table I-4, p. 237) estimated that, on average, 

approximately 26,324 bbl of oil per year entered Gulf waters from petrochemical and oil refinery 

industries in Louisiana and Texas. Further, NRC (2003) calculated an estimate for oil and grease loads 

from all land-based sources per unit of urban land area for rivers entering the sea. Based on the size of its 

watershed, the Mississippi River introduced approximately 3,680,938 bbl of oil and grease per year from 

land-based sources (NRC, 2003, Table I-9, p. 242) into the waters of the Gulf of Mexico. 

The zone of hypoxia on the Louisiana-Texas shelf occurs seasonally and is affected by the timing of 

the Mississippi and Atchafalaya Rivers’ discharges carrying nutrients to the surface waters. The hypoxic 

conditions last until local wind-driven circulation mixes the water again. The 2010 GOM dead zone 

covered 20,000 km2

 (7,722 mi2) (LUMCON, 2010a). The 2010 dead zone was reported to be one of the 

largest ever. The area reported in 2009 measured 8,000 km2 (3,000 mi2

) (LUMCON, 2009), while the 

area reported in 2008 measured 20,720 km2

 (8,000 mi2) (LUMCON, 2008). 

Separate zones of hypoxia have been discovered 5-15 mi (8-24 km) off the coast of Texas and are 

likely the result of freshwater inputs generated in Texas and summer upwelling. In 2007 a Texas-created 

dead zone was discovered and attributed to excessive rainfall and runoff into the Brazos River 

(LUMCON, 2010b). 

Since the marine environment is a dynamic system, sediment quality and water quality can affect 

each other. For example, a contaminant may react with the mineral particles in the sediment and be 

removed from the water column (e.g., adsorption). Thus, under appropriate conditions, sediments can 

serve as sinks for contaminants such as metals, nutrients, or organic compounds. However, if sediments 

are (re)suspended (e.g., due to dredging or a storm event), the resuspension can lead to a temporary redox 

flux, including a localized and temporal release of any formally sorbed metals as well as nutrient 

recycling (Caetano et al., 2003; Fanning et al., 1982). 
4-22 Central Planning Area Supplemental EIS 

The overall coastal condition of the Gulf Coast was evaluated from 2001 to 2002 by USEPA and was 

rated as fair to poor (USEPA, 2008a). Specifically, water quality was rated as fair while sediment quality 

and the coastal habit index, a rating of wetlands habitat loss, both of which affect water quality, were 

rated as poor. The USEPA also conducted similar evaluations from 1990 to 1996 (USEPA, 2001) and 

again from 1997 to 2000 (USEPA, 2005). Water quality was poor overall in the first Coastal Condition 

Report, but it increased to fair overall in the latter reports. Conversely, sediment quality was generally 

fair in the first two reports and decreased to poor in the last report. The Barataria/Terrebonne Estuary, 

near Port Fourchon, which is a common service base, was ranked fair in terms of water quality (USEPA, 

2007b) and was assessed as having moderately high eutrophic conditions by NOAA (Bricker et al., 2007). 

The Galveston Bay estuary system was ranked poor in terms of water quality and fair to poor in terms of 

sediment quality (USEPA, 2007b); Galveston Bay was individually characterized as having moderately 

low eutrophic conditions (Bricker et al., 2007). The estuarine area of the Coastal Bend Bays, which 

includes Corpus Christi Bay, was ranked fair in terms of water quality and poor in terms of sediment 

quality (USEPA, 2007b), while Corpus Christi Bay alone was characterized as moderately eutrophic 

(Bricker et al., 2007). 

The NOAA examined additional Gulf Coast estuary systems near the CPA and, of those with 

sufficient data, the Mississippi/Atchafalaya Plume and Perdido Bay had high overall eutrophic conditions, 

Barataria Bay had moderate high overall eutrophic conditions, Breton/Chandeleur Sound and Lake 

Pontchartrain were ranked as having moderate overall eutrophic conditions, the Mississippi River had 

moderately low overall eutrophic conditions, and Mississippi Sound and Lake Borgne had overall low 

eutrophic conditions (Bricker et al., 2007). 

The condition of the Gulf Coast was altered by the DWH event and associated oil spill. It is currently 

impossible to estimate precisely the long-term impacts that the spill from the DWH event will have on 

coastal water quality. Various monitoring efforts and environmental studies have already begun. At the 

time this Supplemental EIS was prepared, the following sources were used for general information 

concerning the DWH event: 

 BP website on the DWH event (http://www.bp.com/

sectiongenericarticle800.do?categoryId=9036575&contentId=7067541); 

 Restore the Gulf website on the DWH response (http://www.data.gov/

restorethegulf/); 

 USEPA website on response to the BP spill in the Gulf of Mexico (http://

www.epa.gov/bpspill/epa.html); 

 National Science Foundation website on rapid response grants to fund DWH research 

(http://nsf.gov/awardsearch/progSearch.do?SearchType=progSearch&page=2&

QueryText=&ProgOrganization=&ProgOfficer=&ProgEleCode=&Boolean

Element=false&ProgRefCode=5987&BooleanRef=false&ProgProgram=&Prog

FoaCode=&Restriction=2&Search=Search#results); 

 Sea Grant website on DWH oil-spill research and monitoring activities database 

(http://gulfseagrant.tamu.edu/oilspill/database.htm); and 

 Joint Analysis Group review of R/V Brooks McCall data to examine subsurface oil 

(http://www.noaa.gov/sciencemissions/PDFs/

JAG_Report_1_BrooksMcCall_Final_June20.pdf). 

More time is needed to fully assess the impacts of the DWH event. Although response efforts 

decreased the fraction of oil remaining in Gulf waters and reduced the amount of oil contacting the 

coastline, significant amounts of oil remain (RestoreTheGulf.gov, 2010a). 

Coastal water quality will not only be impacted by the oil, gas, and their respective components, but 

also to some degree from cleanup and mitigation efforts. Increased vessel traffic, hydromodification 
Description of the Environment and Impact Analysis 4-23 

(e.g., dredging, berm building, etc.) and the addition of dispersants and methanol to the marine 

environment in an effort to contain, mitigate, or clean up the oil may also tax the environment to some 

degree. Fortunately, over time, natural processes can physically, chemically, and biologically degrade oil 

(NRC, 2003). The physical processes involved include evaporation, emulsification, and dissolution; the 

primary chemical and biological degradation processes include photooxidation and biodegradation (i.e., 

microbial oxidation). 

The oil that entered the Gulf of Mexico from the DWH event is a South Louisiana sweet crude oil 

(i.e., it is low in sulfur) (USDOC, NOAA, 2010b). The oil is fairly high in alkanes (organic compounds 

containing only carbon and hydrogen and single bonds; sometimes called paraffin or aliphatic 

compounds) (USDOC, NOAA, 2010b). Because alkanes are simple hydrocarbons, these oils are likely to 

undergo biodegradation more easily (USDOC, NOAA, 2010b). Weathering of crude can occur within the 

first 24-48 hours with up to a 40 percent weight loss within 7 days (English, 2010). Also, this oil is less 

toxic than other crude oils in general because this oil is lower in PAH’s than many crude oils. 

The DWH event released natural gas into the water column in addition to oil. Methane is the primary 

component of natural gas (NaturalGas.org, 2010b). Limited research is available for the biogeochemistry 

of hydrocarbon gases in the marine environment (Patin, 1999, p 233). Methane may stay in the marine 

environment for long periods of time (Patin, 1999, p. 237) as methane is highly soluble in seawater at the 

high pressures and cold temperatures found in deepwater environments (NRC, 2003, p. 108); however, 

methane diffusing through the water column would likely be oxidized in the aerobic zone and would 

rarely reach the air-water interface (Mechalas, 1974, p. 23). Unfortunately, little is known about methane 

toxicity in the marine environment, but there is concern as to how methane in the water column might 

affect fish (Chapter 4.1.1.16). 

Surface water samples collected along the Gulf Coast in Florida and Alabama by USEPA on 

June 28 and 29, 2010, found that nickel exceeded acute aquatic life benchmarks in one sample and 

chronic aquatic life benchmarks in two other samples, which could cause risk to aquatic life (USEPA, 

2010f). The USEPA also collected coastal surface water samples on May 21-June 29, 2010, along the 

coast of Louisiana; the samples were analyzed for two chemicals associated with dispersants, but neither 

chemical was detected. Surface water samples collected on September 11, 2010, by USEPA found two 

samples that exceeded chronic aquatic benchmarks for nickel, and one sample exceeded acute and chronic 

aquatic benchmarks for oil-related compounds. Fortunately, none of the samples exceeded human health 

benchmarks (USEPA, 2010f). Gulf Coast sediment samples were also collected on June 29 and 30, 2010, 

but they did not reveal elevated levels of chemicals usually found in oil (USEPA, 2010g). Sediment 

samples taken as of July 9, 2010, indicated that there may be risks to aquatic life from sediment pollutants 

at some of USEPA’s sampling locations. The USEPA noted that, “These levels have a higher potential 

for serious impacts to sediment-dwelling organisms and are classified as unhealthy. It is unknown 

whether the sediment contamination resulted from the BP spill or was already present.” In addition, 

samples collected on August 28 and September 9 and 10, 2010, along the Gulf Coast did not detect 

dispersant components above reporting limits. Coastal sediment samples collected on 

September 14 and 15, 2010, found one sample that exceeded the chronic aquatic benchmark for oilrelated compounds, while sediment samples collected on September 9-10 and 14-16, 2010, did not detect 

dispersant chemicals at levels above reporting limits (USEPA, 2010g). More data should evolve over 

time and eventually data is likely to be placed into context through various reports or papers, which will 

hopefully provide data on background levels of any contaminants of concern before the spill. 

One standard tool used in response to spilled oil on water is dispersants. The purpose of chemical 

dispersants is to facilitate the movement of oil into the water column in order to encourage weathering 

and biological breakdown of the oil (i.e., biodegradation) (NRC, 2005; Australian Maritime Safety 

Authority, 2010). If the oil moves into the water column and is not on the surface of the water, it is less 

likely to reach sensitive shore areas (USEPA, 2010h). Since sea birds are often on the surface of the 

water or in shore areas, dispersants are also considered to be very effective in reducing the exposure of 

sea birds to oil (Australian Maritime Safety Authority, 2010). In addition to dispersion being enhanced 

by artificial processes, oil may also be dispersed from natural processes. For instance, microbial 

metabolism of crude oil results in the dispersion of oil (Bartha and Atlas, 1983). Oil dispersion, as a spillresponse strategy, has both positive and negative effects. The positive effect is that the oil, once 

dispersed, is more available to be degraded. The negative effect is that the oil, once dispersed, is more 

available to microorganisms that temporarily increases the toxicity (Bartha and Atlas, 1983). The toxicity 
4-24 Central Planning Area Supplemental EIS 

of dispersed oil in the environment will depend on many factors, including the effectiveness of the 

dispersion, temperature, salinity, the degree of weathering, type of dispersant, and degree of light 

penetration in the water column (NRC, 2005). The toxicity of dispersed oil is primarily due to the toxic 

components of the oil itself (Australian Maritime Safety Authority, 2010). 

Corexit 9500 and 9527 were used in response to the DWH event and resulting spill (USEPA, 2010h). 

The components of these dispersants are identical with the exception of the base solvent; Corexit 9527 

has an organic solvent as a base (McDonald et al. 1984; USEPA, 2010h). Dispersants used in the 1960’s 

were quite toxic, but more recently developed dispersants such as Corexit are considerably less toxic (Doe 

and Wells, 1978; Leahy and Colwell, 1990). Lindstrom and Braddock (2002) found that environmental 

use of Corexit 9500 could result in either increases or decreases in the toxicity of residual oil through 

selective microbial mineralization of hydrocarbons. In fact, reviews of studies have found that the 

general effectiveness of dispersants in enhancing biodegradation of crude oil and individual hydrocarbons 

is highly variable and depends on several factors, including the chemical formulation of the dispersant, its 

concentration, and the dispersant/oil application ratio (Boehm, 1983). However, there was evidence that 

the dispersants worked in the case of the DWH event (USDOC, NOAA, 2010c; USEPA, 2010h). Corexit 

9527 has been shown to greatly increase volatile liquid hydrocarbons incorporation into water, as well as 

to accelerate the process in experiments compared with observations where no dispersant was used 

(McDonald et al. 1984). In fact, dispersants used during the DEH event incident has been noted to reduce 

the volatile organic compounds that can be a workplace issue for response workers on ships near the site 

(White House Press Briefing, 2010). Since the amount of dispersants used for the spill resulting from the 

DWH event is unprecedented and since this is the first time dispersants have been applied in such 

quantities on the surface in deep waters, and at the depth of the well itself, continual monitoring and 

evaluation of their use is imperative (White House Press Briefing, 2010). 

As a result of the use of subsea dispersants, clouds or plumes of dispersed oil may occur near the 

blowout site far from coastal waters. Reports thus far from researchers deployed after the DWH event 

and resulting spill have found such plumes and have shown that the concentrations of these clouds drop to 

undetectable levels within a few miles (USDOC, NOAA, 2010c). Dissolved oxygen levels are a concern 

with any release of a carbon source, such as oil and natural gas, and became a particular concern during 

the DWH event since dispersants were applied at the wellhead for the first time. Thus, USEPA required 

monitoring protocols in order to use subsea dispersants (USDOC, NOAA, 2010d). In areas where plumes 

of dispersed oil were previously found, dissolved oxygen levels decreased by about 20 percent from longterm average values in the GOM; however, scientists reported that these levels have stabilized and are not 

low enough to be considered hypoxic (USDOC, NOAA, 2010e). The drop in oxygen, which has not 

continued over time, has been attributed to microbial degradation of the oil. Initially released studies 

indicate that bacteria are degrading hydrocarbons from both gas and oil, but the degradation rates reported 

in the studies varied considerably (Camilli et al., 2010, Hazen et al., 2010, Valentine et al., 2010). Over 

time, as the oil continues to be degraded and diffused, hypoxia becomes less of a concern. In fact, the 

2010 hypoxic zone could not be linked to the DWH event in either a positive or a negative manner 

(LUMCON, 2010a). 

During the DWH event, one of the earlier attempts to stop the oil from leaking from the well was a 

procedure called a “top kill” (RestoreTheGulf.gov, 2010b). The top kill involved using water-based 

drilling muds, which are heavy due to the mineral component barite, in order to stop flow from the well. 

This procedure was not successful, but during the procedure, 29,712 bbl of water-based mud were used 

(Boland, personal communication, 2010). Much of this mud ended up on the seafloor. The primary 

general components of water-based mud (also referred to as water-based drilling fluids) are fresh or 

saltwater, barite, clay, caustic soda, lignite, lignosulfonates, and water-soluble polymers (USDOI, 

BOEMRE, 2010h). Water-based drilling mud may be discharged to the ocean under normal operations, 

but those discharges are regulated by USEPA (USDOI, BOEMRE, 2010h). The BOEMRE research has 

shown that drilling mud discharges do not move very far, even when discharged at the surface (CSA, 

2006a). Since the muds were discharged in deep water, it is not expected that coastal waters and 

sediments will suffer significant adverse effects. 
Description of the Environment and Impact Analysis 4-25 

4.1.1.2.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine impacts on coastal water quality can be found in Chapter 4.2.1.1.2.1 

of the Multisale EIS. Additional information for the 181 South Area and any new information since the 

publication of the Multisale EIS is presented in Chapter 4.1.2.1.2 of the 2009-2012 Supplemental EIS. 

The following is a summary of the information incorporated from the Multisale EIS and the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

Proposed Action Analysis 

The routine activities associated with the CPA proposed action that would impact water quality 

include the following: 

 discharges during drilling of exploration and development wells; 

 structure installation and removal; 

 discharges during production; 

 installation of pipelines; 

 workovers of wells, 

 maintenance dredging of existing navigational canals; 

 service vessel discharges; and 

 nonpoint-source runoff. 

The scenario information related to the CPA proposed action is presented in Table 3-2. 

Sediment disturbance and turbidity may result from nearshore pipeline installation or maintenance 

dredging. The installation of pipelines can increase the local total suspended solids in the water. The 

adverse effect on water quality would be temporary and localized. Chapter 4.1.2.1.7 of the Multisale EIS 

notes that COE and State permits would require these turbidity impacts to be mitigated through the use of 

turbidity screens and other turbidity reduction or confinement equipment. No new navigation channels 

are expected to be dredged as a result of the CPA proposed action, but the CPA proposed action would 

contribute to maintenance dredging of existing navigation canals. Maintenance dredging would 

temporarily increase turbidity levels in the vicinity of the dredging and disposal of materials. 

In coastal waters, the water quality would be impacted by the discharges from the service vessels in 

port. Service-vessel round trips projected for the CPA proposed action are 137,000-220,000 trips over the 

40-year life of the proposed action (Table 3-2). Based on current service-base usage, it is assumed the 

majority of these trips would occur in Louisiana’s coastal waters. The types of discharges and regulations 

are discussed in Chapters 4.1.1.4.8 and 4.1.2.2.2 of the Multisale EIS. Most discharges are treated or 

otherwise managed prior to release. In coastal waters, bilge and ballast water may be discharged with an 

oil content of 15 ppm or less (33 CFR 151.10). The discharges would affect the water quality locally. 

However, regulations are becoming more stringent. The USCG Ballast Water Management Program 

became mandatory for some vessels in 2004 (33 CFR 151 Subparts C and D) (U.S. Dept. of Homeland 

Security, CG, 2010b). The goal of the program was designed to prevent the introduction on 

nonindigenous (invasive) species that would affect local water quality. Furthermore, USCG published the 

Ballast Water Discharge Standard Notice of Proposed Rulemaking in the Federal Register on August 28, 

2009. Additionally, the final Vessel General Permit, issued by USEPA, became effective on 

December 19, 2008. This permit is in addition to already existing NPDES permit requirements and now 

increases the NPDES regulations so that discharges incidental to the normal operation of vessels 

operating as a means of transportation are no longer excluded unless exempted from NPDES permitting 

by Congressional legislation (USEPA, 2008b). 
4-26 Central Planning Area Supplemental EIS 

Up to one new gas processing plant is projected as a result of the CPA proposed action. In addition, 

the CPA proposed action would contribute to the use of existing onshore facilities in Louisiana, 

Mississippi, Alabama, and possibly Texas. These supporting onshore facilities would discharge into local 

wastewater treatment plants and waterways during routine operations. The types of onshore facilities 

were discussed in Chapter 4.1.2.2.1 of the Multisale EIS. All point-source discharges are regulated by 

USEPA, the agency responsible for coastal water quality, or the USEPA-authorized State agency. The 

USEPA’s NPDES storm-water effluent limitation guidelines control storm-water discharges from support 

facilities. Indirect impacts could occur from nonpoint-source runoff, such as rainfall, which has drained 

from infrastructure such as a public road and parking lot, and may contribute hydrocarbons, trace-metal 

pollutants, and suspended sediments. These indirect impacts would be minimal, as long as existing 

regulations are followed, and difficult to discern from other sources. 

Summary and Conclusion 

The primary impacting sources to water quality in coastal waters are point-source and storm-water 

discharges from support facilities, vessel discharges, and nonpoint-source runoff. These activities are not 

only highly regulated but also localized and temporary in nature. The impacts to coastal water quality 

from routine activities associated with the CPA proposed action should be minimal as long as all existing 

regulatory requirements are met. 

4.1.1.2.1.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental events on coastal water quality can be found in Chapter 4.4.2.1 of 

the Multisale EIS. Additional information for the 181 South Area and any new information since the 

publication of the Multisale EIS is presented in Chapter 4.1.2.1.3 of the 2009-2012 Supplemental EIS. 

The following is a summary of the information incorporated from the Multisale EIS and the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

Accidental events associated with the CPA proposed action that could impact coastal water quality 

include spills of oil and refined hydrocarbons, releases of natural gas, spills of chemicals or drilling fluids, 

and loss of well control, collisions, or other malfunctions that would result in such spills. Chapter 3.2

discusses the accidental events that could result from the impact-producing factors and scenario, with 

particular attention given to the risk of oil spills, response to such oil spills, loss of well control, pipeline 

failures, vessel collisions, and chemical and drilling fluid spills. A brief summary is presented here. The 

impacts of rare, catastrophic spills are discussed in Appendix B. A catastrophic event would not be 

expected to occur in coastal waters, but a catastrophic spill in offshore waters could affect coastal waters. 

Proposed Action Analysis 

Oil Spills and Natural Gas and Condensate Releases 

Water quality is altered and degraded by oil spills through the increase of petroleum hydrocarbons 

and their various transformation/degradation products in the water. The extent of impact from a spill 

depends on the behavior and fate of oil in the water column (e.g., the movement of oil and the rate and 

nature of weathering), which, in turn, depends on oceanographic and meteorological conditions at the 

time (Appendix A.2 and A.3 of the Multisale EIS). Crude oils are not a single chemical, but instead are 

complex mixtures with varied compositions. The various fractions within the crude behave differently in 

water. Thus, the behavior of the oil and the risk that the oil poses to natural resources depends on the 

composition of the specific oil encountered (Michel, 1992). Generally, oils can be divided into three 

groups of compounds: (1) light-weight; (2) medium-weight; and (3) heavy-weight components. Chapter 

3.2.1 further characterizes the components of oil and discusses oil spills. Chapter 4.3.1 of the Multisale 

EIS also discusses oil spills in further detail, with Chapter 4.3.1.4 of the Multisale EIS describing the 

characteristics of OCS oil. Generally, the lighter ends of the oil are more water soluble and would 

contribute to acute toxicity. As the spill weathers, the aromatic components at the water’s surface are 
Description of the Environment and Impact Analysis 4-27 

more likely to exit the water. The heavier fractions are less water soluble and would partition to organic 

matter. This fraction is more likely to persist in sediments and would contribute to longer-term impacts. 

In addition to oil, natural gas may also be explored for or produced in the GOM. Wells and sidetracks 

may produce a mixture of both oil and natural gas. Condensate is a liquid hydrocarbon phase that 

generally occurs in association with natural gas. The quality and quantity of components in natural gas 

vary widely by the field, reservoir, or location from which the natural gas is produced. Although there is 

not a “typical” makeup of natural gas, it is primarily composed of methane (NaturalGas.org, 2010b). 

Thus, if natural gas were to leak into the environment, methane may be released to the environment. 

Methane is a carbon source, such as oil, and its introduction into the marine environment could result in 

lowering dissolved oxygen levels due to microbial degradation. Unfortunately, little is known about the 

toxicity of natural gas and its components in the marine environment, but there is concern as to how 

methane in the water column might affect fish (Chapter 4.1.1.16). 

The National Academy of Sciences (NRC, 2003), Patin (1999), and Boesch and Rabalais (1987) have 

reviewed the fate and effects of spilled oil and, to a lesser degree, natural gas releases. Chapter 4.3.1.7 of 

the Multisale EIS presents the risk of coastal spills associated with the proposed action, and Chapter 

3.2.1.3 of this Supplemental EIS supplements and updates that information. Spills in coastal waters could 

occur at storage or processing facilities supporting the OCS oil and gas industry or from the transportation 

of OCS-produced oil through State offshore waters and along navigation channels, rivers, and through 

coastal bays. For coastal spills, two additional factors that must be considered are the shallowness of the 

area the spill is in and the proximity to shore. Spills in coastal waters are more likely to be in shallow 

waters than offshore spills. Spills near the shore are less likely to be diluted since the volume of water in 

shallow waters is less than in deep waters. Furthermore, spills are more likely to contact land as there is 

less distance from the spill to land and less time for the oil to weather before it reaches the shore. Since 

oil does not mix with water and is usually less dense, most of the oil forms a slick at the surface. Small 

droplets in the water may adhere to suspended sediment and be removed from the water column. Oil may 

also penetrate sand on the beach or be trapped in wetlands, where it can be re-released into the water 

some time after the initial spill. 

In the case of an accidental event, it is likely that response efforts would reduce the amount of oil. 

Chapter 3.2.1.5 provides a further discussion of oil-spill-response considerations. Coastal water quality 

would not only be impacted by the oil, gas, and their respective components but also to some degree from 

cleanup and mitigation efforts. Increased vessel traffic, hydromodification (e.g., dredging, berm building, 

etc.), and the addition of dispersants and methanol to the marine environment in an effort to contain, 

mitigate, or clean up the oil may also tax the environment to some degree. 

One standard tool used in response to spilled oil on water is dispersants. Dispersants are not 

preauthorized for use in coastal areas (NRC, 2005), but it is possible that the use of dispersants in offshore 

spills may have effects on coastal environments. The purpose of chemical dispersants is to facilitate the 

movement of oil into the water column in order to encourage weathering and biological breakdown of the 

oil (i.e., biodegradation) (NRC, 2005; Australian Maritime Safety Authority, 2010). If the oil moves into 

the water column and is not on the surface of the water, it is less likely to reach sensitive shore areas 

(USEPA, 2010h). The toxicity of dispersed oil in the environment will depend on many factors, 

including the effectiveness of the dispersion, temperature, salinity, the degree of weathering, type of 

dispersant, and degree of light penetration in the water column (NRC, 2005). The toxicity of dispersed oil 

is primarily due to the toxic components of the oil itself (Australian Maritime Safety Authority, 2010). 

Fortunately, over time, natural processes can physically, chemically, and biologically degrade oil 

(NRC, 2003). The physical processes involved include evaporation, emulsification and dissolution; the 

primary chemical and biological degradation processes include photooxidation and biodegradation (i.e., 

microbial oxidation). 

Chemical Spills 

A study of chemical spills from OCS activities determined that accidental releases of zinc bromide 

and ammonium chloride could potentially impact the marine environment (Boehm et al., 2001). Both of 

these chemicals are used for well treatment or completion and are not in continuous use; thus, the risk of a 

spill is small. Most other chemicals are either relatively nontoxic or used in such small quantities that a 

spill would not result in measurable impacts. Zinc bromide is of particular concern because of the toxic 
4-28 Central Planning Area Supplemental EIS 

nature of zinc. Close to the release point of an ammonium chloride spill, the ammonia concentrations 

could exceed toxic levels. 

Pipeline Failures 

A pipeline failure would result in the release of crude oil, condensate, or natural gas; the impacts of 

which are discussed above. Pipeline failures are discussed in more detail in Chapter 3.2.3. 

Fuel Oil Spills from Collisions 

A collision may result in the spillage of crude oil, refined products such as diesel, or chemicals. 

Crude oil and chemicals are discussed in the preceding paragraphs. Diesel is the type of refined 

hydrocarbon spilled most frequently as the result of a collision. Minimal impacts result from a spill since 

diesel is light and will evaporate and biodegrade within a few days (USDOC, NOAA, 2006). A collision 

could result in the release of up to the entire contents of the fuel tanks. Since collisions occur 

infrequently, the potential impacts to coastal water quality are not expected to be significant. 

Summary and Conclusion 

Accidental events associated with the CPA proposed action that could impact coastal water quality 

include spills of oil and refined hydrocarbons, releases of natural gas and condensate, and spills of 

chemicals or drilling fluids. The loss of well control, pipeline failures, collisions, or other malfunctions 

could also result in such spills. Although response efforts may decrease the amount of oil in the 

environment, the response efforts may also impact the environment. Natural degradation processes would 

also decrease the amount of spilled oil over time. For coastal spills, two additional factors that must be 

considered are the shallowness of the area and the proximity of the spill to shore. Over time, natural 

processes can physically, chemically, and biologically degrade oil. Chemicals used in the oil and gas 

industry are not a significant risk in the event of a spill because they are either nontoxic, used in minor 

quantities, or are only used on a noncontinuous basis. Spills from collisions are not expected to be 

significant because collisions occur infrequently. 

4.1.1.2.1.4. Cumulative Impacts 

A detailed description of cumulative impacts upon water quality can be found in Chapter 4.5.2 of the 

Multisale EIS and in Chapter 4.1.2.1.4 of the 2009-2012 Supplemental EIS. 

Activities in the cumulative scenario that could impact coastal water quality generally include the 

broad categories of the proposed action and the OCS Program, State oil and gas activity, the activities of 

other Federal agencies (including the military), natural events or processes, and activities related to the 

direct or indirect use of land and waterways by the human population (e.g., urbanization, agricultural 

practices, coastal industry, and municipal wastes). Many of these categories would cause some of the 

same specific impacts (e.g., vessel traffic would occur for all of those categories except natural 

processes). 

Sediment disturbance and turbidity may result from nearshore pipeline installation, maintenance 

dredging, disposal of dredge materials, sand borrowing, sediment deposition from rivers, and hurricanes. 

Turbidity is also influenced by the season. These impacts may be the result of Gulfwide OCS-related 

activities, State oil and gas activities, the activities of other Federal agencies, and natural processes. 

Dredging projects related to restoration or flood prevention measures may be directed by the Federal 

Government for the benefit of growing coastal populations. Chapter 4.1.2.1.7 of the Multisale EIS notes 

that COE and State permits would require that the turbidity impacts due to pipeline installation be 

mitigated by using turbidity screens and other turbidity reduction or confinement equipment. These 

impacts generally degrade water quality locally and are not expected to last for long periods of time. 

Vessel discharges can degrade water quality. Vessels may be service vessels supporting the proposed 

action, OCS-related activities, or State oil and gas activities. However, the vessels may also be vessels 

used for shipping, fishing, military activities, or recreational boating. Fortunately, for many types of 

vessels, most discharges are treated or otherwise managed prior to release through regulations 

administered by USCG and/or USEPA, and many regulations are becoming more stringent. For example, 
Description of the Environment and Impact Analysis 4-29 

the USCG Ballast Water Management Program, which was designed to prevent the introduction of 

invasive species, became mandatory for some vessels in 2004 (33 CFR 151 Subparts C and D) 

(U.S. Dept. of Homeland Security, CG, 2010b). Furthermore, USCG published the Ballast Water 

Discharge Standard Notice of Proposed Rulemaking in the Federal Register on August 28, 2009. 

Additionally, the final Vessel General Permit, issued by USEPA, became effective on December 19, 

2008. This permit is in addition to already existing NPDES permit requirements and now increases the 

NPDES regulations so that discharges incidental to the normal operation of vessels operating as a means 

of transportation are no longer excluded unless exempted from NPDES permitting by Congressional 

legislation (USEPA, 2008b). These regulations should minimize the cumulative impacts of vessel 

activities. 

Erosion and runoff from nonpoint sources degrade water quality. Nonpoint-source runoff from 

onshore support facilities could result from OCS-related activities as well as State oil and gas activities 

and other industries and coastal development. The leading source of contaminants that impair coastal 

water quality is urban runoff. Urban runoff can include suspended solids, heavy metals and pesticides, oil 

and grease, and nutrients. Urban runoff increases with population growth, and the Gulf Coast region has 

experienced a 103 percent population growth since 1970 (USDOC, NOAA, 2008a). The natural 

emptying of rivers into the GOM as part of the water cycle may introduce chemical and physical factors 

that alter the condition of the natural water through both natural and anthropogenic sources, such as the 

addition of waterborne pollutants, or the addition of warmer water, into the GOM through waterbodies 

emptying into the GOM, runoff, groundwater discharge, or precipitation. Nutrients carried in waters of 

the Mississippi River contribute to seasonal formation of the hypoxic zone on the Louisiana-Texas shelf. 

Recently, USEPA has proposed the first set of nutrient standards; the first set of standards is for the State 

of Florida (USEPA, 2010i). The proposed new water quality standards would set a series of numeric 

nutrient (nitrogen and phosphorus) limitations for Florida’s lakes, rivers, steams, springs, and canals. The 

USEPA also regulates point-source discharges. Chapter 4.5.2.1 of the Multisale EIS summarizes the 

regulatory programs designed to protect the waters that enter the Gulf. If these and other water quality 

programs and regulations continue to be administered and enforced, it is not expected that additional oil 

and gas activities would adversely impact the overall water quality of the region. 

Water quality in coastal waters of the northern Gulf of Mexico is also highly influenced by season. 

Seasonality influences salinity and dissolved oxygen, nutrient content, temperature, pH and Eh, 

pathogens, turbidity; metals, and organic compounds. 

Since the marine environment is a dynamic system, sediment quality and water quality can affect 

each other. For example, a contaminant may react with the mineral particles in the sediment and be 

removed from the water column (e.g., adsorption). Thus, under appropriate conditions, sediments can 

serve as sinks for contaminants such as metals, nutrients, or organic compounds. However, if sediments 

are (re)suspended (e.g., due to dredging or a storm event), the resuspension can lead to a temporary redox 

flux, including a localized and temporal release of any formally sorbed metals as well as nutrient 

recycling (Caetano et al., 2003; Fanning et al., 1982). 

Accidental releases of oil, gas, or chemicals would degrade water quality during and after the spill 

until either the spill is cleaned up or natural processes degrade or disperse the spill. These accidental 

releases could be a result of the proposed action, ongoing OCS activity, State oil and gas activity, the 

transport of commodities to ports, and/or coastal industries. The impacts of rare, catastrophic spills are 

discussed in Appendix B. A catastrophic event would not be expected to occur in coastal waters, but a 

catastrophic spill in offshore waters could affect coastal waters. The extent of impact from a spill 

depends on the behavior and fate of oil in the water column (e.g., the movement of oil and the rate and 

nature of weathering), which, in turn, depends on oceanographic and meteorological conditions at the 

time (Appendix A.2 and A.3 of the Multisale EIS). Chapter 4.5.2.1 of the Multisale EIS contains more 

information on accidental releases. A major hurricane can result in a greater number of coastal oil and 

chemical spill events with increased spill volume and decreases in oil-spill-response times. In the case of 

an accidental event, it is likely that response efforts would reduce the amount of oil. Chapter 3.2.1.5

provides further discussion of oil-spill-response considerations. Coastal water quality would not only be 

impacted by the oil, gas, and their respective components but also to some degree from cleanup and 

mitigation efforts. Increased vessel traffic, hydromodification (e.g., dredging, berm building, etc.) and the 

addition of dispersants and methanol to the marine environment in an effort to contain, mitigate, or clean 

up the oil may also tax the environment to some degree. 
4-30 Central Planning Area Supplemental EIS 

Summary and Conclusion 

Water quality in coastal waters would be impacted by sediment disturbance and suspension (i.e., 

turbidity), vessel discharges, erosion, and runoff from nonpoint-source pollutants including river inflows, 

seasonal influences, and accidental events. These impacts may be a result of the proposed action and the 

OCS Program, State oil and gas activity, the activities of other Federal agencies (including the military), 

natural events or processes, or activities related to the direct or indirect use of land and waterways by the 

human population (e.g., urbanization, agricultural practices, coastal industry, and municipal wastes). The 

impacts resulting from the CPA proposed action are a small addition to the cumulative impacts on the 

coastal waters of the Gulf. Increased turbidity and discharge from the CPA proposed action would be 

temporary in nature and minimized by regulations and mitigation. Since a catastrophic accident is both 

rare and not expected to occur in coastal waters, the impact of accidental spills is expected to be small. 

The incremental contribution of the routine activities and accidental events associated with the proposed 

action to the cumulative impacts on coastal water quality is not expected to be significant as long as all 

regulations are followed. 

4.1.1.2.2. Offshore Waters 

4.1.1.2.2.1. Description of the Affected Environment 

A detailed description of offshore water quality can be found in Chapter 3.1.2.2 of the Multisale EIS. 

Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.2.2 of the 2009-2012 Supplemental EIS. The following 

information is a summary of the resource description incorporated from the Multisale EIS and the 2009-

2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

The Gulf of Mexico is the ninth largest waterbody in the world (USDOC, NOAA, 2008a). Over 150 

rivers empty out of North America into the Gulf of Mexico (Gore, 1992, p. 127). The majority of this 

input is accounted for by the two largest United States Deltas, the Mississippi and the 5-river Mobile Bay 

System (Gore, 1992, p. 127). The river deltas emptying into the Gulf bring freshwater and sediment into 

coastal waters (Gore, 1992, pp. 127-131), which affect the water quality of these waters. Rivers carry 

excess nutrients (e.g., nitrogen and phosphorus), as well as other possible inputs such as contaminants 

from industrial wastewater discharge, downstream; and this effect is cumulative as the river reaches an 

estuary (Gore, 1992, pp. 280 and 291). The emptying of rivers into the GOM is part of the hydrologic 

cycle or water cycle (USDOI, GS, 2010a); understanding this cycle not only explains the movement of 

water on Earth but also how water quality might be affected by both natural and anthropogenic sources. 

The water cycle may introduce components into the GOM through waterbodies emptying into the GOM, 

runoff, groundwater discharge, or precipitation. Water quality can be affected by not only chemical 

processes but also by physical and biological processes. For example, the water quality of the Gulf of 

Mexico is influenced by the physical oceanography of the Gulf of Mexico, which is described in 

Appendix A.2 of the Multisale EIS. Besides nutrients, water quality is generally gauged by measuring a 

series of parameters commonly including, but not limited to, temperature, salinity, dissolved oxygen, pH, 

Eh, pathogens, and turbidity. Water quality may also examine possible pollutants such as metals and 

organic compounds. 

The water offshore of the Gulf’s coasts can be divided into two regions: shallow (<1,000 ft; 305 m) 

and deep water (>1,000 ft; 305 m). Waters on the continental shelf (0-200 m; 0-656 ft) and slope 

(200-2,000 m; 656-6,562 ft) are heavily influenced by the Mississippi and Atchafalaya Rivers, the 

primary sources of freshwater, sediment, nutrients, and pollutants from a huge drainage basin 

encompassing 55 percent of the continental U.S. (Murray, 1998). The presence or extent of a nepheloid 

layer, a body of suspended sediment at the sea bottom (Kennet, 1982, p. 524), affects water quality on the 

shelf and slope. Deep waters east of the Mississippi River are affected by the Loop Current and 

associated warm-core (anticyclonic) eddies, which consist of clear, low-nutrient water (Muller-Karger et 

al., 2001). However, cold-core cyclonic eddies (counterclockwise rotating) also form at the edge of the 

Loop Current and are associated with upwelling and nutrient-rich, high-productivity waters. More details 

on the physical oceanography of the Gulf of Mexico are available in Appendix A.2 of the Multisale EIS 

and in Chapter 3.3.7.1 of this Supplemental EIS. 
Description of the Environment and Impact Analysis 4-31 

Seawater generally averages pH 8 at the surface due to marine systems being buffered by carbonates 

and bicarbonates; however, in the open waters of the Gulf of Mexico, pH ranges from approximately 8.1 

to 8.3 at the surface (Gore, 1992, p. 87). The pH decreases to approximately 7.9 at a depth of 700 m 

(2,297 ft), and in deeper waters, it increases again to approximately 8.0 (Gore, 1992, p. 87). 

The salinity in the Gulf of Mexico is generally 36 ppt (Gore, 1992, p. 87). Lower salinities are 

characteristic nearshore where freshwater from the rivers mix with Gulf waters. For example, salinity can 

decrease to less than 25 ppt near inlets due to the emptying of rivers (runoff) (Gore, 1992, p. 81). Salinity 

also varies seasonally. For example, salinity in open water near the coast may vary between 29 and 32 

practical salinity units (psu) during fall and winter but decline to 20 psu during spring and summer due to 

increased runoff (USDOI, MMS, 2000) (practical salinity units [psu] are similar to parts per thousand 

[ppt], but not identical). 

Temperatures in the Gulf of Mexico vary seasonally. The average summer surface temperature is 

approximately 29 oC (84 oF) (Gore, 1992, p. 79). In winter, temperature in the northern Gulf is 19 oC 

(65 F) and in the southern portion of the Gulf, it is about 24 oC (75 oF) (Gore, 1992, p. 79). However, 

temperatures may dip lower during cold fronts. In winter, seawater is well mixed (Gore, 1992, p. 80). At 

other times, sea-surface temperatures can vary from temperatures at depth. In the summer, warm water 

may be found from the surface down to a certain depth known at the thermocline; below this depth, the 

temperature becomes cooler and therefore the water becomes denser (Gore, 1992, pp. 79-80). In the Gulf, 

the thermocline may be found anywhere from just below the surface to 160 ft (50 m) deep. Seawater also 

gets colder in deep water. Below 1,000 m (about 3,300 ft), temperatures are the coldest in the Gulf at 

<4.4 oC (40 oF). 

Dissolved oxygen enters the upper waters (~100-200 m; 328-656 ft) of Gulf of Mexico through the 

atmosphere and photosynthesis (Jochens et al., 2005). In deep waters, dissolved oxygen is introduced 

through the transport and mixing of oxygen-rich watermasses into the Gulf of Mexico from the Caribbean 

Sea through the Yucatan Channel (Jochens et al., 2005). The Gulf of Mexico does not have watermass 

formation to replenish the deep oxygen concentrations (Jochens et al., 2005). Thus, the deep circulation 

of the Gulf of Mexico and its related mixing are the mechanisms that replenish the deep oxygen (Jochens 

et al., 2005). Oxidation of organic matter is the major oxygen sink in the Gulf of Mexico (Jochens et al., 

2005). The Gulf of Mexico has an oxygen minimum zone, which is generally located from 300 to 700 m 

(984 to 2,297 ft) (Jochens et al., 2005). 

The zone of hypoxia on the Louisiana-Texas shelf occurs seasonally and is affected by the timing of 

the Mississippi and Atchafalaya Rivers’ discharges carrying nutrients to the surface waters. The hypoxic 

conditions last until local wind-driven circulation mixes the water again. The 2010 GOM dead zone 

covered 20,000 km2

 (7,722 mi2) (LUMCON, 2010a). Nutrients from the Mississippi River fueling 

enhanced phytoplankton is what was attributed to the formation of the hypoxic zone. The 2010 dead zone 

was reported to be one of the largest ever. The area reported in 2009 measured 8,000 km2 (3,000 mi2

) 

(LUMCON, 2009), while the area reported in 2008 measured 20,720 km2

 (8,000 mi2) (LUMCON, 2008). 

The priority, water quality issues identified by the Gulf of Mexico Alliance are (1) reducing risk of 

exposure to disease-causing pathogens, (2) minimizing occurrence and effects of harmful algal blooms, 

(3) identifying sources of mercury in Gulf seafood, and (4) improving the monitoring of Gulf water 

resources (Gulf of Mexico Alliance, 2009a). In addition to water quality itself, nutrients and nutrient 

impacts are also a regional priority issue for the organization (Gulf of Mexico Alliance, 2009b). 

As noted above, coastal waters are greatly affected by runoff. Runoff may include any number of 

pollutants such as nutrients, pesticides and other organic chemicals, and metals. Shallow water on the 

shelf and slope are also affected by runoff. The National Research Council (2003, Table I-4, p. 237) 

estimated that, on average, approximately 26,324 bbl of oil per year entered Gulf waters from 

petrochemical and oil refinery industries in Louisiana and Texas. The Mississippi River introduced 

approximately 3,680,938 bbl of oil and grease per year from land-based sources (NRC, 2003, Table I-9, 

p. 242) into the waters of the Gulf of Mexico. Offshore waters, especially deeper waters, are more 

directly affected by natural seeps since the natural seeps in the Gulf of Mexico are located in offshore 

waters. Hydrocarbons enter the Gulf of Mexico through natural seeps in the Gulf of Mexico at a rate of 

approximately 980,392 bbl per year (a range of approximately 560,224-1,400,560 bbl per year) (NRC, 

2003, p. 191). Hydrocarbons from natural seeps are considered to be the highest contributor of petroleum 

hydrocarbons to the marine environment (NRC, 2003, p. 33). Produced water (formation water) is the 

largest waste stream by volume from the oil and gas industry that enters Gulf waters. Produced water is 
4-32 Central Planning Area Supplemental EIS 

commonly treated to separate free oil and is either injected back into the reservoir or discharged 

overboard according to NPDES permit limits. The NRC has estimated the quantity of oil in produced 

water entering the Gulf per year to be 473,000 bbl (NRC, 2003, p. 200, Table D-8). These numbers were 

generated from converting the units reported in the noted reference and do not imply any level of 

significance. The numbers in this paragraph were generated from converting the units reported in the 

noted reference and do not imply any level of significance. 

Since the marine environment is a dynamic system, sediment quality and water quality can affect 

each other. For example, a contaminant may react with the mineral particles in the sediment and be 

removed from the water column (e.g., adsorption). Thus, under appropriate conditions, sediments can 

serve as sinks for contaminants such as metals, nutrients, or organic compounds. However, if sediments 

are (re)suspended (e.g., due to dredging or a storm event), the resuspension can lead to a temporary redox 

flux, including a localized and temporal release of any formally sorbed metals as well as nutrient 

recycling (Caetano et al., 2003; Fanning et al., 1982). However, resuspension events are less likely in 

deepwater environments. Deepwater sediments, with the exception of barium concentrations in the 

vicinity of previous drilling, do not appear to contain elevated levels of metal contaminants (USDOI, 

MMS, 1997 and 2000). The western Gulf has lower levels of total organic carbon and hydrocarbons in 

sediment, particularly those from terrestrial sources, than the central Gulf (Gallaway and Kennicutt, 

1988). Reported total hydrocarbons, including biogenic (e.g., from biological sources) hydrocarbons, in 

sediments collected from the Gulf slope range from 5 to 86 nanograms/gram (Kennicutt et al., 1987). 

Hydrocarbons in sediments have been determined to influence biological communities of the Gulf slope, 

even when present in trace amounts (Gallaway and Kennicutt, 1988). 

A 3-year, environmental baseline study conducted from 1974 to 1977 in the eastern GOM resulted in 

an overview of the Mississippi, Alabama, and Florida (MAFLA) OCS environment to 200 m (656 ft) 

(SUSIO, 1977; Dames & Moore, Inc., 1979). Analysis of water, sediments, and biota for hydrocarbons 

indicated that the MAFLA area is relatively pristine, with some influence of anthropogenic and 

petrogenic hydrocarbons from river sources. Analysis of trace metal contamination for the trace metals 

analyzed (barium, cadmium, chromium, copper, iron, lead, nickel, vanadium, and zinc) also indicated no 

contamination. A decade later, the continental shelf off Mississippi and Alabama was revisited (Brooks, 

1991). Bottom sediments were analyzed for high-molecular-weight hydrocarbons and heavy metals. 

High-molecular-weight hydrocarbons can come from natural petroleum seeps at the seafloor or recent 

biological production as well as input from anthropogenic sources. In the case of the MississippiAlabama shelf, the source of petroleum hydrocarbons and terrestrial plant material is the Mississippi 

River. Higher levels of hydrocarbons were observed in the late spring, which coincides with increased 

river influx. The sediments, however, are washed away later in the year, as evidenced by low 

hydrocarbon values in winter months. Contamination from trace metals was not observed (Brooks, 

1991). 

Limited information is available on water quality in deep waters. Water at depths >1,400 m (4,593 ft) 

is relatively homogeneous with respect to temperature, salinity, and oxygen (Nowlin, 1972; Pequegnat, 

1983; Gallaway et al., 1988; Jochens et al., 2005). Limited analyses of trace metals and hydrocarbons for 

the water column and sediments exist (Trefry, 1981; Gallaway et al., 1988). Continental Shelf 

Associates, Inc. (CSA) completed an Agency-funded field study of four drilling sites located in water 

depths of 1,033-1,125 m (3,389-3,691 ft) (CSA, 2006a). The sampling design called for before and after 

exploratory or development drilling and captured the drilling-related changes that occur in sediments and 

sediment pore water. At the Viosca Knoll Block 916 site, the closest drilling activity had occurred 1.4 mi 

(2.3 km) north-northwest and 2 years prior to the study; no drilling had ever been performed at the Viosca 

Knoll Block 916 site. The site was located at a water depth of 1,125 m (3,691 ft) and 70 mi (120 km) 

from the mouth of the Mississippi River. At this relatively pristine site prior to drilling, the average 

sediment barium concentration was 870-1,090 micrograms/gram. The average sediment mercury and 

cadmium concentrations were 0.071 and 0.22-0.28 micrograms/gram, respectively. The range of total 

sediment PAH’s was 159-388 nanograms/gram before drilling. 

Despite more limited information on the water quality of deep water, it is clear that the condition of 

the offshore waters of the Gulf of Mexico was altered by the DWH event and resulting oil spill. It is 

currently impossible to estimate precisely the long-term impacts that the spill from the DWH event will 

have on offshore water quality. Since the DWH event and resulting spill occurred in offshore waters and 

was of considerable magnitude, many of considerations noted in the chapter above on coastal water 
Description of the Environment and Impact Analysis 4-33 

impacts also apply for offshore waters. Various monitoring efforts and environmental studies have 

already begun. At the time this Supplemental EIS was prepared, the following sources were used for 

general information concerning the DWH event: 

 BP website on the DWH event (http://www.bp.com/

sectiongenericarticle800.do?categoryId=9036575&contentId=7067541); 

 Restore the Gulf website on the DWH response (http://www.data.gov/

restorethegulf/); 

 USEPA website on response to the BP spill in the Gulf of Mexico (http://

www.epa.gov/bpspill/epa.html); 

 National Science Foundation website on rapid response grants to fund DWH research 

(http://nsf.gov/awardsearch/progSearch.do?SearchType=progSearch&page=2&

QueryText=&ProgOrganization=&ProgOfficer=&ProgEleCode=&Boolean

Element=false&ProgRefCode=5987&BooleanRef=false&ProgProgram=&Prog

FoaCode=&Restriction=2&Search=Search#results); 

 Sea Grant website on DWH oil-spill research and monitoring activities database 

(http://gulfseagrant.tamu.edu/oilspill/database.htm); and 

 Joint Analysis Group review of R/V Brooks McCall data to examine subsurface oil 

(http://www.noaa.gov/sciencemissions/PDFs/

JAG_Report_1_BrooksMcCall_Final_June20.pdf). 

More time is needed to fully assess the impacts of the DWH event. Although response efforts have 

decreased the fraction of oil remaining in Gulf waters and reduced the amount of oil contacting the 

coastline, significant amounts of oil remain (RestoreTheGulf.gov, 2010a). 

Offshore water quality would not only be impacted by the oil, gas, and their respective components 

but also to some degree from cleanup and mitigation efforts. Increased vessel traffic, hydromodification, 

and the addition of dispersants, methanol, and water-based drilling mud to the marine environment in an 

effort to contain, mitigate, or clean up the oil may also tax the environment to some degree. Fortunately, 

over time, natural processes can physically, chemically, and biologically degrade oil (NRC, 2003). The 

physical processes involved include evaporation, emulsification and dissolution; the primary chemical 

and biological degradation processes include photooxidation and biodegradation (i.e., microbial 

oxidation). 

The oil that entered the Gulf of Mexico from the DWH event is a South Louisiana sweet crude oil 

(i.e., it is low in sulfur) (USDOC, NOAA, 2010b). The oil is fairly high in alkanes (organic compounds 

containing only carbon and hydrogen and single bonds, sometimes called paraffin or aliphatic 

compounds) (USDOC, NOAA, 2010b). Because alkanes are simple hydrocarbons, these oils are likely to 

undergo biodegradation more easily (USDOC, NOAA, 2010b). Weathering of crude can occur within the 

first 24-48 hours with up to a 40 percent weight loss within 7 days (English, 2010). Also, this oil is less 

toxic than other crude oils in general because this oil is lower in PAH’s than many crude oils. 

The DWH event released natural gas into the water column in addition to oil. Methane is the primary 

component of natural gas (NaturalGas.org, 2010b). Limited research is available for the biogeochemistry 

of hydrocarbon gases in the marine environment (Patin, 1999, p. 233). Methane may stay in the marine 

environment for long periods of time (Patin, 1999, p. 237) as methane is highly soluble in sea water at the 

high pressures and cold temperatures found in deepwater environments (NRC, 2003, p. 108); however, 

methane diffusing through the water column would likely be oxidized in the aerobic zone and would 

rarely reach the air-water interface (Mechalas, 1974, p. 23). Unfortunately, little is known about methane 

toxicity in the marine environment, but there is concern as to how methane in the water column might 

affect fish (Chapter 4.1.1.16). 
4-34 Central Planning Area Supplemental EIS 

One tool that was used in response to the oil leaking into the Gulf of Mexico from the DWH event is 

dispersants. The purpose of chemical dispersants is to facilitate the movement of oil into the water 

column in order to encourage weathering and biological breakdown of the oil (i.e., biodegradation) (NRC, 

2005; Australian Maritime Safety Authority, 2010). The amounts of dispersant sprayed at the surface and 

injected at the wellhead are 1,072,514 gallons and 771,272 gallons, respectively (U.S. Dept. of Homeland 

Security, CG, 2010c). The fate of this dispersant remains under study. If the oil moves into the water 

column and is not on the surface of the water, it is less likely to reach sensitive shore areas (USEPA, 

2010h). In addition to dispersion being enhanced by artificial processes, oil my also be dispersed from 

natural processes. For example, microbial metabolism of crude oil results in the dispersion of oil (Bartha 

and Atlas, 1983). Dispersion has both positive and negative effects. The positive effect is that the oil, 

once dispersed, is more available to be degraded. The negative effect is that the oil, once dispersed, is 

more available to microorganisms, which temporarily increase the toxicity (Bartha and Atlas, 1983). 

Toxicity of dispersed oil in the environment would depend on many factors, including the effectiveness of 

the dispersion, temperature, salinity, the degree of weathering, type of dispersant, and the degree of light 

penetration in the water column (NRC, 2005). The toxicity of dispersed oil is primarily due to the toxic 

components of the oil itself (Australian Maritime Safety Authority, 2010). 

Corexit 9500 and 9527 have been used in the DWH event response (USEPA, 2010h). The 

components of these dispersants are identical, with the exception of the base solvent; Corexit 9527 has an 

organic solvent as a base (McDonald et al., 1984; USEPA, 2010h). Dispersants used in the 1960’s were 

quite toxic, but more recently developed dispersants such as Corexit are considerably less toxic (Doe and 

Wells, 1978; Leahy and Colwell, 1990). Lindstrom and Braddock (2002) found that environmental use of 

Corexit 9500 could result in either increases or decreases in the toxicity of residual oil through selective 

microbial mineralization of hydrocarbons. In fact, reviews of studies have found that the general 

effectiveness of dispersants in enhancing biodegradation of crude oil and individual hydrocarbons is 

highly variable and depends on several factors, including the chemical formulation of the dispersant, its 

concentration, and the dispersant/oil application ratio (Boehm, 1983). However, there was evidence that 

the dispersants worked in the case of the DWH event (USDOC, NOAA, 2010a; USEPA, 2010h). Corexit 

9527 has been shown to greatly increase volatile liquid hydrocarbons’ incorporation into water as well as 

to accelerate the process in experiments compared with if no dispersant was used (McDonald et al., 

1984). In fact, dispersants used during the DWH event has been noted to reduce the volatile organic 

compounds, which can be a workplace issue for response workers on ships near the site (White House 

Press Briefing, 2010). Since the amount of dispersants used in the DWH event is unprecedented and 

since this is the first time dispersants have been applied in deep waters, continual monitoring and 

evaluation of their use is imperative (White House Press Briefing, 2010). 

As a result of the use of subsea dispersants, clouds or plumes of dispersed oil may occur near the 

blowout site in offshore waters. Reports thus far from the DWH event found such plumes and have 

shown that the concentrations of these clouds drop to undetectable levels within a few miles (USDOC, 

NOAA, 2010b). Dissolved oxygen levels are a concern with any release of a carbon source, such as oil 

and natural gas, and became a particular concern during the DWH event since dispersants were used in 

deep waters for the first time. Thus, USEPA required monitoring protocols in order to use subsea 

dispersants (USDOC, NOAA, 2010c). In areas where plumes of dispersed oil were previously found, 

dissolved oxygen levels decreased by about 20 percent from long-term average values in the GOM; 

however, scientists reported that these levels have stabilized and are not low enough to be considered 

hypoxic (USDOC, NOAA, 2010d). The drop in oxygen, which has not continued over time, has been 

attributed to microbial degradation of the oil. Initially released studies indicate that bacteria are degrading 

hydrocarbons from both gas and oil, but the degradation rates reported in the studies varied considerably 

(Camilli et al., 2010; Hazen et al., 2010; Valentine et al., 2010). Over time, as the oil continues to be 

degraded and diffuses, hypoxia becomes less of a concern. In fact, the 2010 hypoxic zone could not be 

linked to the DWH event in either a positive or a negative manner (LUMCON, 2010a). 

During the DWH event, one of the earlier attempts to stop the oil from leaking from the well was a 

procedure called a “top kill” (RestoreTheGulf.gov, 2010b). The top kill involved using water-based 

drilling muds, which are heavy due to the mineral component barite, in order to stop flow from the well. 

This procedure was not successful, but during the procedure, 29,712 bbl of water-based mud were used 

(Boland, personal communication, 2010). Much of this mud ended up on the seafloor. The primary 

general components of water-based mud (also referred to as water-based drilling fluids) are fresh or 
Description of the Environment and Impact Analysis 4-35 

saltwater, barite, clay, caustic soda, lignite, lignosulfonates, and water soluble polymers (USDOI, 

BOEMRE, 2010h). Water-based drilling mud may be discharged to the ocean under normal operations, 

but those discharges are regulated by USEPA (USDOI, BOEMRE, 2010h). The BOEMRE research has 

shown that drilling mud discharges do not move very far, even when discharged at the surface (CSA, 

2006a). Since the muds were discharged in deep water, sediments in the area are likely to be affected. 

4.1.1.2.2.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine impacts on offshore water quality can be found in Chapter 

4.2.1.1.2.2 of the Multisale EIS. Additional information for the 181 South Area and any new information 

since the publication of the Multisale EIS is presented in Chapter 4.1.2.2.2 of the 2009-2012 

Supplemental EIS. The following is a summary of the information incorporated from the Multisale EIS 

and the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

Proposed Action Analysis 

The routine activities associated with the CPA proposed action that would impact water quality 

include the following: 

 discharges during drilling of exploration and development wells; 

 structure installation and removal; 

 discharges during production; 

 installation of pipelines; 

 workovers of wells, 

 maintenance dredging of existing navigational canals; 

 service vessel discharges; and 

 nonpoint-source runoff. 

The scenario information related to the CPA proposed action is presented in Table 3-2.

The USEPA regulates discharges associated with offshore oil and gas exploration, development, and 

production activities on the OCS under the Clean Water Act’s NPDES program. Regulated wastes 

include drilling fluids, drill cuttings, deck drainage, produced water, produced sand, well treatment fluids, 

well completion fluids, well workover fluids, sanitary wastes, domestic wastes, and miscellaneous wastes 

(USEPA, 2009a). The USEPA’s NPDES general permit for Region 6 (GMG290000, which authorizes 

discharges to surface water during drilling and production) was reissued and went into effect on 

October 1, 2007 (USEPA, 2007c). This permit covers a large portion of the CPA, as USEPA’s regional 

boundaries do not coincide with BOEMRE’s planning area boundaries. The permit will expire on 

September 30, 2012. The USEPA Region 4 issues individual and general permits covering facilities that 

discharge in water depths seaward of 200 m (656 ft) occurring offshore the coasts of Alabama and 

Florida. The western boundary of the coverage area is demarcated by Mobile and Viosca Knoll lease 

blocks located seaward of the boundary of the territorial seas from the coasts of Mississippi and Alabama. 

The USEPA Region 4’s NPDES general permit (GMG460000) for offshore oil and gas activities in 

Federal waters in the eastern portion of the OCS of the Gulf of Mexico (off of the coast of Mississippi 

and eastward) expired on December 31, 2009 (USEPA, 2009b). The USEPA Region 4 issued the new 

permit, GEG460000, on March 15, 2010, and it expires on March 21, 2015 (USEPA, 2010j). The 

changes in the new permit include the following: (1) the permit number; (2) requirements for cooling 

water intake structures (similar requirements are already in effect in Region 6); (3) best management 

practices plan requirements to address discharges of debris from blasting and painting activities; (4) 
4-36 Central Planning Area Supplemental EIS 

clarifications of the testing procedures for determining the degradation of nonaqueous base fluids in a 

marine, closed-bottle, biodegradation test system; (5) clarifications for the reporting requirements for ratio 

values used to report compliance with the sediment toxicity and biodegradation tests; and (6) the 

requirement to perform a seabed survey was deleted since the industry completed this study during the 

term of the previous permit (USEPA, 2009b). Thus, the permit is similar to the previous permit with the 

exception of the clarifications and more stringent requirements noted above. 

The bulk of waste materials produced by offshore oil and gas activities are formation water (produced 

water) and drilling muds and cuttings. All of these waste streams are regulated by USEPA through 

NPDES permits. Characteristics of drilling muds and cuttings, the impacts of discharge, and regulatory 

controls are discussed in great detail in Chapter 4.1.1.4.1 of the Multisale EIS. The CPA proposed action 

is projected to result in the drilling of a total of 65-121 exploratory and delineation wells and 338-576 

development and production wells (Table 3-2). Muds are the weighted fluids used to lubricate the drill 

bit, and cuttings are the ground rock displaced from the well. Drilling muds generally consist of clays, 

barite, lignite, caustic soda (sodium hydroxide), lignosulfonates, and a base fluid such as freshwater, 

saltwater, mineral oil, diesel oil, or a synthetic oil (USDOI, BOEMRE, 2010h; NRC, 1983; USEPA, 

2009a); however, the exact formulas are complex and vary. Three general types of drilling muds have 

been used during drilling operations: water-based drilling muds (WBM or WBF), oil-based drilling muds 

(OBM or OBF), and synthetic-based drilling muds (SBM or SBF). The WBM and WBM-wetted cuttings 

may be discharged. The OBM’s are used to improve drilling through difficult geologic formations. The 

base mud for OBM is typically diesel or mineral oil. Because these oils often contain toxic materials such 

as PAH’s, the discharge of OBM or cuttings wetted with OBM is prohibited. The SBM’s were developed 

as an alternative to OBM. The base fluid is a synthetic material, typically an olefin or ester, free of toxic 

PAH’s. Discharge of SBM is prohibited and, due to cost, is generally recycled (USEPA, 2009a). 

However, SBM-wetted cuttings may be discharged after the majority of the SBM has been removed. 

Water-based muds and cuttings that are discharged increase turbidity in the water column and alter the 

sediment characteristics in the area where they settle (Neff, 2005). The SBF-wetted cuttings do not 

disperse as readily in water and descend in clumps to the seafloor (Neff et al., 2000). The SBF on the 

wetted cuttings gradually breaks down and may deplete the oxygen level at the sediment water interface 

as it degrades (Neff et al., 2000). 

During production, produced water is brought up from the hydrocarbon-bearing strata along with the 

oil and gas that is generated. Characteristics of produced water, the impacts of discharge, and regulatory 

controls are discussed in greater detail in Chapter 4.1.1.4.2 of the Multisale EIS. The scenario for the 

CPA projects that 338-576 development and production wells would be drilled, of which 149-263 are 

expected to be producing oil wells and 144-237 are expected to be producing gas wells (Table 3-2). 

Greater volumes of produced water are associated with oil rather than with gas production; in fact, a 

report on produced-water volumes in the United States noted that 87 percent of produced water came 

from oil production (Clark and Veil, 2009). Produced water may contain dissolved solids in higher 

concentrations than Gulf waters, metals, hydrocarbons, and naturally-occurring radionuclides (Veil et al., 

2004). Produced water may contain residuals from the treatment completion or workover compounds 

used, as well as additives used in the oil/water separation process (Veil et al., 2004). Produced water is 

treated to meet NPDES requirements before it is discharged. 

Additional chemical products are used to “workover” or treat a well. These wastes are regulated by 

USEPA through the NPDES program as noted above. Characteristics of workover treatment and 

production chemicals, the impacts of discharge, and regulatory controls are discussed in greater detail in 

Chapter 4.1.1.4.3 of the Multisale EIS. Some examples of chemicals that might be used to “workover” or 

treat a well include, but are not limited to, brines used to protect a well, acids used to increase well 

production, and miscellaneous products used to separate water from oil, to prevent bacterial growth, or to 

eliminate scale formation or foaming (Boehm et al., 2001). 

During structure installation and removal, impacts from anchoring, mooring, pipeline and flowline 

emplacement, and the placement of subsea production structures may occur. The CPA proposed action is 

projected to result in the installation of 32-44 structures and the removal of 30-42 structures (Table 3-2). 

The CPA proposed action is also projected to result in the installation of 130-2,075 km (~81-1,289 mi) of 

pipeline. Additional information on bottom-area disturbance is available in Chapter 4.1.1.3.2.1 of the 

Multisale EIS. More specifically, a description of the pipeline installation is provided in Chapter 

4.1.1.8.1 of the Multisale EIS. In the report titled Brief Overview of Gulf of Mexico OCS Oil and Gas 
Description of the Environment and Impact Analysis 4-37 

Pipelines: Installation, Potential Impacts, and Mitigation Measures (Cranswick, 2001), the report states 

the following: 

According to MMS regulations (30 CFR 250.1003(a)(1)), pipelines with diameters ≥8 5/8 

inches that are installed in water depths <200 ft are to be buried to a depth of at least 3 ft 

below the mudline. The regulations also provide for the burial of any pipeline, regardless 

of size, if the MMS determines that the pipeline may constitute a hazard to other uses of 

the OCS; in the GOM, the MMS has determined that all pipelines installed in water 

depths <200 ft must be buried. The purpose of these requirements is to reduce the 

movement of pipelines by high currents and storms, to protect the pipeline from the 

external damage that could result from anchors and fishing gear, to reduce the risk of 

fishing gear becoming snagged, and to minimize interference with the operations of other 

users of the OCS. For lines 8 5/8 inches and smaller, a waiver of the burial requirement 

may be requested and may be approved if the line is to be laid in an area where the 

character of the seafloor will allow the weight of the line to cause it to sink into the 

sediments (self-burial). For water depths ≤200 ft, any length of pipeline that crosses a 

fairway or anchorage in Federal waters must be buried to a minimum depth of 10 ft 

below mudline across a fairway and a minimum depth of 16 ft below mudline across an 

anchorage area. Some operators voluntarily bury these pipelines deeper than the 

minimum. 

Any disturbance of the seafloor would increase turbidity in the surrounding water, but the increased 

turbidity should be temporary and restricted to the area near the disturbance. 

Service-vessel discharges include bilge and ballast water and sanitary and domestic waste. The CPA 

proposed action is projected to result in 137,000-220,000 service-vessel round trips (Table 3-2). A 

marine sanitation device is required to treat sanitary waste generated on the service vessel so that 

surrounding water would not be impacted by possible bacteria or viruses in the waste (40 CFR 140 and 

33 CFR 159). The discharge of treated sanitary waste would still contribute a small amount of nutrients 

to the water. A description of service-vessel operational wastes is provided in Chapter 4.1.1.4.8 of the 

Multisale EIS. Oil may contaminate bilge and, although less likely, ballast water. The regulations for the 

control of oil discharges are in 33 CFR 151.10. When more than 12 nmi (14 mi; 22 km) from the nearest 

land, bilge and ballast water may generally be discharged with an oil content of less than 15 ppm. While 

within 12 nmi (14 mi; 22 km), the oil content of the effluent must not exceed 15 ppm. The discharges 

would affect the water quality locally. However, regulations regarding discharges from vessels are 

becoming increasingly stringent. The USCG Ballast Water Management Program became mandatory for 

some vessels in 2004 (33 CFR 151 Subparts C and D) (U.S. Dept. of Homeland Security, CG, 2010b). 

The program was designed to prevent the introduction on nonindigenous (invasive) species, which would 

affect local water quality. Furthermore, USCG published the Ballast Water Discharge Standard Notice of 

Proposed Rulemaking in the Federal Register on August 28, 2009. Additionally, the final Vessel General 

Permit, issued by USEPA, became effective on December 19, 2008. This permit is in addition to already 

existing NPDES permit requirements and now increases the NPDES regulations so that discharges 

incidental to the normal operation of vessels operating as a means of transportation are no longer 

excluded unless exempted from NPDES permitting by Congressional legislation (USEPA, 2008b). 

Summary and Conclusion 

During exploratory activities, the primary impacting sources to offshore water quality are discharges 

of drilling fluids and cuttings. During platform installation and removal activities, the primary impacting 

sources to water quality are sediment disturbance and temporarily increased turbidity. Impacting 

discharges during production activities are produced water and supply-vessel discharges. Regulations are 

in place to limit the levels of contaminants in these discharges. Pipeline installation can also affect water 

quality by sediment disturbance and increased turbidity. Service-vessel discharges might include water 

with oil concentration of approximately 15 ppm as established by regulatory standards. Any disturbance 

of the seafloor would increase turbidity in the surrounding water, but the increased turbidity should be 

temporary and restricted to the area near the disturbance. There are multiple Federal regulations and 
4-38 Central Planning Area Supplemental EIS 

permit requirements that would decrease the magnitude of these activities. Impacts to offshore waters 

from routine activities associated with the CPA proposed action should be minimal as long as regulatory 

requirements are followed. 

4.1.1.2.2.3. Impacts of Accidental Events 

A detailed description of accidental events on offshore water quality can be found in Chapter 4.4.2.2 

of the Multisale EIS. Additional information for the 181 South Area and any new information since the 

publication of the Multisale EIS is presented in Chapter 4.1.2.2.3 of the 2009-2012 Supplemental EIS. 

The following is a summary of the information incorporated from the Multisale EIS and the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

Accidental events associated with the CPA proposed action that could impact offshore water quality 

include spills of oil and refined hydrocarbons, releases of natural gas, spills of chemicals or drilling fluids, 

and loss of well control, collisions, or other malfunctions that would result in such spills. Chapter 3.2 of 

this document discusses the accidental events that could result from the impact-producing factors and 

scenario, with particular attention given to the risk of oil spills, response to such oil spills, loss of well 

control, pipeline failures, vessel collisions, and chemical and drilling fluid spills. A brief summary is 

presented here. The impacts of rare, catastrophic spills are discussed in Appendix B. 

Proposed Action Analysis 

Oil Spills and Natural Gas and Condensate Releases 

Water quality is altered and degraded by oil spills through the increase of petroleum hydrocarbons 

and their various transformation/degradation products in the water. The extent of impact from a spill 

depends on the behavior and fate of oil in the water column (e.g., the movement of oil and the rate and 

nature of weathering), which, in turn, depends on oceanographic and meteorological conditions at the 

time (Appendix A-2 and A-3 of the Multisale EIS). Crude oils are not a single chemical, but instead are 

complex mixtures with varied compositions. The various fractions within the crude behave differently in 

water. Thus, the behavior of the oil and the risk that the oil poses to natural resources depends on the 

composition of the specific oil encountered (Michel, 1992). Generally, oils can be divided into three 

groups of compounds: (1) light-weight; (2) medium-weight; and (3) heavy-weight components. Chapter 

3.2.1 further characterizes the components of oil and discusses oil spills. Chapter 4.3.1 of the Multisale 

EIS also discusses oil spills in further detail, with Chapter 4.3.1.4 of the Multisale EIS describing the 

characteristics of OCS oil. Generally, the lighter ends of the oil are more water soluble and would 

contribute to acute toxicity. As the spill weathers, the aromatic components at the water’s surface are 

more likely to exit the water. The heavier fractions are less water soluble and would partition to organic 

matter. This fraction is more likely to persist in sediments and would contribute to longer-term impacts. 

In addition to oil, natural gas may also be explored for or produced in the GOM. Wells and sidetracks 

may produce a mixture of both oil and natural gas. Condensate is a liquid hydrocarbon phase that 

generally occurs in association with natural gas. The quality and quantity of components in natural gas 

vary widely by the field, reservoir, or location from which the natural gas is produced. Although there is 

not a “typical” makeup of natural gas, it is primarily composed of methane (NaturalGas.org, 2010b). 

Thus, if natural gas were to leak into the environment, methane may be released to the environment. 

Methane is a carbon source, such as oil, and its introduction into the marine environment could result in 

lowering dissolved oxygen levels due to increased microbial degradation. Unfortunately, little is known 

about the toxicity of natural gas and its components in the marine environment, but there is concern as to 

how methane in the water column might affect fish (Chapter 4.1.1.13). 

Hydrogen sulfide (H2S), a toxic gas that is associated with certain formations in the GOM, could be 

released with natural gas. Depending on the concentration and volume, an H2S release at the seafloor 

could negatively impact the water quality as the gas rises to the surface (Patin, 1999). 

The National Academy of Sciences (NRC, 2003), Patin (1999), and Boesch and Rabalais (1987) have 

reviewed the fate and effects of spilled oil and, to a lesser degree, natural gas releases. Chapters 4.3.1.5 

and 4.3.1.6 of the Multisale EIS presents the risk of offshore spills associated with the proposed action, 

and Chapters 3.2.1.1 and 3.2.1.2 of this Supplemental EIS supplement and update that information. Oil 

spills at the water surface may result from a platform accident. Subsurface spills are more likely to occur 
Description of the Environment and Impact Analysis 4-39 

from pipeline failure or a loss of well control. As noted above, the behavior of a spill depends on many 

things, including the characteristics of the oil being spilled as well as oceanographic and meteorological 

conditions. An experiment in the North Sea indicated that the majority of oil released during a deepwater 

blowout would quickly rise to the surface and form a slick (Johansen et al., 2001). In such a case, impacts 

from a deepwater oil spill would occur at the surface where the oil is likely to be mixed into the water and 

dispersed by wind and waves. The oil would undergo natural physical, chemical, and biological 

degradation processes including weathering. However, data and observations from the DWH event 

challenged the previously prevailing thought that most oil from a deepwater blowout would quickly rise 

to the surface. While analyses are in their preliminary stages, it appears that measurable amounts of 

hydrocarbons (dispersed or otherwise) are being detected in the water column as subsurface plumes 

(Chapter 4.1.1.2.2.1) and perhaps on the seafloor in the vicinity of the release. After the Ixtoc blowout in 

1979, which was located 50 mi (80 km) offshore in the Bay of Campeche, Mexico, some subsurface oil 

also was observed dispersed within the water column (Boehm and Fiest, 1982); however, the scientific 

investigations were limited (Reible, 2010). The water quality of offshore waters would be affected by the 

dissolved components and oil droplets that are small enough that they do not rise to the surface or are 

mixed down by surface turbulence. In the case of subsurface oil plumes, it is important to remember that 

these plumes would be affected by subsurface currents and could be diluted over time. Even in the 

subsurface, oil would undergo natural physical, chemical, and biological degradation processes including 

weathering. 

In the case of an accidental event, it is likely that response efforts would reduce the amount of oil. 

Chapter 3.2.1.5 provides a further discussion of oil-spill-response considerations. Offshore water quality 

would not only be impacted by the oil, gas, and their respective components but also to some degree from 

cleanup and mitigation efforts. Increased vessel traffic, top kill attempts involving the use of drilling 

muds, and the addition of dispersants and methanol to the marine environment in an effort to contain, 

mitigate, or clean up the oil may also tax the environment to some degree. 

Top kills use drilling muds, which are heavy due to the mineral component barite, in order to stop 

flow from a well. Top kill methods would likely involve the use of water-based drilling muds, which 

may be discharged to the ocean under normal operations as regulated by USEPA (USDOI, BOEMRE, 

2010h). Depending on the success of the procedure, a portion of the mud could end up on the seafloor 

since drilling mud discharges do not move far from where they are released (CSA, 2006a). See 

“Accidental Release of Drilling Fluids” below for more information. 

One standard tool used in response to spilled oil on water is dispersants. The purpose of chemical 

dispersants is to facilitate the movement of oil into the water column in order to encourage weathering 

and biological breakdown of the oil (i.e., biodegradation) (NRC, 2005; Australian Maritime Safety 

Authority, 2010). If the oil moves into the water column and is not on the surface of the water, it is less 

likely to reach sensitive shore areas (USEPA, 2010h). The toxicity of dispersed oil in the environment 

would depend on many factors, including the effectiveness of the dispersion, temperature, salinity, the 

degree of weathering, type of dispersant, and the degree of light penetration in the water column (NRC, 

2005). The toxicity of dispersed oil is primarily due to the toxic components of the oil itself (Australian 

Maritime Safety Authority, 2010). 

In addition to response efforts, the natural environment can attenuate some oil. The Gulf of Mexico 

has numerous natural hydrocarbon seeps as discussed in Chapters 3.1.2.2 and 4.1.3.4.1 of the Multisale 

EIS. Thus, the marine environment can be considered adapted to handling small amounts of oil released 

over time. Furthermore, over time, natural processes can physically, chemically, and biologically degrade 

oil (NRC, 2003). The physical processes involved include evaporation, emulsification, and dissolution; 

the primary chemical and biological degradation processes include photooxidation and biodegradation 

(i.e., microbial oxidation). Most of the oil spills that may occur as a result of the proposed action are 

expected to be 1 bbl (Table 3-5). 

Chemical Spills 

A study of chemical spills from OCS activities determined that accidental releases of zinc bromide 

and ammonium chloride could potentially impact the marine environment (Boehm et al., 2001). Both of 

these chemicals are used for well treatment or completion and are not in continuous use; thus, the risk of a 

spill is small. Most other chemicals are either relatively nontoxic or used in such small quantities that a 
4-40 Central Planning Area Supplemental EIS 

spill would not result in measurable impacts. Zinc bromide is of particular concern because of the toxic 

nature of zinc. Close to the release point of an ammonium chloride spill, the ammonia concentrations 

could exceed toxic levels. 

Accidental Releases of Drilling Fluids 

Drilling muds or fluids are the weighted fluids used to lubricate the drill bit. Drilling muds generally 

consist of clays, barite, lignite, caustic soda (sodium hydroxide), lignosulfonates, and a base fluid such as 

freshwater, saltwater, mineral oil, diesel oil, or a synthetic oil (USDOI, BOEMRE, 2010h; NRC, 1983; 

USEPA, 2009a); however, the exact formulas are complex and vary. The impacts of discharge and 

regulatory controls of drilling muds are discussed in great detail in Chapter 4.1.1.4.1 of the Multisale EIS. 

Three general types of drilling muds have been used during drilling operations: water-based drilling 

muds (WBM or WBF); oil-based drilling muds (OBM or OBF); and synthetic-based drilling muds (SBM 

or SBF). Accidental releases of drilling fluids would have similar effects as discharges. In general, 

Continental Shelf Associates, Inc.’s research has shown that drilling mud discharges do not move very far 

even when discharged at the surface (CSA, 2006a); therefore, accidental releases of drilling muds are not 

expected to move very far either. The WBM’s may be discharged, but those discharges are regulated by 

the USEPA through NPDES permits. The WBM’s that are discharged increase turbidity in the water 

column and alter the sediment characteristics in the area where they settle (Neff, 2005). The OBM’s are 

used to improve drilling through difficult geologic formations. The base mud for OBM is typically diesel 

or mineral oil. Because these oils often contain toxic materials such as PAH’s, the discharge of OBM or 

cuttings wetted with OBM is prohibited. Thus, an accidental release of OBM’s could decrease water 

quality locally. The SBM’s were developed as an alternative to OBM and, thus, the use of OBM’s has 

been decreasing. The base fluid is a synthetic material, typically an olefin or ester, free of toxic PAH’s. 

Discharge of SBM itself is prohibited and, due to cost, is generally recycled (USEPA, 2009a). However, 

SBM-wetted cuttings may be discharged after the majority of the SBM has been removed. The SBFwetted cuttings do not disperse as readily in water and descend in clumps to the seafloor (Neff et al., 

2000). The SBF on the wetted cuttings gradually breaks down and may deplete the oxygen level at the 

sediment water interface as it degrades (Neff et al., 2000). An accidental release of SBF is expected to 

behave similarly with the SBF sinking to the seafloor adjacent to the release site and resulting in local 

anoxic conditions. 

Pipeline Failures 

A pipeline failure would result in the release of crude oil, condensate, or natural gas, the impacts of 

which are discussed above. Pipeline failures are discussed in more detail in Chapter 3.2.3. 

Fuel Oil Spills from Collisions 

A collision may result in the spillage of crude oil, refined products such as diesel, or chemicals. 

Crude oil and chemicals are discussed in the preceding paragraphs. Diesel is the type of refined 

hydrocarbon spilled most frequently as the result of a collision. Minimal impacts result from a spill since 

diesel is light and will evaporate and biodegrade within a few days (USDOC, NOAA, 2006). A collision 

could result in the release of up to the entire contents of the fuel tanks. Since collisions occur infrequently 

(USDOI, BOEMRE, 2010i), the potential impacts to offshore water quality are not expected to be 

significant. 

Loss of Well Control 

A loss of well control is the uncontrolled flow of a reservoir fluid that may result in the release of gas, 

condensate, oil, drilling fluids, sand, or water. The impacts of the release of gas, condensate, oil, and 

drilling fluids are discussed above. A loss of well control includes events with no surface expression or 

impact on water quality and events with a release of oil or drilling fluids. A loss of well control event 

may also result in localized suspension of sediments, thus affecting water quality temporarily. Loss of 

well control is a broad term that includes very minor well-control incidents up to the most serious wellcontrol incidents (Appendix B). Historically, most losses of well control have occurred during 
Description of the Environment and Impact Analysis 4-41 

development drilling operations, but losses of well control can happen during exploratory drilling, 

production, well completions, or workover operations. Blowouts are a loss of well subset of more serious 

incidents, with a greater risk of oil spill or human injury. It is through the loss of well control that the 

volume and duration of a catastrophic oil spill could occur. Although there is an extremely low 

probability of a catastrophic spill event, the impacts of such an event on water quality are addressed in 

Appendix B. Overall, since loss of well control events and blowouts are rare events (USDOI, BOEMRE, 

2010i) and of short duration, potential impacts to offshore water quality are not expected to be significant 

except in the rare case of a catastrophic event. 

Summary and Conclusion 

Accidental events associated with the CPA proposed action that could impact offshore water quality 

include spills of oil and refined hydrocarbons, releases of natural gas and condensate, spills of chemicals 

or drilling fluids, and loss of well control, pipeline failures, collisions, or other malfunctions that would 

result in such spills. Spills from collisions are not expected to be significant because collisions occur 

infrequently. Overall, loss of well control events and blowouts are rare events and of short duration, so 

potential impacts to offshore water quality are not expected to be significant except in the rare case of a 

catastrophic event. Although response efforts may decrease the amount of oil in the environment, the 

response efforts may also impact the environment. Natural physical, chemical, and biological processes 

would decrease the amount of spilled oil over time through dilution, weathering, and degradation of the 

oil (NRC, 2003). Chemicals used in the oil and gas industry are not a significant risk for a spill because 

they are either nontoxic, used in minor quantities, or are only used on a noncontinuous basis. Although 

there is the potential for accidental events, the CPA proposed action would not significantly change the 

water quality of the Gulf of Mexico over a large spatial or temporal scale. 

4.1.1.2.2.4. Cumulative Impacts 

A detailed description of cumulative impacts upon water quality can be found in Chapter 4.5.2 of the 

Multisale EIS and in Chapter 4.1.2.1.4 of the 2009-2012 Supplemental EIS. 

Activities in the cumulative scenario that could impact offshore water quality generally include the 

broad categories of the proposed action and the OCS Program, the activities of other Federal agencies 

(including the military), natural events or processes, State oil and gas activity, and activities related to the 

direct or indirect use of land and waterways by the human population (e.g., urbanization, agricultural 

practices, coastal industry, and municipal wastes). Although some of these impacts are likely to affect 

coastal areas to a greater degree, coastal pollutants that are transported away from shore would still affect 

offshore environments. Many of these categories noted above would have some of the same specific 

impacts (e.g., vessel traffic would occur for all of these categories listed above except natural processes). 

Sediment disturbance and turbidity may result from pipeline installation, installation and removal of 

platforms, discharges of muds and cuttings from drilling operations, disposal of dredge materials, sand 

borrowing, sediment deposition from rivers, and hurricanes. Turbidity is also influenced by the season. 

In offshore waters, these impacts may be the result of Gulfwide, OCS-related activities by other Federal 

agencies, including the military, and natural processes. State oil and gas activities may have some effect 

if they take place near offshore waters. Dredging projects related to restoration or flood prevention 

measures may be directed by the Federal Government for the benefit of growing coastal populations. 

These impacts generally degrade water quality locally and are not expected to last for long time periods. 

Furthermore, discharges from drilling platforms are regulated by USEPA through the NPDES permit 

process; thus, effects from these discharges should be limited. 

Vessel discharges can degrade water quality. Vessels may be service vessels supporting the proposed 

action, OCS-related activities, or State oil and gas activities. However, the vessels may also be vessels 

used for shipping, fishing, military activities, or recreational boating. State oil and gas activities, fishing, 

and recreational boating would have fewer effects on offshore waters except for larger fishing operations 

and cruise lines, as smaller vessels tend to remain near shore. Fortunately, for many types of vessels, 

most discharges are treated or otherwise managed prior to release through regulations administered by 

USCG and/or USEPA, and many regulations are becoming more stringent. For example, the USCG 

Ballast Water Management Program, which was designed to prevent the introduction of invasive species, 

became mandatory for some vessels in 2004 (33 CFR 151 Subparts C and D) (U.S. Dept. of Homeland 
4-42 Central Planning Area Supplemental EIS 

Security, CG, 2010b). Furthermore, USCG published the Ballast Water Discharge Standard Notice of 

Proposed Rulemaking in the Federal Register on August 28, 2009. Additionally, the final Vessel General 

Permit, issued by USEPA, became effective on December 19, 2008. This permit is in addition to already 

existing NPDES permit requirements and now increases the NPDES regulations so that discharges 

incidental to the normal operation of vessels operating as a means of transportation are no longer 

excluded unless exempted from NPDES permitting by Congressional legislation (USEPA, 2008b). These 

regulations should minimize the cumulative impacts of vessel activities. 

Erosion and runoff from point and nonpoint sources degrade water quality. Nonpoint-source runoff 

from onshore support facilities could result from OCS-related activities as well as State oil and gas 

activities and other industries and coastal development. Although offshore waters would not be affected 

as strongly as coastal waters since contaminants would be more diluted by the time they reached offshore 

areas, in many cases this runoff would still contribute somewhat to the degradation of offshore waters. 

Urban runoff can include suspended solids, heavy metals and pesticides, oil and grease, and nutrients. 

Urban runoff increases with population growth, and the Gulf Coast region has experienced a 103 percent 

population growth since 1970 (USDOC, NOAA, 2008a). The National Research Council (2003, Table 

I-4, p. 237) estimated that, on average, approximately 26,324 bbl of oil per year entered Gulf waters from 

petrochemical and oil refinery industries in Louisiana and Texas. Chapter 4.1.3.4 of the Multisale EIS 

discussed the various sources of petroleum hydrocarbons that can enter the Gulf of Mexico in further 

detail. The natural emptying of rivers into the GOM as part of the water cycle may introduce chemical 

and physical factors that alter the condition of the natural water through both natural and anthropogenic 

sources, such as the addition of waterborne pollutants, or the addition of warmer water, into the GOM 

through waterbodies emptying into the GOM, runoff, groundwater discharge, or precipitation. The 

Mississippi River introduced approximately 3,680,938 bbl of oil and grease per year from land-based 

sources (NRC, 2003, Table I-9, p. 242) into the waters of the Gulf. Nutrients carried in waters of the 

Mississippi River contribute to seasonal formation of the hypoxic zone on the Louisiana-Texas shelf. 

Recently, USEPA has proposed the first set of nutrient standards; the first set of standards is for the State 

of Florida (USEPA, 2010i). The proposed new water quality standards would set a series of numeric 

nutrient (nitrogen and phosphorus) limitations for Florida’s lakes, rivers, steams, springs, and canals. The 

USEPA also regulates point-source discharges. Chapter 4.5.2.1 of the Multisale EIS summarizes the 

regulatory programs designed to protect the waters that enter the Gulf. If these and other water quality 

programs and regulations continue to be administered and enforced, it is not expected that additional oil 

and gas activities would adversely impact the overall water quality of the region. 

Offshore waters, especially deeper waters, are more directly affected by natural seeps since the 

natural seeps in the Gulf of Mexico are located in offshore waters. Natural seeps are the result of natural 

processes. Hydrocarbons enter the Gulf of Mexico through natural seeps in the Gulf of Mexico at a rate 

of approximately 980,392 bbl per year (a range of approximately 560,224-1,400,560 bbl per year) (NRC, 

2003, p. 191). Hydrocarbons from natural seeps are considered to be the highest contributor of petroleum 

hydrocarbons to the marine environment (NRC, 2003, p. 33). However, studies have shown that benthic 

communities are often acclimated to these seeps and may even utilize them to some degree (NRC, 2003, 

references therein and p. 33). 

Discharges from exploration and production activities can degrade water quality in offshore waters. 

The USEPA regulates discharges associated with offshore oil and gas exploration, development, and 

production activities on the OCS under the Clean Water Act’s NPDES program. Regulated wastes 

include drilling fluids, drill cuttings, deck drainage, produced water, produced sand, well treatment fluids, 

well completion fluids, well workover fluids, sanitary wastes, domestic wastes, and miscellaneous wastes 

(USEPA, 2009a). The bulk of waste materials produced by offshore oil and gas activities are produced 

water (formation water) and drilling muds and cuttings. Produced water is the largest waste stream by 

volume from the oil and gas industry that enters Gulf waters. The NRC has estimated the quantity of oil 

in produced water entering the Gulf per year to be 473,000 bbl (NRC, 2003, p. 200, Table D-8). The 

numbers in this paragraph were generated from converting the units reported in the noted reference and 

do not imply any level of significance. However, produced water is commonly treated to separate free oil 

and, as noted above, is a regulated discharge. Since discharges from drilling and production platforms are 

regulated by USEPA through the NPDES permit process, the effects from these discharges should be 

limited. 
Description of the Environment and Impact Analysis 4-43 

Since the marine environment is a dynamic system, sediment quality and water quality can affect 

each other. For example, a contaminant may react with the mineral particles in the sediment and be 

removed from the water column (e.g., adsorption). Thus, under appropriate conditions, sediments can 

serve as sinks for contaminants such as metals, nutrients, or organic compounds. However, if sediments 

are (re)suspended (e.g., due to a storm event), the resuspension can lead to a temporary redox flux, 

including a localized and temporal release of any formally sorbed metals as well as nutrient recycling 

(Caetano et al., 2003; Fanning et al., 1982). 

Accidental releases of oil, gas, or chemicals would degrade water quality during and after the spill 

until either the spill is cleaned up or natural processes degrade or disperse the spill. These accidental 

releases could be a result of the proposed action, ongoing OCS activity, State oil and gas activity, the 

transport of commodities to ports, and/or coastal industries. Actions taking place directly in offshore 

waters would generally have more significant impacts on offshore waters. The impacts of rare, 

catastrophic spills are discussed in Appendix B. The extent of impact from a spill depends on the 

behavior and fate of oil in the water column (e.g., the movement of oil and the rate and nature of 

weathering), which, in turn, depends on oceanographic and meteorological conditions at the time 

(Appendix A.2 and A.3 of the Multisale EIS). Chapter 4.5.2.1 of the Multisale EIS contains more 

information on accidental releases. A major hurricane can result in a greater number of spill events, with 

increased spill volume and decreases in oil-spill-response times. In the case of an accidental event, it is 

likely that response efforts would reduce the amount of oil. See Chapter 3.2.1.5 for further discussion of 

oil-spill-response considerations. Offshore water quality would not only be impacted by the oil, gas, and 

their respective components but also to some degree from cleanup and mitigation efforts. Increased 

vessel traffic and the addition of dispersants and methanol to the marine environment in an effort to 

contain, mitigate, or clean up the oil may also tax the environment to some degree. 

Summary and Conclusion 

Water quality in offshore waters would be impacted by sediment disturbance and suspension (i.e., 

turbidity), vessel discharges, erosion and runoff of nonpoint-source pollutants including river inflows, 

natural seeps, discharges from exploration and production activities, and accidental events. These 

impacts may be a result of the proposed action and the OCS Program, the activities of other Federal 

agencies (including the military), private vessels, and natural events or processes. To a lesser degree, 

these impacts may also be a result of State oil and gas activity or activities or related to the direct or 

indirect use of land and waterways by the human population (e.g., urbanization, agricultural practices, 

coastal industry, and municipal wastes). Routine activities that increase turbidity and discharges are 

temporary in nature and are regulated; therefore, these activities would not have a lasting adverse impact 

on water quality. In the case of a large-scale spill event, degradation processes would decrease the 

amount of spilled oil over time through natural processes that can physically, chemically, and biologically 

degrade oil (NRC, 2003). The impacts resulting from the CPA proposed action are a small addition to the 

cumulative impacts on the offshore waters of the Gulf. The incremental contribution of the routine 

activities and accidental discharges associated with the proposed action to the cumulative impacts on 

offshore water quality is not expected to be significant as long as all regulations are followed. 

4.1.1.3. Coastal Barrier Beaches and Associated Dunes 

The BOEMRE has reexamined the analysis for coastal barrier beaches and associated dunes presented 

in the Multisale EIS and the 2009-2012 Supplemental EIS (addition of 181 South Area), based on the 

additional information presented below and in consideration of the DWH event. No substantial new 

information was found that would alter the impact conclusion for coastal barrier beaches and associated 

dunes presented in the Multisale EIS and the 2009-2012 Supplemental EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. 

Routine activities associated with the CPA proposed action, such as increased vessel traffic, maintenance 

dredging of navigation canals, and pipeline installation, would cause negligible impacts and would not 

deleteriously affect coastal barrier beaches and associated dunes. Indirect impacts from routine activities 
4-44 Central Planning Area Supplemental EIS 

are negligible and indistinguishable from direct impacts of onshore activities. The potential impacts from 

accidental events, primarily oil spills, associated with the CPA proposed action are anticipated to be 

minimal. The incremental contribution of the proposed action to the cumulative impacts to coastal barrier 

beaches and associated dunes is expected to be small. 

4.1.1.3.1. Description of the Affected Environment 

A detailed description of coastal barrier beaches and associated dunes in the Gulf of Mexico can be 

found in Chapter 3.2.1.1 of the Multisale EIS. Additional information for the 181 South Area and any 

new information since the publication of the Multisale EIS is presented in Chapter 4.1.3.1.1 of the 2009-

2012 Supplemental EIS. The following information is a summary of the resource description 

incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

The coastal environments discussed here are those barrier beaches, wetlands, and submerged 

vegetation that might be impacted by activities resulting from the CPA proposed action. Geographically, 

the discussion covers coastal areas that range from the Texas/Louisiana border through Alabama. Several 

geologic subareas are found along this coast and they vary biologically. The environmental descriptions 

of this coast are organized into three geologic subareas: (1) the larger western portion of the Chenier 

Plain that extends into eastern Texas and western Louisiana (the western component of this feature has 

been previously discussed in Chapter 4.1.1.3.1); (2) the Mississippi River Delta complex of southeastern 

Louisiana; and (3) the barrier-island and Pleistocene Plain complex of Mississippi and Alabama. The 

landmasses in these areas are relatively low, so some form broad flat plains with gradually sloping 

topographies. Tides there are diurnal and micro-tidal. Tidal influences can be seen 25-40 mi (40-64 km) 

inland in some areas of Texas, Louisiana, and Alabama due to large bay complexes, channelization, and 

low topographies. Wind-driven tides are often dominant over the minimal gravity tides that occur there. 

Since the last analysis and description of the CPA resources, there have been several major hurricanes 

in or near the CPA, as well as the DWH event, the largest oil spill ever recorded in the U.S. As a result of 

both of these factors, the existing condition of the barrier and beach resources has been altered. The 

descriptive narrative for these resources that follows reflects the post-storm and post-spill status of these 

resources. The general discussion of barrier island and beach formation discussed in Chapter 3.2.1.1 of 

the Multisale EIS and in Chapter 4.1.3.1.1 of the 2009-2012 Supplemental EIS can be applied to both the 

CPA and the WPA. This discussion focuses on which resources have experienced oil exposure and to 

what degree the resources were oiled. The information discussed is based on information from the 

Department of the Interior’s Shoreline Cleanup Assessment Team (SCAT) maps and reports that are 

publicly available as of September 27, 2010; newspaper interviews; scientific magazines; and public, 

State, and Federal resource agency Deepwater Horizon oil-spill-response sites available on the Internet. 

Areas that have had oil exposure are identified, as these are part of the existing condition of the resource. 

No assumptions as to health of the resource are made here since monitoring and studies are ongoing. In 

Chapter 4.1.1.3.3, there is discussion based on past studies, current interviews with scientists 

participating in field studies, and observation teams on what types of possible effects the spill could have 

on these resources. 

Chenier Plain 

The Chenier Plain of eastern Texas and western Louisiana began developing about 2,800 years ago. 

During that period Mississippi River Delta sediments were intermittently eroded, reworked, and carried 

into the Chenier Plain area by storms and coastal currents. This deposition gathered huge volumes of 

mud and sand, and formed a shoreface that slopes very gently (almost imperceptibly) downward for a 

long distance offshore. This shallow mud bottom is viscous and elastic, which generates hydrodynamic 

friction (Bea et al., 1983). Hence, wave energies along the barrier shorelines of the Chenier Plain are 

greatly reduced and cause minimal longshore sediment transport along the Chenier Plain (USDOI, GS, 

1988). More recently, this shoreline has been eroding as sea level rises. This process converts most of 

the coast to transgressive shorelines. 

During periods when the course of the Mississippi River was at the western edge of its Deltaic Plain, 

sediments from the river were carried westward by currents along the shore. This formed mudflats along 

the Chenier Plain shoreline (Kemp, 1986). When the active river channel moved eastward and the 
Description of the Environment and Impact Analysis 4-45 

Chenier Plain lost most of its sediment supply, erosion reworked the mud deposits This winnowed out the 

finest materials and formed beachfront ridges (cheniers) along the coast, leaving remnants of the old 

mudflats (now marshes) behind them. The present topography reflects multiple river mouth ridges 

converging to form a single beachfront ridge between the river inlets (Gosselink et al., 1979). With the 

increase of flow this century in the Atchafalaya River close to the western edge of the delta, fluvial 

processes are again dominating the Chenier Plain, and mudflat development is occurring along its eastern 

coast (Kemp, 1986). Today, the Red River and about 30 percent of the Mississippi River are diverted to 

the Atchafalaya River. The diversions have increased the sediment load in the longshore currents that 

generally move slowly westward along the coast. 

The barrier beaches of the Chenier Plain are generally narrow, low, and sediment starved due to the 

nature of coastal currents and the shoreface. Beach erosion has exposed relic marsh terraces that were 

buried by past overwash events. The Chenier Plain also supports an extensive marshland interspersed 

with large inland lakes formed in river valleys that were drowned after the last glaciation. When the sea 

reached its present level, the shoreline was more landward. Hurricane Rita (2005) severely impacted the 

shoreface and beach communities of Cameron Parish in southwest Louisiana. Some small towns in this 

area have no standing structures remaining. A storm surge approaching 6 m (20 ft) caused beach erosion 

and overwash, which flattened coastal dunes, depositing sand and debris well into the back marshes. 

After Rita, Hurricane Ike (2008) came ashore just west of the Texas/Louisiana border, severely impacting 

the eastern Chenier Plain near Cameron, Louisiana. A storm surge of 1-3 m (3-10 ft) overtopped the 

beach and severely impacted the Chenier Plain. 

Coastal change includes both beach erosion and erosion of channels where water continues to flow 

seaward to the Gulf of Mexico (Doran et al., 2009). In addition to the hurricane effects, the shoreline of 

the Chenier Plain was exposed to dispersed oil from the DWH event. Based on the SCAT observation 

maps available as of September 20, 2010, that portion of the Louisiana coastline from the area east of the 

Chenier Plain to the Mississippi/Louisiana State boundary was exposed to oil. The shoreline was 

untouched from this point to just east of Rockefeller Wildlife Refuge and Game Preserve (LA State 

Highway 3147). Observations by the SCAT field observers noted no oil in these areas. Since there is no 

publicly available archival information on any changes to the Chenier Plain from oil exposure, it can only 

be reported that the areas were oiled but to varying degrees and for varying durations. The oiled sites are 

still under observation and the cleanup and monitoring operations are ongoing. 

Mississippi River Delta Complex 

The Mississippi Delta region comprises much of coastal Louisiana and adjacent Mississippi. It 

stretches from the Atchafalaya Bay to the Chandeleur Islands and includes the New Orleans metropolitan 

area. The Delta complex contains major river channels and levees, bayous, swamps, marshes, lakes, tidal 

flats and channels, barrier islands, and shallow sea environments. Most barrier shorelines of the 

Mississippi River Delta in Louisiana are transgressive and trace the seaward remains of a series of five 

abandoned deltas. As a lobe of the delta is abandoned by a shift in drainage, that portion begins to 

subside slowly into the sea and is further reduced by erosion. Some of the sediment may be reworked by 

wind and waves into barrier islands. The Chandeleur Islands and Grand Isle are an excellent example of 

this situation. Gradually woodland vegetation became established on the dune sands (e.g., oaks and 

oleander). Salty meadows, marshes, and lagoons occupy the lower terrain. Today, the Mississippi River 

is channelized through the Belize Delta, more commonly known as the Birdfoot Delta. Channelization 

isolated the river from most of this sixth delta, except near the distributary mouths. There, a small 

fraction of the river’s sediment load is contributed to longshore currents for building and maintaining 

barrier shores. The bulk of river sediments are deposited in deep water, where they cannot be reworked 

and contribute to the longshore sediment drift. The shorefaces of the Mississippi River Delta complex 

slope gently seaward, which reduces wave energies at the shorelines. Mud flats are exposed during very 

low tidal events. This slope is not as shallow as that found off the Chenier Plain. The steepest shoreface 

of the delta is found at the Caminada-Moreau Coast, where the greatest rates of erosion occur. At this 

site, the longshore currents split to the east and west, which removes sand from the area without 

replenishment (Wolfe et al., 1988; Wetherell, 1992; Holder and Lugo-Fernandez, 1993). 

Regressive shorelines do occur in Louisiana’s deltaic region. The diversion at the Atchafalaya River 

has allowed the transport of large volumes of sediment into the shallow Atchafalaya Bay. There, inland 
4-46 Central Planning Area Supplemental EIS 

deltas are forming at the mouths of the Atchafalaya River and Wax Lake Outlet. Satellite photography of 

these deltas reveals that dredge-disposal islands were constructed off Point au Fer in shallow water 

(3-5 ft; 1-2 m) at the mouth of Atchafalaya Bay. If the Atchafalaya River Delta continues to build 

seaward as expected, these islands and the surrounding shallows would provide the foundations for a 

future barrier shoreline in this area. 

Barrier island chains in the northern GOM extending from Atchafalaya Bay, Louisiana, to Mobile 

Bay, Alabama, are disintegrating rapidly as a result of combined physical processes involving sediment 

availability, sediment transport, and sea-level rise. The cumulative areas and rates of landloss from these 

ephemeral features are to some extent expected because present physical conditions are different from 

those that existed when the islands first formed. For example, during the past few thousand years 

sediment supply has diminished, rates of relative sea-level rise have increased, and hurricanes and winter 

storms have been frequent events that generate extremely energetic waves capable of permanently 

removing sediment from the islands. These processes continuously act in concert, increasing the rates of 

beach erosion and reducing the area of coastal land. 

At greatest risk of further degradation are the barrier islands associated with the Mississippi Delta; 

these include the Chandeleur-Breton Island, Timbalier Island, and Isle Dernieres chains in Louisiana. 

These chains of individual transgressive barrier island segments have progressively diminished in size 

while migrating landward (McBride et al., 1992). Most of southeastern Louisiana’s barrier beaches are 

composed of medium to coarse sand. Small shoreline regressions occur as a result of jetties located on 

the eastern end of Grand Isle, the western end of Caminada-Moreau Beach, the Empire navigational 

canal, and elsewhere in Louisiana. Most dune zones of the Mississippi River Delta contain low, singleline dune ridges that may be sparsely to heavily vegetated. Generally in this area, the vegetation on a 

dune ridge gets denser as the time between storms lengthens. Unfortunately, the past decade had an 

increase in tropical storm activity for the project area. 

Hurricane Katrina (2005) caused severe erosion and landloss for the coastal barrier islands of the 

Deltaic Plain. The eye of Hurricane Katrina passed directly over the 50-mi (80-km) Chandeleur Island 

chain. Aerial surveys conducted by USGS on September 1, 2005, show that these islands were heavily 

damaged by the storm (USDOI, GS, 2005). The Chandeleur Islands were reduced by Hurricane Katrina 

from 5.64 mi2

 to 2.5 mi2 and then to 2.0 mi2 by Hurricane Rita (Di Silvestro, 2006). Grand Isle received 

extremely high winds and a 12- to 20-ft (3.5- to 6-m) storm surge that caused tremendous structural 

damage to most of its camps, homes, and businesses (Louisiana Sea Grant, 2006). Although barrier 

islands and shorelines have some capacity to regenerate over time, the process is very slow and often 

incomplete. With each passing storm, the size and resiliency of these areas can be diminished, especially 

when major storms occur within a short time period. Hurricane Katrina was the fifth hurricane to impact 

the Chandeleur Island chain within an 8-year period. The other storms were Hurricanes Georges (1998), 

Lili (2002), Ivan (2004), and Dennis (2005). Landmass rebuilt since Hurricane Ivan was subsequently 

washed away by Hurricane Katrina. Hurricanes Gustav and Ike (2008) reactivated ponds caused by the 

surge of Katrina. These ponds, some containing disturbance vegetation (Steyer et al., 2007), occurred in 

intermediate and fresh marshes located between Lake Lery and the Mississippi River. Surge impacts of 

Hurricane Gustav in the Deltaic Plain are smaller in scale and magnitude than surge impacts of Hurricane 

Ike in the Chenier Plain. The effects of Hurricane Gustav were also seen in the further erosion of the 

Chandeleur Islands, as well as significant erosion of the barrier islands forming the southern boundary of 

Terrebonne and Timbalier Bays (Barras, 2009). The Chandeleur Islands were reduced to 544.5 ha 

(1,345.5 ac), a reduction of 102.6 ha (253.5 ac) from the island’s land area of 647.1 ha (1,599.0 ac) in 

2006 (Barras, 2009). Following Hurricane Ike, significant surge-formed and surge-expanded ponds were 

not really noticeable east of Vermilion Bay (Barras, 2007a). Some new scours located on southeastern 

Marsh Island were originally scoured by Hurricane Lili on October 3, 2002 (Barras, 2007a). Water levels 

were visibly lower on the 2006 imagery of the Marsh Island area, causing the shallow scours to be 

classified as land in that dataset. Boyd and Penland (1988) estimated that storms raise mean water levels 

1.73-2.03 m (5.68-6.66 ft) above mean sea level from 10 to 30 times per year. Under those conditions, 

barrier islands of the Mississippi River Delta complex experience severe overwash of up to 100 percent. 

Shell Key is a barrier feature that varies greatly from the others around the Delta. It is located south of 

Marsh Island, Louisiana, at the mouth of Atchafalaya Bay, and is composed almost entirely of oystershell fragments. It is found amid extensive shell reefs, which are part of the Shell Keys National Wildlife 

Refuge. This dynamic feature builds and wanes with passing storms. In 1992 and 1999, Hurricanes 
Description of the Environment and Impact Analysis 4-47 

Andrew and Francis reduced the island to little more than a shoal. The shallow, submerged shell reefs 

around Shell Key also serve as barrier features. Located on the other side of the bay’s mouth and to the 

southeast, the Point au Fer Shell Reefs were commercially dredged for shells, and no longer exist 

(USDOI, FWS, 2001; Schales and Soileau, personal communication, 2001). 

In addition to the hurricanes and winter storms, the Mississippi River Delta complex and its 

associated barrier islands were initially oiled as a result of the DWH event. Before the capping and 

permanent plugging of the well was complete, oil had reached the shorelines of the Chandeleur Islands, 

Whiskey Island, Raccoon Island, South Pass, East Fourchon/Elmers Island, Grand Isle, Trinity Island, and 

Brush Island (Cleveland, 2010). As of September 24, 2010, approximately 367 mi (591 km) of 

Louisiana’s shoreline had some exposure to oil (USDOI, FWS, 2010a). Some areas were oiled more than 

once. The oiling ranged from light to heavy to occasional tarballs depending on the location and time. In 

most cases, the oil came ashore in lines perpendicular to the shoreline rather than in sheets. In an attempt 

to protect the Chandeleur Islands and the marshes shoreward of the islands from oil, the State of 

Louisiana constructed protective berms seaward of the islands. These berms are considered as part of the 

currently existing environment due to potential negative effects that this construction may have on the 

viability and sustainability of the protected island. 

Mississippi and Alabama Coasts 

The only factor that has a historical trend that coincides with the progressive increase in rates of 

landloss is the progressive reduction in sand supply associated with nearly simultaneous deepening of 

channels dredged across the outer bars of the three tidal inlets maintained for deep-draft shipping. 

Neither rates of relative sea-level rise nor storm parameters have long-term historical trends that match 

the increased rates of landloss since the mid-1800’s. The historical rates of relative sea-level rise in the 

northern Gulf of Mexico have been relatively constant, and storm frequencies and intensities occur in 

multidecadal cycles. However, the most recent landloss accelerations are likely related to the increased 

storm activity since 1995. The cumulative areas and rates of landloss from these ephemeral features are 

to some extent expected because present physical conditions are different from those that existed when 

the islands first formed. For example, during the past few thousand years sediment supply has 

diminished, rates of relative sea-level rise have increased, and hurricanes and winter storms have been 

frequent events. These processes continuously act in concert, increasing rates of beach erosion and 

reducing the area of coastal land. 

The Mississippi-Alabama barrier islands do not migrate landward as they decrease in size. Instead, 

the centers of most of the islands are migrating westward in the direction of the predominant littoral drift 

through processes of updrift erosion and downdrift deposition (Richmond, 1962; Otvos, 1970). Although 

the sand spits and shoals of the Mississippi-Alabama barriers are being transferred westward, the 

vegetated interior cores of the islands remain fixed in space. Rucker and Snowden (1989) measured the 

orientations of relict forested beach ridges on the Mississippi barriers and concluded that the ridges and 

swales were formed by recurved spit deposition at the western ends of the islands. The Dog Keys define 

the Mississippi Sound of Mississippi and Alabama. Mississippi has about 33.9 mi (54.6 km) of barrier 

beaches on these islands (USDOI, FWS, 1999). Dauphin Island represents about another 7 mi (12 km). 

This relatively young group of islands was formed 3,000-4,000 years ago as a result of shoal-bar accretion 

(Otvos, 1979). They are separated by wide passes with deep channels. Shoals are typically adjacent to 

these barriers. Generally, these islands are regressive and stable in size as they migrate westward in 

response to the predominantly westward-moving longshore currents. These islands generally have high 

beach ridges and prominent sand dunes. The islands are well vegetated among and behind the dunes and 

around ponds. Southern maritime climax forests of pine and palmetto are found behind some of their 

dune fields. 

Dauphin Island, Alabama, is the exception to the above description. It is essentially a low-profile, 

transgressive barrier island, except for a small, eroding, Pleistocene core at its eastern end. The western 

end is a Holocene spit that is characterized by small dunes and many washover fans, exposed marsh 

deposits, and tree stumps exposed in the surf zone. Dauphin Island experienced significant shoreline 

retreat and rollover after Hurricane Katrina, with overwash deposits forming in the sound. Pelican Island, 

Alabama, is a vegetated sand shoal located Gulfward of Dauphin Island. Southeasterly of that island is 

Sand Island, which is little more than a shoal. These barrier islands are part of Mobile Bay’s ebb-tidal 
4-48 Central Planning Area Supplemental EIS 

delta. As such, they continually change shape under storm and tidal pressures. Their sands generally 

move northwesterly into the longshore drift, nourishing beaches downdrift. These sediments can also 

move landward during flood tides (Hummell, 1990). The Gulf Shores region of Alabama extends from 

Mobile Point eastward to the Florida boundary, a distance of about 31 mi (50 km) (Smith, 1984). It has 

the widest beaches and largest dune system among the barrier beaches in the CPA. 

Since the mid-1800’s, average rates of landloss for all the Mississippi islands accelerated 

systematically. There is an inverse relationship between island size and percentage of land reduction for 

each barrier. For example, Horn Island lost 24 percent and Ship Island lost 64 percent of its area since the 

mid-1800’s (Morton, 2008). Ship Island is particularly vulnerable to storm-driven landlosses because 

topographic and bathymetric boundary conditions focus wave energy onto the island. The three 

predominant morphodynamic processes associated with landloss are as follows: (1) unequal lateral 

transfer of sand related to greater updrift erosion compared with downdrift deposition; (2) barrier 

narrowing resulting from simultaneous erosion of the Gulf and soundside shores; and (3) barrier 

segmentation related to storm breaching. The western portion of Dauphin Island is migrating landward as 

a result of storms that erode the Gulf shore, overwash the island, and deposit sand in Mississippi Sound. 

This has caused a gain in land during the 20th century. Petit Bois, Horn, and Ship Islands have migrated 

westward as a result of predominant westward sediment transport by alongshore currents, and Cat Island 

is being reshaped as it adjusts to post-formation changes in wave and current patterns associated with 

deposition of the St. Bernard lobe of the Mississippi Delta (Morton, 2008). 

The principal causes of barrier island landloss are frequent intense storms, a relative rise in sea level, 

and a deficit in the sediment budget. However, the most recent landloss accelerations are likely related to 

the increased storm activity since 1995. Although overwash channels do not commonly occur, the islands 

may be overwashed during strong storms, as was seen after Hurricanes Ivan (2004), Dennis (2005), and 

Katrina (2005). Hurricane Katrina’s storm surge caused substantial beach erosion and, in some cases, 

completely devastated coastal areas. In Dauphin Island, approximately 90 mi (150 km) to the east of the 

point where the hurricane made landfall, the sand that comprised the barrier island was transported across 

the island into Mississippi Sound, pushing the island towards land. 

Aside from the hurricane effects on the barrier island and beach resources, the DWH event exposed 

most of the Gulf Coast shoreline to some degree of oiling, i.e., from western Louisiana to the Florida 

panhandle. Based on the SCAT ground observation, the cumulative amount of shoreline oiled as of 

September 27, 2010, was 494 mi (795 km) (USDOI, FWS, 2010a). This cumulative figure of oiled 

shoreline includes shorelines of beaches and barrier islands that were exposed to oil, whether it was very 

light, light, moderate, heavily oiled, or only observations of tarballs. As of September 27, 2010, only 176 

km (109 mi) of shoreline was considered moderately to heavily oiled, with 158 km (98 mi) in Louisiana, 

and 18 km (11 mi) in Florida. In Louisiana, the heavy to moderate oiling was sporadic along the 

shorelines of Grand Terre Island, Grand Isle, and Bay Batiste. By May 23, 2010, the Louisiana 

Department of Environmental Quality had confirmed shoreline impact on the Chandeleur Islands, 

Whiskey Island, Raccoon Island, South Pass, East Fourchon/Elmers Island, Grand Isle, Trinity Island, 

Brush Island, the Pass a Loutre area, and Marsh Island. On June 1, 2010, oil first appeared on Dauphin 

Island off the coast of Alabama near the mouth of Mobile Bay. Strands of oil about a 1 m (3 ft) wide and 

2 mi (3 km) long were found on Petit Bois Island near the Mississippi-Alabama border (Cleveland, 2010). 

The shoreline in the Barataria Bay complex, along with the shorelines west of the Mississippi River Delta 

complex, received the most oil (Cleveland, 2010). Some of these areas may have been oiled several 

times. It must be noted that the SCAT maps do not indicate a continuous, uninterrupted area of oiled 

shoreline. Because these coastlines encountered some degree of oiling, oil is now part of the existing 

condition of the resource. 

Deepwater Horizon Event Oil Exposure 

In April 2010, the explosion of the DWH drilling platform resulted in the largest oil spill in the 

history of U.S. The spill was approximated at 4.9 million barrels; the well was capped on July 15, 2010, 

after oil flowed into the Gulf for 87 days. The drilling rig was located west of the Mississippi River 

approximately 90 mi (145 km) from the Louisiana coast. The bulk of the oil was off the coast of 

Louisiana, but eventually the oil spread east of the Mississippi River along the Mississippi, Alabama, and 

Florida coastlines as far away as Panama City, Florida. At the time of preparation of this Supplemental 
Description of the Environment and Impact Analysis 4-49 

EIS, there was little conclusive scientific information on the impacts of the spill. The available 

information presented here is primarily from accounts based on interviews with scientists or personnel 

with the USCG’s Oil Spill Response Team at the Unified Command Post overseeing cleanup operations. 

Various wildlife and resource agencies have launched SCAT to locate the oil as it appears in order to 

engage cleanup teams. Other agencies are involved in the NRDA process that is collecting data to 

identify and quantify the impacts of the spill. To date, none of this information is publicly available; 

therefore, the information presented here only notes what resources have been contacted by the spilled oil 

based on the SCAT observation maps and data available from interviews of local scientists participating 

in the oil response effort. 

4.1.1.3.2. Impacts of Routine Events 

Background/Introduction 

Impacts to the general vegetation and physical aspects of coastal environments by routine activities 

resulting from the CPA proposed action are considered in detail in Chapter 4.2.2.1.3.1 of the Multisale 

EIS and in Chapter 4.1.3.1.2 of the 2009-2012 Supplemental EIS. The following is a summary of the 

information presented in the Multisale EIS and the 2009-2012 Supplemental EIS, and new information 

that has become available since both documents were prepared 

This section considers impacts from routine activities associated with the CPA proposed action to the 

physical shape and structure of barrier beaches and associated dunes. The primary impact-producing 

routine activities associated with the proposed action that could affect these environments include 

pipeline emplacements, navigation channel use (vessel traffic) and dredging, and the use and construction 

of support infrastructure. As a result of the DWH event, remnant oil is still being found either in the 

water column or on the bottom in some areas (Cleveland, 2010). If the remnant oil is encountered, 

routine activities such as dredging or vessel traffic can potentially resuspend and transport it within the 

area. The oil is greatly weathered and treated, so it is expected to have low or no level of toxicity for 

interstitial beach inhabitants. The following sections describe the sources and types of these potential 

impacts. 

Pipeline Emplacements 

Where a pipeline crosses the shoreline is referred to as a pipeline landfall. Many OCS pipelines make 

landfall on Louisiana’s barrier island and shorelines. Pipeline landfall sites on barrier islands could cause 

accelerated beach erosion and island breaching. The CPA proposed action does not include new pipelines 

that make landfall on barrier islands or mainland beaches. If more detailed site-specific, postlease 

analysis indicates barrier beach landfalls are necessary, modern techniques such as directional drilling 

would be used to bring the pipeline ashore. Studies have shown that little to no impact to barrier beaches 

results from modern techniques such as directional boring (LeBlanc, 1985; Mendelssohn and Hester, 

1988; Wicker et al., 1989). Since 2002, only one new pipeline has come to shore in Louisiana from OCSrelated activities. The 30-in Endymion Oil Pipeline, which delivers crude oil from South Pass Block 89 

to the LOOP storage facility near the Clovelly Oil and Gas Field, was installed in 2003. Based on a 

review of the data in the COE permit application (No. 20-020-1632), the emplacement of the pipeline 

caused zero impacts to marshes (emergent wetlands) and beaches. This was because the operator used 

horizontal, directional (trenchless) drilling techniques to avoid damages to these sensitive habitats. 

Additionally, the pipeline route maximized an open-water route to the extent possible (a comprehensive 

description of current mitigation measures is discussed in Chapter 2.2.2). A comparison of aerial photos 

taken before and after Hurricanes Katrina and Rita reveal no observable landloss or impacts associated 

with the Endymion Oil Pipeline. Hurricane Gustav further eroded barrier beaches and completely 

degraded small islands such as Wine Island. Although Hurricane Gustav eroded some beaches and 

damaged onshore pipelines near Port Fourchon, offshore pipelines were left intact. 

Vessel Traffic and Dredging 

Vessel traffic that may support the proposed action is discussed in Chapter 3.1.1.4 of this 

Supplemental EIS and in Chapter 4.1.1.8.4 of the Multisale EIS. Navigation channels projected to be 
4-50 Central Planning Area Supplemental EIS 

used in support of the proposed action are discussed in Chapter 3.1.2 of this Supplemental EIS and in 

Chapter 4.1.2.1.9 of the Multisale EIS. Navigation channels that support the OCS Program are listed in 

Table 3-36 of the Multisale EIS. Current navigation channels will not change and no new navigation 

channels are required as a result of the proposed action. 

Waves generated by boats, ships, barges, and other vessels erode unprotected shorelines and 

accelerate erosion in areas already affected by natural erosion processes. Much of the service-vessel 

traffic that is a necessary component of OCS activities uses the channels and canals along the Louisiana 

coast. Potential for resuspension and transport of oil from the DWH event exists as a result of heavy 

vessel traffic or dredging in areas previously oiled. As a result of the storm surge of Hurricane Gustav, 

the channel at Port Fourchon lost depth from siltation and displacement of some of the rock channel 

armor. This channel may require some minimal maintenance dredging. 

Based on earlier studies by Johnson and Gosselink (1982), canal widening rates in coastal Louisiana 

range from about 2.58 m/yr (8.46 ft/yr) for canals with the greatest boat activity to 0.95 m/yr (3.12 ft/yr) 

for canals with minimal boat activity. A recent study entitled “Navigation Canal Bank Erosion in the 

Western and Central Gulf of Mexico” indicates that shoreline retreat rates along canals were highly 

variable within and across unarmored portions of the canals (Thatcher et al., 2011). It was noted that 

geology and vegetation type influenced the rate of shoreline change. The study also noted that the canal 

widening rate slowed to -0.99 m/yr (-3.25 ft/yr) for the 1996/1998-2005/2006 time period as compared 

with -1.71 m/yr (-5.61 ft/yr) 1978/1979-1996/1998 time period. The existing armored navigation 

channels (e.g., Port Fourchon) that are used to reach shore bases will minimize or eliminate the potential 

for shoreline erosion from vessel traffic. Widening rates for navigation canals have been reduced as a 

result of aggressive management and the restoration of canal edges to prevent erosion. An example of 

this is the construction of rock breakwaters along portions of some of these canals, as well as enforcing 

“wake zone” speeds (Johnston et al., 2009). In addition, BOEMRE and the USGS National Wetlands 

Resource Center have designed and funded a study that was reviewed and coordinated with the Louisiana 

Department of Environmental Quality to better understand salinity behavior in marshes adjacent to 

navigation canals (Snedden, in preparation). This 2-year study began in January 2010 and is scheduled 

for completion in December 2011. 

Continued Use of Support Infrastructure 

In the past, OCS-related facilities were built in the vicinity of barrier shorelines of the CPA. The use 

of some existing facilities in support of the CPA proposed action and subsequent lease sales in the CPA 

may extend the useful lives of those facilities. During that extended life, erosion-control structures may 

be installed to protect a facility. Although these measures may initially protect the facility as intended, 

such structures may accelerate erosion elsewhere in the vicinity. They may also cause the accumulation 

of sediments updrift of the structures. These sediments might have alleviated erosion downdrift of the 

structure. These induced erosion impacts would be most damaging locally. In deltaic Louisiana where 

the sediment supply is critically low, these impacts may be distributed much more broadly. These 

impacts will last as long as the interruption of the sediment drift continues, and that can continue after the 

structure is removed if the hydrodynamics of the area are permanently modified. Expansions of existing 

facilities located on barrier beaches or in associated dunes would cause loss and disturbance of additional 

habitat. Abandoned facility sites must be cleared in accordance with Federal, State, and local 

government, and landowner requirements. Materials and structures that would impair or divert sediment 

drift among the dunes and on the beach must be removed. 

Proposed Action Analysis 

Zero to one pipeline landfalls are projected as a result of the CPA proposed action, resulting in up to 

2 km (1.2 mi) of onshore pipeline. Should one be constructed, it would most likely be in Louisiana, 

where the large majority of the infrastructure exists for receiving oil and gas from the CPA. No landfalls 

are presently planned for barrier or mainland beaches, but if it is later determined that such a landfall in 

the vicinity of a barrier beach and associated dunes is necessary, current regulatory procedures would be 

used to evaluate any impacts associated with the action. Wherever a landfall occurs, regulatory programs 

and permitting processes (COE and the Louisiana Dept. of Natural Resources) are sequenced to ensure 

wetlands are protected first through avoidance, then minimization of impacts, and finally compensation 
Description of the Environment and Impact Analysis 4-51 

for unavoidable impacts. The use of modern technologies (e.g., directional boring) greatly reduces and 

possibly eliminates impacts to coastal barrier islands and beaches. Therefore, effects on barrier beaches 

and dunes from pipeline laying activities associated with the CPA proposed action are expected to be 

minor or nonexistent. These impacts are considered to be negligible. Turner and Cahoon (1988) found 

that OCS traffic in general comprises a relatively small percentage (~12%) of the total commercial traffic 

using navigation channels. The average contribution of the CPA proposed action to OCS-related vessel 

traffic in navigation canals is expected to be small (2-3%). Erosion of coastal barrier beaches and 

associated dunes from vessel traffic associated with the CPA proposed action are expected to be 

negligible. 

Adverse impacts from maintenance dredging of navigation channels can be mitigated by discharging 

dredged materials onto barrier beaches or strategically into longshore sediment currents downdrift of 

maintained channels, or by using the dredged material to create wetlands. Negative effects of sediment 

sinks created by jetties can be mitigated by reducing the jetty length to the minimum needed and by filling 

the updrift side of the jetty with appropriate sediment. Sediment traps that are created by unnecessarily 

large bar channels can also be mitigated by reassessing the navigational needs of the port and by 

appropriately reducing the depth of the channel. Mitigating adverse impacts should be addressed in 

accordance with requirements set forth by the appropriate Federal and State permitting agencies. Effects 

on coastal barrier beaches and associated dunes associated with dredging from the CPA proposed action 

are expected to be restricted to minor and localized areas downdrift of the channel. There are 0-1 gas 

processing plants projected to be constructed as a result of the CPA proposed action. Should one be 

constructed, it would most likely be in Louisiana. Wherever a landfall occurs, regulatory programs and 

permitting processes of COE and the Louisiana Dept. of Natural Resources are sequenced to ensure 

wetlands are protected. Effects on coastal barrier beaches and associated dunes associated with 

construction of a gas processing plant from the CPA proposed action are expected to be restricted to 

minor and very localized areas downdrift of the channel. 

Summary and Conclusion 

Effects to coastal barrier beaches and associated dunes from pipeline emplacements, navigation 

channel use and dredging, and construction or continued use of infrastructure in support of the CPA 

proposed action are expected to be restricted to temporary and localized disturbances. The 0-1 pipeline 

landfalls projected in support of the proposed action are not expected to cause significant impacts to 

barrier beaches because of the use of nonintrusive installation methods and regulations. New processing 

plants would not be expected to be constructed on barrier beaches. The proposed action may contribute to 

the continued use of existing facilities, which can add to erosion. 

Maintenance dredging of barrier inlets and bar channels is expected to occur, which combined with 

channel jetties, causes minor and localized impacts on adjacent barrier beaches. This is due to permit 

regulations and mitigation efforts. The worst of these situations is found on the sediment-starved coasts 

of Louisiana, where sediments are largely organic. Because these impacts occur whether the proposed 

action is implemented or not, the proposed action would account for a small percentage of these impacts. 

In conclusion, the CPA proposed action is not expected to adversely alter barrier beach configurations 

significantly beyond existing, ongoing impacts in localized areas. Strategic placement of dredged 

material from channel maintenance, channel deepening, and related actions can mitigate adverse impacts 

upon those localized areas. 

4.1.1.3.3. Impacts of Accidental Events 

Background/Introduction 

Impacts to the general vegetation and physical aspects of coastal environments by oil spills and 

cleanup response activities resulting from the CPA proposed action are considered in Chapter 4.4.3.1 of 

the Multisale EIS and in Chapter 4.1.2.13 of the 2009-2012 Supplemental EIS. 

The types and sources of spills that may occur and their characteristics are described in Chapter 4.3.1

of the Multisale EIS and in Chapter 3.2 of this Supplemental EIS. There is also a risk analysis of 

accidental events in Chapter 3.2.1. Figures 4-13 and 4-14 of the Multisale EIS provide the probability of 

an offshore spill 1,000 bbl occurring and contacting counties and parishes around the Gulf. Potential 
4-52 Central Planning Area Supplemental EIS 

impacts from oil spills to barrier islands seaward of the barrier-dune system are considered in this section, 

while potential impacts to barrier islands landward of the barrier-dune system are considered in the 

wetlands analysis (Chapter 4.1.1.4.3). Impacts to biological, recreational, and archaeological resources 

associated with beach and dune environments are described in the impact analysis sections for those 

specific resources. 

The central Gulf Coast (i.e., Louisiana, Mississippi, Alabama, and western Florida) and the associated 

barrier islands and beaches have experienced an increase in frequency of high-intensity hurricanes and 

tropical storms over the past several years. As a result of four powerful hurricanes (i.e., Hurricanes 

Katrina, Rita, Gustav, and Ike), changes in barrier island topography and decreases in beach elevation 

potentially increased the probability for oiling farther up the beach head in some locations. Due to the 

more gentle slopes, removal of beach ridges, and cuts into the mainland barrier beaches, the remnant 

transition zone between the water and the current beach ridge may be more vulnerable to spills. In some 

areas along the Louisiana coast, barrier islands were severely damaged, resulting in either heavily 

degraded beachfront elevations and ridges or submergence of the island from sediments redistributed by 

the storm surge. In coastal Louisiana, dune-line heights have been drastically reduced by the storm 

activity. The Isle Dernieres and Chandeleur Island chains had losses in elevation and beach erosion. In 

Mississippi and Alabama, dune elevations exceed those in Louisiana but have been reduced to some 

extent due to storm activity. Hurricane Katrina completely inundated the western side of Dauphin Island, 

Alabama, decreasing elevations to less than 2 m (7 ft). Hurricane Gustav then completely overwashed the 

western edge of the island, resulting in large changes to the islands’ shape and topography (USDOI, GS, 

2008). For tides to carry oil from a spill across and over the dunes, strong southerly winds would have to 

persist for an extended time prior to or immediately after a spill. Strong winds required to produce such 

high tides would also accelerate dispersal and spreading of the oil slick, thereby reducing impact severity 

at the landfall site. Significant dune contact by a normal spill associated with the proposed action is not 

likely; however, the reduced degree of protection does make the mainland beaches and habitat on the 

back side of the barrier islands more susceptible to oiling than they were under pre-storm if winds bring 

the oil shoreward. 

Aside from the hurricane effects on the barrier islands and beach resources, the DWH event exposed 

most of the Gulf Coast shoreline from western Louisiana to the Florida panhandle to some degree of 

oiling. Based on the SCAT ground observation, the cumulative amount of shoreline oiled as of 

September 27, 2010, was 795 km (494 mi) (USDOI, FWS, 2010a). The cumulative figure of oiled 

shorelines includes beaches and barrier island associated shorelines that were exposed to oil, be it very 

light, light, moderate, heavily oiled, or tarballs. Moderately to heavily oiled shorelines were 176 km (109 

mi) for the GOM with 157 km (98 mi) in Louisiana, 14 km (9 mi) in Mississippi, and 3 km (2 mi) in 

Florida. 

The amount of shoreline oiled changes daily based on the observations of SCAT. In Louisiana, the 

heavy to moderate oiling was sporadic along the shorelines of Grand Terre, Grand Isle, and Bay Batiste. 

By May 23, 2010, the Louisiana Department of Environmental Quality confirmed shoreline impact on 

the Chandelier Islands, Whiskey Island, Raccoon Island, South Pass, East Fourchon/Elmers Island, Grand 

Isle, Trinity Island, Brush Island, the Pass a Loutre area, and Marsh Island. On June 1, 2010, oil first 

appeared on Dauphin Island, and strands of oil (1 m x 3 km; 3 ft x 2 mi) were found on Petit Bois Island 

near the Mississippi/Alabama border (Cleveland, 2010). The shoreline in the Barataria Bay complex as 

well as the shorelines west of the Mississippi Delta complex received the most oil (Cleveland, 2010). 

Although it is known where oil was observed onshore, these oiling estimates do not reflect a continuous, 

uninterrupted area of oiled shoreline. 

A large amount of dispersants was used offshore at or near the well site, and oil was kept offshore by 

booms and skimming for long periods of time. These mitigating factors, combined with the natural 

weathering of the oil, should greatly reduce the toxicity of the incoming oil from offshore. After NRDA 

releases the data concerning the condition of the incoming oil, long-term and local effects of the oil on the 

shoreline can be discussed in more detail. 

Proposed Action Analysis 

Barrier islands and beaches adjacent to the CPA are restricted to the coastal waters of Louisiana, 

Mississippi, Alabama, and eastern Florida. The greatest threat to the barrier island and beach resources 
Description of the Environment and Impact Analysis 4-53 

would be from inland oil spills. Based on the assumption that spill occurrence is proportional to the 

volume of oil handled, sensitive coastal environments in eastern Louisiana from Atchafalaya Bay to east 

of the Mississippi River (including Barataria Bay) have the greatest risk of contact from spills related to 

the CPA proposed action. Approximately 49-126 spills are estimated to occur within Gulf coastal waters 

from activities supporting the CPA proposed action over the 40-year life of the lease sale. Most (about 

90%) of these spills would be 1 bbl. The most likely locations of the estimated 44-114 coastal spills 

<1 bbl would be proximate to the major oil pipeline or shore facilities (Table 3-7). The greatest risk of 

contact would be from the assumed 3,000-bbl spill should it occur within or near wetlands. The 

incremental increase in oil production from this lease sale is not expected to result in an overall increase 

in the number of oil spills ≥1,000 bbl likely to occur as a result of the CPA proposed action. Activity that 

would result from the addition of this lease sale would cause a negligible increase in the risk of a large 

spill occurring and contacting barrier islands and beaches. If oil should reach the beaches from this 

distance, it would be sufficiently weathered and detoxified through biodegradation, mixing, and the 

weathering process. 

The probabilities of an offshore spill ≥1,000 bbl occurring and contacting environmental features are 

described in Chapter 4.3.1.8 of the Multisale EIS. Eight parishes in Louisiana have a chance of spill to 

contact their shores. For these parishes, the chance of an OCS offshore spill ≥1,000 bbl ranges from 1 to 

15 percent. Generally, the coastal, deltaic parishes of Louisiana have the highest risk of being contacted 

by an offshore spill from the CPA proposed action. Plaquemines Parish has the highest probability at 

10-15 percent (Chapter 4.3.1.8 of the Multisale EIS). For offshore spills <1,000 bbl, only those >50 bbl 

would be expected to have a chance of persisting as a cohesive slick long enough for the slick to reach 

land. Few offshore spills of 50-1,000 bbl are estimated to occur as a result of the proposed action, and a 

few of these slicks are expected to occur proximate to State waters and to reach shore. Should a slick 

from such a spill make landfall, the volume of oil remaining in the slick is expected to be small. 

Sensitive coastal environments in eastern Louisiana, from Atchafalaya Bay to east of the Mississippi 

River, including Barataria Bay, have the greatest risk of being contacted by spills from operations related 

to the CPA proposed action. Should a spill contact a barrier beach, oiling is expected to be light and sand 

removal during cleanup activities minimized. No significant impacts to the physical shape and structure 

of barrier beaches and associated dunes are expected to occur as a result of the CPA proposed action. 

Although the probability of a catastrophic spill such as the DWH event is low, the potential impacts 

of such a spill is discussed in Appendix B to the extent possible with the current data available.

Oil-Spill Impacts 

The results of earlier studies done in Texas (Webb, 1988) utilizing oiled and unoiled sands indicated 

the survival of dune transplants was better for both species of plants tested in the oil-contaminated dune 

than the oil-free dune. It was concluded that common dune plants can colonize or can be transplanted 

successfully into oil-contaminated sands. The explanation of the favorable survival is probably due to the 

weathering from the photo-oxidation, volatilization, and biodegradation of the oil. However; test results 

of the oiled sands indicated that, while lighter toxic alkanes and cycloalkanes were absent in the “oiled 

sands,” 21 percent of the crude oil was water-insoluble PAH’s. Analysis of the weathered crude oil did 

not indicate a high percentage of PAH’s. The study concluded that the weathering process removed most 

of the toxic compounds (Webb, 1988). 

There are various factors and conditions that affect the toxicity and severity of oil spills on the barrier 

island systems and the associated vegetation. The two most important variables involve location 

(distance of spill from landfall) and weather. If the there is sufficient distance and proper weather 

conditions between the spill and landfall, the spill can be dispersed and thinned. This would allow for 

optimal conditions for biodegradation, volatilization, and photo-oxidation. Therefore, due to the distance 

from shore, the weather, the time oil remains offshore, and the dispersant use, offshore-based crude oil 

would be less in toxicity when it reaches the coastal environments. 

Inland spills have the greatest potential for affecting the coastal barrier resources due to their 

proximity to the resources. Inland spills result from damage to pipelines, vessel collisions, malfunctions 

of onshore production or storage facilities; and blowouts have the greatest potential for contacting the 

barrier and mainland beach resources. The effects from these oil spills depends on the geographic 

location, volume, and rate of the spill; type of oil; oil-slick characteristics; oceanic conditions and season 
4-54 Central Planning Area Supplemental EIS 

at the time of the spill; and response and cleanup efforts. Inland spills from offshore coastal waters and in 

the vicinity of Gulf tidal inlets present a greater potential risk to barrier beaches and dunes because of 

their close proximity, but inland spills occurring away from Gulf tidal inlets are not expected to 

significantly impact barrier beaches and dunes. 

No significant impacts to the physical shape and structure of barrier beaches and associated dunes are 

expected to occur as a result of accidental events associated with the CPA proposed action. However, as 

a result of the DWH event, the State of Louisiana has partially constructed an oil mitigation berm seaward 

of the Chandeleur Islands. Theoretically, it is to protect the island and inland marshes from incoming oil. 

The Federal resource agencies (NMFS, FWS, and USEPA), as well as the local scientific community, is 

concerned that the berm may cause further erosion of the island because of changes to hydrology and 

topography (Lavioe et al., 2010). In addition, the use of heavy equipment for shaping the berm material 

and the chance of disturbing pipelines in the borrow areas could cause potential indirect impacts to the 

coast. 

Through the cleanup effort, associated foot traffic may work oil farther into the sediment than would 

otherwise occur. Close monitoring and restrictions on the use of bottom-disturbing equipment would be 

needed to avoid or minimize those impacts. Mainland beaches in Louisiana (Grand Isle and Grand 

Terre), Mississippi (Waveland, Biloxi, and Gulfport), Alabama (Perdido and Gulf Shores), and Florida 

(Santa Rosa, Pensacola, and Eglin) are currently undergoing either manual or mechanical cleanup 

primarily for tarballs or some submerged weathered oil mats. Mechanical, tractor-mounted sifters disrupt 

the sand base, cause compaction, and disturb the nontidal beach habitat. Should a spill contact a barrier 

beach, oiling is expected to be light and sand removal during cleanup activities minimized. 

Summary and Conclusion 

Because of the proximity of inshore spills to barrier islands and beaches, inshore spills pose the 

greatest threat. Such spills may result from either vessel collisions that release fuel and lubricants or from 

pipelines that rupture. Impacts of a nearshore spill would be considered short term in duration and minor 

in scope because the size of such a spill is projected to be small (coastal spills are assumed to be 5 bbl; 

Table 4-13 of the Multisale EIS). Offshore-based crude oil would be less in toxicity when it reaches the 

coastal environments. This is due to the distance from shore, the weather, the time oil remains offshore, 

and the dispersant used. Equipment and personnel used in cleanup efforts can generate the greatest direct 

impacts to the area. Close monitoring and restrictions on the use of bottom-disturbing equipment would 

be needed to avoid or minimize those impacts. 

The BOEMRE has reexamined the analysis for coastal barrier beaches and associated dunes presented 

in the Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented 

above. Although the most current information did reveal that some of the barrier islands had experienced 

storm-induced reductions in beach shoreline elevations and erosion, the significance of this loss of 

protection is small in comparison with the overriding climatic forces (USDOC, NMFS, 2007a). 

Therefore, this information would not alter the overall conclusion that impacts on barrier islands and 

beaches from accidental impacts associated with the CPA proposed action would be minimal. Should a 

spill other than a catastrophic spill contact a barrier beach, oiling is expected to be light and sand removal 

during cleanup activities minimized. No significant long-term impacts to the physical shape and structure 

of barrier beaches and associated dunes are expected to occur as a result of the CPA proposed action. The 

current lease sale would not pose a significant increase in risk to barrier island or beach resources. 

4.1.1.3.4. Cumulative Impacts 

A detailed description of cumulative impacts upon coastal barrier beaches and associated dunes can 

be found in Chapter 4.5.3.1 of the Multisale EIS and in Chapter 4.1.3.1.4 of the 2009-2012 Supplemental 

EIS. The following information is a summary of the resource description incorporated from the Multisale 

EIS, the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 
Description of the Environment and Impact Analysis 4-55 

Background/Introduction 

This cumulative analysis considers the effects of impact-producing factors related to the proposed 

action, prior and future OCS sales in the Gulf of Mexico, State oil and gas activities, other governmental 

and private projects and activities, and pertinent natural processes that may affect barrier beaches and 

dunes. Specific impact-producing factors considered in this cumulative analysis include channelization of 

the Mississippi River, beach protection and stabilization projects, natural processes, navigation channels, 

development and urbanization, oil spills, oil-spill response and cleanup activities, pipeline landfalls, 

potential for nearshore salinity modifications (preparation of salt domes for oil storage), tourism, and 

recreational activities. 

River Channelization and Beach Protection 

Channel deepening and widening along the Mississippi River and other major coastal rivers, in 

combination with channel training and bank stabilization work, has resulted in the reduced delivery of 

sediment to the eroding deltas along the mouths of the rivers. This reduction in sediment not only 

impedes delta building, but it also fails to provide the needed sediment transport required for nourishment 

of the eroding offshore barrier islands and their beaches. This, coupled with beach building and 

stabilization projects utilizing mined sands, jetties, groins, and other means of sediment capture, is 

depriving natural restoration of the barrier beaches normally accomplished through sediment nourishment 

and sediment transport. 

Subsidence, erosion, and dredging of inland coastal areas, with the concurrent expansion of tidal 

influences that are particularly as seen in Louisiana, continually increases tidal prisms around the Gulf. 

These changes may result in the opening and deepening of many new tidal channels that connect to the 

Gulf and inland waterbodies. These incremental changes would cause adverse impacts to barrier beaches 

and dunes. Efforts to stabilize the Gulf shoreline have adversely impacted barrier landscapes in 

Louisiana. Large numbers and varieties of stabilization techniques including groins, jetties, seawalls, and 

artificially maintained channels and jetties that were installed to stabilize navigation channels have been 

applied along the Gulf Coast. These efforts have contributed to coastal erosion by depriving downdrift 

beaches of sediments and by increasing or redirecting the erosional energy of waves (Morton, 1982). 

Over the last 20 years, better dune and beach stabilization has been accomplished by using more natural 

applications such as sand dunes, beach nourishment, and vegetative plantings. 

As a result of the DWH event, protective berms are being constructed seaward of barrier islands 

(Chandeleur Islands) to protect the inland marshes, wetlands, and seagrasses from incoming oil associated 

with this large spill. The effects of this berm construction on barrier islands could alter present sediment 

transport needed for barrier island growth, as well as change inlet velocities and hydrology in such a way 

that accelerated erosion of Chandeleur Island could occur (Lavoie et al., 2010). Aside from the 

construction impacts, the amount of mined sand required would continue to reduce the already scarce 

supply of sand needed for both natural barrier island building and future coastal restoration projects. 

Other potential cumulative and continuing impacts from this berm construction can be measured through 

long-term monitoring. These impacts include the fate of oil that may be sequestered in the mined sands, 

and the effects of their long-term release. The current testing of dredged sediments required under the 

COE dredging permit for the berm construction does not indicate the presence of petroleum-based 

toxicants at this time. The potential exists for anoxic conditions in deep holes where the sand is mined, 

but COE permit requirements establish that the underwater borrow sites should be backfilled or shallowed 

to the greatest extent possible. 

Natural Processes 

Barrier beaches along coastal Louisiana have experienced severe erosion and landward retreat 

(marine transgression) because of natural processes enhanced by human activities. Adverse effects on 

barrier beaches and dunes have resulted from changes to the natural dynamics of water and sediment flow 

along the coast. This can happen in an attempt to control catastrophic floods and change the natural 

environment to better accommodate navigation on waterways used to support OCS and non-OCS 

seaborne traffic. Sea-level rise and coastal subsidence with tropical and extra-tropical storms exacerbate 
4-56 Central Planning Area Supplemental EIS 

and accelerate the erosion of coastal barrier beaches along the Gulf Coast of Louisiana. The western edge 

of the CPA coast received major damage as a result of Hurricanes Katrina, Rita, Gustav, and Ike. 

The passage of these four powerful hurricanes within a 4-year period resulted in changes in barrier 

island topography and lowered beach elevation. These changes could potentially increase the probability 

for beach oiling farther up the beach in some locations. Due to the now more gentle slopes and in some 

cases cuts into the mainland barrier beaches left by the storms, more of the transition zone between the 

water and beach ridge may be more vulnerable to spills. In some areas along the Louisiana coast, barrier 

islands were severely damaged either by heavily degrading beachfront elevations and beach ridges or by 

completely overtopping the islands. This surge over the island resulted in either removing or completely 

redistributing the sediments on the island, so the island becomes submerged. Along the 

Mississippi/Alabama coast, barrier islands (e.g., Gulf Islands National Seashore chain and Dauphin 

Island) were further eroded and inlets widened by the series of storms following Hurricanes Katrina and 

Rita. The widening of inlets initiated by Katrina and Rita provided larger pathways for saltwater and oil 

influx into the island wetlands. Grand Isle, Louisiana, and its beach restoration project were severely 

damaged by Hurricanes Katrina and Gustav. These islands received oil on the beaches from the DWH 

event. 

Hurricane Rita in September 2005 severely impacted the shore face and beach communities of 

Cameron Parish in southwest Louisiana. These barriers lost elevation and vegetative cover as a result of 

the erosion forces accompanying the storm surge and scour from storm-driven debris (Barras, 2007b). 

This removal of vegetative cover and scour scars provides an avenue for additional erosion to occur as a 

result of inlet formations and tidal rivulets. These modifications to the topography may result in 

hydrological changes that enable further sediment transport from the islands. This provides pathways for 

further erosion and saltwater intrusion into the less salt-tolerant interior vegetated habitats of the islands. 

This loss of elevation, combined with the shoreline retreat and removal of vegetation further aggravated 

by the hurricanes, allowed for the expansion of the overwash zone. This lessens the pre-storm protection 

provided by these barrier islands. The reduction in island elevation results in less frontline protection to 

valuable marshes and makes urban and industrial areas protected by these marshes at a higher risk 

(USDOC, NMFS, 2007a). 

Hurricanes and tropical storms will remain a part of the Gulf Coast weather pattern and will continue 

to affect the elevations of barrier islands, mainland beaches, and dunes. Depending on storm frequency 

and intensity, it may be possible for coastal restoration and protection projects to mitigate some of the 

physical damage to these areas. 

Navigation Channels, Vessel Traffic, and Pipeline Emplacements 

The effects to coastal barrier beaches and associated dunes from pipeline emplacements, navigation 

channel use and dredging, and the construction or continued use of infrastructure in support of the CPA 

proposed action are expected to be restricted to temporary and localized disturbances. The estimated 0-1 

pipeline landfall projected in support of the CPA proposed action is not expected to cause significant 

impacts to barrier beaches because of the use of nonintrusive installation methods. The estimated 0-1 gas 

processing plant would not be expected to be constructed on barrier beaches (Chapter 4.2.2.1.3.1 of the 

Multisale EIS). Existing inland facilities may, through natural erosion and shoreline recession, be located 

in the barrier beach and dune zone and contribute to erosion there. The proposed action may contribute to 

the continued use of such facilities. Maintenance dredging of barrier inlets and bar channels is expected 

to occur, which, when combined with channel jetties, generally cause minor and localized impacts on 

adjacent barrier beaches downdrift of the channel due to sediment deprivation. The greatest effects from 

this are on the sediment starved coasts of Louisiana, where sediments are largely organic. These impacts 

would occur whether the proposed action is implemented or not. The proposed action is not expected to 

adversely alter barrier beach configurations significantly beyond existing, ongoing impacts in localized 

areas downdrift of artificially jettied and maintained channels. 

The CPA proposed action may extend the life and presence of facilities in eroding areas, which would 

accelerate localized erosion. The strategic placement of dredged material from channel maintenance, 

channel deepening, and related actions can mitigate adverse impacts upon those localized areas. With the 

established importance of barrier islands as frontline protection for both coastal wetlands and mainland 
Description of the Environment and Impact Analysis 4-57 

infrastructure, there are no current or future plans for routing navigation channels (if needed) through 

barrier islands. 

A large temporary increase in vessel traffic in the CPA resulted from the DWH event. Large numbers 

of specialty fire fighting, dispersant, and skimmer vessels were concentrated around the Louisiana coast. 

Skimmers, tugboats, sand barges, and dredges comprised the bulk of the vessel traffic that was in near 

proximity to barrier islands as a result of berm construction. Due to the distance from the barrier islands 

and slow speed of these vessels, it is unlikely these vessels markedly increased erosion rates of these 

islands. As noted previously, the possibility of changes in current patterns as a result of sand mining and 

sediment placement, may affect natural island building. In the short term, these vessels and dredges have 

the potential to resuspend oiled bottom sediments that may exist in the area of these islands or mainland 

shorelines. However, it is doubtful that cumulative erosion that results from increased vessel traffic 

related to catastrophic spills would occur because the probability of catastrophic spills is small. Also, it is 

doubtful that there will be increases in production wells over the 40-year period of OCS exploration 

because older wells will come out of service as new wells come into service. This being the case, there 

should not be a sustainable cumulative increase in the need for supply and support vessels. This is 

because vessel traffic would either decrease or reach a state of equilibrium to meet the needs of the 

working wells. The entire current 5-Year Program accounts for only 12 percent of the commercial ship 

traffic. The CPA proposed action is now estimated to account for 2-3 percent (calculated from Table 4-4 

of the Multisale EIS and Table 3-2 of this Supplemental EIS) of the service-vessel traffic of the current 

5-Year Program. Further details concerning vessel traffic can be found in Chapters 4.2.2.1.3.1 and 

4.1.1.8.4 of the Multisale EIS. Navigation channels projected to be used in support of the CPA proposed 

action are discussed in Chapter 4.1.2.1.9 of the Multisale EIS. 

Oil Spills 

Sources and probabilities of oil entering waters of the Gulf and surrounding coastal regions are 

discussed in Chapter 4.1.3.4 of the Multisale EIS. Inland spills that do not occur in the vicinities of 

barrier tidal passes are more likely to contact the landward rather than the ocean side of a barrier island. 

Hence, no inland spills are expected to significantly contact barrier beaches (Chapter 4.2.2.1.3.1 of the 

Multisale EIS). 

Most spills occurring in offshore coastal waters are assumed to proportionally weather and dissipate 

before hitting the Louisiana coast, as described in Table 4-36 of the Multisale EIS. Dispersants are not 

expected to be used in coastal waters. However, for offshore spills the dispersal of about 65 percent of 

the volume of a spill is attributed to the use of dispersants. No calculation has been made to estimate how 

much oil might be deposited on a beach if dispersants are not used. Unfavorable winds and currents 

would further diminish the volume of oil that might contact a beach. A persistent, northwesterly wind 

might preclude contact. As discussed in Chapter 4.5.3.1 of the Multisale EIS, the probability that tide 

levels could reach or exceed the elevations of sand dune vegetation on barrier beaches ranges from 0 to 16 

percent. This depends on the particular coastal setting and the elevation of the vegetation. The strong 

winds (like those found with strong tropical storms) that would be needed to produce unusually high tide 

levels would also disperse the slick over a larger area than is considered in the current analysis. With the 

cumulative effect of successive hurricanes continually lowering the barrier and dune elevations and 

creating erosion pathways in mainland beaches, the probability of beach oiling increases. The 

probabilities of spill occurrence and contact with barrier beaches and sand-dune vegetation are considered 

low unless winds are sufficient to elevate tides over the now reduced barrier island elevations. Hence, 

contact of sand-dune vegetation by spilled oil is not expected to occur except in extreme storm conditions. 

Furthermore, the Mississippi River discharge would help dissipate a slick that might otherwise contact 

Plaquemines Parish, Louisiana. The mixing and spreading would reduce the oil concentrations contacting 

the beach and vegetation, greatly reducing impacts on vegetation. 

Hurricanes and tropical storms will continue to erode and lower elevations of the barrier islands and 

to reduce their effectiveness as protection from inland oiling. While the probability of a catastrophic spill 

like the DWH event is low, it still has the potential to occur. As a result, some barrier islands could be 

oiled. Cleanup of these oiled islands and mainland beaches may involve utilizing heavy machinery that 

further impacts both beach and littoral habitats. Protective measures such as berm building (as discussed 

in the river channelization and beach protection section in this chapter) to prevent oiling may further 
4-58 Central Planning Area Supplemental EIS 

impact barrier islands through increasing compaction, altering currents, and removing sand supplies 

needed for natural barrier island formation. The barrier beaches of Deltaic Louisiana have the greatest 

rates of erosion and landward retreat of any known in the western hemisphere, and among the greatest 

rates on earth. Long-term impacts to contacted beaches from these spills could occur if significant 

volumes of sand were removed during cleanup operations. Removing sand from the coastal littoral 

environment, particularly in the sand-starved transgressive setting of coastal Louisiana, could result in 

accelerated coastal erosion. Spill cleanup is difficult in the inaccessible setting of coastal Louisiana. This 

analysis assumes that Louisiana would require the responsible party to clean the beach without removing 

significant volumes of sand or to replace the sand removed. Hence, cleanup operations are not expected 

to cause permanent effects on barrier beach stability. Within a few months, adjustments in beach 

configuration may result from the disturbance and movement of sand during cleanup. Mechanized 

cleanup was used in Alabama and Florida to remove tarballs from recreational beaches. While sand was 

not removed, but sifted in place to remove tarballs, scientists acknowledge that until long-term monitoring 

results have been analyzed, it is too soon to determine if there will be long-term effects on specific 

organisms that live in the interstitial sands of the beach face. 

The results of an investigation on the effects of the disposal of oiled sand on dune vegetation in Texas 

showed no deleterious impacts on existing vegetation or colonization of the sand by new vegetation 

(Webb, 1988). Hence, projected oil contacts to small areas of lower elevation sand dunes are not 

expected to result in destabilization of the sand dune area or the barrier landform. 

Some oil will penetrate to depths beneath the reach of the cleanup methods. The remaining oil would 

persist in beach sands, periodically being released when storms and high tides resuspend or flush through 

beach sediments. During hot, sunny days, tarballs buried near the surface of the beach sand may liquefy 

and cause a seep to the sand surface. The long-term stressors, including physical effects and the chemical 

toxicity of hydrocarbons, may lead to decreased primary production, plant dieback, and further erosion 

(Ko and Day, 2004b). 

The cumulative effect of aging infrastructure has the potential for increasing spills from older 

pipelines, platforms, and refineries. Older pipelines either cannot or are not as easily monitored for 

potential problems or failures as the newer pipelines. The newer pipelines are manufactured to a more 

stringent safety standard and are constructed so that they may be easily inspected by instruments or 

manually. Spills are more likely to result from the older facilities especially during storm conditions 

because of the age of the pipeline or structure and the lack newer superstructure designed to withstand 

major storms. 

As more improperly abandoned and marked shallow-water wells are removed from production, the 

potential for spills through vessel contact and leaks may increase. Without closer monitoring and 

inspection by the states responsible for regulating State waters, the cumulative effect of the old 

improperly abandoned wells could potentially result in frequent spills in larger numbers over time. 

Recreational Use and Tourism 

Most barrier beaches in the CPA are relatively inaccessible for regular recreational use because they 

are either located a substantial distance offshore as in Mississippi or are in coastal areas with limited road 

access as in Louisiana. Few beaches in the CPA have been, or are likely to be, substantially altered to 

accommodate recreational or industrial construction projects in the near future. 

Most barrier beaches in Alabama and Florida are accessible to people for recreational use because of 

road access, and their use is encouraged. Recreational use of barrier beaches and dunes can have impacts 

on the stability of the landform. Vehicle and pedestrian traffic on sand dunes can stress and reduce the 

density of vegetation that binds the sediment and stabilizes the dune. Destabilized dunes are more easily 

eroded by winds waves and traffic. Recreational vehicles and even hikers have caused problems where 

road access is available and the beach is wide enough to support vehicle use as in Alabama, Florida, and a 

few places in Louisiana. Areas without road access have limited impacts by recreational vehicles. The 

CPA proposed action would not provide any additional access that would result in an additive cumulative 

impact to the barrier beaches and dunes. 

There will continue to be seaside real-estate development where road access is available. The 

protection of dunes, beaches, and coastal environments will be regulated through the Coastal Zone 

Management (CZM) program. This assures that projects are constructed consistent with the Federal CZM 
Description of the Environment and Impact Analysis 4-59 

guidelines in order to preserve the integrity of the coastal ecosystem. Due to the continued occurrence of 

hurricanes, aging infrastructure, and proximity of some of the beaches to the oil production platforms, the 

possibility still exists of oil spills reaching recreational and barrier beaches. The potential for damage 

from oil cleanup can be minimized through utilizing nonintrusive removal techniques should the spill 

reach the shore. 

Summary and Conclusion 

River channelization, sediment deprivation, tropical and extra-tropical storm activity, sea-level rise, 

and rapid submergence have resulted in severe and rapid erosion of most of the barrier and shoreline 

landforms along the Louisiana coast. The barrier system of coastal Mississippi and Alabama are also 

supported on a coastal barrier platform of sand. Beach stabilization projects are considered by coastal 

geomorphologists and engineers to accelerate coastal erosion. Beneficial use of maintenance dredged 

materials and other restoration techniques could be required to mitigate some of these impacts. 

The impacts of oil spills from both OCS and non-OCS sources to the sand-starved Louisiana coast 

should not result in long-term alteration of landforms, provided the beaches are cleaned using techniques 

that do not significantly remove sand from the beach or dunes. The barrier beaches of deltaic Louisiana, 

the Chenier Plain, and the region around Galveston have the greatest risks of sustaining impacts from oilspill landfalls because of the high concentrations of oil production near those coasts. However, the 

majority of inshore spills are assumed to be small in scale (5 bbl; Table 4-13 of the Multisale EIS) and 

short in duration; therefore, impacts would be minor. Oil from most offshore spills is assumed to be 

weathered and dissipated by the time it would contact coastal beaches. The cleanup impacts of these 

spills could result in short-term (up to 2 years) adjustment in beach profiles and configurations as a result 

of sand removal and disturbance during the cleanup operations. Some contact to lower areas of sand 

dunes is expected. These contacts would not result in significant destabilization of the dunes. All 

cleanup efforts would be monitored to ensure the least amount of disturbance to the areas. The long-term 

stressors to barrier beach communities caused by the physical effects and chemical toxicity of an oil spill 

may lead to decreased primary production, plant dieback, and further erosion. 

Under the cumulative scenario, new OCS-related and non-OCS pipeline landfalls are projected. 

These pipelines are expected to be installed using modern techniques, which cause little to no impacts to 

the barrier islands and beaches. Existing pipelines, in particular those that are parallel and landward of 

beaches, that were placed on barrier islands using older techniques and that left canals or shore protection 

structures have caused and will continue to cause barrier beaches to narrow and breach. Aging pipelines 

and infrastructure continue to be problematic, and the potential for spills could exist until they are 

replaced. Improperly abandoned wells can also have a potential to create spills, especially in the shallow 

State waters. 

Recreational use of many barrier beaches in the western Gulf is intense due to their accessibility by 

road; however, because of the inaccessibility of most of the central Gulf barrier coast to humans, 

recreational use is not expected to result in significant impacts to most beaches. In conclusion, coastal 

barrier beaches have experienced severe adverse cumulative impacts from natural processes and human 

activities. Natural processes are generally considered the major contributor to these impacts, whereas 

human activities cause both severe local impacts and the acceleration of natural processes that deteriorate 

coastal barriers. Human activities that have caused the greatest adverse impacts are river channelization 

and damming, pipeline canals, navigation channel stabilization and maintenance, and beach stabilization 

structures. Deterioration of Gulf barrier beaches is expected to continue in the future. Federal, State 

(Louisiana), and parish governments have made efforts over the last 10 years to slow the landward retreat 

of Louisiana’s Gulf shorelines. 

The CPA proposed action is not expected to adversely alter barrier beach configurations significantly 

beyond existing, ongoing impacts in localized areas downdrift of artificially jettied and maintained 

channels. The proposed action may extend the life and presence of facilities in eroding areas, which 

would accelerate erosion in those areas. Strategic placement of dredged material from channel 

maintenance, channel deepening, and related actions could mitigate adverse impacts upon those localized 

areas. The proposed action is not expected to increase the probabilities of oil spills beyond the current 

estimates. Thus, the incremental contribution of the CPA proposed action to the cumulative impacts on 

coastal barrier beaches and associated dunes is expected to be small. 
4-60 Central Planning Area Supplemental EIS 

4.1.1.4. Wetlands 

The BOEMRE has reexamined the analysis for wetlands presented in the Multisale EIS and the 2009-

2012 Supplemental EIS (addition of 181 South Area), based on the additional information presented 

below and in consideration of the DWH event. No substantial new information was found that would 

alter the impact conclusion for wetlands presented in the Multisale EIS or the 2009-2012 Supplemental 

EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information and in consideration of the DWH event is presented in the following sections. A brief 

summary of potential impacts follows. Effects to coastal wetlands from the primary impact-producing 

activities associated with the CPA proposed action are expected to be low. The primary impactproducing activities associated with routine activities for the proposed action that could affect wetlands 

include pipeline emplacement, construction and maintenance, navigational channel use (vessel traffic) 

and maintenance, disposal of OCS-related wastes, and use and construction of support infrastructure in 

these coastal areas. Vessel traffic associated with the proposed action is expected to contribute minimally 

to the erosion and widening of navigation channels and canals. Deltaic Louisiana is expected to continue 

to experience the greatest loss of wetland habitat. Wetland loss is also expected to continue in coastal 

Texas, Mississippi, Alabama, and Florida, but at slower rates. The incremental contribution of the 

proposed action to the cumulative impacts on coastal wetlands is expected to be very small. 

Routine activities in the CPA such as pipeline emplacement, navigational channel use, maintenance 

dredging, disposal of OCS wastes, and construction and maintenance of OCS support infrastructure in 

coastal areas are expected to result in low impacts. Indirect impacts from wake erosion and saltwater 

intrusion are expected to result in low impacts, which are indistinguishable from direct impacts from 

inshore activities. The potential impacts from accidental events, primarily oil spills, are anticipated to be 

minimal. The incremental contribution of the proposed action’s impacts to the cumulative impacts to 

wetlands is small and expected to be negligible. 

4.1.1.4.1. Description of the Affected Environment 

A detailed description of various wetland types, processes, functions, and importance can be found in 

Chapter 3.2.1.2 of the Multisale EIS and in Chapter 4.1.3.2.1 of the Supplemental EIS. The following 

information is a summary of the resource description incorporated from the Multisale EIS, the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

The description of the wetlands resources that follows includes the historical types and location of the 

various wetland resources, the existing condition of these resources after several years of unprecedented 

hurricane activity, and possible effects from exposure of these resources to oil (based on current publicly 

available data) from the DWH event. 

In general, coastal wetland habitats occur as bands around waterways. They are broad expanses of 

saline, brackish, and freshwater marshes; mud and sand flats; forested wetlands that consist of cypresstupelo swamps; and mangrove and bottomland hardwood forests. Saline and brackish habitats support 

sharply delineated and segregated stands of single plant species. Fresh and low-salinity environments 

support more diverse and mixed communities of plants. High organic productivity and efficient nutrient 

recycling are characteristic of coastal wetlands. These wetland corridors also function as floodwater 

retention and purification areas as well as sites for local aquifer recharge. They provide habitats for a 

great number and wide diversity of resident plants, invertebrates, fishes, reptiles, birds, and mammals. 

Marsh environments are also important nursery grounds for many economically important fishes and 

shellfish juveniles. The marsh edge, where marsh and open water meet, is particularly important for its 

higher productivity and greater concentration of organisms. Emergent plants produce the bulk of the 

energy that supports salt-marsh dependent animals. 

General Existing Condition of Louisiana Coastal Wetlands 

According to the U.S. Department of the Interior, during the mid-1980’s, 28 percent of Louisiana 

(3,557,520 ha; 8.790.823 ac) was considered wetlands (Dahl, 1990; Henfer et al., 1994). Wetland loss 
Description of the Environment and Impact Analysis 4-61 

rates in coastal Louisiana are well documented to have been as high as 10,878 ha/yr (42 mi2/yr) during the 

late 1960’s. Studies have shown that the landloss rate in coastal Louisiana for the period 1972-1990 

slowed to an estimated 6,475 ha/yr (25 mi2

/yr) (Louisiana Coastal Wetlands Conservation and Restoration 

Task Force, 1993). Over the next 50 years, Louisiana is projected to lose almost 17 mi2

/yr (4,403 ha) of 

coastline due to storms, sea-level rise, and land subsidence (Government Accountability Office, 2007). A 

recent evaluation of landloss rates suggests that landloss is not occurring as rapidly as previously 

estimated and that it has been relatively stable from the 1970’s through 2004 (Barras et al., 2008). Barras 

et al. (2008) states that, during 1985-2004, the majority of the coastal landloss occurred on the Deltaic 

Plain at a rate of 3,885-4,144 ha/yr (15-16 mi2

/yr). For the same period, the Marginal Deltaic Plain 

showed a slight increase in land at a rate of 155 ha/yr (0.6 mi2

/yr) as a result of the growth of the 

Atchafalaya River and Wax Lake Delta Complexes. However, the Chenier Plain loss rate remained fairly 

stable at 518 ha/yr (2 mi2

/yr). The overall rate of coastal landloss between 1985 and 2004 was 

approximately 3,108 ha/yr (12 mi2

/yr). Annual rates of coastal landloss for 1985-2006 increased from 

777 ha/yr (3 mi2

/yr) to 3,885 ha/yr (15 mi2/yr), relative to the 1985-2004 trends. This 777 ha/yr (3 mi2/yr) 

increase reflects the hurricane-induced acceleration of landloss. To demonstrate the effects of Hurricanes 

Katrina and Rita, the study also analyzed the loss rates between 2004 and 2006. During this period, open 

water (indicates landloss) increased coastwide by 51,282 ha (198 mi2

), the equivalent of 70 percent of the 

cumulative loss from 1978 to 2004. Hurricanes Katrina and Rita increased open water in coastal 

Louisiana by 56,720 ha (219 mi2

) between 2004 and 2005. However, between 2005 and 2006 recovery 

increased the land base by 5,439 ha (21 mi2

) in a short period of time. The land gain between 2005 and 

2006 is equal to approximately 10 percent of the landloss (56,203 ha; 217 mi2

) estimated for 2004-2005 

(Barras, 2006). 

On April 20, 2010, the DWH event resulted in the largest oil spill in the history of the U.S. The oil 

continued to flow for 87 days before the well was capped. It is estimated that a total of about 4.9 million 

bbl were spilled into the GOM. This spill initially oiled shorelines along the Louisiana coast from 

extreme western Louisiana to portions of the Mississippi coast. Most of the Louisiana coast was exposed 

to some degree of oiling ranging from light to heavy, and the oil has degraded the quality of certain areas 

of wetland habitat. The information provided in this Supplemental EIS is from the best publicly available 

information that could be acquired outside of the NRDA process. With regards to the DWH event, the 

data from the SCAT observations, as compiled in the Unified Command Daily Report for October 12, 

2010, indicated that, as of that date, 88.8 mi (142.9 km) of Louisiana were heavily oiled and 203.1 mi 

(326.9 km) of shoreline had light to traces of oil observed. 

Chenier Plain 

The Chenier Plain formed between Port Bolivar, Texas, and Atchafalaya Bay in Louisiana as a result 

of storms and tidal currents reworking and depositing the sediments of the Mississippi River and its delta 

over the past several thousand years. As a result, few tidal passes are found along this coast as compared 

with eastern Louisiana. This reduction in the tidal passes reduces movement of saline waters. As the area 

filled in, a series of shell and sand ridges formed parallel or oblique to the present-day Gulf Coast, and 

these ridges were later abandoned as sea level continued to fall. Mudflats formed between the ridges 

when localized hydrologic and sedimentation patterns favored deposition (summarized from USDOI, GS, 

1998). This intermittent deposition isolated entrenched valleys from the Gulf, forming large lakes such as 

Sabine, Calcasieu, White, and Grand (Gosselink et al., 1979; Fisher et al., 1973). The eastern Chenier 

Plain that comprises the Calcasieu/Sabine Basin in Cameron and Calcasieu Parishes (southwest 

Louisiana) is approximately 630,000 ac (254,952 ha). This Basin contains about 312,500 ac (126,464 ha) 

of wetlands consisting of 32,800 ac (13, 274 ha) of fresh marsh, 112,000 ac (45,325 ha) of intermediate 

marsh, 158,200 ac (64,021 ha) of brackish marsh, and 9,500 ac (3,845 ha) of saline marsh (LaCoast.gov, 

2010c). A total of 122,000 ac (49,373 ha) (28%) has been lost since 1932. Calcasieu and Sabine Lakes 

are the major waterbodies within the basin, and freshwater inflow to the basin occurs primarily through 

these lakes via the Calcasieu and Sabine Rivers. Marshes within the basin historically drained into these 

two large lakes. The Chenier Plain supports an extensive marshland interspersed with large inland lakes 

formed in river valleys that were drowned after the last glaciation (Mac et al., 1998). Brackish and 

intermediate salinity marshes are dominant in the estuarine areas of the Chenier Plain. They are tidal with 

wind-driven tides being more influential, and they occasionally inundate these areas. Since salinity in this 
4-62 Central Planning Area Supplemental EIS 

area ranges broadly, these habitats support a mix of marine and salt-tolerant freshwater plants with marshhay cordgrass (Spartina patens) generally dominant. These habitats are the most extensive and 

productive in coastal Louisiana. 

Plant communities of freshwater marshes are among the most diverse of sensitive coastal 

environments. Annuals have a much greater presence in freshwater marshes than in estuarine areas. 

Dominance changes from season to season as a result of year-round, seed-germination schedules. 

Freshwater wetlands are extensive in the Chenier Plain due to the abundant rainfall and runoff, coupled 

with a ridge system that retains freshwater and restricts the inflow of saline waters. Tidal influences are 

minimal in these areas, although strong storms may inundate the area. This could either raise the salinity 

from seawater coming in or lower the salinity with increased precipitation. Depending on the species, this 

could case salinity and flooding stress. Detritus is not as readily exported and accumulates in the Plain, 

and it supports additional plant growth. Freshwater marsh plants are generally more buoyant than 

estuarine plants. In areas where detritus is thick, marsh plants may form floating marshes (flotants). 

Flotants occur in very low-energy environments. They are held together by surrounding shorelines and a 

weave of slowly deteriorating plant materials and living roots. Forested wetlands only occur in the flood 

plain regions of major streams, along the northern margin of the Chenier Plain. There, cypress-tupelo 

swamps grade through stands of black willow to bottomland hardwoods (LaCoast.gov, 2010c). 

Subsidence and sea-level rise are natural processes that contribute to wetland deterioration, but under 

pristine conditions, marsh building and maintenance processes can maintain the coastal marshes through 

normal subsidence and sea-level rise. The combination of subsidence and sea-level rise in the 

Calcasieu/Sabine Basin is approximately 0.25 in/yr (6 mm/yr) (LaCoast.gov, 2010c). However, due to 

manmade alterations to the basin hydrology, the natural wetland-building process no longer occurs at its 

historic rate. These factors, in combination with tropical storms, continue to deteriorate the Chenier 

Plain. In the Sabine Basin the natural wetland-building processes no longer occur, but natural marsh 

maintenance processes can be fairly effective at keeping wetland loss rates low. As noted in the section 

above (“General Existing Conditions of Louisiana Coastal Wetlands”), the Chenier Plain loss rate 

remained fairly stable at 518 ha/yr (2 mi2

/yr) between 1985 and 2004, while other areas of coastal 

Louisiana deteriorated rapidly (Barras et al., 2008). 

The Louisiana coast was impacted by a series of successive Category 3 and 5 hurricanes between 

2005 and 2008. The Chenier Plain was subjected to extreme flooding and erosion along the coastal 

beaches and marshes. While it is too early to quantify the damages incurred to the existing resource, 

further discussion of the storms’ effects are discussed in the “Hurricanes” section below. In addition to 

these natural effects, the coastline and the adjacent wetlands were exposed to oil from the DWH event, 

which occurred off the Louisiana coast in April 2010. 

Mississippi River Delta Complex 

The Mississippi River Delta Complex forms a plain that is composed of a series of overlapping 

riverine deltas that have extended onto the continental shelf over the past 6,000 years. Wetlands on this 

deltaic plain are the most extensive of those within the northern Gulf of Mexico. Sparse stands of black 

mangrove are found in the highest salinity areas of the Barataria and Terrebonne Basins. Extensive salt 

and brackish marshes are found throughout the southern half of the plain and east of the Mississippi 

River. Farther inland, extensive intermediate and freshwater marshes occur. East of the Mississippi 

River and south of Lake Pontchartrain, Louisiana, very few intermediate and freshwater wetlands 

occurred until the Caernarvon Freshwater Diversion was intermittently put into action in 1993. In 

freshwater areas, cypress-tupelo swamps are found flanking the natural levees and in areas that are 

impounded by dredged materials, levees, or roads. Bottomland hardwoods are on the numerous natural 

levees and in drained levee areas (USDOI, MMS, 2007b). 

Except for leveed areas and the delta and basin of the Atchafalaya River, all of the Mississippi River 

deltas are generally experiencing succession towards wetter terrestrial and deeper water habitats. This is 

due to deltaic abandonment and human actions and their ensuing erosion. Most of these wetlands are 

built upon highly organic soils that are easily eroded, compacted, and oxidized. There are two active 

deltas in this area. The more active is in Atchafalaya Bay at the mouths of the Atchafalaya River and its 

distributary, Wax Lake Outlet. Because the Red River and approximately 30 percent of the Mississippi 

River have been diverted to the Atchafalaya River, large volumes of sediment are being delivered to the 
Description of the Environment and Impact Analysis 4-63 

shallow bay. As a result, extensive freshwater marshes, swamps, and bottomland hardwood forests are 

found in this river basin, and relatively few estuarine marshes. 

The less active delta is at the mouth of the Mississippi River, which is referred to as the Belize or 

Birdfoot Delta. The Mississippi River has been channelized through most of this delta. This 

channelization greatly reduced the volume of sediments that the River contributes to its delta and the 

longshore currents near the mouths of its distributaries. A few manmade diversions have been installed 

and others are in the planning stage. Diversions are designed to deliver water rather than sediments to 

this delta. However, through the Louisiana Coastal Wetlands Planning, Protection and Restoration Act 

Program (LaCoast.gov, 2010a), projects are being either planned or designed to provide not only 

additional freshwater diversions but also sediment delivery projects that are intended to assist in creating 

and restoring marshes in the Mississippi Deltaic Plain (LaCoast.gov, 2010b). Some of these projects 

include manmade crevasses in the Mississippi River levee. Examples are the Delta Wide Crevasse 

project, which is intended to create marsh; Mississippi Channel Armor Gap and West Bay projects. which 

are designed as sediment and water diversions; and Barneys Bay Diversion, which is intended to provide 

water and sediment to the disappearing marsh zones (LaCoast.gov, 2010b). The State of Louisiana is also 

utilizing dustpan dredges in these areas for deposition of sediment to these sediment-starved areas of the 

coast. Smaller shoreline regressions also occur as a result of jetties located on the eastern end of Grand 

Isle, the western end of Caminada-Moreau Beach, the Empire Navigational Canal, and elsewhere. 

Most dune zones of the Mississippi River Delta contain low, single-line dune ridges that may be 

sparsely to heavily vegetated. Generally, in this area the vegetation on dune ridges gets denser as the time 

between storms increases. The shorefaces of the Mississippi River Delta Complex generally slope very 

gently seaward, which reduces wave energies at the shorelines. Mud flats are exposed during very low 

tidal events. The slope here is not as shallow as that found off the Chenier Plain. The steepest shoreface 

of the delta is found at the Caminada-Moreau Coast, where the greatest rates of erosion are seen. At this 

site, the longshore currents split to the east and west, which removes sand from the area without 

replenishment (Wolfe et al., 1988; Wetherell, 1992; Holder and Lugo-Fernandez, 1993). 

Unfortunately, the past decade has seen an increase in tropical storm activity for the project area. 

Hurricane Katrina (August 2005) caused severe erosion and landloss for the coastal barrier islands of the 

Deltaic Plain. Currently, the intense hurricane activity in the Gulf over the past 6 years has accelerated 

either wetland loss or changes in composition or pattern of wetland vegetation in the area. This has 

occurred with the help of both manmade and storm-induced changes in hydrology (Steyer et al., 2008), 

which have resulted in salinity changes and the removal of protected headlands or beaches. Further 

discussion of changes in the delta hydrology and damages to wetlands from Hurricanes Katrina, Rita, Ike, 

and Gustav are discussed under the “Hurricanes” section below. 

Aside from the effects of these tropical storms, the Mississippi River Delta Complex and the majority 

of the Louisiana coast was exposed to some degree of oiling. More information on areas of shoreline 

exposed to oil from the DWH event is included below in this chapter. These shoreline numbers reflect 

conditions as of the Unified Command Report date of October 12, 2010 (U.S. Dept. of Homeland 

Security, CG, 2010d), and are not necessarily indicative of past conditions of oiling. Some areas may 

have been either lightly or heavily oiled in the past, but these details will not be known until after the 

NRDA is completed and data are publicly available. The marshes and shorelines in the Birdfoot Delta 

portion of the Mississippi Delta Complex had the earliest and most severe exposure to shoreline oiling. 

Based on publicly available data from the FWS’s SCAT on September 27, 2010, (USDOI, FWS, 2010a), 

approximately 98 mi (158 km) of shoreline were noted as moderate to heavily oiled and included areas 

within and around the Mississippi Delta, Barataria Bay, Terrebonne Bay, and Bay Jimmy. At this point in 

time, it can only be said that these coastlines and the adjacent barrier islands have had some degree of 

exposure to oil. This oil has either been treated and/or weathered but we do not have available data to 

indicate the toxicity, quantity, or spatial extent of the shoreward exposure. This information should be 

forthcoming and made public as the NRDA Team completes the assessment process. 

Mississippi and Alabama 

According to DOI, during the mid-1980’s, 14 percent of Mississippi and 8 percent of Alabama were 

considered wetlands (Dahl, 1990; Henfer et al., 1994). Historically, vegetated coastal wetlands along the 

Mississippi coast included salt and brackish marshes, tidal freshwater marshes and swamps, and 
4-64 Central Planning Area Supplemental EIS 

submerged aquatic vegetation beds. Between 1930 and 1973, approximately 8,170 ac (3,308 ha) of 

coastal marshes were filled for industrial and residential uses. It was estimated in 1973 that Mississippi 

contained over 66,108 ac (26,764 ha) of salt marshes and approximately 823 ac (33 ha) of freshwater 

marshes (Mississippi Dept. of Marine Resources, 1999). Today, Mississippi has approximately a total of 

72,000 ac (113 mi2

) of designated crucial coastal wetland habitat (Mississippi Dept. of Marine Resources, 

2006). Estuarine wetlands are the second most common wetlands in Mississippi and include coastal, 

estuarine, and fresh marshes; mud flats; and cypress-tupelo gum swamp (estuarine forested wetlands). 

The estuarine marshes around Mississippi Sound and associated bays occur in discontinuous bands. The 

most extensive wetland areas in Mississippi occur in the eastern Pearl River delta near the 

Louisiana/Mississippi border and in the Pascagoula River delta area near the Mississippi/Alabama border. 

Mississippi’s wetlands seem to be more stable than those in Louisiana and Alabama, perhaps reflecting 

the more stable substrate, active and less disrupted sedimentation patterns, and occurrence of only minor 

canal dredging and development. Urban and suburban growths are suggested as the greatest contributors 

to direct coastal wetland loss in Mississippi and Alabama. 

The Gulf Coast of Alabama extends the length of the state, a distance of only 74 km (46 mi) 

(Alabama Coastal Area Board, 1980). The coastline includes the estuaries and inlets that cover a greater 

distance of 977 km (607 mi) (USDOC, NOAA, 1997). Two large drainage basins empty into the northern 

Gulf of Mexico within coastal Alabama; they are the Perdido River Basin and the Mobile River Basin. 

The Perdido Basin encompasses 3,238 km2

 (1,250 mi2) of Alabama and Florida (Sturm et al., 2007). The 

Mobile Basin is the sixth largest drainage area and the fourth largest river basin in terms of flow volume 

in the United States. The 111,370-km2 (43,000-mi2

) Mobile Basin encompasses parts of Tennessee, 

Georgia, Mississippi, and Alabama (Isphording and Flowers, 1990; Johnson et al., 2002). 

The coastal lowlands of Alabama, with gently undulating to flat topography, basically follow the 

shoreline along the Gulf of Mexico and Mobile, Perdido, and Bon Secour Bays (Sapp and Emplaincourt, 

1975). The ecological environments and geomorphology consist of features such as wetlands (e.g., tidal 

marsh), two large peninsulas, a delta, lagoons, islands, and bays. The presence of a high water table with 

a range of salinities gives rise to the abundance of various wetland habitat types that are found within 

Alabama’s coastal area. The largest bays of coastal Alabama stated in size order include Mobile Bay, 

Perdido Bay, and Bon Secour Bay. The largest of these is Mobile Bay and it was formed within a 

submerged river valley (Chermock, 1974). Some of Perdido Bay is in Florida and contains areas 

populated by seagrasses. The Mississippi Sound estuary, located behind the offshore barrier islands, 

extends from southwestern Mobile Bay and borders the entire southern Mobile County and Mississippi 

coastlines. The Mobile, Tensaw, and Blakeley Rivers flow southward to Mobile Bay through the MobileTensaw Delta. The alluvial-deltaic plain is located at the terminus of Mobile Bay to northward along the 

Mobile-Baldwin County line. Topographically, the Mobile-Tensaw Delta is flat and generally below 6 m 

(20 ft) in elevation. Additionally, other major coastal tributaries include Dog and East Fowl Rivers on the 

western side of Mobile Bay and the Blakeley, Fish, Magnolia, and Bon Secour Rivers on the eastern side 

of the Bay. West Fowl and Escatawpa Rivers discharge into Mississippi Sound, and the Perdido and 

Blackwater Rivers are located at the northern end of Perdido Bay. Alabama has approximately 118,000 

ac (184 mi2

) of coastal wetlands, of which approximately 75,000 ac (117 mi2) are forested; 4,400 ac 

(9 mi2

) are freshwater marsh; and 35,400 ac (55 mi2) are estuarine marsh (Wallace, 1996). Most coastal 

wetlands in Alabama occur on the Mobile River Delta or along the northern Mississippi Sound. 

Both Mississippi and Alabama have estuarine intertidal emergent habitats that include salt marsh, as 

well as intertidal forested shrub that can include mangroves and other salt tolerant shrubs. The 

embayments and shallow-water environments in these coastal waters also have estuarine aquatic beds that 

may include submergent or floating vegetation (Swann, 2010). Mississippi had a loss with the original 10 

million acres of marshes in the 1780’s dwindling to approximately 4 million acres by the 1900’s 

representing a 59 percent loss (Dahl, 1990). Coastal Mississippi is predominantly salt marsh habitat with 

very little fresh marsh. The observed loss rates is coastal Mississippi reflect this discrepancy in habitat 

with losses of 64,000 acres of salt marsh and only 800 acres of fresh marsh (Swann, 2010). In Alabama 

approximately 15,000 acres of salt marsh was lost as opposed to 11,000 acres of fresh marsh. Based on 

historical records Alabama had approximately 7.6 million acres of marsh in the 1780’s and by the 1980’s 

was left with 3.6 million acres representing a 50 percent loss in marsh acreage. The existing conditions 

associated with channel maintenance (dredging and filling), bank armoring, vessel wakes, propeller wash, 

coastal development, subsidence, and sea level rise will continue as part of sources aggravating the loss of 
Description of the Environment and Impact Analysis 4-65 

coastal marshes. Federal and State coastal initiatives (e.g., CIAP and CWPPRA) are either ongoing or 

being expanded to restore, protect, or construct wetlands and further prevent coastal wetland loss. Overall 

coastal wetlands in these areas have been greatly reduced approximately 50 percent of historical values. 

The sparse data available since the 1980’s suggest that losses have slowed (Swann, 2010). Another 

important factor in wetland loss over the past 6 years has been the extremely active hurricane season. 

These natural forces, along with the currently unknown long-term effects of the DWH event, may further 

affect the sustainability of these coastal marshes. There were 9 and 81 mi (14 and 130 km), respectively, 

of shoreline in Mississippi exposed to either heavy or light shoreline oilings. The SCAT observations are 

not indicating any moderate to heavy oil exposure along the Alabama shoreline, but some light oiling was 

noted along 60 mi (97 km) of shoreline. Florida had no heavily oiled shoreline as of the October report 

date, but 114 mi (183 km) of light to traces of oil were found along the Alabama shoreline. At this point 

in time it can only be said that these coastlines and the adjacent barrier islands have had some degree of 

exposure to oil, which has either been treated or weathered; however, we do not have available data to 

indicate toxicity, quantity, or spatial extent of the shoreward exposure. This information should be 

forthcoming and made public as the NRDA Team completes the assessment process. 

Hurricanes 

The intensity and frequency of hurricanes in the Gulf over the last 6 years has greatly impacted the 

system of protective barrier islands, beaches, and dunes and associated wetlands along the Gulf Coast. 

Within the last 6 years, the Gulf Coast of Texas, Louisiana, Mississippi, Alabama, and to some degree 

Florida have experienced five major hurricanes (Ivan, Katrina, Rita, Gustav, and Ike). As a result of 

losing dune and barrier island elevations, as well as associated marshes and backshore and foreshore 

wetlands, the inland coasts and wetlands are more vulnerable to future hurricanes and wind-driven tidal or 

storm events. 

The post-storm (Hurricanes Katrina and Rita) estimates of land change made by USGS (Barras, 2006) 

indicated that there was an increase of 217 mi2

 (562 km2) of open water following the storm. Based on 

the analysis of the latest satellite imagery (Barras, 2007b), approximately 82 mi2

 (212 km2) of new openwater locations were in areas primarily impacted by Hurricane Katrina (e.g., Mississippi River Delta 

Basin, Breton Sound Basin, Pontchartrain Basin, and Pearl River Basin), whereas 99 mi2

 (256 km2) were 

in areas primarily impacted by Hurricane Rita (e.g., Calcasieu/Sabine Basin, Mermentau Basin, 

Teche/Vermilion Basin, Atchafalaya Basin, and Terrebonne Basin). The Barataria Basin contained openwater locations caused by both Hurricanes Katrina and Rita, resulting in some 18 mi2

 (46.6 km2) of open 

water. The fresh and intermediate marsh land decreased by 122 mi2

 (316 km2) and 90 mi2 (233.1 km2), 

respectively. The brackish and saline marsh land decreased by 33 mi2

 (85.5 km2) and 28 mi2 (72.5 km2), 

respectively. Based on current observational flights by USGS, wetland recovery 6 years after Hurricane 

Katrina is noted as slow (Israel, 2010,), with open water remaining where viable marshes once existed. 

The marshlands east of the Mississippi Delta were the most severely affected. According to the USGS’s 

5-year, post-Katrina survey, the wetland loss from all four storms (i.e., Hurricanes Katrina, Rita, Gustav, 

and Ike) totaled 340 mi2

 (881 km2). Hurricanes Katrina and Rita alone destroyed 220 mi2 (570 km2) 

(Israel, 2010). 

Intense storms typically blow away all of the vegetation and soil from marsh, leaving behind a body 

of water. Hurricane Katrina was no exception, leaving scour holes where debris accelerated by the storm 

pushed the marsh away. Based on the depths of these scours, marsh type (i.e., fresh, intermediate, 

brackish, or saline), sediment supply, and drainage, possible recovery time is determined. However, it is 

too early to determine if long-term recovery is viable. Another factor that is now superimposed on the 

hurricane damage is the currently unknown, long-term effect of the oil spill from the DWH event. All of 

these factors must now be considered as part of the existing environment. 

4.1.1.4.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine impacts from the CPA proposed action to wetlands is given in 

Chapter 4.2.1.1.3.2 of the Multisale EIS and in Chapter 4.1.3.2.2 of the 2009-2012 Supplemental EIS. 
4-66 Central Planning Area Supplemental EIS 

The following is a summary of the information presented in the Multisale EIS, the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

This section considers impacts from routine activities associated with the CPA proposed action to 

coastal wetlands and marshes. The primary impact-producing activities associated with the proposed 

action that could affect wetlands and marshes include pipeline emplacement, construction, and 

maintenance; navigation channel use (vessel traffic) and maintenance dredging; disposal of OCS-related 

wastes; and use and construction of support infrastructure in these coastal areas. Other potential impacts 

that are indirectly associated with OCS oil and gas activities are wake erosion resulting from navigational 

traffic, levee construction that prevents necessary sedimentary processes, saltwater intrusion that changes 

the hydrology leading to unfavorable conditions for wetland vegetation, and vulnerability to storm 

damage from eroded wetlands. The following sections describe the sources and types of these potential 

impacts. In addition to the above effects, the DWH event oil spill presents other potential indirect effects 

as a result of disturbing remnant oil in the sediment. It is highly unlikely that the remnant oil is toxic due 

to weathering time, biological degradation, and dispersant treatment. Routine activities involving bottom 

disturbances (dredging, waste disposal, and trenching associated with pipeline placement) or sediment or 

water entrainment (shallow-water vessel traffic) could potentially resuspend or transport this bottom 

based oil. 

It was estimated in 2000 that coastal Louisiana would continue to lose land at a rate of approximately 

26 km2

/(10 mi2/) over the next 50 years. Further, it was estimated that an additional net loss of 1,326 km2

(512 mi2

) may occur by 2050, which is almost 10 percent of Louisiana’s remaining coastal wetlands 

(Barras et al., 2003). However, in 2005 Hurricanes Katrina and Rita caused 562 km2

 (217 mi2) of land 

change (primarily wetlands to open water) (Barras, 2006). Based on the analysis of the latest satellite 

imagery, approximately 212 km2

 (82 mi2) of additional open-water habitat was in areas primarily 

impacted by Hurricane Katrina (e.g., Mississippi River Delta Basin, Breton Sound Basin, Pontchartrain 

Basin, and Pearl River Basin) (Barras, 2007b and 2009). Also, 256 km2

 (99 mi2) of open-water habitat 

was in areas primarily impacted by Hurricane Rita (e.g., Calcasieu/Sabine Basin, Mermentau Basin, 

Teche/Vermilion Basin, Atchafalaya Basin, and Terrebonne Basin). Barataria Basin contained 

approximately 46.6 km2

 (18 mi2) of new open-water habitat caused by both hurricanes. These new openwater habitats represent landloss caused by the direct removal of wetlands. They may also indicate 

transitory changes of wetlands to open water caused by remnant flooding, removal of aquatic vegetation, 

scouring of marsh vegetation, and water-level variation attributed to normal tidal and meteorological 

variation between satellite images. An accurate evaluation of permanent loss of wetland areas is difficult 

until several growing seasons have been evaluated. The presence of strong tropical storms is a routine 

background condition in the Gulf that must be taken into consideration. Coastal change from storms in 

the area included both beach erosion and erosion of channels where water continues to flow seaward to 

the Gulf of Mexico (Doran et al., 2009). These eroded barriers that once protected the wetlands behind 

them were severely eroded by the storms. The cumulative effects of human and natural activities in the 

coastal area have severely degraded the deltaic processes and have shifted the coastal area from a 

condition of net land building to one of net landloss and are discussed in Chapter 4.1.1.4.4 (U.S. Dept. of 

the Army, COE, 2004a). 

Pipeline Emplacement 

As of July 2006, there was over 45,000 km (27,962 mi) of pipelines in Federal offshore lands. 

Approximately 15,400 km (9,569 mi) of OCS pipelines extend into State waters and onshore. For the 

CPA proposed action, there would be 130-2,075 km (81-1,289 mi) of installed pipelines (Table 3-2). 

Many OCS pipelines make landfall on Louisiana’s barrier island and wetland shorelines. Approximately 

8,000 km (4,971 mi) of OCS-related pipelines cross marsh and uplands (Johnston et al., 2009). Louisiana 

wetlands protect pipelines from waves and ensure that the lines stay buried and in place (Chapter 

3.1.2.3). Existing pipelines, especially those installed prior to the State of Louisiana Coastal Permit 

Program in 1981, have caused direct landloss averaging between 2.5 ha/(10 ac/) and 4.0 ha/(16 ac/) of 

linear pipeline (Bauman and Turner, 1990; Johnston et al., 2009). Bauman and Turner (1990) indicated 

that the widening of OCS pipeline canals does not appear to be an important factor for total net wetland 

loss in the coastal zone because few pipeline canals are open to navigation. 
Description of the Environment and Impact Analysis 4-67 

Since 2002, only one new pipeline has come to shore in Louisiana from OCS-related activities. In 

2003, the 30-in Endymion Oil Pipeline, which delivers crude oil from South Pass Block 89 to the LOOP 

storage facility near the Clovelly Oil and Gas Field, was installed. Based on a review of the data in the 

COE permit application (No. 20-020-1632), the emplacement of the pipeline caused zero (0) impacts to 

marshes (emergent wetlands) and beaches. This is because the operator used horizontal, directional 

(trenchless) drilling techniques to avoid damages to these sensitive habitats. Additionally, the pipeline 

route maximized an open-water route to the extent possible (a comprehensive description of current 

mitigation measures is discussed in Chapter 2.2.2). A comparison of aerial photos taken before and after 

Hurricanes Katrina and Rita reveal no observable landloss or impacts associated with the Endymion Oil 

Pipeline. Impacts to wetlands from routine activities associated with the proposed action are expected to 

be low and could be further reduced through mitigation. However, in areas where oiling of wetlands 

occurred from the DWH event, there is the potential for disturbing oiled sediment and vegetation. It is 

possible that any dredging or trenching associated with pipeline placement could result in the disturbance 

of oiled sediment and could potentially result in the spread of any associated contaminants to wetlands. 

Maintenance dredging of navigation channels and canals is expected to occur with minimal impacts 

except in areas that have been previously contaminated with oil; however, the proposed action is expected 

to contribute minimally to the need for this dredging. Alternative dredged material disposal methods can 

be used to enhance and create coastal wetlands after material has been tested for the presence of oil 

toxicity. Vessel traffic associated with the proposed action is expected to contribute minimally to the 

erosion and widening of navigation channels and canals. Secondary impacts to wetlands would be 

primarily from vessel traffic corridors and will continue to cause approximately 0.6 ha (1.5 ac) of landloss 

per year, regardless of the CPA proposed action. 

Dredging 

The COE’s New Orleans District annually removes approximately 69 million m3 (90 million yd3) of 

dredged material from 10 Federal navigational channels throughout coastal Louisiana. Approximately 

18 million m3

 (27 million yd3) or 25-35 percent of this material is used for coastal wetland restoration 

projects (Creef and Mathies, 2002). As a result of the tremendous wetlands landloss in the Louisiana 

coastal region, the beneficial use of dredge spoils is expected to increase. Executive Order 11990 (1977) 

requires that, where appropriate, material from maintenance dredging be considered for use as a sediment 

supplement in deteriorating wetland areas to enhance and increase wetland acreage. Given the COE‘s 

policy of beneficial use of dredge, increased emphasis has been placed on the use of dredged material for 

marsh creation. For the proposed action, increased use of dredged material to enhance wetland habitats is 

encouraged as mitigation. 

Dredging and dredged-material disposal can be detrimental to coastal wetlands and associated fish 

and wildlife that use these areas for nursery grounds, protection, etc. As a result of the DWH event, 

dredging may result in the resuspension and transport of oiled sediments in areas where oil is known to 

have once occurred. Maintenance dredging of navigation channels deposits material on existing disposal 

banks and areas. The effects of these disposal banks from the proposed action in the CPA on wetland 

drainage is expected to continue unchanged, except if there are some localized and minor exacerbation of 

existing problems. For example, some dredged material intended for placement on a dredged-material 

disposal bank is placed in adjacent wetlands or shallow water. Wetland loss due to dredge material 

deposition is expected to be offset by wetland creation as adjacent margins of shallow water are filled. In 

both cases, areas impacted are considered small. Maintenance dredging would also temporarily increase 

turbidity levels in the vicinities of the dredging and disposal of materials, which can impact emergent 

wetlands and submerged vegetation communities. 

Two different methods are generally used to dredge and transport sediments from channels to openwater sites: (1) a hydraulic cutterhead suction dredge transfers sediments via connecting pipelines or (2) a 

clamshell bucket dredge transfers sediments via towed bottom-release scows. Each method produces a 

distinctly different deposit. Hydraulic dredging creates a slurry of sediment and water, which is pumped 

through a pipeline to the dredged-material disposal site. Coarser sediment settles to the bottom where it 

spreads outward under the force of gravity, and finer sediments may remain in suspension longer. The 

clamshell dredge scoops sediments relatively intact into scows, which are then towed to the designated 
4-68 Central Planning Area Supplemental EIS 

area. The dredged sediments are released into the area specified for disposal. This method usually 

produces positive relief features in the placement area. 

Access canals, as well as pipeline canals, are commonly bordered by levees created using dredged 

materials (Rozas, 1992). Placement of this material alongside canals converts low-lying marsh to upland, 

an environment unavailable to aquatic organisms except during extreme high tides. Dredged material can 

also form a barrier, causing ponding behind levees and limiting circulation between canal waters and 

marshes to infrequent, high-water events (Swenson and Turner, 1987; Cox et al., 1997). This and similar 

disruptions to marsh hydrology are believed to change coastal habitat structure as well as accelerate 

marsh erosion and conversion to open water (Turner and Cahoon, 1988; Rozas, 1992; Turner et al., 1994; 

Kuhn et al., 1999). 

Navigation Channels and Vessel Traffic 

Vessel traffic that may support the proposed action is discussed in Chapter 4.1.1.8.4 of the Multisale 

EIS, in Chapter 3.1.1.4 of the 2009-2012 Supplemental EIS, and in Chapter 3.1.2 of this Supplemental 

EIS. Most navigation channels projected to be used to support the CPA proposed action are shallow and 

are currently used by vessels that support the OCS Program (Chapter 4.1.2.1.9 and Table 3-36 of the 

Multisale EIS). Approximately 3,200 km (1,988 mi) of OCS-related navigation canals, bayous, and rivers 

are found in the coastal regions around the Gulf. This is exclusive of channels through large bays, 

sounds, and lagoons. About 2,000 km (1,243 mi) support OCS-related activities in the CPA. No new 

navigation channels are expected as a result of the CPA proposed action. Deepwater activities are 

anticipated to increase, requiring use of larger service vessels for efficient operations. This may put a 

substantial emphasis on shore bases associated with deeper channels. Ports that have navigation channels 

deep enough to accommodate deeper-draft vessels may expand their infrastructure to accommodate 

deeper-draft vessels. An example of a significant expansion of a service base is Port Fourchon in coastal 

Louisiana. Port Fourchon has deepened the existing channel and has dredged additional new channels to 

facilitate this expansion. At present, the entrance to Port Fourchon (Belle Pass Channel) is maintained at 

9 m (29 ft). The inland channel in the port is 8 m (26 ft) and Bayou Lafourche is maintained at 7 m 

(24 ft). The Federal Emergency Management Agency (FEMA) has funded the dredging of several sites 

that were silted by Hurricanes Katrina and Rita. 

Waves generated by boats, ships, barges, and other vessels erode unprotected shorelines and 

accelerate erosion in areas already affected by natural erosion processes. Much of the service-vessel 

traffic that is a necessary component of OCS activities uses the channels and canals along the Louisiana 

coast. According to Johnson and Gosselink (1982), canal widening rates in coastal Louisiana range from 

about 2.58 m/(8.46 ft/) for canals with the greatest boat activity to 0.95 m/(3.12 ft/) for canals with 

minimal boat activity. This study found navigational use is responsible for an average of 1.5 m/yr (4.9 ft/

yr) of the canal widening. About 2,000 km (1,243 mi) of navigation channels support OCS-related 

activities in the CPA. Total navigational use results in about 300 ha (741 ac) of landloss per year. A 

USGS study by Johnston et al. (2009) found that canal widening rates have slowed rather than increased 

in recent years as a result of increased bank stabilization efforts. Thus, the canal widening rates 

established by Johnson and Gosselink (1982) are considered overestimates. The most heavily-used OCS 

navigation channel is the channel from Port Fourchon which is heavily armored and is less erodible. A 

recent BOEMRE- and USGS-funded study (Thatcher et al., 2011) is examining the susceptibility to 

erosion of navigation channels based on cover and substrate. During the study, the shorelines along both 

banks of navigation canals were mapped using aerial photography from 1978 to 1979, 1996 to 1997, and 

2005 to 2006. To measure shoreline changes, transects were generated. The erosion rates were 

quantified to determine whether differences in erosion rates are related to embankment substrate, 

vegetation type, geologic region, or soil type. The study found erosion rates were variable within and 

across unarmored portions of the navigation channels. Previous studies have found that canal erosion 

rates have slowed in recent years, and the results of this study support that conclusion. The rate of change 

differed significantly by geologic region and marsh vegetation type. However, when rates for all canals 

were combined for each time period, the average canal widening rate slowed to -0.99 m/yr (-3.25 ft/yr) 

for the 1996/1998-2005/2006 time period compared with -1.71 m/yr (-5.61 ft/yr) for the earlier 

1978/1979-1996/1998 time period. Therefore, this indicates there is a decrease in the rate of erosion for 

the area during that time period. 
Description of the Environment and Impact Analysis 4-69 

Disposal of OCS-Related Wastes 

Produced sands, oil-based or synthetic-based drilling muds and cuttings, along with fluids from well 

treatment work over and completion activities would be transported to shore for disposal. Sufficient 

disposal capacity exists at the disposal site near Lacassine, Louisiana, and at other disposal sites under 

development or projected for future development. Discharging OCS-related produced water into inshore 

waters has been discontinued, so all OCS-produced waters are discharged into offshore waters in 

accordance with NPDES permits or transported to shore for injection. Produced waters are not expected 

to affect coastal wetlands. Because of wetland protection regulations, no new waste disposal site would 

be developed in wetlands. Some seepage from waste sites into adjacent wetland areas may occur and may 

result in damage to wetland vegetation. State requirements are expected to be enforced to prevent and 

correct such occurrences. 

Onshore Facilities 

Various kinds of onshore facilities service OCS development. All projected new facilities that are 

attributed to the OCS Program and the CPA proposed action are described in Chapter 3.1.2. State and 

Federal permitting agencies discourage the placement of new facilities and the expansion of existing 

facilities in wetlands. Any impacts upon wetlands are mitigated.

Overview of Existing Mitigation Techniques and Results 

Numerous mitigation methods have been recommended and used in the field. Depending on the 

location, project, and surrounding environment, different mitigation techniques may be more appropriate 

over another. Based on permits, work documents, and interviews, 17 mitigation techniques have been 

implemented at least once with regards to the OCS. Because no one technique or suite of techniques are 

routinely required by permitting agencies, each pipeline mitigation process is uniquely designed to 

minimize damages given the particular setting and equipment to be installed. Of the identified mitigation 

techniques, there are a number of techniques that are commonly required. Some other mitigation 

techniques are rarely used because they are considered obsolete or because they are applicable only to a 

narrow range of settings. Table 4-42 of the Multisale EIS summarizes the recommended mitigating 

techniques to reduce or avoid adverse impact to wetlands from pipeline construction, canals, dredging, 

and dredged material placement. These mitigation methods are the most common applied by the 

permitting agencies (COE and the State in which the activity has or would occur) to minimize wetland 

impacts. The BOEMRE is not a permitting agency for onshore pipelines, canals, dredging, and dredged 

material placement. 

Proposed Action Analysis 

Zero to one pipeline landfalls that could result in up to 2 km (1.2 mi) onshore pipeline are projected 

as a result of the CPA proposed action. Should one be constructed, it would most likely be in Louisiana, 

where the large majority of infrastructure exists for receiving oil and gas from the CPA. Pipeline landfall 

may occur through or in the immediate vicinity of coastal wetlands and marshes. Wherever a landfall 

occurs, permitting/mitigating processes are in place to ensure wetland habitats are protected first through 

avoidance, then minimization of impacts, and finally compensation for unavoidable impacts to wetlands. 

The use of modern technologies, such as directional boring, greatly reduces and possibly eliminates 

impacts to coastal wetlands and marshes. About 5-8 ha (12-20 ac) of landloss for the projected 2 km 

(1.2 mi) of pipeline (based on historic loss rates) are expected from the CPA proposed action. This 

represents approximately 0.25 percent of the total landloss estimated to occur along the Louisiana coast in 

1 year (~2,590 ha or 10 mi2

) (Barras et al., 2003). This estimate does not take into account the present 

regulatory programs of COE and the Louisiana Dept. of Natural Resources, modern installation 

techniques, and “no net loss” policy that would result in zero to negligible impacts to wetland habitats. 

Therefore, effects on coastal wetlands and marshes from new pipeline laying activities associated with the 

CPA proposed action are expected to be minor or nonexistent. These impacts are considered to be 

negligible. For the proposed action, increased use of dredged material to enhance wetland habitats is 

encouraged as mitigation. 
4-70 Central Planning Area Supplemental EIS 

On average, 12 percent of traffic using OCS-related navigation channels is related to the OCS 

Program (Tables 3-36 and 4-4 of the Multisale EIS). Based on the numbers of service-vessel trips 

projected for the proposed action and the OCS Program (Table 3-2; and Table 4-6 of the Multisale EIS), 

the proposed action is expected to contribute 3-4 percent of the total OCS Program usage. So, the 

proposed action would contribute 0.4-0.5 percent to the total commercial traffic using these navigation 

channels. All estimated navigational use is expected to contribute approximately 1.5 m/(4.9 ft/) to the 

widening to the roughly 2,000 km (1,243 mi) of OCS-related navigation channels, or about 300 ha (741 

ac), of landloss per year. Twelve percent or 36 ha (89 ac) can be attributed to wake erosion from OCSrelated vessel traffic (note that several other factors including storms, tides, and subsidence also 

contribute to canal widening). Of the 3,600 ha (8,896 ac) attributed to total OCS-related wake erosion, 

about 1 ha (3 ac) of landloss per year would be attributed to the CPA proposed action. Therefore, impacts 

from vessel traffic related to the proposed action should remain minimal. Because of wetland protection 

regulations, no new waste disposal site would be developed in wetlands. Some seepage from waste sites 

into adjacent wetland areas may occur and result in damage to wetland vegetation. State requirements are 

expected to prevent and correct such occurrences. No effects to coastal wetlands from the disposal of 

OCS-related wastes associated with the CPA proposed action are expected. 

Summary and Conclusion 

The 0-2 km (0-1.2 mi) of onshore pipeline that could result from the proposed action would cause the 

loss of 0-8 ha (0-20 ac) of wetlands habitat. It is expected that these impacts would be reduced through 

mitigation, such as horizontal, directional (trenchless) drilling techniques to avoid damages to these 

sensitive wetland habitats. Although maintenance dredging of navigation channels and canals in the CPA 

is expected to occur, the proposed action is expected to contribute minimally to the need for this dredging. 

Alternative dredged-material disposal methods can be used to enhance and create wetlands. Secondary 

impacts to wetlands from the CPA proposed action would result from OCS-related vessel traffic 

contributing to the erosion and widening of navigation channels and canals. This would cause 

approximately 1 ha (3 ac) of landloss per year. Overall, the impacts to wetlands from routine activities 

associated with the CPA proposed action are expected to be low due to the small length of projected 

onshore pipelines, the minimal contribution to the need for maintenance dredging, and the mitigation 

measures that would be used to further reduce these impacts. 

4.1.1.4.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of the wetlands resource and accidental impacts from the CPA proposed action 

are given in Chapters 3.2.1.2 and 4.4.3.2 of the Multisale EIS and in Chapters 4.1.3.1.1 and 4.1.3.2.3 of 

the 2009-2012 Supplemental EIS. There is also a risk analysis of accidental events in Chapter 3.2.1 of 

this Supplemental EIS. The following is a summary of the information presented in the Multisale EIS, 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. The main impact-producing factors that would affect wetlands are oil spills. 

Since the preparation of the Multisale EIS and the 2009-2012 Supplemental EIS, the coastal wetlands, 

along with their protective barrier islands, have been heavily impacted by two intense hurricanes in 2008 

(Gustav and Ike). These already eroding, protective barrier islands were further reduced in mass and 

elevation. As a result, there have been losses in the protective landmass (Chandeleur Island) and 

elevations of the barrier islands, as well as the conversion of wetlands to open water through erosion, 

scour, and saltwater intrusion as noted in Barras et al. (2008). With the reduced protection of the barrier 

islands, there is a greater potential for the oiling of coastal wetlands. Both coastal and offshore oil spills 

can be caused by large tropical cyclone events such as Hurricanes Katrina, Rita, Gustav, and Ike. 

In addition to hurricane effects, areas of the Louisiana coast have been further stressed through 

shoreline oiling associated with the DWH event. While most of the Louisiana coastline received some 

degree of oiling, the most heavily oiled areas were around the Mississippi River Birdsfoot Delta, Pass a 

Loutre, and the Barataria Bay Estuary (Bayou Jimmy) due to their close proximity to the spill. 

Mississippi, Alabama, and eastern Florida also received varying amounts of oil from the DWH event, but 

generally less than the Louisiana coast. In most cases offshore spills, unless catastrophic in nature (e.g., 
Description of the Environment and Impact Analysis 4-71 

DWH event spill), are not expected to significantly damage any wetlands along the Gulf Coast. On 

July 27, 2010, an additional vessel collision with an abandoned wellhead within the Barataria Bay, 

Louisiana, resulted in a 16-km2

 (6-mi2) spill that was contained (U.S. Dept. of Homeland Security, CG, 

2010e). It must be noted that, even with offshore spills, the degree of coastal impact is a function of the 

source oil type (Macondo was a light oil), volume, and condition of the oil as it reaches shore, along with 

the season of the spill and the composition of the wetland plant community affected. 

Proposed Action Analysis 

Wetlands are generally more susceptible to contact by inshore spills, which have a low probability of 

occurrence from OCS-related activities. Inshore vessel collisions may release fuel and lubricant oils, and 

pipeline ruptures may release crude and condensate oil. An estimated 49-126 spills could occur in coastal 

waters from the CPA proposed action and its support operations over the 40-year life span (Table 3-7). 

Offshore oil spills are much less likely to contact these wetlands than are inshore spills because these 

areas are generally protected by barrier islands, peninsulas, sand spits, and currents. The probabilities of 

an offshore spill ≥1,000 bbl occurring and contacting environmental features are described in Chapter 

4.3.1.8 of the Multisale EIS. Eight parishes in Louisiana have a chance of spill contact. For these 

parishes, the chance of an OCS offshore spill ≥1,000 bbl occurring and reaching the shoreline ranges from 

1 to 15 percent as the result of the proposed action over its 40-year life. Plaquemines Parish has the 

largest probability (10-15%) of contact in the CPA. Weathering, wave action, and the use of offshore 

dispersants would reduce the amount of oil that would reach wetland areas and would result in minimal 

impacts. 

Primary Impacts of Oil Spills 

While there are concerns that offshore spills may contribute to wetland damage, the distance of these 

production facilities makes the probability of toxic oil to reach the coastal wetlands low. The toxicity of 

the spilled oil from offshore is greatly reduced or eliminated by weathering, wave action, and dispersants. 

The greatest threat to wetland habitat with regard to an oil spill is from an inland spill resulting from a 

vessel accident or pipeline rupture. These spills are a concern since they would be much closer to the 

wetland resource. While a resulting slick may cause some impacts to wetland habitat, the cleanup effort 

(equipment, chemicals, and personnel) can generate greater effects to the area. Associated foot traffic 

may work oil farther into the sediment than would otherwise occur. Close monitoring and restrictions on 

the use of bottom-disturbing equipment would be needed to avoid or minimize those impacts. Added 

concerns or factors that influence the effect of an oil spill to wetlands are the fate (frequency and 

weathering) and behavior of oil, air pollution, availability and adequacy of containment and cleanup 

technologies, and impacts of various oil-spill cleanup methods. 

Numerous investigators have studied the immediate impacts of oil spills on Gulf wetland habitats and 

other wetland habitats elsewhere similar to those affected by OCS activities. Often, seemingly 

contradictory conclusions are generated from these impact assessments. These contradictions can be 

explained by differences in many parameters, including oil concentrations and chemical composition, 

vegetation type and density, season or weather, preexisting stress level on the vegetation, soil types, and 

water levels. Data suggest that vegetation that is lightly oiled will experience plant die-back, followed by 

recovery without replanting; therefore, most impacts to vegetation are considered to be short term and 

reversible (Lytle, 1975; DeLaune et al., 1979; Webb et al., 1985; Alexander and Webb, 1987; Fischel et 

al., 1989). 

Shoreline types have been rated via the ESI’s, and according to their expected retention of oil and 

some biological effects, they exhibit oil persistence (Hayes et al., 1980; Irvine, 2000). Oil has been found 

or estimated to persist for at least 17-20 years in low-energy environments like salt marshes (Teal et al., 

1992; Baker et al., 1993; Burns et al., 1993; Irvine, 2000). In some instances, where there has been 

further damage due to cleanup activities, recovery has been estimated to take from 8 to 100 years (Baca et 

al., 1987). Effects on marsh vegetation can be severe (Baca et al., 1987; Baker et al., 1993). The longterm recovery times occurred in nutrient-limited, colder environments where biodegradation is limited. 

But, those conditions are unlike the nutrient-rich marshes of the Gulf Coast. An effect from the depletion 

of marsh vegetation is increased erosion, which is of special concern to coastal Louisiana and parts of 
4-72 Central Planning Area Supplemental EIS 

coastal Texas. Cleanup activities in marshes that can last years to decades following a spill may 

accelerate erosion rates and retard recovery rates. 

The critical concentration of oil is that concentration above which impacts to wetlands would be long 

term, because recovery would take longer than two growing seasons, and which causes plant mortality 

and permanent wetland loss. In coastal Louisiana, the critical concentration of oil resulting in long-term 

impacts to wetlands is assumed to be 0.1 l/2 (0.026 gal/10.76ft2

). Concentrations less than this typically 

cause dieback of the aboveground vegetation for one growing season, but limited mortality. As discussed 

in Chapter 4.4.3.2 of the Multisale EIS, higher concentrations would cause mortality of contacted 

vegetation, but 35 percent of the affected area would recover within 4 years. Oil can persist in the 

wetland soil for at least 5 years. After 10 years, permanent loss of 10 percent of the affected wetland area 

can be expected from accelerated landloss indirectly caused by a spill. If a spill contacts wetlands 

exposed to wave action, additional and accelerated erosion will occur (Alexander and Webb, 1987). 

Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in the Gulf because of 

high cumulative stress. 

Because OCS-related pipelines traverse wetland areas, pipeline accidents could result in high 

concentrations of oil directly contacting localized areas of wetland habitats (Fischel et al., 1989). The 

fluid nature of the oil, water levels, weather, and the density of the vegetation would limit the area of 

interior wetlands contacted by any given spill. Other studies have noted that oil is more persistent in 

anoxic sediments and, as a result of this longer residence time, have the potential to do damage to both 

marsh vegetation and associated benthic species. The sediment type, the anoxic condition of the soils, 

and whether the area is in a low- or high-energy environment all play a part in the persistence of oil in 

marsh sediment (Teal and Howarth, 1984). Based on data from Mendelssohn et al. (1990), recovered 

vegetation is expected to be the ecologically functional equivalent of unaffected vegetation. This study 

tested the reduction in plant density as the principle impact from spills. Mendelssohn and his associates 

demonstrated that oil could persist in the soil for greater than 5 years if a pipeline spill occurs within the 

interior of a wetland where wave-induced or tidal flushing is not regular or vigorous (Mendelssohn et al., 

1990). Since most of the wetlands along the Texas coast are either in moderate to high-energy 

environments, sediment transport and tidal stirring should reduce the chances for oil persisting in the 

event that these areas are oiled. 

While oil can completely foul wetland plants, it is the amount and type of oil as well as the particular 

plant that determines recovery. Some studies (Pezeshki et al., 2000) found that the Louisiana crude was 

less damaging and fatal to Spartina alterniflora than the heavier crudes. Heavy oiling can stop 

photosynthetic activity, but the S. alterniflora produced additional leaves and was able to recover without 

shoreline cleanup. The experiment did note that S. alterniflora benefited and recovered more quickly 

after shoreline cleanup. Observations by Dr. White (personal communication, 2010) noted the same type 

of recovery with Spartina spp. in the Mississippi River Birdsfoot Delta after the marshes were oiled from 

the DWH event. Within several weeks of the oiling, there was production of new shoots and no 

indication of root damage. He attributes the success partly to no invasive cleanup procedures in the 

marsh, which could result in the compaction of the soils and cause oil to get into the root systems. 

Although the Louisiana Coast is more stressed as a result of oil development and hurricanes, it has a 

viable wetland fringe that is located in a well-flushed tidal environment. However, this wetlands 

ecosystem, which is not nutrient dependent, provides a great environment for biodegradation and 

flushing. 

Secondary Impacts of Oil Spills 

The short-term effects of oil on wetland plants range from reduction in transpiration and carbon 

fixation to plant mortality. Depending on the type and quantity of oil in the sediment, mineralization of 

nutrients can be blocked so there is less nutrient uptake from the soils. The potential impact of the oiling 

on the wetland habitats is dependent on several factors, including season, wetland (fresh, salt, or 

brackish), sediment type, oil type, and quantity and degree of oiling. In general, most wetland plants are 

more susceptible to impacts from oiling during the growing season. Heavy oil causes mortality by 

coating gas exchange surfaces on the plants and by sealing sediment, which limits nutrient exchange to 

below-ground tissue. Light weight oils have been found to be more toxic to the marsh plants and 

associated organisms because the oil alters membrane permeability and disrupts metabolism (Pezeshki et 
Description of the Environment and Impact Analysis 4-73 

al., 2000). Due to the difference in oil tolerances of various wetland plants, changes in species 

composition may be evident as a secondary impact of the spill (Pezeshki et al., 2000). Studies indicated 

that some dominant freshwater marsh species (Sagittaria lancifolia) are tolerant to oil fouling and that 

some may recover without being cleaned (Lin and Mendelssohn, 1996). Even though some species 

recover from fouling without being cleaned and others benefit from cleaning (Pezeshki et al., 2000), other 

studies by Mendelssohn et al. (1990 and 1993) noted that the plant composition in an oiled marsh can be 

changed post-spill as a result of plant sensitivity to oil. So, there can be a trade off from the disturbance 

within these wetlands resulting from workers gaining access to the plants by foot or boat and the potential 

benefits of cleaning. The compaction of the soil, in combination with the oiling, may further stress the 

plants and result in grater mortality (Pezeshki et al., 1995). 

In a study by Mendelssohn et al. (1993) of a coastal pipeline break, low dosages of Louisiana crude 

(0.3 m2

 or 3 ft2 marsh coverage) resulted in considerable short-term effects on the brackish marsh 

community. These effects were due to wind and high water conditions. Winds increased water levels in 

the marsh and resulted in a more complete oiling of both stems and leaves, which caused a 64 percent 

decrease in adjacent vegetation live cover. While considerable die out of the marsh was noted, recovery 

of the marsh was complete within 5 years despite the residual hydrocarbons that were found in the marsh 

sediment (Mendelssohn et al., 1993). As noted in other studies and Mendelssohn et al. (1993), the season 

and wind direction at the time of a spill can increase the potential impact to wetlands. The study also 

noted that the health of the recolonizing vegetation was not significantly different from the health of 

vegetation found in the areas that were not oiled. Patterns of landloss were spatially variable but the rate 

of loss was no different than the unaffected areas. It appears that in areas of incomplete recovery the low 

soil elevation, coupled with subsidence, made them more susceptible to frequent flooding prior to the 

spill. In addition, the soil elevations were further compacted and elevation lowered by the heavy 

machinery used in the cleanup operations (Mendelssohn et al., 1993). 

As noted earlier, cleanup of these sensitive wetland habitats can be more disruptive and sometimes 

damaging than the oiling incident itself. Following the DWH event, USEPA and the USCG National 

Incident Command held a technology workshop and established an Interagency Alternative Technology 

Assessment Program (IATAP). This IATAP included numerous Federal agencies and local marsh 

ecologist with expertise concerning oil-spill cleanup to determine the least damaging approach to oil 

cleanup in these fragile coastal environments (U.S. Dept. of Homeland Security, CG, 2010d). The 

IATAP group reviewed various methods of response that could be used in areas that, based on hydrologic 

modeling, would receive oil. Current methods to clean up oil spills include mechanical and chemical 

removal, in situ burning, and bioremediation. The IATAP work group reviewed these and other 

mitigating measures specifically for areas where the vegetation had already been oiled. The IATAP 

recommended to keep the oil offshore and out of the marshes as long as possible, to not use actions that 

would further drive oil into the sediment (e.g., vessel and foot traffic), to not burn oil-contaminated 

vegetation if the water depth is insufficient or if there is the potential for re-oiling (this may result in root 

damage), to not apply dispersants in the marsh, to not use high-pressure washing that could drive oil 

deeper in sediments, to not hand clean vegetation (utilize low-pressure flushing if possible), and to 

monitor the utilization of sorbent booms. Bioremediation recommendations from the group were to 

minimize or eliminate vessel and foot traffic; mechanical removal methods should not disturb the 

substrate. Consideration was given to using nutrients and bacteria or fungi to enhance biodegradation. 

However, since the Gulf Coast is not nutrient limited, it was not determined to be useful. Two crucial 

points made by IATAP workgroup were (1) the use of particular cleanup methods is situation-dependent 

and (2) in the case of marshes it was best to do nothing and let nature take its course. The cleanup of oil 

spills in coastal marshes remains a problematic issue because wetlands can be extremely sensitive to the 

disturbances associated with cleanup activities. Once a marsh is impacted by an oil spill, a decision must 

be made concerning the best method of cleanup and restoration. Often the best course of action is to let 

the impacted area(s) recover naturally in order to avoid secondary impacts associated with the cleanup 

process, such as trampling vegetation, accelerating erosion, and burying oil (McCauley and Harrel, 1981; 

Long and Vandermeulen, 1983: Getter et al., 1984; Baker et al., 1993; Mendelssohn et al., 1993). 
4-74 Central Planning Area Supplemental EIS 

Summary and Conclusion 

Offshore oil spills resulting from the CPA proposed action are not expected to significantly damage 

any wetlands along the Gulf Coast. This is because of the distance from the spill to the coast and because 

wetlands are generally protected by barrier islands, peninsulas, sand spits, and currents. Although the 

probability of occurrence is low, the greatest threat from an oil spill to wetland habitat is from an inland 

spill as a result of a vessel accident or pipeline rupture. Wetlands in the northern Gulf of Mexico are 

either in moderate- to high-energy environments, so sediment transport and tidal stirring should reduce 

the chances for oil persisting in the event that these areas are oiled. While a resulting slick may cause 

minor impacts to wetland habitat and surrounding seagrass communities, the equipment, chemical 

treatments, and personnel used to clean up can generate the greatest impacts to the area. Associated foot 

traffic may work oil farther into the sediment than would otherwise occur. Close monitoring and 

restrictions on the use of bottom-disturbing equipment would be needed to avoid or minimize those 

impacts. In addition, an assessment of the area covered, oil type, and plant composition of the wetland 

oiled should be made prior to choosing remediation treatment. These treatments could include 

mechanical and chemical techniques with onsite technicians. Overall, impacts to wetland habitats from 

an oil spill associated with activities related to the CPA proposed action would be expected to be low and 

temporary because of the nature of the system, regulations, and specific cleanup techniques. 

4.1.1.4.4. Cumulative Impacts 

A detailed description of cumulative impacts upon wetlands can be found in Chapter 4.5.3.2 of the 

Multisale EIS and in Chapter 4.1.3.2.4 of the 2009-2012 Supplemental EIS. The following is a summary 

of the information presented in the Multisale EIS, the 2009-2012 Supplemental EIS, and new information 

that has become available since both documents were prepared. 

Background/Introduction 

Impacts from residential, commercial, and agricultural and silvicultural (forest expansion) 

developments are expected to continue in coastal regions around the Gulf. Existing regulations and 

development permitting procedures indicate that development-related wetland loss may be slowed and 

that 3-18 new onshore pipeline facilities, other than pipelines (26-39 landfalls), will be constructed in 

wetlands for the estimated life time (40 years) of the proposed action (Table 4-9 of the Multisale EIS). 

Impacts from State onshore oil and gas activities are expected to occur as a result of dredging for new 

canals, maintenance, and usage of existing rig access canals and drill slips, and preparation of new well 

sites. Locally, subsidence may be due to the extraction of large volumes of oil and gas from subsurface 

reservoirs, but subsidence associated with this factor seems to have slowed greatly over the last three 

decades as the reservoirs are depleted. However, recent reexamination of subsidence mechanisms by 

Stephens (2010b) states that the “Northern Gulf of Mexico continental margin is segmented by northwestsoutheast trending transfer fault zones related to Mesozoic rifting.” Indirect impacts from dredging new 

canals for State onshore oil and gas development (Chapter 4.1.3.3.3 of the Multisale EIS) and from the 

maintenance of the existing canal network is expected to continue. Maintenance dredging of the OCSrelated navigation channels accounts for 10 percent of the dredged material produced. 

Insignificant adverse impacts upon wetlands from maintenance dredging are expected because the 

large majority of the material would be disposed upon existing disposal areas. Alternative dredgedmaterial disposal methods can be used to enhance and create coastal wetlands. Depending upon the 

regions and the soils through which they were dredged, secondary adverse impacts of canals may be more 

locally significant than direct impacts. Additional wetland losses may be generated by the secondary 

impacts of saltwater intrusion, flank subsidence, freshwater-reservoir reduction, and deeper tidal 

penetration. A variety of mitigation efforts have been initiated to protect against direct and indirect 

wetland loss. The nonmaintenance of mitigation structures that reduces canal construction impacts can 

have substantial impacts upon wetlands. These localized impacts are expected to continue. Various 

estimates of the total, relative direct, and indirect impacts of pipeline and navigation canals on wetland 

loss vary enormously; they range from estimates of 9 percent (Britsch and Dunbar 1993) to 33 percent 

(Penland et al., 2001a and 2001b) to estimates of greater than 50 percent (Turner et al., 1982; Scaife et al., 

1983; Bass and Turner, 1997). A panel review of scientific evidence suggests that wetland losses directly 
Description of the Environment and Impact Analysis 4-75 

from human activities account for less than 12 percent of the total wetland loss experienced since 1930 

and approximately 29 percent of the total losses between 1955 and 1978 (Boesch et al., 1994). Of these 

direct losses, 33 percent are attributed to canal and spoil bank creation (10% of overall wetland loss). In 

Louisiana, deepening the Fourchon Channel to accommodate larger OCS-related service vessels has 

occurred within a saline marsh environment and provides the opportunity to create wetlands with the 

dredged materials. In addition, installation and improvement of channel armor along the Port Fourchon 

channel and the enforcement of vessel speed and “no wake zones” should greatly reduce the loss of 

wetlands due to erosion and vessel traffic. 

The main factors that continually affect wetlands from OCS activities are dredging, navigation 

channels and canals, pipelines, oil spill, and development of wetlands. The following is a summary of 

these effects on the wetlands and how the proposed action would not add significant negative effects to 

wetlands. 

Dredging of Channels 

There are 10 Federal channels totaling 2,000 km (1,243 mi) that are used in support of OCS activities 

(Chapter 4.5.3.2 of the Multisale EIS). Out of the 10 channels, 7 are shallow-water channels and 3 are 

deep-draft channels. All the channels will continue to require some form of maintenance dredging. The 

dredging cycle can range from 1 to 6 years, depending on channel or channel segment. Secondary 

wetland loss will continue throughout the 40-year project life because of canal widening resulting from 

erosion, saltwater intrusion, or a combination of the two. The extent of the losses depends on the future 

construction of channel stabilization features, hurricane activity, and increase in vessel use. The DOI has 

used a widening rate for OCS-related channels of 1.5 m/yr (4.9 ft/yr) (Chapter 4.5.3.2 of the Multisale 

EIS). Using the 2,000 km (1,243 mi) of estimated OCS-related channel length and the 1.5 m/yr (4.9 ft/yr) 

estimated bank widening rate, an annual landloss of ~300 ha/yr (741 ac/yr) could occur. So, in the 40-

year cumulative activities scenario, landloss from indirect impacts of Federal navigation channels could 

be ~12,000 ha (29,653 ac). These numbers are likely overestimates of losses since different erosion rates 

for armored channels are not considered. More recent studies by USGS found that canal widening rates 

have slowed rather than increased in recent years as a result of increased bank stabilization efforts 

(Johnston et al., 2009). The results of a recently completed study that included both armored and 

unarmored canals supports the hypothesis that there are reduced loss rates along armored canals (Johnston 

et al., 2009; Thatcher et al., 2011). Information about these rates and the results of the Thatcher et al. 

(2011) study are discussed in Chapter 4.1.1.4.2. 

Depending upon the regions and soils through which they were dredged, secondary adverse impacts 

of canals may be more locally significant than direct impacts. The OCS activities are expected to result in 

some level of dredging activity associated with the expansion of offshore platforms or onshore transfer or 

production facilities if needed. The primary indirect impacts from dredging would be wetland loss as a 

result of saltwater intrusion or vessel-traffic erosion. However, the primary support, transfer, and 

production facilities used for the CPA proposed action are located along armored canals and waterways, 

thus minimizing marsh loss. In the foreseeable future, there will be a continuing need for dredged 

material for both coastal restoration, wetland creation, and to some extent offshore sediments (e.g., sand, 

etc.) needed for beach restoration and hurricane protection. Alternative dredged-material disposal 

methods can be beneficially used for wetland creation or restoration as required by COE permitting 

program. 

It is also noted that the DWH event spill exposed both inland and offshore navigation channels to 

treated oil that may now be located on the bottom of the channel. Exact locations, quantities, and 

condition of the oil resulting from the DWH event are not currently known but will be made publicly 

available as the assessment process progresses and analyses are completed. Dredging in these areas could 

resuspend remnant oil, but this oil is not expected to be toxic. This is because of dispersant treatment, 

weathering, and natural biodegradation that occurred. 

The CPA proposed action is expected to use existing navigation channels and to contribute minimally 

to the need for additional channel maintenance. Impacts from State onshore oil and gas activities are 

expected to occur as a result of dredging for new canals, maintenance, and usage of existing rig access 

canals and drill slips, and preparation of new well sites. Insignificant adverse impacts upon wetlands 

from maintenance dredging are expected because the large majority of the material would be placed in 
4-76 Central Planning Area Supplemental EIS 

existing disposal areas or use alternate bank disposal techniques. The alternate bank disposal technique 

creates gaps to maintain hydrological connections and tidal circulation important in maintaining a 

functioning wetland. 

Navigation Channels and Canals 

The effects of pipelines, canal dredging, on navigation activities on wetlands are described in 

Chapters 4.1.2.1 and 4.2.2.1.3.2 of the Multisale EIS. Subsidence of wetlands is discussed in more detail 

in Chapter 4.1.3.3.1 of the Multisale EIS. 

As noted in the referenced chapters above, the previous OCS activities associated with the CPA are 

expected to require some level of dredging, channel deepening, and maintenance of access canals. 

Onshore activity that would further accelerate wetland loss includes additional construction of access 

channels, and drill slips and onshore action needed for construction of new well sites and expansion or 

construction of onshore and offshore facilities (production platforms or receiving and transfer facilities). 

Management activities, including erosion protection and restoration along the edges of these canals, can 

significantly reduce canal-widening impacts on wetland loss (Johnston et al., 2009; Thatcher et al., 2011). 

These and similar studies are discussed in detail in Chapter 4.1.1.4.2. Impacts resulting from activities 

related to navigation canals can be mitigated with bank stabilization, enforcement of no wake zones, and 

where possible, the beneficial use of dredged material (produced during maintenance dredging activities) 

to create wetland or upland habitats. The service vessels associated with the CPA proposed action would 

generate an estimated 137,000-220,000 trips annually, which is 2-3 percent of the total OCS traffic (12% 

of all vessel traffic) generated in the GOM. Based on these estimates, the vessel-induced erosion 

associated with the proposed action is minimal. Therefore, marsh loss resulting from the combination of 

vessel-induced erosion and saltwater intrusion from navigation channels and canals is unlikely. 

Pipelines 

Modern pipeline installation methods and impacts are described in Chapters 4.1.1.8.1 and 4.1.2.1.7 of 

the Multisale EIS. While impacts are greatly reduced by mitigation techniques, expansion of tidal 

influence, saltwater intrusion, hydrodynamic alterations, erosion, sediment transport, and habitat 

conversion can still occur (Cox et al., 1997; Morton, 2003; Ko and Day, 2004b). The majority (over 

80%) of OCS-related direct landloss is estimated to be from pipelines (Turner and Cahoon, 1988). Since 

the beginning of OCS activities in the GOM, approximately 15,400 km (9,563 mi) of pipelines have been 

constructed in Louisiana. These are seaward of the inland CZM boundary to the 3-mi State/Federal 

boundary offshore. Of those pipelines, about 8,000 km (4,971 mi) cross wetland and upland habitat. The 

remaining 7,400 km (4,595 mi) cross waterbodies (Johnston et al., 2009). The total length of non-OCS 

pipelines through wetlands is believed to be approximately twice that of the Gulf OCS Program, or about 

15,285 km (9,492 mi). There is a total of approximately 23,285 km (14,460 mi) of pipelines through 

Louisiana coastal wetlands. The majority of OCS pipelines entering State waters ties into existing 

pipeline systems and does not result in new landfalls. Pipeline maintenance activities that disturb 

wetlands are very infrequent and are mitigated to the maximum extent practicable. 

The widening of OCS pipeline canals does not appear to be an important factor contributing to OCSrelated direct landloss. This is because few pipelines are open to navigation, and the impact width does 

not appear to be significantly different from that for open pipelines closed to navigation. Based on the 

projected coastal Louisiana wetlands loss of 132,607 ha (327,679 ac) for the years 2000-2040 (Barras et 

al., 2003), landloss resulting from new OCS pipeline construction represents <1 percent of the total 

expected wetlands loss for that time period (Chapter 4.5.3.2 of the Multisale EIS). This estimate does not 

take into account the present regulatory programs and modern installation techniques. Recently built 

pipelines and pipeline canals are much narrower than in the past because of advances in technology and 

improved methods of installation. These advances are due to a greater awareness among regulatory 

agencies and industry (Johnston et al., 2009). The magnitude of impacts from OCS-related pipelines is 

inversely proportional to the quantity and quality of mitigation techniques applied. Pipelines with 

extensive mitigation measures appeared to have minimal impacts, while pipelines without such measures 

attributed to significant habit changes. Through proper construction methods, mitigation and 

maintenance, impacts can be minimized or altogether avoided. The BOEMRE is not a permitting agency 

of onshore pipelines. The permitting agency would be COE and the State in which the activity has or 
Description of the Environment and Impact Analysis 4-77 

would occur. Therefore, it would be the responsibility of COE and the States to ensure that wetland 

impacts resulting from pipeline construction are properly mitigated and monitored. 

Oil Spills 

The potential for coastal/inland oil spills will continue. This creates the greatest concern for coastal 

wetlands due to the spill’s proximity to these vegetated areas. The potential for vessel contact with 

improperly marked and abandoned wells in State nearshore waters will continue to increase until adequate 

funding is provided to monitor and inspect wells for compliance with procedures and regulations 

governing abandoned wells. The recent Barataria Bay spill (July 27, 2010) from an abandoned well in 

State waters released an estimated total of 7,000 gallons of oil and approximately 2,000 Mcf of natural 

gas per day (Powell, 2010; U.S. Dept. of Homeland Security, CG, 2010e). Aging infrastructure, 

including both platforms and pipelines, will continue to be an increasingly potential source of both inland 

and offshore spills. Over 3,000 production platforms in the Gulf are over 20 years old and were 

constructed prior to the modern structural requirements that increase endurance to hurricane force winds 

(Casselman, 2010). Earlier studies (Pulsipher et al., 1998) found that the age of a platform significantly 

affects the risk of an oil-spill accident during the exploration and production operations. Older pipelines 

are more susceptible to leaks through corrosion. As a result of how the older pipelines are constructed, 

these pipelines cannot be monitored or periodically inspected for potential leaks or pipeline weakness 

with modern, high-monitoring devices; therefore, the potential for preventing a potential leak is small. 

The potential for onshore and nearshore spills may decrease as a result of more stringent regulations and 

new policies that call for increased enforcement to address properly plugging and dismantling abandoned 

wells. 

Offshore spills are less likely to reach the coastal wetlands in a fully toxic condition due to 

weathering and the blockage of spills by barrier islands. However, any reduced elevation and erosion of 

these barrier islands by Hurricanes Katrina and Rita decrease the level of protection afforded the 

mainland (USDOC, NMFS, 2007a). Flood tides may now bring some oil through tidal inlets into areas 

landward of barrier beaches. The turbulence of tidal water passing through most tidal passes would break 

up the slick, thereby accelerating dispersion and weathering. For the majority of these situations, light 

oiling of vegetated wetlands may occur. This oil contributes less than 0.1 l/m2

 (0.026 gal/10.76 ft2) on 

wetland surfaces. Any adverse impacts that may occur to wetland plants are expected to be very short 

lived, probably less than 1 year. The OCS spills could occur as a result of pipeline accidents and barge or 

shuttle tanker accidents during transit or offloading. The frequency, size, distribution, and impacts of 

OCS coastal spills are provided in Chapter 4.3.1.7 of the Multisale EIS. Non-OCS spills can occur in 

coastal regions as a result of import tankers, coastal oil production activities, and petroleum product 

transfer accidents. Their distribution is believed to be similar to that described in Chapter 4.3.1 of the 

Multisale EIS. Numerous wetland areas have declined or have been destroyed as a result of oil spills 

caused by pipeline breaks or tanker accidents. 

The oil stresses the wetland communities, making them more susceptible to saltwater intrusion, 

drought, disease, and other stressors (Ko and Day, 2004b). Spills that occur in or near Chandeleur or 

Mississippi Sounds could affect wetland habitat in or near the Gulf Islands National Seashore and the 

Breton National Wildlife Refuge and Wilderness Area. Because of their natural history, these areas are 

considered areas of special importance. They also support endangered and threatened species. Although 

the wetland acreage on these islands is small, the wetlands make up an important element in the habitat of 

the islands. This area was severely impacted by Hurricane Katrina in August 2005. The inlets that 

connect Mississippi Sound with the marsh-fringed estuaries and lagoons within the islands are narrow, so 

a small percentage of the oil that contacts the Sound side of the islands would be carried by the tides into 

interior lagoons. The past discharge of saltwater and drilling fluids associated with oil and gas 

development has been responsible for the decline or death of some local marshes (Morton, 2003). 

Discharging OCS-related produced water into inshore waters has been discontinued, and all OCSproduced waters transported to shore are either injected or disposed of in Gulf waters and would not 

affect coastal wetlands (Chapter 4.1.1.4.2 of the Multisale EIS). 

The numbers and sizes of coastal spills are presented in Table 4-13 of the Multisale EIS. About 95 

percent of these spills are projected to be from non-OCS-related activity. Of coastal spills <1,000 bbl, the 

assumed size is 5 bbl; therefore, the great majority of coastal spills would affect a very small area and 
4-78 Central Planning Area Supplemental EIS 

dissipate rapidly. The small coastal spills that do occur from OCS-related activity would originate near 

terminal locations in the coastal zones of Texas, Louisiana, Mississippi, and Alabama, but primarily 

within the Houston/Galveston area of Texas and the deltaic area of Louisiana. An average of nine large 

(10,000 bbl) offshore spills is projected to occur annually in the CPA from all OCS sources over a 

40-year scenario (Table 4-15 of the Multisale EIS). Of these offshore spills, one is estimated to occur 

every year from the Gulfwide OCS Program (Table 4-13 of the Multisale EIS). A total of 1,000-1,200 

smaller (<1,000 bbl) offshore spills are projected annually from the OCS Program Gulfwide (Table 4-13 

of the Multisale EIS). Chapter 4.3.1 of the Multisale EIS describes projections of future spill events in 

more detail. The OCS-related spills in the Gulf are expected to cause relatively small effects to fish 

resources, and they are discussed in Chapter 4.4.10 of the Multisale EIS. 

The DWH event was the largest spill recorded in the GOM and resulted in the oiling of most of the 

Gulf Coast shoreline from the Louisiana/Texas State line to northwest Florida. This event must be 

considered in the cumulative baseline due to the volume of oil released and the geographic area affected. 

However, unlike other historic large spills (Exxon Valdez and Ixtoc), the oil was released and treated in 

deep water nearly 97 km (60 mi) from shore, and the spill occurred in an unconfined open ocean as 

opposed to a sheltered embayment. All of these factors contribute to the weathering and detoxification of 

the oil that reached the shoreline. It is too early to determine the cumulative long-term effect, if any, of 

this spill on the ongoing marsh loss or the acceleration of that loss. The current view of most wetland 

scientists in the area is that, due to the minimal penetration into the marsh, the weathered condition of the 

oil, and the observed resiliency of the marsh plants to oiling, the overall effect would be minor and 

recovery of some marsh vegetation is already being seen (Burdeau and Collins, 2010; Mascarelli, 2010; 

Zabarenko, 2010). While catastrophic spills could occur in the future as a result of human error, new 

regulations focusing on improved safety, more regulatory checks, and inspections should decrease the 

already small likelihood of the occurrence of such spills. 

Development of Wetlands 

The development of wetlands for agricultural, residential, and commercial uses will continue with 

more regulatory and planning constraints. Wetland damage would be minimized through the 

implementation of CZM guidelines, COE regulatory guidelines for wetland development, and various 

State and Federal coastal development programs. Examples of these programs are the Coastal Impact 

Assistance Program (CIAP), the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA), 

and LACPR. 

The past discharge of saltwater and drilling fluids associated with oil and gas development has been 

responsible for the decline or death of some marshes (Morton, 2003). Discharging OCS-related produced 

water into inshore waters has been discontinued, and all OCS-produced waters transported to shore would 

either be injected or disposed of in Gulf waters and would not affect coastal wetlands (Chapter 4.1.1.4.2 

of the Multisale EIS). Dredged material would be deposited either in existing approved discharge sites or 

would be used beneficially for wetland restoration or creation. In the Port Fourchon area, some of the 

existing areas being filled with dredged material may be used, if needed, for the expansion of oil 

production or support facilities. 

Cumulative loss of wetlands has occurred as a result of both natural and anthropogenic events. 

Natural subsidence has caused wetland loss through compaction of Holocene strata (the rocks and 

deposits from 10,000 years ago to present). Human factors such as onshore oil and gas extraction, 

groundwater extraction, drainage of wetland soils, and burdens placed by buildings roads and levees have 

also caused wetland loss. Areas of local subsidence have also been correlated to the past extraction of 

large volumes of underground resources including oil, gas, water, sulfur, and salt (Morton, 2003; Morton 

et al., 2002 and 2005). There is increasing new evidence of the importance of the effect of sea-level rise 

(or marsh subsidence) as it relates to the loss of or changes in marshes, types of marsh, and plant diversity 

(Spalding and Hester, 2007). This study shows that the very structure of coastal wetlands would likely be 

altered by sea-level rise because community shifts would be governed by the responses of individual 

species to new environmental conditions. Flood control and channel training along the Mississippi River 

would continue to deprive the delta of the needed sediment required for the creation or maintenance of the 

existing wetlands. Another recent development that is presently being proposed along the Mississippi 

coast and is planned for the Louisiana and Texas coasts is the preparation of salt domes for the storage of 
Description of the Environment and Impact Analysis 4-79 

strategic oil reserves. The current plan would result in discharging highly concentrated salt solutions into 

the nearshore Gulf and bays. The potential for large modifications (increases) in coastal salinities could 

result in devastating or severely compromising the coastal marshes (Mississippi Press, 2007). 

Following Hurricanes Rita and Katrina, the demand for large quantities of earthen construction 

materials for hurricane-protection levee construction or restoration resulted in either removing or 

damaging some marginal wetlands. It is expected that the need for these materials will continue in the 

future. 

Summary and Conclusion 

Wetlands are most vulnerable to inshore or nearshore oil spills but these are localized events. Spill 

sources include vessel collisions, pipeline breaks, and shore-based transfer, refining, and production 

facilities. The wetlands associated with the CPA proposed action have a minimal probability for oil-spill 

contact. This reduced risk is due to the distance of the offshore facility to wetland sites, beach and barrier 

island topography (although locally reduced post-Hurricanes Katrina and Rita), and product transportation 

through existing pipelines or pipeline corridors. Wetlands can also be at risk for offshore spills, but the 

risks are minimized by distance, time, sea conditions, and weather. If they do reach shore, only light 

localized impacts to inland wetlands would occur. If any inland spills occur, they would likely be small 

and at inland service bases or other support facilities and generally located away from wetlands; therefore, 

the spills would not be expected to affect wetlands. 

While landloss will continue from subsidence and saltwater intrusion, the State of Louisiana and COE 

have implemented freshwater diversion projects to minimize the effect of this saltwater-induced landloss. 

Landloss would continue from vessel traffic; however, because of the small increase in traffic caused by 

the proposed action, this loss would also be minimal. The CPA proposed action would not require any 

channel maintenance; therefore, no additional wetland loss would result from dredged material disposal. 

If dredged-material disposal is required, it would likely be beneficially used for marsh creation. Disposal 

of OCS wastes and drilling by-products would be delivered to existing facilities. Because of existing 

capacity, no additional expansion into wetland areas is expected. 

Development pressures in the coastal regions of Louisiana, Mississippi, Alabama, and Florida have 

caused the destruction of large areas of wetlands. In coastal Louisiana, the most destructive 

developments have been the inland oil and gas industry projects, which have resulted in the dredging of 

huge numbers of access channels. Agricultural, residential, and commercial developments have caused 

the most destruction of wetlands in Mississippi, Alabama and Florida. In Florida, recreational and tourist 

developments have been particularly destructive. These trends are expected to continue. During the 

period from 2001 to 2040, between 248,830 and 346,590 ha (614,872 and 856,443 ac) of wetlands would 

be lost from the Louisiana coastal zone and 1,600-2,000 ha (647-809 ac) would be lost from the 

Mississippi coastal zone. Wetland losses in the coastal zones of Alabama and Florida are assumed to be 

comparable with those in Mississippi. New and existing pipeline channels would continue eroding, 

largely at the expense of wetlands; however, channel armor may be added at a later date. However, these 

estimates do not take into account the current regulatory programs, modern construction techniques and 

mitigations, or any new techniques that might be developed in the future. Because of modern 

construction techniques and mitigation measures, there would be zero to negligible impacts on wetland 

habitats as a result of the CPA proposed action. The CPA proposed action represents a small percentage 

(<10%) of total OCS activity (USDOI, MMS, 2007b). Impacts associated with the CPA proposed action 

are a minimal part of the overall OCS impacts. The cumulative effects of human and natural activities in 

the coastal area have severely degraded the deltaic processes and have shifted the coastal area from a 

condition of net land building to one of net landloss. Deltaic Louisiana is expected to continue to 

experience the greatest loss of wetland habitat. Wetland loss is also expected to continue in coastal 

Mississippi, Alabama, and Florida, but at slower rates. The incremental contribution of the CPA 

proposed action to the cumulative impacts on coastal wetlands is expected to be small. 

4.1.1.5. Seagrass Communities 

The BOEMRE has reexamined the analysis for seagrass communities presented in the Multisale EIS 

and the 2009-2012 Supplemental EIS (addition of 181 South Area) based on the additional information 
4-80 Central Planning Area Supplemental EIS 

presented below and in consideration of the DWH event. No substantial new information was found that 

would alter the impact conclusion for seagrass communities presented in the Multisale EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. 

Turbidity impacts from pipeline installation and maintenance dredging associated with the CPA proposed 

action would be temporary and localized. The increment of impacts from service-vessel transit associated 

with the CPA proposed action would be minimal. Should an oil spill occur near a seagrass community, 

impacts from the spill and cleanup would be considered short term in duration and minor in scope. Close 

monitoring and restrictions on the use of bottom-disturbing equipment to clean up the spill would be 

needed to avoid or minimize those impacts. Of the cumulative activities, dredging generates the greatest 

overall risk to submerged vegetation, while hurricanes cause direct damage to seagrass beds, which may 

fail to recover in the presence of cumulative stresses. The CPA proposed action would cause a minor 

incremental contribution to cumulative impacts due to dredging from maintenance of channels. 

4.1.1.5.1. Description of the Affected Environment 

A detailed description of seagrass communities in the CPA (Louisiana, Mississippi, Alabama, and 

because of its close proximity to the CPA, Florida is discussed here) can be found in Chapter 4.2.2.1.3.3 

of the Multisale EIS. Additional information regarding the additional 181 South Area and any new 

information found since the publication of the Multisale EIS is presented in Chapter 4.1.3.3 of the 2009-

2012 Supplemental EIS. The following information is a summary of the resource description 

incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

A search was conducted for new information published on submerged vegetation, and various 

Internet sources were examined to determine any recent information regarding seagrasses. Sources 

investigated include BOEMRE, USDOC/NOAA, the USGS National Wetlands Research Center, the 

USGS Gulf of Mexico Integrated Science Data Information Management System, Seagrass Watch, Gulf 

of Mexico Alliance, State environmental agencies, USEPA, and coastal universities. Other websites from 

scientific publication databases were checked for new information using general Internet searches based 

on major themes. New information is discussed below. 

Submerged vegetation distribution and composition depend on an interrelationship among a number 

of environmental factors that include water temperature, depth, turbidity, salinity, turbulence, and 

substrate suitability (Kemp, 1989; Onuf, 1996; Short et al., 2001). Marine seagrass beds generally occur 

in shallow, relatively clear, protected waters with sand bottoms (Short et al., 2001). Freshwater 

submerged aquatic vegetation (SAV) species occur in the low-salinity waters of coastal estuaries 

(Castellanos and Rozas, 2001). True seagrasses that occur in the Gulf of Mexico are Halodule beaudettei

(formerly Halodule wrightii; shoal grass), Halophila decipiens (paddle grass), Halophila engelmannii

(star grass), Syringodium filiforme (manatee grass), and Thalassia testudinum (turtle grass) (Short et al., 

2001; Handley et al., 2007). Although it is not considered a true seagrass because it has 

hydroanemophilous pollination (pollen grains float) and can tolerate freshwater, Ruppia maritima

(widgeon grass) is common in the brackish waters of the Gulf of Mexico (Zieman, 1982; Berns, 2003; 

Cho and May, 2008). Freshwater genera that are dominant in the northern Gulf of Mexico are 

Ceratophyllum, Najas, Potamogeton, and Vallisneria (Castellanos and Rozas, 2001; Cho and May, 2008). 

Submerged vegetation increases protection from predation and food resources for associated nekton 

(Rozas and Odum, 1988; Maiaro, 2007). Seagrasses and freshwater SAV’s provide important nursery 

and permanent habitat for sunfish, killifish, immature shrimp, crabs, drum, trout, flounder, and several 

other nekton species and provide a food source for species of wintering waterfowl and megaherbivores 

(Rozas and Odum, 1988; Rooker et al., 1998; Castellanos and Rozas, 2001; Heck et al., 2003; Orth et al., 

2006). They also act in carbon sequestration, nutrient cycling, and sediment stabilization (Heck et al., 

2003; Duarte et al., 2005; Orth et al., 2006). They are also substrate for epiphytes to grow, which can be 

a hindrance (shading) if too thick to the seagrass, but those epiphytes serve as another food source to 

different species (Howard and Short, 1986; Bologna and Heck, 1999). 
Description of the Environment and Impact Analysis 4-81 

According to the most recent and comprehensive data available, approximately 500,000 ha 

(1.25 million ac) of seagrass beds are estimated to exist in exposed, shallow coastal/nearshore waters and 

embayments of the Gulf of Mexico, and over 80 percent of these beds are in Florida Bay and Florida 

coastal waters (calculated from Handley et al., 2007). In the northern Gulf of Mexico from south Texas 

to Mobile Bay, seagrasses occur in relatively small beds behind barrier islands in bays, lagoons, and 

coastal waters (Figure 4-3); while SAV’s occur in the upper freshwater regions of estuaries and rivers 

(Onuf, 1996; Castellanos and Rozas, 2001; Handley et al., 2007). Increased nutrients and sediments from 

either natural or anthropogenic events such as tropical cyclones and watershed runoff are common and 

significant causes of seagrass decline (Carlson and Madley, 2007). Recent increases in natural and 

anthropogenic stresses have led to decreases in these communities worldwide (Orth et al., 2006). The 

USGS’s Seagrass Status and Trend in the Northern Gulf of Mexico: 1940-2002 demonstrated a decrease 

of seagrass coverage from approximately 1.02 million ha (2.52 million ac) estimated in 1992 to 

approximately 500,000 ha (1.25 million ac) calculated in the 2002 report (Handley et al., 2007). While 

declines have been documented for different species in different areas, it is difficult to estimate rates of 

decrease because of the fluctuation of biomass among the different species, seasonally and yearly.

Louisiana: In Louisiana, submerged vegetation primarily consists of freshwater and low-salinity 

vegetation. Largely due to the turbid water conditions that are caused by the Mississippi and Atchafalaya 

Rivers, seagrass beds in Louisiana have low densities and are rare. The exceptions are the beds in the 

vicinity of the Chandeleur Island chain located between Louisiana and Mississippi (Poirrier, 2007). Many 

beds in Louisiana are continually affected by storm events of different severities throughout the year. 

Submerged vegetation is physically removed, buried, or exposed to drastic salinity shifts after severe 

storm events (Maiaro, 2007). The recovery times for beds depends on the size of the disturbance 

(Fourqurean and Rutten, 2004). Strong storm events not only remove seagrass and SAV beds but also 

change the nekton community structure (Maiaro, 2007). In Biloxi Marsh, southeast Louisiana, nekton 

communities at sites denuded of R. maritima by Hurricanes Cindy and Katrina resembled communities in 

sites that had no vegetation before the hurricanes (Maiaro, 2007). The seagrasses behind the Chandeleur 

Island chain and SAV communities within Plaquemines and St. Bernard Parishes had contact with the oil 

from the DWH event and had considerable physical stress from various prevention and cleanup efforts 

(USDOC, NOAA, 2010f). There is the potential for significant shifts in community structure, but the 

current health of the community in unknown. It is assumed there will be a decrease in submerged 

vegetation and a negative impact on the communities in the areas affected by the DWH event. There are 

ongoing research projects that will document effects of the spill and associated activities on local 

communities. This research also includes a study on the environmental effects from the oil barrier berms 

built in portions of southeastern Louisiana. 

Mississippi: Seagrass beds primarily occur in the Mississippi Sound and are in the proximity of the 

Gulf Island National Seashore islands including Ship, Horn, Petit Bois, and Cat (Moncreiff, 2007). After 

local extinctions of T. testudinum and S. filiforme from Hurricane Camille and recent increases in 

freshwater outflow from nearby watersheds, there has been an increase in R. maritima and a persistence 

of H. beaudettei, making them the predominant submerged vegetation communities along the Mississippi 

coast (Cho and May, 2008; Cho et al., 2009; Barry A. Vittor and Associates, Inc., 2009). While 

submerged vegetation abundance decreased in 2005 after the passage of Hurricanes Cindy and Katrina, 

there was a documented increase in abundance in 2006 (Cho and May, 2008). Because R. maritima is 

known to be resilient to temporary disturbances, further studies confirmed a seasonal trend to percent 

cover changes in the Mississippi Sound (Cho and May, 2008). This resiliency could be an important 

factor in ecosystem health with events such as the DWH event. Mississippi Sound had oil slicks from the 

DWH event, and some beds within that area had contact with both tarballs and oil (USDOC, NOAA, 

2010f). The current health of the system is unknown. If this area continues to accrue oil, then there is the 

hypothesis that there would be a decrease in seagrass cover and an adverse effect on the associated 

community. Research is being conducted to assess the effects from the event on the local submerged 

vegetation beds. 

Alabama: Barry A. Vittor & Associates, Inc. (2009) reported approximately 2,100 ha (5,250 ac) of 

freshwater and marine submerged vegetation in Alabama coastal waters. They found there was a 

decrease in SAV cover in the southern portion of the study area in coastal Alabama from 2002 to 2009 by 

approximately 20 percent. Hurricanes Ivan and Katrina potentially influenced the local SAV 

communities with increased salinity, water turbidity, and scouring from storm surges (Barry A. Vittor & 
4-82 Central Planning Area Supplemental EIS 

Associates, Inc., 2009). However, there was no large-scale impact on the distribution or ecological 

performance of Alabama’s marine seagrass beds from either Hurricane Ivan or Katrina (Byron and Heck, 

2006; Anton et al., 2009). While oil and tarballs have impacted the barrier islands in coastal Alabama, 

any effect to the beds from the impact of the DWH event are unknown (USDOC, NOAA, 2010f). At this 

time, it is assumed that these communities are generally similar ecologically to what it was before the 

DWH event occurred. There are extensive sampling efforts underway throughout the Gulf of Mexico to 

assess any effects from the incident to different submerged vegetation beds. 

Florida: There are an estimated 400,000 ha (1 million ac) of seagrasses in west Florida’s nearshore 

coastal waters and Florida Bay (Carlson and Madley, 2007). Most of the seagrass coverage in Florida is 

in south Florida and the higher-salinity estuarine regions in the Florida Panhandle, between Pensacola and 

Alligator Harbor, and the Big Bend area (Dawes et al., 2004; Carlson and Madley, 2007; Carlson et al., 

2010). The Big Bend area has low wave energy due to the shallow and gently sloping nature of the sea 

bottom, and these beds extend into Federal waters (CSA and Martel Laboratories, Inc., 1985; Zieman and 

Zieman, 1989). This area had declined by approximately 95,000 ha (234,750 ac) in 2001 to 

approximately 91,000 ha (224,866 ac) in 2006 (4.5%) in continuous seagrass coverage (Carlson et al., 

2010). Throughout the west Florida shelf, there are seasonally patchy offshore beds of H. decipiens

(Dawes et al., 2004). Many beds in Florida are protected by extensive barrier islands. These islands help 

protect the Florida coast from the many tropical cyclones that impact this State. However, the increased 

turbidity and freshwater from these storm events have decreased many areas of seagrass beds on the 

western coast of Florida (Carlson et al., 2010). The panhandle was exposed to oil and tarballs from the 

DWH event, but the majority of the seagrass beds in south Florida received little impact from the DWH 

event (USDOC, NOAA, 2010f). It is assumed these communities will be similar to how they were before 

the DWH event unless a significant delayed impact occurs. Florida has multiple sampling stations to 

examine any effects from the incident to submerged vegetation beds. 

4.1.1.5.2. Impacts of Routine Events 

Background/Introduction 

The routine events associated with OCS activities in the CPA that could adversely affect submerged 

vegetation communities include construction of pipelines, canals, navigation channels, and onshore 

facilities; maintenance dredging; and vessel traffic (e.g., propeller scars). Many of these activities would 

result in an increase of water turbidity that is detrimental to submerged vegetation health. Through 

avoidance and mitigation policies, these effects are generally localized, short-term, and minor in nature. 

Existing and projected lengths of OCS-related dredging, pipelines, and vessel activities are described in 

detail in Chapters 4.1.2.1.7 and 4.1.3.3.3 of the Multisale EIS and in Chapter 3.1 of this Supplemental 

EIS. The dynamics of how these activities impact submerged vegetation is discussed in Chapters 

4.2.1.1.3.3 and 4.2.2.1.3.3 of the Multisale EIS and are summarized here. 

Proposed Action Analysis 

Dredging impacts associated with the installation of new navigation channels are greater than those 

for pipeline installations because it creates a much wider and deeper footprint. New canal dredging and 

related disposal of dredged material also cause significant changes in regional hydrology (Onuf, 1994; 

Collins, 1995; Erftemeijer and Lewis, 2006). Examples of this are the heavy traffic utilizing the Gulf 

Intracoastal Waterway and maintenance dredging that decrease local seagrass beds in Laguna Madre, 

Texas (Texas Parks and Wildlife Department, 1999). Deepwater oil and gas exploration requires larger 

vessels that could cause channel widening; however, the inshore facilities would probably remain the 

same. In Louisiana, they are located in Cameron, Fourchon, Intracoastal, Morgan City, and Venice. In 

Mississippi, there is a shore base in Pascagoula, and in Alabama, the shore base is in Theodore. Channel 

dredging to facilitate, create, and maintain waterfront real estate, marinas, and waterways will continue to 

be a major impact-producing factor on the Gulf Coast. The waterway maintenance program of COE has 

been operating in the CPA for decades. Impacts generated by initial channel excavations are sustained by 

regular maintenance activities performed on average every 2-5 years. Maintenance activities are 

projected to continue into the future regardless of the OCS activities. 
Description of the Environment and Impact Analysis 4-83 

Dredge and fill activities are the greatest threats to submerged vegetation habitat (Wolfe et al., 1988). 

Effects from dredging and resuspension of sediments are relative to dredge type and sediment size 

(Collins, 1995). The most serious impacts generated by dredging activities to submerged vegetation and 

associated communities are a result of the removal of sediments, changes in salinity, burial of existing 

habitat, and oxygen depletion and reduced light associated with increased water turbidity (Erftemeijer and 

Lewis, 2006). Increased water turbidity from dredging operations that causes light attenuation negatively 

affects vegetation health (Onuf, 1994; Kenworthy and Fonseca, 1996). Suspension of the fine sediments 

from dredging activities may influence not only water clarity but also nutrient dynamics in estuaries, 

which can decrease overall primary production (Essink, 1999; Erftemeijer and Lewis, 2006). While these 

effects can decrease submerged vegetation cover, the activities would be localized and monitored events. 

Also, plans for installation of new linear facilities and maintenance dredging are reviewed by a variety of 

Federal, State, and local agencies and the interested public in order to receive the necessary government 

approvals. Mitigation may be required to reduce undesirable effects on beds from dredging activities. 

The most effective mitigation for direct impacts to submerged vegetation beds and associated 

communities is avoidance, but if contact is unavoidable then actions such as using turbidity curtains with 

a sizable barrier can mitigate dredge effects. 

Pipeline construction in coastal waters could temporarily elevate water turbidity in submerged 

vegetation beds near the pipeline routes. The duration of increased water turbidity would depend on 

factors like currents, bottom topography, and substrate type (Collins, 1995). The COE and State permit 

requirements are expected to impose pipeline routes that avoid high-salinity beds, as well as reduce and 

maintain water turbidity within tolerable limits for submerged vegetation. About 250 active OCS 

pipelines currently cross the Federal/State boundary into State waters, of which over 100 make landfall. 

There are 80-118 new pipelines projected in State waters as a result of the OCS Program from 2007 to 

2046. Of those, 26-39 are anticipated to make landfall in the CPA. Most activities would use existing 

inshore structures, so less than one pipeline a year would make landfall. If any new pipelines run to shore 

due to the CPA proposed action, environmental permit requirements for locating pipelines would result in 

minimal impact on seagrasses. Because of regular tidal flushing, increased water turbidity from pipeline 

activities is projected to be below significant levels. Therefore, effects on submerged vegetation by 

pipeline installation are predicted to be small and short term. 

Vessel traffic would only pose a risk to seagrasses when near shore and to SAV when inshore. 

Submerged vegetation beds near active navigation channels would already be altered physically by 

regularly occurring associated activities. Because of the depths where major vessel traffic occurs, 

propeller wash would not resuspend sediments in navigation channels beyond pre-project conditions. 

Little, if any, damage to submerged vegetation beds would occur as a result of typical channel traffic. 

Scarring of seagrass beds by vessels (e.g., support vessels for OCS and State oil and gas activities, fishing 

vessels, and recreational watercraft) is an increasing concern along the Mississippi, Alabama, and Florida 

coasts (Sargent et al., 1995; USDOI, GS, 2004). Scarring most commonly occurs in water depths less 

than 2 m (~6 ft) as a result of boats operating in too shallow water (Zieman, 1976; Sargent et al., 1995; 

Dunton et al., 1998). Consequently, their propellers and occasionally their keels plow through vegetated 

bottoms tearing up roots, rhizomes, and whole plants, leaving a furrow that is devoid of submerged 

vegetation (Zieman, 1976; Dawes et al., 1997). This can ultimately destroy the beds, which are essential 

nursery habitat for many species (Heck et al., 2003; Orth et al., 2006). The recovery period from scarring 

varies with the width of the scar, type of scarring, sediment, water quality, and species (Zieman, 1976; 

Durako et al., 1992; Sargent et al., 1995). If a bed has extensive damage or an already stressed bed is 

damaged, it could take decades to recover. Scarring may have a more critical effect on habitat functions 

in areas with less submerged vegetation, like those found in Louisiana. The State of Florida has the 

Seagrass Outreach Partnership that consists of citizens, researchers, law enforcement officers, and marine 

resource managers. It was created to reducing boating impacts to seagrass meadows through education. 

Restoration efforts are funded through fines collected from boaters. There would be little reason for an 

OCS vessel to anchor or stop in areas that are not designated ports or work structures; therefore, it would 

be rare for these vessels to be in areas populated by vegetation. There would be little reason for an OCS

vessel to anchor or stop in areas that are not designated ports or work structures; therefore, it would be 

rare for these vessels to be in areas populated by vegetation. 
4-84 Central Planning Area Supplemental EIS 

Summary and Conclusion 

Routine OCS activities in the CPA are not expected to significantly increase in occurrence and range 

in the near future. Mitigation reduces the undesirable effects on submerged vegetation beds from 

dredging activities. Permit requirements should ensure pipeline routes avoid high-salinity beds and 

maintain water clarity and quality. Local programs decrease the occurrence of prop scarring in grass 

beds, and channels utilized by OCS vessels are generally away from exposed submerged vegetation beds. 

Because of these requirements, natural flushing, and implemented programs, any potential effects from 

routine activities on submerged vegetation in the CPA are expected to be localized and not significantly 

adverse. 

4.1.1.5.3. Impacts of Accidental Events 

Background/Introduction 

A detailed analysis of accidental impacts upon seagrass communities can be found in Chapter 4.4.3.3 

of the Multisale EIS and in Chapter 4.1.3.3.3 of the 2009-2012 Supplemental EIS. The following is a 

summary of that information and any new information discovered through recent literature searches since 

both documents were prepared. 

Proposed Action Analysis 

In Louisiana, submerged vegetation primarily consists of freshwater and low-salinity vegetation, but 

there are seagrass beds in the vicinity of the Chandeleur Island chain (Poirrier, 2007). Mississippi 

seagrass beds primarily occur in the Mississippi Sound and are in the proximity of the Gulf Island 

National Seashore islands (Moncreiff, 2007). Alabama’s coast has submerged beds throughout the area. 

Most of the seagrass coverage in Florida is in south Florida and the higher-salinity estuarine regions in the 

Florida Panhandle, between Pensacola and Alligator Harbor, and the Big Bend area (Dawes et al., 2004; 

Carlson and Madley, 2007; Carlson et al., 2010). Accidental events possible with the CPA proposed 

action that could significantly adversely affect submerged vegetation beds include near and inshore spills 

connected with the transport and storage of oil. Offshore oil spills that occur in the proposed action area 

are less likely to contact seagrass communities than are inshore spills because the seagrass beds are 

generally protected by barrier islands, peninsulas, sand spits, and currents. However, if the temporal and 

spatial duration of the spill is massive, then an offshore spill could affect submerged vegetation 

communities as seen with the DWH event. 

The probabilities of a spill 1,000 bbl occurring and contacting environmental features are described 

in Chapter 4.3.1.5 and Figure 4-12 of the Multisale EIS. The total estimated number of offshore spill 

events ranging from 0 to 10,000 bbl over the 40-year life of the CPA proposed action is 2,690-5,452 

spills (Table 3-5; Chapter 4.3.1.5 of the Multisale EIS). The risk of an offshore spill 1,000 bbl 

occurring and contacting coastal counties and parishes was calculated by BOEMRE’s oil-spill trajectory 

model. Counties and parishes are used as an indicator of the risk of an offshore spill reaching sensitive 

coastal environments, and this is the point when oil could contact the submerged community. Figure 4-14 

of the Multisale EIS provides the results of the OSRA model that calculated the probability of a spill 

1,000 bbl occurring offshore as a result of the proposed action and reaching a Gulf Coast county or 

parish. 

Most of the counties and parishes are at minimum risk of being contacted; the most frequently 

calculated probability of a spill contacting their shorelines is less than 0.5 percent. Eight parishes in 

Louisiana have a chance of spill contact that is greater than 0.5 percent. For these parishes, the chance of 

an OCS offshore spill 1,000 bbl occurring and reaching their shoreline ranges from 1 percent to 15 

percent. Plaquemines Parish, Louisiana, has the greatest risk of a spill occurring and contacting its 

shoreline. The probability of an oil spill 1,000 bbl contacting the State offshore waters within 10 days 

and contacting some submerged vegetation in the CPA for western Louisiana is 23-35 percent, eastern 

Louisiana is 6-9 percent, Mississippi is 1 percent, and it is less than 0.5 percent for all other states (Figure 

4-15 of the Multisale EIS). 

Inshore spills may result from either vessel collisions or ruptured pipelines that release crude and 

condensate oil. The coast from the Atchafalaya Bay to east of the Mississippi River in Louisiana has the 
Description of the Environment and Impact Analysis 4-85 

greatest risk of experiencing coastal spills related to the CPA proposed action (Chapter 4.3.1.7.2 of the 

Multisale EIS). Because of the floating nature of nondispersed crude oil, the regional microtidal range, 

dynamic climate with mild temperatures, and the amount of micro-organisms that consume oil, these 

spills would typically be short-term events and have little prolonged effects on vegetated communities 

and the associated fauna (DeLaune et al., 1990; Roth and Baltz, 2009). Increased water turbulence from 

waves, storms, or vessel traffic breaks apart the surface oil sheen and disperses some oil into the water 

column or mix the oil with sediments, which can settle and coat the entire plant with oil and sediments 

(Teal and Howarth, 1984; Thorhaug, 1988; Burns et al., 1994). This coating situation also happens when 

oil is treated with dispersants because the dispersants break down the oil and it sinks into the water 

column. However, as reviewed in Runcie et al. (2004), oil mixed with dispersants has shown an array of 

effects on seagrass depending on the species and dispersant used. 

An offshore spill would inundate the coastal waters first and affect local communities similar to an 

inshore spill. With a greater distance from shore, there is a greater chance of the oil being weathered by 

natural and mechanical processes by the time it reaches the nearshore habitat. 

If an oil slick settles into a protective embayment where submerged vegetation beds are found, 

decreased water clarity from coating and shading causes reduced chlorophyll production and could lead to 

a decrease in vegetation (Erftemeijer and Lewis, 2006). Depending on the species and environmental 

factors (e.g., temperature and wave action), seagrasses may exhibit minimal impacts from a spill; 

however, communities residing within the beds could accrue greater negative outcomes (den Hartog and 

Jacobs, 1980; Jackson et al., 1989; Kenworthy et al., 1993; Taylor et al., 2006). Community effects could 

range from direct mortality due to smothering or indirect mortality from loss of food sources and habitat 

to a decrease in ecological performance of the entire system depending on the severity and duration of the 

spill event (Zieman et al., 1984). Because different species have different levels of sensitivity to oil, it is 

difficult to compare studies and extrapolate what variables caused the documented differences in 

vegetation and community health (Thorhaug et al., 1986; Runcie et al., 2004). 

Prevention and cleanup efforts could also affect the health of submerged vegetation communities 

(Zieman et al., 1984). Many physical prevention methods such as booms, barrier berms, and diversions 

can alter hydrology specifically changing salinity and water clarity. These changes would harm 

seagrasses because they are tolerant to certain salinities and light levels (Zieman et al., 1984; Kenworthy 

and Fonesca, 1996). There is increased boat and human traffic in these sensitive areas that generally are 

protected from this degree of human disturbance prior to the response. Increased vessel traffic would lead 

to elevated water turbidity and increased prop scarring. While the elevated levels of water turbidity 

would be short-term and the possible damages from propellers could be longer, both events would be 

localized during the prevention and cleanup efforts (Zieman, 1976; Dawes et al., 1997). Detailed 

sampling to evaluate the effects of the DWH event and associated prevention/cleanup efforts are 

occurring within the NRDA process. The information that is currently available about the current state of 

the submerged vegetation from Louisiana, Mississippi, Alabama, and Florida are found in Chapter 

4.1.1.5.1. 

Summary and Conclusion 

Although the probability of their occurrence is low, the greatest threat to inland, submerged 

vegetation communities would be from an inland spill resulting from a vessel accident or pipeline rupture. 

The resulting slick may cause short-term and localized impacts to the submerged vegetation bed. There is 

also the remote possibility of an offshore spill to such an extent that it could also affect submerged 

vegetation beds, and this would have similar effects to an inshore spill. Because prevention and cleanup 

measures can have negative effects on submerged vegetation, close monitoring and restrictions on the use 

of bottom-disturbing equipment would be needed to avoid or minimize those impacts. The floating 

nature of nondispersed crude oil, the regional microtidal range, dynamic climate with mild temperatures, 

and the amount of microorganisms that consume oil would alleviate prolonged effects on submerged 

vegetation communities. Also, safety and spill-prevention technologies continue to improve and will 

decrease detrimental effects to submerged vegetation from the proposed action. 
4-86 Central Planning Area Supplemental EIS 

4.1.1.5.4. Cumulative Impacts 

A detailed impact analysis for cumulative impacts in the CPA on submerged vegetation can be found 

in Chapter 4.5.3.3 of the Multisale EIS and in Chapter 4.1.3.3.4 of the 2009-2012 Supplemental EIS. The 

following is a summary and incorporates any new information that has become available since both 

documents were prepared. Of all of the activities in the cumulative scenario found in Chapter 3.3 of this 

Supplemental EIS, dredging, oil spills/pipelines, hydrological changes, and storm events present the 

greatest threat of impacts to submerged vegetation communities. 

Background/Introduction 

Generally dredging generates the greatest overall risk to submerged vegetation by uprooting and 

burying plants, decreasing oxygen in the water, and reducing water clarity in an area. Increased dredging 

in the CPA is expected only in areas that do not support submerged vegetation beds. Maintenance 

dredging would not have a substantial effect on existing seagrass habitat given that no new channels are 

expected to be dredged as a result of OCS activities in the CPA. Another anthropogenic activity that 

could cause adverse effects to submerged vegetation is accidental oil-spill events. These are generally 

rare and small-scale, but they do add to the possible cumulative damage to the submerged vegetation 

systems. Finally, historic and some recent construction of structures like levees and berms change local 

hydrology and that effects submerged vegetation beds. There has also been an increase in tropical 

cyclone events in the Atlantic. Hurricanes generate substantial overall risk to submerged vegetation by 

burial and eroding channels through seagrass beds. When combined with other stresses, impacted 

seagrass beds may fail to recover. 

In support of inshore petroleum development, the oil and gas industry and land developers perform 

most of the dredging that impacts lower salinity submerged vegetation in Louisiana and Texas. 

Mitigation may be required to reduce undesirable impacts of dredging to submerged vegetation. 

Maintenance dredging of navigation channels help sustains the impacts of original dredging. From 2007 

to 2046, offshore oil and gas activities are projected to generate 25-36 pipeline landfalls in Louisiana and 

1-3 pipeline landfalls for Mississippi and Alabama collectively (Table 4-9 of the Multisale EIS). Those 

numbers are equivalent to approximately one pipeline a year. The most effective mitigation for direct 

impacts to submerged vegetation beds is avoidance, but there are other mitigation techniques in place to 

lessen the effects from unavoidable disturbances. 

Inshore oil spills generally present a greater risk of adversely impacting submerged vegetation and 

seagrass communities than do offshore spills with regards to OCS activities in the CPA. However, if an 

offshore spill is of large magnitude like that of the DWH event, then oil could make contact with and have 

similar effects to submerged vegetation beds as an inshore spill. Although little to no direct permanent 

mortality of seagrass beds is expected as a result of oil-spill occurrences, contact of seagrasses with crude 

and refined oil has been implicated as a cause of the decline in plant biomass and cover, and a cause of 

the observed changes in species composition within them (Zieman et al., 1984; Erftemeijer and Lewis, 

2006). Because nondispersed oil floats and because of the local microtidal range, oil spills alone would 

typically have little impact on submerged vegetation beds and associated epifauna. During and after a 

spill event, the cleanup effort can cause significant scarring and trampling of submerged vegetation beds 

with increased traffic in the area. Also, preventative measures (booms, berms, and diversions) can alter 

water hydrology and salinity, which could harm the beds and their associated communities. 

Many of man’s activities have caused landloss either directly or indirectly by accelerating natural 

processes. Floodwaters layered sediment over the active Mississippi River deltaic plain, and this 

accretion countered ongoing submergence and also built new land. However, the river was channelized 

and leveed in the early 1900’s. Because of this anthropogenic effect, areas that did not receive sedimentladen floodwaters continually lost elevation. Further compounding this effect, the suspended sediment 

load in the Mississippi River has decreased more than 50 percent since the 1950’s, largely as a result of 

dam and reservoir construction and soil conservation practices in the drainage basin (Turner and Cahoon, 

1988). 

Saltwater intrusion, as a result of river channelization and canal dredging, is a major cause of coastal 

habitat deterioration (including submerged vegetation communities) (Boesch et al., 1994). Productivity 

and species diversity associated with SAV habitat in the coastal marshes of Louisiana are greatly reduced 

by saltwater intrusion (Stutzenbaker and Weller, 1989; Lirman et al., 2008). Due to increased salinities 
Description of the Environment and Impact Analysis 4-87 

farther up the estuaries, some salt tolerant species of submerged vegetation (including seagrasses) are able 

to populate areas farther inland and outcompete the dominant SAV species (Longley, 1994). Large shifts 

in salinities can decrease both seagrass and SAV populations, which decreases their ecological function 

for juvenile fishes and invertebrates. An example of a salinity shift that occurs in Louisiana is the 

opening of the Bonnet Carré Spillway to divert the Mississippi River flood waters into Lake Pontchartrain 

during high-water stages. This freshwater eventually flows into Mississippi and Chandeleur Sounds, 

lowering salinities there. In the past, spillway openings have been associated with a noticeable decrease 

in seagrass vegetation acreage (Eleuterius, 1987). Conversely, the Caernarvon Freshwater Diversion into 

the Breton Sound Basin, east of the River, provides more regular flooding events, which have reduced 

average salinities there. Reduced salinities there have triggered a large increase in acreage of submerged 

aquatic vegetation like R. maritima (Cho et al., 2009). 

When the Mississippi River is in flood condition, floodways may be opened to alleviate the threat of 

levee damage (e.g. Bonne Carré Spillway). The floodways of the Mississippi River direct water to 

estuarine areas where flood waters may suddenly reduce salinities for a couple of weeks to several 

months. This lower salinity can damage or kill high-salinity seagrass beds if low salinities are sustained 

for longer periods than the seagrass species can tolerate (Eleuterius, 1987). If this continues to happen, 

over time seagrass beds could become stressed and more vulnerable to other impacts. 

Submerged vegetation communities can be scarred by boat anchors, keels, and propellers, and by 

activities such as trampling, trawling, and seismic surveys (Sargent et al., 1995; Dunton et al., 1998). 

Loggerhead turtle, other large animals, and storm events can scar vegetated bottoms. A few State and 

local governments (Seagrass Outreach Partnership) have instituted management programs that have 

resulted in reduced scarring, which could decrease bed patchiness. 

Currently, there is a period of significant increased tropical cyclone activity in the Gulf of Mexico. 

These storms can remove or bury submerged beds and the barriers that protect them from storm surges. 

This could weaken the existing populations of local submerged vegetation. Seagrass beds have been 

repeatedly damaged by the natural processes of transgression from hurricane overwash of barrier islands. 

Storm-generated waves wash sand from the seaward side of the islands over the narrow islands and cut 

new passes through the islands. The overwashed sand buries seagrass beds on the back side of the 

islands. Cuts formed in the islands erode channels that remove seagrass in its path. Over time, seagrass 

recolonizes the new sand flats on the shoreward side, and the natural processes of sand movement rebuild 

the islands. Hurricane impacts can produce changes in seagrass community quality and composition. 

These increased tropical cyclone events coincide with the current period of global climate changes. 

Global climate change can increase surface temperature, increase sea levels, and increase storm events 

(Orth et al., 2006). Whether it is from anthropogenic activities or a cycle, it has effects on seagrass beds 

by adding stress to this sensitive and already stressed ecosystem (Orth et al., 2006). 

Summary and Conclusion 

In general, the CPA proposed action would cause a minor incremental contribution to impacts on 

submerged vegetation from dredging, pipeline installations, possibly oil spills, and boat scarring. 

Dredging generates the greatest overall risk to submerged vegetation, while naturally occurring hurricanes 

cause direct damage to beds. The implementation of proposed lease stipulations and mitigation policies 

that are currently in place, the small probability of an oil spill, and that flow regimes are not expected to 

change further reduce the incremental contribution of stress from the CPA proposed action on submerged 

vegetation. 

4.1.1.6. Live Bottoms 

4.1.1.6.1. Live Bottoms (Pinnacle Trend) 

A detailed description of live bottoms (Pinnacle Trend) can be found in Chapter 3.2.2.1.1 of the 

Multisale EIS. Updated information following Hurricanes Katrina and Rita (2005) is presented in 

Chapter 4.1.4.1.1 of the 2009-2012 Supplemental EIS. The BOEMRE recommends oil and gas operators 

to avoid contact with Pinnacle Trend features and provides a 100-ft (30-m) buffer zone as described in 

NTL 2009-G-39, “Biologically-Sensitive Underwater Features and Areas” (USDOI, MMS, 2009b). The 

following information is a summary of the resource description for the Pinnacle Trend incorporated from 
4-88 Central Planning Area Supplemental EIS 

the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has become available 

since both documents were prepared. 

4.1.1.6.1.1. Description of the Affected Environment 

The northeastern portion of the CPA exhibits a region of high topographic relief known as the 

“Pinnacle Trend” at the outer edge of the Mississippi-Alabama shelf between the Mississippi River and 

De Soto Canyon. The Pinnacle Trend spreads over a 103 x 26 km area (64 x 16 mi) in water depths of 

60-200 m (200-650 ft) (Figure 4-4). It includes pinnacles, flat-top reefs, patch reefs, reef-like mounds, 

and isobath parallel ridges (Sager et al., 1992; Brooks and Giammona, 1990; CSA, 1992a). 

The shape and configuration of these structures is similar to tropical coral reef formations. Early 

investigators of this area in 1957 hypothesized that they are “drowned calcareous reefs” (Ludwick and 

Walton, 1957). Drowned reefs are reefs that were shallow carbonate reefs long ago but their vertical 

growth has been outpaced by sea-level rise and seafloor subsidence, resulting in a skeletal reef structure 

in water too deep and dark to support a living coral reef (Schlager, 1981). More recent studies using 

dredges, grab samples, and imaging have confirmed this evaluation. Some of these formations are tall 

and steep-sided in profile. The taller mounds tend to have more complex shapes with pits and overhangs, 

in addition to flat tops and vertical sides (CSA and GERG, 2001). 

Pinnacle Trend features consist of both high-relief outcroppings at the edge of the MississippiAlabama shelf and low-relief hard bottoms on the inner and middle shelf. High-relief features consist of 

pinnacles, flat-top reefs, reef-like mounds, patch reefs, and isobath-parallel ridges. The high-relief 

features are complex in shape and structure and provide varied zones of microhabitat for attached 

organisms. Low-relief features include fields of small seafloor mounds that rise only a meter or two from 

the seafloor but provide hard surfaces for encrusting and attached epifauna. Both high- and low-relief 

features are relict features that developed prior to the most recent sea-level rise and do not support active 

reef-building activity (Thompson et al., 1999). Fields of shallow depressions about 1 to 5-6 m across 

(3-20 ft) also add complexity to the overall character of the Pinnacle Trend area. 

The eastern part of the pinnacles area is covered with a thin, well-sorted layer of fine- to mediumgrained quartzose sand from eastern continental rivers. The western portion is covered with fine silts, 

sands, and clays deposited by the Mississippi River (CSA, 1992a). The linear orientation and distribution 

of pinnacles correspond with depth contours and may represent a historic shoreline. The rocky pinnacles 

provide a surprising amount of surface area for the growth of sessile invertebrates and attract large 

numbers of fish. Additional areas of hard bottom are located nearby on the continental shelf, outside the 

Pinnacle Trend. These low-relief, hard bottom areas are discussed in Chapter 4.1.1.6.2.1. 

The BOEMRE has sponsored numerous studies providing information about these features (Brooks, 

1991; CSA, 1992a; Thompson et al., 1999; CSA and GERG, 2001). A recent bathymetric survey by 

USGS has provided accurate, up-to-date imaging of the seafloor of the region (Gardner et al., 2002a). 

The Pinnacle Trend covers 74 lease blocks in the CPA, which is where BOEMRE has applied the Live 

Bottom (Pinnacle Trend) Stipulation to protect the ecosystem (Figure 4-4). This area includes portions of 

the continental shelf, shelf break, and upper continental slope. The outer limit of the continental shelf is 

delineated by the 75-m (246-ft) depth contour. Figure 3-4 of the Multisale EIS provides a perspective 

view of the central sector of the Mississippi-Alabama continental shelf. The BOEMRE recommends the 

application of the Live Bottom (Pinnacle Trend) Stipulation for a proposed action within 1 of the 74 OCS 

lease blocks that has Pinnacle Trend features. 

Pinnacles 

Tall spire-like mounds are the historical “pinnacles” for which the region is named. Figure 4-5

shows a drawing of a pinnacle in the foreground. The pinnacles rise up to 20 m (66 ft) in height and can 

be over 500 m (1,640 ft) in diameter (Thompson et al., 1999; Brooks, 1991). They are scattered along the 

74- to 82-m (243- to 269-ft) depth range and also extend laterally for over 28 km (17 mi) at the 105- to 

120-m (345- to 394-ft) depth band (Thompson et al., 1999; Schroeder, 2000). The sides are steep and 

provide surface area for biological growth (CSA, 1992a). Pinnacles may have formed from coral-algal 

assemblages during a rapid sea-level rise (Brooks, 1991). 
Description of the Environment and Impact Analysis 4-89 

Patch Reefs 

Patch reefs are small mushroom-shaped features about 2-12 m (6-39 ft) in diameter and 3-4 m 

(10-13 ft) in height that occur in many areas (Figure 3-4 of the Multisale EIS). They are particularly 

abundant in fields of as many as 35-70 features per hectare (2.47 ac) along the 74- to 82-m (243- to 

269-ft) depth contour in two separate fields on the western portion of the shelf (Brooks, 1991; Schroeder, 

2000). 

Flat-Top Reefs 

Flat-top reefs (Figure 3-4 of the Multisale EIS) are large reef-like structures that occur along the same 

depth contour as patch reefs (74-82 m; 243-269 ft) and follow the shelf edge for a distance of over 70 km 

(43 mi) (Brooks, 1991). They are located in the west-central region of the Mississippi-Alabama shelf 

(Schroeder, 2000). The reefs range from 75 to 700 m (245 to 2,300 ft) in diameter and from 7 to 14 m 

(23 to 46 ft) in height. The structures have steep sides like the pinnacles, but are flat on top. The flat tops 

of these features are all at essentially the same depth of 66 m (216 ft), which was probably at the sea 

surface during their period of formation (Sager et al., 1992). 

Reef-Like Mounds 

Pinnacles and flat-top reefs fall into the category of reef-like mounds; however, these formations are 

also present elsewhere (Thompson et al., 1999). Figure 3-4 of the Multisale EIS shows examples of these 

features. Several clusters are found shoreward in 60-70 m (197-230 ft) of water. In the western part of 

the pinnacle area, two clusters of reef-like mounds are found at the 87- to 94-m (285- to 308-ft) depth 

range (Figure 3-4 of the Multisale EIS) (Brooks, 1991). The mounds are 4 m (13 ft) high and 10-70 m 

(33-230 ft) wide. These features are also present along the western rim of the De Soto Canyon at depths 

of 70-80 m (230-262 ft) (Schroeder, 2000). 

Ridges and Scarps 

Ridges (Figure 4-6) are the largest features in the area and are found between the 68- and 76-m (223- 

to 249-ft) depth range (Schroeder, 2000). Linear ridges paralleling the isobaths are reported in various 

depths (Brooks, 1991; Thompson et al., 1999). These ridges are typically about 20 m (66 ft) wide (up to 

250 m [820 ft]) and over 1 km (0.6 mi) long. Some ridges are 15 km (9 mi) long (Schroeder, 2000). 

Most of the ridges are low relief, around 1 m (3 ft) in height. Brooks (1991) found a ridge with scarps up 

to 8 m (26 ft) high in depths around 60 m (197 ft). They often occur in groups of 6-8 ridges together. 

They appear to be calcareous biogenic features formed during periods of slow sea-level rise during the 

last deglaciation (Sager et al., 1992), possibly from lithified coastal dunes (Thompson et al., 1999). 

Shallow Depressions 

Shallow depressions are another type of low-relief feature common in the pinnacle area, particularly 

to the west of the large pinnacle features (Figure 3-4 of the Multisale EIS). These occur in large fields 

that do not follow depth contours. The formations are found in large clusters (up to 80 per km2

) (Sager et 

al., 1992). They are usually irregularly shaped with bumpy rims, 5-10 m (16-33 ft) across, and probably 

less than a meter in depth. It is thought that they are formed by the collapse of sediments following gas 

expulsion (Brooks, 1991). 

Nepheloid Layer 

A persistent nepheloid layer characterized by high turbidity was identified as a controlling factor for 

hard-bottom communities in the northwestern Gulf of Mexico (Rezak et al., 1985). The nepheloid layer 

is a heavy layer of turbid water laden with sediment that is carried along by water currents above the 

seafloor. This layer reduces the light reaching the reef, resulting in decreased epibiota and reef fish 

species richness and abundance below 80 m (262 ft) (Dennis and Bright, 1988; Rezak et al., 1990). 

Previous studies have suggested that the Mississippi River plume influences the distribution and 
4-90 Central Planning Area Supplemental EIS 

abundance of sessile invertebrates within 70 km (43 mi) of the river delta and may produce a gradient of 

sedimentation and water-column turbidity throughout the Pinnacle Trend (Gittings et al., 1992a; CSA and 

GERG, 2001). In the northeastern Gulf, nepheloid layers are infrequent; although in conjunction with 

episodic Mississippi freshwater plumes and upwelling, they result in increased light attenuation (CSA and 

GERG, 2001). 

Ecology of the Pinnacle Trend Area 

The pinnacles provide a significant amount of hard substrate for colonization by suspension-feeding 

invertebrates and support relatively rich live-bottom and fish communities. Assemblages of coralline 

algae, sponges, octocorals, crinoids, bryozoans, and fishes are present at the tops of the shallowest 

features in water depths of less than 70 m (230 ft) (CSA, 1992a). On the deeper features, as well as along 

the sides of these shallower pinnacles, ahermatypic corals may be locally abundant, along with octocorals, 

crinoids, and basket stars. The diversity and abundance of the associated species appear to be related to 

the size and complexity of the features, with the low-relief rock outcrops (<1 m [3 ft] height) typically 

having low faunal densities, and higher relief features having the more diverse faunal communities 

(Gittings et al., 1992a; Thompson et al., 1999). 

Environmental Influences on the Pinnacle Trend Area 

Substrate characteristics and turbidity seem to be the major factors determining the composition of 

communities at different locations and depth levels in the Pinnacle Trend. The biological communities on 

the Pinnacle Trend become more diverse toward the east and with greater distance from the Mississippi 

River (Gittings et al., 1992a). This is a matter of both substrate and turbidity. The Mississippi River 

brings a large load of fine silty sediment to the Gulf of Mexico. Although the majority of this turbidity is 

swept to the west by currents, it does affect the communities to the east. Sometimes the pattern is 

reversed with the majority swept to the east. Previous studies have suggested that the Mississippi River 

plume influences the distribution and abundance of sessile invertebrates within 70 km (43 mi) of the river 

delta and may produce a gradient of sedimentation and water-column turbidity throughout the Pinnacle 

Trend (Gittings et al., 1992a; CSA and GERG, 2001). 

In addition, a nepheloid layer (heavy bottom turbidity layer), common in the western Gulf of Mexico, 

sometimes affects the Pinnacle Trend (Weaver et al., 2002). Resuspension of sediments is a major 

contributor to turbidity in the Pinnacle Trend. This is more severe in the western part of the Pinnacle 

Trend area because currents and wave action resuspend the silty sediments deposited by the Mississippi 

River. 

Because of the depth of the bottom (60-120 m; 200-400 ft) in the Pinnacle Trend area, waves seldom 

have a direct influence. During severe storms, such as hurricanes, large waves may reach deep enough to 

stir bottom sediments. These forces are not expected to be strong enough to cause direct physical damage 

to organisms living on the reefs. Rather, currents are created by the wave action that can resuspend 

sediments to produce added turbidity and sedimentation (Brooks, 1991; CSA, 1992a). The animals in this 

region are well-adapted to the effects common to this frequently turbid environment. The end result of 

these factors is that benthic communities closer to the Mississippi River are less diverse (CSA, 1992a). 

Diversity and density of epibenthic organisms varies considerably between features in the Pinnacle 

Trend area. The general trend is less turbidity and greater biological development toward the east. In 

addition, the sediment is less silty to the east. This results in an increase of diversity and density of 

organisms to the east. Other factors, such as areas with more exposed hard bottom, vertical relief, 

rugosity, and complexity of the substrate contribute to higher biological diversity and density. 

The association of multiple features in proximity to one another makes an area more biologically 

diverse and promotes higher densities of organisms than an area with fewer, more scattered features 

(Gittings et al., 1992a). The Pinnacle Trend is a system of exposed hard substrates. Low-relief mounds, 

patch reefs, flat-top reefs, tall pinnacles, and ridge formations are often found in groups or clusters, 

creating a cumulative environment (Brooks, 1991). The reefs are richer because they are in proximity to 

each other. Even solitary, simple, low-relief mounds support low-diversity assemblages, which combine 

with major features to form a large reef tract. The Pinnacle Trend forms a major ecosystem with an 

influence that pervades the wider regional ecosystem. 
Description of the Environment and Impact Analysis 4-91 

Pinnacle Zonation 

The characteristics of the substrate have a high degree of control over the composition of the 

biological communities that live on it. The features of the Pinnacle Trend are composed of carbonate reef 

material (Ludwick and Walton, 1957) and vary in shape, size, and vertical relief. The more complex the 

topographic shape of the substrate, the greater the variety of habitats for organisms and thus more highdensity, biologically diverse communities. Shallow depressions and low mounds harbor some organisms, 

but the potential is limited. A pinnacle 20 m (66 ft) tall with slopes, cliffs, crevices, and overhangs may 

host the maximum number of species and a high density of animals (Gittings et al., 1992a). The bottom 

of a tall pinnacle will have very low diversity with mostly upright species present, such as comatulid 

crinoids; the ahermatypic hard coral, Rhizopsammia manuelensis; the black corals, Antipathes spp. and

Cirrhipathes sp.; and the gorgonian, Ellisella sp. (Gittings et al., 1992a). The roughtongue bass, 

Pronotogrammus martinicensis, is the dominant fish at the base of pinnacles. Other common fish near 

the bottom are the red barbier, Hemanthias vivanus; cubbyu, Pareques umbrosus; bigeye soldierfish, 

Ostichthys trachpoma; and wrasse bass, Liopropoma eukrines (Weaver et al., 2002). 

Features tall enough to rise above the common effects of turbidity have higher community diversity 

and density. At least 34 different epibenthic species were found during one study of the shelf-edge 

features (CSA, 1992a). Vertical walls were densely populated by R. manuelensis, with frequent 

occurrence of Antipathes spp., Cirrhipathes luetkeni, and Ellisella sp. Some other ahermatypic stony 

corals were also seen, including Madrepora carolina, Madracis myriaster, Oculina diffusa, and a solitary 

cup coral, possibly Balanophyllia floridana. Comatulid crinoids were also observed. This zone was 

dominated by the roughtongue bass and red barbier (Weaver et al., 2002). 

The crests of the pinnacles are perhaps slightly more diverse than the walls. The same dominant 

species were seen as on the walls, with the common addition of the gorgonian coral, Bebryce sp. (Gittings 

et al., 1992a). Species richness is high at the crest of pinnacles, and R. manuelensis is very common. 

Coralline algae occur on hard substrates above about 78-m (256-ft) depth (Gittings et al., 1992a). The 

crests and walls of pinnacles are dominated by low-growing, ahermatypic hard corals. Fish communities 

on pinnacle crests are dominated by the red barbier; roughtongue bass; Gobiidae; greenband wrasse, 

Halichoeres bathyphilus; and yellowtail reeffish, Chromis enchrysura (Weaver et al., 2002). 

Horizontal surfaces provide surface area for considerably higher biological cover than vertical 

surfaces. This is likely because a greater number of individuals are able to settle and colonize a 

horizontal surface (Gittings et al., 1992a). Dominant species are similar to those on the walls of the 

pinnacles. However, some species not present on vertical surfaces are found on horizontal surfaces, 

including several sponges (Geodia neptuni, Cinachyrella sp., and unidentified orange sponges) and a 

gorgonian coral, possibly Nicella sp. (Gittings et al., 1992a). The tops of reefs with extensive flat 

summits are dominated by the taller gorgonian corals, as well as by sponges and crinoids. It is likely that 

sedimentation limits the colonization of low-growing species on these horizontal surfaces, such as many 

of the ahermatypic hard corals (Gittings et al., 1992a). Dominant fish species on the flat tops include the 

red barbier, roughtongue bass, gobies, yellowtail reeffish, and greenband wrasse (Weaver et al., 2002). 

Pinnacle Trend Field Studies 

Within the Pinnacle Trend area, the feature known as “36 Fathom Ridge” was studied in some detail. 

The 36 Fathom Ridge is part of the Alabama Alps formation. Refer to Figure 4-7 for the location and 

topography of this feature. It is 250 m (820 ft) wide and 1 km (0.6 mi) long and oriented in a north-south 

direction (Brooks and Giammona, 1990). The feature has a maximum relief of 16 m (52 ft), with the base 

88 m (289 ft) below the sea surface and the crest 72 m (236 ft) below the surface (Weaver et al., 2002). 

The top of this feature is an irregular, fairly flat surface colonized by octocorals (Bebryce cinerea, 

Bebryce grandis, Nicella spp., Ellisella sp., Cirrhipathes sp., Antipathes atlantica, and Ctenocella spp.), 

crinoids (Stichopathes lutkeni and Antipathes sp.), gorgonians (Astrocyclus caecilian), ahermatypic coral 

(Rhizopsammia manuelensis), coralline algae, sea fans, ascidians, urchins, and sponges (G. neptuni) 

(CSA, 1992a; Thompson et al., 1999; Hardin et al., 2001). Flat sections of this feature are also covered 

by a silt to sand sediment veneer. The steep sides of the feature are dominated by a dense cover of 

Rhizopsammia manuelensis, a solitary coral. Comatulid crinoids, soft corals (Antipathes spp., 

Cirrhipathes luetkeni), some nonreef-building hard corals (Madracis myriaster, Oculina diffusa), 

coralline algae, and sponges are also present (CSA, 1992a; Thompson et al., 1999; Harden et al., 2001). 
4-92 Central Planning Area Supplemental EIS 

The walls of the feature were interspersed by some flat areas supporting even greater live cover including 

sponges (Geodia neptuni, Cinachtrella sp.), in addition to the vertical wall organism assemblage. The 

base of the feature supported low live cover that included the ahermatypic black coral Rhizopsammia 

manuelensis, several species of the Antipatharian, Antipathes sp., and several species of comatulid 

crinoids (CSA, 1992a; Thompson et al., 1999). 

Other ridges smaller than 36 Fathom Ridge had very similar composition and amount of live cover to 

the 36 Fathom Ridge (CSA, 1992a). One of the mound-like features described by CSA (1992a) was 

located in water 94 m (308 ft) deep, was 11 m (36 ft) tall, 200 m (656 ft) wide, and 250 m (820 ft) long. 

The most common species colonizing the lower parts of the mound was R. manuelensis. There were also 

soft corals (Ellisella sp., Cirrhipathes sp.), comatulid crinoids, and antipatharians. Higher up on the 

mound, there was a greater density of R. manuelensis, together with the nonreef-building corals 

(Madrepora carolensis, M. myriaster, and Oculina sp.), antipatharians (Antipathes sp.), comatulid 

crinoids, and soft corals (Nicella sp.). 

Roughtongue Reef (Figure 4-8) is an elliptical feature with a 400-m (1,300-ft) diameter base, a flat 

top covered with sediment, and steep sides (Weaver et al., 2002). A smaller reef is attached to the south. 

Roughtongue Reef has a maximum relief of 14 m (46 ft), with the base at 78 m (256 ft) below the sea 

surface and the crest at 64 m (210 ft) below the surface (Weaver et al., 2002). Bioturbation from infaunal 

benthic organisms has been reported in the sediment on the top of the reef (Hardin et al., 2001). 

Organisms living on top of the reef are diverse and include octocorals (Bebryce cinera, Bebryce grandis, 

Nicella spp., Thesea sp., Stenogorgiinae, and Ctenocella spp); sponges (Ulosa sp., Dysidea sp., and 

Ircinia campana); crinoids; ectoprocts (Cellaria sp. and Idmidronea sp.); and an antipatharian spiral whip 

(Stichopathes lutkeni) (Hardin et al., 2001). The sides of Roughtongue Reef have a lower density of 

organisms and are dominated by R. manuelensis. The base of the feature also had R. manuelensis, along 

with octocoral fans and coral (Madracis sp., Oculina sp., and Ctenocella spp.) (Hardin et al., 2001). The 

roughtongue bass is also abundant here (Weaver et al., 2002). 

4.1.1.6.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with the CPA 

proposed action on Pinnacle Trend communities is presented in Chapter 4.2.2.1.4.1.1 of the Multisale EIS 

and in Chapter 4.1.4.1.2 of the 2009-2012 Supplemental EIS. The routine activities associated with the 

proposed action that would impact Pinnacle Trend communities in the CPA include anchoring, 

infrastructure and pipeline emplacement, infrastructure removal, drilling discharges, and produced-water 

discharges. The following is a summary of the information presented in the Multisale EIS and the2009-

2012 Supplemental EIS, which incorporates new information found since publication of the Multisale EIS 

and the 2009-2012 Supplemental EIS and in consideration of the DWH event. 

Seventy-four blocks are within the region defined as the Pinnacle Trend, which contains live bottoms 

that may be sensitive to oil and gas activities. These blocks are located in the northeastern portion of the 

CPA and are located in water depths between 60 and 120 m (197 and 394 ft) in the Main Pass, Viosca 

Knoll, and Destin Dome lease areas. Relevant leases in past sales have contained a Live Bottom 

(Pinnacle Trend) Stipulation to protect such areas. The proposed Live Bottom (Pinnacle Trend) 

Stipulation is presented in Chapter 2.4.1.3.2 as a potential mitigating measure for leases resulting from 

the proposed action. The BOEMRE recommends the implementation of the Live Bottom (Pinnacle 

Trend) Stipulation for a proposed action within 1 of the 74 OCS lease blocks that has Pinnacle Trend 

features. The stipulation is designed to prevent drilling activities and anchor emplacement (the major 

potential impacting factors on these live bottoms resulting from offshore oil and gas activities) from 

damaging the pinnacle features. Under the stipulation, both exploration and development plans will be 

reviewed on a case-by-case basis to determine whether a proposed operation could impact a pinnacle 

feature. If it is determined from site-specific information derived from BOEMRE studies, published 

information from other research programs, geohazards survey information, or another source that the 

operation would impact a pinnacle feature, the operator may be required to relocate the proposed 

operation. 

Although the Live Bottom (Pinnacle Trend) Stipulation is regarded as a highly effective protection 

measure, infrequent impacts are possible. Impacts may be caused by operator positioning errors or when 
Description of the Environment and Impact Analysis 4-93 

studies and/geohazards information are inaccurate or fail to note the presence of pinnacle features. One 

such incident has been documented and is discussed in further detail below. While investigating sites of 

previous oil and gas drilling activities, Shinn et al. (1993) documented that a lease operator had located an 

exploratory well adjacent to a medium-relief pinnacle feature; the reason for this occurrence is still 

undetermined. In spite of this documented instance, the stipulation is still considered effective since it 

allows BOEMRE flexibility to request any surveys or monitoring information necessary to ensure 

protection of these sensitive areas. The impact analysis presented below is for routine activities 

associated with the CPA proposed action and includes the proposed Live Bottom (Pinnacle Trend) 

Stipulation. 

A number of OCS-related factors may cause adverse impacts on the live-bottom communities and 

features. Damage caused by anchoring, infrastructure and pipeline emplacement, infrastructure removal, 

blowouts, drilling discharges, produced-water discharges, and oil spills can cause the immediate mortality 

of live-bottom organisms or the alteration of sediments to the point that recolonization of the affected 

areas may be delayed or impossible. Accidental impacts from oil spills and blowouts are discussed in 

Chapter 4.1.1.6.1.3. 

Construction Impacts on Pinnacle Trend Features 

Anchoring may damage lush biological communities or the structure of the live-bottom features 

themselves, which attract fish and other mobile marine organisms. Anchor damage from support boats 

and ships, floating drilling units, and pipeline-laying vessels greatly disturb areas of the seafloor and are 

the greatest threats to live-bottom areas at these depths. The size of the affected area would depend on 

water depth, anchor and chain sizes, chain length, method of placement, wind, and current. Anchor 

damage may result in the crushing and breaking of hard bottoms and associated communities. It may also 

result in community alteration through reduced or altered substrate cover, loss of sensitive species, and a 

reduction in coral cover in heavily damaged areas (Dinsdale and Harriott, 2004). Anchoring often 

destroys a wide swath of habitat by being dragged over the seafloor or by the vessel swinging at anchor, 

causing the anchor chain to drag over the seafloor (Lissner et al., 1991). Damage to corals as a result of 

anchoring may take 10 or more years to recover, depending on the extent of the damage (Fucik et al., 

1984; Rogers and Garrison, 2001). Nearby species on these hard-bottom habitats that disperse larvae 

short distances, such as solitary species (cup corals, octocorals, and hydrocorals) may recolonize areas 

more rapidly than slow-growing colonial forms that disperse larvae great distances (Lissner et al., 1991). 

Pinnacle features would be protected from possible anchor damage through NTL 2009-G39. The 

proposed Live Bottom (Pinnacle Trend) Stipulation states that no bottom-disturbing activities are 

permitted within 30 m (100 ft) of the hard-bottom feature. Therefore, anchoring damage would only 

occur if the proposed stipulation is not followed. 

The emplacement of infrastructure, including drilling rigs and platforms, on the seafloor would crush 

the organisms directly beneath the legs or mat used to support the structure. Pipeline emplacement 

directly affects the benthic communities by crushing it under the pipeline or trenching and burial of the 

pipeline (in less than 60 m [200 ft] water depth) and the resultant resuspension of sediments. These 

resuspended sediments may obstruct filter-feeding mechanisms and gills of fishes and sedentary 

invertebrates. The areas affected by the placement of the platforms and rigs are predominantly softbottom regions where the infaunal and epifaunal communities are not unique as the hard-bottom 

communities. 

Infrastructure and pipeline emplacement could result in suspended sediment plumes and sediment 

deposition on the seafloor. Considering the relatively elevated amounts of drilling muds and cuttings 

discharged per well (approximately 2,000 metric tons [2,205 tons] for exploratory wells—900 metric tons 

[992 tons] of drilling fluid and 1,100 metric tons [1,213 tons] of cuttings—and slightly lower discharges 

for development wells) (Neff, 2005), potential impacts on biological resources of hard-bottom features 

should be expressly considered if drill sites occur in blocks containing such features. Potential impacts 

could be incurred through increased water-column turbidity, the smothering of sessile benthic 

invertebrates, and local accumulations of contaminants. 

Differences in the dispersal patterns for well cuttings and drilling muds would result from differences 

in disposal methodology (surface disposal or bottom shunting). For example, well cuttings that are 

disposed of at the water’s surface tend to disperse in the water column and are distributed widely over a 
4-94 Central Planning Area Supplemental EIS 

large area at low concentrations (CSA, 2004b; NRC, 1983). On the other hand, cuttings that are shunted 

to the seafloor are concentrated over a smaller area in piles instead of being physically dispersing over 

wide areas (Neff, 2005). The heaviest concentrations of well cuttings and drilling fluids, for both waterbased and synthetic-based drilling muds, have been reported within 100 m (328 ft) of wells and are shown 

to decrease beyond that distance (CSA, 2004b; Kennicutt et al., 1996). They are usually distributed 

unevenly and in patches, often dependent on prevailing currents (CSA, 2004b). A gradient of deposition 

may reach up to 500 m (1,640 ft) from the well, depending on surrounding environmental conditions 

(Kennicutt et al., 1996). 

Although the Live Bottom (Pinnacle Trend) Stipulation requires that no drilling be conducted within 

30 m (98 ft) of pinnacles, some cuttings may reach the live-bottom features. Surface-released cuttings 

rarely accumulate thicknesses of about 1 m (3 ft) immediately adjacent to the well; thicknesses are usually 

not higher than a few tens of centimeters (about 1 ft) in the GOM. A gradient of cuttings that 

encompasses most of the cuttings settles within 100 m (328 ft) of the well site. Cuttings settle in a patchy 

distribution determined by water currents and limited to about 250 m (820 ft) from the well site (CSA, 

2004b). Cuttings released at the surface, which are accumulating on the seafloor, should not completely 

cover organisms on pinnacles because the pinnacles have several meters relief above the seafloor and the 

organisms are those adapted to high levels of sedimentation. 

In order to protect live-bottom features, the relocation of operations to avoid live-bottom areas, 

shunting drilling fluids and cuttings to avoid live-bottom areas, transportation of drilling fluids and 

cuttings to approved disposal sites, and/or site monitoring may be required. These measures would limit 

or prevent well drilling activities from occurring in sensitive live-bottom areas. If bottom shunting of 

cuttings is used to protect features, the live-bottom areas would experience little sedimentation. Also, the 

USEPA general NPDES permit sets special restrictions on discharge rates for muds and cuttings to 

protect biological features. Chapters 4.1.1.4.1 and 4.2.1.1.2.2 of the Multisale EIS detail the NPDES 

permit’s general restrictions and the impacts of drilling muds and cuttings on offshore water quality and 

seafloor sediments. If cuttings and drilling fluids are transported to approved disposal sites, the live 

bottoms would be even further protected from sedimentation. Due to the Live Bottom (Pinnacle Trend) 

Stipulation and USEPA discharge regulations, turbidity and smothering impacts of sessile invertebrates 

on hard-bottom features caused by drilling muds and cuttings are anticipated to be minimized. 

Drilling fluid adhering to cuttings forms plumes that are rapidly dispersed on the OCS. 

Approximately 90 percent of the material discharged (cuttings and drilling fluid) settle rapidly to the 

seafloor, while 10 percent forms a plume of fine mud that drifts in the water column (Neff, 2005). 

Although drilling mud plumes may be visible 1 km (0.6 mi) from the discharge, rapid dilution of drilling 

mud plumes was reported within 6 m (20 ft) from the release point (Shinn et al., 1980; Hudson et al., 

1982). Drilling muds and cuttings may be diluted 100 times at a distance of 10 m (33 ft) from the 

discharge and 1,000 times at a distance of 100 m (328 ft) from the discharge (Neff, 2005). Dilution 

continues with distance from the discharge point, and at 96 m (315 ft) from the release point, a plume was 

measured only a few milligrams/liter above background suspended sediment concentrations (Shinn et al., 

1980). Suspended sediment concentrations 6 m (20 ft) from the discharge are often less than those 

produced during storms or from boat wakes (Shinn et al., 1980). With consideration that drilling is not 

allowed within 30 m (100 ft) of pinnacles and considering that field measurements of suspended solids 

rapidly decline with distance from the source, turbidity impacts to live-bottom communities should be 

minimized. 

It is not anticipated that muds drifting in the water column would exceed the natural turbidity levels in 

the Pinnacle Trend areas. The Pinnacle Trend community exists in a relatively turbid environment, 

starting just 65 km (40 mi) east of the mouth of the Mississippi River and trending to the northeast. The 

organisms in this area are tolerant of turbid environments (Rogers, 1990; Gittings et al., 1992a) and 

should not be impacted by the residual suspended sediment discharged during the drilling of a well. 

Many of the organisms that predominate in these communities also grow tall enough to withstand the 

sedimentation that results from their typical turbid environment or they have flexible structures that 

enable the passive removal of sediments (Gittings et al., 1992a). Their structure would also enable them 

to withstand the turbidity that may reach the live bottoms as a result of drilling of a well. Any mud that 

may reach these organisms can be removed by tentacle motion and mucus secretion (Shinn et al., 1980; 

Hudson and Robbin, 1980). 
Description of the Environment and Impact Analysis 4-95 

The resilience of some of the species found on pinnacle features was reported by Shinn et al. (1993). 

An exploratory well site erroneously located immediately adjacent to a 4-5 m (13-16 ft) high pinnacle 

feature, located at a water depth of 103 m (338 ft) was surveyed. Cuttings and drill debris were 

documented within 6,070 m2

 (1.5 ac) surrounding the drill site. In spite of being inundated by drill muds 

and cuttings 15 months prior to the investigation, the pinnacle feature was found to support a diverse 

community, which included gorgonians, sponges, nonreef-building stony corals, a species of horn coral, 

and abundant meter-long whip-like antipatharians characteristic of tropical hard-bottom communities in 

water depths of 30 m (100 ft) or greater. Shinn et al. (1993) concluded the following: “Gorgonians, 

antipatharians, crinoids, and non-reef-building corals attached to the pinnacle feature adjacent to the drill 

site as well as nearby rock bottom did not appear to be affected.” Shinn et al. (1993) acknowledged that 

their evaluation of the drill site was constrained both by the lack of baseline data on the live-bottom 

community prior to inundation by drilling discharges and by the need for a study on long-term changes 

(e.g., 10 years). 

Recruitment studies conducted by Continental Shelf Associates (CSA) and Texas A&M University, 

Geochemical and Environmental Research Group (GERG); Marine Resources Research Institute (MRRI); 

and others suggest that recovery of hard-bottom communities following physical damage will be slow 

(CSA and GERG, 2001; MRRI, 1984; Montagna and Holmberg, 2000). Hard-bottom communities 

studied during the Mississippi/Alabama Pinnacle Trend Ecosystem Monitoring Program exhibit a 

dynamic sedimentary environment with relatively little net growth of the epibiota associated with the 

pinnacle features. Deeper habitats have slower rates of settlement, growth, and community development, 

and recruitment rates are reportedly slow in the pinnacle habitat (Montagna and Holmberg, 2000; CSA 

and GERG, 2001). 

Epibiont recruitment showed relatively slow development of fouling community constituents on 

recruitment plates. Early colonizers are opportunistic epifauna, such as hydroids, bryozoans, barnacles, 

and bivalves that are tolerant of sediment loading (CSA and GERG, 2001; MRRI, 1984). Basically, only 

the earliest successional stages were observed after 1 year (MRRI, 1984) and after 27 months of exposure 

(CSA and GERG, 2001), and the epibiota typically associated with nearby hard-bottom features were rare 

on the plates (CSA and GERG, 2001). No sponges or corals had settled after 1 year (MRRI, 1984). 

Corals and sponges are known to display delayed recruitment and slow growth, and after 10 years, corals 

and anemones were sparse on artificial reef habitats and the community had still not reached “climax” 

state (MRRI, 1984). 

It is not known whether the results of the recruitment studies would have differed if the substrate had 

consisted of exposed patches of natural hard bottom; however, because analysis of artificial reefs exposed 

for months to several years also indicates slow community development, it can be anticipated that hardbottom communities take a long time to recruit and develop (MRRI, 1984). Although settling plates and 

artificial reefs may differ from natural reefs, they can help to indicate recruitment time of a defaunated 

area (MRRI, 1984). This recruitment data indicates that, even though one survey showed thriving hardbottom communities adjacent to a well 15 months after the well was drilled, drilling discharges are still 

considered to have a deleterious impact on the live-bottom communities, and the Live Bottom (Pinnacle 

Trend) Stipulation would continue to be applied to minimize the possibility of similar occurrences. 

Long-Term and Operational Impacts on Pinnacle Trend Features 

Drilling operations may impact live-bottom communities. Drilling operations in Puerto Rico have led 

to reduced coral cover out to 65 m (213 ft) from the well, probably as a result of cutting deposition 

(Hudson et al., 1982). Corals beyond this distance did not show reduced surface cover (Hudson et al., 

1982). Live bottoms of pinnacle features may experience some deposition of cuttings, especially if a well 

is within a few hundred meters of a live bottom. Impacts as a result of cuttings disposal may reach 

100-200 m (328-656 ft) from a well (Montagna and Harper, 1996; Kennicutt et al., 1996). The proposed 

Live Bottom (Pinnacle Trend) Stipulation requires all bottom-disturbing activity to be at least 30 m 

(100 ft) from the pinnacles. This distance is within the deposition zone measured as a result of drilling 

operations in the Gulf of Mexico (Montagna and Harper, 1996; Kennicutt at al., 1996). If BOEMRE 

determines that the proposed activity may adversely impact the feature, then the lessee may be required to 

undertake protective measures (e.g., relocation of operations) or to monitor the potential impact. Further 

protection may be implemented if the cuttings and drilling fluids are transported to an approved disposal 
4-96 Central Planning Area Supplemental EIS 

site. The implementation of the Live Bottom (Pinnacle Trend) Stipulation is anticipated to reduce 

exposure pathways of drilling activities to benthic organisms on live bottoms, eliminating long-term 

operational impacts such as exposure to turbidity and sedimentation or associated contaminants. 

Impacts resulting from exposure to contaminants may occur to live-bottom organisms within 

100-200 m (328-656 ft) of the well as a result of offshore oil and gas production (Montagna and Harper, 

1996; Kennicutt et al., 1996; Hart et al., 1989; Kennicutt, 1995; CSA, 2004b). Sand content, metals, 

barium, inorganic carbon, and petroleum products have all been reported to be elevated near platforms 

(Kennicutt, 1995). Distribution of discharges tends to be patchy, have sharp gradients, and be directional 

(Kennicutt, 1995). The greatest impacts occur in low-energy environments where depositions may 

accumulate and not be redistributed (Neff, 2005; Kennicutt et al., 1996). 

Elevated levels of barium, silver, cadmium, mercury, lead, and zinc were found out to 200 m (656 ft) 

from platforms and are likely a product of drilling muds and cuttings (Kennicutt et al., 1996; Hart et al., 

1989; Chapman et al., 1991; CSA, 2004b). Metal concentrations in sediments near gas platforms 

(approximately out to 100 m [328 ft]) have been reported above those that may cause deleterious 

biological effects. The impacts are believed to be a result of metal toxicity originating from drill cuttings 

during the installation of the well, which remain in the sediment (Montagna and Harper, 1996; Carr et al., 

1996). Hydrocarbon enrichment has been reported within 25 m (82 ft) and out to 200 m (656 ft) of 

petroleum platforms, and the concentrations decreased with distance from the platforms (Hart et al., 1989; 

Chapman et al., 1991; Kennicutt, 1995; Kennicutt et al., 1996). The concentrations of PAH’s in the 

sediment surrounding platforms, however, were below the biological thresholds for marine organisms and 

appeared to have little effect on benthic organisms (Hart et al., 1989; McDonald et al., 1996; Kennicutt et 

al., 1996). If any of the drill cuttings reach live-bottom features, impacts from metal or hydrocarbon 

exposure may occur. Although the literature does not report the impacts to gorgonians or soft corals as a 

result of exposure to contaminants in cuttings, infauna has shown effects including reduced fecundity, 

altered populations, and acute toxicity (Montagna and Harper, 1996; Carr et al., 1996; Kennicutt et al., 

1996; Hart et al., 1989; Chapman et al., 1991; CSA, 2004b). Impacts to benthos would be reduced with 

distance from the discharge. 

Produced waters are discharged at the water surface throughout the lifetime of the production 

platform and may contain hydrocarbons, trace metals, elemental sulfur, and radionuclides (Kendall and 

Rainey, 1991). Heavy metals enriched in the produced waters include cadmium, lead, iron, and barium 

(Trefry et al., 1995). Produced waters may impact both organisms attached to the production platform 

and benthic organisms beneath the platform. A detailed description of the impacts of produced waters on 

water quality and seafloor sediments is presented in Chapter 4.2.1.1.2 of the Multisale EIS. 

Information is contradictory on the distance from a platform that produced waters can affect benthic 

communities. Impacts have been reported from 100 m (328 ft) of the source to 1 km (0.6 mi) from the 

source (Peterson et al., 1996; Armstrong et al., 1977; Osenberg et al., 1992). The produced waters, 

however, are rapidly diluted and impacts are generally only observed within the proximity of the 

discharge point (Gittings et al., 1992b). Literature indicates that acute toxicity that may result from 

produced waters occurs “within the immediate mixing zone around a production platform” (Holdway, 

2002). Past evaluation of the bioaccumulation of offshore produced-water discharges conducted by the 

Offshore Operators Committee (Ray, 1998) assessed that metals discharged in produced water would, at 

worst, affect living organisms found in the immediate vicinity of the discharge, particularly those attached 

to the submerged portion of platforms. Possibly toxic concentrations of produced water were reported 

20 m (66 ft) from the discharge in both the sediment and the water column where elevated levels of 

hydrocarbons, lead, and barium occurred; no impacts to marine organisms or sediment contamination 

were reported beyond 100 m (328 ft) of the discharge (Neff and Sauer, 1991; Trefry et al., 1995). 

Chronic exposure to produced waters may result in altered benthic communities, favoring opportunistic 

species, altered species behavior, reduced growth, and decreased fecundity (Holdway, 2002). 

Naturally occurring radioactive material in produced water was not found to bioaccumulate in marine 

animals (2 species of mollusks and 5 species of fish) (Ray, 1998). Because high-molecular PAH’s are 

usually in such dilute concentrations in produced water, they pose little threat to marine organisms and 

their constituents, and they were not anticipated to biomagnify in marine food webs. Monocyclic 

hydrocarbons and other miscellaneous organic chemicals are known to be moderately toxic, but they do 

not bioaccumulate to high concentrations in marine organisms and are not known to pose a risk to their 

consumers (Ray, 1998). 
Description of the Environment and Impact Analysis 4-97 

Produced waters may have some impact on live-bottom features, but the Live Bottom (Pinnacle 

Trend) Stipulation should help to reduce these impacts. The greatest impacts are reported adjacent to the 

discharge and out to 20 m (66 ft) from the discharge, but they are substantially reduced less than 100 m 

(328 ft) from the discharge. Because no bottom-disturbing activities are permitted within 30 m (100 ft) of 

the pinnacles, produced waters would not be discharged within 30 m (100 ft) of the pinnacles. Since 

produced waters are rapidly dispersed, the distance between the pinnacles and the discharge would allow 

for dispersion of the produced waters, reducing the concentration of discharged material to which the 

pinnacles may be exposed. The USEPA general NPDES permit restrictions on the discharge of produced 

water would also help to limit the impacts on biological resources of live bottoms. 

Structure-Removal Impacts on Pinnacle Trend Features 

The impacts of structure removal on live-bottom benthic communities can include turbidity, sediment 

deposition, explosive shock-wave impacts, and scouring from trawling to retrieve debris. Both explosive 

and nonexplosive removal operations would disturb the seafloor by generating considerable turbidity. 

Suspended sediment may evoke physiological impacts in benthic organisms including “changes in 

respiration rate, abrasion and puncturing of structures, reduced feeding, reduced water filtration rates, 

smothering, delayed or reduced hatching of eggs, reduced larval growth or development, abnormal larval 

development, or reduced response to physical stimulus” (Anchor Environmental CA, L.P., 2003). The 

higher the concentration of suspended sediment in the water column and the longer the sediment remains 

suspended, the greater the impact. 

Sediment deposition that occurs in ahermatypic (nonreef-building) coral communities may smother 

benthic organisms, decreasing gas exchange, increasing exposure to anaerobic sediment, and causing 

physical abrasion (Wilber et al., 2005). Corals may experience reduced coverage, changes in species 

diversity and dominance patterns, alterations in growth rates and forms, decreased calcification, increased 

production of mucus, lesions, reduced recruitment, and mortality (Torres et al., 2001; Telesnicki and 

Goldberg, 1995). Coral larvae settlement may be inhibited in areas where sediment has covered available 

substrate (Rogers, 1990; Goh and Lee, 2008). 

Corals have some ability to rid themselves of sediment through mucus production and ciliary action 

(Marszalek, 1981; Bak and Elgershuizen, 1976; Telesnicki and Goldberg, 1995). Octocorals and 

gorgonians are more tolerant of sediment deposition than scleractinian corals, as they grow erect and are 

flexible, reducing sediment accumulation and allowing easy removal (Marszalek, 1981; Torres et al., 

2001; Gittings et al., 1992a). Gorgonians, corals, and sponges on low-relief features have also been 

reported to protrude above accumulated sediment layers, and it is hypothesized that these organisms can 

resist burial by growing faster than the sediment accumulates over the hard substrate upon which they 

settle (Lissner et al., 1991). 

The shock waves produced by explosive structure removals may also harm benthic biota. However, 

corals and other sessile invertebrates have a high resistance to shock. O’Keeffe and Young (1984) 

described the impacts of underwater explosions on various forms of sea life using, for the most part, 

open-water explosions much larger than those used in typical structure-removal operations. They found 

that sessile benthic organisms, such as barnacles and oysters, and many motile forms of life, such as 

shrimp and crabs, that do not possess swim bladders were remarkably resistant to shock waves generated 

by underwater explosions. Oysters located 8 m (26 ft) away from the detonation of 135-kilogram (kg) 

(298-pound [lb]) charges in open water incurred a 5 percent mortality rate. Crabs distanced 8 m (26 ft) 

away from the explosion of 14-kg (31-lb) charges in open water had a 90 percent mortality rate. Few 

crabs died when the charges were detonated 46 m (151 ft) away. O’Keeffe and Young (1984) also noted 

“. . . no damage to other invertebrates such as sea anemones, polychaete worms, isopods, and 

amphipods.” 

Benthic organisms appear to be further protected from the impacts of subbottom explosive 

detonations by rapid attenuations of the underwater shock wave traversing the seabed away from the 

structure being removed. The shock wave is significantly attenuated when explosives are buried as 

opposed to detonation in the water column (Baxter et al., 1982). Theoretical predictions suggest that the 

shock waves of explosives set 5 m (15 ft) below the seabed, as required by BOEMRE regulations, would 

further attenuate blast effects (Wright and Hopky, 1998). 
4-98 Central Planning Area Supplemental EIS 

Charges used in OCS structure removals are typically much smaller than some of those cited by 

O’Keeffe and Young. The Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf: 

Programmatic Environmental Assessment (USDOI, MMS, 2005) predicts low impacts on the sensitive 

offshore habitats from platform removal precisely because of the effectiveness of the proposed Live 

Bottom (Pinnacle Trend) Stipulation in preventing platform emplacement in the most sensitive areas of 

the GOM. Impacts on the biotic communities, other than those on or directly associated with the 

platform, would be limited by the relatively small size of individual charges (normally 50 lb [27 kg] or 

less per well piling and per conductor jacket) and by the fact that charges are detonated 5 m (15 ft) below 

the mudline and at least 0.9 seconds apart (timing needed to prevent shock waves from becoming 

additive) (USDOI, MMS, 2005). Also, because the Live Bottom (Pinnacle Trend) Stipulation precludes 

platform installation within 30 m (100 ft) of a pinnacle feature, adverse effects to live-bottom features 

should be prevented. 

Infrastructure or pipeline removal would impact the communities that have colonized the structures, 

many of which may also be found on live-bottom features. Removal of the structure itself would result in 

the removal of the hard substrate and the associated encrusting community. The overall community 

would experience a reduction in species diversity (both epifaunal encrusting organisms and the fish and 

large invertebrates that fed on them) with the removal of the structure (Schroeder and Love, 2004). The 

epifaunal organisms attached to the platform would die once the platform is removed. However, the 

seafloor habitat would return to the original soft-bottom substrate that existed before the well was drilled. 

Some structures may be converted to artificial reefs. If the rig stays in place, the hard substrate and 

encrusting communities would remain part of the benthic habitat. The diversity of the community would 

not change and associated finfish species would continue to graze on the encrusting organisms. The 

community would remain an active artificial reef. However, plugging of wells and other reef-in-place 

decommissioning activities would still impact benthic communities as discussed above, since all the steps 

for removal except final removal from the water would still occur. 

Proposed Action Analysis 

The pinnacles in the CPA are located in the Main Pass, Viosca Knoll, and Destin Dome lease areas 

off Mississippi and Alabama within offshore Subareas C0-60 (east of the Mississippi River Delta) and 

C60-200. Table 3-2 provides information regarding the level of proposed-action-related activities. For 

the CPA proposed action, 17-23 exploration/, 62-85 development wells, and 20-25 production structures 

are projected for offshore Subareas C0-60. There are 9-14 exploration/delineation, 23-33 development 

wells, and 2-3 production structures projected for offshore Subareas C60-200. It is unlikely that many of 

the wells or production structures would be located in the Pinnacle Trend area because pinnacle blocks 

make up only 2 percent of the blocks in Subarea C0-60 (eastern) and 6 percent of the blocks in Subarea 

C60-200. If the Live Bottom (Pinnacle Trend) Stipulation is implemented, pinnacle features would avoid 

incidences of anchor damage from support vessels. Furthermore, as noted above, any platforms in this 

region would be placed so as to avoid pinnacle features for safety reasons as well as environmental 

protection. Thus, anchoring events are not expected to impact the resource. Anchor impacts, however, 

could occur by mistake, with recovery taking a few to many years, depending on the severity (Fucik et al., 

1984; Rogers and Garrison, 2001; Lissner et al., 1991). 

Pipeline emplacement also has the potential to cause considerable disruption to the bottom sediments 

in the vicinity of the live bottoms (Chapter 4.1.1.8.1 of the Multisale EIS); however, the implementation 

of the proposed Live Bottom (Pinnacle Trend) Stipulation, or a similar protective measure, would restrict 

pipeline-laying activities as well as oil and gas activities in the vicinity of the pinnacle communities. Data 

gathered for the Mississippi-Alabama Continental Shelf Ecosystem Study (Brooks, 1991) and the 

Mississippi/Pinnacle Trend Ecosystem Monitoring, Final Synthesis Report (CSA and GERG, 2001) 

document dense biological communities (i.e., live-bottom communities, fish habitat, etc.) on the high- and 

medium-relief pinnacle features themselves and the live-bottom organisms more sparsely distributed in 

unconsolidated bottom sediments surrounding the pinnacles. The actual effect of pipeline-laying 

activities on the biota of the pinnacle communities would be restricted to the resuspension of sediments. 

Burial of pipelines is only required in water depths of 60 m (200 ft) or less. Therefore, only the 

shallowest live-bottom communities would be affected by the increased turbidity associated with pipeline 

burial. The laying of pipeline without burial produces much less resuspension of sediments. The 
Description of the Environment and Impact Analysis 4-99 

enforcement of the Live Bottom (Pinnacle Trend) Stipulation would help to minimize the impacts of 

pipeline-laying activities throughout the pinnacle region. 

Summary and Conclusion 

Oil and gas operations discharge drilling muds and cuttings that generate turbidity, potentially 

smothering benthos near the drill sites. Deposition of drilling muds and cuttings in the Pinnacle Trend 

area would not greatly impact the biota of the live bottoms because the biota surrounding the pinnacle 

features are adapted to turbid (nepheloid) conditions and high sedimentation rates associated with the 

outflow of the Mississippi River (Gittings et al., 1992a). The pinnacles themselves are coated with a 

veneer of sediment. Regional surface currents and water depth would largely dilute any effluent. 

Additional deposition and turbidity caused by a nearby well are not expected to adversely affect the 

pinnacle environment because such fluids would be dispersed upon discharge. Mud contaminants 

measured in the Pinnacle Trend region reached background levels within 1,500 m (4,921 ft) of the 

discharge point (Shinn et al., 1993). Toxic impacts on benthos are limited to within 100-200 m 

(328-656 ft) of a well (Montagna and Harper, 1996; Kennicutt et al., 1996), and NPDES permit 

requirements limit discharge. The drilling of a well from the proposed action, therefore, would have 

localized impacts on the benthos nearby the well, which should be located away from live-bottom 

features. 

The toxicity of the produced waters has the potential to adversely impact the live-bottom organisms 

of the Pinnacle Trend; however, as previously stated, the proposed Live Bottom (Pinnacle Trend) 

Stipulation would prevent the placement of oil and gas facilities upon (and consequently would prevent 

the discharge of produced water directly over) the Pinnacle Trend live-bottom areas. 

Platform removals have the potential to impact nearby habitats. As previously discussed, the 

platforms are unlikely to be constructed directly on the pinnacles or low-relief areas because of the 

restraints placed by the Live Bottom (Pinnacle Trend) Stipulation, distancing blasts from sensitive 

habitats. Benthic organisms on live bottoms should also have limited impact because they are resistant to 

blasts, tolerant of turbidity, can physically remove some suspended sediment, and may be located above 

or be tall enough to withstand limited sediment deposition. Live bottoms, however, may be impacted by 

heavy sediment deposition layers. The implementation of the Live Bottom (Pinnacle Trend) Stipulation 

would help to prevent such a smothering event. The proposed Live Bottom (Pinnacle Trend) Stipulation 

could prevent most of the potential impacts on live bottoms from bottom-disturbing activities (structure 

emplacement and removal) and operational discharges associated with the proposed action in the CPA. 

Any contaminants that reach live-bottom features would be diluted from their original concentration, so 

impacts that do occur should be sublethal. 

Effects of the Proposed Action without the Proposed Stipulation 

Activities resulting from the proposed action without the protection of the proposed Live Bottom 

(Pinnacle Trend) Stipulation (Chapter 2.4.1.3.2) could have an extremely deleterious impact on portions 

of the Pinnacle Trend areas. Mechanical damage from anchoring, drilling operations, and other 

installation activities is potentially the most damaging impact because these activities could destroy 

biological communities or damage the structure of the pinnacle areas themselves. This may in turn 

reduce the habitat or shelter areas occupied by commercial and recreational fishes. Those areas actually 

subjected to mechanical disruption would be severely impacted. Potential impacts on the Pinnacle Trend 

areas from other impact-producing factors associated with OCS activities (pipeline emplacement, 

discharges of muds and cuttings, and explosive structure removals) would damage live-bottom areas, 

particularly by smothering organisms with heavy layers of drilling muds and cuttings. 

4.1.1.6.1.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts on live-bottom (Pinnacle Trend) communities can be 

found in Chapter 4.4.4.1.1 of the Multisale EIS and in Chapter 4.1.4.1.3 of the 2009-2012 Supplemental 

EIS. Chapter 2.4.1.3.2 of the Multisale EIS contains a complete description and discussion of the 
4-100 Central Planning Area Supplemental EIS 

proposed Live Bottom (Pinnacle Trend) Stipulation. The following is a summary of the information 

presented in the Multisale EIS and the 2009-2012 Supplemental EIS, which incorporates new information 

found since publication of the Multisale EIS and the 2009-2012 Supplemental EIS and in consideration of 

the DWH event. 

The Pinnacle Trend, live-bottom features of the CPA that sustain sensitive offshore habitats are listed 

and described in Chapter 4.1.1.6.1.1. See Chapter 2.4.1.3.2 for a complete description and discussion of 

the proposed Live Bottom (Pinnacle Trend) Stipulation. 

Disturbances resulting from the CPA proposed action, including oil spills and blowouts, have the 

potential to disrupt and alter the environmental, commercial, recreational, and aesthetic values of livebottom features of the CPA. 

A search was conducted for additional new information published since completion of the Multisale 

EIS and the 2009-2012 Supplemental EIS. Various Internet sources and journal articles were examined to 

discover any recent information regarding impacts of oil on benthic organisms. Sources investigated 

include literature published in journals and websites (NOAA, USEPA, and coastal universities). The 

following information is a summary of the resource description incorporated from the Multisale EIS and 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

Possible Modes of Exposure 

Oil released to the environment as a result of an accidental event may impact live-bottom features in 

several ways. Oil may be physically mixed into the water column from the sea surface, be injected below 

the sea surface and travel with currents, be dispersed in the water column, or be sedimented to particles 

and sink to the seafloor. These scenarios and their possible impacts are discussed in the following 

sections. 

An oil spill that occurs at the sea surface would result in a majority of the oil remaining at the sea 

surface. Lighter compounds in the oil would evaporate, and some components of the oil may dissolve in 

the seawater. Evaporation removes the most toxic components of the oil, while dissolution may allow 

bioavailability of hydrocarbons to marine organisms for a brief period of time (Lewis and Aurand, 1997). 

The oil may also emulsify with water or sediment to particles and fall to the seafloor. 

A spill that occurs below the sea surface (at the rig, along the riser between the seafloor and sea 

surface, or through leak paths on the BOP/wellhead) would result in only a portion of the released oil 

rising to the sea surface. If the leak is deep in the water column and the oil is ejected under pressure, oil 

droplets may become entrained deep in the water column (Boehm and Fiest, 1982). The upward 

movement of the oil may be reduced if methane in the oil is dissolved into the water column at the high 

underwater pressures, reducing the oil’s buoyancy (Adcroft et al., 2010). Large oil droplets would rise to 

the sea surface, but the smaller droplets, formed by vigorous turbulence in the plume or the injection of 

dispersants, may remain neutrally buoyant in the water column, creating a subsurface plume (Adcroft et 

al., 2010). Oil droplets less than 100 μm (0.004 in) in diameter may remain in the water column for 

several months (Joint Analysis Group, 2010a). 

Impacts that may occur to benthic communities on live-bottom features as a result of a spill would 

depend on the type of spill, distance from the spill, relief of the biological feature, and surrounding 

physical characteristics of the environment (e.g., turbidity). The Live Bottom (Pinnacle Trend) 

Stipulation requires a 30-m (100-ft) buffer around hard bottoms or pinnacle features to prevent seafloor 

impacts to the features and associated biota. This Agency created this stipulation to protect hard-bottom 

habitats from disruption due to oil and gas activities. However, oil released during accidental events may 

possibly reach live-bottom features. As described above, a portion of the oil released from a spill would 

rise to the sea surface, therefore reducing the impact to benthic communities by direct oil exposure. 

However, small droplets of oil that are entrained in the water column may migrate into live-bottom 

habitat. Although these small oil droplets would not sink themselves, they may also attach to suspended 

particles in the water column and then be deposited on the seafloor (McAuliffe et al., 1975). Exposure to 

subsea plumes, dispersed oil, or sedimented oil may result in long-term impacts such as reduced 

recruitment success, reduced growth, and reduced coral cover as a result of impaired recruitment. These 

impacts are discussed in the following sections. 
Description of the Environment and Impact Analysis 4-101 

Surface Slicks and Physical Mixing 

Surface oil slicks can spread over a large area; however, the majority of the slick is comprised of a 

very thin surface layer of oil moved by winds and currents (Lewis and Aurand, 1997). Oil spills have the 

potential to foul benthic communities and cause lethal or sublethal effects to organisms that the oil 

contacts as it is moved over the sea surface. Pinnacles are features that rise up to as much as 20 m (66 ft) 

from the seafloor, at water depths between 60 and 120 m (200 and 400 ft) (Thompson et al., 1999; 

Schroeder, 2000). Pinnacles, therefore, are 40 m (130 ft) or more below the sea surface. The depth of 

live-bottom features below the sea surface helps protect benthic species from physical oil contact. 

Field data collected at the Atlantic entrance to the Panama Canal 2 months after a tanker spill has 

shown that subtidal coral did not show measurable impacts to the oil spill, presumably because the coral 

was far enough below the surface oil and the oil did not contact the coral (Rützler and Sterrer, 1970). A 

similar result was reported from a Florida coral reef immediately following and 6 months after a tanker 

discharged oil nearby (Chan, 1977). The lack of acute toxicity was again attributed to the fact that the 

corals were completely submerged at the time of the spill, and calm conditions prevented the oil from 

mixing into the water column (Chan, 1977). 

Disturbance of the sea surface by storms can mix surface oil into the water column, but the effects are 

generally limited to the upper 10-20 m (33-66 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich 

and Chan, 2002). Therefore, the depth of live-bottom features below the sea surface should protect them 

from physical mixing of surface oil below the sea surface. However, if dispersants are used, they would 

enable oil to mix into the water column and possibly impact organisms on the live-bottom features. 

Dispersants are discussed later in this section. 

Subsurface Plumes 

A subsurface oil spill or plume could reach a live-bottom feature and would have the potential to 

damage the local biota contacted by oil. Such impacts on the biota may have severe and long-lasting 

consequences, including loss of habitat, biodiversity, and live coverage; change in community structure; 

and failed reproductive success. 

Pinnacle features are protected from direct petroleum-producing impacts through the 30-m (100-ft) 

buffer distance as described in NTL 2009-G39 (USDOI, MMS, 2009b). The distancing of petroleumproducing activities from live-bottom features allows for several physical and biological changes to occur 

to the oil before it reaches sensitive benthic organisms. Oil would become diluted as it physically mixes 

with the surrounding water. The longer and farther a subsea plume travels in the sea, the more dilute the 

oil will be (Vandermeulen, 1982; Tkalich and Chan, 2002). In addition, microbial degradation of the oil 

occurs in the water column, reducing toxicity (Hazen et al., 2010; McAuliffe et al., 1981b). The oil will 

move in the direction of prevailing currents (S.L. Ross Environmental Research Ltd., 1997); however, 

data has indicated that currents move around large topographic features (Rezak et al., 1983; McGrail, 

1982) and such movement would physically protect larger pinnacles and hard-bottom features by 

sweeping the subsea oil around the features rather than over them. Lower relief features may not 

experience such diversion of currents. Also, subsea oil plumes transported by currents may not travel 

nearly as far as surface oil slicks because some oil droplets may conglomerate and rise or may be blocked 

by fronts, as was observed in the southern Gulf of Mexico during the Ixtoc spill (Boehm and Fiest, 1982). 

Should any of the oil come in contact with adult sessile biota, effects would be primarily sublethal, as the 

oil may be diluted by physical and biological processes by the time it reaches the features. Some lowlevel exposure impacts may be chronic, while others may be temporary, and some may not even be able 

to be measured over time. 

Although the Live Bottom (Pinnacle Trend) Stipulation protects benthic organisms from petroleumproducing activity, it is possible that low levels of oil transported in subsea plumes may reach benthic 

features. Several studies have reported results for oil impacts on both hermatypic and ahermatypic corals. 

Although not all of the same species studied are present on pinnacles, impacts are expected to be similar. 

For example, coral feeding activity may be reduced if it is exposed to low levels of oil. Experiments 

indicated that normal feeding activity of Porites porites and Madracis asperula were reduced when 

exposed to 50 ppm oil (Lewis, 1971). Tentacle pulsation of an octocoral, Heteroxenia fuscescens, has 

also been shown to decrease upon oil exposure, although recovery of normal pulsation was observed 96 

hours after the coral was removed from the oil (Cohen et al., 1977). Porites furcata exposed to Marine 
4-102 Central Planning Area Supplemental EIS 

Diesel and Bunker C oil reduced feeding and left their mouths open for much longer than normal 

(Reimer, 1975). 

Direct oil contact may result in coral tissue damage. Corals exposed to sublethal concentrations of oil 

for 3 months revealed atrophy of muscle bundles and mucus cells (Peters et al., 1981). Porites furcata

submersed in Bunker C oil for 1 minute resulted in 100 percent tissue death, although the effect took 

114 days to occur (Reimer, 1975). 

Reproductive ability may also be reduced if coral is exposed to oil. A hermatypic coral, Stylophora 

pistillata, and an octocoral, Heteroxenia fuscescens, neither of which are present in the Gulf of Mexico, 

but may show impacts similar to those that could occur in the Gulf, shed their larvae when exposed to oil 

(Loya and Rinkevich, 1979; Rinkevich and Loya, 1977; Cohen et al., 1977). Undeveloped larvae in the 

water column have a reduced chance of survival due to predation and oil exposure (Loya and Rinkevich, 

1979), which would in turn reduce the ability of larval settlement and reef expansion or recovery. A 

similar expulsion of gametes may occur in species that have external fertilization (Loya and Rinkevich, 

1979), such as those at the Flower Garden Banks (Gittings et al., 1992c), which may then reduce gamete 

survivorship due to oil exposure. 

The overall ability of a coral colony to reproduce may be affected by oil exposure. Reefs of 

Siderastrea siderea that were oiled in a spill produced smaller gonads than unoiled reefs, which resulted 

in reproductive stress for the oiled reef (Guzmán and Holst, 1993). Stylophora pistillata reefs exposed to 

oil had fewer breeding colonies, reduced number of ovaria per polyp, and significantly reduced fecundity 

compared with unoiled reefs (Rinkevich and Loya, 1977). Impaired development of reproductive tissue 

has also been reported for other reef-building corals exposed to sublethal concentrations of oil (Peters et 

al., 1981). Larvae may not be able to settle on substrate impacted by oil. Field experiments on 

Stylophora pistillata showed reduced settlement rate of larvae on artificial substrates of oiled reefs 

compared with control reefs and lower settlement rates, with increasing concentrations of oil in test 

containers (Rinkevich and Loya, 1977). Impaired larval settlement as a result of oiled substrate may lead 

to slow recovery of a disturbed substrate (CSA and GERG, 2001; MRRI, 1984; Montagna and Holmberg, 

2000). Additionally, deeper habitats have slower rates of settlement, growth, and community 

development, and recruitment rates are reportedly slow in the pinnacle habitat (Montagna and Holmberg, 

2000; CSA and GERG, 2001). It is possible that corals may not recruit to an oiled substrate for 10 years 

(MRRI, 1984). 

Corals exposed to subsea oil plumes may also incorporate petroleum hydrocarbons into their tissue. 

Records indicate that Siderastrea siderea, Diploria strigosa, Montastrea annularis, and Heteroxenia 

fuscescens have accumulated oil from the water column and have incorporated petroleum hydrocarbons 

into their tissues (Burns and Knap, 1989; Knap et al., 1982; Kennedy et al., 1992; Cohen et al., 1977). 

Most of the petroleum hydrocarbons were incorporated into the coral tissues, not their mucus (Knap et al., 

1982). However, hydrocarbon uptake may also modify lipid ratios of coral (Burns and Knap, 1989). If 

lipid ratios are modified, mucus synthesis may be impacted, adversely affecting coral ability to protect 

itself from oil through mucus production (Burns and Knap, 1989). While these species are not present in 

the Pinnacle Trend area, similar effects may occur in pinnacle species. 

Sublethal effects, although often hard to measure, could be long lasting and affect the resilience of 

coral colonies to natural disturbances (e.g., elevated water temperature and diseases) (Jackson et al., 1989; 

Loya, 1976a). Continued exposure to oil from resuspended contaminated sediments could also impact 

coral growth and recovery (Guzmán et al., 1994). Any repetitive or long-term oil exposure could inhibit 

coral larvae’s ability to settle and grow, may damage coral reproductive systems, may cause acute toxicity 

to larvae, and may physically alter the reef, interfering with larval settlement, all of which would reduce 

coral recruitment to an impacted area (Kushmaro et al., 1997; Loya, 1975 and 1976a; Rinkevich and 

Loya, 1977), Exposure of eggs and larvae to oil in the water column may reduce the success of a 

spawning event (Peters et al., 1997). Sublethal exposure to oil may be more detrimental to corals than 

high concentrations of oil (Cohen et al., 1977), as sublethal concentrations are typically more widespread 

and have a larger overall community effect. Therefore, the sublethal effects of oil exposure, even at very 

low concentrations, may result in compounded community impacts that have long-lasting effects. 
Description of the Environment and Impact Analysis 4-103 

Dispersed Oil 

Chemically dispersed oil from a surface slick is not anticipated to result in lethal exposures to 

organisms on live-bottom features. The chemical dispersion of oil promotes the weathering process and 

increases the surface area available for bacterial biodegradation. It also allows surface oil to penetrate to 

greater depths than physical mixing would permit, and the dispersed oil will generally remain below the 

water’s surface (McAuliffe et al., 1981b; Lewis and Aurand, 1997). However, reports on dispersant 

usage on surface plumes indicate that a majority of the dispersed oil remains in the top 10 m (33 ft) of the 

water column, with 60 percent of the oil in the top 2 m (6 ft) (McAuliffe et al., 1981a). Dispersant usage 

also reduces the oil’s ability to stick to particles in the water column, minimizing sedimented oil traveling 

to the seafloor (McAuliffe et al., 1981a; Lewis and Aurand, 1997). 

Field experiments designed to test dispersant use on oil spills reported dispersed oil concentrations 

between 1 and 3 ppm, 9 m (30 ft) below the sea surface, approximately 1 hour after treatment with 

dispersant (McAuliffe et al., 1981a and 1981b). Other studies indicated that dispersed oil concentrations 

were <1 ppm, 10 m (33 ft) below the sea surface (Lewis and Aurand, 1997). The above data indicate that 

the mixing depth of dispersed oil is less than the depths of the crests of Pinnacle Trend features (40 m 

[130 ft] or more below the sea surface), greatly reducing the possibility of exposure to dispersed surface 

oil. 

Any dispersed surface oil that may reach the benthic communities of live-bottom features in the Gulf 

of Mexico would be expected to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a). Such 

concentrations would not be life threatening to larval or adult stages based on experiments conducted with 

coral (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Knap, 1987; Wyers et al., 1986; Cohen et al., 

1977) and observations after oil spills (Jackson et al., 1989; Guzmán et al., 1991). Any dispersed oil in 

the water column that comes in contact with corals, however, may evoke short-term negative responses 

by the organisms, such as reduced feeding and photosynthesis or altered behavior (Wyers et al., 1986; 

Cook and Knap, 1983; Dodge et al., 1984). 

Dispersants that are used on oil below the sea surface can travel with currents through the water and 

may contact benthic organisms on the live-bottom features. If the oil spill occurs near a live-bottom 

feature, the dispersed oil could be concentrated enough to harm the community. However, the longer the 

oil remains suspended in the water column traveling with currents, the more dispersed it would become. 

Weathering will also be accelerated and biological toxicity reduced (McAuliffe et al., 1981b). Although 

the use of subsea dispersants is a new technique and very little data are available on dispersion rates, it is 

anticipated that any oil that could reach live-bottom features on the continental shelf will be in low 

concentration based on surface slick dilution data (McAuliffe et al., 1981a; Lewis and Aurand, 1997). It 

is also anticipated that currents around the larger live-bottom features will sweep the subsea oil clear 

around the features (Rezak et al., 1983). Therefore, impacts resulting from exposure to dispersed oil are 

anticipated to be sublethal. 

The report of damage to deepwater corals on the continental slope (USDOI, BOEMRE, 2010i) as a 

result of exposure to oil from the DWH probably resulted from the use of dispersant at the source of the 

blowout. This situation was the first time subsea dispersants were used, and stratified density layers of 

water allowed the oil plume to remain at depth instead of dispersing into the water column (Joint Analysis 

Group, 2010a). The density-bounded plume eventually contacted the coral. The decision to use subsea 

dispersants at the DWH was carefully weighed against the surrounding environment and anticipated 

environmental impacts. The decision to use subsea dispersants may not occur near protected habitats. 

For example, NOAA policy says that the application of dispersants must occur as far as possible from the 

Flower Garden Banks (Gittings, 2006). Also, because a stratified turbid watermass (the nepheloid layer) 

occurs near the seafloor on the continental shelf in the northwestern Gulf of Mexico no more than 20 m 

(66 ft) up into the water column, a depth that may engulf part or all of a live-bottom feature, 

decisionmakers probably would not select to use dispersants near the habitat. 

Sublethal impacts that may occur to coral and other invertebrates exposed to dispersed oil may 

include reduced feeding, reduced photosynthesis, reduced reproduction and growth, physical tissue 

damage, and altered behavior. Short-term, sublethal responses of Diploria strigosa were reported after 

exposure to dispersed oil at a concentration of 20 ppm for 24 hours (Knap et al., 1983; Wyers et al., 

1986). Although concentrations in this experiment were higher than what is anticipated for dispersed oil 

at depth, effects included mesenterial filament extrusion, extreme tissue contraction, tentacle retraction, 
4-104 Central Planning Area Supplemental EIS 

localized tissue rupture (Wyers et al., 1986), and a decline in tentacle expansion behavior (Knap et al., 

1983). Normal behavior resumed within 2 hours to 7 days after exposure (Wyers et al., 1986; Knap et al., 

1983). This coral, however, did not show indications of stress when exposed to 1 ppm and 5 ppm of 

dispersed oil for 24 hours (Wyers et al., 1986). Diploria strigosa exposed to dispersed oil (20:1, oil: 

dispersant) showed an 85 percent reduction in zooxanthellae photosynthesis after 8 hours of exposure to 

the mixture (Cook and Knap, 1983). However, the response was short-term, as recovery occurred 

between 5 and 24 hours after exposure and return to clean seawater. Investigations 1 year after Diploria 

strigosa was exposed to concentrations of dispersed oil between 1 and 50 ppm for periods between 6 and 

24 hours did not reveal any impacts to growth (Dodge et al., 1984; Knap et al., 1983). It should be noted, 

however, that subtle growth effects may have occurred, but they were not measurable (Knap et al., 1983). 

This type of short-term exposure matches anticipated exposures, if any, to pinnacle features. Subsea oil 

plumes from a spill could be carried by currents to the features but would pass by or change directions, 

resulting in only short-term contact with any particular benthic feature. Many benthic organisms would 

return to normal in a few hours to days. 

Historical studies indicated that dispersed oil appeared to be more toxic to coral species than oil or 

dispersant alone. The greater toxicity may be a result of an increased number of oil droplets, resulting in 

greater contact area between oil and water (Elgershuizen and De Kruijf, 1976). The dispersant causes a 

higher water soluble fraction of oil contacting the cell membranes of the coral (Elgershuizen and De 

Kruijf, 1976). The mucus produced by coral, however, can protect an organism from oil. Both hard and 

soft corals have the ability to produce mucus; mucus production has been shown to increase when corals 

are exposed to crude oil (Mitchell and Chet, 1975; Ducklow and Mitchell, 1979). Dispersed oil, which 

has very small oil droplets, does not appear to adhere to coral mucus, and larger untreated oil droplets 

may become trapped by the mucus barrier (Knap, 1987; Wyers et al., 1986). However, entrapment of the 

larger oil droplets may increase long-term exposure to oil if the mucus is not shed in a timely manner 

(Knap, 1987; Bak and Elgershuizen, 1976). 

More recent field studies did not reveal as great an impact of dispersants on corals as were indicated 

in historical toxicity tests (Yender and Michel, 2010). This difference in reported damage probably 

resulted from a more realistic application of dispersants in an open field system and because newer 

dispersants are less toxic than the older ones (Yender and Michel, 2010). Field studies have shown oil to 

be dispersed to the part per billion level minutes to hours after the dispersant application, which is orders 

of magnitude below the reasonable effects threshold of oil in the water column (20 ppm) measured in 

some studies (McAuliffe, 1987; Shigenaka, 2001). 

Although dispersed oil may be more toxic than untreated oil to corals during exposure experiments 

(Shafir et al., 2007; Wyers et al., 1986; Cook and Knap, 1983), untreated oil may remain in the ecosystem 

for long periods of time, while dispersed oil does not (Baca et al., 2005; Ward et al., 2003). Twenty years 

after an experimental oil spill in Panama, oil and impacts from untreated oil were still observed at oil 

treatment sites, but no oil or impacts were observed at dispersed oil or reference sites (Baca et al., 2005). 

Long-term recovery of the coral at the dispersed oil site had already occurred as reported in a 10-year 

monitoring update, and the site was not significantly different from the reference site (Ward et al., 2003). 

The time of year and surrounding ecosystem must be considered when determining if dispersants 

should be used. Dispersant usage may result in reduced or shorter term impacts to coral reefs; however, it 

may increase the impacts to other communities, such as mangroves (Ward et al., 2003). Therefore, 

dispersant usage may be more applicable offshore than in coastal areas where other species may be 

impacted as well. Dispersants also would probably not be approved during peak coral spawning periods 

(e.g., August-September for major reef-building species) (Gittings et al., 1992c and 1994) in order to limit 

the impacts of oil pollution on the near-surface portion of the water column. 

Sedimented Oil (Oil Adsorbed to Sediment Particles) 

Smaller suspended oil droplets could be carried to the seafloor as a result of oil droplets adhering to 

suspended particles in the water column. Smaller particles have a greater affinity for oil (Lewis and 

Aurand, 1997). Oiled sediment that settles to the seafloor may affect organisms attached to live-bottom 

features. It is anticipated that the greatest amount of sedimented oil would occur close to the spill, with 

lesser concentrations farther from the source. Studies after a spill that occurred at the Chevron Main Pass 

Block 41C Platform in the northern Gulf of Mexico revealed that the highest concentrations of oil in the 
Description of the Environment and Impact Analysis 4-105 

sediment were close to the platform and the oil settled to the seafloor within 5-10 mi (8-16 km) of the 

spill site (McAuliffe et al., 1975). Therefore, if the spill occurs close to a live-bottom feature, the 

underlying benthic communities may be exposed to toxic hydrocarbons. However, because of the 

implementation of the 30-m (100-ft) buffer zone around pinnacles features, these hard-bottom 

communities should be distanced from the heaviest oiled sedimentation effects. 

Some oiled particles may become widely dispersed as they travel with currents while they settle out 

of suspension. Settling rates are determined by size and weight of the particle, salinity, and turbulent 

mixing in the area (Poirier and Thiel, 1941; Bassin and Ichiye, 1977; Deleersbijder et al., 2006). Because 

particles would have different sinking rates, the oiled particles would be dispersed over a large area, most 

likely at sublethal or immeasurable levels. Studies conducted after the Ixtoc oil spill revealed that, 

although oil was measured on particles in the water column, measurable petroleum levels were not found 

in the underlying sediment (ERCO, 1982). Based on BOEMRE restrictions and the settling rates and 

behavior of sedimented oil, the majority of organisms that may be exposed to sedimented oil are 

anticipated to experience low-level concentrations. 

Sublethal impacts to benthic organisms may include reduced recruitment success, reduced growth, 

and reduced coral cover as a result of impaired recruitment. Experiments have shown that the presence of 

oil on available substrate for larval coral settlement has inhibited larval metamorphosis and larval 

settlement (Kushmaro et al., 1997). Crude oil concentrations as low as 0.1 ppm on substrate upon which 

the coral larvae were to settle reduced larval metamorphosis occurrences by 50 percent after 8 days of 

exposure. Oil concentrations of 100 ppm on substrates resulted in only 3.3 percent of the test population 

metamorphosizing (Kushmaro et al., 1997). There was also an increased number of deformed polyps 

after metamorphosis due to oil exposure (Kushmaro et al., 1997). It is also possible that recurring 

exposure may occur to coral if sedimented oil is resuspended locally, possibly inhibiting coral growth and 

recovery in the affected areas (Guzmán et al., 1994). Oil stranded in sediment is reportedly persistent and 

does not weather much (Hua, 1999), so coral may be repeatedly exposed to elevated concentrations of oil. 

Adult coral, however, may be able to protect itself from low concentrations of sedimented oil through 

mucus production. Coral mucus may not only act as a barrier to protect coral from the oil in the water 

column, it has been shown to aid in the removal of oiled sediment on coral surfaces (Bak and 

Elgershuizen, 1976). Coral may use a combination of increased mucus production and ciliary action to 

rid themselves of oiled sediment (Bak and Elgershuizen, 1976). 

Blowout and Sedimentation 

Oil or gas well blowouts are possible occurrences in the OCS. Benthic communities exposed to large 

amounts of resuspended sediments following a subsurface blowout could be subject to sediment 

suffocation, exposure to toxic contaminants, and reduced light. Should oil or condensate be present in the 

blowout flow, liquid hydrocarbons could be an added source of negative impact on the benthos. 

Turbid waters allow less light penetrating to depth, which may result in reduced photosynthesis by the 

symbiotic zooxanthellae that live in hermatypic coral tissue and by calcareous algae (Rogers, 1990). 

Long-term exposures to turbidity have even resulted in significantly reduced skeletal extension rates in 

the scleractinian coral Montastraea annularis (Torres, 2001; Dodge et al., 1974) and acute decrease in 

calcification rates of Madracis mirabilis and Agaricia agaricites (Bak, 1978). The higher the 

concentration of suspended sediment in the water column and the longer the sediment remains suspended, 

the greater the impact. 

Suspended sediment that is transported by currents deep in the water column would not impact the 

benthic organisms on live-bottom features. Studies have shown that deep currents sweep around 

topographic features instead of over them, allowing the suspended sediment to remain at depth (Rezak et 

al., 1983; McGrail, 1982). A similar movement of water is anticipated around larger pinnacle features; 

therefore, suspended sediment or subsea oil plumes from depth would not be deposited on top of the 

elevated benthic organisms. However, lower relief features may experience slightly more deposition as 

currents may not sweep around them as much as the higher relief features. 

Sediment that settles out of upper layers of the water column may impact benthic organisms of livebottom features. Sediment deposition may smother benthic organisms, decreasing gas exchange, 

increasing exposure to anaerobic sediment, reducing light intensity, and causing physical abrasion 

(Wilber et al., 2005). Corals may experience reduced colony coverage, changes in species diversity and 
4-106 Central Planning Area Supplemental EIS 

dominance patterns, alterations in growth rates and forms, decreased calcification, decreased 

photosynthesis, increased respiration, increased production in mucus, loss of zooxanthellae, lesions, 

reduced recruitment, and mortality (Torres et al., 2001; Telesnicki and Goldberg, 1995). Coral larvae 

settlement may also be inhibited in areas where sediment has covered available substrate (Rogers, 1990; 

Goh and Lee, 2008). Gorgonian larvae, for example, only settle on substrate that does not have 

accumulated sediment (Grigg, 1977). 

Impacts to corals as a result of sedimentation would vary based on coral species, the height to which 

the coral grows, degree of sedimentation, length of exposure, and the coral’s ability to clear the sediment. 

Impacts may range from sublethal effects such as reduced growth, alteration in form, reduced recruitment 

and productivity, and slower growth to death (Rogers, 1990). 

Corals have some ability to rid themselves of sediment through mucus production and ciliary action 

(Marszalek, 1981; Bak and Elgershuizen, 1976; Telesnicki and Goldberg, 1995). Scleractinian corals are 

tolerant of short-term sediment exposure and burial, but longer exposures may result in the loss of 

zooxanthellae, polyp swelling, increased mucus production, reduced coral growth, and reduced reef 

development (Marszalek, 1981; Rice and Hunter, 1992). Bleached tissue as a result of sediment exposure 

has been reported to recover in approximately a month (Wesseling et al., 1999). 

Solitary octocorals and gorgonians, which are abundant on many hard-bottom features, are more 

tolerant of sediment deposition than colony-forming scleractinian corals because the solitary species grow 

erect and are flexible, reducing sediment accumulation and allowing easy removal (Marszalek, 1981; 

Torres et al., 2001; Gittings et al., 1992a). Many of these organisms have even been observed to grow tall 

enough to resist burial during periods of sediment encroachment (Lissner et al., 1991). Branching and 

upright forms of scleractinian corals, such as Madracis mirabilis and Agaricia agaricites, also tend to be 

more tolerant of sediment deposition than massive, plating, and encrusting forms, such as Porites 

astreoides (Roy and Smith, 1971; Bak, 1978). Some of the more sediment-tolerant scleractinian species 

in the Gulf of Mexico include Montastraea cavernosa, Siderastrea siderea, Siderastrea radians, and 

Diploria strigosa (Torres et al., 2001; Acevedo et al., 1989; Loya, 1976b). Due to the influence of the 

Mississippi River in the CPA, waters are more turbid near the outflow of the River, and more turbiditytolerant species are present on live bottoms in this portion of the Gulf of Mexico. Because many of the 

species are more tolerant of turbidity and sedimentation, they could better survive exposure to increased 

sediment input (Gittings et al., 1992a). 

Since BOEMRE’s proposed stipulation would preclude drilling within 30 m (100 ft) of a pinnacle 

feature, most adverse effects on live-bottom features from blowouts would likely be prevented. 

Petroleum-producing activities would be far enough removed that heavy layers of sediment suspended as 

a result of a blowout should settle out of the water column before they reach sensitive biological 

communities. Other particles that travel with currents should become dispersed as they travel, reducing 

turbidity and depositional impacts. Furthermore, sediment traveling at depth should remain at depth 

instead of rising to the top of live-bottom features. 

Response Activity Impacts 

Oil-spill-response activity may also impact sessile benthic features. Booms anchored to the seafloor 

are sometimes used to control the movement of oil at the water surface. Boom anchors can physically 

impact corals and other sessile benthic organisms, especially when booms are moved around by waves 

(Tokotch, 2010). Vessel anchorage and decontamination stations set up during response efforts may also 

break or kill hard-bottom features as a result of setting anchors. Anchor damage may result in the 

crushing and breaking of hard bottoms and associated communities. It may also result in community 

alteration through reduced or altered substrate cover, loss of sensitive species, and a reduction in coral 

cover in heavily damaged areas (Dinsdale and Harriott, 2004). Anchoring often destroys a wide swath of 

habitat by being dragged over the seafloor or by the vessel swinging at anchor, causing the anchor chain 

to drag over the seafloor (Lissner et al., 1991). Damage to corals as a result of anchoring may take 10 or 

more years to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and Garrison, 

2001). Nearby species on these hard-bottom habitats that disperse larvae short distances, such as solitary 

species (cup corals, octocorals, and hydrocorals), may recolonize areas more rapidly than slow-growing 

colonial forms that disperse larval great distances (Lissner et al., 1991). Effort should be made to keep 

vessel anchorage areas away from sensitive benthic features to minimize impact. 
Description of the Environment and Impact Analysis 4-107 

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud may be forced out of the well and deposited on the seafloor near the well site. 

Any organisms beneath the extruded drilling mud would be buried. Based on the BOEMRE stipulation 

contained in NTL 2009-G39, a well should be far enough away from live-bottom features to prevent 

extruded drilling muds from smothering sensitive benthic communities. However, if drilling muds were 

to travel far enough or high enough in the water column to contact a hard-bottom community, the fluid 

may smother the existing community. Low-relief communities would be more at risk for burial than the 

higher pinnacles. Experiments indicate that corals perish faster when buried beneath drilling mud than 

when buried beneath carbonate sediments (Thompson, 1979). Turbidity impacts may result in reduced 

photosynthesis or reduced growth (Rogers, 1990; Torres, 2001). Light layers of deposited sediment 

would most likely be removed by mucus and ciliary action (Marszalek, 1981; Bak and Elgershuizen, 

1976; Telesnicki and Goldberg, 1995). 

Proposed Live Bottom (Pinnacle Trend) Stipulation 

The proposed Live Bottom (Pinnacle Trend) Stipulation is a potential mitigating measure for leases 

resulting from the proposed action. The stipulation is designed to prevent petroleum-producing activities 

from damaging the pinnacle features. Under the stipulation, plans will be reviewed on a case-by-case 

basis to determine whether a proposed operation could impact a pinnacle area. If it is determined from 

site-specific information derived from BOEMRE studies, published information from other research 

programs, geohazards survey information, or another source that the operation would impact a pinnacle 

area, the operator may be required to relocate the proposed operation. 

Although the BOEMRE stipulation prevents oil and gas drilling activity within 30 m (100 ft) of 

pinnacle features, some effects may occur to benthic organisms as a result of an oil spill. Sublethal 

impacts may include exposure to low levels of oil, dispersed oil, or sedimented oil and turbidity and 

sedimentation from disturbed sediments. Effects from these exposures may include reduced 

photosynthesis, reduced growth, altered behavior, decreased community diversity, altered community 

composition, reduction in coral cover, and reduced reproductive success. The severity of these impacts 

may be dependent on the concentration and duration of exposure. If concentrated oil is carried to livebottom habitats in a subsea plume, severe lethal effects could result to localized community habitats 

(Dodge et al., 1984; Wyers et al., 1986). Recovery could take 10 years or more (MRRI, 1984; Fucik et 

al., 1984; Rogers and Garrison, 2001). 

Proposed Action Analysis 

The Pinnacle Trend occupies 74 lease blocks in the northeastern portion of the CPA proposed action 

and is protected from impacts from oil and gas activity. The Pinnacle Trend blocks represent a small 

fraction of the continental shelf area in the CPA. The fact that the Pinnacle Trend features are widely 

dispersed, combined with the probable random nature of oil-spill locations, serves to limit the extent of 

damage from any given oil spill to the Pinnacle Trend. 

The shallowest water depth over any features of the Pinnacle Trend in the CPA is about 60 m (200 ft). 

When surface spills are mixed into the water column, the oil is not expected to penetrate below a depth of 

about 10 m (33 ft). The use of dispersants could result in oil mixing into the water column and potentially 

reaching Pinnacle Trend communities. 

With the application of the proposed Live Bottom (Pinnacle Trend) Stipulation, blowouts would not 

occur within 30 m (100 ft) of a Pinnacle Trend feature. Furthermore, blowouts near Pinnacle Trend 

features would be unlikely to impact the biota because oil would rapidly float to the surface. Oil that is 

ejected under pressure may produce tiny droplets that become entrained in the water column and could 

possibly affect the Pinnacle Trend communities. Sedimented oil or sedimentation as a result of a blowout 

near a Pinnacle Trend community may impact benthic organisms. 

Potential impacts to the Pinnacle Trend from oil spills and blowouts from the CPA proposed action 

are unlikely and are not expected to be significant. Chemical spills are also infrequent, of small quantity, 

and usually occur in surface waters. The proposed Live Bottom (Pinnacle Trend) Stipulation would assist 

in preventing most of the potential impacts from oil and gas operations, including accidental oil spills, 

blowouts, and chemical spills on the biota of the Pinnacle Trend. No significant impacts to the Pinnacle 

Trend are expected from the CPA proposed action. 
4-108 Central Planning Area Supplemental EIS 

Summary and Conclusion 

Live-bottom features represent a small fraction of the continental shelf area in the CPA. The fact that 

the live-bottom features are widely dispersed, combined with the probable random nature of oil-spill 

locations, serves to limit the extent of damage from any given oil spill to the live-bottom features. 

The proposed Live Bottom (Pinnacle Trend) Stipulation (Chapter 2.4.1.3.2) would prevent most of 

the potential impacts from oil and gas operations, including accidental oil spills and blowouts, on the 

biota of live-bottoms features. However, operations outside the proposed buffer zones around sensitive 

habitats (including blowouts and oil spills) may affect live-bottom features. 

The depth below the sea surface to which many live-bottom features rise helps to protect them from 

surface oil spills. Some pinnacles may rise to within 40 m (130 ft) of the sea surface; however, many 

features have much less relief or are in deeper water depths. Any oil that might contact pinnacle features 

would probably be at low concentrations because the depth to which surface oil can mix down into the 

water column is less than the peak of the tallest pinnacles, and this would result in little effect to these 

features. 

A subsurface spill or plume may impact sessile biota of live-bottom features. Oil or dispersed oil 

may cause sublethal impacts to benthic organisms if a plume reaches these features. Impacts may include 

loss of habitat, biodiversity, and live coverage; change in community structure; and failed reproductive 

success. The Live Bottom (Pinnacle Trend) Stipulation would limit the potential impact of such 

occurrences by keeping the sources of such adverse events geographically removed from the sensitive 

biological resources of live-bottom features. 

Sedimented oil or sedimentation as a result of a blowout may impact benthic organisms. However, 

because the Live Bottom (Pinnacle Trend) Stipulation places petroleum-producing activity at a distance 

from live-bottom features, this would result in reduced turbidity and sedimentation. Furthermore, any 

sedimented oil should be well dispersed, resulting in a light layer of deposition that would be easily 

removed by the organism and have low toxicity. 

The proposed Live Bottom (Pinnacle Trend) Stipulation would assist in preventing most of the 

potential impacts on live-bottom communities from blowouts, surface, and subsurface oil spills and the 

associated effects. Any contact with spilled oil would likely cause sublethal effects to benthic organisms 

because the distance of activity would prevent contact with concentrated oil. In the unlikely event that oil 

from a subsurface spill would reach the biota of a live-bottom feature, the effects would be primarily 

sublethal and impacts would be at the community level. Any turbidity, sedimentation, and sedimented oil 

would also be at low concentrations by the time the live-bottom features were reached, resulting in 

sublethal impacts. 

Effects of the Proposed Action without the Proposed Stipulation 

The live-bottom features and associated biota of the CPA could be adversely impacted by oil and gas 

activities resulting from the proposed action should it not be restricted by the proposed Live Bottom 

(Pinnacle Trend) Stipulation. This would be particularly true should operations occur directly on top of 

or in the immediate vicinity of otherwise protected live-bottom features. The area within the restricted 

zones would probably be the areas of the live-bottom features that are most susceptible to adverse impacts 

if oil and gas activities are not restricted by the Live Bottom (Pinnacle Trend) Stipulation or projectspecific mitigating measures. These impacting factors would include blowouts, surface oil spills, and 

subsea oil spills. Potential impacts from routine activities resulting from the proposed action are 

discussed in Chapter 4.1.1.6.1.2. 

Oil spills as well as routine activities have the potential to considerably alter the diversity, cover, and 

long-term viability of the biota found on live-bottom features. Direct oil contact may result in acute 

toxicity (Dodge et al., 1984; Wyers et al., 1986). In most cases, recovery from disturbances would take 

10 years or more (MRRI, 1984; Fucik et al., 1984; Rogers and Garrison, 2001). Indeed, disturbances, 

including oil spills and blowouts, would alter benthic substrates and their associated biota over large 

areas. In the unlikely event of a blowout, sediment resuspension (potentially with associated oil) could 

cause adverse turbidity and sedimentation conditions. In addition to affecting the benthic cover of a livebottom feature, a blowout could alter the local benthic morphology, thus irreversibly altering the livebottom community. Oil spills (surface and subsea) could be harmful to the local biota should the oil have 

a prolonged or recurrent contact with the organisms. Therefore, in the absence of the Live Bottom 
Description of the Environment and Impact Analysis 4-109 

(Pinnacle Trend) Stipulation, the proposed action could cause long-term (10 years or more) adverse 

impacts to the biota of the live-bottom features. 

4.1.1.6.1.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts on live-bottom (Pinnacle Trend) communities can be 

found in Chapter 4.5.4.1.1 of the Multisale EIS and in Chapter 4.1.4.1.4 of the 2009-2012 Supplemental 

EIS. The following is a summary of the information presented in the Multisale EIS and the 2009-2012 

Supplemental EIS, which incorporates new information found since publication of the Multisale EIS and 

the 2009-2012 Supplemental EIS and in consideration of the DWH event. 

This cumulative analysis considers the effects of impact-producing factors related to the proposed 

action plus those related to prior and future OCS lease sales, and to tanker and other shipping operations 

that may occur and adversely affect live bottoms of the Pinnacle Trend area. Specific OCS-related, 

impact-producing factors considered in the analysis are structure emplacement and removal, anchoring, 

discharges from well drilling, produced waters, pipeline emplacement, oil spills, blowouts, and 

operational discharges. Non-OCS-related impacts including commercial fisheries, natural disturbances, 

anchoring by recreational boats, and other non-OCS commercial vessels, as well as spillage from import 

tankering, all have the potential to alter live bottoms. 

It is assumed that the Live Bottom (Pinnacle Trend) Stipulation for live bottoms would be part of 

appropriate OCS leases and that existing site/project-specific mitigations would be applied to OCS 

activities on these leases or supporting activities on these leases. The Live Bottom (Pinnacle Trend) 

Stipulation does not permit bottom-disturbing activities within 30 m (100 ft) of any hard bottom or 

pinnacle. However, stipulations and mitigations do not protect the resources from activities outside of 

BOEMRE jurisdiction (i.e., commercial fishing, tanker and shipping operations, or recreational 

activities). 

Severe and permanent physical damage may occur to pinnacle features and the associated live 

bottoms as a result of non-OCS activities. It is assumed those biota associated with live bottoms of the 

CPA are well adapted to natural disturbances such as turbidity and storms; however, human disturbance 

could cause severe damage to live-bottom biota, possibly leading to changes of physical integrity, species 

diversity, or biological productivity. If such events were to occur, recovery to pre-impact conditions 

could take as much as 10 years (Fucik et al., 1984). 

Natural events such as storms, extreme weather, and fluctuations of environmental conditions (e.g., 

nutrient pulses, low dissolved oxygen levels, seawater temperature minima, and seasonal algal blooms) 

may impact live-bottom communities. Because of the depth of the Pinnacle Trend environment, waves 

seldom have a direct influence. During severe storms, such as hurricanes, large waves may reach deep 

enough to stir bottom sediments (Brooks, 1991; CSA, 1992a). These forces are not expected to be strong 

enough to cause direct physical damage to organisms living on the features. Rather, currents are created 

by the wave action that can resuspend sediments to produce added turbidity and sedimentation (Brooks, 

1991; CSA, 1992a). The animals in this region are well-adapted to the effects common to this frequently 

turbid environment (Gittings et al., 1992a). 

Recreational boating, fishing, and import tankering may severely impact live-bottom communities. 

Ships anchoring near major shipping fairways of the CPA or EPA, on occasion, may impact sensitive 

areas located near these fairways. Numerous fishermen also take advantage of the resources of the region 

and may anchor at hard-bottom locations to fish. Much of the fishing on these habitats uses bottom 

fishing gear that may damage benthic organisms or may snag on the reefs and be lost. Such gear, 

particularly lines of varying thickness, can cut into the tissues of many benthic organisms during storm 

movement of bottom waters. 

Damage resulting from commercial fishing, especially bottom trawling, may have a severe impact on 

hard-bottom benthic communities. Bottom trawling in the Gulf of Mexico primarily targets shrimp from 

nearshore waters to depths of approximately 90 m (300 ft) (NRC, 2002). Although trawlers would not 

target areas with pinnacles as fishing ground, since pinnacles may tangle with gear, accidental instances 

of trawling may occur near or over pinnacles, resulting in community damage. Reports indicate that 

bottom trawling activity on hard-bottom substrates can overturn boulders and destroy epifaunal organisms 

(Freese et al., 1999). Large emergent sponges and anthozoans may be particularly vulnerable to trawling 
4-110 Central Planning Area Supplemental EIS 

activity, as these organisms grow above the substrate and can be caught and removed by trawling activity 

(Freese et al., 1999). Recovery rates of corals and coralline algae may take decades to centuries and 

depend on the extent of the impact, frequency of disturbance, other natural changes that occur to the 

habitat, and the organism’s life history (NRC, 2002). 

Structure placement and anchor damage from support boats and ships, floating drilling units, and 

pipeline-laying vessels that disturb areas of the seafloor are considered the greatest oil and gas OCSrelated threat to pinnacle live-bottom areas. The size of the areas affected by chains associated with 

anchors and pipeline-laying barges would depend on the water depth, chain length, sizes of anchor and 

chain, method of placement, wind, and current (Lissner et al., 1991). Anchor damage could include 

crushing and breaking of live bottoms and associated communities. It may also result in community 

alteration through reduced or altered substrate cover, loss of sensitive species, and a reduction in coral 

cover in heavily damaged areas (Dinsdale and Harriott, 2004). Anchoring often destroys a wide swath of 

habitat by being dragged over the seafloor or by the vessel swinging at anchor, causing the anchor chain 

to drag over the seafloor (Lissner et al., 1991). Damage to corals as a result of anchoring may take 10 or 

more years from which to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and 

Garrison, 2001). Nearby species on these hard-bottom habitats that disperse larvae short distances, such 

as solitary species (cup corals, octocorals, and hydrocorals), may recolonize areas more rapidly than slowgrowing colonial forms that disperse larval great distances (Lissner et al., 1991). Such anchoring damage, 

however, should be minimized on pinnacle habitats, as no bottom-disturbing activities are permitted 

within 30 m (100 ft) of the hard-bottom feature, as described by NTL 2009-G39 (USDOI, MMS, 2009b). 

Both explosive and nonexplosive structure-removal operations disturb the seafloor; however, they are 

not expected to affect hard-bottom communities because of required buffer distances and because many 

sessile benthic organisms are known to resist the concussive force of structure-removal-type blasts 

(O’Keeffe and Young, 1984). Also, BOEMRE regulations require charges to be detonated 5 m (15 ft) 

below the mudline, which would attenuate shock waves in the seafloor (Baxter et al., 1982). Should 

pinnacle communities incur any damages as a result of the explosive removal of structures, recruitment 

and succession of the communities would be slow and may take more than 10 years (Montagna and 

Holmberg, 2000; CSA and GERG, 2001; MRRI, 1984). 

Routine discharges of drilling muds and cuttings by oil and gas operations could affect biological 

communities and organisms through a variety of mechanisms, including the smothering of organisms 

through deposition or less obvious sublethal toxic effects (impacts to growth and reproduction). The Live 

Bottom (Pinnacle Trend) Stipulation, however, require that drilling occur at least 30 m (100 ft) from 

pinnacles, which helps protect these features through physical distance from wells. Even though the 

additive effects of drilling several wells add more discharges to the environment, the Live Bottom 

(Pinnacle Trend) Stipulation protects these sensitive communities through distance from drilling. 

Drilling muds quickly disperse upon release, and most of the material is rapidly deposited on the 

seafloor (Neff, 2005; Shinn et al., 1980; Hudson et al., 1982). The drilling fluid plume in the water 

column has been measured to be only a few milligrams/liter above background sediment concentrations 

100 m (328 ft) from the discharge point, concentrations often less than those produced during storms or 

from boat wakes (Shinn et al., 1980). Deposition of drilling muds and cuttings in pinnacle habitats are 

not expected to greatly impact the biota of the surrounding habitat for two reasons. First, the biota that 

live on the pinnacles are adapted to turbid conditions and storm impacts (Gittings et al., 1992a), reducing 

their vulnerability to sedimentation. Second, BOEMRE policy does not allow drilling within 30 m 

(100 ft) of a pinnacle, placing physical distance between the well and the sensitive environment in which 

the cuttings may travel to the seafloor. Any exposure that may occur from muds and cuttings discharged 

as a result of the cumulative scenario would be temporary, primarily sublethal in nature, and the effects 

would be limited to small areas. Recovery to pre-impact conditions from these sublethal impacts would 

take place within 10 years (Fucik et al., 1984). 

Produced waters from petroleum operations are not likely to have a great impact on pinnacles. 

Produced waters are rapidly diluted and impacts are generally only observed within proximity of the 

discharge point, and acute toxicity that may result from produced waters occurs “within the immediate 

mixing zone around a production platform” (Gittings et al., 1992b; Holdway, 2002). There have been no 

reported impacts to marine organisms or sediment contamination beyond 100 m (328 ft) of the producedwater discharge (Neff and Sauer, 1991; Trefry et al., 1995). Rapid dilution of surface discharges was 

reported within 6 m (20 ft) from the release point (Shinn et al., 1980; Hudson et al., 1982). Drilling 
Description of the Environment and Impact Analysis 4-111 

discharges may be diluted 100 times at 10 m (33 ft) from the discharge and 1,000 times at 100 m (328 ft) 

from the discharge (Neff, 2005). Dilution continues with distance from the discharge point; at 96 m 

(315 ft) from the release point, Shinn et al. (1980) measured a plume as only a few milligrams/liter above 

background suspended sediment concentrations. Suspended sediment concentrations 6 m (20 ft) from the 

discharge were often less than those produced during storms or from boat wakes (Shinn et al., 1980). 

Similar dilution factors can be expected for produced-water discharges. Because BOEMRE policy does 

not allow drilling within 30 m (100 ft) of a pinnacle, the possibility of acute toxicity from the discharge is 

eliminated. If any impacts were to occur, they would be sublethal. 

The Live Bottom (Pinnacle Trend) Stipulation and site-specific mitigations are expected to prevent 

operators from placing pipelines directly upon live-bottom communities. The effect of pipeline-laying 

activities on the biota of these communities would be restricted to the resuspension of sediments, possibly 

causing obstruction of filter-feeding mechanisms of sedentary organisms and gills of fishes. Adverse 

impacts from resuspended sediments would be temporary, primarily sublethal in nature, and the effects 

would be limited to small areas. Impacts may include “changes in respiration rate, . . . abrasion and 

puncturing of structures, reduced feeding, reduced water filtration rates, smothering, delayed or reduced 

hatching of eggs, reduced larval growth or development, abnormal larval development, or reduced 

response to physical stimulus” (Anchor Environmental CA, L.P., 2003). Since burial of pipelines is not 

required in water depths >60 m (200 ft), very little of the Pinnacle Trend area ( 60-m [200-ft] depth) 

would be subjected to high turbidity caused by burial during pipeline-laying activities. 

The Live Bottom (Pinnacle Trend) Stipulation would help protect hard-bottom communities from 

experiencing direct oiling as a result of a blowout because bottom-disturbing activities are not permitted 

within 30 m (100 ft) these communities. Also, the depth of pinnacle features (60-120 m; 200-400 ft) 

helps protect them from fouling by oil. Disturbance of the sea surface by storms can mix surface oil into 

the water column, but the effects are generally limited to the upper 10-20 m (33-66 ft) (Lange, 1985; 

McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002). Pinnacles rise up to 20 m (66 ft) above the 

seafloor, at water depths between 60 and 120 m (200 and 400 ft) (Thompson et al., 1999; Schroeder, 

2000). Pinnacles, therefore, are 40 m (130 ft) or more below the sea surface. The depth of the livebottom features below the sea surface helps protect benthic species from physical oil contact. 

Any dispersed surface oil from a tanker or rig spill that may reach the benthic communities of 

pinnacles in the Gulf of Mexico would be expected to be at very low concentrations (less than 1 ppm) 

(McAuliffe et al., 1981a and 1981b; Lewis and Aurand, 1997). Such concentrations would not be life 

threatening to larval or adult stages based on experiments conducted with coral (Lewis, 1971; 

Elgershuizen and De Kruijf, 1976; Knap, 1987; Wyers et al., 1986; Cohen et al., 1977) and observations 

after oil spills (Jackson et al., 1989; Guzmán et al., 1991). Any dispersed or physically mixed oil in the 

water column that comes in contact with corals, however, may evoke short-term negative responses by 

the organisms, such as reduced feeding and photosynthesis or altered behavior (Wyers et al., 1986; Cook 

and Knap, 1983; Dodge et al., 1984). 

Potential blowouts are unlikely to impact the biota of the pinnacles unless dispersants are used 

because BOEMRE policy does not allow drilling within 30 m (100 ft) of a pinnacle. Therefore, these 

sensitive habitats are distanced from the potential lethal impacts of a blowout. Oil leaked at the seafloor 

would rise to the sea surface because all known reserves in the Gulf of Mexico have specific gravity 

characteristics that would preclude oil from sinking immediately after release at a blowout site. If any 

blowouts from wells did occur, the suspended sediments should settle out of the water column before a 

majority of the material reached a pinnacle. Any oil that becomes entrained in a subsurface plume will be 

dispersed as it travels in the water column (Vandermeulen, 1982; Tkalich and Chan, 2002). Also, because 

currents are anticipated to sweep around the larger pinnacle features instead of over them, subsea oil 

should be directed away from the larger features (Rezak et al., 1983; McGrail, 1982). If oil were to 

contact the live-bottom features, concentrations would be sublethal unless the source is close to the 

feature; the impacts may include loss of habitat, biodiversity, and live coverage; change in community 

structure; and failed reproductive success. In the highly unlikely event that oil from a subsurface spill 

could reach a coral covered area in lethal concentrations, the recovery of this area could take in excess of 

10 years (Fucik et al., 1984). 

In the unlikely event a freighter, tanker, or other oceangoing vessel related to OCS Program activities 

sank and collided with pinnacle features or associated habitat, releasing its cargo, recovery capabilities 

from such a catastrophic scenario are unknown at this time. For the purpose of this analysis, it is 
4-112 Central Planning Area Supplemental EIS 

projected that no surface spills, regardless of size, would have an impact on the biota of pinnacles, largely 

because the tops of the features crest at depths greater than 40 m (130 ft) below the sea surface. Surface 

oil spills are therefore not expected to impact the pinnacle communities, as discussed above. 

Should the Live Bottom (Pinnacle Trend) Stipulation not be implemented for the proposed action or 

for future lease sales, OCS activities could have the potential to destroy part of the biological 

communities and damage one or several live/hard-bottom features. The most potentially damaging of 

these are the impacts associated with physical damages that may result from anchors, structure 

emplacement, and other bottom-disturbing operations. 

A recent report documents damage to a deepwater coral community 7 mi (11 km) southwest of the 

DWH event. Results are still pending, but it appears that a deepwater coral community about 

15 m x 40 m (50 ft x 130 ft) in size was severely damaged (USDOI, BOEMRE, 2010j). Surface oil was 

also reported above some pinnacle features; however, results of field studies in the area are pending at this 

time (Boland et al., 2010). 

The cumulative impact of possible oil spills, along with the DWH event, is not anticipated to affect 

the overall Pinnacle Trend habitat. The limited data currently available on the impacts of the DWH event 

make it difficult to definitively say if any impacts have affected the pinnacle features. It appears some 

impacts have occurred to corals within 7 mi (11 km) of the well. Water column sampling, however, 

indicated that concentrations of total petroleum hydrocarbons in the water column were less than 0.5 ppm, 

40 and 45 nmi (74 and 83 km; 46 and 52 mi) northeast of the well (Haddad and Murawski, 2010), which 

is below concentrations known to cause acute toxicity, and are more likely to cause low-level, short-term 

impacts to corals (Dodge et al., 1984; Wyers et al., 1986; Kushmaro et al., 1997). If oil is released near a 

pinnacle feature and concentrated oil is entrained in the water column (by turbulent discharge or use of 

dispersant), it could contact nearby pinnacle habitat with serious detrimental effects. Habitats receiving 

high concentrations of oil could take 10 or more years to recover (Fucik et al., 1984). However, since 

subsea plumes travel directionally with water currents, only pinnacle habitats directly in the path of the 

plume would be affected. Therefore, the acute impacts of any large-scale blowout would likely be limited 

in scale, and any additive impacts of several blowouts should only impact small areas on an acute level, 

with possible sublethal impacts occurring over a larger area. However, BOEMRE policy would not allow 

wells to be drilled within 30 m (100 ft) of a pinnacle, separating the habitat from the worst of the 

sediment deposition and allowing most of the oil to rise to the sea surface without contacting pinnacle 

features. 

Summary and Conclusion 

Non-OCS activities that may occur in the vicinity of the pinnacle communities include recreational 

boating and fishing, import tankering, and natural events such as extreme weather conditions, and 

extreme fluctuations of environmental conditions. These activities could cause damage to the pinnacle 

communities. Ships using fairways in the vicinity of pinnacles anchor in the general area of pinnacles on 

occasion, and numerous fishermen take advantage of the resources of regional bottoms. These activities 

could lead to instances of severe and permanent physical damage. During severe storms, such as 

hurricanes, large waves may reach deep enough to stir bottom sediments (Brooks, 1991; CSA, 1992a). 

Because of the depth of the Pinnacle Trend area, these forces are not expected to be strong enough to 

cause direct physical damage to organisms living on the reefs. 

Possible impacts from routine activities of OCS oil and gas operations include anchoring, structure 

emplacement and removal, pipeline emplacement, drilling discharges, and discharges of produced waters. 

In addition, accidental subsea oil spills, or blowouts associated with OCS activities can cause damage to 

pinnacle communities. Long-term OCS activities are not expected to adversely impact the live-bottom 

environment because these impact-producing factors are restrained by the continued implementation of 

the lease stipulation and site-specific mitigations. The inclusion of the Live Bottom (Pinnacle Trend) 

Stipulation would preclude the occurrence of physical damage, the most potentially damaging of these 

activities. The impacts to the live bottoms are judged to be infrequent because of the small number of 

operations in the vicinity of pinnacles and the distance from the habitat. The impact to the live/hardbottom resource as a whole is expected to be slight because of the projected lack of community-wide 

impacts. 
Description of the Environment and Impact Analysis 4-113 

Impacts from blowouts, pipeline emplacement, muds and cuttings discharges, other operational 

discharges, and structure removals should be minimized because of the proposed Live Bottom (Pinnacle 

Trend) Stipulation and the dilution of discharges and resuspended sediments in the area. Potential 

impacts from discharges would be further reduced by USEPA discharge regulations and permits 

restrictions. 

The incremental contribution of the proposed action to the cumulative impact is expected to be slight, 

with possible impacts from physical disturbance of the bottom, discharges of drilling muds and cuttings, 

other OCS discharges, structure removals, and oil spills. Negative impacts should be restricted by the 

implementation of the Live Bottom (Pinnacle Trend) Stipulation, site-specific stipulations, the depths of 

the features, the currents in the live-bottom area, and the distance of pinnacle habitats from the source of 

impact. 

4.1.1.6.2. Live Bottoms (Low Relief) 

A new chapter describing live-bottom (low-relief) areas is included in this document. It is a summary 

of new information and the description of the biology of live-bottom (low relief) areas found in Chapter 

III.C.2 of Gulf of Mexico OCS Oil and Gas Lease 181: Eastern Planning Area, Final Environmental 

Impact Statement (Sale 181 EIS) (USDOI, MMS, 2001). 

A fine-grained quartz sand sheet covers most of the Mississippi-Alabama shelf; however, numerous 

hard bottoms formed of sedimentary rock occur in the CPA off the Mississippi River Delta and seaward 

of the Chandeleur Islands (Schroeder, 2000). Low-relief, hard-bottom features are located on the inner 

and middle Mississippi-Alabama shelf. These features include isolated low-relief, reef-like structures; 

rubble fields; low-relief flat rocks (e.g., 6 m long and 60 cm thick; 20 ft long and 2 ft thick); limestone 

ledges (e.g., 4 m [13 ft] high); rocky outcrops off Mobile Bay (18- to 40-m [59- to 131-ft] depth range; 

5 m wide and 2 m high; 16 ft wide and 7 ft high); and clustered reefs (e.g., tens of meters across and 3 m 

[10 ft] high) (Schroeder et al., 1988; Schroeder, 2000). 

The Live Bottom (Low Relief) Stipulation implemented by BOEMRE protects biological resources of 

live-bottom areas from potential impacts by oil and gas activities to a depth of 100 m (328 ft) in the EPA 

and a small northeastern portion of the CPA. The Live Bottom (Low Relief) Stipulation defines 

low-relief areas as “seagrass communities, areas that contain biological assemblages consisting of sessile 

invertebrates living upon and attached to naturally occurring hard or rocky formations with rough, broken, 

or smooth topography; and areas where a hard substrate and vertical relief may favor the accumulation of 

turtles, fish, or other fauna” (USDOI, MMS, 2009b). Sessile invertebrates may include sea fans, sea 

whips, hydroids, anemones, ascidians, sponges, bryozoans, or corals. The BOEMRE recommends the 

application of the Live Bottom (Low Relief) Stipulation for a proposed action within one of the OCS 

lease blocks that has low-relief features. 

4.1.1.6.2.1. Description of the Affected Environment 

Hard bottoms of various types are present in many locations of the Mississippi-Alabama Shelf and the 

West Florida Shelf (Figure 4-9). Sediments across the area east of the Mississippi River transition from 

the silt/clay of the delta to quartzose riverine sands of the eastern rivers, to the carbonate Florida platform 

characterized by carbonate sands and generally clear waters (east of De Soto Canyon). Hard-bottom 

features on the Mississippi-Alabama-Florida Shelf (MAFLA) typically provide reef habitat for tropical 

organisms, including sessile epifauna (soft corals, nonreef-building hard corals, sponges, bryozoans, 

crinoids) and fish; these areas are typically of low relief (<1 m; 3 ft) (Thompson et al., 1999). 

Live-bottom communities are widely scattered across the West Florida Shelf (Figure 4-9). The shelf 

is a relatively flat table of carbonate (karst limestone geology) that is largely covered with carbonate sand 

sheets. In many places, the sand moves around due to seasonal storms, forming ephemeral (temporary) 

patches of sand interspersed with exposed hard bottom. Various species of sessile (attached) reef fauna 

and flora grow on the exposed hard grounds. Some species, such as sea whips and other gorgonians that 

are tall enough, often survive when sand moves in to cover the bottom again. 

Some areas have enough relief to support permanent reefs. The Florida Middle Ground is probably 

the best known and most biologically developed of these areas on the West Florida Shelf, with extensive 

colonization by hermatypic (reef-building) corals and related communities. Several other reef areas are 
4-114 Central Planning Area Supplemental EIS 

present and have varying measures of protection including Pulley Ridge, Steamboat Lumps, Madison 

Swanson, and the Sticky Grounds (Figure 4-9). 

Ecology of Inner- and Middle-Shelf Hard Bottoms of the Mississippi-Alabama Shelf 

Nearshore hard-bottom areas are located on the Mississippi-Alabama shelf in 18-40 m (60-130 ft) of 

water (Figure 4-9). Inner- and middle-shelf features include rubble fields, low-relief flat rocks (e.g., 6 m 

long and 60 cm thick; 20 ft long and 2 ft thick), outcrops (e.g., 5 m wide and 2 m high; 16 ft wide and 7 ft 

high), limestone ledges (e.g., 4 m [13 ft] high), and clustered reefs (e.g., tens of meters across and 3 m 

[10 ft] high) (Schroeder, 2000). Four types of rock formations that form the hard-bottom areas are 

described by Schroeder et al. (1988). 

 massive to nodular sideritic sandstones and mudstones, which are scattered on the 

central and western portions of the shelf; 

 slabby-aragonite-cemented coquina and sandstone rubble associated with storm 

related ridges of shell and sand on the central shelf; 

 dolomitic sandstone in small irregular outcrops; and 

 calcite cemented algal calcirudite occurring in reef-like knobs on the southeastern 

shelf. 

Schroeder et al. (1988 and 1989) described four live-bottom areas west of De Soto Canyon: 

Southeast Bank, Southwest Rock, Big Rock/Trysler Grounds, and features at the 17 Fathom Hole (Figure 

4-9). 

 The Southeast Bank is a rock rubble field site in 21-27 m (69-87 ft) of water-bearing 

encrusting epifauna (mostly the soft corals Leptogorgia virgulata and Lophogorgia 

hebes). 

 The Southwest Rock area is in fact made of two rocks that are 10 m (33 ft) apart. 

The larger of the two is 7-9 m (23-30 ft) wide and 1-1.5 m (3-5 ft) high. The smaller 

rock is 1.5-3.5 m (5-11 ft) wide, but it is almost level with the surrounding rubble 

substrate. 

 The Big Rock/Trysler Grounds are 5 m (16 ft) tall mound-like structures of rock 

rubble found in 30-35 m (98-115 ft) of water. 

 The features at the 17 Fathom Hole are reef-like and mound-like. One reef-like 

feature was 100 m (328 ft) long, 35 m (115 ft) wide, and 2 m (7 ft) high. A moundlike feature was made of rock rubble, covered a 300 m2

 (3,228 ft2) area, and rose 2 m 

(7 ft) above the seafloor. 

The soft corals Leptogorgia virgulata and Lophogorgia hebes were the most frequently encountered 

encrusting organisms amongst inner- and mid-shelf hard bottoms. Other biotic cover, not as common as 

soft corals, was made of hydroids and bryozoans (Schroeder et al., 1988 and 1989). Brooks (1991) found 

shallow-water hard bottoms off Mobile Bay that support living algae communities. The 40-Fathom 

Isobath area is located 24 km (15 mi) northeast of the pinnacles area in water depths of approximately 

75 m (245 ft). This area consists of topographic features with up to 9 m (30 ft) of relief that are either 

mound-like, pinnacle-like, or ridge-like in form (Schroeder et al., 1988 and 1989). 

Head of De Soto Canyon 

Shipp and Hopkins (1978) found a hard-bottom area of large, rectangular limestone blocks rising up 

to 10 m (33 ft) off the seafloor near the head of De Soto Canyon in 55 m (180 ft) of water (Figures 4-9 

and 4-10). Live cover included sponges, nonreef-building hard coral (Oculina diffusa), soft corals 

(Lophogorgia cardinalis and L. hebes), and an antipatharian (Antipathes sp.). A diverse and abundant 
Description of the Environment and Impact Analysis 4-115 

tropical fish community was associated with the hard bottom. Benson et al. (1997) found another 

important hard bottom, the “De Soto Canyon rim feature,” on the western edge of the canyon head. 

Madison-Swanson Marine Reserve 

The Madison-Swanson Marine Reserve is 65 km (40 mi) southwest off Cape San Blas, Florida, in 

waters 60-95 m (200-315 ft) deep (Figure 4-4). It covers approximately 300 km2

 (115 mi2) and consists 

of relic reef formations. The reef has outcrops of 1- to 3-m (3- to 10-ft) relief with a ridge of 15-m (50-ft) 

relief and a series of pinnacles about 9 m (30 ft) high. It supports a deep reef community with sponges, 

sea fans, black corals, scattered Oculina corals, echinoderms, and crabs. It is protected as a grouper 

spawning site. 

Steamboat Lumps Marine Reserve 

The Steamboat Lumps Marine Reserve is 161 km (100 mi) south-southeast of Cape San Blas, Florida, 

in waters 70-100 m (230-330 ft) deep (Figure 4-4). It covers approximately 357 km2

 (138 mi2) and 

consists of relic reef formations. The reserve has a series of five broad terraces pockmarked with 

depressions. It supports a deep reef community with sponges, sea fans, black corals, scattered Oculina

corals, echinoderms, and crabs. It is protected as a grouper spawning site. 

Florida Middle Ground 

Amongst the most studied hard-bottom features of the West Florida Shelf in terms of live cover and 

relief are the outcroppings of the Florida Middle Ground. The crests of the Florida Middle Ground 

outcroppings support hard and soft corals, molluscs, crustaceans, echinoderms, sponges, polychaetes, 

algae, and fish (Hopkins et al., 1977). Jaap and Hallock (1991) found the Florida Middle Ground to be 

the most diverse habitat of the West Florida Shelf. The Florida Middle Ground is a series of outcroppings 

located 138 km (86 mi) south of Apalachee Bay and 150 km (93 mi) northwest of Tarpon Springs 

(Figure 4-4). They spread over a 35 km (21 mi) long and 11 km (7 mi) wide area, oriented north-south 

along its length. The outcroppings rise from a 40 m (131 ft) deep seafloor to within 23 m (75 ft) of the 

sea surface. The outcroppings are populated by tropical reef organisms, including live and dead corals, 

invertebrates, and fish (Grimm and Hopkins, 1977). More recent surveys of the Florida Middle Ground 

confirm continued health of the reef (ahermatypic corals, sponges, soft corals, and hydrozoans) 

(Mallinson et al., 1998 and 2006; Coleman et al., 2009). 

Sticky Grounds 

The Sticky Grounds is a trend of seafloor mounds about 185 km (115 mi) west of Tampa Bay, Florida 

(Figure 4-4). They occur in water depths of 120-130 m (390-425 ft). They are uniformly dispersed 

mounds of about 20 m (65 ft) in diameter with 10 m (33 ft) of relief. They are thought to be relic 

drowned reefs, similar to the Pinnacle Trend features (Locker, personal communication, 2008). 

Pulley Ridge 

The Pulley Ridge area consists of a series of submerged linear ridges likely representing the shoreline 

at the last sea level lowstand. Pulley Ridge is found in water depths of 60-110 m (200-360 ft) (Cash et 

al., 2010), trends in a north-south direction, and stretches approximately 300 km (200 mi) in the western 

part of the shelf off southwest Florida (Figure 4-4). It ranges about 5-15 km (3-9 mi) wide (Cash et al., 

2010; Jaap and Halley, 2008) and typically has about 10 m (33 ft) of relief. The southern 30 km 

(18.75 mi) of the reef is colonized by a robust reef community dominated by hermatypic (reef-building) 

stony corals, coralline red algae, and green algae (Halley et al., 2004; Jarrett et al., 2002). The most 

common corals are the lettuce corals (Leptoseris cucullata and Agaricia spp.) (Jaap and Halley, 2008), 

and the reef exhibits 10-60 percent coral cover (Culter et al., 2005). 

The bathymetry in the 70- to 90-m depth range is irregular, and numerous ledges, holes, and 

depressions are seen on the seafloor (CSA, 1988 and 1990). Where the coral reef is not prevalent, Pulley 

Ridge is capped by coralline algal growths (algal nodules and algal pavements), which provide additional 
4-116 Central Planning Area Supplemental EIS 

hard substrate for sessile epifauna even where the underlying rock is not exposed (CSA, 1990). Coralline 

algae appear to produce as much carbonate sediment as the stony corals; algal nodule and cobble zones 

are prevalent in deeper waters around much of the Ridge below 80 m (260 ft) (Halley et al., 2004). 

Baseline Conditions following the Deepwater Horizon Event 

The following sections contain all new data since the Multisale EIS and the 2009-2010 Supplemental 

EIS. Extensive literature, Internet, and database searches have been conducted for results of scientific 

data at pinnacle and low-relief, hard-bottom features following the DWH event. Although many research 

cruises have occurred, very few reports containing data have been released as of the publication of this 

Supplemental EIS. Descriptions of studies in progress are discussed, and any results indicated are 

included below. A few early data releases have indicated that baseline conditions near the well may have 

been changed from conditions described in the Multisale EIS and the 2009-2010 Supplemental EIS. 

The DWH event may have been located close enough to some hard-bottom features on the 

Mississippi-Alabama shelf to cause impacts. A recent report documents damage to a deepwater coral 

community 7 mi (11 km) southwest of the blowout, in an area that oil plume models predict as the 

direction of travel for subsea oil plumes from the DWH event. Results are still pending, but it appears 

that a coral community about 15 m x 40 m (50 ft x 130 ft) in size was severely damaged, possibly the 

result of oil impacts (USDOI, BOEMRE, 2010j). 

Larger pinnacle formations, the Alabama Alps (including the 36 Fathom Ridge) and Roughtongue 

Reef, were located beneath a portion of the surface oil plume during part of the DWH event (Boland et 

al., 2010). The Alabama Alps, 40 nmi (74 km; 46 mi) north of the well, was beneath the surface oil 

plume beginning April 29, 2010; the Roughtongue Reef, 100 nmi (185 km; 115 mi) northeast of the well, 

was beneath the plume beginning May 20, 2010 (Boland et al., 2010). They were still beneath the plume 

at the time of the writing of the Boland et al. (2010) document (July 2, 2010). These features will be 

studied to determine if they have been impacted similarly to the coral communities located closer to the 

well (Boland et al., 2010). 

Water column hydrocarbon measurements collected during the DWH event suggest that it is unlikely 

that the pinnacle features were acutely affected by the oil or dispersed oil. Water samples collected by the 

R/V Weatherbird on May 23-26, 2010, located 40 nmi (74 km; 46 mi) and 45 nmi (83 km; 52 mi) 

northeast of the DWH rig revealed that concentrations of total petroleum hydrocarbons in the water 

column were less than 0.5 ppm (Haddad and Murawski, 2010). The total petroleum hydrocarbons 

concentrations 40 nmi (74 km; 46 mi) northeast of the well were 0.480 ppm and 0.114 ppm at 50-m 

(164 ft) and 100-m (328-ft) depth, respectively. The total petroleum hydrocarbons concentrations 45 nmi 

(83 km; 52 mi) northeast of the well were 0.174 ppm and 0.237 ppm at 50 m (164 ft) and 100 m (328 ft), 

respectively (Haddad and Murawski, 2010). The crests and bases of the Alabama Alps and Roughtongue 

Reef fall between these two water depths and are 40 nmi (74 km; 46 mi) north and 100 nmi (185 km; 

115 mi) northeast of the well (Boland et al., 2010) (Figures 4-7 and 4-8). The measured total petroleum 

hydrocarbons in the water column near these features indicate the concentrations of total petroleum 

hydrocarbons that the hard-bottom features may have been exposed to were extremely low. 

Concentrations of oil in the 1 ppm range, which is higher than those recorded near the pinnacles, but 

in the range of concentrations of dispersed oil reported from different sites in other studies (McAuliffe et 

al., 1981a; Lewis and Aurand, 1997) are likely to cause chronic or short-term impacts to corals, as 

opposed to acute toxicity (Dodge et al., 1984; Wyers et al., 1986; Kushmaro et al., 1997). Therefore, any 

impacts to coral 40 nmi (74 km; 46 mi) north and 100 nmi (185 km; 115 mi) northeast of the well would 

be sublethal and may include reduced recruitment success, reduced growth, and reduced coral cover as a 

result of impaired recruitment (Kushmaro et al., 1997; Loya, 1975 and 1976a; Rinkevich and Loya, 

1977). 

Studies to Measure the Impact of the Deepwater Horizon Event 

Many studies have been planned to analyze the impact of the DWH event and some have been carried 

out already, although not all of the results have been analyzed or published at the time of the writing of 

this Supplemental EIS. The long-lasting impacts of this event will take years to determine. Initial data 

included in this chapter only show the immediate impact, primarily on water quality; long-term effects are 

not known. As more studies are conducted and more data are released, we will have a better 
Description of the Environment and Impact Analysis 4-117 

understanding of the breadth of the effects of the DWH event. The following descriptions outline studies 

that will be conducted in the Pinnacle Trend area and low-relief, hard-bottom areas. 

The NRDA has been approved to conduct an impact assessment to chemosynthetic, deepwater coral, 

and mesophotic coral (pinnacle) environments in the Gulf of Mexico as a result of the DWH event. Some 

pinnacle communities were beneath the surface plume of the oil spill for extended periods of time 

(Boland et al., 2010). The Alabama Alps, 40 nmi (74 km, 46 mi) north of the well, was beneath the 

surface oil plume beginning April 29, 2010; the Roughtongue Reef, 100 nmi (185 km; 115 mi) northeast 

of the well, was beneath the plume beginning May 20, 2010 (Boland et al., 2010). They were beneath the 

plume as of the release of the study (July 2, 2010). Studies at the pinnacles will include a comparison of 

new ROV video and digital imagery to previously collected images from prior studies and laboratory 

analysis of tissue and sediment for petroleum hydrocarbons (Boland et al., 2010). These data have yet to 

be published. 

Florida Atlantic University, Harbor Branch Oceanographic Institute, has conducted a “Rapid 

Response to the Deepwater Horizon Oil Spill” exploration of the Florida Shelf Edge. Although data have 

not been published at the time of this document’s release, the characterization of benthic and mid-water 

habitats was conducted from July 9 to August 7, 2010 (Pomponi, 2010). Mission objectives of the 

exploration included (1) benthic and mid-water habitat baseline and oil impact assessments, which 

targeted deepwater and shelf-edge reefs and hard-bottom essential fish habitat; (2) documenting oil and 

dispersant impacts on benthic and mid-water habitats and marine organisms; (3) documenting the location 

of any encountered submerged oil plumes; and (4) conducting education and outreach activities. The 

survey’s primary focus was on the West Florida Shelf; however, additional sites off other Gulf Coast 

States may have been added as the route of the vessel was flexible dependent on the path of the oil plume. 

Areas considered for study included the mesophotic and shelf-edge reefs (30-200 m; 100-656 ft) 

including habitat areas of particular concern and marine sanctuaries off Texas, including the Flower 

Garden Banks National Marine Sanctuary, shelf-edge paleoshores along the Alabama Shelf (The Alps), 

West Florida Shelf (Madison-Swanson Marine Reserve, Twin Ridges, and Florida Middle Ground), and 

Southwest Florida Shelf (Pulley Ridge and Tortugas Ecological Reserve Preserve). Deepwater sites 

(>200 m; 656 ft) that were studied included Lophelia coral habitat (Viosca Knoll, Mississippi Canyon, 

and De Soto Canyon) and the West Florida Shelf lithotherms (500 m; 1,640 ft) (Pomponi, 2010). 

The NOAA R/V Seward Johnson conducted a baseline survey of the water column and seafloor in 

areas of the GOM from which the data will be used to measure changes if oil from the DWH event 

reaches the areas investigated (USDOC, NOAA, 2010g). Submersibles and ROV’s were used to observe 

baseline conditions of coral reefs and benthic organisms along the deep reef and hard-bottom regions of 

the east, south, and west Florida shelf and slope. The research cruise followed a path from the Oculina 

reefs off southeast Florida, through the Straits of Florida to the Dry Tortugas, north through the eastern 

and northern GOM, and west along the Florida shelf and slope toward Alabama and Mississippi 

(USDOC, NOAA, 2010g). 

The limited data currently available on the impacts of the DWH event make it difficult to definitively 

say if any impacts have occurred or may occur to the Pinnacle Trend and low-relief, hard-bottom features 

in the CPA. It appears some impacts have occurred to deepwater corals within 7 mi (11 km) of the well, 

although definitive testing of samples is necessary. Oil dispersed near the source in 1,500 m (4,921 ft) of 

water depth formed underwater plumes that affected some deep-sea environments. However, that oil is 

carried by deepwater currents, which do not transit up onto the continental shelf (Pond and Pickard, 

1983). 

Once more data are released, we will have a better understanding of the measured impacts and 

possible long-term effects of this event. 

4.1.1.6.2.2. Impacts of Routine Events 

Background/Introduction 

The Live Bottom (Low Relief) Stipulation protection covers lease blocks that include waters less than 

100 m (328 ft) in the EPA and a portion of the northeastern CPA that was previously part of the EPA 

(Figure 4-4). Blocks subject to the Live Bottom (Low Relief) Stipulation, including those in the CPA, 

are not included in the area to be offered in the CPA proposed action. No lease sales since the 1980’s 

have included blocks in areas where this stipulation applies. However, CPA blocks adjacent to this area 
4-118 Central Planning Area Supplemental EIS 

are included in the CPA proposed action. The proposed Live Bottom (Low Relief) Stipulation is 

described in NTL 2009-G39 (USDOI, MMS, 2009b). The BOEMRE recommends the implementation of 

the Live Bottom (Low Relief) Stipulation for a proposed action within one of the OCS lease blocks that 

has low-relief features. The stipulation is designed to prevent drilling activities and anchor emplacement 

(the major potential impacting factors on these live bottoms resulting from offshore oil and gas activities) 

from damaging the low-relief features. Both exploration and development plans will be reviewed on a 

case-by-case basis to determine whether a proposed operation could impact a low-relief area. If it is 

determined from site-specific information derived from BOEMRE studies, published information from 

other research programs, geohazards survey information, or another source that the operation would 

impact a low-relief area, the operator may be required to relocate the proposed operation. 

Since the blocks covered by the Live Bottom (Low Relief) Stipulation are outside the area to be 

offered in the CPA proposed action, only those blocks adjacent to the CPA proposed action in the 

northeastern portion of the CPA could be affected by routine impacts (Figure 4-4 of this Supplemental 

EIS and Figure 2-1 of the 2009-2012 Supplemental EIS). The impact analysis presented below is for 

routine activities associated with the CPA proposed action. 

A number of OCS-related factors may cause adverse impacts on the live-bottom communities and 

features. Damage caused by anchoring, infrastructure and pipeline emplacement, infrastructure removal, 

blowouts, drilling discharges, produced-water discharges, and oil spills can cause mortality of live-bottom 

organisms or the alteration of sediments to the point that recolonization of the affected areas may be 

delayed or impossible. Impacts from oil spills and blowouts are discussed in Chapter 4.1.1.6.2.3. 

Construction Impacts on Low-Relief Features 

Anchoring may damage lush biological communities or the structure of the live-bottom features 

themselves, which attract fish and other mobile marine organisms. Anchor damage from support boats 

and ships, floating drilling units, and pipeline-laying vessels greatly disturb areas of the seafloor and are 

the greatest threats to live-bottom areas at these depths. The size of the affected area would depend on 

water depth, anchor and chain sizes, chain length, method of placement, wind, and current. Anchor 

damage may result in the crushing and breaking of hard bottoms and associated communities. It may also 

result in community alteration through reduced or altered substrate cover, loss of sensitive species, and a 

reduction in coral cover in heavily damaged areas (Dinsdale and Harriott, 2004). Anchoring often 

destroys a wide swath of habitat by being dragged over the seafloor or by the vessel swinging at anchor, 

causing the anchor chain to drag over the seafloor (Lissner et al., 1991). Damage to corals as a result of 

anchoring may take 10 or more years to recover, depending on the extent of the damage (Fucik et al., 

1984; Rogers and Garrison, 2001). Nearby species on these hard-bottom habitats that disperse larvae 

short distances, such as solitary species (cup corals, octocorals, and hydrocorals), may recolonize areas 

more rapidly than slow-growing colonial forms that disperse larval great distances (Lissner et al., 1991). 

Such anchoring damage, however, should be minimized on low-relief hard bottoms, as no bottomdisturbing activities are permitted on the live-bottom habitat. Such damage would only be possible if 

construction activities take place immediately adjacent to designated live-bottom (low-relief) blocks. 

The emplacement of infrastructure, including drilling rigs and platforms, on the seafloor would crush 

the organisms directly beneath the legs or mat used to support the structure. Pipeline emplacement 

directly affects the benthic communities through burial and disruption of the benthos and through 

resuspension of sediments. These resuspended sediments may obstruct filter-feeding mechanisms and 

gills of fishes and sedentary invertebrates. The areas affected by the placement of the platforms and rigs 

are predominantly soft-bottom regions where the infaunal and epifaunal communities are not as unique as 

the hard-bottom communities. 

Infrastructure emplacement and pipeline emplacement could result in suspended sediment plumes and 

sediment deposition on the seafloor. Considering the relatively elevated amounts of drilling muds and 

cuttings discharged per well (approximately 2,000 metric tons [2,205 tons] for exploratory wells—900 

metric tons [992 tons] of drilling fluid and 1,100 metric tons [1,213 tons] of cuttings—and slightly lower 

discharges for development wells) (Neff, 2005), potential impacts on biological resources of hard-bottom 

features should be expressly considered if drill sites occur in blocks adjacent to such features. Potential 

impacts could be incurred through increased water-column turbidity, the smothering of sessile benthic 

invertebrates, and local accumulations of contaminants. 
Description of the Environment and Impact Analysis 4-119 

Differences in the dispersal patterns for well cuttings and drilling muds result from differences in 

disposal methodology (surface disposal or bottom shunting). For example, well cuttings that are disposed 

of at the water’s surface tend to disperse in the water column and are distributed widely over a large area 

at low concentrations (CSA, 2004b; NRC, 1983). On the other hand, cuttings that are shunted to the 

seafloor are concentrated over a smaller area in piles instead of being physically dispersed over wide 

areas (Neff, 2005). The heaviest concentrations of well cuttings and drilling fluids, for both water-based 

and synthetic-based drilling muds, have been reported within 100 m (328 ft) of wells and are shown to 

decrease beyond that distance (CSA, 2004b; Kennicutt et al., 1996). They are usually distributed 

unevenly and in patches, often dependent on prevailing currents (CSA, 2004b). A gradient of deposition 

may reach up to 500 m (1,640 ft) from the well, depending on surrounding environmental conditions 

(Kennicutt et al., 1996). 

Although the Live Bottom (Low Relief) Stipulation requires that low-relief features be protected from 

impact, some cuttings may reach the live-bottom features. Surface-released cuttings rarely accumulate 

thicknesses of about 1 m (3 ft) immediately adjacent to the well; thicknesses are usually not higher than a 

few tens of centimeters (about 1 ft) in the GOM. A gradient that encompasses most of the cuttings settles 

within 100 m (328 ft) of the well site. Cuttings settle in a patchy distribution determined by water 

currents and limited to about 250 m (820 ft) from the well site (CSA, 2004b). The source of cuttings 

released at the surface would be, at the closest, in blocks adjacent to live-bottom (low-relief) habitats. 

However, low-relief features could react negatively to drill cuttings if they do contact the habitat. For 

example, the ahermatypic (nonreef-building) coral, Caryophyllia sp., which may be found on some of 

these hard-bottom habitats, has displayed a significant dose-response relationship with sediment loading 

where densities of the species decreased with an increase in drilling mud particles (Hyland et al., 1994). 

In order to protect live-bottom features, relocation of operations to avoid live-bottom areas, shunting 

drilling fluids and cuttings to avoid live-bottom areas, transportation of drilling fluids and cuttings to 

approved disposal sites, and/or site monitoring may be required. These measures would limit or prevent 

well drilling activities from occurring in sensitive live-bottom areas. If bottom shunting of cuttings is 

used to protect features, the live-bottom areas, including those of low relief, would be protected from 

burial. Also, the USEPA general NPDES permit sets special restrictions on discharge rates for muds and 

cuttings to protect biological features. Chapters 4.1.1.4.1 and 4.2.1.1.2.2 of the Multisale EIS detail the 

NPDES permit’s general restrictions and the impacts of drilling muds and cuttings on marine water 

quality and seafloor sediments. If cuttings and drilling fluids are transported to approved disposal sites, 

the live bottoms would be even further protected from sedimentation. Due to the Live Bottom (Low 

Relief) Stipulation and USEPA discharge regulations, turbidity and smothering impacts of sessile 

invertebrates on hard-bottom features caused by drilling muds and cuttings are anticipated to be 

minimized. 

Drilling fluid adhering to cuttings forms plumes that are rapidly dispersed on the OCS. 

Approximately 90 percent of the material discharged (cuttings and drilling fluid) settle rapidly to the 

seafloor, while 10 percent forms a plume of fine mud that drifts in the water column (Neff, 2005). 

Although drilling mud plumes may be visible 1 km (0.6 mi) from the discharge, rapid dilution of drilling 

mud plumes was reported within 6 m (20 ft) from the release point (Shinn et al., 1980; Hudson et al., 

1982). Drilling muds and cuttings may be diluted 100 times at a distance of 10 m (33 ft) from the 

discharge and 1,000 times at a distance of 100 m (328 ft) from the discharge (Neff, 2005). Dilution 

continues with distance from the discharge point, and at 96 m (315 ft) from the release point, a plume was 

measured only a few milligrams/liter above background suspended sediment concentrations (Shinn et al., 

1980). Suspended sediment concentrations 6 m (20 ft) from the discharge are often less than those 

produced during storms or from boat wakes (Shinn et al., 1980). With consideration that drilling is not 

allowed on live-bottom habitats, that protective measures must be taken to avoid low-relief features, and 

that field measurements of suspended solids rapidly decline with distance from the source, turbidity 

impacts to live-bottom communities should be minimized. 

There is little opportunity for drilling muds and cuttings to affect low-relief live bottoms. The 

low-relief, live-bottom habitats are mostly in the EPA, with some stretching westward into the edge of the 

CPA. Since the northeast portion of the CPA is not included in the area to be offered in the CPA 

proposed action, only activities on the northeast border of the CPA proposed action would be adjacent to 

some low-relief, live-bottom habitats. The Mississippi River flows into this area of the GOM, resulting in 

high levels of natural turbidity. This turbidity forms a gradient from the source with levels declining 
4-120 Central Planning Area Supplemental EIS 

farther from the source. So, while muds and cuttings from the CPA proposed action could drift to the 

east, they will decline to background levels before reaching sensitive live-bottom habitats. The organisms 

in this area are tolerant of turbid environments (Rogers, 1990; Gittings et al., 1992a) and should not be 

impacted by the residual suspended sediment discharged during the drilling of a well. Many of the 

organisms that predominate in these communities also grow tall enough to withstand the sedimentation 

that results from their typical turbid environment or they have flexible structures that enable the passive 

removal of sediments (Gittings et al., 1992a). Any mud that may reach these organisms can be removed 

by tentacle motion and mucus secretion (Shinn et al., 1980; Hudson and Robbin, 1980). 

Recruitment studies conducted by Continental Shelf Associates (CSA) and Texas A&M University, 

Geochemical and Environmental Research Group (GERG); Marine Resources Research Institute (MRRI); 

and others suggest that recovery of hard-bottom communities following a disturbance will be slow (CSA 

and GERG, 2001; MRRI, 1984; Montagna and Holmberg, 2000). Epibiont recruitment showed relatively 

slow development of fouling community constituents on recruitment plates. Early colonizers are 

opportunistic epifauna, such as hydroids, bryozoans, barnacles, and bivalves that are tolerant of sediment 

loading (CSA and GERG, 2001; MRRI, 1984). Basically, only the earliest successional stages were 

observed after 1 year (MRRI, 1984) and after 27 months of exposure (CSA and GERG, 2001), and the 

epibiota typically associated with nearby hard-bottom features were rare on the plates (CSA and GERG, 

2001). No sponges or corals had settled after 1 year (MRRI, 1984). Corals and sponges are known to 

display delayed recruitment and slow growth, and after 10 years corals and anemones were sparse on 

artificial reef habitats, and the community had still not reached “climax” state (MRRI, 1984). 

It is not known whether the results of the recruitment studies would have differed if the substrate had 

consisted of exposed patches of natural hard bottom; however, because analysis of artificial reefs exposed 

for months to several years also indicates slow community development, it can be anticipated that hardbottom communities take a long time to recruit and develop (MRRI, 1984). Although settling plates and 

artificial reefs may differ from natural reefs, they can help to indicate recruitment time in a defaunated 

area (MRRI, 1984). 

Long-Term and Operational Impacts on Low-Relief Features 

Drilling operations may impact live-bottom communities. Drilling operations in Puerto Rico have led 

to reduced coral cover out to 65 m (213 ft) from the well, probably as a result of cutting deposition 

(Hudson et al., 1982). Corals beyond this distance did not show reduced surface cover (Hudson et al., 

1982). Live bottoms of low-relief features may experience some deposition of cuttings, especially if a 

well is within a few hundred meters of a live bottom. Impacts as a result of cuttings disposal may reach 

100-200 m (328-656 ft) from a well (Montagna and Harper, 1996; Kennicutt et al., 1996). The proposed 

Live Bottom (Pinnacle Trend) Stipulation requires all bottom-disturbing activity to avoid direct contact 

with live-bottom habitat. Wells drilled near low-relief, live-bottom features may be required to shunt 

cuttings to within 10 m (33 ft) of the seafloor. Bottom shunting would help protect the live-bottom 

features because it results in localized deposition of cuttings at a depth that is often greater than the 

biological activity of the live bottoms or in an area that avoids the live bottoms. Further protection may 

be implemented if the cuttings and drilling fluids are transported to an approved disposal site. The 

implementation of the Live Bottom (Low Relief) Stipulation is anticipated to reduce exposure pathways 

of drilling activities to benthic organisms on live bottoms, eliminating long-term operational impacts, 

such as exposure to turbidity and sedimentation or associated contaminants. 

Impacts as a result of exposure to contaminants may occur to live-bottom organisms within 100-

200 m (328-656 ft) of the well as a result of offshore oil and gas production (Montagna and Harper, 1996; 

Kennicutt et al., 1996; Hart et al., 1989; Kennicutt, 1995; CSA, 2004b). Sand content, metals, barium, 

inorganic carbon, and petroleum products have all been reported to be elevated near platforms (Kennicutt, 

1995). Distribution of discharges tends to be patchy, have sharp gradients, and be directional (Kennicutt, 

1995). The greatest impacts occur in low-energy environments where depositions may accumulate and 

not be redistributed (Neff, 2005; Kennicutt et al., 1996). 

Elevated levels of barium, silver, cadmium, mercury, lead, and zinc were found out to 200 m (656 ft) 

from platforms and are likely a product of drilling muds and cuttings (Kennicutt et al., 1996; Hart et al., 

1989; Chapman et al., 1991; CSA, 2004b). Metal concentrations in sediments near gas platforms 

(approximately out to 100 m [328 ft]) have been reported above those that may cause deleterious 
Description of the Environment and Impact Analysis 4-121 

biological effects. The impacts are believed to be a result of metal toxicity originating from drill cuttings 

during the installation of the well, which remain in the sediment (Montagna and Harper, 1996; Carr et al., 

1996). Hydrocarbon enrichment has been reported within 25 m (80 ft) and out to 200 m (656 ft) of 

petroleum platforms, and the concentrations decreased with distance from the platforms (Hart et al., 1989; 

Chapman et al., 1991; Kennicutt, 1995; Kennicutt et al., 1996). The concentrations of PAH’s in the 

sediment surrounding platforms, however, were below the biological thresholds for marine organisms and 

appeared to have little effect on benthic organisms (Hart et al., 1989; McDonald et al., 1996; Kennicutt et 

al., 1996). If any of the drill cuttings reach live-bottom features, impacts from metal or hydrocarbon 

exposure may occur. Although the literature does not report the impacts to gorgonians or soft corals as a 

result of exposure to contaminants in cuttings, infauna have shown effects including reduced fecundity, 

altered populations, and acute toxicity (Montagna and Harper, 1996; Carr et al., 1996; Kennicutt et al., 

1996; Hart et al., 1989; Chapman et al., 1991; CSA, 2004b). Impacts to benthos would be reduced with 

distance from the discharge. 

Produced waters are discharged at the water surface throughout the lifetime of the production 

platform and may contain hydrocarbons, trace metals, elemental sulfur, and radionuclides (Kendall and 

Rainey, 1991). Heavy metals enriched in the produced waters include cadmium, lead, iron, and barium 

(Trefry et al., 1995). Produced waters may impact both organisms attached to the production platform 

and benthic organisms beneath the platform. A detailed description of the impacts of produced waters on 

water quality and seafloor sediments is presented in Chapter 4.2.1.1.2 of the Multisale EIS. 

Information is contradictory on the distance from a platform that produced waters can affect benthic 

communities. Impacts have been reported from 100 m (328 ft) of the source to 1 km (0.6 mi) from the 

source (Peterson et al., 1996; Armstrong et al., 1977; Osenberg et al., 1992). The produced waters, 

however, are rapidly diluted and impacts are generally only observed within proximity of the discharge 

point (Gittings et al., 1992b). Literature indicates that acute toxicity that may result from produced waters 

occurs “within the immediate mixing zone around a production platform” (Holdway, 2002). Past 

evaluation of the bioaccumulation of offshore produced-water discharges conducted by the Offshore 

Operators Committee (Ray, 1998) assessed that metals discharged in produced water would, at worst, 

affect living organisms found in the immediate vicinity of the discharge, particularly those attached to the 

submerged portion of platforms. Possibly toxic concentrations of produced water were reported 20 m 

(66 ft) from the discharge in both the sediment and the water column where elevated levels of 

hydrocarbons, lead, and barium occurred, but no impacts to marine organisms or sediment contamination 

were reported beyond 100 m (328 ft) of the discharge (Neff and Sauer, 1991; Trefry et al., 1995). 

Chronic exposure to produced waters may result in altered benthic communities favoring opportunistic 

species, altered species behavior, reduced growth, and decreased fecundity (Holdway, 2002). 

Naturally occurring radioactive material in produced water was not found to bioaccumulate in marine 

animals (2 species of mollusks and 5 species of fish) (Ray, 1998). Because high-molecular PAH’s are 

usually in such dilute concentrations in produced water, they pose little threat to marine organisms and 

their constituents, and they were not anticipated to biomagnify in marine food webs. Monocyclic 

hydrocarbons and other miscellaneous organic chemicals are known to be moderately toxic, but they do 

not bioaccumulate to high concentrations in marine organisms and are not known to pose a risk to their 

consumers (Ray, 1998). 

Produced waters may have some impact on live-bottom features, but the Live Bottom (Low Relief) 

Stipulation should help to reduce these impacts. The greatest impacts are reported adjacent to the 

discharge and out to 20 m (66 ft) from the discharge, but they are substantially reduced less than 100 m 

(328 ft) from the discharge. Because only a few potential live-bottom (low-relief) areas are adjacent to 

the area to be offered in the CPA proposed action, produced waters are not expected to reach the sensitive 

habitats in concentrations that would produce negative effects. The distance between the habitat and the 

discharge would allow for dispersion of the produced waters, reducing the concentration of discharged 

material to which the live bottoms may be exposed. The USEPA general NPDES permit restrictions on 

the discharge of produced water would also limit the impacts on biological resources of live bottoms. 

Structure-Removal Impacts on Low-Relief Features 

The impacts of structure removal on live-bottom benthic communities can include turbidity, sediment 

deposition, explosive shock-wave impacts, and scouring from trawling to retrieve debris. Both explosive 
4-122 Central Planning Area Supplemental EIS 

and nonexplosive removal operations would disturb the seafloor by generating considerable turbidity. 

Suspended sediment may evoke physiological impacts in benthic organisms including “changes in 

respiration rate, . . . abrasion and puncturing of structures, reduced feeding, reduced water filtration rates, 

smothering, delayed or reduced hatching of eggs, reduced larval growth or development, abnormal larval 

development, or reduced response to physical stimulus” (Anchor Environmental CA, L.P., 2003). The 

higher the concentration of suspended sediment in the water column and the longer the sediment remains 

suspended, the greater the impact. 

Sediment deposition that occurs in ahermatypic coral communities may smother benthic organisms, 

decreasing gas exchange, increasing exposure to anaerobic sediment, and causing physical abrasion 

(Wilber et al., 2005). Corals may experience reduced coverage, changes in species diversity and 

dominance patterns, alterations in growth rates and forms, decreased calcification, increased production 

of mucus, lesions, reduced recruitment, and mortality (Torres et al., 2001; Telesnicki and Goldberg, 

1995). Coral larvae settlement may be inhibited in areas where sediment has covered available substrate 

(Rogers, 1990; Goh and Lee, 2008). 

Corals have some ability to rid themselves of sediment through mucus production and ciliary action 

(Marszalek, 1981; Bak and Elgershuizen, 1976; Telesnicki and Goldberg, 1995). Octocorals and 

gorgonians are more tolerant of sediment deposition than scleractinian corals, as they grow erect and are 

flexible, reducing sediment accumulation and allowing easy removal (Marszalek, 1981; Torres et al., 

2001; Gittings et al., 1992a). Gorgonians, corals, and sponges on low-relief features have also been 

reported to protrude above accumulated sediment layers, and it is hypothesized that these organisms can 

resist burial by growing faster than the sediment accumulates over the hard substrate upon which they 

settle (Lissner et al., 1991). 

The shock waves produced by explosive structure removals may also harm benthic biota. However, 

corals and other sessile invertebrates have a high resistance to shock. O’Keeffe and Young (1984) 

described the impacts of underwater explosions on various forms of sea life using, for the most part, 

open-water explosions much larger than those used in typical structure-removal operations. They found 

that sessile benthic organisms, such as barnacles and oysters, and many motile forms of life, such as 

shrimp and crabs, that do not possess swim bladders were remarkably resistant to shock waves generated 

by underwater explosions. Oysters located 8 m (26 ft) away from the detonation of 135-kg (298-lb) 

charges in open water incurred a 5 percent mortality rate. Crabs distanced 8 m (26 ft) away from the 

explosion of 14-kg (31-lb) charges in open water had a 90 percent mortality rate. Few crabs died when 

the charges were detonated 46 m (151 ft) away. O’Keeffe and Young (1984) also noted “. . . no damage 

to other invertebrates such as sea anemones, polychaete worms, isopods, and amphipods.” 

Benthic organisms appear to be further protected from the impacts of subbottom explosive 

detonations by rapid attenuations of the underwater shock wave traversing the seabed away from the 

structure being removed. The shock wave is significantly attenuated when explosives are buried, as 

opposed to detonation in the water column (Baxter et al., 1982). Theoretical predictions suggest that the 

shock waves of explosives set 5 m (15 ft) below the seabed, as required by BOEMRE regulations, would 

further attenuate blast effects (Wright and Hopky, 1998). 

Charges used in OCS structure removals are typically much smaller than some of those cited by 

O’Keeffe and Young. The Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf: 

Programmatic Environmental Assessment (USDOI, MMS, 2005) predicts low impacts on the sensitive 

offshore habitats from platform removal precisely because of the effectiveness of the proposed stipulation 

in preventing platform emplacement in the most sensitive areas of the GOM. Impacts on the biotic 

communities, other than those on or directly associated with the platform, would be limited by the 

relatively small size of individual charges (normally 50 lb [27 kg] or less per well piling and per 

conductor jacket) and by the fact that charges are detonated 5 m (15 ft) below the mudline and at least 

0.9 seconds apart (timing needed to prevent shock waves from becoming additive) (USDOI, MMS, 

2005). Also, because the live-bottom (low-relief) areas are generally far from the CPA proposed action, 

adverse effects to live-bottom features should be prevented. 

Infrastructure or pipeline removal would impact the communities that have colonized the structures, 

many of which may also be found on live-bottom features. Removal of the structure itself would result in 

the removal of the hard substrate and the associated encrusting community. The overall community 

would experience a reduction in species diversity (both epifaunal encrusting organisms and the fish and 

large invertebrates that fed on them) with the removal of the structure (Schroeder and Love, 2004). The 
Description of the Environment and Impact Analysis 4-123 

epifaunal organisms attached to the platform would die once the platform is removed. However, the 

seafloor habitat would return to the original soft-bottom substrate that existed before the well was drilled. 

Some structures may be converted to artificial reefs. If the rig stays in place, the hard substrate and 

encrusting communities would remain part of the benthic habitat. The diversity of the community would 

not change and associated finfish species would continue to graze on the encrusting organisms. The 

community would remain an active artificial reef. However, plugging of wells and other reef-in-place 

decommissioning activities would still impact benthic communities as discussed above, since all the steps 

for removal except final removal from the water would still occur. 

Proposed Action Analysis 

The Live Bottom (Low Relief) Stipulation covers lease blocks that include waters less than 100 m 

(328 ft) in the EPA and a northeastern portion of the CPA that was previously part of the EPA 

(Figure 4-4). Blocks subject to the Live Bottom (Low Relief) Stipulation, including those in the CPA, 

are not included in the area to be offered in the CPA proposed action. No lease sales since the 1980’s 

have included blocks in areas where this stipulation applies. However, adjacent blocks in the CPA are 

included in the area to be offered in the CPA proposed action. For the CPA proposed action, 17-23 

exploration/delineation wells, 62-85 development wells, and 20-25 production structures are projected for 

offshore Subareas C0-60. There are 9-14 exploration/ wells, 23-33 development wells, and 2-3 

production structures projected for offshore Subareas C60-200. Few, if any, of the wells or production 

structures would be located near live-bottom (low-relief) areas because the areas are not included in the 

area to be offered in the CPA proposed action. Low-relief features would incur few incidences of anchor 

damage from support vessels for the same reason. Thus, anchoring events are not expected to impact the 

resource. Accidental anchor impacts, however, could occur, with recovery taking a few to many years, 

depending on the severity (Fucik et al., 1984; Rogers and Garrison, 2001; Lissner et al., 1991). 

Pipeline emplacement also has the potential to cause considerable disruption to the bottom sediments 

in the vicinity of the live bottoms (Chapter 4.1.1.8.1 of the Multisale EIS); however, the implementation 

of the proposed Live Bottom (Low Relief) Stipulation, or a similar protective measure, would restrict 

pipeline-laying activities as well as oil and gas activities in the vicinity of the low-relief communities. 

The actual effect of pipeline-laying activities on the biota of the low-relief communities would be 

restricted to the resuspension of sediments. Burial of pipelines is only required in water depths of 60 m 

(200 ft) or less. Therefore, only the shallowest live-bottom communities would be affected by the 

increased turbidity associated with pipeline burial. The laying of pipeline without burial produces much 

less resuspension of sediments. The enforcement of the Live Bottom (Low Relief) Stipulation would help 

to minimize the impacts of pipeline-laying activities. 

Summary and Conclusion 

Oil and gas operations discharge drilling muds and cuttings that generate turbidity, potentially 

smothering benthos near the drill sites. Deposition of drilling muds and cuttings near low-relief areas 

would not greatly impact the biota of the live bottoms because the biota surrounding the low-relief 

features in or near the CPA are adapted to turbid (nepheloid) conditions and high sedimentation rates 

associated with the outflow of the Mississippi River (Gittings et al., 1992a). Regional surface currents 

and water depth would largely dilute any effluent. Additional deposition and turbidity caused by a nearby 

well are not expected to adversely affect the low-relief environment because such fluids would be 

dispersed upon discharge. Mud contaminants measured in the region reached background levels within 

1,500 m (4,900 ft) of the discharge point (Shinn et al., 1993). Toxic impacts on benthos are limited to 

within 100-200 m (328-656 ft) of a well (Montagna and Harper, 1996; Kennicutt et al., 1996), and 

NPDES permit requirements limit discharge. The drilling of a well, therefore, would have localized 

impacts on the benthos near the well, which should be located away from live-bottom features according 

to the drilling stipulations. 

The toxicity of produced waters has the potential to adversely impact the live-bottom organisms; 

however, as previously stated, many of the low-relief areas are not in the area to be offered in the CPA 

proposed action and the proposed Live Bottom (Low Relief) Stipulation would prevent the placement of 

oil and gas facilities upon (and consequently would prevent the discharge of produced water directly 

over) low-relief, live-bottom habitats. 
4-124 Central Planning Area Supplemental EIS 

Platform removals have the potential to impact nearby habitats. As previously discussed, the 

platforms would not be constructed directly on low-relief areas because these areas are either not included 

in the area to be offered in the CPA proposed action or are protected by the Live Bottom (Low Relief) 

Stipulation, distancing blasts from sensitive low-relief habitats. Benthic organisms on live bottoms 

should also have limited impact because they are resistant to blasts, tolerant of turbidity, can physically 

remove some suspended sediment, and may be located above or be tall enough to withstand limited 

sediment deposition. The implementation of the Live Bottom (Low Relief) Stipulation would help to 

prevent smothering events. Since the live-bottom areas are either not included in the area to be offered in 

the CPA proposed action or are protected by the Live Bottom (Low Relief) Stipulation, most of the 

potential impacts on live bottoms from bottom-disturbing activities (structure emplacement and removal) 

and operational discharges associated with the CPA proposed action would be prevented. Any 

contaminants that reach live-bottom features would be diluted from their original concentration; therefore, 

impacts that do occur should be sublethal. 

Effects of the Proposed Action without the Proposed Stipulation 

Activities resulting from the CPA proposed action without the exclusion of live-bottom (low-relief) 

habitats from the CPA proposed action and the protection of the Live Bottom (Low Relief) Stipulation 

could have an extremely deleterious impact on portions of the low-relief areas. Mechanical damage from 

anchoring, drilling operations, and other installation activities is potentially the most damaging impact 

because these activities could destroy biological communities or damage the structure of the low-relief 

areas themselves. This may in turn reduce the habitat or shelter areas occupied by commercial and 

recreational fishes. Those areas actually subjected to mechanical disruption would be severely impacted. 

Potential impacts on the low-relief, live-bottom areas from other impact-producing factors associated with 

OCS activities (pipeline emplacement, discharges of muds and cuttings, and explosive structure removals) 

would damage live-bottom areas, particularly by smothering organisms with heavy layers of drilling 

muds and cuttings. 

4.1.1.6.2.3. Impacts of Accidental Events 

Background/Introduction 

The live-bottom (low-relief) features of the CPA sustaining sensitive offshore habitats are described 

in Chapter 4.1.1.6.2.1. Disturbances resulting from the CPA proposed action, including oil spills, 

blowouts, and chemical spills have the potential to disrupt and alter the environmental, commercial, 

recreational, and aesthetic values of live-bottom features of the CPA. Live bottoms (low relief) are 

defined in NTL 2009-G39, which describes the applicable lease stipulation effective on blocks in the EPA 

and several blocks in the northeast portion of the CPA (USDOI, MMS, 2009b). Note that none of those 

blocks are included in the area to be offered in the CPA proposed action. Therefore, oil and gas activities 

from this action do not coincide with the live-bottom (low-relief) habitats. Some areas leased as a result 

of the CPA proposed action could be adjacent to the sensitive habitats at the extreme western edge of the 

habitat range. 

A search was conducted for additional new information published since completion of the Multisale 

EIS and the 2009-2012 Supplemental EIS. Various Internet sources and journal articles were examined to 

discover any recent information regarding impacts of oil on benthic organisms. Sources investigated 

include literature published in journals and websites (NOAA, USEPA, and coastal universities). This is a 

new chapter describing accidental impacts to live-bottom (low-relief) areas. It is a summary of new 

information and the description of impacts to live bottoms (low relief) found in Chapter IV.D.1.a.(2)(a) of 

the Sale 181 EIS (USDOI, MMS, 2001b). 

Possible Modes of Exposure 

Oil released to the environment as a result of an accidental event may impact live-bottom features in 

several ways. Oil may be physically mixed into the water column from the sea surface, be injected below 

the sea surface and travel with currents, be dispersed in the water column, or be sedimented to particles 
Description of the Environment and Impact Analysis 4-125 

and sink to the seafloor. These scenarios and their possible impacts are discussed in the following 

sections. 

An oil spill that occurs at the sea surface would result in a majority of the oil remaining at the sea 

surface. Lighter compounds in the oil would evaporate and some components of the oil may dissolve in 

the seawater. Evaporation removes the most toxic components of the oil, while dissolution may allow 

bioavailability of hydrocarbons to marine organisms for a brief period of time (Lewis and Aurand, 1997). 

The oil may also emulsify with water or sediment to particles and fall to the seafloor. 

A spill that occurs below the sea surface (at the rig, along the riser between the seafloor and sea 

surface, or through leak paths on the BOP/wellhead) would result in only a portion of the released oil 

rising to the sea surface. If the leak is deep in the water column and the oil is ejected under pressure, oil 

droplets may become entrained deep in the water column (Boehm and Fiest, 1982). The upward 

movement of the oil may be reduced if methane in the oil is dissolved into the water column at high 

underwater pressures, reducing the oil’s buoyancy (Adcroft et al., 2010). Large oil droplets will rise to 

the sea surface, but the smaller droplets, formed by vigorous turbulence in the plume or the injection of 

dispersants, may remain neutrally buoyant in the water column, creating a subsurface plume (Adcroft et 

al., 2010). Oil droplets less than 100 μm (0.004 in) in diameter may remain in the water column for 

several months (Joint Analysis Group, 2010a). 

Impacts that may occur to benthic communities on live-bottom features as a result of a spill would 

depend on the type of spill, distance from the spill, relief of the biological feature, and surrounding 

physical characteristics of the environment (e.g., turbidity). The Live Bottom (Low Relief) Stipulation 

(appended to NTL 2009-G39) does not specify a buffer zone around low-relief, hard-bottom features, but 

it recommends that no bottom-disturbing activity occur near low-relief features that may impact the 

features, which results in drilling activities occurring away from low-relief, live-bottom features. This 

Agency has created the stipulation in order to protect hard-bottom habitats from disruption due to oil and 

gas activities. However, oil released during accidental events may reach live-bottom features. As 

described above, a portion of the oil released from a spill would rise to the sea surface, therefore, reducing 

impact to benthic communities by direct oil exposure. However, small droplets of oil that are entrained in 

the water column for extended periods of time may migrate onto live-bottom habitat. Although these 

small oil droplets will not sink themselves, they may also attach to suspended particles in the water 

column and then be deposited on the seafloor (McAuliffe et al., 1975). Exposure to subsea plumes, 

dispersed oil, or sedimented oil may result in long-term impacts such as reduced recruitment success, 

reduced growth, and reduced coral cover as a result of impaired recruitment. These impacts are discussed 

in the following sections. 

Surface Slicks and Physical Mixing 

Surface oil slicks can spread over a large area; however, the majority of the slick is comprised of a 

very thin surface layer of oil moved by winds and currents (Lewis and Aurand, 1997). Oil spills have the 

potential to foul benthic communities and cause lethal or sublethal effects to organisms that the oil 

contacts as it is moved over the sea surface. Low-relief, hard-bottom features may rise up to 4 m (13 ft) 

from the seafloor (Schroeder et al., 1988; Schroeder, 2000). Live-bottom features more than 10 m (33 ft) 

below the sea surface would be protected from contact with oil from surface slicks (Lange, 1985; 

McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002). 

Field data collected at the Atlantic entrance to the Panama Canal 2 months after a tanker spill has 

shown that subtidal coral did not show measurable impacts to the oil spill, presumably because the coral 

was far enough below the surface oil and the oil did not contact the coral (Rützler and Sterrer, 1970). A 

similar result was reported from a Florida coral reef immediately following and 6 months after a tanker 

discharged oil nearby (Chan, 1977). The lack of acute toxicity was again attributed to the fact that the 

corals were completely submerged at the time of the spill and that calm conditions prevented the oil from 

mixing into the water column (Chan, 1977). 

Disturbance of the sea surface by storms can mix surface oil into the water column, but the effects are 

generally limited to the upper 10-20 m (33-66 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich 

and Chan, 2002). Therefore, the depth of offshore live-bottom features below the sea surface should 

protect them from physical mixing of surface oil below the sea surface. Features in water depths 

shallower than 10 m (33 ft) would be more susceptible to oil impacts. However, low-relief live bottoms 
4-126 Central Planning Area Supplemental EIS 

nearshore are far from potential activities of the CPA proposed action. If dispersants are used, they would 

enable oil to mix into the water column and possibly impact organisms on the live-bottom features 

adjacent to the CPA proposed action. Dispersants are discussed later in this section. 

Subsurface Plumes 

A subsurface oil spill or plume could reach a live-bottom feature and would have the potential to 

damage the local biota contacted by oil. Such impacts on the biota may have severe and long-lasting 

consequences, including loss of habitat, biodiversity, and live coverage; change in community structure; 

and failed reproductive success. 

Although no buffer zone is established for low-relief features, they are protected from 

bottom-disturbing activity, which in turn results in petroleum-producing activities occurring away from 

low-relief features. In addition, live-bottom, low-relief lease areas are excluded from the CPA proposed 

action. The distancing of petroleum-producing activities from live-bottom features allows for several 

physical and biological changes to occur to the oil before it reaches sensitive benthic organisms. Oil 

becomes diluted as it physically mixes with the surrounding water. The longer and farther a subsea plume 

travels in the sea, the more dilute the oil will be (Vandermeulen, 1982; Tkalich and Chan, 2002). In 

addition, microbial degradation of the oil occurs in the water column, reducing toxicity (Hazen et al., 

2010; McAuliffe et al., 1981b). Subsea oil plumes transported by currents may not travel nearly as far as 

surface oil slicks because some oil droplets may conglomerate and rise or may be blocked by fronts, as 

was observed in the southern Gulf of Mexico during the Ixtoc spill (Boehm and Fiest, 1982). Should any 

of the oil come in contact with adult sessile biota, effects would be primarily sublethal, as the oil may be 

diluted by physical and biological processes by the time it reaches the features. Some low-level exposure 

impacts may be chronic, while others may be temporary, and some may not even be able to be measured 

over time. 

Although the Live Bottom (Low Relief) Stipulation protects benthic organisms from petroleumproducing activity, it is possible that low levels of oil transported in subsea plumes may reach benthic 

features. Several studies have reported results for oil impacts on both hermatypic (reef-building) and 

ahermatypic (nonreef-building) corals. Although not all of the same species studied are present on lowrelief, hard-bottom features, impacts are expected to be similar. For example, coral feeding activity may 

be reduced if it is exposed to low levels of oil. Experiments indicated that normal feeding activity of 

Porites porites and Madracis asperula were reduced when exposed to 50 ppm oil (Lewis, 1971). 

Tentacle pulsation of an octocoral, Heteroxenia fuscescens, has also been shown to decrease upon oil 

exposure, although recovery of normal pulsation was observed 96 hours after the coral was removed from 

the oil (Cohen et al., 1977). Porites furcata exposed to Marine Diesel and Bunker C oil reduced feeding 

and left their mouths open for much longer than normal (Reimer, 1975). 

Direct oil contact may result in coral tissue damage. Coral exposed to sublethal concentrations of oil 

for 3 months revealed atrophy of muscle bundles and mucus cells (Peters et al., 1981). Porites furcata

submersed in Bunker C oil for 1 minute resulted in 100 percent tissue death, although the effect took 

114 days to occur (Reimer, 1975). 

Reproductive ability may also be reduced if coral is exposed to oil. A hermatypic coral, Stylophora 

pistillata, and an octocoral, Heteroxenia fuscescens, neither of which are present in the Gulf of Mexico, 

but may show impacts similar to those that could occur in the Gulf, shed their larvae when exposed to oil 

(Loya and Rinkevich, 1979; Rinkevich and Loya, 1977; Cohen et al., 1977). Undeveloped larvae in the 

water column have a reduced chance of survival due to predation and oil exposure (Loya and Rinkevich, 

1979), which would in turn reduce the ability of larval settlement and reef expansion or recovery. A 

similar expulsion of gametes may occur in species that have external fertilization (Loya and Rinkevich, 

1979), such as those at the Flower Garden Banks (Gittings et al., 1992c), which may then reduce gamete 

survivorship due to oil exposure. 

The overall ability of a coral colony to reproduce may be affected by oil exposure. Reefs of 

Siderastrea siderea that were oiled in a spill produced smaller gonads than unoiled reefs, which resulted 

in reproductive stress for the oiled reef (Guzmán and Holst, 1993). Stylophora pistillata reefs exposed to 

oil had fewer breeding colonies, reduced number of ovaria per polyp, and significantly reduced fecundity 

compared with unoiled reefs (Rinkevich and Loya, 1977). Impaired development of reproductive tissue 

has also been reported for other reef-building corals exposed to sublethal concentrations of oil (Peters et 
Description of the Environment and Impact Analysis 4-127 

al., 1981). Larvae may not be able to settle on substrate impacted by oil. Field experiments on 

Stylophora pistillata showed reduced settlement rate of larvae on artificial substrates of oiled reefs 

compared with control reefs and lower settlement rates, with increasing concentrations of oil in test 

containers (Rinkevich and Loya, 1977). Impaired larval settlement as a result of oiled substrate may lead 

to slow recovery of a disturbed substrate (CSA and GERG, 2001; MRRI, 1984; Montagna and Holmberg, 

2000). Additionally, deeper habitats have slower rates of settlement, growth, and community 

development, and recruitment rates are reportedly slow in some live-bottom habitats (Montagna and 

Holmberg, 2000; CSA and GERG, 2001). It is possible that corals may not recruit to an oiled substrate 

for 10 years (MRRI, 1984). 

Any hermatypic corals present on shallower live-bottom habitats may experience photosynthetic and 

growth impacts. Oil exposure is believed to reduce photosynthesis and growth in corals; however, lowlevel exposures have produced counterintuitive and sometimes immeasurable results. Photosynthesis of 

the zooxanthellae in Diplora strigosa exposed to approximately 18-20 ppm crude oil for 8 hours was not 

measurably affected, although other experiments indicate that photosynthesis may be impaired at higher 

concentrations (Cook and Knap, 1983). A longer exposure (24 hours) of 20 mL/L oil markedly reduced 

photosynthesis in Stylophora pistillata; however, concentrations of 2.5 mL/L oil resulted in physiological 

stress that caused a measurable increase in photosynthesis as compared with controls (Rinkevich and 

Loya, 1983). Other impacts recorded include the degeneration and expulsion of photosynthetic 

zooxanthellae upon coral exposure to oil (Loya and Rinkevich, 1979; Peters et al., 1981). Long-term 

growth changes in Diploria strigosa that was exposed to oil concentrations up to 50 ppm for 6-24 hours 

did not show any measurably reduced growth in the following year (Dodge et al., 1984). 

Corals exposed to subsea oil plumes may also incorporate petroleum hydrocarbons into their tissue. 

Records indicate that Siderastrea siderea, Diploria strigosa, Montastrea annularis, and Heteroxenia 

fuscescens have accumulated oil from the water column and incorporated petroleum hydrocarbons into 

their tissues (Burns and Knap, 1989; Knap et al., 1982; Kennedy et al., 1992; Cohen et al., 1977). Most 

of the petroleum hydrocarbons were incorporated into the coral tissues, not their mucus (Knap et al., 

1982). However, hydrocarbon uptake may also modify lipid ratios of coral (Burns and Knap, 1989). If 

lipid ratios are modified, mucus synthesis may be impacted, adversely affecting coral ability to protect 

itself from oil through mucus production (Burns and Knap, 1989). While these species are not present in 

the live-bottom (low-relief) areas, similar effects may occur in live-bottom species. 

Sublethal effects, although often hard to measure, could be long lasting and affect the resilience of 

coral colonies to natural disturbances (e.g., elevated water temperature and diseases) (Jackson et al., 1989; 

Loya, 1976a). Continued exposure to oil from resuspended contaminated sediments could also impact 

coral growth and recovery (Guzmán et al., 1994). Any repetitive or long-term oil exposure could inhibit 

coral larvae’s ability to settle and grow, may damage coral reproductive systems, may cause acute toxicity 

to larvae, and may physically alter the reef interfering with larval settlement, all of which would reduce 

coral recruitment to an impacted area (Kushmaro et al., 1997; Loya, 1975 and 1976a; Rinkevich and 

Loya, 1977). Exposure of eggs and larvae to oil in the water column may reduce the success of a 

spawning event (Peters et al., 1997). Sublethal exposure to oil may be more detrimental to corals than 

high concentrations of oil (Cohen et al., 1977), as sublethal concentrations are typically more widespread 

and have a larger overall community effect. Therefore, the sublethal effects of oil exposure, even at very 

low concentrations, may result in compounded community impacts that have long-lasting effects. 

Dispersed Oil 

Chemically-dispersed oil from a surface slick is not anticipated to result in lethal exposures to 

organisms on live-bottom features. The chemical dispersion of oil promotes the weathering process and 

increases the surface area available for bacterial biodegradation. It also allows surface oil to penetrate to 

greater depths than physical mixing would permit and the dispersed oil will generally remain below the 

water’s surface (McAuliffe et al., 1981b; Lewis and Aurand, 1997). However, reports on dispersant 

usage on surface plumes indicate that a majority of the dispersed oil remains in the top 10 m (33 ft) of the 

water column, with 60 percent of the oil in the top 2 m (6 ft) (McAuliffe et al., 1981a). Dispersant usage 

also reduces the oil’s ability to stick to particles in the water column, minimizing sedimented oil traveling 

to the seafloor (McAuliffe et al., 1981a; Lewis and Aurand, 1997). 
4-128 Central Planning Area Supplemental EIS 

Field experiments designed to test dispersant use on oil spills reported dispersed oil concentrations 

between 1 and 3 ppm, 9 m (30 ft) below the sea surface, approximately 1 hour after treatment with 

dispersant (McAuliffe et al., 1981a and 1981b). Other studies indicated that dispersed oil concentrations 

were <1 ppm, 10 m (33 ft) below the sea surface (Lewis and Aurand, 1997). The above data indicate that 

the mixing depth of dispersed oil is less than the depths of the crests of most live-bottom features 

offshore, greatly reducing the possibility of exposure to dispersed surface oil. Features nearshore, in less 

than 10 m (33 ft) of water would be more susceptible to oil contact if oil reaches the area, but they are 

also farther from the CPA proposed action; this reduces their chance of contact and, if contact did occur, 

the oil would have more time to weather and biodegrade before contact. 

Any dispersed surface oil that may reach the benthic communities of live-bottom features in the Gulf 

of Mexico would be expected to be at very low concentrations (less than 1 ppm) (McAuliffe et al., 

1981a). Such concentrations would not be life threatening to larval or adult stages based on experiments 

conducted with coral (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Knap, 1987; Wyers et al., 1986; 

Cohen et al., 1977) and observations after oil spills (Jackson et al., 1989; Guzmán et al., 1991). Any 

dispersed oil in the water column that comes in contact with corals, however, may evoke short-term 

negative responses by the organisms such as reduced feeding and photosynthesis or altered behavior 

(Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 1984). 

Dispersants that are used on oil below the sea surface can travel with currents through the water and 

may contact benthic organisms on the live-bottom features. If the oil spill occurs near a live-bottom 

feature, the dispersed oil could be concentrated enough to harm the community. However, the longer the 

oil remains suspended in the water column traveling with currents, the more dispersed it will become. 

Weathering will also be accelerated and biological toxicity reduced (McAuliffe et al., 1981b). Although 

the use of subsea dispersants is a new technique and very little data are available on dispersion rates, it is 

anticipated that any oil that could reach live-bottom features will be in low concentration based on surface 

slick dilution data (McAuliffe et al., 1981a; Lewis and Aurand, 1997). Impacts resulting from exposure 

to dispersed oil are generally anticipated to be sublethal. 

The report of damage to deepwater corals on the continental slope (USDOI, BOEMRE, 2010i) as a 

result of exposure to oil from the DWH probably resulted from the use of dispersant at the source of the 

blowout. This situation was the first time subsea dispersants were used, and stratified density layers of 

water allowed the oil plume to remain at depth instead of dispersing into the water column (Joint Analysis 

Group, 2010a). The density bounded plume eventually contacted the coral. The decision to use subsea 

dispersants at the DWH was carefully weighed against the surrounding environment and anticipated 

environmental impacts. The decision to use subsea dispersants may not occur near protected habitats. 

For example, NOAA policy says that the application of dispersants must occur as far as possible from the 

Flower Garden Banks (Gittings, 2006). Also, because a stratified turbid watermass (the nepheloid layer) 

occurs near the seafloor on the continental shelf in the northwestern Gulf of Mexico no more than 20 m 

(66 ft) up into the water column, a depth that may engulf part or all of a live-bottom feature, 

decisionmakers probably would not select to use dispersants near the habitat. 

Sublethal impacts that may occur to coral and other invertebrates exposed to dispersed oil may 

include reduced feeding, reduced photosynthesis, reduced reproduction and growth, physical tissue 

damage, and altered behavior. Short-term, sublethal responses of Diploria strigosa were reported after 

exposure to dispersed oil at a concentration of 20 ppm for 24 hours (Knap et al., 1983; Wyers et al., 

1986). Although concentrations in this experiment were higher than what is anticipated for dispersed oil 

at depth, effects included mesenterial filament extrusion, extreme tissue contraction, tentacle retraction, 

localized tissue rupture (Wyers et al., 1986), and a decline in tentacle expansion behavior (Knap et al., 

1983). Normal behavior resumed within 2 hours to 7 days after exposure (Wyers et al., 1986; Knap et al., 

1983). This coral, however, did not show indications of stress when exposed to 1 ppm and 5 ppm of 

dispersed oil for 24 hours (Wyers et al., 1986). Diploria strigosa exposed to dispersed oil (20:1, 

oil:dispersant) showed an 85 percent reduction in zooxanthellae photosynthesis after 8 hours of exposure 

to the mixture (Cook and Knap, 1983). However, the response was sublethal, as recovery occurred 

between 5 and 24 hours after exposure and return to clean seawater. Investigations 1 year after Diploria 

strigosa was exposed to concentrations of dispersed oil between 1 and 50 ppm for periods between 6 and 

24 hours did not reveal any impacts to growth (Dodge et al., 1984; Knap et al., 1983). It should be noted, 

however, that subtle growth effects may have occurred but they were not measurable (Knap et al., 1983). 

This type of short-term exposure matches anticipated exposures, if any, to low-relief, live-bottom 
Description of the Environment and Impact Analysis 4-129 

features. Subsea oil plumes from a spill could be carried by currents to the features but would pass across 

or change directions, resulting in only short-term contact with any particular benthic feature. Many 

benthic organisms would return to normal in a few hours to days. 

Historical studies indicate that dispersed oil appeared to be more toxic to coral species than oil or 

dispersant alone. The greater toxicity may be a result of an increased number of oil droplets, resulting in 

greater contact area between oil and water (Elgershuizen and De Kruijf, 1976). The dispersant causes a 

higher water soluble fraction of oil contacting the cell membranes of the coral (Elgershuizen and De 

Kruijf, 1976). The mucus produced by coral, however, can protect an organism from oil. Both hard and 

soft corals have the ability to produce mucus; mucus production has been shown to increase when corals 

are exposed to crude oil (Mitchell and Chet, 1975; Ducklow and Mitchell, 1979). Dispersed oil, which 

has very small oil droplets, does not appear to adhere to coral mucus, and larger untreated oil droplets 

may become trapped by the mucus barrier (Knap, 1987; Wyers et al., 1986). However, entrapment of the 

larger oil droplets may increase long-term exposure to oil if the mucus is not shed in a timely manner 

(Knap, 1987; Bak and Elgershuizen, 1976). 

More recent field studies did not reveal as great an impact of dispersants on corals as were indicated 

in historical toxicity tests (Yender and Michel, 2010). This difference in reported damage probably 

resulted from a more realistic application of dispersants in an open field system and because newer 

dispersants are less toxic than the older ones (Yender and Michel, 2010). Field studies have shown oil to 

be dispersed to the part per billion level minutes to hours after the dispersant application, which is orders 

of magnitude below the reasonable effects threshold of oil in the water column (20 ppm) measured in 

some studies (McAuliffe, 1987; Shigenaka, 2001). 

Although dispersed oil may be toxic to corals during exposure experiments (Shafir et al., 2007; Wyers 

et al., 1986; Cook and Knap, 1983), untreated oil may remain in the ecosystem for long periods of time, 

while dispersed oil does not (Baca et al., 2005; Ward et al., 2003). The time of year and surrounding 

ecosystem must be considered when determining if dispersants should be used. Dispersant usage may 

result in reduced or shorter term impacts to coral reefs; however, it may increase the impacts to other 

communities, such as mangroves (Ward et al., 2003). Therefore, dispersant usage may be more 

applicable offshore than in coastal areas where other species may be impacted as well. Dispersants also 

would probably not be approved during peak coral spawning periods (e.g., August-September for major 

reef-building species) (Gittings et al., 1992c and 1994) in order to limit the impacts of oil pollution on the 

near-surface portion of the water column. 

Sedimented Oil (Oil Adsorbed to Sediment Particles) 

Smaller suspended oil droplets could be carried to the seafloor as a result of oil droplets adhering to 

suspended particles in the water column. Smaller particles have a greater affinity for oil (Lewis and 

Aurand, 1997). Oiled sediment that settles to the seafloor may affect organisms attached to live-bottom 

features. It is anticipated that the greatest amount of sedimented oil would occur close to the spill, with 

lesser concentrations farther from the source. Studies after a spill that occurred at the Chevron Main Pass 

Block 41C Platform in the northern Gulf of Mexico revealed that the highest concentrations of oil in the 

sediment were close to the platform and that the oil settled to the seafloor within 5-10 mi (8-16 km) of the 

spill site (McAuliffe et al., 1975). Therefore, if the spill occurs close to a live-bottom feature, the 

underlying benthic communities may be exposed to toxic hydrocarbons. However, because of the 

prohibition of bottom-disturbing activity on low-relief, live-bottom features and the fact that they are not 

included in the area to be offered in the CPA proposed action, these hard-bottom communities should be 

distanced from the heaviest oiled sedimentation effects. 

Some oiled particles may become widely dispersed as they travel with currents while they settle out 

of suspension. Settling rates are determined by size and weight of the particle, salinity, and turbulent 

mixing in the area (Poirier and Thiel, 1941; Bassin and Ichiye, 1977; Deleersbijder et al., 2006). Because 

particles will have different sinking rates, the oiled particles would be dispersed over a large area, most 

likely at sublethal or immeasurable levels. Studies conducted after the Ixtoc oil spill revealed that, 

although oil was measured on particles in the water column, measurable petroleum levels were not found 

in the underlying sediment (ERCO, 1982). Based on BOEMRE restrictions and the settling rates and 

behavior of sedimented oil, the majority of organisms that may be exposed to sedimented oil are 

anticipated to experience low-level concentrations. 
4-130 Central Planning Area Supplemental EIS 

Sublethal impacts to benthic organisms may include reduced recruitment success, reduced growth, 

and reduced coral cover as a result of impaired recruitment. Experiments have shown that the presence of 

oil on available substrate for larval coral settlement has inhibited larval metamorphosis and larval 

settlement (Kushmaro et al., 1997). Crude oil concentrations as low as 0.1 ppm on substrate upon which 

the coral larvae were to settle reduced larval metamorphosis occurrences by 50 percent after 8 days of 

exposure. Oil concentrations of 100 ppm on substrates only resulted in 3.3 percent of the test population 

metamorphosizing (Kushmaro et al., 1997). There was also an increased number of deformed polyps 

after metamorphosis due to oil exposure (Kushmaro et al., 1997). It is also possible that recurring 

exposure may occur to coral if sedimented oil is resuspended locally, possibly inhibiting coral growth and 

recovery in the affected areas (Guzmán et al., 1994). Oil stranded in sediment is reportedly persistent and 

does not weather much (Hua, 1999), so coral may be repeatedly exposed to elevated concentrations of oil. 

Adult coral, however, may be able to protect itself from low concentrations of sedimented oil through 

mucus production. Coral mucus may not only act as a barrier to protect coral from the oil in the water 

column, it has been shown to aid in the removal of oiled sediment on coral surfaces (Bak and 

Elgershuizen, 1976). Coral may use a combination of increased mucus production and ciliary action to 

rid themselves of oiled sediment (Bak and Elgershuizen, 1976). 

Blowout and Sedimentation 

Oil or gas well blowouts are possible occurrences in the OCS. Benthic communities exposed to large 

amounts of resuspended sediments following a subsurface blowout could be subject to sediment 

suffocation, exposure to toxic contaminants, and reduced light. Should oil or condensate be present in the 

blowout flow, liquid hydrocarbons could be an added source of negative impact on the benthos. 

Turbid waters allow less light penetrating to depth, which may result in reduced photosynthesis by the 

symbiotic zooxanthellae that live in hermatypic coral tissue and by calcareous algae (Rogers, 1990). 

Long-term exposures to turbidity have even resulted in significantly reduced skeletal extension rates in 

the scleractinian coral Montastraea annularis (Torres, 2001; Dodge et al., 1974) and acute decrease in 

calcification rates of Madracis mirabilis and Agaricia agaricites (Bak, 1978). The higher the 

concentration of suspended sediment in the water column and the longer the sediment remains suspended, 

the greater the impact. 

Suspended sediment that is transported by currents deep in the water column would not impact the 

benthic organisms on live-bottom features. Studies have shown that deep currents sweep around 

topographic features instead of over them, allowing the suspended sediment to remain at depth (Rezak et 

al., 1983; McGrail, 1982). A similar movement of water is anticipated around larger live-bottom features; 

therefore, suspended sediment or subsea oil plumes from depth would not be deposited on top of the 

elevated benthic organisms. However, lower relief features may experience slightly more deposition as 

currents may not sweep around them as much as the higher relief features. 

Sediment that settles out of upper layers of the water column may impact benthic organisms of livebottom features. Sediment deposition may smother benthic organisms, decreasing gas exchange, 

increasing exposure to anaerobic sediment, reducing light intensity, and causing physical abrasion 

(Wilber et al., 2005). Corals may experience reduced colony coverage, changes in species diversity and 

dominance patterns, alterations in growth rates and forms, decreased calcification, decreased 

photosynthesis, increased respiration, increased production in mucus, loss of zooxanthellae, lesions, 

reduced recruitment, and mortality (Torres et al., 2001; Telesnicki and Goldberg, 1995). Coral larvae 

settlement may also be inhibited in areas where sediment has covered available substrate (Rogers, 1990; 

Goh and Lee, 2008). Gorgonian larvae, for example, only settle on substrate that does not have 

accumulated sediment (Grigg, 1977). 

Impacts to corals as a result of sedimentation would vary based on coral species, the height to which 

the coral grows, degree of sedimentation, length of exposure, and the coral’s ability to clear the sediment. 

Impacts may range from sublethal effects such as reduced growth, alteration in form, reduced recruitment 

and productivity, and slower growth to death (Rogers, 1990). 

Corals have some ability to rid themselves of sediment through mucus production and ciliary action 

(Marszalek, 1981; Bak and Elgershuizen, 1976; Telesnicki and Goldberg, 1995). Scleractinian corals are 

tolerant of short-term sediment exposure and burial, but longer exposures may result in loss of 

zooxanthellae, polyp swelling, increased mucus production, reduced coral growth, and reduced reef 
Description of the Environment and Impact Analysis 4-131 

development (Marszalek, 1981; Rice and Hunter, 1992). Bleached tissue as a result of sediment exposure 

has been reported to recover in approximately a month (Wesseling et al., 1999). 

Solitary octocorals and gorgonians, which are abundant on many hard-bottom features, are more 

tolerant of sediment deposition than colony-forming scleractinian corals because the solitary species grow 

erect and are flexible, reducing sediment accumulation and allowing easy removal (Marszalek, 1981; 

Torres et al., 2001; Gittings et al., 1992a). Many of these organisms have even been observed to grow tall 

enough to resist burial during periods of sediment encroachment (Lissner et al., 1991). Branching and 

upright forms of scleractinian corals, such as Madracis mirabilis and Agaricia agaricites, also tend to be 

more tolerant of sediment deposition than massive, plating, and encrusting forms, such as Porites 

astreoides (Roy and Smith, 1971; Bak, 1978). Some of the more sediment-tolerant scleractinian species 

in the Gulf of Mexico include Montastraea cavernosa, Siderastrea siderea, Siderastrea radians, and 

Diploria strigosa (Torres et al., 2001; Acevedo et al., 1989; Loya, 1976b). Due to the influence of the 

Mississippi River in the CPA, waters are more turbid near the outflow of the River, and more turbidity 

tolerant species are present on live bottoms in this portion of the Gulf of Mexico. Because many of the 

species are more tolerant of turbidity and sedimentation, they could better survive exposure to increased 

sediment input (Gittings et al., 1992a). 

Since the BOEMRE-proposed stipulation would preclude bottom-disturbing activity near a low-relief, 

live-bottom feature, most adverse effects on live-bottom features from blowouts would likely be 

prevented. Petroleum-producing activities would be far enough removed that heavy layers of sediment 

suspended as a result of a blowout should settle out of the water column before they reach sensitive 

biological communities. Other particles that travel with currents should become dispersed as they travel, 

reducing turbidity and depositional impacts. Furthermore, sediment traveling at depth should remain at 

depth instead of rising to the top of live-bottom features. 

Response Activity Impacts 

Oil-spill-response activity may also impact sessile benthic features. Booms anchored to the seafloor 

are sometimes used to control the movement of oil at the water surface. Boom anchors can physically 

impact corals and other sessile benthic organisms, especially when booms are moved around by waves 

(Tokotch, 2010). Vessel anchorage and decontamination stations set up during response efforts may also 

break or kill hard-bottom features as a result of setting anchors. Anchor damage may result in the 

crushing and breaking of hard bottoms and associated communities. It may also result in community 

alteration through reduced or altered substrate cover, loss of sensitive species, and a reduction in coral 

cover in heavily damaged areas (Dinsdale and Harriott, 2004). Anchoring often destroys a wide swath of 

habitat by being dragged over the seafloor or by the vessel swinging at anchor, causing the anchor chain 

to drag over the seafloor (Lissner et al., 1991). Damage to corals as a result of anchoring may take 10 or 

more years to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and Garrison, 

2001). Nearby species on these hard-bottom habitats that disperse larvae short distances, such as solitary 

species (cup corals, octocorals, and hydrocorals) may recolonize areas more rapidly than slow-growing 

colonial forms that disperse larval great distances (Lissner et al., 1991). Effort should be made to keep 

vessel anchorage areas away from sensitive benthic features to minimize impact. 

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud may be forced out of the well and deposited on the seafloor near the well site. 

Any organisms beneath the extruded drilling mud would be buried. Based on the Low Relief (Live 

Bottom) Stipulation (appended to NTL 2009-G39), a well should be far enough away from live-bottom 

features to prevent extruded drilling muds from smothering sensitive benthic communities. However, if 

drilling muds were to travel far enough or high enough in the water column to contact a hard-bottom 

community, the fluid may smother the existing community. Low-relief communities would be more at 

risk for burial than the higher features. Experiments indicate that corals perish faster when buried beneath 

drilling mud than when buried beneath carbonate sediments (Thompson, 1979). Turbidity impacts may 

result in reduced photosynthesis or reduced growth (Rogers, 1990; Torres, 2001). Light layers of 

deposited sediment would most likely be removed by mucus and ciliary action (Marszalek, 1981; Bak and 

Elgershuizen, 1976; Telesnicki and Goldberg, 1995). 
4-132 Central Planning Area Supplemental EIS 

Proposed Action Analysis 

The BOEMRE blocks for which the Live Bottom (Low Relief) Stipulation applies are found in the 

EPA in water depths of less than 328 ft (100 m) and are located in the northeastern portion of the CPA. 

Although none of these blocks occur in an area to be offered by the CPA proposed action, a few of the 

blocks are adjacent to the area to be offered and are protected from impacts by oil gas activity through 

BOEMRE policies. Any impacting activity from a lease that extends beyond the area to be offered by the 

CPA proposed action into a live-bottom (low-relief) area would be restricted from contacting those 

sensitive habitats. 

The fact that the live bottom (low-relief) features do not coincide with the area to be offered by the 

CPA proposed action and that they are widely dispersed, combined with the probable random nature of 

any potential oil-spill locations, would serve to limit the extent of damage from any given oil spill to a 

live-bottom (low-relief) community. 

When surface spills are mixed into the water column, the oil is not expected to penetrate below a 

depth of about 10 m (33 ft). The water depths of blocks adjacent to live-bottom (low-relief) areas are 

much greater than 10 m (33 ft) (over 40 m; 130 ft). The use of dispersants could result in oil mixing into 

the water column and potentially reaching live-bottom (low-relief) communities. 

Blowouts would not occur near live-bottom (low-relief) features since the habitats are not in the CPA 

sale area. Furthermore, blowouts in blocks adjacent to live-bottom (low-relief) features are unlikely to 

impact the biota because oil would rapidly float to the surface. Oil that is ejected under pressure may 

produce tiny droplets that become entrained in the water column and that could possibly affect the livebottom (low-relief) communities. Sedimented oil or sedimentation as a result of a blowout would only 

reach a live-bottom (low-relief) community if both the blowout and the community are near the border of 

the CPA proposed action. 

Potential impacts to the live-bottom (low-relief) communities adjacent to the CPA from oil spills and 

blowouts are unlikely and are not expected to be significant. Chemical spills are also infrequent, of small 

quantity, and usually occur in surface waters. The BOEMRE policies for live-bottom (low-relief) areas 

would assist in preventing most of the potential impacts from oil and gas operations, including accidental 

oil spills, blowouts, and chemical spills. No significant impacts to the live-bottom (low-relief) area 

adjacent to the CPA proposed action are expected. 

Summary and Conclusion 

Live-bottom features represent a small fraction of the continental shelf area in the CPA. The fact that 

the live-bottom features are widely dispersed, combined with the probable random nature of oil-spill 

locations, serves to limit the extent of damage from any given oil spill to the live-bottom features. 

The depth below the sea surface to which many live-bottom features rise helps to protect them from 

surface oil spills. Because the concentration of oil becomes diluted as it physically mixes with the 

surrounding water and as it moves into the water column, any oil that might be driven to 10 m (33 ft) or 

deeper would probably be at concentrations low enough to reduce impact to these features. Features in 

water shallower than 10 m (33 ft) would be far from the source of activities in the CPA proposed action. 

A subsurface spill or plume may impact sessile biota of live-bottom features. Oil or dispersed oil 

may cause sublethal impacts to benthic organisms if a plume reaches these features. Impacts may include 

loss of habitat, biodiversity, and live coverage; change in community structure; and failed reproductive 

success. The distance of proposed activities from low-relief live bottoms provides considerable 

protection for the habitats. The Live Bottom (Low Relief) Stipulation would limit the potential impact of 

any activities that may approach low-relief habitats (such as pipeline right-of-ways) because the 

stipulation keeps the sources of such adverse events geographically removed from the sensitive biological 

resources of live-bottom features. The distance would serve to reduce turbidity and sedimentation, and 

any sedimented oil should be well dispersed, resulting in a light layer of deposition that would have low 

toxicity and be easily removed by the organism. 

The proposed Live Bottom (Low Relief) Stipulation would assist in preventing most of the potential 

impacts on live-bottom communities from blowouts, surface, and subsurface oil spills and the associated 

effects. Any contact with spilled oil would likely cause sublethal effects to benthic organisms because the 

distance of activity would prevent contact with concentrated oil. In the unlikely event that oil from a 

subsurface spill would reach the biota of a live-bottom feature, the effects would be primarily sublethal 
Description of the Environment and Impact Analysis 4-133 

and impacts would be at the community level. Any turbidity, sedimentation, and sedimented oil would 

also be at low concentrations by the time the live-bottom features were reached, resulting in sub-lethal 

impacts. 

Effects of the Proposed Action without the Proposed Stipulation 

The live-bottom features and associated biota of the CPA could be adversely impacted by oil and gas 

activities resulting from the CPA proposed action should they not be excluded from the CPA proposed 

action or restricted by the proposed Live Bottom (Low Relief) Stipulation. This would be particularly 

true should operations occur directly on top of or in the immediate vicinity of otherwise protected livebottom features. The area within the restricted zones would probably be the areas of the live-bottom 

features that are most susceptible to adverse impacts if oil and gas activities are not excluded or restricted 

by the Live Bottom (Low Relief) Stipulation. These impacting factors would include blowouts, surface 

oil spills, and subsea oil spills. Potential impacts from routine activities resulting from the CPA proposed 

action are discussed in Chapter 4.1.1.6.2.2. 

Oil spills as well as routine activities have the potential to considerably alter the diversity, cover, and 

long-term viability of the biota found on live-bottom features. Direct oil contact may result in acute 

toxicity (Dodge et al., 1984; Wyers et al., 1986). In most cases, recovery from disturbances would take 

10 years or more (MRRI, 1984; Fucik et al., 1984; Rogers and Garrison, 2001). Dispersants should not 

be applied near sensitive areas such as coral communities according to NOAA policy (Gittings, 2006). 

While not specifically regulated by the BOEMRE-proposed stipulation, their possible use is physically 

distanced by buffer zones created by BOEMRE stipulations. Dispersants could be applied at a spill close 

to sensitive features if the buffer zone between petroleum-producing activity and a sensitive feature is not 

written into the proposed stipulations. Indeed, disturbances, including oil spills and blowouts, would alter 

benthic substrates and their associated biota over large areas. In the unlikely event of a blowout, sediment 

resuspension (potentially with associated oil) could cause adverse turbidity and sedimentation conditions. 

In addition to affecting the benthic cover of a live-bottom feature, a blowout could alter the local benthic 

morphology, thus irreversibly altering the live-bottom community. Oil spills (surface and subsea) could 

be harmful to the local biota should the oil have a prolonged or recurrent contact with the organisms. 

Therefore, in the absence of the exclusions, the Live Bottom (Low Relief) Stipulation, or site-specific 

mitigations, the CPA proposed action could cause long-term (10 years or more) adverse impacts to the 

biota of the live-bottom features. 

4.1.1.6.2.4. Cumulative Impacts 

Background/Introduction 

This cumulative analysis considers the effects of impact-producing factors related to the CPA 

proposed action plus those related to prior and future OCS lease sales, and to tanker and other shipping 

operations that may occur and adversely affect live bottoms of low-relief, hard-bottom areas. A 

description of live-bottom (low-relief) areas is given in Chapter 4.1.1.6.2.1. Specific OCS-related, 

impact-producing factors considered in the analysis are structure emplacement and removal, anchoring, 

discharges from well drilling, produced waters, pipeline emplacement, oil spills, blowouts, and 

operational discharges. Non-OCS-related impacts including commercial fisheries, natural disturbances, 

anchoring by recreational boats, and other non-OCS commercial vessels, as well as spillage from import 

tankering, all have the potential to alter live bottoms. 

Oil and gas activities from this action do not coincide with the live-bottom (low-relief) habitats that 

are in the EPA and the northeast corner of the CPA; those blocks are excluded from the CPA proposed 

action. Some of the areas leased as a result of the CPA proposed action could be adjacent to the sensitive 

habitats at the extreme western edge of the habitat range. The Live Bottom (Low Relief) Stipulation 

prohibits bottom-disturbing activities in relevant blocks. Although those blocks are not in the area to be 

offered in the CPA proposed action, the stipulation would serve as a guideline for BOEMRE policy if 

activities in any adjacent blocks required right-of-way for construction or pipelaying. However, 

BOEMRE stipulations and mitigations do not protect the resources from activities outside of BOEMRE 

jurisdiction (i.e., commercial fishing, tanker and shipping operations, or recreational activities). 
4-134 Central Planning Area Supplemental EIS 

Severe and permanent physical damage may occur to low-relief features and the associated live 

bottoms as a result of non-OCS activities. It is assumed those biota associated with live bottoms of the 

CPA are well adapted to natural disturbances such as turbidity and storms; however, human disturbance 

could cause severe damage to live-bottom biota, possibly leading to changes of physical integrity, species 

diversity, or biological productivity. If such events were to occur, recovery to pre-impact conditions 

could take as much as 10 years (Fucik et al., 1984). 

Non-OCS activities have a greater potential to affect the hard-bottom communities of the region than 

BOEMRE-regulated activities. Natural events such as storms, extreme weather, and fluctuations of 

environmental conditions (e.g., nutrient pulses, low dissolved oxygen levels, seawater temperature 

minima, and seasonal algal blooms) may impact live-bottom communities. Live-bottom (low-relief) 

communities occur from the shoreline to 100 m (328 ft) of water and, because many of these features are 

located in shallow water, storm events may damage these environments. Currents are created by wave 

action that can resuspend sediments to produce added turbidity and sedimentation (Brooks, 1991; CSA, 

1992a). Storms can physically affect shallow-bottom environments, causing an increase in sedimentation, 

burial of organisms by sediment, a rapid change in salinity or dissolved oxygen levels, storm surge 

scouring, remobilization of contaminants in the sediment, and abrasion and clogging of gills as a result of 

turbidity (Engle et al., 2008). Storms have also been shown to uproot benthic organisms from the 

sediment (Dobbs and Vozarik, 1983) and breakage or detachment may occur as a result of storm activity 

(Yoshioka and Yoshioka, 1987). Such impacts may be devastating to a benthic community. 

Hypoxic conditions of inconsistent intensities and ranges also occur annually in a band that stretches 

along the Louisiana-Texas shelf each summer (Rabalais et al., 2002). The dissolved oxygen levels of 

bottom waters in the Gulf of Mexico hypoxic zone are less than 2 ppm during part of the summer season. 

Such low concentrations are lethal to many benthic organisms and may result in the loss of some benthic 

populations. Although this is mainly a character of the Louisiana-Texas shelf, its effect could reach some 

live-bottom (low-relief) communities in the northeast portion of the CPA. 

Recreational boating, fishing, and import tankering may severely impact local areas of live-bottom 

communities. Ships anchoring near major shipping fairways of the CPA or EPA may occasionally impact 

sensitive areas located near these fairways. Recreational and commercial fishermen also take advantage 

of the relatively shallow and easily accessible resources of the region and anchor at hard-bottom locations 

to fish. Much of the fishing on these habitats uses bottom fishing gear that may damage benthic 

organisms or may snag on the reefs and be lost. Such gear, particularly lines of varying thickness, can cut 

into the tissues of many benthic organisms during storm movement of bottom waters. 

Damage resulting from commercial fishing, especially bottom trawling, may have a severe impact on 

hard-bottom benthic communities. Bottom trawling in the Gulf of Mexico primarily targets shrimp from 

nearshore waters to depths of approximately 90 m (300 ft) (NRC, 2002). Although trawlers would not 

select areas with sharp relief as fishing ground, since rocky areas may entangle gear, many live-bottom 

areas have little or no relief and may be targeted by trawlers. Reports indicate that bottom trawling 

activity on hard-bottom substrates can overturn boulders and destroy epifaunal organisms (Freese et al., 

1999). Large emergent sponges and anthozoans may be particularly vulnerable to trawling activity, as 

these organisms grow above the substrate and can be caught and removed by trawling activity (Freese et 

al., 1999). Recovery rates of corals and coralline algae may take decades and depend on the extent of the 

impact, frequency of disturbance, other natural changes that occur to the habitat, and the organism’s life 

history (NRC, 2002). 

Structure placement and anchor damage from support boats and ships, floating drilling units, and 

pipeline-laying vessels that disturb areas of the seafloor are considered the greatest oil and gas OCSrelated threat to low-relief, hard-bottom areas. The size of the areas affected by chains associated with 

anchors and pipeline-laying barges would depend on the water depth, chain length, sizes of anchor and 

chain, method of placement, wind, and current (Lissner et al., 1991). Anchor damage could include 

crushing and breaking of live bottoms and associated communities. It may also result in community 

alteration through reduced or altered substrate cover, loss of sensitive species, and a reduction in coral 

cover in heavily damaged areas (Dinsdale and Harriott, 2004). Anchoring often destroys a wide swath of 

habitat by being dragged over the seafloor or by the vessel swinging at anchor, causing the anchor chain 

to drag over the seafloor (Lissner et al., 1991). Damage to corals as a result of anchoring may take 10 or 

more years to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and Garrison, 

2001). Nearby species on these hard-bottom habitats that disperse larvae short distances, such as solitary 
Description of the Environment and Impact Analysis 4-135 

species (cup corals, octocorals, and hydrocorals), may recolonize areas more rapidly than slow-growing 

colonial forms that disperse larvae great distances (Lissner et al., 1991). 

Both explosive and nonexplosive structure-removal operations disturb the seafloor; however, they are 

not expected to affect live-bottom (low-relief) communities because they are not in the area to be offered 

in the CPA proposed action and because many sessile benthic organisms are known to resist the 

concussive force of structure-removal-type blasts (O’Keeffe and Young, 1984). Also, BOEMRE 

regulations require charges to be detonated 5 m (15 ft) below the mudline, which would attenuate shock 

waves in the seafloor (Baxter et al., 1982). 

Routine discharges of drilling muds and cuttings by oil and gas operations could affect biological 

communities and organisms through a variety of mechanisms, including the smothering of organisms 

through deposition or less obvious sublethal toxic effects (impacts to growth and reproduction). The 

live-bottom (low-relief) areas, however, are not in the area to be offered in the CPA proposed action and 

are protected by the BOEMRE stipulation, including bottom shunting of drill cuttings away from the 

features if they are nearby. Even though the additive effects of drilling several wells adds more 

discharges to the environment, the CPA proposed action would be separated from the live-bottom (lowrelief) communities by distance. 

Drilling muds quickly disperse upon release and most of the material is rapidly deposited on the 

seafloor (Neff, 2005; Shinn et al., 1980; Hudson et al., 1982). The drilling fluid plume in the water 

column has been measured to be only a few milligrams per liter above background sediment 

concentrations 100 m (328 ft) from the discharge point, concentrations often less than those produced 

during storms or from boat wakes (Shinn et al., 1980). Deposition of drilling muds and cuttings in lowrelief areas are not expected to greatly impact the biota of the surrounding habitat for two reasons. First, 

the biota near the CPA proposed action that live on the low-relief, hard-bottom communities are adapted 

to turbid conditions and storm impacts (Chiappone and Sullivan, 1994; Gittings et al., 1992a), reducing 

their vulnerability to sedimentation. Second, BOEMRE policy does not allow the disturbance of lowrelief, hard-bottom communities and often requires bottom shunting of drilling material away from the 

sensitive habitat or requires that it be transported to approved disposal sites. Any exposure that may 

occur from muds and cuttings discharged as a result of the cumulative scenario would be temporary, 

primarily sublethal in nature, and the effects would be limited to small areas. Recovery to pre-impact 

conditions from these sublethal impacts would take place within 10 years (Fucik et al., 1984). 

Produced waters from petroleum operations are not likely to have a great impact on live-bottom 

communities. Produced waters are rapidly diluted, impacts are generally only observed within proximity 

of the discharge point, and acute toxicity that may result from produced waters occurs “within the 

immediate mixing zone around a production platform” (Gittings et al., 1992b; Holdway, 2002). There 

have been no reported impacts to marine organisms or sediment contamination beyond 100 m (328 ft) of 

the produced-water discharge (Neff and Sauer, 1991; Trefry et al., 1995). Rapid dilution of surface 

discharges was reported within 6 m (20 ft) from the release point (Shinn et al., 1980; Hudson et al., 1982). 

Drilling discharges may be diluted 100 times at 10 m (33 ft) from the discharge and 1,000 times at 100 m 

(328 ft) from the discharge (Neff, 2005). Dilution continues with distance from the discharge point; at 

96 m (315 ft) from the release point, Shinn et al. (1980) measured a plume as only a few milligrams per 

liter above background suspended sediment concentrations. Similar dilution factors can be expected for 

produced-water discharges. Because BOEMRE policy does not allow bottom-disturbing activities to 

impact live bottoms and because the habitats are not included in the area to be offered in the CPA 

proposed action, wells cannot be drilled in low-relief, hard-bottom features, eliminating the possibility of 

acute toxicity from the discharge. If any impacts were to occur, they would be sublethal and localized to 

habitats adjacent to the CPA proposed action. 

Since many of the low-relief live bottoms are not included in the area to be offered in the CPA 

proposed action, and because of the Live Bottom (Low Relief) Stipulation and site-specific mitigations, 

operators are not expected to place pipelines directly upon live-bottom communities. The effect of 

pipeline-laying activities on the biota of these communities would be restricted to the resuspension of 

sediments, possibly causing obstruction of filter-feeding mechanisms of sedentary organisms and gills of 

fishes. Adverse impacts from resuspended sediments would be temporary, primarily sublethal in nature, 

and the effects would be limited to small areas. Impacts may include “changes in respiration rate, 

abrasion and puncturing of structures, reduced feeding, reduced water filtration rates, smothering, delayed 
4-136 Central Planning Area Supplemental EIS 

or reduced hatching of eggs, reduced larval growth or development, abnormal larval development, or 

reduced response to physical stimulus” (Anchor Environmental CA, L.P., 2003). 

Because many of the low-relief live bottoms are not included in the area to be offered in the CPA 

proposed action and because of the other BOEMRE protection policies, hard-bottom communities would 

be protected from experiencing direct oiling as a result of a blowout because bottom-disturbing activities 

are not permitted to impact these communities. However, surface oil spills and dispersed oil may impact 

hard-bottom communities. Disturbance of the sea surface by storms can mix surface oil 10-20 m (33-66 

ft) into the water column (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002). This 

may result in direct oil contact for shallow, nearshore live-bottom communities. Direct oiling may result 

in lethal impacts to organisms or sublethal responses such as reduced feeding (Lewis, 1971; Cohen et al., 

1977; Reimer, 1975), tissue damage (Peters et al., 1981; Reimer, 1975), decreased reproductive ability 

(Loya and Rinkevich, 1979; Rinkevich and Loya, 1977; Cohen et al., 1977; Guzmán and Holst, 1993), 

reduced photosynthesis (Cook and Knap, 1983; Rinkevich and Loya, 1983; Loya and Rinkevich, 1979; 

Peters et al., 1981), incorporation of petroleum hydrocarbons into their tissue (Burns and Knap, 1989; 

Knap et al., 1982; Kennedy et al., 1992; Cohen et al., 1977), and reduced community resilience (Jackson 

et al., 1989; Loya, 1976a). 

Live-bottom communities farther offshore, in deeper water, would be protected from direct physical 

oil contact by depth below the sea surface unless dispersants are used. Any dispersed surface oil from a 

tanker or rig spill that may reach the benthic communities of low-relief features in the Gulf of Mexico at a 

depth greater than 10 m (33 ft) would be expected to be at very low concentrations (less than 1 ppm) 

(McAuliffe et al., 1981a and 1981b; Lewis and Aurand, 1997). Such concentrations would not be life 

threatening to larval or adult stages, based on experiments conducted with coral (Lewis, 1971; 

Elgershuizen and De Kruijf, 1976; Knap, 1987; Wyers et al., 1986; Cohen et al., 1977) and observations 

after oil spills (Jackson et al., 1989; Guzmán et al., 1991). Any dispersed or physically mixed oil in the 

water column that comes in contact with corals, however, may evoke short-term negative responses by 

the organisms, such as reduced feeding and photosynthesis or altered behavior (Wyers et al., 1986; Cook 

and Knap, 1983; Dodge et al., 1984). 

Potential blowouts are unlikely to impact the biota of the live-bottom features because they are not in 

the area to be offered in the CPA proposed action and because BOEMRE policy that does not allow 

drilling in areas of low-relief, hard-bottom communities. Therefore, these sensitive habitats are distanced 

from the potential lethal impacts of a blowout. If any blowouts from wells did occur, the suspended 

sediments should settle out of the water column before a majority of the material reached low-relief 

habitats. Any oil that becomes entrained in a subsurface plume will be dispersed as it travels in the water 

column (Vandermuelen, 1982; Tkalich and Chan, 2002). If oil were to contact the live-bottom features, 

concentrations should be sublethal, and the impacts may include loss of habitat, biodiversity, and live 

coverage; change in community structure; and failed reproductive success. In the highly unlikely event 

that oil from a subsurface spill could reach a coral-covered area in lethal concentrations, the recovery of 

this area could take in excess of 10 years (Fucik et al., 1984). 

Should the live-bottom (low-relief) habitats not be excluded and the Live Bottom (Low Relief 

Stipulation not be implemented for the CPA proposed action or for future lease sales, OCS activities 

could have the potential to destroy part of the biological communities and damage one or several live/

hard-bottom features. The most potentially damaging of these are the impacts associated with physical 

damages that may result from anchors, structure emplacement, and other bottom-disturbing operations. 

A recent report documents damage to a deepwater coral community 7 mi (11 km) southwest of the 

DWH blowout. Results are still pending, but it appears that a deepwater coral community about 

15 m x 40 m (50 ft x 130 ft) in size was severely damaged (USDOI, BOEMRE, 2010j). Surface oil was 

also reported above some live-bottom features; however, results of field studies in the area are pending at 

this time (Boland et al., 2010). 

The cumulative impacts of possible oil spills, along with the DWH event, are not anticipated to affect 

the overall live-bottom (low-relief) habitat. The limited data currently available on the impacts of the 

DWH event make it difficult to definitively say if any impacts have affected the live-bottom features in 

the CPA and EPA. It appears some impacts have occurred to corals within 7 mi (11 km) of the well. 

Water column sampling, however, indicated that concentrations of total petroleum hydrocarbons in the 

water column were less than 0.5 ppm, 40 and 45 nmi (74-83 km; 46-52 mi) northeast of the well (Haddad 

and Murawski, 2010), which is below concentrations known to cause acute toxicity, and are more likely 
Description of the Environment and Impact Analysis 4-137 

to cause low-level, short-term impacts to corals (Dodge et al., 1984; Wyers et al., 1986; Kushmaro et al., 

1997). If oil is released near a low-relief feature and concentrated oil is entrained in the water column (by 

turbulent discharge or use of dispersant), it could contact nearby live-bottom habitat with serious 

detrimental effects. Habitats receiving high concentrations of oil could take 10 or more years to recover 

(Fucik et al., 1984). However, since subsea plumes travel directionally with water currents, only habitats 

directly in the path of the plume would be affected. Therefore, the acute impacts of any large-scale 

blowout would likely be limited in scale and any additive impacts of several blowouts should only impact 

small areas on an acute level, with possible sublethal impacts occurring over a larger area. Live-bottom 

(low-relief) communities are not included in the area to be offered in the CPA proposed action and are 

protected by other BOEMRE policies, so these sensitive communities would be distanced from any 

possible blowouts. 

Summary and Conclusion 

Non-OCS activities that may occur in the vicinity of the low-relief, hard-bottom communities include 

boating and fishing, import tankering, and natural events such as extreme weather conditions, and 

extreme fluctuations of environmental conditions. These activities could cause damage to the low-relief, 

hard-bottom communities. Ships using fairways in the vicinity of communities anchor in the general area 

of live bottoms on occasion, and commercial and recreational fishermen take advantage of the relatively 

shallow and easily accessible resources of regional hard bottoms. These activities could lead to instances 

of severe and permanent physical damage. During severe storms, such as hurricanes, large waves may 

reach deep enough to stir bottom sediments, which could cause severe mechanical damage to organisms, 

including abrasion from suspended sand, bruising and crushing from tumbling rocks, and complete 

removal of organisms (Brooks, 1991; CSA, 1992a). Yearly hypoxic events may affect portions of 

live-bottom benthic populations in the northeast part of the CPA (Rabalais et al., 2002). 

Possible impacts from routine activities of OCS oil and gas operations include anchoring, structure 

emplacement and removal, pipeline emplacement, drilling discharges, and discharges of produced waters. 

In addition, accidental subsea oil spills or blowouts associated with OCS activities can cause damage to 

low-relief, hard-bottom communities. Long-term OCS activities are not expected to adversely impact the 

live-bottom environment, because these impact-producing factors are restrained by the continued 

implementation of protective lease stipulations and site-specific mitigations. The inclusion of the Live 

Bottom (Low Relief) Stipulation would preclude the occurrence of physical damage, the most potentially 

damaging of these activities. The impacts to the live/hard bottoms are judged to be infrequent because of 

the small number of operations in the vicinity of communities and the distance from the habitats. The 

impact to the live-bottom resource as a whole is expected to be slight because of the projected lack of 

community-wide impacts. 

Impacts from blowouts, pipeline emplacement, muds and cuttings discharges, other operational 

discharges, and structure removals should be minimized because of the proposed Live Bottom (Low 

Relief) Stipulation and the dilution of discharges and resuspended sediments in the area. Potential 

impacts from discharges would be further reduced by USEPA discharge regulations and permit 

restrictions. 

The incremental contribution of the CPA proposed action to the cumulative impact is expected to be 

slight, with possible impacts from physical disturbance of the bottom, discharges of drilling muds and 

cuttings, other OCS discharges, structure removals, and oil spills. Negative impacts should be restricted 

by the implementation of the Live Bottom (Low Relief) Stipulation, site-specific mitigations, and the 

distance of live-bottom habitats from the source of impacts. 

4.1.1.7. Topographic Features 

The BOEMRE has protected topographic features that support sensitive benthic communities since 

the early 1970’s. The Gulf of Mexico seafloor in the CPA is mostly mud bottoms with varying mixtures 

of sand in some areas. Due to periods of lower sea level in geologic history, a thick layer of salt is present 

in a stratum deep beneath the seafloor. This salt becomes liquid under high pressure and pushes its way 

up through faults in the seafloor. In doing so, it sometimes forces up rock strata to form a “salt diapir” 

protruding up above the surrounding soft-bottom seafloor. Wherever these upthrusts of rock protrude into 

the water column, they form a rock reef that supports reef organisms that are different from those on 
4-138 Central Planning Area Supplemental EIS 

typical soft bottoms. These reefs are relatively rare on the seafloor compared with the ubiquitous soft 

bottoms (Parker et al., 1983). These topographic highs, or subsea banks, provide an island of hard 

substrate in a virtual ocean of soft bottoms. As a result, reef communities develop and include many of 

the more sensitive species associated with Caribbean waters. 

“Topographic features” is a term that specifically refers to 37 subsea banks in the GOM that are 

protected from potential impacts by oil and gas activities. They are defined in this Agency’s NTL 

2009-G39, “Biologically-Sensitive Underwater Features and Areas,” as “isolated areas of moderate to 

high relief that provide habitat for hard-bottom communities of high biomass and diversity and large 

numbers of plant and animal species, and support, either as shelter or food, large numbers of 

commercially and recreationally important fishes.” 

Over time, knowledge of these communities has increased and protective measures have evolved. 

This Agency has conducted environmental studies in the GOM for the past 35 years. Protective measures 

were instituted based on the nature and sensitivity of bank habitats and their associated communities. 

These protections have developed into stipulations applied to OCS leases. The lease stipulations establish 

five categories of protection zones: No Activity Zone; 1,000-Meter Zone; 1-Mile Zone; 3-Mile Zone; and 

the 4-Mile Zone. The No Activity Zone surrounds the core of the bank and prohibits any contact with the 

seafloor. The other zones are buffers with restrictions on the discharge of drill cuttings. All 37 banks 

have the No Activity Zone and may have up to two of the other zones. Details of the restrictions are 

described in this Agency’s NTL 2009-G39. The Biological Stipulation Map Package (https://

www.boemre.gov/homepg/regulate/regs/ntls/2009NTLs/09-G39.pdf) includes drawings of each bank 

with associated protection zones. 

The BOEMRE has reexamined the analysis for topographic features presented in the Multisale EIS 

and the 2009-2012 Supplemental EIS, based on the additional information presented below. New 

information supports the previous assessments contained in the Multisale EIS. Results of searches that 

were conducted for available data indicating the impacts to topographic features as a result of the DWH 

event have also been included in this assessment. The full analyses of the potential impacts of routine 

activities, accidental events, and cumulative impacts associated with the CPA proposed action are 

presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. 

4.1.1.7.1. Description of the Affected Environment 

A detailed description of topographic features can be found in Chapter 3.2.2.1.2 of the Multisale EIS. 

Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.4.2 of the 2009-2012 Supplemental EIS. A search was 

conducted for additional new information published since completion of the Multisale EIS and the 2009-

2012 Supplemental EIS. Various Internet sources and journal articles were examined to discover any 

recent information regarding topographic features. Sources investigated include USGS, NOAA, USEPA, 

and coastal universities. Other sites were found through general Internet searches. The following 

information is a summary of the resource description incorporated from the Multisale EIS and the 2009-

2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

Topographic features are hard-bottom habitats and are rare compared with the ubiquitous soft bottoms 

in the GOM (Parker et al., 1983). They are typically upthrusts of rock due to uplift (salt diapirs) by 

underlying layers of salt deep under the seafloor. These topographic highs, or subsea banks, provide an 

island of hard substrate in a virtual ocean of soft bottoms. 

Wherever rock protrudes up into the water column, reef organisms thrive. The type of organisms 

inhabiting a reef is determined by environmental conditions. Major factors are the amount of light and 

sedimentation and the temperature. If conditions are very good, a coral reef is established; this is found in 

the WPA only at the Flower Garden Banks. Other reefs (rocky upthrusts) are too dark or have too much 

sedimentation for hermatypic (reef-building) corals to thrive in numbers adequate to build a coral reef. 

However, these deeper reefs have thriving communities that include some stony corals as well as 

gorgonians, black corals, soft corals, sponges, urchins, crabs, many other invertebrates, macroalgae, 

calcareous algae, and a healthy fish community. The characteristics of protected topographic features in 

the GOM are described in more detail below. 
Description of the Environment and Impact Analysis 4-139 

The habitat created by the topographic features and the organisms found upon them is important for 

the following reasons: 

 they support hard-bottom communities of high biomass, high diversity, and high 

numbers of plant and animal species; 

 they provide shelter, food, and nursery grounds that support large numbers of 

commercially and recreationally important fishes; 

 they are a unique and valuable component of the much larger ecosystem, providing 

essential functions not available elsewhere; 

 they provide a relatively pristine area suitable for scientific research (especially the 

East and West Flower Garden Banks); and 

 they have an aesthetically intrinsic value. 

Figure 4-11 depicts the location of 37 protected topographic features in the GOM; 21 in the WPA 

and 16 in the CPA. In 1998, USGS, in cooperation with BOEMRE and the Flower Garden Banks 

National Marine Sanctuary, surveyed the East and West Flower Garden Banks using high-resolution, 

multibeam mapping techniques (Gardner et al., 1998). In 2002, the same consortium mapped 12 more 

topographic features, including Rankin (1 and 2) and MacNeil Banks in the WPA; and Alderdice, 

Sonnier, Geyer, Bright, Jakkula, Bouma, McGrail, Rezak, and Sidner Banks in the CPA (Gardner et al., 

2002b). 

A total of 16 topographic features are protected in the CPA. The BOEMRE has created “No Activity 

Zones” around major topographic features in order to protect these habitats from disruption due to oil and 

gas activities. A “No Activity Zone” is a protective perimeter associated with a specific depth contour 

that is drawn around each feature; no contact with the seafloor is allowed including the placement of 

structures, drilling rigs, pipelines, anchoring and cables. These No Activity Zones are areas protected by 

BOEMRE policy. The NTL 2009-G39 also recommends that drilling would not occur within 152 m 

(500 ft) of a No Activity Zone of a topographic feature. This additional recommendation is based on 

essential fish habitat; any construction within the buffer would require project-specific consultation with 

NOAA. 

The surveys conducted by Gardner et al. (1998 and 2002b) revealed complex bathymetry in some 

areas surrounding the banks outside the No Activity Zones. Small seafloor features of moderate to high 

relief (8 ft [2.4 m] or higher) outside of the No Activity Zones of the larger banks are called “potentially 

sensitive biological features” and are considered important fish habitat. The potentially sensitive 

biological features provide surface area for the growth of sessile invertebrates and attract large numbers 

of fish. They are protected by BOEMRE from impacts of oil and gas activities as described by NTL 

2009-G39 in that no bottom-disturbing activities may cause impacts to potentially sensitive biological 

features. 

Benthic organisms on these topographic features are mainly limited by temperature, sedimentation, 

and low light. Extreme water temperature and light intensity are known to stress corals. Temperatures 

lower than 16 o

C (60.8 oF) reduce coral growth, while temperatures in excess of 34.4 oC (93.2 oF) impede 

coral growth and induce coral bleaching (loss of symbiotic zooxanthellae) (Kleypas et al., 1999a). While 

intertidal corals are adapted to high light intensity, most corals become stressed when exposed to 

unusually high light levels. Furthermore, although corals will grow or survive under low light level 

conditions, they do best submerged in clear, nutrient-poor waters (Kleypas et al., 1999a). 

Light penetration in the Gulf is limited by several factors including depth and events of prolonged 

turbidity. Hard substrates favorable to colonization by hermatypic coral communities in the northern Gulf 

are found on outer shelf, high-relief features. These substrates protrude above the nepheloid layer (layer 

of high turbidity) that lies above the muddy seafloor and are bathed most of the year in nutrient-poor 

waters (Rezak et al., 1990). The depth of these banks (18 m [59 ft] or more below the sea surface) 

reduces the effects of storms on the habitats. Whereas typical Caribbean shore reefs can suffer extensive 

damage from tropical storms, only the strongest storms reach down to reefs in the GOM. The most 

common influence of strong storms on these banks is an increase in turbidity, generally at the lower levels 
4-140 Central Planning Area Supplemental EIS 

of the banks (Rezak et al., 1990). Turbidity and sedimentation are normal in these lower levels because 

of the nepheloid layer and normal resuspension of soft bottom sediments. 

Gulf of Mexico reefs span a range of environments, resulting in a range of community types. 

Habitats that can be classified as true coral reefs are few in the northern GOM: limited to the East and 

West Flower Garden Banks, a small area of McGrail Bank, and part of Pulley Ridge (in the eastern 

GOM). Other banks support reef communities with varying degrees of diversity, depending on 

environmental conditions. Many of these harbor a variety of corals, including some hermatypic corals, 

but not in densities that build a thriving, accreting coral reef. The banks of the GOM have been identified 

and classified into seven distinct biotic zones (Table 3-3 of the Multisale EIS) (modified/from Rezak and 

Bright, 1981; Rezak et al., 1983); however, none of the banks contain all seven zones. The zones are 

divided into the following four categories depending upon the degree of reef-building activity in each 

zone. 

Zones of Major Reef Building and Primary Production 

Diploria-Montastraea-Porites Zone 

This zone is characterized by 18-20 hermatypic coral species and is only found at the East and West 

Flower Garden Banks in the WPA in water depths less than 36 m (118 ft) (Rezak et al., 1990). The 

dominant species/of the zone in order of dominance are the Montastraea annularis complex (this group 

includes M. franksi, M. faveolata, and M. annularis), Diploria strigosa, Porites astreoides, and

Montastraea cavernosa (Precht et al., 2008; Robbart et al., 2009). Coralline algae are abundant in areas, 

which adds substantial amounts of calcium carbonate to the substrate and serves to cement the reef 

together. In addition to the coralline algae, there is a considerable amount of bare reef rock, which 

fluctuates in percent cover with the appearance of a red-turf like algae. 

Typical sport and commercial fish and invertebrates observed in this zone include various grouper 

species; amberjack; barracuda; red, gray, and vermilion snapper; cottonwick; porgy; spiny lobsters; and 

shovel-nosed lobster (Rezak et al., 1983). There is also a diverse group of tropical reef fish species found 

on these banks, including creole fish; queen, stoplight, red band, and princess parrot fish; rock beauty; 

blue tang, and the whitespotted filefish, just to name a few. There are over 175 tropical reef species that 

reside within the high-diversity zone at the Flower Garden Banks (Dennis and Bright, 1988; Pattengill, 

1998). 

Madracis and Fleshy Algal Zone 

The Madracis Zone is dominated by the small branching coral Madracis mirabilis, which produces 

large amounts of carbonate sediment (Rezak et al., 1990). In places, large (possibly ephemeral) 

populations of turf-like algae dominate the Madracis gravel substratum (Algal Zone). The Madracis

Zone appears to have a successional relationship with the Diploria-Montastraea-Porites Zone. Madracis

colony rubble builds up the substrate and allows the successional species to grow (Rezak et al., 1983). 

The zone occurs at the East and West Flower Garden Banks on peripheral components of the main reef 

structure between 28 and 46 m (92 and 151 ft) (Rezak et al., 1990). 

Stephanocoenia-Millepora Zone 

The Stephanocoenia-Millepora Zone is inhabited by a low-diversity coral assemblage of 12 

hermatypic corals and can be found at McGrail, and Bright Banks in the CPA. The eight most 

conspicuous corals in order of dominance are Stephanocoenia michelini, Millepora alcicornis, 

Montastraea cavernosa, Colpophyllia natans, Diploria strigosa, Agaricia agaricites, Mussa angulosa, 

and Scolymia cubensis (Rezak et al., 1983). The assemblages associated with this zone are not well 

known; coralline algae is the dominant organism in the zone. The American thorny oyster (Spondylus 

americanus) is common in this zone along with populations of some reef fish (Rezak et al., 1983). The 

depth range of this zone is between 36 and 52 m (118 and 171 ft) (Rezak et al., 1990). 
Description of the Environment and Impact Analysis 4-141 

Algal-Sponge Zone 

The Algal-Sponge Zone covers the largest area among the reef-building zones. Sonnier, McGrail, 

Geyer, and Bright banks all exhibit this community. The dominant organisms of the zone are the 

coralline algae, which are the most important carbonate producers. The algae produce nodules called 

“rhodoliths,” which are composed of over 50 percent coralline algae, and form large beds on the seafloor. 

The rhodoliths range from 1 to 10 cm (0.4 to 4 in) in size, cover 50-80 percent of the bottom, and 

generally occur in water depths between 55 and 85 m (180 and 280 ft) (Rezak et al., 1983). The habitat 

created by the alga nodules supports communities that are probably as diverse as the coral-reef 

communities. Most of the leafy algae found on the banks occur in this zone and contribute large amounts 

of food to the surrounding communities. Calcareous green algae (Halimeda and Udotea) and several 

species of hermatypic corals are major contributors to the substrate (Rezak et al., 1983). Deepwater 

alcyonarians are abundant in the lower Algal-Sponge Zone. Sponges, especially Neofibularia 

nolitangere, are conspicuous. Echinoderms are abundant and also add to the carbonate substrate. Small 

gastropods and pelecypods are abundant (Rezak et al., 1983). Gastropod shells are known to form the 

center of some of the algal nodules. Characteristic fish of the zone are yellowtail reef fish, sand tilefish, 

cherubfish, and orangeback bass (Rezak et al., 1983). 

Partly drowned reefs are a major substrate of the Algal-Sponge Zone. They are shallow carbonate 

reefs that are outpaced by sea-level rise and subsidence (Schlager, 1981). Their accumulation of 

carbonate is slower than relative sea-level rise so that, over time, they are found deeper and deeper in the 

water until they are no longer an accreting coral reef. In addition to the organisms typical to the rest of 

the Algal-Sponge Zone, the partly drowned reefs are also inhabited by large anemones, large comatulid 

crinoids, basket stars, limited crusts of Millepora, and infrequent small colonies of other hermatypic 

species (Rezak et al., 1983). The relief and habitat provided by the carbonate structures also attract a 

variety of fish species, especially yellowtail reef fish, reef butterfly fish, spotfin hogfish, orangeback bass, 

cherubfish, wrasse bass, longjaw squirrelfish, and several grouper species (Dennis and Bright, 1988). 

Zone of Minor Reef Building 

Millepora-Sponge Zone 

The Millepora-Sponge Zone occupies depths comparable to the Diploria-Montastraea-Porites Zone 

on the claystone-siltstone substrate of the Texas-Louisiana midshelf banks. Sonnier Bank exhibits this 

community between 18 and 52 m (Robbart et al., 2009). One shelf-edge carbonate bank, Geyer Bank, 

also exhibits the zone but only on a bedrock prominence. Crusts of the hydrozoan coral, Millepora 

alcicornis, sponges, and other epifauna occupy the tops of siltstone, claystone, or sandstone outcrops in 

this zone. Scleractinian corals and coralline algae are rarely observed, largely due to seasonal 

temperatures that drop below the 18 o

C (64 oF) minimum requirement for vigorous coral reef growth 

(Rezak et al., 1990). 

Transitional Zone of Minor to Negligible Reef Building 

Antipatharian Zone 

This transitional zone is not distinct but blends in with the lower Algal-Sponge Zone. It is 

characterized by an abundance of antipatharian whips growing with the algal-sponge assemblage (Rezak 

et al., 1983). With increased water depth, the assemblages of the zone become less diverse, characterized 

by antipatharians, comatulid crinoids, few leafy or coralline algae, and limited fish (yellowtail redfish, 

queen angelfish, blue angelfish, and spotfin hogfish). Again, the depth of this zone differs at the various 

banks but generally extends to 90-100 m (295-328 ft) (Rezak et al., 1990). 

Zone of No Reef Building 

Nepheloid Zone 

High turbidity, sedimentation, and resuspension occur in this zone. Rocks or drowned reefs are 

covered with a thin veneer of sediment and epifauna are scarce. The most noticeable are comatulid 
4-142 Central Planning Area Supplemental EIS 

crinoids, octocoral whips and fans, antipatharians, encrusting sponges, and solitary ahermatypic corals 

(Rezak et al., 1990). The fish fauna is different and less diverse than those of the coral reefs or partly 

drowned reefs. These fish species include red snapper, Spanish flag, snowy grouper, bank butterflyfish, 

scorpionfishes, and roughtongue bass (Rezak et al., 1983). This zone occurs on all banks, but its depth 

differs at each bank. Generally, the Nepheloid Zone begins at the limit of the Antipatharian Zone and 

extends to the surrounding soft bottom (Rezak et al., 1990). 

Banks of the Central Planning Area 

Shelf-Edge Banks Midshelf Banks South Texas Banks 

Alderdice Bank Fishnet Bank WPA Only 

Bouma Bank Sackett Bank 

Bright Bank Sonnier Bank 

Diaphus Bank 

Elvers Bank 

Ewing Bank 

Geyer Bank 

Jakkula Bank 

McGrail Bank 

Parker Bank 

Rezak Bank 

Sidner Bank 

Sweet Bank 

Shelf-Edge Banks 

The shelf-edge banks of the Central Gulf (Geyer, Sackett, Diaphus, Alderice, McGrail, and Bright) 

(Figure 4-11) generally exhibit the Algal-Sponge zonation (where present) that transitions into the deep, 

turbid Nepheloid Zone that is exhibited at these Banks (Rezak et al., 1983). However, Geyer Bank (37 m 

[121 ft] crest), which is within the depth of the high-diversity, coral-reef zone, does not exhibit the highdiversity characteristics. Instead, Geyer Bank has a well-developed Millepora-Sponge Zone, which is 

typically the defining characteristic of midshelf banks found elsewhere in the GOM (Rezak et al., 1983). 

The hydrocoral Millepora and various sponges have dominated the reef crests in the past. A surprising 

quantity of a benthic Sargassum macroalgae was documented by Robbart et al. (2009) in a recent study. 

The algae grows up to about a 0.5 m (1.5 ft) tall, providing considerable upright structure and cover for 

invertebrates and fish over a large portion of the reef cap. Upper portions of the bank house small 

branching corals (Madracis), leafy calcareous algae (Peyssonnelia), calcareous green algae (Halimeda), 

small agariciid coral colonies, ellisellid sea whips, Cirrhipathes, gastropods, sponges (Chelotropella), and 

crinoids (Rezak et al., 1983). Deeper portions of the Bank provide habitat for small sponges, solitary 

corals (Oxysmilia), branching corals (Oculina), octocorals (Nidalia), and octocoral fans (Rezak et al., 

1983). A coherent mud is present at the bottom of the bank and small ophiuroids, hermit crabs, galatheid 

crustaceans, swimming scallops, urchins, and flatfishes were observed occupying the sediment (Rezak et 

al., 1983). 

Sackett and Diaphus Banks (Figure 4-11) are closest to the Mississippi River and have less diverse 

communities than other banks as a result of the turbid waters (Rezak et al., 1983). A thin veneer of 

sediment covers much of Sackett Bank and species present include: comatulid crinoids, encrusting 

sponges, urchins, black corals, Atlantic thorny oyster, saucer-shaped agariciids, and coralline algae 

(Rezak et al., 1983). Turbidity tolerant species were present in the Nepheloid Layer including: comatulid 

crinoids, sponges (Neofibularia), white fire worms (Hermodice), asteroid star fish (Narcissia trigonaria), 

black corals (Cirrhipathes), white sponge (Geodea), branching antipatharians (Antipathes), club-shaped 

octocorals (Nidalia occidentalis), sea fans, stony corals (Oxysmilia), paramuriceids (Nidalia), and large 

solitary corals (Rezak et al., 1983). Diaphus Bank has many drowned reef patches and very little live 

cover or active growth due to the turbid waters and sediment veneer (Rezak at al., 1983). 

Alderice Bank (Figure 4-11) is also influenced by the turbidity of the surrounding water. Black 

corals, sponges, and bryozoans are present at the crest. Below the crest, drowned reef structures appear 
Description of the Environment and Impact Analysis 4-143 

with sediment-covered mats of low epifaunal growth (Rezak et al., 1983). The deeper muddy bottom 

houses mobile benthic invertebrates such as the sand dollar (Clypeaster ravenelli) and starfish (Narcissia 

trigonaria). Two basalt spires protrude from this bank and attract schools of roughtongue bass, yellowtail 

reeffish, creole fish, vermillion snapper, grouper, and jacks (Schmahl et al., 2003; Weaver et al., 2006). 

The community is heavily dominated by roughtongue bass (Weaver et al., 2006). 

The crest of McGrail Bank (45 m, 148 ft) (Figure 4-11) is dominated by macroalgae communities 

having about 38 percent cover. Hermatypic corals are common on the crest with a limited area of up to 

32 percent coral cover. It is one of the few banks in the northwestern Gulf of Mexico that has reefbuilding corals other than the East and West Flower Garden Banks (Schmahl et al., 2003). The bank 

exhibits a Stephanocoenia-Millepora Zone and some relatively high coral coverage compared to other 

banks in the area. Corals observed on this bank include: Stephanocoenia intersepta, Millepora alcicornis, 

Diploria strigosa, Montastraea cavernosa, Colpophyllia natans, Agaricia lamarcki, and Agaricia undata

(Schmahl et al., 2003; Schmahl and Hickerson, 2006). Stephanocoenia intersepta is the dominant coral in 

this zone. Fleshy green, brown, and red algae species including: Dictyota pulchella, Lobophora 

variegate, Peyssonnelia inamoena, Codium isthmocladum, Codium interextum, Anadtomene lacerate, and 

Caulerpa racemosa are abundant (Schmahl and Hickerson, 2006). Planktivorous fish such as creole fish, 

threadnose bass, yellow goatfish, sunshinefish, school bass, bicolor damselfish, and blue chromis 

dominated the fish community (Schmahl and Hickerson, 2006; Weaver et al., 2006). Deeper regions of 

the bank exhibit deep water corals such as antipatharians, solitary corals, and branching corals (Oculina

and Madrepora) (Schmahl and Hickerson, 2006). McGrail Bank has also experienced mechanical 

disturbance and damage from fishing and anchoring and marine debris has been found at the bank 

(Schmahl and Hickerson, 2006). 

Bright Bank (Figure 4-11) is located in deep water with its highest peak at 33 m (108 ft) below the 

sea surface (Robbart et al., 2009). The benthic community is dominated by a very high live cover of 

about 86 percent, with brown, green, and turf algae as the dominant groups. Coral cover is about 

8 percent. Bright Bank exhibits a Stephanocoenia-Millepora Zone with sponges and scleractinian corals 

(Montastraea cavernosa, Stephanocoenia intersepta, and Diploria strigosa) (Robbart et al., 2009; 

Schmahl and Hickerson, 2006). A mud volcano, drowned reef formations, and hydrocarbon seeps have 

also been identified on this bank (Schmahl et al., 2003). Salvage activity searching for a historic 

shipwreck destroyed some coral heads at this bank in the 1980s; excavation activity may have taken place 

as recently as 2001 (Schmahl and Hickerson, 2006). 

It has been suggested that Phleger Bank be considered a sensitive offshore topographic feature. 

Phleger Bank (Figure 4-11) crests at 122 m (400 ft), deeper than the lower limit of the No Activity Zones 

(85 m (279 ft) [100 m (328 ft) in the case of the Flower Gardens]). The depth of the bank precludes the 

establishment of the Antipatharian Zone so that even though the bank is in clear water, the biota is typical 

of the Nepheloid Zone (Rezak et al., 1983). The bank appears to be predominantly covered with sand, 

with scattered rock outcrops of approximately 1-2 m (3-7 ft) in diameter and 1 m (3 ft) in height (CSA, 

1980). The sand substrate is devoid of sessile benthic organisms, although the rock outcrops support a 

number of epifaunal species such as cup-shaped and encrusting sponges, octocorals, and crinoids. 

Roughtongue bass were observed in video surveys to be the dominant fish species on this bank (CSA, 

1980). 

Midshelf Banks 

Two midshelf banks in the CPA contain the Millepora-Sponge Zone: Sonnier and Fishnet Banks 

(Figure 4-11). These banks are associated with underlying salt diapirs and rise from depths of 80 m or 

less. The dominant species on these banks are hydrozoan fire corals (Millepora) and sponges (Rezak et 

al., 1983). 

Sonnier Bank (Figure 4-11), which consists of eight peaks and banks, and has a crest at 

approximately 20 m, is encrusted with fire coral (Millepora alcicornis) and sponges (Neofibularia 

nolitangere and Ircina). With depth, fire coral coverage is reduced and encrusting sponge coverage is 

increased (Weaver et al., 2006). A unique biological assemblage occurs at each of the peaks, which is 

influenced by the depths of the peak and the nepheloid layer (Weaver et al., 2006). Hermatypic 

anthozoan corals (Stephanocoenia michelini) which tolerate low light levels and moderate turbidity were 

reported between 36 and 41 m (Rezak et al., 1983). Planktivorous fish dominate this bank, with the most 
4-144 Central Planning Area Supplemental EIS 

abundant species being yellowtail reeffish, creole fish, brown chromis, sunshine fish, and bluehead 

(Weaver et al., 2006). Angelfish, butterflyfish, damselfish, bluehead, hogfish, rock hind, grouper, 

Vermilion snapper, and red snapper also utilize this bank (Rezak et al., 1983). The crests of the bank 

were dominated by creole fish, brown chromis, bluehead, and creole wrasse and the deeper portions of the 

reef were dominated by tomtate, red snapper, greater amberjack, and grey triggerfish (Weaver et al., 

2006). Benthic organisms occupying the turbid soft-bottom sediment at the base of the Bank include: 

antipatharians (Cirrhipathes and Antipathes), comatulid crinoids, sponge (Ircinia campana), hovering 

goby (Ioglossus calliurus), blue goby (Ptereleotris calliurus), tattler (Seranus phoebe) and large infaunal 

and mobile benthic species (Rezak et al., 1983; Weaver et al., 2006). 

Recent Invasive Species Concerns 

Two invasive species have been reported in the Gulf of Mexico: the orange cup coral (Tubastraea 

coccinea) and the lionfish (Pterois volitans/miles). Invasive species are organisms that are not native to 

the local environment and have the potential to outcompete native species. Tubastraea coccinea, which is 

reported on many oil and gas platforms in the northern Gulf of Mexico, has been reported at both Geyer 

and Sonnier Banks (Hickerson et al., 2008; Fenner and Banks, 2004; Sammarco et al., 2004). Over 100 

colonies were reported at Geyer Bank (Hickerson et al., 2008). The lionfish has been reported off the 

coasts of Florida, Alabama, and Louisiana in 2010 (USDOI, GS, 2010b). Reports of this species began in 

2006 in Florida, but the species was confirmed in the northern Gulf of Mexico in 2010 (Schofield, 2009; 

USDOI, GS, 2010b). It has also recently been reported in the Southern Gulf of Mexico (Aguilar-Perera 

and Tuz-Sulub, 2010). Specific sitings were noted at Sonnier Bank and several oil and gas platforms in 

the CPA (USDOI, GS, 2010b). 

Proposed Candidates for Threatened and Endangered Species 

Elkhorn coral (Acropora palmata), which was listed as “threatened” in 2006 and is protected under 

the ESA, has been documented in the WPA at the East and West Flower Garden Banks. In 2009, a 

petition was submitted to NOAA Fisheries by the Center for Biological Diversity to list 82 additional 

species of coral under the ESA (USDOC, NOAA, 2010h). Those 82 “candidate species” are currently 

under review by NOAA Fisheries. Some of the “candidate species” are found in the Gulf of Mexico, 

including Montastraea annularis, Montastraea faveolata, Montastraea franksi. Once NOAA Fisheries 

has reviewed the candidate species, a decision would be made as whether each species warrants listing 

under the ESA or not. If these species are listed, they would receive protection under the ESA.

Hurricane Impacts on CPA Banks 

Severe hurricanes can cause physical damage to reef structure and organisms. On September 23, 

2005, Hurricane Rita passed over the northwestern Gulf of Mexico, affecting at least 18 topographic 

features. The BOEMRE has conducted studies of select topographic features since Hurricane Rita. An 

Agency-funded study, Post-Hurricane Assessment of Sensitive Habitats of the Flower Garden Banks 

Vicinity (Robbart et al., 2009), investigated hurricane effects at Sonnier, McGrail, Geyer, and Bright 

Banks. Preliminary results suggest little hurricane damage to McGrail, Geyer, and Bright Banks but 

severe damage at Sonnier Bank (Robbart et al., 2009). The impact assessment was conducted 20 months 

after the hurricane, and McGrail, Geyer, and Bright Banks were primarily dominated by algae and 

sponges, so it is difficult to determine if there was no damage initially or if the banks have shown 

recovery. 

Speculation is that Sonnier Bank was more affected by Hurricane Rita because of its shallower depth 

and position on the east side of the storm track. Live cover was reduced at this bank and the 

disappearance of the sponge colonies, Xestospongia muta, was notable (Robbart et al., 2009). The 

community structure had visibly changed from pre-Rita (2004) studies at this bank (Kraus et al., 2006; 

Kraus et al., 2007). In 2006, the habitat was dominated by algae, indicating an alteration in habitat after 

Hurricane Rita (Kraus et al., 2007). The algal cover, however, was the beginning of recovery of the 

storm-impacted areas, which was farther colonized with sponges (Robbart et al., 2009). Fish community 

shifts were also observed on Sonnier Banks after Hurricane Rita as opposed to before the storm, but clear 

links have yet to be made to the storm (Kraus et al., 2007). 
Description of the Environment and Impact Analysis 4-145 

This new information illustrates the potential effects of natural events, especially the cumulative 

impacts of hurricanes. Some change has been detected in habitats affected by Hurricane Rita, mostly the 

degradation of the reef community at Sonnier Bank. Other banks either had no substantive damage or are 

recovering well. 

Baseline Conditions Following the Deepwater Horizon Event 

The following sections contain all new data since the Multisale EIS and the 2009-2012 Supplemental 

EIS. Extensive literature, Internet, and database searches have been conducted for results of scientific 

data at topographic features following the DWH event. Although many research cruises have occurred, 

very few reports containing data have been released as of the preparation of this Supplemental EIS. 

Descriptions of studies in progress are discussed and any results indicated are included. 

It is unlikely that the topographic features of the CPA have been impacted by the DWH event because 

of their distance from the oil spill and their position on the continental shelf. The nearest protected 

topographic feature is Sackett Bank, which is 116 km (72 mi) from the spill site. Beyond that, the next 

nearest feature is Diaphus Bank, approximately 240 km (150 mi) away. The bulk of the oil was dispersed 

in deep water off the shelf and was be directed by water currents in deep water. These currents do not 

typically transit from deep water up onto the shelf. Oil dispersed on the sea surface could have traveled 

onto the continental shelf but the distance from the DWH event to protected topographic features makes it 

unlikely to reach the banks. As a result, it is anticipated that there will be no change in existing baseline 

conditions. The benthic communities on the topographic features are anticipated to remain a diverse and 

highly productive habitat that supports a variety of coral, sponge, algal, invertebrate, and fish species. 

If any impacts do occur, they would be a result of low-level or long term exposure to dispersed oil. 

Impacts may include reduced recruitment success, reduced growth, and reduced coral cover as a result of 

impaired recruitment (Kushmaro et al., 1997; Loya, 1975 and 1976a; Rinkevich and Loya, 1977). It 

would likely be difficult to distinguish the source of any possible low-level impacts because numerous 

natural seeps in the CPA are constantly releasing oil into the water. Possible impacts may be investigated 

in future studies if deemed necessary by the NRDA. 

Studies to Measure the Impact of the Deepwater Horizon Event 

Many studies have been planned to analyze the impact of the DWH event and some have already 

been carried out. However, the long-lasting impacts of this event will take years to determine. As more 

studies are conducted and more data is released, we will have a better understanding of the breadth of the 

effects of the DWH event. The following descriptions outline studies that have been conducted on 

topographic features, most of which have taken place at the Flower Garden Banks which are in the WPA. 

Florida Atlantic University, Harbor Branch Oceanographic Institute has conducted a study entitled 

“Rapid Response to the Deepwater Horizon Oil Spill” exploration of the Florida Shelf Edge. Although 

data have not been published at the time of this Supplemental EIS’s release, the characterization of 

benthic and mid-water habitats was conducted from July 9 to August 7, 2010 (Pomponi, 2010). Mission 

objectives of the exploration included the following: (1) assess benthic and mid-water habitat baseline 

and oil impact (assessments that targeted deepwater and shelf-edge reefs and hard-bottom essential fish 

habitat; (2) document oil and dispersant impacts on benthic and mid-water habitats and marine organisms; 

(3) document location of any encountered submerged oil plumes; and (4) conduct education and outreach 

activities. The survey’s primary focus was on the west Florida shelf. Deepwater sites (>200 m; 656 ft) 

that were studied included Lophelia coral habitat (Viosca Knoll, Mississippi Canyon, and De Soto 

Canyon) and the west Florida shelf lithotherms (500 m; 1,640 ft) (Pomponi, 2010). 

The NOAA R/V Seward Johnson conducted a baseline survey of the water column and seafloor in 

areas of the GOM from which the data will be used to measure changes if oil from the DWH event 

reaches the areas investigated (USDOC, NOAA, 2010g). Submersibles and remotely operated vehicles 

were used to observe baseline conditions of coral reefs and benthic organisms along the deep reef and 

hard-bottom regions of the east, south, and west Florida shelf and slope. The research cruise followed a 

path from the Oculina reefs off southeast Florida, through the Straits of Florida to the Dry Tortugas, north 

through the eastern and northern GOM, and west along the Florida shelf and slope toward Alabama and 

Mississippi (USDOC, NOAA, 2010g). 
4-146 Central Planning Area Supplemental EIS 

The limited data currently available on the impacts of the DWH event make it difficult to definitively 

say if any impacts have occurred or may occur to the topographic features in the CPA. Once more data 

are released, we will have a better understanding of the measured impacts and possible long-term effects 

of the DWH event. The implementation of the proposed Topographic Features Stipulation, however, 

would serve to protect sensitive habitat from accidental impacts from oil and gas production, such as oil 

spills, by distancing production from the protected habitat. Details of how the proposed Topographic 

Features Stipulation protects reefs and banks in the Gulf of Mexico from routine and accidental impacts 

of petroleum production are discussed below. 

4.1.1.7.2. Impacts of Routine Events 

The vast majority of the Gulf of Mexico seabed is comprised of soft sediments. Topographic features 

formed on hard-bottom substrate are interspersed along the continental shelf above the soft sediment. 

These topographic features, which sustain sensitive offshore habitats in the CPA, are listed and described 

in Chapter 4.1.1.7.1. 

The potential impact-producing factors on topographic features of the CPA are anchoring, 

infrastructure emplacement, drilling-effluent and produced-water discharges, and infrastructure removal. 

Impacts from accidental events such as oil spills and blowouts are discussed in Chapter 4.1.1.7.3. These 

disturbances have the potential to disrupt and alter the environmental, commercial, recreational, and 

aesthetic values of topographic features in the CPA. 

A Topographic Features Stipulation similar to the one described in Chapter 2.3.1.3.1 has been 

included in appropriate leases since 1973 and may, at the option of the Secretary, be made a part of 

appropriate leases resulting from this proposed action. The impact analysis of routine activities 

associated with the CPA proposed action presented here includes the proposed Topographic Features 

Stipulation. As noted in Chapter 2.3.1.3.1, the proposed stipulation establishes a No Activity Zone in 

which no bottom-disturbing activities would be allowed, and areas around the No Activity Zones (in most 

cases) within which shunting of drill cuttings and drilling fluids to near the bottom would be required. 

Construction Impacts on Topographic Features 

The anchoring of pipeline lay barges, drilling rigs, or service vessels, as well as the emplacement of 

structures (e.g., pipelines, drilling rigs, or production platforms), results in mechanical disturbances of the 

benthic environment. Anchor damage has been shown to be a large threat to the biota of the offshore 

banks in the Gulf (Rezak and Bright, 1979; Rezak et al., 1985; Gittings et al., 1992a; Hudson et al., 1982). 

Anchors may break, fragment, or overturn corals and the anchor chain may drag across and catch on coral 

(Dinsdale and Harriott, 2004). Coral colonies may experience abrasion of tissue and skeletons, death to 

portions of a colony, fragmentation, or removal from substrate as a result of anchor damage (Dinsdale and 

Harriott, 2004). Branching species tend to experience fragmentation while massive species incur surface 

damage (Marshall, 2000). Anchor damage may result in community alteration through reduced coral 

cover, which indirectly promotes an increase in algal cover, complete coral removal, loss of sensitive 

species, reduction in colony size, and a reduction in soft coral cover in heavily damaged areas (Dinsdale 

and Harriott, 2004). Damage as a result of anchoring in a coral community may take 10 or more years 

from which to recover, depending on the extent of the damage (Fucik et al., 1984; Rogers and Garrison, 

2001). Such anchoring damage, however, would be prevented within any given No Activity Zone by the 

observation of the proposed Topographic Features Stipulation, which does not allow bottom-disturbing 

activity. 

Infrastructure emplacement and pipeline emplacement could result in suspended sediment plumes and 

sediment deposition on the seafloor. Considering the relatively elevated amounts of drilling muds and 

cuttings discharged per well (approximately 2,000 metric tons [2,205 tons] for exploratory wells, i.e., 900 

metric tons [992 tons] of drilling fluid and 1,100 metric tons [1,213 tons] of cuttings) and slightly lower 

discharges for development wells) (Neff, 2005), potential impacts on biological resources of topographic 

features should be expressly considered if drill sites occur in blocks directly adjacent to No Activity Zone 

boundaries. Potential impacts could be incurred through increased water-column turbidity, the 

smothering of sessile benthic invertebrates, and local accumulations of contaminants. 

However, the proposed Topographic Features Stipulation requires all bottom-disturbing activity to be 

at least 152 m (500 ft) away from the boundaries of No Activity Zones. The proposed Topographic 
Description of the Environment and Impact Analysis 4-147 

Features Stipulation limits impact through the No Activity Zone and shunting restrictions imposed within 

the 1-Mile Zone, 3-Mile Zone, 4-Mile Zone, and 1,000-Meter Zone. This would prevent well drilling 

activities from occurring in the No Activity Zone and preclude most resuspended sediments from 

reaching the biota of the banks. Also, USEPA’s NPDES permit sets special restrictions on discharge 

rates for muds and cuttings adjacent to topographic features bound by a No Activity Zone. Chapters 

4.1.1.4.1 and 4.2.1.1.2.2 of the Multisale EIS detail the NPDES permit’s general restrictions and the 

impacts of drilling muds and cuttings on marine water quality and seafloor sediments. Due to the 

Topographic Features Stipulation and USEPA discharge regulations, turbidity and smothering impacts of 

sessile invertebrates on topographic features caused by drilling muds and cuttings are unlikely. 

The proposed Topographic Features Stipulation would protect topographic features by physical 

distance from drilling activities. Drilling fluid plumes are rapidly dispersed on the OCS where 

approximately 90 percent of the material discharged in drilling a well (cuttings and drilling fluid) settles 

rapidly to the seafloor, while 10 percent forms a plume of fine mud that drifts in the water column (Neff, 

2005). The composition of muds is strictly regulated, and discharges of cuttings/muds are tested to ensure 

that toxicity levels are below the limits allowed by NPDES permits (USEPA, 2004a, 2007d, and 2009a). 

Although drilling mud plumes may be visible 1 km (0.6 mi) from the discharge, rapid dilution of drilling 

mud plumes was reported within 6 m (20 ft) from the release point (Shinn et al., 1980; Hudson et al., 

1982). Drilling muds and cuttings may be diluted 100 times at 10 m (33 ft) from the discharge and 1,000 

times at 100 m (328 ft) from the discharge (Neff, 2005). Dilution continues with distance from the 

discharge point, and at 96 m (315 ft) from the release point, the plume was measured only a few 

milligrams/liter above background suspended sediment concentrations (Shinn et al., 1980). Suspended 

sediment concentrations at 6 m (20 ft) from the discharge were often less than those produced during 

storms or from boat wakes (Shinn et al., 1980). 

It is not anticipated that muds drifting in the water column would settle on topographic features. The 

mud particles are extremely fine and would not be able to settle in the high-energy environments 

surrounding topographic features (Shinn et al., 1980; Hudson and Robbin, 1980). Any mud that may 

reach coral can be removed by the coral using tentacles and mucus secretion, and physically removed by 

currents that can shed the mucus-trapped particles from the coral (Shinn et al., 1980; Hudson and Robbin, 

1980). Considering that drilling is not allowed within 152 m (500 ft) of a No Activity Zone, that shunting 

to within 10 m (33 ft) of the bottom is required surrounding the No Activity Zone, and that field 

measurements of suspended solids far below concentrations that cause coral mortality corals 96 m (315 ft) 

from the discharge point (Shinn et al., 1980), corals should be distanced enough from the effects from 

drilling turbidity. 

Due to the proposed Topographic Features Stipulation, impacts measured as a result of drilling 

operations would be minimal in comparison to impacts without the proposed Topographic Features 

Stipulation. Wells drilled in lease blocks containing topographic features would be required to shunt 

cuttings to within 10 m (33 ft) of the seafloor. Bottom shunting would protect the organisms on the 

topographic features because it results in localized deposition of cuttings at a greater depth than the 

biological activity of the topographic features (Neff, 2005). Therefore, the deposited material is not 

anticipated to reach the benthic organisms on the reef. 

Long-Term and Operational Impacts on Topographic Features 

Both distance from drilling operations and shunting of cuttings to the seafloor are anticipated to 

reduce exposure pathways of drilling activities to benthic organisms on topographic features, eliminating 

long-term operational impacts, such as exposure to turbidity and sedimentation or associated 

contaminants. 

Produced waters are discharged at the water surface throughout the lifetime of the production 

platform and may contain hydrocarbons, trace metals, elemental sulfur, and radionuclides (Kendall and 

Rainey, 1991). Heavy metals enriched in the produced waters include cadmium, lead, iron, and barium 

(Trefry et al., 1995). Produced waters may impact both organisms attached to the production platform 

and benthic organisms in the sediment beneath the platform. A detailed description of the impacts of 

produced waters on water quality and seafloor sediments is presented in Chapter 4.2.1.1.2 of the Multisale 

EIS. 
4-148 Central Planning Area Supplemental EIS 

Produced waters are rapidly diluted and impacts are generally only observed within proximity of the 

discharge point (Gittings et al., 1992a). Past evaluation of the bioaccumulation of offshore, producedwater discharges conducted by the Offshore Operators Committee (Ray, 1998) assessed that metals 

discharged in produced water would, at worst, affect living organisms found in the immediate vicinity of 

the discharge, particularly those attached to the submerged portion of platforms. Possibly toxic 

concentrations of produced water were reported 20 m (66 ft) from the discharge in both the sediment and 

the water column where elevated levels of hydrocarbons, lead, and barium occurred, but no impacts to 

marine organisms or sediment contamination were reported beyond 100 m (328 ft) of the discharge (Neff 

and Sauer, 1991; Trefry et al., 1995). A study conducted on two species of mollusk and five species of 

fish (Ray, 1998) found that naturally occurring radioactive material in produced water was not found to 

bioaccumulate in marine animals. Because high-molecular PAH’s are usually in such dilute 

concentrations in produced water, they pose little threat to marine organisms and their constituents, and 

they were not anticipated to biomagnify in marine food webs. Monocyclic hydrocarbons and other 

miscellaneous organic chemicals are known to be moderately toxic, but they do not bioaccumulate to high 

concentrations in marine organisms and are not known to pose a risk to their consumers (Ray, 1998). 

Produced waters should not impact to the biota of topographic features. The greatest impacts are 

reported adjacent to the discharge and substantially reduced less than 100 m (328 ft) from the discharge, 

which is less than the 152-m (500-ft) buffer around the No Activity Zone that surrounds topographic 

features. Also, USEPA’s general NPDES permit restrictions on the discharge of produced water would 

help to limit the impacts on biological resources of topographic features. 

Structure-Removal Impacts 

The impacts of structure removal on soft-bottom benthic communities can include turbidity, sediment 

deposition, explosive shock-wave impacts, and loss of habitat. Both explosive and nonexplosive removal 

operations would disturb the seafloor by generating considerable turbidity. Suspended sediment may 

evoke physiological impacts in benthic organisms, including changes in respiration rate, abrasion and 

puncturing of structures, reduced feeding, reduced water filtration rates, smothering, delayed or reduced 

hatching of eggs, reduced larval growth or development, abnormal larval development, or reduced 

response to physical stimulus (Anchor Environmental CA, L.P., 2003) and reduced photosynthesis 

(Rogers, 1990). Long-term exposures to turbidity have even resulted in significantly reduced skeletal 

extension rates in the scleractinian coral Montastraea annularis (Torres, 2001). The higher the 

concentration of suspended sediment in the water column and the longer the sediment remains suspended, 

the greater the impact. 

Sediment deposition may smother benthic organisms, decreasing gas exchange, increasing exposure 

to anaerobic sediment, reducing light intensity, and causing physical abrasion (Wilber et al., 2005). 

Corals may experience reduced coverage, changes in species diversity and dominance patterns, alterations 

in growth rates and forms, decreased calcification, decreased photosynthesis, increased respiration, 

increased production in mucus, loss of zooxanthellae, lesions, reduced recruitment, and mortality (Torres 

et al., 2001; Telesnicki and Goldberg, 1995). Coral larvae settlement may be inhibited in areas where 

sediment has covered available substrate (Rogers, 1990; Goh and Lee, 2008). 

Corals have some ability to rid themselves of sediment through mucus production and ciliary action 

(Marszalek, 1981; Bak and Elgershuizen, 1976; Telesnicki and Goldberg, 1995). Scleractinian corals are 

tolerant of short-term sediment exposure and burial, but longer exposures may result in loss of 

zooxanthellae, polyp swelling, increased mucus production, reduced coral growth, and reduced reef 

development (Marszalek, 1981; Rice and Hunter, 1992). Bleached tissue as a result of sediment exposure 

has been reported to recover in approximately a month (Wesseling et al., 1999). 

Octocorals and gorgonians are more tolerant of sediment deposition than scleractinian corals, as they 

grow erect and are flexible, reducing sediment accumulation and allowing easy removal (Marszalek, 

1981; Torres et al., 2001; Gittings et al., 1992b). Branching forms of scleractinian corals also tend to be 

more tolerant of sediment deposition than massive and encrusting forms (Roy and Smith, 1971). Some of 

the more sediment-tolerant scleractinian species in the Gulf of Mexico include Montastraea cavernosa, 

Siderastrea siderea, Siderastrea radians, and Diploria strigosa (Torres et al., 2001; Acevedo et al., 1989; 

Loya, 1976b). 
Description of the Environment and Impact Analysis 4-149 

The shock waves produced by the explosive structure removals may also harm benthic biota. 

However, corals and other sessile invertebrates have a high resistance to shock. O’Keeffe and Young 

(1984) described the impacts of underwater explosions on various forms of sea life using, for the most 

part, open-water explosions much larger than those used in typical structure-removal operations. They 

found that sessile benthic organisms, such as barnacles and oysters, and many motile forms of life, such 

as shrimp and crabs (that do not possess swim bladders), were remarkably resistant to shock waves 

generated by underwater explosions. Oysters located 8 m (26 ft) away from the detonation of 135- 

kilogram (kg) (298-pound [lb]) charges in open water incurred a 5-percent mortality rate. Crabs distanced 

8 m (26 ft) away from the explosion of 14-kg (31-lb) charges in open water had a 90-percent mortality 

rate. Few crabs died when the charges were detonated 46 m (151 ft) away. O’Keeffe and Young (1984) 

also described lack of damage to other invertebrates such as sea anemones, polychaete worms, isopods, 

and amphipods. 

Charges used in OCS structure removals are typically much smaller than some of those cited by 

O’Keeffe and Young. The Structure-Removal Operations on the Gulf of Mexico Outer Continental Shelf: 

Programmatic Environmental Assessment (USDOI, MMS, 2005) predicts low impacts on the sensitive 

offshore habitats from platform removal precisely because of the effectiveness of the proposed stipulation 

in preventing platform emplacement in the most sensitive areas of the topographic features of the GOM. 

Impacts on the biotic communities, other than those on or directly associated with the platform, would be 

limited by the relatively small size of individual charges (normally 50 lb [27 kg] or less per well piling 

and per conductor jacket) and because BOEMRE regulations require charges to be detonated 5 m (15 ft) 

below the mudline and at least 0.9 seconds apart (to prevent shock waves from becoming additive) 

(USDOI, MMS, 2005). Also, because the proposed Topographic Features Stipulation precludes platform 

installation within 152 m (500 ft) of a No Activity Zone, adverse effects to topographic features by 

removal explosives should be prevented. The shock wave is significantly attenuated when explosives are 

buried, as opposed to detonation in the water column (Baxter et al., 1982; Wright and Hopky, 1998). 

Removal of infrastructure would result in the removal of the hard substrate and encrusting 

community, with overall reduction in species diversity (both epifaunal encrusting organisms and the fish 

and large invertebrates that fed on them) with the removal of the structure (Schroeder and Love, 2004). 

The removal of a platform may extract a viable habitat utilized during cross pollination with a 

topographic feature and supported viable finfish communities. The epifaunal organisms attached to the 

platform that are physically removed would die once the platform is removed and disposed of. However, 

the seafloor habitat would return to the original soft-bottom substrate that existed before the well was 

drilled. 

Some structures may be converted to artificial reefs. If the rig stays in place, the hard substrate and 

encrusting communities would remain part of the benthic habitat. The diversity of the community would 

not change, and associated finfish species would continue to graze on the encrusting organisms. The 

community would remain an active artificial reef. However, the plugging of wells and other reef in place 

decommissioning activities would still impact benthic communities as discussed above. 

Proposed Action Analysis 

Of 16 topographic features (shelf-edge banks, mid-shelf banks, and low-relief banks) in the CPA, 15 

are found in waters less than 200 m (656 ft) deep. Geyer Bank is located at a depth of 190-210 m 

(623-689 ft). They represent a small fraction of the CPA. As noted above, the proposed Topographic 

Features Stipulation could prevent most of the potential impacts from oil and gas operations on the biota 

of topographic features, including direct contact during pipeline, rig, and platform emplacements; 

anchoring activities, and removals. Yet, operations outside the No Activity Zone could still affect 

topographic features through drilling effluent discharges and produced-water discharges, blowouts, and 

oil spills. Potential impacts from oil spills and blowouts are discussed in Chapter 4.1.1.7.3.

For the CPA proposed action, 17-23 exploration/and 62-85 development wells are projected for 

offshore Subarea W0-60. There are an additional 9-14 exploration/delineation wells and 23-33 

development wells proposed between 60 and 200 m (197 and 656 ft) (the boundary of the continental 

shelf) (Table 3-2). With the inclusion of the proposed Topographic Features Stipulation, no discharges 

would take place within the No Activity Zone. Most drilling discharges would be shunted to within 10 m 

(33 ft) of the seafloor either within the 1,000-Meter Zone, 1-Mile Zone, 3-Mile Zone, or 4-Mile Zone 
4-150 Central Planning Area Supplemental EIS 

(depending on the topographic feature) around the No Activity Zone (see Chapter 2.3.1.3.1 for 

specifics). This procedure would essentially prevent the threat of large amounts of drilling effluents 

reaching the biota of a given topographic feature. Also, most studies indicate that biological impacts and 

sediment contamination occur within 100 m (328 ft) of production platforms (Montagna and Harper, 

1996; Kennicutt at al., 1996; Neff and Sauer, 1991; Trefry et al., 1995). If drilling effluents or produced 

waters do reach any topographic features, concentrations of these anthropogenic influences should be 

diluted substantially from their initial concentration, and effects would be minimal. 

For the CPA proposed action, 20-25 production structures are projected in offshore Subarea W0-60 

and 2-3 production structures are predicted for Subarea W60-200. From 14 to 17 structure removals 

using explosives are projected for the Subarea W0-60 and 2 are projected in Subarea W60-200. The 

explosive removal of platforms should not impact the biota of topographic features because the proposed 

Topographic Features Stipulation prohibits the emplacement of platforms within 152 m (500 ft) of the No 

Activity Zone boundaries. This emplacement would prevent shock-wave impacts and resuspended 

sediments from reaching the biota of topographic features. Site clearance operations following a structure 

removal typically employ trawling the sea bottom within a radius of up to 400 m (1,320 ft) to retrieve 

anthropogenic debris. In areas near sensitive habitats, operators may be required to use sonar to detect 

debris and scuba divers to retrieve it. This precaution is exercised by BOEMRE as needed in the activity 

permitting process. 

Summary and Conclusion 

The proposed Topographic Features Stipulation would prevent most of the potential impacts on 

topographic features from bottom-disturbing activities (structure removal and emplacement) and 

operational discharges associated with the CPA proposed action. Because of the No Activity Zone, 

permit restrictions, and the high-energy environment associated with topographic features, if any 

contaminants reach topographic features they would be diluted from their original concentration and 

impacts that do occur would be minimal. 

Effects of the Proposed Action without the Proposed Stipulation 

The topographic features and associated coral reef biota of the CPA could be adversely impacted by 

oil and gas activities resulting from the proposed action in the absence of the proposed Topographic 

Features Stipulation. This would be particularly true should operations occur directly on top of or in the 

immediate vicinity of otherwise protected CPA topographic features. 

The No Activity Zone of the topographic features would be most susceptible to adverse impacts if oil 

and gas activities are unrestricted without the proposed Topographic Feature Stipulation. These 

impacting activities could include vessel anchoring and infrastructure emplacement; discharges of drilling 

muds, cuttings, and produced water; and ultimately the explosive removal of structures. All the abovelisted activities have the potential to considerably alter the diversity, cover, and long-term viability of the 

reef biota found within the No Activity Zone. In most cases, recovery from disturbances would take 10 

years or more (Fucik et al., 1984; Rogers and Garrison, 2001). Long-lasting and possibly irreversible 

change would be caused mainly by vessel anchoring and structure emplacement (pipelines, drill rigs, and 

platforms). Such activities would physically and mechanically alter benthic substrates and their 

associated biota. Operational discharges would cause substantial and prolonged turbidity and 

sedimentation, possibly impeding the well-being and permanence of the biota and interfering with larval 

settlement, resulting in the decrease of live benthic cover. Finally, the unrestricted use of explosives to 

remove platforms installed in the vicinity of or on the topographic features could cause turbidity, 

sedimentation, and shock-wave impacts that would affect reef biota. 

The shunting of cuttings and fluids, which would be required by the proposed Topographic Features 

Stipulation, is intended to limit the smothering and crushing of sensitive benthic organisms caused by 

depositing foreign substances onto the topographic features. The impacts from unshunted exploration and 

development discharges of drill cuttings and drilling fluids within the 1,000-Meter Zone, 1-Mile Zone, 

and 4-Mile Zone would definitely impact the biota of topographic features. Specifically, the discharged 

materials would cause prolonged events of turbidity and sedimentation, which could have long-term 

deleterious effects on local primary production, predation, and consumption by benthic and pelagic 

organisms, biological diversity, and benthic live cover. The unrestricted discharge of drilling cuttings and 
Description of the Environment and Impact Analysis 4-151 

fluids during development operations would be a further source of impact to the sensitive biological 

resources of the topographic features. Therefore, in the absence of the proposed Topographic Features 

Stipulation, the proposed action could cause long-term (10 years or more) adverse impacts to the biota of 

the topographic features (Fucik et al., 1984; Rogers and Garrison, 2001). 

4.1.1.7.3. Impacts of Accidental Events 

The topographic features of the CPA that sustain sensitive offshore habitats are listed and described in 

Chapter 4.1.1.6.1. See Chapter 2.4.1.3.1 for a complete description and discussion of the proposed 

Topographic Features Stipulation. 

Disturbances resulting from the CPA proposed action, including oil spills and blowouts, have the 

potential to disrupt and alter the environmental, commercial, recreational, and aesthetic values of 

topographic features of the CPA. 

A search was conducted for additional new information published since completion of the Multisale 

EIS and the 2009-2012 Supplemental EIS. Various Internet sources and journal articles were examined to 

discover any recent information regarding impacts of oil on benthic organisms. Sources investigated 

include literature published in journals and websites (NOAA, USEPA, and coastal universities). The 

following information is a summary of the accidental impacts incorporated from the Multisale EIS and 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

Possible Modes of Exposure 

Oil released to the environment as a result of an accidental event may impact topographic features in 

several ways. Oil may be physically mixed into the water column from the sea surface, be injected below 

the sea surface and travel with currents, be dispersed in the water column, or be adsorbed to sediment 

particles and sink to the seafloor. These scenarios and their possible impacts are discussed in the 

following sections. 

An oil spill that occurs at the sea surface would result in a majority of the oil remaining at the sea 

surface. Lighter compounds in the oil may evaporate, and some components of the oil may dissolve in 

the seawater. Evaporation allows the removal of the most toxic components of the oil, while dissolution 

may allow bioavailability of hydrocarbons to marine organisms for a brief period of time (Lewis and 

Aurand, 1997). Remnants of the oil may then emulsify with water or adsorb to sediment particles and fall 

to the seafloor. 

A spill that occurs below the sea surface (i.e., at the rig, along the riser between the seafloor and sea 

surface, or through leak paths on the BOP/wellhead) would result in most of the released oil rising to the 

sea surface. All known reserves in the Gulf of Mexico have specific gravity characteristics that would 

preclude oil from sinking immediately after release at a blowout site. As discussed in Chapter 4.3.1.5.4 of 

the Multisale EIS, oil discharges that occur at the seafloor from a pipeline or loss of well control would 

rise in the water column, surfacing almost directly over the source location, thus not impacting sensitive 

deepwater communities. If the leak is deep in the water column and the oil is ejected under pressure, oil 

droplets may become entrained deep in the water column (Boehm and Fiest, 1982). The upward 

movement of the oil may be reduced if methane in the oil is dissolved at the high underwater pressures, 

reducing the oil’s buoyancy (Adcroft et al., 2010). The large oil droplets would rise to the sea surface, 

but the smaller droplets, formed by vigorous turbulence in the plume or the injection of dispersants, may 

remain neutrally buoyant in the water column, creating a subsurface plume (Adcroft et al., 2010). Oil 

droplets less than 100 μm in diameter may remain in the water column for several months (Joint Analysis 

Group, 2010a). Dispersed oil in the water column begins to biodegrade and may flocculate with 

particulate matter, promoting sinking of the particles. 

Impacts that may occur to benthic communities on topographic features as a result of a spill would 

depend on the type of spill, distance from the spill, relief of the biological feature, and surrounding 

physical characteristics of the environment (e.g., turbidity). The NTL 2009-G39 describes the proposed 

Topographic Features Stipulation, which requires buffers to prevent oil spills in the immediate vicinity of 

a topographic feature or its associated biota. The BOEMRE has created No Activity Zones around 

topographic features in order to protect these habitats from disruption due to oil and gas activities. A No 

Activity Zone is a protective perimeter drawn around each feature that is associated with a specific 
4-152 Central Planning Area Supplemental EIS 

isobath (depth contour) surrounding the feature in which structures, drilling rigs, pipelines, and anchoring 

are not allowed. These No Activity Zones are areas protected by BOEMRE policy. The NTL 2009-G39 

recommends that drilling not occur within 152 m (500 ft) of a No Activity Zone of a topographic feature. 

This additional recommendation is based on essential fish habitat, and construction within the essential 

fish habitat would require project-specific consultation with NOAA. 

Oil released during accidental events may reach topographic features. As described above, most of 

the oil released from a spill would rise to the sea surface and therefore reduce the amount of oil that may 

directly contact benthic communities. Small droplets of oil in the water column could possibly migrate 

into No Activity Zones, attach to suspended particles in the water column, and sink to the seafloor 

(McAuliffe et al., 1975). Topographic features and their benthic communities that are exposed to subsea 

plumes, dispersed oil, or oil adsorbed to sediment particles may demonstrate reduced recruitment success, 

reduced growth, and reduced coral cover as a result of impaired recruitment. These impacts are discussed 

in the following sections. 

Surface Slicks and Physical Mixing 

The potential of surface oil slicks to affect topographic features is limited by its ability to mix into the 

water column. Topographic features are high-relief protrusions above the seafloor on the continental 

shelf; the shallowest peaks rise to within 15 m (49 ft) of the sea surface. The two peaks of the Flower 

Garden Banks are the shallowest and most sensitive features, supporting true coral reefs. Other banks are 

deeper, supporting reef communities but not coral reefs (Chapter 4.1.1.7.1). The depth of the 

topographic features below the sea surface helps protect benthic species from physical oil contact through 

distance below the sea surface. 

Field data collected at the Atlantic entrance to the Panama Canal 2 months after a tanker spill has 

shown that subtidal coral species (i.e., Porites furcata, Porites asteroids, Siderastrea radians, and 

Millepora complanata), all of which are also present in the Gulf of Mexico, did not show measurable 

impacts from the oil spill, presumably because the coral was far enough below the surface oil and the oil 

did not contact the coral (Rützler and Sterrer, 1970). Similar results were reported from a Florida coral 

reef immediately following and 6 months after a tanker discharged oil nearby (Chan, 1977). The lack of 

acute toxicity was again attributed to the fact that the corals were completely submerged at the time of the 

spill and calm conditions prevented the oil from mixing into the water column (Chan, 1977). 

Disturbance of the sea surface by storms can mix surface oil into the water column, but the effects are 

generally limited to the upper 10 m (33 ft). Modeling exercises have indicated that oil may reach a depth 

of 20 m (66 ft). Yet at this depth, the spilled oil would be at concentrations several orders of magnitude 

lower than the amount shown to have an effect on marine organisms (Lange, 1985; McAuliffe et al., 1975 

and 1981a; Tkalich and Chan, 2002). Therefore, depth may contribute to the protection of topographic 

features from physical mixing of surface oil below the sea surface. However, if dispersants are used, they 

would enable oil to mix into the water column and possibly impact organisms on the topographic features. 

Dispersants are discussed later in this section. 

Subsurface Plumes 

A subsurface oil spill or plume has the potential to reach a topographic feature and cause negative 

effects. Such impacts on the biota may have severe and long-lasting consequences, including loss of 

habitat, biodiversity, and live coverage; change in community structure; and failed reproductive success. 

Topographic features are sheltered from petroleum-producing activities through the distance provided 

from No Activity Zone and the NTL 2009-G39 recommendation of the additional 152-m (500-ft) buffer 

beyond the No Activity Zone. The distance allows for several physical and biological changes to occur to 

the oil before it reaches sensitive benthic organisms. Oil would become diluted as it physically mixes 

with the surrounding water, and some evaporation may occur. The longer and farther a subsea plume 

travels in the sea, the more dilute the oil will be (Vandermeulen, 1982; Tkalich and Chan, 2002). 

Microbial degradation of the oil occurs in the water column, reducing toxicity (Hazen et al., 2010; 

McAuliffe et al., 1981b). In addition, oil can adsorb to sediments in the water column and sink to the 

seafloor. The oil will move in the direction of prevailing currents (S.L. Ross Environmental Research 

Ltd., 1997); however, the banks will be physically protected because currents move around the 

topographic features, which may help sweep the subsea oil clear of the banks (Rezak et al., 1978; Rezak 
Description of the Environment and Impact Analysis 4-153 

et al., 1983; McGrail, 1982). Also, subsea oil plumes transported by currents may not travel nearly as far 

as surface oil slicks because some oil droplets may conglomerate and rise or may be blocked by fronts, as 

was observed in the southern Gulf of Mexico during the Ixtoc I spill (Boehm and Fiest, 1982). Should 

any of the oil come in contact with adult sessile biota, effects would be primarily sublethal, as the oil 

would be diluted by physical and biological processes by the time it reaches the banks. Low-level 

exposure impacts may vary from chronic to temporary, or even immeasurable. 

In the event that low concentrations of oil transported in subsea plumes reaches benthic features, coral 

feeding activity may be reduced. Experiments indicated that normal feeding activity of Porites porites

and Madracis asperula were reduced when exposed to 50 ppm oil (Lewis, 1971). Tentacle pulsation of 

an octocoral, Heteroxenia fuscescens, has also been shown to decrease upon oil exposure, although 

recovery of normal pulsation was observed 96 hours after the coral was removed from the oil (Cohen et 

al., 1977). Porites furcata exposed to marine diesel and Bunker C oil reduced feeding and left their 

mouths open for longer than normal periods of time (Reimer, 1975). 

Direct oil contact may result in coral tissue damage. Coral exposed to sublethal concentrations of oil 

for 3 months revealed atrophy of muscle bundles and mucus cells (Peters et al., 1981). Porites furcata

submersed in Bunker C oil for 1 minute resulted in 100 percent tissue death (with a lag time of 114 days) 

(Reimer, 1975). 

Reproductive ability may also be reduced if coral is exposed to oil. A hermatypic coral, Stylophora 

pistillata, and an octocoral, Heteroxenia fuscescens, shed their larvae when exposed to oil (Loya and 

Rinkevich, 1979; Rinkevich and Loya, 1977; Cohen et al., 1977). Neither of these species is present in 

the Gulf of Mexico, but impacts may be similar in Gulf species. Undeveloped larvae exposed to oil in the 

water column have a reduced chance of survival due to predation (Loya and Rinkevich, 1979), which 

would in turn reduce the ability of larval settlement and reef expansion or recovery. A similar expulsion 

of gametes may occur in species that have external fertilization (Loya and Rinkevich, 1979), such as those 

at the Flower Garden Banks in the WPA (Gittings et al., 1992c), which may then reduce gamete 

survivorship due to oil exposure. 

The overall ability of a coral colony to reproduce may be affected by oil exposure. Reefs of 

Siderastrea siderea that were oiled in a spill produced smaller gonads than unoiled reefs, which resulted 

in reproductive stress for the oiled reef (Guzmán and Holst, 1993). Stylophora pistillata reefs exposed to 

oil had fewer breeding colonies, reduced number of ovaries per polyp, and significantly reduced fecundity 

compared with unoiled reefs (Rinkevich and Loya, 1977). Impaired development of reproductive tissue 

has been reported for other reef-building corals exposed to sublethal concentrations of oil as well (Peters 

et al., 1981). Larvae also may not be able to settle on reefs impacted by oil. Field experiments on 

Stylophora pistillata showed reduced settlement rates of larvae on artificial substrates of oiled reefs 

compared with control reefs and lower settlement rates with increasing concentrations of oil in test 

containers (Rinkevich and Loya, 1977). 

Oil exposure is believed to reduce photosynthesis and growth in corals; however, low-level exposures 

have produced counterintuitive and sometimes immeasurable results. Photosynthesis of the zooxanthellae 

in Diploria strigosa exposed to approximately 18-20 ppm crude oil for 8 hours was not measurably 

affected, although other experiments indicate that photosynthesis may be impaired at higher 

concentrations (Cook and Knap, 1983). A longer exposure (24 hours) of 20 mL/L (20 ppt) oil markedly 

reduced photosynthesis in Stylophora pistillata; however, concentrations of 2.5 mL/L (2.5 ppt) oil 

resulted in physiological stress that caused a measurable increase in photosynthesis as compared with 

controls (Rinkevich and Loya, 1983). Other impacts recorded include the degeneration and expulsion of 

photosynthetic zooxanthellae upon coral exposure to oil (Loya and Rinkevich, 1979; Peters et al., 1981). 

Long-term growth changes in Diploria strigosa that was exposed to oil concentrations up to 50 ppm for 

6-24 hours did not show any measurably reduced growth in the following year (Dodge et al., 1984). 

Corals exposed to subsea oil plumes may also incorporate petroleum hydrocarbons into their tissue. 

Records indicate that Siderastrea siderea, Diploria strigosa, Montastraea annularis, and Heteroxenia 

fuscescens have accumulated oil from the water column and have incorporated petroleum hydrocarbons 

into their tissues (Burns and Knap, 1989; Knap et al., 1982; Kennedy et al., 1992; Cohen et al., 1977). 

Hydrocarbon uptake may also modify lipid ratios of coral (Burns and Knap, 1989). If lipid ratios are 

modified, mucus synthesis may be impacted, adversely affecting coral ability to protect itself from oil 

through mucus production (Burns and Knap, 1989). 
4-154 Central Planning Area Supplemental EIS 

Sublethal effects, although often hard to measure, could be long lasting and affect the resilience of 

coral colonies to natural disturbances (e.g., elevated water temperature, extreme low tides, and diseases) 

(Jackson et al., 1989; Loya, 1976a). Continued exposure to oil from resuspended contaminated sediments 

in the area could also impact coral growth and recovery (Guzmán et al., 1994). Any repetitive or longterm oil exposure could inhibit coral larvae’s ability to settle and grow, may damage coral reproductive 

systems, may cause acute toxicity to larvae, and may physically alter the reef interfering with larval 

settlement, all of which would reduce coral recruitment to an impacted area (Kushmaro et al., 1997; Loya, 

1975 and 1976a; Rinkevich and Loya, 1977). Exposure of eggs and larvae to oil in the water column may 

reduce the success of a spawning event (Peters et al., 1997). Sublethal exposure to oil may in fact be 

more detrimental to corals than high concentrations of oil (Cohen et al., 1977), as sublethal concentrations 

are typically more widespread and have a larger overall community effect. Therefore, the sublethal 

effects of oil exposure, even at low concentrations, may have long-lasting effects on the community. 

The NTL 2009-G39 protects topographic features from both routine and accidental impacts that may 

occur during petroleum production; however, recent reports have indicated damage to a deepwater coral 

community that appeared to be impacted by contact with oil resulting from the DWH event; this 

community is far deeper than the reef organisms on the topographic features (USDOI, BOEMRE, 2010i). 

The circumstances of the deepwater coral exposure were not typical because the release of oil was 

1,500 m (4,921 ft) below the sea surface at high pressure, which caused the formation of a subsea plume 

of oil that was treated with dispersant, allowing it to remain at a water depth between 1,100 and 1,300 m 

(3,609 and 4,265 ft) (Joint Analysis Group, 2010a). This 200-m (656-ft) thick subsea plume was in deep 

water and was thought to be bounded by stratified density layers of water, allowing it to remain at depth 

instead of dispersing into the water column and to eventually contact the coral. Such an occurrence 

should not occur on the continental shelf where the topographic features are found because, even though 

stratified waters called the nepheloid layer (a layer of turbid water) are found on the continental shelf, 

studies show that stratified water normally restricts the nepheloid layer to near the seafloor; that is, no 

more than 20 m (66 ft) up into the water column (Bright et al., 1976; Bright and Rezak, 1978). Therefore, 

while stratified layers in deep water may cover 200 m (656 ft) of depth, layers on the shelf would have a 

smaller range and oil trapped in the bottom layer would be restricted to less than 20 m (66 ft) above the 

seafloor. The reef organisms of the topographic features live above the turbid waters and, therefore, they 

could not be contacted by stratified oil later. Also, currents around the topographic features may sweep 

the subsea oil clear of the features, as bottom currents typically travel around topographic highs rather 

than over them (Rezak et al., 1983). 

Dispersed Oil 

Chemically dispersed oil from a surface slick is not anticipated to result in lethal exposures to 

organisms on topographic features. The chemical dispersion of oil may increase the weathering process 

and allow surface oil to penetrate to greater depths than physical mixing would permit, and the dispersed 

oil generally remains below the water’s surface (McAuliffe et al., 1981b; Lewis and Aurand, 1997). 

However, reports on dispersant usage on surface plumes indicate that a majority of the dispersed oil 

remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (6 ft) 

(McAuliffe et al., 1981a). Dispersant usage also reduces the oil’s ability to stick to particles in the water 

column, minimizing oil adsorbed to sediment particles traveling to the seafloor (McAuliffe et al., 1981a; 

Lewis and Aurand, 1997). 

Field experiments designed to test dispersant use on oil spills reported dispersed oil concentrations 

between 1 and 3 ppm, 9 m (26 ft) below the sea surface, approximately 1 hour after treatment with 

dispersant (McAuliffe et al., 1981a and 1981b). Other studies indicated that dispersed oil concentrations 

were <1 ppm, 10 m (33 ft) below the sea surface (Lewis and Aurand, 1997). The above data indicate that 

the mixing depth of dispersed oil is less than the depths of the crests of topographic features (greater than 

15 m [49 ft] below the sea surface), greatly reducing the possibility of exposure to dispersed surface oil. 

Any dispersed surface oil that may reach the benthic communities of topographic features in the Gulf 

of Mexico would be expected to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a). Such 

concentrations would not be life threatening to larval or adult stages, based on experiments conducted 

with coral (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Knap, 1987; Wyers et al., 1986; Cohen et al., 

1977) and observations after oil spills (Jackson et al., 1989; Guzmán et al., 1991). Any dispersed oil in 
Description of the Environment and Impact Analysis 4-155 

the water column that comes in contact with corals, however, may evoke short-term negative responses 

by the organisms, such as reduced feeding and photosynthesis or altered behavior (Wyers et al., 1986; 

Cook and Knap, 1983; Dodge et al., 1984). 

The use of dispersants near or above protected features, such as the Flower Garden Banks, is not 

recommended because dispersants allow floating oil to mix with water. The Flower Garden Banks 

National Marine Sanctuary helped to develop a regional response plan for dispersant use near the 

sanctuary using literature, field observations, and spill risk assessments (Gittings, 2006). Results of the 

investigations led to a NOAA policy revision in 1994 that allowed dispersant use if the Federal On-Scene 

Coordinator deems it appropriate, but the Flower Garden Banks National Marine Sanctuary requests that 

dispersant application be as far as possible from the sanctuary and not occur during seasonal species 

gatherings or spawning. Also, the Sanctuary’s management must be consulted and forwarded incident 

relevant data (Gittings, 2006). The distancing of the dispersant application from the Flower Garden 

Banks National Marine Sanctuary would allow for dilution of the compounds in the surrounding water 

column away from protected habitat. 

Dispersants that are used on oil below the sea surface can travel with currents through the water and 

may contact benthic organisms on the topographic features. If the oil spill occurs near a topographic 

feature, the dispersed oil could be concentrated enough to harm the community. However, the longer the 

oil remains suspended in the water column traveling with currents, the more dispersed it would become. 

Weathering will also be accelerated and biological toxicity reduced (McAuliffe et al., 1981b). Although 

the use of subsea dispersants is a new technique and very little data are available on dispersion rates, it is 

anticipated that any oil that could reach topographic features will be in low concentration based on 

surface slick dilution data (McAuliffe et al., 1981a; Lewis and Aurand, 1997). Currents around the 

topographic features may sweep the subsea oil clear of the features, as bottom currents typically travel 

around topographic highs rather than over them (Rezak et al., 1983). Recent data from studies of the 

DWH event and resulting spill showed that oil treated with dispersant at depth remained at a water depth 

between 1,100 and 1,300 m (3,600 and 4,265 ft) (Joint Analysis Group, 2010a). This subsea plume was 

in deep water rather than on the continental shelf. While the DWH event’s subsea oil plume ranged 

through a 200-m (656-ft) depth range, it was thought to be bounded by stratified density layers of water. 

Stratification is also found on the continental shelf. Studies of the nepheloid layer (a layer of turbid 

water) showed that stratified water normally restricts the nepheloid layer to near the seafloor, no more 

than 20 m (66 ft) up into the water column (Bright et al., 1976; Bright and Rezak, 1978). So, while 

stratified layers in deep water may cover 200 m (656 ft) of depth, layers on the shelf have a smaller range 

and oil trapped in the bottom layer may be restricted to less than 20 m (66 ft) above the seafloor. Unusual 

circumstances, such as mixing resulting from passage of a hurricane, may change this situation somewhat, 

causing subsea oil plumes to mix through the entire water column. However, such mixing would also 

serve to reduce the concentration of toxic components. Therefore, impacts resulting from exposure to 

dispersed oil are anticipated to be sublethal for communities on topographic features. In some cases, less 

diverse communities at the base of topographic features could experience lethal contact with subsea oil 

plumes if the source of the spill is nearby on the seafloor. 

Sublethal impacts that may occur to coral exposed to dispersed oil may include reduced feeding and 

photosynthesis, reduced reproduction and growth, physical tissue damage, and altered behavior. Shortterm, sublethal responses of Diploria strigosa were reported after exposure to dispersed oil at a 

concentration of 20 ppm for 24 hours (Knap et al., 1983; Wyers et al., 1986). Although concentrations in 

this experiment were higher than what is anticipated for dispersed oil at depth, effects included 

mesenterial filament extrusion, extreme tissue contraction, tentacle retraction, localized tissue rupture 

(Wyers et al., 1986), and a decline in tentacle expansion behavior (Knap et al., 1983). Normal behavior 

resumed within 2 hours to 7 days after exposure (Wyers et al., 1986; Knap et al., 1983). This coral, 

however, did not show indications of stress when exposed to 1 ppm and 5 ppm of dispersed oil for 

24 hours (Wyers et al., 1986). Diploria strigosa exposed to dispersed oil (20:1, oil:dispersant) showed an 

85 percent reduction in zooxanthellae photosynthesis after 8 hours of exposure to the mixture (Cook and 

Knap, 1983). However, the response was short-term, as recovery occurred between 5 and 24 hours after 

exposure and return to clean seawater. Investigations 1 year after Diploria strigosa was exposed to 

concentrations of dispersed oil between 1 and 50 ppm for periods between 6 and 24 hours did not reveal 

any impacts to growth (Dodge et al., 1984; Knap et al., 1983). It should be noted, however, that subtle 

growth effects may have occurred but were not measurable (Knap et al., 1983). 
4-156 Central Planning Area Supplemental EIS 

Historical studies indicate that dispersed oil does appear to be more toxic to coral species than oil or 

dispersant alone. The greater toxicity may be a result of an increased number of oil droplets, resulting in 

a greater contact area between the dispersed oil and water (Elgershuizen and De Kruijf, 1976). The 

dispersant results in a higher water-soluble fraction of oil contacting the cell membranes of the coral 

(Elgershuizen and De Kruijf, 1976). The mucus produced by coral, however, can protect an organism 

from oil. Both hard and soft corals have the ability to produce mucus, and mucus production has been 

shown to increase when corals are exposed to crude oil (Mitchell and Chet, 1975; Ducklow and Mitchell, 

1979). Dispersed oil, which has very small oil droplets, does not appear to adhere to coral mucus, and 

larger untreated oil droplets may become trapped by the mucus barrier (Knap, 1987; Wyers et al., 1986). 

However, entrapment of the larger oil droplets may increase long-term exposure to oil if the mucus is not 

shed in a timely manner (Knap, 1987; Bak and Elgershuizen, 1976). 

More recent field studies did not reveal as great an impact of dispersants on corals as were indicated 

in historical toxicity tests (Yender and Michel, 2010). This difference in reported damage probably 

resulted from a more realistic application of dispersants in an open field system and because newer 

dispersants are less toxic than the older ones (Yender and Michel, 2010). Field studies have shown oil to 

be dispersed to the part per billion level minutes to hours after the dispersant application, which is orders 

of magnitude below the reasonable effects threshold of oil in the water column (20 ppm) measured in 

some studies (McAuliffe, 1987; Shigenaka, 2001). 

Although dispersed oil may be more toxic than untreated oil to corals during exposure experiments 

(Shafir et al., 2007; Wyers et al., 1986; Cook and Knap, 1983), untreated oil may remain in the ecosystem 

for long periods of time, while dispersed oil does not (Baca et al., 2005; Ward et al., 2003). Twenty years 

after an experimental oil spill in Panama, oil and impacts from untreated oil were still observed at oil 

treatment sites, but no oil or impacts were observed at dispersed oil or reference sites (Baca et al., 2005). 

Long-term recovery of the coral at the dispersed oil site had already occurred as reported in a 10-year 

monitoring update, and the site was not significantly different from the reference site (Ward et al., 2003). 

The time of year and surrounding ecosystem must be considered when determining if dispersants 

should be used. Dispersant usage may result in reduced or shorter term impacts to coral reefs; however, it 

may increase the impacts to other communities, such as mangroves (Ward et al., 2003). Therefore, 

dispersant usage may be more applicable offshore than in coastal areas where other species may be 

impacted as well. In addition, dispersant use may be restricted in some areas during peak coral spawning 

periods (e.g., August-September for major reef-building species) (Gittings et al., 1992c and 1994) in order 

to limit the impacts of oil pollution on the near-surface portion of the water column. 

Oil Adsorbed to Sediment Particles 

Smaller suspended oil droplets could be carried to the seafloor as a result of oil droplets adhering to 

suspended particles in the water column. Smaller particles have a greater affinity for oil (Lewis and 

Aurand, 1997). Oil may also reach the seafloor through consumption by plankton with excretion 

distributed over the seafloor (ITOPF, 2007). Oiled sediment that settles to the seafloor may affect 

organisms attached to topographic features. It is anticipated that the greatest amount of oil adsorbed to 

sediment particles would occur close to the spill, with lesser concentrations farther from the source. 

Studies after a spill that occurred at the Chevron Main Pass Block 41C Platform in the northern Gulf of 

Mexico revealed that the highest concentrations of oil in the sediment were close to the platform and that 

the oil settled to the seafloor within 5-10 mi (8-16 km) of the spill site (McAuliffe et al., 1975). 

Therefore, if the spill occurs close to a topographic feature, the underlying benthic communities may 

become smothered by the particles and exposed to toxic hydrocarbons. However, because of the 

implementation of the No Activity Zone and surrounding 152-m (500-ft) buffer zone, topographic 

features should be distanced from the heaviest oiled sedimentation effects. Oiled sediment depositional 

impacts, however, are possible and may smother nearby benthic species. 

Some oiled particles may become widely dispersed as they travel with currents while they settle out 

of suspension. Settling rates are determined by size and weight of the particle, salinity, and turbulent 

mixing in the area (Poirier and Thiel, 1941; Bassin and Ichiye, 1977; Deleersbijder et al., 2006). Because 

particles would have different sinking rates, the oiled particles would be dispersed over a large area, most 

likely at sublethal or immeasurable levels. Studies conducted after the Ixtoc oil spill revealed that 

although oil was measured on particles in the water column, measurable petroleum levels were not found 
Description of the Environment and Impact Analysis 4-157 

in the underlying sediment (ERCO, 1982). Based on BOEMRE’s restrictions and the settling rates and 

behavior of oil attached to sediment particles, the majority of organisms that may be exposed to oil 

adsorbed to sediment particles are anticipated to experience low-level concentrations. 

Some oil, however, could reach topographic features as particles with adhered oil settle out of the 

water column. Sublethal impacts to benthic organisms from such exposure may include reduced 

recruitment success, reduced growth, and reduced coral cover as a result of impaired recruitment. 

Experiments have shown that the presence of oil on available substrate for larval coral settlement has 

inhibited larval metamorphosis and larval settlement in the area (Kushmaro et al., 1997). Crude oil 

concentrations as low as 0.1 ppm on substrate upon which the coral larvae were to settle reduced larval 

metamorphosis occurrences by 50 percent after 8 days of exposure. Oil concentrations of 100 ppm on 

substrates resulted in only 3.3 percent of the test population metamorphosizing (Kushmaro et al., 1997). 

There were also an increased number of deformed polyps after metamorphosis due to oil exposure 

(Kushmaro et al., 1997). It is also possible that recurring exposure may occur if oil adsorbed to sediment 

particles is resuspended locally, possibly inhibiting coral growth and recovery in the affected areas 

(Guzmán et al., 1994). Oil stranded in sediment is reportedly persistent and does not weather much (Hua, 

1999), so coral may be repeatedly exposed to low concentrations of oil. 

Adult coral, however, may be able to protect itself from low concentrations of oil adsorbed to 

sediment particles by production and sloughing of mucus. Coral mucus may act as a barrier to protect 

coral from the oil in the water column, and it has been shown to aid in the removal of oiled sediment on 

coral surfaces (Bak and Elgershuizen, 1976). Corals may use a combination of increased mucus 

production and ciliary action to rid themselves of oiled sediment (Bak and Elgershuizen, 1976). 

Blowout and Sedimentation 

Oil or gas well blowouts are possible occurrences in the OCS. Benthic communities exposed to large 

amounts of resuspended sediments following a subsurface blowout could be subject to sediment 

suffocation, exposure to toxic contaminants, and reduced light. Should oil or condensate be present in the 

blowout flow, liquid hydrocarbons could be an added source of negative impact on the benthos. 

Turbid waters have less light penetrating to depth, which may result in reduced photosynthesis by the 

symbiotic zooxanthellae that live in coral tissue (Rogers, 1990). Long-term exposures to turbidity have 

even resulted in significantly reduced skeletal extension rates in the scleractinian coral Montastraea 

annularis (Torres, 2001; Dodge et al., 1974) and an acute decrease in calcification rates of Madracis 

mirabilis and Agaricia agaricites (Bak, 1978). The higher the concentration of suspended sediment in the 

water column and the longer the sediment remains suspended, the greater the impact. 

Suspended sediment that is transported by currents deep in the water column should not impact the 

benthic organisms on the upper portions of topographic features. Studies have shown that deep currents 

sweep around topographic features instead of over them, allowing the suspended sediment to remain at 

depth (Rezak et al., 1983; McGrail, 1982). Therefore, suspended sediment from depth should not be 

deposited on top of the elevated benthic organisms. Organisms on the lower levels around topographic 

features are frequently enveloped in a turbid nepheloid layer; organisms surviving here are tolerant of 

heavy turbidity. 

Sediment that settles out of upper layers of the water column may impact benthic organisms of 

topographic features. Sediment deposition may smother benthic organisms, decreasing gas exchange, 

increasing exposure to anaerobic sediment, reducing light intensity, and causing physical abrasion 

(Wilber et al., 2005). Corals may experience reduced colony coverage, changes in species diversity and 

dominance patterns, alterations in growth rates and forms, decreased calcification, decreased 

photosynthesis, increased respiration, increased production in mucus, loss of zooxanthellae, lesions, 

reduced recruitment, and mortality (Torres et al., 2001; Telesnicki and Goldberg, 1995). Coral larvae 

settlement may also be inhibited in areas where sediment has covered available substrate (Rogers, 1990; 

Goh and Lee, 2008). 

Impacts to corals as a result of sedimentation would vary based on coral species, the height to which 

the coral grows, degree of sedimentation, length of exposure, burial depth, and the coral’s ability to clear 

the sediment. Impacts may range from sublethal effects such as reduced growth, alteration in form, 

reduced recruitment and productivity, and slower growth to death (Rogers, 1990). 
4-158 Central Planning Area Supplemental EIS 

Corals have some ability to rid themselves of sediment through mucus production and ciliary action 

(Marszalek, 1981; Bak and Elgershuizen, 1976; Telesnicki and Goldberg, 1995). Scleractinian corals are 

tolerant of short-term sediment exposure and burial, but longer exposures may result in loss of 

zooxanthellae, polyp swelling, increased mucus production, reduced coral growth, and reduced reef 

development (Marszalek, 1981; Rice and Hunter, 1992). Bleached tissue as a result of sediment exposure 

has been reported to recover in approximately a month (Wesseling et al., 1999). 

Solitary octocorals and gorgonians, which are found on many hard-bottom features, are more tolerant 

of sediment deposition than colony-forming scleractinian corals because the solitary species grow erect 

and are flexible, reducing sediment accumulation and allowing easy removal (Marszalek, 1981; Torres et 

al., 2001; Gittings et al., 1992b). Branching and upright forms of scleractinian corals, such as Madracis 

mirabilis and Agaricia agaricites, also tend to be more tolerant of sediment deposition than massive, 

plating, and encrusting forms, such as Porites astreoides (Roy and Smith, 1971; Bak, 1978). Some of the 

more sediment tolerant scleractinian species in the Gulf of Mexico include Montastraea cavernosa, 

Siderastrea siderea, Siderastrea radians, and Diploria strigosa (Torres et al., 2001; Acevedo et al., 1989; 

Loya, 1976b). 

Since the BOEMRE-proposed stipulation would preclude drilling within 152 m (500 ft) of the No 

Activity Zone, most adverse effects on topographic features from blowouts would be prevented. 

Petroleum-producing activities would be far enough removed that heavy layers of sediment that may 

become resuspended as a result of a blowout should settle out of the water column before they reach 

sensitive biological communities. Other particles that travel with currents should become dispersed as 

they travel, reducing turbidity or depositional impacts. Furthermore, sediment traveling at depth should 

remain at depth instead of rising to the top of topographic features. 

Response Activity Impacts 

Oil-spill-response activity may also affect sessile benthic communities on topographic features. 

Booms anchored to the seafloor are sometimes used to control the movement of oil at the water surface. 

Boom anchors can physically damage corals and other sessile benthic organisms, especially when booms 

are moved around by waves (Tokotch, 2010). Vessel anchorage and decontamination stations set up 

during response efforts may also break or kill hard-bottom features as a result of setting anchors. Spill 

response, especially in the case of a catastrophic spill, can involve activity by varied organizations, 

including many that are not coordinated by the oil-spill-response plan. While the spill-response plan and 

activities coordinated by responsible agencies such as NOAA and USCG would avoid damaging sensitive 

habitats, the risk remains that some other responders may not be aware of all the sensitive habitats of 

concern. Injury to coral reefs as a result of anchor contact may result in long-lasting damage or failed 

recovery (Rogers and Garrison, 2001). Effort should be made to keep vessel anchorage areas far from 

sensitive benthic features to minimize impact. 

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud may be forced out of the well and deposited on the seafloor near the well site. 

Any organisms beneath the extruded drilling mud would be buried. Based on the BOEMRE stipulation 

(NTL 2009-G39), a well should be far enough away from topographic features to prevent extruded 

drilling muds from smothering sensitive benthic communities. It is more likely that benthic organisms on 

topographic features would experience turbidity or light layers of sedimentation due to a blowout based 

on the BOEMRE stipulation. Turbidity impacts may result in reduced photosynthesis or growth (Rogers, 

1990; Torres, 2001). Light layers of deposited sediment would most likely be removed by mucus and 

ciliary action (Marszalek, 1981; Bak and Elgershuizen, 1976; Telesnicki and Goldberg, 1995). 

Proposed Topographic Features Stipulation 

The proposed Topographic Features Stipulation would preclude drilling within 152 m (500 ft) of a No 

Activity Zone to prevent adverse effects from nearby drilling on topographic features. The BOEMRE has 

created a No Activity Zone around topographic features in order to protect these habitats from disruption 

due to oil and gas activities. A No Activity Zone is a protective perimeter drawn around each feature that 

is associated with a specific isobath (depth contour) surrounding the feature in which structures, drilling 

rigs, pipelines, and anchoring are not allowed. These No Activity Zones are areas protected by BOEMRE 

policy. The NTL 2009-G39 recommends that drilling would not occur within 152 m (500 ft) of a No 
Description of the Environment and Impact Analysis 4-159 

Activity Zone of a topographic feature. This additional recommendation is based on essential fish habitat, 

and construction within the essential fish habitat would require project-specific consultation with NOAA. 

Although the BOEMRE’s proposed stipulation prevents oil and gas drilling activity within 152 m 

(500 ft) of the No Activity Zone of topographic features, some sublethal effects may occur to benthic 

organisms as a result of an oil spill. Sublethal impacts may include exposure to low levels of oil, 

dispersed oil, oil adsorbed to sediment particles, and turbidity and sedimentation from disturbed 

sediments. Impacts from these exposures may include reduced photosynthesis, reduced growth, altered 

behavior, decreased community diversity, altered community composition, reduction in coral cover, and 

reduced reproductive success. The severity of these impacts may depend on the concentration and 

duration of exposure. 

Proposed Action Analysis 

All of the topographic features in the CPA are found in water depths less than 200 m (656 ft). They 

represent a small fraction of the continental shelf area in the CPA. The fact that the topographic features 

are widely dispersed, combined with the probable random nature of oil-spill locations, serves to limit the 

extent of damage from any given oil spill to the topographic features. 

The proposed Topographic Features Stipulation (Chapter 2.4.1.3.1) would assist in preventing most 

of the potential impacts from oil and gas operations, including accidental oil spills and blowouts, on the 

biota of topographic features. However, operations outside the No Activity Zone (including blowouts and 

oil spills) may still affect topographic features. 

The depth below the sea surface to which many topographic features rise helps to protect them from 

surface oil spills. Any oil that might be driven to 15 m (49 ft) or deeper would probably be at 

concentrations low enough to reduce impact to these features. 

A subsurface spill or plume may impact sessile biota of topographic features. Oil or dispersed oil 

may cause sublethal impacts to benthic organisms if a plume reaches these features. Impacts may include 

loss of habitat, biodiversity, and live coverage; change in community structure; and failed reproductive 

success. The proposed Topographic Features Stipulation would limit the potential impact of such 

occurrences by keeping the sources of such adverse events geographically removed from the sensitive 

biological resources of topographic features. 

Oil adsorbed to sediments or sedimentation as a result of a blowout may impact benthic organisms. 

However, the proposed Topographic Features Stipulation places petroleum-producing activity at a 

distance from topographic features, resulting in reduced turbidity and sedimentation, and any oil adsorbed 

to sediments should be well dispersed, resulting in a light layer of deposition that would be removed by 

the normal self-cleaning processes of benthic organisms. 

Summary and Conclusion 

The proposed Topographic Features Stipulation would assist in preventing most of the potential 

impacts on topographic feature communities from blowouts, surface, and subsurface oil spills and the 

associated effects by increasing the distance of such events from the topographic features. Any contact 

with spilled oil would likely cause sublethal effects to benthic organisms because the distance of activity 

would prevent contact with concentrated oil. In the unlikely event that oil from a subsurface spill would 

reach the biota of a topographic feature, the effects would be primarily sublethal and impacts would be at 

the community level. Any turbidity, sedimentation, and oil adsorbed to sediments would also be at low 

concentrations by the time the topographic features were reached, also resulting in sublethal impacts. 

Impacts from an oil spill on topographic features are also lessened by the distance of the spill to the 

features, the depth of the features, and the currents that surround the features. 

Effects of the Proposed Action without the Proposed Stipulation 

The topographic features and associated coral reef biota of the CPA could be damaged by oil and gas 

activities resulting from the proposed action should they not be restricted by application of the proposed 

Topographic Features Stipulation. This would be particularly true should operations occur directly on top 

of or in the immediate vicinity of otherwise protected topographic features. The area within the No 

Activity Zone would probably be the areas of the topographic features that are most susceptible to adverse 
4-160 Central Planning Area Supplemental EIS 

impacts if oil and gas activities are unrestricted by the proposed Topographic Features Stipulation. These 

impacting factors would include blowouts, surface oil spills, and subsea oil spills. Potential impacts from 

routine activities resulting from the proposed action are discussed in Chapter 4.1.1.7.2. 

Oil spills as well as routine activities have the potential to considerably alter the diversity, cover, and 

long-term viability of the reef biota found within the No Activity Zone if the proposed Topographic 

Features Stipulation is not applied. Direct oil contact may result in acute toxicity (Dodge et al., 1984; 

Wyers et al., 1986). In most cases, recovery from disturbances would take 10 years or more (Fucik et al., 

1984; Rogers and Garrison, 2001). Indeed, disturbances, including oil spills and blowouts, would alter 

benthic substrates and their associated biota over large areas. In the unlikely event of a blowout, sediment 

resuspension potentially associated with oil could cause adverse turbidity and sedimentation conditions. 

In addition to affecting the live cover of a topographic feature, a blowout could alter the local benthic 

morphology, thus irreversibly altering the reef community. Oil spills (surface and subsea) could be 

harmful to the local biota should the oil have a prolonged or recurrent contact with the organisms. 

Therefore, in the absence of the proposed Topographic Features Stipulation, the proposed action could 

cause long-term (10 years or more) adverse impacts to the biota of the topographic features. 

4.1.1.7.4. Cumulative Impacts 

The proposed Topographic Features Stipulation is assumed to be in effect for this cumulative 

analysis. The continued application of this proposed stipulation would prevent any direct adverse impacts 

on the biota of the topographic features, i.e., impacts potentially generated by oil and gas operations. The 

cumulative impact from routine oil and gas operations includes effects resulting from the proposed action, 

as well as those resulting from past and future OCS leasing. These operations include anchoring, 

structure emplacement, muds and cuttings discharge, effluent discharge, blowouts, oil spills, and structure 

removal. Potential non-OCS-related factors include vessel anchoring, treasure-hunting activities, import 

tankering, heavy storms and hurricanes, the collapse of the tops of the topographic features due to 

dissolution of the underlying salt structure, commercial fishing, and recreational scuba diving. 

Mechanical damage, including anchoring, is considered to be a catastrophic threat to the biota of 

topographic features. The proposed Topographic Features Stipulation prohibits oil and gas leaseholders 

from anchoring vessels and placing structures within 152 m (500 ft) of the No Activity Zone around 

topographic features (Chapter 2.4.1.3.1) (USDOI, MMS, 2009b); the stipulation does not affect other 

non-OCS activities such as anchoring, fishing, or recreational scuba diving, or anchoring other vessels on 

or near these features. Many of the topographic features are found near established shipping fairways and 

are well-known fishing areas. Also, several of the shallower topographic features are frequently visited 

by scuba divers aboard recreational vessels (Hickerson et al., 2008). Anchoring at a topographic feature 

by a vessel involved in any of these activities could damage the biota. The degree of damage would 

depend on the size of the anchor and chain (Lissner et al., 1991). Anchor damages incurred by benthic 

organisms may take more than 10 years to recover, depending on the extent of the damage (Fucik et al., 

1984; Rogers and Garrison, 2001). 

The use of explosives in treasure-hunting operations has become a concern on topographic features; 

several large holes and damage have occurred on Bright Bank. The blasting of large areas of Bright Bank 

by treasure hunters has resulted in the loss of extensive live coral cover (Schmahl and Hickerson, 2006). 

Treasure hunters have damaged the bank as recently as 2001 (Schmahl and Hickerson, 2006). The 

recovery from such destructive activity may take in excess of 10 years (Fucik et al., 1984; Rogers and 

Garrison, 2001). Recovery of the system to pre-interference conditions would depend on the type and 

extent of damage incurred by individual structures. 

Impacts from natural occurrences such as hurricanes occasionally result in damage to the biota of the 

topographic features. Hurricane Rita caused severe damage to Sonnier Bank (Robbart et al., 2009). Live 

cover was reduced at this bank and the disappearance of the sponge colonies, Xestospongia muta, was 

notable (Robbart et al., 2009). The community structure had visibly changed from pre-Rita (2004) studies 

at this bank (Kraus et al., 2006 and 2007). In 2006, the habitat was dominated by algae, indicating an 

alteration in habitat after Hurricane Rita (Kraus et al., 2007). The algal cover, however, was the 

beginning of recovery of the storm-impacted areas, which was farther colonized with sponges (Robbart et 

al., 2009). Fish community shifts were also observed on Sonnier Bank after Hurricane Rita versus before 

the storm, but clear links have yet to be made to the storm (Kraus et al., 2007). Hurricane Katrina may 
Description of the Environment and Impact Analysis 4-161 

have caused similar damage on other topographic features. Another possible natural impact to the banks 

would be the dissolution of the underlying salt structure, leading to collapse of the reef (Seni and Jackson, 

1983). Dissolution of these salt structures is unlikely and beyond regulation abilities. 

Depending on the levels of fishing pressure exerted, fishing activities that occur at the topographic 

features may impact local fish populations. The collecting activities by scuba divers on shallow 

topographic features may have an adverse impact on the local biota. Anchoring during recreational and 

fishing activities, however, would be the source of the majority of severe impacts incurred by the 

topographic features. 

The continued application of the proposed Topographic Features Stipulation precludes anchoring on 

topographic features by oil- and gas-related operations. Detrimental impacts would result if oil and gas 

operators anchored pipeline barges, drilling rigs, and service vessels or if they placed structures on 

topographic features (Rezak and Bright, 1979; Rezak et al., 1985). The Topographic Features Stipulation 

restricts these activities within 152 m (500 ft) of the No Activity Zone around topographic features, thus 

preventing adverse impacts on benthic communities of topographic communities (USDOI, MMS, 2009b). 

The routine discharge of drilling muds and cuttings is restricted in the vicinity of topographic 

features. It is estimated that approximately 2,000 metric tons (2,205 tons) are discharged for exploratory 

wells (900 metric tons [992 tons] of drilling fluid and 1,100 metric tons [1,213 tons] of cuttings) and 

slightly lower discharges for development wells (Neff, 2005). Continued application of the Topographic 

Features Stipulation would require lease operators to comply with measures, such as shunting that would 

keep discharged materials at depths below sensitive biota. 

The USEPA, through its NPDES discharge permit, also enacts further mitigating measures on 

discharges. As noted in Chapter 4.1.1.7.2 above, drilling fluids can be moderately toxic to marine 

organisms (the more toxic effluents are not allowed to be discharged under NPDES permits), and their 

effects are restricted to areas closest to the discharge point, thus preventing contact with the biota of 

topographic features (Montagna and Harper, 1996; Kennicutt et al., 1996). Small amounts of drilling 

effluent in low concentrations may reach a bank from wells outside the No Activity Zone; however, these 

amounts, if measurable, would be extremely small and would be restricted to small areas with little effects 

on the biota. 

The proposed Topographic Features Stipulation would protect topographic features by mandating a 

physical distance from drilling activities. Drilling fluid plumes are rapidly dispersed on the OCS; 

approximately 90 percent of the material discharged in drilling a well (cuttings and drilling fluid) settles 

rapidly to the seafloor, while 10 percent forms a plume of fine mud that drifts in the water column (Neff, 

2005). Shunting of drill muds and cutting is required for wells drilled in the vicinity of topographic 

features. Shunting restricts the cuttings to a smaller area and places the turbidity plume near the seafloor 

where the environment is frequently turbid and benthic communities are adapted to high levels of 

turbidity. Water currents moving turbidity plumes across the seafloor would sweep around topographic 

features rather than carrying the turbidity over the banks (Bright and Rezak, 1978). Any sediment that 

may reach coral can be removed by the coral using tentacles and mucus secretion, and physically 

removed by currents that can shed the mucus-trapped particles from the coral (Shinn et al., 1980; Hudson 

and Robin, 1980). 

With the inclusion of the proposed Topographic Features Stipulation, no discharges of effluents, 

including produced water would take place within the No Activity Zone. Drill cuttings in areas around 

the No Activity Zone would be shunted to within 10 m (33 ft) of the seabed. This procedure, combined 

with USEPA’s discharge regulations and permits, should eliminate the threat of discharges reaching and 

affecting the biota of a topographic high. The impacts that these discharges could cause would be 

primarily sublethal damages that could lead to a possible disruption or impairment of a few elements at a 

local scale, but no interference to the general ecosystem performance should occur. 

Impacts on the topographic features could occur as a result of oil- and gas-related spills or spills from 

import tankering. Due to dilution and the depths of the crests of the topographic features, discharges 

should not reach topographic features in sufficient concentrations to cause impacts. Tanker accidents 

would result in surface oil spills, which generally do not mix below a depth of 10-20 m (33-66 ft) (Lange, 

1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002), which should protect most topographic 

features, very few of which rise to within 15 m (50 ft) of the sea surface. Any dispersed surface oil from 

a tanker spill that may reach the benthic communities of topographic features in the Gulf of Mexico 

would be expected to be at very low concentrations (less than 1 ppm) (McAuliffe et al., 1981a and 1981b; 
4-162 Central Planning Area Supplemental EIS 

Lewis and Aurand, 1997). Such concentrations would not be life threatening to larval or adult stages 

based on experiments conducted with coral (Lewis, 1971; Elgershuizen and De Kruijf, 1976; Knap, 1987; 

Wyers et al., 1986; Cohen et al., 1977) and observations after oil spills (Jackson et al., 1989; Guzmán et 

al., 1991). Any dispersed or physically mixed oil in the water column that comes in contact with corals, 

however, may evoke short-term negative responses by the organisms, such as reduced feeding and 

photosynthesis or altered behavior (Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 1984). 

Potential blowouts could impact the biota of the topographic features. Based on the proposed 

Topographic Features Stipulation, few blowouts, if any, would reach the No Activity zone around the 

topographic features. The proposed stipulation creates a buffer zone around the banks that would protect 

them from direct impacts by damaging amounts of suspended sediment from a seafloor blowout. Most of 

the oil from a seafloor blowout would rise to the surface, but some of it may be entrained in the water 

column as a subsea plume. Oil in a subsea plume could be carried to a topographic feature. The resulting 

level of impacts depends on the concentration of the oil when it contacts the habitat. The farther the 

blowout is from the topographic feature, the more dispersed the oil and sediment would become, reducing 

the possible impacts. Also, because currents sweep around topographic features instead of over them, 

subsea oil should be directed away from the more sensitive communities on the upper levels of 

topographic features (Rezak et al., 1983; McGrail, 1982). If oil were to contact the topographic features, 

the impacts may include loss of habitat, biodiversity, and live coverage; change in community structure; 

and failed reproductive success. In the highly unlikely event that oil from a subsurface spill could reach a 

coral-covered area in lethal concentrations, the recovery of this area could take in excess of 10 years 

(Fucik et al., 1984). 

The cumulative impact of the possibility of a future oil spill along with the DWH event is anticipated 

to be extremely small. It is highly unlikely that the topographic features of the CPA were or will be 

impacted by the DWH event because of their distance from the blowout. Impacts may include reduced 

recruitment success, reduced growth, and reduced coral cover as a result of impaired recruitment. These 

impacts, if they occur, may be difficult to measure. 

Platforms will be removed from the OCS Program each year; some may be in the vicinity of 

topographic features (Table 3-2). However, the proposed Topographic Features Stipulation prevents the 

installation of platforms near the No Activity Zone, thus reducing the potential for impact from platform 

removal. The explosive removals of platforms are far enough away to prevent impacts to the biota of the 

topographic features. 

Summary and Conclusion 

Activities causing mechanical disturbance represent the greatest threat to the topographic features. 

This would, however, be prevented by the continued application of the proposed Topographic Features 

Stipulation. Potential OCS-related impacts include anchoring of vessels and structure emplacement, 

operational discharges (drilling muds and cuttings, and produced waters), blowouts, oil spills, and 

structure removal. 

The proposed Topographic Features Stipulation would preclude mechanical damage caused by oil 

and gas leaseholders from impacting the benthic communities of the topographic features and would 

protect them from operational discharges by establishing a buffer around the feature. As such, little 

impact would be incurred by the biota of the topographic features. The USEPA discharge regulations and 

permits would further reduce discharge-related impacts. 

Blowouts could potentially cause damage to benthic biota; however, due to the application of the 

proposed Topographic Features Stipulation, blowouts would not reach the No Activity zone surrounding 

the topographic features and associated biota, resulting in little impact on the features. If a subsea oil 

plume is formed, it could contact the habitats of a topographic feature; this contact may be restricted to 

the lower, less sensitive levels of the banks and/or may be swept around the banks with the prevailing 

water currents. The farther the oil source is from the bank, the more dilute and degraded the oil would be 

when it reaches the vicinity of the topographic features. 

Oil spills can cause damage to benthic organisms when the oil contacts the organisms. The proposed 

Topographic Features Stipulation would keep sources of OCS spills at least 152 m (500 ft) away from the 

immediate biota of the topographic features. In the unlikely event that oil from a subsurface spill would 

reach the biota of a topographic feature, the effects would be primarily sublethal for corals and much of 
Description of the Environment and Impact Analysis 4-163 

the other fully developed biota. In the event that oil from a subsurface spill reached an area containing 

hermatypic coral cover in lethal concentrations, the recovery could take in excess of 10 years (Fucik et al., 

1984). Finally, in the unlikely event a freighter, tanker, or other oceangoing vessel related to OCS 

Program activities or non-OCS-related activities sank and proceeded to collide with the topographic 

features or associated habitat releasing its cargo, recovery could take years to decades, depending on the 

extent of the damage. Because these events are rare in occurrence, the potential of impacts from these 

events is considered low. 

Non-OCS activities could mechanically disrupt the bottom (such as anchoring and treasure-hunting 

activities, as previously described). Natural events such as hurricanes or the collapse of the tops of the 

topographic features (through dissolution of the underlying salt structure) could cause severe impacts. 

The collapsing of topographic features is unlikely and would impact a single feature. Impacts from scuba 

diving, fishing, ocean dumping, and discharges or spills from tankering of imported oil could have 

detrimental effects on topographic features. 

Overall, the incremental contribution of the CPA proposed action to the cumulative impact is 

negligible because of the implementation of the proposed Topographic Features Stipulation, which would 

limit mechanical impacts and operational discharges. 

4.1.1.8. Sargassum 

A description of Sargassum as a resource has not been included in previous NEPA evaluations 

conducted in the Gulf of Mexico by BOEMRE. Therefore, there is no prior discussion in the Multisale 

EIS or the 2009-2012 Supplemental EIS upon which to tier or information from these documents that 

could be incorporated by reference. 

4.1.1.8.1. Description of the Affected Environment 

Sargassum is one of the most ecologically important brown algal genera found in the pelagic 

environment of tropical and subtropical regions of the world. The pelagic complex in the GOM is mainly 

comprised of S. natans and S. fluitans (Lee and Moser, 1998; Stoner, 1983; Littler and Littler, 2000). 

Both species of macrophytes (aquatic plants) are hyponeustonic (living immediately below the surface) 

and fully adapted to a pelagic existence (Lee and Moser, 1998). Also known as gulf-weed or sea holly 

(Coston-Clements et al., 1991; Lee and Moser, 1998), Sargassum is characterized by a brushy, highly 

branched thallus (stem) with numerous leaf-like blades and berrylike pneumatocysts (air bladders or 

floats) (Coston-Clements et al., 1991; Lee and Moser, 1998; Littler and Littler, 2000). The air bladders 

contain mostly oxygen with some nitrogen and carbon dioxide, allowing for buoyancy. These floating 

plants may be up to a few meters in length and may be found floating alone or in larger rafts or mats that 

support communities of fish and a variety of other marine organisms. The distribution, size, and 

abundance of Sargassum mats varies depending on environmental and physiochemical factors such as 

temperature, salinity, and dissolved oxygen. 

Habitat 

Sargassum provides islands of high energy and carbon content in an otherwise nutrient- and carbonpoor environment (Stoner, 1983). Sargassum mats support a diverse assemblage of marine organisms 

including micro- and macro-epiphytes (plants that grow on plants) (Carpenter and Cox, 1974; CostonClements et al., 1991), fungi (Winge, 1923), more than 100 species of invertebrates (Coston-Clements et 

al., 1991), over 100 species of fish (Dooley, 1972; Stoner, 1983), four species of sea turtles (Carr, 1987; 

Manzella et al., 2001), and various marine birds (Lee and Moser, 1998). Sargassum serves as nurseries, 

sanctuaries, and forage grounds for both commercially and recreationally exploited species. Numerous 

epipelagic fish (fish in upper ocean waters, where light penetrates) use the Sargassum as a source of food, 

certain flying fish lay eggs in the floating mats, and other fish use it as nursery grounds (Adams, 1960; 

Bortone et al., 1977; Dooley, 1972). Sea turtles have been seen using the protective mats for passive 

migration as hatchlings (Carr and Meylan, 1980). These communities may also vary depending on the 

environmental and physiochemical factors known to affect Sargassum, resulting in variable species 

composition, life histories, and diversity. It has been noted that inshore Sargassum communities differ in 

species composition than offshore communities, due to the varied effects of salinity and dissolved 
4-164 Central Planning Area Supplemental EIS 

oxygen. Recent findings suggest that Sargassum provides critical habitat that may have an influence on 

the recruitment success of several species (South Atlantic Fishery Management Council, 2002; Wells and 

Rooker, 2004). 

Invertebrates 

Epiphytic cyanobacteria contribute to overall production and nutrient recycling within the Sargassum

complex (Wells and Rooker, 2004). The algae is colonized first by bacteria, followed by hydroids and 

bryozoans, which provide the base of a food web containing a variety of invertebrates, fishes, and sea 

turtles (Bortone et al., 1977; Dooley, 1972). 

Both sessile and motile invertebrates are found within the Sargassum community. Epifauna (animals 

living on the substrate) include colonial hydroids, encrusting bryozoans, the polychaete Spirorbis, 

barnacles, sea spiders, and the tunicate Diplosoma. Older plants can become heavily encrusted with these 

organisms, causing them to sink to the seafloor. A sunken mat will eventually disintegrate, providing 

further nourishment for animals in deeper water (Coston-Clements et al., 1991; Parr, 1939). Some of the 

motile fauna found within the floating communities include polychaetes, flatworms, nudibranchs, 

decapod crustaceans (such as Latreutes and Leander shrimps and Portunus crabs), and various molluscs 

(including the Sargassum snail Litiopa melanostoma) (Parr, 1939). 

Fish 

Fish assemblages in Sargassum mats located in the GOM and the Atlantic have shown similarities in 

species composition. In studies by Dooley (1972) and Bortone et al. (1977), 90-97 percent of the total 

catch was represented by jacks, pompanos, jack mackerels, scads, triggerfish, filefish, seahorse, pipefish, 

and frogfish in both regions. The abundance of juvenile fish associated with these mats suggests that they 

serve as an important nursery habitat for numerous species, including filefish, sergeant majors, tripletail, 

silver mullet, flying fish, and various jacks (Dooley, 1972). Some species that are endemic to Sargassum

utilize the habitat for early life stages as well as adult stages, while other species may rely on the habitat 

only as a source of food and protection during early life stages (Wells and Rooker, 2004). The patterns of 

habitat use by many of the juvenile fish associated with Sargassum have exhibited spatial and temporal 

variability. Monthly influences such as environmental conditions appear to have an important role in the 

Sargassum fish assemblages within the northwestern GOM. By serving as an important nursery habitat 

for pelagic, benthic, and even estuarine species, Sargassum may have influence on the recruitment 

success of the fishes using it as habitat. 

The importance of Sargassum differs among species depending on its role as essential fish habitat. 

The NMFS has designated Sargassum as essential fish habitat in the south Atlantic (Coston-Clements, 

1991; USDOC, NMFS, 2010a). However, more studies are needed in order to evaluate the importance of 

Sargassum as habitat in the northwestern GOM, where Sargassum is the predominant cover and structure 

offering habitat for pelagic species at the sea surface. 

Turtles 

Four of the five species of sea turtles found in the GOM are associated with floating Sargassum (Carr 

and Meylan, 1980; Carr, 1987; Coston-Clements et al., 1991; Schwartz, 1988). The hatchlings of 

loggerhead (Caretta caretta), green (Chelonia mydas), Kemp’s ridley (Lepidochelys kempii), and 

hawksbill (Eretmochelys imbricata) sea turtles are thought to find the Sargassum rafts when actively 

seeking frontal zones, then utilizing the habitat as foraging grounds and protection during their pelagic 

“lost years” (juvenile years in which turtle sightings are scarce) (Carr, 1987; Coston-Clements et al., 

1991). Schwartz (1988) reported numerous loggerhead hatchlings during commercial trawling for 

Sargassum in the Atlantic. This provided the largest count of hatchlings on record to date. After 

Hurricane David hit the Gulf in September 1979, Carr and Meylan (1980) collected dead and live turtles 

that were found in the Sargassum mats that had washed up on Cocoa Beach. The stomach content of the 

turtles was solely Sargassum floats and leafy parts, further emphasizing the importance of the habitat for 

pelagic growth stages of sea turtles. 
Description of the Environment and Impact Analysis 4-165 

Birds 

A study by Lee and Moser (1998) found that the presence or absence of Sargassum drives local 

abundance and occurrence of certain species of marine birds. Various avian species utilize the resource in 

specific ways, by feeding on small fishes and other organisms in the Sargassum communities. In Lee and 

Moser’s study, birds with over 25 percent of their prey living in Sargassum are classified as Sargassum

specialists. Specialist species included shearwaters (59%), masked boobies (100%), phalaropes (62%), 

and various species of terns (40-60%). Both the GOM and Atlantic pelagic environment provide nutrient 

poor surface waters with low productivity. Therefore, the importance of this highly productive 

Sargassum community to seabird abundance and seasonal distribution is assumed to be high. 

Distribution 

Approximately 1 million wet cubic tons of Sargassum (natans and fluitans) is estimated to grow and 

circulate in the GOM annually. Over 80 percent of this is the dominant species S. natans (Parr, 1939). 

Wells and Rooker (2004) suggest that the abundance and age of Sargassum increases when found in 

slow-moving gyres, such as found in the western GOM and the Sargasso Sea (middle of the North 

Atlantic). These waters provide the ideal environment for Sargassum to grow and provide abundant 

habitat for associated organisms (Dooley, 1972). 

Research by Gower and King (2008) suggests that the northwest GOM is the “major nursery area” for 

Sargassum that supplies the Atlantic population. The transportation of these plants is influenced by 

winds and ocean currents, and the winds over the Gulf blow predominantly from the east to the west and 

adjacent waters move from the west to the east (Parr, 1939; Rhodes et al., 1989). Sargassum originates in 

the northwestern GOM in March of each year, where it remains for long periods of time in the slowly 

rotating gyres of western GOM waters (Gower et al., 2006, Gower and King, 2008). In the months of 

May, June, and July, Sargassum is at its most abundant. The Sargassum begins to expand and spreads 

eastward into the central and eastern Gulf waters, taking up to 2 months to move across the Gulf, where it 

will eventually exit in the Loop Current. The movement of passive drift buoys deployed to track water 

currents corroborates this pattern of Sargassum movement from the Gulf to the Atlantic (Gower et al., 

2006). It was previously assumed that Sargassum in the Atlantic originated in the Sargasso Sea. 

However, Gower and King (2008) used satellite imagery to determine that the Loop Current and Gulf 

Stream are responsible for distributing a large amount of Sargassum from the GOM into the Atlantic near 

Cape Hatteras in July and August. From September through February, the Sargassum that was distributed 

in the Atlantic mixes into the Sargasso Sea, loops around to the south, and dies in the waters north of the 

Bahamas, about a year after it originated in the GOM. 

Historic Impacts on Sargassum

Studies by Parr (1939) and Stoner (1983) suggest that a significant decrease in Sargassum biomass 

has occurred from the 1930’s through the 1980’s, presumably because of increased pollutants and toxins 

in the pelagic environment. Burns and Teal (1973) found that Sargassum and its associates accumulate 

and concentrate petroleum hydrocarbons. An increase in petroleum pollution and associated toxic effects 

in the GOM may have attributed to the declining macrophyte populations. Sargassum has been noted to 

have higher levels of toxins than in surrounding water samples in polluted areas. Oceanographic 

processes that concentrate Sargassum into mats and rafts may also concentrate toxic substances. 

Therefore, it may be assumed that Sargassum can be found in areas where oil, dispersants, and other 

pollutants have accumulated since the DWH event. 

The highest concentration of Sargassum in the GOM during the months of June and July was in the 

vicinity of the DWH event. Since Sargassum would occupy the same portion of water as oil on the sea 

surface and dispersed oil, it can be presumed that oil has damaged or destroyed some Sargassum mats and 

associated organisms. Dead Sargassum would have sunk to the seafloor, possibly affecting localized 

areas of benthic habitat. A noticeable decline in GOM Sargassum biomass as a result of the DWH event 

may also adversely affect the biomass of Sargassum in Atlantic waters because of the annual movement 

of Sargassum from the GOM into the Atlantic (Gower and King, 2008). Once water quality in the GOM 

returns to pre-DWH event conditions, Sargassum and its associated communities may take additional 

time before displaying pre-DWH event abundance and species composition. 
4-166 Central Planning Area Supplemental EIS 

A broad Internet search for relevant new information, as well as a search for scientific journal articles, 

was conducted using a publicly available search engine. A search for relevant information gathered 

during the Ixtoc spill of 1979 was conducted. In addition, the websites for Federal and State agencies, as 

well as other organizations, were reviewed for newly released information. Sources investigated include 

the South Atlantic Fishery Management Council, coordinated communications with the Gulf of Mexico 

Alliance, USEPA, USGS, and coastal universities. Interviews with personnel from academic institutions 

and governmental resource agencies were conducted to determine the availability of new information. In 

addition, there are ongoing NOAA- and National Science Foundation-funded research projects that are 

investigating the Sargassum distribution and impacts from the DWH event. 

4.1.1.8.2. Impacts of Routine Events 

Impact-producing factors associated with routine events for the CPA proposed action that could affect 

Sargassum may include (1) drilling discharges (muds and cuttings); (2) produced water and well 

treatment chemicals; (3) operational discharges (deck drainage, sanitary and domestic water, bilge and 

ballast water); and (4) physical disturbance from vessel traffic and the presence of exploration and 

production structures (i.e., rigs, platforms, and MODU’s). 

Drilling activities differ from other routine activities in the use of drilling muds and the discharge of 

drill cuttings. Modern drilling muds are typically synthetic-based muds. These muds are more costly 

than water-based muds and are routinely recycled rather than released. The USEPA regulates the 

composition of drilling muds to limit toxic components permitted for use. Some muds are released during 

initial spudding of the well (the first segment of the well, before the outer casing is installed); however, 

this release of drilling muds is at the seafloor. Since the muds are heavier than seawater, the muds and 

cuttings from the spudding process generally settle to the seafloor within about 100 m (328 ft) of the well 

site (CSA, 2006a). Therefore, this release at the seafloor would not affect the pelagic Sargassum

community, which floats on and near the sea surface. 

Drill cuttings are typically discharged from the drill platform (on or near the sea surface) during 

drilling. Drill cuttings are heavier than seawater and, when released at the sea surface in deep water, 

generally sink to the seafloor within less than 1,000 m (3,281 ft) of the well site (CSA, 2006a). Cuttings 

can contain some concentrations of naturally-occurring substances that are toxic, e.g., arsenic, cadmium, 

mercury, other heavy metals, and hydrocarbons (Neff, 2005). Hydrogen sulfide is also produced from 

some wells. In addition, some amount of drilling muds is included with the cuttings discharges, as the 

recycling process is not 100 percent efficient. However, the composition of muds is strictly regulated and 

discharges of cuttings/muds are tested to ensure that toxicity levels are below the limits allowed by 

NPDES permits (USEPA, 2004a, 2007d, and 2009a). 

The routine discharge of drill cuttings and muds is expected to have little effect on Sargassum

communities. There are three arguments that support this conclusion. First, as highlighted above, muds 

and cuttings are heavier than seawater, so they would sink relatively rapidly. This means that the 

Sargassum at or near the sea surface would only be exposed to contact with discharges for a short time. 

The Sargassum would be traveling laterally with the surface water current; at the same time, the muds and 

cuttings would be rapidly sinking toward the seafloor. Second, the toxicity of muds and cuttings is 

limited by applicable regulations, so effects can be expected to be low if Sargassum is contacted. Third, 

discharges affect only a localized area of the sea surface. The proposed action is estimated to result in a 

total of 287 wells in the WPA and 697 wells in the CPA. While this may seem like a large number of 

wells, they would affect only a very small portion of the 115,645 km2

 (44,651 mi2) of the WPA and 

268,922 km2

 (103,831 mi2) of the CPA. Although Sargassum occurs in most of the northern GOM, it is 

not abundant, or even present, in all waters at all times. Therefore, only a small portion of pelagic 

Sargassum in the GOM would come in contact with drill cuttings and muds and that contact would be 

brief. 

Produced waters may have an effect on Sargassum communities. Water is often a component of the 

fluid extracted from a well in offshore oil and gas operations. It is more prevalent with oil than with gas 

extraction. The water is typically separated from the product on a platform and discharged at the sea 

surface. Produced waters usually have high salinity, high organic carbon, and low dissolved oxygen. 

They may also contain some added chemicals used in well treatment. These characteristics could make 

the produced waters toxic to some organisms in the Sargassum community, particularly crustaceans and 
Description of the Environment and Impact Analysis 4-167 

filter feeders (e.g., bryozoa). However, the produced waters are required to meet toxicity limits defined 

by NPDES permits and would further diffuse through the water mass, reducing concentrations of any 

toxic component (USEPA, 2004a, 2007d, and 2009a). The Sargassum algae itself has a waxy coating and 

would be unlikely to be affected by possible short-term exposure. 

Platform and service-vessel operational discharges may have an effect on water quality, indirectly 

affecting Sargassum in the immediate area of activity. Since Sargassum is ubiquitous in the northern 

GOM, it will come in contact with operational discharges. However, considering the ratio of the affected 

area (immediately surrounding the activity) to the entire planning area, and even larger area inhabited by 

Sargassum, it is clear that only a small percent of the total Sargassum population would contact 

operational discharges. 

Vessel traffic and the presence of production structures may act as temporary barriers and obstacles 

for free-floating Sargassum. Stationary platforms and their associated fouling communities may snag 

pelagic Sargassum as it passes. In the event that Sargassum is caught in the propellers or cooling water 

intakes of vessels associated with the proposed action, repairable damage may occur to the Sargassum. 

Further research would enhance our knowledge of the effects, if any, of muds, cuttings, operational 

discharges, and physical impingement on Sargassum and its associated communities. Sargassum may 

have the capacity to absorb chemical substances, which may indirectly affect the health of the Sargassum 

and/or associated organisms. The likelihood that Sargassum would contact routine discharges or impinge 

on ships or stationary platforms is high. However, only a small part of the total population would receive 

these types of contact, contact would be only for a short time, and concentrations would be low (within 

permit limits). Given the ratio of Sargassum habitat to the surface area of the proposed activities, it may 

be presumed unlikely that the proposed action would have any lasting effects on Sargassum and its 

associated community. 

Summary and Conclusion 

Sargassum, as pelagic algae, is a widely distributed resource that is ubiquitous throughout the GOM 

and northwest Atlantic. Considering its ubiquitous distribution and occurrence in the upper water column 

near the sea surface, it would contact routine discharges from oil and gas operations. All types of 

discharges including drill muds and cuttings, produced water, and operational discharges (e.g., deck 

runoff, bilge water, sanitary effluent, etc.) would contact Sargassum algae. However, the quantity and 

volume of these discharges is relatively small compared with the pelagic waters of the CPA (268,922 km2

[103,831 mi2

]). Therefore, although discharges would contact Sargassum, they would only contact a very 

small portion of the Sargassum population. Because these discharges are highly regulated for toxicity and 

because they would continue to be diluted in the Gulf water, concentrations of any toxic components 

would be reduced; therefore, produced-water impacts on Sargassum would be minimum. Likewise, 

impingement effects by service vessels and working platforms and drillships would contact only a very 

small portion of the Sargassum population. The impacts to Sargassum that are associated with the 

proposed action are expected to have only minor effects to a small portion of the Sargassum community 

as a whole. The Sargassum community lives in pelagic waters with generally high water quality and 

would be resilient to the minor effects predicted. It has a yearly cycle that promotes quick recovery from 

impacts. No measurable impacts are expected to the overall population of the Sargassum community. 

4.1.1.8.3. Impacts of Accidental Events 

Proposed Action Analysis 

Impact-producing factors associated with accidental events for the CPA proposed action that could 

affect Sargassum and its associated communities include (1) surface oil and fuel spills and underwater 

well blowouts, (2) spill-response activities, and (3) chemical spills. These impacting factors would have 

varied effects depending on the intensity of the spill and the presence of Sargassum in the area of the 

spill. 

Oil spills are the major accidental events of concern to the Sargassum community. The risk of 

various sizes of oil spills occurring in the CPA is presented in Table 3-5. The possibility of a spill over 

10,000 bbl in the OCS of the CPA is estimated to be <1-1 spill, over the 40-year cycle for the proposed 
4-168 Central Planning Area Supplemental EIS 

action of the 5-Year Program. Up to two blowouts are estimated to occur in the same period (Table 3-3 

of the 2009-2012 Supplemental EIS). 

All known reserves in the GOM have specific gravity characteristics that indicate the oil will float to 

the sea surface. As discussed in Chapter 4.3.1.5.4 of the Multisale EIS, oil discharges that occur at the 

seafloor from a pipeline or loss of well control would rise in the water column, surfacing almost directly 

over the source location. Oil on the sea surface has the potential to negatively impact Sargassum

communities. While components of oil on the sea surface would be removed through evaporation, 

dissipation, biodegradation and oil-spill cleanup operations, much of it would persist until it contacts a 

shore. Oil at the sea surface can be mixed into the upper water column by wind and wave action to a 

depth of 10 m (33 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981a; Knap et al., 1985). With vigorous 

wave action, the oil can form an emulsion with water that is viscous and persistent. 

When dispersants are applied to oil on the sea surface or at depth, its behavior is modified, causing 

the oil to mix with water. The dispersed oil would be suspended in the water column and would begin to 

flocculate with particulate matter until it becomes heavy enough to sink to the seafloor. Oil treated with 

dispersant at depth may form underwater plumes that do not rise to the sea surface. Oil treated with 

dispersant on the sea surface mixes with the water where its contact with Sargassum may be temporarily 

increased in the upper few meters of the water column. Data from other studies on dispersant usage on 

surface plumes indicate that a majority of the dispersed oil remained in the top 10 m (33 ft) of the water 

column, with 60 percent of the oil in the top 2 m (6 ft) (McAuliffe et al., 1981a). As time passes, the oil 

begins to adhere to particles in the water column, form clumps, and sink toward the seafloor (ITOPF, 

2007; Kingston, 1995). 

The effects of oil contact with Sargassum communities will vary depending on the severity of 

exposure. Sargassum that contacts concentrated oil that coats the algae would likely succumb to the 

effects, die, and sink to the seafloor. Any attached organisms would suffer the same fate. Motile 

organisms that are dependent on the algae for habitat (shrimp, crabs, nudibranchs, snails, sargassum fish, 

etc.) may also be directly contacted by the oil or may be displaced into open water, resulting in death. 

Sargassum exposed to oil in lower concentrations may suffer sublethal effects. Levels of hydrocarbons, 

toxins, and chemicals in Sargassum from an accidental spill and spill cleanup may be concentrated up to 

four times that found in the adjacent waters (Burns and Teal, 1973). The effects of concentrated toxins on 

the macroalgae itself are undefined. It may result in the loss of associated organisms such as attached 

epifauna that use the algae as a substrate and other organisms that utilize the community as habitat 

including sea turtles, juvenile fish, and various invertebrates. Pelagic organisms feeding on the 

community may suffer sublethal effects that could reduce health and reproduction. 

A catastrophic spill could affect a sizable portion of the Sargassum population. Since Sargassum is 

ubiquitous in the northern GOM, the portion of the population affected would be similar to the portion of 

the surface waters affected. For example, if 10 percent of the surface waters of the northern GOM are 

affected by oil, about 10 percent of the Sargassum population at that time may come in contact with oil. 

However, a reliable estimate must also consider the annual cycle of Sargassum because density of the 

algae varies with season and across geographic locations. If the large spill occurs in an area of high or 

low Sargassum density, then a correspondingly higher or lower percent of the Sargassum population 

would be affected. Impacts from a catastrophic spill and cleanup effort could destroy a large enough 

portion of the population to affect subsequent populations in the Atlantic. The Sargassum community 

lives in pelagic waters with generally high water quality and is expected to show good resilience to the 

predicted effects of spills. It has a yearly cycle that promotes quick recovery from impacts. No 

measurable impacts are expected to the overall population of the Sargassum community unless a 

catastrophic spill occurs. 

Spill-response activities may contribute to negative impacts on Sargassum. The number of vessels 

working to clean a spill can increase physical damage to the Sargassum community, especially in the 

immediate vicinity of the spill. Vessels damage algae by cutting it with their propellers but impingement 

in cooling water intake is probably a larger effect. Vessels circulate seawater through shipboard systems 

as coolant. This can damage Sargassum directly; in addition, an antifoulant such as bleach or copper is 

typically injected to the water to prevent internal growth of organisms inside the systems. Other response 

activities, such as skimming oil from the sea surface, can also damage and remove Sargassum. However, 

these impacts may be inconsequential, as a large part of the Sargassum affected would already be 

contacted by oil. Another major response activity that may occur is the spraying of dispersant. Direct 
Description of the Environment and Impact Analysis 4-169 

effects of dispersant on the Sargassum community are unknown but dispersants are known to be toxic to 

some invertebrates. The use of dispersants is a trade-off to achieve the least overall damage. For 

example, dispersants may increase short-term contact of oil with Sargassum and may have some inherent 

toxic properties but their use can prevent the formation of persistent emulsions and promote diffusion of 

oil resulting in biodegradation, clumping, and sinking. 

Chemical spills are typically small (a few gallons to a few barrels of product) and are unlikely to 

produce any measurable impact on Sargassum communities. Due to the ubiquitous nature of Sargassum

over most of the GOM, such spills are negligible to the overall population. 

A spill may impact the productivity and longevity of Sargassum in an area. A very large spill may 

produce a measurable effect on the population of Sargassum in the Gulf of Mexico, reducing the overall 

biomass that is flushed into the Atlantic via the Loop Current and Gulf Stream. However, because of the 

nature of algal growth and the quality of the habitat under normal conditions, a more likely result is that 

local populations of Sargassum are affected that produce short-term measurable effects in the local area 

with rapid recovery. The Sargassum community is widely distributed over a very large area, including 

two oceans, and appears to have an annual cycle of growth that lends itself to resilient recovery in a short 

time. 

Summary and Conclusion 

Sargassum, as pelagic algae, is a widely distributed resource that is ubiquitous throughout the 

northern GOM and northwest Atlantic. Considering its ubiquitous distribution and occurrence in the 

upper water column near the sea surface, it would contact potential accidental spills from oil and gas 

operations. All types of spills including surface oil and fuel spills, underwater well blowouts, and 

chemical spills would contact Sargassum algae. The quantity and volume of most of these spills would 

be relatively small compared with the pelagic waters of the CPA (268,922 km2

 [103,831 mi2] of the 

CPA). Therefore, most spills would only contact a very small portion of the Sargassum population. The 

impacts to Sargassum that are associated with the proposed action are expected to have only minor effects 

to a small portion of the Sargassum community as a whole unless a catastrophic spill occurs. In the case 

of a very large spill, the Sargassum algae community could suffer severe impacts to a sizable portion of 

the population in the northern GOM. The Sargassum community lives in pelagic waters with generally 

high water quality and is expected to show good resilience to the predicted effects of spills. It has a 

yearly cycle that promotes quick recovery from impacts. No measurable impacts are expected to the 

overall population of the Sargassum community unless a catastrophic spill occurs. 

4.1.1.8.4. Cumulative Impacts 

Pelagic Sargassum algae is an unusual habitat found in the GOM and western Atlantic. It is 

comprised of floating mats of macroalgae that lives on the surface and upper water column of the sea, 

along with a varied community of organisms that inhabit it. It also supports a transient community of 

pelagic fish that take refuge and/or forage in the habitat. See Chapter 4.1.1.8.1 for a description of 

Sargassum habitat. Several impacting factors can affect Sargassum, including impingement by structures 

and marine vessels, oil and gas drilling discharges, operational discharges, accidental spills, hurricanes, 

and coastal water quality. 

Pelagic Sargassum floats at the surface in oceanic waters and is carried by surface currents across the 

GOM. Vessels transiting the Gulf pass through Sargassum mats, producing slight impacts to the 

Sargassum community by their passage, some propeller impacts, and possible impingement on cooling 

water intakes. None of these would have more than minor localized effects to the mats transited. Oil and 

gas structures can impede the movement of Sargassum mats and may entrap small quantities of the algae. 

This is expected to be a minor impact with no consequences to the overall Sargassum community. 

Oil and gas drilling results in discharges of drill cuttings with small quantities of associated drilling 

muds and well treatment chemicals. Most cuttings from well drilling are discharged from the drill 

platform at the sea surface. This creates an area of high turbidity in the vicinity of drill operations. Small 

quantities of drill muds adhere to the cuttings that are discharged. Well treatment chemicals accompany 

muds into the well and may be discharged in small quantities with the cuttings. The composition of muds 

is strictly regulated and discharges of cuttings/muds are tested to ensure that toxicity levels are below the 

limits allowed by NPDES permits (USEPA, 2004a, 2007d, and 2009a). Cuttings discharged at the sea 
4-170 Central Planning Area Supplemental EIS 

surface may spread out to 1,000 m (3,280 ft) from the source, depending on currents, with the thickest 

layers at the well and the majority of the sediment within 250 m (820 ft) (CSA, 2006a; Kennicutt et al., 

1996). Fine components of the plume may travel farther but are dispersed in the water column and are 

distributed widely at low concentrations (CSA, 2004b; NRC, 1983). Contaminants from produced waters 

are reported in benthic environments up to 1,000 m (3,280 ft) from the source (Peterson et al., 1996; 

Armstrong et al., 1977; Osenberg et al., 1992). Floating mats of Sargassum that pass by a drilling 

operation would experience short-term exposure to drill cuttings with associated muds and well treatment 

chemicals. This may cause temporary stress to organisms including changes in respiration rate, abrasion, 

reduced feeding, reduced water filtration rates, and reduced response to physical stimulus (Anchor 

Environmental CA, L.P., 2003). These effects would be localized to a small portion of the total 

Sargassum population and represent a negligible amount of the incremental impact to Sargassum

communities. 

Marine vessels of all types produce at least some minor effects to the environment. Oil and gas 

platforms and drill ships produce similar effects. Runoff water from the decks of ships and platforms may 

contain small quantities of oil, metals, and other contaminants. Larger vessels and offshore platforms 

discharge effluents from sanitary facilities (gray water). They also circulate seawater to cool ship’s 

engines, electric generators, and other machines. The cooling water discharge may be up to 11o

C (20oF) 

warmer than the surrounding sea water (USDOT, CG, 2003; Patrick et al., 1993). This temperature 

difference can accumulate in the vicinity of the discharge. For ships this would only occur when the 

vessel is stationary, as in port. For oil and gas platforms and drill ships and for offshore Liquid Natural 

Gas terminals, localized warming of the water could occur (Emery et al., 1997; USDOT, CG, 2003). 

However, the warm water is rapidly diluted, mixing to background temperature levels within 100 m 

(328 ft) of the source (USDOT, CG, 2003). Effects from gray water, deck runoff, and cooling water are 

only notable for stationary locations. Produced waters from stationary locations are rapidly diluted and 

impacts are only observed within 100 m (328 ft) of the discharge point (Neff and Sauer, 1991; Trefry et 

al., 1995; Gittings et al., 1992b). Those effects are very localized, with only brief contact to passing 

Sargassum before dilution to background levels. These effects would comprise a negligible portion of the 

overall cumulative impact to Sargassum communities. 

Accidental spills of oil and other chemicals could affect Sargassum and its community wherever they 

contact the algae. Small spills would have a limited local effect on a small portion of the Sargassum

community. Short-term exposure of passing Sargassum to high concentrations of oil and chemicals could 

result in death and sinking of algae and organisms contacted. The size of the overall effect on Sargassum

would depend on the size of the spill and the success of spill-response efforts. A catastrophic spill such as 

the DWH event could have noticeable impacts to the overall Sargassum community. These impacts could 

destroy a sizable portion of Sargassum habitat wherever the surface slick of oil travels. The effects could 

reduce the supply of algae transiting from the GOM to the Atlantic. This effect, although large, would 

contact only a portion of the algae in the region of the spill. Sargassum algae is a widespread habitat with 

patchy distribution across the northern GOM and the western Atlantic. Due to the vegetative production 

of Sargassum algae, the community would likely recover within 1-2 seasons (1-2 years). The probability 

of occurrence of a catastrophic spill is very low. If such a spill does occur, it would account for a sizable 

portion of the cumulative impact that affects Sargassum, although even such an impact would affect only 

a portion of the Sargassum in one region of its occurrence. 

Hurricanes are major natural impacts that affect the Sargassum community. The violent surface 

turbulence of these storms would dislocate many of the organisms living on and in the Sargassum. Some 

of the organisms (those that cannot swim or swim only weakly) such as nudibranchs (sea slugs), shrimp, 

sargassum fish (Histrio histrio), and pipefish (Syngnathus spp.) would become separated from the algae. 

Without cover, many would fall prey to larger fish after the storm; others may sink to the seafloor and die. 

Some epifauna, such as hydroids, living on the algae may suffer physical damage or be broken off. In 

addition, hurricanes drive large quantities of Sargassum toward shore, into coastal waters having less 

conducive conditions for Sargassum and even stranding large quantities on shore. Although hurricanes 

offer major physical damage to Sargassum communities, these are natural events for which the 

Sargassum is adapted. The general high quality of the pelagic habitat supports a thriving Sargassum

algae community that can be expected to maintain high resilience, giving it a strong ability to recover 

from detrimental impacts. Although hurricanes cause widespread physical damage to the Sargassum

community seasonally, the habitat routinely recovers from these stresses. Hurricane impacts may be a 
Description of the Environment and Impact Analysis 4-171 

large part of the cumulative impacts to Sargassum, but they are a part of the normal cycle for the 

community. 

Coastal water conditions are normally of lower quality than those found farther offshore in pelagic 

waters. Sargassum mats are often driven toward shore by onshore winds. Some is stranded on coastal 

barrier islands and beaches. Water quality conditions nearshore are different than the pelagic 

environment, with much higher turbidity, higher nutrients, and higher levels of contaminants. These 

conditions can be expected to cause stress to the algae and its inhabitants as they suffer from clogging of 

gills and filter mechanisms and lower light conditions. Increased coastal urbanization contributes to 

lower water quality in coastal waters, particularly near the outlets of rivers. This loss of Sargassum to 

shoreward movement is a normal part of community dynamics, although the effects may be exacerbated 

by increased declines in coastal water quality. As with hurricanes, loss of Sargassum to the coastal 

environment contributes to cumulative impacts for the overall community in the GOM. 

Summary and Conclusion 

A broad Internet search for relevant new information, as well as a search for scientific journal articles, 

was conducted using a publicly available search engine. In addition, the websites for Federal and State 

agencies, as well as other organizations were reviewed for newly released information. Sources 

investigated include the South Atlantic Fishery Management Council, coordinated communications with 

the Gulf of Mexico Alliance, USEPA, USGS, and coastal universities. Interviews with personnel from 

academic institutions and governmental resource agencies were conducted to determine the availability of 

new information. In addition, there are ongoing NOAA- and National Science Foundation-funded 

research projects that are investigating the Sargassum distribution and impacts from the DWH event. 

Because of the ephemeral nature of Sargassum communities, many activities associated with the proposed 

action would have a localized and short-term effect. There is also a low probability of a catastrophic spill 

to occur with the CPA proposed action. The incremental contribution of the proposed action to the 

overall cumulative impacts on Sargassum communities that would result from the OCS Program, 

environmental factors, and non-OCS related user group activities are expected to be minimal. 

4.1.1.9. Chemosynthetic Deepwater Benthic Communities 

The BOEMRE has reexamined the analysis for chemosynthetic deepwater benthic communities 

presented in the Multisale EIS and the 2009-2012 Supplemental EIS based on the additional information 

presented below and in consideration of the DWH event. No substantial new information was found that 

would alter the impact conclusion for this resource presented in the Multisale EIS and the 2009-2012 

Supplemental EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A brief summary of potential impacts follows. Chemosynthetic 

communities are susceptible to physical impacts from structure placement, anchoring, and pipeline 

installation associated with the CPA proposed action; however, the guidance provided in NTL 2009-G40 

greatly reduces the risk of these physical impacts by requiring avoidance of potential chemosynthetic 

communities and by consequence avoidance of other hard-bottom communities. Even in situations where 

the substantial burial of typical benthic infaunal communities occurred, recolonization from populations 

from widespread neighboring soft-bottom substrate would be expected over a relatively short period of 

time for all size ranges of organisms. Potential accidental events associated with the CPA proposed 

action are expected to cause little damage to the ecological function or biological productivity of the 

widespread, low-density chemosynthetic communities and the widespread, typical, deep-sea, soft-bottom 

communities. The most serious, cumulative, impact-producing factor threatening chemosynthetic 

communities is physical disturbance of the seafloor by OCS activities, which could destroy the organisms 

of these communities. The incremental contribution of the proposed action to the cumulative impacts is 

expected to be slight, and adverse impacts would be limited but not completely eliminated by adherence 

to NTL 2009-G40. 
4-172 Central Planning Area Supplemental EIS 

4.1.1.9.1. Description of the Affected Environment 

A detailed description of the continental slope and deepwater resources can be found in Chapter 

3.2.2.2 of the Multisale EIS. Additional information for the 181 South Area and any new information 

since the publication of the Multisale EIS is presented in Chapter 4.1.5.1 of the 2009-2012 Supplemental 

EIS. The following information is a summary of the resource description incorporated from the Multisale 

EIS and the Supplemental EIS, and new information that has become available since both documents 

were prepared. 

Continental Slope and Deepwater Resources 

The northern GOM is a geologically complex basin. It has been described as the most complex 

continental slope region in the world (Carney, 1997 and 1999; Rowe and Kennicutt, 2009). Regional 

topography of the slope consists of basins, knolls, ridges, and mounds derived from the dynamic 

adjustments of salt to the introduction of large volumes of sediment over long time scales. This region 

has become much better known in the last three decades, and the existing information is considerable, 

both from a geological and biological perspective. The first substantial collections of deep GOM benthos 

were made during the cruises of the USCG and Geodetic Steamer, Blake, between 1877 and 1880. Rowe 

and Menzel (1971) reported that their deep GOM infauna data were the first quantitative data published 

for this region. The first major study of the deep northern GOM was performed by a variety of 

researchers from Texas A&M University between 1964 and 1973 (Pequegnat, 1983). A total of 157 

stations were sampled and photographed between depths of 300 and 3,800 m (984 and 12,467 ft) (the 

deepest part of the GOM). A more recent Agency-funded study was completed by LGL Ecological 

Research Associates, Inc. and Texas A&M University in 1988, during which a total of 60 slope stations 

were sampled throughout the northern GOM in water depths between 300 and 3,000 m (9,842 ft) 

(Gallaway et al., 1988). As part of this multiyear study, along with trawls and quantitative box-core 

samples, 48,000 photographic images were collected and a large subset was quantitatively analyzed. 

Another major study, titled Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology 

Study, was completed in 2009. This 6-year project spanned three field sampling years and included 

collections of benthos and sediments through trawling, box coring and bottom photography at a total of 

51 stations ranging in depth from 213 to 3,732 m (699 to 12,244 ft), including some stations in Mexican 

waters (Rowe and Kennicutt, 2009). 

“Deepwater” is a term of convenience referring (in this use) to vast areas of the Gulf with water 

depths ≥300 m (984 ft) that are typically covered by pelagic clay and silt. In, on, and directly above these 

sediments live a wide variety of single-celled organisms, invertebrates, and fish. Their lifestyles are 

extremely varied and can include absorption of dissolved organic material, symbiosis, collection of food 

through filtering, mucous webs, seizing, or other mechanisms including chemosynthesis. Chemosynthetic 

communities are a remarkable assemblage of invertebrates found in association with hydrocarbon seeps. 

The seeps provide a source of carbon independent of photosynthesis and the sun-dependent 

photosynthetic food chain that supports all other life on earth. 

The continental slope is a transitional environment influenced by processes of both the shelf (<200 m; 

650 ft) and the abyssal GOM (>975 m; 3,199 ft). This transitional character applies to both the pelagic 

and the benthic realms. The highest values of surface primary production are found in the upwelling 

areas in the De Soto Canyon region. In general, the eastern GOM is more productive in the oceanic 

region than is the western GOM. It is generally assumed that all the phytoplankton is consumed by the 

zooplankton, except for brief periods during major plankton blooms. The zooplankton then egests a high 

percentage of their food intake as feces that sink toward the bottom. 

Deepwater fauna can be grouped into major assemblages defined by depth, including (1) upper slope, 

(2) mid-slope, (3) lower slope, and (4) abyssal plain (Rowe and Kennicutt, 2009). The 450-m (1,476-ft) 

isobath defines the truly deep-sea fauna where the aphotic zone begins at and beyond these depths. In 

these sunlight-deprived waters, photosynthesis cannot occur and processes of food consumption, 

biological decomposition, and nutrient regeneration occur in cold and dark waters. The lowermost layer 

containing the last meter of water above the bottom and the bottom itself constitutes the benthic zone. 

This zone is a repository of sediments where nutrient storage and regeneration take place in association 

with the solid and semisolid substrate (Pequegnat, 1983). The seven zones previously described by 
Description of the Environment and Impact Analysis 4-173 

Pequegnat (1983) and confirmed by LGL Ecological Research Associates, Inc. and Texas A&M 

University (Gallaway et al., 1988) now appear to be too numerous. 

Similar to the continental slope in general, the CPA proposed action area encompasses a vast range of 

habitats and water depths. The shallowest portions start nearshore at the boundary of State waters and the 

deepest portions extend nearly into the deepest part of the GOM at approximately 3,500 m (11,483 ft) 

south of the Sigsbee Escarpment in the Central Gulf. This is not particularly deep for the rest of the 

world’s oceans, but it is within a few hundred meters of the deepest point of the GOM at 3,840 m (12,467 

ft) and is only accessible from Mexican waters of the southern Gulf. The proposed lease sale area also 

includes the lower portions of De Soto Canyon, the most notable sea-bottom feature on the upper slope in 

this area. Its formation has been attributed to a combination of erosion, deposition, and structural control 

of salt diapirs clustered in the vicinity (Harbison, 1968). Although the northeastern edge of the canyon 

has a steep slope, unlike most submarine canyons, De Soto Canyon has a comparatively gentle gradient; 

however, it does have significant impact on current structure, upwelling features, and resulting increases 

in biological productivity. 

A great number of publications have been derived from the two major Agency-funded deep Gulf 

studies of Gallaway et al. (1988) and Rowe and Kennicutt (2009). These two studies provide extensive 

background information on deepwater GOM habitat and biological communities. 

The vast majority of the Gulf of Mexico seabed is comprised of soft sediments. Major groups of 

animals that live in this habitat include the following: (1) bacteria and other microbenthos; (2) meiofauna 

(0.063-0.3 mm); (3) macrofauna (>0.3 mm); and (4) megafauna (larger organisms such as crabs, sea pens, 

sea cucumbers, crinoids, and bottom-dwelling [demersal] fish). All of these groups are represented 

throughout the entire Gulf − from the continental shelf to the deepest abyssal depths. 

The continental slope and the abyssal zone (≥1,000 m; 3,281 ft) have the following divisions and 

characteristic faunal assemblages: 

 Shelf-Slope Transition Zone (150-450 m; 492-1,476 ft)—A very productive part of 

the benthic environment. Demersal fish are dominant, many reaching their maximum 

populations in this zone. Asteroids, gastropods, and polychaetes are common. 

 Archibenthal Zone—Horizon A (475-740 m; 1,558-2,428 ft)—The Horizon A 

Assemblage is located between 475 and 740 m. Although less abundant, the 

demersal fish are a major constituent of the fauna, as are gastropods and polychaetes. 

Sea cucumbers are more numerous. 

 Archibenthal Zone—Horizon B (775-950 m; 2,543-3,117 ft)—The Horizon B 

Assemblage, located at 775-950 m, represents a major change in the number of 

species of demersal fish, asteroids, and echinoids, which reach maximum populations 

here. Gastropods and polychaetes are still numerous. 

 Upper Abyssal Zone (1,000-2,000 m; 3,281-6,562 ft)—Number of fish species 

decline while the number of invertebrate species appear to increase; sea cucumbers, 

Mesothuria lactea and Benthodytes sanguinolenta, are common; galatheid crabs 

include 12 species of the deep-sea genera Munida and Munidopsis, while the shallow 

brachyuran crabs decline. 

 Mesoabyssal Zone (2,300-3,000 m; 7,546-9,843 ft)—Fish species are few, and 

echinoderms continue to dominate the megafauna. 

 Lower Abyssal Zone (3,200-3,800 m; 10,499 to 12,468 ft)—Large asteroid, Dynaster 

insignis, is the most common megafaunal species. 

Megafauna: Animals of a size typically caught in trawls and large enough to be easily visible (e.g., 

crabs, shrimp, benthic fish, etc.) are called megafauna. In the Gulf, most are crustaceans, echinoderms, or 

benthic fish. Benthic megafaunal communities in the deep Gulf appear to be typical of most temperate 

continental slope assemblages found at depths from 300 to 3,000 m (984 to 9,843 ft) (USDOI, MMS, 

2001a, p. 3-63). Exceptions include the chemosynthetic communities. Although soft-bottom fauna are 
4-174 Central Planning Area Supplemental EIS 

expected to predominate, occasional sea pens, sea whips, and sponges are observed during ROV surveys 

(Geoscience Earth & Marine Services, Inc., 2005). 

Megafaunal invertebrate and benthic fish densities appear to decline with depth between the upper 

slope and the abyssal plain (Pequegnat 1983; Pequegnat et al., 1990). This phenomenon is generally 

believed to be related to the low productivity in deep, offshore Gulf waters (USDOI, MMS, 2001a, 

p. 3-60). Megafaunal communities in the offshore Gulf have historically been zoned by depth (see 

above), which are typified by certain species assemblages (Menzies et al., 1973; Pequegnat, 1983; 

Gallaway et al., 1988; Gallaway and Kennicutt, 1988; Pequegnat et al., 1990; USDOI, MMS, 2001a, 

p. 3-64). 

Carney et al. (1983) postulated a simpler system of zonation having three zones: (1) a distinct shelf 

fauna in the upper 1,000 m (3,281 ft); (2) indistinct slope fauna between 1,000 and 2,000 m (3,281 and 

6,562 ft); and (3) a distinct abyssal fauna between 2,000 and 3,000 m (6,562 and 9,843 ft). 

The baseline Northern Gulf of Mexico Continental Slope (NGMCS) Study conducted in the mid- to 

late 1980’s trawled 5,751 individual fish and 33,695 invertebrates, representing 153 and 538 taxa, 

respectively. That study also collected 56,052 photographic observations, which included 76 fish taxa 

and 193 non-fish taxa. The photographic observations were dominated by sea cucumbers, bivalves, and 

sea pens, groups that were not sampled effectively (if at all) by trawling. Decapod crustaceans dominated 

the trawls and were fourth in abundance in photos. Decapod density generally decreased with depth but 

abundance peaks were determined at 500 m (1,640 ft) and between 1,100 and 1,200 m (3,609 and 

3,937 ft), beyond which numbers diminished. Fish density, while variable, was generally high at depths 

between 300 and 1,200 m (984 and 3,937 ft); it then declined substantially. 

Gallaway et al. (2003) concluded that megafaunal composition changes continually with depth such 

that a distinct upper slope fauna penetrates to depths of about 1,200 m (3,937 ft) and a distinct deep-slope 

fauna is present below 2,500 m (8,202 ft). A broad transition zone characterized by low abundance and 

diversity occurs between depths of 1,200 and 2,500 m (3,937 and 8,203 ft). 

Macrofauna: The benthic macrofaunal component of the NGMCS Study (Gallaway et al., 2003) 

included sampling in nearby areas at similar depths, both east and west of the proposed action. The study 

NGMCS examined 69,933 individual macrofauna from over 1,548 taxa; 1,107 species from 46 major 

groups were identified (Gallaway et al., 2003). Polychaetes (407 species), mostly deposit-feeding forms 

(196 taxa), dominated in terms of numbers. Carnivorous polychaetes were more diverse, but less 

numerous than deposit-feeders, omnivores, or scavengers (Pequegnat et al., 1990; Gallaway et al., 2003). 

Polychaetes were followed in abundance by nematodes, ostracods, harpacticoid copepods, bivalves, 

tanaidacids, bryozoans, isopods, amphipods, and others. Overall abundance of macrofauna ranged from 

518-5,369 individuals/m2

 (Gallaway et al., 1988). The central transect (4,938 individuals/m2) had higher 

macrofaunal abundance than either the eastern or western Gulf transects (4,869 and 3,389 individuals/m2

, 

respectively) (Gallaway et al., 2003). 

In the GOM, macrofaunal density and biomass declines with depth from approximately 5,000 

individuals/m2

 on the lower shelf-upper slope to several hundred individuals/m2 on the abyssal plain 

(USDOI, MMS, 2001a, p. 3-64). This decline in benthos has been attributed to the relatively low 

productivity of the Gulf offshore open waters (USDOI, MMS, 2001a, p. 3-60). Pequegnat et al. (1990) 

reported mid-depth maxima of macrofauna in the upper slope at some locations with high organic 

particulate matter, and Gallaway et al. (2003) noted that the decline with depth is not clear cut and is 

somewhat obscured by sampling artifacts. There is some suggestion that the size of individuals decrease 

with depth (Gallaway et al., 2003). 

Meiofauna: Meiofauna primarily composed of small nematode worms, as with megafauna and 

macrofauna, also decline in abundance with depth (Pequegnat et al., 1990; USDOI, MMS, 2001a, p. 3-64; 

Gallaway et al., 2003). The overall density (mean of 707,000/m2

) of meiofauna is approximately two 

orders of magnitude greater than the macrofauna throughout the depth range of the slope (Gallaway et al., 

1988). These authors reported 43 major groups of meiofauna with nematodes, harpacticoid copepods 

(adults and larvae), polychaete worms, ostracods, and kinorhynchs accounting for 98 percent of the total 

numbers. Nematode worms and harpacticoids were dominant in terms of numbers, but polychaetes and 

ostracods were dominant in terms of biomass, a feature that was remarkably consistent across all stations, 

regions, seasons, and years (Gallaway et al., 2003). Meiofaunal densities appeared to be somewhat higher 

in the spring than in the fall. Meiofaunal densities reported in the NGMCS Study are among the highest 

recorded worldwide (Gallaway et al., 2003). There is also evidence that the presence of chemosynthetic 
Description of the Environment and Impact Analysis 4-175 

communities may enrich the density and diversity of meiofauna in the immediate surrounding area 

(Gallaway et al., 2003). 

Microbiota: Less is known about the microbiota in the GOM than the other size groups, especially in 

deep water (CSA, 2000; USDOI, MMS, 2000, p. IV-15). While direct counts have been coupled with 

some in situ and repressurized metabolic studies performed in other deep ocean sediments (Deming and 

Baross, 1993), none have been made in the deep GOM. Cruz-Kaegi (1998) made direct counts using a 

fluorescing nuclear stain at several depths down the slope, allowing bacterial biomass to be estimated 

from their densities and sizes. Mean biomass was estimated to be 2.37 g of carbon/m2

 for the shelf and 

slope combined, and 0.37 g of carbon/m2

 for the abyssal plain. In terms of biomass, data indicate that 

bacteria are the most important component of the functional infaunal biota. Cruz-Kaegi (1998) developed 

a carbon cycling budget based on estimates of biomass and metabolic rates in the literature. She 

discovered that, on the deep slope of the Gulf, the energy from organic carbon in the benthos is cycled 

through bacteria. 

Deepwater Horizon Event 

The DWH event released an estimated 4.9 million bbl of oil into the water over a period of 87 days. 

Extensive literature, Internet, and database searches have been conducted for results of scientific data. 

Although many research cruises have occurred, very few scientific results have been published as of this 

writing. Descriptions of studies completed or in progress are discussed and available results are included. 

Although the impacts of the oil spill are not yet known, possible impacts to deepwater benthic 

communities are discussed. 

Several opposing forces dictated the behavior of the oil from the DWH event. The oil was lighter 

than water and a portion of it was buoyed to the sea surface. However, it was injected into deep water 

under high pressure, which resulted in vigorous turbulence and the formation of micro-droplets that were 

not buoyant enough to float rapidly to the surface. The upward movement of the oil was also reduced 

because methane in the oil was dissolved at high underwater pressures, reducing the oil’s buoyancy 

(Adcroft et al., 2010). The Joint Analysis Group (2010a) reported that oil droplets less than 100 μm in 

diameter were likely to remain in the water column for several months. Much of the oil was treated with 

dispersant at the sea surface and at the source in 1,500 m (5,000 ft) of water depth. It is reported that 

chemically dispersed surface oil from the DWH event remained in the top 6 m (20 ft) of the water column 

where it mixed with surrounding waters and biodegraded (Lubchenco et al., 2010). Data from other 

studies on dispersant usage on surface plumes indicate that a majority of the dispersed oil remained in the 

top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (7 ft) (McAuliffe et al., 

1981a). Any dispersed oil that reached the seafloor from the water’s surface during this event would be 

expected to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a). Dispersant usage also 

reduces the oil’s ability to adhere to particles in the water column, delaying flocculation and sinking to the 

seafloor (McAuliffe et al., 1981a). Oil exposed to dispersant chemicals became more dispersed and less 

concentrated the longer it remained floating or suspended in the water column. These oil droplets 

remained neutrally buoyant in the water column, creating a subsurface plume of oil (Adcroft et al., 2010). 

Concentrations of dispersed and dissolved oil in the subsea plume were reported to be in the part per 

million range or less and were generally lower away from the water’s surface and away from the wellhead 

(Adcroft et al., 2010; Haddad and Murawski, 2010; Joint Analysis Group, 2010a; Lubchenco et al., 2010). 

Depending on how long it remained in the water column, it may have been thoroughly degraded by 

biological action before contact with the seafloor. Water currents could have carried a plume to contact 

the seafloor directly but a likely scenario would be for the oil to adhere to other particles and precipitate 

to the seafloor, much like rainfall (Kingston, 1995; ITOPF, 2007). Oil also would have reached the 

seafloor through consumption by plankton with excretion distributed over the seafloor (ITOPF, 2007). 

Distribution of the dispersed oil was dictated by water currents and the physical processes of dispersion 

and degradation. These mechanisms would result in a wide distribution of small amounts of oil. This oil 

would be in the process of biodegradation from bacterial action, which would continue on the seafloor, 

resulting in scattered microhabitats with an enriched carbon environment (Hazen et al., 2010). 

Lubchenco et al. (2010) estimated that 26 percent of the total spill volume remained at large in the 

GOM shortly after the Macondo well was capped on July 16, 2010, and at least some portion of that has 

probably settled onto the GOM deepwater seafloor. The majority of the seafloor of the Gulf of Mexico is 
4-176 Central Planning Area Supplemental EIS 

covered in soft sediments. Oil released from the DWH event may have affected some of the organisms 

that live on or in these sediments. Direct contact with high concentrations of oil may have resulted in 

acute toxicity to organisms. Exposures to lower concentrations may have resulted in sublethal impacts 

such as altered reproduction, growth, respiration, excretion, chemoreception, feeding, movement, 

stimulus response, and susceptibility to disease (Suchanek, 1993). It is important to note that the effects 

of oil exposure on soft-bottom benthos are anticipated to have only impacted a relatively small portion of 

the seafloor of the Gulf of Mexico. The greatest concentrations are expected to be near the wellhead and 

to decrease with distance from the source. In situations where soft-bottom infaunal communities were 

negatively impacted, recolonization by populations from neighboring soft-bottom substrate would be 

expected over a relatively short period of time for all size ranges of organisms, i.e., a matter of days for 

bacteria and probably less than 1 year for most macrofauna and megafauna species (Lu and Wu, 2006; 

Netto et al., 2009; Santos et al., 2009). This could take longer for areas affected by direct oil contact in 

higher concentrations. 

A recent report documents damage to a deepwater coral community in an area that oil plume models 

predict as the direction of travel for subsea oil plumes the from DWH event. Results are still pending but 

it appears that a coral community about 15 m x 40 m (50 ft x 130 ft) in size was severely damaged, 

possibly the result of oil impacts (USDOI, BOEMRE, 2010j). A major difference between this 

occurrence and likely effects on soft bottoms is that the coral community forms structures that protrude up 

into the water column. These upright corals would be affected by a passing oil plume in a way that a 

typical smooth soft bottom would not. The oil plume would pass over smooth soft bottom, continuing the 

process of biodegradation in mid-water and continuing to be dispersed over a wide area. 

As of this writing, there are no data on the concentrations of hydrocarbons in sediments or on benthic 

community structure on the seafloor of the Gulf of Mexico after this event. There are, however, a few 

data available on hydrocarbons and dissolved oxygen levels in the water column. Water column data may 

be used to speculate the exposures benthic organisms may have experienced. 

The hydrocarbon concentrations in the water column and subsea plume were close to, and below, the 

values reported by others for dispersed oil in the water column after oil spills. McAuliffe et al. (1981a) 

reported dispersed oil concentrations between 1 and 3 ppm at 9 m (30 ft) below the sea surface and 1 hour 

after treatment with dispersant. Lewis and Aurand (1997) reported dispersed oil concentrations <1 ppm 

at 10 m (33 ft) below the sea surface. Although McAuliffe et al. (1981a) and Lewis and Aurand (1997) 

did not address subsea plumes, the oil concentrations in the subsea plume appear to be similar to the 

concentrations reported from surface use of dispersants (Adcroft et al., 2010; Joint Analysis Group, 

2010a; Lubchenco et al., 2010). 

Water samples collected by the R/V Weatherbird on May 23-26, 2010, located 40 nmi (46 mi; 74 km) 

and 45 nmi (52 mi; 83 km) northeast and 142 nmi (163 mi, 263 km) southeast of the Deepwater Horizon

rig revealed that concentrations of total petroleum hydrocarbons in the water column were less than 

0.5 ppm (Haddad and Murawski, 2010). Concentrations of dispersed and dissolved oil in the subsea 

plume were reported to be in the part per million range or less and to decrease with distance from the 

wellhead (Adcroft et al., 2010; Joint Analysis Group, 2010a; Lubchenco et al., 2010). The available data 

suggest that the concentrations of oil in the water column were low and the oil was dispersed. These data 

suggest that, if any benthic organisms at the sediment/water interface were exposed to oil as a result of the 

DWH event, the concentrations were very low (in the part per million range or less). 

Surveys performed by Camilli et al. (2010) delineated an underwater oil plume to the west-southwest 

of the DWH event site, a plume that extended over 35 km (22 mi) and concentrated at a depth of 1,100 m 

(3,600 ft). The plume was up to 200 m (650 ft) high and over 2 km (1.2 mi) wide in some areas. It was 

being moved by a water current at a depth of 1,100 m (3,600 ft), with an average speed of 7.8 cm s-1

(0.26 ft s-1). Camilli et al. measured monoaromatic petroleum hydrocarbon concentrations in excess of 

50 μg L-1 (>5 ppm) within the plume. 

Joye (2010) reports observation of seafloor conditions that appear to be sedimented oil in the area 

around the DWH event site (Harris, 2010). The report suggests extensive oil deposition based on the 

color of the upper sediments in seafloor cores. While this observation may have some merit, lab analyses 

for verification are pending. The visual appearance and coloration of Joye’s cores are similar to typical 

cores of the seafloor in this area. Underwater currents are directional, making it unlikely that oil would be 

distributed in all directions around the well site. 
Description of the Environment and Impact Analysis 4-177 

Chemosynthetic Communities 

A detailed description of the chemosynthetic communities can be found in Chapter 3.2.2.2.1 of the 

Multisale EIS. Additional information about chemosynthetic communities for the 181 South Area and 

any new information since the publication of the Multisale EIS is presented in Chapter 4.1.5.1.1 of the 

2009-2012 Supplemental EIS. The following information is a summary of the resource description 

incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

Chemosynthetic communities are remarkable in that they utilize a carbon source independent of 

photosynthesis and the sun-dependent photosynthetic food chain that supports all other life on earth. 

Although the process of chemosynthesis is entirely microbial, chemosynthetic bacteria can support 

thriving assemblages of higher organisms. This is accomplished through symbiotic relationships in which 

the chemosynthetic bacteria live within the tissues of tube worms and bivalves and provide a food source 

for their hosts. The first discovery of deep-sea chemosynthetic communities including higher animals 

was unexpectedly made at hydrothermal vents in the eastern Pacific Ocean during geological explorations 

(Corliss et al., 1979). The principal organisms included tube worms, clams, and mussels that derive their 

entire food supply from symbiotic chemosynthetic bacteria, which obtain their energy needs from 

chemical compounds in the venting fluids. Similar communities were first discovered in the eastern Gulf 

of Mexico in 1983 at the bottom of the Florida Escarpment in areas of “cold” brine seepage (Paull et al., 

1984). The fauna here was found to be generally similar to vent communities including tube worms, 

mussels, and rarely, vesicomyid clams. 

Two groups fortuitously discovered chemosynthetic communities in the Gulf of Mexico concurrently 

in November 1984. During investigations by Texas A&M University to determine the effects of oil 

seepage on benthic ecology (until this investigation, all effects of oil seepage were assumed to be 

detrimental), bottom trawls unexpectedly recovered extensive collections of chemosynthetic organisms 

including tube worms and clams (Kennicutt et al., 1985). At the same time, LGL Ecological Research 

Associates, Inc. was conducting a research cruise as part of the Agency-funded, multiyear Northern Gulf 

of Mexico Continental Slope Study (LGL Ecological Research Associates, Inc. and Texas A&M 

University, 1986). Bottom photography resulted in clear images of vesicomyid clam chemosynthetic 

communities. Photography during the same LGL cruise also documented tube-worm communities in situ 

in the Gulf of Mexico for the first time (Boland, 1986) prior to the initial submersible investigations and 

firsthand descriptions of Bush Hill in 1986 (Rosman et al., 1987; MacDonald et al., 1989). 

Distribution 

There is a clear relationship between known hydrocarbon discoveries at great depth in the Gulf slope 

and chemosynthetic communities, hydrocarbon seepage, and authigenic minerals, including carbonates at 

the seafloor (Sassen et al., 1993a and 1993b). Chemosynthetic bacteria form living mats at seep sites and 

precipitate carbonates. While the hydrocarbon reservoirs are broad areas several kilometers beneath the 

Gulf, chemosynthetic communities occur in isolated areas with thin veneers of sediment only a few 

meters thick. 

The northern Gulf of Mexico slope includes a stratigraphic section more than 10 km (6 mi) thick that 

has been profoundly influenced by salt movement. Mesozoic source rocks from Upper Jurassic to Upper 

Cretaceous generate oil in most of the Gulf slope fields (Sassen et al., 1993a and 1993b). Migration 

conduits supply fresh hydrocarbon materials through a vertical scale of 6-8 km (4-5 mi) toward the 

surface. The surface expressions of hydrocarbon migration are referred to as seeps. Geological evidence 

demonstrates that hydrocarbon and brine seepage persists in spatially discrete areas for thousands of 

years. The time scale for oil and gas migration (combination of buoyancy and pressure) from source 

systems is on the scale of millions of years (Sassen, 1998). Seepage from hydrocarbon sources through 

faults towards the surface tends to be diffused through the overlying sediment, carbonate outcroppings, 

and hydrate deposits so the corresponding hydrocarbon seep communities tend to be larger (a few 

hundred meters wide) than chemosynthetic communities found around the hydrothermal vents of the 

Eastern Pacific (MacDonald, 1992). There are large differences in the concentrations of hydrocarbons at 

seep sites. 

The widespread nature of Gulf of Mexico chemosynthetic communities was first documented during 

contracted investigations by the Geological and Environmental Research Group (GERG) of Texas A&M 
4-178 Central Planning Area Supplemental EIS 

University for the Offshore Operators Committee (Brooks et al., 1986). The occurrence of 

chemosynthetic organisms dependent on hydrocarbon seepage has been documented in water depths as 

shallow as 290 m (951 ft) (Roberts et al., 1990) and as deep as 2,200 m (7,218 ft) (MacDonald, 1992). 

This depth range specifically places chemosynthetic communities in the deepwater region of the Gulf of 

Mexico, which is defined as water depths greater than 300 m (984 ft). Chemosynthetic communities are 

not found on the continental shelf. At least 69 communities are now known to exist in the Gulf (Figure 

4-12). Although a systematic survey has not been done to identify all chemosynthetic communities in the 

Gulf, there is evidence indicating that many more such communities may exist. The depth limits of 

discoveries probably reflect the limits of exploration (lack of submersibles capable of depths over 1,000 

m [3,281 ft]). MacDonald et al. (1993 and 1996) have analyzed remote-sensing images from space that 

reveal the presence of oil slicks across the north-central Gulf of Mexico. Results confirmed extensive 

natural oil seepage in the Gulf, especially in water depths greater than 1,000 m (3,281 ft). A total of 58 

additional potential locations were documented where seafloor sources were capable of producing 

perennial oil slicks (MacDonald et al., 1996). Estimated seepage rates ranged from 4 to 70 bbl/day 

compared with less than 0.1 bbl/day for ship discharges (both normalized for 1,000 mi2

 [3,430 km2]). 

This evidence considerably increases the area where chemosynthetic communities dependent on 

hydrocarbon seepage may be expected. 

The densest aggregations of chemosynthetic organisms have been found at water depths of around 

500 m (1,640 ft) and deeper. The best known of these communities was named Bush Hill by the 

investigators who first described it (MacDonald et al., 1989). It is a surprisingly large and dense 

community of chemosynthetic tube worms and mussels at a site of natural petroleum and gas seepage 

over a salt diapir in Green Canyon Block 185. The seep site is a small knoll that rises about 40 m (131 ft) 

above the surrounding seafloor in water about 580 m (1,903 ft) deep. 

Stability 

According to Sassen (1998), the role of naturally occurring methane hydrates at chemosynthetic 

communities has been greatly underestimated. Gas hydrates are a unique and poorly understood class of 

chemical substances in which molecules of one material (in this case water in solid state—ice) form an 

open lattice that physically encloses molecules of a certain size (in this case ─ methane) in a cage-like 

structure without chemical bonding. The biological alteration of frozen gas hydrates was first discovered 

during the recent Agency-funded study Stability and Change in Gulf of Mexico Chemosynthetic 

Communities (Sager, 1997). It is hypothesized that the dynamics of hydrate alteration could play a major 

role as a mechanism for the regulation of the release of hydrocarbon gases to fuel biogeochemical 

processes and could also play a substantial role in community stability (MacDonald, 1998). Recorded 

bottom-water temperature excursions of several degrees in some areas such as the Bush Hill site (4-5 C; 

[39-41 F] at 500-m [1,640-ft] depth) are believed to result in dissociation of hydrates, resulting in an 

increase in gas fluxes (MacDonald et al., 1994). Although not as destructive as the volcanism at vent 

sites of the mid-ocean ridges, the dynamics of shallow hydrate formation and movement clearly affects 

sessile animals that form part of the seepage barrier. There is the potential for an entire layer of shallow 

hydrate to break free of the bottom and result in considerable impact to local communities of 

chemosynthetic fauna. At deeper depths (>1,000 m; >3,281 ft), the bottom-water temperature is colder 

(by approximately 3 C [37 F]) and undergoes less fluctuation. The formation of more stable and 

probably deeper hydrates influences the flux of light hydrocarbon gases to the surface, thus influencing 

the surface morphology and characteristics of chemosynthetic communities. 

Powell (1995) reported on the notable uniqueness of each chemosynthetic community site. Through 

taphonomic studies (death assemblages of shells) and interpretation of seep assemblage composition from 

cores, Powell (1995) reported that, overall, seep communities were persistent over periods of 500-1,000 

years. Some sites retained optimal habitat over geological time scales. Powell reported evidence of 

mussel and clam communities persisting in the same sites for 500-4,000 years. Powell also found that 

both the composition of species and trophic tiering of hydrocarbon seep communities tend to be fairly 

constant across time, with temporal variations only in numerical abundance. He found few cases in which 

the community type changed (from mussel to clam communities, for example) or had disappeared 

completely. Faunal succession was not observed. Surprisingly, when recovery occurred after a past 

destructive event, the same chemosynthetic species reoccupied a site. There was little evidence of 
Description of the Environment and Impact Analysis 4-179 

catastrophic burial events, but two such instances were found in mussel communities in Green Canyon 

Block 234. 

Precipitation of authigenic carbonates and other geologic events will undoubtedly alter surface 

seepage patterns over periods of 1-2 years; although through direct observation, no changes in 

chemosynthetic fauna distribution or composition were observed at seven separate study sites 

(MacDonald et al., 1995). A slightly longer period (12 years) can be referenced in the case of Bush Hill, 

the first community described in situ in 1986. No mass die-offs or large-scale shifts in faunal 

composition have been observed over the 12-year history of research at this site. 

Biology 

MacDonald et al. (1990) has described four general community types. These are communities 

dominated by Vestimentiferan tube worms (Lamellibrachia c.f. barhami and Escarpia.sp.), mytilid 

mussels (Seep Mytilid Ia, Ib, and III, and others), vesicomyid clams (Vesicomya cordata and Calyptogena 

ponderosa), and infaunal lucinid or thyasirid clams (Lucinoma sp. or Thyasira sp.). These faunal groups 

tend to display distinctive characteristics in terms of how they aggregate, the size of aggregations, the 

geological and chemical properties of the habitats in which they occur and, to some degree, the 

heterotrophic fauna that occur with them. Many of the species found at these cold seep communities in 

the Gulf are new to science and remain undescribed. As an example, at least six different species of seep 

mussels have been collected, but none is yet described. 

Individual lamellibrachid tube worms, the longer of two taxa found at seeps (the other is an Escarpialike species but probably a new genus), can reach lengths of 3 m (10 ft) and live hundreds of years (Fisher 

et al., 1997). Growth rates determined from recovered marked tube worms have been variable, ranging 

from no growth of 13 individuals measured one year to a maximum growth of 20 mm/yr (0.8 in/yr) in a 

Lamellibrachia individual. Average growth rate was 2.5 mm/yr (0.1 in/yr) for the Escarpia-like species 

and 7.1 mm/yr (0.28 in/yr) for lamellibrachids. These are slower growth rates than those of their 

hydrothermal vent relatives, but Lamellibrachia individuals can reach lengths 2-3 times that of the largest 

known hydrothermal vent species. Lamellibrachid tube worms over 3 m (10 ft) long have been collected 

on several occasions. Tube worms of this length are probably over 400 years old (Fisher, 1995). 

Vestimentiferan tube worm spawning is not seasonal and recruitment is episodic. 

Growth rates for methanotrophic mussels at cold seep sites have been reported (Fisher, 1995). 

General growth rates were found to be relatively high. Adult mussel growth rates were similar to mussels 

from a littoral environment at similar temperatures. Fisher also found that juvenile mussels at 

hydrocarbon seeps initially grow rapidly, but the growth rate drops markedly in adults; they grow to 

reproductive size very quickly. Both individuals and communities appear to be very long lived. These 

methane-dependent mussels have strict chemical requirements that tie them to areas of the most active 

seepage in the Gulf of Mexico. As a result of their rapid growth rates, mussel recolonization of a 

disturbed seep site could occur relatively rapidly. There is some early evidence that mussels also have 

some requirement of a hard substrate and could increase in numbers if suitable substrate is increased on 

the seafloor (Fisher, 1995). 

Unlike mussel beds, chemosynthetic clam beds may persist as a visual surface phenomenon for an 

extended period without input of new living individuals because of low dissolution rates and low 

sedimentation rates. Most clam beds investigated by Powell (1995) were inactive, with little sign of 

growth. Living individuals were rarely encountered. Powell reported that, over a 50-year time span, local 

extinctions and recolonization should be gradual and exceedingly rare. 

Extensive mats of free-living bacteria are also evident at hydrocarbon seep sites. These bacteria may 

compete with the major fauna for sulfide and methane energy sources and may also contribute 

substantially to overall production (MacDonald, 1998). The white, nonpigmented mats were found to be 

an autotrophic sulfur bacteria Beggiatoa species, and the orange mats possessed an unidentified 

nonchemosynthetic metabolism (MacDonald, 1998). 

Preliminary information has been presented by Carney (1993) concerning the nonchemosynthetic 

animals (heterotrophs) found in the vicinity of hydrocarbon seeps. Heterotrophic species at seep sites are 

a mixture of species unique to seeps (particularly molluscs and crustacean invertebrates) and those that 

are a normal component from the surrounding environment. Carney reports a potential imbalance that 
4-180 Central Planning Area Supplemental EIS 

could occur as a result of chronic disruption. Because of sporadic recruitment patterns, predators could 

gain an advantage, resulting in exterminations in local populations of mussel beds. 

Detection 

Chemosynthetic communities cannot be reliably detected directly using geophysical techniques; 

however, hydrocarbon seeps and chemosynthetic communities living on them modify the near-surface 

geological characteristics in ways that can be remotely detected. These known sediment modifications 

include the following: (1) precipitation of authigenic carbonate in the form of micronodules, nodules, or 

rock masses; (2) formation of gas hydrates; (3) modification of sediment composition through 

concentration of hard chemosynthetic organism remains (such as shell fragments and layers); 

(4) formation of interstitial gas bubbles or hydrocarbons; and (5) formation of depressions or pockmarks 

by gas expulsion. These features give rise to acoustic effects such as wipeout zones (no echoes), hard 

bottoms (strongly reflective echoes), bright spots (reflection enhanced layers), or reverberant layers 

(Behrens, 1988; Roberts and Neurauter, 1990). Potential locations for most types of communities can be 

determined by careful interpretation of these various geophysical modifications, but to date, the process 

remains imperfect and confirmation of living communities requires direct visual techniques. 

As part of the Agency-funded study, Stability and Change in Gulf of Mexico Chemosynthetic 

Communities, Sager (1997) characterized the geophysical responses of seep areas that support 

chemosynthetic communities so that a protocol has been refined to use geophysical remote-sensing 

techniques to locate chemosynthetic communities reliably. One objective is to use geophysical mapping 

techniques to reduce the seafloor area that may require searching by much slower and expensive nearbottom techniques. 

Effects of the Deepwater Horizon Event on the Baseline of Chemosynthetic Communities 

The DWH event released an estimated 4.9 million bbl of oil into the water over a period of 87 days. 

Extensive literature, Internet, and database searches have been conducted for results of scientific data. 

Although many research cruises have occurred, very few scientific results have been published as of this 

writing. Descriptions of studies completed or in progress are discussed previously in this section on 

deepwater environments. Possible impacts to chemosynthetic communities are discussed below. 

A recent report documents damage to a deepwater coral community in an area that oil plume models 

predict as the direction of travel for subsea oil plumes from the DWH event. Results are still pending, but 

it appears that a coral community about 15 m x 40 m (50 ft x 130 ft) in size was severely damaged, 

possibly the result of oil impacts (USDOI, BOEMRE, 2010j). Coral and chemosynthetic communities 

form structures that protrude up into the water column above the seafloor, making them more susceptible 

to impacts from a passing oil plume. It is possible that chemosynthetic communities could have been 

affected by a passing oil plume. Research projects are continuing to investigate these areas to assess the 

impacts. Chemosynthetic communities that received low quantities of well-dispersed oil undergoing 

biodegradation likely experienced little negative effect. Exposure may have been similar to normal 

conditions for these communities or may have caused some fluctuation in health, resulting in slower 

growth or delayed spawning. Exposures to low concentrations may have resulted in sublethal impacts 

such as altered reproduction, growth, respiration, excretion, chemoreception, feeding, movement, 

stimulus response, and susceptibility to disease (Suchanek, 1993). Communities exposed to more 

concentrated oil may have experienced detrimental effects including death of affected organisms, tissue 

damage, lack of growth, interruption of reproductive cycles, and loss of gametes. Other invertebrates 

associated with chemosynthetic communities, particularly the crustaceans, would likely be more 

susceptible to damage from oil exposure. 

4.1.1.9.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with the CPA 

proposed action on chemosynthetic communities is presented in Chapter 4.2.2.1.4.2.1 of the Multisale 

EIS and in Chapter 4.1.5.2.1 of the 2009-2012 Supplemental EIS. 
Description of the Environment and Impact Analysis 4-181 

Chemosynthetic communities are susceptible to physical impacts from drilling discharges, structure 

placement (including templates or subsea completions), anchoring, and pipeline installation. In deep 

water as opposed to shallower areas on the continental shelf, discharges of drilling fluids and cuttings at 

the sea surface are spread across broad areas of the seafloor and are generally distributed in thinner 

accumulations. The physical disturbances by structures themselves are typically limited to anchors for 

holding floating drilling or production facilities over the well sites. Anchors from support boats and ships 

(or any buoys set out to moor vessels), floating drilling units, barges used for construction of platform 

structures, pipelaying vessels, and pipeline repair vessels also cause disturbances to small areas of the 

seafloor. Normal pipelaying activities in deep water could impact areas of chemosynthetic organisms if 

the pipeline crossed the organisms (pipeline burial is not required at depths where chemosynthetic 

communities are found). 

The policies described in NTL 2009-G40 greatly reduce the risk of these physical impacts by 

requiring avoidance of potential chemosynthetic communities identified on required geophysical survey 

records or by requiring photodocumentation to establish the absence of chemosynthetic communities prior 

to approval of the structure or pipeline emplacement. 

Proposed Action Analysis 

Chemosynthetic communities could be found in the deeper water areas of the CPA (i.e., Subareas 

C200-400, C400-800, C800-1600, C1600-2400, and C>2400 m). The levels of projected activity in deep 

water as a result of the CPA proposed action are shown in Table 3-2. There would be an estimated 10-16 

production structures ranging from small subsea developments to large developments involving floating, 

fixed, or subsea structures installed during the 40-year analysis period in the deepwater (>200 m; 656 ft) 

portions of the CPA as a result of the proposed action. 

The NTL 2009-G40 describes BOEMRE’s policy to search for and avoid dense chemosynthetic 

communities or areas that have a high potential for supporting these community types, as interpreted from 

geophysical records. The policies in the NTL are exercised on all applicable leases and are not optional 

protective measures. The requirements and discussion of the effectiveness of the NTL are presented in 

Chapter 4.2.2.1.4.2.1 of the Multisale EIS and in Chapter 4.1.5.2.1 in the 2009-2012 Supplemental EIS. 

Previous NTL 2000-G20 is superseded by NTL 2009-G40; the major difference in policy with the newer 

NTL is that it applies to waters as shallow as 300 m (984 ft), and the avoidance distance for muds and 

cuttings discharge is now 2,000 ft (610 m) from a potential high-density community. 

With the CPA proposed action, when geophysical survey information indicates the potential presence 

of chemosynthetic communities, the biological review process and use of NTL 2009-G40 would apply. 

This would result in a greatly reduced probability of any impacts occurring. 

Summary and Conclusion 

Chemosynthetic communities are susceptible to physical impacts from structure placement (including 

templates or subsea completions), anchoring, and pipeline installation. Because of the avoidance policies 

described in NTL 2009-G40, the risk of these physical impacts are greatly reduced by requiring the 

avoidance of potential chemosynthetic communities. 

The BOEMRE has reexamined the analysis for impacts to chemosynthetic communities presented in 

the Multisale EIS and in the 2009-2012 Supplemental EIS, based on the additional information presented 

above. No substantial new information was found that would alter the overall conclusion that impacts on 

chemosynthetic communities from routine activities associated with the CPA proposed action would be 

minimal to none. 

4.1.1.9.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts upon chemosynthetic benthic communities can be found 

in Chapter 4.4.4.2.1 of the Multisale EIS and in Chapter 4.1.5.3.1 of the 2009-2012 Supplemental EIS. 

The following is a summary of that information with consideration of new information found since 

publication of the Multisale EIS and the 2009-2012 Supplemental EIS. 
4-182 Central Planning Area Supplemental EIS 

Accidental events that could impact chemosynthetic communities are primarily limited to seafloor 

blowouts. Surface oil and chemical spills are not considered to be a potential source of measurable 

impacts on chemosynthetic communities because of the water depths at which these communities are 

located. A blowout at the seafloor could create a crater and could resuspend and disperse large quantities 

of bottom sediments within a 300-m (984-ft) radius from the blowout site. This buries organisms located 

within that distance to some degree. The application of avoidance criteria for chemosynthetic 

communities recommended by NTL 2009-G40 precludes the placement of a well within 610 m (2,000 ft) 

of any suspected site of a chemosynthetic community. 

All known reserves in the Gulf of Mexico have specific gravity characteristics that would preclude oil 

from sinking immediately after release at a blowout site. As discussed in Chapter 4.3.1.5.4 of the 

Multisale EIS, oil discharges that occur at the seafloor from a pipeline or loss of well control would rise in 

the water column and surface almost directly over the source location, thus not impacting sensitive 

deepwater communities. Therefore, the oil is expected to rise to the sea surface under natural conditions. 

This behavior is modified when dispersants are applied to the oil on the sea surface or at depth, causing 

the oil to mix with water. The dispersed oil then begins to biodegrade and may flocculate with particulate 

matter in the water column, promoting sinking of the particles. The potential for weathered components 

from a surface slick, not treated with dispersants, to reach a deepwater community in any measurable 

volume would be very small. 

Studies indicate that periods as long as hundreds of years are required to reestablish a chemosynthetic 

seep community once it has disappeared (depending on the community type); although it may reappear 

relatively quickly once the process begins, as in the case of a mussel community. Tube-worm 

communities may be the most sensitive of all communities because of the combined requirements of hard 

substrate and active hydrocarbon seepage. Mature tube-worm bushes have been found to be several 

hundred years old. There is evidence that substantial impacts on these communities could permanently 

prevent reestablishment, particularly if hard substrate required for recolonization was buried. 

Proposed Action Analysis 

For water depths >300 m (984 ft), 85-102 blowouts are estimated for the CPA proposed action over 

the 2007-2046 period (Table 4-6 of the Multisale EIS). The application of avoidance criteria for 

chemosynthetic communities recommended by NTL 2009-G40 should preclude any impact from a 

blowout at a minimum distance of 610 m (2,000 ft), which is beyond the distance of expected benthic 

disturbance. Resuspended bottom sediments transported by near-bottom currents could reach 

chemosynthetic communities located beyond 610 m (2,000 ft) and potentially impact them by burial or 

smothering. Oil treated with dispersant on the sea surface or at depth can mix with the water column and 

be carried by currents to contact chemosynthetic communities. 

The risk of various sizes of oil spills occurring in the CPA is presented in Table 3-5 . The possibility 

of a spill >10,000 bbl in the CPA is estimated to be up to one spill in the 40-year period for the proposed 

action. The possibility of oil from a surface spill reaching depth of 300 m (984 ft) or greater in any 

measurable concentration is very small. A catastrophic spill, like the DWH event, could affect 

chemosynthetic community habitat if dispersants are applied on the sea surface or at depth. The dispersed 

oil would be suspended in the water column and would begin to flocculate with particulate matter until it 

becomes heavy enough to sink and contact the seafloor. Since oil plumes would be carried by underwater 

currents, the impacts would be distributed in a line from the source toward the direction that the water 

currents travel. Oil plumes reaching chemosynthetic communities could cause oiling of organisms, 

resulting in the death of entire populations on localized sensitive habitats. These potential impacts would 

be localized due to the directional movement of oil plumes by the water currents and because the sensitive 

habitats have a scattered, patchy distribution. Habitats directly in the path of the oil plume when the oil 

contacts the seafloor would be affected. In addition, sublethal effects are possible for communities that 

receive a lower level of impact. These effects could include temporary lack of feeding, expenditure of 

energy to remove the oil, loss of gametes and reproductive delays, loss of tissue mass, and similar effects. 

Summary and Conclusion 

Chemosynthetic communities could be susceptible to physical impacts from a blowout depending on 

bottom-current conditions. The guidance provided in NTL 2009-G40 greatly reduce the risk of these 
Description of the Environment and Impact Analysis 4-183 

physical impacts. It clarifies the requirement to avoid potential chemosynthetic communities identified 

on the required geophysical survey records or photodocumentation to establish the absence of 

chemosynthetic communities prior to approval of the structure emplacement. 

Studies indicate that periods as long as hundreds of years are required to reestablish a seep 

community once it has disappeared (depending on the community type). There is evidence that 

substantial impacts on these communities could permanently prevent reestablishment, particularly if hard 

substrate required for recolonization was buried by resuspended sediments from a blowout. 

Potential accidental impacts from the CPA proposed action are expected to cause little damage to the 

ecological function or biological productivity of widespread, low-density chemosynthetic communities. 

The rarer, widely scattered, high-density, Bush Hill-type chemosynthetic communities located at more 

than 610 m (2,000 ft) away from a blowout could experience minor impacts from resuspended sediments. 

However, the possibility of oil from a surface spill reaching depth of 300 m (984 ft) or greater in any 

measurable concentration is very small. If dispersants are applied to an oil spill, oil would mix into the 

water column, be carried by underwater currents, and eventually contact the seafloor where it may impact 

patches of chemosynthetic community habitat in its path. 

The BOEMRE has reexamined the analysis for impacts to chemosynthetic communities presented in 

the Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented 

above. No substantial new information was found to indicate that accidental impacts associated with the 

CPA proposed action would result in more than minimal impacts to chemosynthetic communities because 

of the NTL 2009-G40 guidelines. One exception would be in the case of a catastrophic spill combined 

with the application of dispersant, producing the potential to cause devastating effects on local patches of 

habitat in the path of subsea plumes where they contact the seafloor. 

4.1.1.9.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts upon deepwater benthic communities of the CPA can be 

found in Chapter 4.5.4.2 of the Multisale EIS and in Chapter 4.1.5.4 of the 2009-2012 Supplemental EIS. 

The following is a summary of the information presented in the Multisale EIS and the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

Cumulative factors considered to impact the deepwater benthic communities of the Gulf of Mexico 

include both oil- and gas-related and non-oil- and non-gas-related activities. The latter type of impacting 

factors includes activities such as fishing and trawling at a relatively small scale, and large-scale factors 

such as storm impacts and climate change. 

There are essentially only three fish (or “shellfish”) species considered important to deepwater 

commercial bottom fisheries—the yellowedge grouper, tilefish, and royal red shrimp. Each of these is 

discussed in Chapter 4.5.4.2 of the Multisale EIS. Unlike other areas in the Atlantic and in Europe, 

bottom fishing and trawling efforts in the deeper water of the CPA are currently minimal, and impacts to 

deepwater benthic communities are negligible. 

Other regional non-oil- and non-gas-related sources of cumulative impact to deepwater benthic 

communities would be possible, but they are considered unlikely to occur. Essentially no anchoring from 

non-OCS-related activities occurs at the deeper water depths considered for these resources (>300 m; 

984 ft). Some impacts are highly unlikely yet not impossible, such as the sinking of a ship or barge 

resulting in collision or contaminant release directly on top of a sensitive, high-density chemosynthetic 

community. 

One potential significant, large-scale source of impact could be potential efforts of carbon 

sequestration in the deep sea as a technique to reduce atmospheric carbon dioxide. This concept is still 

being considered but has major ramifications. One side of the issue, even beyond the problems of sealevel increase and climate change, includes the serious risk to shallow-water benthic organisms through 

pH increases, particularly those with calcium carbonate shells and skeletons (e.g., corals, serpulid worms, 

bryozoa, calcareous algae, etc) (Kleypas et al., 1999b; Barry et al., 2005; Shirayama and Thornton, 2005). 

However, the impacts of even very small excursions of pH and CO2 in the deep sea could also have 

serious, even global, deep-sea ecosystem impacts. Kita and Ohsumi (2004) suggest sequestration of 

anthropogenic CO2 could help reduce atmospheric CO2, but they also summarize the potentially 

substantial biological impact on marine organisms. The issue continues to gain attention with the 
4-184 Central Planning Area Supplemental EIS 

increased emphasis on climate change. Scientists suggested in the August 2006 issue of the Proceedings 

of the National Academy of Sciences that thousands of years of the Nation’s carbon emissions could be 

stored in undersea sediments along the coasts (Zenz House et al., 2006). A similar plan has been 

promoted by a private corporation to spread large amounts of nitrogen fertilizer in low-productive tropical 

waters (Maden and Nevala, 2008). Such a plan needs further thought since nutrients in urban runoff to 

tropical seas are considered to be a major contributor to the decline of coral reefs. Substantial additional 

research is needed before any large-scale actions would take place. 

The greatest potential for cumulative adverse impacts to occur to the deepwater benthic communities 

would come from those OCS-related, bottom-disturbing activities associated with pipeline and platform 

emplacement (including templates and subsea completions), associated anchoring activities, discharges of 

muds and cuttings, and seafloor blowout accidents. The potential impacts to deepwater benthic 

communities from these activities were discussed in detail in Chapter 4.5.4.2 of the Multisale EIS. 

As exploration and development continue on the Federal OCS, activities have moved farther into the 

deeper water areas of the Gulf of Mexico. With this trend comes the certainty that increased development 

would occur on discoveries throughout the entire depth range of the CPA; these activities would be 

accompanied by limited unavoidable impacts to the soft-bottom deepwater benthos from bottom 

disturbances and disruption of the seafloor from associated activities. The extent of these disturbances 

would be determined by the intensity of development in these deepwater regions, the types of structures 

and mooring systems used, and the effective application of the avoidance criteria as described in NTL 

2009-G40 (USDOI, MMS, 2009c). All activity levels for the cumulative scenario in the CPA are shown 

in Table 4-6 of the Multisale EIS. For the CPA deepwater offshore Subareas C200-400, C400-800 

C800-1600, C1600-2400, and C>2400, there are currently an estimated 39-84 exploration and delineation 

wells and 253-458 development wells to be drilled and 10-16 production structures to be installed through 

the 40-year analysis period (Table 3-2). 

Routine discharges of drilling muds and cuttings have been documented to reach the seafloor in water 

depths >300 m (984 ft) and the impacts have been analyzed in the Multisale EIS, including the results 

from a study by CSA (2006b), Effects of Oil and Gas Exploration and Development at Selected 

Continental Slope Sites in the Gulf of Mexico. Potential local cumulative impacts could result from 

accumulations of muds and cuttings resulting from consistent hydrographic conditions and drilling of 

multiple wells from the same location, causing concentrations of material in a single direction or “splay.” 

It is not expected that detectable levels of muds and cuttings discharges from separate developments or 

from adjacent lease blocks would act as a cumulative impact to deepwater benthic communities, due to 

their physical separation and great water depths. 

Numerous new chemosynthetic communities were discovered and explored using the submersible 

Alvin in 2006 and with the remotely operated vehicle Jason II in 2007 as part of the recent Agencyfunded study, Investigations of Chemosynthetic Communities on the Lower Continental Slope of the Gulf 

of Mexico: Interim Report 2 (Brooks et al., 2009). These new communities were targeted using the same 

procedures integral to the biological review process and the use of NTL 2009-G40 targeting areas of 

potential community areas to be avoided by impacting oil and gas activities. There is no reason to expect 

an increased vulnerability of these deep communities to cumulative impacts. 

A blowout at the seafloor could resuspend large quantities of bottom sediments and even create a 

large crater, destroying any organisms in the area. Structure removals and other bottom-disturbing 

activities could resuspend bottom sediments, but not at magnitudes as great as blowout events. Subsea 

structure removals are not expected in water depths >800 m (2,625 ft), in accordance with 30 CFR 250. 

The distance of separation provided by adherence to the guidelines of NTL 2009-G40 would protect 

chemosynthetic communities from sedimentation effects of deepwater blowouts. It is reported that 

chemically dispersed surface oil from the DWH event remained in the top 6 m (20 ft) of the water column 

where it mixed with surrounding waters and biodegraded (Lubchenco et al., 2010). Data from other 

studies on dispersant usage on surface plumes indicate that a majority of the dispersed oil remained in the 

top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (7 ft) (McAuliffe et al., 

1981a). Therefore, oil spills on the sea surface are expected to have little to no effect on deepwater 

communities. 

Subsea oil plumes resulting from a seafloor blowout could affect sensitive deepwater communities. 

This is especially true if dispersants are applied at depth. A recent report documents damage to a 

deepwater coral community in an area that oil plume models predicted as the direction of travel for subsea 
Description of the Environment and Impact Analysis 4-185 

oil plumes from the DWH event. Results are still pending but it appears that a coral community about 

15 m x 40 m (50 ft x 130 ft) in size was severely damaged, possibly the result of oil impacts (USDOI, 

BOEMRE, 2010j). Such blowouts are rare and may not release catastrophic quantities of oil. Oil that is 

released would be carried in whatever direction the water currents flow. This directional flow could only 

affect seafloor habitats that are downstream from the source. Sensitive deepwater communities appear to 

be widely scattered and not as rare as previously expected. Recent BOEMRE analyses of seafloor 

remote-sensing data indicate over 15,000 locations in the deep GOM that represent potential hard-bottom 

habitats. While it is likely that any subsea oil plume traveling more than a few miles on the deep seafloor 

would encounter at least one of these potential habitats, it would result in a localized effect that is not 

expected to alter the wider population of the GOM. 

In cases where high-density communities are subjected to greatly dispersed cumulative discharges or 

suspended sediments, the impacts are most likely to be sublethal in nature and limited in areal extent. The 

impacts to ecological function of high-density communities would be minor; minor impacts to ecological 

relationships with the surrounding benthos would also be likely. 

Because of the great water depths, treated sanitary wastes and produced waters are not expected to 

have any adverse cumulative impacts to any deepwater benthic communities. These effluents would 

undergo a great deal of dilution and dispersion before reaching the bottom, if ever. 

Oil and chemical spills (potentially from non-OCS-related activities) are not considered to be a 

potential source of measurable impacts on any deepwater communities because of water depth. Oil spills 

from the surface would tend to float. Oil discharges at depth or on the bottom would tend to rise in the 

water column and similarly not impact the benthos unless dispersants are applied at depth. 

Deepwater coral and other hard-bottom communities not associated with chemosynthetic 

communities are also expected to be protected from cumulative impacts by general adherence to guidance 

described in NTL 2009-G40 and the shallow hazards NTL 2008-G05, due to the avoidance of areas 

represented as hard bottom on surface anomaly maps derived from 3D seismic records (USDOI, MMS, 

2008c and 2009c). Biological reviews are performed on all deepwater plans (exploration and production) 

and pipeline applications, which include an analysis of maps and the avoidance of hard-bottom areas that 

are also one of several important indicators for the potential presence of chemosynthetic communities. 

Summary and Conclusion 

Cumulative impacts to deepwater communities in the Gulf of Mexico from sources other than OCS 

activities are considered negligible. The most serious, impact-producing factor threatening 

chemosynthetic communities is physical disturbance of the seafloor, which could destroy the organisms 

of these communities. Such disturbance would most likely come from those OCS-related activities 

associated with pipelaying, anchoring, structure emplacement, and seafloor blowouts. Drilling discharges 

and resuspended sediments have a potential to cause minor, mostly sublethal impacts to chemosynthetic 

communities, but substantial accumulations could result in more serious impacts. Seafloor disturbance is 

considered to be a threat only to the high-density communities; widely distributed low-density 

communities would not be at risk. Possible catastrophic oil spills due to seafloor blowouts have the 

potential to devastate localized deepwater benthic habitats. However, these events are rare and would 

only affect a small portion of the sensitive benthic habitat in the GOM. Recent analyses reveal over 

15,000 possible hard-bottom locations across the deepwater GOM. Guidance provided in NTL 2009-G40 

describes required surveys and avoidance prior to drilling or pipeline installation and would greatly 

reduce risk. New studies have refined predictive information and confirmed the effectiveness of these 

provisions throughout all depth ranges of the Gulf of Mexico (Brooks et al., 2009). With the dramatic 

success of this project, confidence is increasing regarding the use of geophysical signatures for the 

prediction of chemosynthetic communities. 

Activities unrelated to the OCS Program include fishing and trawling. Because of the water depths in 

these areas (>300 m; 984 ft) and the low density of potentially commercially valuable fishery species, 

these activities are not expected to impact deepwater benthic comminutes. Regionwide and even global 

impacts from CO2 build-up and proposed methods to sequester carbon in the deep sea (e.g., ocean 

fertilization) are not expected to have major impacts to deepwater habitats in the near future. More 

distant scenarios could include severe impacts. 
4-186 Central Planning Area Supplemental EIS 

The proposed activities in the CPA considered under the cumulative scenario are expected to cause 

little damage to the ecological function or biological productivity of the widespread, low-density 

chemosynthetic communities. The rarer, widely scattered, high-density, Bush Hill-type chemosynthetic 

communities could experience isolated minor impacts from drilling discharges or resuspended sediments, 

with recovery expected within several years, but even minor impacts are not expected. Major impacts to 

localized benthic habitat are possible in the event of a catastrophic blowout on the seafloor. If physical 

disturbance (such as anchor damage) or extensive burial by muds and cuttings were to occur to highdensity, Bush Hill-type communities, impacts could be severe, with recovery time as long as 200 years 

for mature tube-worm communities. There is evidence that substantial impacts on these communities 

would permanently prevent reestablishment. The severity of such an impact is such that there would be 

incremental losses of productivity, reproduction, community relationships, overall ecological functions of 

the community, and incremental damage to ecological relationships with the surrounding benthos. 

The incremental contribution of the CPA proposed action to cumulative impacts is expected to be 

slight and to result from the effects of the possible impacts caused by physical disturbance of the seafloor 

and minor impacts from sediment resuspension or drill cutting discharges. Adverse impacts would be 

limited but not completely eliminated by adherence to guidelines in NTL 2009-G40. 

4.1.1.10. Nonchemosynthetic Deepwater Benthic Communities 

4.1.1.10.1. Description of the Affected Environment 

A description of the continental slope and deepwater resources can be found in the introduction to 

chemosynthetic communities in Chapter 4.1.1.9 of this Supplemental EIS and in Chapter 3.2.2.2 of the 

Multisale EIS. Additional information for the 181 South Area and any new information since the 

publication of the Multisale EIS can be found in Chapter 4.1.5.1 of the 2009-2012 Supplemental EIS. 

The following information is a summary of the resource description incorporated from the Multisale EIS 

and the Supplemental EIS, and new information that has become available since both documents were 

prepared. 

Deepwater Coral Benthic Communities 

Deepwater corals are relatively rare examples of deepwater communities that would not be expected 

considering the fact that the vast majority of the deep GOM continental slope is made up of soft silt and 

clay sediments. Hermatypic (reef-building) corals contain photosynthetic algae and cannot live in 

deepwater environments; however, many ahermatypic corals can live on suitable substrates (hardgrounds) 

in these environments. Scleractinian corals are recognized in deepwater habitats, but there is little 

information regarding their distribution or abundance in the Gulf (USDOI, MMS, 2000, p. IV-14). 

Scleractinian corals may occupy isolated hard-bottom habitats but usually occur in association with highdensity chemosynthetic communities that often are situated on carbonate hardgrounds. 

Deepwater coral communities are now known to occur in many locations in the deep GOM (>300 m; 

984 ft); one example is represented by what was reported as a deepwater coral reef by Moore and Bullis 

(1960). In an area measuring 300 m (984 ft) in length and more than 20 nmi (23 mi; 37 km) from the 

nearest known chemosynthetic community (likely in Viosca Knoll Block 906), a 1955 trawl collection 

from a depth of 421-512 m (1,381-1,680 ft) retrieved more than 300 lb (136 kg) of the scleractinian coral 

Lophelia pertusa. 

The “rediscovery” of the Moore and Bullis site was notable. Prior to a NR 1 Navy submersible cruise 

in 2002, there was a need to identify potential study sites for deepwater corals. The location sampled by 

Moore and Bullis had not been revisited since their trawl in 1955. The rough location given in their paper 

(29°5' N. latitude, 88°19' W. longitude; Moore and Bullis, 1960) was located in a soft-bottom 

environment. A biologist with BOEMRE used this location as a starting point and utilized the BOEMRE 

in-house 3D seismic database depicting seafloor bathymetry and hard-bottom features in the region. 

Approximately 5 nmi (6 mi; 9 km) to the west of the published location, there was a striking set of 

features including a narrow canyon that closely matched the fathometer tracing and depth of a feature 

illustrated in Moore and Bullis (1960). A number of potential high-reflectivity target locations across the 

canyon were provided for the NR 1 project. Although no Lophelia coral was found in the canyon, a 

spectacular habitat including Lophelia and a variety of antipatharian “black corals” (some up to 3 m (9.8 
Description of the Environment and Impact Analysis 4-187 

ft) in height) was found while investigating the shallowest of the hard-bottom features located nearby in 

Viosca Knoll Block 862. It is not known if this peak was along the Moore and Bullis trawl track. 

A large coral community (L. pertusa) was also discovered in Viosca Knoll Block 826 at a depth of 

434 m (1,424 ft) by LGL Ecological Research Associates, Inc. while doing a chemosynthetic community 

environmental survey for Oryx Energy in 1990 (LGL Ecological Research Associates, Inc., 1990). 

Individual coral colonies at this site attain 1.5-2 m (5-7 ft) in height and width and up to 3-4 m (10-13 ft) 

in length. A large portion of the coral colonies are living. It was subsequently studied by submersible in 

the following years, 1991 and 1992, as well as numerous occasions since and is described in detail in 

Schroeder (2002). These deepwater coral habitats have since been shown to be much more extensive and 

important to the support of diverse communities of associated fauna than previously known in the GOM. 

This community in Viosca Knoll Block 826 remains the largest and best developed Lophelia community 

known in the northern GOM. This type of unusual and unexpected community may exist in many other 

areas of the deep GOM. Although Lophelia is best represented in water depths of the upper slope, it has 

been reported as deep as 3,000 m (9,842 ft) in some parts of the world. Additional studies funded by 

BOEMRE are in progress or in earlier stages of development that will further investigate the distribution 

of deepwater corals and other important nonchemosynthetic communities in the deep GOM. 

As described previously, hard substrate originating from the Florida Escarpment appears to be 

exposed both at the upper crest of the escarpment at a depth of 1,600 m (5,248 ft) as well as an 

accumulation of probable talus at the bottom of the escarpment at a depth of 2,800 m (9,184 ft). If these 

reflective targets from 3D seismic are indeed exposed hard substrate, they could very possibly be 

colonized by a variety of deep-sea organisms including scleractinian corals. Although deeper than the 

high-density colonies of the upper slope, these depths are not prohibitive to a variety of coral 

development, including Lophelia and Madrepora. A relatively large accumulation of Madrepora was 

discovered during the recent Agency-funded study “Chemo III” in Green Canyon Block 852 at a depth of 

1,448 m (4,749 ft), very similar to the depth of the top of the escarpment (Brooks et al., 2009). 

Considering the depth of this resource, >300 m (984 ft), these deepwater communities would be beyond 

the impacts from severe storms or hurricanes, and there has been no alteration of these communities 

caused from surface storms, including the severe hurricane season of 2005. 

Deepwater Horizon Event 

The DWH event released an estimated 4.9 million bbl of oil into the water over a period of 87 days. 

Extensive literature, Internet, and database searches have been conducted for results of scientific data. 

Although many research cruises have occurred, very few scientific results have been published as of this 

writing. Descriptions of studies completed or in progress are discussed in the previous section on 

chemosynthetic communities (Chapter 4.1.1.9). Possible impacts to nonchemosynthetic communities 

are discussed below. 

Much of the oil was treated with dispersant at the sea surface and at the source in 1,500-m (5,000-ft) 

water depth. The dispersed oil mixed with the water; its movement was dictated by water currents and 

the physical processes of degradation. A full discussion of the fate and behavior of oil from the DWH 

event on chemosynthetic communities can be found in Chapter 4.1.1.9. Depending on how long it 

remained in the water column, oil may have been well-dispersed and thoroughly degraded by biological 

action before contact with the seafloor. 

There have been no experiments showing the response of deepwater corals to oil exposure. 

Experiments with shallow tropical corals indicate that corals have a high tolerance to oil exposure. The 

mucus layers on coral resist penetration of oil and slough off the contaminant. Longer exposure times and 

areas of tissue where oil adheres to the coral are more likely to result in tissue damage and death of 

polyps. Corals with branching growth forms appear to be more susceptible to damage from oil exposure 

(Shigenaka, 2001). The most common deepwater coral, Lophelia pertusa, is a branching species. Tests 

with shallow tropical gorgonians indicate relatively low toxic effects to the coral, suggesting deepwater 

gorgonians may have a similar response (Cohen et al., 1977). Deepwater coral response to exposure to oil 

from the DWH event would vary, depending on the level of exposure. A recent report documents damage 

to a deepwater coral community in an area that oil plume models predict as the direction of travel for 

subsea oil plumes from the DWH event. Results are still pending but it appears that a coral community 

about 15 m x 40 m (50 ft x 130 ft) in size was severely damaged, possibly the result of oil impacts 
4-188 Central Planning Area Supplemental EIS 

(USDOI, BOEMRE, 2010j). Coral forms structures that protrude up into the water column above the 

seafloor, making them more susceptible to impacts from a passing oil plume. Research projects are 

continuing to investigate areas around the DWH event to assess the impacts. 

Communities exposed to concentrated oil may have experienced detrimental effects including death 

of affected organisms, tissue damage, lack of growth, interruption of reproductive cycles, and loss of 

gametes. Median levels of exposure to dispersed oil in a partly degraded condition may have resulted in 

effects similar to those for shallow tropical corals, with often no discernable effects other than temporary 

contraction and some sloughing. Exposure to widely dispersed oil adhering to organic detritus and 

partially degraded by bacteria may be expected to result in little effect. Health of corals may have been 

degraded by the necessary expenditure of energy as the corals respond to oiling, Coral exposure to lower 

concentrations of oil may have resulted in sublethal impacts such as altered reproduction, growth, 

respiration, excretion, chemoreception, feeding, movement, stimulus response, and susceptibility to 

disease (Suchanek, 1993). Many invertebrates associated with deepwater coral communities, particularly 

the crustaceans, would likely be more susceptible to damage from oil exposure. Recolonization of 

severely damaged or destroyed communities could take years to decades. 

4.1.1.10.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with the CPA 

proposed action on nonchemosynthetic communities is presented in Chapter 4.2.2.1.4.2.2 of the Multisale 

EIS and in Chapter 4.1.5.2.2 of the 2009-2012 Supplemental EIS. Similar to chemosynthetic 

communities, benthic communities other than chemosynthetic organisms could be impacted by physical 

impacts from drilling discharges, structure placement (including templates or subsea completions), 

anchoring, or pipeline installation. 

Both widespread soft-bottom and rare hard-bottom, nonchemosynthetic deepwater benthic 

communities are susceptible to physical impacts from drilling discharges, structure placement (including 

templates or subsea completions), anchoring, and pipeline installation. In deep water as opposed to 

shallower areas on the continental shelf, discharges of drilling fluids and cuttings at the surface are spread 

across broader areas of the seafloor and are generally distributed in thinner accumulations. Carbonate 

outcrops and deepwater coral communities not associated with chemosynthetic communities are 

considered to be most at risk from oil and gas operations. 

The physical disturbances by structures themselves are typically limited to anchors for holding 

floating drilling or production facilities over the well sites. Anchoring would not necessarily directly 

destroy small infaunal organisms living within the sediment. The bottom disturbance would most likely 

change the environment to such an extent that the majority of the directly impacted infauna community 

would not survive (e.g., burial or relocation to sediment layers without sufficient oxygen), but adjacent 

populations of all size classes of organisms would quickly repopulate the modified sediment. In addition, 

increased surface roughness (rugosity) resulting from anchor or related disturbance of mud bottom would 

positively impact the habitat value for many infaunal and epifaunal groups as a result of increased habitat 

complexity. In cases of carbonate outcrops or reefs with attached epifauna or coral, the impacted area of 

disturbance may be small in absolute terms, but it could be a large portion of the local area inhabited by 

fragile hard corals or other organisms that rely on exposed hard substrate. Anchors from support boats 

and ships (or any buoys set out to moor vessels), floating drilling units, barges used for the construction 

of platform structures, pipelaying vessels, and pipeline repair vessels could also cause severe disturbances 

to small areas of the seafloor. 

Normal pipelaying activities in deepwater areas could impact areas of hard-bottom 

nonchemosynthetic organisms if they were crossed by the pipeline (pipeline burial is not required at 

depths where deepwater hard-bottom communities are found). Impacts of pipeline contact on soft bottom 

would be minimal. 

Proposed Action Analysis 

The routine activities associated with the CPA proposed action that would impact nonchemosynthetic 

benthic communities would come from activities associated with drilling discharges, structure placement 
Description of the Environment and Impact Analysis 4-189 

(including templates or subsea completions), anchoring, or pipeline installation. For the CPA proposed 

action, 10-16 production structures ranging from small subsea developments to large developments 

involving floating, fixed, or subsea structures are estimated to be installed during the 40-year analysis 

period in Subareas C200-400 C400-800, C800-1600, C1600-2400, and C>2400 m (Table 3-2). Drilling 

muds and cuttings discharged at the seafloor or from the surface would have some limited impact to softbottom communities at or below the sediment/water interface. The surface discharge of muds and 

cuttings in deeper water would reduce or eliminate the impact of smothering the benthic communities on 

the bottom due to increased dispersal. Even in situations where the substantial burial of typical benthic 

infaunal communities occurred, recolonization by populations from neighboring soft-bottom substrate 

would be expected over a relatively short period of time for all size ranges of organisms. An additional 

analysis of muds and cuttings discharge impacts appears in Chapter 4.1.1.4.1 of the Multisale EIS. 

Physical disturbance or destruction of a limited area of benthos or to a limited number of megafauna 

organisms such as brittle stars, sea pens, or crabs would not result in a major impact to the deepwater 

benthos ecosystem as a whole. Under the current review procedures for chemosynthetic communities as 

described in NTL 2009-G40, carbonate outcrops are targeted as one possible indication (surface 

amplitude anomaly on 3D seismic survey data) of the presence of chemosynthetic seep communities. 

Unique communities that may be associated with any carbonate outcrops or other topographical features 

can be identified via this review, along with the chemosynthetic communities. Typically, all areas 

suspected of being hard bottom are avoided as geological hazards for any well sites. Any proposed 

activity in water depths >300 m (984 ft) would automatically trigger the NTL 2009-G40 evaluation 

described above. 

The impacts of pipeline contact on soft bottom would be minimal because pipeline burial is not 

required in water depths <61 m (200 ft). Hard-bottom areas would be avoided for the same reasons 

described above. 

With the CPA proposed action, when geophysical survey information indicates the potential presence 

of chemosynthetic communities, the biological review process and use of NTL 2009-G40 would apply. 

This would result in a greatly reduced probability of any impacts occurring. 

Summary and Conclusion 

Some impact to soft-bottom benthic communities from drilling and production activities would occur 

as a result of physical impact from drilling discharges, structure placement (including templates or subsea 

completions), anchoring, and installation of pipelines regardless of their locations. However, even in 

situations where the substantial burial of typical benthic infaunal communities occurred, recolonization 

from populations from widespread neighboring soft-bottom substrate would be expected over a relatively 

short period of time for all size ranges of organisms. 

Impacts to other hard-bottom communities are expected to be avoided as a consequence of the 

application of the existing NTL 2009-G40 guidelines for chemosynthetic communities. The same 

geophysical conditions associated with the potential presence of chemosynthetic communities also results 

in the potential occurrence of hard carbonate substrate and nonchemosynthetic communities. Because of 

the NTL 2009-G40 guidelines, these are generally avoided in exploration and development planning. 

The BOEMRE has reexamined the analysis for impacts to nonchemosynthetic communities presented 

in the Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented 

above. No substantial new information was found that would alter the overall conclusion that impacts on 

nonchemosynthetic communities from routine activities associated with the CPA proposed action would 

be minimal to none. 

4.1.1.10.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts upon nonchemosynthetic, deepwater benthic 

communities can be found in Chapter 4.4.4.2.2 of the Multisale EIS and in Chapter 4.1.5.3.2 of the 2009-

2012 Supplemental EIS. The following is a summary of that information with consideration of new 

information found since publication of the Multisale EIS and the 2009-2012 Supplemental EIS. 
4-190 Central Planning Area Supplemental EIS 

Accidental events that could impact nonchemosynthetic deepwater benthic communities are primarily 

limited to seafloor blowouts. Surface oil and chemical spills are not considered to be a potential source of 

measurable impacts on nonchemosynthetic communities because of the water depths at which these 

communities are located. A blowout at the seafloor could create a crater and could resuspend and 

disperse large quantities of bottom sediments within a 300-m (984-ft) radius from the blowout site. This 

would destroy any organisms located within that distance by burial or modification of narrow habitat 

quality requirements. Physical disturbance or destruction of a limited area of benthos or to a limited 

number of megafauna organisms (e.g. brittle stars, sea pens, and crabs) would not result in a major impact 

to the deepwater benthos ecosystem as a whole or even in relation to a small area of the seabed within a 

lease block. The application of avoidance criteria for deepwater coral communities recommended by 

NTL 2009-G40 precludes the placement of a well within 610 m (2,000 ft) of any suspected site of a 

deepwater coral community. 

All known reserves in the Gulf of Mexico have specific gravity characteristics that would preclude oil 

from sinking immediately after release at a blowout site. As discussed in Chapter 4.3.1.5.4 of the 

Multisale EIS, oil discharges that occur at the seafloor from a pipeline or loss of well control would rise in 

the water column and surface almost directly over the source location, thus not impacting sensitive 

deepwater communities. Therefore, the oil is expected to rise to the sea surface under natural conditions. 

This behavior is modified when dispersants are applied to the oil on the sea surface or at depth, causing 

the oil to mix with water. The dispersed oil then begins to biodegrade and may flocculate with particulate 

matter in the water column, promoting sinking of the particles. The potential for weathered components 

from a surface slick, not treated with dispersants, to reach a deepwater community in any measurable 

volume would be very small. 

Deepwater coral habitats and other potential hard-bottom communities not associated with 

chemosynthetic communities appear to be relatively rare. Any hard substrate communities located in 

deep water would be particularly sensitive to impacts. Impacts to these sensitive habitats could 

permanently prevent recolonization, with similar organisms requiring hard substrate. Adherence to the 

guidance provided in NTL 2009-G40 should prevent all but minor impacts to hard-bottom communities 

located the prescribed distance of more than 610 m (2,000 ft) from a well site. Under the current review 

procedures, carbonate outcrops (high reflectivity surface anomalies on 3D seismic survey data) are 

targeted as one possible indication that sensitive hard-bottom communities are present. Typically, all 

areas suspected of being hard bottom are avoided as a potential geological hazard for any well sites. Any 

proposed impacting activity in water depths >300 m (984 ft) would automatically trigger the NTL 

2009-G40 evaluation described above. 

Proposed Action Analysis 

For water depths >300 m (984 ft), 85-102 blowouts are estimated for the CPA proposed action over 

the 2007-2046 period (Table 4-6 of the Multisale EIS). Resuspended sediments caused from a blowout 

would have minimal impacts on the full spectrum of soft-bottom community animals, including the 

possible mortality of a few megafauna specimens such as crab or shrimp. The application of avoidance 

criteria for sensitive deepwater communities recommended by NTL 2009-G40 should preclude a blowout 

from affecting hard-bottom communities located the prescribed distance of more than 609 m (2,000 ft) 

from a well site. 

The risk of various sizes of oil spills occurring in the CPA is presented in Table 3-5 . The possibility 

of a spill >10,000 bbl in the CPA is estimated to be up to one spill during in the 40-year life of the 

proposed action. The possibility of oil from a surface spill reaching depths of 300 m (984 ft) or greater in 

any measurable concentration is very small. A catastrophic spill, like the DWH event, could affect 

nonchemosynthetic community habitat if dispersants are applied on the sea surface or at depth. The 

dispersed oil would be suspended in the water column and would begin to flocculate with particulate 

matter until it becomes heavy enough to sink and contact the seafloor. Since oil plumes would be carried 

by underwater currents, the impacts would be distributed in a line from the source toward the direction 

that the water currents travel. Oil plumes reaching nonchemosynthetic communities could cause oiling of 

organisms resulting in the death of entire populations on localized sensitive habitats. These potential 

impacts would be localized due to the directional movement of oil plumes by the water currents and 

because the sensitive habitats have a scattered, patchy distribution. Habitats directly in the path of the oil 
Description of the Environment and Impact Analysis 4-191 

plume when the oil contacts the seafloor would be affected. In addition, sublethal effects are possible for 

communities that receive a lower level of impact. These effects could include temporary lack of feeding, 

expenditure of energy to remove the oil, loss of gametes and reproductive delays, loss of tissue mass, and 

similar effects. 

Summary and Conclusion 

Accidental events resulting from the CPA proposed action are expected to cause little damage to the 

ecological function or biological productivity of widespread, typical, deep-sea benthic communities. 

Some impact to benthic communities would occur as a result of impact from an accidental blowout. 

Megafauna and infauna communities at or below the sediment/water interface would be impacted by the 

physical disturbance of a blowout or by burial from resuspended sediments. However, even in situations 

where the substantial burial of typical soft benthic communities occurred, recolonization by populations 

from neighboring substrate would be expected over a relatively short period of time. For all size ranges 

of organisms, this can be in a matter of hours to days for bacteria and about 1-2 years for most all 

macrofauna species. 

Impacts to deepwater coral habitats and other potential hard-bottom communities would likely be 

avoided as a consequence of the application of the policies described in NTL 2009-G40. The rare, widely 

scattered, high-density, Bush Hill-type nonchemosynthetic communities located at more than 610 m 

(2,000 ft) away from a blowout could experience minor impacts from resuspended sediments. If 

dispersants are applied to an oil spill oil would mix into the water column, be carried by underwater 

currents, and eventually contact the seafloor where it may impact patches of sensitive deepwater 

community habitat in its path. These potential impacts would be localized due to the directional 

movement of oil plumes by the water currents and because the sensitive habitats have a scattered, patchy 

distribution. 

The BOEMRE has reexamined the analysis for impacts to nonchemosynthetic communities presented 

in the Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented 

above. No substantial new information was found to indicate that accidental impacts associated with the 

CPA proposed action would result in more than minimal impacts to nonchemosynthetic communities. 

One exception would be in the case of a catastrophic spill combined with the application of dispersant, 

producing the potential to cause devastating effects on local patches of habitat in the path of subsea 

plumes where they contact the seafloor. 

4.1.1.10.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts upon deepwater benthic communities of the CPA can be 

found in Chapter 4.5.4.2 of the Multisale EIS and in Chapter 4.1.5.4 of the 2009-2012 Supplemental EIS. 

The following is a summary of the information presented in the Multisale EIS and the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

Cumulative factors considered to impact the deepwater benthic communities of the Gulf of Mexico 

include both oil- and gas-related and non-oil- and non-gas-related activities. The latter type of impacting 

factors includes activities such as fishing and trawling at a relatively small scale, and large-scale factors 

such as storm impacts and climate change. 

There are essentially only three fish (or “shellfish”) species considered important to deepwater 

commercial bottom fisheries—the yellowedge grouper, tilefish, and royal red shrimp. Each of these is 

discussed in Chapter 4.5.4.2 of the Multisale EIS. Unlike other areas in the Atlantic and in Europe, 

bottom fishing and trawling efforts in the deeper water of the CPA are currently minimal, and impacts to 

deepwater benthic communities are negligible. 

Other regional non-oil- and non-gas-related sources of cumulative impact to deepwater benthic 

communities would be possible, but they are considered unlikely to occur. Essentially no anchoring from 

non-OCS-related activities occurs at the deeper water depths considered for these resources (>300 m; 

984 ft). Some impacts are highly unlikely yet not impossible, such as the sinking of a ship or barge 

resulting in collision or contaminant release directly on top of a sensitive, high-density 

nonchemosynthetic community. 
4-192 Central Planning Area Supplemental EIS 

One potential significant large-scale source of impact could be potential efforts of carbon 

sequestration in the deep sea as a technique to reduce atmospheric carbon dioxide. This concept is still 

being considered but has major ramifications. One side of the issue, even beyond the problems of sealevel increase and climate change, includes the serious risk to shallow-water benthic organisms through 

pH increases, particularly those with calcium carbonate shells and skeletons (e.g., corals, serpulid worms, 

bryozoa, calcareous algae, etc) (Kleypas et al., 1999b; Barry et al., 2005; Shirayama and Thornton, 2005). 

However, the impacts of even very small excursions of pH and CO2 in the deep sea could also have 

serious, even global, deep-sea ecosystem impacts. Kita and Ohsumi (2004) suggest sequestration of 

anthropogenic CO2 could help reduce atmospheric CO2, but they also summarize the potentially 

substantial biological impact on marine organisms. The issue continues to gain attention with the 

increased emphasis on climate change. Scientists suggested in the August 2006 issue of the Proceedings 

of the National Academy of Sciences that thousands of years of the Nation’s carbon emissions could be 

stored in undersea sediments along the coasts (Zenz House et al., 2006). A similar plan has been 

promoted by a private corporation to spread large amounts of nitrogen fertilizer in low productive tropical 

waters (Maden and Nevala, 2008). Such a plan needs further thought since nutrients in urban runoff to 

tropical seas are considered to be a major contributor to the decline of coral reefs. Substantial additional 

research is needed before any large-scale actions would take place. 

The greatest potential for cumulative adverse impacts to occur to the deepwater benthic communities 

would come from those OCS-related, bottom-disturbing activities associated with pipeline and platform 

emplacement (including templates and subsea completions), associated anchoring activities, discharges of 

muds and cuttings, and seafloor blowout accidents. The potential impacts to deepwater benthic 

communities from these activities were discussed in detail in Chapter 4.5.4.2 of the Multisale EIS. 

As exploration and development continue on the Federal OCS, activities have moved farther into the 

deeper water areas of the Gulf of Mexico. With this trend comes the certainty that increased development 

would occur on discoveries throughout the entire depth range of the CPA; these activities would be 

accompanied by limited unavoidable impacts to the soft-bottom deepwater benthos from bottom 

disturbances and disruption of the seafloor from associated activities. The extent of these disturbances 

would be determined by the intensity of development in these deepwater regions, the types of structures 

and mooring systems used, and the effective application of the avoidance criteria as described in NTL 

2009-G40 (USDOI, MMS, 2009c). All activity levels for the cumulative scenario in the CPA are shown 

in Table 4-6 of the Multisale EIS. For the CPA deepwater, offshore Subareas C200-400, C400-800, 

C800-1600, C1600-2400, and C>2400, there are currently an estimated 39-84 exploration and delineation 

wells and 253-458 development wells to be drilled and 10-16 production structures to be installed through 

the 40-year analysis period (Table 3-2). 

Routine discharges of drilling muds and cuttings have been documented to reach the seafloor in water 

depths >300 m (984 ft) and the impacts have been analyzed in the Multisale EIS, including the results 

from a study by CSA (2006b), Effects of Oil and Gas Exploration and Development at Selected 

Continental Slope Sites in the Gulf of Mexico. Potential local cumulative impacts could result from 

accumulations of muds and cuttings resulting from consistent hydrographic conditions and drilling of 

multiple wells from the same location causing concentrations of material in a single direction or “splay.” 

It is not expected that detectable levels of muds and cuttings discharges from separate developments or 

from adjacent lease blocks would act as a cumulative impact to deepwater benthic communities due their 

physical separation and great water depths. 

Numerous new deepwater communities were recently discovered and explored using the submersible 

Alvin in 2006 and with the remotely operated vehicle Jason II in 2007 as part of a new Agency-funded 

study (Brooks et al., 2009). These new communities were targeted using the same procedures integral to 

the biological review process and the use of NTL 2009-G40 targeting areas of potential community areas 

to be avoided by impacting oil and gas activities. There is no reason to expect an increased vulnerability 

of these deep communities to cumulative impacts. 

A blowout at the seafloor could resuspend large quantities of bottom sediments and even create a 

large crater, destroying any organisms in the area. Structure removals and other bottom-disturbing 

activities could resuspend bottom sediments, but not at magnitudes as great as blowout events. Subsea 

structure removals are not expected in water depths >800 m (2,625 ft), in accordance with 30 CFR 250. 

The distance of separation provided by adherence to the guidelines of NTL 2009-G40 would protect 

nonchemosynthetic communities from sedimentation effects of deepwater blowouts. It is reported that 
Description of the Environment and Impact Analysis 4-193 

chemically dispersed surface oil from the DWH event remained in the top 6 m (20 ft) of the water column 

where it mixed with surrounding waters and biodegraded (Lubchenco et al., 2010). Data from other 

studies on dispersant usage on surface plumes indicate that a majority of the dispersed oil remained in the 

top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (7 ft) (McAuliffe et al., 

1981a). Therefore, oil spills on the sea surface are expected to have little-to-no effect on deepwater 

communities. 

Subsea oil plumes resulting from a seafloor blowout could affect sensitive deepwater communities. 

This is especially true if dispersants are applied at depth. A recent report documents damage to a 

deepwater coral community in an area that oil plume models predicted as the direction of travel for subsea 

oil plumes from the DWH event. Results are still pending but it appears that a coral community about 

15 m x 40 m (50 ft x 130 ft) in size was severely damaged, possibly the result of oil impacts (USDOI, 

BOEMRE, 2010j). Such blowouts are rare and may not release catastrophic quantities of oil. Oil that is 

released would be carried in whatever direction the water currents flow. This directional flow could only 

affect seafloor habitats that are downstream from the source. Sensitive deepwater communities appear to 

be widely scattered and not as rare as previously expected. Recent BOEMRE analyses of seafloor 

remote-sensing data indicate over 15,000 locations in the deep GOM that represent potential hard-bottom 

habitats. While it is likely that any subsea oil plume traveling more than a few miles on the deep seafloor 

would encounter at least one of these potential habitats, it would result in a localized effect that is not 

expected to alter the wider population of the GOM. 

In cases where high-density communities are subjected to greatly dispersed cumulative discharges or 

suspended sediments, the impacts are most likely to be sublethal in nature and limited in areal extent. The 

impacts to ecological function of high-density communities would be minor; minor impacts to ecological 

relationships with the surrounding benthos would also be likely. 

Because of the great water depths, treated sanitary wastes and produced waters are not expected to 

have any adverse cumulative impacts to any deepwater benthic communities. These effluents would 

undergo a great deal of dilution and dispersion before reaching the bottom, if ever. 

Oil and chemical spills (potentially from non-OCS-related activities) are not considered to be a 

potential source of measurable impacts on any deepwater communities because of water depth. Oil spills 

from the surface would tend to float. Oil discharges at depth or on the bottom would tend to rise in the 

water column and similarly not impact the benthos unless dispersants are applied at depth. 

Deepwater coral and other hard-bottom communities not associated with nonchemosynthetic 

communities are also expected to be protected from cumulative impacts by general adherence to guidance 

described in NTL 2009-G40 and the shallow hazards NTL 2008-G05 due to the avoidance of areas 

represented as hard bottom on surface anomaly maps derived from 3D seismic records (USDOI, MMS, 

2008c and 2009c). Biological reviews are performed on all deepwater plans (exploration and production) 

and pipeline applications, which include an analysis of maps and the avoidance of hard-bottom areas that 

are also one of several important indicators for the potential presence of nonchemosynthetic communities. 

Summary and Conclusion 

Cumulative impacts to deepwater communities in the Gulf of Mexico from sources other than OCS 

activities are considered negligible. The most serious, impact-producing factor threatening 

nonchemosynthetic communities is physical disturbance of the seafloor, which could destroy the 

organisms of these communities. Such disturbance would most likely come from those OCS-related 

activities associated with pipelaying, anchoring, structure emplacement, and seafloor blowouts. Drilling 

discharges and resuspended sediments have a potential to cause minor, mostly sublethal impacts to 

nonchemosynthetic communities, but substantial accumulations could result in more serious impacts. 

Seafloor disturbance is considered to be a threat only to the high-density communities; widely distributed 

low-density communities would not be at risk. Possible catastrophic oil spills due to seafloor blowouts 

have the potential to devastate localized deepwater benthic habitats. However, these events are rare and 

would only affect a small portion of the sensitive benthic habitat in the GOM. Recent analyses reveal 

over 15,000 possible hard-bottom locations across the deepwater GOM. However, because the guidance 

provided in NTL 2009-G40 describes required surveys and avoidance prior to drilling or pipeline 

installation, the risk would be greatly reduced. New studies have refined predictive information and 

confirmed the effectiveness of these provisions throughout all depth ranges of the Gulf of Mexico 
4-194 Central Planning Area Supplemental EIS 

(Brooks et al., 2009). With the dramatic success of this project, confidence is increasing regarding the 

use of geophysical signatures for the prediction of nonchemosynthetic communities. 

Activities unrelated to the OCS Program include fishing and trawling. Because of the water depths in 

these areas (>300 m; 984 ft) and the low density of potentially commercially valuable fishery species, 

these activities are not expected to impact deepwater benthic comminutes. Regionwide and even global 

impacts from CO2 build-up and proposed methods to sequester carbon in the deep sea (e.g., ocean 

fertilization) are not expected to have major impacts to deepwater habitats in the near future. More 

distant scenarios could include severe impacts. 

The activities considered under the cumulative scenario are expected to cause little damage to the 

ecological function or biological productivity of the widespread, low-density deepwater communities. 

The rarer, widely scattered, high-density, Bush Hill-type communities could experience isolated minor 

impacts from drilling discharges or resuspended sediments, with recovery expected within several years, 

but even minor impacts are not expected. Major impacts to localized benthic habitat are possible in the 

event of a catastrophic blowout on the seafloor, but the probability of this occurring is low. If physical 

disturbance (such as anchor damage) or extensive burial by muds and cuttings were to occur to highdensity, Bush Hill-type communities, impacts could be severe, with recovery time as long as 200 years 

for mature communities. There is evidence that substantial impacts on these communities would 

permanently prevent reestablishment. The severity of such an impact is such that there would be 

incremental losses of productivity, reproduction, community relationships, overall ecological functions of 

the community, and incremental damage to ecological relationships with the surrounding benthos. The 

possible impacts to these communities are decreased through BOEMRE’s biological review process and 

the use of NTL 2009-G40, which physically distances petroleum-producing activities from sensitive 

deepwater benthic communities. The incremental contribution of the CPA proposed action to cumulative 

impacts is expected to be slight and to result from the effects of the possible impacts caused by physical 

disturbance of the seafloor and minor impacts from sediment resuspension or drill cutting discharges. 

Adverse impacts would be limited but not completely eliminated by adherence to guidelines in NTL 

2009-G40. 

4.1.1.11. Marine Mammals 

The BOEMRE has reexamined the analysis of the 29 species of marine mammals occurring in the 

Gulf of Mexico presented in the Multisale EIS and the 2009-2012 Supplemental EIS, based on the 

additional information presented below and in consideration of the DWH event. No substantial new 

information was found that would alter the impact conclusion for marine mammals presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. 

Routine events related to the CPA proposed action, particularly when mitigated as required by BOEMRE, 

are not expected to have long-term adverse effects on the size and productivity of any marine mammal 

species or populations in the northern Gulf of Mexico. Characteristics of impacts from accidental events 

depend on chronic or acute exposure, resulting in harassment, harm, or mortality to marine mammals, 

while exposure to dispersed hydrocarbons is likely to result in sublethal impacts. The effects of the 

incremental contribution of the CPA proposed action, combined with non-OCS activities, may be 

deleterious to cetaceans occurring in the Gulf of Mexico. Biological significance of any mortality would 

depend, in part, on the size and reproductive rates of the affected stocks, as well as the number, age, and 

size of animals affected. 

4.1.1.11.1. Description of the Affected Environment 

A detailed description of marine mammals can be found in Chapter 3.2.3 of the Multisale EIS. 

Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.6 of the 2009-2012 Supplemental EIS. The following 

information is a summary of the resource description incorporated from the Multisale EIS and the 2009-
Description of the Environment and Impact Analysis 4-195 

2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

Twenty-nine species of marine mammals occur in the Gulf of Mexico (Davis et al., 2000). The Gulf 

of Mexico’s marine mammals are represented by members of the taxonomic order Cetacea, which is 

divided into the suborders Mysticeti (i.e., baleen whales) and Odontoceti (i.e., toothed whales), as well as 

the order Sirenia, which includes the manatee and dugong. Within the Gulf of Mexico, there are 28 

species of cetaceans (7 mysticete and 21 odontocete species) and 1 sirenian species, the manatee 

(Jefferson et al., 1992) (Table 4-2). The abundance estimates from Table 4-2 are from NMFS’s Gulf of 

Mexico Marine Mammal Stock Assessments (Waring, 2009). The best available stock assessment for 

manatees, which are under the jurisdiction of FWS, is cited from the Manatee Synoptic Aerial Survey 

Data (Florida Fish and Wildlife Conservation Commission, 2011). Seven remaining cetaceans (6 

mysticete species—northern right whale, blue whale, fin whale, sei whale, minke whale, humpback whale 

and 1 odontocete species—Sowerby’s beaked whale) have been observed in the GOM in the past, and 

therefore, there are stock assessments for these species. However, they are not considered resident GOM 

species and are therefore not included in Table 4-2. Chapter 3.2.3 of the Multisale EIS and Chapter 4.1.6 

of the 2009-2012 Supplemental EIS provide further detail. 

The most current and best available count of the Florida manatee population is 4,834 animals, based 

on a synoptic survey in January 2011 of warm-water refuges and adjacent areas (Florida Fish and Wildlife 

Conservation Commission, 2011). 

The DWH event and resulting oil spill in Mississippi Canyon Block 252 and related spill-response 

activities may have impacted marine mammals that come into contact with oil and remediation efforts. 

The best available information does not provide a complete understanding of the effects of the spilled oil 

and active response/cleanup activities on the affected marine mammal environment. For the latest 

available information on oiled or affected marine mammals documented in the area, event response, and 

daily maps of the current location of spilled oil, see RestoreTheGulf.gov (2010c). More detail on the 

potential range of effects to marine mammals from contact with spilled oil can be found in St. Aubin and 

Geraci (1990) and on the NMFS Office of Protected Resources website (http://www.nmfs.noaa.gov/pr/

health/oilspill/mammals.htm). 

A similar yet not comparable blowout of the Ixtoc I offshore drilling rig in the Bay of Campeche, 

Mexico on June 3, 1979, resulted in the release of 500 thousand metric tons (140 million gallons) and 

transport of this oil into the Gulf of Mexico (ERCO, 1982). The effect on marine mammals was 

undetermined. 

Threatened and Endangered Species 

Five baleen cetaceans (the northern right, blue, fin, sei, and humpback whales), one toothed cetacean 

(the sperm whale), and one sirenian (the West Indian manatee) occur in the Gulf of Mexico and are listed 

as endangered under the Endangered Species Act of 1973. The sperm whale is common in oceanic waters 

of the northern Gulf of Mexico and appears to be a resident species, while the baleen whales are 

considered rare or extralimital in the Gulf of Mexico (Würsig et al., 2000). The life history, population 

dynamics, status, distribution, behavior, and habitat use of baleen and toothed whales can be found in 

Chapters 3.2.3.1.1 and 3.2.3.1.2 of the Multisale EIS, respectively. 

The West Indian manatee (Trichechus manatus) typically inhabits only coastal marine, brackish, and 

freshwater areas. The distribution, feeding habits, habitat use, and population estimates of manatees can 

be found in Chapter 3.2.3.1.3 of the Multisale EIS. 

Additional research was conducted to investigate recently available information since completion of 

the Multisale EIS and the 2009-2012 Supplemental EIS. Palka and Johnson (2007) present the results of 

a study that collected the dive patterns of sperm whales in the Atlantic Ocean to compare them with the 

dive patterns and social structure of sperm whales in the Gulf of Mexico. The study started a baseline of 

line transect, photo-identification, oceanographic, and genetic data for the Atlantic sperm whale. 

Compared with the Mississippi River Delta in the Gulf of Mexico, parts of the Atlantic Ocean may serve 

as a control population of sperm whales with little exposure to sounds of oil- and gas-related activities. 

The study found that Gulf of Mexico sperm whales follow a foraging and socializing cycle similar to that 

seen for the North Atlantic whales, but North Atlantic sperm whales dive significantly deeper (average 

934 m (3,064 ft) compared with 639 m (2,096 ft) for Gulf of Mexico whales) when foraging (Palka and 
4-196 Central Planning Area Supplemental EIS 

Johnson, 2007). Jochens et al. (2008) published a synthesis of work conducted as the Sperm Whale 

Seismic Study in the Gulf of Mexico. Data from this study confirm that the GOM sperm whales 

constitute a genetically distinct stock from other Atlantic sperm whale stocks. 

The NOAA recently published a final recovery plan for the sperm whale (USDOC, NMFS, 2010b), 

and current threats to sperm whale populations worldwide are discussed. Threats are defined as “any 

factor that could represent an impediment to recovery” and these include fisheries interactions, 

anthropogenic noise, vessel interactions, contaminants and pollutants, disease, injury from marine debris, 

research, predation and natural mortality, direct harvest, competition for resources, loss of prey base due 

to climate change and ecosystem change, and cable laying. In the GOM, the impacts from many of these 

threats are identified as either low or unknown. 

Recent Consultation 

As mandated by the ESA, BOEMRE consulted with NMFS and FWS on possible and potential 

impacts from the CPA or WPA proposed action on endangered/threatened species and designated critical 

habitat under their jurisdiction. A biological assessment was prepared for each consultation. The action 

area analyzed in the biological assessments included the lease sale areas addressed in this Supplemental 

EIS. 

The formal ESA consultation with NMFS was concluded with receipt of the Biological Opinion on 

July 3, 2007 (USDOC, NMFS, 2007b). The Biological Opinion concludes that the proposed lease sales 

and associated activities in the Gulf of Mexico in the current 5-Year Program are not likely to jeopardize 

the continued existence of threatened and endangered species under NMFS jurisdiction or destroy or 

adversely modify designated critical habitat. The following information was present in the Biological 

Opinion, but not in the Multisale EIS. Based on NMFS’s surveys, opportunistic sightings, and stranding 

records, sperm whales in the Gulf of Mexico occur year-round. Sperm whales appear to favor water 

depths of about 1,000 m (3,281 ft) and appear to be concentrated in at least two geographic regions of the 

northern Gulf of Mexico: (1) an area off the Dry Tortugas and (2) offshore of the Mississippi River Delta 

(Maze-Foley and Mullin, 2006). However, distribution also appears influenced by occurrence and 

movement of cyclonic/anticyclonic currents in the Gulf of Mexico. The informal ESA consultation with 

FWS was concluded with a letter dated September 14, 2007. The FWS concurred with the BOEMRE 

determination that proposed actions of the current 5-Year Program were not likely to adversely affect the 

threatened/endangered species or designated critical habitat under FWS jurisdiction. 

The extent and scope of the spill resulting from the DWH event represents new information not 

assessed in the existing ESA Section 7 consultation in the GOM under the current 5-Year Program. As a 

result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing GOM 

Multisale EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE 

on September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. The existing 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

Nonendangered Species 

One baleen cetacean (Bryde’s whale) and 20 toothed cetaceans (including beaked whales and 

dolphins) occur in the Gulf of Mexico. The life history, population dynamics, status, distribution, 

behavior, and habitat use of the nonendangered baleen and toothed whales can be found in Chapters 

3.2.3.2.1 and 3.2.3.2.2 of the Multisale EIS, respectively. 

Factors Influencing Cetacean Distribution and Abundance 

The distribution and abundance of cetaceans within the northern Gulf of Mexico is strongly 

influenced by various mesoscale oceanographic circulation patterns. These patterns are primarily driven 

by river discharge (primarily the Mississippi/Rivers), wind stress, and the Loop Current and its derived 

circulation phenomena. Circulation on the continental shelf is largely wind-driven, with localized effects 
Description of the Environment and Impact Analysis 4-197 

from freshwater (i.e., river) discharge. Beyond the shelf, mesoscale circulation is largely driven by the 

Loop Current in the eastern Gulf of Mexico. Approximately once or twice a year, the Loop Current sheds 

anticyclonic eddies (also called warm-core rings). Anticyclones are long-lived, dynamic features that 

generally migrate westward and transport large quantities of high-salinity, nutrient-poor water across the 

near-surface waters of the northern Gulf of Mexico. These anticyclones, in turn, spawn cyclonic eddies 

(also called cold-core rings) during interaction with one another and upon contact with topographic 

features of the continental slope and shelf edge. These cyclones contain and maintain high concentrations 

of nutrients and stimulate localized production (Davis et al., 2000). In the north-central Gulf of Mexico, 

the relatively narrow continental shelf south of the Mississippi River Delta may be an additional factor 

affecting cetacean distribution (Davis et al., 2000). Outflow from the mouth of the Mississippi River 

transports large volumes of low-salinity, nutrient-rich water southward across the continental shelf and 

over the slope. River outflow also may be entrained within the confluence of a cyclone-anticyclone eddy 

pair and transported beyond the continental slope. Marine predators such as the bottlenose dolphin focus 

their foraging efforts on these abundant prey locations to improve overall efficiency and reduce energy 

costs (Bailey and Thompson, 2010). This nutrient-rich input of water leads to a localized deepwater 

environment with enhanced productivity and may explain the persistent presence of aggregations of 

sperm whales within 31 mi (50 km) of the Mississippi River Delta in the vicinity of Mississippi Canyon. 

4.1.1.11.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of the marine mammals for the CPA proposed action can be found in 

Chapter 4.2.2.1.5 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new 

information since publication of the Multisale EIS is presented in Chapter 4.1.6.2 of the 2009-2012 

Supplemental EIS. The following information is a summary of the resource description incorporated 

from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has become 

available since both documents were prepared. 

Proposed Action Analysis 

Potential effects on marine mammal species may occur from routine activities associated with the 

CPA proposed action and may be direct or indirect. The major potential impact-producing factors 

affecting marine mammals as a result of routine OCS activities include the degradation of water quality 

from operational discharges; noise generated by helicopters, vessels, operating platforms, and drillships; 

vessel traffic; explosive structure removals; seismic surveys; and marine debris from service vessels and 

OCS structures. 

Most operational discharges are diluted and dispersed when released in offshore areas and are 

considered to have sublethal effects (NRC, 1983; API, 1989; Kennicutt, 1995; Kennicutt et al., 1996). 

Any potential impacts from drilling fluids would be indirect, either as a result of impacts to prey species 

or possibly through ingestion via the food chain (Neff et al., 1989). Marine mammals generally are 

thought to be inefficient assimilators of petroleum compounds within prey (Neff, 1990). Although the 

scope and magnitude of such effects are not known, direct or indirect effects are not expected to be lethal. 

Noise associated with the CPA proposed action, including drilling noise, aircraft, and vessels, may 

affect marine mammals by eliciting a startle response or by masking other underwater sounds necessary 

for proper feeding or reproductive success. Deep-diving whales may be more vulnerable to vessel strikes 

given the longer surface period required to recover from extended deep dives. Given that NMFS has 

determined vessel strikes to be a discountable concern for sperm whales (USDOC, NMFS, 2007b), a 

deep-diving species, the faster-diving marine mammal species with less surface recovery time would be 

expected to have even less risk of vessel strikes. Although manatees have been killed by vessel strikes 

(e.g., Schiro et al., 1998), they are rare in the deepwater GOM, and consequently, the proposed activity 

should pose little, if any, risk to them. The continued presence of sperm whales in close proximity to 

some of the deepwater structures in the GOM tends to lessen the concern of permanent displacement by 

disturbances caused by activity in support of offshore drilling or production. 

The dominant source of noise from vessels is from the propeller operation, and the intensity of this 

noise is largely related to ship size and speed. Vessel noise from the proposed action will produce low 
4-198 Central Planning Area Supplemental EIS 

levels of noise, generally in the 150-170 dB re 1 μPa-m at frequencies below 1,000 Hz. Vessel noise is 

transitory and generally does not propagate at great distances from the vessel. As a result, NMFS’s 2007 

ESA Biological Opinion concluded that the effects to sperm whales from vessel noise are discountable 

(USDOC, NMFS, 2007b). The BOEMRE has proposed adherence with the guidance provided under 

NTL 2007-G04, “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting.” Compliance 

with the regulations as clarified in this NTL should negate or lessen the chance of significant impacts to 

marine mammals. 

The noise and the shadow from helicopter overflights, take-offs, and landings can cause a startle 

response and can interrupt whales and dolphins while resting, feeding, breeding, or migrating (Richardson 

et al., 1995). The Federal Aviation Administration’s Advisory Circular 91-36D (September 17, 2004) 

encourages pilots to maintain higher than minimum altitudes over noise-sensitive areas. Guidelines and 

regulations put in place by NOAA Fisheries under the authority of the Marine Mammal Protection Act 

include provisions specifying that helicopter pilots maintain an altitude of 1,000 ft (305 m) within 300 ft 

(91 m) of marine mammals. Helicopter occurrences would be temporary and pass within seconds. 

Marine mammals are not expected to be adversely affected by routine helicopter traffic operating at 

prescribed altitudes. 

Atmospheric noise inputs, however, are negligible relative to other sources of noise that are 

propagated in water (e.g., vessel traffic and platform and drill rig operations). Noise from service-vessel 

traffic may elicit a startle and/or avoidance reaction from whales and dolphins or mask their sound 

reception. There is the possibility of short-term disruption of movement patterns and behavior, but such 

disruptions are unlikely to affect survival or productivity. The behavioral disruptions potentially caused 

by noise and the presence of service-vessel traffic will have negligible affects on cetacean populations in 

the northern Gulf of Mexico. 

Drilling activities would produce sounds transmitted into the water at intensities and frequencies that 

could be heard by cetaceans. Noise from drilling could be intermittent, sudden, and at times could be 

high intensity as operations take place. Sound from a fixed, ongoing source like an operating drillship is 

continuous. However, the distinction between transient and continuous sounds is not absolute on a 

drillship as generators and pumps operate essentially continuously, but there are occasional transient 

bangs and clangs from various impacts during operations (Richardson et al., 1995). Drilling from 

semisubmersible vessels estimated frequencies are broadband from 80 to 4,000 Hz, with an estimated 

source level of 154 dB re 1μPa at 1 m. Tones of 60 Hz had source levels of 149 dB, 181 Hz was 137 dB, 

and 301 Hz was 136 dB (Greene, 1986). The potential effects that water-transmitted noise have on 

marine mammals include disturbance (subtle changes in behavior, interruption of previous activities, or 

short- or long-term displacement), masking of sounds (calls from conspecifics, reverberations from own 

calls, and other natural sounds such as surf or predators), physiological stress, and hearing impairment. 

Individual marine mammals exposed to recurring disturbance could be negatively affected. Malme et al. 

(1986) observed the behavior of feeding gray whales in the Bering Sea during four experimental 

playbacks of drilling sounds (50-315 Hz; 21-minute overall duration and 10% duty cycle; source levels 

156-162 dB re: 1 μPa-m). In two cases for received levels 100-110 dB re: 1 μPa, there was no observed 

behavioral reaction. Avoidance behavior was observed in two cases where received levels were 110-120 

dB re: 1 μPa. These source levels are all below NMFS’s current 160-dB level B harassment threshold 

under the MMPA. 

The source levels from drilling are relatively low (154 dB and below, as cited by Greene, 1986, in 

Richardson et al., 1995), which is below the level B (behavioral) harassment threshold of 160 dB (set by 

NMFS). According to Southall et al. (2007), for behavioral responses to nonpulses (such as drill noise), 

data indicate considerable variability in received levels associated with behavioral responses. Contextual 

variables (such as novelty of the sound to the marine mammal and operation features of the sound source) 

appear to have been at least as important as exposure level in predicting response type and magnitude. 

While there is some data from the Arctic on baleen whales, there is little data on the behavioral responses 

of marine mammals in the Gulf of Mexico from the sound of drilling. Southall et al. (2007) summarized 

the existing research, stating that the probability of avoidance and other behavioral affects increases when

received levels increase from 120 to 160 dB. Marine mammals may exhibit some avoidance behaviors, 

but their behavioral or physiological responses to noise associated with the proposed project, however, are 

unlikely to have population-level impacts to marine mammals in the northern Gulf of Mexico. 
Description of the Environment and Impact Analysis 4-199 

The BOEMRE published a Programmatic EA on decommissioning operations (USDOI, MMS, 2005) 

that, in part, addresses the potential impacts of explosive and nonexplosive-severance activities on OCS 

resources, particularly upon marine mammals and sea turtles. Pursuant to 30 CFR 250 Subpart Q, 

operators must obtain a permit from BOEMRE before beginning any platform removal or well-severance 

activities. During the review of the permit applications, terms and conditions of the August 2006 NMFS 

Biological Opinion/Incidental Take Statement are implemented for the protection of marine protected 

species and to reduce possible impacts from any potential activities resulting from the proposed lease sale. 

The NMFS has issued regulations (50 CFR 216) under the MMPA for “Taking Marine Mammals 

Incidental to the Explosive Removal of Offshore Structures in the Gulf of Mexico.” 

In 30 CFR 250 Subpart B, BOEMRE requires operators of Federal oil and gas leases to meet the 

requirements of ESA and MMPA. The regulations outline the environmental, monitoring, and mitigation 

information that operators must submit with plans for exploration, development, and production. This 

regulation requires OCS activities to be conducted in a manner that is consistent with the provisions of 

ESA and MMPA. 

Seismic operations have the potential to harm marine mammals in close proximity to firing airgun 

arrays, especially if they are directly beneath airguns when surveying begins. The proposed Protected 

Species Stipulation and several suggested mitigation measures, including onboard observers and airgun 

shut-downs for whales in the exclusion zone, included in NTL 2007-G02, “Implementation of Seismic 

Survey Mitigation Measures and Protected Species Observer Program,” minimize the potential of harm 

from seismic operations to marine mammals. The proposed adherence with the guidance provided under 

NTL 2007-G02 should negate or lessen the chance of significant impacts to marine mammals. 

Many types of plastic materials end up as solid waste during drilling and production operations. 

Some of this material is accidentally lost overboard where cetaceans could consume it or become 

entangled in it. The incidental ingestion of marine debris and entanglement could adversely affect marine 

mammals. Industry has made good progress in debris management on vessels and offshore structures in 

the last several years. The proposed adherence with the guidance provided under NTL 2007-G03, 

“Marine Trash and Debris Awareness and Elimination,” appreciably reduces the likelihood of marine 

mammals encountering marine debris from the proposed activity. 

Summary and Conclusion 

In this Supplemental EIS, BOEMRE has reexamined the analysis for marine mammals presented in 

the Multisale EIS and the 2009-2012 Supplemental EIS, and has considered the recent reports cited above 

and other new information. The extent and scope of the spill resulting from the DWH event represents 

new information not assessed in the existing ESA Section 7 consultation in the GOM on the current 5-

Year Program. As a result of this new information, BOEMRE reinitiated ESA Section 7 consultation on 

the existing GOM Multisale EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a 

letter to BOEMRE on September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 

2010. However, NMFS and FWS have placed this consultation on hold given the environmental baseline 

needing to be updated by the results of the NRDA process. The NRDA data have yet to be released. The 

existing consultations will remain in effect until the reinitiated consultations are completed. The existing 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

Mysticetes, as low-frequency hearing specialists, are the species groups most likely to be susceptible 

to impacts from the low-frequency nonpulse sound (intermittent or continuous), given that their hearing 

ranges overlap most closely with the noise frequencies produced from drilling (Southall et al., 2007). 

However, most mysticete species that may occur in the GOM (i.e., North Atlantic right, blue, fin, sei, 

humpback, and minke whales) are considered either “extralimital,” “rare,” or “uncommon”; however, a 

small population of Bryde’s whales is common in the eastern GOM (Würsig et al., 2000; Waring et al., 

2009). Because of the geographic scope of the proposed action, the presence of these species within the 

action area is unlikely. 

The remaining marine mammal species in the GOM (e.g., sperm whales, dwarf or pygmy sperm 

whales, and dolphins) are considered mid-frequency hearing specialists with hearing ranges that slightly 

overlap with sound frequencies produced from drilling noise (Southall et al., 2007). It is expected that 

there will be some overlap in the frequencies of the drill source and the hearing thresholds of the marine 
4-200 Central Planning Area Supplemental EIS 

mammals present in the GOM. Greene (1986) estimated the broadband frequencies of semisubmersible 

drill vessels to be from 80 to 4,000 Hz, with an estimated source level of 154 dB re 1μPa at 1 m. Tones 

of 60 Hz had source levels of 149 dB, 181 Hz was 137 dB, and 301 Hz was 136 dB. Wartzok and Ketten 

(1999) stated that bottlenose dolphins have hearing thresholds ranging from less than 5 kHz to over 100 

kHz. Ridgway and Carder (2001) found, through auditory brainstem analysis, that pygmy sperm whales 

have thresholds from 90 to 150 kHz. Gordon et al. (1996) found that a stranded sperm whale had lower 

hearing limits at around 100 Hz, while Ridgway and Carder (2001) found that a sperm whale calf had best 

hearing sensitivity between 5 and 20 kHz. Since there is some overlap in the sound levels produced and 

hearing thresholds of marine mammals, there is the potential for the drilling noise produced to cause 

auditory and nonauditory effects, permanent threshold shift, temporary threshold shift, behavioral 

changes, or masking, but it is expected to be limited. However, these levels are under the NMFS 160-dB 

level B harassment under the MMPA. 

The NMFS sets the 180-dB, root-mean-squared isopleth where on-set of auditory injury or mortality 

(level A harassment) to cetaceans may occur. Southall et al. (2007) suggest this level should rather be at 

230 dB root-mean-squared for a nonpulsed sound, such as drilling noise. Richardson et al. (1995) cited 

Greene (1986) and stated that drilling from semisubmersible vessels have estimated broadband 

frequencies from 80 to 4,000 Hz, with an estimated source level of 154 dB re 1μPa at 1 m. Tones of 

60 Hz have source levels of 149 dB, while 181 Hz have source levels of 137 dB and 301 Hz have source 

levels of 136 dB. These source levels all fall below the 180-dB level A harassment isopleths. 

Because of the mitigations described in the above analysis, routine activities (e.g., operational 

discharges, noise, vessel traffic, and marine debris) related to the proposed CPA lease sale are not 

expected to have long-term adverse effects on the size and productivity of any marine mammal species or 

population in the northern GOM. Lethal effects are most likely to be from chance collisions with OCS 

service vessels or ingestion of any accidentally released plastic materials. Most routine OCS activities are 

expected to have sublethal effects. In conclusion, the scope, timing, and transitory nature of the proposed 

action and the mitigation and monitoring requirements in place, the noise related to the CPA proposed 

action is not expected to result in permanent threshold shift, temporary threshold shift, behavioral change, 

masking, or nonauditory effects to marine mammals in the GOM that would rise to the level of 

significance. 

4.1.1.11.3. Impacts of Accidental Events 

A detailed impact analysis of marine mammals for the CPA proposed action can be found in Chapter 

4.4.5 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information 

since publication of the Multisale EIS is presented in Chapter 4.1.6.3 of the 2009-2012 Supplemental EIS. 

The following information is a summary of the resource description incorporated from the Multisale EIS 

and the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

Proposed Action Analysis 

Potential effects on marine mammal species may occur from accidental activities associated with the 

CPA proposed action and may be direct or indirect. The major potential impact-producing factors 

affecting marine mammals in the GOM as a result of accidental OCS activities include accidental 

blowouts, oil spills, and spill-response activities. Characteristics of impacts (i.e., acute vs. chronic 

impacts) depend on the magnitude, frequency, location, and date of accidents; characteristics of spilled 

oil; spill-response capabilities and timing; and various meteorological and hydrological factors. Chronic 

or acute exposure may result in harassment, harm, or mortality to marine mammals. Studies have shown 

varying results. Marine mammals made no apparent attempt to avoid spilled oil in some cases (Smultea 

and Würsig, 1995); however, marine mammals have been observed apparently detecting and avoiding 

slicks in other reports (Geraci and St. Aubin, 1990). Exposure to hydrocarbons persisting in the sea 

following the dispersal of a large oil slick is likely to result in sublethal impacts (e.g., decreased health, 

reproductive fitness, and longevity; and increased vulnerability to disease) to marine mammals. 

Activities considered under this activity could affect protected sirenians (manatees) as well. 

Manatees are generally extralimital in western Louisiana and are rare in waters of the CPA, but they have 

occurred in the warm waters of Lake Pontchartrain (Louisiana Dept. of Wildlife and Fisheries, 2005). 
Description of the Environment and Impact Analysis 4-201 

Protected marine mammals could be impacted by marine debris, contaminant spills and spill-response 

activities, vessel traffic, noise, seismic surveys, explosive structure removals, commercial fishing, capture 

activities, and pathogens. 

The oil from an oil spill can adversely affect cetaceans by causing soft tissue irritation, fouling of 

baleen plates, respiratory stress from inhalation of toxic fumes, food reduction or contamination, direct 

ingestion of oil and/or tar, and temporary displacement from preferred habitats. The long-term impacts to 

marine mammal populations are poorly understood but could include decreased survival and lowered 

reproductive success. The range of toxicity and degree of sensitivity to oil hydrocarbons and the effects 

of cleanup activities on cetaceans are unknown. One assumption concerning the use of dispersants is that 

chemical dispersion of oil will considerably reduce the impacts to seabirds and aquatic mammals, 

primarily by reducing their exposure to petroleum hydrocarbons (French-McCay 2004; NRC, 2005). 

Chemical dispersant application during an oil spill may lower the amount of oil to which a bird or aquatic 

mammal is exposed, while increasing the potential loss of the insulative properties of feathers or fur 

through the reduction of surface tension at the feather/fur-water interface (NRC, 2005). 

Impacts from the dispersants are unknown but may have similar irritants to tissues and sensitive 

membranes as they are known to have had on seabirds and marine mammals (NRC, 2005). There have 

been no experimental studies and only a handful of observations suggesting that oil has harmed any 

manatees (St. Aubin and Lounsbury, 1990). Types of impacts to manatees and dugongs from contact 

with oil include (1) asphyxiation due to inhalation of hydrocarbons, (2) acute poisoning due to contact 

with fresh oil, (3) lowering of tolerance to other stress due to the incorporation of sublethal amounts of 

petroleum components into body tissues, (4) nutritional stress through damage to food sources, and (5) 

inflammation or infection and difficulty eating due to oil sticking to the sensory hairs around their mouths 

(Preen, 1989, in Sadiq and McCain, 1993; Australian Maritime Safety Authority, 2003). For a population 

whose environment is already under great pressure, even a localized incident could be significant (St. 

Aubin and Lounsbury, 1990). Spilled oil might affect the quality or availability of aquatic vegetation, 

including seagrasses, upon which manatees feed. 

The ESA (16 U.S.C. 1631 et seq.), as amended (43 U.S.C. 1331 et seq.), establishes a national policy 

designed to protect and conserve threatened and endangered species and the ecosystems upon which they 

depend. The ESA is administered by FWS and NMFS. Section 7 of the ESA governs interagency 

cooperation and consultation. Under Section 7, BOEMRE consults with FWS and NMFS to ensure that 

OCS activities under BOEMRE jurisdiction do not jeopardize the continued existence of threatened or 

endangered species and/or result in adverse modification or destruction of their critical habitat. 

The formal consultation with NMFS was concluded with receipt of the Biological Opinion dated 

June 29, 2007, and received by BOEMRE on July 3, 2007 (USDOC, NMFS, 2007b). The Biological 

Opinion concludes that the proposed lease sale and associated activities in the GOM during the current 

5-Year Program, which includes the CPA proposed action, are not likely to jeopardize the continued 

existence of threatened and endangered species under NMFS jurisdiction or destroy or adversely modify 

designated critical habitat. 

Section 7(b)(4)(c) of the ESA specifies that, in order to provide an incidental take statement for an 

endangered or threatened species of marine mammal, the taking must be authorized under Section 

101(a)(5) of the Marine Mammal Protection Act (MMPA). Since no incidental take of listed marine 

mammals is expected or has been authorized under Section 101(a)(5)(A) of the MMPA and/or its 1994 

amendments (see ESA Section 7(b)(4)(C)), no statement on incidental take of endangered whales is 

provided and no take is authorized. Nevertheless, BOEMRE must immediately notify (within 24 hours, if 

communication is possible) NMFS’s Office of Protected Resources should a take of a listed marine 

mammal occur. 

On December 26, 2002, this Agency petitioned NMFS for rulemaking under the MMPA for the 

taking, by harassment, of sperm whales incidental to the oil and gas industry’s seismic surveys to 

discover oil and gas deposits offshore in the GOM. The NMFS published a notice of receipt of the 

application on March 3, 2003 (68 FR 9991). This Agency then submitted a revised petition on 

September 26, 2004, to include the incidental take of other species of marine mammals. On July 30, 

2004, this Agency completed its final programmatic EA on the action. On November 18, 2004, NMFS 

published a Notice of Intent to Prepare an EIS, a notice of public meetings, and a request for scoping 

comments. The BOEMRE and NMFS are working together as co-lead agencies on the EIS and, due to 

lengthy delays in the MMPA process, BOEMRE is currently updating and revising its previously 
4-202 Central Planning Area Supplemental EIS 

submitted petition for MMPA rulemaking. Following issuance of such regulations under the MMPA, 

NMFS will amend their opinion to include any authorized incidental take of sperm whales, as may be 

appropriate at that time. 

The NMFS believes that a small number of listed species would experience adverse effects as the 

result of exposure to a large oil spill or ingestion of accidentally spilled oil over the lifetime of the 

proposed action. As per the 2007 Biological Opinion, NMFS stated that spilled oil resulting from the 

proposed sales (Lease Sale 216/222 included) could cause up to 11 nonlethal takes of sperm whales over 

the 40-year lifetime of the proposed lease sale. However, NMFS is not including an incidental take 

statement for the incidental take of listed species due to oil exposure. Incidental take, as defined at 50 

CFR 402.02, refers only to takings that result from an otherwise lawful activity. The Clean Water Act (33 

U.S.C. 1251 et seq.) as amended by the Oil Pollution Act of 1990 (33 U.S.C. 2701 et seq.) prohibits 

discharges of harmful quantities of oil, as defined at 40 CFR 110.3, into waters of the United States. 

Therefore, even though the Biological Opinion considered the effects on listed species by oil spills that 

may result from the CPA proposed action, those takings that would result from an unlawful activity (i.e., 

oil spills) are not specified in this Incidental Take Statement and have no protective coverage under 

Section 7(o)(2) of the ESA. 

The DWH event and resulting oil spill in Mississippi Canyon Block 252 and related spill-response 

activities may impact marine mammals that come into contact with oil and remediation efforts. The best 

available information does not provide a complete understanding of the effects of the spilled oil and 

active response/cleanup activities on the affected marine mammal environment. For the latest available 

information on oiled or affected marine mammals documented in the area, event response, and daily maps 

of the current location of spilled oil, see RestoreTheGulf.gov (2010c). More detail on the potential range 

of effects to marine mammals from contact with spilled oil can be found in Geraci and St. Aubin (1990) 

and on the NMFS Office of Protected Resources website (http://www.nmfs.noaa.gov/

pr/health/oilspill/mammals.htm). The NRDA-related efforts are ongoing and the results will be 

incorporated into future environmental analyses. 

A similar yet not comparable blowout of the Ixtoc I offshore drilling rig in the Bay of Campeche, 

Mexico on June 3, 1979, resulted in the release of 500 thousand metric tons (140 million gallons) and 

transport of this oil into the Gulf of Mexico (ERCO, 1982). The effect on marine mammals was 

undetermined. 

Summary and Conclusion 

The BOEMRE has reexamined the analysis for marine mammals presented in the Multisale EIS and 

the Supplemental EIS, and has considered the recent reports cited above and other new information. The 

extent and scope of the spill resulting from the DWH event represents new information not assessed in the 

existing ESA Section 7 consultation in the GOM under the current 5-Year Program. As a result of this 

new information, BOEMRE reinitiated ESA Section 7 consultation on the existing GOM Multisale EIS 

with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE on 

September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. The existing 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

In the event of a catastrophic spill similar to the DWH event, any substantive impact to marine 

mammals is very unlikely because the potential impacts from a catastrophic spill would be similar to the 

aforementioned routine and accidental issues. However, despite the recent DWH event, historical trends 

in the GOM indicate that catastrophic spill events are not likely to occur as a result of drilling and 

temporary abandonment. 

4.1.1.11.4. Cumulative Impacts 

A detailed impact analysis of marine mammals for the CPA proposed action can be found in Chapter 

4.5.5 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information 

since publication of the Multisale EIS is presented in Chapter 4.1.6.4 of the 2009-2012 Supplemental EIS. 
Description of the Environment and Impact Analysis 4-203 

The following information is a summary of the resource description incorporated from the Multisale EIS 

and the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

Proposed Action Analysis 

The major potential impact-producing factors affecting protected marine mammals in the GOM as a 

result of cumulative OCS activities include marine debris, contaminant spills and spill-response activities, 

vessel traffic, noise, seismic surveys, explosive structure removals, commercial fishing, capture activities, 

and pathogens. Activities considered under the cumulative scenario could affect protected cetaceans and 

sirenians (manatees). Manatees, known to have occurred in the warm waters of Lake Pontchartrain in the 

weeks before Hurricane Katrina (Louisiana Dept. of Wildlife and Fisheries, 2005), are generally 

extralimital in western Louisiana. 

The proposed action may cumulatively affect protected cetaceans when viewed in light of the DWH 

event and associated cleanup activities. Marine mammals could be impacted by oil and gas leasing, 

exploration, development, and production activities including the degradation of water quality resulting 

from operational discharges; vessel traffic; noise generated by platforms, drillships, helicopters and 

vessels; seismic surveys; explosive structure removals; oil spills; oil-spill-response activities; loss of 

debris from service vessels and OCS structures; commercial fishing; capture and removal; and pathogens. 

The cumulative impact on marine mammals is expected to result in a number of chronic and sporadic 

sublethal effects (i.e., behavioral effects and nonfatal exposure to or intake of OCS-related contaminants 

or discarded debris) that may stress and/or weaken individuals of a local group or population and 

predispose them to infection from natural or anthropogenic sources (Harvey and Dahlheim, 1994). 

Few deaths are expected from chance vessel collisions, ingestion of plastic material, commercial 

fishing, and pathogens. Disturbance (noise from vessel traffic and drilling operations, etc.) and/or 

exposure to sublethal levels of toxins and anthropogenic contaminants may stress animals, weaken their 

immune systems, and make them more vulnerable to parasites and diseases that normally would not be 

fatal (Harvey and Dahlheim, 1994). The net result of any disturbance will depend upon the size and 

percentage of the population likely to be affected, the ecological importance of the disturbed area, the 

environmental and biological parameters that influence an animal’s sensitivity to disturbance and stress, 

or the accommodation time in response to prolonged disturbance (Geraci and St. Aubin, 1980). 

The effects of the proposed action, when viewed in light of the effects associated with other relevant 

activities, may impact marine mammals in the GOM. However, the operator is required to follow all 

existing lease stipulations and regulations as clarified by NTL’s. Because of the operator’s reaffirmed 

compliance with NTL 2007-G04 (“Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting”) and NTL 2007-G03 (“Marine Trash and Debris Awareness and Elimination”), as well as the 

limited scope, timing, and geographic location of the proposed action, effects from the proposed drilling 

activities on marine mammals will be negligible. Therefore, no significant cumulative impacts to marine 

mammals would be expected as a result of the proposed exploration activities when added to the impacts 

of past, present, or reasonably foreseeable oil and gas development in the area, as well as other activities 

in the area. 

Natural phenomenon, such as tropical storms and hurricanes, are impossible to predict, but will occur 

in the GOM. Generally, the offshore species and the offshore habitat are not expected to be severely 

affected in the long term. Species that occupy more nearshore habitats, however, may suffer more longterm impacts. The effects of recent GOM hurricanes are difficult to assess, but major impacts to GOM 

marine mammal populations have not been reported. 

Effects of the incremental contribution of the CPA proposed action, combined with non-OCS 

activities, may be deleterious to marine mammals occurring in the GOM. Biological significance of any 

mortality would depend, in part, on the size and reproductive rates of the affected stocks, as well as the 

number, age, and size of animals affected. However, potential impacts from the CPA proposed action 

activities are not expected to result in mortality. 

Summary and Conclusion 

The BOEMRE has reexamined the analysis for marine mammals presented in the Multisale EIS and 

the 2009-2012 Supplemental EIS, and has considered the recent reports cited above and other new 
4-204 Central Planning Area Supplemental EIS 

information. The GOM tropical storm activity in recent years is not expected to have altered the 

cumulative effects baseline for marine mammals. Therefore, the incremental effect of the CPA proposed 

action upon these resources is unchanged, and the description of the environmental effects of the 

proposed action upon these resources described in the Multisale EIS and the 2009-2012 Supplemental 

EIS remains unchanged. Because of the regulations, geographic location of the proposed action, and the 

low probabilities of large accidental events, the cumulative effects to marine mammal populations are 

expected to be minor. 

The extent and scope of the spill resulting from the DWH event represents new information not 

assessed in the existing ESA Section 7 consultation in the GOM under the 5-Year Program. As a result of 

this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing GOM Multisale 

EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE on 

September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. The existing 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

4.1.1.12. Sea Turtles 

The BOEMRE has reexamined the analysis for the five sea turtles species that inhabit the Gulf of 

Mexico in the Multisale EIS and the 2009-2012 Supplemental EIS based on the additional information 

presented below and in consideration of the DWH event. While information from the 5-year status 

reviews for federally listed sea turtles in the Gulf of Mexico was incorporated, there was no substantial 

new information that would alter the impact conclusion for sea turtles presented in the Multisale EIS and 

the 2009-2012 Supplemental EIS. In most foreseeable cases, exposure to hydrocarbons persisting in the 

sea following the dispersal of an oil slick would result in sublethal impacts (e.g., decreased health, 

reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information and the addition of the 181 South Area is presented in the following sections and the 2009-

2012 Supplemental EIS. A brief summary of potential impacts follows. The routine activities of the 

proposed action are unlikely to have significant adverse effects on the size and recovery of any sea turtle 

species or population in the Gulf of Mexico. Accidental events associated with the proposed action have 

the potential to impact small to large numbers of sea turtles. Populations of sea turtles in the northern 

Gulf of Mexico would be exposed to residuals of oils spilled as a result of the proposed action during 

their lifetimes. While chronic or acute exposure from accidental events may result in the harassment, 

harm, or mortality to sea turtles, in most foreseeable cases, exposure to hydrocarbons persisting in the sea 

following the dispersal of an oil slick would result in sublethal impacts. However, the incremental 

contribution of a CPA proposed action, including the 181 South Area, to the numerous cumulative 

impacts to sea turtles are not expected to be significant, especially due to mitigations currently in place. 

4.1.1.12.1. Description of the Affected Environment 

A detailed description of sea turtles can be found in Chapter 3.2.4 of the Multisale EIS. Additional 

information for the 181 South Area and any new information since the publication of the Multisale EIS is 

presented in Chapter 4.1.7 of the 2009-2012 Supplemental EIS. The following information is a summary 

of the resource description incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and 

new information that has become available since both documents were prepared. 

Five sea turtles are known to inhabit the waters of the GOM (Pritchard, 1997): the leatherback 

(endangered, listed June 2, 1970); green turtle (breeding colony populations in Florida and on the Pacific 

Coast of Mexico are listed as endangered; all others are listed as threatened, listed July 28, 1978); 

hawksbill (endangered, listed June 2, 1970); Kemp’s ridley (endangered, listed December 2, 1970); and 

loggerhead (threatened, listed July 28, 1978). These five species are all highly migratory (Table 4-3). 

Individual animals will make migrations into nearshore waters as well as other areas of the North Atlantic 
Description of the Environment and Impact Analysis 4-205 

Ocean, Gulf of Mexico, and the Caribbean Sea. All five species of sea turtles found in the Gulf of 

Mexico have been federally listed as endangered or threatened since the 1970’s. There is currently no 

critical habitat designated in the Gulf of Mexico. On February 17, 2010, NMFS and FWS were jointly 

petitioned to designate critical habitat for Kemp’s ridley sea turtles for nesting beaches along the Texas 

coast and for marine habitats in the Gulf of Mexico and Atlantic Ocean. The NMFS is currently 

reviewing the petition. 

The DWH event and related spill-response activities may impact sea turtles that come into contact 

with oil and remediation efforts. The best available information does not provide a complete 

understanding of the effects of the spilled oil and active response/cleanup activities on the affected sea 

turtle environment. For the latest available information on oiled or affected sea turtles documented in the 

area, event response (including nest relocation), and daily maps of the current location of spilled oil, see 

RestoreTheGulf.gov (2010c). More detail on the potential range of effects to sea turtles from contact with 

spilled oil can be found on the NMFS Office of Protected Resources website (http://www.nmfs.noaa.gov/

pr/health/oilspill/turtles.htm). 

A similar yet not comparable blowout of the Ixtoc I offshore drilling rig in the Bay of Campeche, 

Mexico, on June 3, 1979, resulted in the release of 500,000 metric tons (140 million gallons) and the 

transport of this oil into the Gulf of Mexico (ERCO, 1982). Of the three sea turtles found dead in the 

U.S., all had petroleum hydrocarbons in the tissues examined and there was selective elimination of 

portions of this oil, indicating chronic exposure (Hall et al., 1983). 

In August 2007, FWS and NMFS published 5-year status reviews for federally listed sea turtles in the 

Gulf of Mexico (USDOC, NMFS and USDOI, FWS, 2007a-e). A 5-year review is an ESA-mandated 

process that is conducted to ensure the listing classification of a species as either threatened or endangered 

is still accurate. Both agencies share jurisdiction for federally listed sea turtles and jointly conducted the 

reviews. After reviewing all of the best scientific and commercially available information and data, the 

agencies’ biologists recommended that the current listing classification for the five sea turtle species 

remain unchanged. 

Natural phenomenon, such as tropical storms and hurricanes, are impossible to predict, but they will 

occur in the GOM. Generally, the offshore species and the offshore habitat are not expected to be 

severely affected in the long term. However, species that occupy more nearshore habitats and those that 

use nearshore habitats for nesting may suffer more long-term impacts. Several major hurricanes have hit 

the Gulf Coast in the last several years. Storm impacts, including loss of nesting habitat, increased marine 

debris, and spilled pollutants, can be detrimental to sea turtles. Impacts from the storms to nesting 

activity can be hard to assess. Hurricane Katrina in 2005 decimated the northern Gulf Coast, including 

the Chandeleur Islands off of Louisiana/Mississippi. This barrier island chain was a significant 

loggerhead nesting site (Lohoefener et al., 1990). Very little area that would be suitable for nesting 

remains above sea level. Subsequent storms have delayed any rebuilding of the Chandeleur Islands. 

Hurricane Gustav in 2008 also occurred in areas used by sea turtles for nesting. Both the washing away 

of sand beaches and the proliferation of debris on nesting beaches can post major barriers to successful 

nesting. The late August/September timeframe of most of the recent Gulf of Mexico storms was toward 

the end of the sea turtle nesting season (generally April/May to October). Many nests had successfully 

hatched prior to storm damage (Florida Fish and Wildlife Conservation Commission, 2008). 

In response to a request by the Gulf of Mexico Fishery Management Council, NMFS issued an 

emergency closure for the bottom longline fishery in the eastern Gulf from May 18 through October 28, 

2009 (Federal Register, 2009c). This action was promulgated by recent observer data analysis that 

showed the number of sea turtle takes authorized in a 2005 Biological Opinion had been substantially 

exceeded. The affected fishery operates primarily off the west Florida shelf, which is an important sea 

turtle foraging habitat. A decline in the number of reproducing female loggerheads has been suggested as 

one of the reasons for recent declines in the annual loggerhead sea turtle nest counts in peninsular Florida. 

The bottom longline fishery takes sea turtles, including adult females, incidentally as bycatch. Further 

restrictions and/or mitigations may be required after the expiration of this closure. Although the area of 

greatest impact from this commercial fishing activity is not in the CPA, such impact to the loggerhead sea 

turtle population must be considered with cumulative impacts. Concern over declining numbers of 

loggerhead sea turtles is reflected in NMFS’s second revision of the Recovery Plan for the Northwest 

Atlantic Population of the Loggerhead Sea Turtle (Caretta caretta), which replaced the previous 1991 

report (USDOC, NMFS and USDOI, FWS, 2008). 
4-206 Central Planning Area Supplemental EIS 

Leatherback Sea Turtle 

The leatherback is the most abundant sea turtle in waters over the northern Gulf of Mexico 

continental slope (Mullin and Hoggard, 2000). The leatherback sea turtle is listed as endangered. 

Leatherbacks appear to spatially use both continental shelf and slope habitats in the Gulf of Mexico (Fritts 

et al., 1983; Collard, 1990; Davis and Fargion, 1996). Surveys suggest that the region from Mississippi 

Canyon to De Soto Canyon, especially near the shelf edge, appears to be an important habitat for 

leatherbacks (Mullin and Hoggard, 2000). Leatherbacks have been frequently sighted in the Gulf of 

Mexico during both summer and winter (Mullin and Hoggard, 2000). 

In Florida, an increase in leatherback nesting numbers from 98 nests in 1988 to 800-900 nests per 

season in the early 2000’s has been recorded. There has been a substantial increase in leatherback nesting 

in Florida since 1989 (USDOC, NMFS and USDOI, FWS, 2007a). Florida received a near record 

number of leatherback nests on beaches in 2010 (Florida Fish and Wildlife Conservation Commission, 

2010a). Although nesting is very rare on Gulf of Mexico beaches, leatherbacks occur in Gulf of Mexico 

waters. Satellite telemetry and tag returns have shown that some of the leatherbacks present in the Gulf 

of Mexico were tagged at nesting beaches in Costa Rica and Panama (USDOC, NMFS and USDOI, FWS, 

2007a). 

Critical habitat for the leatherback includes the waters adjacent to Sandy Point, St. Croix, U.S. Virgin 

Islands. There is no critical habitat designation for the leatherback sea turtle in the GOM. Ongoing 

threats to leatherbacks include ingestion of marine debris, poaching of eggs and animals, and 

entanglement in longline fishing gear. 

Green Sea Turtle 

All green sea turtle populations are listed as threatened except for the breeding populations of Florida 

and the Pacific Coast of Mexico, which are endangered. Green sea turtles are found throughout the Gulf 

of Mexico and are known to nest on Gulf of Mexico beaches, but in very small numbers. Reports of 

green turtles nesting along the Gulf Coast are infrequent. 

The east coast of Florida is one of the most important nesting areas for green turtles. Between 1989 

and 2010, the annual number of green sea turtle nests ranged from 267 to 9,091. Green turtle nests have 

increased by a factor of 10 over the last 22 years (Florida Fish and Wildlife Conservation Commission, 

2010a). 

The principal cause of past declines and extirpations of green turtle assemblages has been the overexploitation of green turtles for eggs and meat. Significant threats on green turtle nesting beaches in the 

region include beach armoring, erosion control, artificial lighting, and disturbance. Armoring of beaches 

(e.g., seawalls, revetments, rip-rap, sandbags, and sand fences) in Florida, which is meant to protect 

developed property, is increasing and has been shown to discourage nesting, even when armoring 

structures do not completely block access to nesting habitat (Mosier, 1998). 

Hawksbill Sea Turtle 

Hawksbill sea turtles were once abundant in tropical and subtropical regions. Pelagic-size individuals 

and small juveniles are not uncommon and are believed to be animals dispersing from nesting beaches in 

the Yucatán Peninsula of Mexico and farther south in the Caribbean (Amos, 1989). The hawksbill turtle 

is listed as endangered and is considered critically endangered by the International Union for the 

Conservation of Nature based on global population declines of over 80 percent during the last three 

generations (105 years) (Meylan and Donnelly, 1999). The Atlantic Coast of Florida is the only area in 

the U.S. where hawksbills nest on a regular basis. 

Hawksbills are threatened by all the factors that threaten other marine turtles, including exploitation 

for meat, eggs, and the curio trade; loss or degradation of nesting and foraging habitats; increased human 

presence; nest depredation; oil pollution; incidental capture in fishing gear; ingestion of and entanglement 

in marine debris; and boat collisions (Lutcavage et al., 1997; Meylan and Ehrenfeld, 2000). The primary 

cause of hawksbill decline has been attributed to centuries of exploitation for tortoiseshell, the beautifully 

patterned scales that cover the turtle’s shell (Parsons, 1972). Another manmade factor that affects 

hawksbills in foraging areas and on nesting beaches is global climate change (USDOC, NMFS and 

USDOI, FWS, 2007c). 
Description of the Environment and Impact Analysis 4-207 

Kemp’s Ridley Sea Turtle 

Ogren (1989) suggests that the Gulf Coast, from Port Aransas, Texas, through Cedar Key, Florida, 

represents the primary habitat for subadult ridleys in the northern Gulf of Mexico. Internationally, the 

Kemp’s ridley is considered the most endangered sea turtle. There is no designated critical habitat for the 

Kemp’s ridley sea turtle. There is no designated critical habitat; however, on February 17, 2010, NMFS 

and FWS were jointly petitioned to designate critical habitat for Kemp’s ridley sea turtles for nesting 

beaches along the Texas coast and for marine habitats in the Gulf of Mexico and Atlantic Ocean. The 

NMFS is currently reviewing the petition. 

The species occurs mainly in coastal areas of the Gulf of Mexico and the northwestern Atlantic 

Ocean. Kemp’s ridleys nest in daytime aggregations known as arribadas, primarily at Rancho Nuevo, a 

stretch of beach in Mexico, Tamaulipas State. A 2007 arribada at Rancho Nuevo included over 4,000 

turtles over a 3-day period (USDOC, NMFS and USDOI, FWS, 2007d). Kemp’s ridley sea turtle nest 

numbers reported along the 47-mi (76-km) stretch of Alabama coastline were 1 nest in 2006, 2007, and 

2008. Louisiana and Mississippi have few, if any, nests. 

Of the seven extant species of sea turtles in the world, the Kemp’s ridley has declined to the lowest 

population level. Many threats to the future of the species remain, including interactions with fishery 

gear, marine pollution, foraging habitat destruction, illegal poaching of nests, and the potential threats to 

nesting beaches from such sources as global climate change, development, and tourism pressures 

(USDOC, NOAA, 2011a). 

Loggerhead Sea Turtle 

Loggerhead nesting along the Gulf Coast occurs primarily along the Florida Panhandle, although 

some nesting has been reported from Texas through Alabama (USDOC, NMFS and USDOI, FWS, 1991). 

Loggerhead turtles have been primarily sighted in waters over the continental shelf, although many 

surface sightings of this species have also been made over the outer slope beyond the 1,000-m (3,281-ft) 

isobath. The loggerhead sea turtle is listed as threatened. 

Ongoing threats to the western Atlantic loggerhead populations include incidental takes from 

dredging, commercial trawling, longline fisheries, and gillnet fisheries; loss or degradation of nesting 

habitat from coastal development and beach armoring; disorientation of hatchlings by beachfront lighting; 

nest predation by native and nonnative predators; degradation of foraging habitat; marine pollution and 

debris; watercraft strikes; and disease (USDOC, NOAA, 2011a). 

In the past decade, a 39.5 percent decline in the annual number of nests has been reported (USDOC, 

NMFS and USDOI, FWS, 2007e). The Florida Panhandle Nesting Subpopulation showed a decline of 

6.6 percent annually from 1995 to 2005. Loggerhead sea turtle nest numbers in 2010 were above the 

average of the preceding 10-year period (Florida Fish and Wildlife Conservation Commission, 2010b). 

Along the 47-mi (76-km) stretch of Alabama coastline, 62 loggerhead nests were reported in 2003, 53 in 

2004, 37 in 2005, 45 in 2006 and 1 Kemp’s ridley nest, 54 in 2007 and 1 Kemp’s ridley nest, and 78 in 

2008 and 1 Kemp’s ridley nest. Louisiana and Mississippi have few if any nests. 

Recent Consultation 

As mandated by the ESA, BOEMRE consulted with NMFS and FWS on possible and potential 

impacts from a CPA or WPA proposed action on endangered/threatened species and designated critical 

habitat under their jurisdiction. A biological assessment was prepared for each consultation. The action 

area analyzed in the biological assessments included the lease sale areas addressed in this Supplemental 

EIS. 

The formal ESA consultation with NMFS was concluded with receipt of the Biological Opinion on 

July 3, 2007 (USDOC, NMFS, 2007b). The Biological Opinion concludes that the proposed lease sales 

and associated activities in the Gulf of Mexico in the 5-Year Program are not likely to jeopardize the 

continued existence of threatened and endangered species under NMFS jurisdiction or destroy or 

adversely modify designated critical habitat. The following information was present in the Biological 

Opinion, but not in the Multisale EIS. The informal ESA consultation with FWS was concluded with a 

letter dated September 14, 2007. The FWS concurred with this Agency’s determination that proposed 
4-208 Central Planning Area Supplemental EIS 

actions of the 5-Year Program were not likely to adversely affect the threatened/endangered species or 

designated critical habitat under FWS jurisdiction. 

The extent and scope of the spill resulting from the DWH event represents new information not 

assessed in the existing ESA Section 7 consultation in the GOM under the current 5-Year Program. As a 

result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing GOM 

Multisale EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE 

on September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. The existing 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

4.1.1.12.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of sea turtles for the CPA proposed action can be found in Chapter 

4.2.2.1.6 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information 

since publication of the Multisale EIS is presented in Chapter 4.1.7.2 of the 2009-2012 Supplemental EIS. 

The following information is a summary of the resource description incorporated from the Multisale EIS, 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

Proposed Action Analysis 

Routine activities resulting from the CPA proposed action have the potential to harm sea turtles. The 

major impact-producing factors resulting from the routine activities associated with the CPA proposed 

action that may affect loggerhead, Kemp’s ridley, hawksbill, green, and leatherback turtles include the 

degradation of water quality resulting from operational discharges; noise generated by helicopter and 

vessel traffic, platforms, and drillships, and seismic exploration; vessel collisions; and marine debris 

generated by service vessels and OCS facilities. 

Contaminants in waste discharges and drilling muds might indirectly affect sea turtles through foodchain biomagnification, but there is uncertainty concerning the possible effects. Most operational 

discharges are diluted and dispersed when released in offshore areas and are considered to have sublethal 

effects (NRC, 1983; API, 1989; Kennicutt, 1995; Kennicutt et al., 1996). Any potential impacts from 

drilling fluids would be indirect, either as a result of impacts to prey species or possibly through ingestion 

via the food chain (Neff et al., 1989). Impacts from water degradation are expected to be negligible due 

to the wide-ranging habits of sea turtle species in the GOM. 

The first impact-producing factor associated with the CPA proposed action that could affect ESAlisted sea turtles is impacts from vessel noise and vessel collisions. The dominant source of noise from 

vessels is propeller operation, and the intensity of this noise is largely related to ship size and speed. 

Vessel noise from the proposed action would produce low levels of noise, generally in the 150- to 170-dB 

re 1 μPa-m at frequencies below 1,000 Hz. Vessel noise is transitory and generally does not propagate at 

great distances from the vessel. Also, available information indicates that sea turtles do not greatly utilize 

environmental sound. As a result, NMFS’s 2007 Biological Opinion concluded that effects to sea turtles 

from vessel noise are discountable (USDOC, NMFS, 2007b). 

Drilling activities would produce sounds transmitted into the water that could be intermittent, sudden, 

and at times could be high intensity as operations take place. However, sea turtles are not expected to be 

impacted by this disturbance because NMFS, in their 2007 Biological Opinion, determined that “drilling 

is not expected to produce amplitudes sufficient to cause hearing or behavioral effects to sea turtles or 

sperm whales; therefore, these effects are insignificant.” 

Sea turtles spend at least 3-6 percent of their time at the surface for respiration, and perhaps as much 

as 26 percent of time at the surface for basking, feeding, orientation, and mating (Lutcavage et al., 1997). 

Data show that collisions with all types of commercial and recreational vessels are a cause of sea turtle 

mortality in the GOM (Lutcavage et al., 1997). Stranding data for the U.S. Gulf and Atlantic Coasts, 
Description of the Environment and Impact Analysis 4-209 

Puerto Rico, and the U.S. Virgin Islands show that between 1986 and 1993 about 9 percent of living and 

dead stranded sea turtles had boat strike injuries (Lutcavage et al., 1997). Vessel-related injuries were 

noted in 13 percent of stranded turtles examined from the Gulf of Mexico and the Atlantic during 1993 

(Teas, 1994), but this figure includes those that may have been struck by boats post-mortem. Large 

numbers of loggerheads and 5-50 Kemp’s ridley turtles are estimated to be killed by vessel traffic per 

year in the U.S. (NRC, 1990; Lutcavage et al., 1997). 

There have been no documented sea turtle collisions with drilling and service vessels in the GOM; 

however, collisions with small or submerged sea turtles may go undetected. Based on sea turtle density 

estimates in the GOM, the encounter rates between sea turtles and vessels would be expected to be greater 

in water depths <200 m (656 ft) (USDOC, NMFS, 2007b). To further minimize the potential for vessel 

strikes, BOEMRE issued NTL 2007-G04, which clarifies 30 CFR § 250.282 and provides NMFS 

guidelines for monitoring procedures related to vessel strike avoidance measures for sea turtles and other 

protected species. With implementation of these measures and the avoidance of potential strikes from 

OCS vessels, NMFS’s 2007 Biological Opinion concluded that the risk of collisions between oil/gasrelated vessels (including those for G&G, drilling, production, decommissioning, and transport) and sea 

turtles is appreciably reduced, but strikes may still occur. The BOEMRE monitors for any takes that have 

occurred as a result of vessel strikes and also requires that any operator immediately report the striking of 

any animal (see 30 CFR § 250.282 and NTL 2007-G04). 

To date, there have been no reported strikes of sea turtles by drilling vessels. Given the scope, 

timing, and transitory nature of the CPA proposed action and, with this established mitigation, effects to 

sea turtles from drilling vessel collisions is expected to be negligible. 

Chronic sublethal effects (e.g., stress) resulting in persistent physiological or behavioral changes 

and/or avoidance of impacted areas from noise disturbance, such as G&G activities, could cause declines 

in survival or fecundity and result in population declines; however, such declines are not expected. The 

NTL 2007-G02 provides guidance on mitigations that would minimize the potential impacts of seismic 

airguns to sea turtles. Observers are required to clear the exclusion area of sea turtles prior to ramp-up, 

and the subsequent gradual ramping up of the airguns may help minimize the impact of rapid onset of, 

and close proximity to, very loud noise. 

The BOEMRE published a PEA on decommissioning operations (USDOI, MMS, 2005) that, in part, 

addresses the potential impacts of explosive and nonexplosive severance activities on OCS resources, 

particularly upon marine mammals and sea turtles. Pursuant to 30 CFR 250 Subpart Q, operators must 

obtain a permit from BOEMRE before beginning any platform removal or well-severance activities. 

During the review of the permit applications, terms and conditions of the August 2006 NMFS Biological 

Opinion/Incidental Take Statement are implemented for the protection of marine protected species and to 

reduce possible impacts from any potential activities resulting from the proposed lease sale. 

In 30 CFR 250 Subpart B, BOEMRE requires operators of Federal oil and gas leases to meet the 

requirements of ESA. The regulation outlines the environmental, monitoring, and mitigation information 

that operators must submit with plans for exploration, development, and production. This regulation 

requires OCS activities to be conducted in a manner that is consistent with the provisions of ESA. Actual 

sea turtle impacts from explosive removals in recent years have been small. The updated pre- and postdetonation mitigations should ensure that injuries remain extremely rare. 

Greatly improved handling of waste and trash by industry, along with the annual awareness training 

required by the marine debris mitigations, is decreasing the plastics in the ocean and minimizing the 

devastating effects on sea turtles. Many types of plastic materials end up as solid waste during drilling 

and production operations. Some of this material is accidentally lost overboard where sea turtles could 

consume it or become entangled in it. The incidental ingestion of marine debris and entanglement could 

adversely affect sea turtles. The BOEMRE proposes compliance with the guidelines provided in NTL 

2007-G03, “Marine Trash and Debris Awareness and Elimination,” which appreciably reduces the 

likelihood of sea turtles encountering marine debris from the proposed activity. The routine activities of 

the CPA proposed action are unlikely to have significant adverse effects on the size and recovery of any 

sea turtle species or population in the GOM. 
4-210 Central Planning Area Supplemental EIS 

Summary and Conclusion 

In this Supplemental EIS, BOEMRE has reexamined the analysis for sea turtles presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, and has considered the recent reports cited above 

and other new information. The extent and scope of the spill resulting from the DWH event represents 

new information not assessed in the existing ESA Section 7 consultation in the GOM under the current 5-

Year Program. As a result of this new information, BOEMRE reinitiated ESA Section 7 consultation on 

the existing GOM Multisale EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a 

letter to BOEMRE on September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 

2010. However, NMFS and FWS have placed this consultation on hold given the environmental baseline 

needing to be updated by the results of the NRDA process. The NRDA data have yet to be released. The 

existing consultations will remain in effect until the reinitiated consultations are completed. In the 

interim, BOEMRE will continue to comply with all Reasonable and Prudent Measures and the Terms and 

Conditions under these existing consultations, along with implementing the current BOEMRE-imposed 

mitigation, monitoring, and reporting requirements. Based on the most recent and best available 

information at the time, BOEMRE will also continue to closely evaluate and assess risks to listed species 

and designated critical habitat in upcoming environmental compliance documentation under NEPA and 

other statutes. 

Because of the mitigations described in the above analysis, routine activities (e.g., operational 

discharges, noise, vessel traffic, and marine debris) related to the proposed CPA lease sale are not 

expected to have long-term adverse effects on the size and productivity of any sea turtle species or 

populations in the northern GOM. Lethal effects are most likely to be from chance collisions with OCS 

service vessels or ingestion of accidentally released plastic materials. Most OCS activities are expected to 

have sublethal effects. 

4.1.1.12.3. Impacts of Accidental Events 

A detailed impact analysis of sea turtles for the CPA proposed action can be found in Chapter 4.4.6 of 

the 2007-2012 Multisale EIS and in Chapter 4.1.7.3 of the 2009-2012 Supplemental EIS. The following 

information is a summary of the resource description incorporated from the Multisale EIS, the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

Proposed Action Analysis 

Accidental activities resulting from the CPA proposed action have the potential to harm sea turtles. 

The major impact-producing factors resulting from the accidental activities associated with the CPA 

proposed action that may affect loggerhead, Kemp’s ridley, hawksbill, green, and leatherback turtles 

include accidental blowouts, oil spills, and spill-response activities. These have the potential to impact 

small to large numbers of sea turtles in the GOM, depending on the magnitude and frequency of 

accidents, the ability to respond to accidents, the location and date of accidents, and various 

meteorological and hydrological factors. Chronic or acute exposure may result in harassment, harm, or 

mortality of sea turtles occurring in the northern Gulf. Exposure to hydrocarbons persisting in the sea 

following the dispersal of an oil slick are expected to most often result in sublethal impacts (e.g., 

decreased health and/or reproductive fitness, increased vulnerability to disease) to sea turtles. Sea turtle 

hatchling exposure to, fouling by, or consumption of tarballs persisting in the sea following the dispersal 

of an oil slick would likely be fatal. 

The oil from an oil spill can adversely affect sea turtles by causing soft tissue irritation, respiratory 

stress from inhalation of toxic fumes, food reduction or contamination, direct ingestion of oil and/or tar, 

and temporary displacement from preferred habitats. The long-term impacts to sea turtle populations are 

poorly understood but could include decreased survival and lowered reproductive success. The range of 

toxicity and degree of sensitivity to oil hydrocarbons and the effects of cleanup activities on sea turtles are 

unknown. Impacts from the dispersants are unknown, but may have similar irritants to tissues and 

sensitive membranes as they are known to have had on seabirds and marine mammals (NRC, 2005). 

In accordance with the Incidental Take Statement, NMFS believes that a small number of listed 

species would experience adverse effects as the result of exposure to a large oil spill or ingestion of 

accidentally spilled oil over the lifetime of proposed CPA Lease Sale 216/222. However, NMFS is not 
Description of the Environment and Impact Analysis 4-211 

including an Incidental Take Statement for the incidental take of listed species due to oil exposure. 

Incidental take, as defined at 50 CFR 402.02, refers only to takings that result from an otherwise lawful 

activity. The Clean Water Act (33 U.S.C. 1251 et seq.), as amended by the Oil Pollution Act of 1990 

(33 U.S.C. 2701 et seq.), prohibits discharges of harmful quantities of oil, as defined at 40 CFR 110.3, 

into waters of the United States. Therefore, even though the Biological Opinion (USDOC, NMFS, 

2007b) considered the effects on listed species by oil spills that may result from proposed CPA Lease 

Sale 216/222, those takings that would result from an unlawful activity (i.e., oil spills) are not specified in 

the Incidental Take Statement and have no protective coverage under Section 7(o)(2) of the ESA. 

The DWH event and related spill-response activities may impact sea turtles that come into contact 

with oil and remediation efforts. The best available information does not provide a complete 

understanding of the effects of the spilled oil and active response/cleanup activities on the affected sea 

turtle environment. For the latest available information on oiled or affected sea turtles documented in the 

area, event response, and daily maps of the current location of spilled oil, see RestoreTheGulf.gov 

(2010c). Figure 4-13 summarizes sea turtles collected by date obtained from the consolidated numbers of 

collected fish and wildlife that have been reported to the Unified Area Command from FWS, NOAA, 

incident area commands, rehabilitation centers, and other authorized sources operating within the DWH 

event impact area through November 2, 2010. More detail on the potential range of effects to sea turtles 

from contact with spilled oil can be found on the NMFS Office of Protected Resources website 

(http://www.nmfs.noaa.gov/pr/health/oilspill/turtles.htm). The NRDA-related efforts are ongoing, and 

the results will be incorporated into future environmental analyses. 

A similar yet not comparable blowout of the Ixtoc I offshore drilling rig in the Bay of Campeche, 

Mexico, on June 3, 1979, resulted in the release of 500,000 metric tons (140 million gallons) and the 

transport of this oil into the Gulf of Mexico (ERCO, 1982). Of the three sea turtles found dead in the 

U.S., all had petroleum hydrocarbons in the examined tissues, and there was selective elimination of 

portions of this oil, indicating chronic exposure (Hall et al., 1983). 

Summary and Conclusion 

The BOEMRE has reexamined the analysis for sea turtles presented in the Multisale EIS and the 

2009-2012 Supplemental EIS, and has considered the recent reports cited above and other new 

information. The extent and scope of the spill resulting from the DWH event represents new information 

not assessed in the existing ESA Section 7 consultation in the GOM under the current 5-Year Program. 

As a result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing 

GOM Multisale EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to 

BOEMRE on September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. 

However, NMFS and FWS have placed this consultation on hold given the environmental baseline 

needing to be updated by the results of the NRDA process. The NRDA data have yet to be released. The 

existing consultations will remain in effect until the reinitiated consultations are completed. With current 

regulations, mitigation, and the low probability of an accidental event, effects on turtle populations from a 

CPA proposed action are expected to be small. 

In the event of a catastrophic spill similar to the DWH event, any substantive impact to sea turtles is 

very unlikely because the potential impacts from a catastrophic spill would be similar to aforementioned 

routine and accidental issues. However, despite the recent DWH event, historical trends in the GOM 

indicate that catastrophic spill events are not likely to occur as a result of drilling and temporary 

abandonment associated with the CPA proposed action. 

4.1.1.12.4. Cumulative Impacts 

A detailed impact analysis of sea turtles for the CPA proposed action can be found in Chapter 4.5.6 of 

the Multisale EIS and in Chapter 4.1.7.4 of the 2009-2012 Supplemental EIS. The following information 

is a summary of the resource description incorporated from the Multisale EIS, the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 
4-212 Central Planning Area Supplemental EIS 

Proposed Action Analysis 

The major impact-producing factors resulting from cumulative activities associated with the CPA 

proposed action that may affect loggerhead, Kemp’s ridley, hawksbill, green, and leatherback turtles and 

their habitats include the degradation of water quality resulting from operational discharges; vessel traffic; 

noise generated by platforms, drillships, helicopters and vessels; seismic surveys; explosive structure 

removals; oil spills; oil-spill-response activities; loss of debris from service vessels and OCS structures; 

commercial fishing; capture and removal; and pathogens. The cumulative impact of these ongoing OCS 

activities on sea turtles is expected to result in a number of chronic and sporadic sublethal effects (i.e., 

behavioral effects and nonfatal exposure to or intake of OCS-related contaminants or discarded debris) 

because that may stress and/or weaken individuals of a local group or population and may predispose 

them to infection from natural or anthropogenic sources. 

Few deaths are expected from chance collisions with OCS service vessels, ingestion of plastic 

material, commercial fishing, and pathogens. Disturbance (noise from vessel traffic and drilling 

operations, etc.) and/or exposure to sublethal levels of toxins and anthropogenic contaminants may stress 

animals, weaken their immune systems, and make them more vulnerable to parasites and diseases that 

normally would not be fatal during their life cycle. The net result of any disturbance depends upon the 

size and percentage of the population likely to be affected, the ecological importance of the disturbed 

area, the environmental and biological parameters that influence an animal’s sensitivity to disturbance and 

stress, or the accommodation time in response to prolonged disturbance (Geraci and St. Aubin, 1980). As 

discussed above, lease stipulations and regulations are in place to reduce vessel strike mortalities. 

Incremental injury effects from the proposed action on sea turtles are expected to be negligible for 

drilling and vessel noise and minor for vessel collisions, but the effects will not rise to the level of 

significance because of the limited scope, duration, and geographic area of the proposed drilling and 

vessel activities and the relevant regulatory requirements. 

The effects of the proposed action, when viewed in light of the effects associated with other relevant 

activities, may affect sea turtles occurring in the GOM. With the enforcement of regulatory requirements 

for drilling and vessel operations and the scope of the proposed action, incremental effects from the 

proposed drilling activities on sea turtles will be negligible (drilling and vessel noise) to minor (vessel 

strikes). The best available scientific information indicates that sea turtles do not greatly use sound in the 

environment for survival; therefore, disruptions in environmental sound would have little effect. 

Consequently, no significant cumulative impacts would be expected from the CPA proposed activities or 

as the result of past, present, or reasonably foreseeable oil and gas leasing, exploration, development and 

production in the GOM. 

Summary and Conclusion 

The BOEMRE has reexamined the analysis for sea turtles presented in the Multisale EIS and the 

2009-2012 Supplemental EIS, and has considered the recent reports cited above and other new 

information. While new information discloses significant cumulative impacts on sea turtles as a result of 

tropical storms and longline fishing, the incremental contribution of the CPA proposed action to those 

cumulative impacts remains as described in the Multisale EIS and the 2009-2012 Supplemental EIS and 

still would not have a population-level effect on the species. The analysis and potential impacts detailed 

in the Multisale EIS and the 2009-2012 Supplemental EIS still apply for proposed CPA Lease Sale 

216/222. Because of current regulations, mitigation, and the low probability of an accidental event, 

effects on turtle populations from the CPA proposed action are expected to be small and should not 

elevate cumulative effects from natural and anthropogenic sources. 

The extent and scope of the spill resulting from the DWH event represents new information not 

assessed in the existing ESA Section 7 consultation in the GOM under the current 5-Year Program. As a 

result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing GOM 

Multisale EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE 

on September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. The existing 
Description of the Environment and Impact Analysis 4-213 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

4.1.1.13. Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice 

The BOEMRE has reexamined the analysis for beach mice presented in the Multisale EIS and the 

2009-2012 Supplemental EIS, based on the additional information presented below and in consideration 

of the DWH event. No substantial new information was found that would alter the impact conclusion for 

beach mice presented in the Multisale EIS. Due to the extended distance from shore, activities occurring 

in the 181 South Area are not expected to impact beach mice. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A brief summary of potential impacts follows. An impact from 

consumption of beach trash and debris associated with the CPA proposed action on the Alabama, 

Choctawhatchee, St. Andrew, and Perdido Key beach mice is possible but unlikely. While potential spills 

that could result from the CPA proposed action are not expected to contact beach mice or their habitats, 

large-scale oiling of beach mice could result in local extinction and, if not properly regulated, oil-spillresponse and cleanup activities could have a significant impact to the beach mice and their habitat. 

Cumulative activities posing the greatest potential harm to beach mice are non-OCS factors and natural 

catastrophes, which, in combination, could potentially deplete some beach mice populations to 

unsustainable levels. The expected incremental contribution of the CPA proposed action to the 

cumulative impacts is negligible. Because beach mice are located such a far distance from the proposed 

CPA sale area, the impacts of the CPA proposed action have not been analyzed. 

4.1.1.13.1. Description of the Affected Environment 

A detailed description of beach mice can be found in Chapter 3.2.5 of the Multisale EIS. Additional 

information for the 181 South Area and any new information since the publication of the Multisale EIS is 

presented in Chapter 4.1.8 of the 2009-2012 Supplemental EIS. The following information is a summary 

of the resource description incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and 

new information that has become available since both documents were prepared. 

Hall (1981) recognizes 16 subspecies of field mouse (Peromyscus polionotus), 8 of which are 

collectively known as beach mice. Of Gulf Coast subspecies, the Alabama, Choctawhatchee, St. Andrew, 

and Perdido Key beach mice occupy restricted habitats in the mature coastal dunes of Florida and 

Alabama. All four mice are listed as endangered: the Alabama subspecies in Alabama (listed June 6, 

1985); and the Perdido Key subspecies (June 6, 1985), St. Andrew subspecies (December 18, 1998), and 

Choctawhatchee subspecies (June 6, 1985) in Florida (USDOI, FWS, 1985a, 1987, and 1998). 

Populations have fallen to levels approaching extinction. For example, in the late 1980’s, estimates of 

total remaining beach mice were less than 900 for the Alabama beach mouse, about 80 for the Perdido 

Key beach mouse, and about 500 for the Choctawhatchee beach mouse. The St. Andrew beach mouse is 

the only listed subspecies without designated critical habitat. 

Continued monitoring of populations of all subspecies along the Gulf Coast between 1985 and the 

present indicates that approximately 32.3 mi (52 km) of coastal dune habitat are now occupied by the four 

listed subspecies (1/3 of historic range). Beach mice were listed because of the loss of coastal habitat 

from human development. The reduced distribution and numbers of beach mice have continued because 

of multiple habitat threats over their entire range (coastal development and associated human activities, 

military activities, coastal erosion, and sea states caused by severe weather). Habitat loss is the primary 

cause for declines in populations of beach mice (USDOI, FWS, 2006a). Development of beachfront real 

estate along coastal areas and catastrophic alteration by hurricanes are the primary contributors to loss of 

habitat. Destruction of Gulf Coast sand dune ecosystems for commercial and residential development has 

destroyed about 60 percent of original beach mouse habitat (Holliman, 1983). Recent studies indicate 

that this continues to be a problem (Douglass et al., 1999; South Alabama Regional Planning 

Commission, 2001). 

The inland extent of beach mouse habitat may vary depending on the configuration of the sand dune 

system and the vegetation present. There are commonly several rows of dunes paralleling the shoreline 

and within these rows there are generally three types of microhabitat. The first microhabitat is the frontal 
4-214 Central Planning Area Supplemental EIS 

dunes (from the beach face proceeding inland, these compose the primary and secondary dunes). These 

features are sparsely vegetated with widely scattered coarse grasses including sea oats (Uniola 

paniculata), bunch grass (Andropogon maritimus), and beach grass (Panicum amarum and P. repens), 

and with seaside rosemary (Ceratiola ericoides), beach morning glory (Ipomoea stolonifera), and railroad 

vine (I. Pes-caprae). Primary and secondary dunes only differ in location relative to the beach. The 

second microhabitat is the higher rear scrub dunes (tertial dunes), which support growth of slash pine 

(Pinus elliotti), sand pine (P. clausa), and scrubby shrubs and oaks, including yaupon (Ilex vomitoria), 

marsh elder (Iva sp.), scrub oak (Quercus myrtifolia), and sand-live oak (Q. virginiana var. maritima). 

The third microhabitat is the interdunal areas, which contain sedges (Cyperus sp.), rushes (Juncus 

scirpoides), and salt grass (Distichlis spicata). 

Beach mice are restricted to the coastal barrier sand dunes along the Gulf. Optimal overall beach 

mouse habitat is currently thought to be comprised of a heterogeneous mix of interconnected habitats 

including frontal dunes, scrub (tertiary) dunes farther inland, and interdunal areas between these dune 

habitats, as discussed above. Beach mice dig burrows mainly in the frontal dunes and interior scrub 

dunes where the vegetation provides suitable cover. Most beach mouse surveys conducted prior to the 

mid-1990’s were in primary and secondary frontal dunes because the investigators assumed that these 

habitats are the preferred habitat of beach mice. A limited number of surveys in scrub dunes and other 

interior habitat resulted in less knowledge of the distribution and relative abundance there. In coastal 

environments, the terms “scrub” and “scrub dune” refer to habitat or vegetation communities adjacent to 

and landward of primary and secondary dune types where scrub oaks are visually dominant. Interior 

habitat can include vegetation types such as grass-like forbs (forbs are the herbs other than grasses). 

There is substantial variation in scrub oak density and cover within and among scrub dunes throughout 

ranges of beach mice. The variation, an ecological gradient, is represented by scrub oak woodland with a 

relatively closed canopy at one end of a continuum. At the other extreme of the gradient, scrub dunes are 

relatively open with patchy scrub ridges and intervening swales or interdunal flats dominated by 

herbaceous plants. 

Beach mice feed nocturnally in the dunes and remain in burrows during the day. Their diets vary 

seasonally but consist mainly of seeds, fruits, and insects (Ehrhart, 1978; Moyers, 1996). Changes in the 

availability of foods result in changes in diets between seasons and account for variability of seasonal 

diets between years. Autumn diets of beach mice consist primarily of seeds and/fruits of sea oats, 

evening primrose (Oenothera humifusa), bluestem (Schizachyrium maritimum), and dune spurge 

(Chamaesyce ammannioides). Sea oats and beach pea (Galactia sp.) dominate winter diets. Spring diets 

primarily consist of dune toadflax (Linaria floridana), yaupon holly (Ilex vomitoria), seashore elder (Iva 

imbricata), and greenbrier (Smilax sp.). Summer diets are dominated by evening primrose, insects, dune 

toadflax, and ground cherry (Physalis augustifolia) (Moyers, 1996). Management practices designed to 

promote recovery of dune habitat, increase food sources, and enhance habitat heterogeneity may aid in the 

recovery of beach mouse populations. 

In wild populations, beach mice have an average life span of about 9 months. Males and females 

reach adulthood and are able to reproduce at approximately 35 days of age. Females can nurse one litter 

while pregnant with another litter. From captive colonies we know that litter size is 1-8 with an average 

of four. Young are weaned in 2-3 weeks and are generally on their own 1-2 weeks later. 

Hurricanes are a natural environmental phenomenon affecting the Gulf Coast, and beach mice have 

evolved and persisted in coastal dune habitats since the Pleistocene. Hurricanes are part of a repeated 

cycle of destruction, alteration, and recovery of dune habitat. The extensive coastal dune habitat that 

existed along the Gulf Coast before the fairly recent commercial and residential development allowed 

beach mice to survive even the most severe hurricane events to repopulate dune habitat as it recovered. 

Beach mice are affected by the passage of hurricanes along the northwest Florida and Alabama Gulf 

Coast. Since records on hurricane intensity began in 1885, over 30 hurricanes have struck northwest 

Florida within the historic ranges of the four Gulf Coast beach mouse subspecies (Williams and Duedall, 

1997; Doering et al., 1994; Neumann et al., 1993). In addition, 22 hurricanes have made landfall along 

the coast of Alabama from 1851 to 2004 (USDOC, NOAA, National Hurricane Center, 2006). 

Hurricanes generally produce damaging winds, storm tides and surges, and rain that erode barrierisland, peninsular, and mainland beaches and dunes. Hurricanes cause increased fragmentation of habitat, 

which is correlated with increased distance between fragments that must be crossed by beach mice at 

night if they are to move between habitat patches. Gap distance travelled may decrease when visibility is 
Description of the Environment and Impact Analysis 4-215 

poor during the new moon, making predators harder to see (Wilkinson et al., 2009). Gap distance 

travelled may increase if beach mice know in advance that the target patch is environmentally more 

favorable, making risk of predation worthwhile (Wilkinson et al., 2009). Following hurricanes, the dune 

system begins a slow natural repair process that may take 3-20 years, depending on the magnitude of dune 

loss (Salmon et al., 1982). During this period, sea oats and pioneer dune vegetation become established, 

collecting sand and building dunes. As the dunes grow and become stable, other successional dune 

vegetation colonizes the area (Gibson and Looney, 1994), and beach mouse food sources and habitats are 

reestablished. The rate of recovery of food supplies for beach mice is variable, with some areas adversely 

affected for an extended period of time by hurricane and post-hurricane conditions. 

Tropical storms periodically devastate Gulf Coast sand dune communities, dramatically altering or 

destroying habitat, and either drowning beach mice or forcing them to concentrate on high scrub dunes 

where they are exposed to predators. How a hurricane affects beach mice depends primarily on its 

characteristics (winds, storm surge, rainfall), the time of year (midsummer is the worst), where the eye 

crosses land (side of hurricane—clockwise or counterclockwise), population size, and storm impacts to 

habitat and food sources. The interior dunes and related access corridors may be essential habitats for 

beach mice following survival of a hurricane. For the three subspecies that have critical habitat areas 

(Alabama, Perdido Key, and Choctawhatchee beach mice), the major constituent elements that are known 

to require special management considerations or protection are dunes and interdunal areas and associated 

grasses and shrubs that provide food and cover (USDOI, FWS, 1985a and b). 

Beach mice have existed in an environment subject to recurring hurricanes, but tropical storms and 

hurricanes are now considered to be a primary factor in the beach mouse’s decline. It is only within the 

last 20-30 years that the combination of habitat loss due to beachfront development, isolation of 

remaining beach mouse habitat areas and populations, and destruction of remaining habitat by hurricanes 

have increased the threat of extinction of several subspecies of beach mice. 

The FWS reported considerable damage to 10 national wildlife refuges in Alabama, Mississippi, 

Louisiana, and the Panhandle of Florida caused by Hurricane Ivan in 2004 (USDOI, FWS, 2004a). 

Perdido Key, Florida, was hit hard by Hurricane Ivan, and beach mouse dune habitat and populations 

were greatly reduced. The mice take refuge on higher ground during severe storms. Hurricane Ivan 

adversely impacted an estimated 90-95 percent of primary and secondary dune habitat throughout the 

range of the Alabama beach mouse (USDOI, FWS, 2004b). Trapping data indicate that mice may have 

become locally extinct in these low-lying areas (USDOI, FWS, 2004b). Approximately 3,460 ha (1,400 

ac) of higher elevation scrub habitat did not appear to be inundated by storm surge from either Hurricanes 

Ivan or Katrina (U.S. Dept. of the Army, COE, 2002a; USDOI, FWS, 2004b, 2004c, and 2005a; ENSR 

Corporation, 2004) but received moderate damage from salt spray and wind (Boyd et al., 2003; USDOI, 

FWS, 2004a). The worst damage from Hurricane Ivan occurred in Alabama to Bon Secour National 

Wildlife Refuge located west of Gulf Shores, Alabama, along the Fort Morgan Peninsula. Major primary 

dunes at Bon Secour were almost completely destroyed and tons of debris washed up on the refuge. 

Following Hurricane Opal in 1995, Swilling et al. (1998) reported higher Alabama beach mouse 

densities in the scrub than the foredunes nearly 1 year after the storm. As vegetation began to recover, 

however, the primary and secondary dunes were reoccupied by Alabama beach mice, and population 

densities surpassed those in the scrub in the fall and winter following the storm. Similar movement and 

habitat occupation patterns were observed following Hurricane Georges in 1998. Therefore, while 

Alabama beach mouse numbers and habitat quality in the frontal dunes ebb and flow in response to 

tropical storms, the higher elevation scrub habitat is important to mouse conservation as a more stable 

environment during and after storm events. 

In a population genetics study of the Alabama beach mouse, adult males were often trapped with 

adult females, probably their mates in this monogamous species (Tenaglia et al., 2007). These pairs were 

more distantly related than expected, probably because kin recognition allowed selection of unrelated 

mates to avoid inbreeding depression as a result of breeding of related individuals. Inbreeding depression 

is an increase in the frequency of harmful homozygous recessive genes, which cause reduced fitness of a 

population. As population levels have declined, inbreeding avoidance has become important to this 

subspecies. Subadults were often captured with related mice, suggesting that mice form sibling and adultsubadult familial bonds before final adult dispersal, which itself is a short distance (Tenaglia et al., 2007). 

Consequences for inbreeding impacts remain to be investigated. 
4-216 Central Planning Area Supplemental EIS 

The DWH event has so far had no recorded environmental changes for the Alabama beach mouse and 

probably no ecological changes yet for the other three subspecies (Leblanc, personal communication, 

2010). No changes have yet occurred on the two subspecies of beach mice on the Atlantic Coast of 

Florida. No oil has yet been reported as entering the Loop Current to reach the east coast of Florida. 

Vehicular traffic and activity associated with the DWH event cleanup can trample or bury nests and 

burrows or cause displacement from preferred habitat. Sometimes, because of lack of thorough training 

of all personnel, future vehicle and foot traffic that may take place during shoreline cleanup resulting 

from the DWH event could disturb beach mouse populations or degrade or destroy habitat. A study is 

pending (due out in January or February 2011) in part investigating events where bulldozers in Florida 

allegedly breached possible beach mouse dune habitat so cleanup vehicles could reach oiled beaches 

(Frater, personal communication, 2010). 

4.1.1.13.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of beach mice for the CPA proposed action can be found in Chapter 

4.2.2.1.7 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information 

since publication of the Multisale EIS is presented in Chapter 4.1.8.2 of the 2009-2012 Supplemental EIS. 

The following information is a summary of the resource description incorporated from the Multisale EIS, 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

This chapter discusses the possible effects of routine activities associated with the CPA proposed 

action on the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice, which are designated 

as protected species under the Endangered Species Act (Chapter 1.3). The mice occupy restricted habitat 

behind coastal foredunes of Florida and Alabama (Ehrhart, 1978; USDOI, FWS, 1987). Portions of the 

beach mouse habitat have been designated as critical. 

Proposed Action Analysis 

The major impact-producing factors associated with routine activities of the proposed action that may 

affect beach mice include beach trash and debris, and efforts undertaken for the removal of marine debris 

or for beach restoration. Beach mice may mistakenly consume trash and debris. Mice may become 

entangled in the debris. The proposed action is expected to contribute negligible marine debris or 

disruption to beach mice areas. Their burrows are about 1-3 m (3-10 ft) long and involve a plugged 

escape tunnel, which would function if the main burrow entrance was trampled by foot traffic (beach 

mice would dig themselves out through the plug) of insufficiently trained debris cleanup personnel 

(Mitchell, personal communication, 2010). 

Summary and Conclusion 

An impact from the CPA proposed action on the Alabama, Choctawhatchee, St. Andrew, and Perdido 

Key beach mice is possible but unlikely. Impact may result from consumption of beach trash and debris. 

Because the proposed action would deposit only a small portion of the total debris that would reach the 

habitat, the impacts would be minimal. Unless all personnel are adequately trained, efforts undertaken for 

the removal of marine debris may temporarily scare away beach mice or destroy their food resources such 

as sea oats. However, their burrows are about 1-3 m (3-10 ft) long and involve a plugged escape tunnel, 

which would function after the main burrow entrance was trampled by foot traffic of insufficiently trained 

debris cleanup personnel. 

4.1.1.13.3. Impacts of Accidental Events 

A detailed impact analysis of beach mice for the CPA proposed action can be found in Chapter 4.4.7 

of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information since 

publication of the Multisale EIS is presented in Chapter 4.1.8.3 of the 2009-2012 Supplemental EIS. The 

following information is a summary of the resource description incorporated from the Multisale EIS, the 
Description of the Environment and Impact Analysis 4-217 

2009-2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

Proposed Action Analysis 

This chapter discusses the possible effects of accidental activities associated with the CPA proposed 

action on the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice, which are designated 

as protected species under the Endangered Species Act. The major impact-producing factors resulting 

from the accidental activities associated with the CPA proposed action that may affect beach mice include 

offshore and coastal oil spills, and spill-response activities. 

The oiling of beach mice could result in local extinction, but this is very unlikely, given the chance of 

impact to the habitat is <0.5 percent, and the area of viable habitat is broad relative to the area potentially 

contacted by a large spill. 

For the CPA proposed action, which is based on the 2009-2012 Supplemental EIS OSRA model, the 

probabilities remain low (<0.5%) that one or more offshore spills 1,000 bbl would occur and contact the 

shoreline inhabited by the Alabama, Choctawhatchee, St. Andrews, and Perdido Key beach mice during 

the 40-year life of the proposed action. Spills in coastal waters could occur at storage or processing 

facilities and at service bases supporting the proposed action; however, these facilities would not likely be 

located near beach mouse habitat. 

Recovery of habitat from hurricanes involves a vital link between mouse food supply (involving 

seeds of dune-stabilizing vegetation) and habitat. The link is not unique to the beach mouse (it may occur 

in many habitats) and may be lost after an oil spill; this loss may result in extinction of the beach mouse 

after later serious storms or hurricanes or further beachfront development disrupts habitat. Impacts can 

also occur from spill-response activities. Vehicular traffic and other activities associated with oil-spill 

cleanup can degrade preferred habitat and cause displacement of mice from these areas. 

There is no definitive information on the persistence of oil in the event that a spill was to contact 

beach mouse habitat. In Prince William Sound, Alaska, after the Exxon Valdez spill in 1989, buried oil 

has been measured in the intertidal zone of beaches, but no effort has been made to search for residual 

buried oil above high tide. Similarly, NRC (2003) makes no mention of studies of oil left above high tide 

after a spill. Regardless of the potential for persistence of oil in beach mouse habitat, a slick cannot wash 

over the foredunes unless carried by a heavy storm swell. 

Summary and Conclusion 

The oiling of beach mice could result in local extinction. Oil-spill-response and cleanup activities 

could also have a substantial impact to the beach mice and their habitat if not properly regulated. 

However, potential spills that could result from the proposed action are not expected to contact beach 

mice or their habitats (<0.5% probability). Also, inshore facilities related to the proposed action are 

unlikely to be located on beach mouse habitat. 

Within the last 20-30 years, the combination of habitat loss due to beachfront development, isolation 

of remaining beach mouse habitat areas and populations, and destruction of remaining habitat by tropical 

storms and hurricanes has increased the threat of extinction of several subspecies of beach mice. 

Destruction of the remaining habitat due to a catastrophic spill and cleanup activities would increase the 

threat of extinction, but the potential for a catastrophic spill that would affect beach mice habitat is low. 

The BOEMRE has reexamined the analysis for impacts to beach mice. No substantial new 

information was found at this time that would alter the overall conclusion that impacts on beach mice 

from accidental impacts associated with the CPA proposed action would be minimal. 

4.1.1.13.4. Cumulative Impacts 

A detailed impact analysis of beach mice for the CPA proposed action can be found in Chapter 4.5.7 

of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information since 

publication of the Multisale EIS is presented in Chapter 4.1.8.4 of the 2009-2012 Supplemental EIS. The 

following information is a summary of the resource description incorporated from the Multisale EIS,; the 

2009-2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 
4-218 Central Planning Area Supplemental EIS 

Proposed Action Analysis 

This chapter discusses the possible cumulative activities associated with the CPA proposed action on 

the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice, which are designated as 

protected species under the ESA. Cumulative activities have a potential to harm or reduce the numbers of 

beach mice. The major impact-producing factors resulting from the cumulative activities associated with 

the CPA proposed action that may affect beach mice include oil spills, alteration and reduction of habitat, 

predation and competition, and consumption of beach trash and debris. Most proposed action-related 

spills, as well as oil spills stemming from import tankering and prior and future lease sales, are not 

expected to contact beach mice or their habitats. Cumulative activities posing the greatest potential harm 

to beach mice are non-OCS factors (i.e., beach development, domestic cats, and coastal spills) and natural 

catastrophes (i.e., hurricanes and tropical storms), which, in combination, could potentially deplete some 

beach mice populations to unsustainable levels. The expected incremental contribution of the CPA 

proposed action to the cumulative impacts is negligible. 

The results of a baseline Population and Habitat Viability Analysis (PHVA) model of the Alabama 

beach mouse (Traylor-Holzer et al., 2005) suggest that the Alabama beach mouse metapopulation has an 

18-21 percent probability of extinction over 100 years, depending on whether the habitat recovers slowly 

or quickly following hurricanes. Sensitivity tests for the model give probabilities of extinction of 13-36 

percent over 100 years. Habitat restoration reduces the probability of Alabama beach mouse extinction at 

or immediately following a hurricane. Recolonization by translocation could eliminate the possibility of 

Alabama beach mouse extinction. A relatively small number of domestic cats would result in virtually 

certain extinction of the Alabama beach mouse. Development scenarios have, at most, minor impacts on 

the estimates of probabilities of Alabama beach mouse extinction. 

Many of the model parameters were uncertain and may have been inaccurate, resulting in uncertainty 

in the probability of Alabama beach mouse extinction. Revision of the model using data collected after 

Hurricane Ivan (Traylor-Holzer, 2005) projects a 14 percent risk of extinction over the next 100 years. 

Much of the risk is from hurricanes. None of the revised development scenarios result in certain Alabama 

beach mouse extinction. The highest risk from development is a 34 percent chance of extinction over 100 

years. Under the revised model, habitat restoration efforts are unlikely to substantially reduce or 

eliminate extinction risk. Data collected after Hurricane Katrina were used in a second revision of the 

model (Reed and Traylor-Holzer, 2006). The revised model projects a risk of extinction of 26.8  1.0 

percent over the next 100 years. Destruction of migration corridors between populations raises the risk to 

41.2  1.1 percent, but only 34.9  1.1 percent with the translocation of mice. Total loss of private land 

as suitable habitat raises the risk further to 46.8  1.1 percent, but only 40.8  1.1 percent with the 

translocation of mice. Hanski (1999) warns that simpler metapopulation models, such as that done for the 

Alabama beach mouse, are more reliable than PVHA models because predictions of PHVA and 

Population Viability Analysis models cannot be tested (only intrinsic sensitivity to changes in various 

parameters can be tested). The Incidence Function Model is an example of a testable metapopulation 

model (Hanski, 1999). 

No recent information was found that would necessitate a reanalysis of the cumulative impacts of the 

proposed action upon the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice. Due to 

the extended distance from shore, the incremental impacts associated with activities are not expected to 

impact beach mice. 

Summary and Conclusion 

Cumulative activities have a potential to harm or reduce the numbers of Alabama, Choctawhatchee, 

St. Andrew, and Perdido Key beach mice. Those activities include oil spills, alteration and reduction of 

habitat, predation and competition, and consumption of beach trash and debris. Most spills related to the 

proposed action, as well as oil spills stemming from import tankering and prior and future lease sales, are 

not expected to contact beach mice or their habitats. This is because of the distance of the CPA proposed 

action to beach mice habitat. Cumulative activities posing the greatest potential harm to beach mice are 

non-OCS activities (beach development and coastal spills) and natural catastrophes (hurricanes) which, in 

combination, could potentially deplete some beach mice populations to unsustainable levels. Impacts 

from the CPA proposed action could come from trash and debris and effort to remove them, as well as oil 
Description of the Environment and Impact Analysis 4-219 

spills and cleanup operations. If personnel are properly trained and supervised, these impacts could be 

reduced. The expected incremental contribution of the CPA proposed action to the cumulative impacts is 

negligible. 

Following the DWH event, BOEMRE requested reinitiation of ESA consultation with both NMFS 

and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE on September 24, 2010. 

The FWS responded with a letter to BOEMRE on September 27, 2010. The reinitiated consultations are 

not complete at this time, although BOEMRE is in discussions with both agencies. 

4.1.1.14. Coastal and Marine Birds 

The BOEMRE has reexamined the analysis for coastal and marine birds presented in the Multisale 

EIS and the 2009-2012 Supplemental EIS, based on the additional information presented below and in 

consideration of the DWH event. No substantial new information was found that would alter the impact 

conclusion for coastal and marine birds presented in the Multisale EIS and the 2009-2012 Supplemental 

EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the proposed action and the proposed action’s incremental contribution to the cumulative impacts are 

presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. The 

majority of impacts resulting from routine activities associated with the CPA proposed action on 

endangered/and nonendangered/nonthreatened coastal and marine birds are expected to be sublethal. 

These impacts include behavioral effects, exposure to or intake of OCS-related contaminants or discarded 

debris, temporary disturbances, and displacement of localized groups from impacted habitats. Impacts 

from potential oil spills associated with the proposed action and oil-spill cleanup on birds are expected to 

be negligible; however, small amounts of oil can affect birds, and there are possible delayed impacts on 

their food supply. The effect of cumulative activities on coastal and marine birds is expected to result in a 

discernible decline in the numbers of birds that form localized flocks or populations, with associated 

changes in species composition and distribution. The incremental contribution of the proposed action to 

cumulative impacts is expected to be negligible because it would not seriously alter species composition 

and cause major reductions in the overall carrying capacity of disturbed areas. 

4.1.1.14.1. Description of the Affected Environment 

A detailed description of coastal and marine birds can be found in Chapter 3.2.6 of the Multisale EIS. 

The following information is a summary of the resource description incorporated from the Multisale EIS 

and the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. A search of Internet bibliographic databases, as well as personal interviews 

with authors of references used in the Multisale EIS, was conducted to determine the availability of recent 

information since publication of the Multisale EIS. No new information on the description of bird 

resources was found from these information sources and/or the DWH event. 

Nonendangered and Nonthreatened Species 

A detailed description of bird species, colonial breeding, and foraging habits of nonendangered and 

nonthreatened coastal and marine birds can be found in Chapter 3.2.6.1 of the Multisale EIS. The 

following is a summary of the information presented in the Multisale EIS and the 2009-2012 

Supplemental EIS, which incorporates new information found since the publication of these documents. 

The Gulf of Mexico is populated by both resident and migratory species of coastal and marine birds 

(Parnell et al., 1988; Visser and Peterson, 1994; Mikuska et al., 1998; Miller and Fontenot, 2001; 

Rappole, 2006). They are herein separated into seven major groups: diving birds, seabirds, shorebirds, 

passerines, marsh and tall wading birds, waterfowl, and raptors. Many species are mostly pelagic and, 

therefore, are rarely sighted near shore. The remaining species are found within coastal and inshore 

habitats and are more susceptible to potential deleterious effects resulting from OCS-related activities 

(Clapp et al., 1982). Previous surveys indicate that Louisiana and Texas are among the primary states in 

the southern and southeastern U.S. for both nesting colonies and total number of breeding coastal and 

marine birds (Martin and Lester, 1991; Martin, 1991). 
4-220 Central Planning Area Supplemental EIS 

Diving Birds 

Diving seabirds are discussed separately in the seabirds section and diving ducks are discussed in the 

waterfowl section. Diving birds are a diverse group. There are three main groups of diving birds: 

cormorants and anhingas (Pelecaniformes), loons (Gaviiformes), and grebes (Podicipediformes). The 

only representative diving bird known to breed in the Gulf is the cormorant. The common diving birds in 

the northern GOM are listed with their main features in Table 3-6 of the Multisale EIS. 

Seabirds 

Three taxonomic orders contain seabirds (defined as species that spend a large portion of their lives 

on or over seawater) in the offshore waters of the northern Gulf of Mexico: (1) Procellariiformes 

(albatrosses, petrels, shearwaters, and storm-petrels); (2) Pelecaniformes (frigatebirds, tropicbirds, 

gannets, brown pelican, and boobies); and (3) Charadriiformes (phalaropes, skuas and jaegers, gulls, and 

terns) (Clapp et al., 1982; Harrison, 1983; Warham, 1990; Olsen and Larsson, 1995 and 1997; Peake et 

al., 1995; Harrison, 1996; National Geographic Society, 1999). The brown pelican was removed from the 

threatened and endangered list on November 17, 2009 (Federal Register, 2009d). The species is still 

protected under the Migratory Bird Treaty Act and also has special conservation status in all coastal states 

except Alabama. Colonies of laughing gulls, eight species of terns, and black skimmers nest in the Gulf 

(Martin and Lester, 1991; Pashley, 1991). A census of south Louisiana seabird nesting colonies was 

completed in 2001 (Michot et al., 2003). Collectively, many seabirds live far from land most of the year, 

roosting on the water surface, except at breeding time when they return to nesting areas along coastlines 

(Terres, 1991). Seabirds typically aggregate in social nesting groups called colonies; the degree of colony 

formation varies among species. Much of the deep ocean is relatively devoid of avifauna because of low 

concentrations of nutrients for phytoplankton. However, certain oceanic conditions including upwelling, 

convergences, divergences, specific sea-surface temperatures, thermal fronts, salinities, areas of high 

planktonic productivity, or current activity create veritable oases for foraging seabirds. Seabirds obtain 

their food through a variety of behaviors including kleptoparasitism, scavenging, dipping, plunge diving, 

and surface feeding. Impacts of widespread dispersed oil from the DWH event may have had serious 

impacts on pelagic birds feeding in oiled waters and/or on oiled prey. The baseline for pelagic birds in 

the affected environment of the proposed action may have been negatively affected. Nesting terns include 

Caspian (Sterna caspia), royal (S. maxima), sandwich (S. sandvicensis), common (S. hirundo), Forster’s 

(S. forsteri), coastal least (S. antillarum), gull-billed (Sterna nilotica), and sooty (S. fuscata). All of the 

terns nesting in the GOM, as well as the Arctic tern (S. paradisaea), bridled tern (S. anaethetus), black 

tern (Chlidonias niger), brown noddy (Anous stolidus), and black noddy (Anous minutus), are found in 

blue water in the northern GOM (Cardiff, personal communication, 2006). Most of these species forage 

exclusively on small fish and feed by plunge diving, often from a hovering position. Terns, and gannets 

and boobies (Sula spp.) as well, are streamlined for plunge diving and the underwater pursuit of fish. All 

seabirds are colonial nesters and all evolved from colonial land birds. Most land birds are not colonial 

nesters (Lack, 1968). A discussion of the colonial breeding of seabirds is relevant to their increased 

potential vulnerability to anthropogenic noise, as presented in Chapter 3.2.6.1 of the Multisale EIS. The 

collective feeding characteristic of many colonial nesters and other birds is also discussed. The small 

body-size of terns is a factor in their vulnerability to OCS-related activities and their general ecology, as 

discussed in the Multisale EIS. 

Shorebirds 

Shorebirds are members of the order Charadriiformes and are generally restricted to coastline and 

inland water margins (e.g., beaches, mudflats, etc.). The Gulf of Mexico shorebirds comprise five 

taxonomic families: Jacanidae (jacanas), Haematopodidae (oystercatchers), Recurvirostridae (stilts and 

avocets), Charadriidae (plovers), and Scolopacidae (sandpipers, snipe, and allies) (Hayman et al., 1986). 

Most of the shorebirds are solitary nesters. Along the central Gulf Coast, 44 species of shorebirds have 

been recorded. However, only 6 species are known breeders in the area; the remaining 38 species are 

considered winter residents and/staging migrants (Pashley, 1991). 

Many of the overwintering shorebird species remain within specific areas throughout the season and 

exhibit among-year wintering site fidelity, at least when not disturbed by humans. These species may be 
Description of the Environment and Impact Analysis 4-221 

especially susceptible to localized impacts, resulting in habitat loss or degradation unless they move to 

more favorable habitats when they are disturbed by humans.

An important characteristic of almost all shorebird species is their strongly developed migratory 

behavior, with some shorebirds migrating from nesting places in the high Arctic tundra to the southern 

part of South America (Morrison 1984; Terres, 1991; Morrison et al., 2000, 2001, and 2006). Their 

migratory abilities expose them to a constraint perhaps more than other, less capable migrants. A recent 

study shows that all Arctic-breeding shorebirds (worldwide) tend to avoid migration routes that require 

individuals to negotiate barriers, including the Arctic Ocean itself, where landing and feeding cannot take 

place (Henningsson and Alerstam, 2005). 

Both spring and fall migrations take place in a series of stops among various staging areas where 

birds spend time feeding heavily to store up fat for the sustained flight to the next staging area (Skagen 

and Knopf, 1993; Deleon and Smith, 1999; Farmer and Durbian, 2006; Krapu et al., 2006; Skagen et al., 

2008); many coastal habitats along the GOM are critical for such purposes. Shorebird species of 

conservation concern in coastal Louisiana are dunlin, short-billed dowitcher, marbled godwit, American 

oystercatcher, and the piping, Wilson’s, and snowy plovers. Birds that migrate through or winter along 

the northern Gulf of Mexico in fall may have just experienced impacts from the DWH event, and it is not 

yet clear if any bird taxa will be altered by the spill. Many transients, including most calidrid sandpipers, 

nest in Arctic Canada and Alaska. They feed on insects, a variety of marine and freshwater invertebrates, 

fish, and small amounts of plant life. Coastal sandpipers may not find adequate food in nontidal habitats 

with a static shoreline because of insufficient size of invertebrate forage populations. 

Shorebirds, including sandpipers, have adapted to utilize highly ephemeral habitats, including 

advancing and/or receding with the changing shoreline of wetlands transiently exposed over a 

substantially greater area (relative to narrow, linear, nontidal wetlands) to lunar, solar, or wind-driven 

tides. Sandpiper legs are moderately long for wading and foraging just seaward of the shoreline, and their 

bills and necks are moderately long for pecking on small invertebrates on the sediment surface or probing 

beneath the sediment. Plovers are adapted to follow solar, lunar, or wind tides in and out, foraging just 

landward of the water’s edge. Not being waders, plovers often have relatively shorter bills, necks, and 

legs than sandpipers. Rising tides and low wave action would cause or facilitate accumulation of oil in 

intertidal vegetation and on soft-bottom flats, which are foraging grounds for these species. Substantial 

wave action and falling tides could offer some recurrent seaward transport of oil; such processes could 

ameliorate accumulation of intertidal oil. 

Passerine Birds 

Passerine birds mostly migrate across the Gulf of Mexico each spring and fall and are protected under 

the Migratory Bird Treaty Act. A study of platforms as possible resting sites for birds crossing the Gulf 

was completed (Russell, 2005) and is summarized in Chapter 3.2.6.1 of the Multisale EIS. Migrants 

sometimes arrived at certain platforms shortly after nightfall and proceeded to circle those platforms for 

variable periods ranging from minutes to hours. These nocturnal circulations clearly occurred because 

nocturnal migrants were attracted to platform light and tended to occur on overcast nights. Such 

circulation prevails when birds get inside the cone of light surrounding the platform and are reluctant to 

leave, seemingly becoming trapped by the surrounding “wall of darkness” and loss of visual cues to the 

horizon. Circulations put birds at risk for collision with the platform or with each other, as well as result 

in energetic deficits exacerbating migration-induced mortality via starvation (Russell, 2005). 

Marsh and Tall Wading Birds 

Collectively, the following families of tall wading birds have representatives in the northern Gulf: 

Ardeidae (herons and egrets), Ciconiidae (storks), Threskiornithidae (ibises and spoonbills), and Gruidae 

(cranes). The common wading birds in the northern GOM are listed with their main features in Table 3-7

of the Multisale EIS. A census of south Louisiana wading bird nesting colonies was completed in 2001 

(Michot et al., 2003). Wading birds are those birds that have adapted to living in shallow water. They 

have long legs that allow them to forage by wading into shallow water, while their long bills, usually 

accompanied by long necks, are used to probe under water or to make long swift strokes to seize fish, 

frogs, aquatic insects, crustaceans, and other prey (Terres, 1991). In coastal Louisiana, species of special 

concern include the ardeids reddish egret, yellow-crowned night heron, and American bittern; the ciconiid 
4-222 Central Planning Area Supplemental EIS 

wood stork (in freshwater marshes), which is federally listed as endangered in Alabama and Florida; and 

the gruid whooping crane, which is federally listed as endangered in Texas and which has a planned, 

experimental-introduced population in Louisiana. Seventeen species of wading birds in the Order 

Ciconiiformes are currently known to nest in the northern Gulf coastal region, and all except the wood 

stork nest in the northern Gulf coastal region (Martin, 1991). Within the central Gulf Coast region, 

Louisiana supports the majority of nesting wading birds (Miller and Fontenot, 2001, Rappole, 2006). 

Nests tend to be concentrated in freshwater riparian bottomland hardwood forest wetlands. Great egrets 

are the most widespread nesting species in the central Gulf region (Martin, 1991), while little blue herons, 

snowy egrets, and tricolored herons constitute the greatest number of coastal nesting pairs in the western 

Gulf Coast (Texas Parks and Wildlife Department, 1990). The term “marsh bird” is a general term for a 

bird that lives in or around marshes and swamps. Members of the Rallidae family (rails, including 

moorhens, and gallinules) are labeled marsh birds and not wading birds. 

Waterfowl 

Waterfowl belong to the taxonomic order Anseriformes and include swans, geese, and ducks. A total 

of 33 species are regularly reported along the north-central and western Gulf Coast, consisting of 1 swan, 

5 geese (i.e., greater white-fronted [Anser albifrons], Ross’s [Chen rossii], snow [C. caerulescens], 

Canada [Branta canadensis], and Brant [B. brenicla]), 8 surface-feeding (dabbling) ducks (genus Anas; 

i.e., mallard, mottled, American wigeon, northern pintail, northern shoveler, blue-winged teal, American 

green-winged teal, and gadwall); 5 diving pochards (genus Aythya; canvasback, redhead, lesser scaup, 

greater scaup, and ring-necked duck), and 14 others (including the wood duck [Aix sponsa], fulvous 

whistling ducks [Dendrocygna bicolor], black-bellied whistling duck [D. autumnalis], bufflehead 

[Bucephala albeola], common goldeneye [B. clangula], hooded merganser [Lophodytes cucculatus], 

red-breasted merganser [Mergus serrator], and ruddy duck [Oxyura jamaicensis]) (Clapp et al., 1982b; 

National Geographic Society, 1999; Madge and Burn, 1988; Alsop, 2001). The common waterfowl in the 

northern GOM are listed with their main features in Table 3-8 of the Multisale EIS. Many species usually 

migrate from wintering grounds along the Gulf Coast to summer breeding grounds in the prairies, 

parklands, and tundra in the north. Waterfowl migration pathways have traditionally been divided into 

four parallel north-south paths, or “flyways,” across the North American continent (Bellrose 1980). The 

Gulf Coast serves as the southern terminus of both the Central (Texas) and Mississippi (Louisiana, 

Mississippi, and Alabama) flyways, and winters an estimated 8-10 million ducks, 500,000 geese, and 

1-1.5 million American coots (Bellrose, 1980; Chabreck et al., 1989; Hobaugh et al., 1989; Stuzenbacker 

and Weller, 1989). Waterfowl are highly social and possess a diverse array of feeding adaptations related 

to their habitat (Johnsgard, 1975; Poysa, 1983; Nudds, 1983 and 1992). Waterfowl young are precocial, 

leaving their nests relatively soon after they hatch and, thus, they are capable of swimming and feeding. 

Most waterfowl species in the northern Gulf of Mexico are winter residents and migrate far to the north to 

breed (Sibley, 2000; Alsop, 2001). Herbivorous geese must eat relatively more food than most 

omnivorous or carnivorous waterbirds like ducks. Geese digest little of the vegetation they gorge on 

because much of it is indigestible. Feces can provide immediate cycling of nitrogen in nitrogen-limited 

vegetation. 

Raptors 

The American peregrine falcon was removed from the endangered species list on August 25, 1999 

(Federal Register, 1999). The species is still protected under the Migratory Bird Treaty Act. The FWS 

will continue to monitor the falcon’s status 5 times at 3-year intervals beginning in 2003 and ending in 

2015 to ensure that recovery is established. The bald eagle was delisted on August 8, 2007. It is still 

afforded some protection under the Migratory Bird Treaty Act. The Northern harrier is listed as a species 

of concern in Louisiana. It forages in salt, brackish, intermediate, and fresh marsh and coastal dunegrassland shrub thicket habitat. 

Effects of Hurricanes Katrina and Rita on Baseline Conditions 

A detailed summary of impacts of the hurricanes on birds is provided in Chapter 3.2.6 of the 

Multisale EIS. Hurricanes may exacerbate impacts of OCS-related and cumulative impacts on coastal 
Description of the Environment and Impact Analysis 4-223 

and marine birds. Hurricanes Katrina and Rita have impacted avian habitats throughout the Gulf. Large 

areas of coastal wetlands have been converted to open-water habitat, potentially affecting avian species 

that used the wetlands for foraging, nesting, and as stopover points during migration (Gabe et al., 2005). 

Impacts to these habitats have the potential to result in population-level impacts affecting both abundance 

and distribution of some species. For example, the coastal habitats that were significantly impacted in 

southeastern Louisiana and the Galveston Bay area of Texas support nesting by up to 15 percent of the 

world’s brown pelicans and 30 percent of the world’s sandwich terns (Hunt, personal communication, 

2006). Impacts to these habitats could reduce future nesting success and affect overall population levels 

of these species. Impacts to bottomland forest habitat along the Louisiana and Mississippi coasts 

represent further loss of avian habitat, affecting many different species; up to 70 percent of the cavity 

trees used by the endangered red-cockaded woodpecker at Big Branch Marsh National Wildlife Refuge in 

St. Tammany Parish, Louisiana, were destroyed (Hunt, personal communication, 2006). The long-term 

effects of avian habitat loss because of these hurricanes is not known, and agencies including FWS and 

USGS are implementing numerous studies and monitoring programs to determine the extent and 

magnitude of impacts to affected avian populations. 

After Hurricane Rita, the Chenier Plain in western Louisiana was sampled for plant and animal food 

for neotropical migrant birds. Saltwater intrusion killed almost all crawfish being raised in ponds, and it 

also killed freshwater vegetation there; reptiles, especially amphibians, were also killed by flooding 

saltwater moving inland. 

Effect of the Deepwater Horizon Event on Baseline Conditions 

The DWH event may have exacerbated the impacts of OCS-related and cumulative impacts on 

coastal and marine birds. When oil gets into vegetated or unvegetated sediment, low redox potentials, 

absence of light, and waterlogged substrate may mean that the oil can neither be oxidized by bacteria and 

sunlight nor evaporate. The oil may remain in its unweathered toxic state indefinitely. However, oil 

weathering as it travels to the coast ameliorates toxicity at the shoreline. The oil from the DWH event has 

had serious direct and indirect impacts to coastal and marine birds, but it is premature to report the 

welfare of any population as altered over a long period (RestoreTheGulf.gov, 2010i; Tables 4-4, 4-5, and 

4-6; Figure 4-14). 

Birds that are heavily oiled are usually killed. If physical oiling of individuals or local groups of birds 

occurs, some degree of both acute and chronic physiological stress associated with direct and secondary 

uptake of oil would be expected. Lightly oiled birds can sustain tissue and organ damage from oil 

ingested during feeding and grooming or from oil that is inhaled. Such birds may appear healthy, but 

they may be affected by stress that does not occur until much later. Stress and trauma enhance the effects 

of exposure and poisoning. In the Gulf of Mexico, winter resident waterfowl could suffer substantially if 

considerable oiling of their preferred foraging or roosting habitats occurred, primarily in coastal marshes. 

Substantial oiling could cause local extinction of goose populations unable to find adequate food on 

unoiled marshes or in agricultural fields. 

Lighter PAH’s like naphthalene and anthracene are volatile and water-soluble, but they are somewhat 

more persistent compared with lighter, more volatile, and more water-soluble hydrocarbons like benzene. 

Their impacts are discussed in detail in Chapter 4.1.1.12.3. 

Endangered and Threatened Species 

A detailed description of endangered and threatened coastal and marine bird species can be found in 

Chapter 3.2.6.2 of the Multisale EIS. The following is a summary of the information presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, which incorporates new information found since the 

publication of these documents. 

The Multisale EIS included the bald eagle in the discussion of the endangered and threatened species. 

However, on June 28, 2007, FWS announced the removal of the bald eagle from the list of endangered 

and threatened species (Federal Register, 2007). The FWS will work with State wildlife agencies to 

monitor bald eagles for at least 5 years. The FWS can propose to relist the species if it appears that bald 

eagles again need the protection of the Endangered Species Act. The bald eagle will continue to be 

protected by the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. Both Federal 

laws prohibit “taking” (i.e., killing, selling, or otherwise harming eagles, their nests, or eggs). 
4-224 Central Planning Area Supplemental EIS 

The Multisale EIS included the brown pelican in the discussion of the endangered and threatened 

species. However, the brown pelican was removed from the list of endangered and threatened wildlife on 

November 17, 2009 (USDOI, FWS, 2009). 

Coastal and marine bird species that inhabit or frequent the north-central and western Gulf of Mexico 

coastal areas and that are recognized by FWS as either endangered or threatened include the piping plover 

and whooping crane. 

Piping Plover 

The piping plover (Charadrius melodus) is a migratory shorebird that is endemic to North America. 

The piping plover breeds along shorelines in the northern Great Plains, the Great Lakes, and along the 

Atlantic Coast (Newfoundland to North Carolina). It winters on the Atlantic and Gulf Coasts from North 

Carolina to Mexico and in the Bahamas West Indies. The final rule on critical habitat for the piping 

plover was published July 10, 2001; there are 20 units of critical habitat in western Florida south to 

Tampa Bay, 3 areas in Alabama, 15 in Mississippi, 7 in Louisiana, and 37 in Texas (Federal Register, 

2001). Critical wintering habitat includes the land between mean low water and any densely vegetated 

habitat that is not used by the piping plover. The piping plover is listed as endangered on its Great Lakes 

breeding grounds. It is listed as threatened in the Gulf of Mexico and the rest of its wintering and 

breeding range. The habitats used by wintering birds include beaches, mud flats, sand flats, algal flats, 

and washover passes (areas where breaks in the sand dunes result in an inlet). Wintering plovers are 

dependent on a mosaic of habitat patches and move among these patches depending on local weather and 

tidal conditions. It has been hypothesized that specific wintering habitat, which includes coastal sand 

flats and mud flats in close proximity to large inlets or passes, may attract the largest concentrations of 

piping plovers because of a preferred prey base and/or because the substrate color provides protection 

from aerial predators due to cryptic blending camouflage color (Nicholls and Baldassarre, 1990). The 

migration of the piping plover is poorly understood. They begin arriving on the wintering grounds in July 

and continue arriving through September. In late February, piping plovers begin leaving the wintering 

grounds to migrate back to their breeding sites. Northward migration peaks in late March, and by late 

May most birds have left the wintering grounds. Vegetation imposes an extreme threat of predators on 

breeding adults. On the northern breeding grounds, river alteration and reservoir creation cause high 

water flow where birds once relied on exposed sand bars to breed. However, diversion of peak flows in 

northern nesting habitat is also harmful. The result is the encroachment of vegetation that is usually kept 

under control by scour during high river flows. This species remains in a precarious state given its low 

population numbers, sparse distribution, and continued threats to habitat throughout its range. About 

2,299 birds were located on the U.S. wintering grounds during the 2001 census (Haig and Ferland, 2002). 

During the winter 2006 census, 321 birds were counted on the Gulf Coast of Florida; 29 in Alabama; 78 

in Mississippi; 226 in Louisiana; and 2090 in Texas (Elliot-Smith et al., 2009). The highest numbers of 

wintering plovers occurred along the Texas coast (43.6%), with Louisiana ranked second (21.4%). Piping 

plovers were commonly found on mud flats (36.3%), sandy beaches (33.2%), and sand/salt flats (23.1%) 

(Haig and Ferland, 2002). 

Whooping Crane 

The whooping crane (Grus americana) is an omnivorous, wading bird. Whooping cranes currently 

exist in three wild populations and at five captive locations (USDOI, FWS, 1994). All of the populations 

are listed as endangered. The only self-sustaining wild population nests in the Northwest Territories and 

adjacent areas of Alberta, Canada, primarily within the boundaries of Wood Buffalo National Park. 

These birds winter in coastal marshes and estuarine habitats along the Gulf Coast in the Aransas National 

Wildlife Refuge in Texas, and they represent the majority of the world’s population of free-ranging 

whooping cranes. Another wild flock was created with the transfer of wild whooping crane eggs from 

nests in the Wood Buffalo National Park to be reared by wild sandhill cranes in an effort to establish a 

migratory Rocky Mountains Population (USDOI, FWS, 1994). This population summers in Idaho, 

western Wyoming, and southwestern Montana, and it winters in the middle Rio Grande Valley, New 

Mexico. The third wild population is the first step in an effort to establish a nonmigratory population in 

Florida (USDOI, FWS, 1994). The 2007 wild populations were estimated to total 355; the captive 

population contained 148 birds (Stehn, personal communication, 2007). 
Description of the Environment and Impact Analysis 4-225 

4.1.1.14.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of the coastal and marine birds for the CPA proposed action can be found 

in Chapter 4.2.1.1.7 of the Multisale EIS, and any new information since publication of the Multisale EIS 

is presented in Chapter 4.1.9.2 of the 2009-2012 Supplemental EIS. The following information is a 

summary of the routine events incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, 

and new information that has become available since both documents were prepared. 

The possible effects of routine activities on coastal and marine birds of the Gulf of Mexico and 

contiguous waters and wetlands are discussed below. Federally listed endangered or threatened bird 

species are included in this discussion with nonlisted species because the potential impacts are the same 

or very similar. Major, potential impact-producing factors for marine birds in the offshore environment 

include OCS-related helicopter and service-vessel traffic and associated noise, air emissions, degradation 

of water quality, habitat degradation, discarded trash and debris from service-vessels and OCS structures, 

and structure presence and associated light and presence. Any effects on birds are especially dire for 

intensively managed threatened and endangered populations. For example, endangered and threatened 

species may be harmed by any impact on viable reproductive population size or destruction of or 

disturbance around key habitats. 

Fidelity to coastal and marine bird nesting sites varies from year-to-year along the Gulf Coast. Site 

abandonment along the northern Gulf Coast has often been attributed primarily to habitat alteration and 

excessive human disturbance (Martin and Lester, 1991). Many of the overwintering shorebird species 

remain within specific areas throughout the season and exhibit among-year wintering site fidelity, at least 

when not disturbed by humans. These species may be especially susceptible to localized impacts, 

resulting in habitat loss or degradation unless they move to more favorable habitats when they are 

disturbed by humans. 

The effects of disturbance by air or vessel traffic to birds are highly variable. Behavior patterns may 

be temporarily influenced (e.g., change from foraging behavior to alert behavior) or birds may be 

temporarily or permanently displaced. Reproductive behaviors including pair formation and courtship 

displays may be interrupted; breeding birds may become habituated to noise and the presence of humans 

(Nisbet, 2000). Aircraft may be forced to fly below legal (Federal Aviation Administration or FWS) 

minimum altitudes in inclement weather, possibly increasing disturbance effects on birds. 

Air pollution may cause physiological impairment and further lead to diseases. Effects may vary 

from lethal to sublethal and from short term to long term. Nonpolar, hydrophobic pollutants become a 

special problem for long-distance migrant birds that rely on fat deposits for extra energy requirements. 

More fat will hold more of that kind of pollutant. Migrants are generally sensitive to airborne toxins 

because of sustained high ventilation rates required for flight. Indirect effects of air emissions include 

adverse synergistic effects with other stressors and shifts in food supplies. Acid deposition affects the 

forest forging habitat of birds. Air emissions may cause changes in bird distribution and abundance, but 

the emissions must be diagnostically separated from other possible factors (e.g., weather and food 

supplies) that could have the same effect. 

The impacts of discharges into water vary from short term to long term and from sublethal to lethal. 

Impacts may be from ingestion or contact (direct) or from the changes in the distribution, composition, or 

abundance of preferred foods (indirect). Discharges may affect the breeding success of seabird nesting 

colonies prevalent along the shores of the northern Gulf of Mexico. Maintenance dredging and 

resuspension of sediment in canals and navigation channels increases turbidity over time. Birds feeding 

in such waters would likely experience chronic, sublethal impacts. 

Habitat and plant substrates can be described as the physical environment used by a bird. Birds select 

their habitat at various times in their life histories according to their needs. The greatest negative impact 

to coastal and marine birds is the loss or degradation of preferred or critical habitat and, for a threatened 

or endangered species, this may result in global extinction. This discussion applies to both federally 

listed endangered/threatened bird species and nonlisted species, since the effects are the same or very 

similar. The extent of bird displacement resulting from habitat loss is highly variable among species, 

based upon specific habitat requirements, which for many species is poorly understood. As displaced 

birds move to undisturbed areas of apparently similar habitat, the presence of additional conspecifics may 
4-226 Central Planning Area Supplemental EIS 

exert additional pressure on the habitat, as a result of intra- and interspecific competition for space or 

food. 

Pipeline landfalls and terminals, and other onshore OCS-related construction, can alter or destroy 

wetland habitat, resulting in displacement of associated avian communities. Seabird nesting colonies are 

particularly sensitive and should always be avoided by construction activities. Environmental regulations 

require replanting and restoration of wetlands destroyed by pipelaying barges and associated onshore 

pipeline installation. However, onshore pipelines cross a wide variety of coastal environments and can 

therefore affect certain species generally not associated with freshwater, marine, or estuarine systems. 

The northern Gulf of Mexico and areas inland from it have a large diversity of habitats for a variety of 

avian species including migrants and breeding and wintering birds. 

Seabirds ingest plastic objects and other marine debris more frequently than do any other taxon 

(Ryan, 1990). Interaction with plastic materials may lead to permanent injuries and death. The effects of 

plastic ingestion may be long-term and may include physical deterioration due to malnutrition; plastics 

often cause a distention of the stomach, thus preventing its contraction and simulating a sense of satiation 

(Ryan, 1988). The chemical toxicity of some plastics can be high, posing a hazard in addition to 

obstruction and impaction of the gut (Fry et al., 1987). Some birds also feed plastic debris to their young, 

which could reduce fledging success and offspring survival rates. As a result of stress from the 

consumption of debris, individuals may weaken, facilitating infection and disease; migratory species may 

then not have the energetic capacity to initiate migration or complete the migration process. 

Proposed Action Analysis 

The transportation or exchange of supplies, materials, and personnel between coastal infrastructure 

and offshore oil and gas structures is accomplished with helicopters, aircraft, boats, and a variety of 

service vessels (Table 3-2). It is projected that 1,004,000-2,241,000 helicopter operations related to the 

CPA proposed action would occur over the life of the proposed action; this is a rate of 25,100-56,025 

annual helicopter operations. Service vessels would use selected nearshore and coastal (inland) 

navigation waterways, or corridors, and adhere to protocol set forth by USCG for reduced vessel speeds 

within these inland areas. It is projected 137,000-220,000 service-vessel round trips related to the CPA 

proposed action would occur over the life of the proposed action; this is a rate of 3,425-5,500 servicevessels trips annually. In laboratory experiments, factors determining an animal’s susceptibility to noiseinduced damage, such as species, age, auditory range, and recovery process can be controlled. Memphis 

State University (1971) mentions “the large, well-done body of literature exploring the effects of noise 

upon auditory structures and hearing.” 

Animals exposed intermittently to noise had less impact than animals exposed continuously 

(Memphis State University, 1971). The extent of noise-induced impacts depends on the intensity, 

frequency spectrum, duration, pattern of exposure, and individual susceptibility. Noise-induced stress 

may have increased impacts if combined with other stress. Memphis State University (1971) implies that 

studies of relatively less intense noise pollution such as that from helicopters and service vessels are few. 

Disturbances from OCS-related helicopter or service-vessel traffic to coastal birds can result from the 

mechanical noise or physical presence (or wake) of the vehicle. This discussion applies to both federally 

listed endangered/threatened bird species and nonlisted species since the effects are the same or very 

similar. 

The Federal Aviation Administration and corporate helicopter policy advise helicopters to maintain a 

minimum altitude of 700 ft (213 m) while in transit offshore and 500 ft (152 m) while working between 

platforms. When flying over land, the specified minimum altitude is 1,000 ft (305 m) over unpopulated 

areas or across coastlines and 2,000 ft (610 m) over populated areas and biologically sensitive areas such 

as wildlife refuges and national parks. Many undisturbed coastal areas and refuges provide preferred and/

critical habitat for feeding, resting (or staging), and nesting birds. 

Flushing from the nest is the only behavioral response in raptors that is known to be correlated with 

severe impact from helicopter overflights (Awbrey and Bowles, 1990). Flushing may exert its influence 

by having eggs and young kicked out of a nest, exposed to predators, and exposed to potential negative 

effects of cold or heat stress (inclement weather). Important raptors include the bald eagle and peregrine 

falcon, recently both federally delisted as endangered or threatened species. These species may exhibit 

impacts from helicopters similar to other raptors previously studied. 
Description of the Environment and Impact Analysis 4-227 

A synthesis of literature on impacts of helicopter and other aircraft overflights on raptors by Awbrey 

and Bowles (1990) is presented as follows (with additional information from Frid and Dill, 2002). 

Sometimes flushing, alertness, and other antipredator responses to nonlethal stimuli should become 

stronger with repeated exposure to the stimuli (Frid and Dill, 2002). This conclusion is especially 

important because studies on human disturbance of birds sometimes incorrectly state or imply that birds 

always become accommodated to noise. Sensitization sometimes occurs instead. For example, loom rate 

is the rate at which a predator or human disturbance proxy for a predator increases in size as it 

approaches; loom rate is higher for nearby predators than for distant predators. As multiple exposures to 

the stimuli at different distances occur, the bird should increase its flight initiation distance to stimuli with 

higher loom rates because as the bird will associate the high rate with closeness of the predator, becoming 

sensitized rather than habituated because the bird learns to recognize this high-loom-rate cue to danger of 

close predator approach (Frid and Dill, 2002). 

Flushing has a higher probability early in the breeding season. The cause of this increased likelihood 

is perhaps later habituation. Another potential cause is increased attention to nesting as the breeding 

season proceeds. This increase in parental attentiveness with time could result because as this season 

progresses, renesting success declines and the cost of parental investment in a first nest increases. The 

bald eagle and peregrine falcon, cliff and tree nesting raptors, often experience low levels of egg 

predation, probably less than ground-nesting raptors; flushing may be relatively less important for these 

two species. “Nonspecific” stimuli, where the bird does not identify (specify) the disturbing stimulus as a 

human (when the disturbing agent was a car or an aircraft, for example), drive raptors away from feeding 

areas only briefly 

Birds can lose eggs and young when predators attack nests after parents are flushed into flight by 

service-vessel noise. Overall breeding success (ratio of fledged birds per nest to hatched birds per nest) 

may be reduced. Chronic effects on breeding are especially serious for endangered or threatened species 

because subsequent recovery may not be possible or may be delayed. Routine presence and low speeds of 

service vessels within inland and coastal waterways would possibly reduce the effects of disturbance from 

service vessels on nearshore and inland populations of coastal and marine birds. 

Contamination of wildlife by air emissions can occur in three ways: inhalation, absorption, and 

ingestion. Inhalation is the most common mode of contamination for birds (Newman, 1980). Levels of 

sulfur oxide (mainly SO2) emissions from hydrocarbon combustion from OCS-related activities are of 

concern in relation to birds. 

The indirect effects of air emissions on wildlife include food web contamination and habitat 

degradation, as well as adverse synergistic effects of air emissions with natural and other manmade 

stresses. Air pollutants may cause a change in the distribution of certain bird species (e.g., Newman, 

1977; Llacuna et al., 1993). 

Chapter 4.1.1.1.2 provides an analysis of the routine effects of the proposed action on air quality. 

Emissions of pollutants into the atmosphere from the activities associated with the proposed action would 

have minimum effects on offshore and onshore air quality because of the prevailing atmospheric 

conditions, emission heights and rates, and pollutant concentrations. The NAAQS concentrations are far 

below concentrations that could harm coastal and marine birds. The most likely pathway for air pollution 

to affect birds is through acidification of inland waterbodies and soils, and a subsequent change in trophic 

structure (Environmental Science & Research, 1998). 

Chapters 4.1.1.2.1.2 and 4.1.1.2.2.2 provides an analysis of the effects of the CPA proposed action 

on water quality. This discussion applies to both federally listed endangered/threatened bird species and 

nonlisted species since the effects are the same or very similar. Expected degradation of coastal and 

estuarine water quality resulting from of OCS-related discharges may affect coastal birds directly by 

means of acute or chronic toxic effects from ingestion or contact, or indirectly through the contamination 

of food sources or habitat loss/degradation. Operational discharges or runoff in the offshore environment 

could also affect seabirds (e.g., laughing gulls) that remain and feed in the vicinity of offshore OCS 

structures and platforms. These impacts could also be both direct and indirect. Many seabirds feed and 

nest in the Gulf; therefore, water quality may also affect breeding success (measured as the ratio of 

fledged birds per nest to hatched birds per nest). Produced water is an operational discharge containing 

hydrocarbons, trace heavy metals, radionuclides, sulfates, treatment chemicals, and produced solids that 

represents most of the waste discharged from offshore oil extraction production facilities (Fraser et al., 

2006). The relationship between produced-water discharge and oil sheens is not well understood. In cold 
4-228 Central Planning Area Supplemental EIS 

waters, oiled birds (especially divers) lose insulation and may die from hypothermia (Fraser et al., 2006); 

even contact with thin sheens have the potential to reduce water repellency and insulative characteristics 

of feathers (O’Hara and Morandin, 2010; see also Stephenson, 1997). The maximum allowable 

hydrocarbon concentration in the U.S. is an average of 29 mg/L per month for the OCS and specifies a 

maximum (daily average) of 42mg/L daily; events that may cause sheens (USEPA, 2004, in Fraser et al., 

2006, p. 149). Assertions that the dilution potential of the ocean as a receiving environment makes ocean 

discharge an effective waste treatment for produced water have no supporting evidence. Field evidence 

that any contact between a bird and oil or oily water will be lethal without rehabilitation is also lacking 

(Fraser et al., 2006). The null hypothesis that produced water and resulting sheens do not kill birds needs 

to be tested (Fraser et al., 2006). 

The analysis of the potential impacts to coastal environments (Chapter 4.1.1.3.2) concludes that the 

CPA proposed action is not expected to adversely alter barrier beach configurations significantly beyond 

existing, ongoing impacts in very localized areas downdrift of artificially jettied and maintained channels. 

Adverse impacts of pipeline and navigation canals are the most significant OCS-related and proposedaction-related impacts to wetlands that may be used by many species of birds. Initial impacts are locally 

significant and largely limited to where OCS-related canals and channels pass through wetlands. For the 

CPA proposed action, 0-1 new pipeline landfalls (Chapter 4.1.2.1.7 of the Multisale EIS) and 0-1 new gas 

processing plants (Chapter 4.1.2.1.4.2 of the Multisale EIS) are projected. 

Coastal and marine birds are susceptible to entanglement in floating, submerged, and beached marine 

debris; specifically in plastics discarded from both offshore sources and land-derived litter and waste 

disposal (Heneman and the Center for Environmental Education, 1988). This discussion applies to both 

federally listed endangered/threatened bird species and nonlisted species since the effects are the same or 

very similar. It is expected that coastal and marine birds would seldom become entangled in or ingest 

OCS-related trash and debris as a result of BOEMRE prohibitions on the disposal of equipment, 

containers, and other materials into offshore waters by lessees (30 CFR 250.40). In addition, MARPOL, 

Annex V, Public Law 100-220 (101 Statute 1458), which prohibits the disposal of any plastics, garbage, 

and other solid wastes at sea or in coastal waters, went into effect January 1, 1989, and is enforced by 

USCG. 

Each spring, migratory land birds, including neotropical passerines that cannot feed at the water 

surface or rest there, cross the Gulf of Mexico from wintering grounds in Latin America to breeding 

grounds north of the Gulf of Mexico. Some birds use offshore platforms as stopover sites for this 

migration; this may enhance fitness. However, the quantity of natural selection against weak or sick birds 

may be reduced, decreasing the overall vitality of the populations. This discussion applies to both 

federally listed endangered/threatened bird species and nonlisted species since the effects are the same or 

very similar. 

Migrants sometimes arrive at certain platforms shortly after nightfall or later and proceed to circle 

those platforms (the phenomenon is called a nocturnal circulation event) for variable periods ranging from 

minutes to hours. Russell (2005) notes that, “because of the anecdotal nature of our circulation 

observations, we are reluctant even to speculate about the average duration of participation in circulation 

or the typical energetic consequences of participating in these events.” On the other hand, Weir (1976) 

states “nocturnal kills are virtually certain wherever a lit obstacle extends into an air space where birds are 

flying. The magnitude of the kill would be determined by the time of year, location, height, light and 

cross-sectional areas of the obstacle and weather conditions.” Circulations increase the risks for birds to 

collide with platform structures and with each other. Large attractions to lights and collision mortalities 

are mostly during overcast nights with drizzle and fog. The attractive effect of lights during cloudy nights 

is enhanced by fog, haze, or drizzle when moisture droplets in the air refract the light and greatly increase 

the illuminated area (Wiese et al., 2001). Starving, exhausted, circulating birds may land on the 

platforms. Birds that dropped out of nocturnal circulations sometimes became trapped in well-lit interior 

areas of platforms, and these birds appeared sublethally stressed (Russell, 2005). However, a total of 140 

birds on the nine platforms were recorded as dead because of starvation for the entire spring of 2000 study 

period (Russell, 2005). More detail is presented in Chapter 4.2.1.1.7 of the Multisale EIS. It is projected 

that 32-44 production structures are projected to be installed as a result of the CPA proposed action 

(Table 3-2). Nocturnal circulation on these platforms is assumed to have minimal and mostly sublethal 

impacts on migrating bird populations. This conclusion results from the confirmed low mortality from 

starvation for all birds that landed on the platforms examined by Russell (2005) and from the suggested 
Description of the Environment and Impact Analysis 4-229 

sublethal stress in birds that dropped out of circulation. The presence of a drilling rig may attract seabird 

prey (invertebrates and/or fish) to a site, causing an increase in seabird abundance there relative to bird 

density away from the rig or at the rig during pre-spudding (Baird, 1990). The discharge of human waste 

from a rig may fertilize the area, leading to increases in seabird prey (Wiese et al., 2001). For some 

seabirds, such as shearwaters, offshore oil platforms have become sites where otherwise patchy or scarce 

prey are more predictable and concentrated (Wiese et al., 2001). Storm-petrels and other procellariiforms 

forage at night on vertically migrating bioluminescent prey and are naturally attracted to any kind of light. 

Storm-petrels often fly directly into lights and flares, resulting in death or injury by impact or burning 

(Wiese et al., 2001). 

Summary and Conclusion 

The majority of effects resulting from routine activities with the CPA proposed action on endangered/

and nonendangered/threatened coastal and marine birds are expected to be sublethal. These effects 

include behavioral effects, exposure to or intake of OCS-related contaminants or discarded debris, 

temporary disturbances, and displacement of localized groups from impacted habitats. Chronic sublethal 

stress, however, is often undetectable in birds. As a result of stress, individuals may weaken, facilitating 

infection and disease; migratory species may then not have the energetic reserves necessary to complete 

their migration. Nocturnal circulation around platforms may create acute sublethal stress from energy 

loss and increase the risks of collision, while stopovers on platforms would reduce energy loss. Because 

of regulatory standards for air and water quality, as discussed in Chapters 4.1.1.1, 4.1.1.2.1, and 

4.1.1.2.2, emissions or produced waters should have a small effect on birds. No significant habitat 

impacts are expected to occur directly from routine activities resulting from the CPA proposed action 

because of the distance of these activities from shore. Secondary impacts from pipeline and navigation 

canals to coastal habitats would occur over the long term and may ultimately displace species. These 

activities would occur whether the proposed action was implemented or not; therefore, the proposed 

action itself would not increase these secondary impacts to birds. 

4.1.1.14.3. Impacts of Accidental Events 

A detailed impact analysis of the coastal and marine birds for the CPA proposed action can be found 

in Chapter 4.4.8 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new 

information since publication of the Multisale EIS is presented in Chapter 4.1.9.3 of the 2009-2012 

Supplemental EIS. 

The following is a summary of the information incorporated from the Multisale EIS and the 2009-

2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

Background/Introduction 

This chapter discusses impacts to coastal and marine birds resulting from the CPA proposed action. 

Impact-producing factors include oil spills and oil-spill cleanup. Impact discussions are combined for 

threatened/endangered birds and nonthreatened/nonendangered birds because impacts of oil spills are 

potentially similar for both. 

Oil spills represent the greatest potential direct and indirect impact to coastal and marine bird 

populations. Birds that are heavily oiled succumb to acute toxicity effects shortly after exposure (Clark, 

1984; Leighton, 1993). 

If the physical oiling of individuals or local groups of birds occurs, some degree of both acute and 

chronic physiological stress associated with direct and secondary uptake of oil would be expected. 

The symptoms of oiling are plentiful but are all important because, while resilient or rehabilitated 

birds may quickly recover, symptoms occurring in many birds may cause reduction or loss of whole 

populations. Symptoms of contact with the persistent fraction of crude oil may be the most important 

because that fraction usually has the fate of contacting shallow waters and shorelines and being 

incorporated into wetland sediments. Small coastal spills, pipeline spills, and spills from accidents in 

navigable waterways can contact and affect the different groups of coastal and marine birds, most 

commonly seabirds, divers, marsh and wading birds, waterfowl, and some species of shorebirds. Lightly 
4-230 Central Planning Area Supplemental EIS 

oiled birds can sustain tissue and organ damage from oil ingested during feeding and grooming or from 

oil that is inhaled. Birds that are heavily oiled are usually killed. Lighter PAH’s like naphthalene and 

phenanthrene are volatile and water-soluble, but they are somewhat more persistent compared with 

lighter, more volatile, and more water-soluble hydrocarbons like benzene. They have the greatest impacts 

on birds because of their persistence and high concentration. They are harmful to cell membranes (White 

and Baker, 1999), including the highly specialized membranes of nerve cells (Hell and Ehlers, 2008; 

Byrne and Roberts, 2009) that must function properly for vital behavior to remain adaptive. Thus, low 

levels of oil could deleteriously affect behavior and therefore could interfere with food detection, feeding 

impulses, adaptive changes in food preferences and the ability to discriminate between poor versus ideal 

food sources and ideal sources, predator avoidance, definition and defense of breeding and feeding 

territories, recognition of family members, and homing of migratory and philopatric species. The toxicity 

profile for alkylated naphthalene and phenanthrene in birds has been insufficiently characterized (Klasing 

et al., 2007). Naphthalene fed to birds resulted in reduced food consumption, reduced growth rate, and 

six physiological disorders (Klasing et al., 2007). Naphthalene had no impact on several reproductive 

traits, internal organs, and 12 blood parameters (Klasing et al., 2007). Systemic inflammation did not 

happen. For chicks hatched from eggs of Japanese quail hens that had ingested naphthalene, growth rate, 

mortality, and two blood parameters were unaffected (Klasing et al., 2007). 

The mandatory use of waterbird feeding areas at the sea surface and intertidal wetland zone, where 

spilled oil tends to accumulate, makes the birds vulnerable to exposure to oil. Wetland sediments have 

low oxygen diffusion rates and are waterlogged and therefore not aerated with oxygen-rich air; hence, 

they have low redox potential (Mitsch and Gosselink, 2007). Oxygen has a very low rate of diffusion 

from the atmosphere through pore water in waterlogged sediment. Oil also diffuses very slowly through 

pore waters to reach the sediment-water interface. Therefore, when oil gets into vegetated or unvegetated 

sediment, low redox potentials (from reduced oxygen availability and oxygen loss through bacterial 

respiration) and absence of light may result in oil that can neither be oxidized by bacteria and sunlight nor 

reach the sediment-water interface and evaporate. The oil may also remain in its unweathered toxic state 

indefinitely. However, weathering-related effects on the oil on its the path to the coast ameliorates, to 

some extent, toxicity at the shoreline. If physical oiling of individuals or local groups of birds occurs, 

some degree of both acute and chronic physiological stress associated with direct and secondary uptake of 

oil would be expected. Affected individual birds may initially appear healthy at first, but they may be 

affected by physiological stress that does not occur until much later. Biochemical impacts of lighter 

PAH’s have not been extensively described, but they could possibly include increased susceptibility to 

physiological disorders including all sorts of disruption of homeostasis, weakened immune systems and 

reduced resistance to disease, and disruption of respiratory functions (Nelson and Cox, 2008; Briggs et 

al., 1996). The internal biochemical environment of the bird has a large number of components, 

interactions, and functions (Nelson and Cox, 2008) that may provide potential points of attack from 

petrochemicals. The network and feedback system nature of the internal environment (Nelson and Cox, 

2008) also provides routes by which an effect on one process can lead to cascading sublethal, chronic 

effects and a myriad of interconnected problems. 

Under natural conditions, water does not penetrate through the vanes of the feathers because air is 

present in the tiny pores in the lattice structure of the feather vane. Birds swimming in dispersant had 

reduced buoyancy and water penetration through the feathers. Dispersants reduce water surface tension 

in the feather lattice pores (they have a surfactant component) and render them water attracting instead of 

water repelling (Stephenson, 1997; Stephenson and Andrews, 1997). Beginning at a certain surface 

tension, water will penetrate the pores of the feathers, and death from reduced thermoregulatory function 

hypothermia may result (Lambert et al., 1982; Stephenson, 1997; Stephenson and Andrews, 1997). 

Dispersants alone cause water penetration of the feathers (Lambert et al., 1982) by reducing the surface 

tension of the water in the pores of the lattice. A much smaller minimum volume (1/100) of oil treated 

with Finasol OSR-5 dispersant, relative to the volume of untreated oil, was required to produce a 

substantial effect on plumage insulation and thermoregulation in eiders (Jenssen, 1994). Even with a 

healthy, water-repellant plumage, waterfowl and seabirds living at medium to high altitudes will, for most 

of the year, require an augmented resting metabolic rate when floating on the water surface, due to the 

water’s relatively high heat conductance and water pressure on the feathers provided by the buoyant force 

on the bird (Stephenson, 1997). In other words, even unoiled feathers do not provide complete insulation 

against cold. 
Description of the Environment and Impact Analysis 4-231 

Ingestion of oil by birds may affect reproductive ability, cause anemia, result in reduced eggshell 

thickness that promotes cracking under the weight of an incubating parent, and cause four physiological 

disorders (Fry et al., 1986; Butler et al., 1988; Velando et al., 2005a and 2005b; Zuberogoitia et al., 2006; 

Zabala et al., 2010; Szaro et al., 1978a and 1978b; Lambert et al., 1982; Rocke et al., 1984; Leighton, 

1993; Fowler et al., 1995; Alonso-Alvarez et al., 2007a; Perez et al., 2010). 

External oiling of eggs may slow embryonic growth, induce tumor growth, reduce gas conductance 

through the eggshell, and decrease hatchability (Jenssen, 1994). Impacts on vital life history 

characteristics such as growth rates (Szaro et al., 1978a and 1978b; Trivelpiece et al., 1984) or 

reproductive parameters such as reproductive success may occur, resulting in possible local population 

extinction. Indirect effects occur by fouling of the nesting habitat and displacement of individuals, 

breeding pairs, or populations to less favorable habitats (e.g., Velando et al., 2005b). Competition may 

exclude refugee seabirds from all habitats, especially for seabird colonies in southeastern Louisiana. 

A mathematical model by Peakall et al. (1989) showed that exposure to a slick at the surface (which 

would usually reduce in size or vanish in response to chemical dispersants) was the sensitive pathway to 

contamination in seabirds. Exposure to oil in the water column (a primary destination of chemically 

dispersed oil from surface slicks, along with the seafloor) was modeled to be minor. Sometimes, because 

of lack of thorough training of all personnel or the sheer scale of operations, the air, vehicle, and foot 

traffic that takes place during shoreline cleanup may disturb nesting populations and degrade or destroy 

habitat. 

New research, experience, and testing will help the efficacy of the rehabilitation of oiled birds and 

will probably improve scare methods that will keep birds away from an oil slick. Rehabilitation can be 

significant to the survival of threatened and endangered bird species. Chemically dispersed oil has 

sublethal biochemical and physiological toxicity to seabirds similar to that of oil alone (Peakall et al., 

1987). Toxic effects of untreated and chemically dispersed oil on the hatching success of waterfowl and 

seabirds were similar (NRC, 1989). 

Preening of oiled plumage may drive oil deep into plumage (Jenssen, 1994; Jenssen and Ekker, 

1991). Birds that must feed on or in the water lose heat faster than semiaquatic birds that can feed with a 

dry plumage on land (Jenssen, 1994). Some aquatic birds such as cormorants, when oiled, must either 

starve on land or enter the sea where hypothermia will kill them (Jenssen, 1994). 

Residual material that remains after evaporation and solubilization is water-in-oil emulsions 

(mousse), which are the primary pollutant onshore after offshore spills. The mixing of mousse and 

sediments form aggregates that have the odor of oil and, after photo- and biological oxidation, form 

asphaltic “tarballs” and pavements (Briggs et al, 1996). Mousse emulsions may be the most toxic 

petroleum component because they are the most hydrophobic and will penetrate the hydrophobic core of 

the plasma membrane of cells and will cause disruption of the membrane and enter the cells as well 

(Briggs et al., 1996). Common symptoms of exposed birds include dehydration, gastrointestinal 

problems, infections, arthritis, pneumonia, hemolytic anemias, cloacal impaction, and eye irritation. 

Therefore, antibiotic treatments, nutritional support, rehydration, and other protocols are used at 

rehabilitation centers (Briggs et al., 1996). Capture-recapture methods to calculate survival after 

rehabilitation may work better for waterfowl than for seabirds (Dunne and Miller, 2007). Capturerecapture data for the 30-year period 1974-2004 and for the 11-year period 1993-2004 demonstrated that 

oiling and subsequent rehabilitation do not have an effect on post-release survival in mallards (Dunne and 

Miller, 2007). In the same study, for Canada geese, data from an unfavorable, aberrant release site were 

excluded and oiling and rehabilitation had no effect on post-release survival (Dunne and Miller, 2097). 

Rehabilitation may even give a higher probability of survival to Canada geese than unoiled controls 

because rehabilitation provides consistent access to food, a brief protection from predators, and general 

health management practices (Dunne and Miller, 2007). Standard blood parameters of birds brought to 

rehabilitation centers were first measured in the mid-1970’s. About 12 parameters, including effects on 

both red and white blood cells, have been involved (Briggs et al., 1996). The metabolic rate, correlated 

with heat loss, was not substantially increased by chemically dispersed oil relative to the increase caused 

by oil alone (Lambert et al., 1982). Oiled birds spend more time preening off the water, exposing them to 

predation and reducing the time available for feeding, breeding, and other activities (Stephenson and 

Andrews, 1997). Some body cells respond to oil with excessive deposition of a yellow-brown pigment, 

hemosiderin, causing hemosiderosis (Briggs et al., 1996). Impacts of oil on the immune system include 

inflammation of the gastrointestinal tract following oil ingestion, which affects the intestinal mucosa 
4-232 Central Planning Area Supplemental EIS 

lining. The mucosa functions in immune defense and in suppression of immune response to certain 

antigens such as those in foods. 

Mallards exposed to cold temperature stress had increased mortality rates if they were fed with oil, 

which caused seriously increased stress from release of corticosteroid stress hormone caused by the oil 

(Briggs et al., 1996). 

The immune system has a large number of components, interactions, and functions that can provide 

potential targets for petrochemicals. The network nature of the system also provided a pathway by which 

an effect on one component can lead to a myriad of other interconnected problems (Briggs et al., 1996). 

These authors note, “A complete understanding of how the immune system works, including a finished 

roster of its components, is far from achieved.” 

A search was conducted for new information published since completion of the Multisale EIS. A 

search of Internet bibliographic databases, as well as personal interviews with authors of references used 

in the Multisale EIS, was conducted to determine the availability of recent information since publication 

of the Multisale EIS. The Internet databases examined included Google Advanced Book Search, Google 

Advanced Scholar Search, and Gale Databases. Authors were contacted and interviewed to investigate 

any recent published data that may be available. 

A literature search found Burger (1997), who reports that exposure to small amounts of oil may 

weaken birds or decrease their body weight so they may go for years without problems until they face a 

severe environmental stress. Then, they have a higher mortality than unexposed birds. Burger (1993) 

notes that spill volume has little or no correlation with bird mortality. Similarly, Camphuysen et al. 

(2005) found that, for six major spills in Western Europe, spill volume (ranging from 170 tonnes of heavy 

fuel for the Tricolor to 223,000 tonnes of crude for the Amoco Cadiz) was not correlated with estimated 

bird mortality (ranging from about 5,000 birds for the Braer to about 200,000-300,000 birds for the 

Stylis). In a comparison study with similar results (Kingston, 1995), the Braer spilled 85,000 tonnes but 

killed only about 4,000 birds, while the Exxon Valdez spilled only 35,000 tonnes but killed about 

100,000-300,000 birds. The state of the seas at the time of the Exxon Valdez accident was calm and the 

oil was heavy, high-viscosity crude, resulting in little capability for chemical or natural dispersal. In 

comparison, the Braer oil was light crude and seas were heavy, creating a large potential for dispersal. 

Because of its undispersed state, the Exxon Valdez oil principally affected surface-dwelling and shoredwelling organisms such as birds. The Braer oil did not even moderately affect shores, and because of 

the dispersed state of the oil, it affected only sea bed and pelagic water column biota and killed very few 

birds. However, Wilhelm et al. (2007) shows that the lack of correlation of bird mortality with spill 

volume no longer holds when spill volume is scaled as the perimeter of the oil slick by putting a fractional 

exponent on spill volume (see also Tan et al., 2010). An estimated 10,000 seabirds were killed in a 1,000-

bbl spill from the FPSO Terra Nova vessel off the Grand Banks of Newfoundland on November 21, 2002. 

No birds could be counted on the beach because winds blew out to sea, and no seabird data were available 

from before the spill. Even so, birds inside and outside the slick area were counted from a ship at sea 

while the slick was on the water. The density of seabirds in the affected area, timing (i.e., if peak periods 

in bird density overlap temporally with the spill), wind conditions, wave action, and distance to the shore 

may have more effect than spill volume (Castege et al., 2007; Byrd et al., 2009). Long-term impacts of 

the Sea Empress spill (72,000 tonnes of crude) in Wales were moderate; in a 10-year study (Moore, 

2006), the numbers of the majority of affected breeding seabird colonies (primarily alcids) recovered to 

pre-spill values within 2-3 years. Localized effects on the distribution of migratory wetland birds were 

not evident after 2 years. Khan and Ryan (1991) note substantial mortality in seabirds after attempts at 

rehabilitation (see also Anderson et al., 1996; Sharp, 1996). Sublethal symptoms of contamination were 

numerous and substantial prior to the mortality. Similarly, numerous symptoms were found in dead birds 

on the shore and in birds dying after rehabilitation; these birds were affected by the Prestige oil spill off 

the coast of Spain on November 19, 2002 (Camphuysen et al., 2002; Balseiro et al., 2005; Velando et al., 

2005a; Zuberogoitia et al., 2006; Perez et al., 2008; Zabala et al., 2010). Final major impacts to European 

shags (Phalacrocorax aristotelis) from the Prestige spill probably came in 2003 from a decimated food 

supply of fish (Velando et al., 2005b). As oil weathered, the exposure of seabirds to oil from the Exxon 

Valdez spill shifted from direct oiling to ingestion with food (Hartung, 1995). 

Alonso-Alvarez et al. (2007a and 2007b) used blood chemistry of yellow-legged gulls (Larus 

michahellis) to compare long-term sublethal toxicity of the Prestige oil spill with short-term experimental 

sublethal toxicity in captive birds fed small amounts of fuel oil. Long-term effects were measured about 
Description of the Environment and Impact Analysis 4-233 

19 months after the spill. Short-term effects were measured in captive birds fed a small amount of fuel oil 

for 7 days. Adults from oiled colonies and fuel-oil-fed experimental birds had higher total PAH’s and 

lower levels of three natural metabolites. Calcium was lower in oil-fed females than in control females, 

but it was the same in oil-fed and control males. Calcium is important for sufficient egg shell thickness in 

breeding females. 

Parsons (1994) provides the following unique before and after data for impacts of a spill on birds. 

Extensive shoreline and salt marsh were oiled by a January 1990 Exxon spill in the Arthur Kill and Kill 

van Kull estuaries of New York Harbor. Double-crested cormorants had reached their pre-spill 

population growth by 1991. Productivity of herring gulls remained unchanged by the spill. Most heron 

populations increased after the spill. Great black-backed gulls had a loss of abundance. Snowy egrets 

and glossy ibis used salt marsh and mud flat habitat, some of which was oiled. Black-crowned night 

heron and glossy ibis had delayed nesting after the spill and, along with snowy egret, showed lower 

reproductive success after the spill. Egg laying and hatching were generally more successful than chickrearing because of the shortage of food fed to the chicks. Waterfowl were not affected seriously, except 

for a short-term decline in mallards. 

The new information does not conflict with information in the Multisale EIS and the 2009-2012 

Supplemental EIS, and often it is similar to or supports the information in these two documents. 

Proposed Action Analysis 

The probabilities of oil spills occurring and contacting coastal bird habitat within 10 days as the result 

of the proposed action over its 40-year life are 7-11 percent for the threatened piping plover; 1 percent for 

the endangered whooping crane; 8-13 percent for the brown pelican; 8-13 percent for raptors; 

8-14 percent for gulls, terns, and charadriid allies; 8-14 percent for shoreline charadriids; 8-13 percent for 

diving birds; 8-14 percent for wading birds; and 9-14 percent for waterfowl. All of these groups, except 

for the whooping crane, are widely distributed across the Gulf (Figures 4-22 through 4-31 of the Multisale 

EIS); therefore, an oil spill would only affect a small portion of a bird group. The combined probabilities 

are always <15 percent. Small coastal spills, pipeline spills, and spills from accidents in navigable 

waterways can contact and affect the different groups of coastal and marine birds, most commonly marsh 

birds, waders, waterfowl, and certain shorebirds. In the CPA, an estimated total of 46-102 coastal spills 

would occur over a 40-year production period. Impacts on seabirds at sea are not part of the analysis and 

their seasonal distribution needs to be characterized. Many species breed outside the United States, 

sometimes outside the Northern Hemisphere. Impacts of the CPA proposed action on all coastal birds are 

expected to be negligible. Oil-spill cleanup is not expected to affect coastal birds if all personnel are 

completely trained. 

The DWH event and resulting oil spill in Mississippi Canyon Block 252 and the related spill-response 

activities may impact birds that come into contact with oil and remediation efforts. The best available 

information does not provide a complete understanding of the effects of the spilled oil and active 

response/cleanup activities on the affected coastal and marine bird environment. For the latest available 

information on oiled or affected birds documented in the area, event response, and daily maps of the 

current location of spilled oil, see RestoreTheGulf.gov (2010c). Figure 4-14 and Tables 4-5 and 4-6 

summarize birds collected by date; this information was obtained from FWS as part of the NRDA 

process. Table 4-4 compares past oil spills and relative impacts to birds. 

Summary and Conclusion 

Oil spills have the greatest impact on coastal and marine birds. Small amounts of oil can affect birds, 

and mortality from oil spills is often related to numerous symptoms of toxicity. Data from actual spills 

strongly suggest that impacts on their food supply are delayed after initial impacts from direct oiling. 

Mechanisms of toxic oil effects other than direct oiling of plumage have seldom been confirmed. Oilspill impacts on birds from the CPA proposed action are expected to be negligible because an oil spill 

would only affect a small portion of a bird group. Impacts of oil-spill cleanup from the proposed action 

are also expected to be negligible. 
4-234 Central Planning Area Supplemental EIS 

4.1.1.14.4. Cumulative Impacts 

A detailed impact analysis of the coastal and marine birds for the CPA proposed action can be found 

in Chapter 4.5.8 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new 

information since publication of the Multisale EIS is presented in Chapter 4.1.9.4 of the 2009-2012 

Supplemental EIS. The following is a summary of the information incorporated from the Multisale EIS 

and the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

Background/Introduction 

This cumulative analysis considers impact-producing factors that may adversely affect populations of 

nonendangered/nonthreatened and endangered/threatened birds related to OCS and non-OCS activities. 

Both listed and nonlisted birds are discussed together because the impacts are similar. 

The OCS activities include the following: 

 the proposed action; and 

 prior and future OCS sales. 

Non-OCS activities include the following: 

 State oil and gas activity; 

 crude oil imports by tankers; and 

 other commercial, military, and recreational offshore and coastal activities. 

The OCS-related, impact-producing factors include the following: 

 air emissions; 

 degradation of water quality; 

 platform and pipeline oil spills and any improperly directed spill-response activities; 

 structure presence and lights; 

 aircraft and vessel traffic and associated noise, including OCS helicopter and servicevessels; 

 habitat loss and modification resulting from coastal facility construction and 

development; 

 OCS pipeline landfalls; and 

 trash and debris. 

The non-OCS, impact-producing factors include the following: 

 air emissions; 

 pollution of coastal waters resulting from municipal, industrial, and agricultural 

runoff and discharge; 

 tanker oil spills and spills related to oil and gas activities in State coastal waters and 

any improperly directed spill-response activities; 

 aircraft and military activities including jet training overflights and sonic booms; 
Description of the Environment and Impact Analysis 4-235 

 nonconsumptive recreation including bird-watching activities; 

 maintenance and use of navigation waterways ; 

 collisions of coastal and marine birds with wind turbines, communication towers, 

lighted structures, tall buildings, windows, power lines, and fences; 

 disease; 

 storms and floods ; 

 coastal development; and 

 fisheries interactions (negative impacts of decreased food resources by fisheries catch 

and incidental seabird bycatch, and positive impacts of increased food resources from 

discarded bycatch). 

Proposed Action Analysis 

OCS-Related Impacts 

Air Emissions 

Air emissions include the amount of sulfur dioxide expected to be released due to the proposed 

action, as well as from prior and future OCS sales, and State oil and gas activity. These emissions may 

adversely affect coastal and marine birds. Pollutant emissions into the atmosphere from the activities 

under the cumulative analysis are projected to have minimum effects on offshore air quality because of 

the prevailing atmospheric conditions, emission heights, and pollutant concentrations. Onshore impact on 

air quality from emissions under the OCS cumulative analysis is estimated to be within both Class I and 

Class II PSD allowable increments as applied to the respective subareas. Emissions of pollutants into the 

atmosphere under the cumulative analysis are projected to have little effect on onshore air quality because 

of the atmospheric regime, the emission rates, and the distance of these emissions from the coastline. 

These judgments are based on average steady state conditions and the dispersion equation for 

concentration estimates; however, there would be days of low mixing heights and wind speeds that could 

further decrease air quality. These conditions are characterized by fog formation, which in the Gulf 

averages about 30-40 days a year, mostly during winter. Impacts from offshore sources are reduced in 

winter because the frequency of onshore winds decreases and the removal of pollutants by rain increases. 

The summer is more conducive to air quality effects as onshore winds occur more frequently. Increases 

in onshore annual average concentrations of NOx, SOx, and PM10 under the cumulative analysis are 

estimated to be less than Class I and Class II PSD allowable increments for the respective subareas per 

both the steady state and plume dispersion analyses, and they are below concentrations that could harm 

coastal and marine birds. Indirect impacts on coastal and marine birds due to air quality under the 

cumulative analysis will have a negligible effect on coastal and marine birds. 

Degradation of Water Quality 

Water quality of coastal environments would be affected by bilge water from service vessels and 

point- and nonpoint-source discharges from supporting infrastructure. Water quality in marine waters 

would be impacted by the discharges from drilling, production, and platform removal operation 

operations. Degradation of coastal and inshore water quality resulting from factors related to the 

proposed action plus those related to prior and future OCS sales; crude oil imports by tanker; and other 

commercial, military, and recreational offshore and coastal activities is expected to impact coastal and 

marine birds. 

Platform and Pipeline Oil Spills and Any Improperly Directed Spill-Response Activities 

Oil spills have the greatest potential to impact coastal and marine birds. Mandatory use of waterbird 

feeding areas at the sea surface and intertidal wetland zone, where spilled oil tends to accumulate, makes 

the birds extremely vulnerable to exposure to oil. Exposure to small amounts of oil may have a latent 
4-236 Central Planning Area Supplemental EIS 

impact on birds and a delayed impact on their food supply. Mortality from oil spills is often related to 

numerous symptoms of toxicity. Oil-spill impacts on birds from the CPA proposed action are expected to 

be negligible. For coastal spills >1,000 bbl, the estimated total number of spills is 1 per 6 years from the 

total of OCS sources; for offshore spills >1,000 bbl, the estimated total number of spills for OCS sources 

is <1 per year for facilities and 1 per year for pipelines (Chapter 3.2.1 of the 2009-2012 Supplemental 

EIS). 

Structure Lights and Presence 

Every spring, migratory land birds, including neotropical passerines, cross the Gulf of Mexico from 

wintering grounds in Latin America to breeding grounds north of the Gulf of Mexico. Migrants 

sometimes arrive at certain platforms shortly after night fall or later and proceed to circle those platforms 

(the phenomenon is called a nocturnal circulation event) for variable periods ranging from minutes to 

hours. Nocturnal circulation around platforms may create lethal effects from birds colliding with 

platforms. Acute sublethal stress from energy loss may increase the risks of collision, while stopovers on 

platforms could reduce energy loss. 

Aircraft and Vessel Traffic and Noise from Helicopters and Service Vessels 

Helicopter and service-vessel traffic related to OCS activities could sporadically disturb feeding, 

resting, or nesting behavior of birds or cause abandonment of preferred habitat. The Federal Aviation 

Administration (Advisory Circular 91-36C) and corporate helicopter policy states that helicopters must 

maintain a minimum altitude of 700 ft (213 m) while in transit offshore and 500 ft (152 m) while working 

between platforms. When flying over land, the specified minimum altitude is 1,000 ft (305 m) over 

unpopulated areas or across coastlines and 2,000 ft (610 m) over populated areas and biologically 

sensitive areas such as wildlife refuges and national parks. The net effect of OCS-related flights on 

coastal and marine birds is expected to result in sporadic disturbances, which may result in displacement 

of localized groups. During nesting periods, this could ultimately result in some reproductive failure from 

nest abandonment or predation on eggs and young when a parent is flushed from a nest. 

Service vessels would use selected nearshore and coastal (inland) navigation waterways and would 

adhere to protocol set forth by USCG for reduced vessel speeds within these inland areas. Routine 

presence and low speeds of service vessels within these waterways diminish the effects of disturbance 

from service vessels on nearshore and inland populations of coastal and marine birds. It is expected that 

service-vessel traffic would seldom disturb populations of coastal and marine birds existing within these 

areas. Recreational vessel traffic is a much greater source of impact to birds in coastal habitats. These 

vessels are, in most cases, required to comply with strict speed/wake restrictions (small recreational 

fishing boats, ski boats, etc.) but often flush coastal and marine birds from feeding, resting, and nesting 

areas. Such disturbances displace local groups from these preferred habitats and could lead to 

abandonment of the areas in general or reproductive failure. Disturbance may result in increased energy 

expenditures due to avoidance flights and decreased energy intake due to interference with feeding 

activity. It is estimated that the effects of non-OCS vessel traffic on birds within coastal areas are 

substantial. 

In laboratory experiments, factors determining an animal’s susceptibility to noise-induced damage, 

such as species, age, audibility range, and recovery process, can be controlled. Memphis State University 

(1971) mentions “the large, well-done body of literature exploring the effects of noise upon auditory 

structures and hearing.” Hearing loss or damage to the auditory system from noise has been reported in 

laboratory mammals (Memphis State University, 1971). 

Habitat Loss and Modification Resulting from Coastal Facility Construction and 

Development 

Under the cumulative activities scenario, factors contributing to coastal landloss or modification 

include construction of 0-1 gas processing plants, as well as other facilities. The contribution of 

development from urban and other industrial growth would be substantial, causing both the permanent 

loss of lands and increased levels of disturbance associated with new construction and facilities. 
Description of the Environment and Impact Analysis 4-237 

Pipeline Landfalls 

Under the cumulative activities scenario, factors contributing to coastal landloss or modification 

include construction of 32-47 OCS-related pipeline landfalls, resulting in 64-94 km (40-58 mi) of onshore 

pipeline. Adverse impacts of pipeline canals are the most significant OCS-related and proposed-actionrelated impacts to wetlands. Initial impacts are locally significant and largely limited to where OCSrelated canals pass through wetlands. Pipeline canal dredging will occur in wetland bird habitat, and 

without mitigation, wetland habitat could be destroyed. The regulatory apparatus for mitigation of 

pipeline canal dredging in wetlands is managed by the U.S. Army Corps of Engineers. Mitigation would 

probably result in no substantial impact on wetland bird populations. 

Trash and Debris 

Coastal and marine birds would likely experience chronic physiological stress from sublethal 

exposure to or intake of contaminants or discarded debris. This would cause disturbances and 

displacement of single birds or flocks. Chronic sublethal stress is often undetectable in birds. It can serve 

to weaken individuals (especially serious for migratory species), making them susceptible to infection and 

disease. Coastal and marine birds are commonly entangled and snared in discarded trash and debris. 

Many species would readily ingest small plastic debris, either intentionally or incidentally. Interaction 

with plastic materials may lead to permanent injuries and death. Much of the floating material discarded 

from vessels and structures offshore drifts ashore or remains within coastal waters. These materials 

include lost or discarded fishing gear such as gill nets and monofilament lines, which cause the greatest 

damage to birds. It is expected that coastal and marine birds would seldom become entangled in or ingest 

OCS-related trash and debris as a result of BOEMRE prohibitions on the disposal of equipment, 

containers, and other materials into offshore waters by lessees (30 CFR 250.40). In addition, MARPOL, 

Annex V, Public Law 100-220 (101 Statute 1458), which prohibits the disposal of any plastics at sea or in 

coastal waters, went into effect January 1, 1989. Despite these regulations, quantities of plastic materials 

are accidentally discarded and lost in the marine environment, and so a threat to individual birds remains 

within these areas. 

Non-OCS-Related Impacts 

Habitat Degradation 

Habitat alteration has the potential to disrupt social behavior, food supply, and the health of birds that 

occur in the Gulf of Mexico. Vital habitat needs to be protected so that the ecosystem continues for the 

birds and their prey. Such activities may stress the animals and cause them to avoid traditional feeding 

and breeding areas or migratory routes. Many of these species are declining in numbers and are being 

displaced from areas along the coast (and elsewhere) as a result of the destruction of or encroachment on 

their preferred habitat(s). As these birds move to undisturbed areas of similar habitat, their presence may 

create or augment habitat utilization pressure on these selected areas as a result of intra- and interspecific 

competition for space and food. 

Tanker Oil Spills and Spills Related to Oil and Gas Activities in Coastal State Waters and 

Any Improperly Directed Spill-Response Activities 

Most offshore non-OCS-related spills occur from vessel and barge operations. Table 4-13 of the 

Multisale EIS lists annual oil-spill occurrence in the Gulf of Mexico. Based on the 2009-2012 

Supplemental EIS’s OSRA model for coastal spills >1,000 bbl, the estimated total number of spills is 

3 per 6 years for the total of non-OCS sources; for offshore spills >1,000 bbl, the estimated total number 

of spills for non-OCS sources is <1 per year for tank ships and <1 per year for tank barges. In summary, 

mandatory use of waterbirds feeding areas at the sea surface and intertidal wetland zone, where spilled oil 

tends to accumulate, makes them extremely vulnerable to exposure to oil. Exposure to small amounts of 

oil may have a latent impact on birds and a delayed impact on their food supply. Mortality from oil spills 

is often related to numerous symptoms of toxicity. Oil spills in the cumulative case have the greatest 

potential impact on coastal and marine birds. Oil-spill impacts on birds from the total cumulative 
4-238 Central Planning Area Supplemental EIS 

scenario are expected to be moderate. The increment of oil spills from the CPA proposed action to the 

total cumulative impacts is expected to be negligible. 

Pollution of Coastal Waters Resulting from Municipal, Industrial, and Agricultural Runoff 

and Discharge 

Non-OCS-related activities and natural processes that can impact marine water quality include bilge 

water discharges from large ships and tankers, and coastal pollutants that are transported away from 

shore, including runoff, river input, sewerage discharges, industrial discharge, and natural seepage of oil 

and gas. There exists a wide variety of contaminant inputs into coastal waters bordering the Gulf of 

Mexico. Contaminants from non-OCS pollution of coastal waters resulting from municipal, industrial, 

and agricultural runoff and discharge may have acute or chronic, lethal or sublethal impacts. The 

dominant pollution source is the large volume of water from the Mississippi River, which drains over 

two-thirds of the contiguous United States. Major activities that have added to the contamination of Gulf 

coastal waters include the petrochemical industry, agriculture, forestry, urban expansion, extensive 

dredging operations, municipal sewerage treatment processes, marinas and recreational boating, maritime 

shipping, and hydromodification activities. Not as significant are large commercial waste disposal 

operations, livestock farming, manufacturing industry activities, power plant operations, and pulp and 

paper mills. Vessel traffic is likely to impact water quality through routine releases of bilge and ballast 

waters, chronic fuel and tank spills, trash, and domestic and sanitary discharges. 

Aircraft and Military Activities Including Jet Training Overflights and Sonic Booms 

Playback of aircraft overflight noise at 96 decibels (dB) inside incubators and at 131 dB outside a 

different kind of incubator did not substantially affect the hatchability of chicken eggs or the quality of 

hatched chicks. Playback of overflight noise of about 115 dB made hens stop sitting on eggs (Stadelman, 

1958). Responses to sonic booms in chickens, young turkeys, and pheasants were less intense than low 

subsonic overflights (Bell, 1972). No effects of subsonic aircraft on nesting herring gulls were noted 

(Burger, 1981). Subsonic aircraft overflights flushed significantly more herring gulls than flushed 

immediately before or after the disturbances (Burger, 1981). 

Nonconsumptive Recreation 

Impacts of nonconsumptive recreation depend on many factors including species and type of 

recreation. Even visitation by those most interested in conserving wildlife can have detrimental effects 

(Carney and Sydeman, 1999). Visitation of nesting areas can generate conservation interest and money, 

but disturbance can cause birds to abandon a site that managers need to preserve (Carney and Sydeman, 

1999). Most studies of the effects of visitors on waterbirds did not identify mechanisms of impact, 

determine relative effects of different kinds of disturbance, or control for confounding influences (Carney 

and Sydeman, 1999). 

Some ornithologists have presumed that birds that do not fly in response to disturbance are seldom 

substantially stressed, but this hypothesis has not been tested. A raised heart rate may have serious 

energetic costs to birds that do not fly when approached. In that case, birds still maintain increased 

vigilance, are highly stressed, and may be expending large amounts of energy because of elevated 

metabolic rate. Behavior is an obvious event, which is why it is so often measured, but it does not always 

signify fitness costs of disturbance or relative fitness costs for different species or populations (Beale, 

2007). A decision to avoid a type of behavior may be important. Birds may decide not to flee when 

fitness costs are greater than the fitness benefits of moving to alternative habitat (Gill et al., 2001). The 

decision should depend on the context that the bird-alternative habitat may be lacking or scarce, and 

frequent disturbances could cause frequent flights, creating severe fitness (energy) costs such as lost 

foraging time during flight and the energy cost of flight. Decisions to shift habitat should be constrained 

by the species’ perceptual range, i.e., the distance from which individuals can perceive landscape 

elements (Frid and Dill, 2002). Energy reserve depletion is likely to affect reproductive effort and 

possibly population viability. 

Sometimes flushing, alertness, and other antipredator responses to nonlethal stimuli should become 

stronger; the bird should become sensitized with repeated exposure to the stimuli (Frid and Dill, 2002). 
Description of the Environment and Impact Analysis 4-239 

In that case, bird populations would need to be protected by some type of conservation such as setback 

buffer distances posted on signs. Sensitization to disturbance in birds is a poorly studied phenomenon 

and should never be discounted without supporting data. For an example of possible sensitization, loom 

rate is the rate at which a predator or human disturbance proxy for a predator increases in size as it 

approaches; for predators or proxies moving at the same speed, loom rate is higher for nearby predators or 

proxies than for distant ones. As multiple exposures to the stimuli at different distances occur, the bird 

should increase its flight initiation distance to stimuli with higher loom rates. The bird will associate the 

high rate with closeness of the predator, becoming sensitized rather than habituated. The bird learns to 

recognize this high-loom-rate cue to danger of close predator approach (Frid and Dill, 2002). 

Energy cost in birds is highest for flight. Flight in response to disturbance will result in increased 

energy requirements and feeding time, and increased flight time will reduce the total time for other 

activities (Korschgen et al., 1985; Belanger and Bedard 1990; Ely et al., 1999; Ackerman et al., 2004). 

Fleeing from disturbance may affect feeding ecology and the effects of predation in complex ways; 

staying put may increase or decrease fitness. Outdoor recreation, especially nature appreciation and bird 

watching, is expanding into refuges and putting additional stresses on wild populations (Klein et al., 

1995; Schummer and Eddleman, 2003). 

Ecotourists (including bird watchers and wildlife photographers) and outdoor recreators are not likely 

to be aware of the negative impacts that their presence may have on wildlife (Carney and Sydeman, 

1999). Ecotourists can introduce high levels of disturbance to nesting waterbirds. Ecotourists often 

closely approach birds, return to the same sites repeatedly, and visit sites year-round. The beneficial 

adaptation of flushing to avoid predators may balance with costly and nonbeneficial flushing caused by 

humans. 

Predation risk and its proxy (response to human disturbance) can impact reproduction via decisions 

about parental investment (Frid and Dill, 2002). Once parents have considerably invested in their 

offspring, they may protect their investment by remaining on the nest for the rest of the breeding season 

after a severe disturbance, but they may abandon their nest site the following year (Steidl and Powell, 

2006). 

The ultimate impact on a bird flock of a sufficient disturbance by aircraft and recreationists would 

depend on the overall vigilance of birds within a flock, the size of an individual flock (because in 

response to a disturbance resembling a predator the entire flock would flush), and the rate at which each 

flock is flushed per unit time. 

Hypotheses for the value of flocking to birds focus especially on predator avoidance and foraging 

enhancement, but the relative contribution of different ecological factors to the adaptations(s) of flocks 

remain unclear (Beauchamp, 2004). Evolution of flocking may have occurred in birds preferring highdensity clumped prey such as fruits and seeds, whose high densities assuage competition for food by 

dense flocks (Beauchamp, 2002). Dispersed foods, such as many insects and vertebrates, have lower 

abundance within clumps and a more uniform distribution, which may be matched by uniformly 

distributed solitary foraging birds (Beauchamp, 2002). Conspecific attraction allows individuals to locate 

clumps for other birds, forming a foraging flock (Beauchamp, 2002). Conspecific attraction makes little 

sense for resources with low abundance within clumps. Human disturbance occurs because birds respond 

to humans as if they were predators. Individuals in flocks may have evolved under substantial predation 

risks and flocking may dilute predation risk. However, foragers at the edge of a flock are often first in 

line during predator attacks and do not benefit from the same dilution of risk as neighbors in the center of 

the group (Beauchamp and Ruxton, 2008). In birds constrained to maximize feeding time that trades off 

with lower vigilance time, increased numbers of eyes and ears and prey dilution correlated with increased 

flock size and may result in reduced vigilance time per bird (Beauchamp, 2008). In a meta-analysis, 

group size was important but explained generally less than 20 percent of the variation in vigilance time 

per bird (Beauchamp, 2008). 

Maintenance and Use of Navigation Waterways 

Adverse impacts of navigation canals have substantial impacts on wetlands. Initial impacts are 

locally substantial, but largely limited to where canals and channels pass through wetlands. Current 

channels would not change as a result of the proposed action. In addition, no new channels would be 
4-240 Central Planning Area Supplemental EIS 

required. Periodic maintenance dredging is expected in existing OCS-related navigation channels through 

barrier passes and associated bars. 

Collisions of Coastal and Marine Birds with Wind Turbines, Communication Towers, 

Lighted Structures, Windows, Power Lines, and Fences 

Wide-scale, long-term, standardized, and systematic assessments of bird collisions are few (Manville, 

2005; Drewitt and Langston, 2008). Data on the status of one-third of all North American bird 

populations is lacking (Manville, 2005). The most important structural factors related to collision 

probability may be size and lighting (Drewitt and Langston, 2008). No hypotheses for the apparent 

attraction of birds, especially nocturnally migrating songbirds, to lights have been conclusively supported 

(Drewitt and Langston, 2008). Birds that stopped at lighted structures during inclement weather migrated 

on when weather conditions improved. The location of structures along the flight path, especially for 

flocks of birds, influences collision mortality. Warning lights for aircraft on towers >200 ft (61 m) are 

mandatory in the United States (Drewitt and Langston, 2008). Birds that avoid collision with windows 

may become exhausted as the birds flutter against them, falling to the ground where they may be 

vulnerable to starvation or predation (Drewitt and Langston, 2008). Overall mortality caused by collision 

with tall buildings may be considerable (Drewitt and Langston, 2008). Window strikes may be the 

greatest cause of anthropogenic mortality in the United States, at least an order of magnitude greater than 

strikes with wind turbines, communication towers, tall buildings, and power lines (excluding distribution 

lines to residences and businesses) (Drewitt and Langston, 2008). Collisions with power lines and 

supporting towers can occur during inclement weather and during periods of migration, often causing 

death or permanent injury to birds (Avery et al., 1980; Avian Power Line Interaction Committee, 1994). 

By 2000, the estimated annual death toll from collision with communication towers was at least 

4-5 million birds (Drewitt and Langston, 2008). A current estimate is 40-50 million deaths (Manville, 

2005). Combining collision mortality estimates for communication towers, power lines, and window 

strikes, at least several hundred million birds are killed annually (Drewitt and Langston, 2008). The 

number of birds annually killed by collision with windows is 100 million to 1 billion birds, or 

0.5-5 percent of the estimated 20 billion birds in the United States (Drewitt and Langston, 2008). 

Population mortality greater than 0.5 percent may have a serious impact (Drewitt and Langston, 2008). 

Rapid proliferation of structures in developed countries and their future inevitability in developing 

countries may cause serious future population declines in birds (Drewitt and Langston, 2008). 

Disease 

In the United States, the most commonly diagnosed bacterial bird diseases were avian cholera, 

chlamydiosis, and salmonellosis. The most commonly diagnosed viral diseases were duck plague, 

paramyxovirus, and West Nile virus, together causing almost all deaths due to infectious diseases; fungal 

and parasitical infections were relatively minor (Newman et al., 2007). Even the collection of mosquito 

abundance and prevalence data for West Nile virus study is costly, and now health departments are 

struggling to maintain budgets for these procedures (Kilpatrick et al., 2007). Captive-reared whooping 

cranes have been vaccinated with a DNA vaccine for the RNA West Nile virus, which offers temporary 

relief but interferes with the natural selection for immune resistance (Kilpatrick et al., 2007). 

Chemical pollution, the most commonly reported cause of death in scientific publications and the 

most important OCS-related impact (from oil spills), is probably less significant than infectious diseases 

(Newman et al., 2007). The impact of influenza viruses on wild animal host survival, reproduction, and 

behavior are almost completely unknown (Vandegrift et al., 2010). The two most important groups of 

migratory birds that are natural reservoirs for influenza viruses are waterfowl and charadriiformes 

(including shorebirds and gulls) (Vandegrift et al., 2010). LaDeau et al. (2007) stated that “Emerging 

infectious diseases present a formidable challenge to the conservation of native species in the twenty-first 

century.” The number of diagnosed bird deaths was greater for viruses than for bacterial infections, and 

algal blooms had a relatively minor effect (Newman et al., 2007). 
Description of the Environment and Impact Analysis 4-241 

Storms and Floods 

Coastal storms and hurricanes can often cause deaths to coastal birds through collisions because of 

high winds; associated flooding destroys active nests. Nesting territories and colonial bird rookeries with 

optimum food and/or nest-building materials may also be lost. Elevated levels of municipal, industrial, 

and agricultural pollutants in coastal wetlands and waters expose resident birds to chronic physiological 

stress. 

Coastal Development 

The construction of buildings and other facilities is expected to continue to encroach on bird habitat 

in the northern Gulf of Mexico. Areal extent of the proportion of habitat lost may increase linearly with 

ecological consequences to birds. However, new research indicates that habitat loss may sometimes have 

a critical threshold above which it increases nonlinearly and with greater degree (higher slope) with 

increasing ecological consequences (Swift and Hannon, 2010). This conclusion is based on simulations 

and empirical studies. The presence of thresholds depends on the characteristics of species and 

landscapes. Most existing studies of thresholds have not used any formal statistical methods to identify 

their presence or value (Swift and Hannon, 2010). 

Fisheries Interactions (negative impacts of decreased food resources by fisheries catch and 

incidental seabird bycatch, and positive impacts of increased food resources from discarded 

bycatch) 

Commercial fisheries may accidentally entangle and drown or injure birds during fishing operations 

or by lost and discarded fishing gear. Seabird bycatch before regulation caused severe global declines in 

many seabird species. The longline fisheries in the Gulf of Mexico comprise pelagic tuna and swordfish, 

bottom shark, and bottom reef. The total incidental seabird bycatch for the bottom longline fisheries was 

one gull of unidentified species, two brown pelicans, one herring gull, and two unidentified seabirds from 

2005 to 2008; for the pelagic fishery, it was one brown pelican and two unidentified seabirds from 1992 

to 2005 (Hale and Carlson, 2007; Hale et al., 2007; Scott-Denton, personal communication, 2009; Hale et 

al., 2009; Beerkircher, personal communication, 2009). With recent volunteer monitoring or mandatory 

observation, cumulative impacts for future bird bycatch of longline fisheries on marine birds in the 

northern Gulf of Mexico are expected to be negligible. Competition for prey species may occur between 

birds and fisheries. Fisheries catch may reduce population densities of avian aquatic predators limited by 

food availability by taking substantial food away. Substantially increased food resources from discarded 

fishery bycatch may have the opposite (positive) impact. Both processes are of special concern because 

fisheries are a recent unnatural intrusion into the function of coastal communities and organisms may not 

have had time to adapt. 

Summary and Conclusion 

Activities considered under the cumulative activities scenario would detrimentally affect coastal and 

marine birds. It is expected that the majority of effects from the major impact-producing factors on 

coastal and marine birds are sublethal (behavioral effects and nonfatal exposure to or intake of OCSrelated contaminants or discarded debris) and would usually cause temporary disturbances and 

displacement of localized groups inshore because the activities themselves are temporary. The net effect 

of habitat loss from oil spills, new construction, and maintenance and use of pipeline corridors and 

navigation waterways would alter species composition and reduce the overall carrying capacity of 

disturbed area in general. 

The incremental contribution of the proposed action to the cumulative impact is negligible because 

the effects of the most probable impacts, such as sale-related operational discharges and helicopters and 

service-vessel noise and traffic, are estimated to be sublethal with some displacement of local individuals 

or groups. The cumulative effect on coastal and marine birds is expected to result in a discernible decline 

in the numbers of birds that form localized groups or populations, with associated change in species 

composition and distribution. Some of these changes are expected to be permanent and to stem from a 

net decrease in preferred habitat for all birds and critical habitat for endangered species. 
4-242 Central Planning Area Supplemental EIS 

Activities considered under the cumulative scenario would detrimentally affect coastal and marine 

birds. The net effect of habitat loss from oil spills, OCS pipeline landfalls, and maintenance and use of 

navigation waterways, as well as habitat loss and modification resulting from coastal facility construction 

and development, would alter species composition and reduce the overall carrying capacity of disturbed 

area(s) in general. These would be the most serious cumulative impacts on birds. However, the impacts 

from these activities with the CPA proposed action would be minimal. This is in part because an oil spill 

would affect a small portion of a bird group and because of the low number of pipeline landfalls and the 

regulations, technologies, and mitigation requirements that are in place for dredging and construction 

activities. It is expected that the majority of effects from the major impact-producing factors on coastal 

and marine birds are sublethal (i.e., behavioral effects from aircraft and vessel traffic and noise and birdwatching activities; and nonfatal exposure to or intake of trash, debris, and OCS-related contaminants 

from air emissions and degradation of water quality). Unregulated recreational activities may seriously 

stress birds because approach to birds by humans has uncertain consequences and because recreationists 

usually do not realize the sublethal consequences of intrusion. 

Nocturnal circulation events at platforms are expected to have minimal and mostly sublethal impacts 

on migrating bird populations. This conclusion results from the confirmed low mortality from starvation 

for all birds that landed on the platforms examined by Russell (2005) and from the suggested sublethal 

stress in birds that dropped out of circulation. Behavioral impacts usually cause temporary disturbances 

and displacement of inshore flocks. Collisions of coastal and marine birds with structures such as power 

line towers are usually lethal. Disease is often lethal but it may be a part of natural avian population 

control unless the pathogen is introduced by humans, such as for the West Nile virus. Storms and floods 

are natural disturbances to which exposed organisms are generally adapted, except for hurricane storm 

surge, which is exacerbated by coastal wetland loss in Louisiana. 

The effect of the CPA proposed action to the cumulative effect of programmatic activities on coastal 

and marine birds is expected to result in a small but discernible decline in the numbers of birds, with 

associated change in species composition and distribution. Some of these changes are expected to be 

permanent and to stem from either a net decrease in preferred food resources or displacement of food 

resources and/or a decrease in the availability of preferred or critical habitat. 

The DWH event and resulting oil spill in Mississippi Canyon Block 252 and the related spill-response 

activities may impact birds that come into contact with oil and remediation efforts. The best available 

information does not provide a complete understanding of the effects of the spilled oil and active 

response/cleanup activities on the affected coastal and marine bird environment. For the latest available 

information on oiled or affected birds documented in the area, event response, and daily maps of the 

current location of spilled oil, see RestoreTheGulf.gov (2010c). 

4.1.1.15. Gulf Sturgeon 

The description of the existing condition of the resource and its habitat that follows best describes 

both the known and currently unknown conditions as affected by both the series of intense hurricanes 

(Katrina, Rita, Gustav, and Ike) and the DWH event. Post-storm monitoring of some of the coastal 

sturgeon populations has been completed and the resulting status of those populations are included as part 

of the existing conditions noted below. While the actual affects of the DWH event are currently 

unknown, it is estimated as of October 12, 2010, that Louisiana had 88 mi (142 km), Mississippi had 9 mi 

(14 km), and Florida had 1 mi (2 km) of shoreline exposed to moderate to heavy oiling. An additional 

203 mi (327 km) of Louisiana, 81 mi (130 km) of Mississippi, 60 mi (97 km) of Alabama, and 114 mi 

(183 km) of Florida shoreline was exposed to light to trace oiling (USDOT, CG, 2010d). These estimates 

may represent a decrease from the amount of shoreline oiling noted on the FWS Deepwater Horizon

Response site in September 2010, indicating that a total of 494 mi (795 km) of shoreline received light to 

trace amount as compared with the October 2010 estimate of 458 mi (737 km). During the same 

September period, 98 mi (158 km), 9 mi (14 km), and 2 mi (3 km) of shoreline was exposed to moderate 

to heavily oiling in Louisiana, Mississippi, and Florida, respectively (USDOI, FWS, 2010a). Some of the 

shorelines oiled are within the areas of the Gulf sturgeon critical habitat. The degree of shoreline oiling 

has decreased but the affect on these habitats is not known at this time due to the ongoing NRDA 

assessment process. A more accurate assessment of the existing conditions of this resource and its habitat 

will be forthcoming as monitoring information is gathered and results are made publicly available. 
Description of the Environment and Impact Analysis 4-243 

4.1.1.15.1. Description of the Affected Environment 

A detailed description of Gulf sturgeon can be found in Chapter 3.2.7 of the Multisale EIS and in 

Chapter 4.1.10 of the 2009-2012 Supplemental EIS. The following information is a summary of the 

resource description incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and new 

information that has become available since both documents were prepared. 

The Gulf sturgeon (Acipenser oxyrinchus desotoi), a subspecies of the Atlantic sturgeon (Acipenser 

oxyrinchus oxyrhynchus), has a subcylindrical body embedded with bony plates (scutes), a greatly 

extended snout, ventral mouth with four anterior chin barbels, and a heterocercal tail (Valdykov, 1955; 

Valdykov and Greeley, 1963). Adults range from 1.8 to 2.4 m (5.9 to 7.9 ft) in length, with females 

attaining a greater length and mass than males. 

The NOAA Fisheries Service and FWS listed the Gulf sturgeon as a threatened species on 

September 30, 1991. Subsequently, a recovery plan was developed to ensure the preservation and 

protection of Gulf sturgeon spawning habitat (USDOI, FWS and Gulf States Marine Fisheries 

Commission, 1995). Critical habitat was proposed on June 6, 2002, in the Federal Register (67 FR 39105 

39199) and was designated on April 18, 2003. Critical habitat is defined as specific geographic areas that 

are essential for the conservation of a threatened or endangered species and that may require special 

management consideration or protection. The following geographic areas in the GOM rivers and 

tributaries were included in the critical habitat designation: 

 Pearl and Bogue Chitto Rivers in Louisiana and Mississippi; 

 Pascagoula, Leaf, Bowie (also referred to as Bouie), Big Black Creek, and 

Chickasawhay Rivers in Mississippi; 

 Escambia, Conecuh, and Sepulga Rivers in Alabama and Florida; 

 Yellow, Blackwater, and Shoal Rivers in Alabama and Florida; 

 Choctawhatchee and Pea Rivers in Florida and Alabama; 

 Apalachicola and Brothers Rivers in Florida; and 

 Suwannee and Withlacoochee Rivers in Florida. 

The critical habitat also includes portions of the following estuarine and marine areas: 

 Lake Pontchartrain (east of the Lake Pontchartrain Causeway), Lake St. Catherine, 

Little Lake, The Rigolets, Lake Borgne, Pascagoula Bay, and Mississippi Sound 

systems in Louisiana and Mississippi, and sections of the adjacent State waters within 

the GOM; 

 Pensacola Bay system in Florida; 

 Santa Rosa Sound in Florida; 

 nearshore GOM in Florida; 

 Choctawhatchee Bay system in Florida; 

 Apalachicola Bay system in Florida; and 

 Suwannee Sound and adjacent State waters within the GOM in Florida. 

The primary constituent elements of these designated areas that are considered essential for the 

conservation of the Gulf sturgeon include abundant food items; riverine spawning sites with appropriate 

substrates; riverine aggregation sites; a flow regime necessary for normal behavior, growth, and survival 

of all riverine life stages; water quality with the characteristics needed for normal behavior, growth, and 

viability of all life stages; sediment quality needed for normal behavior, growth, and viability of all life 

stages; and safe and unobstructed migratory pathways necessary for passage within and between riverine, 
4-244 Central Planning Area Supplemental EIS 

estuarine, and marine habitats. The critical habitat for Gulf sturgeon encompasses approximately 1,730 

river miles (2,783 river km) and 2,333 mi2

 (6,042 km2) of estuarine and marine habitat. Major shipping 

channels have been excluded in the critical habitat units. 

The Gulf sturgeon is anadromous, with immature and mature fish participating in freshwater 

migrations. Gill netting and biotelemetry have shown that subadults and adults spend 8-9 months each 

year in rivers and 3-4 of the coolest months in estuaries or Gulf waters. The adult fish tend to congregate 

in deeper waters of rivers with moderate currents and sand and rocky bottoms. Seagrass beds with mud 

and sand substrates appear to be important marine habitats (Mason and Clugston, 1993). Individuals are 

long-lived, some reaching at least 42 years in age (Huff, 1975). Age of sexual maturity for females 

ranges from 8 to 17 years and for males it ranges from 7 to 21 years (Huff, 1975). 

Gulf sturgeon eggs are demersal (sink to the bottom) and adhesive (Vladykov and Greeley, 1963). 

Spawning occurs in freshwater over relatively hard and sediment-free substrates such as limestone 

outcrops and cut limestone banks, exposed limestone bedrock or other exposed rock, large gravel or 

cobble beds, soapstone, or hard clay (Fox and Hightower, 1998; Marchent and Shutters, 1996; Sulak and 

Clugston, 1999). Although fry and juveniles feed in the riverine environment, subadults and adults do not 

(Mason and Clugston, 1993; Sulak and Clugston, 1999). Sturgeon feed on bottom-dwelling organisms 

such as amphipods, isopods, crustaceans, and marine worms. 

Subadult and adult Gulf sturgeon spend cool months (October/November through March/April) in 

estuarine areas, bays, or in the GOM (Odenkirk, 1989; Clugston et al., 1995). Adult Gulf sturgeon likely 

overwinter in the GOM. Habitats used by Gulf sturgeon in the vicinity of the Mississippi Sound barrier 

islands tend to have a sand substrate and an average depth of 1.9-5.9 m (6.2-19.4 ft). Where estuary and 

bay unvegetated “mud” habitats have a preponderance of natural silts and clays supporting Gulf sturgeon 

prey, the Gulf sturgeon found there are assumed to be using these habitats only for foraging. 

Sulak and Clugston (1999) describe two hypotheses regarding where adult Gulf sturgeon may 

overwinter in the GOM to find abundant prey. The first hypothesis is that Gulf sturgeon spread along the 

coast in nearshore waters in depths less than 10 m (33 ft). The alternative hypothesis is that they migrate 

far offshore to the broad sedimentary plateau in water depths of 40-100 m (131-328 ft) west of the Florida 

Middle Grounds. Available data support the first hypothesis. Evaluation of tagging data has identified 

several nearshore GOM feeding migrations but no offshore GOM feeding migrations. Telemetry data 

documented Gulf sturgeon from the Pearl River and Pascagoula River subpopulations migrating from 

their natal bay systems to Mississippi Sound and moving along the barrier islands on both the island 

passes (Ross et al., 2001). Gulf sturgeon from the Choctawhatchee, Yellow, and Apalachicola Rivers 

have been documented migrating in the nearshore GOM waters between Pensacola and Apalachicola Bay 

units (Fox et al., 2000). Telemetry data from the GOM mainly show sturgeon in depths of 6 m (19.8 ft) 

or less (Ross et al., 2001; Fox et al., 2000). 

Gulf sturgeon occur in most major tributaries of the northeastern GOM from the Mississippi River 

east to Florida’s Suwannee River, and in the central and eastern Gulf waters as far south as Charlotte 

Harbor (Wooley and Crateau, 1985). In Florida, Gulf sturgeons are still found in the Escambia, Yellow, 

Blackwater, Choctawhatchee, Apalachicola, Ochlockonee, and Suwannee Rivers (Reynolds, 1993). 

While little is known about the abundance of Gulf sturgeon throughout most of its range, population 

estimates have been calculated for the Apalachicola, Choctawhatchee, and Suwannee Rivers. The FWS 

calculated an average (from 1984 to 1993) of 115 individuals (greater than 45 cm [18 in] total length) 

over-summering in the Apalachicola River below Jim Woodruff Lock and Dam (USDOI, FWS and Gulf 

States Marine Fisheries Commission, 1995). Preliminary estimates of the size of the Gulf sturgeon 

subpopulation in the Choctawhatchee River system are 2,000-3,000 fish over 61 cm (24 in) total length. 

The Gulf sturgeon subpopulation in the Suwannee River are 7,650 individuals over 60 cm (24 in) total 

length and older than age 2 (Sulak and Clugston, 1999). Although the size of the Suwannee River 

sturgeon population is considered stable, the population structure is highly dynamic as indicated by length 

frequency histograms (Sulak and Clugston, 1999). Strong and weak year-classes, coupled with the 

regular removal of larger fish, limit the growth of the Suwannee River population but stabilize the 

average population size (Sulak and Clugston, 1999). 

Based on the latest population estimates from the Pearl River (Rogillio, personal communication, 

2007; Kirk personal communication, 2007), the annual populations of sturgeon varied annually and 

ranged from 222 fish to 536 fish. The information noted the annual population estimates for the Pearl 

River population fluctuated as follows and was not stable as suggested in the earlier account referenced. 
Description of the Environment and Impact Analysis 4-245 

Year Population Size 

(number of fish) 

1992-1996 292 

2000 222 

2001 536 

2002 246 

2003 200 

2004 277 

2005 No estimate calculated 

As noted, there is a great variance in population numbers. The researchers acknowledged that a better 

method of determining the health of the population is the mortality index. The acceptable range for 

annual mortality required to sustain the population in the Pearl River System was estimated in the range 

of 16-24 percent mortality. The estimate of annual mortality post-Hurricane Katrina is 38 percent, which 

is within the range indicative of insufficient recruitment to maintain the current Pearl River population 

(Kirk, personal communication, 2007). In 2005, there was no population estimate since the number of 

fish caught was insufficient to make an accurate estimate. The historic range of the Gulf sturgeon 

included nine major rivers and several smaller rivers from the Mississippi River, Louisiana, to the 

Suwannee River, Florida, and the marine waters of the central and eastern GOM to Tampa Bay (Wooley 

and Crateau, 1985; USDOI, FWS and Gulf States Marine Fisheries Commission, 1995). Its present range 

extends from Lake Pontchartrain and the Pearl River system in Louisiana and Mississippi east to the 

Suwannee River in Florida. Sporadic occurrences have been recorded as far west as the Rio Grande River 

between Texas and Mexico, and as far east and south as Florida Bay (Wooley and Crateau, 1985; 

Reynolds, 1993). 

Five genetically-based stocks have been identified by NOAA Fisheries Service and FWS: (1) Lake 

Pontchartrain and Pearl River; (2) Pascagoula River; (3) Escambia and Yellow Rivers; (4) 

Choctawhatchee River; and (5) Apalachicola, Ochlockonee, and Suwannee Rivers. Mitochondrial DNA 

analyses of individuals from subpopulations indicate that adults return to natal river areas for feeding and 

spawning (Stabile et al., 1996). While some displacement of Gulf sturgeon was noted after Hurricane 

Katrina, mortality was minimal for populations from the Pearl River drainage and Louisiana along the 

western range of the critical habitat (Kirk, 2008). It was also noted that, despite the location of juvenile 

populations of sturgeon in the lower Pearl River, there was no summertime use of either the Mississippi 

River Gulf Outlet or the adjacent disposal sites (Kirk, 2008). 

Until recently, only two spawning sites were known, both in the Suwannee River in Florida. Eggs 

have now been discovered in six locations within the Choctawhatchee River system in Florida and 

Alabama (Fox and Hightower, 1998). In the Choctawhatchee Bay system, sturgeon were found in 

nearshore water depths of 2-4 m (7-13 ft). Areas of the bay where the Gulf sturgeon remained for long 

periods were characterized by sandy substrates with benthic communities dominated by crustaceans and 

annelids. Most of the male sturgeon remained in the Choctawhatchee Bay during the winter and spring, 

while most females were either in the Gulf of Mexico or last detected at the Bay entrance (Fox et al., 

2002a). The Gulf sturgeon move from the 2- to 4-m (7- to 13-ft) water depth of the bays to the deeper 

waters around barrier islands but eventually relocate to shallow waters again. Both in the deeper and 

shallow waters they demonstrate localized movements within the area for extended lengths of time 

(>2 weeks) but then rapidly move to another area where localized patterns of movement are once again 

observed (Fox et al., 2002a). Based on these studies, it is believed that the deepwater areas are used 

primarily to return to the shallow foraging areas. In spring, large subadults and adults that migrate from 

the estuaries or the Gulf into major river passes feed primarily on lancelets, brachiopods, amphipods, 

polychaetes, and globular molluscs. Small sturgeons that remain in river passes during spring feed on 

amphipods, shrimp, isopods, oligochaetes, and aquatic insect larvae (Clugston, 1991). During the riverine 

stage, adults cease feeding, undergo gonadal maturation, and migrate upstream to spawn. Spawning 

occurs in freshwater reaches of the river, over coarse substrate in deep areas or holes with hard bottoms 
4-246 Central Planning Area Supplemental EIS 

and where some current is present (Sulak and Clugston, 1998; Fox et al., 2000). Females lay large 

numbers of eggs. A large female was reported to have the capability of producing 275,000-475,000 eggs 

(Chapman at al., 1993). These eggs are adhesive and attach to rocks, vegetation, or other objects. They 

hatch in about 1 week depending upon the temperature of the water. 

Fisheries scientists interrupt migrating Gulf sturgeon in the rivers and estuaries by capture with nets 

suspended from floats in the rivers and river mouths to determine if these fish are showing signs of natal 

river fidelity. Gill nets with mesh wide enough not to close the very large opercula are used. No capture 

or tracking is feasible in the open Gulf when the fish migrate because cold fronts come every 2 to 3 days, 

with seas up to 9 ft (3 m). These conditions are dangerous for the size of vessel required, and the paths 

traveled in the open Gulf cannot be followed beyond the estuaries. Thus, the offshore winter distribution 

of Gulf sturgeon relative to the location of the activities under the proposed action is unknown. However, 

there have been no reported catches of this species in Federal waters (Sulak, personal communication, 

1997). 

Sturgeons are bottom suction feeders that have ventrally located, highly extrusible mouths. The 

sturgeon head is dorsoventrally compressed with eyes dorsal so benthic food under the sturgeon’s mouth 

is not be visible. They have taste barbels, like catfish, to detect benthic prey. The barbels are also useful 

for feeding in high-order streams if visibility is low or at night. Fishes that forage by taste are 

opportunistic feeders because smell is much more discriminating than taste. Another adaptation of 

sturgeon to mainstem rivers and offshore waters is mobility (an adaptation to the large habitat scale). 

Studies (Parauka, personal communication, 2008) indicate Gulf sturgeon overwinter in the bays 

(Choctawhatchee, Escambia, and Santa Rosa) before migrating into the coastal rivers the following spring 

and summer. It was also noted that sturgeon leaving the Choctawhatchee Bay during the winter may 

utilize the surrounding bays and the Gulf of Mexico. Some adult sturgeon have migrated >100 km (62 

mi) into the marine environment. While it has been hypothesized that some adults may remain in the 

open Gulf for as much as 2 years, the location of the Gulf foraging grounds is still unknown (Fox et al., 

2002b). In this study, the primary food source was found to be the ghost shrimp. High fecundity (egg 

number) facilitates wide dispersal, a major adaptation to the high variance of habitat quality resulting 

from diverse habitats and the dynamic nature of mainstems of watersheds. 

The decline of the Gulf sturgeon is believed to be due to overfishing and habitat destruction, primarily 

the damming of coastal rivers and the degradation of water quality (Barkuloo, 1988). In the late 19th 

century and early 20th century, the Gulf sturgeon supported an important commercial fishery providing 

eggs for caviar, flesh for smoked fish, and swim bladders for isinglass (a gelatin used in food products 

and glues) (Carr, 1983). Dams and sill construction mostly after 1950 restricted access to historic 

spawning areas (Wooley and Crateau, 1985) exacerbating habitat loss, and overfishing resulted in the 

decline of the Gulf sturgeon throughout most of the 20th century. In several rivers throughout its range, 

dams have severely restricted sturgeon access to historic migration routes and spawning areas. Dredging 

and other navigation maintenance that includes lowering river elevations, eliminating deep holes, and 

altering rock substrates may have adversely affected Gulf sturgeon habitats (Wooley and Crateau, 1985). 

Contaminants, both agricultural and industrial, may also be a factor in their decline. Organochlorines 

have been documented to cause reproductive failure in the Gulf sturgeon, reduced survival of young, or 

physiological alterations in other fish (White et al., 1983). In addition, Gulf sturgeon appear to be natal 

spawners with little, if any, spawning from other riverine populations. 

Today, the greatest habitat threat to sturgeon is the damming of coastal rivers because sturgeon 

cannot pass through the lock and dam systems to reach spawning areas. In addition to damming, 

reservoir control and fluctuation of release rates during drought conditions are all factors affecting the 

spawning rivers downstream of major urban water supply reservoirs. Dredging, desnagging, and spoil 

deposition associated with channel maintenance and improvement also present a threat to sturgeon 

spawning habitat. Poor water quality because of pesticide runoff, heavy metals, and industrial 

contamination may be affecting sturgeon populations. Habitat loss continues to pose major threats to the 

recovery of the species. 

Natural phenomena such as tropical storms and hurricanes occur along the Gulf Coast with varying 

frequency and intensity between years. Although these are usually localized and sporadic, the 2004-2005 

storm seasons brought major and repeated damage to the Gulf Coast area. The effects from Hurricane 

Katrina (2005) are still being assessed. It was noted that Hurricanes Gustav and Ike did initially displace 

some of the Gulf sturgeon in the Louisiana/Mississippi area, much like what happened in Florida during 
Description of the Environment and Impact Analysis 4-247 

Hurricane Katrina. Current surveys along the Mississippi coast indicate no permanent impact to critical 

habitat and acknowledge that the sturgeon has returned to their normal feeding and resting areas along the 

coastal rivers. Sampling is not complete to conclude if the population had any change in composition or 

if spawning occurred this year (Slack, personal communication, 2008). While a complete assessment of 

habitat damage due to hurricanes has not been fully executed for Gulf sturgeon based on the recent 

sampling results, the effects are believed to be temporary (Parauka, personal communication, 2007a). 

The impacted area included a large portion of the designated critical habitat and known locations of 

Gulf sturgeon. The sturgeons are upstream in freshwater riverine habitats during the tropical weather 

season. This may give the estuarine and marine areas time to recover from hurricane impacts before the 

sturgeon move downstream. For instance, massive runoff due to flooding rains and swollen tributaries 

could cause a sharp increase in toxic contaminants in estuarine habitats. However, spreading and dilution 

should mitigate any threat to sturgeon very quickly. By the time the downstream migration occurs, 

conditions should have returned to near normal. The flooding and subsequent “unwatering” of New 

Orleans in the fall of 2005 created concern for any sturgeon that might have been in the areas of Lake 

Pontchartrain where those contaminated flood waters were pumped. The COE noted in their 

environmental assessment that temporary impacts to Gulf sturgeon may have resulted as a part of the 

unwatering activities related to the pumping of floodwaters into Lake Pontchartrain. Impacts due to the 

quantity and quality of the floodwaters may have caused some sturgeon to seek forage and resting areas in 

other more undisturbed locations of the lake. It was expected that any sturgeon displaced returned to the 

area once the unwatering activities ceased (U.S. Dept. of the Army, COE, 2005a). The COE also noted 

that the emergency procedures permitted in the Panama City, Florida, aftermath of Hurricane Ivan may 

have created temporary impacts to species including the Gulf sturgeon, but that the emergency procedures 

did not adversely impact the species (U.S. Dept. of the Army, COE, 2005b). After Hurricane Katrina, 

there were reports of fish kills and at least one confirmed report of a dead Gulf sturgeon due to low 

oxygen in the water from organic input from leaf litter and other sources such as raw sewage and 

untreated effluent (Cummins, 2005). Many municipalities or sources of discharges lost power and/or 

were flooded and were likely a source of contaminant discharge. 

Aside from the recent hurricane activity, the DWH event released an estimated 4.9 million barrels of 

oil into the Gulf of Mexico continuously over a 3-month period. Comparison of oil-spill overlay maps 

with the Gulf sturgeon critical habitat maps indicate that all but the most eastern regions of the sturgeon 

habitat has been exposed to oil (USDOC, NOAA, 2010f). The “oil exposed” habitat is found from the 

Chandeleur Islands in Louisiana to the mouth of the Pearl River and adjoining estuaries in both Louisiana 

and Mississippi, along the Gulf Islands National Seashores through Mobile Bay along the Alabama and 

Florida coasts to central Florida. While the exposure to spilled oil was not continuous in all locations, all 

areas were either moderate to lightly oiled, either onshore or on the surface based on maps prepared by 

SCAT observers and posted on NOAA’s ERMA website (USDOC, NOAA, 2010f). It is most probable 

that the oil reaching these areas from the spill site was either weathered, treated (with dispersant), or both. 

The toxicity cannot be verified at this time due to ongoing NRDA assessments in these areas. While 

these sturgeon habitats and foraging areas must be considered as oil-affected (USDOC, NOAA, 2010f), 

for the purpose of the existing environmental conditions for this resource, no assessment of effects can be 

made at this time due to lack of publicly available data. At this time, we do not know the condition of the 

oil reaching the affected areas nor do we know the extent of oil that may be on the bottom in these 

potential foraging areas. As the NRDA assessment process proceeds, the oil on the surface as well as on 

the bottom will be mapped and the data will be forthcoming. 

4.1.1.15.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of the Gulf sturgeon for the CPA proposed action can be found in Chapter 

4.2.2.1.9.1 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new 

information since publication of the Multisale EIS is presented in Chapter 4.1.10.1.2 of the 2009-2012 

Supplemental EIS. The following information is a summary of the resource description incorporated 

from the Multisale EIS, the 2009-2012 Supplemental EIS, and new information that has become available 

since both documents were prepared. 
4-248 Central Planning Area Supplemental EIS 

Potential impacts to the threatened Gulf sturgeon and their designated critical habitat from routine 

activities associated with the CPA proposed action may occur from drilling and produced-water 

discharges, degradation of estuarine and marine water quality from runoff, vessel traffic, explosive 

removal of structures, and pipeline installation. Designated Gulf sturgeon critical habitat occurs in 

estuarine and riverine locations along the Gulf Coast east of the Mississippi River in Louisiana to Florida. 

Critical habitat is defined as special geographic areas that are essential for the conservation of a 

threatened or endangered species and that may require special management and protection. Designated 

Gulf sturgeon critical habitat is confined to State waters, and navigation channels are exempt from the 

critical habitat status. Most activities related to the proposed action would occur in Federal waters (i.e., 

structure placement, drilling, removal, etc); however, critical habitat may be impacted directly or 

indirectly. 

Proposed Action Analysis 

Drilling mud and produced-water discharges contain chemical components that may be detrimental or 

toxic to Gulf sturgeon. Toxicity from drilling muds would require concentrations four or five orders of 

magnitude higher than concentrations found a few meters from the discharge point. Produced-water 

discharges may result in moderate heavy-metal and hydrocarbon contamination of sediments and extend 

through the water column out to several hundred meters down current from the discharge point (CSA, 

1997a). However, offshore discharges of drilling muds and produced waters are expected to dilute to 

background levels within 1,000 m (3,281 ft). These structures would be located well offshore of the 

designated critical habitat. Sturgeon are not known to be attracted to petroleum structures or activity, 

which is where the discharges would be the most concentrated. 

Minor degradation of estuarine water quality is expected in the immediate vicinity of shore bases and 

other OCS-related facilities as a result of routine effluent discharges and runoff. Rapid dilution is 

expected to negate any impact to critical habitat or Gulf sturgeon from these sources. 

Service-vessel traffic running in and out of shore bases may create the potential for impact to Gulf 

sturgeon. Ongoing movement studies currently being conducted off the northwest Florida coast noted 

Gulf sturgeon are found at mid-depth in the water column as opposed to bottom depths where they have 

previously been found (Nunley 2010; Robydek and Nunley, 2010). This finding, coupled with the 

movement between rivers and bays, provides more opportunity for vessel strikes. However, this behavior 

is currently only documented in Florida waters, which are far removed from the heavily traveled support 

bases west of the Mississippi River. There is potential for oiled sediments to be resuspended by vessel 

traffic in the areas where heavy oil was observed near support channels. Major shipping channels, as 

identified on standard navigation charts and marked by buoys, are excluded from critical habitat 

designation. Because Gulf sturgeon are bottom-feeders and are not known to be attracted to areas of 

activity or disturbance, the probability of a take due to vessel strike is extremely low in the areas located 

west of the critical habitat. Dredging of navigation channels and other areas is an impact to Gulf sturgeon 

critical habitat. However, only a small amount of the routine dredging done in coastal areas would be 

directly or indirectly due to the proposed action. 

Platform removal using explosives has the potential to injure or kill a Gulf sturgeon in the near 

vicinity of a blast. However, current data indicate that Gulf sturgeons generally remain in the estuarine 

regions near river mouths or in shallow Gulf waters. Critical habitat is in State waters, well inshore of the 

location of any oil or gas structure installed as a result of the proposed action. In the very unlikely event 

that a Gulf sturgeon was far enough offshore to be in the area of an impending structure removal, the 

associated disturbance and activity is expected to deter the fish from approaching the removal site. 

Pipeline installation may have the greatest potential for impact to Gulf sturgeon and their critical 

habitat from the CPA proposed action. Typical methods to lay pipeline can result in bottom and sediment 

disturbance, burial of submerged vegetation, reduced water clarity, reduced light penetration, and the 

resulting reduction of seagrass cover and productivity. With these methods, it is assumed that about 5 m2 

(55 ft2) of sediments per kilometer of pipeline would be resuspended during the installation of 50-850 km 

(31-528 mi) of pipelines in water depths less than 60 m (200 ft). Such activity would impact the 

nearshore critical habitat of Gulf sturgeon. 

All of the gas production and most of the oil production from the CPA proposed action is expected to 

be mingled in pipelines with other OCS production at sea before going ashore, and most would use 
Description of the Environment and Impact Analysis 4-249 

pipelines already in place. Zero to one pipeline landfall is projected as a result of the CPA proposed 

action. Should one be constructed, it would most likely be in Louisiana, where the large majority of the 

infrastructure exists for receiving oil and gas from the CPA. This area is on the extreme western end of 

the designated critical habitat for Gulf sturgeon. 

Trenchless, or directional, drilling is a recent technique for pipeline installation that is used in 

sensitive habitats. Impacts from this technique are limited to the access and staging sites for the 

equipment, and Gulf sturgeon are expected to avoid lay-barge equipment as well as resuspended 

sediments. This method has been used successfully to place pipelines under scenic rivers so as not to 

disturb the bottom water or impact the banks of the river. Since 2002, only one new pipeline (Endymion 

oil pipeline) has come to shore in Louisiana from OCS-related activities. Based on a review of the data in 

the COE permit application, the emplacement of the pipeline caused zero (0) impacts to marshes and 

beaches because of the use of horizontal, directional (trenchless) drilling techniques to avoid damages to 

these sensitive habitats. Pipeline permit requirements of COE and State agencies are expected to require 

the reduction of turbidity impacts to within tolerable limits for submerged aquatic vegetation. These 

requirements, along with directional drilling capability, would result in impacts to Gulf sturgeon critical 

habitat that are short term and negligible, if they occur at all. 

Summary and Conclusion 

Potential routine impacts on Gulf sturgeon and their designated critical habitat may occur from 

drilling and produced-water discharges, bottom degradation of estuarine and marine water quality by 

nonpoint runoff from estuarine OCS-related facilities, vessel traffic, explosive removal of structures, and 

pipeline installation. Because of the permitted discharge limits mandated and enforced in the Federal and 

State regulatory process, the dilution and low toxicity of this pollution is expected to result in negligible 

impact of the CPA proposed action on Gulf sturgeon. Vessel traffic would generally only pose a risk to 

Gulf sturgeon when leaving and returning to port. Major navigation channels are excluded from critical 

habitat. Also, the Gulf sturgeon’s characteristics of bottom-feeding and general avoidance of disturbance 

make the probability of vessel strike extremely remote. Explosive removal of structures as a result of the 

proposed action would occur well offshore of Gulf sturgeon’s critical habitat and the riverine, estuarine, 

and shallow Gulf habitats where sturgeon are generally located. If any pipeline is installed nearshore as a 

result of the proposed action, regulatory permit requirements governing pipeline placement and dredging, 

as well as recent noninvasive techniques for locating pipelines, would result in very minimal impact to the 

Gulf sturgeon’s critical habitat. Due to regulations, mitigations, and the distance of routine activities from 

known Gulf sturgeon habitats, impacts from routine activities of the CPA proposed action would be 

expected to have negligible effects on Gulf sturgeon and their designated critical habitat. 

4.1.1.15.3. Impacts of Accidental Events 

A detailed impact analysis of the Gulf sturgeon for the CPA proposed action can be found in Chapter 

4.4.9.1 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information 

since publication of the Multisale EIS is presented in Chapter 4.1.10.1.3 of the 2009-2012 Supplemental 

EIS. The following information is a summary of the resource description incorporated from the Multisale 

EIS, the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

Potential accidental impacts on Gulf sturgeon and the designated critical habitat may occur from oil 

spills, drilling and produced-water discharges, degradation of estuarine and marine water quality by 

nonpoint runoff from estuarine OCS-related facilities, vessel traffic, explosive removal of structures, and 

pipeline installation. 

Historically, Gulf sturgeon occurred from the Mississippi River east to Tampa Bay. Sporadic 

occurrences were recorded as far west as the Rio Grande River in Texas and Mexico, and as far east and 

south as Florida Bay (Wooley, 1985). The present range extends from Lake Pontchartrain and the Pearl 

River system in Louisiana and Mississippi, respectively, east to the Suwannee River in Florida. The 

species is anadramous—feeding in the winter months in the marine waters of the Gulf of Mexico 

including bays and estuaries, migrating in the spring up freshwater rivers to spawn on hard substrates, and 

then spending summers in the lower rivers before emigrating back out into estuarine/marine waters in the 

fall. Within the species’ present range, the critical habitat in the Gulf extends from Lake Borgne in 
4-250 Central Planning Area Supplemental EIS 

Louisiana to the Suwannee Sound in Florida. Although this is not the full range of occurrence of Gulf 

sturgeon, these areas constitute the most crucial habitat for the conservation of the Gulf sturgeon. 

The critical rivers and their associated estuaries include the Pearl, Pascagoula, Escambia, Yellow, 

Choctawhatchee, Apalachicola, and the Suwannee Rivers. Reproducing populations continue to be 

evident in these seven river systems. Sturgeon reproduction is not known to currently occur in the Mobile 

Basin where it most likely occurred historically; however, slow recolonization may be occurring as 

evidenced by the recent catch of Gulf sturgeon near Fairhope, Alabama (Mettee et al., 2009). The 

estimated Gulf sturgeon population on the Suwannee River has increased from less than 500 in the 1980’s 

to 2,000 fish in 2005 (Pine and Martell, 2009). The number of Gulf sturgeon in the Escambia River may 

have recently declined due to intense hurricane activity. Parauka (personal communication, 2007a) noted 

changes in distribution of sturgeon following Hurricane Katrina. There was a shift in sturgeon activity 

from the foraging areas in the Santa Rosa Sound and nearshore waters of Panama City, Florida, toward 

Mississippi Sound and Mobile Bay. However, several years after Hurricanes Katrina, Ike, and Gustav, 

these populations seem to have moved back to the Santa Rosa Sound area, but there has not been 

sufficient sampling to determine if the populations along this portion of the Gulf Coast have returned to 

pre-Katrina levels. 

Recent studies found Gulf sturgeon movements may be influenced by the search for and availability 

of food, preferable hydrological conditions and spawning substrates. Brooks and Sulak (2005) noted 

while identifying food sources in the Suwannee Estuary that the benthic infauna biomass was greater in 

the summer than the winter and that the distribution of benthic food sources was patchy. During an 

assessment of the benthic food source in the Choctawhatchee Bay (Heard et al., 2002), a change in 

species composition was noted possibly as a result of nutrient overloading during Hurricane Ivan. This 

may explain the back and forth movement of sturgeon from this area to other areas where more benthic 

forage is available. Edwards et al. (2003 and 2007) noted patterns on tagged fish in the Suwannee 

Estuary that indicated the sturgeon in this area were searching for food where the supply was patchy; thus, 

erratic movements were observed. They also noted some consistent and directed movement patterns, 

indicating that these fish may remember where the most abundant food sources are located and return to 

these locations each year. These back and forth patterns of movement up and down the estuary as well as 

between rivers may explain both the lack of river fidelity and the sharing of marine and estuarine forage 

areas when food sources are not abundant. 

Other important information about habitat use and distribution in Louisiana waters was shown in 

studies by Rogillio et al. (2007) and Ross et al. (2009). These studies documented the use of barrierisland passes in Mississippi Sound and the Chandeleur Islands for winter feeding. The FWS discovered 

nearshore areas of concentrated feeding activity for adults from multiple riverine systems in the waters 

near Tyndall Air Force Base/Panama City Beach, Florida, and Perdido, Florida, to Gulf Shores, Alabama 

(USDOI, FWS, 2002, 2003, 2004d, 2005b, and 2006b). Based on recent, buoy-based telemetry studies 

(Robydek and Nunley, 2008) in the offshore waters in northwest Florida, Gulf sturgeon were found to be 

more abundant in mid-water depths than noted in past studies where they were primarily noted as bottom 

dwellers, except when traveling between feeding sites. The occurrence in mid-water depths could 

increase the potential for vessel strikes during certain times of the year. 

New spawning sites were verified by egg collection on the Apalachicola River, Florida (USDOI, 

FWS, 2006c; Pine et al., 2006; Scollan and Parauka, 2008), and the Yellow River, Florida (Kreiser et al., 

2008). Juvenile movements in the Apalachicola River and Apalachicola Bay, Florida, were traced by 

Randall (2008). In June 2009, COE collected three young-of-the-year Gulf sturgeon in the Brothers 

River, a tributary to the Apalachicola River (Kirk, personal communication, 2010). Adult Gulf sturgeon 

were observed in a previously unreported tributary, the Withlacoochee River, Florida (Suwannee River 

tributary), in the fall of 2005 and in May 2006. Trophic habitat in the estuary of the Suwannee River, 

Florida, was described by Sulak et al. (2009). Juveniles (estimated age 8-9 months) were collected in the 

Santa Fe River, Florida, in December 2006 (Flowers and Pine, 2008); this observation is significant 

because the Santa Fe River is not known to support spawning and it is not known if the juveniles were 

spawned there or searching for habitat. Additional information was gained on feeding habits and 

movements in the estuary of the Suwannee River, Florida (Harris, 2003; Harris et al., 2005). Parkyn et al. 

(2007) described overall seasonal movements in the Suwannee River, Florida, drainage. 
Description of the Environment and Impact Analysis 4-251 

Proposed Action Analysis 

Potential accidental impacts on Gulf sturgeon and the designated critical habitat may occur from oil 

spills, drilling and produced-water discharges, degradation of estuarine and marine water quality by 

nonpoint runoff from estuarine OCS-related facilities, vessel traffic, explosive removal of structures, and 

pipeline installation. The dilution and low toxicity of this pollution is expected to result in a negligible 

impact on Gulf sturgeon as a result of the CPA proposed action. Vessel traffic would generally only pose 

a risk to Gulf sturgeon when leaving and returning to port. Major navigation channels are excluded from 

critical habitat. The Gulf sturgeon’s characteristics of bottom-feeding and general avoidance of 

disturbance make the probability of vessel strike extremely remote. However, recent studies have found 

that Gulf sturgeon spend more time than previously thought at mid-depth as opposed to being strictly 

utilizing the bottom, especially during movement from one area to another (Robydek and Nunley, 2008). 

Explosive removal of structures as a result of the proposed lease sale would occur well offshore of Gulf 

sturgeon critical habitat and the riverine, estuarine, and shallow Gulf habitats where sturgeon are 

generally located. Environmental permit requirements and recent techniques for locating pipelines would 

result in a very minimal impact to Gulf sturgeon critical habitat if any pipeline is installed nearshore. 

Oil spills are the OCS-related factor associated with the CPA proposed action most likely to impact 

the Gulf sturgeon. The brief background information provided above is to provide insight into the factors 

in the sturgeons’ life history and behavioral patterns that increase its susceptibility to accidental impacts 

associated with OCS activities. The coastal movements of Gulf sturgeon between estuaries, feeding in 

barrier island passes and utilizing both shallow and mid-water depths, increases the probability of 

encountering accidental spills. Other factors that may affect the sturgeon’s probability of accidental 

impact is the Gulf sturgeon’s long lifespan and extended residence in riverine and estuarine habitats, 

along with its benthic feeding habitats, which all enhance the chances of the species long-term and 

repeated exposure to environmental contamination and potential bioaccumulation of heavy metals and 

other toxicants including components of spilled oil. 

The PAH studies specifically involving Gulf sturgeon were not found in the current literature, 

although Gulf sturgeon tissue samples were found to contain concentrations of PAH’s (Batemann and 

Brim, 1994). The PAH toxicity to fish in general varies substantially, although impacts of PAH’s on fish 

are often generalized due to the difficulty in testing any specific chemical. In areas of PAH 

contamination, fish may produce the means to allow for faster removal rates of PAH’s from their system; 

however, this often transforms the PAH into a more harmful metabolite (O’Conner and Huggett, 1988). 

Fish exposed to PAH-contaminated sediments have experienced a range of affects including mortality, 

liver lesions, reproductive problems, fin erosion, skin carcinomas, and gill issues (Malins et al., 1985; 

O’Conner and Huggett, 1988; Fabacher et al., 1991; Varanasi et al., 1992; Baumann et al., 1996). There 

is also speculation that exposure to PAH’s may suppress the immune system. Recent research has 

documented the occurrence of endocrine disruption in sturgeons from various chemical contaminants, and 

PAH contamination has resulted in endocrine and reproductive disruption in some salmonids 

(Matthiesson and Sumpter, 1998). Oil can affect Gulf sturgeon by direct ingestion, ingestion of oiled 

prey, or the absorption of dissolved petroleum products through the gills. Upon any exposure to spilled 

oil, liver enzymes of adult fish oxidize soluble hydrocarbons into compounds that are easily excreted in 

the urine (Spies et al., 1982). Contact with or ingestion/absorption of spilled oil by adult Gulf sturgeon 

could result in mortality or sublethal physiological impacts including irritation of gill epithelium and 

disturbance of liver function. Behavior studies of other fish species suggest that adult sturgeon are likely 

to actively avoid an oil spill, thereby limiting the effects and lessening the extent of damage (Baker et al., 

1991; Malins et al., 1982). Fish eggs and larvae, with their limited physiology and mobility, are killed 

when contacted by oil (Longwell, 1977). 

Accidental impacts associated with the CPA proposed action that could adversely affect Gulf 

sturgeon include oil spills associated with the transport and storage of oil. The degree of impact from oil 

spills depends on the location of the spill, oil slick characteristics, water depth, currents, time of year, and 

weather. Offshore oil spills that occur in the proposed action area are much less likely to contact the Gulf 

sturgeon or its critical habitat than are inshore spills because of the proximity of the spill to the critical 

habitat and known range of the sturgeon. Designated Gulf sturgeon critical habitat occurs in estuarine 

and riverine locations along the Gulf Coast east of the Mississippi River in Louisiana, Mississippi, 

Alabama, and Florida in the CPA. Designated Gulf sturgeon critical habitat is confined to State waters. 
4-252 Central Planning Area Supplemental EIS 

Most activities related to the proposed action would occur in Federal waters; however, critical habitat may 

be impacted directly or indirectly. Gulf sturgeon are primarily benthic feeders and inhabit mostly 

nearshore, coastal water environments of moderate depth, except during the riverine spawning period. 

Based on current studies (Parauka, personal communication, 2007b), the sturgeon seems to have 

preference for the nearshore waters and have not been tracked any farther seaward than the seaward side 

of the barrier islands. Currently, telemetry data are being collected through the NRDA and NOAA 

Fisheries in more seaward locations in response to the DWH event. There are no publicly available or 

published data concerning these more seaward locations at this time due to the NRDA assessment 

process. Spawning takes place when eggs are deposited in inland waters, and young Gulf sturgeon is 

believed to remain upstream for perhaps their first 2 years. The probability of spilled oil encroachment 

into an inland waterway is less than for the adjoining coastal area and diminishes even further as one 

moves upstream. Spilled oil is very unlikely to impact adult and juvenile Gulf sturgeon and eggs when 

they are in the inland, riverine portion of their life cycle. The juvenile and subadult Gulf sturgeon, at a 

minimum, seasonally use the nearshore coastal waters and could potentially be at risk from both coastal 

and offshore spills. 

Because of the floating nature of oil and the small tidal range in the coastal Gulf, oil spills alone 

would typically have very little impact on benthic feeders such as the Gulf sturgeon. Unusually low tidal 

events, increased wave energy, or the use of oil dispersants increases the risk of impact with bottomfeeding and/bottom-dwelling fauna. For this reason, dispersants are not expected to be used with coastal 

spills. Winds and currents would also diminish the volume of a slick. For the Louisiana waters and 

beaches with a higher probability of oil-spill occurrence than the surrounding areas, the Mississippi River 

outflow would also serve to help break up a slick that might otherwise contact the area. Spreading of the 

slick would reduce the oil concentrations that might impact the coastal Gulf sturgeon critical habitat. 

The potential risk to sturgeon would result from either direct contact with oil spills (or the potential 

PAH’s introduced through the spill) or, in some cases, long-term exposure to produced water. The 

likelihood of Gulf sturgeon impacts in coastal waters as a result of OCS activity is reduced by both the 

distance from a potential spill or production area and the concentration of contaminants that actually 

reach the area of sturgeon activity. However, PAH studies involving Gulf sturgeon do not exist, although 

Gulf sturgeon tissue samples were found to contain PAH’s (Batemann and Brim, 1994). Except for direct 

pipeline spills in the nearshore environment, the Gulf sturgeon would be at greater risk of a PAH 

encounter during the inland river migrations due to the industrial and farm waste introduced into these 

coastal rivers from the adjacent agricultural and urban land uses. 

The produced waters associated with OCS activities have various chemical constituents that have 

varying potential for concern to the Gulf sturgeon. The components consist of metals, trace elements, 

monocyclic aromatic hydrocarbons, PAH’s, and various organic chemicals. Berg (2006), in his literature 

review of contaminants that affect Gulf sturgeon, found that while pH and water hardness may have an 

affect on the availability and uptake of heavy and trace metals, some sturgeon species were seen to adsorb 

these compounds into their ovarian tissue and sperm at levels that reduced reproductive success. In 

general, many metals have similar impacts on fishes. The majority of metals accumulate externally in the 

mucous of the gill tissues, although metals also disrupt numerous physiological functions in fish (Berg, 

2006). Since the Gulf sturgeon spends most of its time either in nearshore coastal environments or in 

inland rivers, the potential for encountering produced-water impacts or direct spills from a production 

platform is small. Produced water creates a localized area of effect close to the discharge and is mostly 

limited to benthic sediments in the immediate vicinity of the discharge. In the OCS activities, produced 

waters provide the main source of metals (i.e., arsenic, barium, cadmium, chromium, copper, lead, and 

zinc). While there have been no studies on the direct effects of these metals, specifically on Gulf 

sturgeon, there have been studies noting specific impacts of pollution and contamination (containing some 

or all of these metals and other waterborne contaminants) on various other sturgeon species. These 

studies identified the potential effects of these contaminants on sturgeon, which include muscle atrophy, 

abnormality of gonad, sperm and egg development, morphogenesis of organs, tumors, and disruption of 

hormone production (Graham, 1981; Altuf’yev et al., 1992; Dovel et al., 1992; Georgi, 1993; Romanov 

and Sheveleva, 1993; Heath, 1995; Khodorevskaya et al., 1997; Kruse and Scarnecchia, 2002). Mercury 

is only found occasionally in produced waters. All of these metals are natural constituents of clean 

seawater. Barium, chromium, copper, iron, nickel, and zinc are frequently found in produced water in 

higher concentrations than those naturally found in seawater. The complex geochemistry of these metals 
Description of the Environment and Impact Analysis 4-253 

affects their ability to produce adverse effects in the marine environment. Most of these metals are used 

as trace nutrients by marine organisms and, therefore, metal concentrations in the tissue make it difficult 

to determine bioaccumulation in these organisms. As a rule, concentrations of metals in tissues of marine 

organisms in the GOM and in the immediate vicinity of offshore discharges of produced water are in the 

normal range and do not show any evidence of bioaccumulation to potentially toxic levels for the 

organisms themselves or their consumers, including man (Neff, 2002). This study noted that produced 

water from the typical GOM produced water found only copper and cadmium, two metals typically in 

GOM produced water. Any adverse effects of these metals, if they occur at all, are likely to be highly 

localized. 

The monocyclic aromatic hydrocarbons are found in produced water; however, because of their high 

volatility, they are lost rapidly in the seawater following discharge. Most of these volatile compounds are 

immediately diluted to background levels within 100 m (328 ft) of the discharge. The compounds have a 

low potential to be bioaccumulated by marine organisms and do not adsorb to sediments. Therefore, they 

pose a very low risk of harm to marine organisms and human consumers of seafood. 

The PAH’s have a low to moderate risk to marine organisms or human consumers of fishery products. 

Some PAH’s bioaccumulate and are often found in sediments near produced-water discharges. Although 

some of the PAH’s do have a tendency to bioaccumulate, those particular constituents are in such low 

concentrations in the produced water that they are considered to be low risk to marine ecosystems in the 

vicinity of the produced-water discharges. The major source of the more damaging PAH compounds are 

found as a component of soot from various combustion sources. The PAH associated with soot are not 

accumulated efficiently from the food sources and are biodegraded rapidly in the tissues of most marine 

animals; therefore, they do not biomagnify in the marine food web and do not pose a hazard to fish that 

consume biofouling organisms from submerged platform structures. 

While not specifically addressing Gulf sturgeon, it has been observed that on other surrogate species 

such as brook trout, Caspian Sea sturgeon, and white sturgeon that sublethal concentrations of 

contaminants containing metals and hydrocarbon components may result in impaired physiological 

function and behavior in these fish species. The range of issues may include endocrine disruption, 

impacting reproduction and osmoregulation; immune system suppression; inhibition of the olfactory 

system; inhibition of the nervous system, interfering with behavior; and biochemical changes and 

developmental interference. All of these on their own may increase mortality and impair the recovery of 

a population or species (Berg, 2006). 

Vessel traffic would generally only pose a risk to Gulf sturgeon when leaving and returning to port. 

Major navigation channels are excluded from critical habitat. The Gulf sturgeon’s characteristics of 

bottom-feeding and general avoidance of disturbance make the probability of vessel strike extremely 

remote. 

The coastal waters inhabited by Gulf sturgeon and comprising their critical habitat are not expected to 

be at risk from coastal spills resulting from the proposed action. However, based on the SCAT reports 

and maps produced by the FWS’s Deepwater Horizon Response Team (USDOI, FWS, 2010a), critical 

habitat from Lake Borgne to the Florida/Alabama State line has at least been exposed to oil from the 

DWH event. It is not possible at this time to determine the type, condition, or volume of oil that 

contacted these areas due to the void of public data. It can be assumed that since the oil was treated with 

dispersant that it may sink, and depending on the condition (toxicity) of the oil, it may potentially affect 

the benthic forage in the areas where it blankets the bottom. There is a possibility that forage patterns and 

migration patterns of sturgeon may change along the coast if former foraging areas have been affected by 

the oil from the DWH event. Telemetry data concerning sturgeon movement are currently being collected 

from nearshore and offshore buoy systems by both NRDA and NOAA Fisheries. When this data 

becomes available, along with the NRDA data providing the location type and condition of the oil, an 

analysis will be able to be made on the effect of the DWH event on Gulf sturgeon and their habitat. 

Several factors influence the probability of spilled oil contact with Gulf sturgeon or their critical 

habitat. The anadromous migrations and the spawning and lengthy habitations of inshore, riverine areas 

greatly diminish the probability of spilled oil contact with Gulf sturgeon. The floating nature of oil and 

the lack of large tidal ranges, as well as the influence of the Mississippi River outflow to help disperse 

slicks, diminishes the probability of significant impact of spilled oil on Gulf sturgeon or their critical 

habitat. The very low probability of a large offshore oil spill contacting the Gulf sturgeon’s critical

habitat in all but the very westernmost area diminishes the potential impact to Gulf sturgeon or alteration 
4-254 Central Planning Area Supplemental EIS 

of critical habitat. The extremely low probability of a coastal spill impacting east of the Mississippi 

River, and thus the designated critical habitat, diminishes the probability of oil impacts to critical habitat. 

Summary and Conclusion 

The Gulf sturgeon could be impacted by oil spills resulting from the CPA proposed action. If there is 

contact with spilled oil, it could have detrimental physiological effects. The juvenile and subadult Gulf 

sturgeon, at a minimum, seasonally use the nearshore coastal waters and could potentially be at risk from 

both coastal and offshore spills. Due to the distance of the activity from shore and Gulf sturgeon critical 

habitat, there is a minimal risk of any oil coming in contact with Gulf sturgeon. The probability of a spill 

of a size and duration to persist long enough in the environment to impact the sturgeon or the sturgeon’s 

estuarine habitats is small (≤10%; Figure 3-10 of the 2009-2012 Supplemental EIS) unless it is 

catastrophic in nature such as the DWH event. In the rare event contact with oil occurs, this could cause 

nonlethal effects, including causing the fish to temporarily migrate from the affected area, irritation of gill 

epithelium, an increase of liver function in a few adults, and possibly interference with reproductive 

activity. 

The extent and scope of the spill resulting from the DWH event represents new information not 

assessed in the existing ESA Section 7 consultation in the GOM under the 5-Year Program. As a result of 

this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing GOM Multisale 

EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE on 

September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. The existing 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

4.1.1.15.4. Cumulative Impacts 

A detailed impact analysis of the Gulf sturgeon for the CPA proposed action can be found in Chapter 

4.5.9.1 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new information 

since publication of the Multisale EIS is presented in Chapter 4.1.10.1.4 of the 2009-2012 Supplemental 

EIS. The following information is a summary of the resource description incorporated from the Multisale 

EIS, the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

Proposed Action Analysis 

This cumulative analysis summary considers activities that could occur and adversely affect Gulf 

sturgeon within its range and critical habitat in the northern Gulf of Mexico, east of the Mississippi River 

during the 40-year analysis period. These activities include effects of the OCS Program (the proposed 

action, and prior and future OCS lease sales), State oil and gas activity, coastal development, 

man-induced modifications to water quantity, water and air quality, crude oil imports by tanker, 

commercial and recreational fishing, coastal restoration and protection, and navigation and flood control 

projects, as well as natural phenomena. Specific types of impact-producing factors considered in this 

cumulative analysis include coastal and marine environmental degradation by nonpoint runoff from 

estuarine OCS-related facilities, produced-water discharges, pipeline emplacements, oil spills, dredgeand-fill operations and natural catastrophes that alter or destroy habitat, commercial fishing techniques 

that result in sturgeon bycatch, and man-induced salinity modifications. 

Vessel traffic would generally only pose a risk to Gulf sturgeon when leaving and returning to port. 

Major navigation channels are excluded from critical habitat. The Gulf sturgeon’s characteristics of 

bottom-feeding and general avoidance of disturbance make the probability of vessel strike extremely 

remote. The explosive removal of structures as a result of the CPA proposed action would occur far 

offshore of Gulf sturgeon critical habitat and the riverine, estuarine, and shallow Gulf habitats where 

sturgeon are generally located. Environmental permit requirements and recent techniques for locating 
Description of the Environment and Impact Analysis 4-255 

pipelines would result in very minimal impact to the Gulf sturgeon’s critical habitat if any pipeline is 

installed nearshore as a result of a CPA proposed action. 

Oil Spills 

The Gulf sturgeon could be impacted by oil spills resulting from the CPA proposed action. The 

highest probability for cumulative impacts to the Gulf sturgeon or its habitat would be from coastal spills 

or vessel collisions in close proximity to its nearshore feeding and nursery areas. Due to the current 

distances of the CPA proposed action to the Gulf sturgeon’s critical habitat, migratory routes, or nursery 

and feeding areas, there is a very low probability of impact from spills from this area unless it is 

catastrophic in nature, such as the DWH event (Appendix B). 

Direct contact with spilled oil could have detrimental physiological effects. The juvenile and 

subadult Gulf sturgeon, at a minimum, seasonally use the nearshore coastal waters and could potentially 

be at risk from both coastal and offshore spills. However, several factors influence the probability of 

spilled oil contact with Gulf sturgeon or their critical habitat. The likelihood of spill occurrence and 

subsequent contact with, or impact to, Gulf sturgeon and/or their designated critical habitat is extremely 

low. Based on the 2009-2012 Supplemental EIS’s OSRA model, there is <0.5 percent probability of oil 

spills (1,000 bbl) occurring and contacting Gulf sturgeon critical habitat as a result of an accidental spill 

occurring. Chapter 4.3.1.2 of the Multisale EIS describes the projections of future spill events in more 

detail. 

For spills 1,000 bbl in the 2009-2012 Supplemental EIS, concentrations of oil below the slick are 

within the ranges that cause sublethal effects on marine organisms. However, when exposure time 

beneath accidental spills, hydrocarbon composition, and the change in this composition during weathering 

are considered, exposure doses are assumed to be far less than doses reported to cause even sublethal 

effects (McAuliffe, 1987). Given the low probability that Gulf sturgeon would be present in the specific 

area where and when a spill occurs, small likelihood of contact of a surface oil slick with a demersal fish 

and its benthic habitat, and minimal concentrations of toxic oil relative to levels that would be toxic to 

adult or subadult Gulf sturgeon, the impacts of spilled oil on this endangered subspecies are expected to 

be very low. With the DWH event, the oil was treated with dispersant, making the oil less toxic but 

causing the oil to sink and reach the benthic habitat. Normally, dispersants would be used in moderate 

amounts and only offshore so the benthic forage areas, as they are presently known and utilized by the 

sturgeon, would not be affected since the treated oil would sink in deepwater areas away from Gulf 

sturgeon nearshore habitat. 

Regardless of spill size, the effects of direct contact from spilled oil on Gulf sturgeon occur through 

the ingestion of oil or oiled prey and the uptake of dissolved petroleum through the gills by adults and 

juveniles. Contact with or ingestion/absorption of spilled oil by adult Gulf sturgeon can result in 

mortality or sublethal physiological impacts, especially irritation of gill epithelium and disturbance of 

liver function. It is expected that the extent and severity of effects from oil spills would be lessened by 

active avoidance of oil spills by adult sturgeon. Sturgeons are demersal and would forage for benthic 

prey well below an oil slick on the surface. Adult sturgeon only venture out of the rivers into the marine 

waters of the Gulf for roughly 3 months during the coolest weather. This reduces the likelihood of 

sturgeon coming into contact with oil. It is expected that contact would cause sublethal irritation of gill 

epithelium and an increase in liver function for less than a month. 

Based on currently available public information, it is reasonable to expect that oil production in the 

Gulf would continue to increase, although possibly at a slower rate due to economics of deepwater 

production and investment in other energy sources. In light of the DWH event and the impending cost of 

physical production modifications, regulations and safety requirements that may be needed to obtain a 

deepwater lease may reduce or temporarily delay the number of deepwater leases in production. This 

may have the effect of increasing shallow-water production, which could potentially result in adding a 

larger cumulative number of facilities closer to nearshore sturgeon habitat. If this happens, the potential 

for larger accidental spills closer to Gulf sturgeon critical habitat is possible. Currently, the toxicity, 

quantity, and the above and subsurface area of the oil spilled during the DWH event is unknown until the 

NRDA assessment is completed and made available. However, based on the available SCAT maps 

(USDOI, FWS, 2010a), the entire sturgeon critical habitat from Louisiana to eastern Florida was exposed 

to some portion of the spilled oil. What is not known is the condition of the oil and how much, if any, 
4-256 Central Planning Area Supplemental EIS 

effect it has had on the benthic forage base of the Gulf sturgeon. Since the oil was treated with 

dispersants, it should at least have a reduced toxicity; however, the treatment would also cause the oil to 

sink and therefore coat the ocean floor. Due to the season of the spill, the more vulnerable young 

sturgeon and larvae were still in the upper reaches of the rivers and not the estuary; therefore, they should 

be less affected. 

Dredging, Channelization, and Dredged Material Disposal 

Dredge-and-fill activities occur throughout the nearshore areas of the United States. These activities 

range in scope from propeller dredging (scarring) by recreational boats to large-scale navigation dredging 

and fill for land reclamation and coastal restoration projects. There will be a continual need for sand 

mining in coastal waters as a result of hurricane protection and coastal restoration projects. Other 

non-OCS operations, such as dredge-and-fill activities, indirectly impact Gulf sturgeon through the loss or 

disturbance of inland spawning and nearshore nursery habitat. Maintenance dredging and disposal to 

maintain navigation channels will continue to occur within Gulf sturgeon critical habitat (navigation 

channels are exempt from critical habitat) and may remove or modify foraging habitat as well as injure or 

kill some life history stages of the sturgeon. Hydraulic and mechanical dredging can lethally harm or kill 

various life stages of Gulf sturgeon. Of the three dredge types (hopper, clam, and pipeline), the hopper 

captured the most sturgeon (USDOI, FWS and USDOC, NMFS, 2009). The hopper dredges entrain 

young sturgeon either through the drag arm or the impeller pumps. Potential impacts from hydraulic 

dredge operations may be avoided by imposing work restrictions during sensitive time periods (i.e., 

spawning, migration, staging, and feeding) when sturgeon are most vulnerable to mortalities from 

dredging activity. 

Dredged material disposal is to be used beneficially for wetland restoration or creation, therefore 

eliminating the covering of important benthic feeding areas or fringe wetlands. Depending on the time of 

year, dredging can potentially entrain eggs, larvae, or postlarval sturgeon within the coastal rivers or near 

the river mouths. The CPA proposed action would not require dredging near natal rivers used as 

migratory routes to upstream spawning areas. While there could be a need for maintenance dredging in 

the nearshore waters, juvenile or adult sturgeon using these areas have the ability to avoid the dredging 

activity. The construction and maintenance of navigation channels is regulated by COE, and dredging 

permits are “conditioned” to avoid and minimize impacts to Gulf sturgeon and their critical habitat. The 

permitted activity is “conditioned” with specific time windows to exclude dredging during times of 

sturgeon migration, spawning, or active use of critical nursery areas. These conditioned permits are 

coordinated with either FWS or NMFS or both, depending on the origin of the dredging operation. At 

present, BOEMRE’s coordination with NMFS indicates no changes in critical habitat have occurred, and 

they are working to develop an estimate of sturgeon habitat loss and a Habitat Suitability Index for the 

species (Bolden, personal communication, 2010). They also have no data indicating that sturgeons are 

using the deeper Gulf waters where most of the OCS activities occur. In general, the mud substrates 

found in the Gulf waters do not support the appropriate benthic food source for Gulf sturgeon. 

Hurricanes and Other Natural Catastrophes 

Natural catastrophes and non-OCS activities such as dredge-and-fill may destroy or temporarily 

impair Gulf sturgeon habitat. Natural catastrophes including storms, floods, droughts, and hurricanes can 

result in substantial habitat damage. The result of Hurricane Ivan studies by McLelland and Heard (2004 

and 2005) demonstrated that the benthic forage base in the Choctawhatchee Bay was damaged and 

changed in composition as a result of the difference in sediment composition and nutrient loading. This 

lack of habitat caused Gulf sturgeon to temporarily abandon this feeding area. Parauka (personal 

communication, 2007a) noted an absence of Gulf sturgeon following Hurricanes Katrina, Rita, and 

Gustav in the Santa Rosa Sound. Further sampling indicated that the fish had moved to the Mobile Bay 

area but did return to the original Santa Rosa location within 1 to 1.5 years. 

Loss of habitat is expected to have a substantial effect on the reestablishment and growth of Gulf 

sturgeon populations. Natural phenomenon such as tropical storms and hurricanes will continue to occur 

along the Gulf Coast with varying frequency and intensity between years. Although these are usually 

localized and sporadic, the 2004 and 2005 hurricane seasons brought major and repeated damage to the 

Gulf Coast area. The effects from Hurricane Katrina (2005) are still being assessed. As a result of 
Description of the Environment and Impact Analysis 4-257 

Hurricanes Katrina, Rita and Ike, sampling in the western portion of the range in Louisiana and 

Mississippi has been sparse. However, new studies to survey the Pearl River for Gulf sturgeon and to 

track its movements began in summer 2009 (USDOI, FWS and USDOC, NMFS, 2009, as per Bolden, 

personal communication, 2010). It was noted that Hurricanes Gustav and Ike did initially displace some 

of the Gulf sturgeon in the Mississippi-Louisiana area, much like what happened in Florida during 

Hurricane Katrina. Current surveys along the Mississippi coast indicate no permanent impact to critical 

habitat, and Parauka (personal communication, 2007a) acknowledged that the sturgeons have returned to 

their normal feeding and resting areas along the coastal rivers. Sampling is not yet complete to see if the 

population has had any change in composition or if spawning has occurred (Slack, personal 

communication, 2008). 

The effects on Gulf sturgeon from COE’s operation of Federal dams, water control structures 

including freshwater diversions, and reservoirs in the impacted area included a large portion of the 

designated critical habitat and known locations of Gulf sturgeon. The sturgeons are located upstream in 

freshwater riverine habitats during hurricane season. This may give the estuarine and marine areas time 

to recover from hurricane impacts before the sturgeon move downstream. For instance, massive runoff 

due to flooding rains and swollen tributaries could cause a sharp increase in toxic contaminants in 

estuarine habitats. Evaluations of water and sediment quality in Gulf sturgeon habitat on the northern 

Gulf of Mexico coast have consistently shown elevated pollutant loading. This has been observed in both 

tidal coastal rivers of the type that the sturgeon use in the spring and summer (Hemming et al., 2006 and 

2008, as reported by USDOI, FWS, and USDOC, NMFS 2009). Perhaps better understood is the 

widespread contamination throughout the overwintering feeding habitat of the Gulf sturgeon (USDOI, 

FWS and USDOC, NMFS, 2009). However, spreading and dilution should mitigate any threat to 

sturgeon very quickly. By the time the downstream migration occurs, conditions should have returned to 

near normal. 

Parauka (personal communication, 2007a) noted that his sturgeon monitoring program located fish 

that were displaced from the Panama City, Florida, area to Mobile Bay, Alabama. He noted this 

movement may have been as a result of damaged habitat in Florida; however, the return of the fish this 

year is indicative of habitat recovery. Similar absences were noted by Kirk and Rogillio (personal 

communication, 2007) in the Pearl River system, but again current monitoring indicates that the 

population of Gulf sturgeon is returning. The flooding and subsequent “unwatering” of New Orleans in 

the fall of 2005 created concern for any sturgeon that might have been in the areas of Lake Pontchartrain, 

which is where those contaminated floodwaters were pumped. The COE noted in their environmental 

assessment that temporary impacts to Gulf sturgeon may have resulted as a part of the “unwatering” 

activities related to the pumping of floodwaters into Lake Pontchartrain. Impacts due to the quantity and 

quality of the floodwaters may have caused some sturgeon to seek forage and resting areas in other more 

undisturbed locations of Lake Pontchartrain. It was expected that any sturgeon displaced returned to the 

area once the “unwatering” activities ceased (U.S. Dept. of the Army, COE, 2005a). After Hurricane 

Katrina, there were reports of fish kills and at least one confirmed report of a dead Gulf sturgeon due to 

low oxygen in the water from organic input from leaf litter and other sources such as raw sewage and 

untreated effluent (Cummins, 2005). Many municipalities or sources of discharges lost power or were 

flooded and were likely a source of contaminant discharge. The COE also noted that the emergency 

procedures permitted in the Panama City, Florida, aftermath of Hurricane Ivan may have created 

temporary impacts to species including the Gulf sturgeon, but that the emergency procedures did not 

adversely impact the species (U.S. Dept. of the Army, COE, 2005b). The hurricane impacts have not yet 

been fully assessed for Gulf sturgeon but are generally believed to be temporary (Parauka, personal 

communication, 2007a). 

Unpredicted drought events in the upper river basins are currently impacting some of the Gulf 

sturgeon’s riverine spawning habitat along the Apalachicola River in Florida. Recently, potential threats 

to the Gulf sturgeon’s habitat in the Apalachicola River system and the receiving bays have been raised as 

a consequence of reducing river flow to meet upstream water needs during drought conditions in Georgia. 

It is expected with the current predictions of climate change that there will continue to be cyclic drought 

conditions that will persist in various regions of the sturgeon’s range. This, combined with the increasing 

need for water from reservoirs in the urban areas north of the coast, will continue to be problematic for 

the conflicting needs for water. The OCS activities are primarily in deepwater marine locations outside of 

the inland spawning areas and migratory routes. 
4-258 Central Planning Area Supplemental EIS 

Red tides are caused by toxic marine algae that occurs in the Gulf of Mexico and is distributed 

Gulfwide. This algae contains a brevetoxin that causes paralysis, intoxication, irregular swimming 

motions, loss of equilibrium, convulsions, and regurgitation, which normally ends in death as a result of 

respiratory failure. Since the 1990’s, the blooms of red tide have been increasing in frequency, with the 

most recent outbreak occurring in 2007 and 2008. Red tide was the probable cause of death for at least 20 

Gulf sturgeons in Choctawhatchee Bay in 1999 (USDOI, FWS, 2000). 

Commercial Fishing 

Commercial fishing techniques such as trawling, gill netting, or purse seining, when practiced 

nonselectively, may impact species other than the target species. For example, Gulf sturgeons are a small 

part of the shrimp bycatch. It is estimated that for every 1.1 lb (0.5 kg) of shrimp harvested, 8.8 lb (4 kg) 

of bycatch is discarded (Sports Fishing Institute, 1989). The death of several Gulf sturgeons is expected 

from commercial fishing. Commercial fishing is expected to continue; however, the magnitude of the 

trawl fleet has been at least temporarily diminished by Hurricane Katrina. Aside from the “Katrina 

effect” on the industry, the Louisiana and Mississippi waters were closed to commercial fishing 

(including shrimp and oyster grounds) for 5 months as a result of the DWH event. In addition, increases 

in trawl density and successive trawling in one area may cause long-term impacts to the critical habitat. 

Other Impact-Producing Factors 

The cumulative and possibly repetitive effects of altering water flow in coastal rivers used by 

sturgeon for spawning may have long-term cumulative effects on the success of future spawning 

populations. Changes in climate may continue to alter weather patterns such that persistent drought 

conditions may naturally or artificially (alter flow for reservoir maintenance) reduce river flow over 

critical riverine spawning habitat and, in turn, may displace spawning activities closer to the coastal 

waters, increasing the vulnerability of sturgeon larvae to coastal and inland spills. Changes in climate 

may also increase flooding frequency and intensity, adding large amounts of both nutrients and toxins 

into the estuary. Warmer water, sea-level rise, and higher salinity levels could lead to accelerated 

changes in habitats utilized by Gulf sturgeon. Changes in water temperature may alter the growth and life 

history of fishes, and even moderate changes can make a difference in distribution and number (Florida 

Fish and Wildlife Commission, 2009). In addition, the currently proposed enlargement of coastal salt 

domes for use as oil-reserve storage will compromise flows in natal spawning rivers, as well as 

potentially increase salinity in the nearshore estuaries and bays (USDOI, FWS and USDOC, NMFS, 

2009). As proposed, large amounts of freshwater will be removed from coastal rivers currently used by 

Gulf sturgeon and will be used to hydraulically mine the salt domes, producing a hypersaline effluent that 

will be piped to the coastal waters. 

Access to historic Gulf sturgeon spawning habitat continues to be blocked by existing dams, and the 

ongoing operations of these dams also affect downstream habitat. Several new dams are being proposed 

that would increase these threats to the Gulf sturgeon and its habitat. Dams continue to impede access to 

upstream spawning areas and continue to adversely affect downstream habitat, including both spawning 

and foraging areas. The operation of the Federal reservoir in Georgia, which is controlled by COE, is 

affecting the spawning habitat of the Gulf sturgeon on the Apalachicola River in Florida. Two dams, 

Pools Bluff and Bogue Chitto Sills, also impact Gulf sturgeon movements in the Pearl River drainage. 

Upstream passage is likely possible over these structures during some flow conditions, but the extent to 

which passage occurs is still unknown. New studies to survey the Pearl River for Gulf sturgeon and to 

track their movements began in summer 2009 (Bolden, personal communication, 2010). Additional dams 

will be likely constructed in the future and will include dams on the Pearl River in Mississippi, Escambia 

River in Alabama, and Yellow and Apalachicola Rivers in Florida (USDOI, FWS and USDOC, NMFS, 

2009). The cumulative effect of these and possibly others when combined with other environmental 

factors can considerably diminish the riverine spawning habitat for the Gulf sturgeon. 

Summary and Conclusion 

The Gulf sturgeon and its critical habitat can be cumulatively impacted by activities such as oil spills, 

dredging, alteration and destruction of habitat, natural catastrophes, commercial fishing, and onshore 
Description of the Environment and Impact Analysis 4-259 

alterations resulting in change in river flow and salinity modifications. The effects from contact with 

spilled oil would be sublethal and last for less than 1 month (Berg, 2006). Currently, there is no existing 

public data to ascertain the short-term and long-term effects of the DWH event on Gulf sturgeon or their 

critical habitat. It can be said that the critical habitat was exposed to oil and could possibly have been 

repeatedly exposed to oil in some cases. Until information is available on the quantity, type, and toxicity 

of the oil and where its’ spatial subsurface location is, no assessment can be made to the benthic forage 

base of the Gulf sturgeon. Contact with spilled oil could have detrimental physiological effects. The 

juvenile and subadult Gulf sturgeon, at a minimum, seasonally use the nearshore coastal waters and could 

potentially be at risk from both coastal and offshore spills. However, several factors influence the 

probability of spilled oil contact with Gulf sturgeon or their critical habitat. Because of the low 

probability of an offshore oil spill from the CPA proposed action to impact Gulf sturgeon habitat (≤10%), 

Gulf sturgeon contact with oil is expected to be minimal. Also, the amount of oil projected to spill with a 

coastal spill is small (approximately 5 bbl) and it would have localized effects. The likelihood of spill 

occurrence and subsequent contact with, or impact to, Gulf sturgeon and/or their designated critical 

habitat is extremely low. Substantial damage to Gulf sturgeon critical habitat is expected from inshore 

alteration activities and natural catastrophes. As a result, it is expected that the Gulf sturgeon would 

experience a decline in population sizes and a displacement from their current distribution that would last 

more than one generation. Deaths of adult sturgeon are expected to occur from commercial fishing. 

The incremental contribution of the CPA proposed action to the cumulative impact is negligible. This 

is because the effect of contact between sale-specific oil spills and Gulf sturgeon is expected to be 

sublethal and last less than 1 month, and regulations and mitigations decrease impacts from routine 

events. 

The extent and scope of the spill resulting from the DWH event represents new information not 

assessed in the existing ESA Section 7 consultation in the GOM under the 5-Year Program. As a result of 

this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing GOM Multisale 

EIS with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE on 

September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. The existing 

consultation recognizes that BOEMRE-required mitigations and other reasonable and prudent measures 

should reduce the likelihood of impacts from BOEMRE-authorized activities. 

4.1.1.16. Fish Resources and Essential Fish Habitat 

The BOEMRE has reexamined the analysis for fish resources and (EFH) presented in the Multisale 

EIS and the 2009-2012 Supplemental EIS, based on the additional information presented below and in 

consideration of the DWH event. No substantial new information was found that would alter the impact 

conclusion for fish resources and EFH presented in the Multisale EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. Fish 

resources and EFH could be impacted by coastal environmental degradation, marine environmental 

degradation, pipeline trenching, and offshore discharges of drilling discharges and produced waters 

associated with routine activities. The impact of coastal and marine environmental degradation is 

expected to cause an undetectable decrease in fish resources or in EFH. Impacts of routine discharges are 

localized in time and space, are regulated by USEPA permits, and would have minimal impact. 

Accidental events that could impact fish resources and EFH include blowouts and oil or chemical spills. 

A subsurface blowout would have a negligible effect on Gulf of Mexico fish resources. If spills due to 

the CPA proposed action were to occur in open waters of the OCS proximate to mobile adult finfish or 

shellfish, the effects would likely be nonfatal and the extent of damage would be reduced due to the 

capability of adult fish and shellfish to avoid a spill. 

Impact-producing factors of the cumulative scenario that are expected to substantially affect fish 

resources and EFH include coastal and marine environmental degradation, overfishing, and to a lesser 
4-260 Central Planning Area Supplemental EIS 

degree, coastal petroleum spills and coastal pipeline trenching. At the estimated level of cumulative 

impact, the resultant influence on fish resources and EFH is expected to be substantial but not easily 

distinguished from effects due to natural population variations. The incremental contribution of the CPA 

proposed action to the cumulative impacts on fisheries and EFH would be small. 

4.1.1.16.1. Description of the Affected Environment 

A detailed description of the fish resources and EFH can be found in Chapter 3.2.8 of the Multisale 

EIS. Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.11 of the 2009-2012 Supplemental EIS. The following 

information is a summary of the resource description incorporated from the Multisale EIS and the 2009-

2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

The Gulf of Mexico supports a great diversity of fish. Distribution of fish species are related to 

variable ecological factors that include salinity, primary productivity, and bottom type. These factors 

differ widely across the Gulf of Mexico and between the inshore and offshore waters. Characteristic fish 

resources are associated with the various environments and are not randomly distributed. Major gradients 

include rainfall and river output, bottom composition, and depth. High densities of fish resources are 

associated with particular habitat types. Most finfish resources are linked both directly and indirectly to 

the vast estuaries that ring the Gulf of Mexico. Estuaries serve as nursery grounds for a large number of 

marine fishes that live on the inner continental shelves, such as the anchovies, herrings, mojarras, and 

drums. Because of the variety of habitats, almost the entire GOM is within a designated EFH. 

The Gulf also has some limited areas of smaller carbonate features often referred to as pinnacles 

offshore Mississippi and Alabama in the CPA. There are thousands of these carbonate mounds or 

pinnacles dotting the OCS of Mississippi/Alabama. They share many characteristics of patch reefs found 

in shallow tropical areas. The mounds are discrete, vary in size and structural complexity, and are 

surrounded by level sediment bottoms. The remaining OCS shelf, ranging to a depth of approximately 

200 m (656 ft), generally has a muddy or silty soft bottom. Fish communities that occur on topographic 

features and pinnacles are described in Chapter 3.2.8.1 of the Multisale EIS. Deepwater demersal fishes 

below several hundred meters of depth are better known than the deep pelagic species. Extensive trawl 

sampling of Gulf of Mexico continental slope demersal fish are reported in a major Agency-funded, deep 

Gulf study (Gallaway, 1981). 

Recently, hurricanes have been a prominent impacting factor to Gulf resources and have affected fish 

resources by destroying oyster reefs and by changing physical characteristics of inshore and offshore 

ecosystems. The intense hurricane season of 2005, including Hurricanes Katrina and Rita, did not affect 

the offshore fisheries as much as initially expected. By far, the worst resource devastation that occurred 

was for oyster populations, but even this fishery has recovered significantly, as evidenced in the 

Louisiana Dept. of Wildlife and Fisheries’ Stock Assessment Report for the public oyster seed grounds 

(Louisiana Dept. of Wildlife and Fisheries, 2010a). 

In September 2008, Hurricanes Gustav and Ike made landfall on the Gulf Coast. Hurricane Gustav 

came ashore southwest of New Orleans as a Category 2 storm, and Hurricane Ike made landfall as a 

Category 2 storm at Galveston, Texas. In April 2009, the Louisiana Dept. of Wildlife and Fisheries 

announced a $15.7 million cooperative research program with NOAA to monitor the recovery of 

Louisiana commercial fisheries impacted by Hurricanes Katrina, Rita, Gustav, and Ike (Louisiana Dept. 

of Wildlife and Fisheries, 2009). Caffey (personal communication, 2009) estimated revenue losses from 

Hurricanes Gustav and Ike on Louisiana fisheries and aquaculture sectors in excess of $98 million. The 

NOAA landings data show a drop in finfish harvest in both Louisiana and Texas, an increase in shrimp 

harvest in Texas, and a drop in shrimp harvest in Louisiana (USDOC, NMFS, 2008). This may be due to 

the loss of boats and infrastructure. 

In September 2008, the Louisiana Dept. of Wildlife and Fisheries (2008a and 2008b) released 

preliminary, nonquantitative reports of the effects of Hurricanes Gustav and Ike on Louisiana fisheries. 

In it they noted the extensive marsh erosion and vegetative debris present in the canals of southeastern 

Louisiana, as well as localized fish kills, loss of marsh through erosion, and displacement and 

encroachment of saltwater into freshwater areas, a contributor to loss of essential fish habitat. 
Description of the Environment and Impact Analysis 4-261 

The DWH event in Mississippi Canyon Block 252, southeast of Venice, Louisiana, introduced large 

quantities of oil into the water column between the spill site and the marshes of the central Gulf Coast 

during the spring and summer of 2010. Oil from this incident has been observed to contact shorelines 

from Galveston, Texas, to Apalachicola, Florida, with the primary areas of oiling occurring from Grand 

Isle, Louisiana, west of the mouth of the Mississippi River to Santa Rosa Island, Florida. The oil 

penetrated estuaries at least along the Louisiana and Mississippi coasts and was driven farther inshore by 

the passage of Hurricane Alex, which made landfall near the Texas/Mexico border. All of these estuaries 

are extremely important nursery areas (EFH) for fish and aquatic life (Bahr et al., 1982). Oiling of these 

areas, depending on the severity, can destroy nutrient-rich marshes and erode coastlines, adding to the 

destruction caused by the recent hurricanes. 

Early life stages of animals are usually more sensitive to environmental stress than adults (Moore and 

Dwyer, 1974). Oil can be lethal to fish, especially in larval and egg stages, depending on the time of the 

year that the event happened. Weathered crude oil has been shown in laboratory experiments to cause 

malformation, genetic damage, and even mortality at low levels in fish embryos of Pacific herring (Carls 

et al., 1998). Hernandez et al. (2010) recently studied seasonality in ichthyoplankton abundance and 

assemblage composition in the northern GOM off of Alabama. They found larvae representing 58 

different families. Fish egg abundance, total larval abundance, and taxonomic diversity were significantly 

related to water temperature, not salinity, with peaks in spring, spring-summer, and summer. Detailed 

analyses of ichthyoplankton are not available east of this single sampling station nor west of it closer to 

the spill area. The patterns found in this study do indicate, however, that a possible mortality occurred in 

the larval fishes of the Gulf that came in contact with the spilled oil, depending on the timing of the 

spawn and the area influenced by the spill. 

The use of dispersants adds to these uncertainties. Although Corexit 9500, the dispersant used, is 

believed to be the least toxic of all of its counterparts to small fish, its toxicity mixed with oil to specific 

species of ichthyoplankton is unknown. In July 2010, USEPA and NOAA proposed a monitoring 

program that will assess the toxicity of 20:1 oil/Corexit to Atlantic silversides. 

The addition of Corexit 9500 at the seafloor spill site and the surface resulted in the dispersion of oil 

in the water column. The addition of any carbon source such as oil can decrease dissolved oxygen due to 

microbial breakdown and was a particular concern during the DWH event due to the use of dispersants 

(Chapter 4.1.1.2.1.1). In areas where plumes of dispersed oil were previously found, dissolved oxygen 

levels decreased by about 20 percent from long-term average values in the GOM; however, scientists 

reported that these levels have stabilized and are not low enough to be considered hypoxic (USDOC, 

NOAA, 2010e). The drop in oxygen, which has not continued over time, has been attributed to microbial 

degradation of the oil. 

Methane gas (CH4) is commonly found in the Gulf of Mexico in concentrations of 6 x 10-5

milliliter/liter (ml/L) to 125 x 10-5 ml/L in the Gulf of Mexico (Frank et al., 1970). At their baseline 

levels, methane levels are controlled by methanotrophs (methane degrading bacteria) (Patin, 1999). Very 

little is really known about the effects of methane on fish. Patin (1999) reported elevated concentrations 

of methane, resulting from gas blowouts from drilling platforms in the Sea of Asov, resulted in significant 

species-specific pathological changes including damages to cell membranes, organs and tissues, 

modifications of protein synthesis and other anomalies typical for acute poisoning of fish. These impacts, 

however, were observed at levels of 1-10 ml/L. 

Recently published research (Kessler et al., 2011) revealed that a large amount of methane was 

released by the during the DWH event and, based upon the methane and oxygen distributions measured at 

207 stations in the affected area, a large amount of oxygen was respired by methanotrophs. Kessler et al. 

suggest that the methane triggered a large methanotroph bloom that rapidly degraded the methane, 

leaving behind a residual methanotrophic community. 

How assemblages of fish have changed or will change as a result of the DWH event is unknown at 

this time. Adult fish tend to avoid contact with oil in the water column. Specific effects of oil on 

organisms can include direct lethal toxicity, sublethal disruption of physiological processes (internal 

lesions), effects of direct coating by oil (suffocation by coating gills), incorporations of hydrocarbons in 

organisms causing tainting or accumulation in the food chain, and changes in biological habitat (Moore 

and Dwyer, 1974). 

In general, most reef fishes are associated with habitats on the continental shelf inshore of the spill. 

Most of these fish spawn during spring/summer and the larvae may be at risk, affecting recruitment in 
4-262 Central Planning Area Supplemental EIS 

future age classes. Surface feeders as menhaden and inhabitants of seagrass beds may be at risk 

depending on whether the oil floats or sinks. Sharks are commonly found Gulfwide in nearshore and 

offshore waters. Blacktip sharks and bull sharks are often found in estuaries Gulfwide and may be at risk, 

along with other estuarine species depending on the extent of the penetration of the oil into the estuaries. 

Of particular concern are Gulf populations of bluefin tuna. The occurrence of bluefin tuna larvae 

associated with the Loop Current boundary and the Mississippi River discharge plume is evidence that 

these species spawn in the GOM (Richards, 1990). Block et al. (2001) also reported on the GOM being 

used as a breeding ground and demonstrated trans-Atlantic migrations of bluefin tuna between the eastern 

Mediterranean, Atlantic, and GOM using electronic data storage tags. The North Atlantic bluefin tuna 

has its peak spawning period in April and May in the Gulf. 

The Western Atlantic stock has suffered a significant decline in spawning stock biomass since 1950, 

and a 20-year rebuilding plan has failed to revive the population or the North American fishery. The 

failure of the Gulf of Mexico spawning population to rebuild, as well as the scope of illegal and underreported catches, particularly in the Mediterranean Sea, are of such major concern that the species was 

recently considered by the Convention for International Trade in Endangered Species for endangered 

species listing in March 2010. On September 21, 2010, NMFS announced a 90-day finding for a petition 

to list Atlantic bluefin tuna (Thunnus thynnus) as endangered or threatened under the Endangered Species 

Act and to designate critical habitat concurrently with a listing (Federal Register, 2010f). 

Because of their decline in stock, the timing of their spawn in the Gulf, their buoyant eggs, and the 

timing of the DWH event, there is concern about further decline in the Gulf stock of bluefin tuna. The 

effects at this time are, however, unknown. 

Thus far, only anecdotal (observational) evidence is available concerning fish kills. Offshore, a few 

small fish kills very near the spill site have been reported.. On the shelf and inshore also, a few, small 

fish kills have been reported that included common inshore species such as Atlantic croaker, anchovy, 

and menhaden. 

During the DWH event, whale sharks were sited swimming in heavy oil 4 mi (6 km) from the spill 

site. These large, migratory sharks have been traced by satellite tags to come to the Gulf in the summer 

from as far away as Belize and Honduras. They are surface feeders, filtering plankton and tiny fish 

through their mouths. Oil poses a threat to them not only by direct ingestion but by coating their gills 

(Raines, 2010). 

The severity and the duration of the effects of all of these factors on the fish assemblages and 

fisheries of the Gulf of Mexico are unknown at this time. New information relevant to the effects of the 

DWH event was sought in referenced journal articles, particularly those regarding the Ixtoc and Exxon 

Valdez spills, as well as government publications, white papers, and government Internet sites. All 

relevant literature was incorporated. 

Essential Fish Habitat 

In consideration of existing mitigation measures, lease stipulations, and a submitted EFH assessment 

document, this Agency entered into a Programmatic Consultation agreement with NMFS on July 1, 1999, 

for petroleum development activities in the CPA and WPA. This agreement was extended into that 

portion of the Eastern Planning Area known as Lease Sale 181. 

Chapters 1.5 and 2.2.2 of the Multisale EIS discuss this Agency’s approach to the preservation of 

EFH, with specific mitigations. Chapter 3.2.1 of the Multisale EIS details coastal areas that are 

considered EFH, including wetlands and areas of submerged vegetation. Chapter 3.2.2 of the Multisale 

EIS describes live-bottom formations and their biotic assemblages, which are considered EFH. Chapter 

4.2.2.10 of the Multisale EIS contains the impact analysis of the proposed action on EFH. Chapter 

4.4.3.10 of the Multisale EIS contains the impact analysis for accidental spills on EFH. Chapter 4.5.10 of 

the Multisale EIS contains the impact analysis of cumulative actions. 

In 2005, a new amendment to the original EFH Generic Amendment was finalized (GMFMC, 2005). 

One of the most significant proposed changes in this amendment reduced the extent of EFH relative to the 

1998 Generic Amendment by removing EFH description and identification from waters between 100 

fathoms and the seaward limit of the EEZ. There are Fishery Management Plans in the Gulf of Mexico 

OCS region for shrimp, red drum, reef fishes, coastal migratory pelagics, stone crabs, spiny lobsters, coral 

and coral reefs, billfish, and highly migratory species. 
Description of the Environment and Impact Analysis 4-263 

A new EFH consultation has been initiated between BOEMRE’s Gulf of Mexico Region and 

NOAA’s Southeastern Region. Some of the EFH requirements may change with the new agreement. 

Until the new agreement is in place, the 1999 Programmatic Consultation with the elements described 

above will be the rule. 

4.1.1.16.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the fish resources and EFH can be found in Chapter 3.2.8 of the Multisale 

EIS. Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.11 of the 2009-2012 Supplemental EIS, and new information is 

presented in Chapter 4.1.1.16.1 of this Supplemental EIS. 

A detailed description of the possible impacts from routine activities associated with the CPA 

proposed action on fish resources and EFH is presented in Chapter 4.2.2.1.10 of the Multisale EIS and in 

Chapter 4.1.11.2 of the 2009-2012 Supplemental EIS. The following information is a summary of the 

resource description incorporated from the Multisale EIS and the Supplemental EIS, and new information 

that has become available since both documents were prepared. 

Effects on fish resources and EFH from routine activities associated with the CPA proposed action 

could result from coastal environmental degradation, marine environmental degradation, pipeline 

trenching, and offshore discharges of drilling discharges and produced waters. Since the majority of fish 

species within the CPA are estuary dependent, coastal environmental degradation resulting from the 

proposed action, although indirect, has the potential to adversely affect EFH and fish resources. The 

environmental deterioration and effects on EFH and fish resources result from the loss of Gulf wetlands 

and coastal estuaries as nursery habitat and from the functional impairment of existing habitat through 

decreased water quality. 

Proposed Action Analysis 

The routine impacts of the CPA proposed action on coastal wetlands and coastal water quality, with 

the exception of accidental events, are analyzed in detail in Chapters 4.2.2.1.3.2 and 4.2.2.1.2.1 of the 

Multisale EIS. Collectively, the adverse impacts from these effects are called coastal environmental 

degradation in this Supplemental EIS. The effects of the CPA proposed action on offshore live bottoms 

and marine water quality are analyzed in detail in Chapters 4.2.1.1.4.1.1 and 4.2.1.1.2.2 of the Multisale 

EIS. Collectively, the adverse impacts from these effects are called marine environmental degradation in 

this Supplemental EIS. The direct and/or indirect effects from coastal and marine environmental 

degradation on fish resources and EFH are summarized and considered below. 

Coastal Environmental Degradation 

A range of 0-1 new pipeline landfalls are projected in support of the proposed action (Chapter 

4.1.2.1.7 of the Multisale EIS). Localized, minor degradation of coastal water quality is expected in 

waterbodies in the immediate vicinity of coastal shore bases, commercial waste-disposal facilities, and oil 

refineries or gas processing plants as a result of routine effluent discharges and runoff. There are 0-12 

new gas processing plants projected in support of the CPA proposed action (Table 4-9 and Chapter 

4.1.2.1.4.2 of the Multisale EIS). 

Wetlands that could be impacted for some period of time or converted to open water are discussed in 

Chapter 4.2.2.1.3.2 of the Multisale EIS and in Chapter 4.1.1.4.2 of this Supplemental EIS. A small 

amount of the routine dredging done in coastal areas could be a direct or indirect consequence of the 

proposed action. Some resuspension of bottom contaminants would be realized during dredging 

operations, although very little would be soluble in the water column and in bioavailable form. Since the 

proposed action would have minimal impact to the coastal environment, it is expected that coastal 

environmental degradation from the CPA proposed action would have little effect on fish resources or 

EFH. 

Recovery of fish resources or EFH can occur from most, but not all, of the potential coastal 

environmental degradation. Fish populations, if left undisturbed, would regenerate quickly, but the loss 
4-264 Central Planning Area Supplemental EIS 

of wetlands as EFH could be permanent. At the expected level of effect, the resultant influence on fish 

resources or EFH from the CPA proposed action would be negligible and indistinguishable from natural 

population variations. 

Marine Environmental Degradation 

The Topographic Features Stipulation is discussed in Chapter 2.4.1.3.1 of the Multisale EIS, Chapter 

2.2.1.3 of the 2009-2012 Supplemental EIS, and Chapter 2.3.1.3.1 of this Supplemental EIS. The 

application of the guidelines outlined in NTL 2009-G39, “Potentially Sensitive Biological Features,” 

would also serve to prevent impacts to hard-bottom EFH habitat associated with topographic features that 

may be outside previously defined No Activity Zones. For any activities associated with the proposed 

action, USEPA’s Region 6 would regulate discharge requirements for the CPA through their NPDES 

permits. The projected total number of production structure installations resulting from the CPA 

proposed action (32-44) is for all water depths (Table 3-2). Bottom disturbance from structure 

emplacement operations associated with the proposed action would produce localized, temporary 

increases in suspended sediment loading, resulting in decreased water clarity and little reintroduction of 

pollutants. Structure removal results in artificial habitat loss and causes fish kills when explosives are 

used. 

Most multi-leg platforms are removed by severing their pilings with explosives placed 4.6 m (15 ft) 

below the seafloor. It is projected that 14-17 structures in water depths <200 m (<656 ft) in the CPA 

would be removed using explosives as a result of the proposed action (Table 3-2). It is expected that 

structure removals would have a negligible effect on fish resources because these activities kill only those 

susceptible fish in close proximity to the removal site. 

The projected length of pipeline installations for the CPA proposed action is 130-2,075 km 

(81-1,289 mi) for all water depths (Table 3-2). Trenching for pipeline burial has the potential to 

adversely affect fish resources. Any affected population is expected to recover to pre-disturbance 

condition quickly. At the expected level of impact, the resultant influence on fish resources would be 

negligible and indistinguishable from other natural population variations. 

The major sources of routine discharges to marine waters associated with the CPA proposed action 

are the temporary discharge of drilling muds and cuttings and the long-term discharge of produced-water 

effluent. Drilling muds can contain materials such as mercury and cadmium, which may be toxic to 

fishery resources depending on their concentration; however, the discharge plume disperses rapidly. 

Therefore, the concentrations are near background levels at a distance of 1,000 m (3,281 ft) and are 

usually nondetectable at distances greater than 3,000 m (9,842 ft) (Kennicutt, 1995). 

The toxicity of the metals associated with drilling muds also depends upon their bioavailability to 

organisms. Methylmercury is the bioavailable form of mercury (Trefry and Smith, 2003). In a study of 

methylmercury in sediments surrounding six offshore drilling sites, it was found that methylmercury 

concentrations did not vary significantly between nearfield and farfield sites (Trefry et al., 2003). 

Further, the study suggested that levels of methylmercury in sediments around drilling sites are not a 

widespread phenomenon in the Gulf of Mexico (Trefry et al., 2003). The discharge of drilling muds is, 

therefore, not anticipated to contribute to fish mortality either through direct exposure to discharged 

drilling muds or resuspension of muds through wave action or dredging. 

Produced-water discharges contain components and properties potentially detrimental to fish 

resources, including trace metals, hydrocarbons, brine, and organic acids. Offshore discharges of 

produced water are expected to disperse and dilute to background levels within 1,000 m (3,280 ft) of the 

discharge point (CSA, 1997b). Because the produced water is highly diluted, it is not anticipated and has 

it been shown to cause fish mortality in populations surrounding platforms. 

It is expected that marine environmental degradation from the CPA proposed action would have little 

effect on fish resources or EFH. The impact of marine environmental degradation is expected to cause an 

undetectable decrease in fish populations. Recovery of fish resources or EFH can generally occur from 

the potential marine environmental degradation. Fish populations, if left undisturbed, would regenerate 

quickly given the absence of catastrophic events. Offshore live bottoms and topographic features are not 

expected to be impacted. 
Description of the Environment and Impact Analysis 4-265 

Offshore discharges and subsequent changes to marine water quality would be regulated by USEPA 

NPDES permits. At the expected level of effect, the resultant influence on fish resources or EFH would 

be negligible and indistinguishable from natural population variations. 

Other Factors 

Structure emplacements can act as fish attracting devices and can result in aggregation of highly 

migratory fish species. A number of commercially important highly migratory species, such as tunas and 

marlins, are known to congregate around fish attracting devices. The attraction of pelagic highly 

migratory species to offshore structures would likely occur to some degree. Almost immediately after a 

platform is installed, the structure would be acting as an artificial reef. After just a few years, many of the 

fish species present would be residents and not new transients from nearby areas. Reef-building corals 

and other species such as black corals have also been documented colonizing numerous platforms 

(Sammarco et al., 2004; Boland and Sammarco, 2005). 

Summary and Conclusion 

It is expected that any possible coastal and marine environmental degradation from the CPA proposed 

action would have little effect on fish resources or EFH. The impact of coastal and marine environmental 

degradation is not expected to cause a detectable decrease in fish resources or in EFH. Routine activities 

such as pipeline trenching and OCS discharge of drilling muds and produced water would cause 

negligible impacts and would not deleteriously affect fish resources or EFH. This is because mitigation 

reduces the undesirable effects from dredging and other construction activities on coastal habitats. Permit 

requirements should ensure that pipeline routes either avoid different coastal habitat types or that certain 

techniques are used to decrease impacts. At the expected level of impact, the resultant influence on fish 

resources would cause minimal changes in fish populations or EFH. That is, if there are impacts, they 

would be short-term and localized; therefore, they would only affect small portions of fish populations 

and selected areas of EFH. As a result, there would be little disturbance to fish resources or EFH. In 

deepwater areas many of the EFH’s are protected under stipulations and regulations currently set in place. 

The BOEMRE has reexamined the analysis for impacts to fish resources and EFH presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented above. 

No substantial new information was found that would alter the overall conclusion that impacts to fish 

resources and EFH from routine activities associated with the CPA proposed action would be minimal to 

none. The CPA proposed action is expected to result in a minimal decrease in fish resources and/or 

standing stocks or in EFH. It would require a short time for fish resources to recover from most of the 

impacts. Recovery from the loss of wetlands habitat would probably not occur. 

Additional hard substrate habitat provided by structure installation in areas where natural hard bottom 

is rare would tend to increase fish populations. The removal of these structures would eliminate that 

habitat, except when decommissioned platforms are used as artificial reef material. This practice is 

expected to increase over time. 

4.1.1.16.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts upon fish resources and EFH in the CPA can be found in 

Chapter 4.4.10 of the Multisale EIS and in Chapter 4.1.11.3 of the 2009-2012 Supplemental EIS. The 

risk of oil spills from the proposed action has the potential to affect fish resources and EFH, and it is 

discussed in detail in Chapter 4.3.1 of the Multisale EIS. The following is a summary of the information 

incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

Further, the effect of accidental events from the CPA proposed action on coastal wetlands and coastal 

water quality is analyzed in Chapters 4.4.3.2 and 4.4.2.1 of the Multisale EIS and in Chapters 4.1.3.2.3 

and 4.1.2.1.3 of the 2009-2012 Supplemental EIS. Both of these discussions are based upon oil untreated 

with dispersants. These are mentioned because they are important resources to fisheries species. 

Accidental events that could impact fish resources and EFH include blowouts and oil or chemical spills. 
4-266 Central Planning Area Supplemental EIS 

Proposed Action Analysis 

Currently, the CPA proposed action is estimated to result in the drilling of a total of 65-121 

exploration wells and 338-576 development and production wells. Of these production wells, 149-263 

are estimated to be producing oil wells and 144-237 are estimated to be producing gas wells (Table 3-2). 

There is a 69-86 percent chance of one or more spills ≥1,000 bbl occurring. The most likely source or 

cause of an offshore spill is also discussed in Chapters 4.3.1.5.2 and 4.3.1.6.2 of the Multisale EIS. The 

most likely size of spill is the smallest size group (<1 bbl). Spills that contact coastal bays and estuaries 

would have the greatest potential to affect fish resources. The risks of an oil spill ≥1,000 bbl occurring 

and contacting county and parish shorelines and specific sensitive biological features were calculated and 

are presented in Figures 4-12, 4-13, 4-14, and 4-16 of the Multisale EIS. The probability of an oil spill 

≥1,000 bbl occurring from the CPA and stranding on the Chandeleur Islands is calculated to be 3-5 

percent over its 40-year life. The risk to other hard/live bottoms in the Gulf of Mexico such as the 

Pinnacle Trend was not calculated. Other areas of hard-bottom shelf (EFH) would potentially remain 

unharmed as spilled substances could reach the seafloor in small concentrations. This is because of the 

distances and time required for transportation from the deepwater areas of the CPA proposed action and 

the potential dispersion of oil. 

There is a small risk of spills occurring during shore-based support activities, and the majority would 

be small in size. Most of these incidents would occur at or near pipeline terminals or shore bases and are 

expected to affect a highly localized area with low-level impacts. As a result of spill response and 

cleanup efforts, most of the inland spill would be recovered and what is not recovered would affect a 

small area and dissipate rapidly. A total of 15-34 coastal spills of all sizes are estimated to occur over the 

40-year life of the proposed action (Chapter 4.3.1.7.1 of the Multisale EIS). It is also assumed that a 

petroleum spill would occasionally contact and affect nearshore and coastal areas important to Gulf of 

Mexico fisheries. These species are highly migratory and would actively avoid the spill area. 

Blowout and Oil-Spill Impacts 

Loss of well control and resultant blowouts seldom occur on the Gulf OCS. The potential causes and 

probabilities of blowouts are discussed in Chapter 4.3.1.2 of the Multisale EIS. A blowout with 

hydrocarbon release has a low probability of occurring as a result of the proposed action. Less than one 

blowout of 1,000 bbl is projected for the entire depth range of the CPA proposed action. A blowout 

with an oil release has a low probability of occurrence, but it is possible given the occurrence of the spill 

resulting from the DWH event. 

Subsurface blowouts, although highly unlikely, have the potential to adversely affect fish resources. 

A blowout at the seafloor could create a crater and resuspend and disperse large quantities of bottom 

sediments. This potentially affects a limited number of resident and transient fish in the immediate area. 

The majority of mobile deep-sea benthic or near-bottom fish taxa would be expected to leave (and not 

re-enter) the area of a blowout before being impacted by the localized area of resuspended sediments. 

Resuspended sediments can clog fish gills and interfere with respiration. Settlement of resuspended 

sediments may directly smother deepwater invertebrates that serve as food sources. However, coarse 

sediment should be redeposited quickly within several hundred meters or feet of a blowout site. Finer 

sediments can be more widely dispersed and redeposited over a period of hours to days within a few 

thousand meters or feet depending on the particle size. 

Oil loss from a blowout is rare although possible. Less than 10 percent of blowouts in recent history 

have resulted in spilled oil. Gas blowouts consist mainly of methane, which rapidly dissolves in the water 

column or disperses upward into the air. These gas blowouts are less of an environmental risk. Loss of 

gas well control does not always release liquid hydrocarbons. The release of hydrocarbons with the gas is 

possible. 

In the case of the DWH event (consisting of a combination of oil and gas), it has been suggested that 

the addition of dispersants at the seafloor has resulted in large subsurface clouds of elevated methane 

concentrations. These alleged areas of elevated methane concentrations may potentially result in areas of 

lowered dissolved oxygen concentrations due to the actions of methanotrophic bacteria. Literature on this 

subject is scarce, so little is really known about the effects of methane on fish. Methane gas (CH4) is 

commonly found in the Gulf of Mexico in concentrations of 6 x10 -5 ml/L to 125 x 10-5 ml/L in the Gulf 

of Mexico (Frank et al, 1970). Patin (1999) reported elevated concentrations of methane in the Sea of 
Description of the Environment and Impact Analysis 4-267 

Asov resulting from gas blowouts from drilling platforms. He reported that these levels resulted in 

significant species specific pathological changes. These include damages to cell membranes, organs and 

tissues, modifications of protein synthesis, and other anomalies typical for acute poisoning of fish. 

However, these impacts were observed at levels of 1-10 ml/L, which is higher than the background levels 

in the Gulf of Mexico. 

Recently published research (Kessler et al., 2011) revealed that a large amount of methane was 

released by the DWH event and, based upon the methane and oxygen distributions measured at 207 

stations in the affected area, a large amount of oxygen was respired by methanotrophs. Kessler et al. 

suggest that the methane triggered a large methanotroph bloom that rapidly degraded the methane, 

leaving behind a residual methanotrophic community. 

The toxicity of an oil spill depends on the concentration of the hydrocarbon components exposed to 

the organisms (in this case fish and shellfish) and the variation of the sensitivity of the species considered. 

The effects on and the extent of damage to fisheries resources from a petroleum spill are restricted by 

time and location. Oil has the potential to affect finfish through direct ingestion of hydrocarbons or 

ingestion of contaminated prey. Hydrocarbon uptake of prey can be by dissolved petroleum products 

through the gills and epithelium of adults and juveniles, decreased survival of larvae, and through the 

death of eggs (NRC, 1985 and 2002a). It can also result in incorporations of hydrocarbons in organisms 

causing tainting or accumulation in the food chain and changes in the biological habitat (Moore and 

Dwyer, 1974). 

The level of impacts of oil on fish depends on the amount of oil released, the toxicity of the oil, and 

the availability of bacteria to degrade the oil. The speed of degradation of the oil by bacteria is also 

related to the water temperature. Physical toxicity of oil to fishes depends on the application of 

dispersants and the toxicity of the dispersant. In the case of the DWH event, the application of the 

dispersant (Corexit 9500) at the seafloor and the surface was alleged to have had the potential to produce 

larger areas of subsurface anoxic water because of the degradation of oil by bacteria. The effect of oil on 

fishes is also related to the distance from the shore, the location in the Gulf of Mexico, and the time of the 

year that the spill occurs. In the case of the DWH event, however, few offshore and onshore fish kills 

have been observed in Louisiana (Bourgeois, written communication, 2010a), Mississippi (Devers, 

written communication, 2010), and Alabama (Denson, personal communication, 2010) (Table 4-7). 

Accidental spills have the potential to affect sensitive species in the Gulf of Mexico, such as the 

bluefin tuna that spawn in the Gulf of Mexico in April-May (Block et al., 2001). The Western Atlantic 

stock has suffered a significant decline in spawning stock biomass since 1950, and a 20-year rebuilding 

plan has failed to revive the population or the North American fishery. The failure of the Gulf of Mexico 

spawning population to rebuild, as well as the scope of illegal and under-reported catches (particularly in 

the Mediterranean Sea) are of such major concern that the species was recently considered by the 

Convention for International Trade in Endangered Species for endangered species listing in March 2010. 

On September 21, 2010, NMFS announced a 90-day finding for a petition to list Atlantic bluefin tuna 

(Thunnus thynnus) as endangered or threatened under the Endangered Species Act and to designate 

critical habitat concurrently with a listing (Federal Register, 2010f). Because of their decline in stock 

from overfishing, the timing of their spawn in the Gulf, their buoyant eggs, and the timing of the DWH 

event, there is concern about further decline in the Gulf stock of blue fin tuna. 

The effect of petroleum spills on fish resources as a result of the proposed action is expected to cause 

a minimal decrease in fish resources or standing stocks of any population. At the expected level of 

impact, the resultant influence on fish populations within or in the general vicinity of the proposed lease 

sale area would be negligible and indistinguishable from natural population variations. 

Summary and Conclusion 

Accidental events that could impact fish resources and EFH include blowouts and oil or chemical 

spills. Subsurface blowouts, although highly unlikely, have the potential to adversely affect fish 

resources. If spills due to the CPA proposed action were to occur in open waters of the OCS proximate to 

mobile adult finfish or shellfish, the effects would likely be nonfatal and the extent of damage would be 

reduced due to the capability of adult fish and shellfish to avoid a spill, to metabolize hydrocarbons, and 

to excrete both metabolites and parent compounds. Fish populations may be impacted by an oil spill but 

they would be primarily affected if the oil reaches the productive shelf and estuarine areas, and this 
4-268 Central Planning Area Supplemental EIS 

probability is generally low. Also, much of the coastal northern Gulf of Mexico is a moderate- to highenergy environment; therefore, sediment transport and tidal stirring should reduce the chances for oil 

persisting in these habitats if they are oiled. Early life stages of animals are usually more sensitive to 

environmental stress than adults (Moore and Dwyer, 1974). Oil can be lethal to fish, especially in larval 

and egg stages, depending on the time of the year that the event happened. The extent of the impacts of 

the oil would depend on the properties of the oil and the time of year of the event. 

Fisheries closures may result from a large spill event. These closures may have a negative effect on 

short-term fisheries catch and/or marketability. In the long term, they may have a positive impact on 

species populations. 

The effect of proposed-action-related oil spills on fish resources is expected to cause a minimal 

decrease in standing stocks of any population because most spill events would be localized; therefore, 

they would affect a small potion of fish populations. Historically, there have been no oil spills of any size 

that have had a long-term impact on fishery populations. Although many potential effects of the DWH 

event on the fish populations of the Gulf of Mexico have been alleged, the actual effects are at this time 

unknown and the total impacts are likely to be unknown for several years. 

4.1.1.16.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts on commercial fishing can be found in Chapter 4.5.10 of 

the Multisale EIS and in Chapter 4.1.11.4 of the 2009-2012 Supplemental EIS. The following is a 

summary of the information presented in those documents, and incorporates new information found since 

publication of the 2009-2012 Supplemental EIS. 

This cumulative analysis summary includes effects of the OCS Program (the proposed action and past 

and future OCS lease sales), State oil and gas activity, coastal development, crude oil imports by tanker, 

commercial and recreational fishing, and natural phenomena. Specific types of impact-producing factors 

considered in this cumulative analysis include cumulative onshore impacts such as (1) wetland loss as a 

result of environmental degradation and natural factors, e.g., hurricane loss of wetlands; (2) marine 

environmental degradation including factors affecting marine hypoxia; and (3) physical disturbance of 

live-bottom features, including non-OCS-related disturbances such as those related to commercial and 

recreational fishing; (4) removal of production structures; (5) petroleum spills; (6) subsurface blowouts; 

(7) pipeline trenching; and (8) offshore discharges of drilling mud and produced waters. All of these 

subjects are discussed at length in Chapter 4.5.10 of the Multisale EIS and in Chapter 3 of the 2009-2012 

Supplemental EIS. 

Wetland Loss 

The most serious impact to coastal EFH is the cumulative effects on wetlands that are occurring at an 

ever-increasing rate. This is from the population increase of the Gulf Coast States and the recent effects 

of major storms on wetland loss. The cumulative impacts of pipelines; canal dredging to accommodate 

commercial, residential, and recreational development; and major storm events (i.e., Hurricanes Katrina 

and Rita 2005; Hurricanes Gustav and Ike 2008) to wetlands are described in Chapter 4.5.3.2 of the 

Multisale EIS, in Chapter 4.1.3.2.4 of the 2009-2012 Supplemental EIS, and in Chapter 4.1.1.4.4 of this 

Supplemental EIS. 

In comparison to the large area of wetland loss to commercial and recreational development, as well 

as to natural forces such as hurricanes, the incremental wetland losses due to the CPA proposed action are 

anticipated to be minimal. 

Marine/Estuarine Water Quality Degradation 

The coastal waters of the CPA are expected to continue to experience nutrient overenrichment, 

periods of low-dissolved oxygen, and toxin and pesticide contamination. This results in the loss of both 

commercial and recreational uses of the affected waters. Fish kills and shellfish-ground closures would 

likely increase in numbers in the coming years. Localized, minor degradation of coastal water quality is 

expected from the proposed action within the immediate vicinity of the waterbodies proximate to the 
Description of the Environment and Impact Analysis 4-269 

proposed service bases, commercial waste-disposal facilities, and gas processing plants as a result of 

routine effluent discharges and runoff. Only a small amount of dredging would occur as a result of the 

CPA proposed action. 

The incremental contribution of the CPA proposed action, because the input of effluent, runoff, and 

nutrients from such action is very limited, would be a very small part of the cumulative impacts to coastal 

water quality. 

Damage to Live Bottoms 

Non-OCS sources of impacts on biological resources and the structure of live bottoms include natural 

disturbances (e.g., turbidity, disease, and storms), anchoring by recreational and commercial vessels, and 

commercial and recreational fishing. These impacts may result in severe and permanent mechanical 

damage at various scales to live-bottom communities. Fishing activities that could impact live bottoms 

would include trawl fishing and trap fishing. These techniques and their impacts are described in detail in 

the Chapter 4.5.10 of the Multisale EIS. 

The OCS-related activities that could impact the biological resources and the structure of live bottoms 

are the anchoring of vessels, emplacement of structures (drilling rigs, platforms, and pipelines), 

sedimentation (operational waste discharges, pipeline emplacement, explosive removal of platforms, and 

blowouts), and chemical contamination (produced water, operational waste discharges, and petroleum 

spills). Live-bottom features in the CPA consist primarily of the Pinnacle Trend, which is described in 

detail in Chapter 4.1.4.1.1 of the Multisale EIS. The Topographic Features Stipulation (in the CPA and 

WPA), enacted by this Agency and clarified in its NTL 2009-G39, would prevent most of the potential 

impacts on live-bottom communities and EFH from any OCS Program activities. These include bottomdisturbing activities (anchoring, structure emplacement and removal, and pipeline trenching), operational 

offshore waste discharges (drilling mud and cuttings and produced waters), and any nearby blowouts. 

Because there are a large number of natural factors that can affect live bottoms and because the OCS 

factors that can affect live bottoms have been mitigated by BOEMRE, the OCS factors are anticipated to 

be a small portion of impacts to live bottom features in the CPA. 

Structure Removals 

Structure removals would result in artificial habitat loss. It is estimated that 30-42 structures would 

be removed as a result of the OCS Program in the CPA (Table 3-2). It is expected that structure removals 

would have an effect on fish resources near the removal sites when explosives are used (23-32 structures 

are expected to be removed by explosives, Table 3-2). However, only those fish proximate to sites 

removed by explosives would be killed. These expected impacts to fish resources have been shown to be 

small overall and would not alter determinations of status for impacted species or result in changes in 

management strategies (Gitschlag et al., 2000). 

Petroleum Spills 

Spills that contact coastal bays, estuaries, and offshore waters when pelagic eggs and larvae are 

present have the greatest potential to affect fish resources. If spills occur in these coastal environments or 

waters of the OCS that are proximate to mobile adult finfish or shellfish, the effects would likely be 

nonfatal. The extent of this damage would be reduced due to the capability of adult fish and shellfish to 

avoid a spill, to metabolize hydrocarbons, and to excrete both metabolites and parent compounds. For 

eggs and larvae contacted by spilled oil, the effect is expected to be lethal. The numbers and sizes of 

coastal spills over the 40-year life of the proposed action are presented in Table 4-13 of the Multisale EIS. 

About 90 percent of these spills are projected to be from non-OCS-related activity. For spills <1,000 bbl, 

the assumed size for an average spill is 5 bbl, so the great majority of coastal spills would affect a very 

small area and dissipate rapidly (Table 4-13 of the Multisale EIS). The small coastal spills that do occur 

from OCS-related activity would originate near terminal locations in the coastal zones of the CPA. 

One large (≥1,000 bbl) offshore spill is projected to occur annually from the Gulfwide OCS Program 

(Table 4-13 of the Multisale EIS), and a total of 1,500-1,800 small offshore spills (<1,000 bbl) are 

projected annually. Of these, 450-500 would originate from OCS Program sources. Chapter 4.3.1.2 of 

the Multisale EIS describes projections of future spill events in more detail. The impacts of a catastrophic 
4-270 Central Planning Area Supplemental EIS 

spill, such as the DWH event, in the CPA are discussed in detail in Appendix B with the currently 

available data. 

Because spills are a low-probability event, both in the inshore and the OCS area, the cumulative 

impact on EFH and fish populations in the CPA is not anticipated to be large as a result of the CPA 

proposed action. 

Subsurface Blowouts 

Subsurface gas blowouts of both oil and natural gas wells have the potential to affect adversely 

fishery resources. Loss of well control and resultant blowouts seldom occur on the Gulf of Mexico OCS. 

Considering the entire OCS Program during the 40-year analysis period, it is projected that there would 

be 169-197 blowouts out of 23,181-26,243 development wells (<1%) for all water depths in the CPA 

(Table 4-6 of the Multisale EIS). 

Sandy sediments would be quickly redeposited within 400 m (1,312 ft) of a blowout site, and finer 

sediments would be widely dispersed and redeposited within a few thousand meters or feet over a period 

of 30 days or longer. These events are expected to have a negligible impact on fish populations. It is 

expected that the infrequent subsurface natural gas blowout that may occur on the Gulf of Mexico OCS 

would have a negligible effect on offshore fish resources. 

Subsurface blowouts, such as the DWH event, that include both oil and natural gas have the potential 

to affect fish populations, particularly eggs, larvae, and juveniles. The specific effects of this type of spill 

on individual fish populations in the Gulf of Mexico are currently unknown. Spills from this type of a 

blowout are a low-probability event, so the cumulative impact on EFH and fish populations in the CPA is 

not anticipated to be large as a result of the proposed CPA lease sale. 

Pipeline Trenching 

Sediment would potentially be resuspended during the installation of pipelines. A total of 

130-2,075 km (80-1,289 mi) of pipeline is projected to be installed in the CPA (only in the water depth 

category of <60 m or 200 ft) during the 40-year analysis period (Table 3-2). In many areas of the Gulf of 

Mexico, sediments are not static, as evidenced by the relatively recently discovered deep-sea furrows 

(Bryant et al., 2004). 

Because the contribution of resuspended sediment as a result of pipeline trenching compared with the 

natural movement of sediment on the sea floor is very small, the effect on fish resources from pipeline 

trenching is expected to be minimal. 

Discharges of Drilling Mud and Produced Waters 

Drilling mud discharges contain chemicals toxic to marine fishes. These concentrations of toxins are 

four or five orders of magnitude higher than those found more than a few meters or feet from the 

discharge point. Offshore discharges of drilling mud dilute to near background levels within 1,000 m 

(3,280 ft) of the discharge point and would have a negligible effect on the fishery. 

Produced-water discharges contain components and properties detrimental to fishery resources. 

These include petroleum hydrocarbons, trace metals, radionuclides, and brine. Limited petroleum 

concentrations and metal contamination of sediments and the upper water column would occur out to 

several hundred meters or feet down current from the discharge point. Offshore discharges of produced 

water disperse and dilute to near background levels within 1,000 m (3,280 ft) of the discharge point and 

have a negligible effect on fisheries. Offshore live bottoms would not be impacted. Offshore discharges 

and subsequent changes to marine water quality are regulated by USEPA NPDES permits. 

Biomagnification of mercury in large fish of higher trophic levels is a problem in the Gulf of Mexico. 

In the press, biomagnification is often associated with drilling discharges, but the bioavailability and any 

association with trace concentrations of mercury in discharged drilling mud has not been demonstrated. 

Numerous studies have concluded that platforms do not contribute to higher mercury levels in marine 

organisms. Recent data suggest that mercury in sediment from drilling platforms is not in a bioavailable 

form (Trefry and Smith, 2003; Trefry et al., 2003). 

The input of drilling mud and produced waters are limited and are diluted very quickly in the marine 

environment. Their environmental effects are, therefore, expected to be limited. 
Description of the Environment and Impact Analysis 4-271 

Summary and Conclusion 

Activities resulting from the OCS Program and non-OCS events in the northern Gulf of Mexico have 

the potential to cause cumulative detrimental effects on fish resources and EFH. Impact-producing 

factors of the cumulative scenario that are expected to substantially affect fish resources and EFH include 

coastal and marine environmental degradation, overfishing, and to a lesser degree, coastal petroleum 

spills and coastal pipeline trenching. The implementation of proposed lease stipulations and mitigation 

policies that are currently in place, the small probability of an oil spill, and that flow regimes are not 

expected to change further reduce the incremental contribution of stress from the CPA proposed action on 

coastal habitats. The Live Bottom (Low Relief) Stipulation and the guidelines in NTL’s 2009-G39 and 

2009-G40 would limit the potential impact of any activities on deepwater EFH because the stipulation 

and NTL’s keep the sources of such adverse events geographically removed from EFH. Decreases of 

impacts to EFH will decrease the impacts of similar activities on fish resources. At the estimated level of 

cumulative impact, the resultant influence on fish resources and EFH is expected to be substantial, but not 

easily distinguished from effects due to natural population variations. 

The incremental contribution of the CPA proposed action to the cumulative impacts on fish resources 

and EFH is small, as analyzed in Chapters 4.2.2.1.10, 4.4.10, and 4.5.10 of the Multisale EIS. The effects 

of impact-producing factors (e.g., coastal and marine environmental degradation, petroleum spills, 

subsurface blowouts, pipeline trenching, and offshore discharges of drilling mud and produced waters) 

related to the CPA proposed action are expected to be negligible and virtually undetectable among the 

other cumulative impacts and natural population variability. 

4.1.1.17. Commercial Fishing 

The BOEMRE has reexamined the analysis for commercial fishing presented in the Multisale EIS and 

the 2009-2012 Supplemental EIS, based on the additional information presented below and in 

consideration of the DWH event. No substantial new information was found that would alter the impact 

conclusion for commercial fishing presented in the Multisale EIS and the 2009-2012 Supplemental EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. 

Routine activities in the CPA, such as seismic surveys and pipeline trenching, would cause negligible 

impacts and would not deleteriously affect commercial fishing activities. Indirect impacts from routine 

activities to inshore habitats are negligible and indistinguishable from direct impacts of inshore activities 

on commercial fisheries. The potential impacts from accidental events (i.e., a well blowout or an oil spill) 

associated with the CPA proposed action are anticipated to be minimal. Commercial fishermen are 

anticipated to avoid the area of a well blowout or an oil spill. Any impact on catch or value of catch 

would be insignificant compared with natural variability. The incremental contribution of the proposed 

action to the cumulative impacts on commercial fishing is small, and it is expected to be negligible and 

indiscernible from natural fishery population variability. 

4.1.1.17.1. Description of the Affected Environment 

Detailed descriptions of commercial fishing can be found in Chapter 3.3.1 of the Multisale EIS and in 

Chapter 4.1.12.1 of the 2009-2012 Supplemental EIS. The following is a summary of the information 

incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

Finfish 

Commercial fishing regulations are detailed and change on a regular basis depending on a variety of 

factors, including stock assessment and catch statistics. These regular changes, not withstanding any 

closures based on the DWH event, can occur on short notice. This is especially true for time closures 

based on allowable catches. The Gulf of Mexico Fishery Management Council (GMFMC) provides the 
4-272 Central Planning Area Supplemental EIS 

current information on commercial and recreational fishing rules for U.S. Federal waters of the GOM 

(GMFMC, 2010a and 2010b). 

In September 2008, Hurricanes Gustav and Ike made landfall on the Gulf Coast. Hurricane Gustav 

came ashore southwest of New Orleans as a Category 2 storm, and Hurricane Ike made landfall as a 

Category 2 storm at Galveston, Texas. In April 2009, the Louisiana Dept. of Wildlife and Fisheries 

announced a $15.7 million cooperative research program with NOAA to monitor the recovery of 

Louisiana commercial fisheries impacted by Hurricanes Katrina, Rita, Gustav, and Ike (Louisiana Dept. 

of Wildlife and Fisheries, 2009). Caffey (personal communication, 2009) estimated revenue losses from 

Hurricanes Gustav and Ike on Louisiana fisheries and aquaculture sectors in excess of $98 million. The 

NOAA landings data show a drop in finfish and shrimp harvest in Louisiana (USDOC, NMFS, 2010c). 

This may be due to loss of boats and infrastructure. 

In September 2008, the Louisiana Dept. of Wildlife and Fisheries (2008a and 2008b) released 

preliminary, nonquantitative reports of the effects of Hurricane Gustav on Louisiana fisheries. In it they 

noted the extensive marsh erosion and vegetative debris present in the canals of southeastern Louisiana. 

There was a loss of marsh through erosion and displacement and encroachment of saltwater into 

freshwater areas, which contributes to the loss of essential fish habitat, and localized fish kills. 

Menhaden, with landings of over 1 billion pounds and valued at $60.5 million, was the most 

important Gulf species in terms of quantity landed during 2009. The menhaden catch was up from 927.5 

million pounds worth $64.3 million in 2008 in the Gulf of Mexico, although the price per pound was 

down (USDOC, NMFS, 2010c). Data presented in the 2009-2012 Supplemental EIS clearly show that 

menhaden and shrimp are major fisheries in the Gulf of Mexico. Menhaden are harvested extensively for 

their oil, which is included in animal food and human supplements as Omega-3 fatty acid. 

The DWH event changed the baseline of GOM commercial fishing, at least for the 2010 fishing 

season, because of the massive fishing closures associated with the event. This spill resulted in 

commercial fisheries closures in the GOM waters (EEZ) as well as State and inshore waters in Louisiana, 

Mississippi, Alabama, and Florida at various times during the spill. State commercial fishing areas 

changed with the movement of the oil. The closures were generally limited to the area between 

Vermilion Bay, Louisiana, and Pensacola, Florida. 

The fishing closure area in the Gulf varied from 6,817 mi2

 (17,648 km2) on May 2, 2010, when the 

closure was initiated to a high of 88,522 mi2

 (229,270 km2), or 36 percent, of the EEZ on June 2, 2010. 

The closure area was located off the coasts of Louisiana, Mississippi, Alabama, and Florida based on 

projections of the path of the spilled oil. The closed area increased as the spill continued and spread 

(USDOC, NOAA, 2010i). On April 19, 2011, NOAA reopened to commercial and recreational fishing 

the last areas of the Gulf closed to fishing due to the DWH spill (USDOC, NOAA, 2011b). 

The resulting impacts for the short- and long-term of the DWH event to commercial finfish species of 

the Gulf Coast are unknown at this time. Because nondispersed oil generally floats on the surface of 

water, the fisheries resources most at risk are those species whose eggs and larvae float near the water 

surface. Some species have spawning periods with narrow temporal peaks coinciding with the timing of 

the highest oil concentrations. These species could experience measurable effects on that area’s year 

class. Early developmental stages are generally more susceptible to sublethal toxic effects, which may 

lead to abnormal development. 

One important highly migratory species with a spawning period coinciding with the spill is the 

Atlantic bluefin tuna. This species has its peak spawning period in April and May in the Gulf (Teo et al., 

2007a and 2007b). A catastrophic spill, such as the DWH event, during the spring season may cause a 

negative effect on this population. This is one of only two documented spawning grounds for the Atlantic 

bluefin tuna (the other is in the Mediterranean). Eggs are buoyant, which puts them at greater risk of 

floating oil. Bluefin tuna are among the most valuable fish in global markets. On September 21, 2010, 

NMFS announced a 90-day finding for a petition to list Atlantic bluefin tuna (Thunnus thynnus) as 

endangered or threatened under the Endangered Species Act and to designate critical habitat concurrently 

with the listing (Federal Register, 2010f). There may be many other commercially important species 

such as menhaden, red snapper, groupers, mackerel, swordfish, sheepshead, blacktip sharks, red drum, 

speckled trout, and many more that occur on the shelf or in estuarine waters that have been affected by the 

DWH event. Due to the lack of published/analyzed data, these effects are unknown at this time. The 

largest cash fishery in the Gulf Coast is menhaden. Menhaden are small schooling fish that are surface 

feeders, making them very vulnerable to the surface oil. 
Description of the Environment and Impact Analysis 4-273 

There have been some confirmed reports of inshore fish kills, particularly in Louisiana, Mississippi, 

and Alabama. Fish kills have been reported in inshore Louisiana behind the Chandeleur Islands, behind 

the rock jetties at the mouth of the Mississippi River Gulf Outlet, at Joshua’s Marina south of Empire, in 

Bayou Chaland, and in Bay Joe Wise. Communications with Martin Bourgeois (written communication, 

2010a) and Harry Blanchet (written communication, 2010) about these various kills between August 24 

and September 24, 2010, confirm that most of the species that died were menhaden in high-temperature, 

low dissolved oxygen waters. This is not unusual during the summer in the shallow, high-temperature, 

low dissolved oxygen waters of Louisiana that contain large concentrations of fish. It is impossible, 

however, to discount completely that the oil spill contributed to the oxygen depletion of these waters. 

While this is a somewhat common occurrence, oil cannot be ruled out as a factor contributing to low 

dissolved oxygen. Fish kills in Louisiana and Mississippi are summarized in Table 4-7. Personnel from 

the Alabama Dept. of Environmental Monitoring confirmed that there had been some fish kills in Mobile 

Bay, all of which had been attributed to low dissolved oxygen and high temperatures (Denson, personal 

communication, 2010). 

Shellfish 

Commercial shellfish of most importance to the central Gulf Coast include shrimp (primarily brown 

and white), blue crabs, and oysters. In 2009, the central Gulf States harvested a total of nearly 56.1 

million pounds of brown shrimp and over 90.6 million pounds of white shrimp. This constitutes 

approximately 44 percent and 73 percent of the brown and white shrimp, respectively, harvested in the 

entire U.S. Blue crab harvest in the three central Gulf States was approximately 53.0 million pounds in 

2009, or about 35 percent of the total U.S. harvest. Eastern oyster (Crassostera virginica) harvest in 

Louisiana, Mississippi, and Alabama in 2009 totaled 16.9 million pounds of oyster meat or approximately 

68.4 percent of all the Eastern oyster meats harvested in the U.S. for that year. Louisiana alone harvested 

14.7 million pounds of oyster meats, or 59.5 percent of all of the Eastern oyster meats harvested in the 

U.S. in 2009. 

The commercially important species of shrimp (particularly the white and brown shrimp of Louisiana 

and Mississippi) and blue crabs spend at least part of their life cycle in the estuaries or on the nearshore 

shelf. Both shrimp species and the blue crab spawn in high salinity waters offshore, and the larvae and 

subadults move inshore to mature in the estuaries of the coast. These species are short lived, and losses to 

the crop from the DWH event may be evident in the 2011 harvest if they are not offset by the fishing 

closures. 

Eastern oyster grounds are located in the CPA from Sabine and Calcasieu Lakes eastward in the 

inshore bays and estuaries of Louisiana, through eastern Mississippi Sound (Mississippi), Mobile Bay 

(Alabama), and from upper Pensacola Bay through Apalachicola Bay (Florida). Public seed grounds in 

Louisiana include Calcasieu and Sabine Lakes, Bay Gardene, Hackberry Bay, Sister Lake, Bay Junop, 

Lake Borgne, Breton/Chandeleur Sound, Barataria Bay, Little Lake, Deep Lake, Lake Chien, Lake 

Felicity, Lake Tambour, Lake Mechant, and Vermilion/Cote Blanche and Atchafalaya Bays (Louisiana 

Dept. of Wildlife and Fisheries, 2010a). These seed grounds provide a source of spat (small oysters) for 

oystermen to transplant to their leases for grow-out, as well as a source of sack-sized oysters that can be 

readily marketed. Every July, the Louisiana Dept. of Wildlife and Fisheries conducts a survey of thee 

public seed grounds. The general trend of oyster abundance on the seed grounds has been decreasing 

since 2001, approaching the 2nd smallest statewide stock size since 1989. According to the 2010 

assessment, the 2010 stock size showed an overall slight increase over the 2009 stock size (Louisiana 

Dept. of Wildlife and Fisheries, 2010a). 

The DWH event may have an effect on this year’s crop, but it is difficult to infer with the current lack 

of public data. Many of the beds have been closed for most of the season. The public seed ground 

openings for much of the area east of the Mississippi River and Hackberry Bay west of the Mississippi 

River that were scheduled for November 15, 2010, have been postponed indefinitely because of the small 

size of the stock present in that area. Although the small stock size has not been directly attributed to the 

spill, it may be a result of the freshwater diversions that were operated in an attempt to keep oil from 

reaching the inshore areas. 

The larval and juvenile stages of aquatic organisms are more vulnerable to contact with hydrocarbons 

than adults (Moore and Dwyer, 1974). Contact with oil does not always kill adult oysters, a fact 
4-274 Central Planning Area Supplemental EIS 

demonstrated by Mackin and Sparks (1961), but it does affect their taste and render them unmarketable. 

Oysters will clear themselves of the taste given clean water conditions. If, however, the oil is combined 

with other stress factors, such as extreme temperatures and low salinities, death may result. In an attempt 

to keep the oil out of the inshore areas of Louisiana, the freshwater diversions were run at near maximum 

capacity. Sustained freshwater kills oysters, especially at high temperatures (Davis, 1958). The higher 

the temperature and the lower the salinity, the shorter the oyster life will be. 

Representatives of the Louisiana Dept. of Wildlife and Fisheries confirmed that there had been a 

complaint of an oyster kill in Bay Jacques in Plaquemines Parish, Louisiana, on June 20, 2010 

(Bourgeois, personal communication, 2010b). The report reads as follows: 

They saw approximately 100 floating pieces of oysters (more were seen coming from the 

prop wash so likely more dead ones on the bottom), but it is nearly impossible to 

estimate. Coordinates in decimal degrees—N29.28725 W89.51665, coordinates in 

decimal minutes—N29°17.235’ W89°30.999’. There are fish swimming in the area and 

no dead fish were seen. The surface DO was 10.2 mg/L, pH was 8.7, temp was 32.9°C, 

and salinity was 0.9 ppt. Bottom DO was 10.1 mg/L, pH was 8.7, temp was 32.9°C, and 

salinity was 0.9 ppt. Low salinity and high temperature combined appear to be 

responsible for this kill although other factors cannot be excluded. 

Mississippi Sound and Alabama oyster beds were closed to oyster fishing for approximately 2 months 

during the summer of 2010. There are several areas of oyster reefs in the panhandle of Florida: 

Pensacola, Choctawhatchee, St. Andrew, and Apalachicola. The primary producing area is Apalachicola 

Bay. None of the Florida Panhandle reefs areas were closed as a result of the spill. 

Stock Status 

The NOAA Fisheries reports to the Congress and Fishery Management Councils on the status of all 

fish stocks in the Nation. As of the 2008 status report (USDOC, NMFS, 2008), they reviewed 531 

individual stocks and stock complexes and made determinations of overfishing and overfished for 191 

complexes; an additional 68 stocks have either an overfishing or overfished determination. Overfishing is 

harvesting at a rate above a prescribed fishing mortality threshold, and overfished is defined as a stock 

size that is below a prescribed biomass threshold. Species that are currently listed as subject to 

overfishing in the GOM are red snapper, greater amberjack, gag grouper, gray triggerfish, and pink 

shrimp. Overfished species in the GOM are red snapper, greater amberjack, and gray triggerfish. The 

effects of the DWH event on the population levels of each of these species are unknown at this time. 

Economics of Commercial Fisheries 

The commercial fishing industry is an important component to the economy of the Gulf of Mexico. 

Table 4-8 provides an overview of the economic significance of the commercial fishing industry in the 

Gulf of Mexico (USDOC, NMFS, 2010d). Commercial fishing landings in the Gulf were worth over 

$700 million in 2008. Louisiana had the highest catch value with over $270 million, Texas and Florida 

each had around $170 million in landings, and Alabama and Mississippi each had around $40 million in 

landings. Detailed information regarding the catch rates and prices paid for individual species in each 

Gulf Coast State can be obtained through NMFS’s economics report (USDOC, NMFS, 2010d). Further 

information on fishing harvests at individual Gulf Coast ports is also available. 

Landings revenue also supports economic activity along the commercial fishing supply chain. 

Table 4-8 presents estimates of sales and employment in the economy that depend on commercial fishing 

activity. Approximately $10 billion in combined sales activity and over 200,000 jobs depend directly or 

indirectly on commercial fishing in the GOM. Of the Gulf Coast States, Florida has the highest level of 

overall commercial fishing-dependent jobs due to a large number of retail outlets and seafood distributors 

located in the state. Louisiana has approximately 40,000 jobs in the industry, while Alabama and 

Mississippi each have slightly under 10,000 jobs. More detailed breakdowns of sales and employment 

statistics in each Gulf Coast State can be obtained through NMFS. The final column of Table 4-8

presents the commercial fishing quotient, which is a measure of the concentration of the fishing industry 
Description of the Environment and Impact Analysis 4-275 

in a particular state relative to the national average. Louisiana has the highest commercial fishing 

quotient in the Gulf of Mexico; its commercial fishing quotient of 2.5 means that the concentration of the 

fishing industry in Louisiana is 2.5 times that of the U.S. average. Texas and Alabama have the lowest 

commercial fishing quotients in the Gulf; the concentration of the commercial fishing industry in these 

states is roughly one-third the national average. 

The DWH event has had a number of effects on the commercial fishing industry. The most direct 

manner in which the spill affects the industry is through the potential for decreased harvests of a number 

of species over the next few years. While, at this time, there exists substantial uncertainty regarding the 

range and magnitude of these effects, IEM (2010) attempts to create estimates of the economic effects of 

lower harvests on the economy of the Louisiana. This study first estimates harvest losses of certain 

species over the next 3 years. It then uses available price information to compute a range of possible 

revenue losses for the industry. It estimates that revenue losses in Louisiana could be between $115 

million and $173 million over the next 3 years. The IEM also attempts to estimate the broader economic 

implications from these potential revenue losses. Namely, losses in fishing harvests cause reduced 

revenue throughout the commercial fishing supply chain. In turn, this lower revenue reduces the income 

of workers in the commercial fishing industry, which reduces their spending on a broader range of goods 

and services. Based on this “multiplier” effect, IEM estimates that total output losses resulting from these 

effects could be between $285 million and $427 million over the next 3 years. 

The DWH event has also affected the financial condition of the workers and firms who work in the 

commercial fishing industry. A number of workers were idled during the spill and during the subsequent 

State and Federal commercial fishing bans. Some of these workers were hired by BP as part of the Vessel 

of Opportunity program. While this work led to reasonably high income to some workers, it created a 

divergence among the financial conditions between those who were hired by the program and those who 

were not (Davidson, 2010). In addition, even though some fishermen were helped by the Vessel of 

Opportunity program, businesses further up the supply chain had fewer alternative options and thus 

suffered due to the closures. Payments from BP also helped mitigate the financial damage to some 

individuals and businesses to some extent; as of November 27, 2010, $124 million in damage claims had 

been paid to individuals and $354 million had been paid to firms in the fishing industry in the GOM (Gulf 

Coast Claims Facility, 2010a). 

The long-term economic implications of the DWH event on the commercial fishing industry remain 

unclear. In part this is due to uncertainty regarding the fate of fish species in the GOM. However, it will 

also take some time to determine the speed and extent to which confidence in the seafood industry in the 

GOM will be restored. Preliminary evidence suggests that the general public became wary of consuming 

seafood from the Gulf of Mexico as the spill progressed. For example, Louisiana State University and the 

University of Minnesota conducted a nationwide survey of roughly 1,000 people to gauge the effects of 

the spill on seafood consumption. This study found that one-half of the overall population was extremely 

concerned about the effects of the spill on seafood and that a one-third of the population would curtail 

their overall seafood consumption to some extent. It is likely that confidence in the seafood industry will 

gradually return if Gulf seafood can be demonstrated to be safe. Indeed, BP has given Louisiana 

$18 million for seafood monitoring and $30 million for seafood promotion programs (World Fishing 

Network, 2010). The Federal Government also has programs in place to monitor the safety of seafood 

obtained from reopened fishing areas. Information regarding these testing programs and their findings 

can be found at the U.S. Dept. of Health and Human Services, Food and Drug Administration (2011) and 

USDOC, NOAA (2011b). These testing programs have generally found that seafood from Gulf waters is 

safe. However, Wilkinson (2011) provides a summary of some of the longer term concerns regarding the 

impacts of the oil spill on the fishing industry in the Gulf of Mexico. However, it will take some time 

before the full impacts of the oil spill, including actual fisheries impacts and the effects of perceptions on 

seafood consumption, are fully understood. 

4.1.1.17.2. Impacts of Routine Events 

Background/Introduction 

The detailed description of possible impacts on commercial fishing from routine activities associated 

with the CPA proposed action is given in Chapter 4.2.2.1.11 of the Multisale EIS and in Chapter 4.1.12.2 

of the 2009-2012 Supplemental EIS. The BOEMRE has reexamined the impacts of CPA activities on the 
4-276 Central Planning Area Supplemental EIS 

commercial fisheries resources. A search was conducted for new information published since completion 

of the Multisale EIS and the 2009-2012 Supplemental EIS. A search of Internet information sources 

(including scientific journals), as well as interviews with personnel from academic institutions and 

governmental resource agencies, was conducted to determine the availability of new information. The 

following is a summary of the information incorporated from the Multisale EIS and the 2009-2012 

Supplemental EIS, and new information that has become available since both documents were prepared. 

Direct effects on commercial fishing from routine offshore activities could result from the installation 

of production platforms, underwater OCS obstructions including pipelines, production platform removals, 

seismic surveys, and the discharge of offshore waste. 

Offshore structures can cause space-use conflicts with commercial fishing, especially with longline 

fishing. Exploratory drilling rigs cause temporary interference to commercial fishing, lasting 

approximately 30-150 days. Major production platforms present a permanent area unavailable for fishing 

that includes structures and safety zones. Underwater OCS obstructions such as pipelines can cause loss 

of trawls and catch, as well as fishing downtime and vessel damage. 

Production platform removal in water depths <200 ft (61 m) removes artificial reef habitat and often 

involves the use of explosives. This is lethal to fish that have internal air chambers (swim bladders), are 

demersal, and are in close association with the structure or are transitory in the area. Intense sounds 

generated by seismic surveys affect the spatial distribution of fish during and for some period following 

exposure. 

The most commonly discharged offshore wastes are drill mud and produced water. Drill mud 

contains metals such as mercury and cadmium, which are toxic to fishery resources. Produced water 

commonly contains brine, trace metals, hydrocarbons, organic acids, and radionuclides. Any or all of 

these constituents, in high enough concentrations, can be toxic to fish at any stage of their life cycle. 

Additionally, routine offshore activities may impact inshore commercial fisheries indirectly. These 

activities include the construction or expansion of onshore facilities in wetland areas, pipeline 

emplacement in wetland areas, vessel usage of navigation channels and access canals, maintenance of 

navigation channels, and inshore disposal of OCS-generated, petroleum-field wastes. 

Degradation of coastal water quality may indirectly impact commercial fisheries. Coastal water 

quality (discussed at length in Chapter 4.2.2.1.2.1 of the Multisale EIS and in Chapter 4.1.2.1.2 of the 

2009-2012 Supplemental EIS) may be affected adversely by saltwater intrusion and sediment 

disturbances from channel maintenance dredging, onshore pipeline emplacements, and canal widening. 

These factors potentially also affect the quality and quantity of wetlands and the quality of estuaries. 

Many commercial fish in the offshore Gulf of Mexico depend on these resources as nursery habitat. 

Trash, discharges, and runoff may be released from onshore facilities and vessel traffic, and may cause 

degradation of coastal water quality. Besides coastal sources, trash occurring in association with OCS 

operations and reaching coastal waters may impact water quality conditions. Marine environmental 

degradation resulting from routine offshore activities also has the potential to indirectly affect commercial 

fish resources by reducing food stocks in soft-bottom and reef habitats. These routine activities include 

the offshore discharge of produced water and drilling mud. 

Proposed Action Analysis 

The routine activities associated with the CPA proposed action that would impact commercial 

fisheries include installation of production platforms, underwater OCS obstructions, pipeline trenching, 

production platform removals, seismic surveys, and the discharge of offshore waste. 

The number of production structures projected as a result of the CPA proposed action range from 32 

to 44. Applying a 500-m (1,640-ft) safety zone around a platform would exclude approximately 193 ac 

(78 ha) from commercial fishing, assuming that the operator applied to USCG for a safety zone around 

the platform. The total number of platforms projected in the CPA in <200 m (656 ft), the area in which 

concentrated bottom trawling occurs, is 20-25, thus potentially excluding 1,562-1,953 ha (3,860-4,825 ac) 

or <0.01 percent from the total area available to trawling. 

Commercial fisheries conflicts with platforms in water deeper than 200 m (656 ft) are limited to the 

longline fishery. Surface-drifting longlines may contact a deepwater platform if not set an appropriate 

distance from the surface-piercing structure. The area of a surface-piercing structure is very small in 

relation to the total area available to longliners. 
Description of the Environment and Impact Analysis 4-277 

The number of kilometers of pipeline projected to be emplaced in the CPA in water depths <60 m 

(200 ft) is from 50 to 850 km (31 to 528 mi). In water depths >60 m (200 ft), the projected length of 

pipeline is unavailable. Because of pipeline burial requirements, it is assumed that installed pipelines 

would seldom conflict with bottom trawling activities in water depths <60 m (200 ft), and it would not 

conflict with commercial fishing in deeper waters. 

Structural removals in water depths <200 m (656 ft) result in a loss of artificial habitat and in fish 

mortality when explosives are used. It is projected that 20-26 removals would result in the CPA in water 

depths <200 m (656 ft) as a result of the proposed action, making approximately 1,562-2,030 ha (3,860-

5,018 ac) available again for commercial fishing. It is expected that structure removals would have a 

negligible impact on commercial fishing because of the small number of removals and the consideration 

that removals kill primarily those fish associated with the platforms or those transient in the area. 

Produced water and drill mud are discharged in shallow and deep waters of the CPA. Studies of drill 

mud and produced water from platforms show that the plume disperses rapidly in both cases and does not 

pose a threat to commercial fisheries. In a recent study of the concentrations of the bioavailable form of 

mercury (methylmercury) in drill mud, Trefry et al. (2003) found concentrations did not vary significantly 

between near-platform and far-platform sites. Further, the study suggested that elevated levels of 

methylmercury in sediments around drilling sites are not a widespread phenomenon in the Gulf of Mexico 

(Trefry et al., 2003). 

Summary and Conclusion 

Routine activities such as seismic surveys and pipeline trenching in the CPA would cause negligible 

impacts and would not deleteriously affect commercial fishing activities. Because seismic surveys are 

temporary events, they are not expected to cause long-term or permanent displacement of any listed 

species from critical/preferred habitat or to result in the destruction or adverse modification of critical 

habitat or EFH. Operations such as production platform emplacement, underwater OCS impediments, 

and explosive platform removal would cause slightly greater impacts on commercial fishing, but their 

effects are localized to a small percentage of the area fished and they are temporary in nature. 

Commercial catches by species and by State have been updated in Chapter 4.1.1.17.1, as have the 

impacts of the 2005 and 2008 hurricanes on fish and fish habitat from recent reports (USDOC, NMFS, 

2010c; Haby et al., 2009). The new information presented in this Supplemental EIS does not alter the 

conclusion presented in the Multisale EIS and the 2009-2012 Supplemental EIS that impacts on 

commercial fisheries from routine activities associated with the CPA proposed action would be minimal. 

4.1.1.17.3. Impacts of Accidental Events 

Background/Introduction 

The description of possible impacts on commercial fisheries resulting from accidental events 

associated with the CPA action is presented in detail in Chapter 4.4.10 of the Multisale EIS and in 

Chapter 4.1.12.3 of the 2009-2012 Supplemental EIS. The risk of oil-spill events as a result of the 

proposed action was discussed at length in Chapter 4.3.1 of the Multisale EIS, and the potential effects of 

a spill on commercial fisheries is detailed at length in Chapter 4.4.10 of the Multisale EIS. The following 

is a summary of the information incorporated from the Multisale EIS and the 2009-2012 Supplemental 

EIS, and new information that has become available since both documents were prepared. 

Accidental events that would impact commercial fisheries include subsurface offshore blowouts and 

oil spills, both inshore and offshore. There is a small risk of spills occurring during shore-based support 

activities. The great majority of these would be very small. Most of these incidents would occur at or 

near pipeline terminals or shore bases, and they are expected to affect a highly localized area with lowlevel impacts. 

Proposed Action Analysis 

The accidental events that would impact commercial fisheries include well blowouts, primarily gas 

well blowouts, and/or oil spills. Impacts of gas well blowouts on commercial fisheries are generally very 

localized and limited. Sediment redistribution would affect only the area within a few hundred yards of 
4-278 Central Planning Area Supplemental EIS 

the blowout. Impacts of oil or oil/gas mixture blowouts may affect commercial fisheries populations, 

depending on their exposure to the oil, the type of oil, and the time of year of the spill. Most commercial 

species are only affected if the oil reaches the shelf or the inshore estuarine waters. 

Commercial fishermen would actively avoid the area of a small spill, but they may be prevented from 

fishing by State or Federal agency closures in some areas in the case of larger spills. Fish flesh tainting 

(oily tasting fish/shellfish) and resultant area closure could decrease commercial landings, value, or catch 

in the short term. Perception of tainting of commercial catches may affect the ability of commercial 

fishermen to sell their product. 

Closure areas imposed by State or Federal agencies may also impact the commercial fisheries 

positively in the long term by easing fishing pressure on commercially (especially annually) harvested 

populations. 

The effects of the DWH event on commercial fisheries are preliminary and mostly speculative. Data 

are lacking, and it will take several years to analyze specific long-term effects of the DWH event on all 

Gulf of Mexico commercial fisheries populations. 

Blowout and Oil-Spill Impacts 

A subsurface blowout event, although highly unlikely, has the potential to affect fish within a few 

hundred feet of the blowout. A blowout at the seafloor can cause a crater that might interfere with 

longlining in the near vicinity or cause an area to be closed to longlining. A seafloor blowout could also 

result in a localized increase in suspended sediments. These sediments can clog finfish gills and interfere 

with respiration. Sediments remaining in suspension can cause interference in feeding in finfish species 

that are sight feeders. Coarse sediments such as sand-sized particles, however, fall out of the water 

column quickly, but finer sediments are redistributed by currents and settle out over a larger area. 

Oil spills may occur from blowouts; however, most product loss from blowouts is natural gas, 

primarily methane, which rapidly dissolves in the water column or escapes into the air. Recently 

published research (Kessler et al., 2011) revealed that a large amount of methane was released by the 

DWH event and, based upon the methane and oxygen distributions measured at 207 stations in the 

affected area, a large amount of oxygen was respired by methanotrophs. Kessler et al. suggest that the 

methane triggered a large methanotroph bloom that rapidly degraded the methane, leaving behind a 

residual methanotrophic community. 

Most of the commercial fish and shellfish harvested in the CPA are estuarine dependent at some point 

in their life cycles. These include brown shrimp, white shrimp, pink shrimp, blue crabs, croaker, 

sheepshead, menhaden, black drum, red drum, spotted sea trout and sand sea trout. Oysters are most 

abundant in estuarine areas. Other species such as red snapper and king mackerel are most abundant on 

the shelf. 

Oil spilled in the offshore areas is usually localized and has a very low probability of reaching shelf 

waters and coastal estuaries. Much of the oil volatilizes or is dispersed by currents in the offshore 

environment. Oil that is not volatilized, dispersed, or emulsified by dispersants, and through a 

combination of oceanographic and meteorological factors moves onto the shelf or into the estuaries and 

has the potential to affect finfish through direct ingestion of hydrocarbons or ingestion of contaminated 

prey. Hydrocarbon uptake of prey can be by dissolved petroleum products through the gills and 

epithelium of adults and juveniles, decreased survival of larvae, and death of eggs (NRC, 1985 and 

2002a). All of these mechanisms are discussed at length in Chapter 4.4.10 of the Multisale EIS. 

Actual effects of any oil that is released and comes in contact with the shelf or estuarine populations 

of commercially important species will depend on the API gravity of the oil, its ability to be metabolized 

by microorganisms, and the time of year of the spill. Effects on the populations would be at a maximum 

during the spawning season of any commercially important population, exposing larvae and juvenile to 

oil. Effects on commercial species may also include tainting of flesh or the perception of tainting in the 

market. This can, depending on the extent and duration of the spill, affect marketability of commercial 

species. 

The effects on future generations of commercial fisheries depend on the mobility of the species and 

the length of their life cycles. Sessile species such as oysters would be affected more than species with 

the ability to avoid the oil. Species with short life cycles such as shrimp and crabs are most vulnerable 

because they are essentially an annual crop. Longer-lived species such as snapper and grouper have more 
Description of the Environment and Impact Analysis 4-279 

resilience because these populations consist of multiple year classes that can breed, and the failure of any 

one year class does not necessarily threaten the survival of the population. 

Closure areas imposed by State or Federal agencies may impact the commercial fisheries of an area 

either inshore in State waters or in the EEZ by easing fishing pressure on commercially harvested 

populations. Most of these short-lived, estuarine-dependent species, such as brown and white shrimp and 

blue crabs, are harvested on an annual basis. Closure to harvest relieves the annual fishing pressure and, 

assuming no devastation of the population due to the effects of oil, may actually increase population 

levels during the period of closure. 

Recent data collected by Dauphin Island Sea Lab researchers from stations outside of the barrier 

islands and inside of the estuaries prior to and after the DWH event and resulting spill show a clear 

increase in biomass and abundance of estuarine species such as Atlantic croaker, spot, shrimp, and crabs 

(i.e., post-DWH spill). Species studied were most abundant in the estuaries (as compared with outer 

barrier island stations) both pre-and post-spill. These data also show that the ratio between the total 

abundance of shrimp and crabs to Atlantic croaker and spot exhibited a huge decrease in the ratio after the 

spill (Valentine, personal communication, 2010). Area closure may, therefore, have a positive impact on 

inshore commercial fisheries populations. 

Information on the effects of the DWH event on commercial fisheries is preliminary. Data are 

lacking and it will take several years to analyze the effects of this event on all Gulf of Mexico commercial 

fisheries populations. 

Summary and Conclusion 

The BOEMRE has reexamined the analysis for impacts to commercial fish resources presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, based on updated information obtained through the 

peer reviewed data, Internet sources, and conversations with Gulf Coast State agencies, Federal agencies, 

and professors at local academic institutions. No substantial newly published, peer-reviewed information 

was found that would alter the overall conclusion that impacts to commercial fish resources from 

accidental activities associated with the CPA proposed action would be minimal. In summary, the 

impacts of the CPA proposed action from accidental events (i.e., a well blowout or an oil spill) are 

anticipated to be minimal because the potential for oil spills is very low. 

Fish populations may be impacted by an oil-spill event should it occur, but they would be primarily 

affected if the oil reaches the productive shelf and estuarine areas. The probability of an offshore spill 

impacting these nearshore environments is also low, and oil would generally be volatilized or dispersed 

by currents in the offshore environment. Extent of the impacts of the oil would depend on the properties 

of the oil and the time of year of the event. 

Commercial fishermen are anticipated to avoid the area of a well blowout or an oil spill. Fisheries 

closures may result from a large spill event. These closures may have a negative effect on short term 

fisheries catch and/or marketability. In the long term, they may have a positive impact on annually 

harvested species because there was a decrease in fishing pressure on the stocks. 

4.1.1.17.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts on commercial fishing can be found in Chapter 4.5.11 of 

the Multisale EIS and in Chapter 4.1.12.4 of the 2009-2012 Supplemental EIS. The following is a 

summary of the information incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, 

and new information that has become available since both documents were prepared. This information 

has been gathered from referenced journals, government agency publications, conversations with 

government resource agency employees, and the Internet. 

Specific types of impact-producing factors considered in the cumulative analysis include the 

following: (1) commercial fishing techniques or practices; (2) hurricanes; (3) installation of production 

platforms and underwater OCS obstructions; (4) production platform removals; (5) seismic surveys; (6) 

petroleum spills; (7) subsurface blowouts; (8) pipeline trenching; and (9) offshore discharges of drilling 

mud and produced waters. 
4-280 Central Planning Area Supplemental EIS 

Commercial Fishing Practices 

There is competition among large numbers of commercial fishermen, among commercial operations 

employing different fishing methods, and between commercial and recreational fishermen for a given 

fishery resource. That competition, coupled with natural phenomena such as hurricanes, hypoxia, and red 

or brown tides, can impact commercial fishing activities. When practiced nonselectively, fishing 

techniques such as trawling, gill netting, or purse seining may reduce the standing stocks of the desired 

target species. This can also significantly affect species other than the target. In addition, continued 

fishing of most commercial species at the present levels can result in rapid declines in the landings and 

the eventual failure of certain fisheries. 

Hurricanes 

Hurricanes may impact commercial fishing by damaging gear and shore facilities and by dispersing 

resources over a wide geographic area. Hurricanes may also affect the availability and price of key 

supplies and services (e.g., fuel) that also affect commercial fishing. Hurricanes suspend fishing activity 

and are destructive to wetlands that act as nursery grounds to many commercial fish. Hurricanes can be 

extremely destructive to oyster beds by causing siltation over the beds and smothering spat along with 

adult oysters, as evidenced by Hurricanes Katrina, Rita, Gustav, and Ike. Commercial fisheries landings 

of the central Gulf Coast were drastically impacted by Hurricanes Katrina and Rita in 2005 as a result of 

the severe impact on coastal port facilities and fishing vessels. These data are discussed in detail in 

Chapter 3.3.1 of the Multisale EIS. Equally as destructive were Hurricanes Gustav and Ike in 2008, as 

discussed in Chapter 3.3.7.2 of this Supplemental EIS. These impacts were so severe that Commerce 

Secretary Gutierrez determined a fisheries resource disaster as a result (Upton, 2010). However, natural 

disaster impacts such as these are easily distinguished from incremental impacts of OCS activities. 

Installation of Production Platforms and Underwater Obstructions 

The CPA proposed action is anticipated to result in the installation of 32-44 new production facilities 

(Table 3-2). These productions facilities compete with commercial fishing interests for physical space in 

the open ocean. The facilities can also be associated with underwater OCS obstructions that pose hazards 

to fishing nets. These facilities are also known fish attracting devices, so fish often congregate around 

them for food and shelter from predators. The area occupied by these structures is small compared with 

the area available in the CPA for fishing. Because the area is small, the cumulative impact of the CPA 

proposed action to the commercial fisheries of the CPA is anticipated to be small. 

Platform Removals 

Offsetting the anticipated installation of platforms in the CPA is the anticipated removal of 30-42 

existing platforms (Table 3-2). The removal of these platforms not only frees the area for commercial 

fishing but also removes them as fish attracting devices. There is the possibility the structures can be 

used in a rigs-to-reef program where they would serve as artificial habitat for fish. Of those estimated to 

be removed, 23-32 are anticipated to be removed using explosives (Table 3-2). Explosives do cause 

mortality in fish with swim bladders when they are either associated with the platform or transient in the 

area at the time of the explosions. Because the number of platform removals is small, the effects on 

commercial fishery populations are expected to be minimal. 

Seismic Surveys 

Seismic surveys are used in both shallow- and deepwater areas of the Gulf of Mexico. Although it 

has been alleged that catch rates are lower after seismic surveys, fishermen are usually precluded from the 

area for several days. This should not significantly affect the annual landings or the value of landings for 

commercial fisheries because Gulf of Mexico species are found in many adjacent locations and Gulf 

commercial fishermen do not fish in one locale. 
Description of the Environment and Impact Analysis 4-281 

Petroleum Spills 

The potential causes, sizes, and probabilities of petroleum spills that could occur during activities 

associated with the CPA proposed action are discussed in detail in Chapter 3.2.1. One large (≥1,000 bbl) 

offshore spill is estimated to occur annually from all sources Gulfwide (Chapter 4.3.1.5.1 of the Multisale 

EIS). Large spills can potentially affect commercial fisheries resources by causing potential losses to 

commercial fish populations. These potential population losses may be offset by commercial fisheries 

closure areas necessitated by a large spill. The effects of a catastrophic spill such as the DWH event, 

although based on limited data at this time, are discussed in Appendix B. Although the effects can be 

significant from any one spill, the overall probability of a large spill occurring is still low. 

The majority of coastal spills in the Gulf (90%) are expected to be small (<1 bbl) and to cause a 

minimal decrease in commercial fishing local to the spill area. Because these spills are small, the 

resultant influence on commercial fishing, landings, or the value of those landings is not expected to be 

distinguishable from natural population variations. 

Subsurface Blowouts 

Subsurface blowouts of both oil and natural gas wells and pipeline trenching have the potential to 

adversely affect commercial fishery resources. The loss of well control and resultant blowouts seldom 

occur in the Gulf OCS over a 40-year time period (169-197 blowouts out of 28,191-32,832 wells drilled; 

i.e., <1%) (Table 4-6 of the Multisale EIS). Sandy sediments are quickly redeposited within 400 m 

(1,312 ft) of a blowout site, and finer sediments are widely dispersed and redeposited within a few 

thousand meters or feet over a period of 30 days or longer. These events are expected to have a negligible 

impact on fish populations. It is expected that the infrequent subsurface natural gas blowout that can 

occur on the Gulf of Mexico OCS would have a negligible effect on commercial fish resources. 

Subsurface blowouts, such as the DWH event, that include both oil and natural gas have the potential 

to affect fish populations particularly eggs, larvae, and juveniles. The specific effects of this type of spill 

on individual fish populations in the Gulf of Mexico are currently unknown, and spills of this type are a 

low-probability event. Because these spills are a low-probability event, the contribution to the cumulative 

impact on commercial fisheries populations is not expected to be large as a result of the CPA proposed 

action. 

Pipeline Trenching 

Pipeline trenching also has the potential to affect commercial fisheries as a result of sediment 

suspension. Sandy sediments from either source are quickly redeposited within 400 m (1,312 ft) of the 

trench, and finer sediments are widely dispersed and redeposited over a period of hours to days within a 

few thousand meters of the event. No significant effects to commercial fisheries are anticipated as a 

result of oil or gas well blowouts or pipeline trenching. Resuspension of vast amounts of sediments as a 

result of large storms and hurricanes occurs on a regular basis in the northern Gulf of Mexico (<50 m; 

164 ft) (Hu and Muller-Karger, 2007). In many areas of the Gulf of Mexico, sediments are not static 

under natural conditions, as evidenced by the recently discovered deep-sea furrows (Bryant et al., 2004). 

The cumulative effect on commercial fisheries from oil and gas well blowouts in the Gulf OCS and 

pipeline trenching is not expected to be distinguishable from natural events or natural population 

variations. 

Offshore Discharge of Drilling Mud and Produced Waters 

Drilling mud discharges contain chemicals toxic to marine fishes, including brine, hydrocarbons, 

radionuclides, and metals. These concentrations are many orders of magnitude higher than those found 

more than a few meters or feet from the discharge point. Offshore discharges of drilling mud dilute to 

near background levels within 1,000 m (3,281 ft) of the discharge point and would have a negligible 

cumulative effect on fisheries. 

Produced-water discharges contain components and properties detrimental to commercial fishery 

resources. Offshore discharges of produced water also disperses and dilutes to near background levels 

within 1,000 m (3,281 ft) of the discharge point and have a negligible cumulative effect on fisheries. 
4-282 Central Planning Area Supplemental EIS 

Offshore live bottoms would not be impacted. Offshore discharges and subsequent changes to marine 

water quality are regulated by USEPA NPDES permits. 

Biomagnification of mercury in large fish of higher trophic levels is a problem in the Gulf of Mexico. 

In the press, this biomagnification is often associated with drilling discharges, but the bioavailability and 

any association with trace concentrations of mercury in discharged drilling mud has not been 

demonstrated. Numerous studies have concluded that platforms do not contribute to higher mercury 

levels in marine organisms. Recent data suggest that mercury in sediments near drilling platforms is not 

in a bioavailable form. 

The input of drilling mud and produced waters are limited and are diluted very quickly in the marine 

environment. Their environmental effects are, therefore, expected to be limited. 

Summary and Conclusion 

Activities resulting from the OCS Program and non-OCS events have the potential to cause limited 

detrimental effects to commercial fishing, landings, and the value of those landings. The impactproducing factors of the cumulative scenario that are expected to substantially affect commercial fishing 

include commercial fishing techniques or practices, hurricanes, installation of production platforms and 

underwater OCS obstructions, production platform removals, seismic surveys, petroleum spills, 

subsurface blowouts, pipeline trenching, and offshore discharges of drilling mud and produced waters. 

Recent substantial impacts occurred to commercial fisheries because of the 2005 and 2008 hurricanes. 

At the estimated level of cumulative impact, the resultant influence on commercial fishing, landings, and 

the value of those landings is expected to be substantial and easily distinguished from effects due to 

natural population variations. The effects of impact-producing factors (e.g., installation of production 

platforms, underwater OCS obstructions, production platform removals, seismic surveys, oil spills, 

subsurface blowouts, pipeline trenching, and offshore discharges of drilling mud and produced waters) 

related to the CPA proposed action are expected to be negligible and indiscernible from natural fishery 

population variability. This is because the installation of production platforms and underwater OCS 

obstructions in the area is small, the number of platform removals is small, seismic surveys are 

temporary, oil spills are vernally small scale, blowouts have a small probability, and trenching and 

discharges are highly regulated. The impacts of a catastrophic oil spill, such as the DWH event recently 

experienced in the Gulf of Mexico, based on limited data now available, are discussed in Appendix B. 

4.1.1.18. Recreational Fishing 

The BOEMRE has reexamined the analysis for recreational fishing presented in the Multisale EIS and 

the 2009-2012 Supplemental EIS, based on the additional information presented below and in 

consideration of the DWH event. While the DWH event had some impacts on recreational fishing 

activity, the fact that the spill was a low-probability event leads the conclusions reached in the Multisale 

EIS and the 2009-2012 Supplemental EIS to be largely unchanged. Namely, the CPA proposed action 

could cause minor space-use conflicts and could have minor effects on fish populations that support 

recreational fishing activity. However, routine OCS activities can also enhance recreational fishing 

opportunities since oil platforms serve as artificial reefs for fish habitats. Small to medium spills are 

unlikely to significantly impact recreational fishing activity due to the short-term duration of their impacts 

and the likely availability of substitute fishing sites in a particular region. A large spill such as the DWH 

event can have more noticeable impacts to recreational fishing activity, as well as to individuals and firms 

that depend on angler spending. However, these effects can be mitigated to some extent through financial 

compensation and through policies of Federal and State fisheries management agencies. The CPA 

proposed action should not have large effects on recreational fishing activity since it does not 

significantly increase the likelihood of an additional spill along the lines of the DWH event. 

4.1.1.18.1. Description of the Affected Environment 

A detailed description of recreational fishing can be found in Chapter 3.3.3 of the Multisale EIS. 

Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.14 of the 2009-2012 Supplemental EIS. The following 

information is a summary of the description of recreational fishing incorporated from the Multisale EIS, 
Description of the Environment and Impact Analysis 4-283 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

The proposed CPA lease sale has the potential to impact a number of recreational fishing areas in the 

Gulf of Mexico. This section discusses the baseline environment for recreational fishing along the coasts 

of Louisiana, Mississippi, Alabama, and Florida; the baseline environment for recreational fishing along 

the coast of Texas is described in Chapter 4.1.1.15.1. Data on effort and catch levels for the most often 

fished species is discussed first. This is followed by a description of the interaction between recreational 

fishing activity and the broader economy of the region. Finally, an analysis of the effects of the DWH 

event on the recreational fishing industry is presented. While there is some evidence regarding the 

impacts of the oil spill on recent recreational fishing activity, a fair amount of uncertainty remains 

regarding the shape this industry will take as the impacts of the oil spill gradually recede. 

Catch and Effort Data 

Table 4-9 presents data on the most commonly landed species by recreational fishermen in Louisiana, 

Mississippi, Alabama, and Florida. These data, along with the majority of the other data presented, 

comes from the NMFS online database. Table 4-9 presents the total number of fish caught and the total 

landings weight of certain fish species from 2001 through 2009 in these four states. In 2009, the most 

number of fish landings occurred for spotted seatrout, pinfish, red drum, sand seatrout, Atlantic croaker, 

and gray snapper. The species with the most total pounds landed in 2009 were spotted seatrout, red drum, 

sheepshead, red snapper, king mackerel, and black drum. The number of landings for most species has 

been somewhat stable over time. However, landings of species such as sand seatrout and Atlantic croaker 

have shown an uptrend in recent years, while landings of species such as striped mullet and cobia have 

exhibited a general downtrend. Table 4-10 shows the percent of the catch in Table 4-9 that occurred in 

ocean versus inland waters. As expected, these percentages are highly species dependent, ranging from 

almost 100 percent ocean-landed for dolphins and blackfin tuna to less than 10 percent for southern 

flounder and black drum. This information is particularly relevant in light of the DHW event, which 

appears to have had a more pronounced effect on ocean-based recreational fishing. 

Table 4-11 presents data from two sources regarding angler participation in the Gulf of Mexico. 

Panel A presents data from NMFS and shows the total number of anglers in 2009 for each of the Gulf 

States in three categories: coastal; noncoastal; and out-of state. Coastal refers to anglers who are State 

residents of coastal counties, noncoastal refers to anglers who are State residents of noncoastal counties, 

and out-of-state refers to out-of-state residents. Florida has the largest number of recreational fishing 

participants. Florida’s approximately 6 million anglers accounted for 78 percent of participants among 

the four Gulf States that participated in the surveys by NMFS. Louisiana has the second highest number 

of participants, followed by Alabama and Mississippi, respectively. Florida also has the highest 

percentage of out-of-state anglers, and Louisiana has the highest percentage of in-state anglers. Panel B 

presents participation data from the National Survey of Fishing, Hunting, and Wildlife Associated 

Recreation. The scales of the findings are reasonably similar, although the differences are certainly not 

negligible; other than different survey years, the causes of these discrepancies are not immediately clear. 

The National Survey of Fishing, Hunting, and Wildlife Associated Recreation occurred in 2006. 

Table 4-12 presents data on the number of angler trips taken in each state in the Gulf of Mexico in 

2009. Angler trips in West Florida accounted for approximately 70 percent of the 22 million trips in the 

Gulf of Mexico. There were approximately 4 million trips in Louisiana, 1.7 million trips in Alabama, and 

1.1 million trips in Mississippi. Table 4-13 also breaks down these trips by location and mode. The three 

geographic locations for each state are inland, State ocean waters (less than 3 mi [5 km] from shore), and 

Federal ocean waters (more than 3 mi [5 km] from shore). The three modes of fishing are shore fishing, 

charter fishing, and private/rental fishing. Approximately 67 percent of all recreational fishing trips in the 

Gulf of Mexico are conducted inland; fishing in State ocean waters accounts for approximately 27 percent 

of angler trips; and fishing in Federal ocean waters accounts for approximately 6 percent of the trips. 

Ocean fishing is more prevalent in Alabama and West Florida, which comprise approximately 40 percent 

of the total number of trips in each State. Offshore fishing only accounts for about 5 percent of trips in 

both Mississippi and Louisiana. The bulk of ocean fishing in the Gulf of Mexico is conducted through 

either shore fishing (37%) or private rentals (59%). Charter fishing accounts for less than 5 percent of the 

total number of angler trips. 
4-284 Central Planning Area Supplemental EIS 

Economic Effects of the Recreational Fishing Industry 

Recreational fishing activity can affect a regional economy in a number of ways. The most direct 

manner in which anglers affect the economy is through direct spending on fishing-related goods and 

services. This direct spending includes both trip expenditures and expenditures on durable equipment. 

Trip expenditures include such things as transportation costs, boat fees, and bait expenses. Durable 

purchases include spending on things such as fishing equipment and fishing boats. Table 4-14 presents 

data on total direct spending by anglers in each state along the Gulf of Mexico. There was approximately 

$12.5 billion in direct spending by anglers in 2008; roughly half of this spending occurred in West 

Florida. Louisiana and Texas each had over $2.5 billion in spending, while Alabama and Mississippi 

each had over $400 million in spending. 

Direct spending by fishermen also supports firms in related industries along an economy’s supply 

chain. In addition, spending by fishermen serves as income to other agents in an economy, which 

supports overall spending patterns. The NMFS conducted an economic analysis that attempted to 

quantify this dependence of the regional economy on recreational fishing activity (USDOC, NMFS, 

2010d and 2010e); this analysis utilizes many of the techniques of an earlier study by Gentner and 

Steinbeck (2008). These studies utilize input-output economic models, which create multipliers that can 

be used to predict levels of sales, value added, and jobs that result from direct spending on recreational 

fishing. As can be seen in Table 4-14, direct spending by anglers supported approximately $12 billion in 

sales. One reason that sales are lower than spending is that only spending on newly produced goods 

contributes to economic activity (i.e., sales of used equipment does not). In addition, some spending that 

occurs by anglers would likely be replaced by spending by others if angler spending levels were to 

change. These sales contributed to $6 billion in value added in the economy. While the sales data 

aggregates spending at different stages of production, value added only includes the incremental 

production at each level in the supply chain. Finally, it is estimated that spending by anglers supports 

over 87,000 jobs in Louisiana, Mississippi, Alabama, and Florida. 

Deepwater Horizon Event 

Previous sections describe the baseline environment for recreational fishing in the Gulf of Mexico 

prior to the DWH event. The most direct impact of the spill on fisheries was to close a number of fishing 

grounds in or near the oil-impacted areas. At the peak of its impact in June 2010, the oil spill led to the 

closure of 36.6 percent of the fishing waters in the Gulf of Mexico; this percentage fell dramatically by 

mid-November to less than 1 percent. The NMFS continued to conduct angler surveys as the spill 

progressed. These data are presented in 2-month “waves” and thus provide a picture of the evolving state 

of recreational fishing in the Gulf of Mexico. Table 4-12 presents data on the number of angler trips in 

each Gulf State for inland, State, and Federal waters in 2010; data for comparable months in 2009 are also 

presented. Prior to the DWH event, recreational fishing activity in the Gulf of Mexico was occurring at a 

pace that was slightly below the same time period the year before. After the spill, total angler activity did 

generally fall; however, this decrease in aggregate activity was not overly pronounced. This result is 

largely due to the fact that the majority of recreational fishing is conducted inland. Inland fishing did fall 

noticeably in May and June 2010 when compared with 2009, but by July and August 2010, inland fishing 

had recovered to a level of activity that was actually higher than in 2009. Angler trips in State ocean 

waters fell dramatically in Louisiana, while State ocean trips in Alabama and Florida were only modestly 

impacted. The effects of the spill were most pronounced Federal waters; for example, angler trips in 

Alabama fell from around 65,000 in July/August 2009 to only a few hundred in July/August 2010. 

Federal water angler trips also fell noticeably in Louisiana, although trips prior to the spill also seemed to 

be running at a below trend rate. Table 4-15 presents data on the species of fish caught for the same time 

periods as were presented in Table 4-12 in order to provide an initial sense of the impacts of the spill on 

individual species. Landings for most species in the Gulf of Mexico fell only modestly after the oil spill. 

Species landings that fell more significantly include gray snapper, red snapper, and red grouper. 

While the previous data provide a useful picture of recreational activity as the spill progressed, there 

is more uncertainty regarding the long-term implications of the oil spill on recreational fishing. The most 

important determinant of the longer-term effects of the spill will be the manner in which the fish 

ecosystems in the Gulf of Mexico evolve in response to the spill. IEM (2010) provides an overview of 

the factors that determine the extent to which some fish species will be able to adapt to the spill. 
Description of the Environment and Impact Analysis 4-285 

However, one factor that makes these issues hard to gauge at this point is that, for many species, oil is 

more damaging to eggs and larvae than to adults. Thus, even if recreational fishing activity is maintained 

in the near term, it will take some time to observe if, and to what degree, the reproductive cycle of 

particular species has been impacted. 

Impacts to the recreational fishing industry will also be determined by the ability of the people and 

firms in the industry to weather the current conditions. Fishing closures occurred during a normally 

strong period for recreational fishing. In addition, many firms that cater to recreational fishing are small 

and may lack the ability to weather the resulting lack of business. IEM (2010) presents some survey 

results regarding the effects of the spill on local fishermen. While a number of fishermen in affected 

areas were idled directly after the spill, Louisiana officials opened a number of areas to recreational 

fishing in mid-July 2010 (Federal Reserve Bank of Atlanta, 2010). In addition, a number of people were 

supported short term by BP claims and by the Vessels of Opportunity Program. For example, businesses 

and individuals in the fishing industry have received approximately $500 million in compensation 

payments as of November 2010 (Gulf Coast Claims Facility, 2010a). 

The fate of the recreational fishing industry will also depend on the extent to which confidence can be 

restored in the tourism and seafood industries along the Gulf Coast. This is a particularly hard issue to 

quantify at this point, in part because this issue will be determined by the success of government policy 

initiatives. For example, Louisiana will receive $78 million from BP to monitor seafood and to promote 

tourism. Thus, while a number of fishermen and businesses catering to them have been financially 

damaged by the spill, it appears that, if long-term impacts to recreational fishing do result from the DWH 

event, they will primarily be determined by the extent to which the fish ecosystems in the Gulf of Mexico 

are able to adapt to the spill over time. 

4.1.1.18.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the impacts of routine activities on recreational fishing can be found in 

Chapter 4.2.1.1.10 of the Multisale EIS. Additional information for the 181 South Area and any new 

information since the publication of the Multisale EIS is presented in Chapter 4.1.13 of the 2009-2012 

Supplemental EIS. The following information is a summary of the description of recreational fishing 

incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

Many of the species fished by recreational anglers are the same as those caught by commercial 

fishermen; one exception is menhaden, which is primarily a commercially fished species. The effects of 

routine OCS activities on commercial fishing are discussed in Chapter 4.1.1.17.2. Routine OCS actions 

can cause some minor disturbances to the fish populations that support recreational fishing activity. For 

example, OCS activity could cause coastal environmental degradation either through effects on water 

quality or on wetland habitat. The effects of OCS actions on essential fish habitat are discussed in more 

detail in Chapter 4.1.1.16.2. In addition, construction operations and vessel traffic could cause some 

degree of space-use conflict with recreational fishing vessels. However, these impacts are likely to be 

short lived and small in scale. 

A unique manner in which OCS actions can increase recreational fishing activity is through the role 

of oil platforms as artificial reefs. Indeed, oil platforms often attract a large fish population due to their 

particular suitability as reef structures. The Atlantic and Gulf States Marine Fisheries Commissions 

provide a guidebook that compares the relative suitability of various materials for use as artificial reefs 

(Atlantic and Gulf States Marine Fisheries Commissions, 2004). Hiett and Milon (2002) estimate that 

over 20 percent of all recreational fishing activity in the Gulf of Mexico occurs within 300 ft (91 m) of an 

oil and gas structure. The role of oil rigs as artificial reefs becomes a particularly important issue during 

the decommissioning stage. Namely, the removal of an oil rig from a particular site has the potential to 

damage the fish assemblages that often develops on an oil rig, which would also affect recreational 

fishing activity in a particular area. However, the owner of an oil rig has the option to participate in the 

“rigs-to-reefs” program of the appropriate State. These programs allow for portions of oil platforms to 

remain in the water as reefs after the productive life of a platform has ended. Platforms that are a part of 

these programs are either toppled in place or moved to a location that is a suitable fish habitat. Rigs-toreefs programs are discussed in more detail in Appendix D of the Multisale EIS. The U.S. policy towards 
4-286 Central Planning Area Supplemental EIS 

artificial reef creation is outlined in the National Artificial Reef Plan: Guidelines for Siting, Construction, 

Development, and Assessment of Artificial Reefs (USDOC, NOAA, 2007). This Agency’s policy 

regarding rigs-to-reefs programs is outlined in Rigs-to-Reefs Policy, Progress, and Perspective

(Dauterive, 2000) and was updated in Rigs to Reefs Policy Addendum: Enhanced Reviewing and 

Approval Guidelines in Response to the Post-Hurricane Katrina Regulatory Environment (USDOI, 

MMS, 2009d) in light of Hurricane Katrina. 

Proposed Action Analysis 

The CPA proposed action would lead to 32-44 oil and gas production structures. This could lead to 

minor space-use conflicts with recreational fishermen, primarily during the construction phase. The 

proposed action could also lead to some forms of environmental degradation that could affect fish 

populations, which would impact recreational fishing activity; these effects are discussed in more detail in 

Chapter 4.1.1.16.2. However, these effects are expected to be minimal, particularly given the small scale 

of the proposed action relative to the existing OCS oil and gas program. 

The extent to which the proposed oil platforms would support recreational fishing activity would 

depend on their location. For example, oil rigs very far offshore are less likely to support recreational 

fishing activity. In addition, the extent to which a rig would serve as an attractor to fish would depend on 

the fish populations in nearby areas. Essential fish habitat maps of the Gulf of Mexico can be found on 

the Internet website of the Galveston Laboratory of NOAA Fisheries Service. Maps of artificial reef 

locations in Louisiana (Louisiana Dept. of Wildlife and Fisheries, 2010b), Mississippi (Mississippi Dept. 

of Marine Resources, 2010a), and Alabama (Alabama Dept. of Conservation and National Resources, 

2010a) are also available. 

Summary and Conclusion 

There could be minor and short-term space-use conflicts with recreational fishermen during the initial 

phases of the CPA proposed action. The proposed action could also lead to low-level environmental 

degradation of fish habitat (Chapter 4.1.1.16.2), which would also negatively impact recreational fishing 

activity. However, these minor negative effects would likely be outweighed by the beneficial role that oil 

rigs serve as artificial reefs for fish populations. Each structure placed during the CPA proposed action 

has the potential to function as a de facto artificial reef. The degree to which oil platforms would become 

a part of a particular State’s rigs-to-reefs program would be an important determinant of the degree to 

which the proposed action would impact recreational fishing activity in the long term. 

4.1.1.18.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of the impacts of accidental events on recreational fishing can be found in 

Chapter 4.4.11 of the Multisale EIS. Additional information for the 181 South Area and any new 

information since the publication of the Multisale EIS is presented in Chapter 4.1.13 of the 2009-2012 

Supplemental EIS. The following information is a summary of the description of recreational fishing 

incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

The most direct manner in which oil spills and other accidental events would impact recreational 

fishing activity would be through their effects on fish habitats in the area impacted by the spill. A spill 

could either contaminate fish in the immediate area or cause fish to move during the duration of the spill. 

A spill would likely cause more direct harm to larvae and eggs than adults, which could affect 

recreational fishing in the longer term. The effects of accidental events on essential fish habitats are 

discussed in Chapter 4.1.1.16.3. The fish species most important to recreational fishing in certain 

regions are discussed in Chapter 4.1.1.18.1. A number of these species are similar to the species that are 

important to the commercial fishing industry; the effects of accidental effects on commercial fishing are 

described in Chapter 4.1.1.17.3. The majority of recreational fishing in the Gulf of Mexico occurs in the 

bays and wetlands areas along the Gulf Coast; the impacts of accidental events on wetland areas are 

described in Chapter 4.1.1.4.3. 
Description of the Environment and Impact Analysis 4-287 

The effects of an oil spill on recreational fishing are different from those experienced by the 

commercial fishing industry in several ways. Most directly, the benefits received by anglers from fishing 

activity are determined by subtle issues such as the enjoyment of the fishing process and the aesthetics of 

a particular fishing site. As a result, the damage of an oil spill to recreational fishing will be determined 

by issues such as the availability of substitute fishing sites in a region and the additional costs of attending 

alternate sites. These effects are most often analyzed using a variety of mathematical modeling 

techniques; an overview of these techniques is presented by the NRC (2006) and the European Inland 

Fisheries Advisory Commission (2010). Haab et al. (2000 and 2009) and Greene et al. (1997) are 

examples of applications of these methods to fisheries in the Gulf of Mexico. The Exxon Valdez spill was 

an example of a spill that occurred in an area with a large recreational fishing industry. Carson and 

Hanemann (1992) provide an economic analysis of the direct recreational fishing losses due to the spill; 

Mills (1992) provides a more descriptive analysis of the evolution of recreational fishing activity 

following the spill. 

Any disruption to recreational fishing activity would also have broader economic implications to a 

particular geographic region. Disruptions to recreational fishing would affect boat launches, bait shops, 

and durable fishing equipment manufacturers. Gentner Consulting Group (2010) attempts to quantify the 

potential losses to State economies due to recreational fishing closures in light of the DWH event. This 

study uses the expenditure estimates and input output modeling framework of Gentner and Steinbeck 

(2008) to derive a daily measure of the potential losses in the economy due to fishing closures in the Gulf 

of Mexico. This study estimates that the recreational fishing industry contributes $9.8 million in direct 

expenditures, $23 million in total sales, and 183 jobs per day to the economy of the Gulf of Mexico. One 

can estimate the cost of a spill by restricting these estimates to a particular region and then multiplying the 

daily estimates by the total duration of a fishing closure brought about by an oil spill. It is also possible 

that an oil spill’s effects on the recreational fishing industry could have broader effects on tourism. 

Namely, the loss of recreational fishing options at certain locations could dissuade visitors from taking 

trips to an overall area. Similarly, recreational fishing may suffer in areas not directly affected by oil due 

to uncertainty or to misperceptions regarding the extent of the oil damage. While these effects are 

difficult to quantify, the U.S. House of Representatives (2010) provides a descriptive overview of the 

tourism effects felt during the DWH event. 

Proposed Action Analysis 

The CPA proposed action would result in 149-263 producing oil wells, 144-237 producing gas wells, 

and 32-44 installed production platforms (Table 3-2). A spill at one of these sites would likely lead to 

recreational fishing closures in the immediate vicinity in the short term. Since oil rigs often are habitats 

for certain fish species, there could be noticeable impacts to the fish ecosystem in the area of the spill. In 

general, oil spills that are closer to shore would have greater impacts on recreational fishing activity. As 

can be seen in Tables 4-9 and 4-15, spotted seatrout, pinfish, red drum, sand seatrout, and Atlantic 

croaker, which are primarily caught in nearshore waters, are the most often caught fish species by anglers. 

A spill farther from shore would have more of an impact on species such as king mackerel and red 

snapper. Maps of fish habitats in the Gulf of Mexico that could be impacted by an oil spill can be found 

on the Internet website of the Galveston Laboratory of NOAA Fisheries Service and on NOAA’s ERMA 

website (USDOC, NOAA, 2010f). 

Summary and Conclusion 

An oil spill would likely lead to recreational fishing closures in the vicinity of the oil spill. Smallscale spills should not affect recreational fishing to a large degree due to the likely availability of 

substitute fishing sites in neighboring regions. A rare large spill such as the one associated with the DWH 

event can have more noticeable effects because of the larger potential closure regions and because of the 

wider economic implications such closures can have. However, the longer-term implications of a large 

oil spill would primarily depend on the extent to which fish ecosystems recover after the spill has been 

cleaned. Because offshore spills have a small probability of contacting estuarine habitats that serve as 

nurseries for many recreational species and because inshore spills would have localized impacts to an 

area, oil spills would have a small effect on recreational fisheries. 
4-288 Central Planning Area Supplemental EIS 

4.1.1.18.4. Cumulative Impacts 

Background/Introduction 

A detailed description of the cumulative impacts to recreational fishing can be found in Chapter 

4.5.12 of the Multisale EIS. Additional information for the 181 South Area and any new information 

since the publication of the Multisale EIS is presented in Chapter 4.1.13.4 of the 2009-2012 Supplemental 

EIS. The following information is a summary of the description of recreational fishing incorporated from 

the Multisale EIS, the 2009-2012 Supplemental EIS, and new information that has become available since 

both documents were prepared. 

The cumulative impacts to recreational fishing activity from the CPA proposed action would arise 

from the existing 5-Year Program and from the expected progression of the recreational fishing industry 

in the Gulf of Mexico. These impacts are from the cumulative effects on fish resources in the Gulf of 

Mexico, which are discussed in Chapter 4.1.1.16.4. This chapter discusses the cumulative impacts of 

wetland loss, marine/estuary water quality degradation, damage to live bottoms, structure removals, 

petroleum spills, subsurface blowouts, pipeline trenching, and discharges of drilling mud and processed 

waters on fish resources. Because many of the recreationally sought fishes are also harvested 

commercially, a number of the cumulative impacts of the recreational fishing industry are similar to those 

of the commercial fishing industry. This is true even though recreational fishing is primarily confined to 

smaller, closer inshore areas of the Gulf of Mexico than commercial fishing. Chapter 4.1.1.17.4 outlines 

the cumulative impacts of commercial fishing practices, hurricanes, installation of production and 

underwater obstructions, platform removals, seismic surveys, petroleum spills, subsurface blowouts, 

pipeline trenching, and the offshore discharge of drilling mud and produced waters on commercial 

fishing. The cumulative impacts unique to recreational fishing activity will arise from State and Federal 

fisheries management plans, the role of oil platforms as artificial reefs, and the lingering impacts of the 

DWH event. 

State and Federal Fisheries Management Plans 

The CPA proposed action could have cumulative impacts to the extent to which it alters or interacts 

with State and Federal Fisheries Management Plans. Recreational fishing activity is highly regulated, 

primarily to ensure a sustainable fisheries population through time. This often takes the form of catch 

limits per trip and quotas for overall catch per species during a given season. Recreational fishing activity 

in Federal waters is governed by the GMFMC; their most recent policies are outlined in Recreational 

Fishing Regulations for Gulf of Mexico Federal Waters (GMFMC, 2011). Each State has its own 

guidelines for recreational fishing in State waters. The following websites are where the State fisheries 

policies can be found: Louisiana Dept. of Wildlife and Fisheries (2010c); Mississippi Dept. of Marine 

Resources (2010b); Alabama Dept. of Conservation and Natural Resources (2010b); and Florida Fish and 

Wildlife Conservation Commission (2010c). Federal Fisheries Management Plans could exacerbate the 

impacts of OCS actions if both were to impact certain species or fishing sites. However, fisheries 

management plans could also serve to mitigate the effects of an oil spill since these plans are often 

designed to maintain stable fishing activity. For example, the GMFMC allowed for a supplemental red 

snapper season in October 2010 since red snapper catch was unusually low during the DWH event 

(GMFMC, 2010b). This supplemental red snapper season was designed to allow the 2010 quota for red 

snapper catch to be reached. 

Rigs-to-Reefs and Artificial Reef Development 

Oil and gas platforms constructed as a result of the CPA proposed action would contribute to the 

important role of existing OCS platforms and serve as artificial reefs for fish habitats. Platforms often 

attract a large fish population due to their particular suitability as reef structures. Hiett and Milon (2002) 

estimate that over 20 percent of all recreational fishing activity in the Gulf of Mexico occurs within 300 ft 

(91 m) of an oil and gas structure. 

The role of oil rigs as artificial reefs becomes a particularly important issue during the 

decommissioning stage. Namely, the removal of an oil rig from a particular site has the potential to 

damage the fish assemblages that often develop at an oil rig, and this would also affect recreational 
Description of the Environment and Impact Analysis 4-289 

fishing activity in the area. However, the owner of an oil rig has the option to participate in the “rigs-toreefs” program of the appropriate State. These programs allow for portions of oil platforms to remain in 

the water as reefs after the productive life of a platform has ended. Platforms that are a part of these 

programs are either toppled in place or moved to a location that is a suitable fish habitat. Rigs-to-reefs 

programs are discussed in more detail in Appendix A.4 of the Multisale EIS. The U.S. policy towards 

artificial reef creation is outlined in the National Artificial Reef Plan: Guidelines for Siting, Construction, 

Development, and Assessment of Artificial Reefs (USDOC, NOAA, 2007). This Agency’s policy 

regarding rigs-to-reefs programs is outlined in Rigs-to-Reefs Policy, Progress, and Perspective

(Dauterive, 2000) and was updated in Rigs to Reefs Policy Addendum: Enhanced Reviewing and 

Approval Guidelines in Response to the Post-Hurricane Katrina Regulatory Environment (USDOI, 

MMS, 2009d) in light of Hurricane Katrina. Maps of artificial reef locations in Louisiana (Louisiana 

Dept. of Wildlife and Fisheries, 2010b), Mississippi (Mississippi Dept. of Marine Resources, 2010a), and 

Alabama (Alabama Dept. of Conservation and National Resources, 2010a) are also available. 

Deepwater Horizon Event 

The DWH event may heighten the sensitivity of recreational fishing activity in the CPA to additional 

oil spills during the next several years. This is partly due to the fact that fish populations are still 

responding to the spill and the ultimate long-term outcomes are not yet clear. This is also due to the 

complex manner in which recreational fishing activity and tourism interact. Namely, recreational fishing 

activity is one of a number of factors that draw tourists to a particular region. The high level of national 

attention focused onto the DHW suggests that future oil spills, even if smaller in scale, could raise greater 

concerns regarding recreational fishing in affected areas among tourists. While this effect may be offset 

by additional fishing by others, any decrease in fishing-based tourism could have broader impacts to a 

local economy. 

Summary and Conclusion 

The CPA proposed action and the broader OCS Program have varied effects on recreational fishing 

activity. The OCS Program has generally enhanced recreational fishing opportunities due to the role of 

oil platforms as artificial reefs. This effect depends importantly on the extent to which rigs are removed 

at decommissioning or are maintained through “rigs-to-reefs” programs. However, oil spills can have 

important negative consequences on recreational fishing activity due to the resultant fishing closures and 

longer-term effects oil spills can have on fish populations. This was evident during the DWH event, the 

effects of which are not yet certain. However, this type of catastrophic spill event is rare. The 

contribution of the CPA proposed action to these positive and negative cumulative effects would be 

minimal because of the relatively small amount of activity expected with the proposed action. It is likely 

that Fisheries Management Plans of the Federal and State governments would serve to keep overall 

recreational fishing activity reasonably stable through time. 

4.1.1.19. Recreational Resources 

The BOEMRE has reexamined the analysis for recreational resources presented in the Multisale EIS 

and the 2009-2012 Supplemental EIS, based on the additional information presented below and in 

consideration of the DWH event. No substantial new information was found that would alter the impact 

conclusion for recreational resources presented in the Multisale EIS and the 2009-2012 Supplemental 

EIS. 

The full analyses of the potential impacts of routine activities and accidental events associated with 

the CPA proposed action and the proposed action’s incremental contribution to the cumulative impacts 

are presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information is presented in the following sections. A brief summary of potential impacts follows. While 

marine debris and nearshore operations, either individually or collectively, may adversely affect the 

quality of some recreational experiences, they are unlikely to reduce the number of recreational visits to 

Gulf Coast beaches. It is unlikely that a spill would be a major threat to recreational beaches because any 

impacts would be short term and localized, and should have no long-term effect on tourism. The 
4-290 Central Planning Area Supplemental EIS 

incremental contribution of the CPA proposed action to cumulative impacts to recreational resources 

would be minor. 

4.1.1.19.1. Description of the Affected Environment 

A detailed description of recreational resources can be found in Chapter 3.3.3 of the Multisale EIS. 

Additional information for the 181 South Area and any new information since the publication of the 

Multisale EIS is presented in Chapter 4.1.14 of the 2009-2012 Supplemental EIS. The following 

information is a summary of the description of recreational resources incorporated from the Multisale EIS 

and the 2009-2012 Supplemental EIS, and new information that has become available since both 

documents were prepared. 

The CPA proposed action has the potential to affect the diverse set of recreational resources located 

throughout the coast of the Gulf of Mexico. The Gulf Coast is one of the major recreational regions of 

the United States. The shorefronts along the coasts of Florida, Alabama, Mississippi, Louisiana, and 

Texas support activities such as beach visitation, marine fishing, and nature-based recreation. These 

recreational opportunities attract visitors from around the world to the region. As such, these recreational 

resources are integral components to the broader economy of the Gulf of Mexico, supporting activities 

such as restaurants, lodging, and transportation. The Gulf Coast recreation/tourism economy has 

generally performed well in past years; however, events such as hurricanes, the recent global economic 

downturn, and the DWH event and resulting oil spill have strained various components of the recreation 

and tourism industries; they have also affected the baseline conditions for these industries in some 

regions. This section discusses the baseline conditions for recreational resources along the coasts of 

Louisiana, Alabama, Mississippi, and Florida since these are the primary areas that could be impacted by 

the CPA proposed action. The economic significance of the recreation and tourism industries in the 

coastal zones of these states is presented first; this is followed by a more in-depth discussion of the 

structure of the recreational industries in Florida, Mississippi, Alabama, and Louisiana. This section then 

presents a discussion of the impacts of the DWH event on the Gulf Coast, since the most direct effects of 

the resulting spill were felt in these states. 

Economic Significance of the Recreational Industry in the Gulf Coast 

The recreation and tourism industries are major sources of employment along the Gulf Coast. 

Table 4-16 presents employment statistics for a set of geographic regions in the Gulf of Mexico. Panel A 

presents data on the number of employees in the leisure/hospitality industry from 2001 through 2009 in 

13 BOEMRE-defined economic impact areas (EIA’s); these regions are defined in Figure 2-2 (All 

employment data were obtained through the U.S. Dept. of Labor, Bureau of Labor Statistics). In Table 4-

16, the leisure/hospitality industry corresponds to the definition used by the North American Industrial 

Classification System; this definition includes sub-industries such as entertainment providers, lodging 

services, and food/beverage services. Panel A shows that approximately 685,000 people worked in the 

leisure/hospitality industry in the Florida, Alabama, Mississippi, and Louisiana EIA’s in 2009. FL-3 and 

FL-4 had the largest concentration of recreation employees, with a total of about 423,000 workers. LA-4 

had a sizable recreation industry, having over 67,000 workers. Most of the EIA’s showed steady 

employment growth from 2001 through 2008; employment fell in all EIA’s except FL-1in 2009 with the 

onset of the global economic downturn during that time. A notable exception to the steady growth 

experienced by most regions occurred in 2005 in LA-4 and MS-1. Hurricane Katrina hit these two 

regions extremely hard, slashing tourism/recreation employment by almost half (the data presented is of 

December of that year; thus, the figure for 2005 should fully reflect the impact of Hurricane Katrina). 

Recreation employment in these regions has recovered a fair amount, although employment in 2009 is 

still below employment in 2004 in both LA-4 and MS-1 (U.S. Dept. of Labor, Bureau of Labor Statistics, 

2010a). 

Panel B of Table 4-16 presents the number of employees in recreation/tourism in the EIA 

counties/parishes that are directly along the Gulf Coast. These counties/parishes are particularly 

vulnerable to the effects of an oil spill such as the DWH event. As can be seen in Table 4-16, there are 

over 566,000 recreation jobs in the Florida, Alabama, Mississippi, and Louisiana coastal EIA 

counties/parishes. Over 400,000 of these jobs are in Florida, whose economy is particularly dependent on 

coastal recreation. Panel C of Table 4-16 presents data on the total number of jobs in the recreation and 
Description of the Environment and Impact Analysis 4-291 

tourism industries in each state; this data is primarily presented in order to provide some perspective on 

the relative size of the coastal recreational economies in these states. Table 4-17 presents data on total 

wages earned in the leisure/hospitality industry for the same geographic regions discussed in Table 4-16. 

In 2009, workers in the leisure and hospitality industries in the Florida, Alabama, Mississippi, and 

Louisiana EIA’s earned approximately $14 billion. The trends for each EIA over time are similar as was 

seen in Table 4-16. The effect on wages in 2005 in LA-4 and MS-1 from Hurricane Katrina would 

appear to less than that was observed for employment; however, this is simply a data issue since wages in 

2005 include wages earned before the onset of Hurricanes Katrina and Rita in August and September 

2005. It is worth noting that higher than average wages in LA-4, MS-1, and FL-4 lead total wages in 

these areas to represent a greater fraction of total wages than these areas have in total employment (the 

average salary of workers can be closely approximated by dividing total wages by total employment in 

any geographic region). Similarly, wages were lower than average in FL-2. 

Table 4-18 presents data on total tourism spending in each of the Gulf States (U.S. Travel 

Association, 2010). This is a somewhat different perspective than the wage data of Table 4-17. Total 

spending is higher than total wages since only a fraction of tourism spending translates into wages. For 

example, a portion of spending will end up as profit to the owners of the enterprises. In addition, 

spending on some items, particularly manufactured goods, may translate into wages to workers that are 

not categorized as being in the leisure/hospitality industry. Thus, looking at total spending provides a 

broader measure of the impact of tourism on the economies of the Gulf States. However, it is important 

to note that the data in Table 4-18 focuses only on spending by visitors and ignores spending on 

recreational activity by local residents. Therefore, the total economic impact of the recreation/tourism 

industry is somewhat greater than the data shows. 

Table 4-18 shows that visitors to the Gulf Coast States of Florida, Alabama, Mississippi, and 

Louisiana spent approximately $94 million in 2008. The trends observed for spending are reasonably 

similar as was observed for wages. As seen in Table 4-18, there has been a gradual increase in tourism 

spending in most years in these states. We see the decline in spending in Louisiana and Mississippi 

associated with Hurricanes Katrina and Rita; however, 2006 was the first full year after the hurricanes 

and, thus, more fully reflects their impacts on tourism in these states. 

A final perspective from which to view aggregate employment data is provided by Kaplan and 

Whitman (unpublished). This paper attempts to isolate those jobs that are particularly sensitive to OCS 

activities. For example, ocean and beach recreational activities are likely to be quite sensitive to OCS 

activities, particularly in the event of an oil spill. This is particularly true for some of the island-based 

recreational activities in the Gulf of Mexico; examples of these are Dauphin Island (Alabama) and the 

Gulf Islands National Seashore (Mississippi/Florida). However, a large portion of the jobs listed in 

Table 4-16 occur in restaurants, gambling facilities, and a myriad of other types of recreational activities. 

While these types of activities can still be affected by OCS activities, these effects are less direct than for 

ocean-based tourism/recreation. Kaplan and Whitman (unpublished) attempt to account for this effect by 

weighting each recreational activity by the extent to which it applies to tourism activity, as well as the 

extent to which it is dependent on coastal resources. 

Table 4-19 presents the estimated payroll, number of employees, and number of establishments 

associated with coastal travel, tourism, and recreation in 2004; there has not been a more recent study that 

uses an approach similar to Kaplan and Whitman. Kaplan and Whitman (unpublished) identify 

approximately 49,000 jobs in this category in Florida, Alabama, Mississippi, and Louisiana that support a 

payroll of approximately $583 million. Approximately half of these jobs occur in Florida. There is a fair 

amount of uncertainty in these numbers due to measurement issues and to events that have occurred since 

the measurement period, most notably hurricanes and the DWH event and resulting oil spill. However,

Kaplan and Whitman still provide a rough sense of the scale of coastal recreational employment in each 

state from a unique perspective. Namely, these numbers represent a narrowly defined measure of jobs in 

the region; this is particularly true in light of the DWH event and resulting oil spill, the scale of which has 

the potential to affect a broader group of activities. However, it is still of use to identify the most at risk 

jobs in a particular area since the data can provide a rough sense of the scale of the broader effects OCS 

activities can have on activities that indirectly depend on these workers. Indeed, one of the particularly 

important contributions of this study is to estimate the number of coastal travel, recreation, and tourism 

jobs on a county-by-county basis, which can guide policymakers when analyzing the effects of the DWH 

event and oil spill and of future potential accidental events. 
4-292 Central Planning Area Supplemental EIS 

Another more positive way in which OCS activity can affect recreation is through the effect of oil and 

gas structures themselves. Namely, there is substantial recreational activity associated with these 

structures in the Gulf of Mexico from Alabama through Texas, and these activities have a considerable 

economic impact. An Agency study to determine the economic contribution of rig-associated recreational 

activities estimated that a total of 980,264 fishing trips were taken within 300 ft (91 m) of an oil or gas 

structure or an artificial reef created from such structures during 1999 out of a total 4.48 million marine 

recreational fishing trips in the Gulf, about 22 percent of the total (Hiett and Milon, 2002). While rigs as 

reefs contribute substantially to fishing, they are also the destination for the vast majority of recreational 

diving trips. The study found that there were 83,780 dive trips near oil and gas structures out of a total 

89,464 dive trips taken, about 93.6 percent of the total. Overall, the study estimated a total of $172.9 

million in trip related costs for fishing and diving near oil and gas structures, with $13.2 million in trip 

expenditures for diving and $159.7 million associated with trip expenses for recreational fishing. 

Recreational Resources in Florida, Alabama, Mississippi, and Louisiana 

Florida has the largest coastal recreation economy among the Gulf Coast States. Approximately 84 

million visitors to Florida in 2008 spent approximately $70 billion statewide (Visit Florida Research, 

2010; U.S. Travel Association, 2010). One of the primary recreational activities near the Gulf Coast of 

Florida is beach visitation, particularly in the northern Panhandle and in the southern half of the state. As 

can be seen in Table 4-20, USEPA reports 634 beaches in the 22 coastal counties along the Gulf of 

Mexico. The National Survey on Recreation and the Environment estimates that 22 million people from 

throughout the United States visit Florida beaches annually; the surveys that form the basis of this 

estimate were taken from 2005 through 2009. Alpert et al. (2008) estimate that there were 20 million outof-state visitors and 2.2 million in-state visitors to Florida beaches in 2006. They estimate that beach 

tourism contributed $24.1 billion to Florida’s economy in 2006 and supported approximately 275,000 

jobs. Alpert et al. (2005) present a more detailed analysis of the economic impacts of beach tourism in 

Florida; they also provide information regarding the economic impacts of each beach region in Florida. 

For example, they estimate that beach visitors in the northwest and southwest beach regions in Florida 

spent $15.5 billion in 2002. 

Florida is also the most economically significant state nationwide in a number of other coastal-related 

recreation activities. Florida has the largest recreational fishing industry in the Nation, with 

approximately 160 million fish landed in 2009 (USDOC, NMFS, 2010e). Additional information on 

recreational fishing can be found in Chapter 4.1.1.18. The recreational marine industry as a whole 

generated approximately $18.4 billion in spending and directly or indirectly supported 220,000 jobs in the 

region; this includes activities such as boating, marinas, fishing, and marine science research (Monterey 

Bay Aquarium Research Institute, 2008). Finally, the Florida system of State parks provided a direct 

economic impact of over $900 million (Monterey Bay Aquarium Research Institute, 2008); examples of 

these include the Gulf Islands National Seashore, St. George Island State Park, the DeSoto National 

Memorial, Big Cypress National Preserve, Apalachicola National Forest, and Everglades National Park. 

There are also national wildlife refuges along Florida’s coast that are used for various recreational 

activities; examples of these include Aucilla Wildlife Management Area, Cecil M. Webb State Wildlife 

Management Area, and Steinhatchee Conservation Area. Estimates of the economic significance of some 

of these facilities can be found in Kaplan and Whitman (unpublished); the geographic location of these 

parks, as well as information on the extent to which they were affected by the DWH event, can be found 

using NOAA’s ERMA mapping system (USDOC, NOAA, 2010f). 

Tourism and recreation accounted for $7.7 billion in tourism spending and 160,000 jobs in Alabama. 

Approximately 35 percent of spending and 36 percent of recreational employment in Alabama occurs 

along the Gulf Coast (Alabama Tourism Department, 2009). Mobile County has around 15,000 

recreation workers, while Baldwin County has an additional 9,000 workers (U.S. Dept. of Labor). 

Approximately 21 million people visited the State of Alabama as a whole (Alabama Tourism Department, 

2009). The coastal areas are particularly dependent on beach recreation and wildlife activities (such as 

birding). For example, approximately 1 million people participated in wildlife viewing in Alabama in 

2006 (USDOI, 2006). Much of this activity occurs in State parks and refuges; examples of these include 

Maeher State Park, Gulf State Park, and the Marine Resources Division Laboratory on Dauphin Island. 
Description of the Environment and Impact Analysis 4-293 

Visitors to Mississippi spent approximately $6.3 billion in 2008, which helped to support 125,000 

leisure/hospitality jobs statewide. Approximately $1.8 billion of this spending and 27,000 of these jobs 

occur in the Gulf Coast region (U.S. Dept. of Labor, Bureau of Labor Statistics, 2010a; Mississippi 

Development Authority, 2010). Harrison County has the highest tourism employment in the region, with 

approximately 19,000 jobs. One of the primary contributors to the Gulf Coast recreation industry in 

Mississippi is the casino gaming industry that accounts for approximately 35 percent of recreational 

employment in the State (Mississippi Development Authority, 2010). Mississippi had 30 State-licensed 

casinos as of June 30, 2009; these casinos had revenues of $2.6 billion in 2009. Nine of these casinos are 

located along the Gulf of Mexico and had revenues of approximately $1.2 billion in 2009. In addition, 

the Mississippi District of the Gulf Islands National Seashore is an important recreational area; more 

information on the Gulf Islands National Seashore can be found through the National Parks Service 

(USDOI, NPS, 2010). 

The leisure hospitality industry in Louisiana brought in $9.6 million in spending and supported 

190,000 jobs Statewide in 2008. The EIA parishes with over 10,000 recreation workers are Calcasieu, 

Lafayette, East Baton Rouge, Jefferson, and Orleans (U.S. Dept. of Labor, Bureau of Labor Statistics, 

2010a). Jefferson and Orleans Parishes are the largest coastal recreation centers, with much of the 

tourism activity being driven by the various attractions of the New Orleans area. The recreation activity 

in these two parishes has been in a state of flux in recent years as they have attempted to recover from 

Hurricanes Katrina and Rita. For example, recreation employment in Orleans Parish fell from 43,508 in 

December 2004 to 18,064 in December 2005; it recovered to a level of 31,449 in December 2009 (U.S. 

Dept. of Labor, Bureau of Labor Statistics, 2010a). The recreational activity in the remaining coastal 

counties in Louisiana centers around Cajun culture, wetlands, and wildlife activities. State parks in the 

coastal zone of Louisiana include Cypremort Point State Park, Palmetto Island State Park, Grand Isle 

State Park, St. Bernard State Park, and Fontainebleau State Park; a map of these parks can be found at 

(Louisiana Dept. of Culture, Recreation, and Tourism, 2010). Coastal Louisiana is also characterized by a 

vast array of wildlife refuges that support a variety of recreational activities; those that are closest to the 

Gulf of Mexico include Sabine National Wildlife Refuge, Rockefeller State Wildlife Refuge and Game 

Preserve, Russell Sage Foundation Marsh Island State Wildlife Refuge, Atchafalaya Delta State Wildlife 

Management Area, Pointe Aux Chenes Wildlife Management Area, Delta National Wildlife Refuge, Pass 

a Loutre State Wildlife Management Area, Biloxi State Wildlife Management Area, Breton National 

Wildlife Refuge, and Bayou Savage National Wildlife Refuge. Estimates of the economic significance of 

some of these areas can be found in Kaplan and Whitman (unpublished); the geographic location of these 

areas, as well as information on the extent to which they were affected by the DWH event, can be found 

using NOAA’s ERMA mapping system (USDOC, NOAA, 2010f). 

Change in Baseline Conditions due to the Deepwater Horizon Event 

The previous discussion presents the tourism/recreation baseline prior to the DWH event and 

resulting oil spill. This oil spill was a major event that affected the recreation industry in a number of 

ways. The most direct effects of the spill were on recreational fishing and on beach visitation. For 

example, at the height of its impact, the spill had closed 36.6 percent of recreational fishing areas in the 

Gulf of Mexico (this occurred on June 2); as of November 15, 2010, this percentage had dropped to less 

than 1 percent (USDOC, NOAA, 2010j); see Chapter 4.1.1.18 for more information on the short-term 

impacts of the oil spill on recreational fishing activity. In addition, several beaches between eastern 

Louisiana and the northeast corner of Florida have experienced either advisories or closures to the spill (a 

list of these advisories/closures can be found at National Resources Defense Council, 2010). The 

NOAA’s ERMA system also provides an updated graphical account of the extent to which certain coastal 

regions were impacted by the spill; for example, in November 2010, the primary areas that remained 

somewhat oiled were in Barataria Bay, Grand Isle, Breton National Wildlife Refuge, and some of the 

smaller islands off the coast of Gulfport, Mississippi (USDOI, NOAA, 2010f). 

The effects of the spill, however, were broader than the effects to the contaminated fishing sites and 

beaches. For example, Butler and Sayre (2010) found that restaurants, hotels, and boating activities were 

noticeably impacted in coastal Mississippi as a result of the oil spill. It also appears that the effects on 

these industries reached beyond the areas in which oil actually came ashore; examples of these findings 

include The Knowland Group (2010) and the Federal Reserve Bank of Atlanta (2010). This effect could 
4-294 Central Planning Area Supplemental EIS 

be due to both misperceptions about the extent of the spill, as well as general hesitation to visit a general 

region impacted by an event such as the DWH event. For example, the Mississippi Development 

Authority (2010) conducted a study of perceptions of the extent to which Louisiana was impacted as the 

spill progressed. It also appears that the influx of relief workers, as well as the compensation payments 

received by affected workers, altered the complexion of those who were economically helped and hurt by 

the spill. For example, one analysis found a noticeable increase in hotel receipts in coastal Louisiana and 

on the Mississippi/Alabama border during the summer of 2010 compared with the summer of 2009; this 

same study found that counties in the northwest corner of Florida experienced a noticeable decrease in 

receipts during the same time periods (Gulf of Mexico Oil Spill Blog, 2010). 

For the purposes of analyzing the baseline environment, there is an important distinction between 

those effects that occurred during the spill versus those that will persist now that the spill has been 

stopped. The most direct manner in which the effects of the oil spill will persist will be as a result of 

resources that will remain damaged for some time. It appears that reasonably rapid progress has been 

made regarding the removal of oil from beaches and other coastal areas in the Gulf of Mexico. For 

example, the length of oiled coastline has decreased from 658 mi 1,059 km) on August 6, 2010, to 

approximately 95 mi (153 km) on October 27, 2010 (RestoreTheGulf.gov, 2010d and 2010e). However, 

more uncertainty remains regarding the effects of the oil spill on the fish ecosystems in the Gulf of 

Mexico. Even if the fish ecosystems emerge in a reasonable period of time, it will likely take some time 

for recreational fishing activity in the region to return; it will also take time to restore confidence in the 

seafood industry in the region. Similarly, tourists will likely only gradually return to the beach areas in 

the vicinity of the oil spill. 

Oxford Economics (2010) conducted a study of recent catastrophic events in order to estimate the 

longer-term economic implications of the DWH event and resulting oil spill. For example, they examine 

the extent to which the Exxon Valdez spill and the Ixtoc oil spill of 1979 are comparable to the DWH; 

more information on the Ixtoc spill can be found in (USDOI, BLM, 1982). They estimate that the longterm economic damage from the spill could be between $7.6 and $22.7 billion. Analyzing previous oil 

spills and other catastrophic events, they also suggest that it could take 15-36 months for the tourism 

industry to recover to pre-spill levels. Given Florida’s dependence on fishing and beach activities (as 

well as the overall size of its economy), this study suggests that the State will bear the majority of the 

economic damage from the spill. However, it is important to recognize the uncertainty inherent in 

attempting to predict the speed at which the tourism industry will recover. A number of factors will come 

in to play; for example, the extent to which the broader economy rebounds from the serious recent 

recession will likely come in to play. In addition, the policy actions of State and local governments will 

influence the extent to which confidence in the region can be restored. The BOEMRE will continue to 

monitor developments in the region and will update the baseline estimates of recreation and tourism in the 

Gulf of Mexico as new information becomes available. 

4.1.1.19.2. Impacts of Routine Events 

Background/Introduction 

Routine OCS oil and gas activities can affect recreation and tourism in diverse ways. The OCS 

activities can have direct negative impacts on beach and coastal recreational resources through discharges 

of marine debris, noise, and visual impairments. There are also possible indirect impacts on local 

recreational resources from space-use conflicts and from increased economic activity from OCS 

operations. The unique role that oil platforms can play as artificial reefs should also be accounted for 

when considering policy actions. Finally, the possible effects of public perceptions on tourism, 

particularly in light of the DWH event, should be considered. In summary, while impacts on recreational 

resources from routine OCS activities can occur from a number of sources, in total they are likely to be 

reasonably small in scale. 

Beach- and coastal-related recreational resources are the most vulnerable to routine OCS operations. 

The potential for OCS-related marine debris to wash up along beaches is one of the most immediate 

concerns. Marine debris originates from OCS operations, sewage treatment plants, recreational and 

commercial fishing, industrial manufacturing, and various forms of vessel traffic. The prevalence of 

marine debris is an important global problem and can noticeably detract from the aesthetic value of 

recreational beaches. Various government agencies participate in a coordinated effort to combat marine 
Description of the Environment and Impact Analysis 4-295 

debris; a broad summary of the issues involved and the policy structure with respect to marine debris can 

be found in the report of the Interagency Report on Marine Debris Sources, Impacts, Strategies, and 

Recommendation (USDOC, NOAA, 2008b). There is also a national monitoring program in place to 

track the progression of the marine debris problem in various locations (Sheavly, 2007). McIlgorm et al. 

(2009) presents an economic analysis of the costs of marine debris and of programs designed to minimize 

debris. Besides these general responses, there are a number of regulations in place to minimize the 

potential for marine debris to be released due to OCS activities. This Agency issued an NTL that explains 

the actions oil and gas operators are required to implement (USDOI, MMS, 2002a). It is likely that this 

regulatory framework will keep the discharge of marine debris from OCS facilities to a reasonably low 

level. 

There are also potential negative impacts on beach tourism from vessel noise and from the visibility 

of OCS infrastructure. While the potential effects of noise on tourism are difficult to quantify, several 

characteristics of the OCS industry serve to mitigate the potential for noise effects. First, most OCSrelated vessel traffic moves between onshore support bases and work and production areas far offshore. 

Support bases are located in industrial ports, which are usually distant from recreational use areas. 

Second, OCS vessel use of approved travel lanes should help to separate this traffic from recreational 

resources and to keep noise fairly transitory and thus unlikely to noticeably impact tourism. The extent to 

which the visibility of OCS platforms can affect tourism depends primarily on the distance of platforms 

from shore and on the size of the particular oil rig. For example, a study by the Mississippi Development 

Authority found that a 50-ft (15-m) high production platform was identifiable 3 mi (5 km) from shore and 

a 100-ft (30-m) high production platform was visible 10 mi (16 km) from shore (Collins Center for Public 

Policy, 2010). All OCS platforms are at least 3 mi (5 km) from shore and most are beyond 10 mi (16 km) 

from shore. However, should a platform be visible, the scale of its impact on tourism would likely be 

small unless it interrupted the vision of other important landscape features. 

Oil platforms constructed along with OCS activities serve unique roles as artificial reefs. Soon after 

deployment, an oil platform attracts a wide variety of fish species and other organisms to its structure. As 

a result, some offshore platforms are important components to the recreational fishing industry; oil 

platforms are also hosts to a large amount of recreational diving activity (Hiett and Milon, 2002). The 

role of oil rigs as artificial reefs also raises a number of issues during the decommissioning stage of an oil 

platform’s life. Each Gulf Coast State has a mechanism for allowing some oil platforms to remain in 

place and to continue to serve as artificial reefs after oil production has ceased; Dauterive (2000) provides 

an overview of these programs. McGinnis et al. (2001) also discusses the broader economic implications 

of decommissioning oil structures. This decommissioning stage has the potential to affect recreational 

resources in a particular area if a rig is ultimately not maintained for reef purposes or if the rig is moved 

to a different location. 

The OCS oil and gas activity can also affect recreational resources indirectly due to a number of 

economic factors. First, increased onshore infrastructure necessary to support offshore activities can 

create space-use conflicts. For example, Brody et al. (2006) present an analysis of space-use conflicts for 

oil and gas activities off the coast of Texas, although the issues they raise would be generally applicable 

to OCS activities in the other Gulf Coast States as well. They used a GIS-based framework to identify 

specific locations where conflicts between oil activities and other concerns (including recreational use) 

are most acute; they found that recreational use conflicts tend to be concentrated around some of the 

major wildlife viewing and beach areas near the larger population areas in Texas. In addition, the effects 

of OCS activities on the structure of employment in local economies have the potential to increase or 

decrease the demand for recreational resources in these communities. Increased demand for recreational 

resources has the potential to attract new recreational firms to a community; however, increased demand 

also has the potential to lessen the enjoyment of a particular resource by some community members. 

Mason (2010) provides some context on the interdependence of the offshore oil and gas industry with 

other sectors of the economy of the Gulf of Mexico; for example, they show that accommodation and 

food service resources have a reasonably high dependence on OCS activities. Wallace et al. (2001) also 

discuss community level effects of OCS activities on some of the local economies in the Gulf of Mexico; 

for example, this study presents descriptive evidence regarding concerns some local residents have 

regarding the impacts of OCS activities on recreational opportunities. However, given the limited scale 

of the proposed action relative to the existing oil and gas industry, the scale of the indirect economic 

impacts caused by new leasing activity is likely to be small. 
4-296 Central Planning Area Supplemental EIS 

While the DWH event primarily affects the baseline environment and our understanding of the 

impacts of accidental events, it also raises issues regarding the effects of OCS routine actions on 

recreation and tourism. Because of the particular sensitivity of tourism activity to public perceptions, 

concerns over offshore oil operations could potentially cause routine OCS actions to have impacts even in 

the absence of a future spill. This is primarily the case for recreational resources that require investment 

in real estate or other long-term fixed assets. For example, the DWH event has apparently caused a 

noticeable fall in property values in some areas in the Gulf of Mexico (see CoreLogic [2010] for 

preliminary data on some of these effects). Effects on property values may prove transitory. However, 

this impact could negatively impact recreational resources should this decline be long lived and lead to a 

reduction in the construction of recreational resources or to a decline in the use of existing recreational 

facilities. While the scale of this effect is unclear, it is likely that the incremental effect of the CPA 

proposed action would be small given their size relative to ongoing OCS oil and gas operations. 

Proposed Action Analysis 

The CPA proposed action would result in 149-263 producing oil wells, 144-237 producing gas wells, 

and 32-44 installed production platforms. Marine debris would be lost from time to time from OCS 

operations associated with drilling activities projected to result from the CPA proposed action. Current 

industry waste management practices, training and awareness programs focused on the beach litter 

problem, and the OCS industry’s continuing efforts to minimize, track, and control offshore wastes are 

expected to minimize the potential for accidental loss of solid wastes from OCS oil and gas operations. 

The CPA proposed action is expected to result in 3,425-5,500 service-vessel trips and 25,100-56,025 

helicopter operations annually. Service vessels are assumed to use established nearshore traffic lanes, and 

helicopters are assumed to comply with areal clearance restrictions at least 90 percent of the time. These 

actions tend to distance traffic from recreational beach users and thus minimize its effects. The additional 

helicopter and vessel traffic would add a low level of noise pollution that would affect beach users. 

The CPA proposed action would have a number of broader economic impacts, some of which have 

the potential to affect recreational resources in the Gulf of Mexico. This issue is of particular interest in 

the CPA due to the higher relative scale of the CPA proposed action compared with the WPA proposed 

action. The employment and income effects are likely to be felt in the Houston, Texas, area and in coastal 

Louisiana. Loren C. Scott & Associates (2008) presents an analysis of the particular economic 

importance of Port Fourchon and its impacts on the local region of Houma. Houston is at the center of a 

large inland metropolitan area connected to the Gulf by an industrial canal. The potential economic 

effects of the CPA proposed lease sale on recreational resources would not be identifiable in the Houston 

area, given the size and location of this metropolis. Recreational resources in coastal Louisiana could be 

affected by space-use conflicts and by increased use of recreational resources in local areas; however, 

these effects are likely to be small in scale due to the already entrenched nature of the oil industry in these 

areas. The role of perceptions on recreational activity in light of the DWH event has the potential to be an 

issue for most areas along the Gulf Coast. This is notably true for recreation in Florida, which, although 

not bordering the CPA, could be impacted by public perceptions raised by lease sites close enough to the 

Florida shore. The Collins Center for Public Policy (2010) presents a discussion of the potential impacts 

of oil and gas operations to Florida. Hagerty and Ramseur (2010) present a broader perspective of the 

economic impacts of the oil spill on tourism; this study also points out that the tourism promotion 

programs that have been enacted in the Gulf Coast States has the potential to mitigate some of the 

negative impacts from OCS operations on tourism. 

Summary and Conclusion 

Routine OCS actions in the CPA could cause minor disturbances to recreational resources, 

particularly beaches, through increased levels of noise, debris, and rig visibility. Because offshore spills 

have a small probability of contacting estuarine habitats that serve as nurseries for many recreational 

species and because inshore spills would have localized impacts to an area, oil spills would have a small 

effect on recreational fisheries. Routine activities could also cause minor changes the composition of 

local economies through changes in employment, land-use, and recreation demand. The CPA proposed 

action has the potential to directly and indirectly impact recreational resources along the coastal areas 
Description of the Environment and Impact Analysis 4-297 

adjacent to the CPA. However, the small scale of OCS activities relative to the scale of the existing oil 

and gas industry is such that these potential impacts on recreational resources are likely to be minimal. 

Spills most likely to result from the CPA proposed action would be small, of short duration, and not 

likely to impact Gulf Coast recreational resources. Should an oil spill occur and contact a beach area or 

other recreational resource, it would cause some disruption during the impact and cleanup phases of the 

spill. However, these effects are also likely to be small in scale and of short duration. This is because the 

size of a coastal spill is projected to be small (coastal spills are assumed to be 5 bbl; Table 4-13 of the 

Multisale EIS), and the probability of an offshore spill contacting most beaches is small. In the unlikely 

event that a spill that is sufficiently large to affect large areas of the coast occurs and, through public 

perception, has effects that reach beyond the damaged area, effects to recreation and tourism could be 

significant. The DWH event was such a case; the resulting spill damaged some coastal resources but had 

economic effects in a much larger area. The role of perception on tourism activity was a particularly 

important feature of the DWH event, one that should become better understood as the aftermath of the 

spill unfolds. 

4.1.1.19.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of the effects of accidental events on recreational resources can be found in 

Chapter 3.3.3 of the Multisale EIS. Additional information for the 181 South Area and any new 

information since the publication of the Multisale EIS is presented in Chapter 4.1.14 of the 2009-2012 

Supplemental EIS. The following information is a summary of the description of recreational resources 

incorporated from: the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

This chapter first presents background information that is relevant to either a CPA or WPA proposed 

action. This includes an analysis of the effects of previous oil spills, as well as new information that has 

become available in light of the DWH event. This section then presents a discussion of some issues that 

are unique to the CPA proposed action. 

The recreational resources most vulnerable to an oil spill are beaches and nature parks along the Gulf 

Coast. The ESI’s provide overall measures of the sensitivity of a particular coastline to a potential oil 

spill (USDOC, NOAA, 2010k). The ESI’s rank coastlines from 1 (lease sensitive) to 10 (most sensitive); 

ESI maps also provide point indicators for recreational resources. Marshes and swamps are examples of 

resources that have ESI’s of 10 due to the extreme difficulty of removing oil from these areas. The ESI’s 

for beach areas generally range from 3 to 6, depending on the type of sand and the extent to which gravel 

is mixed into the beach area. The ESI maps for any coastline along the Gulf of Mexico can be viewed 

using NOAA’s ERMA mapping system (USDOC, NOAA, 2010f). 

The effects of an oil spill on a particular beach region will depend on the success of the containment 

and cleanup operations following an oil spill. The NOAA provides a broad overview of the procedures 

used to assess oiled beaches (USDOC, NOAA, 2000). Both manual and machine-based techniques can 

be used to clean oil; the cleaning technique chosen for a particular beach will depend on the nature of the 

oiling of a particular beach area. Oil that remains on beach surfaces is often easier to clean than oil that 

seeps deeper into the ground. Overall, there appeared to be reasonably rapid progress in cleaning the 

coastline following the DWH event; for example, the length of oiled coastline has decreased from 658 mi 

(1,059 km) on August 6, 2010, to approximately 95 mi (153 km) on October 27, 2010 

(RestoreTheGulf.gov, 2010d and 2010e). However, Wang and Roberts (2010) argue that a fair amount of 

the oil from the DWH event may be buried below the beach surfaces in some areas, which can cause 

problems to the long-term recreational and ecological uses of these areas. 

Recreational resources such as beaches serve as important bases for certain local economies. 

Therefore, oiled beach regions can cause economic losses to both individuals and firms in the area of an 

oiled or closed beach. Parsons and Kang (2007) perform an economic analysis of the costs of 

hypothetical beach closures along the Texas Gulf Coast. They estimate that the economic costs of beach 

closures along the Padre Island National Seashore would range from $26,000 to $172,000, depending on 

the time of year the closures would occur. The oil spill off the Tampa Bay, Florida, coast in 1993 is an 

example of a spill that affected recreational beaches. Damage to these beaches and other recreational 

resources was determined to cause $2.5 million in damages to the affected parties in the area (Florida 
4-298 Central Planning Area Supplemental EIS 

Dept. of Environmental Protection and USDOC, NOAA, 2000). Finally, the New Orleans oil spill of 

2008 demonstrates that a spill can affect different types of recreational activities. Namely, this spill 

impacted some of the boating and restaurant businesses in the vicinity of the spill; it also caused some 

aesthetic impacts to the experiences of tourists in the region (Tuler et al., 2010). 

The DWH event was much more significant in size and duration than the previously mentioned spills. 

As such, it raises important questions regarding the impacts of oil spills on recreation and tourism. One 

important point is that a spill of the DHW event’s dimensions can influence a much broader range of 

individuals and firms than can a smaller spill. For example, a small, localized spill may lead some 

travelers to seek substitute recreational opportunities in nearby areas. However, a large spill is more 

likely to dissuade travelers from visiting a broader economic region. Similarly, mid-sized restaurant 

chains and hotels may be able to find other customers or to simply weather a smaller spill. However, a 

spill the size of the DWH event is more likely to affect these types of firms since they are less able to 

diversify their customer base. These effects can be seen in the makeup of those who have filed damage 

claims with BP (Gulf Coast Claims Facility, 2010a). For example, the bulk of the claims by individuals 

have been made in the food, beverage, lodging sector and in the retail, sales, and service sector. Claims 

have also been made by individuals and firms in a broad range of geographic regions, many of which 

were not directly impacted by oil. The claims process and the cleanup process must also be taken into 

account when attempting to ascertain the ultimate impacts of a spill on a recreational economy. For 

example, one analysis found a noticeable increase in hotel receipts in coastal Louisiana and on the 

Mississippi/Alabama border during the summer of 2010 compared with the summer of 2009; this same 

study found that counties in the northwest corner of Florida experienced a noticeable decrease in receipts 

during the same time periods (Gulf of Mexico Oil Spill Blog, 2010). While the spill caused economic 

damage to a number of people in the Louisiana and Mississippi/Alabama border area, this example 

demonstrates that the effects of cleanup and damage mitigation activities must be taken into account when 

analyzing the overall impact of a spill on recreational economies. 

The broad impact of the DWH event also highlights the critical role of media coverage and public 

perceptions in determining the extent to which an oil spill will affect the recreational economy. Namely, 

there were a number of reports that various effects on tourism were felt in areas beyond the locations in 

which oil washed up along beaches and other areas. A Congressional hearing into this matter (U.S. 

House of Representatives, 2010) provides a broad overview of some of the effects that were felt along the 

Gulf Coast. For example, a representative of Pinellas County estimated that this area had lost roughly 

$70 million in hotel revenue even though beaches in this area did not receive any oil damage. This type 

of effect could be due to misperceptions about the spill, uncertainty about the future of the spill, or 

concerns about whether a tourism experience will be affected even if the destination is only within close 

proximity to a spill. While these effects are complex and largely determined by the dynamics of a 

particular spill, the DWH event demonstrates that they must be considered as part of the full effects of a 

spill. 

Oxford Economics (2010) attempts to quantify these effects by analyzing the impacts of recent 

catastrophic events on recreational economies. For example, they analyzed the Ixtoc oil spill of 1979, the 

scale and nature of which is reasonably similar to the DWH event. In this example, it took approximately 

3 years for beaches to be cleaned and for recreational activity to return to similar levels as before the spill. 

More information regarding the economic effects of the Ixtoc spill can be found in (USDOI, BLM, 1982). 

They also looked at the Prestige oil spill of 2002 off the coast of Spain. Given the nature and size of that 

spill, recreational activity was able to return to pre-spill levels in approximately 1 year. More information 

regarding the Prestige spill can be found in Garza et al. (2009). Oxford Economics (2010) estimates that 

the long-term economic damage from the DWH event’s resulting spill to be between $7.6 and $22.7 

billion. Given Florida’s dependence on fishing and beach activities (as well as the overall size of its 

economy), this study suggests that the State might bear the majority of the economic damage from the 

spill even though it experienced fewer physical impacts than did other states. However, this conclusion is 

highly uncertain since it depends so greatly on the role of perceptions on recreational activity. It is likely 

our understanding of the role of oil spills on perceptions and tourism will improve as the aftermath of the 

DWH event unfolds. 
Description of the Environment and Impact Analysis 4-299 

Proposed Action Analysis 

Spills of the magnitude of the DWH event are high impact but low-probability events. Catastrophic 

spills are discussed in Appendix B. The risk of a spill occurring from the CPA proposed action and 

contacting recreational beaches is described in Chapter 4.3.1.8 of the Multisale EIS. Figure 4-13 of the 

Multisale EIS displays the probabilities of oil spills 1,000 bbl occurring and contacting certain 

shorelines as a result of the CPA proposed action. The probabilities of an oil spill occurring and 

contacting the shoreline are greater than 0.5 percent in the following parishes and counties: Cameron, 

Vermillion, Iberia, Terrebonne, Lafourche, Jefferson, St. Bernard, and Plaquemines Parishes in Louisiana; 

and Jefferson and Galveston Counties in Texas. Figure 4-13 of the Multisale EIS provides the 

probabilities of oil spills 1,000 bbl occurring and contacting recreational beach areas or State offshore 

waters within 10 days as a result of the CPA proposed action. As can be seen, the CPA proposed action 

has a 5-9 percent chance of impacting Louisiana’s beach regions, while the probability of reaching 

Texas’s beach regions is less than 1 percent. 

The ESI maps of the coastline of the Gulf of Mexico can be found using NOAA’s ERMA mapping 

system (USDOC, NOAA, 2010f). Most pieces of the beach region in western Louisiana have an ESI 

rating of 3, suggesting that a small-scale spill would be able to be cleaned in a reasonable period of time. 

However, the vast majority of the nature preserves along the remainder of coastal Louisiana are 

characterized by marsh and swamp areas, which have an ESI of 10. Oil entering these recreational areas 

would take a fair amount of time and effort to clean. This would have a particular impact on recreational 

fishing activity; more information regarding recreational fishing can be found in Chapter 4.1.1.18. 

However, given that recreational uses of these areas are less densely concentrated, it would take a largesized spill to alter the structure of the recreational industry in a particular region. 

Summary and Conclusion 

Spills most likely to result from the CPA proposed action would be small, of short duration, and not 

likely to impact Gulf Coast recreational resources. Should an oil spill occur and contact a beach area or 

other recreational resource, it would cause some disruption during the impact and cleanup phases of the 

spill. However, these effects are also likely to be small in scale and of short duration. In the unlikely 

event that a spill occurs that is sufficiently large to affect large areas of the coast and, through public 

perception, have effects that reach beyond the damaged area, effects to recreation and tourism could be 

significant. The DWH event was such a case; the resulting spill damaged some coastal resources but had 

economic effects in a much larger area. The role of perceptions on tourism activity was a particularly 

important feature of the DWH event, one that should become better understood as the aftermath of the 

spill unfolds. 

4.1.1.19.4. Cumulative Impacts 

Background/Introduction 

A detailed description of the cumulative effects on recreational resources can be found in Chapter 

3.3.3 of the Multisale EIS. Additional information for the 181 South Area and any new information since 

the publication of the Multisale EIS is presented in Chapter 4.1.14 of the 2009-2012 Supplemental EIS. 

The following information is a summary of the description of recreational resources incorporated from the 

Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has become available since 

both documents were prepared. 

The cumulative impacts to recreational resources would occur through the proposed action, the 

existing OCS Program, and from the expected impacts of external events and actions to recreational 

resources and tourism activity. The proposed action would contribute to a number of aesthetic and spaceuse issues arising from existing oil and gas programs. Oil spills can also impact the recreational uses of 

beaches and wetland areas, which are already being impacted through coastal erosion. Finally, lingering 

impacts of the global recession and the DWH event’s oil spill would contribute to the incremental impacts 

of an oil spill, should one arise from the proposed action. 
4-300 Central Planning Area Supplemental EIS 

Aesthetic Impacts 

The CPA proposed action would contribute to some negative aesthetic impacts of the existing OCS 

Program and of State oil and gas programs. First, oil and gas activities would contribute to the marine 

debris problems experienced by the Gulf Coast. Marine debris originates from OCS operations, sewage 

treatment plants, recreational and commercial fishing, industrial manufacturing, and various forms of 

vessel traffic. The prevalence of marine debris is an important global problem and can noticeably detract 

from the aesthetic value of recreational beaches. Various government agencies participate in a 

coordinated effort to combat marine debris; a broad summary of the issues involved and the policy 

structure with respect to marine debris can be found in the report of the Report on Marine Debris Sources, 

Impacts, Strategies, and Recommendation (USDOC, NOAA, 2008b). There is also a national monitoring 

program in place to track the progression of the marine debris problem in various locations (Sheavly, 

2007). McIlgorm et al. (2009) presents an economic analysis of the costs of marine debris and of 

programs designed to minimize debris. Besides these general responses, there are a number of 

regulations in place to minimize the potential for marine debris to be released due to OCS activities. This 

Agency issued an NTL that describes and explains the actions oil and gas operators are required to 

implement (USDOI, MMS, 2002a). It is likely that this regulatory framework would keep the discharge 

of marine debris from OCS facilities and its contributions to the cumulative impacts of marine debris to a 

reasonably low level. 

The oil platforms and infrastructure that arise from the CPA proposed action would contribute to the 

existing visibility of oil facilities along the Gulf Coast. The extent to which the visibility of OCS 

platforms can affect tourism depends primarily on the distance of platforms from shore and on the size of 

the particular oil rig. For example, a study by the Mississippi Development Authority found that a 50-ft 

(15-m) high production platform was identifiable 3 mi (5 km) from shore and a 100-ft (30-m) high 

production platform was visible 10 mi (16 km) from shore (Collins Center for Public Policy, 2010). All 

Federal OCS platforms in the CPA are at least 3 mi (5 km) from shore and most are 10 or more miles 

(16 or more kilometers) from shore. In addition, the visibility of OCS infrastructure is unlikely to 

noticeably detract from recreational uses unless it blocks the sight path of significant landmarks. Finally, 

the CPA proposed action would contribute incrementally to helicopter and vessel noise due to routine 

OCS operations. This would likely be most acute during the construction phases near service-vessel 

ports. However, the use of approved traffic lanes and times should keep the disturbance of these activities 

to recreational users to a minimum. 

Space-Use Conflicts 

The CPA proposed action would incrementally contribute to space-use conflicts that exist between 

OCS operations and some recreational uses. Conflicts could primarily arise with recreational boaters and 

fishermen; the nature of the space use of OCS operations is discussed in Chapter 4.1.1.3.3.2 of the 

Multisale EIS. Space-use conflicts from the CPA proposed sale could occur in the WPA as well. Much 

of the recreational activity that could conflict with OCS operations occurs near parks and wildlife refuges; 

the locations of these sites and other recreational use sites can be found using NOAA’s ERMA mapping 

system. The OCS service-vessel ports are presented in Figure 3-5; onshore infrastructure locations in the 

CPA are shown in Figure 3-14 and 3-15 of the Multisale EIS. The OCS ports and infrastructure are 

particularly prevalent throughout coastal Louisiana. However, since most recreational use sites in 

Louisiana are fairly spread out, it is likely that space-use issues would not be overly pronounced. In 

addition, since most ocean-based recreation occurs relatively close to shore, there would more likely be 

conflicts with State oil and gas programs than with the CPA proposed action. Overall, the incremental 

contribution of the CPA proposed action to potential sources of space-use conflict should be minimal. 

Oil Spills and Beach/Wetland Depletion 

The OCS Program occurs in an environment in which beach and wetland resources are undergoing 

depletion due to human development, hurricanes, and natural processes. An overview of coastal erosion 

threats can be found in Evaluation of Erosion Hazards (The Heinz Center, 2000). Government policy 

towards managing beach erosion can be found at the website of NOAA’s Coastal Services Center. A 

recent example of a proposed beach nourishment project in Panama City Beach, Florida, is presented by 
Description of the Environment and Impact Analysis 4-301 

COE (U.S. Dept. of the Army, COE, 2010). Oil spills have the potential to contribute to beach erosion, 

both due to contaminated sentiment and to the potential sediment losses during the cleanup process. This 

would have a particular impact on recreational activity in some of the high-volume beach areas such as 

Galveston and South Padre Island. However, beach cleaning techniques that are less damaging to 

beaches may become more prevalent during future years; a discussion of beach cleaning techniques is 

presented in Chapter 3.2.1.5.4 of the 2009-2012 Supplemental EIS. A more detailed discussion of the 

cumulative impacts of OCS actions on coastal beaches and dunes is presented in Chapter 4.1.1.3.4. 

Further information on the cumulative impacts on wetlands resources can be found in Chapter 4.1.1.4.4. 

Deepwater Horizon Event and Tourism 

The effects of the DWH event on tourism and recreational activity are still evolving. While a number 

of workers in the recreational industry were harmed, the response and mediation activities, as well as a 

gradually improving overall economy, have helped to put the tourism industry in the affected areas on a 

path to recovery. However, the DWH event will help shape public reaction to any future spills or other 

accidental events that occur due to offshore leasing programs on the OCS or in State waters. For 

example, the role of perceptions would likely be magnified in any future spill due to the significant media 

attention given the DWH event. On the other hand, lessons were learned from the DWH event may 

lessen the severity of a future spill; therefore, some effects on recreation may be lessened in the future. 

Lessons learned from the DWH event may also lower the probability of a future catastrophic oil spill. 

The cumulative impact of the CPA proposed action to these effects is small since the probability of 

another spill on the scale of the DWH event is quite low. 

Summary and Conclusion 

The CPA proposed action would contribute to low levels of aesthetic and space-use conflict with 

recreational activity that is expected to result cumulatively from the impacting factors. This is because 

much of the activities associated with the proposed action would be removed from recreational areas. Oil 

spills could also contribute to the overall degradation being experienced by beach and wetland-based 

recreational resources, but these are usually localized and small-scale events. The dynamics of any 

possible future large-scale oil spill would also be influenced by the damage done and lessons learned from 

the DWH event. However, the cumulative impact of the CPA proposed action to recreational resources is 

small since the incremental increase in the probability of a large spill is also low. 

4.1.1.20. Archaeological Resources 

The BOEMRE has reexamined the analysis for archaeological resources presented in the Multisale 

EIS and the 2009-2012 Supplemental EIS. Archaeological resources are any material remains of human 

life or activities that are at least 50 years of age and that are of archaeological interest (30 CFR 250.105). 

This Supplemental EIS is based upon additional information available since the publication of these two 

documents and in consideration of the DWH event. Substantial new information that alters the impact 

conclusion for archaeological resources presented in the Multisale EIS and the 2009-2012 Supplemental 

EIS has come to light as a result of BOEMRE-sponsored studies and industry surveys; specifically, 

reports of damage to significant cultural resources (i.e., historic shipwrecks) have been confirmed in lease 

areas >200 m (656 ft) deep where no survey data was available. Although the exact cause of this damage 

is unknown, it may be linked to postlease bottom-disturbing activities. As part of the environmental 

reviews conducted for postlease activities, available information will be evaluated regarding the potential 

presence of archaeological resources within the proposed action area to determine if mitigation is 

warranted. 

4.1.1.20.1. Historic 

4.1.1.20.1.1. Description of the Affected Environment 

A detailed description of historic archaeological resources can be found in Chapter 3.3.4.1 of the 

Multisale EIS. Additional information for the additional 181 South Area and any new information since 
4-302 Central Planning Area Supplemental EIS 

the publication of the Multisale EIS is presented in Chapter 4.1.15 of the 2009-2012 Supplemental EIS. 

The following information is a summary of the resource description incorporated from the Multisale EIS, 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

With the exception of the Ship Shoal Lighthouse structure, historic archaeological resources on the 

OCS consist of historic shipwrecks. A historic shipwreck is defined as a submerged or buried vessel, at 

least 50 years old, that has foundered, stranded, or wrecked and that is currently lying on or is embedded 

in the seafloor. This includes vessels that exist intact or as scattered components on or in the seafloor. 

The National Park Service (NPS) and this Agency contracted three studies (CEI, 1977; Garrison et 

al., 1989; Pearson et al., 2003) aimed at modeling areas in the GOM where historic shipwrecks are most 

likely to exist. The 1977 study concluded that two-thirds of the total number of shipwrecks in the 

northern Gulf lie within 1.5 km (1 mi) of shore and most of the remainder lie between 1.5 and 10 km 

(1 and 6 mi) of the coast (CEI, 1977). The 1989 study found that changes in the late 19th- and early 20thcentury sailing routes increased the frequency of shipwrecks in the open sea in the eastern Gulf to nearly 

double that of the central and western Gulf (Garrison et al., 1989). The Garrison study also found the 

highest observed frequency of shipwrecks occurred within areas of intense marine traffic, such as the 

approaches and entrances to seaports and the mouths of navigable rivers and straits. 

Pearson et al. (2003) benefited from the experience of almost 15 years of high-resolution, shallow 

hazard surveys in lease blocks (a typical lease block is 9 mi2

 [5,760 ac]) and along pipeline routes. Some 

of these surveys (almost exclusively for pipeline routes) were conducted in deep water. Several of these 

pipeline hazard surveys succeeded in locating historic ships, ranging in age from an 18th-century armed 

sailing ship to a World War II German U-boat. 

Historic shipwrecks have, to date, been discovered through oil industry sonar surveys in water depths 

up to 6,500 ft (1,891 m). In fact, in the last 5 years, over a dozen shipwrecks have been located in deep 

water and nine of these ships have been confirmed visually as historic vessels. Many of these wrecks 

were not previously known to exist in these areas from the historic record. Taking these discoveries into 

account, the 2003 study then recommended including some deepwater areas, primarily on the approach to 

the Mississippi River, among those lease areas requiring archaeological investigation. With this in mind, 

BOEMRE revised its guidelines for conducting archaeological surveys and added about 1,200 lease 

blocks to the list of blocks requiring an archaeological survey and assessment. These requirements are 

posted on the BOEMRE website under NTL 2005-G07 and NTL 2008-G20. Since implementation of 

these new lease blocks on July 1, 2005, at least 39 possible historic sites have been reported in this area. 

Recent research on historic shipping routes, moreover, suggests that the ultra-deepwater area of the Gulf 

of Mexico, between 25o and 27.5o N. latitude, was located along the historic Spanish trade route, which 

therefore increases the probability that a historic shipwreck could be located in this area (Lugo-Fernandez 

et al., 2007). This route runs through the proposed sale areas, and much of this area is not currently 

identified as requiring an archaeological assessment. A study to conduct archival research on these 

historic shipping routes was completed in 2010 (Krivor et al., in press) and concluded that both Spanish 

and French vessels were lost in the 16th, 17th, and 18th centuries while transiting the route between Vera 

Cruz, New Orleans, and Havana. 

The BOEMRE shipwreck database currently lists 959 wrecks in the CPA (Table 4-21). Many of 

these reported shipwrecks may be considered historic and could be eligible for nomination to the National 

Register of Historic Places. Most of these wrecks are known only through the historical record and, to 

date, have not been located on the ocean floor. This list should not be considered exhaustive. Regular 

reporting of shipwrecks did not occur until late in the 19th century, and losses of several classes of 

vessels, such as small coastal fishing boats, were largely unreported in official records. There have been 

34 historic wrecks positively identified in the CPA, over half of which have been found in deepwater 

blocks in Mississippi Canyon, Green Canyon, and Viosca Knoll. Nearly all of these have been 

discovered as a result of BOEMRE-mandated oil industry surveys. The discoveries include two late 18thto early 19th-century wooden sailing vessels, one lying in nearly 2,700 ft (823 m) of water (Atauz et al., 

2006) and the other in 4,000 ft (1,219 m) of water (Ford et al., 2008). There are also several World War 

II casualties located in deep water off the mouth of the Mississippi River (e.g., Alcoa Puritan, GulfPenn, 

Halo, Virginia, Robert E. Lee, and the German submarine U-166) (Church et al., 2007). All of these 

wrecks have been investigated using a remotely operated vehicle from a surface vessel and are in an 

excellent state of preservation. 
Description of the Environment and Impact Analysis 4-303 

Historic shipwrecks also have been identified in shallow water in the CPA. One shipwreck, the 

steamship Josephine (22HR843), currently is listed to the National Register in the CPA (Irion and Ball, 

2001); a second, the Spanish American War gunboat USS Castine, is awaiting final listing by the Keeper 

of the Register. 

Submerged shipwrecks off the coasts of Louisiana, Mississippi, and Alabama are likely to be 

moderately well preserved because of the high sediment load in the water column from upland drainage 

and wind and water erosion. Wrecks occurring in or close to the mouth of bays likely would have been 

quickly buried by transported sediment and therefore somewhat protected from the destructive effects of 

wood-eating shipworms (Teredo navalis) or storms, as has been observed at the site of La Belle in 

Matagorda Bay, Texas, and the Emanuel Point wrecks in Pensacola Bay, Florida. A good example of this 

type of historic wreck is the Emanuel Point Wreck, believed to be part of Spanish explorer Tristan de 

Luna’s fleet lost in Pensacola Bay in 1559 (Smith et al., n.d.; State of Florida, Division of Historic 

Resources, 2010). Wrecks occurring in deeper water also have a moderate to high preservation potential. 

In the deep water, temperature at the seafloor is extremely cold, which slows the oxidation of ferrous 

metals. While the cold water at depth would eliminate the wood-eating shipworm Teredo navalis, it is 

clear from recent studies that other marine organisms consume wooden shipwrecks and that microbial 

organism are at work breaking down steel and iron hulls (Atauz et al., 2006; Church et al., 2007; Church 

and Warren, 2008; Ford et al., 2008). Deepwater shipwreck discoveries continue to be made in the CPA 

off the mouth of the Mississippi River. 

Aside from acts of war, hurricanes cause the greatest number of wrecks in the Gulf. Wrecks 

occurring as a result of an extremely violent storm are more likely to be scattered over a broad area. The 

wreckage of the 19th-century steamer New York, which was destroyed in a hurricane, lies in 16 m (52 ft) 

of water off the coast of Mississippi and has been documented by BOEMRE (Irion and Anuskiewicz, 

1999; Gearhart et al., in press) as scattered over the ocean floor in a swath over 1,500 ft (457 m) long. 

Shipwrecks occurring in shallow water nearer to shore are more likely to have been reworked and 

scattered by subsequent storms than those wrecks occurring at greater depths on the OCS. Historic 

research indicates that shipwrecks occur less frequently in Federal waters. These wrecks are likely to be 

better preserved, less disturbed, and, therefore, more likely to be eligible for nomination to the National 

Register of Historic Places than are wrecks in shallower State waters. 

Recent hurricane activity in the Gulf of Mexico is certain to have impacted archaeological resources 

in shallow water. It is almost certain that any shipwrecks within the path of Hurricanes Katrina or Rita in 

shallow water were impacted to some extent by these storms. In September 2005, NPS conducted a study 

of sites along the Gulf Coast that were impacted by Hurricane Katrina (USDOI, NPS, 2005). This 

assessment identified three types of damage that can occur to archaeological sites: tree throws; storm 

surge, scouring, and erosion; and seabed shifting. On the OCS, the two primary types of damage would 

be associated with storm surge and seabed shifting. Damage from either of these activities could 

adversely affect both prehistoric and historic sites on the OCS. In early 2007, this Agency awarded a 

study to investigate the impacts that recent storm activity may have had on historic shipwrecks in the Gulf 

of Mexico. Remote-sensing surveys for this study were completed in May 2007 and dive operations were 

completed in October 2007. A final report of findings was submitted in 2011. Analysis of the remotesensing surveys and diver investigations indicates that at least 3 of the 10 shipwrecks examined were 

affected by recent storm activity (Gearhart et al., in press). The study also concluded that older, wooden 

hulled vessels became less affected by recent storm events after having settled into an equilibrium within 

their environment, despite being periodically exposed and reburied. 

4.1.1.20.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of routine impacts for the CPA proposed action on historic archaeological 

resources can be found in Chapter 4.2.1.1.12 of the Multisale EIS and in Chapter 4.1.15.2 of the 2009-

2012 Supplemental EIS. The following information is a summary of the impact analysis incorporated 

from the Multisale EIS, the 2009-2012 Supplemental EIS, and new information that has become available 

since both documents were prepared. 
4-304 Central Planning Area Supplemental EIS 

Proposed Action Analysis 

This section discusses the possible effects of routine activities associated with the CPA proposed 

action on archaeological resources. Routine impact-producing factors associated with the CPA proposed 

action that could affect historic archaeological resources include the direct physical contact with a 

shipwreck site; the placement of drilling rigs and production systems on the seafloor; pile driving 

associated with platform emplacement; pipeline placement; dredging of new channels, as well as 

maintenance dredging of existing channels; anchoring activities; pipeline installation; structure removals 

and site clearance; and the masking of archaeological resources from industry-related debris. 

Several OCS-related, impact-producing factors may cause adverse impacts to historic archaeological 

resources. Offshore development could result in a drilling rig, platform, pipeline, dredging activity, or 

anchors having an impact on a historic shipwreck. Direct physical contact with a wreck site could destroy 

fragile ship remains, such as the hull and wooden or ceramic artifacts, and could disturb the site context. 

The result would be the loss of archaeological data on ship construction, cargo, and the social 

organization of the vessel’s crew, and the concomitant loss of information on maritime culture for the 

period from which the ship dates. Industry-related impacts have been found to have occurred in areas 

where remote-sensing surveys had not been previously required (Atauz et al., 2006; Church and Warren, 

2008). Remote-sensing surveys of the seafloor using high-resolution sidescan sonar and magnetometers 

have been found to be an effective means of locating historic submerged properties in order to avoid 

impacts from the undertaking. 

The placement of drilling rigs and production systems has the potential to cause physical impact to 

prehistoric and/historic archaeological resources. The area of seafloor disturbance from each of these 

structures is defined in Chapter 3.1.1.2. Pile driving associated with platform emplacement may also 

cause sediment liquefaction an unknown distance from the piling, disrupting stratigraphy in the area of 

liquefaction. 

According to estimates presented in Table 3-2, 403-697 exploration, delineation, development, and 

production wells would be drilled and 32-44 production platforms would be installed in support of the 

proposed action. Of these, 111-155 exploration, delineation, development and production wells would be 

drilled, and 22-28 platforms would be installed in water depths of 200 m (656 ft) or less, where the 

majority of blocks having the highest potential for historic period shipwrecks are located. The location of 

any proposed activity within a lease that has a high potential for historic shipwrecks requires 

archaeological clearance prior to operations. While the expanded BOEMRE shipwreck database contains 

911 reported shipwrecks in the entire CPA (Table 4-21), this number is believed to represent a fraction of 

the actual number of ships lost in the CPA. Recent research on historic shipping routes, moreover, 

suggests that the ultra-deepwater area of the Gulf of Mexico, between 25o and 27.5o N. latitude, was 

located along the historic Spanish trade route, which therefore increases the probability that a historic 

shipwreck could be located in this area (Lugo-Fernandez et al., 2007). This route runs through the 

proposed sale area, and much of this area had not previously been identified as requiring an 

archaeological assessment. A study to conduct archival research on these historic shipping routes was 

completed in 2010 (Krivor et al., in press) and concluded that both Spanish and French vessels were lost 

in the 16th, 17th, and 18th centuries while transiting the route between Vera Cruz, New Orleans, and 

Havana. In addition, discoveries made since 2005 in newly surveyed deepwater lease blocks in the CPA 

suggest that shipwrecks may occur anywhere on the OCS, and the ability to predict their specific 

locations offshore in the Gulf of Mexico based on a review of historic literature is limited. Of the 12,409 

lease blocks in the CPA, less than 40 percent (4,686) are leased. There are 2,332 blocks that fall within 

the Gulf of Mexico Region’s current high-potential areas for historic resources in the CPA. Of these 

blocks, 812 are in water depths of 200 m (656 ft) or less and would require a survey at 50-m linespacing. 

There are 1,520 blocks in water depths that preclude a survey with a magnetometer and require sidescansonar survey at no more than a 300-m linespacing. The potential of an interaction between rig or platform 

emplacement and a historic shipwreck is greatly diminished by site surveys. In certain circumstances, the 

Regional Director may require the preparation of an archaeological report to accompany the EP, DOCD, 

or DPP, under 30 CFR 250.194. As part of the environmental reviews conducted for postlease activities, 

available information would be evaluated regarding the potential presence of archaeological resources 

within the proposed action area to determine if mitigation is warranted. 
Description of the Environment and Impact Analysis 4-305 

Pipeline placement has the potential to cause a physical impact to prehistoric and/or historic 

archaeological resources. Pipelines placed in water depths of less than 200 ft (61 m) must be buried. 

Burial depths of 3 ft (1 m) are required, with the exception of shipping fairways and anchorage areas, 

where the requirements are 10 ft (3.1 m) and 15 ft (4.6 m), respectively. 

Maintenance dredging in support of activities resulting from the proposed action has the potential to 

impact a historic shipwreck. Impacts from maintenance dredging can be attributed proportionally to the 

users of the navigation channels. The BOEMRE assessment indicates that, under the proposed action, 

<1 percent of the ship traffic is related to OCS use. Therefore, the impact to archaeological sites directly 

attributable to traffic and maintenance dredging as a result of the OCS Program is negligible. Proposed 

action activities represent <1 percent of the usage of the major navigation channels for the CPA. 

Anchoring associated with platform and pipeline emplacement, as well as with service-vessel and 

shuttle-tanker activities, may also physically impact prehistoric and/or historic archaeological resources. 

It is assumed that, during pipeline emplacement, an array of eight 20,000-lb anchors is continually 

repositioned around the pipelaying barge. 

Activities resulting from the proposed action would generate ferromagnetic structures and debris, 

which would tend to mask magnetic signatures of significant historic archaeological resources. The task 

of locating historic resources through an archaeological survey is, therefore, made more difficult as a 

result of leasing activity. 

Explosive seismic charges set off near historic shipwrecks may displace the surrounding sediments 

and cause loss of archaeological information regarding the context of the site. Furthermore, damage may 

result to the associated artifact assemblage. 

Archaeological surveys are assumed to be effective in reducing the potential for an interaction 

between an impact-producing activity and a historic resource. The surveys are expected to be most 

effective in areas where there is only a thin veneer of unconsolidated Holocene sediments. In these areas, 

shipwreck remains are more likely to be exposed at the seafloor where they can be detected by the sidescan sonar as well as the magnetometer. In areas of thicker unconsolidated sediments, shipwreck remains 

are more likely to be completely buried, with detection relying solely on recording an anomalous 

perturbation of the ambient magnetic field. With sites that are buried, and therefore more difficult to 

identify, the preservation potential is higher; thus, the potential for significant archaeological data is also 

higher. At the current survey linespacing requirement of 50 m, studies have concluded that a sizeable 

portion of shipwrecks would be detected on at least one survey line (Garrison et al., 1989; Enright et al., 

2006, p. 129). By the same token, however, “small wooden-hulled vessels, whether machine- or sailpowered, are unlikely to be detected by 300-m (984-ft) surveys in most instances” (Enright et al., 2006, p. 

129). In the CPA, 1,802 lease blocks are designated as having a high potential for containing submerged 

prehistoric sites, but a low potential for historic shipwrecks and are surveyed at a 300-m survey interval. 

In the CPA, 1,520 deepwater (>200 m; 656 ft) lease blocks, designated as having a high probability for 

containing shipwrecks, are beyond the practical range of magnetometers and are surveyed at 300-m 

linespacing using sidescan sonar. 

Summary and Conclusion 

The greatest potential impact to an archaeological resource as a result of the CPA proposed action 

would result from direct contact between an offshore activity (i.e., platform installation, drilling rig 

emplacement, and dredging or pipeline project) and a historic site. Archaeological surveys, where 

required prior to an operator beginning oil and gas activities on a lease, are expected to be effective at 

identifying possible archaeological sites. The technical requirements of the archaeological resource 

reports are detailed in NTL 2005-G07, “Archaeological Resource Surveys and Reports.” Under 30 CFR 

250.194(c) and 30 CFR 250.1010(c), lessees are required to notify this Agency immediately of the 

discovery of any potential archaeological resources. 

Offshore oil and gas activities resulting from the proposed action could impact an archaeological 

resource because of incomplete knowledge on the location of these sites in the Gulf. The risk of contact 

to archaeological resources is greater in instances where archaeological survey data are unavailable. Such 

an event could result in the disturbance or destruction of important archaeological information. 

Archaeological surveys, where required, would provide the necessary information to develop avoidance 

strategies that would reduce the potential for impacts on archaeological resources. 
4-306 Central Planning Area Supplemental EIS 

Except for the projected 0-1 new gas processing plants and 0-1 new pipeline landfall, a CPA proposed 

action would require no new oil and gas coastal infrastructure. It is expected that archaeological 

resources would be protected through the review and approval processes of the various Federal, State, and 

local agencies involved in permitting onshore activities. 

4.1.1.20.1.3. Impacts of Accidental Events 

Background/Introduction 

A detailed impact analysis of the possible effects of accidental impacts associated with the proposed 

WPA lease sale on historic archaeological resources can be found in Chapter 4.4.13.1 of the Multisale 

EIS and in Chapter 4.1.15.3 of the 2009-2012 Supplemental EIS. The following information is a 

summary of the impact analysis incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, 

and new information that has become available since both documents were prepared. 

Proposed Action Analysis 

Impacts to a historic archaeological resource could occur as a result of an accidental spill. A major 

effect from an oil-spill impact would be visual contamination of a historic coastal site, such as a historic 

fort or lighthouse. Such effects would be temporary and reversible. The use of dispersants, however, 

could result in chemical contamination of submerged cultural heritage sites. The effect, if any, of 

chemical dispersant use at the Macondo well site in 2010 on submerged shipwrecks is still not known. It 

is known that there are at least seven historically significant sites within 20 mi (32 km) of the well site. A 

recent site investigation of corals approximately 7 mi (11 km) from the Macondo well site revealed that 

the corals were impacted by the oiling event. “Here is a lot of dead coral, dying coral, dying associates, 

even a dead golden crab in the field. Much of the coral is covered by what looks like oily gunk” (Fisher, 

personal communication, 2010). This has implications for the oiling of shipwreck sites and the 

microbiological organisms that are consuming these steel-hulled vessels. According to Church et al., the 

observed bioaccumulation of oxidized forms of iron at the site of Alcoa Puritan, generated by microbial 

activity in 2004 (located 12 mi [19 km] from the Macondo wellhead), was parallel to the degradation of 

the remains of RMS Titanic (Church et al., 2007, p. 205). This microbial activity may have been 

accelerated or retarded by compounds and elements associated with the release of millions of gallons of 

hydrocarbons in the water column. Currently, little information is known about the impacts of microbial 

activity on wooden shipwreck sites in deep water, and further study is warranted for both wooden 

shipwrecks and steel-hulled vessels to properly assess the impacts on these historically significant 

archaeological resources. 

Other impacts that remain unknown at this time include the effect that the oiling of archaeological 

resources would have on the ability to conduct future chemical and observational analysis on the artifact 

assemblage. Currently, it is unknown if the release of hydrocarbons or of dispersant would impede the 

analysis that may help interpret and understand archaeological resources. 

The major impacts to both coastal historic and prehistoric sites from the Exxon Valdez spill in Alaska 

in 1989 were related to cleanup activities such as the construction or helipads, roads, and parking lots and 

to looting by cleanup crews rather than from the oil itself (Bittner, 1996). As a result, cultural resources 

were recognized as significant early in the response to the DWH event, and archaeologists were 

embedded in SCAT’s and were consulting with cleanup crews. Although the process took several weeks 

to fully form, historic preservation representatives eventually were stationed at both the Joint Incident 

Command as well as each Area Command under the general oversight of the National Park Service to 

coordinate response efforts (Odess, personal communication, 2010). 

Summary and Conclusion 

Accidental events producing oil spills may threaten archaeological resources along the Gulf Coast. 

Should a spill contact a historic archaeological site (including submerged sites), damage might include 

direct impact from oil-spill cleanup equipment, contamination of materials, and/or looting. The major 

effect from an oil-spill impact would be visual contamination of a historic coastal site, such as a historic 

fort or lighthouse. It is expected that any spill cleanup operations would be considered a Federal action 
Description of the Environment and Impact Analysis 4-307 

for the purposes of Section 106 of the NHPA and would be conducted in such a way as to cause little or 

no impacts to historic archaeological resources. Recent research suggests the impact of direct contact of 

oil on historic properties may be long term and not easily reversible without risking damage to fragile 

historic materials (Chin and Church, 2010). Previously unrecorded sites could be impacted by oil-spill 

cleanup operations on beaches and offshore. As indicated in Chapter 4.3.1.8 of the Multisale EIS, it is not 

very likely for an oil spill to occur and contact submerged, coastal or barrier island historic sites as a 

result of the CPA proposed action. 

The potential for spills is low, the effects would generally be temporary and localized, and the 

cleanup efforts would be regulated. The proposed action, therefore, is not expected to result in impacts to 

historic archaeological sites; however, should such an impact occur, unique or significant archaeological 

information could be lost and this impact could be irreversible. 

4.1.1.20.1.4. Cumulative Impacts 

An impact analysis for cumulative impacts in the CPA on historic archaeological resources can be 

found in Chapter 4.5.14.1 of the Multisale EIS and in Chapter 4.1.15.4 of the 2009-2012 Supplemental 

EIS. 

Of the cumulative scenario activities, those that could potentially impact historic archaeological 

resources include the following: (1) the OCS Program; (2) State oil and gas activity; (3) maintenance 

dredging; (4) OCS sand borrowing; (5) artificial rigs-to-reef development; (6) offshore LNG projects; (7) 

renewable energy and alternative use conversions; (8) commercial fishing; (9) sport diving and 

commercial treasure hunting, and (10) hurricanes. 

Archaeological surveys are assumed to be highly effective in reducing the potential for an interaction 

between an impact-producing activity and a historic resource. The surveys are expected to be most 

effective in areas where there is only a thin veneer of unconsolidated Holocene sediments. In these areas, 

shipwreck remains are more likely to be exposed at the seafloor where they can be detected by the sidescan sonar as well as the magnetometer. In areas of thicker unconsolidated sediments, shipwreck remains 

are more likely to be completely buried with detection relying solely on magnetometer. 

According to estimates presented in Table 4-4 of the Multisale EIS, an estimated 38,677-45,338 

exploration, delineation, and development wells would be drilled, and 2,958-3,262 production platforms 

would be installed as a result of the OCS Program. Of this range, between 19,840 and 22,216 

exploration, delineation, and development wells would be drilled, and 2,779-2,991 production structures 

would be installed in water depths of 200 m (656 ft) or less. The majority of lease blocks in this water 

depth have a high potential for historic shipwrecks. Archaeological surveys were first required for Lease 

Sale 32 held in December 1973; therefore, it is assumed that any major impacts to historic resources that 

may have occurred resulted from development prior to this time. 

Of the 17,649 lease blocks in the OCS Program area, less than half of these blocks are leased. There 

are 2,938 blocks that fall within the Gulf of Mexico Region’s high-potential areas for historic resources. 

Of these blocks, 1,395 blocks are in water depths of 200 m (656 ft) or less and would require a survey at 

50-m linespacing. The potential of an interaction between MODU or platform emplacement and a 

historic shipwreck is greatly diminished by requisite site surveys, but it still exists. Such an interaction 

could result in the loss of or damage to significant or unique historic resources. 

Table 4-4 of the Multisale EIS indicates that the placement of between 9,470 and 66,550 km (5,884-

41,352 mi) of pipelines is projected in the cumulative activity area. While the required archaeological 

survey minimizes the chances of impacting a historic shipwreck, there remains a possibility that a wreck 

could be impacted by pipeline emplacement. Such an interaction could result in the loss of significant or 

unique historic resources. 

The setting of anchors for drilling rigs, platforms, and pipeline lay barges, and anchoring associated 

with oil and gas service-vessel trips to the OCS have the potential to impact historic wrecks. 

Archaeological surveys serve to minimize the chance of impacting historic wrecks; however, these 

surveys are not infallible and the chance of an impact from future activities does exist. Impacts from 

anchoring on a historic shipwreck may have occurred. There is also a potential for future impacts from 

anchoring on a historic shipwreck. Such an interaction could result in the loss of or damage to significant 

or unique historic resources and the scientific information they contain. 
4-308 Central Planning Area Supplemental EIS 

The probabilities of offshore oil spills 1,000 bbl occurring from OCS Program activities is presented 

in Chapter 3.1.1.3. Oil spills have the potential to impact coastal historic sites directly or indirectly by 

physical impacts caused by oil-spill cleanup operations. The impacts caused by oil spills to coastal 

historic archaeological resources are generally short term and reversible. Table 4-22 presents the coastal 

spill scenario from both OCS and non-OCS sources. It is assumed that the majority of the spills would 

occur around terminals and be contained in the vicinity of the spill. Should such oil spills contact a 

historic site, the effects would be temporary and reversible. 

Most channel dredging occurs at the entrances to bays, harbors, and ports. These areas have a high 

potential for historic shipwrecks; the greatest concentrations of historic wrecks are likely associated with 

these features (Pearson et al., 2003). It is reasonable to assume that significant or unique historic 

archaeological information has been lost as a result of past channel dredging activity. In many areas, 

COE requires remote-sensing surveys prior to dredging activities to minimize such impacts. 

Past, present, and future OCS oil and gas exploration and development and commercial trawling 

would result in the deposition of tons of ferromagnetic debris on the seafloor. Modern marine debris 

associated with these activities would tend to mask the magnetic signatures of historic shipwrecks, 

particularly in areas that were developed prior to requiring archaeological surveys. Such masking of the 

signatures characteristic of historic shipwrecks may have resulted or may yet result in OCS activities in 

the cumulative activity area impacting a shipwreck containing significant or unique historic information. 

State oil and gas program wells, structures, and pipelines in State waters are not under the jurisdiction 

of BOEMRE with respect to the archaeological resource protection requirements of the NHPA. However, 

other Federal agencies, such as COE, which issues permits associated with pipelines in State waters, are 

responsible for the protection of archaeological resources under the NHPA. Therefore, the impacts that 

might occur to archaeological resources by pipeline construction originating from OCS-related activity 

within State waters should be mitigated under the requirements of the NHPA, and the same 

archaeological surveys for planned pipelines that lead into a landfall or a tie-in to a pipeline in State 

waters are required. Prior to 1989, it is possible that explosive seismic surveys on the OCS and within 

State waters could have impacted historic shipwrecks. Explosive seismic charges set near historic 

shipwrecks could have displaced the vessel’s surrounding sediments, acting like a small underwater fault 

and moving fragile wooden, ceramic, and metal remains out of their initial cultural context. Such an 

impact would have resulted in the loss of significant or unique archaeological information. 

Maintenance dredging takes place in existing, often well-used, and marked seaways and transit 

corridors within which any historic wrecks would have been already disturbed or their historical context 

destroyed. Most channel dredging occurs at the entrances to bays, harbors, and ports. These areas have a 

high potential for historic shipwrecks; the greatest concentrations of historic wrecks are likely associated 

with these features (Pearson et al., 2003). It is reasonable to assume that significant or unique historic 

archaeological information has been lost as a result of past channel dredging activity. In many areas, 

COE requires remote-sensing surveys prior to dredging activities to minimize such impacts. Routine 

maintenance dredging, as an ongoing activity in well-plied channels, is not likely to result in any new 

disturbance or disruption to historic wrecks. 

The OCS sand borrowing is expected to be an activity on the increase during the OCS cumulative 

activities period. Approximately 76 million yd3

 of OCS sand is liable to be accessed for coastal 

restorations over the next 5-10 years from Ship Shoal Blocks 88 and 89 and from South Pelto Blocks 12 

and 13, primarily. For these bottom-disturbing activities, a preconstruction archaeological survey is 

required by BOEMRE for the borrow site lease. No new disturbance of historic shipwrecks would be 

expected when a predeployment archaeological survey of sand borrow sites is first examined for seabottom anomalies by BOEMRE so that the proper setback distances can be required that allow potential 

resources to be avoided. 

Artificial reef development, offshore LNG projects, and renewable energy projects and alternative use 

conversions are expected to remain at, respectively, a steady pace of activity, to decrease, and to increase 

as competing uses of the OCS. A preconstruction archaeological survey is required before bottomdisturbing activities are permitted for artificial reef emplacement (if not reefed on site), deepwater ports 

for LNG facilities, and newly built renewable energy facilities. Alternative-use conversions of existing 

infrastructure likely would not involve new bottom-disturbing activities, but if called for in applications, a 

preconstruction survey would be required. No new disturbance of historic shipwrecks would be expected 

when predeployment archaeological surveys are first examined for sea-bottom anomalies by BOEMRE, 
Description of the Environment and Impact Analysis 4-309 

or the permitting agency, so that proper setback distances can be required that allow mitigation potential 

resources to be avoided. 

Commercial fishing trawling activity specifically would only affect the uppermost portions of the 

sediment column (Garrison et al., 1989) in water depths generally <600 ft (183 m). On many wrecks, the 

uppermost portions would already be disturbed by natural factors and would contain only artifacts that 

have lost all original context. 

Sport diving, which is generally restricted to water depths <130 ft (40 m), and commercial treasure 

hunting are significant factors in the loss of historic data from wreck sites. Efforts to educate sport divers 

and to foster the protection of historic shipwrecks, such as those of the Florida Keys National Marine 

Sanctuary and the Florida Public Archaeology Network, serve to lessen these potential impacts. While 

commercial treasure hunters generally impact wrecks with intrinsic monetary value, sport divers may 

collect souvenirs from all types of wrecks within their diving limits. Since the extent of these activities is 

unknown, the impact cannot be quantified. A Spanish war vessel, El Cazador, was discovered in the 

CPA; it contained a large amount of silver coins and has been impacted by treasure hunting salvage 

operations (McLaughlin, 1995). The historic data available from this wreck and from other wrecks that 

have been impacted by treasure hunters and sport divers represent a significant or unique loss. 

Hurricanes and tropical storms are normal occurrences in the GOM and along the Gulf Coast. On 

average, 15-20 hurricanes make landfall along the northern Gulf Coast per decade. Shipwrecks in 

shallow waters are exposed to a greatly intensified, longshore current during tropical storms (Clausen and 

Arnold, 1975). Under such conditions, it is highly likely that artifacts (e.g., ceramics and glass) would be 

dispersed. Some of the original information contained in the site would be lost in this process, but a 

significant amount of information would also remain. Overall, a significant loss of data from historic 

sites has probably occurred, and will continue to occur, in the northeastern Gulf from the effects of 

tropical storms. Some of the data lost have most likely been significant or unique. 

Summary and Conclusion 

Several impact-producing factors may threaten historic archaeological resources, all related to 

bottom-disturbing activities. An impact could result from contact between a historic shipwreck located 

on the OCS and OCS Program or State oil and gas activities (i.e., pipeline and platform installations, 

drilling rig emplacement and operation, dredging, anchoring activities, structure removal, and site 

clearance). Bottom-disturbing activities on the OCS also include maintenance dredging, sand borrowing, 

transported artificial reef emplacement, LNG facility construction, and renewable energy facility 

construction. With the exception of maintenance dredging, preconstruction surveys may be required by 

BOEMRE or the permitting agency. Impacts resulting from the imperfect knowledge of the location of 

historic resources may still occur in areas where a high-resolution survey is only required at 300-m (98-ft) 

survey intervals. The OCS development prior to requiring archaeological surveys has been documented 

to have impacted wrecks containing significant or unique historic information. This was amply 

demonstrated when a pipeline was laid across a previously unknown early 19th-century shipwreck and 

when an MODU mooring anchor chain cut a shipwreck in half (Atauz et al., 2006; Church and Warren, 

2008). The archaeological resources regulation at 30 CFR 250.194 grants authority in certain cases to 

each BOEMRE Regional Director to require archaeological reports to be submitted with the EP, DOCD, 

or DPP where deemed necessary. As part of the environmental reviews conducted for postlease activities, 

available information will be evaluated regarding the potential presence of archaeological resources 

within the proposed action area to determine if mitigation is warranted. 

The loss or discard of ferromagnetic debris associated with oil and gas exploration and development 

and trawling activities could result in the masking of historic shipwrecks or the identification of false 

negatives on archaeological surveys (an anomaly that does not appear to be of historical significance, but 

actually is). 

Damage to or loss of significant or unique historic archaeological information from commercial 

fisheries (trawling) is highly likely in water depths <600 ft (183 m) (Foley, 2010). It is expected that 

maintenance dredging, commercial bottom trawling, sport-diving and commercial treasure hunting, and 

hurricanes and tropical storms have impacted and would continue to impact historic period shipwrecks on 

the shelf where such activities occur. 
4-310 Central Planning Area Supplemental EIS 

Development onshore as a result of the proposed action could result in the direct physical contact 

between a historic site and pipeline trenching. It is assumed that archaeological investigations prior to 

construction would serve to mitigate these potential impacts. The expected effects of oil spills on historic 

coastal resources are temporary and reversible. 

The effects of the various impact-producing factors discussed in this analysis have likely resulted in 

the loss of significant or unique historic archaeological information. In the case of factors related to OCS 

Program activities of the past within the cumulative activity area, it is reasonable to assume that most 

impacts would have occurred prior to 1973 (the date of initial archaeological survey and site-clearance 

requirements). Future OCS Program activities and the bottom-disturbing activities permitted by 

BOEMRE and other agencies may require preconstruction archaeological surveys that, when completed, 

are highly effective in identifying bottom anomalies that could be avoided or investigated before bottomdisturbing activities begin. When surveys are not required, it is impossible to anticipate what might be 

imbedded in or lying directly on the seafloor, and impacts to these sites are likely to be major in scale. 

Despite diligence in site-clearance survey reviews, there is still the possibility of an unanticipated 

interaction between bottom-disturbing activity (i.e., rig emplacement, pipeline trenching, anchoring, and 

other ancillary activities) and a historic shipwreck. The incremental contribution of the proposed action is 

expected to be very small due to the efficacy of the remote-sensing surveys and archaeological reports, 

where required. 

4.1.1.20.2. Prehistoric 

4.1.1.20.2.1. Description of the Affected Environment 

A detailed description of prehistoric archaeological resources can be found in Chapter 3.3.4.2 of the 

Multisale EIS. Additional information for the additional 181 South Area and any new information since 

the publication of the Multisale EIS is presented in Chapter 4.1.15 of the 2009-2012 Supplemental EIS. 

The following information is a summary of the resource description incorporated from the Multisale EIS, 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

Available evidence suggests that sea level in the northern GOM was at least 90 m (295 ft), and 

possibly as much as 130 m (427 ft), lower than present sea level during the period 20,000-17,000 years 

B.P. (Nelson and Bray, 1970). Sea level in the northern Gulf reached its present stand around 3,500 years 

B.P. (Pearson et al., 1986). 

During periods that the continental shelf was exposed above sea level, the area was open to habitation 

by prehistoric peoples. The advent of early man into the GOM region is currently accepted to be around 

12,000 years B.P. (Aten, 1983). The sea-level curve for the northern GOM proposed by Coastal 

Environments, Inc. (CEI) suggests that sea level at 12,000 years B.P. would have been approximately 

45-60 m (148-197 ft) below the present-day sea level (CEI, 1977 and 1982). On this basis, the 

continental shelf shoreward of the 45- to 60-m (148- to 197-ft) bathymetric contours has potential for 

prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the depth of sea 

level and the entry date of prehistoric man into North America, this Agency adopted the 60-m (197-ft) 

water depth as the seaward extent for archaeological site potential in the GOM region. 

Based on their 1977 baseline study, CEI (1977) proposed that sites analogous to the types of sites 

frequented by Paleo-Indians can be identified on the now-submerged shelf. Geomorphic features that 

have a high potential for associated prehistoric sites include barrier islands and back-barrier embayments, 

river channels and associated floodplains and terraces, and salt-dome features. Remote-sensing surveys 

have been very successful in identifying these types of geographic features, which have a high potential 

for associated prehistoric sites. Recent investigations in Louisiana and Florida indicate the moundbuilding activity by prehistoric inhabitants may have occurred as early as 6,200 years B.P. (cf. Haag, 

1992; Saunders et al., 1992; Russo, 1992). Therefore, manmade features, such as mounds, may also exist 

in the shallow inundated portions of the OCS. 

Regional geological mapping studies by BOEMRE allow interpretations of specific geomorphic 

features and assessments of archaeological potential in terms of age, the type of system the geomorphic 

features belong to, and geologic processes that formed and modified them. The potential for site 

preservation must also be considered as an integral part of the predictive model. In general, sites 

protected by sediment overburden have a high potential for preservation from the destructive effects of 
Description of the Environment and Impact Analysis 4-311 

marine transgression. The same holds true for sites submerged in areas subjected to low wave energy and 

for sites on relatively steep shelves, which were inundated during periods of rapid rise in sea level. 

Although many specific areas in the Gulf having a high potential for prehistoric sites have been identified 

through archaeological surveys, industry generally has chosen to avoid these areas rather than conduct 

further investigations. 

Surveys from other areas of the western part of the CPA have produced evidence of floodplains, 

terracing, and point-bar deposits in association with relict late Pleistocene fluvial systems. Prehistoric 

sites associated with these features would have a high potential for preservation. Salt diapirs with 

bathymetric expression have also been recorded during lease-block surveys in this area. Solution features 

at the crest of these domes would have a high potential for preservation of associated prehistoric sites. 

The Salt Mine Valley site on Avery Island is a Paleo-Indian site associated with a salt-dome solution 

feature (CEI, 1977). The proximity of most of these relict landforms to the seafloor facilitates further 

investigation and data recovery. 

The Holocene history of southeastern Louisiana is extremely complex and characterized by 

overlapping deltaic lobes. Prehistoric terrestrial sites inhabited during active buildout of the old deltas 

and during early stages of their deterioration can be anticipated in shallow shelf areas. A large number of 

prehistoric sites have likely been encapsulated in the alluvial deposits of older deltaic lobes but through a 

combination of subsidence, and rapid deposition could be buried by as much as 300 ft (91 m) of Holocene 

sediment. 

A good-faith effort was made to identify any impacts to known prehistoric sites in the Central GOM 

as a result of recent hurricane activity; however, no such information was identified. It is unlikely that 

Hurricane Katrina would have affected any prehistoric sites on the OCS because of the deep burial of the 

Pleistocene surface. 

4.1.1.20.2.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of the possible effects of routine impacts associated with the CPA 

proposed action on prehistoric archaeological resources can be found in Chapter 4.2.1.1.12.2 of the 

Multisale EIS and in Chapter 4.1.15.2 of the 2009-2012 Supplemental EIS. The following information is 

a summary of the impact analysis incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, 

and new information that has become available since both documents were prepared

Proposed Action Analysis 

Blocks with a high potential for prehistoric archaeological resources are found landward of the 

12,000-years-B.P. shoreline position, which is roughly approximated by the last geologic still-stand 

before inundation at approximately 13,000 years B.P. This 13,000-years-B.P. still-stand also roughly 

follows the 45-m (148-ft) bathymetric contour. Because of inherent uncertainties in both the depth of 

historic sea-level stands and the entry date of prehistoric man into North America, BOEMRE has adopted 

the 60-m (197-ft) water depth as the seaward extent of the area considered to have potential for 

prehistoric archaeological resources. 

Offshore development as a result of the CPA proposed action could result in an interaction between a 

drilling rig, platform, pipeline, dredging activity, or anchors and an inundated prehistoric site. This direct 

physical contact with a site could destroy fragile artifacts or site features and could disturb artifact 

provenance and site stratigraphy. The result would be the loss of archaeological data on prehistoric 

migrations, settlement patterns, subsistence strategies, and archaeological contacts for North America, 

Central America, South America, and the Caribbean. 

The placement of drilling rigs and production systems has the potential to cause physical impact to 

prehistoric archaeological resources. Pile driving associated with platform emplacement may also cause 

sediment liquefaction an unknown distance from the piling, disrupting stratigraphy in the area of 

liquefaction. 

Pipeline placement has the potential to cause a physical impact to prehistoric archaeological 

resources. Pipelines placed in water depths of <60 m (200 ft) must be buried. Burial depths of 3 ft (1 m) 

are required, with the exception of shipping fairways and anchorage areas, where the requirements are 10 
4-312 Central Planning Area Supplemental EIS 

ft (3.1 m) and 15 ft (4.6 m), respectively. Anchoring associated with platform and pipeline emplacement, 

as well as with service-vessel and shuttle-tanker activities, may also physically impact prehistoric 

archaeological resources. It is assumed that, during pipeline emplacement, an array of eight 20,000-lb 

anchors is continually repositioned around the pipelaying barge. 

Onshore prehistoric archaeological resources include sites, structures, and objects such as shell 

middens, earth middens, campsites, kill sites, tool manufacturing areas, ceremonial complexes, and 

earthworks. Prehistoric sites that have yet to be identified would have to be assessed after discovery to 

determine the uniqueness or significance of the information that they contain. Sites already listed in the 

National Register of Historic Places and those considered eligible for the Register have already been 

evaluated as having the potential for making a unique or significant contribution to science. Of the 

unidentified coastal prehistoric sites that could be impacted by onshore development, some may contain 

unique information. 

Onshore development as a result of the proposed action could result in direct physical contact 

between construction of new onshore facilities or a pipeline landfall and a previously unidentified 

prehistoric site. Direct physical contact with a prehistoric site could destroy fragile artifacts or site 

features and could disturb the site context. The result would be the loss of information on the prehistory 

of North America and the Gulf Coast region. 

Since all platform locations within the high-potential areas for the occurrence of offshore prehistoric 

archaeological resources are given archaeological clearance prior to setting the structure, removal of the 

structure should not result in any adverse impact to archaeological resources. This is consistent with the 

findings of the Programmatic Environmental Assessment: Structure Removal Activities, Central and 

Western Gulf of Mexico Planning Areas (USDOI, MMS, 1987). 

Except for the projected 0-1 new gas processing plant and 0-1 new pipeline landfall, the proposed 

action would require no new oil and gas coastal infrastructure. Any facility constructed must receive 

approval from the pertinent Federal, State, county, and community involved. Protection of archaeological 

resources in these cases is expected to be achieved through the various approval processes involved. 

There should, therefore, be no impact to onshore prehistoric sites from onshore development related to the 

proposed action. 

In order to reduce the risk of impacting a prehistoric archaeological resource during a BOEMREpermitted activity, BOEMRE requires a 300-m (984-ft), remote-sensing survey linespacing for lease 

blocks that have been identified as having a high potential for containing prehistoric resources. The 

current NTL—NTL 2005-G07, effective July 1, 2005—supersedes all other archaeological NTL’s and 

Letters to Lessees and Operators, and it clarifies the updated information to reflect current technology. 

The list of lease blocks requiring an archaeological survey and assessment are identified in NTL 2008-

G20. 

Summary and Conclusion 

The greatest potential impact to an archaeological resource as a result of a CPA proposed action 

would result from direct contact between an offshore activity (i.e., platform installation, drilling rig 

emplacement, and dredging or pipeline project) and a prehistoric site. Prehistoric archaeological sites are 

thought potentially to be preserved shoreward of the 45-m (148-ft) bathymetric contour, where the Gulf of 

Mexico continental shelf was subaerially exposed during the Late Pleistocene. The archaeological 

survey, where required prior to an operator beginning oil and gas activities on a lease, is expected to be 

somewhat effective at identifying submerged landforms that could support possible archaeological sites. 

NTL 2005-G07 suggests a 300-m (984-ft) linespacing for remote-sensing surveys of leases within areas 

having a high potential for prehistoric sites. While surveys provide a reduction in the potential for a 

damaging interaction between an impact-producing factor and a prehistoric archaeological site, there is a 

possibility of an OCS activity contacting an archaeological site because of an insufficiently dense survey 

grid. Should such contact occur, there would be damage to or loss of significant and/unique 

archaeological information. Except for the projected 0-1 new gas processing plants and 0-1 new pipeline 

landfall, a CPA proposed action would require no new oil and gas coastal infrastructure. It is expected 

that archaeological resources would be protected through the review and approval processes of the 

various Federal, State, and local agencies involved in permitting onshore activities. 
Description of the Environment and Impact Analysis 4-313 

4.1.1.20.2.3. Impacts of Accidental Events 

Background/Introduction 

A detailed impact analysis of the possible effects of accidental impacts associated with the CPA 

proposed action on prehistoric archaeological resources can be found in Chapter 4.4.13.2 of the Multisale 

EIS and in Chapter 4.1.15.3 of the 2009-2012 Supplemental EIS. The following information is a 

summary of the impact analysis incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, 

and new information that has become available since both documents were prepared. 

Proposed Action Analysis 

Impacts to a prehistoric archaeological resource could occur as a result of an accidental spill. A 

major effect from an oil-spill impact would be visual contamination of a historic coastal site, such as a 

historic fort or lighthouse. Such effects would be temporary and reversible. The use of dispersants, 

however, could result in chemical contamination of submerged cultural heritage sites. The effect, if any, 

of chemical dispersant use at the Macondo well site on submerged shipwrecks is still not known. The 

major impacts to both coastal historic and prehistoric sites from the Exxon Valdez spill in Alaska in 1989 

were related to cleanup activities such as the construction of helipads, roads, and parking lots and to 

looting by cleanup crews rather than from the oil itself (Bittner, 1996). As a result, cultural resources 

were recognized as significant early in the response to the DWH event, and archaeologists were 

embedded in SCAT’s and were consulting with cleanup crews. Although the process took several weeks 

to fully form, historic preservation representatives eventually were stationed at both the Joint Incident 

Command as well as each Area Command under the general oversight of the National Park Service to 

coordinate response efforts (Odess, personal communication, 2010). 

Summary and Conclusion 

Accidental events producing oil spills may threaten archaeological resources along the Gulf Coast. 

Should a spill contact a prehistoric archaeological site, damage might include loss of radiocarbon-dating 

potential, direct impact from oil-spill cleanup equipment, and/or looting. Previously unrecorded sites 

could be impacted by oil-spill cleanup operations on beaches. As indicated in Chapter 4.3.1.8 of the 

Multisale EIS, it is not very likely for an oil spill to occur and contact coastal and barrier island 

prehistoric sites as a result of a CPA proposed action. The proposed action, therefore, is not expected to 

result in impacts to prehistoric archaeological sites. 

4.1.1.20.2.4. Cumulative Impacts 

An impact analysis for cumulative impacts in the CPA on prehistoric archaeological resources can be 

found in Chapter 4.5.14.2 of the Multisale EIS and in Chapter 4.1.15.4 of the 2009-2012 Supplemental 

EIS. The following information is a summary of the impact analysis incorporated from the Multisale EIS, 

2009-2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

Future OCS exploration and development activities in the Gulf of Mexico between 2007 and 2046, 

which can be found in Table 4-4 of the Multisale EIS, projects drilling 12,966-14,187 exploration, 

delineation, and development wells in water depths <60 m (197 ft). Relative sea-level curves for the Gulf 

of Mexico indicate there is no potential for the occurrence of prehistoric archaeological sites in water 

depths greater than 60 m (197 ft). Archaeological surveys are assumed to be highly effective in reducing 

the potential for an interaction between an impact-producing activity and a prehistoric resource. 

Archaeological surveys were first required for Lease Sale 32 held in December 1973; therefore, it is 

assumed that the major impacts to prehistoric resources that may have occurred resulted from 

development prior to this time. The potential of an interaction between rig or platform emplacement and 

a prehistoric site is diminished by the survey, but it still exists. Such an interaction would result in the 

loss of or damage to significant or unique prehistoric information. 

The placement of 2,980-22,110 km (1,852-13,739 mi) and 2,340-9,580 km (1,454-5,953 mi) of 

pipelines in water depths <60 m (197 ft) is projected as a result OCS Program activities in the CPA and 
4-314 Central Planning Area Supplemental EIS 

WPA, respectively. For the OCS Program, 5,320-31,690 km (5,320-19,691 mi) of pipelines are projected 

in water depths <60 m (197 ft). While archaeological surveys minimize the chances of impacting a 

prehistoric site, there remains a possibility that a site could be impacted by pipeline emplacement. Such 

an interaction would result in the loss of significant or unique archaeological information. 

The setting of anchors for drilling rigs, platforms, and pipeline lay barges, and anchoring associated 

with oil and gas service-vessel trips to the OCS have the potential to impact shallowly buried prehistoric 

sites. Archaeological surveys minimize the chance of impacting these sites; however, these surveys are 

not seen as infallible, and the chance of an impact from future activities exists. Impacts from anchoring 

on a prehistoric site may have occurred. Such an interaction could result in the loss of significant or 

unique archaeological information. 

The probabilities of offshore oil spills 1,000 bbl occurring from the OCS Program in the cumulative 

activity area is presented in Chapter 3.3. Oil spills have the potential to impact coastal prehistoric sites 

directly or indirectly by physical impacts caused by oil-spill cleanup operations. Coastal, oil-spill 

scenario numbers are presented in Table 4-13 of the Multisale EIS for both OCS and non-OCS sources. It 

is assumed that the majority of the spills would occur around terminals and would be contained in the 

vicinity of the spill. There is a small possibility of these spills contacting a prehistoric site. The impacts 

caused by oil spills to coastal prehistoric archaeological resources can severely distort information 

relating to the age of the site. Contamination of the organic site materials by hydrocarbons can make 

radiocarbon dating of the site more difficult or even impossible. This loss might be ameliorated by using 

artifact seriation or other relative dating techniques. Coastal prehistoric sites might also suffer direct 

impact from oil-spill cleanup operations as well as looting resulting from interactions between persons 

involved in cleanup operations and unrecorded prehistoric sites. Interaction between oil-spill cleanup 

equipment or personnel and a site could destroy fragile artifacts or disturb site context, possibly resulting 

in the loss of information on the prehistory of North America and the Gulf Coast region. Some coastal 

sites may contain significant or unique information. 

Most channel dredging occurs at the entrances to bays, harbors, and ports. Bay and river margins 

have a high potential for the occurrence and preservation of prehistoric sites. Prior channel dredging has 

disturbed buried and/inundated prehistoric archaeological sites in the coastal plain of the Gulf of Mexico. 

It is assumed that some of the sites or site information were unique or significant. In many areas, COE 

requires surveys prior to dredging activities to minimize such impacts. 

Trawling activity would only affect the uppermost portion of the sediment column (Garrison et al., 

1989). This zone would already be disturbed by natural factors, and site context to this depth would 

presumably be disturbed. Therefore, no effect of trawling on prehistoric sites is assumed. Investigations 

prior to construction can determine whether prehistoric archaeological resources occur at these sites. 

Table 4-9 of the Multisale EIS indicates the projected coastal infrastructure related to OCS Program 

activities in the cumulative activity area. Investigations prior to construction can determine whether 

prehistoric archaeological resources occur at these sites. 

Because BOEMRE does not have jurisdiction over pipelines in State waters, the archaeological 

resource protection requirements of the NHPA are not within BOEMRE’s jurisdiction. However, other 

Federal agencies, such as COE, which lets permits associated with pipelines in State waters, are 

responsible for the protection of archaeological resources under the NHPA. Therefore, the impacts that 

might occur to archaeological resources by pipeline construction within State waters should be mitigated 

under the requirements of the NHPA. 

Over 100 hurricanes have made landfalls along the northern Gulf of Mexico coast from the Florida 

Panhandle to Texas over the past century (Liu and Fearn, 2000; Keim and Muller, 2009). Prehistoric sites 

in shallow waters and on coastal beaches are exposed to the destructive effects of wave action and 

scouring currents. Under such conditions, it is highly likely that artifacts would be dispersed and the site 

context disturbed. Some of the original information contained in the site would be lost in this process. 

Overall, a significant loss of data from prehistoric sites has probably occurred, and will continue to occur, 

in the northeastern Gulf from the effects of tropical storms. 

Summary and Conclusion 

Several impact-producing factors may threaten prehistoric archaeological resources of the Gulf of 

Mexico. An impact could result from a contact between proposed oil and gas activities (including 
Description of the Environment and Impact Analysis 4-315 

pipeline construction, platform installation, drilling rig emplacement and operation, dredging, and 

anchoring activities) and an oil spill and subsequent cleanup efforts. Each of these activities or events 

could damage and destroy a prehistoric archaeological site located on the continental shelf. 

Archaeological surveys, where required, and the resulting archaeological analyses completed prior to an 

operator beginning oil and gas activities on a lease are expected to be highly effective at identifying 

possible prehistoric sites. The OCS development prior to the first required archaeological survey in 1973 

has possibly impacted sites containing significant or unique prehistoric information, and it is possible 

that, even with current survey methods, prehistoric archaeological sites may be missed. No significant 

new information was found at this time that would alter the overall conclusion that cumulative impacts on 

prehistoric archaeological sites associated with the CPA proposed action is expected to be minimal. 

Because of continued regulations and surveys, the potential impact from the CPA proposed action to 

prehistoric archeological resources would be decreased. 

4.1.1.21. Human Resources and Land Use 

4.1.1.21.1. Land Use and Coastal Infrastructure 

The BOEMRE has reexamined the analysis for land use and coastal infrastructure presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, based on the additional information presented below 

and in consideration of the DWH event. While some new information was found, none of it conclusively 

changes the description of environmental effects. It is too early to determine substantial, long-term 

changes as a result of the DWH event and the subsequent drilling suspensions. The BOEMRE anticipates 

that there will be some long-term consequences and these will become apparent over time. Additionally, 

for the interim, BOEMRE recognizes the need to continue monitoring all resources for changes that are 

applicable for land use and infrastructure. Short-term impacts and potential long-term impacts related to 

the DWH event, in general, and the drilling suspensions, in particular, are discussed at the end of the 

chapters below on the “Description of the Affected Environment” (Chapter 4.1.1.21.1.1) and “Impacts of 

Accidental Events” (Chapter 4.1.1.21.1.3). 

A detailed description of the affected environment and full analyses of the potential impacts of 

routine activities and accidental events associated with the CPA proposed action and the proposed 

action’s incremental contribution to the cumulative impacts are presented in the Multisale EIS. A 

summary of those analyses and their reexamination due to new information and the addition of the 181 

South Area was presented in the 2009-2012 Supplemental EIS. The following is a summary of the 

information presented in the Multisale EIS and the 2009-2012 Supplemental EIS, and new information 

that has become available since both documents were prepared. 

The CPA proposed action would not require additional coastal infrastructure, with the possible 

exception of 0-1 new gas processing facility and 0-1 new pipeline landfall, and it would not alter the 

current land use of the analysis area. In fact, as industry responds to the new environment since the lifting 

of the drilling suspensions, increased scrutiny of industry practices post-DWH event, and pending 

regulatory revisions, the 0-1 projection range becomes even more conservative, i.e., it becomes even more 

likely that the number would be zero (Dismukes, personal communication, 2010a). Thus, the existing oil 

and gas infrastructure is expected to be sufficient to handle development associated with the proposed 

action. There may be some expansion at current facilities, but the land in the analysis area is sufficient to 

handle such development. There is also sufficient land to construct a new gas processing plant in the 

unlikely event that one should be needed. However, because the current spare capacity at existing 

facilities should be sufficient to satisfy new gas production, any such a need would likely materialize only 

toward the end of the 40-year life of the proposed action (Dismukes, personal communication, 2010b). 

This excess capacity substantially diminishes the likelihood of new facility construction. Existing solidwaste disposal infrastructure is adequate to support both existing and projected offshore oil and gas 

drilling and production needs. Minor accidental events such as oil or chemical spills, blowouts, and 

vessel collisions would have no long-term negative effects on land use. Coastal or nearshore spills, as 

well as vessel collisions, could have short-term adverse effects on coastal infrastructure, requiring the 

cleanup of any oil or chemicals spilled. The incremental contribution of the proposed action to the 

cumulative impacts on land use and coastal infrastructure are expected to be minor. An analysis of 

impacts from a catastrophic event such as the DWH event can be found in Appendix B.
4-316 Central Planning Area Supplemental EIS 

4.1.1.21.1.1. Description of the Affected Environment 

For the proposed CPA action, the primary region of geographic influence is coastal Louisiana, 

Mississippi, and Alabama. Oil and gas activities are quite limited in the Florida area. Land use in the 

CPA analysis area has not substantially changed since the Multisale EIS (Chapter 3.3.5.1.2) or the 2009-

2012 Supplemental EIS (Chapter 4.1.16.1.1) and that description is summarized below. 

The coastal zone of the northern GOM is not a physically, culturally, or economically homogenous 

unit (Gramling, 1984a). The counties and parishes along the coasts of Louisiana, Mississippi, Alabama, 

and Florida represent some of the most valuable coastline in the U.S. Not only does it include miles of 

recreational beaches and the protection of an extended system of barrier islands, but it also has deepwater 

ports, oil and gas support industries, manufacturing, farming, ranching, and hundreds of thousands of 

acres of wetlands and protected habitat. These counties and parishes vary in their histories and in the 

composition and economic activities of their respective local governments. 

According to the U.S. Department of Agriculture’s Economic Research Service, which classifies 

counties into economic types that indicate primary land-use patterns, 3 of the 90 counties/parishes in the 

analysis area are classified as farming dependent, 6 as mining dependent (suggesting the importance of oil 

and gas development to these local economies), 18 as manufacturing dependent, 24 as government 

employment centers, and 20 as tied to service employment. The Economic Research Service also 

classifies counties in terms of their status as a retirement destination; 25 of the 90 counties/parishes are 

considered major retirement destinations (U.S. Dept. of Agriculture, Economic Research Service, 2004). 

The varied land-use patterns are displayed in Figure 3-16 of the Multisale EIS. 

The BOEMRE defines the analysis area for potential impacts on population, labor, and employment 

as that portion of the GOM coastal zone whose social and economic well-being (population, labor, and 

employment) is directly or indirectly affected by the OCS oil and gas industry. In this description of the 

socioeconomic environment, sets of counties (and parishes in Louisiana) have been grouped on the basis 

of intercounty commuting patterns into LMA’s, as identified by Tolbert and Sizer (1996). The 

methodology employed by Tolbert and Sizer is fully described in the Multisale EIS. Along the Gulf 

Coast, from the southern tip of Texas to Miami and the Florida Keys, 23 LMA’s were identified and 

comprise the 13 BOEMRE-defined EIA’s for the Gulf of Mexico region. The counties and parishes that 

form the LMA’s and EIA’s are listed in Table 4-23, and the EIA’s are visually illustrated in Figure 2-2. 

The LMA’s geographically adjacent to the CPA include Lake Charles, Lafayette, Baton Rouge, 

Houma, and New Orleans, Louisiana; Biloxi-Gulfport, Mississippi; and Mobile, Alabama. The LMA’s 

geographically adjacent to the EPA are all within Florida and include Pensacola, Panama City, 

Tallahassee, Lake City, Gainesville, Ocala, Tampa-St. Petersburg, Sarasota, Ft. Myers, and Miami. Use 

of the LMA geography brings together not only counties immediately adjacent to the GOM but also 

counties tied to coastal counties as parts of functional economic areas. An analysis that encompasses 

where people live as well as where they work permits a more meaningful assessment of the impact of 

offshore oil and gas activities. Because exploration, development, and production activities on the OCS 

draw on existing infrastructural, economic, and labor capacity from across the GOM region, the 

socioeconomic impacts of the proposed action in an individual planning area (WPA, CPA, and EPA) are 

not limited to geographically adjacent areas. For this reason, BOEMRE’s impact analysis analyzes the 

potential impacts in all 13 EIA’s regardless of where the proposed action is taking place. 

The Louisiana coastal area includes broad expanses of marshes and swamps interspersed with ridges 

of higher well-drained land. Southeastern Louisiana is a thriving metropolitan area hosting shipping, 

navigation, U.S. Navy facilities, and oil and chemical refineries. Historically, Terrebonne, Plaquemines, 

and Lafourche Parishes have been the primary staging and support area for offshore oil and gas 

exploration and development. 

Coastal Mississippi includes bays, deltas, marshland, and waterways. Two-thirds of the coast is 

devoted to State-chartered, beachfront gambling enterprises and heavy tourism. One-third is industrial, 

e.g., oil refining and shipbuilding, boat and helicopter facilities, and an onshore support base for drilling 

and production. 

Coastal resource-dependent industries in Alabama include navigation, tourism, marine recreation, 

commercial fishing, and, since its 1979 discovery in State waters, natural gas development and 

production, along with minimal oil production. The military has long had a presence in the area. 
Description of the Environment and Impact Analysis 4-317 

An extensive maritime industry exists in the northern GOM. There is a substantial amount of 

domestic waterborne commerce in the analysis area and also some foreign maritime traffic. For the year 

2005, seven of the leading 25 U.S. ports ranked by total trade tonnage are located in Louisiana, 

Mississippi, Alabama, and Florida (American Association of Port Authorities, 2007). Chapter 3.3.5.6 of 

the Multisale EIS includes a detailed description of the Gulf maritime industry in the analysis area. 

Infrastructure that supports oil and gas exploration and development in the GOM region is far 

reaching and consists of several categories including platform fabrication yards, shipyards, shipbuilding 

manufacturers, service bases, port facilities, pipeline manufacturers, pipecoating yards, waste 

management facilities, transportation facilities, gas processing plants, natural gas storage facilities, LNG 

facilities, refineries, and petrochemical plants, to name a few. 

The OCS-related offshore infrastructure includes offshore production systems, platform fabrication, 

pipelines, barges, service vessels, and helicopters. Chapter 3.3.5.7 of the Multisale EIS describes the 

various types of offshore infrastructure. 

The OCS-related coastal infrastructure is large, supports OCS development, and consists of thousands 

of small and large contractors covering virtually every facet of OCS activity, including service bases, 

construction facilities for platform fabrication, pipecoating, pipelines, shipbuilding, and processing 

facilities such as gas processing plants, refineries and petrochemical plants, as well as terminal facilities 

such as pipeline shore facilities, barge terminals, and it also includes waste disposal facilities. Chapter 

3.3.5.8 of the Multisale EIS details the various types of infrastructure mentioned above. 

See Chapter 3.3.3 of the Multisale EIS for a listing of major public, recreational, and conservation 

areas; Chapter 3.3.5.6 of the Multisale EIS for a discussion of major ports and waterways; and Figures 

3-13 through 3-15 of the Multisale EIS for a description of OCS infrastructure. 

Deepwater Horizon Event 

In response to the DWH event, the Department of the Interior Secretary Ken Salazar imposed 

temporary suspensions on certain offshore drilling. The moratorium was modified on May 27, 2010, to 

allow drilling only in shallow waters less than 500 ft (152 m) deep (USDOI, Office of Public Affairs, 

2010a). However, only a limited amount of drilling has actually resumed because of new information 

requirements as clarified in (NTL 2010-N06), the time it takes for operators to comply, and the increasing 

rate at which BOEMRE is able to process permit applications (Weinstein, 2010). For example, from June 

28, 2010, when new requirements were announced, until September 10, 2010, there were 13 Applications 

to Permit Drilling filed. Of the 13, five had been approved and eight were pending as of September 14, 

2010 (USDOI, Office of Public Affairs, 2010b). On October 12, 2010, the remaining deepwater drilling 

suspension was lifted in its entirety. Operators are in the process of meeting the new requirements issued 

since the DWH event, and BOEMRE continues to review and approve permits and plans. The impacts of 

the suspensions and the temporary interruption in permitting are being experienced at Port Fourchon, 

where rental rates were cut by 30 percent as an incentive for businesses to stay. However, companies 

have removed a large portion of their equipment from the port and there has been a substantial decrease in 

helicopter flights and servicing of rigs. Many companies have had to trim their budgets by cutting hours 

and salaries. Support services companies, such as chemical suppliers, and welders have also been 

affected (Lohr, 2010). The effects of this decreased demand will ripple through the various infrastructure 

categories (e.g., fabrication yard, shipyards, port facilities, pipecoating facilities, gas processing facilities, 

waste management facilities, etc.) and also will affect the oil and gas support sector businesses (e.g., 

drilling contractors, offshore support vessels, helicopter hubs, mud/drilling fluid/lubricant suppliers, etc.). 

The BOEMRE will continue to monitor these infrastructure effects as they evolve over time. 

Land use experienced a more immediate but short-term impact, with temporary waste staging areas 

and decontamination areas that were set up to handle the spill-related waste. Concerns about waste 

management practices were expressed by the government and public (Barringer, 2010). The USEPA, in 

consultation with the Coast Guard, issued solid waste management directives to address the issue of 

contaminated materials and solid or liquid wastes that were recovered as a result to cleanup operations 

(USEPA, 2010k and 2010l). Twenty-five waste staging areas were set up across Louisiana, Mississippi, 

Alabama, and Florida. Six decontamination areas were stationed in Mississippi, Alabama, and Florida. 

The USEPA visited each staging and decontamination area once per week and each landfill two times per 

month, and they documented their findings on the USEPA public website. There were some issues, but 
4-318 Central Planning Area Supplemental EIS 

nothing that would appear to cause a long-term impact (USEPA, 2010m). Additional description of the 

DWH event’s waste stream is found in Chapter 4.1.1.21.4. 

It should be noted that the post-DWH environment in which we find ourselves is dynamic and everchanging. The BOEMRE will continue to monitor these resources over time as long-term impacts to the 

affected environment become more evident. 

4.1.1.21.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed impact analysis of routine events on land use and coastal infrastructure for the CPA 

proposed action can be found in Chapter 4.2.1.1.13.1 of the Multisale EIS. Impact analyses for the 181 

South Area that includes any new information since publication of the Multisale EIS is presented in 

Chapter 4.1.16.1.2 of the 2009-2012 Supplemental EIS. The following information is a summary of the 

impact analysis incorporated from the Multisale EIS, the 2009-2012 Supplemental EIS, and new 

information that has become available since both documents were prepared. 

Proposed Action Analysis 

Impact-producing factors associated with the CPA proposed action that could affect land use and 

coastal infrastructure include (1) gas processing facilities, (2) pipeline landfalls, (3) service bases, (4) 

navigation channels, and (5) waste disposal facilities. 

Chapter 4.1.2.1 of the Multisale EIS and Chapter 3.1.2 of the 2009-2012 Supplemental EIS discuss 

OCS-related coastal infrastructure and projected new coastal infrastructure that may result from the CPA 

proposed action or the OCS Program, including the potential need for the construction of new facilities 

and/or the expansion of existing facilities. Based on current information, the development scenario 

presented in the 2009-2012 Supplemental EIS has been reconsidered and revised for the CPA proposed 

action, but changes have been few. All onshore infrastructure requires permits for construction and 

operation. The BOEMRE is not the permitting agency for these activities. The permitting agencies for 

any onshore infrastructure would be the State in which the activity would occur, and/or COE, and/or 

USEPA. According to the scenario analysis in the 2009-2012 Supplemental EIS, the construction of 0-1 

new gas processing facilities would be expected to occur near the end of the 40-year life of the proposed 

action. Most of the projected new pipeline would be offshore and would tie into the existing offshore 

pipeline infrastructure. According to the scenario analysis, 0-1 new pipeline landfalls would be expected 

to occur toward the end of the 40-year lifespan of the proposed lease sale. According to these BOEMRE 

projections, no other new coastal infrastructure would be expected to result from the proposed action. 

Given the uncertain environment of the post-DWH event, the application of the scenario revised for the 

CPA proposed action is very conservative since the likelihood is diminished that any new gas processing 

facility or pipeline landfall would result from the proposed action. That is, the lingering effects of the 

drilling suspensions, changes in Federal requirements for drilling safety, and the temporary interruption in 

the permit approval process has depressed existing demand for gas processing facilities and pipeline 

landfalls; hence, the likelihood of new gas processing facilities or pipeline landfalls has moved closer to 

zero and farther from one (Dismukes, personal communication, 2010a). However, BOEMRE recognizes 

the need to continue monitoring all resources for changes that are applicable for land use and 

infrastructure. Maintenance dredging of existing navigation channels is still expected, but no new 

navigation channels are expected to be dredged as a result of the CPA proposed action. The volume of 

OCS-generated waste is closely correlated with the level of offshore drilling and production activity. 

Demand for waste disposal facilities is influenced by the volume of waste generated. At this time, it is 

unclear how long the current slowdown in activity will continue or how it might affect later years. Until 

OCS drilling activity recovers, potential for a new waste facility as a result of the CPA proposed action is 

highly unlikely. 

Chapter 4.1.2.1.4.2 of the Multisale EIS and Chapter 3.1.2.2 of the 2009-2012 Supplemental EIS 

discuss gas processing plants and the potential for new facilities and/or expansion at existing facilities. 

Over the past 5 years, there has been a substantial decrease in offshore natural gas production, partially as 

a result of increasing emphasis on onshore shale gas development, which is less expensive to produce and 

provides larger per well production opportunities and reserve growth. Also, there has been a trend toward 
Description of the Environment and Impact Analysis 4-319 

more efficient gas processing facilities with greater processing capacities. In Alabama, Mississippi, and 

the eastern portion of South Louisiana, plant capacity increased significantly as plant expansions occurred 

and new larger plants were built in response to offshore production (USDOE, Energy Information 

Administration, 2006). While natural gas production on the OCS shelf (shallow water) has been rapidly 

declining, deepwater gas production has been increasing, but not quickly enough to make up the 

difference. Increasing onshore shale gas development, declining offshore gas production, and the 

increasing efficiency and capacity of existing gas processing facilities are trends that have combined to 

lower the need for new gas processing facilities along the Gulf Coast in the past 5 years. Combined with 

this, existing facilities that were already operating at about 50 percent of capacity prior to the 2005 

hurricane season are operating at even lower capacity utilization levels now. Spare capacity at existing 

facilities should be sufficient to satisfy new gas production for many years, although there remains a slim 

chance that a new gas processing facility may be needed by the end of the 40-year life of the proposed 

action (Dismukes, personal communication, 2010b). 

The BOEMRE analyzes the potential for new pipeline landfalls to determine the potential impacts to 

wetlands and other coastal habitats. In Chapter 4.1.2.1.7 of the Multisale EIS and other previous EIS’s 

and EA’s, BOEMRE assumed that the majority of new Federal OCS pipelines would connect to the 

existing infrastructure in Federal and State waters and that very few would result in new pipeline 

landfalls. Therefore, BOEMRE projected up to one pipeline landfall per lease sale. Between the 

Multisale EIS and the 2009-2012 Supplemental EIS, BOEMRE tested this assumption by analyzing past 

lease sale outcomes (USDOI, MMS, 2007d). This analysis shows that it is generally unlikely that even 

one landfall would result from an individual lease sale. A mature pipeline network already exists in the 

Gulf of Mexico and companies have very strong financial incentives to reduce their costs by designing 

and utilizing pipeline systems to their fullest extent possible. Companies consider “economies of scale” 

in pipeline transportation, maximizing the amount of product moved through a constructed pipeline to 

decrease the long-run, average cost of production. Mitigation costs for any new wetland and 

environmental impacts, as well as various landowner issues at the landfall point are additional 

considerations. These are strong incentives to move new production into existing systems and to avoid 

creating new landfalls (USDOI, MMS, 2007d). This analysis confirms BOEMRE’s assumption that the 

majority of new pipelines constructed would connect to the existing infrastructure in Federal and State 

waters and that very few would result in new pipeline landfalls. However, there may be instances where 

new pipelines would need to be constructed. Location would be a determining factor; if there are no 

existing pipelines reasonably close and it is more cost effective to construct a pipeline to shore, then there 

may be a new OCS pipeline landfall. However, the very strong financial incentives to link into the 

existing, mature pipeline network make this highly unlikely (Dismukes, personal communication, 2010c). 

Chapters 4.1.1.3.2 and 4.1.1.4.2 provide a detailed discussion of coastal barrier beaches and wetlands, 

respectively, and potential pipeline landfall impacts to those resources. 

Chapters 3.3.5.8.1 and 4.1.2.1.1 of the Multisale EIS and Chapter 3.1.2.1 of the 2009-2012 

Supplemental EIS present a description of OCS-related service bases. A service base is a community of 

businesses that load, store, and supply equipment, supplies, and personnel that are needed at offshore 

work sites. The proposed action is not projected to change existing OCS-related service bases or require 

construction of new service bases. Instead, it would contribute to the use of existing service bases. 

Figure 3-4 shows the 50 service bases the industry currently uses to service the OCS. These facilities are 

identified as the primary service bases from plans received by BOEMRE. The ports of Fourchon, 

Cameron, Venice, and Morgan City, Louisiana, are the primary service bases for Gulf of Mexico mobile 

rigs. Major platform service bases in the CPA are Cameron, Fourchon, Intracoastal City, Morgan City, 

and Venice, Louisiana; Pascagoula, Mississippi; and Theodore, Alabama. 

Service bases are utilized for three types of OCS offshore support: supply vessel, crewboat, and 

helicopter. Supply vessels transport pipe and bulk supplies, and the supply vessel base serves as the 

loading point and provides temporary storage. Crewboats transport personnel and small supplies. 

Collectively, supply vessels and crewboats are known as “OSV’s” (offshore supply vessels). There are 

approximately 1,200 OSV’s operating in the GOM. Important drivers for the OSV market include the 

level of offshore exploration and drilling activities, current oil and gas prices, expectations for future oil 

and gas prices, and customer assessments of offshore prospects (Dismukes, in preparation-b). High 

demand for OSV’s translates into a positive impact on OCS-related employment (see Chapter 4.1.1.21.3, 

“Economic Factors” below). Helicopters transport small supplies and workers and also may patrol 
4-320 Central Planning Area Supplemental EIS 

pipelines to spot signs of damage or leakage. Helicopters service drilling rigs, production platforms, and 

pipeline terminals, as well as specialized vessels, such as jack-up barges. The OCS activity levels and 

offshore oil and gas industry transportation needs substantially influence the demand for and profitability 

of helicopter services (Dismukes, in preparation-b). Exploration and development plans filed with 

BOEMRE identify the expected number and frequency of vessel and helicopter trips, and the primary and 

secondary service bases for each project. In the event of changes in weather or operation conditions, a 

small amount of vessel and helicopter traffic may be dispatched from other bases. However, these 

deviations would occur on a temporary basis, and vessel traffic and helicopter transport should return to 

the primary and secondary bases as timely as possible. 

Chapter 4.1.2.1.9 of the Multisale EIS and Chapter 3.1.2.1 of the 2009-2012 Supplemental EIS 

discuss navigation channels along the Gulf Coast. Much of the traffic navigating these channels is 

unrelated to OCS activity, and the current system of navigation channels in the northern GOM is 

projected to be adequate for accommodating traffic generated by the CPA proposed action. The Gulf-toport channels and the Gulf Intracoastal Waterway that support prospective OCS ports are generally deep 

and wide enough to handle OCS-related traffic and are maintained by regular dredging (Figure 3-5). The 

COE is the responsible Federal agency for the regulation and oversight of navigable waterways. The 

maintained depths for these waterways are shown in Table 3-36 of the Multisale EIS. All lease sales 

contribute to the demand for OSV support; hence, it also contributes to the vessel traffic that moves in 

and out of support facilities. Therefore, the CPA proposed action is likely to contribute to the continued 

need for maintenance dredging of existing navigation channels. However, no new navigation channels 

are expected to be dredged as a result of the proposed action. Maintenance dredging is essential for 

proper water depths in channels to allow all shipping to move safely through the waterways to ports, 

services bases, and terminal facilities. Several million cubic yards of sand, gravel, and silt are dredged 

from waterways and harbors every year. This is a controversial process because it necessarily occurs in 

or near environmentally sensitive areas such as valuable wetlands, estuaries, and fisheries (Dismukes, in 

preparation-b). Chapter 4.1.1.4.2 provides a discussion of wetlands and the impacts of navigation 

channel dredging. 

Chapters 4.1.2.2 of the Multisale EIS and Chapter 4.1.16.1.2 of the 2009-2012 Supplemental EIS 

discuss OCS waste disposal. These analyses and other previous EIS’s and EA’s concluded that no new 

solid-waste facilities would be built as a result of a single lease sale or as a result of the OCS Program. 

Recent research further supports these past conclusions that existing solid-waste disposal infrastructure is 

adequate to support both existing and projected offshore oil and gas drilling and production needs 

(Dismukes et al., 2007). The industry trend is toward innovative methods to handle wastes to reduce the 

potential for environmental impacts; e.g., hydrocarbon recovery/recycling programs, slurry fracture 

injection, treating wastes for reuse as road base or levee fill, and segregating waste streams to reduce 

treatment time and improve oil recovery. The volume of OCS waste generated is closely correlated with 

the level of offshore drilling and production activity (Dismukes, in preparation-a). Before the DWH 

event, BOEMRE analyses indicated that there was an abundance of solid waste capacity in the GOM 

region and thus highly unlikely that any new waste facilities would be constructed. If any increase in the 

need for capacity develops, it would probably be met by expansion of existing facilities. However, now it 

is unclear whether this will remain true and more research is needed (Dismukes, personal communication, 

2010d). In recent months, due to the drilling suspensions and temporary interruption in permit approval 

slowdown, there has been some reduction in offshore drilling activity. Given this situation, demand for 

waste disposal facilities may not be likely to increase. However, at this time BOEMRE cannot predict 

how long these impacts continue or how long it will take for activity levels to recover. The BOEMRE 

will continue to monitor waste-disposal demands and activity in the post-DWH event environment. 

Chapter 4.1.1.21.4.2 provides a discussion of environmental justice issues related to waste disposal 

facilities. 

Summary and Conclusion 

The impacts of routine events associated with the CPA proposed action are uncertain due to the postDWH event environment, lingering effects of the drilling suspensions, changes in Federal requirements 

for drilling safety, and the temporary interruption of the permit approval process. The BOEMRE projects 

0-1 new gas processing facilities and 0-1 new pipeline landfalls for the proposed action. However, based 
Description of the Environment and Impact Analysis 4-321 

on the most current information available, there is a very slim chance that either would result from the 

CPA proposed action, and if a new gas processing facility or pipeline landfall were to result, it would 

likely occur toward the end of the 40-year analysis period. The likelihood of a new gas processing 

facility or pipeline landfall is much closer to zero than to one (Dismukes, personal communication, 

2010a). The BOEMRE anticipates that there would be maintenance dredging of navigation channels and 

an increase in activity at services bases as a result of the CPA proposed action. If drilling activity 

recovers post-DWH event and increases, there could be new increased demand for a waste disposal 

services as a result of the CPA proposed action. Because of the current near zero estimates for pipeline 

landfalls and processing facility construction, the routine activities associated with the CPA proposed 

action would have little effect on land use. 

As a result of the DWH event, it is too early to determine substantial, long-term changes in routine 

event impacts to land use and infrastructure. The BOEMRE anticipates these changes would become 

apparent over time. Therefore, BOEMRE recognizes the need to continue monitoring all resources for 

changes that are applicable for land use and infrastructure. From the information that is currently 

available, in regard to land use and infrastructure, it does not appear that there would be adverse impacts 

from routine events associated with the CPA proposed action. 

4.1.1.21.1.3. Impacts of Accidental Events 

Background/Introduction 

Impacts of accidental events on land use and coastal infrastructure for the CPA proposed action are 

discussed in Chapter 4.4.14.1 of the Multisale EIS. Impact analyses for the 181 South Area that includes 

new information since publication of the Multisale EIS is presented in Chapter 4.1.16.1.3 of the 2009-

2012 Supplemental EIS. The following information is a summary of the impact analysis incorporated 

from the Multisale EIS, the 2009-2012 Supplemental EIS, and new information that has become available 

since both documents were prepared. 

Proposed Action Analysis 

Impact-producing factors associated with the CPA proposed action that could affect land use and 

coastal infrastructure include (1) oil spills, (2) vessel collisions, and (3) chemical/drilling-fluid spills. The 

DWH event was an accidental event of historic and catastrophic proportion, the largest blowout in U.S. 

history, and the first to occur on the OCS in over 30 years. Such events should be distinguished from 

accidental events that are smaller in scale and that occur more frequently. Chapter 4.3.1.3 of the 

Multisale EIS provides a detailed discussion of oil spills that have occurred and their frequency. Detailed 

analysis of a high-impact, low-probability catastrophic event such as DWH event is provided in 

Appendix B. 

Oil spills may be associated with exploration, production, or transportation activities that result from 

the CPA proposed action. Detailed risk analysis of offshore oil spills ≥1,000 bbl and coastal spills 

associated with the CPA proposed action is provided in Chapters 4.3.1.5, 4.3.1.6, and 4.3.1.7 of the 

Multisale EIS, respectively. Because oil spilled in the offshore areas normally volatilizes and is dispersed 

by currents, it has a low probability of contacting coastal areas. Oil spills in coastal and inland waters, 

such as spills resulting from the operations of offshore supply vessels, pipelines, barges, tanker ships, and 

ports are more likely to affect BOEMRE-recognized coastal infrastructure categories. Table 3-7 contains 

the estimated number of oil spills that could happen in Gulf coastal waters as a result of an accidental 

event associated with the CPA proposed action. 

Vessel collisions may be associated with exploration, production, or transportation activities that 

result from the CPA proposed action. Chapter 4.3.3 of the Multisale EIS provides a detailed discussion of 

vessel collisions. The BOEMRE data show that, from 1996 through 2005, there were 129 OCS-related 

collisions. The majority of vessel collisions involve service vessels colliding with platforms or pipeline 

risers, although sometimes vessels collide with each other. These collisions often result in spills of 

various substances and, while most occur on the OCS far from shore, ones in coastal waters can have 

consequences to land use and coastal infrastructure. For example, on July 23, 2008, a barge carrying 

heavy fuel collided with a tanker ship in the Mississippi River at New Orleans, Louisiana. Over several 

days the barge leaked approximately 419,000 thousands of gallons of fuel. From New Orleans to the 
4-322 Central Planning Area Supplemental EIS 

south, 85 mi (137 km) of the river were closed to all traffic while cleanup efforts were undertaken, 

causing a substantial backup of river traffic (USDOC, NOAA, 2008c). 

Chemical/drilling-fluid spills may be associated with exploration, production, or transportation 

activities that result from the CPA proposed action. Chapter 4.3.4 of the Multisale EIS provides a 

detailed discussion of chemical and drilling-fluid spills. Each year, between 5 and 15 chemical spills are 

expected to occur; most of these are ≤50 bbl in size. Large spills are much less frequent. For example, 

from 1964 to 2005, only two chemical spills of ≥1,000 bbl occurred. Even though additional production 

chemicals are needed in deepwater operations where hydrate formation is a possibility, spill volumes are 

expected to remain stable because of advances in subsea processing. 

With the exception of a catastrophic accidental event, such as the DWH event, the impact of oil spills, 

vessel collisions, and chemical spills are not likely to last long enough to adversely affect overall land use 

or coastal infrastructure in the analysis area. 

Deepwater Horizon Event 

While it is too early to determine the final outcome and impacts of the DWH event, much is known. 

In the months following the DWH event, there have been some short-term, indirect impacts on land use 

and coastal infrastructure caused by the drilling suspension imposed on July 12, 2010, and lifted on 

October 12, 2010; by its lingering effects; and from changes in Federal requirements for drilling safety 

and the permit approval process. Drilling has actually resumed in shallow waters but must meet new 

drilling application information requirements as clarified in NTL 2010-N06. Deepwater drilling has 

commenced and is dependent upon operators fulfilling new more stringent requirements and BOEMRE 

permit approvals. The impacts of the suspension were experienced at Port Fourchon, Louisiana, where 

rental rates were cut by 30 percent as an incentive for businesses to stay. However, companies have 

removed a large portion of their equipment from the port and there has been a substantial decrease in 

helicopter flights and servicing of rigs. 

The deepwater exploration activity at Port Fourchon is expected to resume with the approval of 

deepwater permits. The rate of drilling is dependent upon compliance with more stringent Federal 

enforcement, the industry’s efforts to fulfill new safety requirements that are not yet finalized, and the 

resulting slow pace for drilling application approvals. Deepwater exploratory drilling is a huge economic 

driver for jobs, investments, vessels, etc. (Chaisson, personal communication, 2010). In the long term, 

the effects of the suspension and its aftermath are not expected to change the basic market fundamentals 

that drive demand for support infrastructure. In the short term, the decrease in deepwater exploratory 

drilling is expected to ripple through the various infrastructure categories (e.g., fabrication yard, 

shipyards, port facilities, pipecoating facilities, gas processing facilities, waste management facilities, 

etc.) and will also affect the oil and gas support sector businesses (e.g., drilling contractors, offshore 

support vessels, helicopter hubs, mud/drilling fluid/lubricant suppliers, etc.). See Chapter 4.1.1.21.3 for 

a detailed analysis of economic factors. The BOEMRE will continue to monitor these infrastructure 

effects as they evolve over time. 

Land use experienced more immediate, short-term impacts from the establishment of temporary waste 

staging areas and decontamination areas set up to handle spill-related waste. Concerns about waste 

management practices were expressed by government and the public (Barringer, 2010). The USEPA, in 

consultation with the Coast Guard, issued solid waste management directives to address the issue of 

contaminated materials, and solid or liquid wastes that were recovered as a result to cleanup operations 

(USEPA, 2010k and 2010l). Fifteen waste staging areas spread out across Louisiana, and there were none 

in Texas. No decontamination areas were set up in either Louisiana or Texas. The USEPA visited each 

staging and decontamination area once per week and each landfill two times per month, and they 

documented their findings on the USEPA public website. There were some issues, but nothing that 

would appear to cause a long-term impact (USEPA, 2010m). Additional description of the DWH event’s 

waste stream is located in Chapter 4.1.1.21.4. Detailed analysis of a high-impact, low-probability 

catastrophic event such as the DWH event may be found in Appendix B. 

Summary and Conclusion 

Many of the impacts of the DWH event to land use and infrastructure have been temporary and shortterm, such as the ship decontamination sites and the waste staging areas established in the immediate 
Description of the Environment and Impact Analysis 4-323 

aftermath of the DWH event (USDOT, 2010). The indirect effects on infrastructure use are still rippling 

through the industry, but this should resolve as issues with the suspensions, permitting, etc. are resolved. 

With regards to land use and infrastructure, the post-DWH event environment remains somewhat 

dynamic, and BOEMRE will continue to monitor these resources over time and to document short- and 

long-term DWH event impacts. In the future, the long-term impacts of the DWH event will be clearer as 

time allows the production of peer-reviewed research and targeted studies that determine those impacts. 

The DWH event was a low-probability, high-impact catastrophic event. For the reasons set forth in the 

analysis above, the kinds of accidental events that are likely to result from the CPA proposed action are 

not likely to significantly affect land use and coastal infrastructure. This is because accidental events 

offshore would have a small probability of impacting onshore resources. Also, if an accident occurs 

nearshore, it would be most probably be near a facility; therefore, the impacts would be temporary and 

localized because of the decrease in response time. 

4.1.1.21.1.4. Cumulative Impacts 

Background/Introduction 

A detailed analysis of cumulative impacts upon land use and coastal infrastructure for the CPA 

proposed action can be found in Chapter 4.5.15.1 of the Multisale EIS. Impact analyses for the 181 South 

Area that includes any new information since publication of the Multisale EIS is presented in Chapter 

4.1.16.1.4 of the 2009-2012 Supplemental EIS. The following information is a summary of the impact 

analysis incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information 

that has become available since both documents were prepared. 

The cumulative analysis considers the effects of impact-producing factors from OCS and State oil and 

gas activities. The OCS- and State-related factors consist of prior, current, and future OCS and State 

lease sales. Chapters 3.3.5.1.2 and 3.3.5.8 of the Multisale EIS discuss land use and OCS-related oil and 

gas infrastructure associated with the analysis area. The vast majority of this infrastructure also supports 

oil and gas production in State waters as well as in coastal areas onshore. 

According to BOEMRE development scenario analysis, the construction of 0-1 new gas processing 

facilities would be expected to occur near the end of the 40-year life of the proposed action. Most new 

pipelines would be offshore and would tie into the existing offshore pipeline infrastructure. According to 

the scenario analysis, 0-1 new pipeline landfalls would be expected to occur toward the end of the 40-year 

lifespan of the proposed lease sale. Those projections also called for no new waste disposal facilities due 

to existing excess capacity along the Gulf Coast. Recently, based on the analysis of historical data, 

BOEMRE validated its past scenario projections of new gas processing facilities and new pipeline 

landfalls and found its projections to be conservative; that is, the actual numbers proved to be equal to, or 

less than, the projected numbers. Current scenario projects are also likely to be conservative (Dismukes, 

personal communication, 2010a). 

In the months following the DWH event, much information has been generated regarding the 

consequences of the oil spill and subsequent drilling suspensions. Because petroleum activities on the 

OCS and in State waters and coastal areas are driven by market fundamentals, the DWH event and related 

events are not expected to have long-term consequences on them. Hence, these events are not expected to 

affect land use and infrastructure in the cumulative case. However, because the post-DWH event 

environment is dynamic and ever-changing, BOEMRE is currently conducting ongoing monitoring of 

post-DWH event impacts to land use and coastal infrastructure, and BOEMRE will conduct targeted and 

peer-reviewed research should this monitoring identify long-term impacts of concern. 

Land use in the analysis area will evolve over time. The majority of change is likely to occur from 

general, regional economic and demographic growth rather than from activities associated with current 

OCS and/or State offshore petroleum production or future planned OCS or State lease sales. Projected 

new coastal infrastructure as a result of the OCS Program is shown by State in Table 4-9 of the Multisale 

EIS. The BOEMRE development scenarios consider demand from both current and future OCS and State 

leases. These scenarios project 0-1 new gas processing facilities to result from the proposed action. 

However, this number is derived from the estimated demand for future processing capacity. Given 

current industry practice, it is likely that few (if any) new, Greenfield gas processing facilities would 

actually be constructed along the CPA. Instead, it is likely that a large share (and possibly all) of any 

additional natural gas processing capacity that is needed in the industry will be developed at existing 
4-324 Central Planning Area Supplemental EIS 

facilities, through future investments in expansions, and/or replacement of depreciated capital equipment. 

Also, these BOEMRE scenario projections are conservative; i.e., they likely overestimate the additional 

capacity that would be required. 

Over the past 5 years, there has been a substantial decrease in offshore natural gas production, 

partially as a result of increasing emphasis on onshore shale gas development, which is less expensive to 

produce and provides larger per-well production opportunities and reserve growth. Also, there has been a 

trend toward more efficient gas processing facilities with greater processing capacities (Dismukes, in 

preparation-a). In Alabama, Mississippi, and the eastern portion of South Louisiana, plant capacity 

increased significantly as plant expansions occurred and new larger plants were built in response to 

offshore production (USDOE, Energy Information Administration, 2006). While natural gas production 

on the OCS shelf (shallow water) has been rapidly declining, deepwater gas production has been 

increasing, but not quickly enough to make up the difference. Increasing onshore shale gas development, 

declining offshore gas production, and the increasing efficiency and capacity of existing gas processing 

facilities are trends that have combined to lower the need for new gas processing facilities along the Gulf 

Coast in the past 5 years. Combined with this, existing facilities that were already operating at about 

50 percent of capacity prior to the 2005 hurricane season are operating at even lower capacity utilization 

levels now. Spare capacity at existing facilities should be sufficient to satisfy new gas production for 

many years, although there remains a slim chance that a new gas processing facility may be needed by the 

end of the 40-year life of the proposed action (Dismukes, personal communication, 2010b). Any 

additions to, or expansions of, current facilities would also support State oil and gas production and, 

should any occur, the land in the analysis area is sufficient to handle development. Thus, the results of 

OCS and State oil and gas activities are expected to minimally alter the current land use of the area. 

Service base infrastructure supports offshore petroleum-related activities in both OCS and State 

waters. Any changes to offshore support infrastructure that occurs in the cumulative case are expected to 

be contained on available land. Service bases are industrial ports and are located in designated industrial 

parks designed with the intent to accommodate future oil and gas needs. Also, most of these are located 

in BOEMRE analysis areas that have strong industrial bases. Shore-based OCS and State servicing is 

expected to increase in the ports of Galveston, Texas; Port Fourchon, Louisiana; and Mobile, Alabama. 

There is sufficient land designated in commercial and industrial parks and adjacent to the Galveston and 

Mobile port areas. This would minimize disruption possible from port expansions to current residential 

and business use patterns. In contrast, while Port Fourchon has land designated for future expansion, the 

port has a limited amount of waterfront land available and, because of surrounding wetlands, may face 

capacity constraints in the long term. At present, there is a small amount of waterfront property available 

that is situated around Slip C (The Greater Lafourche Port Commission, 2010a) and approximately 55 ac 

(22 ha) of nonwaterfront property also available for lease (The Greater Lafourche Port Commission, 

2010b). The port’s 4,000-ac (1,620-ha) Northern Expansion is nearly complete and will essentially 

double its operational area. Phase 1 of the Northern Expansion is a 700-ac (284-ha) site containing 

520 ac (210 ha), with 21,000 ft (6,400 m) of water frontage. Construction of 700 ft (213 m) of bulkhead 

in Slip B is complete and an additional 1,100 ft (335 m) of bulkhead is currently under construction. 

Another 1,425 ft (434 m) of bulkhead is scheduled for construction in 2010. Phase 1 of the Northern 

Expansion is nearly complete, and over 80 percent of total Phase 1 property is already leased (The Greater 

Lafourche Port Commission, 2010c). Port Fourchon serves as the primary support base for over 90 

percent of existing deepwater projects. From 2008 through 2009, the demand for support base facilities 

continued to increase despite an economic recession. Prior to the DWH event, new facilities at the port 

were leased as soon as they could be constructed (Redden, 2009). Since the DWH event and the May 

2010 drilling moratorium, port tenants have been struggling with the drop in exploration drilling even 

8 weeks after the July drilling suspension was lifted on October 12, 2010. This hiatus is due to more 

stringent Federal enforcement, industry’s efforts to fulfill new safety requirements, and the resulting slow 

pace for drilling application approvals. During this time, cleanup and decontamination work are keeping 

companies busy, but it is slated to cease at the end of December 2010. There is much uncertainty about 

what is going to happen at Port Fourchon from an economic standpoint when the decontamination work 

ends, and deepwater exploratory drilling is a huge economic driver for jobs, investments, vessels, etc. 

(Chaisson, personal communication, 2010). However, BOEMRE expects that this uncertainty to be short 

term and, because the economic prospectivity of the Gulf has not changed, deepwater activity at the port 
Description of the Environment and Impact Analysis 4-325 

will gradually increase to pre-DWH event levels after new Federal regulations are finalized and 

appropriate permit applications for new deepwater exploratory drilling are submitted and approved. 

LA Hwy 1 is the only highway connecting Port Fourchon with the rest of Louisiana. This two-lane 

highway is surrounded by marshland and has been prone to extreme flooding over the years, jeopardizing 

critical access to Port Fourchon, which is the service base for 90 percent of OCS deepwater activity. 

While, in the absence of planned expansions, LA Hwy 1 would not be able to handle future OCS and 

State activities, a multiphase LA Hwy 1 improvement project is currently underway. On July 8, 2009, the 

new LA Hwy 1 fixed-span toll bridge over Bayou Lafourche connecting Port Fourchon and Leeville, 

Louisiana, was opened and marks partial completion of the first phase of improvements to LA Hwy 1 

(Toll Roads News, 2009). A large portion of the tolls collected would be paid by transportation activities 

associated with OCS oil- and gas-related activities. The remaining portion of Phase 1 construction, a twolane elevated highway from the bridge to Port Fourchon, is scheduled for completion in late 2011. There 

are continuing efforts to get Federal funding to construct Phase 2 of the project—an elevated highway 

from the Golden Meadow floodgates to Leeville, Louisiana (LA 1 Coalition, 2010a). 

The South Lafourche Leonard Miller Jr. Airport recently opened a partial parallel taxiway and the 

Port commission has plans to extend it to full length. In the past 8 years, $20 million have been invested 

in the airport for improvements that include the paving of airport roadways, runway expansion and 

overlay, installation of fuel tanks, and construction of an extra large hanger. The runway expansion and 

overlay have increased the maximum aircraft weight to allow access by 20-passenger jets. From 2008 to 

2009, activity at the airport increased 19 percent. Airport authorities are also in the second phase of 

implementing an Instrument Landing System like those found at major commercial airports as a 

navigational aid to pilots. The Greater Lafourche Port Commission recently acquired 1,200 ac (485 ha) of 

property near the airport and intends to develop that land into an industrial park (The Greater Lafourche 

Port Commission, 2010d). 

If the service base expansion occurs in the cumulative case at the ports of Galveston, Texas, and 

Mobile, Alabama, this expansion would occur in areas that are already industrialized and would have 

little effect on land use and infrastructure. This is also true for Port Fourchon, Louisiana, although, in the 

cumulative case, expansion of this service base may eventually be constrained by surrounding wetlands. 

Limited highway access and airport capacity could also constrain service base expansion at Port Fourchon 

in the cumulative case. However, ongoing and planned improvement projects make this unlikely. 

Summary and Conclusion 

Activities relating to the OCS Program and State oil and gas production are expected to minimally 

affect the current land use of the analysis area because most subareas have strong industrial bases and 

designated industrial parks to accommodate future growth in oil and gas businesses. The BOEMRE 

projects 0-1 new gas processing facilities and 0-1 new pipeline landfalls for the proposed action, although 

this is a conservative estimate and the number is much closer to zero than to one. If a new gas processing 

facility or pipeline landfall were to occur, it would likely be toward the end of the 40-year analysis period 

(Dismukes, personal communication 2010b). There may be new increase demand for a waste disposal 

services as a result of the proposed action. Any service base expansion in the cumulative case would be 

limited, would occur on lands designated for such purposes, and would have minimal effects on land use 

and infrastructure. However, in the cumulative case it is possible that Port Fourchon expansions may 

eventually be constrained by surrounding wetlands. Based on the available information and current 

BOEMRE scenario projections, the cumulative impacts on land use and coastal infrastructure are 

expected to be minor, and the incremental contribution of the CPA proposed action to the cumulative 

impacts on land use and coastal infrastructure are also expected to be minor. The current post-DWH 

event environment is dynamic and BOEMRE will continue to monitor any developments regarding 

coastal land use and infrastructure. 

4.1.1.21.2. Demographics 

In light of the recent DWH event, BOEMRE has reexamined the analysis of demographics presented 

in the Multisale EIS and the 2009-2012 Supplemental EIS. While some new information was found 

related to the baseline conditions (most notably the new Woods & Poole Economics, Inc. (2010) 

population projection data), the incremental population impacts of the CPA proposed action, and the 
4-326 Central Planning Area Supplemental EIS 

impacts of accidental events, a reanalysis found that none of the new information altered the impact 

conclusions for demographics presented in the Multisale EIS and the 2009-2012 Supplemental EIS. 

While it is too early to determine if there will be any significant long-term demographic changes as a 

result of the DWH event and the subsequent drilling suspensions and given current information on the 

limited employment impacts to date (Chapters 4.1.1.17, 4.1.1.18, 4.1.1.19, and 4.1.1.21.3), BOEMRE 

anticipates that there will not be any substantial long-term population and demographic changes. 

However, BOEMRE will continue to monitor data and information as it becomes available. If there are 

substantial long-term employment impacts to the tourism and recreation, fishing, or energy industries in 

the area, there may be some out-migration from some affected areas in the region. Short-term impacts 

and potential long-term impacts related to the DWH event in general, and the drilling suspensions in 

particular, are discussed at the end of the sections below on the “Description of the Affected 

Environment” (Chapter 4.1.1.21.2.1) and “Impacts of Accidental Events” (Chapter 4.1.1.21.2.3). 

A detailed description of the affected environment and full analyses of the potential impacts of 

routine activities and accidental events associated with the CPA proposed action are presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, as are the proposed action’s incremental contribution 

to the cumulative impacts. A summary of those analyses and their reexamination due to new information 

and the DWH event and drilling suspensions are presented in the following sections. 

A brief summary of potential impacts follows. The CPA proposed action is projected to minimally 

affect the demography of the analysis area. Population impacts from the CPA proposed action are 

projected to be minimal (<1% of the total population) for any EIA in the Gulf of Mexico region. The 

baseline population patterns and distributions projected and described in Chapter 4.1.1.21.2.1 below are 

expected to remain unchanged as a result of the CPA proposed action. The increase in employment 

discussed in Chapter 4.1.1.21.3.2 is expected to be met primarily with the existing population and 

available labor force, with the exception of limited in-migration (some possibly foreign) projected for 

focal areas such as Port Fourchon. Accidental events associated with the proposed action, such as oil or 

chemical spills, blowouts, and vessel collisions, would likely have no effects on the demographic 

characteristics of the Gulf Coastal communities. The cumulative activities are projected to minimally 

affect the analysis area’s demography. 

4.1.1.21.2.1. Description of the Affected Environment 

The description of the environment for demographics is described in Chapter 3.3.5.4 of the Multisale 

EIS and in Chapter 4.1.16.2.1 of the 2009-2012 Supplemental EIS. The following is a summary and 

update of the information presented in those documents. A search was conducted for new information 

since completion of the 2009-2012 Supplemental EIS that would impact the baseline demographics of the 

region. The BOEMRE examines demographic impacts over the 40-year life of the proposed action. The 

new 2011 CEDDS data from Woods & Poole Economics, Inc. (2010) was most relevant to this 

examination, and BOEMRE updated all baseline projections using these data. The limited supplemental 

information related to the short-term impacts of the DWH event and the drilling suspensions that is 

available is presented at the end of this section. However, this supplemental information does not change 

the Woods & Poole Economics, Inc.’s baseline population projections used to analyze impacts of the 

CPA proposed action and the OCS Program, which, as explained in Chapter 4.1.1.21.2.4, is used for the 

cumulative impact analysis. The methodology BOEMRE uses to measure employment impacts (and the 

subsequent demographic impacts that are generated by employment changes) over the 40-year life of the 

proposed lease sale recognizes that most of the employment that results from industry activities that result 

from the lease sale is not generated until 4-7 years after the sale. In contrast, the supplemental 

information provided below is related to current socioeconomic conditions. 

Offshore waters of the WPA, CPA, and EPA lie adjacent to coastal Texas, Louisiana, Mississippi, 

Alabama, and Florida. The BOEMRE groups sets of counties and, in Louisiana, parishes into LMA’s on 

the basis of intercounty commuting patterns. Twenty-three of these LMA’s span the Gulf Coast and 

comprise the 13 BOEMRE-defined EIA’s. Table 4-23 lists the counties and parishes that comprise the 

LMA’s and EIA’s, and Figure 2-2 illustrates the counties and parishes that comprise the EIA’s; see 

Chapter 3.3.5.4.1 of the Multisale EIS for further detail. The nature of the offshore oil and gas industry is 

such that the same onshore impact area is used to examine activities in the WPA and CPA. First, workers 

commute long distances for rotations offshore that last for 2-3 weeks at a time, and there is great 
Description of the Environment and Impact Analysis 4-327 

flexibility between where employees live and where they work offshore in the GOM. Second, industry 

equipment and supplies for offshore projects in both planning areas come from throughout the region. 

Although the same overall onshore impact area is used to analyze sales in both planning areas, the 

impacts to the different individual EIA’s do vary between WPA sales and CPA sales. 

Tables 3-18 through 3-30 of the Multisale EIS provide projections of detailed demographic data for 

the EIA’s using 2006 CEDDS data (Woods & Poole Economics, Inc., 2006). Tables 4-24 through 4-36

of this Supplemental EIS provide updated projections of the data using the 2011 CEDDS data (Woods & 

Poole Economics, Inc., 2010). The EIA’s total population increased by 6 percent between 2005 and 

2010, to approximately 24.5 million. In the U.S., population age structures typically reflect the presence 

of the baby-boom generation. In the EIA’s, the largest increases from 2005 to 2010 were in the Age 50 to 

64 and Age 65 and Over categories, which grew by 16 percent and 10 percent, respectively. In the EIA’s, 

the Hispanic population increased 17.2 percent between 2005 and 2010. This group is the second largest 

race/ethnic group in the area, making up 27.8 percent of the area’s population in 2010. The total AfricanAmerican population increased 5.2 percent between 2005 and 2010. Although Asians and Pacific 

Islanders constitute a relatively small portion of the Gulf Coast population (3.1%), this group has 

experienced a growth rate of 19.5 percent between 2005 and 2010. The proportion of white population 

has remained fairly constant and in 2010 constitutes 51.4 percent of the area’s population. These overall 

trends vary from one EIA to another and from one Gulf Coast State to another. 

Differences in age structure, as well as net migration, among the coastal EIA’s could create variations 

in population growth. The highest rates of population growth between 2010 and 2040 are expected in 

Texas EIA’s (TX-1 at 63%) and Florida EIA’s (FL-1 at 54.4%) and the lowest are expected in Alabama, 

Mississippi, and Louisiana EIA’s (LA-1 is the lowest at 18.3%). 

The racial and ethnic composition of the analysis area reflects both historical settlement patterns and 

current economic activities. For example, those areas in Texas where Hispanics are the dominant 

group—EIA TX-1 where they represent 81 percent of the population—were also first settled by people 

from Mexico. Their descendants remain, many of whom work in farming, tending cattle, or in low-wage 

industrial jobs. By TX-3, the size of the African-American population increases, and there is a more 

diversified racial mix indicating more urban and diverse economic pursuits. In Louisiana, Mississippi, 

Alabama, and Northern Florida (FL-1 and FL-2), African-Americans outnumber Hispanics, reflecting the 

dominant minority status of African-Americans throughout much of the analysis area. A more detailed 

discussion of minority populations in the area can be found in Chapter 4.1.1.21.4.1. 

Table 4-37 presents the baseline population projections used to analyze the impacts of the CPA 

proposed action and the OCS Program (which, as explained in Chapter 4.1.1.21.2.4 is used for the 

cumulative impact analysis). As stated above, these baseline projections assume the continuation of 

existing social, economic, and technological trends at the time of the forecast (i.e., prior to the DWH 

event and the subsequent drilling suspensions). However, this data still remain the best long-term 

forecast of regional trends for socioeconomic impact analyses of the CPA proposed action. 

4.1.1.21.2.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine impacts on demographics associated with the CPA proposed action 

can be found in Chapter 4.2.2.1.15.2 of the Multisale EIS and in Chapter 4.1.16.2 of the 2009-2012 

Supplemental EIS. The following is a summary of the information presented in these documents and 

incorporates new information found since their publication. 

The addition of any new human activity, such as oil and gas development resulting from the CPA 

proposed action, can affect local communities in a variety of ways. Typically, these effects are in the 

form of people and money, which can translate into changes in the local social and economic institutions. 

Minor demographic changes, primarily in focus areas, are projected as a result of the CPA proposed 

action. 
4-328 Central Planning Area Supplemental EIS 

Proposed Action Analysis 

Population 

Projected population changes reflect the number of people dependent on income from OCS-related 

employment for their livelihood (i.e., family members of oil and gas workers). The population 

projections due to the CPA proposed action are calculated by multiplying the employment projections for 

the sale (Chapter 4.1.1.21.3.2) by a ratio of baseline population to baseline employment (Tables 4-37 

and 4-38). The CPA proposed action is projected to generate from 12,400 to 35,900 persons in the entire 

analysis area during the peak impact year (model year 5 or 2016) for the low- and high-case scenarios, 

respectively. While population associated with the proposed sale is projected to peak in year 5, years 2 

and 6 also display high levels. During these years, a substantial amount of platform and pipeline 

installations are projected in association with the proposed sale. Platform fabrication and installation, and 

pipeline installation activities are labor intensive and tend to occur concurrently, leading to more 

substantial employment and population impacts. 

Using the new Woods & Poole Economics, Inc. (2010) data discussed above as the baseline, 

BOEMRE recalculated the population impacts on a percentage basis. The revised numbers do not differ 

substantially from those presented in Table 4-29 of the Multisale EIS and mirror those for employment 

impacts discussed in Chapter 4.1.1.21.3.2. Population impacts from the CPA proposed action are 

expected to be minimal (less than 1% of total population) for any EIA in the Gulf of Mexico region. The 

increase in employment is expected to be met primarily with the existing population and labor force, with 

the exception of some in-migration projected to move into such focal areas as Port Fourchon. 

Age 

The age distribution of the analysis area as a result of the CPA proposed action is projected to remain 

virtually unchanged. Given both the low levels of population growth and industrial expansion associated 

with the proposed action, the age distribution pattern discussed above in Chapter 4.1.1.21.2.1 is expected 

to continue through the life of the CPA proposed action. The proposed CPA lease sale is not expected to 

affect the analysis area’s median age. 

Race and Ethnic Composition 

The racial distribution of the analysis area is projected to remain virtually unchanged as a result of the 

CPA proposed action. Given the low levels of employment and population growth and the industrial 

expansion projected as a result of the proposed action, the racial distribution pattern described above in 

Chapter 4.1.1.21.2.1 is expected to continue through the life of the CPA proposed action. 

Summary and Conclusion 

The CPA proposed action is projected to minimally affect the demography of the analysis area. 

Population impacts from the proposed action are projected to be minimal (<1% of the total population) 

for any EIA in the Gulf of Mexico region. The baseline population patterns and distributions, as 

projected and described in Chapter 4.1.1.21.2.1, are expected to remain unchanged as a result of the CPA 

proposed action. The increase in employment is expected to be met primarily with the existing 

population and available labor force, with the exception of some in-migration projected to occur in focal 

areas, such as Port Fourchon. 

4.1.1.21.2.3. Impacts of Accidental Events 

Accidental events associated with the CPA proposed action, such as oil or chemical spills, blowouts, 

and vessel collisions, would likely have no effects on the demographic characteristics of the Gulf coastal 

communities. This is because net employment impacts from a spill are not expected to exceed 1 percent 

of baseline employment for any EIA in any given year even if they are included with employment 

associated with routine oil and gas development activities associated with the CPA proposed action and if 

population changes are derived from employment changes. 
Description of the Environment and Impact Analysis 4-329 

In the case of a catastrophic spill, there may be some out-migration from some affected areas in the 

region if there are substantial long-term employment impacts to the tourism and recreation, fishing, or 

energy industries in the area. For further discussion on the employment and demographic impacts of a 

catastrophic spill, see Appendix B. 

4.1.1.21.2.4. Cumulative Impacts 

Background/Introduction 

A detailed discussion of the cumulative impacts to demographics can be found in Chapter 4.5.15.2 of 

the Multisale EIS and in Chapter 4.1.16.2.4 of the 2009-2012 Supplemental EIS. The following is a 

summary of the information presented in these documents, and it incorporates new information found 

since their publication. The cumulative analysis considers the effects of OCS-related, impact-producing 

factors as well as non-OCS-related factors on demographics. The OCS-related factors consist of 

population and employment from prior, current, and future OCS lease sales. Non-OCS factors include 

fluctuations in workforce, net migration, relative income, oil and gas activity in State waters, and offshore 

LNG activity. Not considered in this analysis are the unexpected events that may influence oil and gas 

activity within the analysis area that cannot be predicted with reasonable accuracy. Examples of 

unexpected events include oil embargos and acts or war or terrorism. 

Most approaches to analyzing cumulative effects begin by assembling a list of “other likely projects 

and actions” that will be included with the proposed action analysis. However, no such list of future 

projects and actions could be assembled that would be sufficiently current and comprehensive to support 

a cumulative analysis for all 132 of the coastal counties and parishes in the analysis area over a 40-year 

period. Instead, this analysis uses the economic and demographic projections from Woods & Poole 

Economics, Inc. (2010) to define the contributions of other likely projects, actions, and trends to the 

cumulative case. These projections include population associated with the continuation of current 

patterns of OCS leasing activity as well as the continuation of trends in other industries important to the 

region. The same methodology used to project changes to population from routine activities associated 

with the CPA proposed action is used to examine impacts of the OCS Program in the region. 

Population 

Population impacts from the OCS Program (Table 4-43 in the Multisale EIS) remain unchanged 

because the exploration and development scenarios for the OCS Program did not change for this 

document (and thus the employment projections related to the OCS Program did not change). Projected 

population changes reflect the number of people dependent on income from oil- and gas-related 

employment for their livelihood (i.e., family members of oil and gas workers). Activities associated with 

the OCS Program are projected to have minimal effects on population in most of the EIA’s. Lafourche 

Parish (EIA LA-3) and Lafayette Parish (EIA LA-2) in Louisiana, in particular, are projected to 

experience noteworthy increases in population resulting from increases in demand for OCS labor. 

Chapter 4.5.15.3 of the Multisale EIS discusses this issue in more detail. 

Using the new Woods & Poole Economics, Inc.’s data (2010) discussed above as the baseline, 

BOEMRE recalculated the population impacts of the OCS Program on a percentage basis. These revised 

numbers do not differ substantially from those presented in Table 4-44 of the Multisale EIS and mirror 

those discussed for OCS Program employment in Chapter 4.1.1.21.3.4. 

Age 

Cumulative activities are projected to leave the age distribution of the analysis area virtually 

unchanged. Given both the low levels of population growth and the industrial expansion associated with 

the cumulative activities, it is projected that the age distribution pattern discussed above in Chapter 

4.1.1.21.2.1 will likely continue throughout the analysis period. 
4-330 Central Planning Area Supplemental EIS 

Race and Ethnic Composition 

Cumulative activities are projected to leave the racial distribution of the analysis are virtually 

unchanged. Given the low levels of employment and population growth and the industrial expansion 

projected for the cumulative activities, the racial distribution pattern discussed above in Chapter 

4.1.1.21.2.1 is projected to continue throughout the analysis period. 

Summary and Conclusion 

The cumulative activities are projected to minimally affect the analysis area’s demography. Baseline 

patterns and distributions of these factors, as described in Chapter 4.1.1.21.2.1, are not expected to 

change for the analysis area as a whole. Lafourche Parish (EIA LA-3), including Port Fourchon, and 

Lafayette Parish (EIA LA-2) in Louisiana are projected to experience noteworthy impacts to population 

as a result of an increase in demand for OCS labor from the OCS Program. The CPA proposed action is 

projected to have an incremental contribution of less than 1 percent to the population level in any of the 

EIA’s. Given both the low levels of population growth and industrial expansion associated with the 

proposed action, it is expected that the baseline age and racial distribution pattern would continue through 

the analysis period. 

4.1.1.21.3. Economic Factors 

In light of the recent DWH event, BOEMRE has reexamined the analysis of economic factors 

presented in the Multisale EIS and the 2009-2012 Supplemental EIS. While some new information was 

found related to the baseline employment conditions (most notably the new Woods & Poole Economics, 

Inc. (2010) data on projections for employment), the incremental employment impacts of the CPA 

proposed action, and the impacts of accidental events, a reanalysis found that none of the new information 

altered the impact conclusions for employment presented in the Multisale EIS and the 2009-2012 

Supplemental EIS. It is too early to determine if there will be any significant long-term employment 

changes in the region as a result of the DWH event and the subsequent drilling suspensions. Given 

current information, BOEMRE anticipates that there may be some long-term employment changes in 

some counties and parishes in the region. However, at this time, it is not clear if these changes will be 

significant or not. The BOEMRE will continue to monitor data and information on employment as it 

becomes available. Short-term employment impacts and potential long-term employment impacts related 

to the DWH event in general and the drilling suspensions in particular are discussed at the end of the 

sections below on the “Description of the Affected Environment” (Chapter 4.1.1.21.3.1) and “Impacts of 

Accidental Events” (Chapter 4.1.1.21.3.3). The following sections focus on the employment impacts to 

the energy industries and offshore support industries in the EIA’s. The employment impacts to 

commercial fishing (Chapter 4.1.1.17), recreational fishing (Chapter 4.1.1.18), and tourism and 

recreation (Chapter 4.1.1.19) are discussed in detail within their individual sections. 

A detailed description of the affected environment and full analyses of the potential impacts of 

routine activities and accidental events associated with the CPA proposed action are presented in the 

Multisale EIS and the 2009-2012 Supplemental EIS, as are the proposed action’s incremental contribution 

to the cumulative impacts. A summary of those analyses and their reexamination due to new information 

and the DWH event and drilling suspensions are presented in the following sections. 

A brief summary of potential impacts follows. Should the CPA proposed action occur, there would 

be only minor economic changes in the Texas, Louisiana, Mississippi, Alabama, and Florida EIA’s. The 

proposed action is expected to generate less than a 1 percent increase in employment in any of the coastal 

subareas, even when the net employment impacts from accidental events are included. Most of the 

employment related to the proposed action is expected to occur in Texas and Louisiana. The labor 

demand would be met primarily with the existing population and labor force. The cumulative activities 

are projected to minimally affect the analysis area’s economic conditions. 

4.1.1.21.3.1. Description of the Affected Environment 

The description of the environment for economic factors is described in Chapter 3.3.5.5 of the 

Multisale EIS and in Chapter 4.1.16.3.1 of the 2009-2012 Supplemental EIS. The following is a 
Description of the Environment and Impact Analysis 4-331 

summary and update of the information presented in those documents. A search was conducted for new 

information since completion of the Supplemental EIS that would impact the baseline economic factors of 

the region. The BOEMRE examines economic impacts over the 40-year life of the proposed action. The 

new 2011 CEDDS data from Woods & Poole Economics, Inc. (2010) was most relevant to this 

examination, and BOEMRE updated all baseline projections using these data. The limited supplemental 

information related to the short-term impacts of the DWH event and the drilling suspensions that is 

available is presented at the end of this section. However, this supplemental information does not change 

the Woods & Poole Economics, Inc.’s baseline employment projections used to analyze impacts of the 

CPA proposed action and the OCS Program, which, as explained in Chapter 4.1.1.21.3.4, is used for the 

cumulative impact analysis. The methodology BOEMRE uses to measure employment impacts (and 

subsequent demographic impacts) over the 40-year life of the proposed lease sale recognizes that most of 

the employment that results from industry activities that result from the lease sale is not generated until 4-

7 years after the sale. In contrast, the supplemental information provided below is related to current 

socioeconomic conditions. 

Offshore waters of the WPA, CPA, and EPA lie adjacent to coastal Texas, Louisiana, Mississippi, 

Alabama, and Florida. The BOEMRE grouped sets of counties and, in Louisiana, parishes into LMA’s 

on the basis of intercounty commuting patterns. Twenty-three of these LMA’s span the Gulf Coast and 

comprise the 13 BOEMRE-defined EIA’s. Table 4-23 lists the counties and parishes that comprise the 

LMA’s and EIA’s, and Figure 2-2 illustrates the counties and parishes that comprise the EIA’s; see 

Chapter 3.3.5.4.1 of the Multisale EIS for further detail. The nature of the offshore oil and gas industry is 

such that the same onshore economic impact area is used to examine leasing activities in both the WPA 

and CPA. First, workers commute long distances for rotations offshore that last for 2-3 weeks at a time, 

and there is great flexibility between where employees live in the region and where they work offshore in 

the GOM. Second, industry equipment and supplies for offshore projects in both planning areas come 

from throughout the region. Although the same overall economic impact area is used to analyze sales in 

both planning areas, the economic impacts to the different individual EIA’s do vary between WPA sales 

and CPA sales. 

Tables 3-18 through 3-30 of the Multisale EIS provide current and baseline projections for 

employment, income and wealth, and business patterns for the EIA’s using 2006 CEDDS data (Woods & 

Poole Economics, Inc., 2006). Tables 4-24 through 4-36 provide updated projections of the data using 

the 2011 CEDDS data (Woods & Poole Economics, Inc., 2010). Average annual employment growth 

projected from 2010 to 2040 range from a low of 1.03 percent for EIA MS-1 to a high of 2.04 percent for 

EIA FL-1 in the western panhandle of Florida. Over the same time period, employment for the U.S. is 

expected to grow at about 1.39 percent per year, while the GOM economic impact analysis area as a 

whole is expected to grow at about 1.79 percent per year. 

The Woods & Pool Wealth Index is a measure of relative wealth, with the U.S. having a value of 100. 

The Wealth Index is the weighted average of regional income per capita divided by U.S. income per 

capita (80% of the index), plus the regional proportion of income from dividends/interest/rent divided by 

the U.S. proportion (10% of the index), plus the U.S. proportion of income from transfers divided by the 

regional proportion (10% of the index). Thus, relative income per capita is weighted positively for a 

relatively high proportion of income from dividends, interest, and rent, and negatively for a relatively 

high proportion of income from transfer payments. In 2010, all EIA’s within the GOM analysis area with 

the exception of FL-4 (which had an index of 113.4) ranked below the U.S. in terms of wealth. The next 

two highest EIA’s were LA-4 and TX-3, with indices of 91.9 and 87.4, respectively. The EIA FL-2 

ranked the lowest of all EIA’s, with an index of 66.8. The Florida EIA’s comprise the portion of the 

analysis area that is least influenced by OCS development. The EIA’s with the next lowest wealth indices 

are AL-1 and MS-1, with indices of 71.9 and 73.6, respectively. 

Of the 132 counties that comprise the GOM region’s economic analysis area, 19 ranked above the 

U.S. (6 in FL-4; 4 in LA-4; 3 in TX-3; 2 in LA-1; and 1 in LA-2, TX-1, FL-1, and FL-3). Monroe County 

in FL-4 was the highest, with an index of 157.91. The lowest county is Starr County in TX-1 with an 

index of 42.12, followed by Greene County in MS-1 with 50.92 and Hamilton County in FL-2 with 51.76. 

As shown in Tables 4-24 through 4-36, the industrial composition for the EIA’s is similar. In 2010, 

all of the EIA’s had State and Local Government and Retail Trade as one of their top five ranking sectors 

in terms of employment, and all of them except MS-1 had Health Care and Social Assistance as one of 

their top five. Accommodation and Food Services is one of the top five sectors for seven of the EIA’s 
4-332 Central Planning Area Supplemental EIS 

(TX-1, LA-1, LA-3, LA-4, MS-1, FL-1, and FL-2). As part of its economic impact analysis in Chapter 

4.1.1.21.3.2, BOEMRE uses regional input-output multipliers from the commercial software IMPLAN. 

A set of multipliers is created for each EIA in the analysis area based on each EIA’s unique industry 

make-up. An assessment of the change in overall economic activity for each EIA is then modeled as a 

result of the expected changes in economic activity associated with holding the CPA proposed action. 

Table 4-38 presents the baseline employment projections used to analyze the impacts of the CPA 

proposed action and the OCS Program which, as explained in Chapter 4.1.1.21.3.4, is used for the 

cumulative impact analysis). These baseline projections assume the continuation of existing social, 

economic, and technological trends at the time of the forecast. Therefore, the projections include 

employment associated with the OCS leasing patterns and other industry trends that were prevalent prior 

to the DWH event and the subsequent drilling suspensions. However, this data still remains the best longterm forecast of regional trends for socioeconomic impact analyses of the CPA proposed action. 

Deepwater Horizon Event 

Tracking the economic and employment impacts in the GOM region as a result of the DWH event 

will be a long-term and difficult task. Many of the potentially affected jobs, like fishing charters, are selfemployed. Thus, they will not necessarily file for unemployment and will not be included in business 

establishment surveys used to estimate State unemployment levels. In addition, unemployment numbers 

in states are based on nonagricultural jobs, and the fishing industry is considered within the agriculture 

category. On the other side, it is also a challenge to estimate how many of these displaced workers have 

been hired to clean up the spill. Furthermore, the extent of the geographic areas that will be affected 

economically in the long-term is unknown, as is how long the impacts will last (e.g., if fisheries are 

irreparably damaged, affected fishermen will have no jobs to go back to). 

On May 6, 2010, this Agency announced a deepwater drilling moratorium to last through the month; 

however, it was extended 6 months to November 30, 2010. The May moratorium had the effect of 

suspending activity at all 33 rigs developing exploratory wells in deepwater. This posed new hardships 

for hundreds of oil-service companies that supply the steel tubing, engineering services, drilling crews 

and marine-supply boats critical to offshore exploration. Early estimates varied concerning the potential 

economic and employment impacts of the moratorium varied. David Dismukes, of LSU’s Center for 

Energy Studies, estimated as many as 35,000 jobs could be affected (Hargreaves, 2010). The Louisiana 

Mid-Continent Oil and Gas Association estimated a total of 800-1,400 jobs per idle rig platform were at 

risk, or roughly 34,400-60,000 throughout the Gulf economy (Louisiana Mid-Continent Oil and Gas 

Association, 2010). The Louisiana Department of Economic Development estimated that if the 

suspension of active drilling activity continued for an extended period, the State risked losing more than 

20,000 existing and potential jobs over a 12- to 18-month period (Jindal, 2010). Lawrence R. Dickerson, 

the Chief Executive of Diamond Offshore Drilling, which owns six deepwater rigs in the Gulf, stated that 

15,000-20,000 rig and associated service jobs were at risk during this period (Zeller, 2010). 

Roubini Global Economics (Teslik and Menegatti, 2010) estimated that the economic consequences 

of the spill will lead to a net loss of just under $20 billion for the U.S. economy in 2010, which will lower 

U.S. economic growth in 2010 by roughly 0.1 percent and will lower growth in the four states most 

affected (Louisiana, Mississippi, Alabama, and Florida) by 1.6 percent of their combined gross domestic 

product. They estimated that the oil and gas industry was likely to suffer the most from the spill 

($9 billion including impacts of a deepwater drilling suspension and impacts to oil and gas support 

industries), followed by tourism ($8.4 billion regionwide, with Louisiana and Florida taking the biggest 

losses), and fishing ($1.2 billion). An economist at Wells Fargo estimated that up to 250,000 Gulf jobs in 

fishing, tourism, and energy would be lost in the second half of the year (Aversa, 2010). It was estimated 

that in total, the new jobs in cleanup would not make up for what had been lost and would likely pay less 

(e.g., $15-18/hr compared with roughly $45/hr on a drilling rig), so consumers in the region would likely 

spend less as a result (Aversa, 2010). However, the degree to which new cleanup jobs offset job losses 

would vary greatly from county-to-county/parish-to-parish. As of July 6, 2010, more than 45,000 

personnel were working on the response effort (RestoreTheGulf.gov, 2010a). 

As more information became available, estimates of the impacts of the DWH event changed. An 

Inter-Agency Report on the economic effects of the deepwater drilling suspension on the Gulf Coast 

economy in September found that there had not been large increases in unemployment. Recipients of 
Description of the Environment and Impact Analysis 4-333 

unemployment insurance in three states had been asked whether their claims were related to the drilling 

suspensions. Based on the responses through September 13, 2010, only 734 suspension-related 

continuing claims had been filed in Louisiana, 22 in Mississippi, and 64 in Texas (for a total of 820). As 

noted previously, however, self-employed persons are not eligible for unemployment insurance and are 

thus not reflected in the data. The report estimated that during the 6-month period an average of 2,000 rig 

workers would have been laid off or left the Gulf Coast, or about 20 percent of the rig workers employed 

in the GOM prior to the DWH event. The report also estimated that total operator spending on leasing 

vessels, supplies, services, and materials would be reduced by about $1.95 billion as a result of the 

suspension, affecting the network of onshore businesses that serve the deepwater drilling economy. 

Including multiplier impacts, the report estimated that up to 8,000-12,000 jobs may be temporarily lost, 

but that most would return following the resumption of deepwater drilling in the GOM. As stated, 

deepwater drilling has resumed, and the pace of permit issuance will determine the rate at which these 

jobs become available. 

As of April 8, 2011, 10 permits for deepwater drilling have been awarded. At the end of November, 

27 jackups were actually working, only 5 of 25 semisubmersibles were working and only one of 11 

drillships (Greenberg, 2010). Day rates for large, deepwater, supply vessel operators dropped from an 

average $14,787 a day in October to $11,500 in November, and utilization fell from 89 percent to 81 

percent (Greenberg, 2010). As of December 2010, only three deepwater rigs had exited the Gulf since the 

deepwater suspension was implemented. However, the post-suspension delay in the resumption of 

operations was continuing, increasing the possibility that more rigs will leave the Gulf in the future. In 

addition, the offshore industry also continues to face compliance with new regulations and higher 

insurance costs, and these may potentially lead to lower levels of industry activity than prevailed prior to 

the DWH event. According to one annual study for Louisiana, Lafayette and Houma-Thibodaux face 

employment drops because of a projected slowdown in the Gulf oil and natural gas activity. The report 

projects a loss of 3,000 (2%) jobs in 2011 and another 800 (0.6%) in 2012 for Lafayette. HoumaThibodaux is forecast to have a 1,500 job loss (1.7%) in 2011 and another 500 (0.5%) in 2012 (Sayre, 

2010). The report also warns that the planned closing of the Northrop Grumman Corp. shipyard in 

suburban Avondale, which currently employs about 4,400, will be felt in early 2013 in the New Orleans 

area (Sayre, 2010). 

State figures show that employment remained relatively steady in Louisiana in August, September, 

and October, and oil and gas employment remained fairly constant (Schmidt, 2010a and 2010b; Magill, 

2010). To date, the suspension has not triggered the significant economic impacts that were originally 

estimated (and described in the preceding paragraphs). Even though many deepwater rigs that remain in 

the GOM are not currently working, drilling contractors have decided, to date, to retain most of their 

crews in the interest of holding on to drilling expertise in the hope of restarting quickly once they are able. 

Similarly, rig operators and well servicing firms have largely retained their employees (USDOC, 2010). 

Many employers have been keeping their workers busy doing maintenance and repair work. Although the 

official numbers have not changed much, the State’s count of workers does not track the cuts to hours and 

benefits that oilfield workers claim they have been experiencing as a result of the deepwater-drilling ban. 

There is evidence of some increased demand for assistance in affected areas as a result of those cuts 

(Schmidt, 2010a). Also, in the absence of active drilling, companies have no need for certain kinds of 

services and equipment, and this affects the revenues (and employment levels) of many small businesses 

in the area (Nolan, 2010). Companies, particularly independents and small businesses, have been unable 

to make new, important investments, have stopped hiring workers, and have been forced to drain their 

reserves while they sit and wait (Broder, 2010). Smaller or nonexistent paychecks also add up to less tax 

revenues along the Gulf Coast. 

In addition to the small businesses, another group that has been hard hit in recent months has been the 

shallow-water rig workers who, unlike their deepwater counterparts, are ineligible for the $100 million 

Rig Worker Assistance Fund established by BP and administered by the Baton Rouge Area Foundation. 

While there was no suspension of shallow-water drilling, it has been affected by permitting delays. 

According to a spokesman for the advocacy group Shallow Water Energy Security Coalition, some 500 

workers were laid off across the shallow-water sector through October (December 2010). Shallow-water 

driller’s woes are aggravated by the fact that these rigs operate on contracts with oil companies ranging 

from a few days to a few months. While idle deepwater rigs, which are leased out for years, keep 

bringing in cash for their owners, shallow-water rigs are in limbo when contracts end. According to 
4-334 Central Planning Area Supplemental EIS 

Dr. Dismukes at Louisiana State University, 624 deepwater rig workers started the application with the 

Baton Rouge Area Foundation, but only 343 provided a complete package (Dismukes, personal 

communication, 2010e). 

To date, U.S. State and local governments are also faring far better than forecast, largely because of 

massive cleanup spending, according to Moody’s Investor Service (Connor, 2010). Moody’s had named 

59 debt issues that might have been affected by the oil disaster, which had raised fears that populations 

might decline and that local property values and tax revenue would be decreased. Moody’s reports that 

its analysts had determined that vital government revenue, such as property taxes, utility charges, and 

State school district funding, had broadly held up and that the fiscal pressures have been manageable and 

are not likely to be of a long-term nature (Connor, 2010). 

Whatever the actual numbers turn out to be, much of the employment loss will be concentrated in 

coastal oil-service parishes in Louisiana (St. Mary, Terrebonne, Lafourche and Plaquemines Parishes) and 

counties/parishes where drilling-related employment is most concentrated (Harris County, Texas 

[Houston]; Lafayette and Iberia Parishes, Louisiana) (Nolan and Good, 2010; U.S. Dept. of Labor, Bureau 

of Labor Statistics, 2010b; USDOC, 2010). The BOEMRE will continue to monitor Federal, State, and 

public data and analyses conducted on the economic and employment impacts of the spill and provide 

updated information as it becomes available. As noted above, additional detailed information on 

employment impacts to commercial fishing, recreational fishing, and tourism can also be found in 

Chapters 4.1.1.17, 4.1.1.18, and 4.1.1.19 of this Supplemental EIS. 

4.1.1.21.3.2. Impacts of Routine Events 

Background/Introduction 

The detailed description of possible impacts on economic factors, primarily employment, from 

routine activities associated with the CPA proposed action is given in Chapter 4.2.2.1.15.3 of the 

Multisale EIS and in Chapter 4.1.16.3.2 of the 2009-2012 Supplemental EIS. The economic analysis for 

the CPA proposed lease sale focuses on the potential direct, indirect, and induced impacts of the OCS oil 

and gas industry on the population and employment of the counties and parishes in the analysis region 

defined in Chapter 3.3.5.1 of the Multisale EIS. 

Proposed Action Analysis 

Tables 4-30 and 4-31 of the Multisale EIS provide the low- and high-case employment projections for 

the CPA proposed action by economic impact area over the 40-year life. Because of the changes made to 

the exploration and development scenarios used in the analysis of the CPA proposed action, BOEMRE 

made corresponding adjustments to the employment projections. Based on these adjustments, direct 

employment (for the entire economic impact area) associated with the CPA proposed action is 

approximately 3,365-10,155 during the peak impact year for the low- and high-case scenarios. Indirect 

employment is projected at about 1,455-4,050 jobs, while induced employment is calculated to be about 

2,275-6,385. Thus, total employment in the EIA resulting from the CPA proposed action is not expected 

to exceed 7,095-20,590 jobs in any given year over the proposed action’s 40-year lifetime. Most of the 

employment related to the CPA proposed action is expected to occur in Texas (EIA TX-3) and Louisiana 

(EIA’s LA-2, LA-3, and LA-4). It should be emphasized, however, that a portion of these estimates do 

not represent “new” jobs; many of these would represent new contracts or orders at existing firms that 

would essentially keep the firm operating at its existing level as earlier contracts and orders are completed 

and filled. In other words, a portion of these 7,095-20,590 jobs would be staffed with existing company 

labor force and would simply maintain the status quo. Thus, these estimates may overestimate the actual 

magnitude of new employment effects from the proposed action. Considering Florida’s current 

opposition to oil and gas development in offshore waters and the scarcity, if not absence, of onshore 

supporting service bases, BOEMRE anticipates that very few OCS-related activities would be staged from 

Florida. 

Using the new Woods & Poole Economics, Inc. (2010) data discussed above as the baseline, 

BOEMRE recalculated the employment impacts on a percentage basis. The revised numbers do not differ 

substantially from those presented in the Multisale EIS and the 2009-2012 Supplemental EIS. 

Employment is not expected to exceed 1 percent of total employment in any given EIA of Texas, 
Description of the Environment and Impact Analysis 4-335 

Louisiana, Mississippi, Alabama, or Florida. On a percentage basis, LA-2 and LA-3 are still projected to 

have the greatest employment impacts at 1 percent and 0.5 percent, respectively. On a percentage basis, 

EIA LA-4 is still projected to have the next greatest impact at 0.3 percent, followed by TX-3 and LA-1 at 

0.2 percent. 

Summary and Conclusion 

Should the CPA proposed action occur, there would be only minor economic changes in the Texas, 

Louisiana, Mississippi, Alabama, and Florida EIA’s. This is because the demand would be met primarily 

with the existing population and labor force. The CPA proposed action is expected to generate less than a 

1 percent increase in employment in any of these subareas. Most of the employment related to the CPA 

proposed action is expected to occur in Texas (EIA TX-3) and Louisiana (EIA’s LA-2, LA-3, and LA-4). 

4.1.1.21.3.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of the possible impacts from accidental events associated with the CPA 

proposed action on economic factors, primarily employment, is presented in Chapter 4.4.14.3 of the 

Multisale EIS and in Chapter 4.1.16.3.3 of the 2009-2012 Supplemental EIS. Accidental events 

associated with the CPA proposed action, such as oil or chemical spills, blowouts, and vessel collisions, 

would likely have minimal, if any, net effects on employment. 

Proposed Action Analysis 

Chapters 4.3.1.5, 4.3.1.6, and 4.3.4 of the Multisale EIS depict the risks and number of spills 

estimated to occur for the proposed action. The probabilities of an offshore spill ≥1,000 bbl occurring 

and contacting coastal counties and parishes was used as an indicator of the risk of a slick from such a 

spill reaching sensitive coastal environments. Figure 3-7 of the 2009-2012 Supplemental EIS shows the 

Gulf of Mexico coastal counties and parishes having a risk of >0.5 percent of being contacted within 10 

days by an offshore oil spill ≥1,000 as a result of the CPA proposed action. Most counties and parishes 

have a <0.5 percent probability of an oil spill ≥1,000 bbl occurring and contacting (combined probability) 

their shorelines within 10 days; two counties in Texas and eight parishes in Louisiana have a 1-16 percent 

chance of an OCS offshore oil spill ≥1,000 bbl occurring and reaching their shoreline within 10 days as 

the result of the proposed action over its 40-year life. In Louisiana, Plaquemines Parish has the greatest 

risk (10-16%) of being contacted within 10 days by an oil spill occurring offshore as a result of the CPA 

proposed action. The BOEMRE estimates that between 5 and 15 chemical spills associated with the OCS 

Program are anticipated each year, with a small percentage of these associated with the proposed action. 

The majority of spills are expected to be <50 bbl in size; a chemical spill of ≥1,000 bbl as a result of the 

proposed action or OCS Program is very unlikely. 

The immediate social and economic consequences for the region in which a spill occurs are a mix that 

includes not only additional opportunity cost jobs and sales but also nonmarket effects such as traffic 

congestion, strains on public services, shortages of commodities or services, and disruptions to the normal 

patterns of activities or expectations. These negative short-term social and economic consequences of a 

spill are expected to be modest as measured by projected cleanup expenditures and the number of people 

employed in cleanup and remediation activities. Negative long-term economic and social impacts may be 

more substantial if fishing, shrimping, oystering, and/or tourism were to suffer or were to be perceived as 

having suffered because of the spill, or if there were substantial changes to the energy industries in the 

region as a result of the spill. Additional information on employment impacts to commercial fishing, 

recreational fishing, and tourism from accidental events can be found in Chapters 4.1.1.17, 4.1.1.18, and

4.1.1.19 of this Supplemental EIS. For a discussion of the employment impacts of catastrophic spill, see 

Appendix B. 

Net employment impacts from a spill are not expected to exceed 1 percent of baseline employment 

for any EIA in any given year even if they are included with employment associated with routine oil and 

gas development activities associated with the CPA proposed action. The employment impacts from a 

vessel collision are likely to be shorter term and less than those from a spill. 
4-336 Central Planning Area Supplemental EIS 

Summary and Conclusion 

The short-term social and economic consequences for the Gulf coastal region should a spill 

≥1,000 bbl occur includes the opportunity cost of employment and expenditures that could have gone to 

production or consumption rather the spill cleanup efforts. Nonmarket effects such as traffic congestion, 

strains on public services, shortages of commodities or services, and disruptions to the normal patterns of 

activities or expectations are also expected to occur in the short term. These negative, short-term social 

and economic consequences of a spill are expected to be modest in terms of projected cleanup 

expenditures and the number of people employed in cleanup and remediation activities. Negative, longterm economic and social impacts may be more substantial if fishing, shrimping, oystering, and/or 

tourism were to suffer or were to be perceived as having suffered because of the spill or if there were 

substantial changes to the energy industries in the region as a result of the spill. Net employment impacts 

from a spill are not expected to exceed 1 percent of baseline employment for any EIA in any given year 

even if they are included with employment associated with routine oil and gas development activities 

associated with the CPA proposed action. 

4.1.1.21.3.4. Cumulative Impacts 

Background/Introduction 

A detailed discussion of the cumulative impacts to economic factors, primarily employment, can be 

found in Chapter 4.5.15.3 of the Multisale EIS and in Chapter 4.1.16.3.4 of the 2009-2012 Supplemental 

EIS. The following is a summary of the information presented in these documents and incorporates new 

information found since their publication. 

The cumulative economic analysis focuses on the potential direct, indirect, and induced employment 

impacts of the OCS Program’s oil and gas activities in the Gulf of Mexico, together with those of other 

likely future projects, actions, and trends in the region. Most approaches to analyzing cumulative effects 

begin by assembling a list of “other likely projects and actions” that will be included with the proposed 

action for analysis. However, no such list of future projects and actions could be assembled that would be 

sufficiently current and comprehensive to support a cumulative analysis for all 132 of the coastal counties 

and parishes in the analysis area over a 40-year period. Instead of an arbitrary assemblage of future 

possible projects and actions, the analysis employs the economic and demographic projections from 

Woods & Poole Economics, Inc. (2010) to define the contributions of other likely projects, actions, and 

trends to the cumulative case. These projections are based on local, regional, and national trend data as 

well as likely changes to local, regional, and national economic and demographic conditions. Therefore, 

the projections include employment associated with the continuation of current patterns in OCS leasing 

activity as well as the continuation of trends in other industries important to the region. These Woods & 

Poole Economics, Inc.’s projections represent a more comprehensive and accurate appraisal of cumulative 

conditions than could be generated using the traditional list of possible projects and actions. The same 

regional economic impact assessment methodology used to estimate changes to employment from the 

proposed lease sale was used for the cumulative analysis. Using the new Woods & Poole Economics, Inc. 

(2010) data discussed above as the baseline, BOEMRE recalculated the employment impacts of the OCS 

Program on a percentage basis. These revised numbers do not differ significantly from those presented in 

the Multisale EIS. 

Tables 4-45 and 4-46 of the Multisale EIS present projected employment associated with the OCS 

Program. These projections have not changed for this analysis, as the exploration and development 

scenarios associated with the OCS Program did not change. Based on the model results, direct 

employment in the BOEMRE-defined EIA associated with OCS Program activities is estimated to range 

between 126,000 and 160,000 jobs during peak activity years for the low and high resource estimate 

scenarios, respectively. Indirect employment is projected between 48,000 and 62,000 jobs, while induced 

employment is projected between 83,000 and 106,000 jobs for the same period. Therefore, total 

employment resulting from OCS Program activities in the BOEMRE-defined EIA is not expected to 

exceed 257,000-328,000 jobs in any given year over the 40-year analysis period. 

In Texas, the majority of OCS-related employment is expected to occur in EIA TX-3, which also 

represents the largest projected employment level of any EIA. This employment is expected to never 

exceed a maximum of 2.2 percent of total employment in that EIA. The OCS-related employment for 
Description of the Environment and Impact Analysis 4-337 

EIA’s LA-2, LA-3, and LA-4 is also projected to be substantial. Direct employment levels in LA-2 and 

LA-3 are comparable, with LA-2 slightly higher. However, the impacts on a percentage basis are much 

higher in LA-2, reaching a maximum of nearly 20.3 percent versus about 8 percent in LA-3. However, 

the percentage analysis is highly dependent on the baseline employment projections, which are dependent 

on the size of the EIA. The EIA LA-2 has one labor market area (Lafayette) while LA-3 has two labor 

market areas (Baton Rouge and Houma). It follow that the baseline employment projections for LA-2 are 

less than (in this case, less than half) the baseline employment projections for LA-3 and that the resulting 

percentage impacts in LA-2 are more than twice as high. Nonetheless, over the last decade there has been 

a migration to Lafayette Parish (and to a lesser extent Iberia Parish) from areas throughout coastal 

Louisiana, particularly in the extraction and oil and gas support sectors. The next greatest impacts in 

percentage terms are in LA-4, LA-1, TX-3 and TX-2, respectively, with none exceeding 5 percent in any 

given year. The OCS-related employment for TX-1 and all of the Alabama, Mississippi, and Florida 

EIA’s is not expected to exceed 2 percent of the total employment in any EIA. 

Employment demand will continue to be met primarily with the existing population and available 

labor force in most EIA’s. The vast majority of these cumulative employment estimates represent 

existing jobs from previous OCS-Program actions. The BOEMRE does expect some employment will be 

met through in-migration; however, this level is projected to be small and localized and, thus, BOEMRE 

expects the sociocultural impacts from in-migration to be minimal in most EIA’s. Peak annual changes in 

the population, labor, and employment of all EIA’s resulting from the OCS Program are minimal, except 

in some parts of Louisiana. As discussed in Chapter 4.1.1.21.3.2, the CPA proposed action is expected 

to have an incremental contribution of <1 percent to the employment level in any of the EIA’s. 

Summary and Conclusion 

The OCS Program will produce only minor economic changes in the Texas, Mississippi, Alabama, 

and Florida EIA’s. The OCS Program is expected to represent <2.2 percent of employment projected in 

the EIA’s in these states. However, the OCS Program is projected to substantially impact LA-2 and LA3, with OCS-related employment expected to peak at 20.3 percent and 8 percent of total employment, 

respectively. As discussed in Chapter 4.1.1.21.3.2, the CPA proposed action is expected to have an 

incremental contribution of <1 percent to the employment level in any of the EIA’s. 

4.1.1.21.4. Environmental Justice 

The BOEMRE has reexamined the analysis for environmental justice presented in the Multisale EIS 

and the 2009-2012 Supplemental EIS, based on the additional information presented below and in 

consideration of the DWH event. No substantial new information was found that would alter the impact 

conclusion for environmental justice presented in the Multisale EIS and the 2009-2012 Supplemental EIS. 

On February 11, 1994, President Clinton issued Executive Order 12898, entitled Federal Actions to 

Address Environmental Justice in Minority Populations and Low-Income Populations, which directs 

Federal agencies to assess whether their actions have disproportionate environmental effects on people of 

ethnic or racial minorities or people living below the poverty line. Those environmental effects 

encompass human health, social, and economic consequences. The BOEMRE has examined 

environmental justice for the CPA proposed action and has provided opportunities for community input 

during the NEPA process (See Chapter 5 for a discussion of scoping and community consultation and 

coordination.). 

Environmental justice is a complex issue, and although methodologies have evolved to assess 

whether an environmental injustice has taken place, this type of analysis still poses challenges, 

particularly when considering OCS leasing decisions. First, the OCS Program in the Gulf of Mexico is 

large and has been ongoing for more than 50 years. During this period, substantial leasing has occurred 

off Texas, Louisiana, Mississippi, and Alabama. The OCS lease sales occur in Federal waters 3 mi 

(5 km) or more from shore; thus, the resulting exploration, extraction, and production activities on 

leaseholds are distant from human habitation. State offshore oil and gas leases are closer to land and their 

petroleum-related activities in State waters are generally viewed as having a greater potential for directly 

impacting coastal communities. Second, most OCS sale-related impacts that potentially might affect 

environmental justice are indirect, arising onshore as the result of industry activities in support of OCS 

exploration, extraction, and production. An extensive upstream support infrastructure system exists to 
4-338 Central Planning Area Supplemental EIS 

support offshore oil and gas and includes platform fabrication yards, shipyards, repair and maintenance 

yards, onshore service bases, heliports, marinas for crewboats and supply boats, pipeline coating 

companies, and waste management facilities. Downstream infrastructure moves hydrocarbon product to 

market and includes gas processing plants, petrochemical plants, transportation corridors, petroleum bulkstorage facilities, and gas and petroleum pipelines. This infrastructure system is both widespread and 

concentrated. Much infrastructure is located in coastal Louisiana, less in coastal Texas, and less still in 

Mississippi’s Jackson County and Alabama’s Mobile County. While many fabrication and supply 

facilities are concentrated around coastal ports, downstream processing is concentrated more in industrial 

corridors farther inland (The Louis Berger Group, Inc., 2004). 

This analysis identifies potential environmental justice impacts that might arise from these support 

activities, but they are only indirectly influenced by BOEMRE decisionmaking, and BOEMRE has no 

regulatory authority over them. Third, the resulting onshore support activities occur in the context of a 

very large and long-established oil industry. For the most part, activities generated by a new lease sale 

occur where there are ongoing ones, and the two are virtually indistinguishable from each other or from 

established land-use patterns. Each industry sector and its associated impacts are often cumulative and 

occur within a mix of the effects of other sectors in each geographic location. Several of BOEMRE’s past 

and ongoing studies (e.g., Hemmerling and Colten, 2003 and in preparation) seek to understand the 

underlying socioeconomic and potential environmental justice implications of OCS activities. Several 

ongoing studies also seek to understand the short- and long-term impacts of the recent DWH event (e.g., 

the study “Ethnic Groups and Enclaves Affected by OCS,” which was launched on August 1, 2010). The 

BOEMRE will continue to seek additional information and bases the following analysis on the best 

information currently available. 

4.1.1.21.4.1. Description of the Affected Environment 

A detailed description of environmental justice from the WPA and CPA can be found in Chapters 

4.2.1.1.13.4 and 4.2.2.1.15.4 of the Multisale EIS. Additional information regarding the additional 181 

South Area and any new information found since the publication of the Multisale EIS is presented in 

Chapter 4.1.16.4 of the 2009-2012 Supplemental EIS. The following information is a summary of the 

resource description incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, and new 

information that has become available since both documents were prepared. 

The oil and gas exploration and production industry and its associated support sectors are interlinked 

and widely distributed along the Gulf Coast. Offshore OCS-related industry operations within the CPA 

may rely on onshore facilities within the CPA, WPA, or both. As an example, Port Fourchon in 

Lafourche Parish, Louisiana, caters to 90 percent of all deepwater oil production in the GOM and roughly 

45 percent of all shallow-water rigs in the Gulf (Loren C. Scott & Associates, 2008). While this analysis 

focuses on potential impacts within the CPA, the interlinked nature of the offshore industry necessitates a 

discussion of the WPA as well. Within the GOM economic impact areas, there are 81 counties/parishes 

that contain facilities, with five as the median number of facilities. For comparative purposes, 

counties/parishes with more than five facilities are considered to contain concentrations of facilities. 

These 39 counties/parishes are then divided into three levels of infrastructure concentration: low (6-15 

facilities); medium (16-49 facilities); and high (50 or more facilities). The WPA has four high 

concentration counties/parishes, and the CPA has six, five of which are located in Louisiana. Most of the 

counties/parishes with low and medium concentrations are located in Texas (WPA) or Louisiana (CPA). 

The OCS activities (and their potential environmental consequences) are concentrated around support 

infrastructure such as ports, canals, heliports, repair yards, pipecoating facilities, and gas processing 

plants. While the coastal zone of the northern GOM is not a physically, culturally, or economically 

homogenous area, some communities within its boundaries warrant an environmental justice lens 

(Gramling, 1984b). The USEPA’s guidelines suggest different thresholds for determining whether a 

community or local population should be considered an environmental justice population. The BOEMRE 

focuses on counties/parishes with high or medium concentration of OCS-related infrastructure and defines 

minority populations as those counties/parishes that exhibit ethnic characteristics that are above 

50 percent of the total population. 

Environmental justice maps (Figures 4-15 through 4-18) display the location of oil-related 

infrastructure and the distribution of low-income and minority residents across GOM counties and 
Description of the Environment and Impact Analysis 4-339 

parishes based on U.S. Census data from 2010 and a BOEMRE-funded study on Gulf Coast OCS 

infrastructure. Ten counties/parishes are considered to have a high concentration (50 facilities or more) of 

oil-related infrastructure (Table 3-40 of the Multisale EIS). Of these 10 counties/parishes, 6 are located in 

the CPA, and of those, 3 have higher minority percentages than their respective State averages: 41 

percent minority residents are in Mobile County, Alabama; 44 percent minority residents are in Jefferson 

Parish, Louisiana; and 43 percent minority residents are in St. Mary Parish, Louisiana. Jefferson Parish, 

Louisiana, ranks second in terms of concentration of OCS-related infrastructure with 1 petrochemical 

plant, 46 terminals, 8 ship yards, and 6 platform fabrication facilities among other infrastructure types 

(Kaplan et al., in preparation). A BOEMRE-funded study, using the 2000 Census and a weighting 

scheme to identify counties with heavy concentrations of OCS infrastructure, identified a dozen areas 

within Jefferson Parish where African Americans make up more than 75 percent of the population. The 

analysis found a visual correlation between the concentration of black population and OCS-related 

infrastructure along the Harvey Canal. 

Thirteen counties/parishes are considered to have a medium concentration (16-49 facilities) of oilrelated infrastructure. Of these 13 counties/parishes, 10 are located in the CPA, and of those, 3 have 

higher minority populations than the State average: Hillsborough County in Florida and Orleans and 

St. James Parishes in Louisiana. The population of metro New Orleans declined 11 percent since 2000, 

140,845 residents in Orleans Parish alone, largely reflecting the significant job losses associated with 

Hurricane Katrina and the recession. The percentage of black population fell from 67.3 percent to 

60.2 percent. 

Poverty is defined by the Office of Management and Budget’s Statistical Policy Directive 14 and the 

U.S. Census using a set of money income thresholds that vary by family size and composition. The 

official poverty thresholds do not vary geographically, but they are updated for inflation using the 

Consumer Price Index (U.S. Census). This analysis uses the 2009 Community Survey on a county/parish 

level basis as a placeholder. Only one parish, St. Mary Parish, out of the six CPA high infrastructure 

concentration counties/parishes has a higher poverty rate than its respective State poverty rate, with 

18 percent of the parish living below the poverty line compared with the State’s 17.6 percent average. 

Four parishes (Iberia, Orleans, St. Bernard, and Vermilion) out of the 10 CPA medium infrastructure 

concentration counties/parishes had higher poverty rates than their respective State poverty rate. In the 

aforementioned Eastern Research Group study, which uses census tract data (a smaller level of 

geographic analysis), they found five areas in Jefferson Parish, Louisiana, where more than half the 

population had an income below the poverty level; this population is clustered in the northern part of the 

parish. In Orleans Parish, using 2000 data, there was not much visual correlation between areas of high 

poverty and OCS infrastructure, with the possible exception of one repair facility to the west of New 

Orleans. 

Baseline Post Hurricanes and Post-Deepwater Horizon Event 

Whether the proposed lease sale occurs within the CPA or WPA, oil and gas exploration and 

production activities would rely on an established network of support and processing facilities and 

associated labor force both within the onshore CPA and WPA. As a result, a baseline change within the 

WPA could potentially alter the relative risks of a lease sale in the CPA. Therefore, where appropriate, 

this discussion considers recent baseline changes in the WPA. On August 29, 2005, Hurricane Katrina 

made landfall on the Gulf Coast between New Orleans, Louisiana, and Mobile, Alabama. Hurricane 

Katrina had differential impacts on the Gulf Coast population. Approximately half of those displaced 

lived in New Orleans, Louisiana, where the storm heavily impacted the poor and African Americans 

(Gabe et. al., 2005). As stated in the Multisale EIS, the three states most affected also rank among the 

poorest according to the 2000 U.S. Census; Mississippi ranked second in its poverty rate, Louisiana third, 

and Alabama sixth. Approximately one-fifth (21%) of the population most directly affected by the storm 

was poor, a rate significantly higher than the national rate of 12.4 percent reported in the 2000 Census. 

While the 2008 hurricane season was particularly active in southeast Texas in the WPA, it also strongly 

affected CPA baseline conditions. Hurricane Gustav made landfall on September 1, 2008, near Cocodrie, 

Louisiana (Terrebonne Parish), and continued northwest across the state, resulting in 34 parish disaster 

declarations, which made areas eligible for disaster assistance following the storm (U.S. Dept. of 

Homeland Security, FEMA Emergency Declaration August, 2008). The affected coastal parishes also 
4-340 Central Planning Area Supplemental EIS 

have high concentrations oil-related infrastructure. Damage to Mississippi and Alabama coastal areas 

was less severe, but the National Weather Service reported 14 confirmed tornadoes from Biloxi to 

Mobile, Mississippi. 

The DWH event on Mississippi Canyon Block 252 has raised several concerns regarding OCS 

activities and environmental justice. The Gulf Coast boasts several distinct ethnic, cultural, and lowincome groups whose substantial reliance on the area’s natural resources of the marshes, barrier islands, 

and coastal beaches and wetlands can make them particularly vulnerable to the direct and indirect effects 

of environmental impacts to coastal wetlands, marshes, barrier islands, and beaches. Besides an 

economic dependence on commercial fishing and oystering, coastal low-income and minority groups rely 

heavily on these fisheries and on other traditional subsistence fishing, hunting, trapping, and gathering 

activities, to augment their diets and household incomes (see Hemmerling and Colten, 2003, for an 

evaluation of environmental justice considerations for south Lafourche Parish). Even when landloss and 

destruction caused by recent hurricanes have forced families to relocate, regular commuting has sustained 

this reliance on the natural resources of the coastal environments. While by no means a complete 

inventory of the minority, ethnic, and nationality groups that make up this diverse region and that are 

engaged in natural resource use and/or the petroleum industry, several populations of note have been 

identified to underscore the potential for environmental justice concerns: African Americans, Cajuns, 

Chitimacha, Houma, Isleños, Laotians, Mexicans, and Vietnamese. 

The DWH event and subsequent fishing closures dealt an immediate blow to many CPA coastal 

communities and may have longer term impacts by damaging fish stocks or by undermining the Gulf 

Coast seafood “brand.” Members of several minority and low-income groups, including among others 

African Americans, Cajuns, Houma, and Vietnamese, rely on the commercial seafood industry. For 

example, an estimated 20,000 Vietnamese fishermen and shrimpers live along the Gulf Coast; by 1990, 

over 1 in 20 Louisiana fishers and shrimpers had roots in Southeast Asia even though they comprised less 

than half a percent of the State’s workforce (Bankston and Zhou, 1996). As of Spring 2010, 

30-50 percent of all commercial fishers living in the Gulf of Mexico region were Vietnamese Americans, 

while 80 percent of all Vietnamese Americans in the region were connected to the seafood industry 

(Mississippi Coalition of Vietnamese Fisherfolk and Families, 2010). African Americans, although not 

exclusively, have traditionally comprised much of the fish processing and oyster shucking industries, and 

shucking houses, particularly, have provided an avenue into the mainstream economy for minority groups 

(Brassieur et al., 2000). African Americans in lower Plaquemines Parish, where Pointe a la Hache and 

other black towns such as Davant and Phoenix are found, have worked and subsisted on the natural 

resources of the regions for generations (The Louisiana Justice Institute, 2010). A representative sample 

of affidavits submitted to the Gulf Coast Claims Facility (responsible for administrating DWH event 

claims) indicates that Louisiana commercial fisherfolks customarily take home approximately 

5-15 percent of their total catch for subsistence use (United Louisiana Vietnamese American Fisherfolks, 

2010). 

Disruptions to the oil and gas industry because of the DWH event and the subsequent deepwater 

drilling suspensions have also raised equity concerns. The Multisale EIS states the following: “Evidence 

also suggests that a healthy offshore petroleum industry also indirectly benefits low-income and minority 

populations.” Recent data from the U.S. Census confirms that a sizable workforce (a little over 17,000 

workers) employed in mineral extraction live in the southeastern coastal parishes of Louisiana. One 

Agency study in Louisiana found income inequality decreased during the oil boom and increased with the 

decline (Tolbert, 1995). Prior to the DWH even, “certain rural coastal parishes [were home to] more jobs 

in their parishes than workers [residing there], implying that Louisianians in neighboring parishes rely on 

these areas for their employment” (Plyer and Campanella, 2010). Plaquemines Parish, for example, was 

home to close to 12,000 jobs, but only about 7,000 workers, and 11.5 percent of Terrebonne Parish’s jobs 

were in the oil and gas industry. The long-term socioeconomic impact to low-income and minority 

communities because of industry uncertainty has the potential to reverberate across the region. 

The DWH is one of three substantial crises experienced by Louisiana coastal communities during the 

last 6 years, and the environmental justice concerns from future events must be considered in this context. 

First, southeast Louisiana is losing coastal land from erosion and subsidence because of both natural 

processes (e.g., hurricanes) and human activities (e.g., control and diversion projects) (Morton, 2003). 

For example, since measurements began in 1956, 23 percent of the lands protecting the New Orleans 

metropolitan area from storm surges have converted to open water 1956 (Liu and Plyer, 2010). Besides 
Description of the Environment and Impact Analysis 4-341 

the decreased hurricane and oil-spill protections, rapid landloss and habitat fragmentation has impacted 

the ability to make a living, and flooding has even caused abandonment of whole communities. The 

second crises to impact the region includes the 2005/2008 hurricane season, consequences of which have 

been discussed above. While tropical weather is normal, low income and minority groups may bear a 

larger burden than the general population. An estimated 4,500 American Indians living on the southeast 

Louisiana coast lost their possessions to Hurricane Katrina according to State official and tribal leaders. 

Cajuns were also impacted by Katrina, and especially by Hurricane Rita, whose 20-ft (6-m) storm surges 

flooded low-lying communities in Cameron, Calcasieu, and other coastal parishes. Close to 90 percent of 

Louisiana Vietnamese live in seven southern parishes: Orleans, Jefferson, East Baton Rouge, St. Mary, 

Vermilion, Terrebonne, and Lafourche (Bankston and Zhou, 1996). The New Orleans East Vietnamese 

community of Village de L’Est was almost entirely flooded by levee failures following Hurricane 

Katrina. The third crises is the DWH event. Cumulatively, such events can reduce community resiliency 

and increase vulnerability to future hazards, opening them up to disproportionate affects from future 

catastrophic events. 

Waste Management of the Deepwater Horizon Event Waste 

The USEPA’s standards exempt oil and gas exploration and production wastes from Federal 

hazardous waste regulations. This exemption does not preclude more stringent State and local regulation 

and USEPA recognizes that exploration and production wastes could present a human health hazard if not 

properly managed (USEPA, 2002). However, wastes from oil spills are not exempt, and the DWH event 

has raised the additional environmental justice concern as to whether or not low-income and minority 

groups have been disproportionately impacted by the disposal of wastes associated with the DWH event’s 

containment and cleanup. Disposal procedures involved sorting waste materials into standard “waste 

stream types” at small, temporary stations and, then, sending each type to existing facilities that were 

licensed to dispose of them. The location of temporary sorting stations was linked to the location of 

containment and cleanup operations. Hence, future locations of any sorting stations would be determined 

by the needs of cleanup operations. However, waste disposal locations were determined by the 

specializations of existing facilities and by contractual relationships between them and the cleanup and 

containment firms. Although, in the case of the DWH event, most cleanup occurred in the CPA, but 

disposal occurred in both the CPA and WPA. The requirements of the cleanup operations would likely 

determine the use of facilities in both the CPA and WPA should a future event occur. Tables 4-39 and 

4-40 identify the DWH waste disposal sites that received the greatest percentages of waste and the waste 

types received. Table 4-41 also shows minority and low-income percentages, as well as the density of 

populations living within 1 mi (1.6 km) of each site. Figure 4-19 is a map that shows the location of all 

sites that received DWH waste. Argonne National Laboratory reported that there are 46 waste 

management facilities that service the oil and gas industry along the GOM, with 18 in Louisiana, 18 in 

Texas, 5 in Mississippi, 4 in Alabama, and 1 in Florida (Puder and Veil, 2006). Louisiana received about 

82 percent of the DWH event’s liquid waste recovered; of this, 56 percent was manifested to mud 

facilities located in Venice, Plaquemines Parish, Louisiana, and in Port Fourchon, Lafourche Parish, 

Louisiana; it was then transferred to a processing facility in Port Arthur, Texas. The waste remaining 

after processing was sent to deep well injection landfills located in Fannett and Big Hill, Texas. The sites 

located in Venice and Port Fourchon, Louisiana, and in Port Arthur, Fannett, and Big Hill, Texas, have 

low minority populations, but a few of these areas have substantial poverty rates relative to State and 

county means. 

4.1.1.21.4.2. Impacts of Routine Events 

Background/Introduction 

A detailed analysis of the routine impacts of OCS activities on low-income and minority communities 

and environmental justice as a whole for the CPA proposed action can be found in Chapter 4.2.2.1.15.4 of 

the Multisale EIS and in Chapter 4.1.16.4.2 of the 2009-2012 Supplemental EIS, respectively. Impact 

analyses for the 181 South Area that include new information since publication of the Multisale EIS are 

presented in Chapter 4.1.16.4.1 of the 2009-2012 Supplemental EIS. Chapter 4.1.1.21.4.1 describes the 

widespread presence of an extensive OCS support system and associated labor force, as well as economic 
4-342 Central Planning Area Supplemental EIS 

factors related to OCS activities. The following information is a summary of the impact analysis 

incorporated from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has 

become available since both documents were prepared. 

Impact-producing factors associated with the CPA proposed action that could affect environmental 

justice include the following: (1) potential infrastructure changes/expansions including (a) fabrication 

yards, (b) support bases, and (c) onshore disposal sites for offshore waste; (2) increased commuter and 

truck traffic; and (3) employment changes and immigration. Possible changes/expansions/increases to 

any of these routine impact-producing factors of OCS activities occur in the context of the long-lived 

State and Federal oil and gas leasing programs and as incremental additions to a robust offshore oil and 

gas industry. As a result, the impacts from routine events produced by the CPA proposed action due to 

these factors are also incremental. Particularly in the case of potential social impacts, it is often not 

possible to separate out each additional new OCS Program effect from ongoing impacts because dynamic 

economic and political factors can influence investment decisions that, one way or another, will 

reverberate through many of the OCS economic impact areas. While individual sales have little influence 

on the factors causing impacts from routine events, the overall OCS Program may have more. For this 

reason, the factors considered in this chapter are explored in more detail in the cumulative analysis 

Chapter 4.1.1.21.4.4. Offshore operations within the CPA may be supported by onshore facilities within 

the WPA. For example, Gulf Coast States have a dedicated industry-specific network of offsite 

commercial disposal companies and facilities. Therefore, waste produced from activities in the CPA 

brought onshore at Port Fourchon in Lafourche Parish, Louisiana, may be sent to processing facilities in 

Texas and finally sent to deep well injection landfills in Fannett or Big Hill Texas (Puder and Veil, 2006). 

Therefore, this analysis of possible impacts due to the CPA lease sale addresses potential impacts from 

the WPA as well. The BOEMRE estimates that production from the CPA proposed action would be 

0.801-1.624 BBO and 3.332-6.560 Tcf of gas, which is a marginal decrease in production from the last 

lease sale.

Proposed Action Analysis 

The Executive Order mandating an environmental justice analysis arose out of cases where minority 

and/or low-income communities disproportionately bore the environmental risk or direct burdens of 

industrial development or Federal actions. As discussed in Chapter 4.1.1.21.4.1, the OCS Program in the 

GOM is large and has been ongoing for more than 50 years. While the program is offshore, onshore 

activities related to it occur within a mix of communities whose economies are linked in various ways and 

at differing levels to its many industrial sectors. 

Fabrication/shipbuilding yards and port facilities are major infrastructure types that demonstrate the 

interlinked nature of OCS activity within the GOM and pose potential environmental justice risks. As 

mentioned earlier, CPA oil and gas exploration and production help to maintain ancillary industries 

within the WPA, including waste processing facilities. Over one-third (28 facilities) of the U.S. major 

shipbuilding yards are located on the GOM. Of these, most facilities are concentrated in a 200-mi 

(322-km) area between New Orleans, Louisiana, and Mobile, Alabama. The offshore oil industry relies 

heavily on specialized port infrastructure that specifically serves the need of the industry. Such activities 

as repair and maintenance of supply vessels, fabrication yards, and supply bases tend to be located in 

ports nearest to offshore drilling operations. Thus, the 34 OCS-related service bases are mainly 

concentrated on the coast of Louisiana, with a handful located in Mississippi, Alabama, and Florida (The 

Louis Berger Group, Inc., 2004). Since the CPA proposed action would help to maintain ongoing levels 

of activity rather than expand them, it would not generate new infrastructure demand sufficient to raise 

siting issues. Also, prior to construction, any new OCS-related onshore facility would first be required to 

receive approval by relevant Federal, State, county and/or parish, and community governments with 

jurisdiction. The BOEMRE assumes that any new construction would be approved only if it were 

consistent with appropriate land-use plans, zoning regulations, and other State/regional/local regulatory 

mechanisms. For these reasons, this Supplemental EIS considers infrastructure projections only for the 

cumulative analysis (Chapter 4.1.1.21.4.4). 

All material that moves to and from an offshore platform goes through an onshore service base. 

Although support and transport operations are spread throughout the Gulf Coast, most producing 

deepwater fields have service bases in southeast Louisiana and much of this goes through Port Fourchon 
Description of the Environment and Impact Analysis 4-343 

in Lafourche Parish, Louisiana. Port Fourchon has grown in recent decades, in large measure due to its 

role in servicing the deepwater OCS, and it is currently undergoing a 400-ac (162-ha) expansion. 

Indicating the growth of the port, port operating revenues with a 5 percent annual increase of the lease 

rental rate rose from $3.38 million in 1996 to $6.16 million in 2000 (Port Services 22). 

LA Hwy 1 is the primary north-south corridor through Lafourche Parish and is the principal 

transportation route for trucks entering and exiting Port Fourchon. According to the LA 1 Coalition, a 

nonprofit corporation working to improve LA Hwy 1, between 1991 and 1996, there were over 5,000 

accidents along this largely rural two-lane highway. According to some studies, LA Hwy 1’s fatality rate 

is double that of similar highways (LA 1 Coalition, 2010a). Additionally, LA Hwy 1 is the only means of 

evacuation for thousands of people. Approximately 35,000 people, including 6,000 offshore workers, use 

LA Hwy 1 for hurricane evacuations (LA 1 Coalition, 2010a). According to one study, the average daily 

traffic along LA Hwy 1 appears to be heavily influenced by the overall level of oil and gas activities and 

due to increased demand, particularly for deepwater services (Guo et al., 1998). Residents along the 

highway have expressed concern over LA Hwy 1’s adequacy for traffic congestion, desiring improved 

hurricane evacuation, and emergency medical transportation routes (USDOT, Federal Highway 

Administration, 2004). 

While local governments near the service bases have gained revenue from the increased activity 

within their jurisdictions, the demands for additional services and facilities resulting from oil and gas 

operations have sometimes exceeded growth in the revenue stream. A Federal cost share helped support 

the construction of the Leeville Bridge in 2009, considered the weakest link of the LA Hwy 1 system; the 

two-lane Leeville overpass is expected to open to traffic in November 2011 (LA 1 Coalition, 2010b). A 

proposed 27.5 mi (44.3 km) of improvements to the Port Fourchon highway system have yet to be 

funded, and continued growth of Port Fourchon and associated road traffic would add to an increased risk 

for users of and residents along the highway. As described in Chapter 4.1.1.21.4.1, community string 

settlement patterns in the area (in this case, on high ground along LA Hwy 1 and Bayou Lafourche) mean 

that all income groups would be affected by any increased traffic alike. For considering environmental 

justice, the percentage of a group’s population within an affected area is often compared with the 

percentage of that population for the state. Using this method, two minority populations are at greater 

risk. Hispanics are 1.36 times more likely to live along the transportation corridor, and Native Americans 

are twice as likely to live along the transportation corridor than anywhere else in the parish (Hemmerling 

and Colten, 2003). While the majority of OCS-related infrastructure in south Lafourche Parish is near 

where the Houma Indian population resides, the CPA proposed action would not significantly alter this 

preexisting situation. Over the last two decades, the area has been experiencing increased truck traffic 

and its associated effects due to increasing offshore-related activities at Port Fourchon. Since the CPA 

proposed action would significantly alter this preexisting situation, minority and low-income populations 

would not sustain disproportionate adverse effects from the proposed action. 

The development of any new oilfield would result in an increase in hazardous materials transported 

onshore. An estimated 0.2-2.0 bbl of total drilling waste are produced for each vertical foot drilled 

(USEPA, 2000b, p. 37), although not all oilfield waste is considered hazardous material. The BOEMRE 

rules require that all waste considered hazardous be transported onshore and disposed of, which lowers 

the risks to the environment but increases the risk to those people living along the hazardous 

transportation routes (NTL 2009-G35, USDOI, MMS, 2009e). The USDOT currently recommends a 

default isolation distance of one-half mile around any roadway involved in a hazardous chemical fire. 

Argonne National Laboratory reported that there are 46 waste management facilities that service the oil 

and gas industry along the GOM, with 18 in Louisiana, 18 in Texas, 5 in Mississippi, 4 in Alabama, and 1 

in Florida (Puder and Veil, 2006). Because a relatively small amount of waste results from a single sale 

and because of the difficulty of separating out the relative contribution of all OCS waste from municipal 

waste in general or distinguishing the effects on nearby communities of OCS waste disposal from the 

disposal of other waste, this Supplemental EIS addresses the marginal contribution of the CPA proposed 

action on waste issues as part of the cumulative analysis (Chapter 4.1.1.21.4.4). While most waste 

disposal facilities along the GOM suffered little reported damage during recent hurricane seasons, a 

discussion of potential impacts to these sites as a result of storms is addressed in the cumulative analysis 

as well. 

Because of Louisiana’s extensive oil-related support system (Chapter 4.1.21.1), that State is likely to 

experience more employment effects related to the CPA proposed action than are the other coastal states. 
4-344 Central Planning Area Supplemental EIS 

As has been the case with several prior lease sales, Lafourche Parish, Louisiana, is likely to experience 

the greatest concentration of these benefits. The BOEMRE employment projections can neither estimate 

the socioeconomic or ethnic composition of new employment nor identify the communities in which that 

employment would likely occur. Sectors such as the fabrication industry and support industries (e.g., 

trucking) employ minority workers and provide jobs across a wide range of pay levels and 

educational/skill requirements (Austin et al., 2002a and 2002b; Donato et al., 1998). Also, evidence 

suggests that a healthy offshore petroleum industry does indirectly benefit low-income and minority 

populations. For example, one Agency study in Louisiana found income inequality decreased during the 

1970’s oil boom and increased with the mid-1980’s decline (Tolbert, 1995). Because of the expected 

concentration of employment effects in Lafourche Parish, it is also the only parish where the additional 

OCS-related activities and employment may be sufficient to increase stress to its infrastructure. For 

example, one study found that because of local labor shortages in the past, employers actively recruited 

foreign employees including Laotian refugees and Mexican migrant workers. This trend has, in turn, 

applied pressure on available housing stocks within some GOM coastal communities that exhibited 

varying degrees of results in incorporating new residents into local communities (Donato, 2004). 

However, these effects arose during a time of a booming economy and high employment in general. 

According to BOEMRE estimates, the CPA proposed action would provide little additional employment 

growth. Instead, it would have the effect of maintaining current activity and employment levels, which is 

expected to have beneficial, although limited, direct and indirect employment effects to low-income and 

minority populations. 

While a reevaluation of the baseline conditions pertaining to environmental justice was recently 

conducted as a result of the recent DWH event, it is yet to be seen how issues like new industry 

regulations and long-term biological impacts of the spill will affect minority and low-income 

communities residing along the CPA coast. 

Summary and Conclusion 

Because of the existing extensive and widespread support system for OCS-related industry and 

associated labor force, the effects of the CPA proposed action are expected to be widely distributed and to 

have little impact. This is because the proposed action is not expected to significantly change most of the 

existing conditions, such as traffic or the amount of infrastructure. In general, who would be hired and 

where new infrastructure might be located is impossible to predict but, in any case, it would be very 

limited. Because of Louisiana’s extensive oil-related support system, that State is likely to experience 

more employment effects related to the CPA proposed action than are the other coastal states, and 

because of the concentration of this system in Lafourche Parish, that parish is likely to experience the 

greatest benefits from employment benefits and burdens from traffic and infrastructure demand. 

Similarly, impacts related to the CPA proposed action are expected to be economic and to have a limited 

but positive effect on low-income and minority populations, particularly in Louisiana and Lafourche 

Parish. However, given the low levels of expected effects and given the existing distribution of the 

industry and the limited concentrations of minority and low-income peoples, the CPA proposed action is 

not expected to have a disproportionate effect on these populations even in Lafourche Parish. 

The CPA proposed action is not expected to have disproportionate high/adverse environmental or 

health effects on minority or low-income people. 

4.1.1.21.4.3. Impacts of Accidental Events 

Impacts of accidental impacts on environmental justice for the CPA proposed action can be found in 

Chapter 4.4.14.4 of the Multisale EIS. Impact analyses for the 181 South Area that includes any new 

information since publication of the Multisale EIS is presented in Chapter 4.1.16.4.3 of the 2009-2012 

Supplemental EIS. The following information is a summary of the impact analyses incorporated from the 

Multisale EIS and the 2009-2012 Supplemental EIS, and new information available since both documents 

were prepared. 
Description of the Environment and Impact Analysis 4-345 

Proposed Action Analysis 

Impact-producing factors associated with the CPA proposed action that could affect environmental 

justice include (1) oil spills, (2) vessel collisions, and (3) chemical/drilling-fluid spills. These factors 

could affect environmental justice through (1) direct exposure to oil, dispersants, degreasers, and other 

chemicals that can affect human health; (2) decreased access to natural resources due to environmental 

damages, fisheries closures, or wildlife contamination; and (3) proximity to onshore disposal sites used in 

support of oil and chemical spill cleanup efforts. The DWH event was an accidental event of catastrophic 

proportion and should be distinguished from accidental events that are smaller in scale and occur more 

frequently. Detailed analysis of a high-impact, low-probability catastrophic event such as the DWH event 

may be found in Appendix B. Actions occurring within the CPA may impact environmental justice 

within the WPA, and vise versa. Facilities located on the coasts of the CPA may provide support for 

offshore activities on the WPA, and vise versa. Oil and chemical spills on the CPA may be carried by 

winds and currents to the coasts of the WPA, and vise versa. As a result, a discussion of a potential 

accidental event within the CPA proposed action area addresses potential impacts of accidental events to 

environmental justice both in the CPA and the WPA. 

Potential oil spills including surface spills and underwater well blowouts may be associated with 

exploration, production, or transportation phases of the CPA proposed action. Detailed risk analysis of 

offshore oil spills  1,000 bbl, 1,000 bbl, and coastal spills associated with the CPA proposed action is 

provided in Chapters 4.3.1.4, 4.3.1.6, and 4.3.1.7 of the Multisale EIS, respectively. When oil is spilled 

in offshore areas, much of the oil volatilizes or is dispersed by currents, so it has a low probability of 

contacting coastal areas. Low-income and minority populations might be more sensitive to oil spills in 

coastal waters than the general population because of their dietary reliance on wild coastal resources, their 

reliance on these resources for other subsistence purposes such as sharing and bartering, their limited 

flexibility in substituting wild resources with purchased ones, and their likelihood of participating in 

cleanup efforts and other mitigating activities. Table 3-7 contains the estimated number of oil spills that 

could happen in Gulf coastal waters as a result of an accidental event associated with the CPA proposed 

action. 

Vessel collisions may be associated with exploration, production, or transportation activities that 

result from the CPA proposed action and are the most common source of OCS-related spills. Chapter 

4.3.3 of the Multisale EIS provides a detailed discussion of vessel collisions. The BOEMRE data show 

that, from 1996 through 2005, there were 129 OCS-related collisions. The majority of vessel collisions 

involve service vessels colliding with platforms or pipeline risers, although sometimes vessels collide 

with each other. These collisions often result in spills of various substances, and while most occur on the 

OCS far from shore, collisions in coastal waters can have consequence to low-income and minority 

communities. For example, on July 23, 2008, a barge carrying heavy fuel collided with a tanker in the 

Mississippi River at New Orleans, Louisiana. Over several days the barge leaked an estimated 419,000 

gallons of fuel. From New Orleans to the south, 85 mi (137 km) of the river were closed to all traffic 

while cleanup efforts were undertaken, causing a substantial backup of river traffic (USDOC, NOAA, 

2008c). Downriver from the collision, cities and parishes that pull drinking water from the river (i.e., 

Gretna, Algiers, and St. Bernard and Plaquemines Parishes) shut their water intakes out of fear of possible 

treatment system contamination (Tuler et al., 2010). Not only can these types of events erode public 

confidence in governmental and corporate institutions, they may compromise municipal services for 

which low-income communities may be financially unable to find private market substitutions, interfere 

with people’s ability to use natural resources, or even interfere with people’s ability to travel to work, as 

in the case of this spill which temporarily shutdown ferry service between Algiers and downtown New 

Orleans. These types of events may impact an entire region, but low-income and/or minority groups 

lacking financial or social resources may be more sensitive and less equipped to cope with the disruption 

these events pose. While this event did not involve OCS-related transportation, it is an example of the 

types of impacts from an accidental spill that could have environmental justice consequences. 

Chemical and drilling-fluid spills may be associated with exploration, production, or transportation 

activities that result from the CPA proposed action. Chapter 4.3.4 of the Multisale EIS provides a

detailed discussion of chemical and drilling-fluid spills. Each year, between 5 and 15 chemical spills are 

expected to occur; most of these are ≤50 bbl in size. Large spills are much less frequent. For example, 

from 1964 to 2005, only two chemical spills of ≥1,000 bbl occurred. Dispersants are of particular 
4-346 Central Planning Area Supplemental EIS 

concern for human health because, while dispersants are a relatively common product used to clean and 

control oil spills, they can evaporate from fresh crude and weathered oil and can come ashore as a result 

of burning oil out at sea. While additional production chemicals are needed in deepwater operations 

where hydrate formation is a possibility, overall spill volumes are expected to remain stable because of 

advances in subsea processing. 

With the exception of a catastrophic accidental event, such as the DWH event, the impacts of oil 

spills, vessel collisions, and chemical/drilling fluid spills are not likely to be of sufficient duration to have 

adverse and disproportionate long-term effects for low-income and minority communities in the analysis 

area. As described earlier, low-income and/or minority groups lacking financial or social resources may 

be more sensitive and less equipped to cope with the disruption these events pose over the short term, but 

again, these smaller events should not have disproportionate long-term affects on low-income and 

minority communities. 

Deepwater Horizon Event 

While it is still too early to determine the long-term social impacts that may result from the DWH 

event, anecdotal evidence from media coverage and phone survey studies suggest possible trends that 

may represent disproportionate effects to low-income and minority communities. The National Center for 

Disaster Preparedness at the Mailman School of Public Health at Columbia University, in partnership 

with the Children’s Health Fund, conducted a phone study (through the Marist Poll) between July 19 and 

July 25, 2010, of 1,203 adult residents of Louisiana and Mississippi living within a 30-minute drive from 

the Gulf of Mexico (Abramson et al., 2010). Survey respondents earning less than $25,000 reported 

having lost income as a result of the DWH event, and they were more likely than were higher earners to 

report physical (defined as respiratory symptoms or skin irritations) and mental health effects among 

themselves and their children. Black respondents were also more likely to report physical health 

problems both for their children and themselves as a result of the DWH event (Abramson et al., 2010). In 

a study of communities near the Exxon Valdez spill, Palinkas et al. (1992) suggest that cultural differences 

played an important role in the perception of the psychological damage produced by the disaster, which 

was related to “the cleaning work in which the people were involved and also the damage to fishing 

grounds, the main sustenance of these communities” (Palinkas et al., 1992). This work underscores the 

importance of the varying capacities of affected groups to cope with these types of events. 

The Gulf Coast Claims Facility (GCCF) Program, administered by the Federal Government’s Claims 

Administrator Kenneth R. Feinberg, has provided data on DWH spill claimants divided by claim type, 

payout amount, and county/parish in which the claimant worked or originated from. The fund is the 

official way for individuals and businesses to file claims for costs and damages incurred as a result of the 

oil discharges due to the DWH event. While not organized by minority or income group, these data allow 

us to identify where claims are being made and to compare this with environmental justice communities 

of note. In Table 4-42, total GCCF Program claimants as of November 25, 2010, are divided by state and 

at what stage the claimant is within the claims process. A total of 450,711 claimants, including 

individuals and businesses (claimants may have one or more claim type) have filed for some kind of 

emergency or final payment. These claims include claims for removal and cleanup costs, real or personal 

property, lost earnings or profits, loss of subsistence use of natural resources, and physical injury/death 

directly or indirectly because of the DWH event (see Table 4-42 for a state-by-state break down). Many 

of these coastal counties and parishes contain large metropolitan centers as well as beach communities 

with economies based at least partially on tourism and recreation. Claimants can range from charter boat 

operators working out of Florida to bartenders working in downtown New Orleans. Either the direct 

effects of the DWH event or the indirect effects caused by altered perception were grounds for claims, if 

loss could be demonstrated. These figures include claimants living within the county or parish where the 

claim was made, claimants claiming losses while working in the county or parish where the claim was 

made, or both. Because impacted industry may employ low-income or minority workers, this analysis 

considers both businesses and individuals within a parish or county because both could result in potential 

environmental justice consequences. 

Claimants were from coastal counties/parishes; there is no observable relationship between lowincome or high-minority communities and number of claims. Figure 4-20 displays the distribution of the 

GCCF Program’s claimants and the average amount paid to each claimant by county/parish. Several 
Description of the Environment and Impact Analysis 4-347 

high- or medium-OCS infrastructure counties/parishes of environmental justice concern had high 

numbers of residents, workers, or both claiming losses. In Mobile County, Alabama, the GCCF Program 

awarded 9,515 claimants a total of $144,886,265. In Florida, 189 claimants were awarded $2,540,400 in 

Miami-Dade County and 303 claimants were awarded $4,765,700 in Hillsborough County. In Louisiana, 

22,320 claimants were awarded a total of $227,338,000 in Orleans Parish; 2,130 claimants were awarded 

a total $86,645,800 in Plaquemines Parish; 1,942 claimants were awarded $38,135,100 in St. Bernard 

Parish; and 1,821 claimants were awarded $47,459,000 in Lafourche Parish. Harrison County, 

Mississippi, which encompasses Biloxi and Gulfport and is home to a 33 percent minority population, had 

8,252 claimants awarded $111,699,036.

Chapter 4.1.1.21.4.1. discusses the DWH event’s waste disposal system. While there are concerns 

about whether locations would worsen existing environmental injustices, waste disposal locations were 

determined by the specializations of existing facilities and by the contractual relationships between them 

and cleanup and containment firms. 

Subsistence 

While users of coastal waters may trend towards the relatively affluent, because of the limited ability 

of low-income and minority subsistence users to acquire comparable substitutes for Gulf of Mexico 

natural resources, they may be particularly sensitive to an oil spill and related fishery closures. Several 

ethnic minority and low-income groups rely substantially on subsistence-based activities for food, shelter, 

clothing, medicine, or other minimum necessities of life (e.g., see Hemmerling and Colten, 2003, for an 

evaluation of environmental justice considerations for south Lafourche Parish). The DWH event and the 

resulting NOAA fishing closures interrupted access to these resources for weeks or months depending on 

the area. As of November 27, 2010, over 29,722 DWH emergency advance payments claims had been 

filed claiming loss of subsistence use of natural resources. Of these many claims, only five had been paid 

out at a total of $13,000 distributed among the five claimants. Louisiana had the lion’s share of claimants 

with 16,554 individuals claiming loss of subsistence use of natural resources, followed by Mississippi 

with 6,299 claims, Alabama with 4,119 claims, and Florida with 2,473 claims. To qualify for emergency 

funds, claimants were asked to identify the specific natural resource that had been injured, destroyed, or 

lost as a result of the DWH event; to describe the actual subsistence use for the natural resource; and to 

describe to what extent the subsistence use was affected by the damaged or destroyed natural resource 

using documentation such as store and barter receipts showing the replacement costs claimed (Gulf Coast 

Claims Facility, 2010b). The GCCF Program told the New Orleans newspaper, The Times-Picayune, that 

a claimant needs to “show documentation on their heritage, their history, and their having lived off the 

land” (Alexander-Bloch, 2010). In the Vietnamese fishing communities of Louisiana, however, these 

requirements have proven vague and challenging. Fishers save anywhere from 5 to 25 percent of their 

catch that they do not sell at the dock to feed themselves and immediate and extended family members or 

friends, and to contribute to community gatherings, such as weddings, church functions, local festivals, or 

to barter for other seafood, fruit, or vegetables (Alexander-Bloch, 2010). The BOEMRE is currently 

proposing a subsistence study of the Gulf Coast to better document subsistence distribution networks. 

Health 

Prior research on the health effects of oil spills have focused primarily on the acute physical 

symptoms of cleanup workers and wildlife caretakers. Of the 38 accidents involving supertankers and 

resulting in large oil spills throughout the world, only seven studies on the repercussions of the exposure 

of spilled oils on human health have been completed. Aguilera et al. (2010) compiled and reviewed these 

studies for patterns of health effects and found evidence of the relationship between exposure and “acute 

physical, psychological, genotoxic, and endocrine effects in the exposed individuals.” Acute symptoms 

from exposure to oil, dispersants, and degreasers include headaches, nausea, vomiting, diarrhea, sore 

eyes, runny nose, sore throat, cough, nose bleeds, rash, blisters, shortness of breath, and dizziness 

(Sathiakumar, 2010). Sathiakumar also compiled and reviewed most of post-oil spill health studies and 

found that hydrocarbons were below occupational safety levels and that the level of benzene did not 

exceed threshold limit values. There has been concern regarding the use of the dispersant Corexit 952, 

which according to the New Jersey Department of Health, “may be absorbed through the skin; [and] 

should be handled as a carcinogen...[because it] can irritate the nose and throat; can cause nausea, 
4-348 Central Planning Area Supplemental EIS 

vomiting; diarrhea and abdominal pain, can cause headache, dizziness, lightheadedness, and passing out 

and may damage the liver and kidneys” (Trapido, 2010). The USEPA monitoring data has so far shown 

that the use of dispersants during the DWH event did not result in a presence of chemicals that surpassed 

human health benchmarks (Trapido, 2010). Studies of possible long-term health effects from exposure to 

either the DWH event’s oil or dispersants, such as the possible bioaccumulation of toxins in tissues and 

organs, are lacking and the potential for the long-term human health effects are largely unknown 

(although the National Institutes of Health has proposed such a study). Sathiakumar also suggests longterm studies to clarify potential genotoxic and endocrine changes. 

As of November 27, 2010, the GCCF Program has received 8,638 claims for emergency advance 

payment for physical injury/death. Of those, 18 have been paid at a total of $14,336.50. As of the end of 

September 2010, U.S. poison control centers had taken 1,172 exposure calls involving physical exposure 

to an oil-spill-related toxin (e.g., oil, dispersant, food contamination, or other associated toxin) and 681 

information calls from persons with questions about the medical impact of the DWH event. Most calls 

originated from the Gulf States and most exposures had come via inhalation, although some were through 

dermal exposure. The most common symptoms included headaches, nausea, vomiting, diarrhea, throat 

irritation, eye pain, coughing/choking, and dizziness (Trapido, 2010). Sathiakumar’s review also found 

that, in prior post-spill cleanup efforts, the duration of cleaning work was a risk factor for acute toxic 

symptoms and that seamen had the highest occurrence of toxic symptoms compared with volunteers or 

paid workers. Therefore, participants in the DWH “Vessels of Opportunity” program, which recruited 

local boat owners (including Cajun, Houma Indian, and Vietnamese fishermen) to assist in cleanup 

efforts, would likely be one of the most exposed groups. African Americans are thought to have made up 

a high percentage of the cleanup workforce. The OSHA released two matrices of gear requirements for 

onshore and offshore Gulf operations that are organized by task (OSHA). Of past oil-spill workers, 

uninformed and poorly informed workers were at more risk of exposure and symptoms, demonstrating the 

importance of education and proper training of workers (Sathiakumar, 2010). One of the most serious 

health hazards reported was heat; about 740 heat-related events (i.e., illnesses) were reported for workers 

involved in cleanup (U.S. Dept. of Labor, OSHA, 2010). 

The National Oceanic and Atmospheric Administration, the Food and Drug Administration, and State 

regulators have coordinated efforts to help prevent oil-tainted seafood from reaching the market. An 

assumption of the Food and Drug Administration’s guidelines, however, is that people eat two meals of 

fish and one meal of shrimp per week, with no more than 3 ounces of shrimp per meal (approximately 4 

jumbo shrimp). A Natural Resources Defense Council online survey of 547 Gulf Coast residents in 

Louisiana, Mississippi, Alabama, and Florida was conducted from August through October 2010 to assess 

seafood consumption rates in the Gulf coastal zone. Online survey tools generally suffer from an 

unknown level of selection bias; however, these numbers still provide at least a snapshot of local seafood 

consumption patterns, particularly for minority subsistence-reliant groups. The Asian/Pacific Islander 

ethnic group surveyed had an average fish consumption frequency of 5 times per week and median fish 

consumption frequency of 2 times per week, with some individuals reporting to eat fish 5-8 times per 

week (Natural Resources Defense Council, 2010). Native Americans and Asian/Pacific Islanders 

consumed oysters more frequently as well. The Asian ethnic group surveyed also had an average and 

median crab consumption frequency of 1 time per week and some respondents reporting to consuming 

crab 4 times per week. The Natural Resources Defense Council calculated total daily consumption rates 

in grams(g)/day for all respondents and found that the median daily consumption for the study as a whole 

was 48g/day, respondents from Louisiana rural coastal communities was 53.3g/day, and respondents from 

Vietnamese-American communities in Louisiana and Mississippi was 64g/day. All consumption rates 

exceeded the Food and Drug Administration’s assumptions. In Gulf coastal areas, low-income and 

minority groups are heavy subsistence users of local seafood. The concern is that heavy subsistence users 

face higher than expected, and potentially harmful, exposure rates to PAH’s from the DWH event. In a 

study following the MV Erika spill off the coast of France, rats were fed oil-contaminated mussels daily 

for 2 and 4 weeks. No evidence of genotoxicity was observed in the blood samples, although significant 

increases in DNA damage were observed in the liver and the bone marrow of the rats. The intensity of 

the DNA damage increased with the PAH contamination level of the mussels (Aguilera, 2010). Actual 

levels of exposure are unknown as are the potential health effects from higher than expected exposure, but 

State and local health monitoring and Federal health studies are either ongoing or in the proposal phase 

(Mackar, 2010). 
Description of the Environment and Impact Analysis 4-349 

Summary and Conclusion 

Chemical and drilling-fluid spills may be associated with exploration, production, or transportation 

activities that result from the CPA proposed action. Low-income and minority populations might be 

more sensitive to oil spills in coastal waters than is the general population because of their dietary reliance 

on wild coastal resources, their reliance on these resources for other subsistence purposes such as sharing 

and bartering, their limited flexibility in substituting wild resources with purchased ones, and their 

likelihood of participating in cleanup efforts and other mitigating activities. With the exception of a 

catastrophic accidental event, such as the DWH event, the impacts of oil spills, vessel collisions, and 

chemical/drilling fluid spills are not likely to be of sufficient duration to have adverse and 

disproportionate long-term effects for low-income and minority communities in the analysis area. 

An event like the DWH event could have adverse and disproportionate effects for low-income and 

minority communities in the analysis area. Many of the long-term impacts of the DWH event to lowincome and minority communities are unknown. While economic impacts have been partially mitigated 

by employers retaining employees for delayed maintenance or through the GCCF Program’s emergency 

funds, the physical and mental health effects to both children and adults within these communities could 

potentially unfold for many years. As studies of past oil spills have highlighted, different cultural groups 

can possess varying capacities to cope with these types of events (Palinkas et al., 1992). Likewise, some 

low-income and/or minority groups may be more reliant on natural resources and/or less equipped to 

substitute contaminated or inaccessible natural resources with private market offerings. Because lowerincome and/or minority communities may live near and directly involved with spill cleanup efforts, the 

vectors of exposure can be higher for them than for the general population, increasing the potential risks 

of long-term health affects. To date, there have been no studies of possible long-term health effects for 

oil-spill cleanup workers. The post-DWH event human environment remains dynamic, and BOEMRE 

will continue to monitor these populations over time and to document short- and long-term DWH event 

impacts. In the future, the long-term impacts of the DWH event will be clearer as time allows the 

production of peer-reviewed research and targeted studies that determine those impacts. 

The DWH event was a low-probability, high-impact catastrophic event. For the reasons set forth in 

the analysis above, the kinds of accidental events (smaller, shorter time scale) that are likely to result from 

the CPA proposed action may affect low-income and/or minority more than the general population, at 

least in the shorter term. These higher risk groups may lack the financial or social resources and may be 

more sensitive and less equipped to cope with the disruption these events pose. These smaller events, 

however, are not likely to significantly affect minority and low-income communities in the long term. 

4.1.1.21.4.4. Cumulative Impacts 

An impact analysis for cumulative impacts in the CPA and WPA on environmental justice can be 

found in Chapter 4.5.15.4 of the Multisale EIS. Impact analyses for the CPA and WPA that includes any 

new information since publication of the Multisale EIS is presented in Chapter 4.1.16.4.4 of the 2009-

2012 Supplemental EIS. The following information is a summary of the impact analysis incorporated 

from the Multisale EIS and the 2009-2012 Supplemental EIS, and new information that has become 

available since both documents were prepared. 

Background/Introduction 

Of all activities in the cumulative scenario, those that could potentially impact environmental justice 

in the CPA include (1) proposed actions and the OCS Program, (2) State oil and gas activity, (3) existing 

infrastructure associated with petrochemical processing including refineries and polyvinyl plants, (4) 

existing waste facilities including landfill, (5) coastal erosion/subsidence, (6) hurricanes, (7) global 

climate change, and (8) the lingering impacts of the DWH event. The context in which people may find 

themselves, and how that context affects their ability to respond to an additional change in the 

socioeconomic or physical environment, is the heart of an environmental justice analysis. The OCS 

Program in the GOM is large and has been ongoing for more than 50 years with established infrastructure, 

resources, and labor pools to accommodate it. That said, low-income and/or minority groups lacking 

financial, social, or environmental resources or practical alternatives may be more sensitive to, or are less 

equipped than are other groups to cope with an consequences of an oil spill, such as interruptions to 
4-350 Central Planning Area Supplemental EIS 

municipal services or fisheries closures. In studies on social disaster resiliency, variables such as income 

inequality can negatively impact a community’s ability to respond and recover from a disaster (Norris et 

al., 2008). Groups may be even less so equipped to respond to these types of events if, for example, they 

are already in the process of recovering from a hurricane. On the other hand, Cutter et al. (2008) found 

that previous disaster experience, defined as the number of paid disaster declarations, positively affected 

disaster resilience. This cumulative impact analysis examines how incremental additions to an 

established program from the CPA proposed action area potentially may interact with other ongoing 

impacts along the Gulf Coast. As explained in prior sections, the interlinked nature of the OCS industry 

requires a discussion of potential impacts both in the CPA and the WPA. 

OCS Program 

The CPA proposed action and the OCS Program have the potential to adversely impact low-income, 

minority, and other environmental justice communities either directly or indirectly from onshore activities 

conducted in support of OCS exploration, development, and production (for a fuller discussion on 

potential impacts from routine events and accidental events, see Chapters 4.1.1.21.4.2 and 4.1.1.21.4.3, 

respectively). Potential vectors for impacts include increases in onshore activity (such as employment, 

migration, commuter traffic, and truck traffic), additions to the infrastructure supporting this activity 

(such as fabrication yards, supply ports, and onshore disposal sites for offshore waste), and additional 

accidental events such as oil or chemical spills. The BOEMRE estimates that production from the CPA 

proposed action would be 0.801-1.624 BBO and 3.332-6.560 Tcf of gas and that production in both the 

CPA and WPA proposed actions would range from 28.562 to 32.57 BBO and 142.366-162.722 Tcf of gas 

during 2007-2046 (Table 3-1). Chapter 3.3.1 describes the widespread and extensive OCS-support 

system and associated labor force, as well as economic factors related to OCS activities. The widespread 

nature of the OCS-related infrastructure serves to limit the magnitude of effects that a single proposed 

action or the overall OCS Program may have on a particular community. Future lease sales would serve 

mostly to maintain the ongoing activity levels associated with the current OCS Program. 

For most of the Gulf Coast, the OCS Program will result in only minor economic changes. Generally, 

effects will be widely yet thinly distributed across the Gulf Coast and will consist of slight increases in 

employment and few, if any, increases in population. Some places could experience elevated 

employment, population, infrastructure, and/or traffic effects because of local concentrations of 

fabrication and supply operations. Because of Louisiana’s extensive oil-related support system, that State 

is likely to experience more employment effects related to the CPA proposed action than are the other 

coastal states. Because Lafourche Parish, Louisiana, already services about 90 percent of all deepwater 

and 45 percent of all shallow-water oil and gas production in the Gulf, it is likely to continue experiencing 

benefits from the OCS Program (Loren C. Scott & Associates, 2008). While the addition of the C-Port in 

Galveston, Texas, is expected to increase Texas’s share of future effects, Louisiana is likely to continue to 

experience more than do other Gulf Coast States. Except in Louisiana, the OCS Program is expected to 

provide little additional employment, although it will serve to maintain current activity levels, which is 

expected to be beneficial to Gulf region low-income and minority populations generally. The Multisale 

EIS states the following: “Evidence also suggests that a healthy offshore petroleum industry also 

indirectly benefits low-income and minority populations.” One Agency study found income inequality in 

Louisiana decreased during the oil boom and increased with the decline (Tolbert, 1995). 

Environmental justice often concerns infrastructure siting, which may have disproportionate and 

negative effects on minority and low-income populations. Since OCS lease sales help maintain ongoing 

levels of activity rather than expand them, no one sale generates significant new infrastructure demand. 

Pipeline shore facilities are small structures, such as oil metering stations, associated with pipeline 

landfalls. At present, there are 126 OCS-related pipeline landfalls and 50 OCS-related pipeline shore 

facilities in the GOM region (Table 3-38 of the Multisale EIS). Cumulatively, over the next 40 years, the 

OCS Program is expected to result in 32-47 new pipeline landfalls, and 4-6 pipeline shore facilities are 

projected (Table 4-9 of the Multisale EIS). From 25 to 36 landfalls are projected for Louisiana, 6-8 are 

projected for Texas, 1-3 are projected for Mississippi and Alabama, and 0 are projected for Florida. From 

3 to 5 pipeline shore facilities are projected for Louisiana, 1-2 for Texas, 0-1 for Mississippi and 

Alabama, and 0 for Florida. Each OCS-related facility that may be constructed onshore must receive 

approval by the relevant Federal, State, and local agencies. Each onshore pipeline must obtain similar 
Description of the Environment and Impact Analysis 4-351 

permit approval and concurrence. The BOEMRE assumes that all such approvals would be consistent 

with appropriate land-use plans, zoning regulations, and other Federal/State/regional/local regulatory 

mechanisms. Should a conflict occur, BOEMRE assumes that approval would not be granted or that 

appropriate mitigating measures would be enforced by the responsible political entities. 

As stated in Chapter 4.1.1.21.4.1 the region as a whole is not homogenous, but there are several 

potentially vulnerable ethnic and socioeconomic groups, some residing in enclaves, dispersed throughout 

OCS Gulf of Mexico economic impact areas. It shows that the 10 counties/parishes with high 

concentrations of oil-related infrastructure (Table 3-40 of the Multisale EIS) are not generally those with 

high concentrations of minority and low-income populations and that, in these counties/parishes, many of 

the low-income and minority populations reside in large urban areas where the complexity and dynamism 

of the economy and labor force preclude measurable sale-level or programmatic-level OCS effects. 

Two local infrastructure issues analyzed in Chapter 4.1.1.21.4.1 could possibly have related 

environmental justice concerns: traffic on LA Hwy 1 and the Port Fourchon expansion. This analysis 

concludes that the minority and low-income populations of Lafourche Parish will share the negative 

impacts of the OCS Program with the rest of the population. However, most effects are expected to be 

economic and positive. It is likely that a proposed 27.5 mi (44.3 km) of improvements to the Port 

Fourchon highway system will be funded in the next few years, alleviating many of the associated issues 

with the highway. 

While there is a link between a healthy oil industry and indirect economic benefits to all sectors of 

society, this link may be weak in some communities and strong in others, such as Lafourche Parish, 

Louisiana (Hughes et al., 2001). Even in these areas, the petroleum industry has not been a critical factor 

in social change, except for limited periods of time (Wallace et al., 2001). This is the conclusion of this 

Agency’s 5-Year Programmatic EIS (USDOI, MMS, 2001b), which analyzed the contribution of the OCS 

Program in the GOM (i.e., its cumulative effects) to the cumulative factors affecting environmental 

justice. Impacts, including how communities respond to fluctuations in industry activity, vary from one 

coastal community to the next. Expansion or contraction of offshore or onshore oil and gas activity has 

produced moderate impacts in some communities, whereas other communities have dealt with episodes of 

rapid industry change with negligible to minor impact. Furthermore, non-OCS activities, such as 

expansions of the tourism industry or the highway system, often can generate socioeconomic impacts by 

being a catalyst for such things as in-migration, demographic shifts, population change, job creation and 

cessation, community development strategies, and overall changes in social institutions (i.e., family, 

government, politics, education, and religion). Reflecting this Agency’s earlier 5-Year Programmatic EIS 

analysis, this analysis concludes that the contribution of the CPA proposed action to the OCS Program’s 

cumulative environmental justice impacts would be negligible. The analysis also concludes that, overall, 

OCS programmatic impacts to environmental justice over the next 40 years would likely represent a very 

small proportion of the cumulative impacts of all activities that affect environmental justice. 

State Oil and Gas 

State oil and gas activity has the potential to adversely impact low-income, minority, and other 

environmental justice communities either directly or indirectly from onshore activities conducted in 

support of State oil and gas exploration, development, and production. Louisiana, Mississippi, and 

Alabama jurisdiction over mineral resources extends 3 nmi from the shore; Texas and Florida jurisdiction 

over the seabed extends out 9 nmi. The annual gas production from Alabama State waters has ranged 

from 150 to 200 Bcf or approximately 50 percent of the State’s total gas production (State of Alabama, 

n.d.). While offshore leasing in shallow waters is in general decline, states like Louisiana are attempting 

to incentivize increased activity closer to the shore. In 2006, the Louisiana Legislature authorized the 

Louisiana Dept. of Environmental Quality to implement an Expedited Permit Processing Program, which 

has so far resulted in a 55 percent reduction in coastal permitting time (Louisiana Dept. of Natural 

Resources, 2009). In November 2010, Louisiana voters passed the Louisiana Natural Resource Severance 

Tax Amendment, which effectively decreases the amount of taxes retained by the State on the severance 

of natural resources, but it increases what can be collected by the parishes where resources are extracted 

(State of Louisiana, 2010). Whether this measure will increase individual parishes’ incentive to 

encourage production closer to the coast is still unknown. 
4-352 Central Planning Area Supplemental EIS 

State offshore oil and gas programs pose the same potential issues as does the OCS Program, 

although since State leases are closer to land, their petroleum-related activities are generally viewed as 

having greater potential for directly impacting coastal communities. The BOEMRE assumes that sitings 

of any future facilities associated with State programs would be based on the same economic, logistical, 

zoning, and permitting considerations that determined past sitings. Revenues from State water oil 

programs have produced several positive impacts and the steady stream of oil exploration and 

development have produced positive cumulative impacts that include increased funding for infrastructure, 

higher incomes (that can be used to purchase better equipment for subsistence), better health care, and 

improved educational facilities. While industrialization generally leads to a shift in community 

organization and cultural development, the offshore oil and gas industry and its concentrated work 

schedule has been more accommodating of “traditional” activities, such as trapping and fishing, during 

their time at home (Luton and Cluck, 2003). 

Downstream Activities 

Existing infrastructure associated with petrochemical processing including refineries and the 

production of petroleum-based goods such as polyvinyl plants poses potential health and other related 

risks to minority and low-income communities. The BOEMRE projects that, cumulatively, 14 new gas 

processing plants would be needed in support of the OCS Program over the next 40 years. The marginal 

contribution of the CPA proposed action does not change the estimate. The geographic distribution of 

projected gas processing plants differs markedly from the current distribution. Three new gas processing 

plants are projected for Louisiana, which currently has 28; 2 are projected for Texas, which currently 

has 1; and 9 are projected for Mississippi and Alabama, which currently have 6. As described in Chapter 

3.3.5.8, this distribution is based on economic and logistical considerations unrelated to the distribution of 

concentrations of minority or low-income populations. The BOEMRE cannot predict and does not 

regulate the siting of future gas processing plants. The BOEMRE assumes that sitings of any future 

facilities would be based on the same economic, logistical, zoning, and permitting considerations that 

determined past sitings and that they would not disproportionately affect minority and low-income 

populations. An environmental justice study of industrial siting patterns in Jefferson, St. Bernard, and 

Lafourche Parishes, Louisiana, found that “people appear to be moving into densely populated, largely 

industrial areas where the costs of rent are lower. In addition, people tend to be moving into newer 

housing” (Hemmerling and Colten, in preparation). This historical analysis revealed little evidence of 

systematic environmental injustice of various oil-related industries, with the demographic makeup of the 

communities changing after facilities arrived. Communities with a higher than average number of 

chemical plants should be monitored to ensure that industry dominating the landscape does not 

disproportionately burden low-income or minority communities. 

Waste 

Existing waste facilities, including landfills and oil waste pits, can pose potential environmental 

justice impacts to low-income and minority communities. The development of any new oilfield would 

result in an increase in hazardous materials transported onshore. Tables 4-39 and 4-40 identify the DWH 

waste disposal sites that received the greatest percentages of waste and the waste types received. Figure 

4-19 shows the location of all sites that received DWH waste. Argonne National Laboratory reported that 

there are 46 waste management facilities that service the oil and gas industry along the GOM, with 18 in 

Louisiana, 18 in Texas, 5 in Mississippi, 4 in Alabama, and 1 in Florida (Puder and Veil, 2006). Because 

of existing capacity, no new waste disposal sites are projected for the cumulative case (The Louis Berger 

Group, Inc., 2004). 

Coastal Erosion and Subsidence 

Coastal erosion and subsidence in some parts of the southeastern coastal plain serves to amplify the 

vulnerability of communities, infrastructure, and natural resources to storm-surge flooding (Dalton and 

Jones, 2010). Submergence in the Gulf is occurring most rapidly along the Louisiana coast and more 

slowly in other coastal states. Depending on local geologic conditions, the subsidence rate varies across 

coastal Louisiana from 3 to over 10 mm/yr (0.12 to over 0.39 in/yr). Natural drainage patterns along 
Description of the Environment and Impact Analysis 4-353 

many Texas coast areas have been severely altered by construction of the Gulf Intracoastal Waterway and 

other channelization projects associated with its development. Saltwater intrusion resulting from river 

channelization and canal dredging is a major cause of coastal habitat deterioration (Tiner, 1984; National 

Wetlands Inventory Group, 1985; Cox et al., 1997); see Chapter 4.1.1.4 for a discussion of wetlands in 

the CPA. As discussed in Chapter 4.1.1.21.4, tropical storms are the norm in the region, but low-income 

and minority communities may bear a larger burden than the general populations. Native Americans, 

Vietnamese, Cajun, African American, and other ethnic enclaves have all borne catastrophic losses in 

recent storm events. An estimated 4,500 Native Americans living on the southeast Louisiana coast lost 

their possessions to Hurricane Katrina according to State official and tribal leaders. Cajuns were also 

impacted by Hurricane Katrina, and especially by Hurricane Rita, whose 20-ft (6-m) storm surges flooded 

low-lying communities in Cameron, Calcasieu, and other coastal parishes. According to a USGS 5-year, 

post-Katrina survey, wetland loss from all four storms (Hurricanes Katrina, Rita, Gustav, and Ike) totaled 

340 mi2

 (881 km2). 

Recent climate change projections suggest global sea level will rise by 0.8-2.0 m (2.6-6.6 ft) by 2100 

due to climate change (Bryan et al., 2001; Kont et al., 2003; Overpeck et al., 2006; Pfeffer et al., 2008). 

Such a rise in sea level would cause unprotected shorelines to migrate inland and future hurricane stormsurge inundation to extend farther inland than contemporary hazard zones predict (Frazier et al., 2010). 

Chapter 4.1.1.4 explains that disappearing dune and barrier island elevations and associated marshes 

make inland coasts more vulnerable to future hurricanes and wind-driven tidal or storm events. Several 

studies highlight the potentially disastrous effects of future hurricane storm-surge enhanced by sea-level 

rise on coastal communities (Cohen et al., 1997; Gommes et al., 1998; Field et al., 2001; Wu et al., 2002; 

Kleinosky et al., 2007). Even if hurricanes do not increase in frequency or intensity in the future, 

continued sea-level rise puts low-lying coastlines at much greater storm-surge risk (Frazier et al., 2010). 

Such sea-level rise increases the amount of people impacted by storm events and could also displace 

communities in areas below or near sea level. 

Coastal subsidence and erosion can increase community vulnerability to future hazards and also 

threaten traditional ways of life. Saltwater intrusion reduces productivity and species diversity associated 

with Louisiana and Texas wetlands and coastal marshes (Stutzenbaker and Weller, 1989; Cox et al., 

1997). While users of coastal waters may trend towards the relatively affluent, low-income and minority 

groups may be more dependent on the resources of the Gulf Coast. Several ethnic minority and lowincome groups rely substantially on these resources for food, shelter, clothing, medicine, or other 

minimum necessities of life (e.g., see Hemmerling and Colten, 2003, for an evaluation of environmental 

justice considerations for south Lafourche Parish). 

Coastal Storms 

Hurricanes, tropical storms, and other wind-driven tidal or storm events are a fact of life for 

communities living along the Gulf of Mexico coastal zone. For low-income and minority populations, 

however, the impacts of coastal storm events can be particularly profound because of factors like limited 

resources to evacuate or to mitigate hazards. Baseline conditions pertaining to environmental justice were 

reevaluated in light of recent hurricane activity in the GOM. The intensity and frequency of hurricanes in 

the Gulf over the last 6 years has greatly impacted the system of protective barrier islands, beaches, and 

dunes and associated wetlands along the Gulf Coast. Within the last 6 years, the Gulf Coast of Texas, 

Louisiana, Mississippi, Alabama, and to some degree Florida have experienced five major hurricanes 

(Ivan, Katrina, Rita, Gustav, and Ike). Impacts from future hurricanes and tropical storm events are 

uncertain. Municipal programs like the New Orleans Office of Homeland Security and Public Safety’s 

City Assisted Evacuation Plan are being implemented to help citizens who want to evacuate during an 

emergency but lack the capability to self-evacuate (City of New Orleans, n.d.). Hazard mitigation funds 

available through individual states and FEMA also seek to mitigate potential damage to homes in flood 

zones throughout the Gulf. While hurricanes and tropical storms are inevitable, lessons learned from 

Hurricanes Katrina and Rita are shaping local and national policies as well as efforts by nongovernmental organizations to protect low-income, minority, and other vulnerable communities. 
4-354 Central Planning Area Supplemental EIS 

Global Climate Change 

While predictions remain uncertain, global climate change has the potential to adversely impact lowincome and minority communities living within the Gulf of Mexico economic impact zones. Although 

research on the frequency and intensity of future hurricanes is still under debate (Shepherd and Knutson, 

2007), consensus is emerging that climate change may result in fewer tropical cyclones but with 

increasing intensities and precipitation totals (Bengtsson et al., 2007; Edwards, 2008; Landsea et al., 

2006). A regional model of the tropical North Atlantic used by the latest report from the 

Intergovernmental Panel on Climate Change found decreasing storm activity over the North Atlantic. A 

new technique for deriving hurricane climatologies from global data, applied to climate models, indicates 

that global climate change should reduce the global frequency of hurricanes, although their intensity may 

increase in some locations (Intergovernmental Panel on Climate Change, 2007b). Hurricane intensity has 

been demonstrated to be highly correlated to thermodynamic potential (warmer waters); therefore, it is 

believed that an increase in sea temperatures should lead to an amplification of storm intensity and 

increased rainfall totals (Emanuel, 2000 and 2005; Knutson and Tuleya, 2004; Pielke et al., 2005; 

Webster et al., 2005). Coupled with potential sea-level rise, global climate change exposes a greater 

number of the residential population and assets (i.e., infrastructure and natural resources) to the impacts of 

storms. 

Deepwater Horizon Event 

While it is still too soon to determine the long-term social impacts of the DWH event, anecdotal 

evidence from media coverage and early survey studies suggest the possibility of trends that might 

disproportionately affect low-income and minority communities for some time to come. A phone survey 

conducted by a team of LSU sociologists found that nearly 60 percent of the 925 coastal Louisiana 

residents interviewed reported being almost constantly worried by the DWH event (Lee and Blanchard, 

2010). Studies of residents near past oil spills (such as the Exxon Valdez in Prince William Sound, 

Alaska) have noted impacts to social cohesion and increased distrust in government and other institutions, 

which contributed to community anxiety (Tuler et al., 2009). 

Cumulative effects on social organization could include decreasing importance of family, 

cooperation, sharing, and subsistence availability. Long-term effects on wild resource harvest patterns 

might also be expected. While acute health effects from oil-spill events have been somewhat studied, the 

long-term impacts form exposure is unknown (Aguilera et al., 2010; Meo, 2009; Morita et al., 1999; 

Sathiakumar, 2010). Studies of possible long-term health effects from exposure to either the DWH 

event’s oil or dispersants, such as the possible bioaccumulation of toxins in tissues and organs, are 

lacking, and the potential for the long-term human health effects are largely unknown (although the 

National Institutes of Health has proposed such a study). In prior post-spill cleanup efforts, the duration 

of cleaning work was a risk factor for acute toxic symptoms, and seamen had the highest occurrence of 

toxic symptoms compared with volunteers or paid workers (Sathiakumar, 2010). Therefore, participants 

in the DWH “Vessels of Opportunity” program, which recruited local boat owners (including Cajun, 

Houma Indian, and Vietnamese fishermen) to assist in cleanup efforts, would likely be one of the most 

exposed groups. African Americans are thought to have made up a high percentage of the cleanup 

workforce. In Gulf coastal areas, low-income and minority groups are heavy subsistence users of local 

seafood. The concern is that heavy subsistence users face higher than expected, and potentially harmful, 

exposure rates to PAH’s from the DWH event. As mentioned earlier, the National Institutes of Health’s 

proposed study should provide a better understanding of the long-term and cumulative health impacts, 

such as the consequences of working close to a spill and of consuming contaminated seafood. Several 

ongoing studies also seek to understand the short- and long-term impacts of the recent DWH event (e.g., 

the study “Ethnic Groups and Enclaves Affected by OCS,” which was launched August 1, 2010). The 

BOEMRE will continue to seek additional information. 

Summary and Conclusion 

The cumulative impacts of the CPA proposed action would occur within the context of other impactproducing factors on environmental justice, including (1) proposed actions and the OCS Program, (2) 

State oil and gas activity, (3) existing infrastructure associated with petrochemical processing including 
Description of the Environment and Impact Analysis 4-355 

refineries and polyvinyl plants, (4) existing waste facilities including landfill, (5) coastal 

erosion/subsidence, (6) hurricanes, (7) global climate change, and (8) the lingering impacts of the DWH 

event. 

Because of the presence of an extensive and widespread support system for the OCS and associated 

labor force, the effects of the cumulative case are expected to be widely distributed and, except in 

Louisiana, little felt. In general, the cumulative effects of the OCS Program are expected to be economic 

and to have a limited but positive effect on low-income and minority populations. In Louisiana, these 

positive economic effects are expected to be greater. In general, who would be hired and where new 

infrastructure might be located is impossible to predict, although a new C-Port in Galveston, Texas, is 

likely to increase Texas’ share of effects. Given the existing distribution of the OCS-related industry and 

the limited concentrations of minority and low-income peoples, the cumulative OCS Program would not 

have a disproportionate effect on these populations. Lafourche Parish would experience the most 

concentrated effects of cumulative impacts. Because the parish is not heavily low-income or minority and 

because the effects of road traffic and port expansion would not occur in areas of low-income or minority 

concentration, these groups are not expected to be differentially affected. 

To summarize, the CPA proposed action is not expected to have disproportionate high/adverse 

environmental or health effects on minority or low-income people, and in the GOM coastal area, the 

contribution of the proposed action and the OCS Program to the cumulative effects of all activities and 

trends affecting environmental justice issues over the next 40 years is expected to be negligible to minor. 

The cumulative effects would be concentrated in coastal areas, and particularly Louisiana. Most OCS 

Program effects are expected to be in the areas of job creation and the stimulation of the economy, and 

they are expected to make a positive contribution to economic justice. The contribution of the cumulative 

OCS Program to the cumulative impacts of all factors affecting environmental justice is expected to be 

minor (USDOI, MMS, 2001c); therefore, the incremental contribution of the CPA proposed action to the 

cumulative impacts would also be minor. State offshore leasing programs in Alabama and Louisiana 

have similar, although more limited effects, due to their smaller scale. Cumulative effects from onshore 

infrastructure, including waste facilities, is also expected to be minor because existing infrastructure is 

regulated, because little new infrastructure is expected to result in the cumulative case, and because any 

new infrastructure would be subject to relevant permitting requirements. Coastal landloss/subsidence, 

hurricanes, and global warming all raise environmental justice issues, as do the lingering effects of the 

DWH event. The cumulative consequences to environmental justice cannot be determined at this time. 

Nevertheless, a single OCS lease sale, State leasing programs, and onshore infrastructure would make 

only minor contributions to these cumulative effects. 

4.1.1.22. Additional Resources Considered due to the Deepwater Horizon Event 

The following resources, i.e., soft bottoms and diamondback terrapins, have not been included in 

previous EIS’s due to the negligible impacts to these resources from routine impact-producing factors 

associated with OCS-related activities. The BOEMRE has included these resources in this Supplemental 

EIS primarily to address concerns about the potential impacts of the DWH event and resulting oil spill to 

these resources. 

4.1.1.22.1. Soft Bottoms 

4.1.1.22.1.1. Description of the Affected Environment 

The seafloor on the continental shelf in the Gulf of Mexico consists primarily of muddy to sandy 

sediments. The eastern shelf is primarily sand extending out to 100-m (328-ft) water depth, while the 

central and western shelf is a mixture of sand, silt, and clay (Brooks and Darnell, 1991). Sediments near 

the shoreline of the Alabama coast consist of fine-grained, well-sorted sand and transition to clay and 

marl (Ellwood et al., 2006; Balsam and Beeson, 2003). Sediments offshore of Mississippi and Louisiana 

are primarily silt and clay of terrigenous origin (Ellwood et al., 2006; Balsam and Beeson, 2003). 

Benthic fauna include infauna (animals that live in the substrate, including mostly burrowing worms, 

crustaceans, and mollusks) and epifauna (animals that live on or are attached to the substrate; mostly 

crustaceans, as well as echinoderms, mollusks, hydroids, sponges, soft and hard corals, and demersal 

fishes). Infauna is comprised of meiofauna, small organisms (63-500 μ) that live among the grains of 
4-356 Central Planning Area Supplemental EIS 

sediment; and macroinfauna, slightly larger organisms (>0.5 mm; 0.02 in) that live in the sediment 

(Dames & Moore, Inc., 1979). Shrimp and demersal fish are closely associated with the benthic 

community. The most abundant organisms on the continental shelf are the deposit-feeding polychaetes. 

The slope and deep sea consist of vast areas of primarily fine sediments that support benthic communities 

with lower densities and biomass but higher diversity than the continental shelf (Rowe and Kennicutt, 

2001). The following information is an entirely new section since the writing of the Multisale EIS and 

the 2009-2012 Supplemental EIS and will be described in full. 

Environmental Influences on Benthic Community Structure 

Substrate is the single most important factor in the distribution of benthic fauna (densities of infaunal 

organisms increase with sediment particle size), although temperature and salinity are also important in 

determining the extent of faunal distribution (Vittor, 2000; Byrnes et al., 1999; Harper, 1991; Dames & 

Moore, Inc., 1979; Parker et al., 1975; Barry A. Vittor & Associates Inc., 1985; Defenbaugh, 1976). 

Depth and distance from shore also influence the benthic faunal distribution (Harper, 1991; Dames & 

Moore, Inc., 1979; Defenbaugh, 1976; Parker et al., 1975). Lesser important factors include illumination, 

food availability, currents, tides, and wave shock. Experiments indicate that fluctuating physical factors 

have a greater influence in estuaries than farther offshore, where sediment type is the primary influencing 

factor (Flemer et al., 2002). 

Substrate type, as the most important control upon benthic infaunal assemblages, has been 

emphasized by previous sampling efforts over broad areas of the northern Gulf of Mexico shelf. Studies 

of the infauna of the Mississippi, Alabama, and Florida (MAFLA) OCS by Dames & Moore, Inc. (1979) 

revealed that inner shelf benthic habitats of the northeastern Gulf of Mexico can be described primarily on 

the basis of sediment texture and water depth. Barry A. Vittor & Associates, Inc. (1985) and Vittor 

(2000) categorized the OCS of the northern Gulf of Mexico based on sediment types and species 

associated with those habitats. 

Infaunal assemblages are comprised of species adapted to particular sedimentary habitats through 

differences in behavioral, morphological, physiological, and reproductive characteristics. Feeding is one 

of the behavioral aspects most closely related to sedimentary habitat (Rhoads, 1974). In general, habitats 

with coarse sediment and high water current velocities, where organic particles are maintained in 

suspension in the water column, favor the occurrence of suspension-feeding taxa that strain food particles 

from the water column. Coarse sediments also facilitate the feeding of carnivorous taxa that consume 

organisms occupying interstitial habitats (Fauchald and Jumars, 1979). At the other extreme, habitats 

with fine-textured sediments and little or no current are characterized by the deposition and accumulation 

of organic material, thereby favoring the occurrence of surface and subsurface deposit-feeding taxa. In 

between these habitat extremes are a variety of habitat types that differ with respect to various 

combinations of sedimentary regime, depth, and hydrological factors, with each habitat type facilitating 

the existence of particular infaunal assemblages (Barry A. Vittor & Associates, Inc., 1985). An east-towest transition of sedimentary regimes, from predominantly sands along the west Florida shelf to silts and 

clays along the Louisiana shelf, was evident during previous regional studies. Infaunal assemblages 

varied along this east-west gradient as well (Barry A. Vittor & Associates, Inc., 1985). 

Descriptions of Continental Shelf Soft-Bottom Benthic Communities 

Vittor (2000) described the general community composition of the infaunal habitats on the OCS of 

the northern Gulf of Mexico. He described the communities primarily based on sediment type and 

distance from shore and grouped the inhabitants by feeding mode. 

 Assemblage I consisted of sandy sediments (<5% silt/clay or gravel) spread along the 

entire continental shelf. Dominant filter feeders on the shelf were mollusks (Astarte 

nana, Chione intapurpurea, Ervilia concentrica, Tellina aequistriata). Deposit 

feeders included mollusks (Caecum cooperi, Caecum imbricatum, Cadulus tetrodon) 

and ostracods (Rutiderma darbyi). Carnivores included polychaetes (Nephtys picta, 

Sigambra tentaculata, Synelims albini) and mollusks (Nassarius albus, Tectonatica 

pusilla). 
Description of the Environment and Impact Analysis 4-357 

 Assemblage II consisted of silty sand and sandy silt on the inner shelf in less than 

100 m (328 m) of water. These areas generally have greater than 5 percent or 

10 percent silt and are affected by sediment transport from estuaries. Burrowing and 

surface deposit-feeding polychaete detritivores such as Armandia maculata, Dispio 

uncinata, Magelona petiboneae, Paraprionospio pinnata, and Spiophanes bombyx

inhabit this habitat. Filter-feeding crustaceans (Ampelisca agassizi, Branchiostoma

sp.) and polychaetes (Diopatra cuprea, Owenia fusiformis) are also abundant. 

 Assemblage III is comprised of patchy coarse sand or gravel. Deposit feeders in this 

group include mollusks (Caecum cooperi), amphipods (Metharpinia floridana), 

tanaids (Apseudes sp.), and polychaetes (Aonides paucibranchiata, Chone duneri, 

and Filograna implexa). Chloeia viridis, Eunice vittata, Nephtys picta, and 

Bhawania heteroseta are resident carnivores. 

 Assemblage IV is comprised of fine and silty sand habitats in >100 m (328 m) of 

water. The most abundant organisms are the burrowing and surface deposit feeders 

including polychaetes (Ampharete acutifrons, Aricidea neosuecica, Armandia 

maculata, Laonice cirrata, Poecilochaetus johnsoni) and mollusks (Nuculana acuta, 

Yoldia liorhina). Polychaete carnivores/omnivores also include Goniada maculata, 

Paralacydonia paradoxa, and Synelmis albini. 

Vittor (2000) based his community assemblages on his previous (Barry A. Vittor & Associates, Inc., 

1985) descriptions of the continental shelf habitats between Florida and Louisiana. Barry A. Vittor & 

Associates, Inc. (1985) recognized four depth-related benthic habitats for infaunal communities in the 

region of the northeastern Gulf of Mexico: shallow beach habitat; inner shelf habitat; intermediate shelf 

habitat; and outer shelf habitat. Each of these habitats was further divided into sediment type (mud, sandy 

mud, muddy sand, or sand). Infaunal assemblage associations were recognized with each combination of 

water depth and substratum type. Cluster analysis revealed that infaunal taxa were closely tied to 

sediment type and texture. 

The benthic habitat descriptions were a result of compiled habitat data collected from several studies 

conducted in the Tuscaloosa Trend regional area from the Florida to Louisiana shelves. Barry A. Vittor 

& Associates (1985) noted that the sediment is sandier on the Florida shelf and transitions to terrigenous 

silts and clays on the southeast Louisiana shelf. Sediment also becomes finer in the offshore direction. 

The following material describes the macroinfauna and macroepifauna communities to the east of the 

Mississippi River. 

 Shallow Beach Habitat is located in 2-4 m (7-13 ft) of water and consists of well 

sorted sand and shell fragments. Temperature and salinity fluctuate and wave action 

is heavy. Dominant species include bivalves (Donax spp.), echinoderms (Mellita 

quinquiesperforata), and amphipods (Protohaustorius spp.). 

 Inner Shelf Habitat is located in 4-20 m (13-66 ft) of water and is adjacent to barrier 

islands. Species in this area tolerate lower salinities resulting from Mississippi River 

freshwater input. Infaunal species that dominate in muddy (<20% sand) portions of 

this area include a hemichordate (Balanoglossus aurantiacus), a polychaete 

(Paramphinome sp.), and mollusks (Utriculastra canaliculata, Nassarius acutus). 

Epifaunal inhabitants include a sea pansy (Renilla mulleri), mollusks (Nassarius 

acutus, Nuculana concentricia), shrimp (Farfantepenaeus aztecus, Litopenaeus 

setiferus, Rimapenaeus similis), and crabs (Portunus spp., Callinectes similis). 

Echinoderms (Hemipholis elongate, Micropholis atra), mollusks (Nuculana 

concentrica), and crustacea (Pinnixia pearsei) are found in sandy mud habitats (20-

50% sand). Infaunal species found in sandy (>90% sand) habitats include 

polychaetes indicative of offshore environments (Nephtys picta, Dispio uncinata, 

Onuphis nebulosa, Magelona riojai, Aricidea wassi, Apoprionospio pygmaea, Brania 

wellfleetensis), amphipods (Acanthohaustorius sp., Protohaustorius sp., Lepidactylus

sp.), the cephalochordate (Branchiostoma carribeum), and the archiannelid 
4-358 Central Planning Area Supplemental EIS 

(Polygordius sp.), which are common in tidal inlets. Epifaunal species in this habitat 

include a sea pansy (Renilla mulleri), baby’s ear gastropod (Sinum prospectivum), 

bivalves (Noetia ponderosa, Chione clenchi), brown shrimp (Farfantepenaeus 

aztecus), purse crabs (Persephone spp.), shame-faced crabs (Calappa sulcata, 

Hepatus epheliticus), and echinoderms (Hemipholis elongate, Mellita 

quinquiesperforata). Transitional polychaete species that thrive in both 

environments include Magelona phyllisae, Paraprionospio pinnata, Mediomastus 

californiensis, Sigambra tentaculata, and Spiophanes bombyx. 

 Intermediate Shelf Habitat is located in 20-60 m (66-197 ft) of water and is 

comprised of both sand and mud environments. Muddy sediments are dominated by 

polychaetes (Cirrophorus lyriformis, Nephtys incise, and Notomastus daueri). 

Organisms in the sandy areas include polychaetes (Aricidea wassi), amphipods 

(Metharpinia floridana and Ampelisca agassizi), and tanaids (Kalliapseudes sp.). 

Polychaetes found in both sandy and muddy environments include Cossura soyeri, 

Nereis micromma, Sigambra tentaculata, and Aglaophamus verrilli. Epifaunal 

species found on the Intermediate Shelf Habitat include gastropods (Strombus sp., 

Murex sp., Busycon sp., Fasciolaria sp.), bivalves (Argopecten sp., Tellina sp., Pitar

sp.), shrimps (Penaeus sp., Sicyonia sp.), crabs (Calappa sp., Portunnus sp., 

Anasimus sp., Libinia sp., Parthenope sp.), echnioids (Encope sp., Stylocidaris sp.), 

and starfish (Luidia sp., Astropecten sp.). 

 Outer Shelf Habitat is comprised of mud (<20% sand) with the infauna characterized 

by polychaetes (Notomastus latriceus, Nereis grayi, Cirrophorus lyriformis, Nephtys 

incisa, Paraprionospio pinnata, Mediomastus califirniensis). A variety of epifauna 

are found in this zone including gastropods (Turritella exoleta, Polystira albida), 

bivalves (Anadara spp., Verticordia ornate), crabs (Munida sp., Raninoides sp., 

Myropsis sp.), echinoids (Echinocardium sp., Brissopsis sp.), and starfish 

(Astropecten sp., Cheiraster sp.). 

Researchers from Texas A&M University collected benthic infauna and epifauna between the 

Mississippi Delta and De Soto Canyon as part of the Mississippi-Alabama Continental Shelf Ecosystem 

Study. Polychaetes dominated the macroinfauna, comprising 58.3 percent of the specimens taken, 

followed by bivalves and amphipods, comprising 12.2 percent and 9.4 percent of the specimens collected 

(Harper, 1991). The density of the infaunal species was related to the sediment type where the highest 

densities were found in coarse sediments and lowest densities were found in slit and clay. Organism 

diversity and abundance also decreased with depth. Of the epifaunal species collected, decapods 

(primarily shrimp) made up over 77 percent, echinoderms made up over 9 percent and mollusks made up 

over 7 percent of the specimens taken (Harper, 1991). The decapods showed seasonal migration where 

they moved inshore to the Louisiana marshes during the summer and offshore during the winter (Harper, 

1991). 

Infaunal surveys of sand resources identified off the coast of Alabama described seasonal variation in 

dominant species. Sandy habitats were dominated by the gastropods Caecum pulchellum and Caecum 

cooperi (Byrnes et al., 1999). These two species were dominant in samples collected in both May and 

December; however, May surveys also had high numbers of spionid polychaetes (Paraprionospio pinnata

and Spiophanes bombyx), while December surveys had high numbers of the archiannelid Polygordius, the 

polychaete Scoletoma verrilli, and the amphipod Eudevenopus hondurans (Byrnes et al., 1999). Infaunal 

species richness was much higher in May than December, and assemblage was determined by grain size 

(Byrens et al., 1999), as reported by Harper (1991). Sandy sediments had high numbers of archiannelids 

(Polygordius), lancelet (Brachiostoma), and polychaete (Spiophanes bombyx), while finer sediments had 

greater numbers of the polychaetes Mediomastus and Paraprionospio pinnata (Byrnes at al., 1999). 

Epifaunal invertebrates collected off the Alabama coast were dominated by the roughneck shrimp 

(Trachypenaeus constrictus), squid (Loligo sp.), striped sea star (Luidia clathrata), and rock shrimp 

(Sicyonia spp.) (Byrnes et al., 1999). May surveys were numerically dominated by striped sea star, squid, 

and roughneck shrimp, while December surveys were dominated by roughneck shrimp, squid, penaeid 

shrimp, and rock shrimp (Byrnes et al., 1999). 
Description of the Environment and Impact Analysis 4-359 

Dames & Moore, Inc. (1979) collected meiofaunal, macroinfaunal, and macroepifaunal samples along 

the Mississippi-Alabama-Florida OCS during a MAFLA baseline environmental survey. Although many 

samples were collected to the east of the CPA, some samples were collected in the CPA. Those samples 

collected outside of the area were composed of similar organisms due to similar benthic environmental 

conditions in the northern Gulf of Mexico, and they may be used in determining trends. 

Nematodes and harpacticoid copepods are the most abundant meiofauna on the OCS of the northern 

Gulf of Mexico. Higher densities were recorded closer to shore, and they decreased with distance 

offshore. Densities tended to be highest in medium to fine sediments with a moderate to high carbonate 

composition (Dames & Moore, Inc., 1979). The macroinfauna were dominated by polychaetes. 

Macroinfauna also had the highest densities inshore and decreased offshore, and the greatest diversity 

occurred within 30-60 m (98-197 ft) of water. Density, however, decreased with decreasing grain size. 

Macroepifauna was dominated by crustaceans and mollusks, followed by echinoderms and coelenterates, 

and the macroepifauna followed the same density gradient offshore as the meiofauna and macroinfauna. 

Non-OCS Oil and Gas Program Threats to Benthic Communities 

The benthic communities are threatened by two natural environmental perturbations that occur on the 

Louisiana-Texas continental shelf: hypoxic to anoxic bottom conditions and tropical storms. Hypoxic 

conditions occur annually with inconsistent intensities and ranges (Rabalais et al., 2002). On average, 

one tropical storm of varying intensity occurs on the Louisiana continental shelf every 4 years (Stone, 

2001). 

The Gulf of Mexico hypoxic zone is a band that stretches along the Louisiana-Texas shelf each 

summer where the dissolved oxygen concentrations are less than 2 ppm. It is one of the largest hypoxic 

areas in the world’s coastal waters. The hypoxic zone is the result of excess nutrients, primarily nitrogen, 

in the water. More than half the nitrogen comes from nonpoint sources about the confluence of the Ohio 

and Mississippi Rivers. A large variability in river discharge exists from year to year (Nowlin et al., 

1998). Measurements of suspended particulate matter in the area of the proposed action have found 

concentrations from <1 to 10 mg/L. The rivers’ effects on temperature and salinity have been detected as 

far west as Galveston (Murray and Donley, 1996). 

Storms can physically affect shallow-bottom environments, causing an increase in sedimentation, a 

rapid change in salinity or dissolved oxygen levels, storm surge scouring, and remobilization of 

contaminants in the sediment (Engle et al., 2008). Storms have also been shown to uproot benthic 

organisms from the sediment and suspend them in the water column (Dobbs and Vozarik, 1983). Studies 

conducted in the coastal waters of Louisiana, Mississippi, and Alabama 2 months after the passing of 

Hurricane Katrina revealed a significant decrease in the number of species, species diversity, and species 

density (Engle et al., 2008). The opportunistic polychaetes Mediomastus ambiseta and Paraprionospio 

pinnata dominated benthic communities 2 months after the storm, and some other species were 

completely missing from the community (Engle et al., 2008). Evidence shows that communities are not 

completely restructured after a storm event, but there may be a dominance shift, at least temporarily 

(Dobbs and Vozarik, 1983). 

The frequent disturbances on the inner shelf cause the infaunal community to be dynamic and 

unstable and to remain at an immature level of development, compared with a mature and stable 

community comprised of large, deep-dwelling, head-down deposit feeders. Transitional taxa are able to 

numerically dominate habitats that experience various perturbations, including siltation, low salinity, and 

low levels of dissolved oxygen (hypoxia) (Thistle, 1981; Rabalais et al., 2002). Recolonization of 

depurated areas by populations from unaffected neighboring soft-bottom substrate would be expected to 

occur within a relatively short period of time (Dubois et al., 2009; Thistle, 1981). Initial repopulation 

from nearby stocks may begin with subsequent recruitment or immigration events and may be 

predominantly comprised of pioneering species, such as tube-dwelling polychaetes or oligochaetes 

(Rhodes and Germano, 1982). Full recovery will follow as later stages of successional communities 

overtake the opportunistic species (Rhodes and Germano, 1982), but the time it takes to reach a climax 

community may vary depending on the species and degree of impact. This environmental 

unpredictability selects for opportunistic organisms that rapidly reach sexual maturity and produce large 

quantities of offspring repeatedly throughout the year. Species requiring an extended growth and 

development period or more constant environmental conditions may not survive to maturity. These 
4-360 Central Planning Area Supplemental EIS 

environmental threats tend to produce communities with lower biodiversity and biomass since longerlived species tend to be eliminated. 

Deepwater Horizon Event Impacts on Soft-Bottom Benthic Communities 

The following sections contain all new data since the Multisale EIS and the 2009-2012 Supplemental 

EIS were prepared. Extensive literature, Internet, and database searches have been conducted for results 

of scientific data on soft-bottom benthic communities following the DWH event. Although many 

research cruises have occurred, very few reports containing data have been released as of the writing of 

this document. Descriptions of studies completed or in progress are discussed and any results indicated 

are included. Also, because the impacts of the oil spill are not yet known, possible impacts to soft-bottom 

benthic communities as a result of oil exposure are discussed. 

As discussed earlier, the majority of the seafloor of the Gulf of Mexico is covered in soft sediments. 

Oil released from the DWH event may have impacted some of the organisms that live on or in these 

sediments. Direct contact with high concentrations of oil may have resulted in acute toxicity to 

organisms, and lower concentration exposures may have resulted in sublethal impacts such as altered 

reproduction, growth, respiration, excretion, chemoreception, feeding, movement, stimulus response, and 

susceptibility to disease (Suchanek, 1993). These impacts may occur through exposure pathways at the 

sediment/water interface or in the sediment itself. 

It is important to note that the effects of oil exposure to soft-bottom benthos are anticipated to have 

only impacted a very small portion of the seafloor of the Gulf of Mexico. Although approximately 

4.64 million barrels of oil were released into the Gulf waters, not all of that oil reached the seafloor. It is 

estimated that 26 percent of the released oil remains in the environment as oil on or just below the water 

surface as a light sheen or tarballs, oil that was washed ashore or collected from the shore, and oil that is 

in the sediments (Lubchenco et al., 2010). This residual oil has been degrading over time. The greatest 

concentrations are expected to be near the wellhead and decrease with distance from the source. The 

modes of transport to the seafloor discussed below are anticipated to only deliver a small amount of oil to 

the seafloor with decreasing concentrations away from the well. 

Water Column and Sediment Water Interface Exposure 

Although a portion of the oil that was released rose to the sea surface, because the oil was ejected 

under pressure, oil droplets become entrained deep in the water column. The upward movement of the oil 

was reduced because methane in the oil was dissolved at the high underwater pressures, reducing the oil’s 

buoyancy (Adcroft et al., 2010). The large oil droplets rose to the sea surface, but the smaller droplets, 

formed by vigorous turbulence in the plume and the subsea injection of dispersants, remained neutrally 

buoyant in the water column, creating a subsurface plume of oil (Adcroft et al., 2010). Oil droplets less 

than 100 μm (0.0036 in) in diameter remained in the water column for several months (Joint Analysis 

Group, 2010a). Organisms may have been exposed to oil droplets in the water column (if they are 

mobile) or at the seafloor/water interface. 

Also, some chemically dispersed oil may have reached the seafloor, but presumably in very low 

concentrations. It is reported that chemically dispersed surface oil from the DWH event remained in the 

top 6 m (20 ft) of the water column where it mixed with surrounding waters and biodegraded (Lubchenco 

et al., 2010). Data from other studies on dispersant usage on surface plumes indicates that a majority of 

the dispersed oil remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 

2 m (6 ft) (McAuliffe et al., 1981a). Dispersant usage also reduces the oil’s ability to stick to particles in 

the water column, minimizing the ability of dispersed surface oil to sediment to particles and travel to the 

seafloor (McAuliffe et al., 1981a). Any dispersed oil that reached the seafloor from the water’s surface 

during this event would be expected to be at very low concentrations (less than 1 ppm) (McAuliffe et al., 

1981a). 

Oil dispersed in the subsurface plume may have also reached the seafloor. However, as with the 

surface dispersed oil, concentrations reaching the seafloor would be extremely low. Concentrations of 

dispersed and dissolved oil in the subsea plume were reported to be in the part per million range or less 

and decrease with distance from the wellhead (Lubchenco et al., 2010; Adcroft et al., 2010; Joint Analysis 

Group, 2010a). A recent report documents damage to a deepwater coral community in an area that oil 

plume models predict as the direction of travel for subsea oil plumes from the DWH event. Results are 
Description of the Environment and Impact Analysis 4-361 

still pending but it appears that a coral community about 15 m x 40 m (50 ft x 130 ft) in size was severely 

damaged and may have been the result of oil impacts (USDOI, BOEMRE, 2010j). A major difference 

between this occurrence and likely effects on soft bottoms is that the coral community forms structures 

that protrude up into the water column. These upright corals would be affected by a passing oil plume in 

a way that a typical smooth soft bottom would not. The oil plume would pass over smooth soft bottom, 

continuing the process of biodegradation in mid-water and continuing to be dispersed over a wide area. 

Dispersed oil may also come in contact with benthic organisms that move into the water column or at the 

sediment/water interface. However, during the passage of an oil plume, benthic filter or suspension 

feeders have the ability to simply withdraw into the substrate until water quality improves. 

There is very little data available on the impacts of the DWH event on benthic communities. There is 

no data to date on the concentrations of hydrocarbons in sediments or on benthic community structure on 

the seafloor of the Gulf of Mexico after this event. There are, however, a few data available on 

hydrocarbons and dissolved oxygen levels in the water column. Water column data may be used to 

speculate the exposures benthic organisms may have experienced at the sediment/water interface. 

Water samples collected by the R/V Weatherbird on May 23-26, 2010, located 40 nmi and 45 nmi 

(46 mi and 52 mi; 74 km and 83 km) northeast and 142 nmi (163 mi; 263 km) southeast of the DWH rig 

revealed that concentrations of total petroleum hydrocarbons in the water column were less than 0.5 ppm 

(Haddad and Murawski, 2010). The total petroleum hydrocarbons concentrations were generally higher 

near the water’s surface and closer to the wellhead (Haddad and Murawski, 2010; Joint Analysis Group, 

2010a). Concentrations of dispersed and dissolved oil in the subsea plume were reported to be in the part 

per million range or less and decrease with distance from the wellhead (Lubchenco et al., 2010; Adcroft et 

al., 2010; Joint Analysis Group, 2010a). 

The hydrocarbon concentrations in the water column and subsea plume were close to, and below, the 

values reported by others for dispersed oil in the water column after oil spills. McAuliffe et al. (1981a) 

reported dispersed oil concentrations between 1 and 3 ppm, 9 m (30 ft) below the sea surface, 1 hour after 

treatment with dispersant, and Lewis and Aurand (1997) reported dispersed oil concentrations <1 ppm, 

10 m (33 ft) below the sea surface. Although McAuliffe et al. (1981a) and Lewis and Aurand (1997) did 

not address subsea plumes, the oil concentrations in the subsea plume appear to be similar to the 

concentrations reported from surface use of dispersants (Lubchenco et al., 2010; Adcroft et al., 2010; 

Joint Analysis Group, 2010a). 

The available data suggest that the concentrations of oil in the water column were low and the oil was 

dispersed. This data suggest that, if any benthic organisms at the sediment/water interface were exposed 

to oil as a result of the DWH event, the concentrations were very low (in the part per million range or 

less). 

Hypoxia from Oil Biodegradation 

Reduced oxygen conditions, or hypoxia, caused by the presence of oil in the water column and 

resultant break down of petroleum hydrocarbons by bacteria was also a concern. Numerous stations were 

sampled throughout the Gulf of Mexico by several research vessels between May 8 and August 9, 2010. 

Measured dissolved oxygen levels never reached hypoxic conditions (1.4 ml/L or 2 mg/L) and, in fact, 

were never below 2.5 ml/L at any station sampled (Joint Analysis Group, 2010a and 2010b). 

A subsea hydrocarbon plume, which generally trended southwest from the release at the wellhead, 

was discovered during sampling events (Joint Analysis Group, 2010a). Dissolved oxygen anomalies were 

measured at 1,000-1,400 m (3,281-4,593 ft) below the sea surface, which corresponded to the depths that 

hydrocarbons from the DWH event were located (Joint Analysis Group, 2010b). Models indicated that 

hypoxic levels may be reached in the subsea plume when methane is oxidized (Adcroft et al., 2010). 

Field measurements indicated that these dissolved oxygen depressions, however, did not approach 

hypoxic levels as of August 9, 2010 (Joint Analysis Group, 2010b). The dissolved oxygen in the water 

column did not appear to be decreasing over time, indicating that the oil was mixing with the surrounding 

oxygen-rich water (Joint Analysis Group, 2010b). 

Dissolved oxygen measurements taken at the seafloor between May 15 and May 25 were between 

4.0 and 5.0 ml/L (Joint Analysis Group, 2010a). Dissolved oxygen was toward the lower end of the 

measurements south and southwest of the wellhead and was toward the higher end to the north and 

northwest of the wellhead (Joint Analysis Group, 2010a). This is the most recent data released for 
4-362 Central Planning Area Supplemental EIS 

dissolved oxygen levels on the seafloor at the time of this writing. Dissolved oxygen levels of this 

concentration are far above the hypoxic range (<1.4 ml/L) and are not anticipated to result in loss of the 

benthic population. 

A yearly hypoxic event on the continental shelf of the northern Gulf of Mexico off the Mississippi 

and Atchafalaya Rivers result in bottom oxygen levels dropping below 1.4 ml/L (2 mg/L) for prolonged 

periods during the spring through late summer (Rabalais et al., 2002). This hypoxic event results in lower 

dissolved oxygen levels than what were measured in the water column and bottom waters as a result of 

the DWH event (Joint Analysis Group, 2010a and 2010b; Haddad and Murawski, 2010). The yearly 

hypoxia results in most of the benthic organisms leaving the area or dying; however, data indicates that 

the benthic colonies recolonize yearly after this event (Rabalais et al., 2002; Diaz and Solow, 1999). This 

pattern of yearly disturbance and recruitment favors opportunistic species (for organisms that die as a 

result of the hypoxia), resulting in a community composition that does not reach its climax. 

Based on the above water column and seafloor data, benthic communities would not have been lost 

due to hypoxia caused by the DWH event. Naturally occurring, yearly annual events cause lower 

dissolved oxygen levels than what were recorded as a result of the DWH event. The yearly hypoxic zone 

would likely have occurred during the DWH event and resulting spill, with its typical effects. However, 

if any organisms were lost due to reduced oxygen levels caused by natural occurrences or by 

biodegradation of oil in the environment, they should recolonize the area similarly to the yearly hypoxic 

event. 

Sedimented Oil (Oil Adsorbed to Sediments) 

Some of the smaller suspended oil droplets resulting from forceful injection at depth could have been 

carried to the seafloor as a result of oil droplets sedimenting to suspended particles in the water column. 

Some portion of the oil treated with dispersant, although having less affinity for adhering to suspended 

sediment, may still have settled to the seafloor before completely biodegrading. Oiled sediment that 

settled to the seafloor may affect the underlying organisms. It is not yet known how much oil sedimented 

to particles and settled to the seafloor. If large amounts of oil made its way to the seafloor, the underlying 

benthic communities may have been smothered by the particles or exposed to toxic hydrocarbons. It is 

anticipated that the greatest concentration of sedimented oil occurred close to the well; oil would continue 

to disperse over wider areas with lower concentrations as it travels farther from the source (Haddad and 

Murawski, 2010; Joint Analysis Group, 2010a). 

Acute Toxicity and Recovery 

The greatest threat to the benthic communities is anticipated to be the sedimented oil that may reach 

the seafloor. Because oil concentrations decreased in the water column away from the well, the highest 

sedimented oil concentrations should be in areas closer to the well. Soft-bottom infaunal communities 

near the wellhead may have been negatively impacted by direct contact with sedimented oil and may 

experience sublethal (exposure) and/or lethal (smothering) effects. 

Localized areas of lethal effects will be recolonized by populations from neighboring soft-bottom 

substrate once the oil in the sediment has been sufficiently reduced to support marine life (Sanders et al., 

1980). Opportunistic species, such as tube-dwelling polychaetes or oligochaetes, will be the first to 

appear. These species will occur within the first recruitment cycle of the surrounding populations and 

from species immigrating from surrounding stocks (Rhodes and Germano, 1982). These pioneering 

species will maintain a stronghold in the area until community succession begins (Rhodes and Germano, 

1982; Sanders et al., 1980). Full recovery would follow as later stages of successional communities 

overtake the pioneering species (Rhodes and Germano, 1982). The time it takes to reach a climax 

community may vary depending on the species and degree of impact. Full benthic community recovery 

may take years to decades if the benthic habitat is heavily oiled (Gómez Gesteira and Dauvin, 2000; 

Sanders et al., 1980; Conan, 1982). 

One must be careful, however, in studying the impacts of the DWH event. One should not 

immediately designate benthic communities that contain pioneering species as areas that were defaunated 

as a result of the DWH event. Benthic populations in the Gulf of Mexico that experience yearly hypoxic 

events are permanently in early successional stages (Gaston et al., 1998; Diaz and Solow, 1999). These 
Description of the Environment and Impact Analysis 4-363 

communities are dominated by small, opportunistic, surface-feeding polychaetes and there is a lack of 

large, suspension-feeding bivalves (Gaston et al., 1998; Rabalais et al., 2002). 

However, one may be able to presume that the early successional stage of a large area of the northern 

Gulf of Mexico reveals its ability to quickly recover from stressful events, such as yearly hypoxia in 

areas, and therefore suggests that the benthic community may also rapidly return to its prior state if it was 

impacted by oil. Recovery after hypoxic events has been reported to begin within 6 months, and full 

recovery to the original community state has been seen in 1-2 years, depending on other environmental 

disturbances (Diaz and Solow, 1999; Harper et al., 1991). Similar recovery times would be expected for 

most communities exposed to sedimented oil unless the area is heavily oiled and, therefore, recovery 

could take much longer (Gómez Gesteira and Dauvin, 2000; Sanders et al., 1980; Conan, 1982). 

The areas that may be defaunated as a result of the DWH event are small compared with the area of 

the entire seafloor of the Gulf of Mexico. The greatest damage is anticipated to have occurred closest to 

the well where hydrocarbon readings were highest. Most of the seafloor is not anticipated to experience 

any impact from the event. In areas where low levels of oil reach the seafloor, sublethal or immeasurable 

impacts may occur. 

Sublethal Impacts 

Research on oil spilled from the Chevron Main Pass Block 41C Platform into the Gulf of Mexico has 

indicated that oil in bottom sediments can weather rapidly, leaving only a small percentage of the oil in 

the sediments after a year (McAuliffe et al., 1975). Substantial weathering was noted 1 week and 

1 month after the Chevron Main Pass spill, and the oil remained in the top 1.5 in (3.8 cm) of the sediment. 

Benthic community fluctuations could not be correlated to the oil in the sediment from this oil spill, and 

the numbers of brown and white shrimp and blue crabs in the area of the oil spill did not appear to 

decrease 3 months or 1 year after the spill (McAuliffe et al., 1975). Although the volume of the Chevron 

Main Pass spill was much less than the spill that resulted from the DWH event, it is probable that oil on 

the seafloor will behave the same way and weather similarly. 

The Ixtoc oil spill in the Bay of Campeche, Gulf of Mexico, was much more on scale with the volume 

of oil that entered the Gulf of Mexico. The Ixtoc blowout flowed for 290 days and resulted in an 

estimated 120,000 metric tons of oil reaching the seafloor (Jernelöv and Lindén, 1981). Oil reached the 

seafloor in small droplets in the offshore waters, although some aggregates formed nearshore. The 

approximate concentration of oil on the seafloor was 1 g/m2

, which is not high enough to cause 

substantial damage to a benthic ecosystem (Jernelöv and Lindén, 1981). Surface sediment samples 

collected mid- and post-spill did not reveal any hydrocarbons from the Ixtoc spill; however, hydrocarbons 

from this source were identified on suspended sediment in the water column (ERCO, 1982). This data 

show that the oil may take some time to reach the seafloor and when it does, it is widely dispersed. 

As with the Chevron Main Pass spill, depressions in the benthic community during and following the 

Ixtoc spill could not be linked to the oil because hydrocarbons from the blowout were not present in 

sediment samples (ERCO, 1982). The benthic populations were depressed following the spill compared 

with pre-spill conditions; however, environmental evidence was not strong enough to separate oil impacts 

from natural variation or possible storm damage impacts (Tunnell et al., 1981). Oil may have been 

present in the sediment and affected benthic communities, but weathered before sampling occurred, or oil 

in the water column may have affected species, but these possible factors were not measured (Rabalais, 

1990). 

Regardless of the speculations, field measurements indicate that the concentrations of oil that reached 

the seafloor were low even after uncontrolled flow for a long period of time, and the oil was vastly 

dispersed by the time it reached the seafloor. The inability to measure hydrocarbons in the sediment after 

the spill suggested that any oil that reached the seafloor had weathered rapidly. It is anticipated that 

similar dispersion of oil, rapid weathering, and resultant low-level, widespread concentrations of oil on 

the seafloor will be measured from the DWH event. 

Long-Term Impacts 

Long-term or low-level exposure may also occur to benthic infauna as a result of oil adhering to 

sediment. Mesocosm experiments using long-term, low-level concentrations of No. 2 fuel oil indicate 

acute toxicity to meiofauna due to direct oil contact and sublethal effects from sedimented oil and 
4-364 Central Planning Area Supplemental EIS 

byproducts of the decomposition of the sedimented oil (Frithsen et al., 1985). Long-term exposure to low 

levels of fuel oil was shown to affect recruitment success; meiofaunal population recovery took between 

2 and 7 months (Frithsen et al., 1985). These types of impacts would be expected farther from the well 

where oil concentrations were diluted with distance. 

An increase in contamination levels in sediments can result in a decrease in trophic diversity and an 

increase in opportunistic pollution tolerant species (Gaston et al., 1998). Contaminated and disturbed 

areas are generally dominated by small, subsurface deposit feeders (Gaston et al., 1998). These small 

opportunistic species live at the sediment water interface and are more tolerant of contaminants (Gaston et 

al., 1998). Those species that can tolerate the disturbed or contaminated environment and recruit rapidly 

will be the initial colonizers of the area. Two pioneering Capitellid polychaetes in the Gulf of Mexico 

known to tolerate environmental stress are Mediomastus californiensis and Notomastus latericeus, and 

they can be expected in recovering areas (Gaston et al., 1998). Amphipods on the other hand, especially 

of the genus Ampelisca, are extremely sensitive to oil pollution and would not be found in the early 

recovery stages after hydrocarbon pollution (Gómez Gesteira and Dauvin, 2000). The pioneering 

community will remain until later successional organisms settle, or the pioneering stage may remain in 

continually disturbed areas, such as those affected by yearly hypoxia. 

An alteration in the benthic trophic structure may impact food availability for fish and invertebrates. 

Burrowing polychaetes and subsurface deposit feeders are not important in the diets of the red drum and 

spotted sea trout, two commercially and recreationally important species in the Gulf of Mexico (Gaston et 

al., 1998). Therefore, an increase in opportunistic species will result in less available food for certain 

species of fish (Gaston et al., 1998). The small surface-dwelling opportunistic species, however, appear 

to be important in the diet of juvenile brown shrimp (McTigue and Zimmerman, 1998) and therefore may 

provide additional food sources for this species. Early stage successional communities, however, cannot 

store and regulate the nutritional energy that a later stage community can because the organisms are small 

and remain at the sediment surface, resulting in a less stable and productive food source for higher trophic 

levels (Diaz and Solow, 1999). 

Studies to Measure the Impact of the Deepwater Horizon Event 

Many studies have been planned to analyze the impact of the DWH event, and some have already 

been carried out. The limited data currently available on the impacts of the DWH event make it difficult 

to definitively describe any impacts that have occurred or may occur to the benthic communities in the 

CPA. However, the long-lasting impacts of this event will take years to determine. As more studies are 

conducted and more data are released, we will have a better understanding of the breadth of the effects of 

the DWH event and possible long-term effects. 

4.1.1.22.1.2. Impacts of Routine Events 

Background/Introduction 

The vast majority of the Gulf of Mexico seabed is comprised of soft sediments. These soft-bottom 

benthic communities of the CPA are described in Chapter 4.1.1.22.1.1. Impacts from routine oil and gas 

activities to the soft-bottom benthic communities are discussed in this section, as a majority of the oil and 

gas exploration would be conducted in soft seafloor sediments. This is an entirely new section, as softbottom benthic community impacts were not discussed in the Multisale EIS or the 2009-2012 

Supplemental EIS. Impacts to these communities include infrastructure emplacement, turbidity and 

smothering, drilling-effluent and produced-water discharges, and infrastructure removal. Disturbances of 

soft-bottom communities may cause localized disruptions to food sources for some large invertebrate and 

finfish species. 

It is important to note that the effects of routine events on soft-bottom benthos would only impact a 

very small portion of the 268,922 km2

 (103,831 mi2) of seafloor in the CPA. Impacts from the drilling of 

wells are generally confined to a few hundred meters from the well and impacts decrease with distance 

from the well. Recovery from construction impacts should begin within a year but may take several years 

to complete recovery (Rhodes and Germano, 1982; Neff et al., 2000; Newell et al., 1998). Recovery 

would depend on the benthic community composition, sediment type, and the intensity of the disturbance. 
Description of the Environment and Impact Analysis 4-365 

Long-term operational impacts are localized and generally result in a shift in benthic community 

dominance (Montagna and Harper, 1996). 

Construction Impacts on Infauna and Soft-Bottom Benthic Communities 

Organisms from the bacterial level up through polychaete worms and crabs inhabit the soft-bottom 

benthos. Many of these organisms form the base of the food chain for larger invertebrates and finfish 

species. Any immobile benthic organisms that are in the footprint of the infrastructure or pipeline 

emplacement would be physically crushed. The soft-bottom habitat would be replaced with a hard 

substrate for the life of the structure; for some, such as pipelines or seafloor templates that are abandoned 

in place at the end of their service, the substitution of hard bottom is permanent. While the substrate and 

community are changed, the change is generally considered an improvement in value and ecological 

services. This hard substrate would supply a foundation upon which encrusting organisms may settle 

(Gallaway and Lewbel, 1982). Encrusting organisms may include barnacles, oysters, mussels, bryozoans, 

hydroids, sponges, octocorals, corals, and algae (Gallaway and Lewbel, 1982). These organisms provide 

habitat and food for larger benthic organisms and finfish. The addition of a petroleum platform would 

result in a community shift from a soft-bottom infaunal community to a reef community above a softbottom benthic community. This shift provides more complex habitat, supporting more diverse 

assemblages than typical soft bottom. The shrimp trawling fishery is negatively affected to a small 

degree because structures create more obstacles to their trawling. There is also a reduction in trawlable 

area but this amount is so small compared with the available area (268,922 km2

; 103,831 mi2) as to be 

insignificant. 

The drilling of a well may result in water column turbidity, smothering of benthic organisms by the 

deposition of cuttings, coarsening of sediment near the well, trace metal contamination from cuttings, 

organic enrichment of the seabed, and hypoxic conditions if synthetic-based drilling fluid is used, and 

possible hydrocarbon contamination. Turbidity is a short-term impact as the cuttings rapidly sink to the 

seafloor. Burial of benthic communities and alteration of the sediment near the platform would result in 

the repopulation of smothered benthic habitats, possibly with different species that are adapted to coarser 

sediment. The impacts of long-term exposures to metals and hydrocarbons in the cuttings are discussed 

in the following section, as they occur during the lifetime of the project. 

Drilling disposal methodology (surface disposal or bottom shunting) and drilling fluid (synthetic or 

water based) would result in slight differences in the dispersal of the well cuttings and drilling muds. For 

example, well cuttings that are disposed of at the water’s surface tend to disperse in the water column and 

are distributed widely at low concentrations (CSA, 2004b; NRC, 1983). In deep water, cuttings 

discharged at the sea surface may spread out to 1,000 m (3,280 ft) from the source, depending on currents, 

with the thickest layers at the well and the majority of the sediment within 250 m (820 ft) (CSA, 2006a). 

On the other hand, cuttings that are shunted to the seafloor are concentrated over a smaller area in piles 

instead of being physically dispersed over wide areas (Neff, 2005). The heaviest concentrations of well 

cuttings and drilling fluids, for both water-based and synthetic-based drilling muds, have been reported 

within 100 m (328 ft) of well and are shown to decrease beyond that distance (CSA, 2004b; Kennicutt et 

al., 1996). Deposition may reach up to 500 m (1,640 ft) from the well, depending on surrounding 

environmental conditions (Kennicutt et al., 1996). 

Surface-released cuttings rarely accumulate thicknesses of about 1 m (3 ft) immediately adjacent to 

the well; thicknesses are usually not higher than a few tens of centimeters (about 1 ft) in the GOM. A 

gradient of cuttings that encompasses most of the cuttings settles within 100 m (328 ft) of the well site. 

Cuttings settle in a patchy distribution determined by water currents and limited to about 250 m (820 ft) 

from the well site (CSA, 2004b). Impacts would be less in shallow waters than deep waters, as the 

shallow water organisms have greater vertical migration ability in the sediment than the deepwater 

benthos (CSA, 2004b). Because cuttings are distributed unevenly and in patches, burial would be 

localized (CSA, 2004b). 

The greatest impact to the benthic community may result from the shunting of cuttings to the seafloor 

in order to protect nearby topographic features. Cuttings that are shunted to the seafloor form 

concentrated thicker depositions over a smaller area of soft seafloor (Neff, 2005). Any organisms beneath 

heavy layers of deposited cuttings would be smothered. 
4-366 Central Planning Area Supplemental EIS 

Additional stress may occur if synthetic drilling fluids are used. Base fluids of synthetic drilling 

muds that remain on the cuttings are designed to be low in toxicity and biodegradable in offshore marine 

sediments (Neff et al., 2000). However, as bacteria and fungi break down the synthetic drilling fluids, the 

sediments may become anoxic (Neff et al., 2000). Benthic macrofaunal recovery would occur when 

synthetic drilling mud concentrations are reduced to levels that enable the sediment to become 

reoxygenated (Neff et al., 2000). Complete community recovery from synthetic drilling mud exposure 

may take 3-5 years (Neff et al., 2000). 

Sediment grain size may be altered near the new structure. Investigations have shown that sediments 

were enriched with sandy material out to 100 m (328 ft) from a well (Kennicutt et al., 1996). Altered 

grain size can result in different species inhabiting the sediment. 

Recolonization and immigration by organisms from neighboring soft-bottom substrate to the 

impacted areas would be expected to occur within a relatively short period of time. Initial repopulation 

from nearby stocks may begin with the following recruitment event and be predominantly comprised of 

pioneering species, such as tube-dwelling polychaetes or oligochaetes (Rhodes and Germano, 1982). Full 

recovery would follow as later stages of successional communities overtake the opportunistic species 

(Rhodes and Germano, 1982), but the time it takes to reach a climax community may vary depending on 

the species and degree of impact. Initial recovery should be well advanced within a year following the 

deposition (Neff, 2005). Because some benthic communities in the northern Gulf of Mexico are 

permanently in early community successional stages due to frequent disturbances, full recovery may 

occur very quickly (Rabalais et al., 2002; Gaston et al., 1998; Diaz and Solow, 1999). 

Long-Term and Operational Impacts on Infauna and Soft-Bottom Benthic Communities 

Benthic organisms may experience long-term impacts such as exposure to contaminants, alteration in 

habitat, and a change in community structure as a result of offshore oil and gas production. These 

impacts are generally localized and occur close to the production platform (within 100-200 m [328-656 ft] 

from the platform) (Montagna and Harper, 1996; Kennicutt et al., 1996; Hart et al., 1989; Kennicutt, 

1995; CSA, 2004b). Sand content, metals, barium, inorganic carbon, and petroleum products have all 

been reported to be elevated near platforms (Kennicutt, 1995). Distribution of discharges tends to be 

patchy, have sharp gradients, and be directional (Kennicutt, 1995). The greatest impacts occur in low 

energy environments where depositions may accumulate and not be redistributed (Neff, 2005; Kennicutt 

et al., 1996). Despite these possible impacts, it is important to consider that they occur over a very small 

portion of the seafloor of the Gulf of Mexico. The CPA covers 268,922 km2

 (103,831 mi2) and is mostly 

soft-bottom sediment. 

Long-term impacts of oil and gas production have been studied in the Gulf of Mexico Offshore 

Monitoring Experiment and other monitoring programs. These programs indicated that the greatest longterm impacts to benthic organisms were from the deposition of drilling muds and cuttings on the seabed. 

Drilling mud is primarily composed of barium. Elevated levels of barium, silver, cadmium, mercury, 

lead, and zinc were found out to 200 m (656 ft) from platforms and are likely a product of drilling mud 

and cuttings (Kennicutt et al., 1996; Hart et al., 1989; Chapman et al., 1991; CSA, 2004b). The 

concentrations of metals decreased with distance from the platform and were highest in low energy 

environments (Kennicutt et al., 1996). 

Other additions of metals to sediments near offshore platforms may come from produced waters and 

corrosion of the structure itself. Information is contradictory on the distance from a platform that 

produced waters can affect benthic communities. Impacts have been reported from 100 m (328 ft) of the 

source to 1 km (0.6 mi) from the source (Peterson et al., 1996; Armstrong et al., 1977; Osenberg et al., 

1992). Elevated levels of lead, zinc, and cadmium in sediments near platforms are most likely deposited 

from produced waters and corrosion of the galvanized platform itself (Kennicutt et al., 1996). Lead 

concentrations have been reported to continue to accumulate in sediment during the lifetime of an 

offshore platform (Kennicutt et al., 1996). The continual addition of metals to sediment near platforms 

results in continuous exposure of benthos to the metals. 

Metal concentrations in sediments near gas platforms have been reported above those that may cause 

deleterious biological effects. Sublethal infaunal impacts have been reported out to 100 m (328 ft) from 

the platform. Of the species sampled, harpacticoid copepods were most sensitive to contamination. They 

showed reduced abundances, reduced survival, and increased reproductive effort paired with reduced 
Description of the Environment and Impact Analysis 4-367 

recruitment closer to platforms (Montagna and Harper, 1996; Carr et al., 1996). Copepods showed 

reduced genetic diversity near platforms and the production efficiency of nematodes was found to be 

reduced by half within 50-100 m (164-328 ft) of a platform (Montagna and Li, 1997; Kennicutt, 1995). 

The impacts are believed to be a result of metal toxicity originating from drill cuttings that remain in the 

sediment during the installation of the well (Montagna and Harper, 1996; Carr et al., 1996). 

Lethal impacts may also occur near the wells due to localized elevated metal concentrations in 

sediments from cuttings. Porewater toxicity as a result of metal contamination was detected near gas 

platforms (Carr et al., 1996). Sea urchin fertilization and embryological development were reduced 

within 150 m (492 ft) from gas platforms, as was polychaete reproduction and copepod nauplii survival 

(Carr et al., 1996; Kennicutt, 1995). 

Hydrocarbon contamination as a result of regular gas production activities is relatively low 

(Montagna and Harper, 1996). Hydrocarbon enrichment has been reported within 25 m (82 ft) and out to 

200 m (656 ft) of petroleum platforms, and the concentrations decreased with distance from the platforms 

(Hart et al., 1989; Chapman et al., 1991; Kennicutt, 1995; Kennicutt et al., 1996). The concentrations of 

PAH’s in the sediment surrounding platforms, however, were below the biological thresholds for marine 

organisms and appeared to have little effect on benthic organisms (Hart et al., 1989; McDonald et al., 

1996; Kennicutt et al., 1996). Other studies indicated that chronic low-level discharges from petroleum 

production in the northern Gulf of Mexico did not result in hydrocarbons accumulating to stressful levels 

in benthic organisms or resultant organism responses to the hydrocarbons (Sharp and Appan, 1982). 

It is anticipated that hydrocarbon contamination at oil-producing wells is higher than for gas wells 

(Carr et al., 1996). Unlike with metals, links between petroleum products and benthic impacts are not 

established (Holdway, 2002; Southwest Research Institute, 1981). It is possible that petroleum 

hydrocarbons in drilling muds and cuttings may cause toxicity to benthic organisms and bioaccumulate 

up the food chain; however, very little information is available on such impacts (Neff, 2005). It is also 

possible that continuous influx of contaminants from the Mississippi River and periodic flooding and 

storms mask the impact to benthic organisms from chronic exposure to petroleum production (Southwest 

Research Institute, 1981). Variation in natural environments also makes it difficult to determine a link 

between petroleum production impacts and natural environmental impacts on benthic communities 

(Holdway, 2002). 

The sedimentary environment surrounding a well may be altered by the disposal of cuttings on the 

seafloor. The sediment grain size near petroleum platforms was reportedly larger and enriched with sand 

compared with the surrounding environment (Kennicutt et al., 1996). Sediment was coarser within 100 m 

(328 ft) of a discharge site and sediment alterations have been reported out to 500 m (1,640 ft), depending 

on the surrounding environment and method of disposal (surface disposal or bottom shunting) (CSA, 

2004b; Kennicutt et al., 1996). Sediment was coarser near the platform, becoming finer with distance 

(Hart et al., 1989; Kennicutt, 1995). The field of impact is not heterogeneous and there are often 

concentration gradients within the discharged material, which is often deposited directionally as it is 

carried by water currents (Kennicutt, 1995). 

Metal and hydrocarbon concentrations and altered sediment characteristics near wells may result in an 

altered benthic population surrounding the production platform. Significant impacts to benthos as a result 

of sediment alteration were measured within a few hundred meters of petroleum platforms (Kennicutt, 

1995). The benthic assemblages within 150 m (492 ft) of some wells differed from the infaunal depositfeeding species farther from the well (Hart et al., 1989). Epifaunal organisms can be sloughed from the 

platform to the surrounding seafloor and the bottom community surrounding the platform may be similar 

to those associated with shell reefs, rubble bottoms, and hard substrates (Hart et al., 1989). The infaunal 

deposit-feeding species that are typical of the Gulf of Mexico seafloor become more prevalent with 

distance from the well. 

Contaminants also reportedly altered benthic community structure in a 25- to 100-m (82- to 328-ft) 

radius surrounding platforms (Chapman et al., 1991; Montagna and Harper, 1996). In general, 

polychaetes, bivalves, nemerteans, decapods, and isopods all increased near platforms, while amphipods 

and foraminiferans, which are more sensitive to contamination, decreased near platforms and increased 

with distance from the well (Chapman et al., 1991; Montagna and Harper, 1996; Kennicutt, 1995). 

Deposit feeders are generally much less sensitive to environmental contaminants than the crustaceans, and 

reduced crustacean populations are likely the result of elevated metal concentrations near platforms 

resulting from well drilling, produced waters, and corrosion of the structure (Peterson et al., 1996). 
4-368 Central Planning Area Supplemental EIS 

Mobile epifaunal organisms do not show trends associated with distance from platforms. Instead, 

each platform is a unique community that is influenced by the physical and chemical parameters of the 

platform itself (Ellis et al., 1996). The platforms, however, act as artificial reefs, attracting encrusting 

organisms to the introduced structure. The colonization of platforms and resultant attraction of fish and 

mobile invertebrates may result in localized organic enrichment in sediments near the platforms 

(Montagna and Harper, 1996). Organic enrichment has been reported within 100 m (328 ft) of wells and 

may alter benthic communities where sediment is enriched (CSA, 2004b). Enriched sediments may lead 

to increased infaunal deposit-feeder density and diversity near platforms as reported by Montagna and 

Harper (1996). The number of organisms was reportedly greater within 100 m (328 ft) of platforms, most 

likely due to the organic enrichment near platforms (Kennicutt, 1995). Surveys indicate that, although the 

number of organisms was high within this radius, species diversity was low and dominated by a few 

opportunistic species (CSA, 2004b). Elevated, nonselective, deposit-feeding populations near platforms 

are likely the combined result of enriched organic material near the platforms as a result of “organic 

shedding” from platforms and opportunistic species populating defaunated sediment as a result of metal 

toxicity or anaerobic conditions (Peterson et al., 1996; Kennicutt, 1995; CSA, 2004b). Deposit feeders 

are able to utilize organic material in polluted areas as a food source, allowing them to feed in areas other 

organisms cannot tolerate (Peterson et al., 1996). Bivalves may also be found in organically enriched 

areas as many bivalves are able to tolerate low dissolved oxygen levels that can occur in such 

environments (CSA, 2004b). 

Synthetic drilling fluids are designed to be nontoxic to marine organisms; however, as bacteria and 

fungi break down the synthetic drilling fluids, the sediments may become anoxic (Neff et al., 2000). The 

time it takes for the sediment to hold enough oxygen for organisms to populate the area may take several 

years (Neff et al., 2000). The time between drilling and repopulation may result in an altered benthic 

community. Monitoring of a drill site indicated that sediments out to 75 m (246 ft) from the site were 

anaerobic 4 months after drilling and benthic infauna abundance was low out to 200 m (656 ft) (CSA, 

2004b). The opportunistic polychaete, Capitella capitata, was abundant out to 125 m (410 ft) from the 

drill site but was not found beyond 200 m (656 ft) from the well (CSA, 2004b). Evidence of recovery 

was observed a year after drilling occurred, especially at stations greater than 75 m (246 ft) from the well 

(CSA, 2004b). After 2 years, community structure had recovered, but species composition was slightly 

altered (CSA, 2004b). Biological effects appear to be a result of the organic enrichment from syntheticbased drilling fluid, and the resultant biodegradation and anaerobic conditions (CSA, 2004b). 

It should be noted that the combined impacts of drilling wells may lead to unexpected ecological 

interactions surrounding wells. For example, infaunal deposit feeders are usually associated with finer 

sediments, but they are seen in the coarser sediments close to platforms. This is probably due to both 

tolerance to contaminants in the sediment and their ability to utilize organic enrichment in the sediment 

deposited by higher tropic levels or from the breakdown of synthetic drilling fluids. Epifaunal organisms, 

however, are those that associate with coarser sediments and reefs, as there is substrate on the reef and 

larger material in the sediment for attachment. These alterations lead to a local altered environment that 

is specific to each platform and its impacts on the surrounding environment (Montagna and Harper, 1996; 

Hart et al., 1989; Ellis et al., 1996). 

An alteration in the benthic community may impact food availability for fish and invertebrates. 

Burrowing polychaetes and subsurface deposit feeders are not important in the diets of the red drum and 

spotted sea trout, two commercially and recreationally important species in the Gulf of Mexico (Gaston et 

al., 1998). Therefore, an increase in opportunistic species would result in less available food for certain 

species of fish (Gaston et al., 1998). The small surface-dwelling opportunistic species, however, appear 

to be important in the diet of juvenile brown shrimp (McTigue and Zimmerman, 1998) and therefore may 

provide additional food sources for this species. Early stage successional communities, however, cannot 

store and regulate the nutritional energy that a later stage community can because the organisms are small 

and remain at the sediment surface, resulting in a less stable and productive food source for higher trophic 

levels (Diaz and Solow, 1999). This impact on higher trophic levels may last as long as the alteration in 

benthic community structure does. 
Description of the Environment and Impact Analysis 4-369 

Structure-Removal Impacts 

The impacts of structure removal on soft-bottom benthic communities can include turbidity, sediment 

deposition, explosive shock-wave impacts, and loss of habitat. Both explosive and nonexplosive removal 

operations would disturb the seafloor by generating considerable turbidity. Suspended sediment may 

evoke physiological impacts in benthic organisms including “changes in respiration rate, . . . abrasion and 

puncturing of structures, reduced feeding, reduced water filtration rates, smothering, delayed or reduced 

hatching of eggs, reduced larval growth or development, abnormal larval development, or reduced 

response to physical stimulus” (Anchor Environmental CA, L.P., 2003). The higher the concentration of 

suspended sediment in the water column and the longer the sediment remains suspended, the greater the 

impact. Also, different species have differing tolerances to suspended sediment. In general, polychaete 

worms can withstand much higher concentrations of suspended sediment in the water column than 

amphipods (Swanson et al., 2003). Bivalves can withstand high concentrations of suspended sediment by 

reducing net pumping rates and rejecting material in pseudofeces (Clarke and Wilber, 2000). Mobile 

organisms have a much better chance of escaping high suspended sediment concentrations and the 

possible resultant smothering than sessile organisms do because they can avoid areas of disturbance 

(Clarke and Wilber, 2000). 

Structural removal may also result in resuspension of contaminated sediments (Schroeder and Love, 

2004). The impact to benthic organisms as a result of contaminant exposure from suspended sediments is 

dependent on many variables and not well understood (Eggleton and Thomas, 2004). Acute toxicity, 

chronic impacts, and bioavailability would all be dependent on the changes in the physical and chemical 

environment as a result of the disturbance. 

Sediment deposition may smother benthic organisms, decreasing gas exchange, increasing exposure 

to anaerobic sediment, reducing light intensity, and causing physical abrasion (Wilber et al., 2005). Many 

benthic organisms have the ability to tolerate some sedimentation, as they experience it through natural 

processes (Wilber et al., 2005). For example, organisms may vertically migrate up through deposited 

sediment (Wilber et al., 2005). If a different size sediment is deposited on the seafloor than what is 

presently there, the impacts may be greater than if the same grain size was deposited, and the habitat may 

be altered as a result (Wilber et al., 2005). 

The shock waves produced by explosive structure removals damage some benthic organisms in the 

near vicinity of the blasts. O’Keeffe and Young (1984) described the impacts of underwater explosions 

on various forms of sea life using, for the most part, open-water explosions much larger than those used in 

typical structure-removal operations. They found that sessile benthic organisms, such as barnacles and 

oysters, and many motile forms of life, such as shrimp and crabs, that do not possess swim bladders were 

remarkably resistant to shock waves generated by underwater explosions. Oysters located 8 m (26 ft) 

away from the detonation of 135-kg (29-lb) charges in open water incurred a 5 percent mortality rate. 

Crabs distanced 8 m (26 ft) away from the explosion of 14-kg (31-lb) charges in open water had a 

90 percent mortality rate. Few crabs died when the charges were detonated 46 m (151 ft) away. 

O’Keeffe and Young (1984) also noted “. . . no damage to other invertebrates such as sea anemones, 

polychaete worms, isopods, and amphipods.” Impacts to invertebrates are anticipated to be minimal as 

they do not have air bladders inside their bodies that may burst with explosions as some fish do 

(Schroeder and Love, 2004). 

Benthic organisms appear to be further protected from the impacts of subbottom explosive 

detonations by rapid attenuations of the underwater shock wave traversing the seabed away from the 

structure being removed. The shock wave is significantly attenuated when explosives are buried as 

opposed to detonation in the water column (Baxter et al., 1982). Theoretical predictions suggest that the 

shock waves of explosives set 5 m (15 ft) below the seabed, as required by BOEMRE regulations, would 

attenuate blast effects (Wright and Hopky, 1998). 

Infrastructure or pipeline removal would impact both the communities that have colonized the 

structures and the soft-bottom benthos surrounding the structure. Removal of the structure itself would 

result in the removal of the hard substrate and encrusting community. The overall community would 

experience a reduction in species diversity (both epifaunal encrusting organisms and the fish and large 

invertebrates that fed on them) with the removal of the structure (Schroerer and Love, 2004). The

epifaunal organisms attached to the platform that are physically removed would die once the platform is 
4-370 Central Planning Area Supplemental EIS 

removed. However, the seafloor habitat would return to the original soft-bottom substrate that existed 

before the well was drilled. 

Some structures may be converted to artificial reefs. If the platform stays in place, the hard substrate 

and encrusting communities would remain part of the benthic habitat. The diversity of the community 

would not change and associated finfish species would continue to graze on the encrusting organisms. 

The community would remain an active artificial reef. However, the plugging of wells and other reef in 

place decommissioning activities would still impact benthic communities as discussed above, since all the 

steps for removal except final removal from the water would still occur. 

Proposed Action Analysis 

As mentioned earlier, a majority of the seafloor of the Gulf of Mexico is soft-bottom sediments. 

Drilling activities would occur directly in these soft substrates; however, these routine activities would 

only affect a small portion of the substrate and benthic communities of the Gulf of Mexico. The CPA 

covers 268,922 km2

 (103,831 mi2). Operations may affect soft-bottom benthic communities through 

drilling effluent discharges and produced-water discharges, blowouts, and oil spills. Of the small area 

affected, the impacts have been measured to reach only about 100-500 m (328-1,640 ft) from the 

production well. 

For the CPA proposed action, 65-121 exploration/and 338-576 development wells are projected 

(Table 3-2). Cuttings from the wells would be released at the sea surface and dispersed in the water 

column, resulting in a widespread deposition on the seafloor (up to 1,000 m [3,280 ft] distance; CSA, 

2006a). Deposition thickness would be patchy, but it should only accumulate a few centimeters to 

possibly a meter on the seafloor (beside the well) (CSA, 2004b and 2006a). Benthic organisms are 

anticipated to either vertically migrate through the depositional layers or immigrants would repopulate the 

smothered habitat. Altered community structure may occur as a result of the environmental changes, but 

this alteration would be limited to a few hundred meters from the well. 

If any of these wells are proposed near a topographic feature, no discharges would take place within 

the feature’s No Activity Zone. The drilling discharges would be shunted to within 10 m (33 ft) of the 

seafloor either within the 1,000-Meter Zone, 1-Mile Zone, 3-Mile Zone, or 4-Mile Zone (depending on 

the topographic feature) around the No Activity Zone (see Chapter 2.3.1.3.1 for specifics). This 

procedure would essentially prevent the threat of large amounts of drilling effluents reaching the biota of 

a given topographic feature. It would, however, result in heavy layers of cuttings on the seafloor, which 

could smother underlying benthic communities and create turbid waters in a localized area near the well. 

Seafloor depositions have been measured to 1,000 m (3,280 ft) in a gradient of declining density with 

distance from the well (Kennicutt et al., 1996; CSA, 2006a). Benthic organisms may not be able to 

vertically migrate through the heavy depositional layers near the well, but it is anticipated that they would 

repopulate the areas through the reproduction and immigration of nearby stocks. Altered community 

structure may occur as a result of environmental changes, but this alteration would be limited to a few 

hundred meters from the well. 

For the CPA proposed action, 32-44 production structures are projected. Between 23 and 32 structure 

removals using explosives are projected (Table 3-2). The explosive removals of platforms may impact 

the biota through suspended sediment, sediment redeposition and smothering, explosive shock, and loss 

of hard substrate habitat. Communities, however, are anticipated to recover. Turbidity impacts would be 

short lived, and many organisms are tolerant of short-term increases in turbidity. Repopulation of the area 

disturbed by burial and shock-wave effects would begin within 6 months to a year, although it may take 

several years for complete recovery (Rhodes and Germano, 1982; Neff et al., 2000; Newell et al., 1998). 

And although the hard substrate that provided structure for encrusting organisms that created an artificial 

reef habitat may be removed, the environment would return to its previous state as a soft-bottom infaunal 

community. 

Summary and Conclusion 

Although localized impacts to comparatively small areas of the soft-bottom benthic habitats would 

occur, the impacts would be on a relatively small area of the seafloor compared with the overall area of 

the seafloor of the CPA (268,922 km2

, 103,831 mi2). The greatest impact is the alteration of benthic 

communities as a result of smothering, chemical toxicity, and substrate change. Communities that are 
Description of the Environment and Impact Analysis 4-371 

smothered by cuttings repopulate, and populations that are eliminated as a result of sediment toxicity or 

organic enrichment would be taken over by more tolerant species. The community alterations are not so 

much the introduction of a new benthic community as a shift in species dominance (Montagna and 

Harper, 1996). These localized impacts generally occur within a few hundred meters of platforms, and 

the greatest impacts are seen close to the platform. These patchy habitats within the Gulf of Mexico are 

probably not very different from the early successional communities that predominate throughout areas of 

the Gulf of Mexico that are frequently disturbed (Rabalais et al., 2002; Gaston et al., 1998; Diaz and 

Solow, 1999). 

4.1.1.22.1.3. Impacts of Accidental Events 

Background/Introduction 

The majority of the seafloor of the Gulf of Mexico is comprised of soft substrate. The soft-bottom 

benthic communities of the CPA are described in Chapter 4.1.1.22.1.1. Any activity that may affect the 

soft-bottom communities would only impact a small portion of the overall area of the seafloor of the Gulf 

of Mexico. Because the soft-bottom substrate is ubiquitous throughout the Gulf of Mexico, there are no 

lease stipulations to avoid these communities. Other routine practices restrict detrimental activities that 

could cause undue harm to benthic habitats (e.g., discharge restrictions, debris regulations, NPDES 

permits). 

This is an entirely new section to this Supplemental EIS, as soft-bottom benthic community impacts 

were not discussed in the Multisale EIS or the 2009-2012 Supplemental EIS. Various Internet sources 

and journal articles were examined to discover information regarding impacts of oil on soft-bottom 

benthic organisms. Sources investigated include literature published in journals and websites (NOAA, 

USEPA, and coastal universities). 

Possible Modes of Exposure 

Oil released to the environment as a result of an accidental event may impact soft-bottom benthic 

communities in several ways. Oil may be physically mixed into the water column from the sea surface, 

injected below the sea surface and travel with currents, dispersed in the water column, or sedimented to 

particles and sink to the seafloor. These scenarios and their possible impacts are discussed in the 

following sections. 

An oil spill that occurs at the sea surface would result in a majority of the oil remaining at the sea 

surface. Lighter compounds in the oil may evaporate and some components of the oil may dissolve in the 

seawater. Evaporation allows the removal of the most toxic components of the oil, while dissolution may 

allow bioavailability of hydrocarbons to marine organisms for a brief period of time (Lewis and Aurand, 

1997). Remnants of the oil may then emulsify with water or sediment to particles and fall to the seafloor. 

A spill that occurs below the sea surface (at the rig, along the riser between the seafloor and sea 

surface, or through leak paths on the BOP/wellhead) would result in most of the released oil rising to the 

sea surface. All known reserves in the Gulf of Mexico have specific gravity characteristics that would 

preclude oil from sinking immediately after release at a blowout site. As discussed in Chapter 4.3.1.5.4 of 

the Multisale EIS, oil discharges that occur at the seafloor from a pipeline or loss of well control would 

rise in the water column, surfacing almost directly over the source location, thus not impacting sensitive 

deepwater communities. If the leak is deep in the water column and the oil is ejected under pressure, oil 

droplets may become entrained deep in the water column (Boehm and Fiest, 1982). The upward 

movement of the oil may be reduced if methane in the oil is dissolved at the high underwater pressures, 

reducing the oil’s buoyancy (Adcroft et al., 2010). The large oil droplets would rise to the sea surface, 

but the smaller droplets, formed by vigorous turbulence in the plume or the injection of dispersants, may 

remain neutrally buoyant in the water column, creating a subsurface plume (Adcroft et al., 2010). Oil 

droplets less than 100 μm (0.004 in) in diameter may remain in the water column for several months 

(Joint Analysis Group, 2010a). Dispersed oil in the water column begins to biodegrade and may 

flocculate with particulate matter, promoting sinking of the particles. 

Impacts that may occur to soft-bottom benthic communities as a result of a spill would depend on the 

type of spill, distance from the spill, and surrounding physical characteristics of the environment. As 

described above, most of the oil released from a spill would rise to the sea surface, therefore, reducing the 
4-372 Central Planning Area Supplemental EIS 

impact to benthic communities by direct oil exposure. However, small droplets of oil that are entrained in 

the water column for extended periods of time would migrate within the water column. Although these 

small oil droplets would not sink themselves, they may attach to suspended particles in the water column 

and then be deposited on the seafloor (McAuliffe et al., 1975). Exposure to subsea plumes, dispersed oil, 

or sedimented oil may result in impacts such as smothering, reduced recruitment success, reduced growth, 

toxicity to larvae, alteration of embryonic development, and altered community structure. These impacts 

are discussed in the following sections. 

Surface Slick and Physical Mixing 

Surface oil slicks can spread over a large area; however, the majority of the slick is comprised of a 

very thin surface layer of oil moved by winds and currents (Lewis and Aurand, 1997). The potential of 

surface oil slicks to affect benthic habitats is limited by its ability to mix into the water column. Softbottom benthic communities below 10-m (33-ft) water depth are protected from surface oil because of its 

lack of ability to mix with water (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 

2002). Benthic organisms would not become physically coated or smothered by surface oil. However, if 

this surface oil makes its way into the water column through physical mixing, the use of dispersants, or 

sedimenting to particles in the water column, benthic communities may be impacted. These scenarios are 

discussed in later sections. 

Disturbance of the sea surface by storms can mix surface oil into the water column, but the effects are 

generally limited to the upper 10 m (33 ft). Modeling exercises have indicated that oil may reach a depth 

of 20 m (66 ft). Yet at this depth, the spilled oil would be at concentrations several orders of magnitude 

lower than the amount shown to have an effect on marine organisms (Lange, 1985; McAuliffe et al., 1975 

and 1981a; Tkalich and Chan, 2002). Therefore, soft-bottom benthic communities located in shallow 

water have the potential to be fouled by oil that is floating on shallow water and mixes to the depth of the 

seafloor. Nearshore oil deposits that occur in sheltered areas, such as bays, may remain in the sediment 

and impact organisms for long periods. Oil in nearshore sediments was found in high concentrations 8 

years following the Exxon Valdez spill (Dean and Jewett, 2001). Benthic communities located in deeper 

water would not be impacted by oil physically mixed into the water column. However, if dispersants are 

used, they would enable oil to mix into the water column and possibly impact organisms in deeper water. 

Dispersants are discussed later in this section. 

Subsurface Plumes 

A subsurface oil spill or plume has the potential to reach a soft-bottom benthic community and cause 

negative effects. Such impacts on the biota may have severe and long-lasting consequences, including 

loss of habitat and biodiversity; change in community structure; toxicity to larvae and embryos; and failed 

reproductive success. 

A subsurface plume that contacts the seafloor may result in acute toxicity. The water accommodated 

fraction (WAF) or water soluble fraction (WSF) of oil that dissolves in water may be the most toxic to 

organisms, especially larvae and embryos in the water column or at the water sediment interface. Lethal 

effects for marine invertebrates have been reported at exposures between 0.10 ppm to 100 ppm WSF of 

oil (Suchanek, 1993). The WSF of petroleum hydrocarbons was reportedly highly toxic to the embryos 

of oysters and sea urchins, while sediment containing weathered fuel was not toxic to the same species 

(Beiras and Saco-Álvarez, 2006). Quahog clam embryos and larvae also experienced toxicity and 

deformation of several different crude oils at WSF concentrations between 0.10 ppm and 10 ppm (Byrne 

and Calder, 1977). An experiment indicated that the WSF of No. 2 fuel oil at a concentration of 5 ppm 

disrupted the cellular development of 270 out of 300 test organisms within 3 hours of exposure (Byrne, 

1989). After 48 hours exposure, all of the test organisms died and the 48-hour LC50 (lethal concentration 

for 50 percent of the test population) was calculated to be 0.59 ppm (Byrne, 1989). Another experiment 

indicated that a WSF of 0.6 ppm and greater of No. 2 fuel oil depressed respiration, reduced mobility of 

sperm, interfered with cell fertilization and embryonic cleavage, and retarded larval development of sand 

dollar eggs (Nicol et al., 1977). Experiments that exposed sea urchin embryos to 10-30 ppm WSF of 

diesel oil for 15-45 days resulted in defective embryonic development and nonviable offspring 

(Vashchenko, 1980). Therefore, any dissolved petroleum hydrocarbon constituents that reach larval 

benthic organisms may cause acute toxicity and other developmental effects to this life stage. 
Description of the Environment and Impact Analysis 4-373 

Sublethal responses of marine invertebrates may result in population level changes (Suchanek, 1993). 

Such sublethal responses may occur at concentrations as low as 1-10 ppb (Hyland and Schneider, 1976). 

Sublethal impacts may include reduced feeding rates, reduced ability to detect food, ciliary inhibition, 

reduced movement, decreased aggression, and altered respiration (Suchanek, 1993). 

The farther a subsea plume travels, the more physical and biological changes occur to the oil before it 

reaches benthic organisms. Oil becomes diluted as it physically mixes with the surrounding water, and 

some evaporation may occur from surface slicks. The most toxic compounds of oil are lost within the 

first 24 hours of a spill, leaving the heavier, less toxic compounds in the system (Ganning et al., 1984). 

Water currents could carry a plume to contact the seafloor directly but a likely scenario would be for the 

oil to adhere to other particles and precipitate to the seafloor, much like rainfall (ITOPF, 2007; Kingston 

et al., 1995). Oil also would reach the seafloor through consumption by plankton with excretion 

distributed over the seafloor (ITOPF, 2007). The longer and farther a subsea plume travels in the sea, the 

more dilute the oil will be (Vandermeulen, 1982; Tkalich and Chan, 2002). In addition, microbial 

degradation of the oil occurs in the water column, reducing toxicity (Hazen et al., 2010; McAuliffe et al., 

1981b). The oil will move in the direction of prevailing currents (S.L. Ross Environmental Research 

Ltd., 1997) and although the oil will weather with the distance it travels, low levels of oil transported in 

subsea plumes will impact benthic communities. These mechanisms would result in a wide distribution 

of small amounts of oil. This oil would be in the process of biodegradation from bacterial action, which 

would continue on the seafloor, resulting in scattered microhabitats with an enriched carbon environment 

(Hazen et al., 2010). 

Dispersed Oil 

Chemically dispersed oil from a surface slick is not anticipated to result in lethal exposures to 

organisms on the seafloor. The chemical dispersion of oil may increase the weathering process and allow 

surface oil to penetrate to greater depths than physical mixing would permit, and the dispersed oil 

generally remains below the water’s surface (McAuliffe et al., 1981b; Lewis and Aurand, 1997). 

However, reports on dispersant usage on surface plumes indicates that a majority of the dispersed oil 

remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (6 ft) 

(McAuliffe et al., 1981a). Dispersant usage also reduces the oil’s ability to stick to particles in the water 

column, slowing its rate of precipitation to the seafloor (McAuliffe et al., 1981a; Lewis and Aurand, 

1997). However, the use of dispersant increases oil concentrations in the water column, ultimately 

leading to precipitation on the seafloor in some form (Whittle et al., 1982). 

Field experiments designed to test dispersant use on oil spills reported dispersed oil concentrations 

between 1 and 3 ppm, 9 m (30 ft) below the sea surface, approximately 1 hour after treatment with 

dispersant (McAuliffe et al., 1981a and 1981b). Other studies indicated that dispersed oil concentrations 

were <1 ppm, 10 m (33 ft) below the sea surface (Lewis and Aurand, 1997). The above data indicate that 

the mixing depth of dispersed oil is less than the depths of the majority of the Gulf of Mexico. Oil 

plumes are carried by water currents; some of these currents may carry subsea plumes toward shore, 

reaching water shallow enough for the plume to impinge on the seafloor. Unless the source of the oil is in 

shallow water, the dispersed oil would likely be widely diffused by the time it reaches shallow water. 

Most currents, however, would move laterally along depth contours rather than approaching shore, since 

the shore acts as a barrier containing the water, much like a levee bounding a river; inshore water would 

have to be displaced for offshore currents to move shoreward. Therefore, most subsea oil plumes would 

continue in oceanic currents until the oil is deposited to the seafloor over time by flocculation (clumping), 

planktonic consumption and excretion, or bacterial biodegradation (eventually bacteria die and fall to the 

seafloor) (Hazen et al., 2010; ITOPF, 2007; Kingston et al., 1995). This pattern would result in 

distribution of tiny quantities of oil that are widely scattered over a very large area. This oil would be in 

the process of biodegradation from bacterial action, which would continue on the seafloor, resulting in 

scattered microhabitats with an enriched carbon environment (Hazen et al., 2010). 

Any dispersed surface oil that may reach the benthic communities in the Gulf of Mexico would be 

expected to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a). Such concentrations may 

not be life threatening to adult stages but may harm larval or embryonic life stages of benthic organisms 

(Fucik et al., 1995; Suchanek, 1993; Beiras and Saco-Álvarez, 2006; Byrne, 1989). The LC50 for blue 

crab, white shrimp, and brown shrimp exposed to western and central Gulf of Mexico oil dispersed with 
4-374 Central Planning Area Supplemental EIS 

Corexit 9527 experienced toxicity of 50 percent of the test population at concentrations an order of 

magnitude greater than what is expected for dispersed oil in the environment (Fucik et al., 1995). Any 

dispersed oil in the water column that comes in contact with benthic organisms, however, may evoke 

short-term negative responses by the organisms or altered embryonic survival and development such as 

that discussed in the subsurface plumes section. 

Dispersants that are used on oil below the sea surface can travel with currents through the water and 

may contact benthic organisms on the seafloor. It is possible that the dispersed oil could be concentrated 

enough to harm a benthic community near the oil’s source. However, the longer the oil remains 

suspended in the water column traveling with currents, the more it would disperse. Weathering would 

also be accelerated and biological toxicity reduced (McAuliffe et al., 1981b). Although the use of subsea 

dispersants is a new technique and very little data are available on dispersion rates, it is anticipated that 

any oil that could reach the seafloor would be in low concentration based on surface slick dilution data 

(McAuliffe et al., 1981a; Lewis and Aurand, 1997). Therefore, impacts resulting from exposure to 

dispersed oil, except possibly for communities very close to applications, are anticipated to be sublethal. 

Soft-bottom infaunal communities near the oil spill that are negatively impacted by direct contact 

with oil or dispersed oil may experience sublethal and/or lethal effects. Localized areas of lethal effects 

would be recolonized by populations from neighboring soft-bottom substrate once the oil in the sediment 

has been sufficiently reduced to support marine life (Sanders et al., 1980). This initial recolonization 

process may be fairly rapid, but full recovery may take up to 10 years, depending on the species present, 

substrate in the area, toxicity of oil spilled, concentration and dispersion of oil spilled, and surrounding 

environmental factors that may also affect recruitment (Kingston et al., 1995; Gómez Gesteira and 

Dauvin, 2000; Sanders et al., 1980; Conan, 1982). Opportunistic species would take advantage of the 

barren sediment, repopulating impacted areas first. These species may occur within the first recruitment 

cycle of the surrounding populations or from species immigration from surrounding stocks, and they may 

maintain a stronghold in the area until community succession proceeds (Rhodes and Germano, 1982; 

Sanders et al., 1980). 

Sedimented Oil (Oil Adsorbed to Sediment) 

Smaller suspended oil droplets could be carried to the seafloor as a result of oil droplets adhering to 

suspended particles in the water column. Smaller particles have a greater affinity for oil (Lewis and 

Aurand, 1997). Oil may also reach the seafloor through consumption by plankton with excretion 

distributed over the seafloor (ITOPF, 2007). Oiled sediment that settles to the seafloor may affect benthic 

organisms. It is anticipated that the greatest amount of sedimented oil would occur close to the spill, with 

lesser concentrations farther from the source. Studies after a spill that occurred at the Chevron Main Pass 

Block 41C Platform in the northern Gulf of Mexico revealed that the highest concentrations of oil in the 

sediment were close to the platform and that the oil settled to the seafloor within 5-10 mi (8-16 km) of the 

spill site (McAuliffe et al., 1975). Therefore, the benthic communities closest to the source of a spill may 

become smothered by the particles and exposed to toxic hydrocarbons. 

Oiled sediment depositional impacts, however, are possible as a result of an oil spill and may smother 

nearby benthic species. Organisms that are physically smothered by sedimented oil, or the oil itself, may 

experience reduced respiration and inhibition of movement, and mobile organisms may experience 

additional weight or shearing forces form the sedimented oil (Suchanek, 1993). Barnacles, for example, 

are extremely tolerant to oil exposure but would die if smothered by it (Suchanek, 1993). 

Locations closest to the oil spill would have elevated contaminant levels in sediments. Deposition of 

sedimented oil is anticipated to begin occurring within days or weeks of the spill and may be fairly deep 

(Ganning et al., 1984; Gómez Gesteira and Dauvin, 2000). Oily sand layers were reported to be 10 cm 

(4 in) deep on the seafloor near the Amoco Cadiz spill (Gómez Gesteira and Dauvin, 2000). Acute 

toxicity may occur near the spill, eliminating benthic communities. As the benthic species recolonize the 

area, there would be a reduced trophic diversity and an increase in opportunistic pollution tolerant species 

(Gaston et al., 1998). 

Those species that can tolerate the disturbed or contaminated environment and can recruit rapidly 

would be the initial colonizers of the impacted area. Recolonization and immigration by organisms from 

neighboring soft-bottom substrate to the impacted areas would be expected to occur within a relatively 

short period of time. Initial repopulation from nearby stocks may begin with the following recruitment 
Description of the Environment and Impact Analysis 4-375 

event and be predominantly comprised of pioneering species, such as tube-dwelling polychaetes or 

oligochaetes (Rhodes and Germano, 1982). The contaminated or disturbed area would be initially 

dominated by small, opportunistic, subsurface deposit feeders that inhabit the sediment water interface 

and are more tolerant of contaminants (Gaston et al., 1998). Two pioneering Capitellid polychaetes in the 

Gulf of Mexico known to tolerate environmental stress are Mediomastus californiensis and Notomastus 

latericeus, and they would be the first to inhabit recovering areas (Gaston et al., 1998). Amphipods on 

the other hand, especially of the genus Ampelisca, are extremely sensitive to oil pollution and would not 

be found in the early recovery stages after hydrocarbon pollution (Gómez Gesteira and Dauvin, 2000). 

Full recovery would follow as later stages of successional communities overtake the opportunistic species 

(Rhodes and Germano, 1982), but the time it takes to reach a climax community may vary depending on 

the species and degree of impact. Initial recovery should be well advanced within a year following the 

deposition (Neff, 2005). Because some benthic communities in the northern Gulf of Mexico are 

permanently in early community successional stages due to frequent disturbances, full recovery may 

occur very quickly (Rabalais et al., 2002; Gaston et al., 1998; Diaz and Solow, 1999). 

Experiments and field data indicate that benthic recovery will take approximately 1 year to occur. 

For example, a study of the recolonization and succession of subtidal macrobenthos in sediment 

contaminated with petroleum hydrocarbons indicated that recovery to pre-oiling conditions took 

11 months (Lu and Wu, 2006). Initial colonization occurred within the first month of the study and 

polychaetes dominated the population (Lu and Wu, 2006). A crest after 3 months occurred with 

polychaetes being dominant, then at 6 months a peak occurred with bivalves dominating, followed by a 

decline in number of organisms and a leveling off of the community at 11 months (Lu and Wu, 2006). A 

similar time scale was observed in Corpus Christi Bay, Texas, where recovery from dredge material 

placement occurred after 1 year (Wilber et al., 2008). Recovery of benthic populations in soft subtidal 

environments, however, has been reported to take up to 5-10 years after oiling (Ganning et al., 1984; 

Gómez Gesteira and Dauvin, 2000). The overall recovery would depend on the extent of oiling, presence 

of recolonizers nearby, time of year for reproduction of those colonizers, currents and water circulation 

patterns, and the ability of the recolonizers to tolerate the sediment conditions (Ganning et al., 1984). 

Certain species are more sensitive to oil than others. Crustaceans, for example, are very sensitive to 

oil and have disappeared from oiled environments and had slow returns to the oiled areas (Dean and 

Jewett, 2001; Gómez Gesteria and Dauvin, 2000). The amphipod, Ampelisca sp., which disappeared from 

some sediments after the Amoco Cadiz oil spill took 2 years to begin repopulating areas, as the sediments 

decreased in contamination (Gómez Gesteira and Dauvin, 2000). Polychaetes, on the other hand, are 

much less sensitive to oil pollution and may experience population booms in contaminated areas (Gómez 

Gesteira and Dauvin, 2000). 

The benthic population may be altered following an oil spill, and the return to pre-spill conditions 

may take many years. Opportunistic species are usually the first to occupy contaminated sediments, 

especially the polychaete, Capitella capitata (Sanders et al., 1980). Some polychaetes have been reported 

to have positive responses to oiling where they have greater densities at oiled sites compared with oil-free 

sites (Dean and Jewett, 2001). Concentrations as low as 10 ppm may alter benthic community structure 

(Gómez Gesteira and Dauvin, 2000). 

An alteration in the benthic trophic structure may impact food availability for fish and invertebrates. 

Burrowing polychaetes and subsurface deposit feeders are not important in the diets of the red drum and 

spotted sea trout, two commercially and recreationally important species in the Gulf of Mexico (Gaston et 

al., 1998). Therefore, an increase in opportunistic species would result in less available food for certain 

species of fish (Gaston et al., 1998). The small surface-dwelling opportunistic species, however, appear 

to be important in the diet of juvenile brown shrimp (McTigue and Zimmerman, 1998) and therefore may 

provide additional food sources for this species. Early stage successional communities, however, cannot 

store and regulate the nutritional energy that a later stage community can because the organisms are small 

and remain at the sediment surface, resulting in a less stable and productive food source for higher trophic 

levels (Diaz and Solow, 1999). 

Oil may be persistent when deposited in soft-bottom habitats, and biodegradation rates may be slower 

than those in coarser sediments (Dean and Jewett, 2001; Whittle et al., 1982). The oil at the surface may 

be weathered by bacteria, but the oil that is buried may remain unchanged for long periods of time 

because oxygen is required to weather oil, and lower sediment layers may be anoxic (Whittle et al., 1982; 

Ganning et al., 1984). Infaunal benthic species may be very sensitive to the persistent oil in benthic 
4-376 Central Planning Area Supplemental EIS 

sediments that do not experience rapid biodegradation (Ganning et al., 1984). Oil that penetrates deep 

into the sediment can also cause anoxia and toxicity to the infaunal population as a result (Ganning et al., 

1984). Minimum residence time for oil deposited in offshore sediments is estimated to be 3-4 years 

(Ganning et al., 1984; Moore, 1976). 

Long-term or low-level exposure may also occur to benthic infauna exposed to oil adhered to 

sediment. Mesocosm experiments using long-term, low-level concentrations of No. 2 fuel oil indicate 

acute toxicity to meiofauna due to direct oil contact and sublethal effects from sedimented oil and 

byproducts of the decomposition of the sedimented oil (Frithsen et al., 1985). Long-term exposure to low 

levels of fuel oil was shown to affect recruitment success; meiofaunal population recovery took between 

2 and 7 months (Frithsen et al., 1985). These types of impacts would be expected farther from the well 

where oil concentrations were diluted with distance. 

Some oiled particles may become widely dispersed as they travel with currents while they settle out 

of suspension. Sedimented oil may travel great distances from the spill site and could be deposited 1-2 

years following the spill (Suchanek, 1993). Settling rates are determined by size and weight of the 

particle, salinity, and turbulent mixing in the area (Poirier and Thiel, 1941; Bassin and Ichiye, 1977; 

Deleersbijder et al., 2006). Because particles would have different sinking rates, the oiled particles would 

be dispersed over a large area, most likely at sublethal or immeasurable levels. Studies conducted after 

the Ixtoc oil spill revealed that, although oil was measured on particles in the water column, measurable 

petroleum levels were not found in the underlying sediment (ERCO, 1982). Based on the settling rates 

and behavior of sedimented oil, the majority of organisms that may be exposed to sedimented oil are 

anticipated to experience low-level concentrations. 

Research on oil spilled from the Chevron Main Pass Block 41C Platform into the Gulf of Mexico has 

indicated that oil in bottom sediments can weather rapidly, leaving only a small percentage of the oil in 

the sediments after a year (McAuliffe et al., 1975). Substantial weathering was noted 1 week and 

1 month after the Chevron Main Pass spill and the oil remained in the top 1.5 in (3.8 cm) of the sediment. 

Benthic community fluctuations could not be correlated to the oil in the sediment from this oil spill and 

the numbers of brown and white shrimp and blue crabs in the area of the oil spill did not appear to 

decrease 3 months or 1 year after the spill (McAuliffe et al., 1975). 

The toxicity of the oil is greatly reduced by the time it reaches the seafloor as a result of weathering in 

the water column (Ganning et al., 1984). The Ixtoc blowout flowed for 290 days and resulted in an 

estimated 120,000 metric tons of oil reaching the seafloor (Jernelöv and Lindén, 1981). Oil reached the 

seafloor in small droplets in the offshore waters, although some aggregates formed nearshore. The 

approximate concentration of oil on the seafloor was 1g/m2

, which is not high enough to cause substantial 

damage to a benthic ecosystem (Jernelöv and Lindén, 1981). Surface sediment samples collected midand post-spill did not reveal any hydrocarbons from the Ixtoc spill; however, hydrocarbons from this 

source were identified on suspended sediment in the water column (ERCO, 1982). These data show that 

the oil may take some time to reach the seafloor and when it does, it is widely dispersed and weathered. 

As with the Chevron Main Pass spill, depressions in the benthic community during and following the 

Ixtoc spill could not be linked to the oil because hydrocarbons from the blowout were not present in 

sediment samples (ERCO, 1982). The benthic populations were depressed following the spill compared 

with pre-spill conditions; however, environmental evidence was not strong enough to separate oil impacts 

from natural variation or possible storm damage impacts (Tunnell et al., 1981). Oil may have been 

present in the sediment and affected benthic communities but weathered before sampling occurred, or oil 

in the water column may have affected species, but these possible factors were not measured (Rabalais, 

1990). 

Regardless of the speculations, field measurements indicate that the concentrations of oil that reached 

the seafloor were low even after uncontrolled flow for a long period of time, and the oil was vastly 

dispersed by the time it reached the seafloor. Inability to measure hydrocarbons in the sediment after the 

spill suggested that any oil that reached the seafloor had weathered rapidly. It is anticipated that similar 

dispersion of oil, rapid weathering, and resultant low-level, widespread concentrations of oil on the 

seafloor may be measured from similar blowouts. 

Weathered oil is less toxic than freshly spilled oil because the remaining constituents are the larger, 

less bioavailable compounds (Ganning et al., 1984). The oil deposited on the seafloor is weathered from 

traveling in the water column and has lost a majority of its toxic compounds (Beiras and Saco-Álvarez, 

2006). For example, amphipods, which are very sensitive to petroleum hydrocarbons, do not experience 
Description of the Environment and Impact Analysis 4-377 

the level of toxicity when exposed to weathered oil that they do to fresh oil (Gómez Gesteira and Dauvin, 

2000). Therefore, the majority of the oil that is on the seafloor would most likely result in sublethal 

impacts rather than acute toxicity, except for oil that may be rapidly deposited on the seafloor near the 

source of the spill. 

Blowout and Sedimentation 

Oil or gas well blowouts are possible occurrences in the OCS. Benthic communities exposed to large 

amounts of resuspended sediments following a subsurface blowout could be subject to sediment 

suffocation and exposure to toxic contaminants. Sediment deposition may smother benthic organisms, 

decreasing gas exchange, increasing exposure to anaerobic sediment, and causing physical abrasion 

(Wilber et al., 2005). Should oil or condensate be present in the blowout flow, liquid hydrocarbons could 

be an added source of negative impact on the benthos. 

In rare cases, a portion or the entire rig may sink to the seafloor as a result of a blowout. The benthic 

communities on the seafloor upon which the rig settles would be destroyed or smothered. A settling rig 

may suspend sediments, which may smother nearby benthic communities as the sediment is redeposited 

on the seafloor. The habitats beneath the rig may be permanently lost; however, the rig itself may become 

an artificial reef upon which epibenthic organisms may settle. The rig may add to the contaminants in the 

local area by leaking stores of fuel, oil, well treatment chemicals, and other toxic substances. The 

surrounding benthic communities that were smothered by sediment would repopulate from nearby stocks 

through spawning recruitment and immigration. 

Soft-bottom infaunal communities that are smothered or lost would be recolonized by populations 

from neighboring soft-bottom substrate. Recolonization would begin with the next recruitment cycle of 

the surrounding populations or from species immigration from surrounding stocks and may maintain a 

stronghold in the area until community succession begins (Rhodes and Germano, 1982; Sanders et al., 

1980). Repopulation and succession in a disturbed bay off coastal Texas occurred within a year (Wilber 

et al., 2008). 

Response Activity Impacts 

Oil-spill-response activity may also affect sessile benthic communities. Continued localized 

disturbance of soft-bottom communities may occur during oil-spill-response efforts. Anchors used to set 

booms to contain oil or vessel anchors in decontamination zones may affect infaunal communities in the 

response activity zone. Infaunal communities may be altered in the anchor scar, and deposition of 

suspended sediment may result from setting and resetting of anchors. Anchors may also destroy 

submerged vegetation, altering benthic habitat (Dean and Jewett, 2001). The disturbed benthic 

community should begin to repopulate from the surrounding communities during their next recruitment 

event and through immigration of organisms from surrounding stocks. Any decontamination activities, 

such as cleaning vessel hulls of oil, may also contaminate the sediments of the decontamination zone, as 

some oil may settle to the seabed, impacting the underlying benthic community. 

If a blowout occurs at the seafloor, drilling muds (primarily barite) may be pumped into a well in 

order to “kill” it. If a kill is not successful, the mud (possibly tens of thousands of barrels) may be forced 

out of the well and deposited on the seafloor near the well site. Any organisms beneath heavy layers of 

the extruded drilling mud would be buried. Base fluids of drilling muds are designed to be low in toxicity 

and biodegradable in offshore marine sediments (Neff et al., 2000). However, as bacteria and fungi break 

down the drilling fluids, the sediments may be come anoxic (Neff et al., 2000). Benthic macrofaunal 

recovery would occur when drilling mud concentrations are reduced to levels that enable the sediment to 

become reoxygenated (Neff et al., 2000). Complete community recovery from drilling mud exposure 

may take 3-5 years, although microbial degradation of drilling fluids, followed by an influx of tolerant 

opportunistic species, is anticipated to begin almost immediately (Neff et al., 2000). 

Proposed Action Analysis 

A subsurface spill or plume may impact soft-bottom benthic communities. Oil or dispersed oil may 

cause lethal or sublethal impacts to benthic organisms where a plume may contact them. Impacts may 

include loss of habitat and biodiversity, contamination of substrate, change in community structure, 
4-378 Central Planning Area Supplemental EIS 

toxicity to larvae and embryos, and failed reproductive success. Sedimented oil or sedimentation as a 

result of a blowout would impact benthic organisms, although the greatest impact would be to those 

organisms closest to the spill. Communities farther from the spill may experience low-level exposure and 

possibly sublethal impacts. It is important to note that soft sediments cover a majority of the seafloor of 

the Gulf of Mexico and any impacts incurred, even lethal exposures, would not impact the overall 

population of soft-bottom benthic organisms that inhabit the seafloor of the Gulf of Mexico. Any local 

communities that are lost would be repopulated fairly rapidly (Neff, 2005). Those communities that are 

continuously in an early successional stage would reach their previous community composition rapidly, in 

as little as 1 year (Gaston et al., 1998). 

Summary and Conclusion 

Because of the small amount of proportional space that OCS activities occupy on the seafloor, only a 

very small portion of the seafloor of the Gulf of Mexico would experience lethal impacts as a result of 

blowouts, surface and subsurface oil spills, and the associated effects. The greatest impacts would be 

closest to the spill, and impacts would decrease with distance from the spill. Contact with spilled oil at a 

distance from the spill would likely cause sublethal to immeasurable effects to benthic organisms because 

the distance of activity would prevent contact with concentrated oil. Oil from a subsurface spill that 

reaches benthic communities would be primarily sublethal and impacts would be at the local community 

level. Any sedimentation and sedimented oil would also be at low concentrations by the time it reaches 

benthic communities far from the location of the spill, also resulting in sublethal impacts. Also, any local 

communities that are lost would be repopulated fairly rapidly (Neff, 2005). Although an oil spill may 

have some detrimental impacts, especially closest to the occurrence of the spill, the impacts may be no 

greater than natural biological fluctuations (Clark, 1982), and impacts would be to an extremely small 

portion of the overall Gulf of Mexico. 

4.1.1.22.1.4. Cumulative Impacts 

This cumulative analysis considers the effects of impact-producing factors related to soft bottoms of 

the Gulf of Mexico continental shelf. The proposed action plus those related to prior and future OCS 

lease sales are considered; in this discussion, these are referred to as “OCS-related” factors. Other 

impacting factors that may occur and adversely affect soft-bottom benthic communities include shipping 

operations, cable and pipeline laying, bottom trawling, hypoxia (low oxygen levels 2 ppm), and storm 

events. The vast majority of the Gulf of Mexico seabed is comprised of soft sediments and drilling is 

focused on these sediments, so the greatest number of impacts occurs on soft-bottom benthic 

environments. Specific OCS-related, impact-producing factors considered in the analysis are structure 

emplacement and removal, anchoring, discharges from well drilling, produced waters, pipeline 

emplacement, oil spills, blowouts, and operational discharges. Non-OCS-related impacts, including 

commercial fisheries, natural disturbances, anchoring by recreational boats, and other non-OCS 

commercial vessels, as well as spillage from import tankering, all have the potential to damage softbottom benthic communities. 

There are no BOEMRE stipulations that require avoidance of soft-bottom benthic communities 

because they are so ubiquitous throughout the seafloor of the Gulf of Mexico; most of the 268,922 km2

(103,831 mi2

) of the CPA are soft mud bottoms; they are the substrate upon which well drilling occurs. It 

is important to note, however, that because the soft-bottom benthic communities comprise a majority of 

the seafloor of the Gulf of Mexico, impacts are not detrimental to the overall population of these habitats 

across the Gulf of Mexico. Also, because a large portion of the seafloor is subject to natural fluctuations 

and physical disturbances (such as storms and yearly hypoxic events), a permanent early successional 

community occupies much of the seafloor and enables rapid recovery of disturbed areas. 

Severe physical damage may occur to soft-bottom sediments and the associated benthic communities 

as a result of non-OCS activities. It is assumed infauna associated with soft-bottom sediments of the CPA 

are well adapted to natural disturbances such as turbidity and storms. However, human disturbance, such 

as trawling or non-OCS activity oil spills, could cause severe damage to infauna, possibly leading to 

changes of physical integrity, species diversity, or biological productivity. If such events were to occur, 

recovery to pre-impact conditions could take approximately a year (Lu and Wu, 2006; Neff, 2005), with 

the overall recovery time depending on the extent of oiling, presence of recolonizers nearby, time of year 
Description of the Environment and Impact Analysis 4-379 

for reproduction of those colonizers, currents and water circulation patterns, and the ability of the 

recolonizers to tolerate the sediment conditions (Ganning et al., 1984). Recovery of benthic populations 

in soft subtidal environments, however, have been reported to take up to 5-10 years after oiling (Ganning 

et al., 1984; Gómez Gesteira and Dauvin, 2000). However, because some benthic communities in the 

northern Gulf of Mexico are permanently in early community successional stages due to frequent 

disturbances, full recovery may occur very quickly (Rabalais et al., 2002; Gaston et al., 1998; Diaz and 

Solow, 1999). 

Non-OCS activities have a greater potential to affect the soft-bottom communities of the region than 

BOEMRE-regulated activities. Natural events such as storms, extreme weather, and fluctuations of 

environmental conditions may impact soft-bottom infaunal communities. Soft-bottom communities occur 

from the shoreline into the deep waters of the Gulf of Mexico. Storms can physically affect shallow 

bottom environments, causing an increase in sedimentation, burial of organisms by sediment, a rapid 

change in salinity or dissolved oxygen levels, storm surge scouring, remobilization of contaminants in the 

sediment, and abrasion and clogging of gills as a result of turbidity (Engle et al., 2008). Storms have also 

been shown to uproot benthic organisms from the sediment and suspend organisms in the water column 

(Dobbs and Vozarik, 1983). Large storms may devastate infaunal populations; for example, 2 months 

after Hurricane Katrina a significant decrease in the number of species, species diversity, and species 

density occurred in coastal waters off Louisiana, Mississippi, and Alabama (Engle et al., 2008). Such 

impacts may be devastating to a benthic community. 

Hypoxic conditions of inconsistent intensities and ranges also occur annually in a band that stretches 

along the Louisiana-Texas shelf each summer (Rabalais et al., 2002). The dissolved oxygen levels in the 

Gulf of Mexico hypoxic zone are less than 2 parts per million (ppm). Such low concentrations are lethal 

to many benthic organisms and may result in the loss of some benthic populations. Recolonization of 

devastated areas by populations from unaffected neighboring soft-bottom substrate would be expected to 

occur within a relatively short period of time (Dubois et al., 2009; Thistle, 1981). 

Recreational boating, fishing, and import tankering may have limited impact on soft-bottom 

communities. Ships anchoring near major shipping fairways of the CPA or recreational fishing boats 

setting anchor would impact bottom habitats. Anchor placement may crush and eliminate infauna in the 

footprint of the anchor. 

Damage resulting from commercial fishing, especially bottom trawling, may have a severe impact on 

soft-bottom benthic communities. Bottom trawling in the Gulf of Mexico primarily targets shrimp from 

nearshore waters to depths of approximately 90 m (295 ft) (NRC, 2002), which are the depths where the 

greatest trawling impacts are anticipated. Studies have indicated that trawled seafloor has reduced species 

diversity compared with untrawled seafloor (McConnaughey et al., 2000). Trawl trails may scour 

sediment, killing infauna, and epifaunal organisms may be physically removed (Engel and Kvitek, 1998). 

Trawling also contributes regularly to turbidity, as nets drag the seafloor, leaving trails of suspended 

sediment. Repetitive disturbance by trawling activity may lead to a community dominated by 

opportunistic species (Engel and Kvitek, 1998). Recovery from the passing of a trawl net would begin to 

occur with the following reproduction cycle of surrounding benthic communities (Rhodes and Germano, 

1982), but populations may be severely impacted by repetitive trawling activity (Engel and Kvitek, 1998). 

Structure placement and anchor damage from support boats and ships, floating drilling units, and 

pipeline-laying vessels are oil and gas OCS-related threats that disturb areas of the seafloor. The size of 

the areas affected by chains associated with anchors and pipeline-laying barges would depend on the 

water depth, chain length, sizes of anchor and chain, method of placement, wind, and current (Lissner et 

al., 1991). Anchor damage could result in the crushing and smothering of infauna. Anchoring often 

destroys a wide swath of habitat by being dragged over the seafloor or by the vessel swinging at anchor, 

causing the anchor chain to drag over the seafloor (Lissner et al., 1991). Damage to infauna as a result of 

anchoring may take approximately 1 year to recover, depending on the reproductive cycle and 

immigration of surrounding communities (Rhodes and Germano, 1982). 

Both explosive and nonexplosive structure-removal operations disturb the seafloor; however, they are 

not expected to affect soft-bottom communities because many sessile benthic organisms are known to 

resist the concussive force of structure-removal-type blasts (O’Keeffe and Young, 1984). O’Keeffe and 

Young (1984) also noted “. . . no damage to other invertebrates such as sea anemones, polychaete worms, 

isopods, and amphipods.” Impacts to invertebrates are anticipated to be minimal as they do not have air 

bladders inside their bodies that may burst with explosions, as some fish do (Schroeder and Love, 2004). 
4-380 Central Planning Area Supplemental EIS 

Routine discharges of drilling muds and cuttings by oil and gas operations could affect biological 

communities and organisms through a variety of mechanisms, including the smothering of organisms 

through deposition or less obvious sublethal toxic effects (impacts to growth and reproduction). 

Smothering of infauna by drilling discharges may be one of the greatest impacts to localized communities 

near a well, especially one that has shunted its cuttings to the seafloor to protect surrounding sensitive 

features. The heaviest concentrations of well cuttings and drilling fluids, for both water-based and 

synthetic-based drilling muds, have been reported within 100 m (328 ft) of wells and are shown to 

decrease beyond that distance (CSA, 2004b; Kennicutt et al., 1996). Although impacts are locally drastic, 

cumulative impacts over the seafloor of the Gulf of Mexico are anticipated to be very small, as such 

comparatively small areas are affected. 

Produced waters from petroleum operations are not likely to have a great impact on soft-bottom 

communities. Produced waters are rapidly diluted and impacts are generally only observed within 

proximity of the discharge point, and acute toxicity that may result from produced waters occurs “within 

the immediate mixing zone around a production platform” (Gittings et al., 1992b; Holdway, 2002). There 

have been no reported impacts to marine organisms or sediment contamination beyond 100 m (328 ft) of 

the produced-water discharge (Neff and Sauer, 1991; Trefry et al., 1995). Therefore, impacts to infauna 

are anticipated to be localized and only affect a small portion of the entire seafloor of the Gulf of Mexico. 

Traditional pipeline-laying barges (as opposed to dynamically positioned barges) affect more seafloor 

than other anchoring impacts. These barges typically use an array of 8-12 anchors weighing about 

4,500 kg (10,000 lb) each. While the large anchors crush organisms in their footprint, a much larger area 

is affected by anchor cable sweep as the barge is pulled forward to lay the pipeline by reeling-in forward 

cables and reeling-out aft cables. The anchors are reset repeatedly to forward positions to allow the barge 

to “crawl” forward. In this way, the anchor sweep scours parallel paths on each side of the vessel where 

the cables touch the seafloor. The width of the scoured paths varies with water depth (deeper water 

equals longer cables) and may be as much as 1,500 m (5,000 ft) to each side (only a portion of the cable 

adjacent to the anchor touches the seafloor). Another major impact of the process is pipeline burial. In 

waters 60 m (200 ft), burial of pipelines is required. This involves trenching up to 3.3 m (10 ft) deep in 

the seafloor from a water depth of 60 m (200 ft) to shore. This is a severe disturbance of the trenched 

area and creates a large turbidity plume. Resuspended sediments can cause obstruction of filter-feeding 

mechanisms of sedentary organisms and gills of fishes. Adverse impacts from resuspended sediments 

would be temporary, primarily sublethal in nature, and the effects would be limited to areas in the vicinity 

of the barge. Impacts may include “changes in respiration rate, abrasion and puncturing of structures, 

reduced feeding, reduced water filtration rates, smothering, delayed or reduced hatching of eggs, reduced 

larval growth or development, abnormal larval development, or reduced response to physical stimulus” 

(Anchor Environmental CA. L.P., 2003). 

Surface oil slicks released offshore can be moved toward shore by winds, but oil mixed into the water 

column is moved by water currents, which do not generally travel toward shore (Pond and Pickard, 1983). 

Surface oil spills and dispersed oil released from tankers may impact shallow, nearshore benthic 

communities. Disturbance of the sea surface by storms can mix surface oil 10-20 m (33-66 ft) into the 

water column (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002). This may result 

in direct oil contact for shallow nearshore benthic communities. Direct oiling or exposure to water 

soluble fractions of oil may result in lethal impacts to organisms (Suchanek, 1993; Beiras and SacoÁlvarez, 2006; Byrne, 1989) or impaired embryonic development (Byrne and Calder, 1977; Nicol et al., 

1977; Vashchenko, 1980). Benthic communities farther offshore, in deeper water, would be protected 

from direct physical contact of surface oil by depth below the sea surface. Any dispersed surface oil from 

a tanker or rig spill that may reach the benthic communities on the seafloor of the Gulf of Mexico at a 

depth greater than 10 m (33 ft) would be expected to be at very low concentrations (<1 ppm) (McAuliffe 

et al., 1981a and 1981b; Lewis and Aurand, 1997). Such concentrations may not be life threatening to 

adult stages, but they may harm larval or embryonic life stages of benthic organisms (Fucik et al., 1995; 

Suchanek, 1993; Beiras and Saco-Álvarez, 2006; Byrne, 1989). 

Potential blowouts may impact the biota of the soft-bottom benthic communities. If any blowouts 

from wells occur, the suspended sediments should settle out of the water column fairly quickly, locally 

smothering benthic organisms near the well. Any oil that becomes entrained in a subsurface plume would 

be dispersed as it travels in the water column (Vandermuelen, 1982; Tkalich and Chan, 2002). Subsea oil 

plumes near the seafloor would pass over smooth soft bottom, continuing the processes of diffusion and 
Description of the Environment and Impact Analysis 4-381 

biodegradation. These plumes would continue to be dispersed over a wide area in low concentrations 

with sublethal to immeasurable effect. If concentrated oil were to contact the soft-bottom communities 

directly, the impacts may include lethal effects with loss of habitat and biodiversity, contamination of 

substrate, change in community structure, and failed reproductive success. Damage to infauna as a result 

of subsurface plume exposure may take approximately 1 year to recover, depending on the reproductive 

cycle and immigration of surrounding communities (Rhodes and Germano, 1982). A recent report 

documents damage to a deepwater coral community 7 mi (11 km) southwest of the blowout. Soft 

bottoms in this area likely received oil also, but they would not be expected to catch as much oil as the 

benthic communities with greater relief above the seafloor (USDOI, BOEMRE, 2010j). 

It was estimated that 26 percent of the released oil from the DWH event remains in the environment 

as oil on or just below the water surface as a light sheen or tarballs, oil that was washed ashore or 

collected from the shore, and oil that is in the sediments (Lubchenco et al., 2010). This residual oil has 

been degrading over time. The greatest concentrations are expected to be near the wellhead and to 

decrease with distance from the source. Evidence shows that gas and oil from the DWH event in the 

water column has rapidly deteriorated (Hazen et al., 2010). 

The cumulative impact to soft bottoms of possible future oil spills, along with the DWH event, is 

anticipated to be small. The limited data currently available on the impacts of the DWH event make it 

difficult to define impacts to the soft-bottom communities in the CPA. It appears some impacts have 

occurred to corals within 7 mi (11 km) of the well, and it is anticipated that the soft-bottom communities 

in the area were impacted as well but with a lower impact because smooth, flat seafloor would allow the 

oil plume to pass unimpeded. Water column sampling, however, indicated that concentrations of total 

petroleum hydrocarbons in the water column were less than 0.5 ppm, 40 and 45 nmi (74 and 83 km; 

46 and 52 mi) northeast of the well (Haddad and Murawski, 2010). Therefore, the acute impacts of any 

large-scale blowout would likely be limited in scale and any additive impacts of several blowouts should 

have acute effects in only small areas, with possible sublethal impacts occurring over a larger area. 

However, the locally impacted seafloor would be very small compared with the overall size of the 

seafloor of the CPA (268,922 km2

; 103,831 mi2) and would not impact the overall infaunal population. 

Summary and Conclusion 

Non-OCS activities that may occur on soft-bottom benthic substrate include recreational boating and 

fishing, import tankering, and natural events such as extreme weather conditions, and extreme 

fluctuations of environmental conditions. These activities could cause temporary damage to soft-bottom 

communities. Ships and fishermen anchoring on soft bottoms may crush and smother underlying 

organisms. During severe storms, such as hurricanes, large waves may stir bottom sediments, which 

cause scouring, remobilization of contaminants in the sediment, abrasion and clogging of gills as a result 

of turbidity, uprooting benthic organisms from the sediment, and an overall result in decreased species 

diversity (Engle et al., 2008; Dobbs and Vozarik, 1983). Yearly hypoxic events may eliminate many 

species from benthic populations over a wide area covering most of the CPA and part of the WPA 

continental shelf (Rabalais et al., 2002). 

Impacts from routine activities of OCS oil and gas operations include anchoring, structure 

emplacement and removal, pipeline emplacement, drilling discharges, and discharges of produced waters. 

In addition, accidental subsea oil spills or blowouts associated with OCS activities can cause damage to 

infaunal communities. Long-term OCS activities are not expected to adversely impact the entire softbottom environment because the local impacted areas are extremely small compared with the entire 

seafloor of the Gulf of Mexico. 

Impacts from blowouts, pipeline emplacement, muds and cuttings discharges, other operational 

discharges, and structure removals may have local devastating impacts but the cumulative effect on the 

overall seafloor and infaunal communities on the Gulf of Mexico would be very small. Soft-bottom 

benthic communities are ubiquitous throughout and often remain in an early successional stage due to 

natural fluctuation, and therefore, the activities of OCS production of oil and gas would not cause 

additional severe cumulative impacts. 

The incremental contribution of the proposed action to the cumulative impact is expected to be slight, 

with possible impacts from physical disturbance of the bottom, discharges of drilling muds and cuttings, 

other OCS discharges, structure removals, and oil spills. Negative impacts, however, are small compared 
4-382 Central Planning Area Supplemental EIS 

with the overall size and ubiquitous composition of the soft-bottom benthic communities in the Gulf of 

Mexico. 

4.1.1.22.2. Diamondback Terrapins 

A description of diamondback terrapins as a resource has not been included in previous NEPA 

evaluations conducted by the BOEMRE Gulf of Mexico Region. Therefore, there is no prior discussion 

in the Multisale EIS or the 2009-2012 Supplemental EIS upon which to tier this information. 

4.1.1.22.2.1. Description of the Affected Environment 

Diamondback terrapins occur in 16 states along the Atlantic and Gulf Coasts; the coastline of Florida 

represents approximately 20 percent of their entire range (Butler et al., 2006). The one subspecies of 

terrapin that occurs in the CPA and that is a Federal species of concern is the Mississippi diamondback 

terrapin (Malaclemys terrapin pileata). The Mississippi diamondback terrapin (listed November 15, 

1994) has a range that includes Louisiana, Mississippi, Alabama, Georgia, and Florida (USDOI, FWS, 

2010b). 

Terrapins inhabit brackish waters including coastal marshes, tidal flats, creeks, and lagoons behind 

barrier beaches (Hogan, 2003). Juveniles spend the first years of their life under mats of tidal wrack and 

flotsam. Terrapins meet the osmotic challenges of a saline environment with several behavioral, 

physiological, and anatomical adaptations (U.S. Dept. of the Army, COE, 2002b). Their diet consists of 

fish, snails, worms, clams, crabs, and marsh plants (Cagle, 1952). 

Female Florida terrapins on the east coast reach sexual maturity at a plastron length of 135 mm (5 in) 

or 4-5 years of age; male Florida terrapins mature at 95 mm (4 in) about age 2-3 years (Butler et al., 

2006). Reproductive activities vary throughout the terrapin range. Courtship and mating occur in March 

and April, and the nesting season extends through July (U.S. Dept. of the Army, COE, 2002b). Terrapins 

nest on dunes, beaches, sandy edges of marshes, islands, and dike roads (Roosenburg, 1994). The 

common factor for proper egg development is sandy soil, which does not clog eggshell pores, thus 

allowing sufficient gas exchange between the developing embryo and the environment (Roosenburg, 

1994). Nesting occurs primarily in the daytime during high tide on high sand dunes with gentle slopes 

and minimal vegetation (Burger, 1977). Clutch size ranges from 4 to 22 eggs, and incubation time ranges 

from 61 to 104 days (Butler et al., 2006; Burger, 1977). Female terrapins may nest 2-3 times in the same 

nesting season. Gender determination is temperature-dependent. Hatching occurs from August through 

October in northern populations (Burger, 1977). 

Severely depleted by commercial harvest for food a century ago, diamondback terrapins are currently 

threatened by drowning in crab pots, development of shoreline habitats and nesting beaches, predation of 

nests and adults, boat strikes, and road mortality (Butler et al., 2006). Spending most of their lives at the 

aquatic-terrestrial boundary in estuaries, terrapins are susceptible to habitat destruction from cleanup 

efforts, as well as direct catastrophic oil contact; however, most impacts cannot be quantified at this time. 

Tropical storms, hurricanes, and beach erosion threaten their preferred nesting habitats. The actual 

impacts of these storms on the animals in the Gulf and the listed species have not yet been determined 

and, for the most part, may remain very difficult to quantify. However, some impacts, such as loss of 

beach habitat, are known to have occurred and would impact terrapin populations that would have used 

those areas for nesting beaches. 

The DWH event and associated oil spill has impacted the turtle community in the GOM. Impacts can 

be either direct (mortality or injury) or indirect (e.g., reduced prey availability); however, most impacts 

cannot be quantified at this time. The Deepwater Horizon Unified Command reports daily fish and 

wildlife collection reports that include turtles; this can be found at http://www.restorethegulf.gov/. 

As of October 14, 2010, two other reptiles have been collected alive and one has been collected dead 

(RestoreTheGulf.gov, 2010f). As data continue to be gathered and impact assessments completed, a 

better characterization of the full scope of impacts to the terrapin populations in the GOM from the DWH 

event will be available. 
Description of the Environment and Impact Analysis 4-383 

4.1.1.22.2.2. Impacts of Routine Events 

Background/Introduction 

The major impact-producing factors resulting from the routine activities associated with the CPA 

proposed action that may affect the Mississippi diamondback terrapin (Malaclemys terrapin pileata) 

include beach trash and debris and efforts undertaken for the removal of marine debris or for beach 

restoration. 

Proposed Action Analysis 

Mississippi diamondback terrapins spend most of their lives at the aquatic-terrestrial boundary in 

estuaries. Terrapins are susceptible to habitat destruction from cleanup efforts; however, most impacts 

cannot be quantified at this time. Nests can also be disturbed or destroyed by cleanup efforts. 

Habitat destruction, road construction, and drowning in crab traps are the most recent threats to 

diamondback terrapins. In the 1800’s, populations declined due to overharvesting for meat (Hogan, 

2003). Tropical storms, hurricanes, and beach erosion threaten their preferred nesting habitats. 

Destruction of the remaining habitat due to response efforts could drastically affect future population 

levels and reproduction. Characteristics of terrapin life history render this species especially vulnerable to 

overfishing and habitat loss. These characteristics include low reproductive rates, low survivorship, 

limited population movements, and nest site philopatry. 

The major routine impact-producing factors associated with the CPA proposed action that may affect 

terrapins include beach trash and debris and efforts undertaken for the removal of marine debris or for 

beach restoration. Terrapins may mistakenly consume trash and debris or may become entangled in 

debris. The proposed action is expected to contribute negligible marine debris or disruption to terrapin 

habitat. Unless properly regulated, personnel removing marine debris may temporarily disturb terrapins 

or trample nesting sites. Due to the extended distance from shore, impacts associated with activities 

occurring in the OCS are not expected to impact terrapins or their habitat. 

Little or no damage is expected to the physical integrity, species diversity, or biological productivity 

of terrapin habitat as a result of the CPA proposed action. 

Summary and Conclusion 

Impacts from routine activities resulting from the CPA proposed action are possible but unlikely. 

Because of the greatly improved handling of waste and trash by industry and the annual awareness 

training required by the marine debris mitigations, the amount of plastics in the ocean is decreasing, thus 

minimizing the devastating effects on offshore and coastal marine life. The routine activities of the CPA 

proposed action are unlikely to have significant adverse effects on the size and recovery of any terrapin 

species or population in the GOM. 

4.1.1.22.2.3. Impacts of Accidental Events 

Background/Introduction 

The major impact-producing factors resulting from the accidental activities associated with the CPA 

proposed action that may affect the Mississippi diamondback terrapin (Malaclemys terrapin pileata) 

include offshore and coastal oil spills and spill-response activities. 

Proposed Action Analysis 

Spending most of their lives at the aquatic-terrestrial boundary in estuaries, terrapins are susceptible 

to habitat destruction from cleanup efforts, as well as direct catastrophic oil contact; however, most 

impacts cannot be quantified at this time. Even after the oil is no longer visible, terrapins may still be 

exposed while they forage in the salt marshes lining the edges of estuaries where oil may have 

accumulated under the sediments and within the food chain. Nests can also be disturbed or destroyed by 

cleanup efforts. Chronic (longer-term lethal or sublethal oil-related injuries) effects from oil contact may 

persist through the generations, potentially reducing population levels. 
4-384 Central Planning Area Supplemental EIS 

Habitat destruction, road construction, and drowning in crab traps are the most recent threats to 

diamondback terrapins. In the 1800’s, populations declined due to overharvesting for meat (Hogan, 

2003). Tropical storms, hurricanes, and beach erosion threaten their preferred nesting habitats. 

Destruction of the remaining habitat due to a catastrophic spill and response efforts could drastically 

affect future population levels and reproduction. Characteristics of terrapin life history render this species 

especially vulnerable to overfishing and habitat loss. These characteristics include low reproductive rates, 

low survivorship, limited population movements, and nest site philopatry. 

The DWH event and associated oil spill has impacted the turtle community in the GOM. Impacts can 

be either direct (mortality or injury) or indirect (e.g., reduced prey availability); however, most impacts 

cannot be quantified at this time. The best available information does not provide a complete 

understanding of the effects of the spilled oil and active response/cleanup activities on the affected marine 

mammal environment. The Deepwater Horizon Unified Command reports daily fish and wildlife 

collection reports that include turtles; this can be found at http://www.restorethegulf.gov/. 

Summary and Conclusion 

Habitat destruction, road construction, and drowning in crab traps are the most recent threats to 

diamondback terrapins. In the 1800’s, populations declined due to overharvesting for meat (Hogan, 

2003). Tropical storms, hurricanes, and beach erosion threaten their preferred nesting habitats. 

Destruction of the remaining habitat due to a catastrophic spill and response efforts could drastically 

affect future population levels and reproduction. However, there is not expected to be a significant 

increase to infrastructure, and the probability of a spill large enough to impact the diamondback terrapins 

or their habitat is low with the CPA proposed action. 

No substantial information was found at this time that would alter the overall conclusion that 

accidental impacts on diamondback terrapins associated with the CPA proposed action would be minimal. 

4.1.1.22.2.4. Cumulative Impacts 

Background/Introduction 

The major impact-producing factors resulting from the cumulative activities associated with the CPA 

proposed action that may affect the Mississippi diamondback terrapin (Malaclemys terrapin pileata) 

include oil spills and spill-response activities, alteration and reduction of habitat, predation and 

competition, and consumption of trash and debris. 

Proposed Action Analysis 

Most proposed action-related spills, as well as oil spills stemming from import tankering and prior 

and future lease sales, are not expected to contact terrapins or their habitats. Cumulative activities posing 

the greatest potential harm to terrapins are non-OCS factors (i.e., coastal spills) and natural catastrophes 

(i.e., hurricanes and tropical storms), which, in combination, could potentially deplete some terrapin 

populations to unsustainable levels. The expected incremental contribution of the CPA proposed action 

to the cumulative impacts is expected to be minimal. 

Spending most of their lives within their limited home ranges at the aquatic-terrestrial boundary in 

estuaries, terrapins are susceptible to habitat destruction from cleanup efforts, as well as direct 

catastrophic oil contact; however, most impacts cannot be quantified at this time. Even after the oil is no 

longer visible, terrapins may still be exposed while they forage in the salt marshes lining the edges of 

estuaries where oil may have accumulated under the sediments and within the food chain (Roosenburg et 

al., 1999). Nests can also be disturbed or destroyed by cleanup efforts. 

Tropical storms, hurricanes, and beach erosion threaten their preferred nesting habitats. Destruction 

of the remaining habitat due to response efforts could drastically affect future population levels and 

reproduction. Characteristics of terrapin life history render this species especially vulnerable to 

overfishing and habitat loss. These characteristics include low reproductive rates, low survivorship, 

limited population movements, and nest site philopatry. 

The DWH event and associated oil spill has impacted the turtle community in the GOM. Impacts can 

be either direct (mortality or injury) or indirect (e.g., reduced prey availability); however, most impacts 
Description of the Environment and Impact Analysis 4-385 

cannot be quantified at this time. The best available information does not provide a complete 

understanding of the effects of the spilled oil and active response/cleanup activities on the affected marine 

mammal environment. The Deepwater Horizon Unified Command reports daily fish and wildlife 

collection reports that include turtles; this can be found at http://www.restorethegulf.gov/. 

Summary and Conclusion 

The major impact-producing factors resulting from the cumulative activities associated with the CPA 

proposed action that may affect the diamondback terrapin include oil spills and spill-response activities, 

alteration and reduction of habitat, predation and competition, and consumption of trash and debris. Due 

to the extended distance from shore, impacts associated with activities occurring in the OCS are not 

expected to impact terrapins or their habitat. No substantial new information was found at this time that 

would alter the overall conclusion that cumulative impacts on diamondback terrapins associated with the 

CPA proposed action is expected to be minimal. 

4.1.2. Alternative B—The Proposed Action Excluding the Unleased Blocks Near 

Biologically Sensitive Topographic Features 

Description of the Alternative 

Alternative B differs from Alternative A (the proposed action) by not offering blocks that are possibly 

affected by the proposed Topographic Features Stipulation (Chapter 2.3.1.3.1; Figure 2-1). All of the 

assumptions (including the seven other potential mitigating measures) and estimates are the same as for 

the proposed action (Alternative A). A description of Alternative A is presented in Chapter 2.3.1.1. 

Effects of the Alternative 

The following analyses are based on the scenario for the CPA proposed action (Alternative A). The 

scenario provides assumptions and estimates on the amounts, locations, and timing for OCS exploration, 

development, and production operations and facilities, both offshore and onshore. These are estimates 

only and not predictions of what would happen as a result of holding the proposed lease sale. A detailed 

discussion of the scenario and related impact-producing factors is presented in Chapter 3.1. 

The analyses of impacts to the various resources under Alternative B are very similar to those for 

Alternative A. The reader should refer to the appropriate discussions under Alternative A for additional 

and more detailed information regarding impact-producing factors and their expected effects on the 

various resources. Impacts under Alternative B are expected to be the same as the proposed action in the 

CPA (Chapter 4.1) for the following resources: 

— Air Quality 

— Water Quality 

— Coastal Barrier Beaches and Associated 

 Dunes 

— Wetlands 

— Seagrass 

— Live Bottoms (Pinnacle Trend and 

 Low Relief) 

— Sargassum 

— Chemosynthetic and Nonchemosynthetic 

 Deepwater Benthic Communities 

— Marine Mammals 

— Sea Turtles 

— Alabama, Choctawhatchee, St. Andrew 

 and Perdido Key Beach Mice 

— Coastal and Marine Birds 

— Gulf Sturgeon 

— Fish Resources and Essential Fish 

 Habitat 

— Commercial Fishing 

— Recreational Fishing 

— Recreational Resources 

— Archaeological Resources 

— Human Resources and Land Use 

— Soft Bottoms 

— Diamondback Terrapins 

The impacts to some Gulf of Mexico resources under Alternative B would be different from the 

impacts expected under the proposed action. These impacts are described below. 
4-386 Central Planning Area Supplemental EIS 

Impacts on Topographic Features 

The sources and severity of impacts associated with this alternative are those sale-related activities 

discussed for the proposed action. The potential impact-producing factors to the topographic features of 

the CPA are anchoring and structure emplacement, effluent discharge, blowouts, oil spills, and structure 

removal. A more detailed discussion of these potential impact-producing factors is presented in 

Chapter 3.

Of the 16 topographic features of the CPA, 15 are located within water depths less than 200 m 

(656 ft). Geyer Bank is located in water depths of 190-210 m (623-689 ft). These features occupy a very 

small portion of the entire area. Of the potential impact-producing factors that may affect the topographic 

features, anchoring, structure emplacement, and structure removal would be eliminated by the adoption of 

this alternative. Effluent discharge and blowouts would not be a threat to the topographic features 

because blocks near enough to the banks for these events to have an impact on the biota of the banks 

would have been excluded from leasing under this alternative. Thus, the only impact-producing factor 

remaining from operations in blocks included in this alternative (i.e., those blocks not excluded by this 

alternative) is an oil spill. The potential impacts from oil spills are summarized below and are discussed 

further in Chapter 3.2.1. 

A subsurface spill would have to come into contact with a biologically sensitive feature to have an 

impact. A subsurface spill is expected to rise to the surface, and any oil remaining at depth would be 

swept clear of the banks by currents moving around the banks (Rezak et al., 1983). Deepwater subsurface 

spills may travel along the sea bottom or in the water column for some distance before rising to the 

surface. The fact that the topographic features are widely dispersed in the CPA, combined with the 

random nature of spill events, would serve to limit the likelihood of a spill occurring proximate to a 

topographic feature. Chapter 4.3.1.8 of the Multisale EIS discussed the risk of spills interacting with 

topographic features in more detail. The currents that move around the banks would likely steer any 

spilled oil around the banks rather than directly upon them, lessening impact severity. In the unlikely 

event that oil from a subsurface spill would reach the biota of a topographic feature, the effects would be 

primarily sublethal for most of the adult sessile biota. Lethal effects would probably be limited to a few 

coral colonies (CSA, 1992b and 1994). It is anticipated that recovery from a mostly sublethal exposure 

would occur within a period of 2 years. In the unlikely event that oil from a subsurface spill contacted a 

coral-covered area, the areal extent of coral mortality would be limited, but long-lasting sublethal effects 

may be incurred by organisms surviving the initial effects of a spill (Jackson et al., 1989). Indeed, the 

stress resulting from the oiling of reef coral colonies could affect their resilience to natural disturbances 

(e.g., elevated water temperature and diseases) and may hamper their ability to reproduce. A complete 

recovery of such an affected area could take in excess of 10 years. 

Cumulative Impacts 

With the exception of the topographic features, the cumulative impacts of Alternative B on the 

environmental and socioeconomic resources of the Gulf of Mexico would be identical to Alternative A. 

The incremental contribution of the proposed action to the cumulative impacts on topographic features is 

expected to be slight, and negative impacts should be restricted by the implementation of the Topographic 

Features Stipulation and site-specific mitigations, the depths of the features, and water currents in the 

topographic feature area. 

Summary and Conclusion 

Alternative B, if adopted, would prevent any oil and gas activity whatsoever in the blocks containing 

topographic features; thus, it would eliminate any potential direct impacts to the biota of those blocks 

from oil and gas activities, which otherwise would be conducted within the blocks. In the unlikely event 

that oil from a subsurface spill contacts the biota of a topographic feature, the effects would be localized 

and primarily sublethal for most of the adult sessile biota. Some lethal effects would probably occur upon 

oil contact to coral colonies. 
Description of the Environment and Impact Analysis 4-387 

4.1.3. Alternative C—The Proposed Action Excluding Unleased Blocks within 

15 Miles of the Baldwin County, Alabama, Coast 

Description of the Alternative 

Alternative C differs from Alternative A (the proposed action) by not offering any unleased blocks 

within 15 mi (24 km) of the Baldwin County, Alabama, coast. All the assumptions (including potential 

mitigating measures) and estimates are the same as those under Alternative A (Chapters 2.3.1.). A 

description of Alternative A is presented in Chapter 2.3.1.1. 

Effects of the Alternative 

The following analyses are based on the scenario for the CPA proposed action (Alternative A). A 

detailed discussion of the scenario and related impact-producing factors is present in Chapter 3.

The analyses of impacts to the various resources under Alternative C are very similar to those for 

Alternative A. The reader should refer to the appropriate discussions under Alternative A for additional 

and more detailed information regarding impact-producing factors and their effects on the various 

resources. Impacts are expected to be the same as those estimated under the proposed action in the CPA 

(Chapter 4.1) for the following resources: 

— Air Quality 

— Coastal Barrier Beaches and Associated 

 Dunes 

— Wetlands 

— Seagrass 

— Live Bottoms (Pinnacle Trend and 

 Low Relief) 

— Topographic Features 

— Sargassum 

— Chemosynthetic and Nonchemosynthetic 

 Deepwater Benthic Communities 

— Marine Mammals 

— Sea Turtles 

— Alabama, Choctawhatchee, St. Andrew, 

 and Perdido Key Beach Mice 

— Coastal and Marine Birds 

— Gulf Sturgeon 

— Fish Resources and Essential Fish 

 Habitat 

— Commercial Fishing 

— Recreational Fishing 

— Human Resources and Land Use 

— Soft Bottoms 

— Diamondback Terrapins 

Impacts to some Gulf of Mexico resources would be different from the impacts of the proposed 

action. These impacts are described below. 

Impacts on Water Quality 

Bottom-area disturbance resulting from platform emplacement and removal, drilling activities, and 

blowouts results in some level of increased water-column turbidity in overlying offshore waters. 

Generally, each of these operations has been shown to produce localized, temporary impacts on water 

quality conditions in the immediate vicinity of the emplacement operation (Chapters 3.1 and 3.2). 

Alternative C would eliminate impacts associated with platform emplacement in the areas within 15 mi 

(24 km) of the coast of Baldwin County, Alabama. 

The oil-spill events related to the proposed action under Alternative A were projected to be mostly 

very small events, to be very infrequent for spills greater than 50 bbl, to have effects for only a shortduration (from a few days to 3 months), and to affect only a small area of offshore waters at any one time 

(Chapter 4.3.1 of the Multisale EIS). These events would not be eliminated as a result of Alternative C. 

The risk of spills due to exploration and development would be eliminated within the deferral area. 

Impacts on Archaeological Resources 

As a result of the CPA proposed action, Federal waters offshore Alabama were assumed to have new 

exploration, delineation, and development wells drilled. There would be platform installations and 

pipelines laid in the area. The location of any proposed activity within a lease block that has a high 

potential for historic shipwrecks requires archaeological clearance prior to operations. The probability of 
4-388 Central Planning Area Supplemental EIS 

an OCS activity contacting and damaging a shipwreck is low; the required clearance measures are 

considered to be 90 percent effective at protecting potential unknown historic shipwrecks. If an OCS 

structure did contact a historic resource, unique archaeological information contained within a site or 

resource could be lost. Under Alternative C, drilling activities and installation of platforms within 15 mi 

(24 km) of the shoreline of Baldwin County, Alabama, would not occur. Any potential impacts from 

drilling activities or platform emplacement to historic shipwrecks would be eliminated in OCS blocks 

within 15 mi (24 km) of the Baldwin County shoreline. 

Impacts on Recreational Resources 

The major impact-producing factors that could potentially affect recreational beaches include the 

presence of offshore structures, pipelaying activities, support helicopter and vessel traffic, trash and 

debris, and oil spills. Exploratory rig activity and platforms associated with OCS development activity 

could be viewed from coastal communities along the Gulf of Mexico when they are closer than 

approximately 10 mi (16 km) from shore; beyond that, structures appear very small and barely 

discernable to the naked eye, eventually disappearing from view. Alternative C would exclude those 

blocks within 15 mi (24 km) of the shoreline from leasing. No OCS structures would be constructed 

within the excluded area. Any visual impact due to OCS structures in the area off Baldwin County, 

Alabama, would be eliminated. Pipelaying activities, support helicopter and vessel traffic, trash and 

debris, and oil spills from the remaining areas offered from lease would continue to present potential 

impacts to recreational beaches. 

Cumulative Impacts 

With the exception of the water quality, archaeological resources, and recreational resources, the 

cumulative impacts of Alternative C on the environmental and socioeconomic resources of the Gulf of 

Mexico would be identical to Alternative A. The incremental contribution to cumulative impacts on 

water quality, archaeological resources, and recreational resources within 15 mi (24 km) of the Baldwin 

County coast would be reduced or eliminated. 

Summary and Conclusion 

Alternative C, if adopted, prevent any oil and gas activity whatsoever in the blocks within 15 miles of 

Baldwin County, Alabama coast thus, it would eliminate any potential direct impacts to the biota of those 

blocks from oil and gas activities, which otherwise would be conducted within the blocks. Bottom 

disturbances from platform emplacements and removals, drilling activities, and blowouts would not occur 

within the excluded area under Alternative C. Therefore, localized, temporary impacts to water quality 

due to sediment resuspension would be eliminated in the area within 15 mi (24 km) of the Baldwin 

County coast. Additionally, the risk of oil-spill impacts would be slightly reduced as exploration and 

development operations would not occur in the excluded area. 

The probability of an OCS activity contacting and damaging a shipwreck is low because of existing 

mitigation in the form of archaeological clearance requirements for proposed activities. Alternative C 

would eliminate the potential for impacts from drilling or platform emplacement to historic 

archaeological resources within the area excluded under Alternative C. 

Since no OCS structures would be constructed under Alternative C in the excluded blocks, any visual 

impact due to OCS structures in the area off Baldwin County would be eliminated. 

4.1.4. Alternative D—No Action 

Description of the Alternative 

Alternative D is equivalent to cancellation of a lease sale scheduled for a specific period in the Final 

Proposed Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012. By canceling the 

proposed lease sale, the opportunity is postponed for development of the estimated 0.801-1.624 BBO and 

3.332-6.560 Tcf of gas, some of which may be foregone. Any potential environmental and 
Description of the Environment and Impact Analysis 4-389 

socioeconomic impacts resulting from the proposed lease sale (Chapter 4.1.1, Alternative A—The 

Proposed Action) would be postponed or not occur. 

Effects of the Alternative 

Under Alternative D, DOI cancels the proposed CPA lease sale. Therefore, the discovery and 

development of oil and gas expected from a lease sale would be delayed and a portion may not occur. 

The environmental and socioeconomic effects of Alternative A (the proposed action) also would be 

delayed or not occur. 

This Agency recently published a report that examined previous exploration and development activity 

scenarios (USDOI, MMS, 2007e). The Agency compared forecasted activity with the actual activity from 

14 WPA and 14 CPA lease sales. 

The report shows that many lease sales contribute to the present level of OCS activity, and any single 

lease sale accounts for only a small percentage of the total OCS activities. In 2006, leases from 92 

different sales contributed to Gulf of Mexico production, while an average CPA lease sale contributed to 

2 percent of oil production and 2 percent of gas production in the CPA. In 2006, leases from 15 different 

sales contributed to the installation of production structures in the Gulf of Mexico, while an average CPA 

lease sale contributed to 6 percent of the installation of production structures in the CPA. In 2006, leases 

from 70 different sales contributed to wells drilled in the Gulf of Mexico, while an average CPA lease 

sale contributed to 4 percent of wells drilled in the CPA. 

Like past lease sales, the proposed CPA lease sale would contribute to maintaining the present level 

of OCS activity in the Gulf of Mexico. Exploration and development activity, including service-vessel 

trips, helicopter trips, and construction, that would result from the proposed lease sale would replace 

activity resulting from existing leases that have reached, or are near the end of, their economic life. 

Environmental Impacts 

If the proposed lease sale would be canceled, the resulting development of oil and gas would most 

likely be postponed to a future sale; therefore, the overall level of OCS activity in the CPA would only be 

reduced by a small percentage, if any. Therefore, the cancellation of one lease sale would not 

significantly change the environmental impacts of overall OCS activity. 

Economic Impacts 

A sudden change in policy that restricts access to oil and gas resources or that alters the timetables the 

offshore industry has come to depend on when making their investment decisions may lead to undesirable 

socioeconomic disruptions in local coastal economies (USDOI, MMS, 2007e). Since 1983, this Agency 

has scheduled and held annual areawide lease sales in the Gulf of Mexico, canceling only one lease sale. 

In October 2006, this Agency and the State of Louisiana reached a settlement on the lawsuit filed by the 

State challenging WPA Lease Sale 200. As part of this settlement, this Agency canceled CPA Lease Sale 

201, scheduled for March 2007. However, the acreage was offered 7 months later in CPA Lease Sale 205 

(October 2007). This Agency canceled WPA Lease Sale 215 in July 2010 after the Deepwater Horizon

event. Direct economic impacts are occurring from the cancellation of WPA Lease Sale 215; however, 

there are limitations to BOEMRE’s awareness for what business decisions industry has made or intends to 

make that are the result of the cancellation of WPA Lease Sale 215, let alone the consequences of 

selecting Alternative D to cancel a CPA lease sale. 

The cancellation of a lease sale may have economic impacts on an industry that has planned their 

investments according to annual lease sales in the Gulf of Mexico. Smaller independent companies 

would have fewer alternative projects available in their investment portfolios, and thus would be more 

affected by the cancellation of the lease sale. Therefore, they would have a more difficult time than major 

companies replacing lost production capacity. The magnitude and length of economic impacts on 

industry would be dependent on individual firm characteristics, global trends, and the number of lease 

sales canceled or delayed. 

Canceling the lease sale would result in delaying the subsequent development activities that would 

take place. Revenues collected by the Federal Government (and thus revenue disbursements to the States) 

would be adversely affected by such a delay due to the “time value of money” (i.e., a dollar received in 
4-390 Central Planning Area Supplemental EIS 

the future is valued less than the same dollar received today because of the opportunity to earn interest). 

Canceling the lease sale would delay the receipt of interest on billions of dollars of bonus bids, rental 

income, and royalty income by the Federal treasury. 

Other Sources of Energy 

Other sources of energy may substitute for the delayed or lost production. Principal substitutes would 

be additional imports, conservation, additional domestic production, and switching to other fuels. These 

alternatives, except conservation, have their own significant negative environmental and socioeconomic 

impacts. 

Chapter 4.2.1.4 of the Multisale EIS briefly discusses the most likely alternative energy sources, the 

quantities expected to be needed, and the environmental and socioeconomic impacts associated with these 

alternative energy sources. The discussion is based on material from the following publications: Outer 

Continental Shelf Oil and Gas Leasing Program: 2007-2012 (USDOI, MMS, 2007a); Gulf of Mexico 

Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012, Final Environmental Impact 

Statement (USDOI, MMS, 2007c); and Energy Alternatives and the Environment (King, 2007). 

Summary and Conclusion 

If Alternative D is selected, all impacts, positive and negative, associated with the CPA proposed 

action discussed in Chapter 4 would be eliminated. The incremental contribution of the proposed action 

to cumulative effects would also be eliminated, but effects from other activities, including other OCS 

lease sales, would remain. 

If the lease sale would be canceled, the resulting oil and gas exploration and development activity 

would most likely be postponed to a future sale; therefore, the overall level of OCS activity in the CPA 

would only be reduced by a small percentage, if any. Therefore, the cancellation of the proposed lease 

sale would not significantly change the environmental impacts of overall OCS activity. The WPA Lease 

Sale 215 was canceled on July 28, 2010 (Federal Register, 2010g). The impact on oil and gas activity in 

the GOM of selecting Alternative D to cancel another lease sale is more problematic in forecasting the 

combined impact on industry levels of activity resulting from two canceled GOM lease sales. Direct 

economic impacts have undoubtedly already occurred from the cancellation of WPA Lease Sale 215; 

however, there are limitations to BOEMRE’s awareness for what business decisions industry has made or 

intends to make that are the result of the cancellation of WPA Lease Sale 215, let alone selecting 

Alternative D to cancel a CPA lease sale. 

As an oil province, so far the highest daily oil production rate in the GOM has been 1.73 million 

barrels/day (MMbbl/d) in June 2002 (The Oil Drum, 2009). On January 3, 2011, Casselman and Gilbert 

(2011a) reported that a slowed permitting process in the GOM has long-term implications for U.S. oil 

production. The DOE’s Energy Information Administration reported that domestic crude oil production 

in the U.S. in 2010 as 5.51 MMbbl/d. The DOE’s Energy Information Administration also reported that 

production in the GOM would decline 190,000 bbl/d in 2011 and 2012 (USDOE, Energy Information 

Administration, 2011b). The forecasted production declines in the GOM are partially offset by projected 

increases in the lower-48, non-GOM production of 220,000 bbl/d in 2011 and 70,000 bbl/d in 2012. The 

DOE’s Energy Information Administration also reported that a drop in GOM natural gas production in 

2011 and 2012 would be more than offset by increases in production in the lower 48 states (USDOE, 

Energy Information Administration, 2011b). The duration of the decline reported by DOE’s Energy 

Information Administration for GOM oil production is uncertain, as is the question of whether or not 

GOM oil production will return to pre-DWH event levels of approximately 1.6 MMbbl/d in 2009 

(USDOE, Energy Information Administration, 2010e). 

Some operators have been reported to be shifting investments out of the Gulf (Casselman and Gilbert, 

2011a). BP PLC recently said it would move a brand-new rig that was meant to work in the Gulf, Pride 

International Inc.’s Deep Ocean Ascension, to Libya. Marathon Oil Corp. has tried to cancel a contract 

for a newly built Gulf rig owned by Noble Corp. (Casselman and Gilbert, 2011a). When the new 

suspension of deepwater drilling was announced on July 12, 2010, by Secretary of the Interior Ken 

Salazar, some industry leaders predicted thousands of layoffs and a quick exodus of rigs from the Gulf. 

Instead, most companies either kept their rigs on stand-by or kept them busy with jobs that were not 
Description of the Environment and Impact Analysis 4-391 

covered by the suspension, such as decommissioning nonproducing equipment and plugging and 

abandoning nonproductive wells (Casselman and Gilbert, 2011a). 

There are signs that companies remain committed to the Gulf. On December 16, 2010, Chevron 

announced 2011 commitments to further develop discoveries at Big Foot, Jack/St. Malo, Tahiti-2, 

Perdido, and Buckskin. Gilbert (2011) reported that deepwater operators, such as Transocean Ltd., had 

12 of 13 deepwater rigs leased for work in the GOM. 

On January 3, 2011, Casselman and Gilbert (2011b) reported that the Obama Administration 

announced an agreement to clear a path for 13 companies drilling deepwater prospects at the time of the 

moratorium to renew drilling 16 of these projects. The plans controlling the drilling operations must be 

revised to comply with new safety regulations, but new environmental reviews under NEPA in most cases 

would not be required. 

Smaller oil companies that often work in shallower water, however, are less able to wait out a 

slowdown if paying high fixed costs for rigs that are idle because of longer permitting timeframes. On 

January 4, 2011, Gilbert (2011) reported that of the 83 shallow-water rigs in the Gulf, 29 were leased as 

of December 20, compared with 39 at the time of the DWH event. Among the hardest hit have been 

Hercules Offshore Inc. and Seahawk Drilling Inc., both of Houston, Texas. Gilbert (2011) contains a 

graphic showing GOM shallow-water operators and the number of rigs owned versus the number of rigs 

now leased. Some of these operators are going through layoffs, such as Hercules, which let go 2,000 

workers over the last 18 months (Gilbert, 2011). 

One condition to which operators pay close attention is uncertainty in access to new land offerings on 

the OCS or access to their current leases in the face of large capital costs under existing contracts that 

assumed work would proceed expeditiously. The outcomes of numerous Presidential and Secretarial 

inquiries following the DWH event (Appendix D and Table 2-1) are not yet totally known with respect 

to how recommendations could influence regulations. Since the October 14, 2010, release of the new 

safety regulations, industry and BOEMRE’s experience for the ramp-up time needed to understand and 

reach compliance with them has proven to be a work in progress. Both conditions, immediate new 

requirements and possible future unknown requirements, has lead to uncertainty. 

Alternative D, the cancellation of CPA Lease Sale 216/222, on top of already canceled WPA Lease 

Sale 215, would manifest further impacts. The magnitude would depend on the operating plans of 

individual companies that currently operate or hold leases in the GOM and that also operate in other areas 

of the world. The last CPA sale, Lease Sale 213, was held on March 17, 2010. The end of the current 

5-Year Program (2007-2012) is June 30, 2012. Cancellation of the last CPA lease sale in the 5-Year 

Program would cause operators to face the prospect of no new leasing in the CPA for 2 years at a 

minimum. 

Operators that have interests worldwide must balance their company resources against multiple, 

independent variables. Among these variables are future price forecasts, geologic basin (e.g., if it is gas 

prone or oil prone), quality of prospect inventory in each basin, the in-house maturation state of prospect 

inventories, partnering relationships with other operators or national oil companies, and in-country 

operator risk (e.g., if the country has a stable political environment and legal system to protect 

investment). The U.S. has been long regarded as a favorable operating environment because of a strong 

tradition for the rule of law, a stable political system, a tested leasing program with regular opportunities 

to secure access to land in lease sales, and a mature regulatory system for OCS operations. 

Alternative D, in combination with canceled WPA Lease Sale 215, could cause a company to 

reevaluate operator risk in rebalancing a worldwide portfolio of operating opportunities. If a company 

begins to view lease sale predictability as being in question or at least counter to longstanding experience 

in the GOM, it may decide to shift its attention and assets to other places in the world until new and 

predictable processes are developed and tested. Because contracts tend to be multiyear, a commitment of 

drilling rigs and other support services to operate in other geologic basins could extend from 2 to 5 years. 

Alternative D would also negatively affect revenues collected by the Federal Government and the 

revenue distributions to the States that are based on total revenue. 

Other sources of energy may partially substitute for the lost production. Principal substitutes would 

be additional imports, conservation, additional domestic production, and switching to other fuels. Except 

for conservation, these alternatives have negative environmental impacts of their own, some of which are 

significant. For example, increased tanker traffic in U.S. territorial waters carries with it the risk for 
4-392 Central Planning Area Supplemental EIS 

collisions and oil spills. The quantity spilled in tanker accidents or collisions could be large and take 

place instantaneously for the most part. 

4.2. UNAVOIDABLE ADVERSE IMPACTS OF THE PROPOSED ACTION

Unavoidable adverse impacts associated with the proposed action are expected to be primarily short 

term and localized in nature and are summarized below. All OCS activities involve temporary and 

exclusive use of relatively small areas of the OCS over the lifetimes of specific projects. Lifetimes for 

these activities can be days, as in the case of seismic surveys; or decades, as in the case of a production 

structure or platform. No activities in the OCS Program involve the permanent or temporary use or 

“taking” of large areas of OCS on a semicontinuous basis. Cumulatively, however, a multitude of 

individual projects results in a major use of OCS space. 

Sensitive Coastal Habitats: If an oil spill contacts beaches or barrier islands, the removal of beach 

sand during cleanup activities could result in adverse impacts if the sand is not replaced, and a beach 

could experience several years of tarballs washing ashore over time, causing an aesthetic impact. Sand 

borrowing on the OCS for coastal restorations involves the taking of a quantity of sand from the OCS and 

depositing it onshore, essentially moving small products of the deltaic system to another location. If sand 

is left where it is, it would eventually be lost to the deltaic system by redeposition or burial by younger 

sediments; if transported onshore, it would be lost to burial and submergence caused by subsidence and 

sea-level rise. 

If an oil spill contacts coastal wetlands, adverse impacts could be high in localized areas. In more 

heavily oiled areas, wetland vegetation could experience suppressed productivity for several years; in 

more lightly oiled areas, wetland vegetation could experience die-back for one season. Epibionts on 

wetland vegetation and grasses in the tidal zone could be killed, and the productivity of tidal marshes for 

the vertebrates and invertebrates that use them to spawn and develop could be impaired. Much of the 

wetland vegetation would recover over time, but some wetland areas could be converted to open water. 

Some unavoidable impacts could occur during pipeline and other related coastal construction, but 

regulations are in place to avoid and minimize these impacts to the maximum extent practicable. 

Unavoidable impacts resulting from dredging, wake erosion, and other secondary impacts related to 

channel use and maintenance would occur as a result of the proposed action. 

Sensitive Coastal and Offshore Biological Habitats: Unavoidable adverse impacts would take place 

if an oil spill occurred and contacted sensitive coastal and offshore biological habitats, such as Sargassum 

at the surface; fish, turtles, and marine mammals in the water column; or benthic habitats (live bottoms) 

on the bottom. There could be some adverse impacts on organisms contacted by oil, dispersant 

chemicals, or emulsions of dispersed oil droplets and dispersant chemicals that, at this time, are not well 

understood.

Water Quality: Unavoidable adverse impacts from routine offshore operations are dependent in large 

part on the quality of the water. Drilling, construction, overboard discharges of drilling mud and cuttings, 

and pipelaying activities would cause an increase in the turbidity of the affected waters for the duration of 

the activity periods. This, however, would only affect water in the immediate vicinity of the construction 

activity or in the vicinity of offshore structures, rigs, and platforms. The discharge of treated sewage from 

manned rigs and platforms would increase the levels of suspended solids, nutrients, chlorine, and 

biochemical oxygen demand in a small area near the discharge point for a short period of time. 

Accidental spills from platforms and the discharge of produced waters could result in increases of 

hydrocarbon levels and trace metal concentrations in the water column in the vicinity of the platforms. 

Spilled oil from a tanker collision would affect the water surface in combination with dispersant 

chemicals used during spill response. A subsurface blowout would subject the surface, water column, and 

near-bottom environment to spilled oil and exsolved gas, dispersant chemicals, or emulsions of dispersed 

oil droplets and dispersant chemicals. 

Unavoidable impacts to onshore water quality would occur as a result of chronic point- and nonpointsource discharges such as runoff and effluent discharges from existing onshore infrastructure used in 

support of lease sale activities. Vessel traffic contributes to the degradation of water quality by chronic 

low-quantity oil leakage, treated sanitary and domestic waste, bilge water, and contaminants known to 

exist in ship paints. Regulatory requirements of the State and Federal water authorities and some local 
Description of the Environment and Impact Analysis 4-393 

jurisdictions would be applicable to point-source discharges from support facilities such as refineries and 

marine terminals. 

Air Quality: Unavoidable short-term impacts on air quality could occur after large oil spills and 

blowouts because of evaporation and volatilization of the lighter components of crude oil, combustion 

from surface burning, and aerial spraying of dispersant chemicals. Mitigation of long-term effects from 

offshore engine combustion during routine operations would be accomplished through existing 

regulations and development of new control emission technology. Short-term effects from nonroutine 

spill events are uncontrollable and are likely to be aggravated or mitigated by the time of year the spills 

take place. 

Endangered and Threatened Species: Unavoidable adverse impacts on endangered and threatened 

marine mammals, birds, sea turtles, Gulf sturgeon, and hermatypic corals because of routine activities 

associated with the proposed action (e.g., seismic surveys, water quality and habitat degradation, 

helicopter disturbance, vessels and collisions with vessels, and discarded trash and debris) would be 

primarily negligible to minor to a population, but they could be lethal to individuals. Large oil-spill 

events or the response activities to them could adversely impact endangered species that are directly oiled 

or that come into contact with emulsions of oil droplets and dispersant chemicals. Large oil spills are 

expected to be rare, but depending on time and place, the acute impacts from oiled animals could kill tens 

to hundreds of individuals. 

Nonendangered and Nonthreatened Marine Mammals: Unavoidable adverse impacts to 

nonendangered and nonthreatened marine mammals would be those that also affect endangered and 

threatened marine mammal species. Routine operation impacts (such as seismic surveys, water quality 

and habitat degradation, helicopter disturbance, vessel collision, and discarded trash and debris) would be 

negligible or minor to a population, but they could be lethal to individuals as in the case of a vessel 

collision. A large oil spill would temporarily degrade habitat if spilled oil, dispersant chemicals, or 

emulsions of dispersed oil droplets and dispersant chemicals contact free-ranging pods or spawning 

grounds. 

Beach Mice: Impacts to the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice are 

possible but unlikely. Impacts may result from consumption of beach trash and debris. The proposed 

action would deposit only a small portion of the total debris that would reach the habitat. Oil-spillresponse and cleanup activities could also have a significant impact to the beach mice and their habitat if 

not properly regulated. However, potential spills that could result from the proposed action are not 

expected to contact beach mice or their habitats. 

Coastal and Marine Birds: Unavoidable adverse impacts from routine operations on coastal birds 

could result from helicopter and OCS service-vessel traffic, facility lighting, and floating trash and debris. 

Marine birds could be affected by noise, platform lighting, aircraft disturbances, and trash and debris 

associated with offshore activities. Cross-Gulf migrating species could be affected by lighted platforms, 

helicopter and vessel traffic, and floating trash and debris. If a large oil spill occurs and contacts coastal 

or marine bird habitats, some birds could experience lethal and sublethal impacts from oiling, and birds 

feeding or resting in the water could be oiled and die. Coastal birds coming into contact with oil may 

migrate more deeply into marsh habitats, out of reach from spill responders seeking to count them or 

collect them for rehabilitation. Oil spills and oil-spill cleanup activities could also affect the food species 

for coastal, marine, and migratory bird species. 

Fish Resources and Commercial Fisheries: Unavoidable adverse impacts from routine operations are 

loss of open ocean or bottom areas desired for fishing by the presence or construction of OCS facilities 

and pipelines. Loss of gear could occur from bottom obstructions around platforms and subsea 

production systems. Routine discharges from vessels and platforms are minor given the available area for 

fish habitat. If a large oil spill occurs, the oil, dispersant chemicals, or emulsions of oil droplets and 

dispersant chemicals could temporarily displace mobile fish species on a population or local scale. It is 

unlikely that fishermen would want, or be permitted, to harvest fish in the area of an oil spill, as spilled oil 

could coat or contaminate commercial fish species rendering them unmarketable. 

Recreational Beaches: Unavoidable adverse impacts from routine operations may result in the 

accidental loss overboard of some floatable debris that may eventually come ashore on frequented 

recreational beaches. A large oil spill could make landfall on recreational beaches, leading to local or 

regional economic losses and stigma effects, causing potential users to avoid the area after acute impacts 
4-394 Central Planning Area Supplemental EIS 

have been removed. Some recreational beaches become temporarily soiled by weathered crude oil, and 

tarballs may come ashore long after stranded oil has been cleaned from shoreline areas. 

Economic Activity: Net economic, political, and social benefits accrue from the production of 

hydrocarbon resources. Once these benefits become routine, unavoidable adverse impacts from routine 

operations follow trends in supply and demand based on the commodity prices for oil, gas, and refined 

hydrocarbon products. Declines in oil and gas prices can lead to activity ramp downs by operators until 

prices rise. A large oil spill would cause temporary increases in economic activity associated with spillresponse activity. An increase in economic activity from the response to a large spill could be offset by 

temporary work stoppages that are associated with spill-cause investigations and would involve a transfer 

or displacement of demand to different skill sets. Routine operations affected by new regulations that are 

incremental would not have much affect on the baseline of economic activity; however, temporary work 

stoppages or the introduction of several new requirements at one time that are costly to implement could 

cause a drop off of activity as operators adjust to new expectations or use the opportunity to move 

resources to other basins where they have interests. 

Archaeological Resources: Unavoidable adverse impacts from routine operations could lead to the 

loss of unique or significant archaeological information if unrecognized at the time an area is disturbed. 

Required archaeological surveys significantly reduce the potential for this loss by identifying potential 

archaeological sites prior to an interaction occurring, thereby making avoidance or mitigation of impacts 

possible. A large oil spill could make landfall on or near protected archaeological landmarks to cause 

temporary aesthetic or cosmetic impacts until the oil is cleaned or degrades. 

4.3. IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES

Irreversible or irretrievable commitment of resources refers to impacts or losses to resources that 

cannot be reversed or recovered. Examples are when a species becomes extinct or when wetlands are 

permanently converted to open water. In either case, the loss is permanent. 

Wetlands: An irreversible or loss of wetlands and associated biological resources could occur if 

wetlands are permanently lost because of impacts caused by dredging and construction activities that 

displace existing wetlands or from oil spills severe enough to cause permanent die-back of vegetation and 

conversion to open water. Construction and emplacement of onshore pipelines in coastal wetlands 

displace coastal wetlands in disturbed areas that are then subject to indirect impacts like saltwater 

intrusion or erosion of the marsh soils along navigation channels and canals. Ongoing natural and 

anthropogenic processes in the coastal zone, only one of which is OCS-related activity, can result in direct 

and indirect loss of wetlands. Natural losses as a consequence of the coastal area becoming 

hydrologically isolated from the Mississippi River that built it, sea-level rise, and subsidence of the delta 

platform in absence of new sediment added to the delta plain appear to be much more dominant processes 

impacting coastal wetlands. 

Sensitive Nearshore and Offshore Biological Resources: An irreversible loss or degradation of 

ecological habitat caused by cumulative activity tends to be incremental over the short term. Irretrievable 

loss may not occur unless or until a critical threshold is reached. It can be difficult or impossible to 

identify when that threshold is, or would be, reached. Oil spills and chronic low-level pollution can injure 

and kill organisms at virtually all trophic levels. Mortality of individual organisms can be expected to 

occur, and possibly a reduction or even elimination of a few small or isolated populations. The proposed 

biological stipulations, however, are expected to eliminate most of these risks. 

Threatened and Endangered Species: Irreversible loss of individuals that are protected species may 

occur after a large oil spill from the acute impact of being oiled or the chronic impact of oil having 

eliminated, reduced, or rendered suboptimal the food species upon which they were dependent. 

Fish Resources and Commercial Fisheries: Irreversible loss of fish and coral resources, including 

commercial and recreational species, are caused by structural removal using explosives. Fish in 

proximity to an underwater explosion can be killed. Without the structure to serve as habitat area, sessile, 

attached invertebrates and the fish that live among them are absent. Removing structures eliminates these 

special and local habitats and the organisms living there, including such valuable species as red snapper. 

Continued structure removal, regardless of the technique used, would reduce the net benefits to 

commercial fishing due to the presence of these structures.
Description of the Environment and Impact Analysis 4-395 

Recreational Beaches: Impacts on recreational beaches from a large oil spill may at the time seem 

irreversible, but the impacts are temporary. Beaches fouled by a large oil spill would be temporarily 

unavailable to the people who would otherwise frequent them, but only during the period between landfall 

and cleanup of the oil, followed by an indefinite lag period during which stigma effects recede from 

public consciousness. 

Archaeological Resources: Irreversible loss of a prehistoric or historic archaeological resource can 

occur if bottom-disturbing activity takes place without the required survey to demonstrate its absence 

before work proceeds. A resource can be completely destroyed, severely damaged, or the scientific 

context badly impaired by well drilling, subsea completions, and platform and pipeline installation, or 

sand borrowing. 

Oil and Gas Development: Leasing and subsequent development and extraction of hydrocarbons as a 

result of the proposed action represents an irreversible and irretrievable commitment by the removal and 

consumption of nonrenewable oil and gas resources. The estimated amount of resources to be recovered 

as a result of the proposed action is presented in Table 3-1. 

Loss of Human and Animal Life: The OCS oil and gas exploration, development, production, and 

transportation are carried out under comprehensive, state-of-the-art, enforced regulatory procedures 

designed to ensure public and work place safety and environmental protection. Nevertheless, some loss 

of human and animal life is inevitable from unpredictable and unexpected acts of man and nature (i.e., 

unavoidable accidents, accidents caused by human negligence or misinterpretation, human error, willful 

noncompliance, and adverse weather conditions). Some normal and required operations, such as structure 

removal, can kill sea life in proximity to explosive charges or by removal of the structure that served as 

the framework for invertebrates living on it and the fish that lived with it. 

4.4. RELATIONSHIP BETWEEN THE SHORT-TERM USE OF MAN’S ENVIRONMENT 

AND THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY

The short-term effects on various components of the environment in the vicinity of the proposed 

action are related to long-term effects and the maintenance and enhancement of long-term productivity. 

Short-Term Use 

Short-term refers to the total duration of oil and gas exploration and production activities. Extraction 

and consumption of offshore oil and natural gas is a short-term benefit. Discovering and producing 

domestic oil and gas now delays the increase in the Nation’s dependency on foreign imports. Depleting a 

nonrenewable resource now removes these domestic resources from being available for future use. The 

production of offshore oil and natural gas from the proposed action would provide short-term energy, and 

as it delays the increase in the Nation’s dependency on foreign imports, it can also allow additional time 

for ramp-up and development of long-term renewable energy sources or substitutes for nonrenewable oil 

and gas. Economic, political, and social benefits would accrue from the availability of these natural 

resources. 

The principle short-term use of the leased areas in the GOM would be for the production of 

0.801-1.624 BBO and 3.332-6.560 Tcf of gas from the CPA proposed action. The cumulative impacts 

scenario in the Multisale EIS extended from 2007 to 2046, and the cumulative scenario for this 

Supplemental EIS extends approximately from 2012 to 2052. The 40-year time period is used because it 

is the approximate longest life span of activities conducted on an individual lease. The next 40 years is 

the period of time during which the activities and impacting-factors that follow as a consequence of the 

proposed lease sale would be influencing the environment. 

The specific impacts of the proposed action vary in kind, intensity, and duration according to the 

activities occurring at any given time (Chapter 3). Initial activities, such as seismic surveying and 

exploration drilling, result in short-term, localized impacts. Development drilling and well workovers 

occur sporadically throughout the life of the proposed action but also result in short-term, localized 

impacts. Activities during the production life of a platform may result in chronic impacts over a longer 

period of time (over 25 years), potentially punctuated by more severe impacts as a result of accidental 

events or a spill. Platform removal is also a short-term activity with localized impacts, including removal 

of the habitat for encrusting invertebrates and fish living among them. Many of the effects on physical, 
4-396 Central Planning Area Supplemental EIS 

biological, and socioeconomic resources discussed in Chapter 4 are considered to be short term (being 

greatest during the construction, exploration, and early production phases). These impacts could be 

further reduced by the mitigation measures discussed in Chapter 2. 

The OCS development off Louisiana and Texas has enhanced recreational and commercial fishing 

activities, which in turn has stimulated the manufacture and sale of larger private fishing vessels and 

specialized recreational fishing equipment. Commercial enterprises such as charter boats have become 

heavily dependent on offshore structures for satisfying recreational customers. The proposed action could 

increase these incidental benefits of offshore development. Offshore fishing and diving has gradually 

increased in the past three decades, with offshore structures and platforms becoming the focus of much of 

that activity. As mineral resources become depleted, platform removals would occur and may result in a 

decline in these activities. 

The short-term exploitation of hydrocarbons for the OCS Program in the GOM may have long-term 

impacts on biologically sensitive coastal and offshore resources and areas if a large oil spill occurs. A 

spill and spill-response activity could temporarily interfere with commercial and recreational fishing, 

beach use, and tourism in the area where the spill makes landfall and in a wider area based on stigma 

effects. The proposed leasing may also result in onshore development and population increases that could 

cause very short-term adverse impacts to local community infrastructure, particularly in areas of low 

population and minimal existing industrial infrastructure (Chapter 4.1.1.18). 

Relationship to Long-Term Productivity 

Long-term refers to an indefinite period beyond the termination of oil and gas production. Over a 

period of time after peak oil production has occurred in the GOM, a gradual easing of the specific impacts 

caused by oil and gas exploration and production would occur as the productive reservoirs in the GOM 

have been discovered and produced, and have become depleted. The Oil Drum (2009) showed a graphic 

demonstrating that peak oil production in the GOM occurred in June 2002 at 1.73 Mbbl/d. Whether or 

not this date is correct can only be known in hindsight and only after a period of years while production 

continues. At this time, however, the trend is fairly convincing (The Oil Drum, 2009). There is 

disagreement on what future production trends may be in the GOM after several operators, BP among 

them, announced discoveries over the last 5 years (Oil and Gas Journal, 2009) in the Lower Tertiary in 

ultra-deepwater with large projected reserves. These claims are as yet unproven and there are questions 

as to the difficulties that may be encountered producing these prospects because of their geologic age, 

burial depth and high-temperature, high pressure in-situ conditions, lateral continuity of reservoirs, and 

the challenges of producing from ultra-deepwater water depths. 

The GOM’s large marine ecosystem is considered a Class II, moderately productive ecosystem (mean 

phytoplankton primary production 150-300 gChlorophyll-a/m2

-yr [The Encyclopedia of Earth, 2008]), 

based on Sea-viewing Wide Field-of-view Sensor (SeaWiFS) global primary productivity estimates 

(USDOC, NASA, 2003). After the completion of oil and gas production, a gradual ramp-down to 

economic conditions without oil and gas activity would be experienced, while the marine environment is 

generally expected to remain at or return to its normal long-term productivity levels that in recent years 

has been described as stressed (The Encyclopedia of Earth, 2008). The GOM’s large marine ecosystem 

shows signs of ecosystem stress in bays, estuaries, and coastal regions (Birkett and Rapport, 1999). There 

is shoreline alteration, pollutant discharge, oil and gas development, and nutrient loading. The overall 

condition for the U.S. section of this large marine ecosystem, according to USEPA’s seven primary 

indicators (Jackson et al., 2000), is good dissolved oxygen, fair water quality, poor coastal wetlands, poor 

eutrophic condition, and poor sediment, benthos, and fish tissue (The Encyclopedia of Earth, 2008). 

To help sustain the long-term productivity of the GOM ecosystem, the OCS Program provides 

structures to use as site-specific artificial reefs and fish-attracting devices for the benefit of commercial 

and recreational fishermen and to sport divers and spear fishers. Approximately 10 percent of the oil and 

gas structures removed from the OCS are eventually used for State artificial reef programs. 
CHAPTER 5 

CONSULTATION AND COORDINATION
Consultation and Coordination 5-3 

5. CONSULTATION AND COORDINATION 

5.1. DEVELOPMENT OF THE PROPOSED ACTION

The purpose of this Supplemental EIS is to address the remaining proposed Gulf of Mexico CPA 

OCS oil and gas lease sale (CPA Lease Sale 216/222) scheduled under the Outer Continental Shelf Oil 

and Gas Leasing Program: 2012-2017 (5-Year Program). This Supplemental EIS is being prepared 

because of the potential changes to baseline conditions of the environmental, socioeconomic, and cultural 

resources that may have occurred as a result of (1) the DWH event between April 20 and July 15, 2010 

(the period when oil flowed from the Macondo well in Mississippi Canyon Block 252 [Figure 1-2]); (2) 

the acute impacts that have been reported or surveyed since that time; and (3) any new information that 

may be available. The environmental resources include sensitive coastal environments, offshore benthic 

resources, marine mammals, sea turtles, coastal and marine birds, endangered and threatened species, and 

fisheries. This Supplemental EIS analyzes the potential impacts of the proposed action on the marine, 

coastal, and human environments. 

5.2. NOTICE OF PREPARATION OF THE SUPPLEMENTAL EIS 

On November 10, 2010, a Notice of Intent to Prepare a Supplemental EIS (NOI) was published in the 

Federal Register. A second NOI was published on November 16, 2010, to correct clerical errors. 

Additional public notices were distributed via local newspapers, the U.S. Postal Service, and the Internet. 

A 45-day comment period, which closed on January 3, 2011, was announced for the NOI. Federal, State, 

and local governments, along with other interested parties, were invited to send written comments to the 

Gulf of Mexico OCS Region on the scope of the Supplemental EIS. The comments in these letters are 

summarized in Chapter 5.3.2.

5.3. DEVELOPMENT OF THE DRAFT SUPPLEMENTAL EIS 

Scoping for this Supplemental EIS was conducted in accordance with CEQ regulations implementing 

NEPA. Scoping provides those with an interest in the OCS Program an opportunity to provide comments 

on the proposed action. In addition, scoping provides BOEMRE an opportunity to update the Gulf of 

Mexico OCS Region’s environmental and socioeconomic information base. The scoping process 

commenced on November 16, 2010, with the publication of the corrected NOI in the Federal Register. 

Scoping meetings were held in Louisiana, Texas, and Alabama. No meeting had more than 15 attendees. 

The dates, times, locations, and public attendance of the scoping meetings for this proposed Supplemental 

EIS were as follows: 

Tuesday, November 16, 2010 Wednesday, November 17, 2010 

1:00 p.m. CST until adjournment 1:00 p.m. CST until adjournment 

Hilton New Orleans Airport Houston Airport Marriott 

New Orleans, Louisiana Houston, Texas 

9 registered attendees 16 registered attendees 

4 speakers 5 speakers 

Thursday, November 18, 2010 

1:00 p.m. CST until adjournment 

The Battle House Renaissance 

Mobile Hotel and Spa 

Mobile, Alabama 

13 registered attendees 

4 speakers 
5-4 Central Planning Area Supplemental EIS 

5.3.1. Summary of Scoping Comments 

Comments (both verbal and written) were received from the NOI and the three scoping meetings from 

Federal, State, and local government agencies; interest groups; industry; businesses; the Seminole Tribe 

of Florida; and the general public on the scope of the Supplemental EIS, significant issues that should be 

addressed, alternatives that should be considered, and mitigation measures. All scoping comments 

received, which were appropriate for a lease sale NEPA document, were considered in the preparation of 

this Supplemental EIS. All speakers at the scoping meetings were generally supportive of the proposed 

lease sales and recognized the economic benefits of the OCS Program. Comments received from 

attendees included the following: 

 use currently available new information to evaluate impacts; 

 supported holding lease sales as soon as possible; 

 move expeditiously to complete the Supplemental EIS; 

 cancelling lease sales would harm the economy, damage energy production, depress 

job creation, and reduce revenues to the State and Federal treasuries; 

 resume permitting of existing leases; 

 Lease Sales 216, 218, and 222 should be held with no reduction in acreage; 

 recommended that the Supplemental EIS incorporate all new regulations and 

requirements put in place post-Macondo; and 

 put no restrictions on drilling in deepwater areas. 

5.3.2. Summary of Written Comments Received in Response to the Notice of 

Intent 

In response to the NOI, BOEMRE received 11 individual letters by e-mail, 595 identical form 

e-letters from an advocacy website, and a package of 3 CD’s with over 20,000 identical website-derived 

form letters from an advocacy group. Information submitted from written comments is summarized in 

Table 5-1, including the form letters submitted by the Consumer Energy Alliance. All scoping comments 

received that were appropriate for the lease sale NEPA document were considered in the preparation of 

this Supplemental EIS. Scoping comments appropriate for a lease sale NEPA document include scenario 

information; physical, biological, and socioeconomic resources to consider; impacting factors and impacts 

on resources; alternatives to be analyzed; and mitigation measures. Several comments received did not 

apply to scoping for this document including, but not limited, to scheduling and delays of remaining lease 

sales, expediting the completion of the Supplemental EIS, impacts from delay of the lease sales that had 

been scheduled as part of the 5-Year Program, categorical exclusions, and using this Supplemental EIS as 

a document to tier future lease sales for the 2012-2017 lease sale program. All other comments described 

in Table 5-1 were considered in this document. 

5.3.3. Cooperating Agency 

According to Part 516 of the DOI Departmental Manual, BOEMRE must invite eligible governmental 

entities to participate as cooperating agencies when developing an EIS, in accordance with the 

requirements of NEPA and the CEQ regulations. The BOEMRE must also consider any requests by 

eligible government entities to participate as a cooperating agency with respect to a particular EIS, and 

then to either accept or deny such requests. 

The NOI’s published on November 10 and November 16, 2010, included invitations to other Federal 

agencies and State, tribal, and local governments to consider becoming cooperating agencies in the 

preparation of this Supplemental EIS. The USEPA (Region 6) and NOAA requested to participate as 

cooperating agencies. The BOEMRE has accepted NOAA and USEPA (Region 6) as cooperating 

agencies. 
Consultation and Coordination 5-5 

5.4. DISTRIBUTION OF THE DRAFT SUPPLEMENTAL EIS FOR REVIEW AND 

COMMENT

The BOEMRE sent copies of this Draft Supplemental EIS to the public and private agencies and 

groups listed below. Local libraries along the Gulf Coast were provided copies of this document; a list of 

these libraries is available on BOEMRE’s Internet website at http://www.gomr.boemre.gov/homepg/

regulate/environ/libraries.html. 

Federal Agencies 

Congress 

Congressional Budget Office 

House Resources Subcommittee on Energy 

and Mineral Resources 

Senate Committee on Energy and Natural 

Resources 

Department of Commerce 

National Marine Fisheries Service 

National Oceanic and Atmospheric 

Administration 

Department of Defense 

Department of the Air Force 

Department of the Army 

 Corps of Engineers 

Department of the Navy 

 Naval Mine and ASW Command 

Department of Energy 

Strategic Petroleum Reserve PMD 

Department of the Interior 

Bureau of Ocean Energy Management, 

Regulation and Enforcement 

Fish and Wildlife Service 

Geological Survey 

National Park Service 

Office of Environmental Policy and 

Compliance 

Office of the Solicitor 

Department of State 

Bureau of Oceans and International 

Environmental and Scientific Affairs 

Department of Transportation 

Coast Guard 

Office of Pipeline Safety 

Environmental Protection Agency 

 Region 4 

 Region 6 

Marine Mammal Commission 

State and Local Agencies 

Alabama 

Governor’s Office 

Alabama Highway Department 

Alabama Historical Commission and State 

 Historic Preservation Officer 

Alabama Public Service Commission 

Department of Conservation and Natural 

Resources 

Department of Environmental Management 

South Alabama Regional Planning 

Commission 

State Docks Department 

State Legislature Natural Resources 

Committee 

State Legislature Oil and Gas Committee 

Florida 

Governor’s Office 

Bureau of Archaeological Research 

City of Gulf Breeze 

City of Panama 

City of Pensacola 

Department of Community Affairs 

Department of Environmental Protection 

Department of State Archives, History and 

Records Management 

Escambia County 

Florida Coastal Zone Management Office 

Sarasota County Coastal Resources 

State Legislature Natural Resources and 

Conservation Committee 

State Legislature Natural Resources 

Committee 

West Florida Regional Planning Council 

Louisiana 

Governor’s Office 

City of Grand Isle 

City of Morgan City 

City of New Orleans 

Department of Culture, Recreation, and 

Tourism 

Department of Environmental Quality 

Department of Natural Resources 

Department of Transportation and 

Development 

Department of Wildlife and Fisheries 

Houma-Terrebonne Chamber of Commerce 

Jefferson Parish Director 

Jefferson Parish President 
5-6 Central Planning Area Supplemental EIS 

Lafourche Parish CZM 

Lafourche Parish Water District #1 

Louisiana Geological Survey 

South Lafourche Levee District 

St. Bernard Planning Commission 

State House of Representatives, Natural 

Resources Committee 

State Legislature, Natural Resources 

Committee 

Mississippi 

Governor’s Office 

City of Gulfport 

Department of Archives and History 

Department of Natural Resources 

Department of Wildlife Conservation 

Mississippi Development Authority 

State Legislature Oil, Gas, and Other 

Minerals Committee 

Industry 

Air Armament Center 

Alabama Petroleum Council 

American Petroleum Institute 

Area Energy LLC 

Baker Atlas 

Bellwether Group 

B-J Services Co 

BP Amoco 

Chevron U.S.A. Inc. 

Coastal Conservation Association 

Coastal Environments, Inc. 

Continental Shelf Associates, Inc. 

Dominion Exploration & Production, Inc. 

Ecological Associates, Inc. 

Ecology and Environment 

Energy Partners, Ltd. 

EOG Resources, Inc. 

Escambia County Marine Resources 

Exxon Mobil Production Company 

Florida Petroleum Council 

Florida Propane Gas Association 

Freeport-McMoRan, Inc. 

Fugro Geo Services, Inc. 

Gulf Environmental Associates 

Gulf of Mexico Newsletter 

Horizon Marine, Inc. 

Industrial Vehicles International, Inc. 

International Association of Geophysical 

Contractors 

J. Connor Consultants 

John Chance Land Surveys, Inc. 

Marine Safety Office 

Midstream Fuel Service 

Mote Marine Laboratory 

Murphy Exploration & Production 

Newfield Exploration Company 

NWF Daily News 

Petrobras America, Inc. 

PPG Industries, Inc. 

Propane Market Strategy Newsletter 

Science Applications International 

Corporation 

Seneca Resources Corporation 

Shell Exploration & Production Company 

Stone Energy Corporation 

Strategic Management Services-USA 

T. Baker Smith, Inc. 

Texas Geophysical Company, Inc. 

The Houston Exploration Company 

Triton Engineering Services Co. 

W & T Offshore, Inc. 

Washington Post 

WEAR-TV 

Special Interest Groups 

1000 Friends of Florida 

Alabama Oil & Gas Board 

American Cetacean Society 

Audubon Louisiana Nature Center 

Bay County Audubon Society 

Citizens Assoc. of Bonita Beach 

Clean Gulf Associates 

Coastal Conservation Association 

Earthjustice 

Florida Chamber of Commerce 

Florida Institute of Oceanography 

Florida Marine Research 

Florida Natural Area Inventory 

Florida Public Interest Research Group 

Florida Sea Grant College 

Gulf Coast Environmental Defense 

Gulf County 

Gulf County Atlantic Fisheries 

Gulf Island National Seashore 

Hernando County Planning Department 

Hunt Oil 

Izaak Walton League of America, Inc 

JOC Venture 

Louisiana State University 

Marine Mammal Commission 

Mission Enhancement Office 

Mississippi State University 

Mobile Bay National Estuary Program 

Natural Resources Defense Council 

Nature Conservancy 
Consultation and Coordination 5-7 

Nicholas State University 

Perdido Key Association 

Population Connection 

Portersville Revival Group 

Sierra Club 

South Mobile Communities Association 

Southeastern Fisheries Association 

The Conservancy 

The Conservation Fund 

The Daspit Company 

The Nature Conservancy 

Walton County Growth Management 

Ports/Docks 

Alabama 

Alabama State Port Authority 

Port of Mobile 

Florida 

Panama City Port Authority 

Louisiana 

Greater Baton Rouge Port Commission 

Greater Lafourche Port Commission 

Grand Isle Port Commission 

Plaquemines Port, Harbor and Terminal 

District 

Port of Baton Rouge 

Port of Iberia District 

Port of New Orleans 

Twin Parish Port Commission 

St. Bernard Port, Harbor and Terminal 

 District 

Mississippi 

Port of Gulfport 

State Port Authority 

5.5. PUBLIC HEARINGS

In accordance with 30 CFR 256.26, BOEMRE will schedule public hearings soliciting comments on 

this Supplemental EIS. The hearings also provide the Secretary of the Interior with information from 

interested parties to help in the evaluation of potential effects of the proposed lease sale. An 

announcement of the dates, times, and locations of the public hearings will be included in the Notice of 

Availability for this Supplemental EIS. A copy of the public hearing notices were included with this 

Supplemental EIS that were mailed to the parties indicated above, posted on BOEMRE’s Internet website 

(http://www.gomr.boemre.gov), and published in local newspapers. 

5.6. COASTAL ZONE MANAGEMENT ACT

A consistency review will be performed and a Consistency Determination (CD) will be prepared for 

the affected States prior to the proposed lease sale. To prepare the CD’s, BOEMRE reviews each State’s 

Coastal Management Plan (CMP) and analyzes the potential impacts as outlined in this Supplemental 

EIS, new information, and applicable studies as they pertain to the enforceable policies of each CMP. 

The CZMA requires that Federal actions that are reasonably likely to affect any land or water use or 

natural resource of the coastal zone be “consistent to the maximum extent practicable” with relevant 

enforceable policies of the State’s federally approved coastal management program (15 CFR 930 

Subpart C). If an activity will have direct, indirect, or cumulative effects, the activity is subject to Federal 

consistency. 

Based on the analyses, the BOEMRE Director makes an assessment of consistency, which is then sent 

to each State with the Proposed Notice of Sale. If a State concurs, BOEMRE can hold the lease sale. If 

the State objects, it must do the following under the CZMA: (1) indicate how BOEMRE’s presale 

proposal is inconsistent with their CMP and suggest alternative measures to bring BOEMRE’s proposal 

into consistency with their CMP; or (2) describe the need for additional information that would allow a 

determination of consistency. Unlike the consistency process for specific OCS plans and permits, there is 

no procedure for administrative appeal to the Secretary of Commerce for a Federal CD for presale 

activities. Either BOEMRE or the State may request mediation. Mediation is voluntary, and the DOC 

would serve as the mediator. Whether there is mediation or not, the final CD is made by DOI and it is the 

final administrative action for the presale consistency process. Each Gulf State’s CMP is described in 

Appendix B of the Multisale EIS (USDOI, MMS, 2007b). 
5-8 Central Planning Area Supplemental EIS 

5.7. ENDANGERED SPECIES ACT

The Endangered Species Act of 1973 (ESA) (16 U.S.C. 1631 et seq.) of 1973, as amended (43 U.S.C. 

1331 et seq.), establishes a national policy designed to protect and conserve threatened and endangered 

species and the ecosystems upon which they depend. In accordance with Section 7 of the ESA, 

BOEMRE consulted with NMFS and FWS on possible and potential impacts from the proposed sale on 

endangered/threatened species and designated critical habitat under their jurisdiction. A biological 

assessment was prepared for each consultation. The action area analyzed in the biological assessments 

included the lease sale area addressed in this Supplemental EIS. 

The formal ESA consultation with NMFS was concluded with receipt of the Biological Opinion on 

July 3, 2007. The Biological Opinion concludes that the proposed lease sale and associated activities in 

the Gulf of Mexico under the 5-Year Program are not likely to jeopardize the continued existence of 

threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated 

critical habitat. The informal ESA consultation with FWS was concluded with a letter dated 

September 14, 2007. The FWS concurred with BOEMRE’s determination that this proposed action under 

the 5-Year Program was not likely to adversely affect the threatened/endangered species or designated 

critical habitat under FWS jurisdiction. 

Under these existing consultations with FWS and NMFS, BOEMRE continues to request annual 

concurrence from both NMFS and FWS to ensure current activities and any actual take remain consistent 

with the Terms and Conditions of the Biological Opinion. For 2010, NMFS emailed their concurrence to 

BOEMRE on December 3, 2009, and FWS emailed their concurrence to BOEMRE on December 8, 2009. 

The extent and scope of the spill caused by the DWH event represents new information not assessed 

in the existing ESA Section 7 consultation in the Gulf of Mexico under the current 5-Year Program. As a 

result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the Multisale EIS 

with NMFS and FWS on July 30, 2010. The NMFS responded with a letter to BOEMRE on 

September 24, 2010; FWS responded with a letter to BOEMRE on September 27, 2010. However, 

NMFS and FWS have placed this consultation on hold given the environmental baseline needing to be 

updated by the results of the NRDA process. The NRDA data have yet to be released. The existing 

consultations will remain in effect until the reinitiated consultations are completed. 

In the interim, BOEMRE will continue to comply with all Reasonable and Prudent Measures and the 

Terms and Conditions under these existing consultations, along with implementing the current BOEMREimposed mitigation, monitoring, and reporting requirements. Based on the most recent and best available 

information at the time, BOEMRE will also continue to closely evaluate and assess risks to listed species 

and designated critical habitat in upcoming environmental compliance documentation under NEPA and 

other statutes. 

5.8. MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT ACT

Pursuant to Section 305(b) of the Magnuson-Stevens Fishery Conservation and Management Act, 

Federal agencies are required to consult with NMFS on any action that may result in adverse effects to 

EFH. The NMFS published the final rule implementing the EFH provisions of the Magnuson-Stevens 

Fisheries Conservation and Management Act (50 CFR 600) on January 17, 2002. Certain OCS activities 

authorized by BOEMRE may result in adverse effects to EFH, and therefore, require EFH consultation. 

In March 2000, BOEMRE’s Gulf of Mexico OCS Region consulted with NMFS’s Southeast 

Regional Office in preparing a NMFS regional finding for the Gulf of Mexico OCS Region that allows 

BOEMRE to incorporate the EFH assessments into NEPA documents. The BOEMRE consulted on a 

programmatic level by letters of July 1999 and August 1999 to address EFH issues for certain BOEMRE 

OCS activities (i.e., plans of exploration and production, pipeline rights-of-way, and platform removals). 

An EFH consultation for the CPA and WPA lease sales included in the 5-Year Program, using the 

Gulf of Mexico OCS Oil and Gas Lease Sales: 2003-2007; Central Planning Area Sales 185, 190, 194, 

198, and 201; Western Planning Area Sales 187, 192, 196, and 200, Draft Environmental Impact 

Statement (USDOI, MMS, 2002b) as the NEPA document, was initiated in March 2002 by this Agency 

with NMFS’s Southeast Regional Office. The NMFS responded in April 2002, endorsing the 

implementation of resource protection measures previously developed cooperatively by this Agency and 

NMFS in 1999 to minimize and avoid EFH impacts related to exploration and development activities in 
Consultation and Coordination 5-9 

the CPA and WPA. In addition to routine measures, additional conservation recommendations were 

made. In May 2002, this Agency responded to NMFS, acknowledging receipt and agreement to follow 

the additional conservation recommendations. The EFH conservation measures recommended by NMFS 

serve the purpose of protecting EFH. Continuing agreements, including avoidance distances from the 

topographic features’ No Activity Zones and live-bottom pinnacle features, as well as circumstances that 

require project-specific consultation, appear in the clarifying provisions of NTL 2004-G05. 

Effective January 23, 2006, NMFS approved a revision to the EFH rules, acknowledging amendments 

made by the Gulf of Mexico Fishery Management Council resulting in the identification of habitat areas 

of particular concern. One of the most important changes noted in the amendment is the elimination of 

the EFH description and identification from waters between 100 fathoms and the seaward limit of the 

EEZ. 

Further programmatic consultation was initiated and completed for the 5-Year Program’s lease sales 

included in the Multisale EIS. The NMFS concurred by letter dated December 12, 2006, that the 

information presented in the 2003-2007 Draft Multisale EIS satisfies the EFH consultation procedures 

outlined in 50 CFR 600.920 and as specified in NMFS’s March 17, 2000, findings. Provided that 

BOEMRE’s proposed mitigations, NMFS’s previous EFH conservation recommendations, and the 

standard lease stipulations and regulations are followed as proposed, NMFS agrees that impacts to EFH 

and associated fishery resources resulting from activities conducted under the 5-Year Program’s lease 

sales would be minimal. Following the DWH event, on July 30, 2010, BOEMRE requested reinitiation of 

ESA consultation with both NMFS and FWS. The NMFS responded with a letter to BOEMRE on 

September 24, 2010. The EFH consultation was also addressed in NMFS’s letter. The reinitiated 

consultations are not complete at this time, although BOEMRE and NMFS have had discussions and are 

working on a new consultation document for the 2012-2017 Multisale EIS. 

5.9. NATIONAL HISTORIC PRESERVATION ACT

In accordance with the National Historic Preservation Act (NHPA) (16 U.S.C. 470), Federal agencies 

are required to consider the effect of their undertakings on historic properties. The implementing 

regulations for Section 106 of the NHPA (16 U.S.C. 470f), issued by the Advisory Council on Historic 

Preservation (16 CFR 800), specify the required review process. The BOEMRE initiated a request for 

consultation with the affected Gulf States and Tribal Nations on November 12, 2010, via a formal letter. 

A timeline of 30 days was provided and two responses were received. 

The State of Louisiana, in a letter to BOEMRE dated December 16, 2010, indicated that no known 

historic properties will be affected by this undertaking and that consultation regarding the proposed action 

is not necessary. The Seminole Tribe of Florida-Tribal Historic Preservation Officer (STOF-THPO) 

responded to BOEMRE’s request for consultation on December 6, 2010. The STOF-THPO indicated that 

there was no objection to the proposed undertaking at this time. The STOF-THPO requested to review 

the impending remote-sensing survey reports that are to be conducted over the high-probability zones 

within the project area. Additionally, the STOF-THPO requested to be notified if cultural resources that 

are potentially ancestral or historically relevant to the Seminole Tribe of Florida are inadvertently 

discovered at any point during this process. No further responses were received beyond the 30-day 

timeline and no further requests for consultation were received. 

This Section 106 consultation is concluded at this time. The BOEMRE will continue to impose 

mitigating measures and monitoring and reporting requirements to ensure that historic properties are not 

affected by the proposed undertaking. The BOEMRE will reinitiate the consultation process with the 

affected parties should such circumstances warrant further consultation. 
CHAPTER 6 

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Pollution Bulletin 52:1176-1181. 
CHAPTER 7 

PREPARERS
Preparers 7-3 

7. PREPARERS 

Gary D. Goeke, Chief, Environmental Assessment Section 

Casey Rowe, Lead NEPA Coordinator, Senior Environmental Scientist 

Barry Obiol, Coordinator, Senior Environmental Scientist 

Keely Hite, Headquarters’ Coordinator, Environmental Specialist 

Pat Adkins, Information Management Specialist 

Bruce Baird, Senior Environmental Scientist 

Tom Bjerstedt, Coordinator, Senior Physical Scientist 

Perry Boudreaux, Biologist 

Darice K. Breeding, Environmental Protection Specialist 

Sindey Chaky, Environmental Protection Specialist 

Dennis Chew, Marine Biologist 

Deborah Epperson, Protected Species Biologist 

Barret Fortier, Biologist 

Donald (Tre) W. Glenn III, Protected Species Biologist 

Mike Gravois, Geographer 

Larry M. Hartzog, Environmental Scientist 

Christopher Horrell, Senior Marine Archaeologist 

Chin Hua Huang, Meteorologist 

Mark Jensen, Economist 

Jack Irion, Unit Supervisor, Marine Archaeologist 

Agatha Kaller, Marine Biologist 

Nancy M. Kornrumpf, Program Analyst 

Carla Langley, Geographer 

Daniel (Herb) Leedy, Supervisor, Biological Sciences Unit 

Lissa Lyncker, Biologist 

Alexis Lugo-Fernandez, Oceanographer 

Harry Luton, Social Scientist 

Margaret Metcalf, Physical Scientist 

Deborah H. Miller, Technical Editor 

Megan Milliken, Environmental Protection Specialist 

David P. Moran, Biologist 

Maureen M. Mulino, Marine Biologist 

Michelle Nannen, Marine Biologist 

S. Erin O’Reilly, Physical Scientist 

Catherine A. Rosa, Environmental Assessment Program Specialist 

James Sinclair, Marine Biologist 

Kristen L. Strellec, Economist 

Kate Winters, Biologist 
CHAPTER 8 

GLOSSARY
Glossary 8-3 

8. GLOSSARY 

Acute — Sudden, short term, severe, critical, 

crucial, intense, but usually of short duration. 

Anaerobic — Capable of growing in the absence 

of molecular oxygen. 

Annular preventer — A component of the 

pressure control system in the BOP that forms 

a seal in the annular space around any object 

in the wellbore or upon itself, enabling well 

control operations to commence.

Anthropogenic — Coming from human sources, 

relating to the effect of humankind on nature. 

API gravity — A standard adopted by the 

American Petroleum Institute for expressing 

the specific weight of oil. 

Aromatic — Class of organic compounds 

containing benzene rings or benzenoid 

structures.

Attainment area — An area that is shown by 

monitored data or by air-quality modeling 

calculations to be in compliance with primary 

and secondary ambient air quality standards 

established by the USEPA. 

Barrel (bbl) — A volumetric unit used in the 

petroleum industry; equivalent to 42 U.S. 

gallons or 158.99 liters. 

Benthic — On or in the bottom of the sea.

Biological Opinion — The FWS or NMFS 

evaluation of the impact of a proposed action 

on endangered and threatened species, in 

response to formal consultation under Section 

7 or the endangered Species Act.

Block — A geographical area portrayed on 

official BOEMRE protraction diagrams or 

leasing maps that contains approximately 

2,331 ha (9 mi2

).

Blowout — An uncontrolled flow of fluids below 

the mudline from appurtenances on a wellhead 

or from a wellbore. 

Blowout preventer (BOP) — One of several 

valves installed at the wellhead to prevent the 

escape of pressure either in the annular space 

between the casing and drill pipe or in open 

hole (i.e., hole with no drill pipe) during 

drilling completion operations. Blowout 

preventers on jackup or platform rigs are 

located at the water’s surface; on floating 

offshore rigs, BOP’s are located on the 

seafloor.

Bottom kill — A wild well-control procedure 

involving the intersection of an uncontrolled 

well with a relief well for the purpose of 

pumping heavy mud or cement into the wild 

well to stanch the flow of oil or gas (the well 

control strategy for the Macondo spill 

deployed in mid-July 2010 that resulted in the 

successful capping of the well. 

Cetacean — Aquatic mammal of the order 

Cetacea, such as whales, dolphins, and 

porpoises. 

Chemosynthetic — Organisms that obtain their 

energy from the oxidation of various inorganic 

compounds rather than from light 

(photosynthetic). 

Cofferdam containment dome — A vertically 

elongated box structure designed to fit loosely 

over the Macondo lower marine riser package 

to capture escaping oil at the surface (an early 

containment strategy for the Macondo spill 

deployed in May 2010). 

Coastal waters — Waters within the geographical 

areas defined by each State’s Coastal Zone 

Management Program. 

Coastal wetlands — forested and nonforested 

habitats, mangroves, and marsh islands 

exposed to tidal activity. These areas directly 

contribute to the high biological productivity 

of coastal waters by input of detritus and 

nutrients, by providing nursery and feeding 

areas for shellfish and finfish, and by serving 

as habitat for birds and other animals. 

Coastal zone — The coastal waters (including the 

lands therein and thereunder) and the adjacent 

shorelands (including the waters therein and 

thereunder) strongly influenced by each other 

and in proximity to the shorelines of the 

several coastal states; the zone includes 

islands, transitional and intertidal areas, salt 

marshes, wetlands, and beaches and extends 

seaward to the outer limit of the United States 

territorial sea. The zone extends inland from 

the shorelines only to the extent necessary to 

control shorelands, the uses of which have a 

direct and significant impact on the coastal 

waters. Excluded from the coastal zone are 
8-4 Central Planning Area Supplemental EIS

lands the use of which is by law subject to the 

discretion of or which is held in trust by the 

Federal Government, its officers, or agents. 

See also State coastal zone boundaries. 

Completion — Conversion of a development well 

or an exploratory well into a production well. 

Condensate — Liquid hydrocarbons produced 

with natural gas; they are separated from the 

gas by cooling and various other means. 

Condensates generally have an API gravity of 

50o

-120o. 

Continental margin — The ocean floor that lies 

between the shoreline and the abyssal ocean 

floor, includes the continental shelf, 

continental slope, and continental rise. 

Continental shelf — General term used by 

geologist to refer to the continental margin 

province that lies between the shoreline and 

the abrupt change in slope called the shelf 

edge, which generally occurs in the Gulf of 

Mexico at about 200 m water depth. The 

continental shelf is characterized by a gentle 

slope (about 0.1o

). This is different from the 

juridicial term used in Article 76 of the 

Convention on the Law of the Sea (see the 

definition of Outer Continental Shelf). 

Continental slope — The continental margin 

province that lies between the continental 

shelf and continental rise, characterized by a 

steep slope (about 3o

-6o). 

Critical habitat — Specific areas essential to the 

conservation of a protected species and that 

may require special management 

considerations or protection. 

Crude oil — Petroleum in its natural state as it 

emerges from a well, or after it passes through 

a gas-oil separator but before refining or 

distillation. An oily, flammable, bituminous 

liquid that is essentially a complex mixture of 

hydrocarbons of different types with small 

amounts of other substances. 

Deferral — Action taken by the Secretary of the 

Interior at the time of the Area Identification 

to remove certain areas/blocks from the 

proposed sale. 

Delineation well — A well that is drilled for the 

purpose of determining the size and/or volume 

of an oil or gas reservoir. 

Demersal — Living at or near the bottom of the 

sea. 

Deepwater Horizon (DWH) event — All actions 

stemming from the April 20, 2010, explosion 

and subsequent sinking of the Transocean 

drillship Deepwater Horizon, up to and 

including the Macondo well kill declaration on 

September 19, 2010.

Development — Activities that take place 

following discovery of economically 

recoverable mineral resources, including 

geophysical surveying, drilling, platform 

construction, operation of onshore support 

facilities, and other activities that are for the 

purpose of ultimately producing the resources.

Development Operations Coordination 

Document (DOCD) — A document that must 

be prepared by the operator and submitted to 

BOEMRE for approval before any 

development or production activities are 

conducted on a lease in the Western Gulf. 

Development well — A well drilled to a known 

producing formation to extract oil or gas; a 

production well; distinguished from a wildcat 

or exploratory well and from an offset well. 

Direct employment — Consists of those workers 

involved the primary industries of oil and gas 

exploration, development, and production 

operations (Standard Industrial Classification 

Code 13—Oil and Gas Extraction). 

Discharge — Something that is emitted; flow rate 

of a fluid at a given instant expressed as 

volume per unit of time. 

Dispersant — A suite of chemicals and solvents 

used to break up an oil slick into small 

droplets, which increases the surface area of 

the oil and hastens the processes of weathering 

and microbial degradation. 

Dispersion — A suspension of finely divided 

particles in a medium. 

Drilling mud — A mixture of clay, water or 

refined oil, and chemical additives pumped 

continuously downhole through the drill pipe 

and drill bit, and back up the annulus between 

the pipe and the walls of the borehole to a 

surface pit or tank. The mud lubricates and 

cools the drill bit, lubricates the drill pipe as it 

turns in the wellbore, carries rock cuttings to 

the surface, serves to keep the hole from 

crumbling or collapsing, and provides the 

weight or hydrostatic head to prevent 

extraneous fluids from entering the well bore 
Glossary 8-5 

and to downhole pressures; also called drilling 

fluid. 

Economically recoverable resources — An 

assessment of hydrocarbon potential that takes 

into account the physical and technological 

constraints on production and the influence of 

costs of exploration and development and 

market price on industry investment in OCS 

exploration and production. 

Effluent — The liquid waste of sewage and 

industrial processing. 

Effluent limitations — Any restriction 

established by a State or the USEPA on 

quantities, rates, and concentrations of 

chemical, physical, biological, and other 

constituents discharged from point sources 

into U.S. waters, including schedules of 

compliance. 

Epifaunal — Animals living on the surface of 

hard substrate. 

Essential habitat — Specific areas crucial to the 

conservation of a species and that may 

necessitate special considerations. 

Estuary — Coastal semienclosed body of water 

that has a free connection with the open sea 

and where freshwater meets and mixes with 

seawater. 

Eutrophication — Enrichment of nutrients in the 

water column by natural or artificial methods 

accompanied by an increase of respiration, 

which may create an oxygen deficiency. 

Exclusive Economic Zone (EEZ) — The 

maritime region extending 200 nmi from the 

baseline of the territorial sea, in which the 

United States has exclusive rights and 

jurisdiction over living and nonliving natural 

resources. 

Exploration Plan (EP) — A plan that must be 

prepared by the operator and submitted to 

BOEMRE for approval before any exploration 

or delineation drilling is conducted on a lease 

in the Western Gulf. 

Exploration well — A well drilled in unproven or 

semi-proven territory to determining whether 

economic quantities of oil or natural gas 

deposit are present; exploratory well. 

False crawls — Refers to when a female sea turtle 

crawls up on the beach to nest (perhaps) but 

does not and returns to the sea without laying 

eggs. 

Field — An accumulation, pool, or group of pools 

of hydrocarbons in the subsurface. A 

hydrocarbon field consists of a reservoir in a 

shape that will trap hydrocarbons and that is 

covered by an impermeable, sealing rock. 

Floating production, storage, and offloading 

(FPSO) system — A tank vessel used as a 

production and storage base; produced oil is 

stored in the hull and periodically offloaded to 

a shuttle tanker for transport to shore.. 

Gathering lines — A pipeline system used to 

bring oil or gas production from a number of 

separate wells or production facilities to a 

central trunk pipeline, storage facility, or 

processing terminal. 

Geochemical — Of or relating to the science 

dealing with the chemical composition of and 

the actual or possible chemical changes in the 

crust of the earth. 

Geophysical survey — A method of exploration 

in which geophysical properties and 

relationships are measured remotely by one or 

more geophysical methods. 

Habitat — A specific type of environment that is 

occupied by an organism, a population, or a 

community. 

Hermatypic coral — Reef-building corals that 

produce hard, calcium carbonate skeletons and 

that possess symbiotic, unicellular algae 

within their tissues. 

Harassment — An intentional or negligent act or 

omission that creates the likelihood of injury 

to wildlife by annoying it to such an extent as 

to significantly disrupt normal behavior 

patterns that include, but are not limited to, 

feeding or sheltering. 

Hydrocarbons — Any of a large class of organic 

compounds containing primarily carbon and 

hydrogen. Hydrocarbon compounds are 

divided into two broad classes: aromatic and 

aliphatics. They occur primarily in petroleum, 

natural gas, coal, and bitumens. 

Hypoxia — Depressed levels of dissolved oxygen 

in water, usually resulting in decreased 

metabolism. 

Incidental take — Takings that result from, but 

are not the purpose of, carrying out an 
8-6 Central Planning Area Supplemental EIS

otherwise lawful activity (e.g., fishing) 

conducted by a Federal agency or applicant 

(see Taking). 

Indirect employment — Secondary or supporting 

oil- and gas-related industries, such as the 

processing of crude oil and gas in refineries, 

natural gas plants, and petrochemical plants. 

Induced employment — Tertiary industries that 

are created or supported by the expenditures of 

employees in the primary or secondary 

industries (direct and indirect employment), 

including consumer goods and services such 

as food, clothing, housing, and entertainment. 

Infrastructure — The facilities associated with 

oil and gas development, e.g., refineries, gas 

processing plants, etc. 

Jack-up rig — A barge-like, floating platform 

with legs at each corner that can be lowered to 

the sea bottom to raise the platform above the 

water. 

Junk shot — A wild well-control procedure 

accompanying a top kill that introduces 

foreign objects into the drilling fluid (such as 

shredded rope, rubber, or golf balls) and that is 

designed to clog the openings or partial 

openings in a nonfunctioning blowout 

preventer (an early well control strategy for 

the Macondo spill in May 2010). 

Kick — A deviation or imbalance, typically 

sudden or unexpected, between the downward 

pressure exerted by the drilling fluid and the 

upward pressure of in situ formation fluids or 

gases.

Landfall — The site where a marine pipeline 

comes to shore. 

Lease — Authorization that is issued under 

Section 8 or maintained under Section 6 of the 

Outer Continental Shelf Lands Act and that 

authorizes exploration for, and development 

and production of, minerals. 

Lease sale — The competitive auction of leases 

granting companies or individuals the right to 

explore for and develop certain minerals under 

specified conditions and periods of time. 

Lease term — The initial period for oil and gas 

leases, usually a period of 5, 8, or 10 years 

depending on water depth or potentially 

adverse conditions. 

Lessee — A party authorized by a lease, or an 

approved assignment thereof, to explore for 

and develop and produce the leased deposits in 

accordance with regulations at 30 CFR 250. 

Lower marine riser package — The head 

assembly of a subsurface well at the point 

where the riser connects to a blowout 

preventer.

Macondo — Prospect name given by BP to the 

Mississippi Canyon Block 252 exploration 

well that the Deepwater Horizon rig was 

drilling when a blowout occurred on April 20, 

2010.

Macondo spill — The name given to the oil spill 

that resulted from the explosion and sinking of 

the Deepwater Horizon rig from the period 

between April 24, 2010, when search and 

recovery vessels on site reported oil at the sea 

surface until uncontrolled flow from the 

Macondo well was capped. 

Marshes — Persistent, emergent, nonforested 

wetlands characterized by predominantly 

cordgrasses, rushes, and cattails. 

Military warning area — An area established by 

the Department of Defense within which 

military activities take place. 

Minerals — As used in this document, minerals 

include oil, gas, sulphur, and associated 

resources, and all other minerals authorized by 

an Act of Congress to be produced from 

public lands as defined in Section 103 of the 

Federal Land Policy and Management Act of 

1976. 

Nepheloid — A layer of water near the bottom 

that contains significant amounts of suspended 

sediment. 

Nonattainment area — An area that is shown by 

monitoring data or by air-quality modeling 

calculations to exceed primary or secondary 

ambient air quality standards established by 

the USEPA. 

Nonhazardous oil-field wastes (NOW) — 

Wastes generated by exploration, 

development, or production of crude oil or 

natural gas that are exempt from hazardous 

waste regulation under the Resource 

Conservation and Recovery Act (Regulatory 

Determination for Oil and Gas and 

Geothermal Exploration, Development and 

Production Wastes, dated June 29, 1988, 
Glossary 8-7 

53 FR 25446; July 6, 1988). These wastes 

may contain hazardous substances. 

Naturally occurring radioactive materials 

(NORM) — naturally occurring material that 

emits low levels of radioactivity, originating 

from processes not associated with the 

recovery of radioactive material. The 

radionuclides of concern in NORM are 

Radium-226, Radium-228, and other isotopes 

in the radioactive decay chains of uranium and 

thorium. 

Offloading — Unloading liquid cargo, crude oil, 

or refined petroleum products. 

Operational discharge — Any incidental 

pumping, pouring, emitting, emptying, or 

dumping of wastes generated during routine 

offshore drilling and production activities. 

Operator — An individual, partnership, firm, or 

corporation having control or management of 

operations on a leased area or portion thereof. 

The operator may be a lessee, designated 

agent of the lessee, or holder of operating 

rights under an approved operating agreement. 

Organic matter — Material derived from living 

plants or animals. 

Outer Continental Shelf (OCS) — All 

submerged lands that comprise the continental 

margin adjacent to the United States and 

seaward of State offshore lands. 

Pelagic — Of or pertaining to the open sea; 

associated with open water beyond the direct 

influence of coastal systems. 

Penaeids — Chiefly warm water and tropical 

prawns belonging to the family Penaeidae. 

Plankton — Passively floating or weakly motile 

aquatic plants (phytoplankton) and animals 

(zooplankton). 

Platform — A steel or concrete structure from 

which offshore development wells are drilled. 

Play — A prospective subsurface area for 

hydrocarbon accumulation that is 

characterized by a particular structural style or 

depositional relationship. 

Primary production — Organic material 

produced by photosynthetic or chemosynthetic 

organisms. 

Produced water — Total water discharged from 

the oil and gas extraction process; production 

water or production brine. 

Production — Activities that take place after the 

successful completion of any means for the 

extraction of resources, including bringing the 

resource to the surface, transferring the 

produced resource to shore, monitoring 

operations, and drilling additional wells or 

workovers. 

Province — A spatial entity with common 

geologic attributes. A province may include a 

single dominant structural element such as a 

basin or a fold belt, or a number of contiguous 

related elements. 

Ram — The main component of a blowout 

preventer designed to shear casing and tools in 

a wellbore or to seal an empty wellbore. A 

blind shear ram accomplishes the former and a 

blind ram the latter.

Recoverable reserves — The portion of the 

identified hydrocarbon or mineral resource 

that can be economically extracted under 

current technological constraints. 

Recoverable resource estimate — An assessment 

of hydrocarbon or mineral resources that takes 

into account the fact that physical and 

technological constraints dictate that only a 

portion of resources can be brought to the 

surface. 

Recreational beaches — Frequently visited, 

sandy areas along the Gulf of Mexico 

shorefront that support multiple recreational 

activities at the land-water interface. Included 

are National Seashores, State Park and 

Recreational Areas, county and local parks, 

urban beachfronts, and private resorts. 

Refining — Fractional distillation of petroleum, 

usually followed by other processing (for 

example, cracking). 

Relief — The difference in elevation between the 

high and low points of a surface. 

Reserves — Proved oil or gas resources. 

Rig — A structure used for drilling an oil or gas 

well. 

Riser insertion tube tool — A “straw” and gasket 

assembly improvised during the Macondo spill 

response that was designed to siphon oil and 

gas from the broken riser of the Deepwater 
8-8 Central Planning Area Supplemental EIS

Horizon lying on the sea bottom (an early 

recovery strategy for the Macondo spill in 

May 2010). 

Royalty — A share of the minerals produced from 

a lease paid in either money or “in-kind” to the 

landowner by the lessee. 

Saltwater intrusion — Saltwater invading a body 

of freshwater. 

Sciaenids — Fishes belonging to the croaker 

family (Sciaenidae). 

Seagrass beds — More or less continuous mats of 

submerged, rooted, marine, flowering vascular 

plants occurring in shallow tropical and 

temperate waters. Seagrass beds provide 

habitat, including breeding and feeding 

grounds, for adults and/or juveniles of many 

of the economically important shellfish and 

finfish. 

Sediment — Material that has been transported 

and deposited by water, wind, glacier, 

precipitation, or gravity; a mass of deposited 

material. 

Seeps (hydrocarbon) — Gas or oil that reaches 

the surface along bedding planes, fractures, 

unconformities, or fault planes. 

Sensitive area — An area containing species, 

populations, communities, or assemblages of 

living resources, that is susceptible to damage 

from normal OCS-related activities. Damage 

includes interference with established 

ecological relationships. 

Shear ram — The component in a BOP that cuts, 

or shears, through the drill pipe and forms a 

seal against well pressure. Shear rams are 

used in floating offshore drilling operations to 

provide a quick method of moving the rig 

away from the hole when there is no time to 

trip the drill stem out of the hole. 

Shunting — A method used in offshore oil and 

gas drilling and production activities where 

expended cuttings and fluids are discharged 

through a downpipe, which terminates no 

more than 10 m from the ocean floor, rather 

than discharged at the ocean surface. 

Shoreline Cleanup and Assessment Team — 

The on-the-scene responders for post-spill 

shoreline protection who established priorities, 

standardized procedures and establish 

terminology.

Spill of National Significance — Designation by 

the USEPA Administrator under 40 CFR 

300.323 for discharges occurring in the inland 

zone and the Commandant of the CG for 

discharges occurring in the coastal zone, 

authorizing the appointment of a National 

Incident Commander for spill-response 

activity. 

State coastal zone boundary — The State coastal 

zone boundaries for each CZMA-affected 

State are defined at http://

coastalmanagement.noaa.gov/mystate/docs/

StateCZBoundaries.pdf. 

Structure — Any OCS facility that extends from 

the seafloor to above the waterline; in 

petroleum geology, any arrangement of rocks 

that may hold an accumulation of oil or gas. 

Subarea — A discrete analysis area. 

Subsea isolation device — An emergency 

disconnection and reconnection assembly for 

the riser at the seafloor.

Supply vessel — A boat that ferries food, water, 

fuel, and drilling supplies and equipment to an 

offshore rig or platform and returns to land 

with refuse that cannot be disposed of at sea. 

Taking — To harass, harm, pursue, hunt, shoot, 

wound, kill, trap, capture, or collect any 

endangered or threatened species, or to 

attempt to engage in any such conduct 

(including actions that induce stress, adversely 

impact critical habitat, or result in adverse 

secondary or cumulative impacts). 

Harassments are the most common form of 

taking associated with OCS Program 

activities. 

Tension-leg platform (TLP) — A production 

structure that consists of a buoyant platform 

tethered to concrete pilings on the seafloor 

with flexible cable. 

Top hat — A short cylindrical sleeve with a 

tapered apex designed to fit atop of the lower 

marine riser package and to capture oil and 

gas from the flowing Macondo well (a 

functional subsurface recovery strategy for the 

Macondo spill in June and July, before the 

well was capped on July 15, 2010). 

Top kill — A wild well-control procedure 

involving the pump-down under pressure of 

heavy drilling fluid to equalize pressure and to 

stop the flow of gas and oil exiting a blowout 
Glossary 8-9 

(an early well control strategy for the 

Macondo spill deployed in May 2010). 

Total dissolved solids — The total amount of 

solids that are dissolved in water.

Total suspended particulate matter — The total 

amount of suspended solids in water. 

Total suspended solids — The total amount of 

suspended solids in water. 

Trunkline — A large-diameter pipeline receiving 

oil or gas from many smaller tributary 

gathering lines that serve a large area; 

common-carrier line; main line. 

Turbidity — Reduced water clarity due to the 

presence of suspended matter. 

Unified Area Command — A system of satellite 

work, coordination, and remediation stations 

administered by the Unified Incident 

Commander during a spill of national 

significance. 

Unified Incident Command — Command and 

coordination center for the National Incident 

Commander.

Volatile organic compound (VOC) — Any 

organic compound that is emitted to the 

atmosphere as a vapor. 

Water test areas — Areas within the Eastern Gulf 

where Department of Defense research, 

development, and testing of military planes, 

ships, and weaponry take place. 

Weathering (of oil) — The aging of oil due to its 

exposure to the atmosphere, causing marked 

alterations in its physical and chemical 

makeup. 
APPENDICES
APPENDIX A 

 

FIGURES AND TABLES
Figures and Tables A-3 

Eastern

 Planning

 Area

Central Planning Area

Western Planning Area

TEXAS

GEORGIA

FLORIDA

LOUISIANA

MISSISSIPPI ALABAMA

60 m

800 m

200 m

400 m

1600 m

2400 m

VENICE

MORGAN

CITY

HOUMA

BROWNSVILLE

CORPUS

CHRISTI TAMPA

HOUSTON

PORT

ARTHUR

BEAUMONT NEW

ORLEANS LAKE

CHARLES

LAFAYETTE PANAMA

CITY

PENSACOLA

MOBILE

TALLAHASSEE

NAPLES

Planning Area Proposed Sale Area

0 100 200 Kilometers

0 100 200 Miles

Figure 1-1. Gulf of Mexico Outer Continental Shelf Planning Areas, Proposed Lease Sale Area, and Locations 

of Major Cities. 

CENTRAL PLANNING AREA

LOUISIANA

MISSISSIPPI ALABAMA

FL

Macondo

Well Site

TEXAS

WESTERN PLANNING AREA

0 200

Kilometers

0 200

Planning Area Miles

Proposed Lease Sale 216/222

Figure 1-2. Location of the Macondo Well in the Gulf of Mexico’s Central Planning Area. 
A-4 Central Planning Area Supplemental EIS

Eastern

 Planning

 Area

Central Planning Area

Western Planning Area

TEXAS

GEORGIA

FLORIDA

LOUISIANA

MISSISSIPPI ALABAMA

VENICE

MORGAN

CITY

HOUMA

BROWNSVILLE

CORPUS

CHRISTI TAMPA

HOUSTON

PORT

ARTHUR

BEAUMONT NEW

ORLEANS LAKE

CHARLES

LAFAYETTE PANAMA

CITY

PENSACOLA

MOBILE

TALLAHASSEE

NAPLES

14 21

19 20 18

17

16

15

13

12

11

10

9

8

7

6

5

4

3

2

1

Planning Area Grids

0 100 200 Kilometers

0 100 200 Miles

Figure 1-3. Grid Areas of Remotely Operated Vehicle Surveys in Deep Water from NTL 2008-G06. 

Topographic

Features

Blocks

Topographic Features Blocks

1.4-Nautical-Mile 

Buffer Zone

Blocks Beyond

U.S. Exclusive

Economic Zone

Pinnacle Trend

Blocks

Blocks within

15 Miles of

Baldwin County,

Alabama

Central Planning Area

Western Planning Area

TEXAS

LOUISIANA

MISSISSIPPI ALABAMA

60 m

800 m

400 m

200 m

1600 m

2400 m

0 100 200 Kilometers

0 100 200 Miles

Proposed Sale Area

Topographic Feature Stipulation Block

Pinnacle Trend Stipulation Block

Blocks Within 15 Miles of Baldwin County,

Alabama, Coast

Blocks Beyond U.S. Exclusive Economic Zone

(northern portion of the Eastern Gap)

1.4 Nautical Mile Buffer Zone North of the

Continental Shelf Boundary Between the 

U.S. and Mexico

Deferred Area East of Military Mission Line

Deferred Area Required by GOMESA of 2006

Figure 2-1. Location of Proposed Stipulations and Deferrals. 
Figure 2-2. Economic Impact Areas in the Gulf of Mexico. 
Eastern Planning Area Central Planning Area Western Planning Area TEXAS GEORG

LOUISIANA MISSISSIPPI ALABAMA VENICE MORGAN CITY HOUMA BROWNSVILLE CORPUS CHRISTI 

HOUSTON PORT ARTHUR BEAUMONT NEW ORLEANS LAKE CHARLES LAFAYETTE PANAMA CITY PENSACOLA MOBILE TALLAHASSEE 

W-155 W-453 W-470 W-59 W-147 EWTA-1 W-151 W-92 EWTA-3 EWTA-2 W-228 W-602 W-168 EWTA-4 EWTA-5 W-174 EWTA-6 W-147 0 100 200 Kilometers 0 100 200 Miles Military Warning Area Boundary Military Mission Line Planning Area Proposed Sale Area Figure 2-3. Military Warning Areas and Eglin Water Test Areas Located in the Gulf of Mexico. 
W 0-60m W 1600-2400mW 800-1600m W >2400m W 200-400m W 400-800m W 60-200m C 0-60m (Western) C 60-200m C 800-1600m (Western) C 1600-2400m C >2400m 

C 0-60m (Eastern) 

TEXAS LOUISIANA MISSISSIPPI A

0 100 200 Kilometers 0 100 200 Miles Figure 3-1. Offshore Subareas in the Gulf of Mexico. 
A-8 Central Planning Area Supplemental EIS

WESTERN

PLANNING

AREA

CENTRAL PLANNING AREA

TEXAS LOUISIANA

MISSISSIPPI

0 50 100 Kilometers

0 50 100 Statute Miles

BOEMRE Transitioning OCS Pipeline

State of Louisiana Pipeline

Refinery

Port

Terminal

Figure 3-2. Pipelines Transitioning from Federal OCS and Louisiana State Waters. 

Eastern

 Planning

 Area

Central Planning Area

Western Planning Area

TEXAS

GEORGIA

FLORIDA

LOUISIANA

MISSISSIPPI ALABAMA

VENICE

MORGAN

CITY

HOUMA

BROWNSVILLE

CORPUS

CHRISTI TAMPA

HOUSTON

PORT

ARTHUR

BEAUMONT NEW

ORLEANS LAKE

CHARLES

LAFAYETTE PANAMA

CITY

PENSACOLA

MOBILE

TALLAHASSEE

NAPLES

USEPA/BOEMRE Air Quality 

Jurisdictional Boundary Planning Area Proposed Sale Area

BOEMRE

Air Quality Jurisdiction

USEPA Air Quality

Jurisdiction

0 100 200 Kilometers

0 100 200 Miles

Figure 3-3. Air Quality Jurisdiction. 
Figures and Tables A-9 

Figure 3-4. OCS-Related Service Bases in the Gulf of Mexico. 
Figure 3-5. Major Ports and Domestic Waterways in the Gulf of Mexico. 
Figures and Tables A-11 

Henderson

Lloyd Ridge

Walker Ridge

Destin Dome

Garden Banks Green Canyon

De Soto Canyon

Keathley Canyon

Mississippi Canyon

Florida Plain

Lund South

Pensacola

High

Island

Area

Amery Terrace Amery Terrace

Mobile

Viosca Knoll

Viosca Knoll

Sigsbee Escarpment

Ewing Bank

Vermilion

Area Eugene

Island

Area Ship

Shoal

Area

West

Cameron

Area

East

Cameron

Area

South

Timbalier

Area

High

Island

Area,

South

Addition

Main

Pass

Area

West

Cameron

Area,

South

Addition

Vermilion

Area,

South

Addition

West

Delta

Area West

Cameron

Area,

West

Addition Grand

Isle

Area

Ship Shoal Area,

South Addition

Main

Pass

Area,

South

and

East

Addition

East

Cameron

Area,

South

Addition

Eugene Island Area,

South Addition

High

Island

Area,

East

Addition

High

Island

Area,

East

Addition,

South

Extension

South

Marsh

Island

Area,

South

Addition

South

Marsh

Island

Area

South Tim balier Area,

South Addition

South

Marsh

Island

Area,

North

Addition

Chandeleur

Area

South Pass Area

South

Pelto

Area

West Delta Area,

South Addition

Grand

Isle

Area,

South

Addition

Ewing

Bank

Sabine Pass Area (LA)

South Pass Area,

South and East Addition

Breton Sound Area

Chandeleur Area,

East Addition East Addition

Sabine Pass Area (TX)

Baldwin

Lafourche

Terrebonne

Calcasieu Hardin

Mobile

Jefferson Vermilion

Jackson

Okaloosa

Harrison Livingston St. Tammany

Iberia

Santa Rosa

Cameron

Pearl River Stone

Orange

George

East

Baton

Rouge

St. Mary St. Martin

Assumption

Ascension

St. John

the Baptist

Tangipahoa

St. Bernard

Orleans

St. Charles

Hancock

Plaquemines

Escambia

St. James

WESTERN

PLANNING AREA

CENTRAL PLANNING AREA

TEXAS LOUISIANA

* USCG Data Used as Oil Spill Events Source for the Gulf of Mexico Region

MISSISSIPPI

ALABAMA FLORIDA

Jefferson

EASTERN

PLANNING AREA

0 50 100 Kilometers

0 50 100 Statute Miles

Oil Spill Events* (2008)

Central Planning Area

Gulf of Mexico OCS

# of Spill Events = 487

Spill Amount = 293 bbl

<1 bbl

1 - 9.99 bbl

10 - 49.9 bbl

50+ bbl

Figure 3-6. Oil-Spill Events (2008) in the Central Planning Area (Dickey, personal communication, 2010). 
A-12 Central Planning Area Supplemental EIS

Status of counties and parishes is based on USEPA Ozone Nonattainment State/Area/County Report, April, 2011 (USEPA, 2011)

TEXAS

LOUISIANA

MISSISSIPPI ALABAMA

FLORIDA

Central Planning Area Western Planning Area

Eastern

Planning

Area

Collin

Ellis

Kaufman

Galveston

Johnson

Montgomery

Brazoria

Tarrant

Fort

Bend

Harris

Chambers

Rockwall

Liberty

Parker

Waller

Dallas

Denton

East

Baton

Rouge

Iberville

Livingston

Ascension

West

Baton

Rouge

Ozone Non-attainment Area

0 100 200 Kilometers

0 100 200 Miles

Figure 4-1. Status of Ozone Attainment in Coastal Counties and Parishes of the Central and Western 

Planning Areas (USEPA, 2011). 

Figure 4-2. Coastal and Marine Waters of the Gulf of Mexico with Selected Rivers and Water Depths. 
TEXAS

GEORGIA

LOUISIANA

MISSISSIPPI ALABAMA

VENICE

MORGANCITY

HOUMA

BROWNSVILLE

CORPUSCHRISTI 

HOUSTON

PORTARTHUR

BEAUMONT NEW

ORLEANS

LAKECHARLES

LAFAYETTE

PANAMACITY

PENSACOLA

MOBILE

TALLAHASSEE

Seagrass Area 

0 100 200 Kilometers0 100 200 Miles

Gulf of Mexico

Figure 4-3. Seagrass Locations of the Northern Gulf of Mexico. 
A-14 Central Planning Area Supplemental EIS

TAMPA

NAPLES

PANAMA CITY TALLAHASSEE

PENSACOLA

60 m

200 m

400 m

800 m

1600 m

2400 m

Florida FLORIDA

Middle

Grounds

Steamboat Lumps 

Special Management 

Area

Madison and Swanson 

Special Management Area

Sticky Ground

Mounds

Eastern

Planning

Area

Central

Planning

Area

Pulley

Ridge

Live Bottom (Low Relief)

Live Bottom (Pinnacle Trend)

Proposed Sale Area

Representative Eastern Planning Area

High-Relief Live Bottoms

0 100 200 Kilometers

0 100 200 Miles

Figure 4-4. Live Bottoms (Low Relief and Pinnacle Trend) in the Central and Eastern Planning Areas. 
Figures and Tables A-15 

Figure 4-5. Perspective Sketch of the Submerged Landscape of a Pinnacle Province as Visualized 

from Sidescan Sonar and Remotely Operated Vehicle Information (Brooks and 

Giammona, 1990). 
A-16 Central Planning Area Supplemental EIS 

Figure 4-6. Sketch of a Submerged Ridge (Brooks and Giammona, 1990). 
Figures and Tables A-17 

Figure 4-7. Location of the 36 Fathom Ridge within the Alabama Alps Formation (A & B) (Gardner et al., 

2002) and Oblique View of the 36 Fathom Ridge within the Alabama Alps (C) (Weaver et al., 

2002). 
A-18 Central Planning Area Supplemental EIS 

Figure 4-8. Location of Roughtongue Reef (A & B) (Gardner et al., 2002) and Oblique View of 

Roughtongue Reef (C) (Weaver et al., 2002). 
Figures and Tables A-19 

Figure 4-9. Location of Some Mapped Low-Relief, Hard-Bottom Areas and Pinnacles on the Alabama-Florida 

Continental Shelf (Schroeder et al., 1988). 
A-20 Central Planning Area Supplemental EIS 

Figure 4-10. Block-Like, Hard-Bottom Substrate North of the Head of De Soto Canyon (Shipp 

and Hopkins, 1978). 
Figures and Tables A-21 

2400 m

1600 m

800 m

400 m

200 m

60 m

TEXAS

LOUISIANA

EAST FLOWER

GARDEN BANK

29 FATHOM

BANK

32 FATHOM BANK

EWING BANKS

SACKETT BANK

PARKER DIAPHUS BANK

BANK

JAKKULA BANK

FISHNET

BANK

SWEET BANK REZAK

BANK

COFFEE LUMP

BANK

STETSON BANK

BIG DUNN

BAR BANK SMALL DUNN 

BAR BANK

BAKER SOUTH BAKER

BANK

MYSTERIOUS

BANK

NORTH 

HOSPITAL

BANK

SOUTHERN

BANK

HOSPITAL BANK

ARANSAS BANK

DREAM

BANK BLACKFISH 

RIDGE

CLAYPILE 

BANK

APPELBAUM BANK

WEST FLOWER 

GARDEN BANK

ELVERS BANK

GEYER BANK

BRIGHT BANK

MACNEIL BANK

SIDNER

BANK

BOUMA BANK

ALDERDICE

SONNIER BANK

BANK

MCGRAIL

BANK

RANKIN BANKS

Central Planning Area

Western Planning Area

0 100 200 Kilometers

0 100 200 Miles Topographic Feature

Figure 4-11. Location of Topographic Features in the Gulf of Mexico. 
A-22 Central Planning Area Supplemental EIS 

Central Planning Area

Western Planning Area

TEXAS LOUISIANA

MISSISSIPPI ALABAMA

60 m 800 m

400 m

200 m

1600 m

2400 m

VENICE

MORGAN

CITY

HOUMA

BROWNSVILLE

CORPUS

CHRISTI

HOUSTON PORT

ARTHUR

BEAUMONT NEW

ORLEANS

LAKE

CHARLES

LAFAYETTE

PENSACOLA

MOBILE

0 100 200 Kilometers

Proposed Sale Area Known Chemosynthetic Community 0 100 200 Miles

Figure 4-12. Location of Known Chemosynthetic Communities in the Gulf of Mexico. 
Figures and Tables A-23 

238

289

494

598

660

815

1032

1073 1086 1107 1122 1125 1129 1129 1135 1144 1144

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

5/28/10

6/6/10

6/20/10

7/4/10

7/15/10

8/1/10

8/14/108/31/10

9/7/10

9/14/109/21/109/28/1010/4/1010/6/10

10/12/1010/27/10

11/2/10

Date

# Collected

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48

50

% Change

Figure 4-13. Summary of Sea Turtles Collected by Date Obtained from the Consolidated Numbers of Collected 

Fish and Wildlife That Have Been Reported to the Unified Area Command from the U.S. Fish and 

Wildlife Service, National Oceanic and Atmospheric Administration, Incident Area Commands, 

Rehabilitation Centers, and Other Authorized Sources Operating within the Deepwater Horizon/BP 

Incident Impact Area through November 2, 2010. (Data on the Y-axis reflects the cumulative 

number of individual sea turtles collected by date [alive and dead] and data on the Z-axis reflects 

proportional change from one reporting date to the next. For the latest available information on oiled 

or affected sea turtles documented in the area, event response, and daily maps of the current location 

of spilled oil, see RestoreTheGulf.gov, 2011). 
A-24 Central Planning Area Supplemental EIS 

4676

4943

5303

5697 5833

6359

6844

7267

7651 7835 8000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

9/14/20109/21/20109/28/201010/3/201010/6/2010

10/12/201010/20/201010/27/2010

11/3/2010

11/16/201011/30/2010

Date

# Collected

0

1

2

3

4

5

6

7

8

9

% Chang

e

Figure 4-14. Summary of Avian Species Collected by Date Obtained from the U.S. Fish and Wildlife Service 

(FWS) as Part of the NRDA Process through November 30, 2010. (Data on the Y-axis reflects the 

cumulative number of individual birds collected, identified, and summarized by date; data on the Zaxis reflects proportional change from one reporting date to the next. The data used in this table are 

verified as per the FWS QA/QC processes. Disclaimer: All data should be considered provisional, 

incomplete, and subject to change. For more information, see USDOI, FWS, 2010). 
TEXAS LOUISIANA MIS

- Termina- Waste F- Supply B- Ship Re- Refineri- Ports - Platform Fabrication - Pipecoating - Petrochemical Facilities - Natural Gas Storage - Heliports - Electric Generators Oil and Gas Related Infrast

0 100 200Kilometers 0 100 200Miles * 2009 U.S. Census Data Poverty Range* 34 - 42% 27 - 33% 21 - 26% 14 - 20% 7 - 13% Figure 4-15. Locations of Oil- and Gas-Related Infrastructure and the Distribution of Low-Income Residents across Counties and 

Louisiana based on U.S. Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in preparation). 
MISSISSIPPI LOUISIANA ALABAMA GEORGIA 

0 100 200Kilometers 0 100 200Miles - Terminals - Waste Facilities - Supply Bases - Ship Repair Yards - Refineries - Ports - Platform Fabrication - Pipecoating - Petrochemical Facilities - Natural Gas Storage - Heliports - Electric Generators Oil and Gas Related Infrastructure * 2009 U.S. Census Data Poverty Range* 27 - 33% 21 - 26% 14 - 20% 7 - 13% Figure 4-16. Locations of Oil- and Gas-Related Infrastructure and the Distribution of Low-Income Residents across Counties in 

and Florida based on U.S. Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in preparation). 
TEXAS

LOUISIANA MIS

- Termina- Waste F- Supply B- Ship Re- Refineri- Ports

- Platform Fabrication- Pipecoating- Petrochemical Facilities- Natural Gas Storage- Heliports- Electric Generators

Minority Range* Oil and Gas Related Infrast

* 2010 U.S. Census Data

5 - 25%26 - 46%47 - 67%68 - 88%89 - 100%

0 100 200

Kilometers

0 100 200

Miles

Figure 4-17. Locations of Oil- and Gas-Related Infrastructure and the Distribution of Minority Residents across Counties and P

Louisiana based on U.S. Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in preparation). 
MISSISSIPPI LOUISIANA ALABAMA GEORGIA 

0 100 200Kilometers 0 100 200Miles - Terminals - Waste Facilities - Supply Bases - Ship Repair Yards - Refineries - Ports - Platform Fabrication - Pipecoating - Petrochemical Facilities - Natural Gas Storage - Heliports - Electric Generators Minority Range* Oil and Gas Related Infrastructure * 2010 U.S. Census Data 5 - 25% 26 - 46% 47 - 67% 68 - 88% Figure 4-18. Locations of Oil- and Gas-Related Infrastructure and the Distribution of Minority Residents across Counties in Miss

Florida based on U.S. Census Data from 2009 (USDOC, Census Bureau, 2010; Dismukes, in preparation). 
Harris Cameron Baldwin Mobile Miam

Terrebonne Vermilion Lafourche Jackson Okaloosa Plaquemines St. Mary Hillsborough Harrison Jefferson Jefferson Davis Galveston Ascension TEXAS LOUISIANA MISSISSIPPI ALABAMA GEORGIA 

ARKANSAS 

0 100 200Kilometers 0 100 200Miles * 2010 NOAA Deepwater Horizon Data Waste Disposal Sites per County/Parish 5 + 3 - 4 1 - 2 Deepwater Horizon W aste Disposal Sites* Figure 4-19. Location of All Deepwater Horizon Waste Disposal Sites (USDOC, NOAA, 2011; USEPA and British Petr

Petroleum, 2011a and 2011b). 
$43,597 $67,753 $71,300 $79,900 $106,458 $226,700 Harris County, TX Hidalgo County., TX Matagorda County, TX Jim Wells County, TX Lafayette County, FL West Baton Rouge Parish, LA TEXAS LOUISIANA MISSISSIPPI ALABAMA GEORGIA 

OKLAHOMA ARKANSAS 

0 100 200Kilometers 0 100 200Miles Average Payout per Claimant* * 2011 Gulf Coast Claims Facility Data N/A $3,250 - 12,159 $12,160 - 18,759 $18,760 - 25,359 $25,360 - 31,959 $31,960 - 38,559 $38,600 - 226,700 Figure 4-20. Distribution of the Gulf Coast Claims Facility’s Claimants and the Average Amount Paid to Each Claimant across G

and Parishes (Gulf Coast Claims Facility, 2011). 
Figures and Tables A-31 

Table 1-1 

 

Emergency 30 CFR 250 Subpart D Interim Final Rule Provisions 

Regulation Summary Existing 

Requirement New Requirement Cost 

Requires the operator to evaluate 

the best practices according to 

API RP 65-Part 2 and submit a 

written description for the 

evaluation. 

Written description must include 

the mechanical barriers and 

cementing practices the operator 

will use for each casing string. 

30 CFR 

§250.415(f) 

Evaluate best 

practices in 

API RP 65-

Part2 

No evaluation 

required 

API RP 65 Part 2 addresses 

cementing practices and factors 

affecting cementing success. 

No meaningful cost 

Schematics of all control systems, 

including primary controls, 

secondary controls, and pods for 

the BOP system must be 

submitted. 

30 CFR 

§250.416(d) 

Submittal of 

schematics of 

all control 

systems for 

BOP stack 

Schematic of BOP 

system showing 

inside diameter of 

BOP stack, number 

and type of 

preventers, location 

of choke and kill 

lines 

Location of the controls must be 

included 

No meaningful cost 

Information that the 

blind-shear ram is 

capable of shearing 

the pipe 

Verification that the blind-shear 

rams installed in the BOP stack 

are capable of shearing the drill 

pipe in the hole under maximum 

anticipated surface pressure. 

Independent thirdparty certification 

will require a small 

cost per well 

Independent third party must be a 

technical classification society or 

an API licensed manufacturing, 

inspection, certification firm, or 

licensed professional engineering 

firm. 

30 CFR 

§250.416(e) 

Independent 

third party 

verification 

to ensure 

blind-shear 

rams are 

capable of 

cutting the 

drill pipe 

used 

No independent 

third-party 

certification 

required 

Independent third-party must not 

be the OEM. 

Will add moderate 

costs 

30 CFR 

§250.418(i) 

Submit 

qualifications 

of 

independent 

third parties 

with APD 

No independent 

third-party 

certification 

required 

Description of qualifications in 

accordance with §250.416 (e) 

No meaningful cost 
A-32 Central Planning Area Supplemental EIS 

Table 1-1. Emergency 30 CFR 250 Subpart D Interim Final Rule Provisions (continued). 

Regulation Summary Existing 

Requirement New Requirement Cost 

PE will verify there are two 

independent barriers 

Small cost per well 

if performed by an 

independent third 

party 

No cost if PE 

certification is done 

in house 

30 CFR 

§250.420(a) 

(6) 

Professional 

Engineer 

verification 

of well casing 

and 

cementing 

program 

No PE verification 

required 

Verify the casing cementing 

design is appropriate for the 

purpose it was intended under 

expected wellbore conditions Assumed that some 

majors would 

verify in-house; 

smaller operators 

will use third party 

Estimated that 80% 

of wells already use 

dual mechanical 

barriers 

Installation of dual 

mechanical barriers 

is estimated to take 

21 hours 

30 CFR 

§250.420(b) 

(3) 

Dual 

mechanical 

barriers 

No requirement Operator must install dual 

mechanical barriers in addition to 

cement in the final casing string 

and document to BOEMRE. 

Dual float valves, or one float 

valve and a mechanical plug. 

Will add significant 

costs to regulation 

Perform a pressure 

test on all casing 

strings (except 

drive/structural) 

according to 

250.423 (a) 

Pressure tests are 

already required, no 

extra equipment 

time 

Each pressure test 

only takes a few 

minutes 

30 CFR 

§250.423(b) 

(2) 

Pressure test 

on the casing 

seal assembly 

No requirement to 

ensure proper 

installation of the 

casing in the subsea 

wellhead 

Additional pressure test for the 

intermediate and production 

casing strings on the casing seal 

assembly to ensure proper 

installation of the casing in the 

subsea wellhead. 

No meaningful cost 

Negative pressure 

test will take 90 

minutes for each 

required string of 

casing 

30 CFR 

§250.423(c) 

Negative 

pressure test 

No negative 

pressure test 

required 

Perform a negative pressure test to 

ensure proper installation of 

intermediate and production 

casing strings 

Will result in 

significant costs for 

the regulation 

30 CFR 

§250.442(e) 

Maintain 

ROV and a 

trained crew 

ROV’s used for 

visual inspection 

every 3 days; 

250.446(b) 

Required to maintain an ROV and 

trained crew on each floating rig 

on a continuous basis. 

All rigs are 

assumed to have an 

ROV on board. 

This regulation will 

not add additional 

costs. 
Figures and Tables A-33 

Table 1-1. Emergency 30 CFR 250 Subpart D Interim Final Rule Provisions (continued). 

Regulation Summary Existing 

Requirement New Requirement Cost 

 ROV must be capable of shutting 

in the well during emergency 

situations 

Regulation does not 

require a timed test, 

therefore current 

ROV’s will be 

capable of 

performing all 

required functions. 

30 CFR 

§250.442(f) 

Provide an 

autoshear and 

deadman 

system for 

dynamically 

positioned 

rigs 

No 

autoshear/deadman 

system requirement 

All dynamically positioned rigs 

must have an autoshear and 

deadman system 

Industry standard 

for dynamically 

positioned rigs to 

have 

autoshear/deadman 

systems 

No meaningful cost 

30 CFR 

§250.442(g) 

Barriers on 

BOP control 

panels to 

prevent 

accidental 

disconnect 

functions 

No two-handed 

requirement 

Incorporate enable buttons on 

control panels to ensure 2-handed 

operations for all critical 

functions. 

No meaningful cost 

30 CFR 

§250.442(h) 

Label subsea 

BOP control 

panel 

No labeling 

requirement 

Clearly label all control panels, 

such as hydraulic control panels 

and ROV interface on the BOP 

No meaningful cost 

Develop and use a management 

system for operating the BOP 

system 

Written procedures for operating 

the BOP stack and LMRP 

30 CFR 

§250.442(i) 

Develop 

management 

system for 

BOP 

No management 

requirement 

Minimum knowledge 

requirements for personnel 

authorized to operate and maintain 

critical BOP components 

No meaningful cost 

30 CFR 

§250.442(j) 

Training for 

BOP 

equipment 

No training 

requirement 

Train BOP personnel in deepwater 

well control theory and practice in 

accordance with 30 CFR 250, 

Subpart O 

No meaningful cost 

30 CFR 

§250.446(a) 

Document 

maintenance 

and 

inspections to 

BOP system 

No documentation 

requirement 

BOP maintenance and inspections 

must meet or exceed provisions of 

Sections 17.10 and 18.10 

No meaningful cost 

30 CFR 

§250.449(j) 

Subsea 

function test 

for ROV 

intervention 

No initial test on the 

seafloor 

All ROV intervention functions 

must be tested during the stump 

test and one set of rams during the 

initial test on the seafloor 

Initial test on the 

seafloor is not 

industry standard 
A-34 Central Planning Area Supplemental EIS 

Table 1-1. Emergency 30 CFR 250 Subpart D Interim Final Rule Provisions (continued). 

Regulation Summary Existing 

Requirement New Requirement Cost 

ROV hot stabs must be function 

tested and capable of actuating at 

least 1 set of pipe rams, 1 set of 

blind-shear rams and unlatching 

the LMRP 

on a subsea 

BOP stack 

Stump test for 

subsea BOP stack 

Operator must examine all surface 

and subsea well-control 

equipment to ensure that it is 

properly maintained and capable 

of shutting in the well during 

emergency operations 

ROV seafloor test 

is estimated to take 

about 24 hours 

Will add significant 

costs 

30 CFR 

§250.449(k) 

Autoshear/ 

deadman 

function test 

No required 

function test 

The autoshear and deadman 

systems must be function tested 

during the stump test and during 

the initial test on the seafloor. 

No meaningful cost 

30 CFR 

§250.451(i) 

Emergency 

activation of 

blind or 

casing shear 

rams 

No required action If the blind-shear or casing shear 

rams are activated in a well 

control situation, the BOP must be 

retrieved and fully inspected and 

tested 

Emergency 

situation only, will 

incur significant 

loss of rig time 

Approval required from District 

Manager before displacing killweight drilling fluid from the 

wellbore 

Submit reasons for displacing and 

provide detailed procedures of 

displacement process. 

30 CFR 

§250.456(j) 

District 

Manager 

approval for 

displacing 

kill-weight 

drilling fluid 

No approval 

requirement 

Follow procedures in 250.456 

No meaningful cost 

All ROV intervention functions 

must be tested during the stump 

test and 1 set of rams during the 

initial test on the seafloor 

ROV hot stabs must be function 

tested and capable of actuating at 

least 1 set of pipe rams, 1 set of 

blind-shear rams and unlatching 

the LMRP 

30 CFR 

§250.516(d) 

(8) 

Subsea 

function test 

for ROV 

intervention 

on a subsea 

BOP stack 

Stump test BOP 

stack before 

installation 

Operator must examine all surface 

and subsea well-control 

equipment to ensure that it is 

properly maintained and capable 

of shutting in the well during 

emergency operations 

Will add costs for 

well completions 

operations 
Figures and Tables A-35 

Table 1-1. Emergency 30 CFR 250 Subpart D Interim Final Rule Provisions (continued). 

Regulation Summary Existing 

Requirement New Requirement Cost 

All ROV intervention functions 

must be tested during the stump 

test and 1 set of rams during the 

initial test on the seafloor 

ROV hot stabs must be function 

tested and capable of actuating at 

least 1 set of pipe rams, 1 set of 

blind-shear rams and unlatching 

the LMRP 

30 CFR 

§250.616(h) 

(1) 

Subsea 

function test 

for ROV 

intervention 

on a subsea 

BOP stack 

Stump test BOP 

stack before 

installation 

Operator must examine all surface 

and subsea well-control 

equipment to ensure that it is 

properly maintained and capable 

of shutting in the well during 

emergency operations 

Will add costs for 

well workover 

operations 

Source: Federal Register, 2010. 

Table 2-1 

 

Presidential and Secretarial Inquiries Resulting from the Deepwater Horizon Event and Spill 

Initiator and Date Purpose Expected Outputs 

April 30, 2010 

President Obama 

Reported if additional precautions and 

technologies should be required to improve the 

safety of oil and gas operations on the OCS. 

The so-called “30-day Report” or 

“Safety Measures Report” was delivered 

to the Secretary on May 27, 2010 

(USDOI, 2010a). 

April 30, 2010 

Secretary Salazar 

Created OCS Safety Oversight Board (Board) to 

provide recommendations for improving and 

strengthening DOI’s overall management, 

regulation, and oversight of OCS operations, 

including undertaking further audits or reviews, 

and reviewing existing authorities and 

procedures. 

The Board delivered its report to the 

Secretary on September 1. It was made 

public with an implementation plan on 

September 8, 2010 (USDOI, 2010b). 

May 11, 2010 

Secretary Salazar 

Impaneled a review by the National Academy of 

Engineering (NAE) of the root causes of the 

Deepwater Horizon event and provide 

recommendations 

The NAE panel forecasts delivery of 

their final report that presents the 

Committee’s final analysis, including 

findings and/or recommendations, by 

June 1, 2011 (pre-publication version); a 

final published version will follow by 

December 30, 2011 (NAE and NRC, 

2011). 

May 21, 2010 

President Obama 

Created the National Commission on the BP 

Deepwater Horizon Oil Spill and Offshore 

Drilling to develop findings and 

recommendations within 6 months. 

The Commission delivered the Final 

Report to the President on January 11, 

2011 (Oil Spill Commission, 2011). 

May 25, 2010 

Secretary Salazar 

Requested that the DOI’s Office of the Inspector 

General investigate any deficiencies in 

BOEMRE policies and practices that may have 

contributed to the Deepwater Horizon event. 

The DOI’s Office of the Inspector 

General released its report on 

December 7, 2010 (USDOI, Office of 

the Inspector General, 2010). 
A-36 Central Planning Area Supplemental EIS 

Table 3-1 

 

Projected Oil and Gas in the Gulf of Mexico OCS 

Proposed Action OCS Program 

(2007-2046) 

Western Planning Area 

 Reserve/Resource Production 

 Oil (BBO) 0.222-0.423 6.629-8.060 

 Gas (Tcf) 1.495-2.647 52.211-59.961 

Central Planning Area 

 Reserve/Resource Production 

 Oil (BBO) 0.801-1.624 21.933-24.510 

 Gas (Tcf) 3.332-6.560 90.155-102.761 

BBO = billion barrels of oil 

Tcf = trillion cubic feet 

Table 3-2 

 

Offshore Scenario Information Related to a Proposed Action in the Central Planning Area 

Offshore Subareas1

 0-60 m 60-200 m 200-400 m 400-800 m 800-1,600 m 1,600-2,400 m >2,400 m Total CPA2

Wells Drilled 

 Exploration and Delineation Wells 17-23 9-14 6-14 9-17 11-24 7-16 6-13 65-121 

 Development and Production Wells 62-85 23-33 76-132 65-102 58-112 37-73 20-39 338-576 

 Producing Oil Wells 14-19 6-9 38-66 32-52 30-58 19-38 10-21 149-263 

 Producing Gas Wells 40-55 14-20 28-48 22-36 20-39 13-26 7-13 144-237 

Production Structures 

 Installed 20-25 2-3 2-3 2-3 1-4 2-3 3 32-44 

 Removed Using Explosives 14-17 2 2 0-1 0 0 0 23-32 

 Total Removed 18-23 2-3 2-3 2-3 1-4 2-3 3 30-42 

Length of Installed Pipelines (km)3 50-850 NA NA NA NA NA NA 130-2,075 

Service-Vessel Trips (1,000's round trips) 22-27 3-5 5-9 5-8 19-69 34-52 49-50 137-220 

Helicopter Operations (1,000 operations) 714-1,185 71-169 36-169 36-169 36-226 36-169 75-154 1,004-2,241

1

 See Figure 3-1. 

2

 Subareas totals may not add up to the planning area total because of rounding.

3

 Projected length of pipelines does not include length in State waters. 

NA = not available. 
Figures and Tables A-37 

Table 3-3 

 

Deepwater Rig Counts, Day Rates, and Annual Drill Rates in the Gulf of Mexico* 

Rig Type Number of Rigs Loaded Day Rate 

Drillship 11 $1,000,000 

Deep Semisubmersible 21 $923,953 

Low Semisubmersible 4 $715,792 

MODU Total or Weighted Average 36 $924,060 

Platform 10 $400,000 

* Current to August 2010. 

Table 3-4 

 

Oil Spilled from Pipelines on the Federal OCS, 2002-2009 

Regulator Area Total Oil Spilled 

(bbl) 

Oil Spilled due to 

Hurricanes (bbl) 

Proportion of Total due to 

Hurricanes (%) 

BOEMRE Federal OCS 5,522 5,179 94 

DOT Federal OCS 5,667 3,272 58 

DOT State Waters 9,903 9,622 97 

Source: USDOI, BOEMRE and DOT data. 

Table 3-5 

 

Mean Number and Sizes of Spills Estimated to Occur 

in OCS Offshore Waters from an Accident Related 

to Activities Supporting the Proposed Action Over a 40-Year Time Period 

Spill Size Group Spill Rate 

(spills/BBO) 1

Number of Spills Estimated for 

a WPA Proposed Action 2

Number of Spills Estimated for 

a CPA Proposed Action 2

Estimated 

Spill Size 1

0-1.0 bbl 3,357.31 745-1,420 2,690 -5,452 0.073

1.1-9.9 bbl 74.7 17-32 60-121 34

10.0-49.9 bbl 16.18 4-7 13-27 204

50.0-499.9 bbl 6.37 1-3 5-11 904

500.0-999.9 bbl 0.52 <1 <1-1 6404

1,000 bbl 1.51 <1-1 1-3 4,6004

10,000 bbl 0.39 <1 <1-1 15,0004

Notes: The number of spills estimated is derived by application of the historical rate of spills per volume crude oil 

handled (1985-1999) (Anderson and LaBelle, 2000) to the projected production for a proposed action in the 

WPA or CPA (Table 4-1). Projected production is an estimate of recoverable resource and is influenced by 

supporting infrastructure, as well as economic and technological factors. The actual number of spills that 

may occur in the future could vary from the estimated number. 

1 Source: Anderson and LaBelle, 2000. 

2 Source: Table 4-1. 

3 Average spill size. 

4 Median spill size. 
A-38 Central Planning Area Supplemental EIS 

Table 3-6 

 

Properties and Persistence by Oil Component Group 

Properties and Persistence Light-weight Medium-weight Heavy-weight 

Hydrocarbon compounds Up to 10 carbon atoms 10-22 carbon atoms >20 carbon atoms 

API o >31.1o 31.1o-22.3 o <22.3 o 

Evaporation rate Rapid (within 1 day) and 

complete 

Up to several days; not 

complete at ambient 

temperatures 

Negligible 

Solubility in water High Low (at most a few mg/L) Negligible 

Acute toxicity High due to monoaromatic 

hydrocarbons (BTEX) 

Moderate due to diaromatic 

hydrocarbons 

(naphthalenes—2 ring 

PAH’s) 

Low except due to 

smothering (i.e., heavier oils 

may sink) 

Chronic toxicity None, does not persist due 

to evaporation 

PAH components 

components (e.g., 

naphthalenes—2 ring 

PAH’s) 

PAH components (e.g., 

phenanthrene, anthracene—

3 ring PAH’s) 

Bioaccumulation potential None, does not persist due 

to evaporation 

Moderate Low, may bioaccumulate 

through sediment sorption 

Compositional majority Alkanes and cycloalkanes Alkanes that are readily 

degraded (specify, as done 

for others) 

Waxes, asphaltenes, and 

polar compounds (not 

significantly bioavailable or 

toxic) 

Persistence Low due to evaporation Alkanes readily degrade, 

but the diaromatic 

hydrocarbons are more 

persistent 

High; very low degradation 

rates and can persist in 

sediments as tarballs or 

asphalt pavements 

Sources: Michel, 1992; Canadian Center for Energy Information, 2010. 
Figures and Tables A-39 

Table 3-7 

 

Estimated Number of Spills that Could Happen in Gulf Coastal Waters 

from an Accident Related to Activities Supporting a Proposed Action 

Size Category Assumed Size 

WPA 

Proposed Action 

CPA 

Proposed Action 

Total 15-34 49-126 

1 bbl 1 bbl 12-29 44-114 

>1 bbl and <50 bbl 3 bbl 1-2 2-5 

50 bbl and <1,000 bbl 150 bbl 1-2 2-6 

1,000 bbl 3,000 bbl <1-1 <1-1 

Note: The estimated number of spills is obtained from the count of coastal spills for 2001 

proportioned to reflect that OCS oil comprised 19 percent of the oil crossing into 

GOM coastal waters in 2001. Intrastate oil and refined product transport were not 

included. The low estimate in the range was obtained from Dickey (personal 

communication, 2006) and the high estimate was obtained from aggregated 

national data available on the Internet (USDOT, Coast Guard, 2001). 

Sources: Dickey, personal communication, 2006; USDOT, Coast Guard, 2001; National 

Ocean Economics Program, 2006; USDOE, Energy Information Administration, 

2006. 

Table 3-8 

 

Primary Cleanup Options Used during the Deepwater Horizon Response

Fresh Oil Sheens Mousse Tarballs Burn Residue 

On-Water 

Response 

Disperse, skim, 

burn 

Light sheens 

very difficult to 

recover, heavier 

sheens picked up 

with sorbent 

boom or sorbent 

pads 

Skim Snare boom Manual removal 

On-Land 

Response 

Sorbent pads, 

manual 

recovery, 

flushing with 

water, possible 

use of chemical 

shoreline 

cleaning agents 

Light sheens 

very difficult to 

recover, heavier 

sheens picked up 

with sorbent 

boom or sorbent 

pads 

Sorbent pads, 

manual recovery 

Snare boom, 

manual removal, 

beach cleaning 

machinery 

Manual removal 

Source: USDOC, NOAA, 2010a. 
A-40 Central Planning Area Supplemental EIS 

Table 3-9 

 

Pipelines* Damaged after 2004-2008 Hurricanes Passing through the WPA and CPA 

Hurricane Total Damage 

Reports 

Pipe and 

Movement 

Platform 

Connection Riser Mudflow Outside Impact Unknown

Ivan 168 38 20 67 16 9 18 

Katrina 299 61 139 66 1 9 14 

Rita 243 31 94 89 0 8 21 

Gustav/Ike 314 14 2 273 2 7 16 

* Not discriminated by diameter. 

Sources: Energo Engineering, 2010; Atkins et al., 2007. 

Table 3-10 

 

Causes of Hurricane-Related Pipeline Spills Greater Than 50 Barrels 

Hurricane Amount Spilled (bbl) Cause 

Ivan 1,720 Mudflow 

Ivan 671 Movement 

Ivan 126 Platform 

Ivan 200 Platform 

Ivan 250 Platform 

Ivan 260 Platform 

Ivan 95 Movement 

Ivan 123 Movement 

Katrina 960 Movement 

Katrina 50 Platform 

Katrina 55 Riser 

Katrina 132 Mudslide 

Katrina 50 Movement 

Rita 75 Riser 

Rita 100 Outside Force 

Rita 862 Outside Force/Platform 

Rita 67 Platform 

Rita 108 Riser 

Ike 69 Movement 

Ike 108 Riser 

Ike 56 Platform 

Ike 1,316 Outside Force 

Ike 209 Riser 

Ike 268 Riser 

Source: USDOI, BOEMRE data. 
Figures and Tables A-41 

Table 3-11 

 

Total Producing Wells, Total Oil, and Total Gas Production in the Nine Coastal Parishes of Louisiana in 2009 

Parish Total Producing Wells Total Oil Produced (bbl) Total Gas Produced (Mcf) 

St. Bernard 114 666,757 12,662,442 

Plaquemines 1,734 16,870,508 74,737,520 

Jefferson 221 1,202,961 11,199,616 

Lafourche 539 5,769,795 35,366,426 

Terrebonne 569 5,984,437 93,070,163 

St. Mary 345 3,400,486 40,127,959 

Iberia 172 2,891,805 48,567,357 

Vermilion 249 3,062,983 63,928,992 

Cameron 323 3,278,189 57,276,938 

TOTAL 4,266 43,127,921 436,940,000 

Mcf = 1,000 ft3 

bbl = 42 U.S. gal 

Source: SONRIS lite database (Louisiana Dept. of Natural Resources, 2010). 
A-42 Central Planning Area Supplemental EIS 

Table 3-12 

 

Designated Ocean Dredged-Material Disposal Sites in the Cumulative Impact Area 

ODMDS Location Coordinates 

Name Latitude Longitude 

Water 

Depth Size Authorized Material, Last Time Used and Amount Disposed 

30°17'24"N 87°18'30"W 

30°17'00"N 87°19'50"W 

30°15'36"N 87°17'48"W 

Pensacola 

Nearshore 

30°15'15"N 87°19'18"W 

~36 ft, 

~11m 

2.48 mi2, 

642 ha, 

1,587 ac 

Medium-grained sand, <10% fines. 

1987; 157,100 yd3

30°08'50"N 87°19'30"W 

30°08'50"N 87°16'30"W 

30°07'05"N 87°16'30"W 

Pensacola 

Offshore 

30°07'05"N 87°19'30"W 

65-80 ft 

20-24m 

6 mi2, 

1,554 ha, 

3,840 ac 

Primarily fine-grained. 

2005; 63,000 yd3

30°10'00"N 88°07'42"W 

30°10'24"N 88°05'12"W 

30°09'24"N 88°04'42"W 

30°08'30"N 88°05'12"W 

Mobile 

30°08'30"N 88°08'12"W 

~46 ft, 

~14m 

4.8 mi2, 

1,243 ha, 

3,072 ac 

Dredged material meeting USEPA Ocean 

Dumping Criteria. 

2008; 2,235,993 yd3

30°12'06"N 88°44'30"W 

30°11'42"N 88°33'24"W 

30°08'30"N 88°37'00"W Pascagoula 

30°08'18"N 88°41'54"W 

38-52 ft, 

11.5-19m 

18.5 mi2, 

4,791 ha, 

11,840ac 

Suitable material from the Mississippi 

Sound and vicinity. 

2008; 1,489,100 yd3

30°12'00"N 89°00'30"W 

30°12'00"N 88°59'30"W 

30°11'00"N 89°00'00"W 

30°07'00"N 88°56'30"W 

30°06'36"N 88°57'00"W 

Gulfport West 

30°10'30"N 89°00'36"W 

~27 ft, 

~8.2m 

5.2 mi2, 

1,346 ha, 

3,328 ac 

Dredged material meeting USEPA Ocean 

Dumping Criteria. 

2005; 390,000 yd3

30°11'10"N 88°58'24"W 

30°11'12"N 88°57'30"W 

30°07'36"N 88°54'24"W Gulfport East 

30°07'24"N 88°54'48"W 

~30 ft, 

~9.1m 

2.47 mi2, 

640 ha, 

1,581 ac 

Meet USEPA Ocean Dumping Criteria. 

1996; 323,300 yd3

29°22'00"N 88°56'30"W 

29°23'00"N 88°54'30"W 

Mississippi 

River - Gulf 

Outlet 29°24'30"N 88°52'30"W 

20-40 ft, 

6-12m 

6.03 mi2, 

1,562 ha, 

3,859 ac 

Dredged material from the vicinity of 

Mississippi River Gulf Outlet. 

2005; 909,100 yd3

28°53'58"N 89°25'31"W 

28°53'45"N 89°25'09"W 

28°53'13"N 89°25'28"W 

Mississippi 

River - 

Southwest 

Pass 28°53'11"N 89°24'49"W 

8-106 ft, 

2.7-32.2m 

3.44 mi2, 

891 ha, 

2,202 ac 

Dredged material from the vicinity of the 

Southwest Pass Channel. 

2008; 6,890,400 yd3

29°13'30"N 89°53'30"W 

29°13'54"N 89°53'48"W Barataria Bay 

Waterway 

29°14'21"N 89°54'06"W 

8-20 ft, 

2.4-6.1m 

1,4 mi2, 

362 ha, 

896 ac 

Dredged material from the vicinity of 

Barataria Bay Waterway. 

1988; 775,000 yd3

28°58'09"N 90°29'30"W 

28°58'57"N 90°31'30"W 

Houma 

Navigation 

Canal (Cat 

Island Pass) 28°57'57"N 90°31'54"W 

6-30 ft, 

1.8-9.1m 

2.08 mi2, 

539 ha, 

1,331 ac 

Dredged material from the vicinity of Cat 

Island Pass, Louisiana. 

1997; 117,400 yd3
Figures and Tables A-43 

Table 3-12. Designated Ocean Dredged-Material Disposal Sites in the Cumulative Impact Area (continued). 

ODMDS Location Coordinates 

Name Latitude Longitude 

Water 

Depth Size Authorized Material, Last Time Used and Amount Disposed 

29°07'00"N 91°31'30"W 

29°08'00"N 91°29'00"W Atchafalaya 

Bar Channel 

29°09'00"N 91°27'00"W 

~16 ft, 

~4.8m 

9.14 mi2, 

2,367 ha, 

5,850 ac 

Dredged material from the bar channel of 

the Atchafalaya River. 

2008; 9,545,800 yd3

29°30'00"N 93°10'18"W 

29°30'51"N 93°10'00"W Calcasieu 

River & Pass 

29°30'00"N 93°09'27"W 

36-46 ft, 

11 to 14 m 

5.8 mi2, 

1,502 ha, 

3,712 ac 

Dredged material from the vicinity of the 

Calcasieu River and Pass Project. 

2008; 364,700 yd3

29°27'30"N 93°37'00"W 

29°27'30"N 93°36'45"W 

29°26'38"N 93°36'45"W 

Sabine-Neches 

Waterway No. 

1 & 2 

29°26'38"N 93°37'00"W 

25.7-42.6 ft, 

9-13m 

6.6 mi2, 

1709 ha, 

4,224 ac 

Dredged material from the Sabine-Neches 

area. 

2006; 1,524,200 yd3

29°35'52"N 93°41'45"W 

29°35'52"N 93°41'30"W 

29°35'00"N 93°41'30"W 

Sabine-Neches 

Waterway No. 

3 & 4 

29°35'00"N 93°41'45"W 

16.4-33 ft, 

5-10m 

8.9 mi2, 

2,305 ha, 

5,696 ac 

Dredged material from the Sabine-Neches 

area. 

2008; 1,691,900 yd3

29°20'22"N 94°37'11"W 

29°19'32"N 94°36'56"W 

29°19'23"N 94°37'06"W 

Galveston 

Harbor & 

Channel 

29°20'13"N 94°37'21"W 

33-51 ft, 

10-15.5m 

6.6 mi2, 

1,709 ha, 

4,224 ac 

Dredged material from the Galveston, 

Texas, area. 

2008; 2,395,800 yd3

28°54'28"N 95°13'40"W 

28°54'35"N 95°13'28"W 

28°55'07"N 95°14'01"W 

Freeport 

Harbor, New 

Work 

28°54'60"N 95°14'13"W 

54-61 ft, 

16.4-18.6m 

2.64 mi2, 

684 ha, 

1,690 ac 

Dredged material from the Freeport 

Harbor Entrance and Jetty Channels, 

Texas. 

1992; 46,800 yd3

28°24'27"N 96°16'04"W 

28°24'33"N 96°15'52"W 

28°25'10"N 96°16'30"W 

Matagorda 

Ship Channel 

28°25'04"N 96°16'42"W 

25-40 ft, 

7.5-12.2m 

0.56 mi2, 

145 ha, 

358 ac 

Dredged material from the Matagorda 

Ship Channel, Texas. 

2006; 336,700 yd3

27°50'10"N 96°59'17"W 

27°50'20"N 96°59'09"W 

27°50'48"N 96°59'57"W 

Corpus Christi 

Ship Channel 

27°50'38"N 97°00'05"W 

35-50 ft, 

10.6-15.2m 

0.63 mi2, 

163 ha, 

403 ac 

Dredged material from the Corpus Christi 

Ship Channel, Texas. 

2007; 954,600 yd3

26°32'11"N 97°13'44"W 

26°31'58"N 97°13'44"W 

26°31'58"N 97°14'42"W 

Port Mansfield 

26°32'11"N 97°14'42"W 

35-50 ft, 

10.6-15.2m 

0.42 mi2, 

109 ha, 

269 ac 

Dredged material from the Port Mansfield 

Entrance Channel, Texas. 

1986; 104,200 yd3

26°02'18"N 96°06'30"W 

26°02'18"N 97°07'26"W 

26°02'05"N 97°07'26"W 

Brazos Island 

Harbor 

26°02'05"N 96°06'30"W 

55-65 ft, 

16.7-19.8m 

0.42 mi2, 

109 ha, 

269 ac 

Dredged material from the Brazos Island 

Harbor Entrance Channel, Texas. 

1997; 350,900 

~ approximately. 

Sources: National Archives and Records Administration, 2010; U.S. Dept. of the Army, COE, 2011. 
A-44 Central Planning Area Supplemental EIS 

Table 3-13 

 

Projected OCS Sand Borrowing Needs for Planned Restoration Projects 

Restoration Project Maximum Sand (yd3) Source (OCS Area and Block) (if known) 

Pelican Island (CWPPRA BA-35) ~5,500,000 West Delta (Sandy Point site) 

Raccoon Island (CWPPRA TE-48) 750,000 to 830,000 Ship Shoal 64 & 71 

Cameron Parish Shoreline ~10,000,000 Sabine Bank 

Point Au Fer Shoreline N/A N/A 

LCA Terrebonne Basin 

Raccoon Island ~8,340,000 Ship Shoal 88 & 89; South Pelto 12 & 13 

Whiskey Island ~7,720,000 Ship Shoal 88 & 89; South Pelto 12 & 13 

Trinity and East Islands ~16,260,000 Ship Shoal 88 & 89; South Pelto 12 & 13 

Timbalier Island ~10,700,000 Ship Shoal 88 & 89; South Pelto 12 & 13 

East Timbalier Island ~11,230,000 N/A 

LCA Barataria Basin 

Caminada Headland ~6,000,000 South Pelto 12 &13 

TOTAL ~76,500,000

N/A = not available 

~ approximately 

Table 3-14 

 

Vessel Calls at U.S. Gulf Coast Ports in 2004 and 2009 

Vessel Type 2004 Percent of Total Calls in U.S. 2009 Percent of Total Calls in U.S. 

Tanker 52.4 55.8 

Container 7.0 9.0 

Dry Bulk 42.6 46.8 

RO-RO (Roll-on Roll-off) 7.0 9.9 

Gas 59.8 62.6 

Combo 56.2 75.6 

General 28.8 39.0 

All Types 31.2 34.1 

Source: USDOT, MARAD, 2009. 
Figures and Tables A-45 

Table 3-15 

 

Designated Louisiana Service Bases Identified in Applications for Pipelines, Exploration, 

and Development Plans between 2003 and 2008 and Miles of Navigation Canal Bordered 

by Saline, Brackish Water, and Freshwater Wetlands 

Number of Pipeline 

Applications with Designated 

Service Base 

Number of Exploration and 

Development Plans with 

Designated Service Base Shore Base 

2003-2008 Percent 2003-2008 Percent 

Miles 

Bordering Salt 

and Brackish 

Wetlands 

Miles 

Bordering 

Fresh 

Wetlands 

Fourchon 303 31.5 618 44.4 0** 0** 

Cameron 247 25.7 383 27.5 0 0 

Intracoastal City 102 10.6 94 6.7 6.4 0 

Venice 96 10.0 139 9.9 Miss. River 0 

Morgan City 68 7.1 52 3.7 Miss. River 0 

Leeville 37 3.9 18 1.3 0 0 

Grand Isle 29 3.0 2 0.1 0 0 

Dulac 20 2.1 8 0.6 1.7 0 

Berwick 14 1.5 19 1.4 Miss. River 0 

Lake Charles 12 1.2 1 0.1 3.4 0 

Freshwater City 10 1.0 18 1.3 0 0 

Houma 8 0.8 18 1.3 5.3 6.6 

Amelia 2 0.2 7 0.5 0 0 

Galliano 1 0.1 7 0.5 0 0 

Boothville 3 0.3 6 0.4 Miss. River 0 

Abbeville 7 0.7 0 0.0 0 0 

Grand Chenier 2 0.2 1 0.1 0 0 

Grand Total 961 99.9 1,391 99.8 16.8 6.6 

 *= compiled by BOEMRE staff using operator-designated service bases from OCS plans and pipeline applications. 

**= “0” indicates the service base has no surrounding wetlands in the category. 
A-46 Central Planning Area Supplemental EIS 

Table 3-16 

 

Coastal Impact Assistance Program Allocations for all Eligible States ($) 

Recipient FY 2007 FY 2008 FY 2009 FY 2010 Total 

Alabama 25,551,607.04 25,551,607.04 19,728,257.36 19,524,845.48 90,356,316.92

State Share 16,608,544.58 16,608,544.58 12,823,367.28 12,691,149.56 58,731,606.00

County Share 8,943,062.46 8,943,062.46 6,904,890.08 6,833,695.92 31,624,710.92

Alaska 2,425,000.00 2,425,000.00 37,471,876.48 37,085,568.47 79,407,444.95

State Share 1,576,250.00 1,576,250.00 24,356,719.71 24,105,619.51 51,614,839.22

Borough Share 848,750.00 848,750.00 13,115,156.77 12,979,948.97 27,792,605.74

California 7,444,441.75 7,444,441.75 4,923,124.98 4,872,363.83 24,684,372.31

State Share 4,838,887.13 4,838,887.13 3,200,031.24 3,167,036.49 16,044,841.99

County Share 2,605,554.61 2,605,554.61 1,723,093.74 1,705,327.34 8,639,530.30

Louisiana 127,547,898.57 127,547,898.57 120,911,588.83 119,663,560.77 495,670,946.74

State Share 82,906,134.07 82,906,134.07 78,592,532.74 77,781,314.50 322,186,115.38

Parish Share 44,641,764.50 44,641,764.50 42,319,056.09 41,882,246.27 173,484,831.36

Mississippi 30,939,850.55 30,939,850.55 23,819,815.26 23,574,217.72 109,273,734.08

State Share 20,110,902.86 20,110,902.86 15,482,879.92 15,323,241.52 71,027,927.16

County Share 10,828,947.69 10,828,947.69 8,336,935.34 8,250,976.20 38,245,806.92

Texas 48,591,202.09 48,591,202.09 35,645,337.09 35,279,443.73 168,107,185.00

State Share 31,584,281.36 31,584,281.36 23,169,469.11 22,931,638.42 109,269,670.25

County Share 17,006,920.73 17,006,920.73 12,475,867.98 12,347,805.30 58,837,514.74

Table 3-17 

 

Coastal Impact Assistance Program Grants Status for Gulf of Mexico States ($) 

Recipient Total 

Allocation 

Amount 

Applied For 

Amount 

Awarded 

Amount 

Under Review 

Allocation 

Balance 

Alabama 90,356,316.92 26,371,168.00 17,665,845.59 8,705,322.41 63,985,148.92

State 58,731,606.00 13,408,368.07 10,576,735.04 2,831,633.03 45,323,237.93

County 31,624,710.92 12,962,799.93 7,089,110.55 5,873,689.38 18,661,910.99

Louisiana 495,670,946.74 167,570,557.69 151,147,595.40 16,422,962.29 328,100,389.05

State 322,186,115.38 114,414,404.38 109,013,629.00 5,400,775.38 207,771,711.00

Parish 173,484,831.36 53,156,153.31 42,133,966.40 11,022,186.91 120,328,678.05

Mississippi 109,273,734.08 41,527,869.50 32,065,439.00 9,462,430.50 67,745,864.58

State 71,027,927.16 33,239,105.50 30,083,154.00 3,155,951.50 37,788,821.66

County 38,245,806.92 8,288,764.00 1,982,285.00 6,306,479.00 29,957,042.92

Texas 168,107,185.00 25,091,736.63 22,005,691.30 3,086,045.33 143,015,448.36

State 109,269,670.25 19,627,047.36 18,627,047.36 1,000,000.00 89,642,622.89

County 58,837,514.74 5,464,689.27 3,378,643.94 2,086,045.33 53,372,825.47

Total GOM 863,408,182.74 260,561,331.82 222,884,571.29 37,676,760.53 602,846,850.91
Figures and Tables A-47 

Table 3-18 

 

Hurricane Landfalls in the Northern Gulf of Mexico 

from 1995 to 2010 

Event Year Impacted State Storm Name Intensity at Landfall 

1 1995 AL, FL Opal Hurricane Category 3 

2 1995 FL Erin Hurricane Category 2 

3 1997 LA, AL Danny Hurricane Category 1 

4 1998 FL Earl Hurricane Category 1 

5 1998 MS, AL Georges Hurricane Category 2 

6 1999 TX Bret Hurricane Category 3 

7 2002 LA Lili Hurricane Category 1 

8 2003 TX Claudette Hurricane Category 1 

9 2004 MS, AL Ivan Hurricane Category 4 

10 2005 LA, MS Cindy Hurricane Category 1 

11 2005 FL, AL Dennis Hurricane Category 3 

12 2005 LA, MS Katrina Hurricane Category 5 

13 2005 TX, LA Rita Hurricane Category 3 

14 2007 TX, LA Humberto Hurricane Category 1 

15 2008 LA Gustav Hurricane Category 2 

16 2008 TX, LA Ike Hurricane Category 4 

17 2008 TX Dolly Hurricane Category 1 

* No hurricane landfalls in the northern Gulf of Mexico in 2009 or 2010. 

Source: USDOC, NOAA, 2010b. 

Table 3-19 

 

OCS Facility Damage after the 2004-2008 Hurricanes in the WPA and CPA 

Platforms 

Storm Platforms Exposed to High Winds 

(≥73 mph) Destroyed Damaged 

Damaged 

Pipelines 

(≥10 in) 

Ivan (2004) 150 7 14 13 

Katrina (2005) 43 NR 40 

Rita (2005) 3,050* 69 NR 101 

Gustav (2008) 677 1 40 NR 

Ike (2008) 2,127 60 124 NR 

NR = not reported. 

*Combined totals for both Hurricanes Katrina and Rita. 

Statistics compiled from BOEMRE website and press releases. 
A-48 Central Planning Area Supplemental EIS 

Table 4-1 

 

National Ambient Air Quality Standards 

 Primary Standards Secondary Standards 

Pollutant Level Averaging Time Level Averaging Time

9 ppm (10 mg/m3 Carbon Monoxide ) 8-hour (1) 

35 ppm (40 mg/m3

) 1-hour (1) 

None 

0.15 μg/m3 Lead (2) Rolling 3-Month Average Same as Primary 

1.5 μg/m3 Quarterly Average Same as Primary 

Nitrogen Dioxide 53 ppb (3) Annual (Arithmetic Average) Same as Primary 

100 ppb 1-hour (4) None 

Particulate Matter (PM10) 150 μg/m3 24-hour (5) Same as Primary 

15.0 μg/m3 Particulate Matter (PM2.5) Annual (6) (Arithmetic Average) Same as Primary 

35 μg/m3 24-hour (7) Same as Primary 

0.075 ppm (2008 std) 8-hour (8) Same as Primary 

0.08 ppm (1997 std) 8-hour (9) Same as Primary 

Ozone 

0.12 ppm 1-hour (10) Same as Primary 

0.03 ppm Annual (Arithmetic Average) 

0.14 ppm 24-hour (1) 

0.5 

ppm 

Sulfur Dioxide 3-hour (1) 

75 ppb (11) 1-hour None 

(1) Not to be exceeded more than once per year. 

(2) Final rule signed October 15, 2008. 

(3) The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for the 

purpose of clearer comparison to the 1-hour standard. 

(4) To attain this standard, the 3-year average of the 98th percentile of the daily maximum 1-hour average at each 

monitor within an area must not exceed 100 ppb (effective January 22, 2010). 

(5) Not to be exceeded more than once per year on average over 3 years. 

(6) To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or 

multiple community-oriented monitors must not exceed 15.0 μg/m3

. 

(7) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each populationoriented monitor within an area must not exceed 35 μg/m3

 (effective December 17, 2006). 

(8) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone 

concentrations measured at each monitor within an area over each year must not exceed 0.075 ppm (effective 

May 27, 2008). 

(9) (a) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone 

concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm. 

 (b) The 1997 standard—and the implementation rules for that standard—will remain in place for 

implementation purposes as USEPA undertakes rulemaking to address the transition from the 1997 ozone 

standard to the 2008 ozone standard. 

 (c) USEPA is in the process of reconsidering these standards (set in March 2008). 

(10)(a) USEPA revoked the 1-hour ozone standard in all areas, although some areas have continuing obligations 

under that standard (“anti-backsliding”). 

 (b) The standard is attained when the expected number of days per calendar year with maximum hourly 

average concentrations above 0.12 ppm is 1. 

(11)(a) Final rule signed June 2, 2010. To attain this standard, the 3-year average of the 99th percentile of the daily 

maximum 1-hour average at each monitor within an area must not exceed 75 ppb. 
Figures and Tables A-49 

Table 4-2 

 

Estimated Abundance of Cetaceans 

in the Northern Gulf of Mexico Oceanic Waters 

Species Common Name Estimated Number of 

Individuals 

Balaenoptera edeni Bryde’s whale 15 

Physeter macrocephalus Sperm whale* 1,665 

Kogia spp. Dwarf and Pygmy sperm whale 453 

Ziphius cavirostris Cuvier’s beaked whale 65 

Mesoplodon sp. Blainville’s and Gervais’ beaked whale 57 

Feresa attenuata Pygmy killer whale 323 

Pseudorca crassidens False killer whale 777 

Orcinus orca Killer whale 49 

Globicephala sp. Pilot whale, short-finned 716 

Peponocephala electra Melon-headed whale 2,283 

Grampus griseus Risso’s dolphin 1,589 

Tursiops truncatus Bottlenose dolphin 3,708 

Steno bredanensis Rough-toothed dolphin unknown 

Lagenodelphis hosei Fraser’s dolphin unknown 

Stenella frontalis Atlantic spotted dolphin unknown 

Stenella longirostris Spinner dolphin 1,989 

Stenella attenuate Pantropical spotted dolphin 34,067 

Stenella clymene Clymene dolphin 6,575 

Stenella coeruleoalba Striped dolphin 3,325 

*Endangered. 

Source: Waring et al., 2009. 
A-50 Central Planning Area Supplemental EIS 

Table 4-3 

 

Sea Turtle Taxa of the Northern Gulf of Mexico 

Order Testudines (turtles) Relative Occurrence ESA Status 

Family Cheloniidae (hardshell sea turtles) 

Loggerhead sea turtle (Caretta caretta) C T 

Green sea turtle (Chelonia mydas) C T/E 

Hawksbill sea turtle (Eretmochelys imbricata) R E 

Kemp’s ridley sea turtle (Lepidochelys kempii) C E 

Family Dermochelyidae (leatherback sea turtle) 

Leatherback sea turtle (Dermochelys coriacea) U E 

Population status in the northern Gulf is summarized according to the following categories: 

COMMON (C): A common species is one that is abundant wherever it occurs in the region (i.e., the 

northern Gulf). Most common species are widely distributed over the area. 

UNCOMMON (U): An uncommon species may or may not be widely distributed but does not occur 

in large numbers. Uncommon species are not necessarily rare or endangered. 

RARE (R): A rare species is one that is present in such small numbers throughout the region that it is 

seldom seen. Although not threatened with extinction, a rare species may become endangered if 

conditions in its environment change. 

Endangered Species Act (ESA) status is summarized according to listing status under the following 

categories: 

ENDANGERED (E): Species determined to be in imminent danger of extinction throughout all of a 

significant portion of their range. 

THREATENED (T): Species determined likely to become endangered in the foreseeable future. 
Table 4-4 Comparison of Oil Spills by Type, Location, Year, and Volume (in U.S. gallons) and Their Relative Impacts to Birds based on Su

Incident Type Location Year Volumeb,c Bird Surveysd Estimated Morta

Ixtoc Blowout Mexico 1979 145.6 million >3,000 No research or modExxon Valdez Tanker Alaska, USA 1989 10.8 million >30,000 100,000-645,000 Sea Empress Tanker Wales, UK 1996 22.1 million >4,500 No research or modM/V Citrus Tanker Alaska, USA 1996 Unknown >1,000 1,930 Erika Tanker France 1999 6.1 million >74,000 80,000-150,000 Prestige Tanker Spain 2002 19.2 million >9,000 115,000-300,000 Terra Nova Rig Newfoundland, CAN 2004 42,000 No survey 3,593-16,122 M/V Selendang Ayu Tanker Alaska, USA 2004 354,218 1,603 Pending** Black Sea Tanker Kerch Strait, RUS 2007 1.47 million >30,000 No research or modDeepwater Horizon Blowout Louisiana, USA 2010 210 million 8,000 Pending** a Since the Exxon Valdez oil spill in March 1989, but including the Ixtoc I blowout in the Bay of Campeche, Mexico (1979; Jernelöv, 2

in Helm et al. (2008) for additional information. Includes oil spills associated with tankers, barges, wells, rigs-platforms, and blowo

data are available. This list of spills is not exhaustive but reflects a representative cross-section of oil-spill events across the world o

a more comprehensive review of oil spills, locations, spill volumes, and bird mortality, refer to Burger (1993, Table 1), Castege et a

al. (2008, Tables 1-6), and Tan et al. (2010, Table 1). b Volume estimates are in gallons. c Volume estimates were in some cases converted from figures cited in a specific reference using the conversion of metric tons to 

42 gal/bbl (Wilhelm et al., 2007, p. 540). In other cases, the figures were pulled from the Tables in Helm et al. (2008). NOTE: 

poor predictor of bird mortality associated with an oil spill (Burger, 1993), although it should be considered for inclusion in any m

mortality, preferably with some metric of species composition and abundance (preferably density) pre-spill (Wilhelm et al., 2007). d Figures cited in specific references usually as a part of the damage assessment process including beached-bird surveys, boat or sh

surveys to collect dead or oiled birds. It has been well documented that, in most cases, survey efforts to collect bird carcasses represtotal mortality for a given oil-spill event. That is, the recovery rate of oiled carcasses is biased low; Burger (1993) and Wiese and Jomethodologies, arrived at recovery rate estimates of only 20%. Piatt and Ford (1996) derived a recovery mean rate estimate of only 

based on 17 different studies spanning 21 years (1970-1991). e Final estimated mortality typically includes results from drift and carcass experiments plus modeling efforts to account for birds oil

detected; that is, a correction for detection and scavenging bias, deposition and persistence rates, and the effects of wind, currents, habitat. Refer to Flint and Fowler (1998), Flint et al. (1999), Castège et al. (2007), Wilhelm et al. (2007), Byrd et al. (2009), and 

additional information regarding biases associated with mortality estimates from carcass surveys only. f Most of the references used herein are from the peer-reviewed scientific literature. 
A-52 Central Planning Area Supplemental EIS Table 4-4. Comparison of Oil Spills by Type, Location, Year, and Volume (in U.S. gallons) and Their Relative Impacts to Birds based on Surveys and Modelinga (continued). * Literature searches on the Internet revealed only two avian-related references as a result of the Ixtoc I oil spill: Chapman, 1981 and 1984. ** Pending results of the NRDA process and litigation regarding damage claims against litigants; see also Helm et al., 2006 and 2008. 1 Jernelöv, 2010. 2 Helm et al., 2006. 3 Helm et al., 2008. 4 Ford et al., 1996. 5 Piatt and Ford, 1996. 6 Banks et al., 2008. 7 Law and Kelley, 2004. 8 Flint et al., 1999. 9 Cadiou et al., 2004. 10 Castège et al., 2004. 11 Castège et al., 2007. 12 Alonso-Alvarez et al., 2007. 13 Munilla and Velando, 2010. 14 Velando et al., 2005a. 15 Velando et al., 2005b. 16 Camphuysen et al., 2002. 17 Wilhelm et al., 2007. 18 Byrd et al., 2009. 19 Tan et al., 2010. 20 USDOI, FWS, 2010. 21 Oil Spill Commission, 2010.
Figures and Tables A-53 

Table 4-5 

 

Relative Oiling Ranks for Various Avian Species Groupings Collected Post-Deepwater Horizon Event 

in the Gulf of Mexicoa

Species Group # Representative Spp.1 # Collected # Oiled Oiling Rate (%  SE)2

Oiling 

Rank3 

Diving* 5 182 102 0.50  0.19 1 

Seabirds* 25 5946 2512 0.37  0.05 2 

Shorebirds* 13 97 24 0.13  0.06 6 

Passerines* 21 77 17 0.20  0.07 5 

Marsh/Wading* 21 424 117 0.24  0.05 4 

Waterfowl* 11 56 16 0.37  0.13 3 

Raptors* 6 16 3 0.05  0.05 7 

a Data obtained from the U.S. Fish and Wildlife Service (FWS) as summarized a table dated November 30, 2010. 

The data used in this table are verified as per the FWS QA/QC processes. Disclaimer: All data should be 

considered provisional, incomplete, and subject to change. For more information, see USDOI, FWS, 2010. 

* Species Group: As defined in the text of this Supplemental EIS. As of November 30, 2010, 8,000 individuals 

of 102 species had been collected and identified by FWS. Six new species were added since the 

November 16th summary. NOTE: The Top 5 most-impacted species are all representative of the “seabirds” 

group, with an oiling rate (0.44) above the combined average of all species, including “unknowns” and “other” 

(0.27). 

1 Represents the actual number of birds identified to the species level for each of the Species Groups; reflects 

sample size for determining mean Oiling Rate. This number should be fairly representative of the suite of 

species available to be oiled. However, this number is dependent on efforts to correctly assign species to 

unidentified birds or unknowns, which is also a function of the search effort. The search effort has likely 

declined dramatically since the Deepwater Horizon was plugged/capped. 

2 Oiling Rate: For each species, an oiling rate was calculated by dividing the “total” number of oiled individuals 

(∑ alive + dead) /∑ of individuals collected for a given species/row. These rates were then used to calculate 

summary statistics. In general, it has been well documented that the number of birds collected after a spill 

event represents a small fraction of the total oiled population (direct mortality) due to various factors: speciesspecific differences in vulnerability to spilled oil; species-specific differences in distribution, habitat use, and 

behavior; species-specific differences in abundance; species-specific differences in carcass deposition rates, 

persistence rates, and detection probabilities; overall search effort and temporal and spatial variation in search 

effort; and carcass loss due to predation, habitat, weather, tides, and currents (Piatt et al., 1990a and 1990b; 

Ford et al., 1996; Piatt and Ford, 1996; Fowler and Flint, 1997; Flint and Fowler, 1998; Flint et al., 1999; 

Castege et al., 2007; Byrd et al., 2009; Flint et al., 2010). For example, Piatt and Ford (1996, Table 1) 

estimated a mean carcass recovery rate of only 17% for a number of previous oil-bird impact studies. Burger 

(1993) and Wiese and Jones (2001) estimated recovery rates of 20%, with the latter study based on a drift-block 

design to estimate carcass recovery rate from beached-bird surveys. NOTE: Spill volume tends to be a poor 

predictor of bird mortality associated with an oil spill (Burger, 1993), although it should be considered for 

inclusion in any models to estimate total bird mortality, preferably with some metric of species composition and 

abundance (preferably density) pre-spill (Wilhelm et al., 2007). For this table, the value obtained for passerines 

and raptors is almost certainly biased high due to the small sample sizes (several cases where only 1-2 

birds/species) for individual species and due to the influence of high estimates for oiling (100%). For the other 

Species Groups, e.g., shorebirds, the value obtained is likely biased low due the larger number of species with 

several instances where only one bird was collected and it did not meet the criteria to be designated as oiled. 

There was a significant difference (F = 20.80, df = 1, 12; P = 0.0006) in oiling rates among species. 

3 Oiling Rank: Reflects the relative rank of a given Species Group as a function of the mean Oiling Rate. As 

expected, diving birds and seabirds had the highest oiling rate of any of the Species Groups (King and Sanger, 

1979; Wiens et al., 1984; Piatt et al., 1990a; Williams et al., 1995) due to their reliance on offshore habitat for 

foraging and as a substrate for resting, preening, and other maintenance behaviors. 
A-54 Central Planning Area Supplemental EIS 

Table 4-6 

 

Birds Collected and Summarized by the U.S. Fish and Wildlife Service Post-Deepwater Horizon Event 

in the Gulf of Mexicoa, b

Common Name Species Group*

Grand 

Total

Visibly 

Oiled Total

Not 

Visibly 

Oiled Total

Unknown 

Oiling Total

Oiling 

Rate1,2

Dead Alive Dead Alive Dead Alive 

American Coot Marsh/Wading 5 2 2 4 0 0 0 1 0 1 0.80

American 

Oystercatcher Shorebird 17 7 3 10 3 3 6 1 0 1 0.59

American Redstart Passerine 1 0 0 0 1 0 1 0 0 0 0.00

American White 

Pelican Seabird 17 2 0 2 2 6 8 7 0 7 0.12

Audubon's 

Shearwater Seabird 6 1 1 2 2 2 4 0 0 0 0.33

Barn Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Barn Swallow Passerine 1 1 0 1 0 0 0 0 0 0 1.00

Belted Kingfisher Passerine 2 0 0 0 1 1 2 0 0 0 0.00

Black-crowned 

Night Heron Marsh/Wading 22 6 3 9 7 5 12 1 0 1 0.41

Black Oystercatcher Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Black Skimmer Seabird 263 51 16 67 141 14 155 41 0 41 0.25

Black Tern Seabird 12 1 0 1 7 3 10 1 0 1 0.08

Black-bellied 

Whistling Duck Waterfowl 2 0 0 0 0 2 2 0 0 0 0.00

Black-necked Stilt Shorebird 3 0 0 0 3 0 3 0 0 0 0.00

Blue-winged Teal Waterfowl 3 0 0 0 3 0 3 0 0 0 0.00

Boat-tailed Grackle Passerine 2 0 0 0 1 1 2 0 0 0 0.00

Brown Pelican Seabird 911 136 210 346 225 146 371 194 0 194 0.38

Brown-headed 

Cowbird Passerine 1 0 0 0 0 1 1 0 0 0 0.00

Bufflehead Waterfowl 1 0 1 1 0 0 0 0 0 0 1.00

Canada Goose Waterfowl 4 0 1 1 1 2 3 0 0 0 0.25

Caspian Tern Seabird 20 7 2 9 5 4 9 2 0 2 0.45

Cattle Egret Marsh/Wading 32 1 1 2 21 4 25 5 0 5 0.06

Clapper Rail Marsh/Wading 128 27 5 32 63 12 75 21 0 21 0.25

Common Loon Diving 106 33 27 60 22 20 42 4 0 4 0.57

Common Moorhen Marsh/Wading 4 1 0 1 3 0 3 0 0 0 0.25

Common Nighthawk Passerine 1 0 0 0 0 1 1 0 0 0 0.00

Common Tern Seabird 32 13 9 22 8 1 9 1 0 1 0.69

Common 

Yellowthroat Passerine 2 0 0 0 2 0 2 0 0 0 0.00

Cooper's Hawk Raptor 1 0 0 0 0 1 1 0 0 0 0.00

Cory's Shearwater Seabird 1 0 0 0 0 1 1 0 0 0 0.00

Double-crested 

Cormorant Diving 25 2 1 3 13 7 20 2 0 2 0.12

Eastern Kingbird Passerine 2 1 0 1 1 0 1 0 0 0 0.50

Eastern Meadowlark Passerine 1 0 0 0 1 0 1 0 0 0 0.00
Figures and Tables A-55 

Table 4-6. Birds Collected and Summarized by the U.S. Fish and Wildlife Service Post-Deepwater Horizon Event 

in the Gulf of Mexicoa, b (continued). 

Common Name Species Group*

Grand 

Total

Visibly 

Oiled Total

Not 

Visibly 

Oiled Total

Unknown 

Oiling Total

Oiling 

Rate1,2

Dead Alive Dead Alive Dead Alive 

Eurasian CollaredDove Passerine 1 0 0 0 1 0 1 0 0 0 0.00

European Starling Passerine 2 0 1 1 1 0 1 0 0 0 0.50

Forster's Tern Seabird 52 16 8 24 13 9 22 6 0 6 0.46

Fulvous Whistling 

Duck Waterfowl 1 0 0 0 0 1 1 0 0 0 0.00

Glossy Ibis Marsh/Wading 2 0 0 0 1 0 1 1 0 1 0.00

Great Blue Heron Marsh/Wading 50 5 2 7 23 16 39 4 0 4 0.14

Great Egret Marsh/Wading 33 6 6 12 10 3 13 8 0 8 0.36

Great-horned Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Greater Shearwater Seabird 28 7 4 11 12 4 16 1 0 1 0.39

Green Heron Marsh/Wading 18 2 0 2 9 6 15 1 0 1 0.11

Gull-billed Tern Seabird 8 0 0 0 2 4 6 2 0 2 0.00

Herring Gull Seabird 42 8 8 16 9 13 22 4 0 4 0.38

Horned Grebe Diving 1 0 1 1 0 0 0 0 0 0 1.00

House Sparrow Passerine 2 0 0 0 1 1 2 0 0 0 0.00

Killdeer Shorebird 3 0 0 0 3 0 3 0 0 0 0.00

King Rail Marsh/Wading 1 0 0 0 0 1 1 0 0 0 0.00

Laughing Gull Seabird 3339 968 341 1309 1341 365 1706 323 1 324 0.39

Least Bittern 

Marsh/ 

Wading 6 0 0 0 4 2 6 0 0 0 0.00

Least Tern Seabird 110 45 6 51 40 6 46 13 0 13 0.46

Lesser Black-backed 

Gull Seabird 5 1 1 2 0 1 1 2 0 2 0.40

Lesser Scaup Waterfowl 1 0 0 0 0 0 0 1 0 1 0.00

Little Blue Heron Marsh/Wading 6 0 0 0 4 1 5 1 0 1 0.00

Long-billed 

Dowitcher Shorebird 1 0 0 0 0 1 1 0 0 0 0.00

Magnificant 

Frigatebird Seabird 9 3 2 5 1 1 2 2 0 2 0.56

Mallard Waterfowl 31 5 4 9 15 7 22 0 0 0 0.29

Manx Shearwater Seabird 1 1 0 1 0 0 0 0 0 0 1.00

Masked Booby Seabird 12 4 3 7 1 4 5 0 0 0 0.58

Mottled Duck Waterfowl 6 0 0 0 5 0 5 1 0 1 0.00

Mourning Dove Passerine 17 2 1 3 8 6 14 0 0 0 0.18

Neotropic 

Cormorant Diving 3 0 0 0 1 0 1 2 0 2 0.00

Northern Cardinal Passerine 3 0 0 0 3 0 3 0 0 0 0.00

Northern Gannet Seabird 632 221 187 408 89 103 192 31 1 32 0.65

Northern 

Mockingbird Passerine 4 0 0 0 3 1 4 0 0 0 0.00

Osprey Raptor 11 2 1 3 5 3 8 0 0 0 0.27

Pied-billed Grebe Diving 47 14 24 38 5 3 8 1 0 1 0.81

Piping Plover Shorebird 1 0 0 0 1 0 1 0 0 0 0.00
A-56 Central Planning Area Supplemental EIS 

Table 4-6. Birds Collected and Summarized by the U.S. Fish and Wildlife Service Post-Deepwater Horizon Event 

in the Gulf of Mexicoa, b (continued). 

Common Name Species Group*

Grand 

Total

Visibly 

Oiled Total

Not 

Visibly 

Oiled Total

Unknown 

Oiling 

Oiling 

Rate1,2 Total

 Dead Alive Dead Alive Dead Alive 

Purple Gallinule Marsh/Wading 1 0 0 0 1 0 1 0 0 0 0.00

Purple Martin Passerine 5 1 0 1 3 1 4 0 0 0 0.20

Red-breasted 

Merganser Waterfowl 4 1 1 2 1 1 2 0 0 0 0.50

Reddish Egret Marsh/Wading 4 1 1 2 1 1 2 0 0 0 0.50

Red-shouldered 

Hawk Raptor 1 0 0 0 0 1 1 0 0 0 0.00

Red-tailed Hawk Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Red-winged 

Blackbird Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Ring-billed Gull Seabird 2 0 1 1 1 0 1 0 0 0 0.50

Rock Dove (pigeon) Passerine 19 2 2 4 4 9 13 2 0 2 0.21

Roseate Spoonbill Marsh/Wading 18 7 2 9 3 1 4 5 0 5 0.50

Royal Tern Seabird 348 116 66 182 95 49 144 22 0 22 0.52

Ruddy Duck Waterfowl 1 1 0 1 0 0 0 0 0 0 1.00

Ruddy Turnstone Shorebird 18 1 3 4 8 5 13 1 0 1 0.22

Sanderling Shorebird 32 4 2 6 17 6 23 3 0 3 0.19

Sandwich Tern Seabird 90 26 19 45 23 13 36 9 0 9 0.50

Seaside Sparrow Passerine 6 4 0 4 2 0 2 0 0 0 0.67

Semipalm. 

Sandpiper Shorebird 2 1 0 1 0 0 0 1 0 1 0.50

Short-billed 

Dowitcher Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Snowy Egret Marsh/Wading 30 10 8 18 7 3 10 2 0 2 0.60

Sooty Shearwater Seabird 1 0 0 0 0 1 1 0 0 0 0.00

Sooty Tern Seabird 4 0 1 1 2 1 3 0 0 0 0.25

Sora Marsh/Wading 6 2 1 3 1 0 1 2 0 2 0.50

Spotted Sandpiper Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Surf Scoter Waterfowl 2 1 1 2 0 0 0 0 0 0 1.00

Tri-colored Heron Marsh/Wading 34 9 5 14 7 2 9 11 0 11 0.41

Virginia Rail Marsh/Wading 4 0 0 0 3 1 4 0 0 0 0.00

White Ibis Marsh/Wading 11 1 1 2 4 3 7 2 0 2 0.18

White-winged Dove Passerine 2 0 0 0 1 1 2 0 0 0 0.00

Willet Shorebird 15 2 1 3 7 3 10 2 0 2 0.20

Wilson's Plover Shorebird 2 0 0 0 1 0 1 1 0 1 0.00

Wilson's Storm 

Petrel Seabird 1 0 0 0 0 1 1 0 0 0 0.00

Yellow-billed 

Cuckoo Passerine 2 2 0 2 0 0 0 0 0 0 1.00

Yellow-crowned 

Night Heron Marsh/Wading 9 0 0 0 7 2 9 0 0 0 0.00

Unid. Blackbird Passerine 1 0 0 0 0 1 1 0 0 0 0.00

Unid. Cormorant Diving 14 3 0 3 10 0 10 1 0 1 0.21

Unid. Dowitcher Shorebird 5 2 0 2 1 2 3 0 0 0 0.40
Figures and Tables A-57 

Table 4-6. Birds Collected and Summarized by the U.S. Fish and Wildlife Service Post-Deepwater Horizon Event 

in the Gulf of Mexicoa, b (continued). 

Common Name Species Group*

Grand 

Total

Visibly 

Oiled Total

Not 

Visibly 

Oiled Total

Unknown 

Oiling 

Oiling 

Rate1,2 Total

 Dead Alive Dead Alive Dead Alive 

Unid. Duck Waterfowl 4 0 0 0 2 1 3 1 0 1 0.00

Unid. Egret Marsh/Wading 11 2 0 2 7 0 7 2 0 2 0.18

Unid. Flycatcher Passerine 1 1 0 1 0 0 0 0 0 0 1.00

Unid. Grackle Passerine 1 1 0 1 0 0 0 0 0 0 1.00

Unid. Grebe Diving 6 4 0 4 2 0 2 0 0 0 0.67

Unid. Gull Seabird 253 79 3 82 131 7 138 33 0 33 0.32

Unid. Hawk Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Heron Marsh/Wading 14 5 0 5 6 1 7 2 0 2 0.36

Unid. Loon Diving 9 2 2 4 4 1 5 0 0 0 0.44

Unid. Mockingbird Passerine 2 0 0 0 1 1 2 0 0 0 0.00

Unid. Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Passerine Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Pelican Seabird 26 5 1 6 15 1 16 4 0 4 0.23

Unid. Pigeon Passerine 17 2 1 3 6 7 13 1 0 1 0.18

Unid. Rail 

Marsh/ 

Wading 4 1 0 1 3 0 3 0 0 0 0.25

Unid. Raptor Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Sandpiper Shorebird 4 0 0 0 2 2 4 0 0 0 0.00

Unid. Shearwater Seabird 4 0 0 0 3 0 3 1 0 1 0.00

Unid. Shorebird Shorebird 3 2 0 2 0 0 0 1 0 1 0.67

Unid. Skimmer Seabird 6 0 0 0 6 0 6 0 0 0 0.00

Unid. Sparrow Passerine 3 0 0 0 1 0 1 2 0 2 0.00

Unid. Swallow Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Tern Seabird 129 37 1 38 72 1 73 18 0 18 0.29

Unknown spp. 561 51 2 53 420 3 423 85 0 85 0.09

Other 119 33 4 37 58 16 74 8 0 8 0.31

Column Totals 8,000 2,024 1,011 3,035 3,108 948 4056 907 2 909 0.27

a Data obtained from the U.S. Fish and Wildlife Service (FWS) as a summarized table dated November 30, 2010. 

The data used in this table are verified as per the FWS QA/QC processes. Disclaimer: All data should be 

considered provisional, incomplete, and subject to change. For more information, see USDOI, FWS, 2010. b As of November 30, 2010, 102 avian species had been identified through the Deepwater Horizon post-spill 

monitoring and collection process. Overall oiling rate across species including “others” and “unknowns” was 

0.27. Oiling rate for the Top 5 (see bold rows in table) most-impacted avian species was 0.44 and included 

representatives from only the seabird group. In descending order based on the number collected: laughing gull 

(3,339 collected, 0.39 oiling rate); brown pelican (911 collected, 0.38 oiling rate); northern gannet (632 collected, 

0.65 oiling rate); royal tern (348 collected, 0.52 oiling rate); and black skimmer (263 collected, 0.25 oiling rate). * Species Group: As defined in the text of this Supplemental EIS. 1 Oiling Rate: For each species, an oiling rate was calculated by dividing the “total” number of oiled individuals 

(∑ alive + dead) /∑ of individuals collected for a given species/row. In general, it has been well documented that 

the number of birds collected after a spill event represents a small fraction of the total oiled population (direct 

mortality) due to various factors: species-specific differences in vulnerability to spilled oil; species-specific 

differences in distribution, habitat use, and behavior; species-specific differences in abundance; species-specific 

differences in carcass deposition rates, persistence rates, and detection probabilities; overall search effort and 
A-58 Central Planning Area Supplemental EIS 

temporal and spatial variation in search effort; and carcass loss due to predation, habitat, weather, tides, and 

currents (Piatt et al., 1990a and 1990b; Ford et al., 1996; Piatt and Ford, 1996; Fowler and Flint, 1997; Flint and 

Fowler, 1998; Flint et al., 1999; Castege et al., 2007; Byrd et al., 2009; Flint et al., 2010). For example, Piatt and 

Ford (1996, Table 1) estimated a mean carcass recovery rate of only 17% for a number of previous oil-bird 

impact studies. Burger (1993) and Wiese and Jones (2001) estimated recovery rates of 20%, with the latter study 

based on a drift-block design to estimate carcass recovery rate from beached-bird surveys. NOTE: Spill volume 

tends to be a poor predictor of bird mortality associated with an oil spill (Burger 1993), although it should be 

considered for inclusion in any models to estimate total bird mortality, preferably with some metric of species 

composition and abundance (preferably density) pre-spill (Wilhelm et al., 2007). 2 For additional information on oiling rates by Species Group and additional statistics, see Table 4-5. 

Table 4-7 

 

Mississippi Department of Marine Resources: Summary of Fish Kills Observed along the Gulf Coast 

Date Area Dissolved Oxygen Fish 

May 5, 2010 Bayou Chicot, LA <1.0 mg/l 3.3 million juvenile menhaden* 

May 5, 2010 Lake Mars Boat Ramp, Belle Fontaine, MS 2 mg/l 1.9 million menhaden* 

May 11-12, 2010 Mississippi beaches 5-5.7 mg/l 27 hardhead catfish 

July 8, 2010 Bayou Caddy, MS 1.7 mg/l 97 with 11 species† 

August 1, 2010 Long Beach Harbor, MS NA 1,900 with 23 species‡ 

August 3, 2010 Mississippi Sound south of Deer Island NA 500,000 menhaden* (broken net)

August 5, 2010 Pass Christian Harbor, MS 6.7 mg/l NA 

* Abundance of menhaden are estimates from the kill site. 

† Species include trout, croaker, sheepshead, mullet, flounder, drum, catfish, and pinfish. 

‡ Species include brown shrimp, crabs, stingrays, kingfish, silver perch, shrimp, eel, lookdown, least puffer, 

lizardfish, cusk-eel, black cheek, tonguefish, bay whiff, and Atlantic spadefish. 

NA = not available. 

Source: Devers, written communication, 2010.

Table 4-8 

 

Economic Significance of Commercial Fishing in the Gulf of Mexico 

State Landings Revenue Sales Impacts Job Impacts CFQ 

Alabama 44,317 445,449 9,750 0.33 

Florida 169,711 5,657,246 108,695 0.99 

Louisiana 272,884 2,033,587 43,711 2.50 

Mississippi 43,696 390,702 8,575 1.96 

Texas 176,098 2,013,272 42,541 0.32 

Total 706,706 10,540,256 213,272 -- 

Source: USDOC, NOAA, 2010c. 
Figures and Tables A-59 

Table 4-9 

 

Top Species Caught by Recreational Fishers in the Gulf Coast States 

Number of Fish 

Species/Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Atlantic Croaker 4,186,990 3,589,525 3,488,464 4,342,264 2,659,716 3,905,810 3,979,556 4,245,495 5,331,132

Black Drum 1,509,119 1,586,284 1,523,614 1,686,081 1,115,153 1,346,737 1,233,862 1,728,173 1,672,719

Blackfin Tuna 50,581 35,051 38,601 73,301 60,501 64,825 83,375 92,763 91,581

Cobia 175,045 163,606 127,512 125,923 108,746 108,656 117,448 161,636 88,721

Dolphins 555,466 364,917 609,001 434,879 316,110 315,264 430,367 368,457 251,429

Gag 2,386,672 2,996,920 3,878,651 4,197,440 2,938,891 2,084,588 3,254,196 4,746,177 2,924,329

Gray Snapper 3,511,496 3,798,482 6,073,935 4,530,800 5,851,190 4,039,090 5,571,680 7,669,142 4,401,510

Great Amberjack 477,424 315,674 346,070 254,283 201,443 161,534 199,429 245,344 207,226

King Mackerel 575,699 488,142 398,234 447,247 380,793 967,378 429,562 376,508 596,232

Little Tuny 265,456 423,424 197,927 362,243 153,204 293,337 333,310 193,546 179,928

Pinfishes 14,675,911 11,664,212 8,848,476 13,813,893 10,274,164 10,324,881 11,762,014 15,942,884 11,591,996

Red Drum 8,261,019 7,351,899 8,587,461 8,387,639 7,492,498 9,838,039 9,030,204 9,700,431 8,063,967

Red Grouper 1,880,567 2,197,298 2,298,287 3,632,743 1,862,289 1,012,572 1,198,064 3,312,054 3,410,731

Red Snapper 2,654,554 3,196,853 2,934,322 3,217,643 2,732,425 3,527,145 3,872,259 2,624,982 2,910,337

Sand Seatrout 4,342,805 4,129,064 4,062,981 3,326,749 2,524,347 4,334,134 4,587,006 5,853,369 6,502,913

Sheepshead 3,126,988 3,253,252 3,945,716 4,669,176 3,961,753 2,992,718 2,397,513 3,229,301 3,189,143

Southern Flounder 902,531 622,566 911,039 917,938 692,293 738,351 802,929 691,132 757,326

Southern Kingfish 2,660,631 1,404,170 1,733,446 2,206,406 1,988,897 1,848,665 1,608,861 1,727,889 1,670,001

Spanish Mackerel 4,321,962 3,882,193 3,715,281 4,303,273 2,518,250 4,946,966 3,817,443 4,132,207 2,988,112

Spotted Seatrout 20,582,815 22,664,920 28,785,103 28,851,638 29,679,185 36,435,823 30,611,531 32,564,976 29,352,993

Striped Mullet 2,293,741 1,340,382 1,866,563 1,257,205 1,323,021 1,303,076 1,162,019 1,231,121 969,123

White Grunt 6,779,775 5,529,179 4,831,100 5,133,524 3,687,435 1,694,738 2,157,816 4,036,236 2,490,431

Pounds 

Species/Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Atlantic Croaker 677,890 287,934 490,887 306,179 280,489 553,449 600,690 598,106 508,967

Black Drum 2,341,032 2,531,258 2,857,730 3,057,965 1,922,411 2,531,999 2,276,953 2,907,574 2,870,621

Blackfin Tuna 526,547 294,526 580,484 830,021 525,045 863,090 286,572 868,698 660,264

Cobia 1,129,714 791,793 1,101,782 1,227,464 1,208,989 1,072,033 1,012,921 913,566 534,810

Dolphins 2,496,877 2,227,922 2,530,400 2,011,021 1,222,221 1,183,392 2,028,360 1,327,670 1,358,031

Gag 3,854,869 3,781,229 3,278,245 4,693,183 3,510,799 1,936,492 2,534,137 3,071,762 1,594,303

Gray Snapper 1,412,589 1,324,563 1,893,108 2,044,198 1,964,576 1,975,178 1,512,298 2,065,549 1,604,298

Great Amberjack 1,153,786 1,847,882 2,416,947 2,251,265 1,358,653 1,282,616 989,630 1,213,319 1,484,002

King Mackerel 2,865,226 3,043,569 2,763,371 2,434,372 1,635,507 3,374,852 2,606,005 1,894,691 3,324,003

Little Tuny 587,429 873,813 590,683 1,108,632 310,877 619,746 813,722 385,382 578,719

Pinfishes 1,560,872 1,677,357 1,739,776 3,811,171 1,215,008 742,368 1,683,034 3,510,949 2,831,692

Red Drum 13,419,400 11,575,766 13,113,186 14,290,334 10,242,490 14,215,737 13,988,083 13,910,457 11,898,383

Red Grouper 1,415,307 1,744,180 1,359,015 3,235,764 1,431,359 980,311 1,039,597 896,377 926,111

Red Snapper 3,737,264 4,369,698 3,921,340 4,162,485 3,322,074 3,232,025 3,769,388 3,128,771 3,613,267

Sand Seatrout 1,905,500 1,723,872 1,556,192 1,121,936 879,417 1,557,953 1,701,233 1,930,689 2,389,301

Sheepshead 4,385,765 3,775,195 5,002,901 6,487,492 5,288,789 4,013,009 3,836,123 4,670,992 4,388,254

Southern Flounder 1,082,858 630,928 823,083 834,794 645,835 780,468 810,986 749,674 851,999

Southern Kingfish 993,027 581,779 683,569 783,204 657,967 616,415 608,426 629,250 710,651

Spanish Mackerel 3,549,609 3,202,118 2,614,570 2,907,069 1,583,811 2,655,099 2,542,007 2,788,369 1,962,775

Spotted Seatrout 12,514,780 9,684,768 11,881,531 11,880,671 11,761,193 18,057,746 13,817,897 15,180,141 14,500,754

Striped Mullet 2,330,227 1,523,427 2,194,545 1,525,980 1,536,234 1,600,983 1,245,425 1,418,025 900,037

White Grunt 2,352,568 2,019,945 1,785,777 1,751,156 1,602,724 680,403 701,343 1,325,970 1,013,062

Note: Fish that are released alive are included in the landings data but not in the weight data. 

Note: This table presents the sum of fishing data for Louisiana, Mississippi, Alabama, and West Florida. 

Source: USDOC, NOAA 2010d. 
A-60 Central Planning Area Supplemental EIS 

Table 4-10 

 

Percentage of Species Landings that are Ocean Based 

Number of Fish 

Species/Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Atlantic Croaker 14.44 10.97 13.76 27.27 10.77 11.41 12.42 6.85 5.54

Black Drum 10.11 9.76 11.49 11.39 16.10 9.48 4.41 4.66 5.41

Blackfin Tuna 100.00 100.00 100.00 100.00 96.64 100.00 100.00 100.00 100.00

Cobia 64.14 72.50 74.56 79.25 83.60 86.83 81.25 73.28 71.72

Dolphins 98.92 100.00 100.00 100.00 100.00 99.72 99.49 99.21 100.00

Gag 82.69 75.01 76.77 81.08 83.59 71.17 63.72 71.40 61.45

Gray Snapper 49.48 32.43 41.52 42.93 36.45 49.40 40.26 48.61 32.00

Great Amberjack 96.21 99.63 99.51 99.74 99.18 98.85 100.00 99.44 100.00

King Mackerel 97.34 96.94 99.20 95.87 93.48 62.50 94.85 93.83 93.00

Little Tuny 97.84 96.08 99.76 99.80 99.10 92.75 87.64 86.66 87.22

Pinfishes 36.89 31.37 48.33 30.53 43.72 44.88 26.31 37.73 24.59

Red Drum 18.34 13.25 14.44 13.50 21.46 17.50 12.96 12.48 7.45

Red Grouper 98.33 99.38 98.22 97.36 98.12 98.60 97.14 91.04 83.08

Red Snapper 99.32 99.67 99.49 99.20 98.38 98.21 97.97 96.82 98.39

Sand Seatrout 22.81 14.26 11.90 24.40 19.24 23.00 21.26 13.97 12.28

Sheepshead 30.22 23.09 19.56 22.49 24.68 28.70 32.45 19.91 13.34

Southern Flounder 14.11 15.62 5.44 15.59 12.10 8.26 12.23 6.21 4.68

Southern Kingfish 48.30 43.11 33.38 29.19 26.33 39.34 28.73 36.84 18.05

Spanish Mackerel 69.03 53.39 68.10 73.05 63.10 67.63 55.73 70.40 51.93

Spotted Seatrout 23.52 25.12 20.03 18.99 22.97 20.61 23.59 17.20 15.36

Striped Mullet 18.47 13.28 13.20 13.04 28.14 38.07 15.12 21.97 9.98

White Grunt 79.12 86.20 85.07 87.96 91.14 90.42 78.79 85.87 69.51

Pounds 

Species/Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Atlantic Croaker 10.99 12.90 18.98 11.59 3.21 6.63 8.58 5.00 2.37

Black Drum 16.37 21.47 10.60 17.86 9.56 7.15 6.12 6.30 12.54

Blackfin Tuna 100.00 100.00 100.00 100.00 91.49 100.00 100.00 100.00 100.00

Cobia 87.14 80.65 84.22 92.18 95.30 92.92 87.02 87.07 75.04

Dolphins 99.00 100.00 100.00 100.00 100.00 100.00 100.00 99.57 100.00

Gag 97.52 96.43 95.77 96.10 93.16 94.32 89.21 90.92 81.40

Gray Snapper 75.80 75.27 74.21 80.80 84.10 75.51 70.68 71.76 59.57

Great Amberjack 100.00 100.00 99.97 100.00 99.71 100.00 100.00 100.00 100.00

King Mackerel 99.08 96.50 99.46 98.06 98.58 82.52 96.19 97.61 96.20

Little Tuny 100.00 100.00 99.58 99.98 100.00 95.96 70.54 94.12 92.99

Pinfishes 41.84 34.38 56.40 26.93 48.10 54.05 19.22 25.85 22.79

Red Drum 18.82 15.84 16.08 19.52 15.07 15.14 14.94 10.93 7.22

Red Grouper 99.30 99.73 99.71 99.86 100.00 100.00 98.89 97.43 98.25

Red Snapper 99.85 99.83 99.81 98.32 99.45 98.97 96.89 98.31 98.53

Sand Seatrout 21.90 13.65 11.51 26.39 20.30 24.21 19.14 14.25 15.06

Sheepshead 43.70 30.20 26.82 26.65 34.75 39.45 47.43 23.60 13.88

Southern Flounder 16.88 16.23 6.27 14.58 9.26 7.55 9.00 6.98 3.98

Southern Kingfish 51.32 41.90 28.09 27.11 30.90 33.24 28.64 42.04 15.56

Spanish Mackerel 70.72 63.52 70.76 76.73 69.40 67.47 61.28 68.15 56.71

Spotted Seatrout 25.10 28.31 16.25 17.92 20.36 15.85 19.12 14.32 14.31

Striped Mullet 24.07 10.45 7.14 14.07 22.48 31.63 12.10 27.41 6.60

White Grunt 89.48 90.69 91.05 89.34 93.79 94.64 83.12 90.31 83.39

Note: Fish that are released alive are included in the landings data but not in the weight data. 

Note: This table presents the sum of fishing data for Louisiana, Mississippi, Alabama, and West Florida. 

Note: The NMFS divides fishing data into inland, State, and Federal categories. Ocean based is defined as the sum of State and Federal 

categories. 

Source: USDOC, NOAA 2010d. 
Figures and Tables A-61 

Table 4-11 

 

Recreational Fishing Participation 2009 

State Coastal Noncoastal Out of State Total 

West Florida 1,551,478 0 1,670,603 3,222,081

East Florida 1,098,575 0 1,741,339 2,839,914

Alabama 205,365 151,379 208,775 565,519

Mississippi 125,048 36,496 50,328 211,872

Louisiana 668,576 108,086 139,120 915,782

Source: USDOC, NOAA, 2010d. 

State Resident Nonresident Total 

Florida 1,881 885 2,767 

Texas 2,308 218 2,527 

Alabama 600 206 806 

Mississippi 465 80 546 

Louisiana 590 112 702 

Source: USDOI, FWS, and USDOC, Census Bureau, 2006. 
A-62 Central Planning Area Supplemental EIS 

Table 4-12 

 

Angler Trips in the Gulf of Mexico during Certain Months of 2009 and 2010 

2009 2010 

Jan/Feb Mar/April May/June July/Aug Jan/Feb Mar/April May/June July/Aug 

Total Trips 

Alabama 134,887 309,545 454,940 405,356 84,493 275,061 392,199 354,099

Florida 2,205,141 2,588,254 3,963,196 3,422,240 1,760,394 1,947,677 3,517,096 3,082,397

Louisiana 583,195 561,112 1,058,162 838,820 367,898 559,726 901,671 583,342

Mississippi 127,336 148,993 222,623 251,448 90,718 174,983 334,441 159,674

Total 3,050,559 3,607,904 5,698,921 4,917,864 2,303,503 2,957,447 5,145,407 4,179,512

Inland 

Alabama 90,030 201,215 271,504 225,383 90,030 55,150 147,288 237,353

Florida 1,432,011 1,579,247 2,227,167 2,077,674 1,432,011 1,445,472 1,307,968 2,101,879

Louisiana 568,870 552,088 990,311 718,606 568,870 357,404 546,930 880,636

Mississippi 121,012 145,411 201,851 241,075 121,012 90,067 171,824 326,780

Total 2,211,923 2,477,961 3,690,833 3,262,738 2,211,923 1,948,093 2,174,010 3,546,648

State 

Alabama 44,218 93,732 80,117 114,938 29,006 113,399 116,297 180,098

Florida 662,919 927,192 1,423,612 1,105,167 242,215 548,438 1,176,779 949,626

Louisiana 5,302 1,728 38,986 61,425 7,068 10,970 14,779 11,386

Mississippi 1,150 273 7,627 10,191 651 3,042 7,661 --

Total 713,589 1,022,925 1,550,342 1,291,721 278,940 675,849 1,315,516 1,141,110

Federal 

Alabama 639 14,597 103,320 65,035 336 14,374 38,548 313

Florida 110,211 81,815 312,418 239,399 72,707 91,271 238,438 170,106

Louisiana 9,023 7,296 28,865 58,788 3,427 1,826 6,256 6,986

Mississippi 5,175 3,309 13,144 182 -- -- -- --

Total 125,048 107,017 457,747 363,404 76,470 107,471 283,242 177,405

Note: This table presents the sum of fishing data for Louisiana, Mississippi, Alabama, and West Florida. 

Source: USDOC, NOAA, 2010d. 
Figures and Tables A-63 

Table 4-13 

 

Angler trips in the Gulf of Mexico by Location and Mode in 2009 

State Area Number of Trips % State Total 

Alabama Shore Ocean (< 3 nmi) 354,043 20.6

 Shore Inland 407,982 23.8

 Charter Ocean (<3 nmi) 9228 0.5

 Charter Ocean (>3 nmi) 36672 2.1

 Charter Inland 10759 0.6

 Private/Rental Ocean (<3 nmi) 154301 9.0

 Private/Rental Ocean (>3 nmi) 165012 9.6

 Private/Rental Inland 579033 33.7

 Total 1,717,030 

West Florida Shore Ocean (< 9 nmi) 2,511,933 16.2

 Shore Inland 3,942,920 25.4

 Charter Ocean (<9 nmi) 195,688 1.3

 Charter Ocean (>9 nmi) 259,622 1.7

 Charter Inland 112,007 0.7

 Private/Rental Ocean (<9 nmi) 2,602,581 16.8

 Private/Rental Ocean (>9 nmi) 616,371 4.0

 Private/Rental Inland 5,276,236 34.0

 Total 15,517,358 

Louisiana Shore Ocean (< 3 nmi) 37,324 0.9

 Shore Inland 731,676 18.3

 Charter Ocean (<3 nmi) 3,283 0.1

 Charter Ocean (>3 nmi) 18,031 0.5

 Charter Inland 135,654 3.4

 Private/Rental Ocean (<3 nmi) 75,482 1.9

 Private/Rental Ocean (>3 nmi) 102,196 2.6

 Private/Rental Inland 2,896,326 72.4

 Total 3,999,972 

Mississippi Shore Ocean (< 3 nmi) 330 0.0

 Shore Inland 307,856 29.0

 Charter Ocean (<3 nmi) 2,831 0.3

 Charter Ocean (>3 nmi) 330 0.0

 Charter Inland 7,680 0.7

 Private/Rental Ocean (<3 nmi) 18,602 1.8

 Private/Rental Ocean (>3 nmi) 26,095 2.5

 Private/Rental Inland 698,752 65.8

 Total 1,062,476 

Gulf Total Shore Ocean (< 3 nmi) 2,903,630 13.0

 Shore Inland 5,390,434 24.2

 Charter Ocean (<3 nmi) 211,030 0.9

 Charter Ocean (>3 nmi) 314,655 1.4

 Charter Inland 266,100 1.2

 Private/Rental Ocean (<3 nmi) 2,850,966 12.8

 Private/Rental Ocean (>3 nmi) 909,674 4.1

 Private/Rental Inland 9,450,347 42.4

 Total 22,296,836 

Note: This table presents the sum of fishing data from Louisiana, Mississippi, Alabama, and West Florida 

Note: State waters in Florida extend 9 nautical miles from the coast rather than the typical 3 nautical miles.

Source: USDOC, NOAA, 2010d. 
A-64 Central Planning Area Supplemental EIS 

Table 4-14 

 

Economic Impact of Recreational Fishing in the Gulf of Mexico in 2008 

Expenditures* Sales* Value Added* Employment 

Alabama 480,587 455,093 235,481 4,719 

West Florida 6,332,287 5,650,068 3,075,710 54,589 

Mississippi 410,007 382,778 148,837 2,930 

Louisiana 2,727,225 2,297,078 1,156,796 25,590 

Texas 2,594,714 3,288,135 1,656,545 25,544 

Total 12,544,820 12,073,152 6,273,369 113,372 

*Data on expenditures, sales, and value added are presented in thousands of dollars. 

Source: USDOC, NOAA, 2010c. 
Figures and Tables A-65 

Table 4-15 

 

Fish Species Caught by Recreational Anglers during Certain Months of 2009 and 2010 

Species/Year 2009 2010 

Months Jan/Feb Mar/April May/June July/Aug Jan/Feb Mar/April May/June July/Aug 

Number of Fish 

Atlantic Croaker 145,458 809,858 1,816,279 1,625,287 50,971 386,179 1,944,042 1,044,961

Black Drum 161,376 164,735 325,061 224,853 227,071 225,385 364,503 275,733

Blackfin Tuna 27,354 4,581 3,530 26,771 949 1,932 4,657 13,858

Cobia 584 4,475 40,360 34,150 871 14,029 28,830 15,197

Dolphins 12,011 14,355 130,214 84,491 2,113 19,700 136,119 26,805

Gag 395,418 296,874 811,646 478,649 230,505 220,433 634,532 366,454

Gray Snapper 485,160 635,363 934,055 1,451,321 313,131 222,635 407,943 714,142

Great Amberjack 31,396 12,326 104,533 45,653 68,638 55,138 146,875 42,207

King Mackerel 19,359 63,883 202,625 188,375 5,607 32,121 146,680 40,138

Little Tuny 19,291 9,276 32,635 38,169 3,955 8,159 15,674 51,860

Pinfishes 1,371,965 1,391,786 2,470,196 4,232,636 533,986 701,588 4,025,971 3,181,734

Red Drum 982,472 747,513 1,361,522 1,484,450 925,532 1,198,622 1,577,535 1,452,287

Red Grouper 437,521 250,878 1,198,225 691,905 62,283 147,913 771,742 397,990

Red Snapper 84,572 106,800 1,458,523 1,018,133 161,625 120,570 619,128 172,683

Sand Seatrout 269,556 638,973 2,068,415 1,612,595 111,317 630,783 1,851,837 859,674

Sheepshead 1,272,356 901,817 135,120 169,281 746,819 997,496 179,120 110,364

Southern Flounder 36,231 57,573 143,744 213,087 18,603 85,698 267,215 315,046

Southern Kingfish 76,964 289,755 500,087 405,015 133,317 149,150 500,078 131,282

Spanish Mackerel 81,393 472,775 1,059,242 612,279 12,449 592,166 691,469 1,132,884

Spotted Seatrout 3,771,209 2,719,521 8,622,412 5,350,897 1,539,569 1,719,419 5,585,438 4,486,243

Striped Mullet 198,193 31,379 109,002 322,672 31,735 8,328 260,327 413,764

White Grunt 518,784 236,420 448,748 554,624 160,520 252,943 729,231 602,460

Pounds 

Atlantic Croaker 11,715 57,628 173,870 166,893 12,044 24,010 200,460 107,664

Black Drum 272,586 352,421 531,320 546,397 298,282 660,342 306,550 386,283

Blackfin Tuna 202,746 21,076 30,382 265,762 10,708 0 73,709 79,780

Cobia 0 65,580 133,791 297,808 15,919 193,213 171,895 88,019

Dolphins 77,512 90,040 630,635 476,560 10,000 47,840 380,042 120,936

Gag 87,005 146,676 566,695 246,203 171,685 198,240 560,661 179,243

Gray Snapper 152,724 162,960 446,707 618,699 32,209 73,124 189,543 282,467

Great Amberjack 187,900 73,076 693,653 459,602 75,765 314,726 542,118 109,240

King Mackerel 111,522 214,979 983,633 1,136,665 38,517 176,646 972,566 208,339

Little Tuny 68,459 41,731 87,565 165,513 11,933 44,784 41,341 213,463

Pinfishes 258 313,523 747,119 1,375,430 747,218 206,004 347,535 513,628

Red Drum 817,402 1,345,542 2,748,252 2,309,682 1,184,906 2,269,014 2,288,800 2,079,421

Red Grouper 21,369 53,245 307,916 411,885 14,533 37,661 214,075 146,487

Red Snapper 0 0 1,683,450 1,929,816 0 0 396,817 286,040

Sand Seatrout 148,892 220,669 765,417 492,922 54,110 230,046 639,504 387,178

Sheepshead 1,685,580 1,480,944 201,108 222,947 666,634 1,464,578 197,581 60,044

Southern Flounder 29,987 59,601 147,221 233,972 13,772 105,545 282,568 332,260

Southern Kingfish 39,828 125,402 216,637 228,593 68,592 57,467 159,080 47,474

Spanish Mackerel 109,864 320,961 683,805 431,326 8,241 359,894 462,765 501,242

Spotted Seatrout 1,445,014 1,134,580 5,358,179 2,776,994 478,076 811,950 3,312,727 1,805,049

Striped Mullet 124,267 4,899 67,245 330,619 44,936 7,566 265,989 686,934

White Grunt 272,297 115,689 140,164 180,879 94,253 125,841 231,324 253,337

Note: Fish that are released alive are included in the landings data but not in the weight data. 

Note: This table presents the sum of fishing data for Louisiana, Mississippi, Alabama, and West Florida. 

Source: USDOC, NOAA, 2010d. 
A-66 Central Planning Area Supplemental EIS 

Table 4-16 

 

Employment in the Leisure/Hospitality Industry in Selected Geographic Regions 

Region 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Panel A—Economic Impact Area 

TX-1 45,553 46,979 48,490 49,165 50,446 53,281 54,654 54,551 53,691

TX-2 14,055 14,113 14,241 14,728 14,670 16,153 16,564 16,883 16,702

TX-3 195,214 203,090 207,245 214,025 219,203 231,840 241,110 240,231 240,366

LA-1 13,682 14,065 14,300 14,725 15,339 14,747 14,563 14,295 14,246

LA-2 17,653 17,451 18,560 19,817 20,787 21,072 21,517 21,364 20,588

LA-3 37,902 38,048 40,752 42,229 43,483 44,533 44,810 46,037 44,157

LA-4 80,990 80,677 81,243 85,093 47,641 64,812 68,531 68,605 67,438

MS-1 31,485 32,752 33,714 33,297 18,024 29,191 29,680 27,702 26,938

AL-1 23,785 23,937 24,488 24,464 25,481 26,463 26,850 26,516 26,034

FL-1 34,829 36,139 36,520 39,956 41,133 41,887 41,688 40,001 41,003

FL-2 17,934 19,733 18,860 21,588 21,861 22,478 22,913 22,502 21,699

FL-3 123,248 130,250 132,256 137,302 145,005 145,894 149,448 146,368 142,393

FL-4 238,090 251,658 256,472 268,487 274,635 280,874 283,748 283,359 280,380

TX EIA Total 254,822 264,182 269,976 277,918 284,319 301,274 312,328 311,665 310,759

LA EIA Total 150,227 150,241 154,855 161,864 127,250 145,164 149,421 150,301 146,429

MS EIA Total 31,485 32,752 33,714 33,297 18,024 29,191 29,680 27,702 26,938

AL EIA Total 23,785 23,937 24,488 24,464 25,481 26,463 26,850 26,516 26,034

FL EIA Total 414,101 437,780 444,108 467,333 482,634 491,133 497,797 492,230 485,475

EIA Total 874,420 908,892 927,141 964,876 937,708 993,225 1,016,076 1,008,414 995,635

Panel B—Coastal 

TX 57,637 59,250 60,873 61,983 63,069 67,625 68,195 67,388 68,025

LA 88,235 87,640 88,431 92,703 56,242 73,405 77,567 77,580 75,958

MS 30,052 31,295 32,172 31,625 16,152 26,926 27,444 25,575 25,080

AL 21,231 21,690 22,249 22,250 23,099 24,186 24,437 24,319 23,990

FL 377,323 399,122 404,048 423,855 437,761 445,948 450,414 445,164 441,068

Coastal Total 574,478 598,997 607,773 632,416 596,323 638,090 648,057 640,026 634,121

Panel C—Statewide 

TX 818,164 840,506 854,733 877,284 900,646 943,581 982,437 995,445 982,122

LA 191,394 192,342 198,195 206,298 171,674 189,822 194,614 194,905 189,527

MS 116,714 120,243 121,528 122,557 110,430 123,402 125,192 121,033 115,924

AL 148,989 149,172 154,287 158,390 163,390 168,558 171,697 168,413 166,237

FL 772,721 808,429 817,571 866,269 893,043 912,409 932,012 922,534 896,923

State Total 2,047,982 2,110,692 2,146,314 2,230,798 2,239,183 2,337,772 2,405,952 2,402,330 2,350,733

1) Economic Impact Areas are defined in Figure 2-2. 

2) The Coastal category refers to counties within EIA's that are directly along the coast of the U.S. 

3) The Statewide category refers to the number of employees within the borders of the entire state. 

4) The leisure/hospitality industry is defined according to the North American Industrial Classification System (NAICS). 

5) The employment figure for any given year corresponds to the total number of employees in December of that year. 

Source: U.S. Dept. of Labor, Bureau of Labor Statistics, 2010. 
Figures and Tables A-67 

Table 4-17 

 

Total Wages Earned by Employees in the Leisure/Hospitality Industry in Selected Geographic Regions 

Region 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Panel A—Economic Impact Area 

TX-1 516,185 544,244 566,896 586,252 627,083 685,028 739,142 746,670 766,750

TX-2 148,743 155,321 158,437 168,256 175,260 190,740 209,082 221,889 237,274

TX-3 3,018,006 3,184,819 3,269,332 3,482,253 3,711,467 4,067,402 4,341,536 4,559,854 4,635,997

LA-1 179,049 190,839 196,760 207,015 252,162 250,432 251,148 257,990 263,543

LA-2 176,741 186,845 195,892 219,352 243,347 280,120 295,347 308,107 314,147

LA-3 446,102 452,046 487,564 498,022 543,970 597,138 633,241 654,806 667,398

LA-4 1,318,417 1,378,771 1,429,488 1,493,019 1,409,983 1,246,477 1,505,206 1,633,224 1,595,567

MS-1 591,065 591,974 608,043 618,987 617,535 453,168 621,439 616,442 560,510

AL-1 281,331 287,381 300,006 305,922 321,934 347,512 371,712 388,644 390,968

FL-1 470,616 508,316 528,008 599,949 655,141 721,483 761,247 738,910 743,731

FL-2 182,944 209,213 210,758 232,143 249,152 270,339 294,144 293,528 291,417

FL-3 1,849,168 1,956,066 2,046,441 2,224,235 2,418,168 2,576,029 2,752,991 2,906,630 2,795,652

FL-4 4,219,638 4,391,881 4,669,982 5,131,115 5,650,225 5,981,862 6,304,312 6,493,402 6,344,752

TX EIA Total 3,682,934 3,884,384 3,994,665 4,236,761 4,513,810 4,943,170 5,289,760 5,528,413 5,640,021

LA EIA Total 2,120,309 2,208,501 2,309,704 2,417,408 2,449,462 2,374,167 2,684,942 2,854,127 2,840,655

MS EIA Total 591,065 591,974 608,043 618,987 617,535 453,168 621,439 616,442 560,510

AL EIA Total 281,331 287,381 300,006 305,922 321,934 347,512 371,712 388,644 390,968

FL EIA Total 6,722,366 7,065,476 7,455,189 8,187,442 8,972,686 9,549,713 10,112,694 10,432,470 10,175,552

EIA Total 13,398,005 14,037,716 14,667,607 15,766,520 16,875,427 17,667,730 19,080,547 19,820,096 19,607,706

Panel B—Coastal 

TX 706,679 737,035 761,880 790,346 834,820 927,109 986,605 994,817 1,027,931

LA 1,401,025 1,459,632 1,512,219 1,578,886 1,503,750 1,359,770 1,631,966 1,764,631 1,734,276

MS 579,122 579,914 595,776 605,542 602,391 433,995 600,226 594,626 539,240

AL 259,024 265,870 279,872 284,844 299,662 324,127 347,209 363,802 367,039

FL 6,309,393 6,624,756 6,991,895 7,687,112 8,410,661 8,955,648 9,456,949 9,762,721 9,522,041

Coastal Total 9,255,243 9,667,207 10,141,642 10,946,730 11,651,284 12,000,649 13,022,955 13,480,597 13,190,527

Panel C—Statewide 

TX 12,226,217 12,630,640 12,936,441 13,601,748 14,407,978 15,653,469 16,677,752 17,490,862 17,674,963

LA 2,674,740 2,762,055 2,886,189 3,028,338 3,069,485 3,013,979 3,336,193 3,530,708 3,511,171

MS 1,714,340 1,746,899 1,778,922 1,840,583 1,872,402 1,789,900 1,990,974 2,024,034 1,915,700

AL 1,682,365 1,730,048 1,800,093 1,882,015 1,998,089 2,124,157 2,244,583 2,344,058 2,345,332

FL 13,388,764 13,677,833 14,336,358 15,686,585 17,089,645 18,132,360 19,354,496 19,990,305 19,103,860

State Total 31,686,426 32,547,475 33,738,003 36,039,269 38,437,599 40,713,865 43,603,998 45,379,967 44,551,026

1) Economic Impact Areas are defined in Figure 2-2. 

2) The Coastal category refers to counties within EIA's that are directly along the coast of the U.S. 

3) The Statewide category refers to the number of employees within the borders of the entire state. 

4) The leisure/hospitality industry is defined according to the North American Industrial Classification System (NAICS) 

5) Wages are presented in thousands of dollars. 

Source: U.S. Dept. of Labor, Bureau of Labor Statistics, 2010. 
A-68 Central Planning Area Supplemental EIS 

Table 4-18 

 

Total Tourism Spending in Gulf Coast States 

(millions of dollars) 

State 2000 2001 2002 2003 2004 2005 2006 2007 2008 

Texas 36,753 35,106 34,238 34,589 37,065 40,790 44,707 44,428 50,874 

Louisiana 9,227 9,266 9,262 9,418 9,964 8,248 6,718 9,021 9,642 

Mississippi 5,282 5,227 5,345 5,489 5,755 5,939 5,633 6,060 6,329 

Alabama 5,487 5,423 5,368 5,627 6,051 6,639 6,998 7,405 7,723 

Florida 60,296 56,166 54,544 56,265 61,118 64,544 66,165 68,820 70,521 

Source: U.S. Travel Association, 2010. 

Table 4-19 

 

Coastal Travel, Tourism, and Recreation Estimates in 2004 

State Employees Payroll Establishments 

Texas 13,712 $366,374 1,626 

Louisiana 4,362 $158,357 544 

Mississippi 12,188 $192,864 148 

Alabama 1,078 $35,407 212 

Florida 31,166 $721,440 2,398 

Gulf Total 62,506 $949,711 4,928 

Source: Kaplan and Whitman, unpublished. 

Table 4-20 

 

Number of Beaches and Beach Participation in Gulf States 

State Number of Beaches1 Beach Visitation2, 3

Texas 168 4,929,000 

Louisiana 28 578,000 

Mississippi 20 956,000 

Alabama 25 1,527,000 

Florida 634 21,989,000 1

 USEPA, 2008. 

2

 U.S. Dept of Agriculture, Forest Service, 2010. 

3

 Beach visitation only refers to visitors originating from within the U.S. 
Figures and Tables A-69 

Table 4-21 

 

Shipwrecks in the Gulf of Mexico Central Planning Area 

Map Area No. of Reported Wrecks Historic Wrecks (verified) 

Bay Marchand 3 1 

Breton Sound 11 0 

Chandeleur 8 0 

East Cameron 49 1 

Eugene Island 98 1 

Ewing Bank 5 1 

Green Canyon 15 2 

Grand Isle 33 3 

Lund 11 0 

Mississippi Canyon 49 11 

Mobile 56 2 

Main Pass 65 0 

South Pelto 16 0 

Sabine Pass (LA) 15 0 

South Marsh Island 33 1 

South Pass 36 1 

Ship Shoal 95 3 

South Timbalier 90 2 

Viosca Knoll 23 4 

Vermilion 62 0 

West Cameron 121 1 

West Delta 62 0 

Walker Ridge 3 0 

TOTAL 959 34 
A-70 Central Planning Area Supplemental EIS 

Table 4-22 

 

OCS and Non-OCS Program Spill Rates 

OCS Program Spill Rates 

<1,000 bbl 

1 bbl 3,357 spills/BBO handled 

1 and <50 bbl 91 spills/BBO handled 

50 bbl and <1,000 bbl 7 spills/BBO handled 

1,000 bbl 

Facility 0.13 spills/BBO handled 

Pipeline 1.38 spills/BBO handled 

Shuttle Tanker 0.72 spills/BBO handled 

At sea 0.29 spills/BBO handled 

In port 0.0.43 spills/BBO handled 

Barge 1.23 spills/BBO handled 

Non-OCS Program Spill Rates 

1,000 bbl rate based on yearly occurrence information 

1,000 bbl 

Tanker Worldwide 0.82 spills/BBO handled 

At sea 0.46 spills/BBO handled 

In port 0.36 spills/BBO handled 

Tanker in U.S. waters 0.72 spills/BBO handled 

At sea 0.29 spills/BBO handled 

In port 0.43 spills/BBO handled 

Barge in U.S. coastal, offshore and inland waters 1.23 spills/BBO handled 

Pipeline rate based on yearly occurrence information 

BBO = billion barrels of oil. 

Source: Anderson and LaBelle, 2000 (page 312 [Table 6], page 313 [Table 7], page 314 [Table 8], 

page 316 [Table 10], page 319 [Table 13]). 
Table 4-23 Classification of the Gulf Economic Impact Areas State Area Labor Market County/Parish State Area Labor Market County State Area Labo

Alabama AL-1 Mobile Baldwin Texas TX-1 Brownsville Cameron Florida FL-1 Pana

Clarke Hidalgo Conecuh Starr Escambia Willacy PensMobile Corpus Christi Aransas Monroe Brooks Washington Duval Wilcox Jim Wells FL-2 Talla

Kenedy 

Mississippi MS-1 Biloxi-Gulfport George Kleberg 

Greene Nueces Hancock Refugio Harrison San Patricio Jackson TX-2 Brazoria Brazoria Pearl River Matagorda Stone Wharton 

Victoria Calhoun Lake 

Louisiana LA-1 Lake Charles Allen Colorado 

Beauregard Dewitt Calcasieu Fayette Cameron Goliad Jefferson Davis Gonzales Vernon Jackson Lavaca Victori a
A-72 Central Planning Area Supplemental EIS Table 4-23. Classification of the Gulf Economic Impact Areas (continued). State Area Labor Market County State Area Labor Market County State Area Labor Market County FL-3 Ocala Citrus LA-2 Lafayette Acadia Marion Evangeline Gainesville Alachua Iberia TX-3 Beaumont - Hardin Bradford Lafayette Port Arthur Jasper Dixie St. Landry Jefferson Gilchrist St. Martin Newton Levy Vermillion Orange Union LA-3 Baton Rouge Ascension Polk Tampa-St. Petersburg Hernando East Baton Rouge Tyler Hillsborough Iberville Houston - Austin Pasco Livingston Galveston Chambers Pinellas Tangipahoa Fort Band FL-4 Ft. Myers Collier West Baton Rouge Galveston Lee Houma Assumption Harris Miami Broward Lafourche Liberty Miami-Dade St. Mary Montgomery Monroe Terrebonne San Jacinto Sarasota Charlotte LA-4 New Orleans Jefferson Waller DeSoto Orleans Washington Manatee Plaquemines Sarasota St. Bernard St. Charles St. James St. John the Baptist St. Tammany Washington 
Table 4-24 Demographic and Employment Baseline Projections for Economic Impact Area TX-1 2005 2010 2011 2012 2013 2014 2015 2020 20

Total Population (in thousands) 1,625.42 1,771.25 1,807.15 1,843.24 1,879.50 1,915.95 1,952.51 2,137.01 2,32

Age Under 19 Years 36.1% 36.4% 36.4% 36.4% 36.4% 36.4% 36.4% 36.6% 3Age 20 to 34 21.0% 20.2% 20.0% 20.0% 19.9% 19.9% 19.8% 18.8% 1Age 35 to 49 18.7% 18.0% 17.8% 17.6% 17.4% 17.3% 17.1% 17.1% 1Age 50 to 64 13.5% 14.6% 14.8% 14.8% 14.9% 14.9% 14.8% 14.5% 1Age 65 and Over 10.7% 10.9% 11.0% 11.2% 11.4% 11.6% 11.9% 13.1% 1

Median Age of Population (years) 33 34 34 34 35 35 35 36 White Population (in thousands) 18.7% 16.8% 16.4% 16.1% 15.8% 15.5% 15.3% 14.1% 1Black Population (in thousands) 1.3% 1.3% 1.3% 1.2% 1.2% 1.2% 1.2% 1.1% Native American Population (in thousands) 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% Asian and Pacific Islander Population (in thousands) 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% Hispanic or Latino Population (in thousands) 79.0% 80.9% 81.2% 81.5% 81.9% 82.1% 82.4% 83.7% 8Male Population (in thousands) 48.7% 48.8% 48.8% 48.8% 48.8% 48.8% 48.8% 48.8% 4Total Employment (in thousands of jobs) 728.91 840.00 864.86 878.23 891.81 905.55 919.48 991.85 1,06

 Farm Employment 1.7% 1.6% 1.6% 1.5% 1.5% 1.5% 1.4% 1.3%  Forestry, Fishing, Related Activities 1.2% 1.1% 1.1% 1.1% 1.0% 1.0% 1.0% 1.0%  Mining 1.8% 2.4% 2.4% 2.3% 2.3% 2.3% 2.3% 2.1%  Utilities 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2%  Construction 7.2% 6.0% 6.0% 6.0% 5.9% 5.9% 5.9% 5.8%  Manufacturing 4.0% 3.2% 3.1% 3.1% 3.0% 3.0% 3.0% 2.7%  Wholesale Trade 2.8% 2.4% 2.4% 2.3% 2.3% 2.3% 2.3% 2.1%  Retail Trade 12.0% 11.4% 11.4% 11.3% 11.3% 11.3% 11.2% 11.1% 1 Transportation and Warehousing 3.3% 3.4% 3.4% 3.4% 3.4% 3.4% 3.4% 3.4%  Information Employment 1.2% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0%  Finance and Insurance 3.1% 3.4% 3.4% 3.4% 3.4% 3.4% 3.4% 3.4%  Real Estate / Rental and Lease 3.0% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9%  Professional and Technical Services 3.4% 3.2% 3.2% 3.2% 3.2% 3.3% 3.3% 3.4%  Management 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.3%  Administrative and Waste Services 5.4% 5.6% 5.7% 5.7% 5.8% 5.8% 5.9% 6.1%  Educational Services 0.8% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0%  Health Care and Social Assistance 15.6% 17.9% 18.0% 18.2% 18.4% 18.6% 18.7% 19.6% 2 Arts, Entertainment, and Recreation 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1%  Accommodation and Food Services 7.2% 7.3% 7.3% 7.3% 7.3% 7.3% 7.3% 7.3%  Other Services, Except Public Administration 6.5% 6.3% 6.3% 6.3% 6.3% 6.3% 6.3% 6.3%  Federal Civilian Government 1.7% 1.8% 1.7% 1.7% 1.7% 1.7% 1.7% 1.6%  Federal Military 1.3% 1.1% 1.1% 1.1% 1.0% 1.0% 1.0% 0.9%  State and Local Government 15.1% 15.7% 15.6% 15.6% 15.6% 15.5% 15.5% 15.3% 1
A-74 Central Planning Area Supplemental EIS Table 4-24. Demographic and Employment Baseline Projections for Economic Impact Area TX-1 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 24,168.27 25,503.71 26,303.90 26,962.27 27,636.74 28,327.69 29,035.50 32,841.93 37,134.15 41,972.31 53,564.65 Farm 1.6% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0.3% 0.3% 0.2% Forestry, Fishing, Related Activities 0.7% 0.7% 0.7% 0.7% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.4% Mining 3.6% 5.4% 5.3% 5.3% 5.3% 5.3% 5.3% 5.3% 5.3% 5.3% 5.3% Utilities 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% Construction 7.5% 6.2% 6.6% 6.5% 6.4% 6.3% 6.3% 5.9% 5.5% 5.1% 4.4% Manufacturing 5.9% 4.8% 4.9% 4.8% 4.8% 4.7% 4.6% 4.3% 4.0% 3.6% 3.1% Wholesale Trade 4.2% 4.0% 4.1% 4.1% 4.0% 4.0% 4.0% 3.8% 3.6% 3.4% 3.1% Retail Trade 8.8% 7.9% 8.0% 7.9% 7.9% 7.9% 7.8% 7.6% 7.4% 7.1% 6.7% Transportation and Warehousing 3.6% 3.6% 3.6% 3.6% 3.6% 3.6% 3.6% 3.5% 3.4% 3.4% 3.3% Information 1.5% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% Finance and Insurance 3.4% 2.9% 2.9% 2.9% 2.9% 3.0% 3.0% 3.1% 3.2% 3.3% 3.5% Real Estate / Rental and Lease 1.4% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% 1.3% Professional and Technical Services 4.6% 3.9% 3.8% 3.8% 3.9% 3.9% 3.9% 4.1% 4.2% 4.3% 4.6% Management 0.1% 0.3% 0.2% 0.2% 0.2% 0.2% 0.3% 0.3% 0.3% 0.4% 0.4% Administrative and Waste Services 3.0% 3.2% 3.2% 3.3% 3.3% 3.3% 3.4% 3.5% 3.7% 3.9% 4.3% Educational Services 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% Health Care and Social Assistance 14.9% 17.9% 18.0% 18.2% 18.4% 18.6% 18.8% 19.8% 20.8% 21.8% 23.8% Arts, Entertainment, and Recreation 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% Accommodation and Food Services 3.4% 3.2% 3.2% 3.2% 3.2% 3.2% 3.2% 3.1% 3.1% 3.1% 3.0% Other Services, Except Public Administration 4.5% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% 4.1% Federal Civilian Government 4.9% 5.6% 5.5% 5.5% 5.4% 5.4% 5.4% 5.2% 5.1% 4.9% 4.6% Federal Military 2.8% 2.8% 2.8% 2.7% 2.7% 2.7% 2.6% 2.5% 2.4% 2.3% 2.0% State and Local Government 17.8% 18.8% 18.7% 18.7% 18.7% 18.7% 18.8% 18.8% 18.9% 18.9% 18.8% Total Personal Income Per Capita (in 2005 dollars) 21,146 22,321 22,304 22,511 22,729 22,955 23,191 24,519 26,103 27,956 32,387 Woods & Poole Economics Wealth Index (U.S. = 100) 68.3 75.0 74.8 74.9 75.0 75.2 75.3 75.9 76.5 77.0 77.8 Persons Per Household (in number of people) 3.3 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.1 3.1 3.2 Mean Household Total Personal Income (in 2005 dollars) 69,895 79,290 79,758 80,471 81,303 82,071 82,820 87,661 93,266 100,012 116,180 Number of Households (in thousands) 499.93 548.88 560.61 573.81 586.98 600.13 613.23 677.74 740.82 801.64 914.78 Income < $10,000 (thousands of households, 2000 dollars) 15.6% 14.2% 13.9% 13.7% 13.5% 13.3% 13.1% 12.0% 10.6% 9.0% 6.7% Income $10,000 to $19,999 17.6% 16.0% 15.7% 15.5% 15.2% 15.0% 14.8% 13.6% 12.0% 10.2% 7.6% Income $20,000 to $29,999 15.0% 13.8% 13.6% 13.4% 13.2% 13.0% 12.8% 11.7% 10.3% 8.8% 6.5% Income $30,000 to $44,999 18.8% 19.9% 20.0% 20.1% 20.2% 20.3% 20.4% 20.5% 19.8% 17.5% 13.0% Income $45,000 to $59,999 12.5% 13.7% 14.0% 14.2% 14.4% 14.6% 14.8% 16.0% 17.7% 19.7% 19.7% Income $60,000 to $74,999 7.7% 8.5% 8.6% 8.7% 8.9% 9.0% 9.1% 9.9% 11.2% 13.1% 17.3% Income $75,000 to $99,999 6.6% 7.2% 7.3% 7.4% 7.5% 7.7% 7.8% 8.4% 9.5% 11.1% 15.0% Income $100,000 or more 6.1% 6.7% 6.8% 6.9% 7.1% 7.2% 7.3% 7.9% 8.9% 10.5% 14.2% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 13 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-25 Demographic and Employment Baseline Projections for Economic Impact Area TX-2 2005 2010 2011 2012 2013 2014 2015 2020 202

Total Population (in thousands) 579.99 626.33 634.39 642.51 650.70 658.94 667.23 709.17 75

Age Under 19 Years 29.7% 29.4% 29.3% 29.3% 29.2% 29.2% 29.1% 29.1% 28Age 20 to 34 18.6% 18.9% 19.2% 19.3% 19.4% 19.3% 19.2% 19.1% 19Age 35 to 49 22.5% 20.5% 20.0% 19.5% 19.1% 18.9% 18.7% 18.1% 17Age 50 to 64 16.8% 18.5% 18.8% 18.9% 19.1% 19.2% 19.2% 18.4% 17Age 65 and Over 12.3% 12.6% 12.7% 13.0% 13.2% 13.5% 13.7% 15.3% 17

Median Age of Population (in years) 39 40 40 39 39 39 39 39 White Population (in thousands) 58.9% 55.1% 54.5% 53.8% 53.2% 52.6% 51.9% 48.8% 45Black Population (in thousands) 9.1% 9.9% 10.0% 10.0% 10.1% 10.2% 10.3% 10.7% 11Native American Population (in thousands) 0.3% 0.3% 0.3% 0.3% 0.4% 0.4% 0.4% 0.4% 0Asian and Pacific Islander Population (in thousands) 2.3% 3.1% 3.2% 3.2% 3.3% 3.3% 3.4% 3.5% 3Hispanic or Latino Population (in thousands) 29.4% 31.5% 32.0% 32.6% 33.1% 33.6% 34.1% 36.6% 39Male Population (in thousands) 50.4% 50.4% 50.4% 50.4% 50.4% 50.4% 50.4% 50.4% 50Total Employment (in thousands of jobs) 287.61 309.97 317.96 321.85 325.78 329.76 333.78 354.48 37

 Farm Employment 7.4% 7.0% 6.9% 6.8% 6.7% 6.7% 6.6% 6.2% 5 Forestry, Fishing, Related Activities 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1 Mining 2.4% 3.4% 3.4% 3.4% 3.3% 3.3% 3.3% 3.2% 3 Utilities 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0 Construction 9.6% 7.5% 7.5% 7.6% 7.6% 7.7% 7.8% 8.0% 8 Manufacturing 9.7% 9.2% 9.1% 9.0% 8.9% 8.8% 8.7% 8.2% 7 Wholesale Trade 2.7% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2 Retail Trade 11.3% 11.0% 11.0% 11.0% 11.0% 11.0% 11.0% 10.9% 10 Transportation and Warehousing 2.9% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% 3.1% 3 Information Employment 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7% 0 Finance and Insurance 3.4% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3 Real Estate / Rental and Lease 3.4% 3.6% 3.6% 3.6% 3.6% 3.6% 3.7% 3.7% 3 Professional and Technical Services 3.9% 4.1% 4.1% 4.1% 4.2% 4.2% 4.2% 4.4% 4 Federal Civilian Government 0.5% 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0 Federal Military 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0 State and Local Government 12.9% 13.4% 13.4% 13.4% 13.4% 13.3% 13.3% 13.3% 13 Management 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0 Administrative and Waste Services 4.6% 4.3% 4.3% 4.4% 4.4% 4.5% 4.5% 4.7% 5 Educational Services 0.9% 1.3% 1.3% 1.3% 1.4% 1.4% 1.4% 1.5% 1 Health Care and Social Assistance 7.7% 8.9% 8.9% 9.0% 9.1% 9.1% 9.2% 9.6% 10 Arts, Entertainment, and Recreation 1.2% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1 Accommodation and Food Services 5.6% 5.7% 5.7% 5.7% 5.7% 5.7% 5.7% 5.6% 5 Other Services, Except Public Administration 6.5% 6.2% 6.3% 6.3% 6.3% 6.3% 6.3% 6.3% 6
A-76 Central Planning Area Supplemental EIS Table 4-25. Demographic and Employment Baseline Projections for Economic Impact Area TX-2 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 10,282.28 10,218.80 10,728.94 10,949.05 11,173.46 11,402.24 11,635.47 12,871.31 14,231.04 15,725.90 19,170.07 Farm Employment 3.5% 1.4% 1.2% 1.2% 1.2% 1.2% 1.1% 1.0% 0.9% 0.8% 0.7% Forestry, Fishing, Related Activities 0.7% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% Mining 4.3% 6.0% 5.8% 5.8% 5.8% 5.9% 5.9% 6.1% 6.3% 6.4% 6.8% Utilities 1.6% 1.5% 1.4% 1.4% 1.4% 1.4% 1.5% 1.5% 1.6% 1.7% 1.8% Construction 11.7% 9.1% 10.1% 10.1% 10.0% 10.0% 10.0% 9.8% 9.6% 9.5% 9.0% Manufacturing 20.2% 19.4% 19.6% 19.4% 19.1% 18.9% 18.7% 17.7% 16.8% 15.8% 14.0% Wholesale Trade 3.5% 3.8% 3.7% 3.7% 3.7% 3.7% 3.7% 3.8% 3.8% 3.8% 3.9% Retail Trade 8.1% 7.8% 7.7% 7.7% 7.7% 7.7% 7.7% 7.6% 7.5% 7.4% 7.2% Transportation and Warehousing 3.5% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.8% 3.8% Information Employment 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7% 0.7% 0.7% 0.6% Finance and Insurance 3.0% 3.2% 3.3% 3.3% 3.4% 3.4% 3.4% 3.5% 3.6% 3.7% 3.8% Real Estate / Rental and Lease 1.5% 1.7% 1.6% 1.6% 1.7% 1.7% 1.7% 1.8% 1.8% 1.9% 2.1% Professional and Technical Services 3.9% 4.1% 4.1% 4.1% 4.2% 4.2% 4.3% 4.5% 4.7% 5.0% 5.5% Management 0.1% 0.2% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.4% Administrative and Waste Services 2.5% 2.6% 2.6% 2.6% 2.7% 2.7% 2.7% 2.9% 3.1% 3.3% 3.7% Educational Services 0.5% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% 0.8% 0.9% 1.0% Health Care and Social Assistance 7.5% 8.5% 8.6% 8.7% 8.7% 8.8% 8.9% 9.2% 9.6% 10.0% 10.8% Arts, Entertainment, and Recreation 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% Accommodation and Food Services 2.2% 2.5% 2.4% 2.4% 2.4% 2.4% 2.4% 2.3% 2.3% 2.2% 2.2% Other Services, Except Public Administration 5.2% 4.9% 4.7% 4.7% 4.7% 4.7% 4.8% 4.8% 4.8% 4.8% 4.7% Federal Civilian Government 0.9% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% Federal Military 0.6% 0.7% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% State and Local Government 13.9% 15.5% 15.1% 15.1% 15.2% 15.2% 15.2% 15.4% 15.5% 15.5% 15.6% Total Personal Income Per Capita (in 2005 dollars) 29,643 30,101 30,571 30,892 31,211 31,533 31,862 33,626 35,635 37,920 43,270 Woods & Poole Economics Wealth Index (U.S. = 100) 79.0 80.7 81.0 81.2 81.4 81.6 81.8 82.8 83.8 84.8 86.9 Persons Per Household (in number of people) 2.8 2.8 2.8 2.8 2.7 2.7 2.7 2.7 2.7 2.7 2.8 Mean Household Total Personal Income (in 2005 dollars) 71,979 73,706 75,027 75,915 76,840 77,800 78,796 84,429 91,140 99,046 118,671 Total Number of Households (in thousands) 208.95 226.47 229.54 233.19 236.81 240.39 243.95 261.04 277.09 291.82 317.15 Income < $10,000 (thousands of households, 2000 dollars) 9.6% 8.8% 8.5% 8.4% 8.2% 8.1% 7.9% 7.1% 6.3% 5.5% 4.2% Income $10,000 to $19,999 12.9% 11.8% 11.6% 11.4% 11.2% 11.0% 10.7% 9.7% 8.7% 7.6% 5.8% Income $20,000 to $29,999 12.9% 11.9% 11.7% 11.5% 11.3% 11.1% 10.9% 9.8% 8.9% 7.8% 6.0% Income $30,000 to $44,999 17.5% 16.9% 16.7% 16.5% 16.3% 16.1% 15.9% 14.5% 13.1% 11.5% 8.8% Income $45,000 to $59,999 14.4% 15.0% 15.2% 15.3% 15.4% 15.6% 15.7% 16.1% 15.7% 14.2% 10.8% Income $60,000 to $74,999 11.3% 12.1% 12.4% 12.6% 12.8% 13.0% 13.3% 14.6% 16.1% 17.6% 17.2% Income $75,000 to $99,999 11.0% 11.9% 12.2% 12.4% 12.6% 12.8% 13.0% 14.4% 15.9% 18.1% 24.0% Income $100,000 or More 10.6% 11.5% 11.8% 12.0% 12.2% 12.4% 12.6% 13.9% 15.4% 17.5% 23.3% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 12 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-26 Demographic and Employment Baseline Projections for Economic Impact Area TX-3 2005 2010 2011 2012 2013 2014 2015 2020 2025 

Total Population (in thousands) 5,552.60 6,192.43 6,299.99 6,408.25 6,517.13 6,626.68 6,736.63 7,292.42 7,855.

Age Under 19 years 30.9% 30.8% 30.7% 30.6% 30.6% 30.5% 30.4% 30.2% 29.7Age 20 to 34 22.3% 21.8% 21.8% 21.7% 21.7% 21.6% 21.5% 21.2% 21.4Age 35 to 49 22.7% 21.2% 20.9% 20.6% 20.4% 20.3% 20.2% 19.7% 19.1Age 50 to 64 15.6% 17.1% 17.4% 17.4% 17.5% 17.5% 17.5% 16.9% 16.1Age 65 and over 8.6% 9.1% 9.3% 9.5% 9.8% 10.1% 10.4% 12.0% 13.7

Median Age of Population (in years) 37 38 38 38 38 38 38 38 White Population (in thousands) 46.5% 43.0% 42.3% 41.7% 41.1% 40.4% 39.8% 36.8% 33.9Black Population (in thousands) 17.4% 17.4% 17.3% 17.2% 17.0% 16.9% 16.8% 16.3% 15.7Native American Population (in thousands) 0.3% 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4Asian and Pacific Islander Population (in thousands) 5.4% 5.9% 6.1% 6.2% 6.3% 6.4% 6.5% 7.1% 7.6Hispanic or Latino Population (in thousands) 30.4% 33.4% 34.0% 34.6% 35.2% 35.9% 36.5% 39.5% 42.4Male Population (in thousands) 50.0% 50.1% 50.1% 50.1% 50.0% 50.0% 50.0% 49.9% 49.8Total Employment (in thousands of jobs) 3,218.66 3,596.00 3,700.61 3,758.99 3,818.15 3,878.09 3,938.83 4,254.86 4,592.

 Farm Employment 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5 Forestry, Fishing, Related Activities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2 Mining 2.8% 3.5% 3.4% 3.4% 3.4% 3.3% 3.3% 3.1% 2.9 Utilities 0.5% 0.6% 0.6% 0.6% 0.5% 0.5% 0.5% 0.5% 0.5 Construction 8.0% 7.2% 7.3% 7.3% 7.3% 7.3% 7.4% 7.5% 7.6 Manufacturing 7.4% 7.4% 7.3% 7.2% 7.2% 7.1% 7.0% 6.6% 6.2 Wholesale Trade 4.5% 4.3% 4.3% 4.3% 4.3% 4.2% 4.2% 4.2% 4.2 Retail Trade 10.2% 9.4% 9.4% 9.4% 9.4% 9.4% 9.4% 9.3% 9.3 Transportation and Warehousing 4.3% 4.3% 4.3% 4.3% 4.3% 4.3% 4.3% 4.2% 4.2 Information Employment 1.5% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2 Finance and Insurance 4.5% 4.5% 4.5% 4.5% 4.5% 4.5% 4.5% 4.5% 4.5 Real Estate / Rental and Lease 4.1% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9 Professional and Technical Services 7.8% 8.0% 8.0% 8.0% 8.1% 8.1% 8.2% 8.5% 8.7 Management 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8 Administrative and Waste Services 7.4% 7.1% 7.1% 7.2% 7.2% 7.3% 7.3% 7.6% 7.9 Educational Services 1.6% 1.7% 1.7% 1.8% 1.8% 1.8% 1.8% 1.8% 1.9 Health Care and Social Assistance 8.2% 9.5% 9.5% 9.6% 9.6% 9.6% 9.7% 9.9% 10.1 Arts, Entertainment, and Recreation 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5 Accommodation and Food Services 6.5% 6.7% 6.7% 6.7% 6.7% 6.7% 6.7% 6.7% 6.7 Other Services, Except Public Administration 6.0% 5.8% 5.9% 5.9% 5.9% 5.9% 5.9% 6.0% 6.1 Federal Civilian Government 1.0% 0.9% 0.9% 0.9% 0.9% 0.8% 0.8% 0.8% 0.7 Federal Military 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3 State and Local Government 10.3% 10.5% 10.5% 10.4% 10.4% 10.4% 10.4% 10.3% 10.1
A-78 Central Planning Area Supplemental EIS Table 4-26. Demographic and Employment Baseline Projections for Economic Impact Area TX-3 (continued) 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 186,536.19 200,395.27 208,221.43 213,342.61 218,582.25 223,942.87 229,427.07 258,795.84 291,672.20 328,441.16 415,393.44 Farm Employment 0.1% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% Forestry, Fishing, Related Activities 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% Mining 12.3% 13.9% 13.7% 13.8% 13.8% 13.9% 13.9% 14.2% 14.4% 14.6% 15.0% Utilities 1.6% 2.2% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.0% Construction 8.2% 6.8% 7.3% 7.2% 7.2% 7.1% 7.1% 6.9% 6.6% 6.4% 5.9% Manufacturing 11.7% 11.5% 11.8% 11.7% 11.5% 11.4% 11.3% 10.6% 10.0% 9.4% 8.4% Wholesale Trade 6.2% 6.1% 6.2% 6.2% 6.2% 6.2% 6.2% 6.2% 6.3% 6.3% 6.3% Retail Trade 5.2% 4.6% 4.6% 4.6% 4.6% 4.5% 4.5% 4.4% 4.3% 4.2% 4.0% Transportation and Warehousing 5.6% 5.6% 5.6% 5.6% 5.5% 5.5% 5.5% 5.3% 5.2% 5.1% 4.8% Information Employment 1.7% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.3% 1.2% 1.2% 1.1% Finance and Insurance 5.5% 5.2% 5.2% 5.2% 5.2% 5.2% 5.3% 5.4% 5.4% 5.5% 5.6% Real Estate / Rental and Lease 2.4% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.6% 1.6% 1.7% Professional and Technical Services 10.8% 10.8% 10.7% 10.8% 10.8% 10.9% 11.0% 11.4% 11.8% 12.2% 13.0% Management 0.6% 1.2% 1.2% 1.2% 1.2% 1.2% 1.3% 1.4% 1.5% 1.6% 1.8% Administrative and Waste Services 4.4% 3.9% 4.0% 4.0% 4.1% 4.1% 4.1% 4.3% 4.6% 4.8% 5.2% Educational Services 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.1% 1.1% 1.1% 1.2% Health Care and Social Assistance 6.5% 7.2% 7.1% 7.2% 7.2% 7.2% 7.3% 7.4% 7.5% 7.7% 7.9% Arts, Entertainment, and Recreation 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6% 0.6% 0.6% Accommodation and Food Services 2.3% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.1% 2.1% 2.1% Other Services, Except Public Administration 3.1% 2.9% 2.8% 2.8% 2.8% 2.8% 2.8% 2.9% 2.9% 2.9% 2.9% Federal Civilian Government 1.7% 1.7% 1.7% 1.7% 1.6% 1.6% 1.6% 1.6% 1.5% 1.5% 1.4% Federal Military 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0.3% State and Local Government 8.3% 8.9% 8.8% 8.8% 8.8% 8.8% 8.8% 8.8% 8.8% 8.7% 8.6% Total Personal Income Per Capita (in 2005 dollars) 38,941 38,315 39,041 39,421 39,818 40,231 40,661 43,035 45,798 48,984 56,613 Woods & Poole Economics Wealth Index (U.S. = 100) 85.7 87.4 87.9 87.8 87.6 87.5 87.4 86.9 86.7 86.7 87.2 Persons Per Household (in number of people) 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.9 Mean Household Total Personal Income (in 2005 dollars) 80,484 82,582 84,242 84,841 85,460 86,115 86,816 91,101 96,652 103,525 121,269 Total Number of Households (in thousands) 1,988.28 2,215.36 2,252.62 2,295.55 2,338.22 2,380.57 2,422.51 2,625.44 2,817.83 2,996.74 3,310.18 Income < $10,000 (thousands of households, 2000 dollars) 8.7% 8.2% 8.0% 7.9% 7.7% 7.6% 7.4% 6.7% 6.0% 5.4% 4.2% Income $10,000 to $19,999 11.0% 10.4% 10.1% 10.0% 9.8% 9.7% 9.5% 8.6% 7.7% 6.9% 5.5% Income $20,000 to $29,999 12.0% 11.4% 11.1% 11.0% 10.8% 10.6% 10.4% 9.4% 8.5% 7.6% 6.0% Income $30,000 to $44,999 16.8% 16.1% 15.8% 15.6% 15.4% 15.1% 14.8% 13.5% 12.2% 11.0% 8.7% Income $45,000 to $59,999 14.0% 14.4% 14.5% 14.5% 14.6% 14.6% 14.6% 14.2% 13.1% 11.9% 9.4% Income $60,000 to $74,999 10.8% 11.3% 11.5% 11.7% 11.9% 12.1% 12.3% 13.4% 14.4% 14.9% 13.3% Income $75,000 to $99,999 11.4% 12.0% 12.3% 12.4% 12.6% 12.9% 13.1% 14.4% 16.0% 17.8% 21.5% Income $100,000 or more 15.4% 16.3% 16.7% 16.9% 17.2% 17.5% 17.9% 19.7% 22.0% 24.6% 31.3% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 17 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-27 Demographic and Employment Baseline Projections for Economic Impact Area LA1 2005 2010 2011 2012 2013 2014 2015 2020 20

Total Population (in thousands) 334.22 334.72 336.53 338.39 340.27 342.20 344.15 354.20 3

Age Under 19 years 29.2% 28.5% 28.4% 28.3% 28.3% 28.2% 28.2% 28.1% 2Age 20 to 34 21.8% 21.9% 21.9% 21.9% 21.7% 21.4% 20.8% 19.6% 1Age 35 to 49 20.9% 18.9% 18.5% 18.3% 18.1% 18.1% 18.4% 18.6% 1Age 50 to 64 16.2% 18.1% 18.5% 18.6% 18.8% 18.9% 19.0% 18.4% 1Age 65 and over 11.9% 12.6% 12.6% 12.9% 13.2% 13.4% 13.6% 15.2% 1

Median Age of Population (in years) 35 35 36 36 36 36 36 38 White Population (in thousands) 74.6% 73.9% 73.8% 73.8% 73.7% 73.6% 73.6% 73.2% 7Black Population (in thousands) 20.8% 20.7% 20.7% 20.7% 20.7% 20.7% 20.6% 20.5% 2Native American Population (in thousands) 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% Asian and Pacific Islander Population (in thousands) 1.0% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.3% Hispanic or Latino Population (in thousands) 3.0% 3.5% 3.6% 3.7% 3.8% 3.8% 3.9% 4.3% Male Population (in thousands) 49.9% 49.8% 49.8% 49.8% 49.8% 49.8% 49.8% 49.8% 4Total Employment (in thousands of jobs) 171.65 177.73 182.05 183.91 185.81 187.70 189.62 199.43 2

 Farm Employment 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% 1.8% 1.8%  Forestry, Fishing, Related Activities 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0%  Mining 1.1% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1%  Utilities 0.4% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3%  Construction 8.7% 8.9% 9.0% 9.0% 9.0% 9.1% 9.1% 9.3%  Manufacturing 6.7% 6.7% 6.6% 6.5% 6.4% 6.4% 6.3% 5.9%  Wholesale Trade 2.2% 2.0% 2.0% 2.0% 1.9% 1.9% 1.9% 1.8%  Retail Trade 11.0% 10.4% 10.4% 10.4% 10.4% 10.4% 10.4% 10.3% 1 Transportation and Warehousing 3.2% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8%  Information Employment 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 0.9%  Finance and Insurance 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.4% 2.4%  Real Estate / Rental and Lease 2.4% 2.4% 2.4% 2.4% 2.4% 2.5% 2.5% 2.5%  Professional and Technical Services 4.7% 4.5% 4.5% 4.5% 4.6% 4.6% 4.7% 4.9%  Management 0.7% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6%  Administrative and Waste Services 3.8% 4.9% 5.0% 5.0% 5.1% 5.2% 5.3% 5.8%  Educational Services 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%  Health Care and Social Assistance 9.5% 10.7% 10.8% 10.9% 11.0% 11.1% 11.2% 11.8% 1 Arts, Entertainment, and Recreation 2.3% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1%  Accommodation and Food Services 7.9% 7.6% 7.6% 7.6% 7.6% 7.6% 7.6% 7.7%  Other Services, Except Public Administration 6.2% 5.8% 5.8% 5.8% 5.9% 5.9% 6.0% 6.2%  Federal Civilian Government 2.1% 2.0% 2.0% 2.0% 2.0% 1.9% 1.9% 1.8%  Federal Military 5.7% 5.8% 5.8% 5.7% 5.6% 5.6% 5.5% 5.2%  State and Local Government 14.0% 14.8% 14.8% 14.7% 14.6% 14.5% 14.4% 14.0% 1
A-80 Central Planning Area Supplemental EIS Table 4-27. Demographic and Employment Baseline Projections for Economic Impact Area LA-1 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 6,873.26 7,285.45 7,545.69 7,677.77 7,811.98 7,948.32 8,086.83 8,813.22 9,599.12 10,449.14 12,361.78 Farm Employment 0.5% 0.8% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.4% Forestry, Fishing, Related Activities 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% Mining 1.7% 2.3% 1.9% 1.9% 1.9% 1.9% 1.9% 2.0% 2.0% 2.0% 2.1% Utilities 0.8% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% Construction 7.6% 10.9% 11.8% 11.7% 11.7% 11.6% 11.6% 11.3% 11.0% 10.7% 10.0% Manufacturing 14.6% 12.5% 12.7% 12.6% 12.4% 12.3% 12.2% 11.5% 10.8% 10.2% 8.9% Wholesale Trade 2.7% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2.3% 2.2% 2.2% 2.0% Retail Trade 6.3% 5.6% 5.6% 5.6% 5.5% 5.5% 5.5% 5.5% 5.4% 5.4% 5.2% Transportation and Warehousing 3.6% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 2.9% 2.8% 2.8% 2.8% Information Employment 2.6% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.3% 2.3% Finance and Insurance 2.3% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% Real Estate / Rental and Lease 1.2% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% 1.3% 1.3% 1.4% 1.6% Professional and Technical Services 5.4% 5.4% 5.3% 5.4% 5.5% 5.5% 5.6% 6.0% 6.3% 6.7% 7.4% Management 1.5% 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% Administrative and Waste Services 2.2% 3.0% 3.0% 3.1% 3.2% 3.2% 3.3% 3.7% 4.1% 4.5% 5.5% Educational Services 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Health Care and Social Assistance 8.7% 9.2% 9.2% 9.3% 9.4% 9.5% 9.7% 10.2% 10.8% 11.4% 12.6% Arts, Entertainment, and Recreation 1.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% Accommodation and Food Services 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.8% Other Services, Except Public Administration 3.7% 3.0% 3.0% 3.0% 3.1% 3.1% 3.1% 3.2% 3.3% 3.4% 3.7% Federal Civilian Government 3.8% 4.1% 4.0% 4.0% 4.0% 4.0% 3.9% 3.9% 3.8% 3.7% 3.6% Federal Military 10.6% 11.4% 11.3% 11.3% 11.2% 11.2% 11.2% 11.0% 10.8% 10.6% 10.1% State and Local Government 13.8% 14.1% 13.8% 13.8% 13.8% 13.8% 13.7% 13.6% 13.4% 13.2% 12.8% Total Personal Income Per Capita (in 2005 dollars) 27,573 29,916 30,288 30,714 31,145 31,584 32,032 34,415 37,065 39,997 46,695 Woods & Poole Economics Wealth Index (U.S. = 100) 70.1 84.8 84.6 84.8 85.0 85.2 85.4 86.4 87.4 88.4 90.3 Persons Per Household (in number of people) 2.7 2.7 2.7 2.7 2.7 2.7 2.6 2.6 2.6 2.6 2.6 Mean Household Total Personal Income (in 2005 dollars) 66,070 78,879 79,669 80,570 81,502 82,473 83,478 89,133 95,837 103,681 123,003 Total Number of Households (in thousands) 123.62 124.83 125.65 126.79 127.92 129.02 130.11 135.19 139.77 143.78 150.15 Income < $10,000 (thousands of households, 2000 dollars) 12.1% 10.9% 10.6% 10.5% 10.3% 10.1% 9.9% 8.7% 7.5% 6.4% 4.8% Income $10,000 to $19,999 14.8% 13.3% 13.0% 12.8% 12.6% 12.3% 12.1% 10.6% 9.2% 7.8% 5.8% Income $20,000 to $29,999 13.0% 11.6% 11.3% 11.1% 10.9% 10.7% 10.5% 9.2% 7.9% 6.8% 5.0% Income $30,000 to $44,999 19.5% 18.6% 18.4% 18.2% 17.9% 17.6% 17.4% 15.3% 13.2% 11.3% 8.3% Income $45,000 to $59,999 15.2% 17.0% 17.4% 17.7% 18.0% 18.3% 18.6% 20.1% 20.1% 18.3% 13.8% Income $60,000 to $74,999 9.6% 10.8% 11.1% 11.3% 11.5% 11.7% 11.9% 13.7% 16.0% 18.7% 20.4% Income $75,000 to $99,999 8.9% 9.9% 10.2% 10.3% 10.5% 10.7% 10.9% 12.5% 14.7% 17.4% 23.7% Income $100,000 or more 6.9% 7.8% 8.0% 8.1% 8.2% 8.4% 8.5% 9.7% 11.4% 13.4% 18.2% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 6 parishes in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-28 Demographic and Employment Baseline Projections for Economic Impact Area LA-2 2005 2010 2011 2012 2013 2014 2015 2020 20

Total Population (in thousands) 558.39 587.88 593.59 599.38 605.23 611.14 617.10 647.47 67

Age Under 19 years 29.9% 28.9% 28.8% 28.7% 28.5% 28.5% 28.4% 28.2% 2Age 20 to 34 21.0% 22.0% 22.1% 22.0% 21.8% 21.5% 21.0% 19.5% 1Age 35 to 49 21.6% 19.1% 18.7% 18.4% 18.3% 18.3% 18.5% 19.3% 2Age 50 to 64 15.9% 18.0% 18.4% 18.6% 18.8% 18.9% 18.9% 18.4% 1Age 65 and over 11.6% 12.0% 12.1% 12.3% 12.6% 12.8% 13.1% 14.7% 1

Median Age of Population (in years) 35 35 35 35 35 35 36 37 White Population (in thousands) 69.1% 68.3% 68.2% 68.1% 68.0% 67.9% 67.8% 67.2% 6Black Population (in thousands) 27.7% 28.0% 28.0% 28.0% 28.1% 28.1% 28.2% 28.4% 2Native American Population (in thousands) 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% Asian and Pacific Islander Population (in thousands) 1.2% 1.2% 1.3% 1.3% 1.3% 1.3% 1.3% 1.5% Hispanic or Latino Population (in thousands) 1.7% 2.2% 2.2% 2.3% 2.3% 2.4% 2.4% 2.7% Male Population (in thousands) 48.6% 48.7% 48.7% 48.7% 48.8% 48.8% 48.8% 48.9% 4Total Employment (in thousands of jobs) 297.51 321.93 330.21 334.03 337.89 341.78 345.70 365.76 38

 Farm Employment 1.9% 1.8% 1.8% 1.8% 1.7% 1.7% 1.7% 1.6%  Forestry, Fishing, Related Activities 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5%  Mining 6.9% 8.3% 8.3% 8.3% 8.2% 8.2% 8.2% 8.0%  Utilities 0.2% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2% 0.2%  Construction 6.7% 6.8% 6.8% 6.8% 6.7% 6.7% 6.7% 6.5%  Manufacturing 6.1% 5.9% 5.8% 5.7% 5.6% 5.6% 5.5% 5.1%  Wholesale Trade 3.7% 3.6% 3.6% 3.5% 3.5% 3.5% 3.5% 3.4%  Retail Trade 11.5% 11.2% 11.2% 11.2% 11.1% 11.1% 11.1% 10.9% 1 Transportation and Warehousing 3.5% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0%  Information Employment 1.5% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2%  Finance and Insurance 3.4% 3.2% 3.2% 3.2% 3.2% 3.1% 3.1% 3.1%  Real Estate / Rental and Lease 4.0% 3.4% 3.4% 3.4% 3.4% 3.4% 3.4% 3.3%  Professional and Technical Services 4.7% 5.2% 5.2% 5.3% 5.3% 5.3% 5.4% 5.5%  Management 1.1% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%  Administrative and Waste Services 4.6% 4.9% 4.9% 4.9% 4.9% 5.0% 5.0% 5.2%  Educational Services 1.2% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5%  Health Care and Social Assistance 11.2% 12.0% 12.1% 12.3% 12.5% 12.6% 12.8% 13.6% 1 Arts, Entertainment, and Recreation 1.5% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.5%  Accommodation and Food Services 6.4% 6.4% 6.4% 6.4% 6.4% 6.4% 6.4% 6.5%  Other Services, Except Public Administration 7.0% 7.0% 7.1% 7.1% 7.2% 7.2% 7.3% 7.6%  Federal Civilian Government 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5%  Federal Military 0.9% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%  State and Local Government 10.8% 10.2% 10.2% 10.1% 10.1% 10.0% 9.9% 9.7% 
A-82 Central Planning Area Supplemental EIS Table 4-28. Demographic and Employment Baseline Projections for Economic Impact Area LA-2 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 11,484.00 12,782.07 13,132.04 13,420.62 13,715.20 14,015.87 14,322.73 15,953.99 17,757.47 19,748.33 24,357.40 Farm Employment 0.8% 1.5% 1.3% 1.3% 1.3% 1.2% 1.2% 1.1% 1.0% 0.9% 0.8% Forestry, Fishing, Related Activities 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.2% 0.2% 0.2% Mining 13.7% 17.7% 17.7% 17.8% 17.9% 18.0% 18.1% 18.7% 19.3% 19.9% 21.0% Utilities 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% Construction 7.1% 6.0% 6.3% 6.2% 6.1% 6.0% 5.9% 5.4% 4.9% 4.5% 3.8% Manufacturing 7.5% 7.6% 7.7% 7.6% 7.5% 7.4% 7.3% 6.8% 6.3% 5.9% 5.1% Wholesale Trade 4.7% 4.8% 5.0% 4.9% 4.9% 4.9% 4.9% 4.9% 4.8% 4.7% 4.5% Retail Trade 7.9% 7.7% 7.8% 7.7% 7.7% 7.6% 7.5% 7.3% 7.0% 6.7% 6.2% Transportation and Warehousing 4.6% 3.8% 3.7% 3.7% 3.7% 3.7% 3.7% 3.6% 3.6% 3.6% 3.5% Information Employment 1.7% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.2% Finance and Insurance 4.1% 2.9% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% 3.0% Real Estate / Rental and Lease 3.5% 2.6% 2.6% 2.6% 2.7% 2.7% 2.7% 2.7% 2.7% 2.8% 2.8% Professional and Technical Services 6.0% 6.1% 6.1% 6.1% 6.1% 6.2% 6.2% 6.3% 6.4% 6.5% 6.7% Management 1.6% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.5% 1.5% 1.6% 1.7% Administrative and Waste Services 3.1% 2.9% 2.9% 2.9% 3.0% 3.0% 3.0% 3.1% 3.2% 3.2% 3.4% Educational Services 0.7% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.7% 0.7% Health Care and Social Assistance 11.3% 11.6% 11.7% 11.8% 12.0% 12.1% 12.2% 12.9% 13.6% 14.3% 15.7% Arts, Entertainment, and Recreation 0.6% 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Accommodation and Food Services 2.5% 2.6% 2.7% 2.7% 2.7% 2.6% 2.6% 2.6% 2.6% 2.6% 2.5% Other Services, Except Public Administration 4.5% 4.1% 4.1% 4.2% 4.2% 4.2% 4.2% 4.4% 4.5% 4.7% 4.9% Federal Civilian Government 1.2% 1.2% 1.2% 1.2% 1.2% 1.1% 1.1% 1.1% 1.1% 1.0% 0.9% Federal Military 0.9% 0.9% 0.7% 0.7% 0.7% 0.7% 0.6% 0.6% 0.6% 0.6% 0.6% State and Local Government 11.3% 11.3% 11.2% 11.1% 11.1% 11.1% 11.0% 10.8% 10.6% 10.4% 9.9% Total Personal Income (in millions of 2005 dollars) Total Personal Income Per Capita (in 2005 dollars) 28,507 30,706 30,852 31,247 31,645 32,047 32,456 34,618 37,001 39,634 45,589 Woods & Poole Economics Wealth Index (U.S. = 100) 72.7 78.6 77.7 77.7 77.8 77.8 77.8 77.8 77.7 77.7 77.5 Persons Per Household (in number of people) 2.7 2.7 2.7 2.7 2.6 2.6 2.6 2.6 2.6 2.6 2.7 Mean Household Total Personal Income (in 2005 dollars) 68,505 75,359 75,338 76,021 76,720 77,445 78,201 82,488 87,604 93,623 108,360 Total Number of Households (in thousands) 208.17 220.47 222.77 225.63 228.48 231.29 234.07 247.40 259.85 271.19 290.47 Income < $10,000 (thousands of households, 2000 dollars) 15.9% 14.1% 13.9% 13.7% 13.4% 13.2% 13.0% 11.8% 10.4% 8.9% 6.5% Income $10,000 to $19,999 15.2% 13.6% 13.3% 13.1% 12.9% 12.7% 12.6% 11.3% 10.0% 8.6% 6.3% Income $20,000 to $29,999 12.9% 11.7% 11.5% 11.3% 11.2% 11.0% 10.8% 9.8% 8.7% 7.5% 5.5% Income $30,000 to $44,999 18.2% 18.4% 18.3% 18.3% 18.2% 18.1% 18.0% 17.0% 15.5% 13.7% 9.9% Income $45,000 to $59,999 14.1% 15.8% 16.1% 16.3% 16.5% 16.7% 17.0% 18.2% 18.8% 18.9% 16.5% Income $60,000 to $74,999 9.1% 10.2% 10.4% 10.6% 10.7% 10.9% 11.0% 12.3% 14.0% 16.2% 19.4% Income $75,000 to $99,999 7.4% 8.3% 8.5% 8.6% 8.8% 8.9% 9.0% 10.1% 11.5% 13.4% 18.4% Income $100,000 or more 7.1% 7.9% 8.0% 8.2% 8.3% 8.4% 8.5% 9.6% 11.0% 12.8% 17.5% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 7 parishes in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-29 Demographic and Employment Baseline Projections for Economic Impact Area LA-3 2005 2010 2011 2012 2013 2014 2015 2020 20

Total Population (in thousands) 1,039.88 1,126.87 1,140.44 1,154.15 1,167.97 1,181.91 1,195.92 1,266.99 1,3

Age Under 19 years 29.7% 28.8% 28.6% 28.4% 28.3% 28.1% 28.1% 27.9% 2Age 20 to 34 22.4% 23.1% 23.4% 23.5% 23.5% 23.5% 23.1% 21.7% 2Age 35 to 49 21.4% 19.2% 18.7% 18.3% 18.0% 17.9% 17.9% 18.4% 1Age 50 to 64 16.2% 17.8% 18.1% 18.2% 18.3% 18.3% 18.3% 17.7% 1Age 65 and over 10.3% 11.1% 11.3% 11.6% 11.9% 12.2% 12.5% 14.3% 1

Median Age of Population (in years) 35 35 35 35 35 36 36 37 White Population (in thousands) 65.7% 64.0% 63.7% 63.5% 63.3% 63.1% 62.9% 61.8% 6Black Population (in thousands) 29.6% 30.6% 30.7% 30.8% 30.9% 31.0% 31.1% 31.6% 3Native American Population (in thousands) 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.1% Asian and Pacific Islander Population (in thousands) 1.4% 1.4% 1.5% 1.5% 1.5% 1.5% 1.5% 1.6% Hispanic or Latino Population (in thousands) 2.3% 3.0% 3.1% 3.2% 3.3% 3.4% 3.5% 3.9% Male Population (in thousands) 48.7% 48.8% 48.8% 48.8% 48.8% 48.8% 48.8% 48.8% 4Total Employment (in thousands of jobs) 606.81 663.02 680.63 689.17 697.80 706.51 715.33 760.83 8

 Farm Employment 0.7% 0.7% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6%  Forestry, Fishing, Related Activities 0.8% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6%  Mining 1.5% 1.9% 1.9% 1.9% 1.9% 1.8% 1.8% 1.7%  Utilities 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3%  Construction 9.8% 9.3% 9.3% 9.3% 9.4% 9.4% 9.5% 9.6%  Manufacturing 6.8% 6.1% 6.1% 6.0% 5.9% 5.8% 5.7% 5.3%  Wholesale Trade 3.2% 2.8% 2.8% 2.8% 2.8% 2.7% 2.7% 2.6%  Retail Trade 10.9% 10.1% 10.0% 10.0% 10.0% 10.0% 10.0% 9.9%  Transportation and Warehousing 4.4% 4.6% 4.5% 4.5% 4.5% 4.5% 4.5% 4.4%  Information Employment 1.4% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.1%  Finance and Insurance 3.5% 3.3% 3.3% 3.3% 3.3% 3.3% 3.3% 3.2%  Real Estate / Rental and Lease 3.6% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.8%  Professional and Technical Services 4.8% 5.6% 5.6% 5.7% 5.7% 5.7% 5.8% 6.0%  Management 1.0% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0%  Administrative and Waste Services 5.8% 6.1% 6.1% 6.2% 6.3% 6.4% 6.5% 7.1%  Educational Services 1.1% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.6%  Health Care and Social Assistance 8.8% 10.0% 10.1% 10.1% 10.2% 10.3% 10.3% 10.6% 1 Arts, Entertainment, and Recreation 1.3% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4%  Accommodation and Food Services 6.6% 6.7% 6.7% 6.8% 6.8% 6.8% 6.8% 6.9%  Other Services, Except Public Administration 6.7% 6.6% 6.7% 6.7% 6.7% 6.8% 6.8% 7.0%  Federal Civilian Government 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%  Federal Military 0.8% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6%  State and Local Government 15.6% 15.0% 14.9% 14.8% 14.7% 14.5% 14.4% 13.8% 1
A-84 Central Planning Area Supplemental EIS Table 4-29. Demographic and Employment Baseline Projections for Economic Impact Area LA-3 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 24,055.56 27,529.09 28,679.63 29,248.86 29,828.55 30,418.91 31,020.09 34,194.93 37,669.23 41,468.73 50,154.87 Farm Employment 0.3% 0.3% 0.3% 0.3% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% Forestry, Fishing, Related Activities 0.3% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% Mining 2.6% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% Utilities 0.7% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% Construction 10.3% 11.0% 12.0% 11.9% 11.9% 11.8% 11.7% 11.4% 11.1% 10.8% 10.1% Manufacturing 12.4% 11.2% 11.3% 11.2% 11.1% 10.9% 10.8% 10.1% 9.5% 8.9% 7.7% Wholesale Trade 4.4% 3.7% 3.8% 3.7% 3.7% 3.7% 3.7% 3.6% 3.5% 3.4% 3.2% Retail Trade 7.2% 6.4% 6.4% 6.3% 6.3% 6.3% 6.3% 6.2% 6.1% 6.0% 5.8% Transportation and Warehousing 6.0% 6.7% 6.7% 6.7% 6.7% 6.6% 6.6% 6.6% 6.5% 6.4% 6.3% Information Employment 1.7% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% Finance and Insurance 4.3% 3.6% 3.5% 3.5% 3.5% 3.5% 3.5% 3.6% 3.7% 3.8% 4.0% Real Estate / Rental and Lease 2.1% 1.8% 1.7% 1.7% 1.7% 1.8% 1.8% 1.8% 1.9% 2.0% 2.1% Professional and Technical Services 6.0% 6.9% 6.8% 6.9% 6.9% 7.0% 7.0% 7.3% 7.6% 7.9% 8.4% Management 1.4% 1.9% 1.9% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% Administrative and Waste Services 3.5% 3.9% 3.8% 3.9% 4.0% 4.1% 4.2% 4.7% 5.2% 5.7% 7.0% Educational Services 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% 0.7% 0.7% 0.8% 0.8% 1.0% Health Care and Social Assistance 9.2% 9.4% 9.3% 9.3% 9.4% 9.5% 9.6% 9.9% 10.3% 10.6% 11.2% Arts, Entertainment, and Recreation 0.7% 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.5% 0.5% 0.5% Accommodation and Food Services 2.7% 2.6% 2.5% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6% 2.7% 2.7% Other Services, Except Public Administration 4.1% 3.6% 3.5% 3.5% 3.6% 3.6% 3.6% 3.7% 3.8% 3.9% 4.1% Federal Civilian Government 1.2% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.6% 1.6% 1.7% Federal Military 0.9% 0.9% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% State and Local Government 17.5% 17.8% 17.4% 17.3% 17.3% 17.2% 17.2% 16.9% 16.6% 16.3% 15.6% Total Personal Income Per Capita (in 2005 dollars) 30,731 32,203 32,690 33,093 33,505 33,924 34,352 36,628 39,151 41,951 48,338 Woods & Poole Economics Wealth Index (U.S. = 100) 79.2 85.3 85.7 85.7 85.8 85.9 86.0 86.4 86.8 87.2 88.0 Persons Per Household (in number of people) 2.7 2.7 2.7 2.7 2.7 2.6 2.6 2.6 2.6 2.6 2.6 Mean Household Total Personal Income (in 2005 dollars) 77,923 83,219 84,664 85,438 86,256 87,115 88,016 93,155 99,279 106,460 124,061 Total Number of Households (in thousands) 385.14 421.32 426.92 433.61 440.27 446.88 453.43 485.13 515.26 543.37 593.15 Income < $10,000 (thousands of households, 2000 dollars) 12.4% 11.3% 11.1% 10.9% 10.7% 10.6% 10.4% 9.3% 8.2% 7.1% 5.3% Income $10,000 to $19,999 13.2% 12.1% 11.8% 11.7% 11.5% 11.3% 11.1% 10.0% 8.8% 7.6% 5.7% Income $20,000 to $29,999 12.1% 11.1% 10.8% 10.7% 10.5% 10.4% 10.2% 9.2% 8.1% 7.0% 5.2% Income $30,000 to $44,999 17.5% 16.6% 16.3% 16.1% 15.9% 15.7% 15.5% 14.1% 12.4% 10.8% 8.0% Income $45,000 to $59,999 14.7% 16.0% 16.3% 16.5% 16.7% 16.9% 17.0% 17.3% 16.7% 15.3% 11.7% Income $60,000 to $74,999 11.1% 12.1% 12.4% 12.7% 12.9% 13.1% 13.3% 15.0% 17.1% 19.0% 19.1% Income $75,000 to $99,999 10.0% 10.9% 11.1% 11.3% 11.5% 11.7% 11.9% 13.3% 15.3% 17.7% 24.2% Income $100,000 or more 9.1% 9.8% 10.0% 10.1% 10.3% 10.4% 10.6% 11.8% 13.4% 15.4% 20.8% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 10 parishes in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-30 Demographic and Employment Baseline Projections for Economic Impact Area LA-4 2005 2010 2011 2012 2013 2014 2015 2020 2025 

Total Population (in thousands) 1,378.12 1,267.52 1,278.34 1,289.31 1,300.40 1,311.64 1,322.96 1,380.77 1,439

Age Under 19 years 28.1% 26.3% 26.2% 26.1% 26.1% 26.1% 26.1% 26.5% 26.Age 20 to 34 20.7% 20.7% 20.6% 20.5% 20.4% 20.1% 19.9% 18.1% 17.Age 35 to 49 22.0% 20.1% 19.7% 19.4% 19.2% 19.0% 18.8% 19.1% 19.Age 50 to 64 17.5% 20.5% 20.8% 20.9% 20.9% 21.0% 20.9% 19.8% 18.Age 65 and over 11.6% 12.5% 12.7% 13.1% 13.4% 13.8% 14.2% 16.5% 18.

Median Age of Population (in years) 36 36 37 37 37 37 37 38 White Population (in thousands) 54.4% 55.5% 55.3% 55.1% 54.9% 54.8% 54.6% 53.7% 52.Black Population (in thousands) 37.7% 35.0% 35.0% 35.0% 35.0% 35.1% 35.1% 35.2% 35.Native American Population (in thousands) 0.4% 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.Asian and Pacific Islander Population (in thousands) 2.4% 2.7% 2.7% 2.8% 2.8% 2.8% 2.9% 3.1% 3.Hispanic or Latino Population (in thousands) 5.1% 6.4% 6.5% 6.6% 6.7% 6.9% 7.0% 7.5% 8.Male Population (in thousands) 48.0% 48.2% 48.2% 48.2% 48.2% 48.2% 48.2% 48.2% 48.Total Employment (in thousands of jobs) 740.50 728.32 745.53 752.64 759.77 766.93 774.11 810.24 846

 Farm Employment 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0. Forestry, Fishing, Related Activities 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0. Mining 1.3% 1.5% 1.4% 1.4% 1.4% 1.3% 1.3% 1.2% 1. Utilities 0.4% 0.4% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0. Construction 6.2% 7.4% 7.4% 7.5% 7.6% 7.6% 7.7% 8.1% 8. Manufacturing 5.6% 5.6% 5.5% 5.5% 5.4% 5.3% 5.3% 4.9% 4. Wholesale Trade 3.6% 3.1% 3.1% 3.1% 3.1% 3.1% 3.1% 3.0% 3. Retail Trade 10.0% 10.2% 10.2% 10.3% 10.3% 10.3% 10.3% 10.5% 10. Transportation and Warehousing 4.1% 3.8% 3.7% 3.7% 3.7% 3.7% 3.7% 3.7% 3. Information Employment 1.6% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1. Finance and Insurance 3.9% 3.5% 3.5% 3.4% 3.4% 3.4% 3.4% 3.3% 3. Real Estate / Rental and Lease 4.0% 3.9% 3.9% 3.9% 3.9% 4.0% 4.0% 4.0% 4. Professional and Technical Services 5.7% 6.3% 6.3% 6.3% 6.2% 6.2% 6.2% 6.2% 6. Management 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 1. Administrative and Waste Services 6.4% 6.1% 6.2% 6.2% 6.3% 6.3% 6.3% 6.5% 6. Educational Services 3.1% 3.2% 3.2% 3.2% 3.2% 3.1% 3.1% 3.1% 3. Health Care and Social Assistance 8.8% 9.6% 9.7% 9.7% 9.8% 9.8% 9.9% 10.1% 10. Arts, Entertainment, and Recreation 2.5% 2.4% 2.4% 2.4% 2.4% 2.5% 2.5% 2.5% 2. Accommodation and Food Services 8.8% 9.1% 9.0% 8.9% 8.9% 8.8% 8.8% 8.4% 8. Other Services, Except Public Administration 6.5% 6.3% 6.4% 6.4% 6.4% 6.4% 6.5% 6.6% 6. Federal Civilian Government 2.1% 1.7% 1.7% 1.7% 1.7% 1.6% 1.6% 1.6% 1. Federal Military 1.4% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1. State and Local Government 11.9% 11.7% 11.7% 11.7% 11.8% 11.8% 11.8% 11.9% 11.
A-86 Central Planning Area Supplemental EIS Table 4-30. Demographic and Employment Baseline Projections for Economic Impact Area LA-4 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 33,666.07 33,632.01 34,709.10 35,337.46 35,974.63 36,620.67 37,275.64 40,686.08 44,326.90 48,203.33 56,678.49 Farm Employment 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% Forestry, Fishing, Related Activities 0.2% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% Mining 4.4% 4.9% 4.8% 4.8% 4.8% 4.7% 4.7% 4.6% 4.5% 4.4% 4.1% Utilities 1.2% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% Construction 6.5% 6.2% 6.7% 6.7% 6.7% 6.7% 6.7% 6.7% 6.7% 6.7% 6.6% Manufacturing 8.6% 9.0% 9.2% 9.1% 9.0% 8.9% 8.8% 8.2% 7.8% 7.3% 6.5% Wholesale Trade 5.3% 4.9% 5.0% 5.0% 5.0% 5.0% 5.0% 4.9% 4.9% 4.9% 4.8% Retail Trade 6.2% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8% 5.8% Transportation and Warehousing 5.1% 4.9% 4.8% 4.8% 4.8% 4.7% 4.7% 4.6% 4.5% 4.4% 4.2% Information Employment 1.7% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.4% 1.4% 1.4% Finance and Insurance 5.1% 4.2% 4.2% 4.3% 4.3% 4.3% 4.3% 4.3% 4.3% 4.3% 4.3% Real Estate / Rental and Lease 2.6% 1.1% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.3% 1.3% 1.4% Professional and Technical Services 8.0% 9.0% 8.9% 8.9% 8.9% 8.9% 8.9% 8.9% 8.9% 8.8% 8.8% Management 1.8% 1.7% 1.6% 1.6% 1.6% 1.7% 1.7% 1.7% 1.7% 1.8% 1.8% Administrative and Waste Services 4.0% 3.9% 4.0% 4.1% 4.1% 4.1% 4.2% 4.4% 4.6% 4.8% 5.1% Educational Services 2.2% 2.5% 2.5% 2.5% 2.5% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% Health Care and Social Assistance 8.7% 9.8% 9.7% 9.8% 9.9% 9.9% 10.0% 10.3% 10.6% 10.9% 11.6% Arts, Entertainment, and Recreation 2.1% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.1% 2.1% 2.2% 2.2% Accommodation and Food Services 4.4% 4.8% 4.7% 4.6% 4.6% 4.6% 4.5% 4.3% 4.2% 4.0% 3.7% Other Services, Except Public Administration 3.7% 3.6% 3.6% 3.6% 3.6% 3.6% 3.6% 3.7% 3.8% 3.9% 4.0% Federal Civilian Government 4.2% 4.0% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.8% 3.8% Federal Military 1.8% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% State and Local Government 12.1% 13.0% 12.9% 12.9% 13.0% 13.0% 13.1% 13.4% 13.7% 14.0% 14.5% Total Personal Income Per Capita (in 2005 dollars) 32,677 35,414 35,829 36,225 36,628 37,038 37,456 39,644 42,012 44,580 50,228 Woods & Poole Economics Wealth Index (U.S. = 100) 79.1 91.9 91.0 90.8 90.7 90.5 90.4 89.9 89.4 88.9 87.7 Persons Per Household (in number of people) 2.6 2.6 2.6 2.6 2.6 2.6 2.5 2.5 2.5 2.5 2.5 Mean Household Total Personal Income (in 2005 dollars) 77,994 87,207 87,276 87,772 88,333 88,946 89,614 93,616 98,555 104,400 118,602 Total Number of Households (in thousands) 530.24 491.36 496.01 501.93 507.80 513.61 519.34 546.73 572.34 595.76 635.83 Income < $10,000 (thousands of households, 2000 dollars) 12.7% 10.8% 10.6% 10.5% 10.3% 10.1% 9.9% 9.2% 8.2% 7.2% 5.5% Income $10,000 to $19,999 13.5% 11.9% 11.7% 11.5% 11.3% 11.1% 10.9% 10.1% 9.1% 8.0% 6.2% Income $20,000 to $29,999 12.9% 11.4% 11.2% 11.1% 10.9% 10.8% 10.6% 9.7% 8.7% 7.8% 6.1% Income $30,000 to $44,999 17.6% 15.5% 15.3% 15.2% 15.0% 14.8% 14.6% 13.6% 12.2% 10.8% 8.4% Income $45,000 to $59,999 13.7% 15.1% 15.3% 15.4% 15.5% 15.6% 15.7% 15.5% 14.9% 14.0% 11.2% Income $60,000 to $74,999 10.1% 11.7% 11.9% 12.0% 12.2% 12.4% 12.6% 13.8% 15.2% 16.2% 15.7% Income $75,000 to $99,999 9.3% 11.3% 11.5% 11.7% 11.9% 12.1% 12.3% 13.6% 15.3% 17.4% 22.5% Income $100,000 or more 10.2% 12.3% 12.5% 12.6% 12.8% 13.1% 13.3% 14.5% 16.4% 18.6% 24.3% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 9 parishes in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-31 Demographic and Employment Baseline Projections for Economic Impact Area MS-1 2005 2010 2011 2012 2013 2014 2015 2020 20

Total Population (in thousands) 476.88 470.61 474.64 478.72 482.85 487.02 491.23 512.71 53

Age Under 19 years 28.6% 28.0% 27.9% 27.8% 27.6% 27.6% 27.5% 27.5% 2Age 20 to 34 20.2% 20.3% 20.4% 20.5% 20.6% 20.5% 20.2% 19.6% 1Age 35 to 49 21.7% 19.8% 19.4% 19.1% 18.8% 18.5% 18.5% 18.3% 1Age 50 to 64 17.4% 19.0% 19.3% 19.3% 19.3% 19.4% 19.5% 18.9% 1Age 65 and over 12.1% 12.8% 13.0% 13.4% 13.7% 14.0% 14.3% 15.7% 1

Median Age of Population (in years) 36 36 36 36 37 37 37 37 White Population (in thousands) 75.5% 74.0% 73.8% 73.7% 73.5% 73.4% 73.2% 72.5% 7Black Population (in thousands) 19.2% 19.8% 19.8% 19.9% 19.9% 19.9% 20.0% 20.3% 2Native American Population (in thousands) 0.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% Asian and Pacific Islander Population (in thousands) 2.0% 2.1% 2.1% 2.2% 2.2% 2.2% 2.2% 2.3% Hispanic or Latino Population (in thousands) 2.8% 3.6% 3.7% 3.8% 3.8% 3.9% 4.0% 4.4% Male Population (in thousands) 49.6% 49.6% 49.6% 49.6% 49.6% 49.5% 49.5% 49.5% 4Total Employment (in thousands of jobs) 238.83 243.91 249.36 251.56 253.76 255.98 258.22 269.62 28

 Farm Employment 1.4% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2% 1.2%  Forestry, Fishing, Related Activities 0.8% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%  Mining 0.1% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%  Utilities 0.9% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%  Construction 7.5% 7.2% 7.2% 7.2% 7.2% 7.3% 7.3% 7.4%  Manufacturing 9.5% 10.2% 10.2% 10.1% 10.0% 9.9% 9.8% 9.4%  Wholesale Trade 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.3%  Retail Trade 10.9% 10.2% 10.1% 10.1% 10.1% 10.1% 10.0% 9.9%  Transportation and Warehousing 2.4% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5%  Information Employment 1.4% 0.8% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9%  Finance and Insurance 2.5% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6%  Real Estate / Rental and Lease 3.1% 3.5% 3.5% 3.5% 3.6% 3.6% 3.6% 3.8%  Professional and Technical Services 3.8% 4.1% 4.2% 4.2% 4.2% 4.3% 4.3% 4.5%  Management 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3%  Administrative and Waste Services 5.4% 6.0% 6.1% 6.1% 6.2% 6.3% 6.4% 6.8%  Educational Services 0.5% 0.8% 0.8% 0.9% 0.9% 0.9% 0.9% 1.0%  Health Care and Social Assistance 6.2% 6.8% 6.9% 6.9% 6.9% 7.0% 7.0% 7.1%  Arts, Entertainment, and Recreation 2.2% 1.8% 1.8% 1.8% 1.8% 1.8% 1.8% 1.8%  Accommodation and Food Services 12.1% 10.3% 10.3% 10.3% 10.2% 10.2% 10.2% 10.0%  Other Services, Except Public Administration 5.5% 5.5% 5.6% 5.6% 5.6% 5.7% 5.7% 5.9%  Federal Civilian Government 3.9% 4.0% 4.0% 3.9% 3.9% 3.9% 3.8% 3.7%  Federal Military 5.7% 5.3% 5.3% 5.2% 5.2% 5.1% 5.1% 4.8%  State and Local Government 12.3% 13.4% 13.4% 13.4% 13.4% 13.4% 13.3% 13.3% 1
A-88 Central Planning Area Supplemental EIS Table 4-31. Demographic and Employment Baseline Projections for Economic Impact Area MS-1 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 9,318.99 9,816.16 10,180.77 10,354.51 10,530.94 10,710.09 10,892.03 11,844.59 12,872.19 13,979.85 16,456.60 Farm Employment 0.3% 0.0% 0.2% 0.2% 0.2% 0.2% 0.1% 0.1% 0.1% 0.1% 0.1% Forestry, Fishing, Related Activities 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% Mining 0.2% 0.4% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% Utilities 2.1% 1.6% 1.6% 1.6% 1.6% 1.6% 1.7% 1.7% 1.8% 1.9% 2.0% Construction 6.0% 5.4% 6.0% 6.0% 5.9% 5.9% 5.8% 5.7% 5.5% 5.3% 5.0% Manufacturing 15.4% 17.3% 17.7% 17.5% 17.4% 17.3% 17.1% 16.5% 15.8% 15.1% 13.9% Wholesale Trade 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.6% 1.5% 1.5% 1.4% 1.3% Retail Trade 7.0% 6.1% 6.1% 6.0% 6.0% 6.0% 5.9% 5.8% 5.7% 5.5% 5.3% Transportation and Warehousing 2.3% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% Information Employment 1.4% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.9% 0.9% 1.0% 1.1% Finance and Insurance 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.3% 2.4% 2.5% 2.6% Real Estate / Rental and Lease 1.0% 0.7% 0.8% 0.8% 0.8% 0.8% 0.8% 0.9% 0.9% 1.0% 1.1% Professional and Technical Services 4.6% 5.1% 5.1% 5.2% 5.3% 5.3% 5.4% 5.7% 6.0% 6.3% 6.9% Management 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% Administrative and Waste Services 3.1% 3.4% 3.4% 3.5% 3.5% 3.6% 3.6% 3.9% 4.2% 4.5% 5.2% Educational Services 0.3% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.6% 0.6% 0.7% 0.9% Health Care and Social Assistance 6.7% 6.9% 6.9% 6.9% 6.9% 7.0% 7.0% 7.1% 7.3% 7.4% 7.6% Arts, Entertainment, and Recreation 1.5% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1.0% 1.0% 1.0% 0.9% Accommodation and Food Services 8.0% 5.9% 5.8% 5.8% 5.7% 5.7% 5.7% 5.6% 5.4% 5.3% 5.1% Other Services, Except Public Administration 3.4% 3.5% 3.4% 3.4% 3.5% 3.5% 3.5% 3.6% 3.8% 3.9% 4.1% Federal Civilian Government 8.4% 8.8% 8.6% 8.6% 8.6% 8.6% 8.6% 8.6% 8.5% 8.5% 8.4% Federal Military 10.2% 10.2% 10.1% 10.0% 10.0% 10.0% 9.9% 9.8% 9.6% 9.5% 9.2% State and Local Government 13.2% 15.3% 15.0% 15.0% 15.1% 15.1% 15.2% 15.4% 15.5% 15.7% 16.1% Total Personal Income Per Capita (in 2005 dollars) 27,815 29,510 29,900 30,216 30,539 30,868 31,204 32,989 34,961 37,140 42,045 Woods & Poole Economics Wealth Index (U.S. = 100) 68.6 73.6 73.5 73.4 73.4 73.3 73.2 72.8 72.4 72.0 71.2 Persons Per Household (in number of people) 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.5 2.5 2.6 Mean Household Total Personal Income (in 2005 dollars) 65,960 67,129 67,940 68,417 68,918 69,445 70,003 73,247 77,212 81,941 93,603 Total Number of Households (in thousands) 180.00 179.76 181.51 183.72 185.92 188.09 190.24 200.49 210.03 218.68 233.44 Income < $10,000 (thousands of households, 2000 dollars) 10.8% 9.8% 9.7% 9.5% 9.4% 9.2% 9.1% 8.4% 7.4% 6.4% 4.6% Income $10,000 to $19,999 122.2% 122.3% 122.3% 122.3% 122.3% 122.3% 122.3% 122.5% 122.6% 122.8% 122.9% Income $20,000 to $29,999 103.6% 102.5% 102.4% 102.4% 102.4% 102.4% 102.4% 101.9% 101.3% 101.1% 100.9% Income $30,000 to $44,999 148.8% 154.6% 155.9% 156.8% 157.6% 158.3% 158.9% 161.1% 162.6% 163.1% 163.2% Income $45,000 to $59,999 79.1% 92.0% 94.5% 96.5% 98.6% 100.9% 103.3% 115.9% 132.2% 147.5% 162.6% Income $60,000 to $74,999 65.2% 66.6% 66.8% 66.9% 67.1% 67.3% 67.4% 71.0% 80.1% 94.1% 134.9% Income $75,000 to $99,999 83.1% 82.9% 82.9% 82.9% 82.9% 82.8% 82.8% 82.7% 82.7% 84.6% 103.1% Income $100,000 or more 81.1% 81.1% 81.2% 81.2% 81.2% 81.2% 81.2% 81.2% 81.2% 81.0% 81.1% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 7 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-32 Demographic and Employment Baseline Projections for Economic Impact Area AL-1 2005 2010 2011 2012 2013 2014 2015 2020 202

Total Population (in thousands) 691.71 725.48 731.11 736.83 742.62 748.49 754.41 784.68 81

Age Under 19 years 28.1% 27.4% 27.2% 27.1% 26.9% 26.8% 26.7% 26.5% 2Age 20 to 34 19.2% 19.5% 19.6% 19.6% 19.5% 19.3% 19.1% 18.3% 17Age 35 to 49 21.1% 19.3% 18.9% 18.6% 18.5% 18.4% 18.4% 18.5% 1Age 50 to 64 18.0% 19.5% 19.7% 19.8% 19.8% 19.8% 19.8% 19.0% 17Age 65 and over 13.6% 14.4% 14.6% 14.9% 15.3% 15.6% 16.0% 17.7% 19

Median Age of Population (in years) 38 39 39 40 40 40 40 41 White Population (in thousands) 66.6% 66.0% 65.9% 65.9% 65.8% 65.7% 65.7% 65.3% 64Black Population (in thousands) 29.6% 29.4% 29.4% 29.4% 29.3% 29.3% 29.3% 29.3% 29Native American Population (in thousands) 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% Asian and Pacific Islander Population (in thousands) 1.2% 1.5% 1.5% 1.5% 1.6% 1.6% 1.6% 1.7% Hispanic or Latino Population (in thousands) 1.6% 2.2% 2.3% 2.3% 2.4% 2.4% 2.5% 2.7% 3Male Population (in thousands) 48.2% 48.3% 48.3% 48.3% 48.3% 48.3% 48.4% 48.4% 4Total Employment (in thousands of jobs) 363.84 353.63 362.59 366.69 370.81 374.97 379.15 400.55 42

Farm Employment 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.3% Forestry, Fishing, Related Activities 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 0.9% 0.9% 0Mining 0.3% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0Utilities 0.4% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0Construction 8.5% 7.5% 7.6% 7.6% 7.6% 7.6% 7.6% 7.7% 7Manufacturing 8.7% 7.6% 7.6% 7.5% 7.4% 7.3% 7.2% 6.9% Wholesale Trade 3.5% 3.1% 3.0% 3.0% 3.0% 3.0% 2.9% 2.8% 2Retail Trade 12.4% 11.9% 11.8% 11.8% 11.7% 11.6% 11.5% 11.1% 10Transportation and Warehousing 3.7% 3.9% 3.9% 3.8% 3.8% 3.8% 3.8% 3.6% Information Employment 1.3% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% Finance and Insurance 3.4% 3.7% 3.7% 3.7% 3.7% 3.6% 3.6% 3.5% Real Estate / Rental and Lease 4.4% 4.6% 4.7% 4.7% 4.7% 4.7% 4.8% 4.9% 5Professional and Technical Services 4.4% 4.6% 4.7% 4.7% 4.7% 4.8% 4.8% 5.0% 5Management 0.2% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0Administrative and Waste Services 6.4% 6.4% 6.5% 6.5% 6.6% 6.7% 6.7% 7.0% 7Educational Services 1.4% 1.6% 1.7% 1.7% 1.7% 1.7% 1.7% 1.8% Health Care and Social Assistance 8.5% 9.4% 9.4% 9.5% 9.6% 9.6% 9.7% 10.1% 10Arts, Entertainment, and Recreation 1.3% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% Accommodation and Food Services 6.8% 7.6% 7.6% 7.7% 7.7% 7.7% 7.8% 8.0% Other Services, Except Public Administration 7.7% 7.9% 7.9% 8.0% 8.0% 8.1% 8.1% 8.4% Federal Civilian Government 0.9% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0Federal Military 1.3% 1.1% 1.1% 1.1% 1.0% 1.0% 1.0% 1.0% 0State and Local Government 12.0% 12.0% 12.0% 11.9% 11.9% 11.9% 11.8% 11.6% 1
A-90 Central Planning Area Supplemental EIS Table 4-32. Demographic and Employment Baseline Projections for Economic Impact Area AL-1 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 12,930.79 13,040.20 13,381.74 13,639.05 13,900.74 14,166.88 14,437.55 15,860.94 17,407.25 19,085.19 22,872.66 Farm Employment 0.8% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.5% 0.4% Forestry, Fishing, Related Activities 1.0% 1.0% 1.0% 0.9% 0.9% 0.9% 0.9% 0.9% 0.8% 0.8% 0.7% Mining 0.4% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% 0.7% 0.8% Utilities 1.0% 1.4% 1.1% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% 1.2% Construction 8.9% 7.9% 8.6% 8.5% 8.4% 8.4% 8.3% 8.0% 7.7% 7.4% 6.8% Manufacturing 13.6% 12.2% 12.6% 12.5% 12.4% 12.3% 12.2% 11.7% 11.2% 10.7% 9.8% Wholesale Trade 5.1% 4.6% 4.7% 4.7% 4.6% 4.6% 4.6% 4.5% 4.4% 4.3% 4.0% Retail Trade 8.9% 8.4% 8.5% 8.4% 8.3% 8.3% 8.2% 7.9% 7.5% 7.2% 6.5% Transportation and Warehousing 4.8% 5.7% 5.6% 5.6% 5.6% 5.5% 5.5% 5.3% 5.1% 4.9% 4.6% Information Employment 1.6% 1.2% 1.2% 1.2% 1.2% 1.2% 1.2% 1.3% 1.3% 1.3% 1.3% Finance and Insurance 4.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 3.8% Real Estate / Rental and Lease 2.3% 1.7% 1.8% 1.8% 1.8% 1.8% 1.8% 2.0% 2.1% 2.2% 2.5% Professional and Technical Services 5.5% 6.1% 6.1% 6.2% 6.2% 6.3% 6.4% 6.7% 7.0% 7.3% 7.9% Management 0.3% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% 0.7% 0.8% Administrative and Waste Services 3.7% 3.6% 3.7% 3.7% 3.7% 3.8% 3.8% 4.1% 4.3% 4.6% 5.1% Educational Services 0.9% 1.0% 1.0% 1.0% 1.0% 1.0% 1.0% 1.1% 1.1% 1.2% 1.3% Health Care and Social Assistance 9.8% 11.0% 11.1% 11.2% 11.3% 11.4% 11.5% 11.9% 12.4% 12.9% 13.8% Arts, Entertainment, and Recreation 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% Accommodation and Food Services 3.2% 3.5% 3.5% 3.5% 3.5% 3.6% 3.6% 3.7% 3.7% 3.8% 4.0% Other Services, Except Public Administration 4.8% 4.9% 4.9% 4.9% 4.9% 5.0% 5.0% 5.2% 5.4% 5.5% 5.8% Federal Civilian Government 2.2% 2.5% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% Federal Military 1.8% 1.8% 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2% 1.2% State and Local Government 13.8% 15.2% 15.1% 15.1% 15.1% 15.1% 15.2% 15.2% 15.2% 15.2% 15.1% Total Personal Income Per Capita (in 2005 dollars) 26,961 28,132 28,252 28,605 28,964 29,329 29,701 31,665 33,826 36,202 41,511 Woods & Poole Economics Wealth Index (U.S. = 100) 69.0 71.9 71.2 71.2 71.3 71.3 71.4 71.6 71.8 72.0 72.2 Persons Per Household (in number of people) 2.6 2.6 2.6 2.6 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Mean Household Total Personal Income (in 2005 dollars) 61,397 63,756 63,690 64,304 64,944 65,612 66,308 70,242 74,885 80,263 93,095 Total Number of Households (in thousands) 267.98 283.15 285.62 288.82 292.00 295.14 298.23 312.96 326.65 339.07 360.09 Income < $10,000 (thousands of households, 2000 dollars) 13.3% 11.9% 11.7% 11.6% 11.4% 11.2% 11.0% 10.0% 8.6% 7.4% 5.4% Income $10,000 to $19,999 14.5% 13.2% 13.0% 12.8% 12.7% 12.5% 12.3% 11.2% 9.7% 8.3% 6.2% Income $20,000 to $29,999 13.0% 11.9% 11.8% 11.6% 11.5% 11.3% 11.2% 10.2% 8.9% 7.7% 5.7% Income $30,000 to $44,999 18.8% 18.5% 18.4% 18.2% 18.1% 17.9% 17.8% 16.5% 14.6% 12.6% 9.4% Income $45,000 to $59,999 14.8% 16.4% 16.6% 16.8% 17.0% 17.2% 17.4% 18.7% 19.5% 18.8% 14.8% Income $60,000 to $74,999 9.6% 10.6% 10.7% 10.9% 11.0% 11.2% 11.3% 12.5% 14.4% 16.8% 19.9% Income $75,000 to $99,999 8.4% 9.3% 9.4% 9.5% 9.7% 9.8% 9.9% 11.0% 12.7% 14.9% 20.1% Income $100,000 or more 7.5% 8.4% 8.5% 8.6% 8.7% 8.9% 9.0% 10.0% 11.6% 13.5% 18.4% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 8 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-33 Demographic and Employment Baseline Projections for Economic Impact Area FL-1 2005 2010 2011 2012 2013 2014 2015 2020 20

Total Population (in thousands) 865.12 896.10 911.70 927.40 943.19 959.08 975.02 1,055.59 1,13

Age Under 19 years 26.1% 25.0% 24.8% 24.7% 24.6% 24.5% 24.5% 24.9% 2Age 20 to 34 20.5% 21.5% 21.7% 21.8% 21.9% 21.9% 21.5% 19.9% 1Age 35 to 49 22.0% 19.5% 19.0% 18.5% 18.1% 17.7% 17.7% 18.2% 1Age 50 to 64 17.9% 19.4% 19.6% 19.7% 19.7% 19.8% 19.8% 18.8% 1Age 65 and over 13.4% 14.6% 14.8% 15.3% 15.7% 16.1% 16.4% 18.2% 2

Median Age of Population (in years) 39 39 40 40 40 40 40 40 White Population (in thousands) 79.2% 77.6% 77.4% 77.2% 77.1% 76.9% 76.7% 75.8% 7Black Population (in thousands) 13.8% 14.3% 14.3% 14.3% 14.4% 14.4% 14.4% 14.6% 1Native American Population (in thousands) 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% Asian and Pacific Islander Population (in thousands) 2.4% 2.6% 2.6% 2.6% 2.7% 2.7% 2.7% 2.8% Hispanic or Latino Population (in thousands) 3.7% 4.6% 4.7% 4.8% 5.0% 5.1% 5.2% 5.9% Male Population (in thousands) 49.8% 50.0% 50.1% 50.1% 50.2% 50.2% 50.2% 50.4% 5Total Employment (in thousands of jobs) 487.45 489.82 504.24 512.13 520.13 528.26 536.52 579.78 62

Farm Employment 0.5% 0.6% 0.6% 0.6% 0.6% 0.5% 0.5% 0.5% Forestry, Fishing, Related Activities 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Mining 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% Utilities 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% Construction 9.0% 5.6% 5.6% 5.7% 5.7% 5.7% 5.7% 5.7% Manufacturing 3.4% 3.0% 3.0% 3.0% 3.0% 3.0% 2.9% 2.8% Wholesale Trade 2.6% 2.1% 2.1% 2.1% 2.0% 2.0% 2.0% 1.9% Retail Trade 12.0% 11.8% 11.8% 11.7% 11.7% 11.7% 11.7% 11.5% 1Transportation and Warehousing 1.8% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% Information Employment 1.9% 1.8% 1.8% 1.8% 1.8% 1.8% 1.8% 1.7% Finance and Insurance 3.6% 3.9% 3.9% 3.9% 3.9% 3.9% 3.9% 4.0% Real Estate / Rental and Lease 5.5% 5.6% 5.6% 5.6% 5.7% 5.7% 5.7% 5.7% Professional and Technical Services 5.2% 5.7% 5.7% 5.8% 5.9% 5.9% 6.0% 6.4% Management 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% Administrative and Waste Services 7.0% 6.4% 6.4% 6.5% 6.5% 6.6% 6.7% 6.9% Educational Services 1.0% 1.1% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% Health Care and Social Assistance 8.9% 10.8% 10.9% 11.0% 11.1% 11.2% 11.3% 11.8% 1Arts, Entertainment, and Recreation 1.7% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% Accommodation and Food Services 8.8% 9.2% 9.2% 9.2% 9.2% 9.2% 9.2% 9.1% Other Services, Except Public Administration 6.2% 6.3% 6.3% 6.3% 6.3% 6.3% 6.4% 6.5% Federal Civilian Government 3.5% 3.7% 3.7% 3.7% 3.6% 3.6% 3.5% 3.3% Federal Military 6.9% 7.3% 7.2% 7.1% 7.0% 6.9% 6.8% 6.2% State and Local Government 9.1% 9.7% 9.7% 9.6% 9.6% 9.6% 9.5% 9.3% 
A-92 Central Planning Area Supplemental EIS Table 4-33. Demographic and Employment Baseline Projections for Economic Impact Area FL-1 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 19,144.97 18,366.21 19,090.88 19,571.64 20,064.69 20,570.39 21,089.01 23,888.71 27,067.17 30,676.87 39,438.19 Farm Employment 0.1% 0.2% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% Forestry, Fishing, Related Activities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% Mining 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% Utilities 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Construction 8.1% 4.4% 4.8% 4.8% 4.7% 4.7% 4.6% 4.4% 4.2% 4.0% 3.7% Manufacturing 4.8% 4.7% 4.8% 4.8% 4.8% 4.8% 4.7% 4.6% 4.5% 4.4% 4.2% Wholesale Trade 3.0% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2.3% 2.2% 2.2% 2.0% Retail Trade 7.9% 7.3% 7.3% 7.3% 7.2% 7.2% 7.2% 7.0% 6.9% 6.7% 6.4% Transportation and Warehousing 1.8% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.1% 2.1% 2.1% Information Employment 2.4% 2.0% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% 2.1% Finance and Insurance 3.9% 3.6% 3.6% 3.6% 3.7% 3.7% 3.8% 4.0% 4.2% 4.4% 4.9% Real Estate / Rental and Lease 3.1% 2.0% 2.0% 2.1% 2.1% 2.1% 2.1% 2.2% 2.3% 2.4% 2.5% Professional and Technical Services 6.6% 6.8% 6.8% 6.9% 7.0% 7.1% 7.2% 7.7% 8.2% 8.8% 9.9% Management 0.8% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% Administrative and Waste Services 4.5% 3.7% 3.8% 3.8% 3.9% 3.9% 3.9% 4.2% 4.4% 4.6% 5.1% Educational Services 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.8% 0.8% 0.9% 0.9% Health Care and Social Assistance 10.0% 12.0% 12.0% 12.2% 12.3% 12.5% 12.6% 13.3% 14.0% 14.7% 16.2% Arts, Entertainment, and Recreation 0.6% 0.6% 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Accommodation and Food Services 4.6% 4.4% 4.4% 4.4% 4.4% 4.4% 4.3% 4.3% 4.3% 4.3% 4.2% Other Services, Except Public Administration 4.4% 4.3% 4.2% 4.2% 4.3% 4.3% 4.3% 4.4% 4.4% 4.5% 4.6% Federal Civilian Government 6.8% 7.8% 7.6% 7.6% 7.5% 7.5% 7.4% 7.1% 6.8% 6.6% 6.0% Federal Military 14.5% 18.2% 18.0% 17.8% 17.6% 17.4% 17.2% 16.3% 15.4% 14.5% 12.8% State and Local Government 10.5% 11.2% 11.1% 11.1% 11.0% 11.0% 11.0% 11.0% 10.9% 10.7% 10.4% Total Personal Income Per Capita (in 2005 dollars) 30,955 31,238 31,611 31,972 32,345 32,728 33,123 35,252 37,665 40,392 46,766 Woods & Poole Economics Wealth Index (U.S. = 100) 86.0 86.1 85.9 86.0 86.0 86.1 86.2 86.6 87.2 87.8 89.2 Persons Per Household (in number of people) 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.4 2.4 2.5 Mean Household Total Personal Income (in 2005 dollars) 70,630 68,775 69,464 70,092 70,758 71,474 72,225 76,569 81,867 88,167 103,926 Total Number of Households (in thousands) 339.50 355.60 362.19 369.74 377.31 384.77 392.23 428.80 464.20 497.98 559.96 Income < $10,000 (thousands of households, 2000 dollars) 8.7% 8.1% 7.9% 7.8% 7.7% 7.5% 7.4% 6.6% 5.7% 4.9% 3.5% Income $10,000 to $19,999 12.4% 11.6% 11.3% 11.1% 11.0% 10.8% 10.6% 9.4% 8.1% 7.0% 5.1% Income $20,000 to $29,999 13.8% 12.9% 12.6% 12.4% 12.2% 12.0% 11.8% 10.4% 9.1% 7.8% 5.7% Income $30,000 to $44,999 19.7% 18.9% 18.6% 18.3% 18.1% 17.8% 17.5% 15.6% 13.6% 11.7% 8.5% Income $45,000 to $59,999 16.5% 17.4% 17.8% 18.0% 18.2% 18.3% 18.5% 19.1% 18.7% 17.1% 12.7% Income $60,000 to $74,999 11.2% 12.0% 12.3% 12.5% 12.7% 13.0% 13.2% 15.0% 17.3% 19.3% 20.1% Income $75,000 to $99,999 9.2% 9.8% 10.1% 10.2% 10.4% 10.6% 10.8% 12.3% 14.2% 16.5% 22.7% Income $100,000 or more 8.6% 9.2% 9.5% 9.6% 9.8% 10.0% 10.2% 11.6% 13.4% 15.7% 21.7% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 7 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-34 Demographic and Employment Baseline Projections for Economic Impact Area FL-2 2005 2010 2011 2012 2013 2014 2015 2020 202

Total Population (in thousands) 613.83 657.40 666.76 676.21 685.71 695.29 704.90 753.56 80

Age Under 19 years 25.8% 24.6% 24.3% 24.2% 24.0% 23.9% 24.0% 24.2% 24Age 20 to 34 24.5% 25.3% 25.6% 25.8% 25.9% 25.9% 25.5% 22.8% 20Age 35 to 49 20.7% 18.9% 18.5% 18.1% 17.8% 17.5% 17.4% 18.7% 20Age 50 to 64 17.1% 18.2% 18.4% 18.3% 18.3% 18.3% 18.3% 17.6% 16Age 65 and over 11.9% 12.9% 13.2% 13.6% 14.0% 14.4% 14.8% 16.7% 18

Median Age of Population (in years) 37 38 38 38 39 39 39 40 White Population (in thousands) 66.6% 65.2% 65.0% 64.8% 64.6% 64.4% 64.2% 63.2% 62Black Population (in thousands) 27.1% 27.5% 27.6% 27.6% 27.7% 27.7% 27.8% 28.2% 28Native American Population (in thousands) 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0Asian and Pacific Islander Population (in thousands) 1.3% 1.5% 1.5% 1.5% 1.6% 1.6% 1.6% 1.7% 1Hispanic or Latino Population (in thousands) 4.5% 5.3% 5.4% 5.5% 5.6% 5.8% 5.9% 6.4% 6Male Population (in thousands) 50.3% 50.8% 50.8% 50.9% 50.9% 51.0% 51.0% 51.2% 51Total Employment (in thousands of jobs) 322.62 330.09 338.56 342.74 346.98 351.28 355.62 378.16 40

Farm Employment 2.6% 3.0% 3.0% 3.0% 2.9% 2.9% 2.9% 2.7% 2Forestry, Fishing, Related Activities 1.3% 1.4% 1.4% 1.4% 1.4% 1.4% 1.4% 1.3% 1Mining 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0Utilities 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0Construction 6.5% 4.7% 4.7% 4.8% 4.8% 4.8% 4.8% 4.9% 5Manufacturing 4.6% 3.6% 3.6% 3.6% 3.5% 3.5% 3.5% 3.3% 3Wholesale Trade 2.1% 1.9% 1.9% 1.9% 1.9% 1.8% 1.8% 1.7% 1Retail Trade 11.0% 10.3% 10.2% 10.2% 10.2% 10.2% 10.2% 10.0% 9Transportation and Warehousing 1.6% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1Information Employment 1.8% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.6% 1Finance and Insurance 3.2% 3.5% 3.5% 3.5% 3.5% 3.5% 3.5% 3.5% 3Real Estate / Rental and Lease 3.1% 3.2% 3.2% 3.2% 3.2% 3.2% 3.2% 3.3% 3Professional and Technical Services 5.8% 6.2% 6.3% 6.4% 6.5% 6.6% 6.7% 7.1% 7Management 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0Administrative and Waste Services 4.8% 4.8% 4.8% 4.9% 4.9% 4.9% 5.0% 5.1% 5Educational Services 1.1% 1.6% 1.6% 1.6% 1.7% 1.7% 1.7% 1.9% 2Health Care and Social Assistance 8.6% 10.3% 10.4% 10.5% 10.7% 10.8% 10.9% 11.4% 12Arts, Entertainment, and Recreation 1.2% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.6% 1Accommodation and Food Services 6.7% 6.8% 6.8% 6.9% 6.9% 6.9% 6.9% 7.0% 7Other Services, Except Public Administration 6.2% 6.1% 6.1% 6.1% 6.2% 6.2% 6.2% 6.3% 6Federal Civilian Government 1.2% 1.3% 1.3% 1.3% 1.2% 1.2% 1.2% 1.1% 1Federal Military 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0State and Local Government 25.3% 25.0% 24.8% 24.6% 24.4% 24.2% 24.0% 23.0% 22
A-94 Central Planning Area Supplemental EIS Table 4-34. Demographic and Employment Baseline Projections for Economic Impact Area FL-2 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 11,927.62 11,506.58 11,863.49 12,113.72 12,369.19 12,629.96 12,896.15 14,312.49 15,882.28 17,622.00 21,685.31 Farm Employment 1.3% 1.2% 1.3% 1.2% 1.2% 1.2% 1.2% 1.1% 1.0% 0.9% 0.7% Forestry, Fishing, Related Activities 1.3% 1.3% 1.3% 1.3% 1.3% 1.3% 1.2% 1.2% 1.1% 1.1% 1.0% Mining 0.1% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% Utilities 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.9% 0.9% 0.9% 1.0% Construction 6.4% 4.2% 4.5% 4.4% 4.4% 4.4% 4.4% 4.2% 4.1% 3.9% 3.6% Manufacturing 5.9% 5.3% 5.5% 5.4% 5.4% 5.4% 5.4% 5.2% 5.1% 4.9% 4.6% Wholesale Trade 2.7% 2.3% 2.4% 2.4% 2.4% 2.4% 2.3% 2.3% 2.2% 2.1% 1.9% Retail Trade 7.2% 7.0% 7.0% 7.0% 6.9% 6.9% 6.9% 6.7% 6.6% 6.4% 6.1% Transportation and Warehousing 1.5% 1.6% 1.7% 1.7% 1.7% 1.7% 1.6% 1.6% 1.6% 1.5% 1.5% Information Employment 2.4% 2.3% 2.3% 2.3% 2.3% 2.3% 2.3% 2.2% 2.1% 2.0% 1.9% Finance and Insurance 4.2% 4.5% 4.6% 4.6% 4.7% 4.7% 4.8% 5.0% 5.2% 5.4% 5.9% Real Estate / Rental and Lease 1.1% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 0.9% 1.0% 1.0% Professional and Technical Services 7.9% 8.1% 8.1% 8.2% 8.3% 8.4% 8.6% 9.2% 9.8% 10.4% 11.7% Management 0.4% 0.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% Administrative and Waste Services 2.7% 2.7% 2.7% 2.7% 2.8% 2.8% 2.8% 2.9% 3.0% 3.1% 3.4% Educational Services 0.5% 0.8% 0.8% 0.8% 0.8% 0.8% 0.9% 0.9% 1.0% 1.1% 1.4% Health Care and Social Assistance 9.6% 11.6% 11.7% 11.8% 12.0% 12.1% 12.2% 12.9% 13.5% 14.1% 15.4% Arts, Entertainment, and Recreation 0.4% 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Accommodation and Food Services 2.7% 2.8% 2.7% 2.7% 2.7% 2.8% 2.8% 2.8% 2.8% 2.8% 2.9% Other Services, Except Public Administration 5.2% 5.4% 5.3% 5.3% 5.3% 5.3% 5.4% 5.4% 5.5% 5.5% 5.6% Federal Civilian Government 2.7% 3.2% 3.2% 3.2% 3.1% 3.1% 3.1% 3.0% 2.9% 2.8% 2.6% Federal Military 0.5% 0.6% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% State and Local Government 32.3% 32.2% 31.6% 31.4% 31.2% 31.0% 30.8% 29.9% 28.9% 27.9% 26.0% Total Personal Income Per Capita (in 2005 dollars) 27,200 26,656 26,811 27,063 27,321 27,585 27,856 29,328 31,005 32,905 37,298 Woods & Poole Economics Wealth Index (U.S. = 100) 67.0 66.8 66.7 66.6 66.5 66.4 66.3 65.9 65.6 65.4 64.9 Persons Per Household (in number of people) 2.6 2.6 2.6 2.6 2.6 2.5 2.5 2.5 2.5 2.5 2.5 Mean Household Total Personal Income (in 2005 dollars) 57,688 56,795 57,352 57,724 58,116 58,529 58,970 61,586 64,884 68,883 78,850 Total Number of Households (in thousands) 236.50 255.39 259.32 263.92 268.49 273.05 277.56 299.51 320.40 339.91 374.75 Income < $10,000 (thousands of households, 2000 dollars) 13.6% 12.8% 12.6% 12.4% 12.2% 12.1% 11.9% 11.0% 10.1% 8.9% 6.6% Income $10,000 to $19,999 14.3% 13.6% 13.4% 13.2% 13.0% 12.8% 12.6% 11.7% 10.7% 9.4% 7.0% Income $20,000 to $29,999 14.0% 13.3% 13.1% 12.9% 12.7% 12.5% 12.4% 11.5% 10.5% 9.3% 6.9% Income $30,000 to $44,999 18.7% 18.8% 18.8% 18.8% 18.7% 18.6% 18.5% 17.9% 16.8% 14.9% 11.1% Income $45,000 to $59,999 14.2% 14.9% 15.2% 15.4% 15.6% 15.8% 16.1% 17.2% 18.3% 19.3% 17.8% Income $60,000 to $74,999 9.4% 9.9% 10.0% 10.2% 10.3% 10.5% 10.6% 11.5% 12.5% 14.3% 18.6% Income $75,000 to $99,999 8.2% 8.6% 8.7% 8.8% 8.9% 9.1% 9.2% 9.9% 10.8% 12.4% 16.6% Income $100,000 or more 7.8% 8.1% 8.3% 8.4% 8.5% 8.6% 8.7% 9.4% 10.2% 11.6% 15.4% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 15 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-35 Demographic and Employment Baseline Projections for Economic Impact Area FL-3 2005 2010 2011 2012 2013 2014 2015 2020 202

Total Population (in thousands) 3,416.04 3,624.88 3,675.05 3,725.64 3,776.58 3,827.91 3,879.47 4,140.64 4,40

Age Under 19 years 24.0% 23.4% 23.3% 23.2% 23.2% 23.1% 23.1% 23.1% 23Age 20 to 34 18.9% 19.4% 19.7% 19.8% 19.9% 19.9% 19.8% 19.2% 18Age 35 to 49 21.2% 19.6% 19.2% 18.8% 18.5% 18.2% 18.1% 17.9% 18Age 50 to 64 18.1% 19.5% 19.8% 19.8% 19.8% 19.9% 19.9% 19.1% 17Age 65 and over 17.8% 18.0% 18.1% 18.4% 18.6% 18.9% 19.1% 20.6% 22

Median Age of Population (in years) 41 41 42 42 42 42 42 43 White Population (in thousands) 74.5% 71.2% 70.7% 70.1% 69.6% 69.1% 68.5% 65.9% 63Black Population (in thousands) 11.3% 11.8% 11.9% 12.0% 12.0% 12.1% 12.1% 12.3% 12Native American Population (in thousands) 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0Asian and Pacific Islander Population (in thousands) 2.5% 2.9% 3.0% 3.0% 3.1% 3.2% 3.3% 3.6% 4Hispanic or Latino Population (in thousands) 11.4% 13.7% 14.1% 14.5% 14.9% 15.3% 15.8% 17.8% 19Male Population (in thousands) 48.7% 48.9% 49.0% 49.0% 49.1% 49.2% 49.2% 49.4% 49Total Employment (in thousands of jobs) 1,944.16 1,868.77 1,922.79 1,951.29 1,980.12 2,009.31 2,038.85 2,192.00 2,35

 Farm Employment 1.0% 1.2% 1.1% 1.1% 1.1% 1.1% 1.1% 1.0% 1 Forestry, Fishing, Related Activities 0.5% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.5% 0 Mining 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0 Utilities 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0 Construction 7.3% 4.8% 4.8% 4.9% 4.9% 4.9% 4.9% 5.0% 5 Manufacturing 5.0% 4.4% 4.3% 4.3% 4.2% 4.1% 4.0% 3.7% 3 Wholesale Trade 3.4% 3.4% 3.3% 3.3% 3.3% 3.3% 3.3% 3.2% 3 Retail Trade 11.4% 11.1% 11.1% 11.0% 11.0% 11.0% 11.0% 10.8% 10 Transportation and Warehousing 2.3% 2.5% 2.4% 2.4% 2.4% 2.4% 2.4% 2.4% 2 Information Employment 2.2% 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% 1.9% 1 Finance and Insurance 5.8% 5.9% 5.9% 5.9% 5.9% 5.8% 5.8% 5.7% 5 Real Estate / Rental and Lease 4.5% 4.4% 4.5% 4.5% 4.5% 4.5% 4.5% 4.6% 4 Professional and Technical Services 6.4% 7.3% 7.3% 7.3% 7.3% 7.3% 7.3% 7.3% 7 Management 0.8% 1.2% 1.2% 1.2% 1.2% 1.3% 1.3% 1.3% 1 Administrative and Waste Services 10.8% 7.8% 7.9% 8.0% 8.1% 8.2% 8.2% 8.7% 9 Educational Services 1.3% 1.7% 1.7% 1.8% 1.8% 1.8% 1.8% 2.0% 2 Health Care and Social Assistance 10.3% 13.0% 13.1% 13.2% 13.4% 13.5% 13.6% 14.2% 14 Arts, Entertainment, and Recreation 2.0% 2.4% 2.4% 2.4% 2.4% 2.4% 2.3% 2.3% 2 Accommodation and Food Services 6.8% 7.0% 7.0% 7.0% 6.9% 6.9% 6.8% 6.6% 6 Other Services, Except Public Administration 5.9% 6.2% 6.2% 6.2% 6.2% 6.2% 6.2% 6.1% 6 Federal Civilian Government 1.3% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1 Federal Military 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6% 0 State and Local Government 9.9% 10.3% 10.3% 10.2% 10.2% 10.1% 10.1% 9.9% 9
A-96 Central Planning Area Supplemental EIS Table 4-35. Demographic and Employment Baseline Projections for Economic Impact Area FL-3 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 79,115.35 72,699.32 75,523.98 77,335.32 79,187.57 81,081.56 83,018.17 93,371.74 104,929.66 117,819.11 148,161.00 Farm Employment 0.5% 0.3% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0.3% 0.2% Forestry, Fishing, Related Activities 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% Mining 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.4% 0.4% 0.4% 0.4% Utilities 0.9% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.9% Construction 7.5% 4.4% 4.8% 4.8% 4.7% 4.7% 4.7% 4.5% 4.3% 4.1% 3.8% Manufacturing 6.8% 6.0% 6.1% 6.0% 5.9% 5.8% 5.8% 5.3% 4.9% 4.5% 3.8% Wholesale Trade 4.9% 4.8% 4.9% 4.8% 4.8% 4.8% 4.8% 4.7% 4.6% 4.6% 4.4% Retail Trade 8.3% 7.7% 7.7% 7.6% 7.6% 7.5% 7.5% 7.3% 7.0% 6.8% 6.3% Transportation and Warehousing 2.3% 2.3% 2.3% 2.3% 2.3% 2.3% 2.3% 2.2% 2.2% 2.1% 2.1% Information Employment 3.3% 3.1% 3.0% 3.0% 3.0% 3.0% 3.0% 2.9% 2.9% 2.8% 2.7% Finance and Insurance 8.0% 7.2% 7.2% 7.2% 7.3% 7.3% 7.3% 7.4% 7.5% 7.6% 7.7% Real Estate / Rental and Lease 2.3% 1.5% 1.5% 1.6% 1.6% 1.6% 1.6% 1.7% 1.7% 1.8% 1.9% Professional and Technical Services 8.1% 9.2% 9.1% 9.1% 9.1% 9.1% 9.1% 9.1% 9.1% 9.1% 9.0% Management 1.6% 2.4% 2.4% 2.5% 2.5% 2.6% 2.6% 2.8% 3.0% 3.3% 3.7% Administrative and Waste Services 7.1% 4.8% 4.9% 4.9% 5.0% 5.1% 5.1% 5.4% 5.8% 6.1% 6.9% Educational Services 0.8% 1.1% 1.1% 1.1% 1.2% 1.2% 1.2% 1.3% 1.4% 1.5% 1.7% Health Care and Social Assistance 12.1% 15.5% 15.4% 15.6% 15.7% 15.9% 16.0% 16.7% 17.4% 18.1% 19.5% Arts, Entertainment, and Recreation 1.5% 2.0% 2.0% 2.0% 1.9% 1.9% 1.9% 1.9% 1.8% 1.7% 1.6% Accommodation and Food Services 3.9% 4.2% 4.1% 4.1% 4.0% 4.0% 4.0% 3.8% 3.6% 3.5% 3.2% Other Services, Except Public Administration 4.0% 4.2% 4.1% 4.1% 4.1% 4.1% 4.1% 4.0% 4.0% 3.9% 3.8% Federal Civilian Government 2.7% 3.5% 3.4% 3.4% 3.4% 3.4% 3.4% 3.5% 3.5% 3.5% 3.5% Federal Military 1.2% 1.5% 1.5% 1.5% 1.5% 1.5% 1.5% 1.4% 1.4% 1.3% 1.2% State and Local Government 11.8% 12.8% 12.6% 12.6% 12.5% 12.5% 12.5% 12.3% 12.2% 12.0% 11.6% Total Personal Income Per Capita (in 2005 dollars) 33,224 31,323 31,639 32,001 32,373 32,754 33,144 35,240 37,593 40,226 46,260 Woods & Poole Economics Wealth Index (U.S. = 100) 79.5 77.2 77.2 77.2 77.1 77.1 77.1 77.0 77.0 77.0 77.0 Persons Per Household (in number of people) 2.4 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 Mean Household Total Personal Income (in 2005 dollars) 64,512 62,252 63,029 63,502 63,992 64,509 65,058 68,279 72,269 77,062 88,938 Total Number of Households (in thousands) 1,449.40 1,546.55 1,568.95 1,595.36 1,621.62 1,647.70 1,673.53 1,798.54 1,917.25 2,027.90 2,223.65 Income < $10,000 (thousands of households, 2000 dollars) 9.1% 8.7% 8.6% 8.4% 8.3% 8.1% 8.0% 7.2% 6.3% 5.5% 4.1% Income $10,000 to $19,999 13.8% 13.4% 13.1% 12.9% 12.6% 12.4% 12.1% 11.0% 9.7% 8.4% 6.2% Income $20,000 to $29,999 14.7% 14.2% 13.9% 13.7% 13.5% 13.2% 12.9% 11.7% 10.3% 8.9% 6.6% Income $30,000 to $44,999 19.6% 19.5% 19.3% 19.2% 19.0% 18.7% 18.5% 17.1% 15.3% 13.3% 9.9% Income $45,000 to $59,999 15.1% 15.7% 16.0% 16.3% 16.6% 16.8% 17.1% 18.0% 18.6% 18.4% 15.2% Income $60,000 to $74,999 9.7% 10.1% 10.3% 10.5% 10.7% 10.9% 11.1% 12.4% 14.2% 16.1% 18.7% Income $75,000 to $99,999 8.4% 8.7% 8.9% 9.0% 9.2% 9.4% 9.6% 10.7% 12.2% 13.9% 18.7% Income $100,000 or more 9.4% 9.7% 9.9% 10.1% 10.2% 10.4% 10.7% 11.9% 13.5% 15.4% 20.5% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 12 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-36 Demographic and Employment Baseline Projections for Economic Impact Area FL-4 2005 2010 2011 2012 2013 2014 2015 2020 2025 

Total Population (in thousands) 5,960.39 6,210.44 6,294.73 6,379.76 6,465.42 6,551.79 6,638.56 7,078.51 7,525

Age Under 19 years 24.7% 24.0% 23.9% 23.7% 23.6% 23.6% 23.5% 23.5% 23.Age 20 to 34 18.5% 18.6% 18.6% 18.7% 18.7% 18.8% 18.8% 18.2% 17.Age 35 to 49 22.1% 20.8% 20.4% 20.1% 19.7% 19.3% 19.0% 18.3% 18.Age 50 to 64 17.5% 18.9% 19.1% 19.3% 19.4% 19.6% 19.7% 19.3% 18.Age 65 and over 17.2% 17.8% 18.0% 18.2% 18.5% 18.8% 19.1% 20.7% 22.

Median Age of Population (in years) 44 45 45 45 45 45 45 46 White Population (in thousands) 46.6% 43.3% 42.7% 42.1% 41.5% 40.9% 40.4% 37.7% 35.Black Population (in thousands) 16.5% 16.5% 16.6% 16.6% 16.6% 16.7% 16.7% 16.8% 16.Native American Population (in thousands) 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.Asian and Pacific Islander Population (in thousands) 1.9% 2.1% 2.1% 2.2% 2.2% 2.2% 2.3% 2.5% 2.Hispanic or Latino Population (in thousands) 34.8% 37.9% 38.5% 39.0% 39.5% 40.0% 40.5% 42.8% 45.Male Population (in thousands) 48.8% 49.0% 49.1% 49.1% 49.1% 49.1% 49.1% 49.2% 49.Total Employment (in thousands of jobs) 3,395.35 3,329.05 3,426.96 3,479.99 3,533.68 3,588.03 3,643.04 3,928.30 4,230

 Farm Employment 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0.6% 0. Forestry, Fishing, Related Activities 0.4% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0. Mining 0.1% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.1% 0. Utilities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0. Construction 8.0% 5.0% 5.0% 5.0% 5.0% 5.1% 5.1% 5.3% 5. Manufacturing 3.6% 2.9% 2.9% 2.9% 2.8% 2.8% 2.7% 2.5% 2. Wholesale Trade 4.5% 4.3% 4.3% 4.2% 4.2% 4.2% 4.1% 3.9% 3. Retail Trade 11.2% 11.1% 11.1% 11.0% 11.0% 10.9% 10.9% 10.7% 10. Transportation and Warehousing 3.8% 3.9% 3.9% 3.9% 3.9% 3.8% 3.8% 3.7% 3. Information Employment 2.0% 1.7% 1.7% 1.7% 1.7% 1.7% 1.7% 1.6% 1. Finance and Insurance 5.0% 4.9% 4.9% 4.8% 4.8% 4.8% 4.8% 4.7% 4. Real Estate / Rental and Lease 6.0% 6.1% 6.1% 6.1% 6.1% 6.1% 6.1% 6.1% 6. Professional and Technical Services 6.5% 6.8% 6.8% 6.8% 6.8% 6.9% 6.9% 7.0% 7. Management 0.7% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0.8% 0. Administrative and Waste Services 9.0% 7.9% 8.0% 8.0% 8.1% 8.2% 8.2% 8.6% 9. Educational Services 1.8% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.6% 2. Health Care and Social Assistance 9.1% 11.4% 11.5% 11.6% 11.7% 11.8% 11.8% 12.3% 12. Arts, Entertainment, and Recreation 2.2% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2. Accommodation and Food Services 7.2% 7.4% 7.3% 7.3% 7.3% 7.3% 7.2% 7.1% 7. Other Services, Except Public Administration 7.7% 8.4% 8.4% 8.4% 8.4% 8.4% 8.5% 8.6% 8. Federal Civilian Government 1.0% 1.1% 1.1% 1.1% 1.0% 1.0% 1.0% 1.0% 1. Federal Military 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 0.4% 0.4% 0. State and Local Government 9.0% 9.6% 9.6% 9.5% 9.5% 9.5% 9.4% 9.3% 9.
A-98 Central Planning Area Supplemental EIS Table 4-36. Demographic and Employment Baseline Projections for Economic Impact Area FL-4 (continued). 2005 2010 2011 2012 2013 2014 2015 2020 2025 2030 2040 Total Earnings (in millions of 2005 dollars) 146,349.28 133,109.32 138,104.63 141,438.36 144,845.84 148,328.48 151,887.81 170,888.07 192,042.06 215,564.73 270,666.64 Farm Employment 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.3% 0.3% 0.3% Forestry, Fishing, Related Activities 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% Mining 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% Utilities 0.4% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Construction 9.4% 5.2% 5.6% 5.6% 5.6% 5.5% 5.5% 5.4% 5.3% 5.2% 4.9% Manufacturing 4.4% 3.6% 3.7% 3.7% 3.6% 3.6% 3.5% 3.3% 3.1% 2.9% 2.5% Wholesale Trade 6.8% 6.7% 6.9% 6.8% 6.8% 6.7% 6.7% 6.4% 6.2% 5.9% 5.4% Retail Trade 8.5% 8.4% 8.4% 8.3% 8.3% 8.2% 8.2% 7.9% 7.7% 7.4% 6.9% Transportation and Warehousing 4.0% 4.0% 3.9% 3.9% 3.9% 3.9% 3.8% 3.7% 3.6% 3.5% 3.2% Information Employment 3.6% 3.4% 3.4% 3.4% 3.4% 3.3% 3.3% 3.3% 3.2% 3.1% 3.0% Finance and Insurance 6.9% 6.2% 6.1% 6.1% 6.1% 6.1% 6.1% 6.1% 6.1% 6.1% 6.0% Real Estate / Rental and Lease 3.7% 2.4% 2.4% 2.4% 2.4% 2.4% 2.5% 2.5% 2.5% 2.6% 2.7% Professional and Technical Services 8.3% 9.2% 9.1% 9.1% 9.1% 9.2% 9.2% 9.4% 9.5% 9.6% 9.9% Management 1.3% 1.9% 1.9% 2.0% 2.0% 2.1% 2.1% 2.3% 2.5% 2.7% 3.2% Administrative and Waste Services 6.2% 4.9% 4.9% 5.0% 5.0% 5.1% 5.1% 5.4% 5.6% 5.9% 6.5% Educational Services 1.5% 2.2% 2.2% 2.2% 2.2% 2.2% 2.2% 2.3% 2.4% 2.5% 2.7% Health Care and Social Assistance 9.5% 12.2% 12.1% 12.2% 12.3% 12.4% 12.5% 13.0% 13.5% 14.1% 15.1% Arts, Entertainment, and Recreation 1.6% 1.9% 1.9% 1.9% 1.9% 1.9% 1.9% 1.8% 1.8% 1.8% 1.7% Accommodation and Food Services 4.3% 4.6% 4.5% 4.5% 4.5% 4.5% 4.4% 4.3% 4.2% 4.1% 3.9% Other Services, Except Public Administration 4.2% 4.6% 4.5% 4.5% 4.6% 4.6% 4.6% 4.6% 4.7% 4.7% 4.7% Federal Civilian Government 2.2% 2.7% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6% 2.6% Federal Military 0.6% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.6% 0.6% State and Local Government 11.8% 14.0% 13.8% 13.8% 13.8% 13.8% 13.8% 13.8% 13.7% 13.6% 13.5% Total Personal Income Per Capita (in 2005 dollars) 37,332 35,529 35,954 36,438 36,933 37,438 37,957 40,740 43,871 47,389 55,589 Woods & Poole Economics Wealth Index (U.S. = 100) 119.1 113.4 113.6 113.8 114.0 114.2 114.5 115.7 117.1 118.5 121.7 Persons Per Household (in number of people) 2.5 2.6 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Mean Household Total Personal Income (in 2005 dollars) 92,182 86,404 87,645 88,598 89,600 90,651 91,754 98,070 105,688 114,735 137,497 Total Number of Households (in thousands) 2,337.90 2,434.13 2,469.25 2,510.68 2,551.90 2,592.85 2,633.43 2,830.25 3,017.88 3,193.31 3,504.05 Income < $10,000 (thousands of households, 2000 dollars) 9.2% 8.8% 8.7% 8.5% 8.4% 8.2% 8.1% 7.2% 6.4% 5.6% 4.4% Income $10,000 to $19,999 12.1% 11.7% 11.5% 11.4% 11.2% 11.0% 10.7% 9.6% 8.5% 7.5% 5.8% Income $20,000 to $29,999 12.6% 12.3% 12.1% 11.9% 11.7% 11.5% 11.2% 10.0% 8.9% 7.9% 6.1% Income $30,000 to $44,999 17.3% 17.0% 16.8% 16.5% 16.3% 16.0% 15.7% 14.0% 12.4% 11.0% 8.6% Income $45,000 to $59,999 14.9% 15.3% 15.5% 15.6% 15.8% 15.9% 16.0% 16.2% 15.5% 14.1% 11.0% Income $60,000 to $74,999 10.6% 11.0% 11.2% 11.4% 11.6% 11.8% 12.0% 13.5% 15.1% 16.3% 15.8% Income $75,000 to $99,999 10.0% 10.3% 10.5% 10.7% 10.9% 11.1% 11.3% 12.8% 14.4% 16.4% 20.7% Income $100,000 or more 13.1% 13.5% 13.8% 14.0% 14.3% 14.5% 14.8% 16.7% 18.8% 21.4% 27.6% Notes: Median age, wealth index, and mean household income is the average of the original Woods & Poole values for the 9 counties in the EIA; income per capita calculated using personal income/total population for the EIA; persons per household calculated using total population/number of households for the EIA. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-37 Baseline Population Projections (in thousands) by Economic Impact Area M od ndar el Cale Year Year AL-1 MS-1 LA-1 LA-2 LA-3 LA-4 TX-1 TX-2 TX-3 FL-1 FL-2 

2010 725.48 470.61 334.72 587.88 1,126.87 1,267.52 1,771.25 626.33 6,192.43 896.10 657.42011 731.11 474.64 336.53 593.59 1,140.44 1,278.34 1,807.15 634.39 6,299.99 911.70 666.

1 2012 736.83 478.72 338.39 599.38 1,154.15 1,289.31 1,843.24 642.51 6,408.25 927.40 676.2 2013 742.62 482.85 340.27 605.23 1,167.97 1,300.40 1,879.50 650.70 6,517.13 943.19 685.3 2014 748.49 487.02 342.20 611.14 1,181.91 1,311.64 1,915.95 658.94 6,626.68 959.08 695.4 2015 754.41 491.23 344.15 617.10 1,195.92 1,322.96 1,952.51 667.23 6,736.63 975.02 704.5 2016 760.38 495.47 346.12 623.10 1,210.00 1,334.37 1,989.19 675.55 6,847.01 991.02 714.6 2017 766.41 499.75 348.12 629.15 1,224.17 1,345.89 2,026.02 683.92 6,957.91 1,007.10 724.7 2018 772.47 504.05 350.13 635.22 1,238.39 1,357.45 2,062.92 692.31 7,069.08 1,023.22 734.8 2019 778.57 508.38 352.16 641.34 1,252.68 1,369.10 2,099.94 700.73 7,180.66 1,039.39 743.9 2020 784.68 512.71 354.20 647.47 1,266.99 1,380.77 2,137.01 709.17 7,292.42 1,055.59 753.

10 2021 790.89 517.11 356.28 653.68 1,281.45 1,392.61 2,174.35 717.69 7,405.11 1,071.93 763.411 2022 797.15 521.54 358.38 659.95 1,296.07 1,404.55 2,212.34 726.31 7,519.54 1,088.51 773.412 2023 803.46 526.02 360.48 666.29 1,310.86 1,416.60 2,251.00 735.03 7,635.74 1,105.36 783.13 2024 809.82 530.53 362.60 672.68 1,325.83 1,428.75 2,290.33 743.85 7,753.73 1,122.46 793.14 2025 815.74 534.70 364.61 678.54 1,339.29 1,439.98 2,323.71 751.75 7,855.87 1,137.26 802.15 2026 821.98 539.11 366.70 684.79 1,353.80 1,451.87 2,361.17 760.29 7,968.97 1,153.65 812.16 2027 828.26 543.56 368.81 691.09 1,368.46 1,463.87 2,399.24 768.92 8,083.69 1,170.28 822.17 2028 834.60 548.05 370.92 697.46 1,383.29 1,475.96 2,437.91 777.65 8,200.07 1,187.15 833.18 2029 840.98 552.58 373.05 703.88 1,398.27 1,488.16 2,477.21 786.48 8,318.13 1,204.26 843.19 2030 846.94 556.77 375.07 709.79 1,411.83 1,499.47 2,511.01 794.43 8,421.37 1,219.22 852.420 2031 853.17 561.19 377.17 716.05 1,426.34 1,511.37 2,548.50 802.95 8,534.58 1,235.62 862.21 2032 859.46 565.63 379.27 722.36 1,440.99 1,523.36 2,586.55 811.57 8,649.31 1,252.25 872.422 2033 865.79 570.12 381.39 728.73 1,455.80 1,535.45 2,625.17 820.28 8,765.59 1,269.10 882.23 2034 872.17 574.64 383.51 735.16 1,470.76 1,547.64 2,664.37 829.09 8,883.43 1,286.17 892.24 2035 878.13 578.84 385.53 741.09 1,484.37 1,558.97 2,698.47 837.06 8,987.43 1,301.24 902.25 2036 884.41 583.28 387.64 747.40 1,498.95 1,570.96 2,736.13 845.63 9,101.21 1,317.72 911.26 2037 890.74 587.76 389.77 753.76 1,513.68 1,583.03 2,774.31 854.28 9,216.42 1,334.42 922.27 2038 897.11 592.27 391.90 760.17 1,528.55 1,595.20 2,813.03 863.02 9,333.09 1,351.32 932.28 2039 903.53 596.82 394.04 766.64 1,543.57 1,607.46 2,852.29 871.85 9,451.24 1,368.44 942.429 2040 909.54 601.05 396.08 772.62 1,557.29 1,618.89 2,886.77 879.89 9,556.30 1,383.66 951.30 2041 916.04 605.67 398.25 779.20 1,572.59 1,631.33 2,927.06 888.89 9,677.28 1,401.19 962.31 2042 922.60 610.31 400.43 785.83 1,588.03 1,643.87 2,967.91 897.99 9,799.78 1,418.94 972.32 2043 929.20 615.00 402.62 792.52 1,603.64 1,656.50 3,009.33 907.18 9,923.84 1,436.92 983.33 2044 935.84 619.72 404.83 799.26 1,619.39 1,669.23 3,051.33 916.46 10,049.47 1,455.12 994.434 2045 942.54 624.47 407.04 806.06 1,635.30 1,682.06 3,093.91 925.84 10,176.68 1,473.56 1,005.35 2046 949.28 629.27 409.27 812.92 1,651.37 1,694.99 3,137.09 935.31 10,305.51 1,492.22 1,016.36 2047 956.07 634.09 411.51 819.84 1,667.59 1,708.02 3,180.87 944.88 10,435.97 1,511.13 1,027.37 2048 962.91 638.96 413.76 826.82 1,683.97 1,721.15 3,225.27 954.55 10,568.08 1,530.27 1,039.38 2049 969.80 643.86 416.03 833.86 1,700.52 1,734.37 3,270.28 964.32 10,701.87 1,549.66 1,050.39 2050 976.73 648.81 418.30 840.95 1,717.22 1,747.70 3,315.92 974.19 10,837.34 1,569.29 1,062.40 2051 983.72 653.78 420.59 848.11 1,734.09 1,761.14 3,362.20 984.16 10,974.54 1,589.17 1,073.

Notes: Actual Woods & Poole data for 2010 through 2020, 2025, 2030, 2035, and 2040. Missing estimates through 2040 calculated using average annual 

period; projections after 2040 calculated using the average annual growth rate from 2035 to 2040. Source: Woods & Poole Economics, Inc., 2010. 
Table 4-38 Baseline Employment Projections (in Thousands) by Coastal Subarea Mode e l Cal ndar Year Year AL-1 MS-1 LA-1 LA-2 LA-4 TX-2 LA-3 TX-1 TX-3 FL-1 FL-2 

20 10 353.63 243.91 177.73 321.93 663.02 728.32 840.00 309.97 3,596.00 489.82 330.0

 20 59 11 362. 249.36 182.05 330.21 680.63 745.53 864.86 317.96 3,700.61 504.24 338.

1 20 69 12 366. 251.56 183.91 334.03 689.17 752.64 878.23 321.85 3,758.99 512.13 342.72 20 81 13 370. 253.76 185.81 337.89 697.80 759.77 891.81 325.78 3,818.15 520.13 346.3 20 97 14 374. 255.98 187.70 341.78 706.51 766.93 905.55 329.76 3,878.09 528.26 351.4 20 15 15 379. 258.22 189.62 345.70 715.33 774.11 919.48 333.78 3,938.83 536.52 355.5 20 37 16 383. 260.47 191.54 349.65 724.23 781.30 933.58 337.82 4,000.39 544.90 360.06 20 62 17 387. 262.73 193.50 353.63 733.24 788.52 947.87 341.92 4,062.77 553.43 364.47 20 90 18 391. 265.01 195.46 357.65 742.34 795.74 962.34 346.07 4,125.95 562.07 368.8 20 21 19 396. 267.30 197.44 361.69 751.53 802.98 977.00 350.24 4,189.99 570.86 373.9 20 55 20 400. 269.62 199.43 365.76 760.83 810.24 991.85 354.48 4,254.86 579.78 378.

10 20 99 21 404. 271.97 201.47 369.93 770.43 817.53 1,007.28 358.83 4,322.32 589.12 382.11 20 48 22 409. 274.34 203.54 374.15 780.14 824.89 1,022.95 363.24 4,390.84 598.61 387.12 20 02 23 414. 276.74 205.62 378.41 789.98 832.32 1,038.87 367.71 4,460.45 608.25 392.713 20 61 24 418. 279.15 207.73 382.73 799.95 839.81 1,055.03 372.22 4,531.17 618.06 397.714 20 75 25 422. 281.38 209.65 386.61 808.81 846.71 1,069.01 376.26 4,592.14 626.48 402.15 20 35 26 427. 283.81 211.77 390.93 818.92 854.06 1,085.44 380.83 4,664.06 636.56 407.16 20 99 27 431. 286.26 213.92 395.30 829.16 861.46 1,102.12 385.46 4,737.10 646.80 412.17 20 69 28 436. 288.73 216.09 399.71 839.52 868.93 1,119.07 390.14 4,811.29 657.21 417.18 20 43 29 441. 291.22 218.28 404.18 850.02 876.47 1,136.27 394.88 4,886.64 667.78 422.19 20 72 30 445. 293.52 220.27 408.21 859.36 883.43 1,151.17 399.12 4,951.73 676.88 427.20 20 47 31 450. 296.02 222.48 412.68 870.01 890.79 1,168.65 403.92 5,028.34 687.75 433.021 20 27 32 455. 298.55 224.71 417.21 880.78 898.22 1,186.39 408.78 5,106.13 698.79 438.22 20 12 33 460. 301.09 226.97 421.78 891.69 905.70 1,204.41 413.70 5,185.13 710.01 444.023 20 02 34 465. 303.66 229.25 426.41 902.73 913.25 1,222.69 418.67 5,265.35 721.41 449.724 20 47 35 469. 306.03 231.32 430.59 912.57 920.25 1,238.56 423.13 5,334.78 731.22 454.725 20 37 36 474. 308.61 233.62 435.21 923.76 927.61 1,257.14 428.15 5,416.31 742.93 460.426 20 32 37 479. 311.21 235.94 439.89 935.09 935.02 1,275.99 433.24 5,499.10 754.83 466.27 20 33 38 484. 313.83 238.28 444.61 946.56 942.50 1,295.13 438.38 5,583.14 766.92 472.28 20 39 39 489. 316.47 240.64 449.38 958.16 950.04 1,314.56 443.59 5,668.48 779.21 478.29 20 98 40 493. 318.92 242.80 453.71 968.53 957.04 1,331.45 448.26 5,742.46 789.79 483.30 20 14 41 499. 321.61 245.21 458.58 980.40 964.70 1,351.41 453.58 5,830.23 802.44 489.31 20 35 42 504. 324.31 247.64 463.51 992.42 972.41 1,371.68 458.97 5,919.33 815.29 495.32 20 62 43 509. 327.05 250.10 468.48 1,004.59 980.19 1,392.26 464.42 6,009.81 828.36 502.33 20 94 44 514. 329.80 252.58 473.52 1,016.91 988.02 1,413.14 469.94 6,101.66 841.63 508.34 20 32 45 520. 332.58 255.09 478.60 1,029.38 995.93 1,434.33 475.52 6,194.92 855.11 514.35 20 76 46 525. 335.38 257.62 483.74 1,042.00 1,003.89 1,455.85 481.17 6,289.60 868.81 521.36 20 25 47 531. 338.20 260.17 488.94 1,054.78 1,011.92 1,477.68 486.88 6,385.73 882.72 528.37 20 80 48 536. 341.05 262.75 494.19 1,067.71 1,020.01 1,499.84 492.66 6,483.33 896.87 534.38 20 40 49 542. 343.92 265.36 499.49 1,080.81 1,028.17 1,522.34 498.52 6,582.42 911.23 541.39 20 07 50 548. 346.82 267.99 504.86 1,094.06 1,036.39 1,545.17 504.44 6,683.02 925.83 548.440 20 79 51 553. 349.74 270.65 510.28 1,107.48 1,044.68 1,568.35 510.43 6,785.16 940.66 555.4

Notes: Actual Woods & Poole data for 2010 through 2020, 2025, 2030, 2035, and 2040. Missing estimates through 2040 calculated using average annual growth rate for the 5 year 

calculated using the average annual growth rate from 2035 to 2040. Source: Woods & Poole Economics, Inc., 2010. 
Apex Environmental Services 17.44% 

Liquid Environmental Solutions 13.07% 

Tidewater Landfill LLC (Environmental Operations) Coast Guard Road Sanitary Landfill 11.08% 

Newpark Environmental Mud Facility—Venice 11.08% 

MBO LLC (Lacassine Oilfield Services) 3.20% 

Newpark Environmental Services—Morgan City Site Code 5102 2.84% 

Chemical Waste Management 1.04% 

Aaron Oil 0.89% 

Waste Water 0.83% 

Intergulf 0.58% 

Cliff Berry, Inc.—Tampa/ Miami 0.55% 

Clearview Landfill 0.46% 

Newpark Environmental Intercoastal City 0.27% 

Vacco Marine 0.16% 

Oil Recovery Company 0.08% 

Vacco Marine/River Birch 0.03% 

City of Tampa Treatment Plant 0.01% 

Bealine 0.00% 

SWS 0.00% 

Gulf Coast Water Authority 0.00% 

M.A. Norden Company 0.00% 

WH Chastang Landfill 0.00% 

Geocycle/Holcim 0.00% 

Sunbelt Crushing 0.00% 

Baldwin County Magnolia Landfill 0.00% 

Tarpon Recycling 0.00% 

Covanta-Huntsville 0.00% 

WM Springhill Regional Landfill 0.00% 

Fort Walton Transfer 0.00% 

Gulf West Landfill (Texas) 0.00% 

Allied Waste/BFI Colonial Landfill 0.00% 

Jefferson Parish Waste Management 0.00% 

Allied Waste Jefferson Davis Parish 0.00% 

Allied Waste Recycling Center 0.00% 

Newpark Environmental Services—Cameron Site Code 1205 0.00% 

Advanced Disposal Services 0.00% 

WM Pecan Grove 0.00% 

Coastal Plains—Waste Management 0.00% 

Sources: British Petroleum, 2011a and 2011b.
A-102 Central Planning Area Supplemental EIS 

Table 4-40 

 

Solid Waste Collected from the Deepwater Horizon Event 

Landfill Name Percentage 

WM Springhill Regional Landfill 26.11% 

Allied Waste/BFI Colonial Landfill 25.12% 

Baldwin County Magnolia Landfill 11.31% 

Clearview Landfill 8.66% 

Newpark Environmental Services—Fourchon Site Code 2913 7.99% 

River Birch Industries Landfill 7.70% 

WH Chastang Landfill 6.81% 

Jefferson Parish Waste Management 6.56% 

Newpark Environmental Services—Cameron Site Code 1205 4.60% 

WM Pecan Grove 3.82% 

Covanta-Huntsville 0.78% 

Tidewater Landfill LLC (Environmental Operations) Coast Guard Road Sanitary Landfill 0.50% 

Sunbelt Crushing 0.34% 

M.A. Norden Company 0.17% 

Tarpon Recycling 0.07% 

Coastal Plains—Waste Management 0.06% 

Allied Waste Recycling Center 0.03% 

Gulf West Landfill (Texas) 0.03% 

Fort Walton Transfer 0.02% 

Advanced Disposal Services 0.00% 

Intergulf 0.00% 

Aaron Oil 0.00% 

Geocycle/Holcim 0.00% 

Apex Environmental Services 0.00% 

Liquid Environmental Solutions 0.00% 

Chemical Waste Management 0.00% 

Oil Recovery Company 0.00% 

City of Tampa Treatment Plant 0.00% 

Cliff Berry, Inc.—Tampa/ Miami 0.00% 

Vacco Marine 0.00% 

Vacco Marine/River Birch 0.00% 

Gulf Coast Water Authority 0.00% 

Waste Water 0.00% 

Allied Waste Jefferson Davis Parish 0.00% 

Newpark Environmental Mud Facility—Venice 0.00% 

Newpark Environmental Services—Morgan City Site Code 5102 0.00% 

Newpark Environmental Intercoastal City 0.00% 

MBO LLC (Lacassine Oilfield Services) 0.00% 

Bealine 0.00% 

SWS 0.00% 

Sources: British Petroleum, 2011a and 2011b. 
Figures and Tables A-103 

Table 4-41 

 

Deepwater Horizon Waste Destination Communities 

Landfill Name and Location 

Percent 

Minority 

living 

within 

1-Mile 

Radius 

of Site 

Total 

Population 

living within 

1-Mile Radius 

of Site 

(2000 Census) 

Percentage of 

Total DWH 

Liquid Waste 

Collected 

Percentage of 

Total DWH 

Solid Waste 

Collected 

Liquid Environmental Solutions, Mobile, AL 95.80% 4,257 13.17% 0.00% 

Oil Recovery Company, Mobile, AL 93.90% 3,238 0.08% 0.00% 

Cliff Berry, Inc.—Miami, FL 92.80% 24,768 >0.58% 0.00% 

River Birch Industries Landfill Avondale, LA 92.20% 167 16.99% 8.67% 

Jefferson Parish Waste Management, Avondale, LA 91.40% 120 0.00% 0.02% 

Sunbelt Crushing, Mobile, AL 76.80% 3,173 0.00% 0.29% 

Chemical Waste Management, Emelle, AL 75.20% 33 1.02% 0.00% 

WM Springhill Regional Landfill, Campbelton, FL 74.30% 109 0.00% 23.67% 

Allied Waste/BFI Colonial Landfill, Sorrento, LA 74.10% 153 0.00% 21.98% 

Allied Waste Recycling Center, Metairie, LA 63.50% 14,420 0.00% 0.06% 

WH Chastang Landfill, Mount Vernon, AL 62.50% 123 0.00% 8.93% 

Clearview Landfill Lake, MS 50.90% 55 0.44% 14.92% 

Cliff Berry, Inc.—Tampa, FL 50.50% 1,817 >0.58% 0.00% 

Apex Environmental Services, Theodore, AL 50.40% 383 17.44% 0.00% 

Newpark Environmental Services Site Code 5102 

Morgan City, LA 35.90% 4,237 2.74% 0.00% 

Landfill Name and Location 

Percent 

Below 

Poverty 

Living within 

a 1-Mile 

Radius 

of Site 

Total Population 

Living within a 

1-Mile Radius of 

Site 

(2000 Census) 

Percentage of 

Total DWH 

Event Liquid 

Waste Collected 

Percentage of 

Total DWH 

Event Solid 

Waste Collected

Liquid Environmental Solutions, Mobile, AL 63.30% 4,257 13.17% 0.00% 

Newpark Environmental Mud Facility—Venice, LA 50.00% 2 10.90% 0.00% 

Oil Recovery Company, Mobile, AL 41.70% 3,238 0.08% 0.00% 

Chemical Waste Management, Emelle, AL 36.40% 33 1.02% 0.00% 

Newpark Environmental Services Site Code 2913, 

Fourchon, LA 33.30% 3 30.14% 0.00% 

Vacco Marine, Houma, LA 29.20% 525 0.16% 0.00% 

River Birch Industries Landfill, Avondale, LA 28.10% 167 16.99% 8.67% 

Jefferson Parish Waste Management, Avondale, LA 26.70% 120 0.00% 0.02% 

Apex Environmental Services, Theodore, AL 26.20% 383 17.44% 0.00% 

Allied Waste/BFI Colonial Landfill, Sorrento, LA 25.00% 153 0.00% 21.98% 

WM Pecan Grove, Pass Christian, MS 14.40% 290 0.00% 3.28% 

Baldwin County Magnolia Landfill, AL 13.70% 446 0.00% 11.18% 

MBO LLC (Lacassine Oilfield Services) 12.90% 85 3.82% 0.00% 

Coast Guard Rd Sanitary Landfill 0.00% 0 0.00% 8.05% 

Sources: British Petroleum, 2011 and 2011b. 
A-104 Central Planning Area Supplemental EIS 

Table 4-42 

 

Gulf Coast Claims Facility—Deepwater Horizon Claimant Data by State 

Alabama Claimant Status No. of Claimants 

TOTAL GCCF Claimants to Date (Claimants may have one or more Claim Type) 66,129 

1. Claimants Paid and Approved for Payment 26,815 

2. Claimants Requiring Additional Information or Documentation (Claimants providing no 

documentation: 7,503) 10,913 

3. Claimants Referred to Government, Moratorium and Real Estate Funds 1 

4. Denied Claimants 22,080 

5. Claimants Under Review (Emergency Advance Payment) 4,561 

6. Claimants Under Review (for Final Claim Only) 1,759 

State 

Claims for Emergency or Final Payment 

(includes Individual and Business)

Claims 

Submitted 

Number of Claims 

Paid Amount Paid 

Alabama 1. Removal and Cleanup Costs 394 0 $0 

 2. Real or Personal Property 1,201 35 $364,463 

 3. Lost Earnings or Profits 65,655 26,380 $426,205,265 

 

4. Loss of Subsistence Use of Natural 

Resources 4,119 3 $9,000 

 5. Physical Injury/Death 745 5 $1,300 

Alabama 

Total Total to Date 72,114 55,166 $426,580,028 

Florida Claimant Status No. of Claimants 

TOTAL GCCF Claimants to Date (Claimants may have one or more Claim Type) 151,760 

1. Claimants Paid and Approved for Payment 63,578 

2. Claimants Requiring Additional Information or Documentation (Claimants providing no 

documentation: 7,503) 20,557 

3. Claimants Referred to Government, Moratorium and Real Estate Funds 0 

4. Denied Claimants 50,858 

5. Claimants Under Review (Emergency Advance Payment) 12,093 

6. Claimants Under Review (for Final Claim Only) 4,674 

State 

Claims for Emergency or Final Payment 

(includes Individual and Business)

Claims 

Submitted 

Number of Claims 

Paid Amount Paid 

Florida 1. Removal and Cleanup Costs 573 0 $0 

 2. Real or Personal Property 2,319 23 $71,400 

 3. Lost Earnings or Profits 153,118 62,362 $848,846,576 

 

4. Loss of Subsistence Use of Natural 

Resources 2,473 0 $0 

 5. Physical Injury/Death 552 0 $0 

Florida 

Total Total to Date 159,035 62,385 $848,917,976 
Figures and Tables A-105 

Table 4-42. Gulf Coast Claims Facility—Deepwater Horizon Claimant Data by State (continued). 

Louisiana Claimant Status No. of Claimants 

TOTAL GCCF Claimants to Date (Claimants may have one or more Claim Type) 187,476 

1. Claimants Paid and Approved for Payment 56,308 

2. Claimants Requiring Additional Information or Documentation (Claimants providing no 

documentation: 7,503) 38,906 

3. Claimants Referred to Government, Moratorium and Real Estate Funds 8 

4. Denied Claimants 75,495 

5. Claimants Under Review (Emergency Advance Payment) 12,136 

6. Claimants Under Review (for Final Claim Only) 4,623 

State 

Claims for Emergency or Final Payment 

(includes Individual and Business)

Claims 

Submitted 

Number of Claims 

Paid Amount Paid 

Louisiana 1. Removal and Cleanup Costs 1,155 0 $0 

 2. Real or Personal Property 2,876 39 $421,400 

 3. Lost Earnings or Profits 173,632 55,120 $817,551,315 

 

4. Loss of Subsistence Use of Natural 

Resources 16,553 1 $3,000 

 5. Physical Injury/Death 6,043 6 $7,800 

Louisiana 

Total Total to Date 200,259 55,166 $817,983,515 

Mississippi Claimant Status No. of Claimants 

TOTAL GCCF Claimants to Date (Claimants may have one or more Claim Type) 49,879 

1. Claimants Paid and Approved for Payment 14,218 

2. Claimants Requiring Additional Information or Documentation (Claimants providing no 

documentation: 7,503) 6,963 

3. Claimants Referred to Government, Moratorium and Real Estate Funds 5 

4. Denied Claimants 24,143 

5. Claimants Under Review (Emergency Advance Payment) 3,155 

6. Claimants Under Review (for Final Claim Only) 1,395 

State 

Claims for Emergency or Final Payment 

(includes Individual and Business)

Claims 

Submitted 

Number of Claims 

Paid Amount Paid 

Mississippi 1. Removal and Cleanup Costs 282 0 $0 

 2. Real or Personal Property 1,040 13 $63,500 

 3. Lost Earnings or Profits 44,793 13,978 $202,514,200 

 

4. Loss of Subsistence Use of Natural 

Resources 6,299 1 $1,000 

 5. Physical Injury/Death 844 4 $4,737 

Mississippi 

Total Total to Date 53,258 13,996 $202,583,437 
A-106 Central Planning Area Supplemental EIS 

Table 4-42. Gulf Coast Claims Facility—Deepwater Horizon Claimant Data by State (continued). 

Texas Claimant Status No. of Claimants 

TOTAL GCCF Claimants to Date (Claimants may have one or more Claim Type) 9,583 

1. Claimants Paid and Approved for Payment 2,657 

2. Claimants Requiring Additional Information or Documentation (Claimants providing no 

documentation: 7,503) 587 

3. Claimants Referred to Government, Moratorium and Real Estate Funds 0 

4. Denied Claimants 5,412 

5. Claimants Under Review (Emergency Advance Payment) 537 

6. Claimants Under Review (for Final Claim Only) 390 

State 

Claims for Emergency or Final Payment 

(includes Individual and Business)

Claims 

Submitted 

Number of Claims 

Paid Amount Paid 

Texas 1. Removal and Cleanup Costs 79 0 $0 

2. Real or Personal Property 167 4 $50,000 

3. Lost Earnings or Profits 9,371 2,618 $81,394,000 

4. Loss of Subsistence Use of Natural 

Resources 301 0 $0 

5. Physical Injury/Death 277 1 $100 

Texas 

Total Total to Date 10,195 2,623 $81,444,100 

Sources: Gulf Coast Claims Facility, 2010 and 2011. 
Figures and Tables A-107 

Table 5-1 

 

Scoping Comments 

Name and Affiliation Concerns 

Defenders of Wildlife 

Washington, DC 

 Ensure the reanalysis of baseline conditions is woven into the Agency’s decisionmaking process. 

 The Supplemental EIS should include impacts to threatened and endangered 

species, target and nontarget fish species, water quality, seafloor conditions, and 

any other natural resources affected by the Deepwater Horizon spill. 

 The BOEMRE must closely examine the types of basic information about the Gulf 

marine environment that were not analyzed prior to the spill. 

 The reassessment of risk for future oil spills has two primary components. First, 

BOEMRE must reexamine the risk of oil spills in general. Second, BOEMRE 

must reexamine the risk of oil spills in the particular locations and conditions at 

issue in a particular NEPA analysis. 

 As BOEMRE examines the risk of future oil spills occurring, BOEMRE also must 

look closely at the likely impact of such spills. 

 The BOEMRE must ensure that its use of categorical exclusions and 

environmental assessments that tier to the Multisale EIS are on solid footing by 

taking a precautionary approach that reexamines the environmental impacts of a 

range of oil and gas activities that have not been analyzed adequately, or in some 

cases analyzed at all. 

 In examining ways to maximize avoidance and minimize impacts to 

environmental resources, BOEMRE should begin with analyzing additional 

measures to address safety and well control issues for both deep and shallowwater operations. 

 The Supplemental EIS also should examine options for improving offshore 

inspections and safety procedures, enforcing stronger cementing and well control 

protocols, and requiring improvements in the reliability factor of blowout 

prevention technology in any water depth. 

 Defenders of Wildlife further recommends that BOEMRE enact a hiatus in future 

permits and approvals for floating offshore storage and processing vessels due to 

the spill threat posed by these facilities and the demonstrated lack of effective 

response capabilities for large oil releases evidenced during the Deepwater 

Horizon event, and we request that this limitation on future permitting be analyzed 

in the Supplemental EIS. 

 In addition to the regulatory suggestions listed above, the Supplemental EIS 

should also assess the impact of requiring the following measures to increase 

worker safety, protect sensitive ecosystems and marine and intertidal habitats, and 

ensure a more adequate, rapid response to future OCS disasters: (1) research, 

development, and implementation of a new type of fail-safe backup valve, shut-in 

device that would reliably preclude loss of well control in the event of the failure 

of the blowout preventer in any water depth; measures beyond a future 

requirement of a second blind shear ram will likely be necessary; (2) 

predeployment of a rig capable of drilling a relief well at the appropriate water 

depth in a location within a certain reasonable response time of every drilling site; 

(3) strict requirements that oil spill contingency plans be certified by the U.S. 

Government as capable of immediate response in the event of a “worst case” well 

blowout, riser break, damaged floating storage vessel, tankship spill, or other 

cause of a major hydrocarbon release into the marine environment; (4) research 

and development of new types of biodegradable dispersants, their comprehensive 

testing and certification by USEPA for use in mass quantities under predefined 
A-108 Central Planning Area Supplemental EIS 

Table 5-1. Scoping Comments (continued). 

Name and Affiliation Concerns 

Defenders of Wildlife 

Washington, DC 

appropriate conditions, their manufacture in commercial quantities, and their 

predeployment at locations of possible future need; (5) engineering and development 

of large ship-scaled oil skimmers for use in realistic wind, wave, and ocean current 

conditions, to be certified by the U.S. Coast Guard and built and operated by the 

petroleum industry; (6) immediate development and manufacture of more effective 

oil spill containment technologies and sorbent booms, and their predeployment in 

storage facilities in geographic areas of likely future need; (7) required testing of spill 

response technology in real world conditions and mandatory certification as to the 

measurable response impact of response equipment and plans; (8) a minimum 

requirement for response capacity onsite or within reasonable distance such that 

operators have capacity to recover a certain minimum percentage of oil spilled; and 

(9) bonding requirements sufficient to cover the cost of response and cleanup in the 

event of a blowout or other spill are necessary. 

 The No Action alternative of canceling the remaining lease sales should receive 

robust consideration in order to guarantee maximum protection for the resources that 

have been damaged by the Deepwater Horizon event. 

 The Defenders of Wildlife further reiterate that no activities in reliance on the 

previous inadequate Gulf Multisale EIS should move forward until the Supplemental 

EIS is complete, including all analyses that tier to the previous EIS to justify use of 

an environmental assessment or categorical exclusion. 

 The Supplemental EIS should also strongly consider exclusion of sensitive areas and 

possible recommendations for Gulf marine protected areas. 

Center for Biological 

Diversity 

San Francisco, CA 

 In determining the scope of the environmental impacts of OCS drilling in the GOM, 

BOEMRE should take into account the fact that many of the species move in and 

throughout the GOM. 

 It should also take into account all aspects of drilling including spills—both large and 

small, seismic activities—both noise impacts and vessel strikes, impacts to fisheries, 

tourism, and other industries that rely on the health of the GOM. 

 It is unclear at this time, and may be for some time, the entire impact of the spill on 

the flora and fauna of the GOM; therefore, BOEMRE should employ precautionary 

principles in its estimates of the harm as well as its assumptions about future spills. 

 The BOEMRE must also take into account the already degraded status of the Gulf of 

Mexico in its assessment of the environmental baseline, as well as the effect of these 

persistent stressors. 

 The BOEMRE should include detailed assessments of (1) areas of high seismic risk 

or seismicity, relatively untested deep water, or remote areas; or (2) activities within 

the boundary of a proposed or established marine sanctuary, and/or within or near the 

boundary of a proposed or established wildlife refuge or areas of high biological 

sensitivity; or (3) activities in areas of hazardous natural bottom conditions; or (4) 

utilizing new or unusual technology. 

 The BOEMRE should analyze and review areas and activities in the GOM OCS 

program that (a) have significant impacts on public health or safety; (b) have 

significant impacts on such natural resources and unique geographic characteristics 

as historic or cultural resources; park, recreation, or refuge lands; wilderness areas; 

wetlands (Executive Order 11990); floodplains (Executive Order 11988); national 

monuments; migratory birds; and other ecologically significant or critical areas;
Figures and Tables A-109 

Table 5-1. Scoping Comments (continued). 

Name and Affiliation Concerns 

Center for Biological 

Diversity 

San Francisco, CA 

(c) have highly controversial environmental effects or involve unresolved conflicts 

concerning alternative uses of available resources [NEPA Section 102(2)(E)]; (d) 

have highly uncertain and potentially significant environmental effects or involve 

unique or unknown environmental risks; . . . . (h) have significant impacts on species 

listed, or proposed to be listed, on the List of Endangered or Threatened Species or 

have significant impacts on designated Critical Habitat for these species; (i) violate a 

Federal law, or a State, local, or tribal law or requirement imposed for the protection 

of the environment. 

 The BOEMRE should also address the following significant issues in its 

Supplemental EIS: (1) environmental impacts or worst-case scenario oil spills and 

cumulative oil spills, including response activities and the use of dispersants; (2) the 

direct, indirect, and cumulative climate change impacts of the action, including the 

greenhouse gas emissions from the produced oil and gas, and the influence of those 

climate change impacts on the affected environment; (3) the impacts of the action on 

special status species such as those protected under the Endangered Species Act and 

Marine Mammal Protection Act and sensitive habitat areas, including but not limited 

to critical habitat, essential fish habitat, marine protected areas; (4) a reasonable 

range of alternatives that would avoid or minimize environmental impacts; (5) 

broader cumulative impacts analysis which take into consideration the incremental 

impacts of the action when considered in conjunction with past, present, and 

reasonably foreseeable future actions in the Gulf; (6) at lease sale and exploration 

stages, each EIS should contain site-specific analyses, smaller in scale than a typical 

multisale EIS, though not so narrowly focused as to result in impermissible 

segmentation of the project; (7) at exploration and drilling stages, specific focus on 

time and place of activity, keeping in mind seasonal shifts in migratory patterns and 

habitat composition. 

Chevron North 

America Exploration 

and Production 

Company 

Houston, TX 

 The Supplemental EIS should be confined to truly new information and focus on 

impacts of accidental events and to a lesser extent, cumulative impacts. 

 The BOEMRE must heed its own finding that a catastrophic spill remains a very low 

probability. 

 The planned Supplemental EIS must proceed with the supplemental analyses based 

upon information available at a certain date and cannot rely on speculative 

information and not await a series of new GOM studies. 

 When there are gaps in data and knowledge, BOEMRE must identify the information 

that is not known in the Supplemental EIS. 

 The BOEMRE must carefully review all new information and ensure its reliability 

before inclusion in the Supplemental EIS. 

 The BOEMRE must consider recent, significant improvements in safety and response 

capacity in the Supplemental EIS. 

 Chevron encourages BOEMRE to consider a reasonable range of clearly defined 

proposed alternatives and each alternative should be concise with no ambiguity. 

 Future NEPA analysis should tier to this Supplemental EIS. 

 The BOEMRE must review any suggestions for new and additional mitigation 

measures very carefully and have sufficient information to support their adoption. 

 There is no evidence that certain activities at a particular water depth are inherently 

more dangerous than others. 
A-110 Central Planning Area Supplemental EIS 

Table 5-1. Scoping Comments (continued). 

Name and Affiliation Concerns 

Dean Peeler 

Alabama Petroleum 

Council (APC) 

Mobile, AL 

 It is prudent to update the baseline conditions and potential environmental effects of 

oil and natural gas leasing. 

 The BOEMRE should use any currently new information that helps evaluate the 

defined impacts of the lease sales. 

 Proposed Lease Sales 216, 218, and 222 should be held with no reduction in the 

acreage traditionally offered in areawide lease sales. 

 The Supplemental EIS development should complement other environmental 

analyses by BOEMRE on the 2012-2017 5-Year Program. 

Andy Radford 

American Petroleum 

Institute (API) 

 Lease Sales 216, 218, and 222 should be held with no reduction in the acreage 

traditionally offered in areawide lease sales. 

 The scope of the Supplemental EIS should be focused specifically on new 

information that is readily available during the drafting of the Supplemental EIS and 

should limit the Supplemental EIS to an analysis of this new information as it exists 

at this time. 

 The BOEMRE must consider the extensive safety improvements implemented since 

the Deepwater Horizon event and consider the possibility of a catastrophic oil spill 

remains a very low probability. 

 The implementation of new drilling and environmental safeguards by industry since 

the Deepwater Horizon event should be considered and analyzed in the Supplemental 

EIS. 

 The possibility of another catastrophic spill will be reduced even further since 

implementation of the extensive safety improvements. 

 The Supplemental EIS should be designed specifically to be used as a reference for 

tiering in the future. 

Marine Mammal 

Commission 

Bethesda, MD 

 The BOEMRE should develop a set of standards for baseline information needed to 

assess the effects of oil and gas operations on marine mammals and their 

environment, initiate research on these topics prior to the resumption of lease sales in 

the Gulf of Mexico, and consider ways to improve oil-spill prevention and response 

capabilities. 

U.S. Fish and Wildlife 

Service 

Lafayette, LA 

 The Supplemental EIS should evaluate direct, indirect, and cumulative oil spill 

impacts from MC 252 to wetlands, migratory birds, endangered and threatened 

species, and designated critical habitat, as well as any impacts to those FWS trust 

resources from potential future spills. 

 Any possible correlations of the MC 252 spill and potential future spills to climate 

change should also be discussed. 

 The Supplemental EIS should include an assessment of potential direct, indirect, and 

cumulative impacts (including global climate change) to FWS trust resources from 

oil and gas industry exploration, development and response activities. 

 The FWS requests that BOEMRE discuss the relative risk of exploration and 

production wells leaking oil on the continental shelf versus those located on the 

continental slope and deepwater Gulf of Mexico. The BOEMRE should revise spill 

probabilities and model different sized spills, including catastrophic or multiday 

spills for the Gulf of Mexico for sources of spills in offshore and nearshore 

environments. 

 Any new safety regulations or revised permit review processes should be evaluated in 

the proposed Supplemental EIS for their impact to FWS trust resources. Changes to 

spill contingency planning, spill response, and restoration actions should also be 

described and their effects on FWS trust resources assessed. 
Figures and Tables A-111 

Table 5-1. Scoping Comments (continued). 

Name and Affiliation Concerns 

International 

Association of 

Geophysical 

Contractors (IAGC) 

Houston, TX 

 Any analysis of alternatives should recognize and take into account the improved 

regulatory management, oversight, and enforcement enacted since the blowout of the 

Macondo well and the resulting oil spill. 

 The BOEMRE should analyze an alternative that includes the holding of all 

remaining scheduled lease sales for the entire Western and Central Planning Areas. 

 The IAGC believes that there should be no discrimination between areas within the 

Western and Central Planning Areas in regard to geophysical, leasing, drilling, and 

production activities based upon popular political goals or environmental opinions 

that cannot be substantiated. 

 The IAGC strongly recommends that the final Supplemental EIS clearly provide for 

and facilitate new geophysical data acquisition and subsequent analysis of the 

hydrocarbon production of the Western and Central Planning Areas. 

 In developing the Supplemental EIS, BOEMRE should only rely on the best 

available scientific information and knowledge. 

 The IAGC also encourages BOEMRE to consider the environmental and 

socioeconomic information gathered and analyzed, and the conclusions made as part 

of this process to be utilized in the Supplemental EIS to be developed for the next 5-

Year OCS Program. 

Stone Energy 

Lafayette, LA 

 Stone Energy recommends that BOEMRE incorporate consideration of all new 

regulations and requirements put in place post-Macondo. 

Consumer Energy 

Alliance 

Houston, TX 

 The BOEMRE should proceed with the Supplemental EIS in an expedited and 

efficient manner, and consider thoroughly the socioeconomic impacts of oil and gas 

development on coastal communities. 

National Oceanic and 

Atmospheric 

Administration, 

National Marine 

Fisheries Service 

St. Petersburg, FL 

 The BOEMRE should consider the understatement of frequency and magnitude of oil 

spills, understatement of potential environmental impacts of oil spills, the need to 

better evaluate the potential adverse impacts that a spill could have on the seafood 

industry and markets, the need to better evaluate modeling of spills, and the need to 

address cumulative impacts on wetlands. 

 The Supplemental EIS should provide an analysis of the potential social, economic, 

and environmental impacts of a major oil event to fish stocks and to commercial and 

recreational fisheries in the Gulf of Mexico. Additionally, the Supplemental EIS 

should include an analysis of the potential effects of a major spill event to seafood, 

including wild-caught finfish and shellfish and aquaculture products that are 

important components of the Nation’s food supply. These analyses should consider 

fishery closures, impacts to food safety, and contamination by hydrocarbon 

compounds and dispersants. 

 The Environmental Sensitivity Index used in past programs does not consider the 

sensitivity of marine habitats in the OCS to oil spills or other activities associated 

with oil and gas exploration, development, or production. The NOAA suggests that 

BOEMRE broaden the scope of its analysis to consider the impacts of all activities, 

including potential oil-spills and the use of chemical dispersants in any oil spill 

response efforts, to EFH and other vulnerable deepwater habitats such as deep-sea 

corals. The NOAA also suggests that BOEMRE evaluate the potential impacts to 

EFH for each life stage of each managed species, as well as impacts to other 

vulnerable habitats, from a worst-case scenario spill, including impacts to benthic 

and pelagic coastal and offshore habitats and prepare proposed mitigation 

requirements for such a spill. 

 The NOAA provided a list of 14 habitat areas of particular concern, which are 

designated within the Western and Central Planning Areas. 
A-112 Central Planning Area Supplemental EIS 

Table 5-1. Scoping Comments (continued). 

Name and Affiliation Concerns 

National Oceanic and 

Atmospheric 

Administration, 

National Marine 

Fisheries Service 

St. Petersburg, FL 

 The EFH section of the Supplemental EIS should reflect the current EFH 

identifications and descriptions by the Gulf of Mexico Fishery Management Council in 

2005 for Council-managed species and by NMFS for highly migratory species in 2009. 

 The NOAA recommends a recalculation of the likelihood of a major oil-spill event 

and an analysis of the effects from oil spills that utilize the flow rates and quantities 

identified in the “Oil Budget Calculator Deepwater Horizon Technical 

Documentation.” Additionally, the Supplemental EIS should reanalyze the effects of 

dispersant application and in-situ burning. 

 If the proposed activity may affect a listed species or designated critical habitat, 

BOEMRE must initiate consultation with NMFS pursuant to Section 7 of the ESA. 

 The NMFS would like to work with BOEMRE to enhance, refine, or develop new 

oil-spill analyses to improve the understanding of the effects of oil spills on listed 

species and to improve the Section 7 consultation. The NMFS recommends that spill 

probabilities and modeling of different sized spills, including catastrophic spills, be 

provided for sources of spills in offshore and nearshore environment and for surface 

and deepwater sources. The NMFS also asks BOEMRE to provide additional 

information regarding the relative risk of exploration and production wells leaking oil 

on the continental shelf versus those located on the continental slope and deepwater 

Gulf of Mexico. 

 The NOAA recommends that revised spill probabilities and modeling of different 

sized spills, including catastrophic spills for the Gulf of Mexico for sources of spills 

in offshore and nearshore environments be conducted. These models must include 

both surface and deepwater sources, as well as the effects of oil-spill response plans 

(e.g., dispersants) on the fate of the oil in the models. The Supplemental EIS should 

consider the variety and magnitude of effects associated with the chance of an oil 

spill taking listed species and adversely modifying or destroying critical habitat. 

 Please describe any changes to the proposed action resulting from the Deepwater 

Horizon event, including safety, spill contingency planning, spill response, and 

restoration actions. Also include any new programs and safeguards to reduce the 

likelihood of spills occurring in the future and provide an analysis of any new 

information and the potential for impacts to occur on listed species and critical 

habitat. 

 The Supplemental EIS should define the proposed lease sale areas, air permit 

requirements, and types of operations that fall under the jurisdictions of both 

BOEMRE and USEPA. The USEPA may be included as a co-agency in the 

biological opinion for air emissions for lease areas under their jurisdiction and should 

be included in any such request for ESA consultation. 

 The NMFS recommends that BOEMRE conduct a study to better understand the 

cumulative effects of noise from oil and gas construction and development activities 

on the OCS. This recommendation includes characterizing all aspects of noiseproducing construction and operation activities such as pile driving during well 

construction and platform installation, and other common OCS activities. Major 

noise-producing activities (>120 dB re 1 μParms) should be identified, and 

measurements of noise from these activities should be reported in appropriate units of 

measurement to estimate the acoustic footprint on the environment, duration, 

frequency, and relative contribution to ambient noise levels in the Gulf of Mexico. 

 The BOEMRE should consider a data collection program for the protected species 

observer program in coordination with NMFS, and include the program in the 

Supplemental EIS as appropriate. 
Figures and Tables A-113 

Table 5-1. Scoping Comments (continued). 

Name and Affiliation Concerns 

National Oceanic and 

Atmospheric 

Administration, 

National Marine 

Fisheries Service 

St. Petersburg, FL 

 Pipeline construction may affect habitats important to listed species and should be 

considered in the Supplemental EIS. 

 The BOEMRE should continue to work with NMFS and the Offshore Operators 

Committee to provide informational materials to the offshore oil and gas workers, 

require annual training, and continue to develop best management practices to reduce 

the release of debris into the marine environment. The BOEMRE should work with 

NMFS to update the Marine Debris Notice to Lessees (NTL) 2003-G11 and apply 

this to other geographic areas/regions as appropriate. 

 The NOAA recommends that the Vessel Strike Avoidance Measures and Reporting 

for Mariners be applied throughout approved lease areas. 

 The Supplemental EIS should characterize all noise sources with source levels above 

120 dB re 1 μParms as the potential to affect marine mammals and other listed species. 

 Many general impacts associated with the construction and operation of oil and gas 

structures should be considered in the Supplemental EIS. Habitat alterations to water 

quality may result from accidental spills, turbidity during terminal an pipeline 

construction, wastewater discharges, and warming water outflow. Habitat effects 

may also occur from propeller wash, benthic impacts from pipeline and terminal 

construction, and discharges of marine debris. 

 In the event that any aspect of a proposed oil and gas operation will result in a “take,” 

the oil and gas applicant, or the lead agency acting on behalf of the applicant, would 

be required to obtain an incidental take authorization from NOAA. 

 The NOAA had two primary comments on the Supplemental EIS related to national 

marine sanctuaries: (1) NOAA requests that BOEMRE review the designation of all 

No-Activity Zones associated with all of the topographic features in the Central and 

Western Planning Area, and re-establish these areas based on current bathymetric and 

biological data; and (2) NOAA requests that BOEMRE require the shunting of 

material from all wells drilled within the specified buffer zones around the NoActivity Zones. 

 As BOEMRE considers scoping for the Supplemental EIS, BOEMRE should 

consider the following issues: (1) potential and cumulative impacts on the 

mesophotic and deep-sea communities during the development of oil and gas 

resources; (2) potential and cumulative impacts on mesophotic and deep-sea coral 

communities in the siting of undersea pipelines; (3) potential and cumulative impacts 

on mesophotic and deep-sea coral communities in the event of a major spill; recent 

findings from research conducted to assess impacts from the Deepwater Horizon spill 

on deep-sea coral communities should be helpful in considering these impacts; (4) 

potential and cumulative impacts on shallow coral reef, mesophotic and deep-sea 

coral communities connected by prevailing ocean currents to the lease sites; and (5) 

potential and cumulative socioeconomic impacts to communities dependent on 

recreational and commercial fishing in the lease areas, as well as communities 

dependent on coastal and ocean tourism and fishing in places connected by prevailing 

ocean currents. 
A-114 Central Planning Area Supplemental EIS 

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APPENDIX B 

 

CATASTROPHIC SPILL EVENT ANALYSIS
Catastrophic Spill Event Analysis B-3 

APPENDIX B. CATASTROPHIC SPILL EVENT ANALYSIS 

1. INTRODUCTION 

In 1986, the Council on Environmental Quality (CEQ) regulations were amended to rescind the 

requirement to prepare a “worst-case analysis” for an Environmental Impact Statement (EIS). See 40 

C.F.R. § 1502.22(b)(4). The regulation, as amended, states that catastrophic, low-probability impacts 

must be analyzed if the analysis is “supported by credible scientific evidence, is not based on pure 

conjecture, and is within the rule of reason.” 

The August 16, 2010, CEQ report, prepared following the Deepwater Horizon blowout and spill in 

the Gulf of Mexico (CEQ, 2010), recommended that the Bureau of Ocean Energy Management, 

Regulation and Enforcement (BOEMRE), formerly the Minerals Management Service (MMS), should 

“ensure that NEPA documents provide decisionmakers with a robust analysis of reasonably foreseeable 

impacts, including an analysis of reasonably foreseeable impacts associated with low probability 

catastrophic spills for oil and gas activities on the Outer Continental Shelf” (CEQ, 2010). This Analysis 

provides that robust analysis of the impacts of low-probability catastrophic spills for all applicable 

decisionmakers including, but not limited to, the Secretary of the Department of the Interior (USDOI) for 

the National 5-Year Program, the Assistant Secretary of Land Management for an oil and gas lease sale, 

or the Regional Supervisor of the Office of Field Operations for an exploration or development plan. 

1.1. WHAT IS A CATASTROPHIC EVENT? 

As applicable to NEPA, Eccleston (2008) defines a catastrophic event as “large-scale damage 

involving destruction of species, ecosystems, infrastructure, or property with long-term effects, and/or 

major loss of human life.” For oil and gas activities on the Outer Continental Shelf (OCS), a catastrophic 

event is a high-volume, long-duration oil spill regardless of the cause, whether natural disaster (i.e., 

hurricane) or manmade (i.e., human error and terrorism). This high-volume, long-duration oil spill, or 

catastrophic spill, has been further defined by the National Oil and Hazardous Substances Pollution 

Contingency Plan as a “spill of national significance” or “a spill which due to its severity, size, location, 

actual or potential impact on the public health and welfare or the environment, or the necessary response 

effort, is so complex that it requires extraordinary coordination of federal, state, local, and responsible 

party resources to contain and cleanup the discharge” (40 C.F.R. Part 300, Appendix E). 

Each oil-spill event is unique; its outcome depends on several factors, including time of year and 

location of release relative to winds, currents, land, and sensitive resources, specifics of the well (i.e., 

flow rates, hydrocarbon characteristics, and infrastructure damage), and response (i.e., speed and 

effectiveness). For this reason, the severity of an oil spill cannot be predicted based on volume alone, 

although a minimum volume of oil must be spilled to reach catastrophic impacts. 

Though large spills may result from a pipeline rupture, this likely will not result in a catastrophic spill 

because the ability to detect leaks and shut off pipelines limits the spill to the contents of the pipeline. The 

largest, non-blowout-related spill on the Gulf of Mexico OCS occurred in 1967, a result of internal 

pipeline corrosion caused by anchor damage. In 13 days, 160,638 barrels of oil leaked (USDOI, 

BOEMRE, 2010a); however, no significant environmental impacts were recorded as a result of this spill. 

Loss of well control creates the volume and duration that produces a catastrophic oil spill. Although 

loss of well control is defined as the uncontrolled flow of a reservoir fluid that may result in the release of 

gas, condensate, oil, drilling fluids, sand, or water, it is a broad term that includes very minor well control 

incidents as well as the most severe well control incidents. Historically, loss of well control incidents 

occurred during development drilling operations, but loss of well control incidents can occur during 

exploratory drilling, production, well completions, or workover operations. These losses of well control 

incidents may occur between zones in the wellbore or at the seafloor. 

Blowouts are a more severe loss of well subset with that create a greater risk of an oil spill and human 

injury. Two blowouts that resulted in catastrophic spills have occurred in U.S. and Mexican waters of the 

Gulf of Mexico. In 1979, the Ixtoc blowout in shallow water (164 feet [ft] 50 miles (mi) offshore in the 

Bay of Campeche, Mexico), spilled 3.5 million barrels of oil spilled in 10 months (USDOC, NOAA, 

Office of Response and Restoration, 2010a; USDOC, NOAA, Hazardous Materials Response and 

Assessment Division, 1992; ERCO, 1982). In 2010, the Deepwater Horizon blowout, in deepwater 
B-4 Central Planning Area Supplemental EIS 

(4,992 ft) 48 mi offshore in Mississippi Canyon Block 252, spilled an estimated 4.9 million barrels of oil 

until it was capped almost 3 months later. 

Prior to the Deepwater Horizon incident, the two largest spills in U.S. waters of the Gulf of Mexico 

OCS resulting from a loss of well control occurred in 1970 and released 30,000 and 53,000 barrels of oil 

(USDOI, BOEMRE, 2010a). These incidents resulted in four human fatalities. Although only 8-14 miles 

from shore, there was minor shoreline contact (USDOC, NOAA, Office of Response and Restoration, 

2010b and 2010c). In 1987, a blowout of the Mexican exploratory oil well, YUM II, resulted in a spill of 

58,640 barrels and 75 miles of impacted shoreline (USDOC, NOAA, Hazardous Materials Response and 

Assessment Division, 1992). None of these spills met the definition of a catastrophic event or spill. 

For this reason, only the Ixtoc and Deepwater Horizon blowouts and spills are analyzed below. 

1.2. METHODOLOGY

Two general approaches are utilized to analyze a catastrophic event under NEPA. The first approach 

is a bounding analysis for each individual resource category (e.g., marine mammals, sea turtles, etc.). This 

requires selecting a different set of factors and scenarios for each resource affected by a worst-case 

analysis. The second approach selects a single set of key circumstances that, in combination, result in 

catastrophic consequences. This creates a site-specific analysis with limited usefulness in future NEPA 

documents and consultations. Accordingly, this analysis combines the two approaches, relying on a 

generalized scenario while identifying site-specific severity factors for individual resources. This 

combined approach allows for the scientific investigation of a range of possible, although not necessarily 

probable, consequences of a catastrophic blowout and oil spill in the Gulf of Mexico. 

1.2.1. Geographic Scope 

Because the Gulf of Mexico is a semi-enclosed basin with an extensive history of oil and gas 

activities and with unique environmental conditions and hydrocarbon reservoir properties, this analysis is 

applicable to the Gulf of Mexico OCS only. It is not intended for other OCS regions. 

When possible, this analysis distinguishes between shallow water (<1,000 feet) and deep water 

(1,000 feet). 

1.2.2. Impact-Producing Factors and Scenario 

A hypothetical, yet feasible, scenario was developed to provide a framework for identifying the 

impacts of an extended oil spill from an uncontrolled blowout in both shallow and deep water. Unless 

noted, this scenario is based on the larger magnitude, blowout-related oil spills that have occurred in the 

Gulf of Mexico, discussed in Section 1.1. As noted above, because each spill event is unique, its outcome 

depends on many factors. Therefore, this scenario cannot predict the outcome of present or future spills. 

1.2.3. Environmental and Socioeconomic Impacts 

This analysis evaluates the impacts to the Gulf of Mexico’s coastal, marine, environmental, and 

socioeconomic resources from a catastrophic blowout, oil spill and its associated cleanup activities. 

Although the most recent EIS’s prepared by MMS for oil and gas lease sales in the Gulf of Mexico 

analyze the potential impacts from smaller oil spills that are more reasonably foreseeable (USDOI, MMS, 

2007 and 2008), the analysis below focuses on the most likely and most significant impacts created by a 

high-volume, extended-duration spill. Because catastrophic consequences may not occur for all resources, 

factors affecting the severity of impacts are identified by individual resource. 

1.3. HOW TO USE THIS ANALYSIS

The purpose of this technical analysis is to assist BOEMRE in meeting CEQ requirements (40 C.F.R. 

§ 1502.22) for analysis of catastrophic, low-probability impacts if the analysis is “supported by credible 

scientific evidence, is not based on pure conjecture, and is within the rule of reason.” Therefore, this 

analysis identifies the most likely and most significant impacts from a high-volume blowout and oil spill 

that continues for an extended period of time. The scenario and impacts discussed in this analysis should 
Catastrophic Spill Event Analysis B-5 

not be confused with the scenario and impacts anticipated to result from routine activities or more 

reasonably foreseeable accidental events of a proposed action. 

This technical analysis is designed to be incorporated by reference in future NEPA documents and 

consultations. Therefore, factors that affect the severity of impacts of a high-volume, extended-duration 

spill are highlighted throughout the analysis for use in subsequent site-specific analyses. 

To analyze a hypothetical catastrophic event in an area such as the Gulf of Mexico, several 

assumptions and generalizations were made. However, future project-specific analyses should also 

consider specific details such as potential flow rates for the specific proposed activity, the properties of 

the targeted reservoir, and distance to shore of the proposed activities. 

The life cycle of a catastrophic blowout and spill is divided into four geographic areas and/or time 

periods, some of which may overlap: 

 Phase 1: Initial event (Section 2) 

 Phase 2: Offshore spill (Section 3) 

 Phase 3: Onshore contact (Section 4) 

 Phase 4: Post-spill, long-term recovery (Section 5) 

Each phase of a catastrophic oil spill is addressed in this analysis. For each phase, the scenario is 

described, factors that could produce environmental impacts are listed, and the most likely and most 

significant impacts are discussed. 

2. INITIAL EVENT (PHASE 1) 

While most of the environmental and socioeconomic impacts of a catastrophic blowout would occur 

during the ensuing high-volume, extended-duration spill (see Sections 3, 4, and 5), it is important to 

acknowledge the deadly events that could occur in the initial phase of a catastrophic blowout. The 

following scenario was developed to provide a framework for identifying the most likely and most 

significant impacts during the initial phase. 

2.1. IMPACT-PRODUCING FACTORS AND SCENARIO

Phase 1 of the scenario is the initial incident of a catastrophic blowout. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. While there are several points where a 

blowout could occur, four major distinctions that are important to the analysis of impacts are described in 

Table 1 below. 

For this analysis, an explosion and subsequent fire are assumed to occur. If a blowout associated with 

the drilling of a single exploratory well occurs, this could result in a fire that would burn for 1 or 2 days. 

If a blowout occurs on a production platform, other wells could feed the fire, allowing it to burn for over a 

month (USDOC, NOAA, Office of Response and Restoration, 2010c). The drilling rig or platform may 

sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. For example, the Deepwater Horizon drilling rig sank, landing 1,500 feet away on the 

seafloor. Regardless of water depth, the immediate response would be from search and rescue vessels and 

aircraft, such as United States Coast Guard (USCG) cutters, helicopters, and rescue planes, and 

firefighting vessels. 
B-6 Central Planning Area Supplemental EIS 

Table 1 

 

Blowout Scenarios and Key Differences 

in Impacts, Response, and/or Intervention 

Location of Blowout 

and Leak 

Key Differences in Impacts, Response, 

and/or Intervention 

Blowout occurs at the sea 

surface (i.e., at the rig) 

Offers the least chance for oil recovery due to the restricted access to the release 

point; therefore, greater impacts to coastal ecosystems. In addition to relief wells, 

there is potential for other intervention measures such as capping and possible 

manual activation of Blow-Out-Preventer (BOP) rams. 

Blowout occurs along the riser 

anywhere from the seafloor to 

the sea surface. However, a 

severed riser would likely 

collapse, resulting in a leak at 

the seafloor. 

In deep water, the use of subsea dispersants may reduce impacts to coastal 

ecosystems; however, their use may increase exposure of marine resources to oil. 

There is a possibility for limited recovery of oil at the source. In addition to relief 

wells, there is potential for other intervention measures, such as capping and 

possible manual activation of BOP rams. 

At the seafloor, through leak 

paths on the BOP/wellhead 

In deep water, the use of subsea dispersants may reduce impacts to coastal 

ecosystems; however, their use may increase exposure of deepwater marine 

resources to dispersed oil. 

With an intact subsea BOP, intervention may involve the use of drilling mud to 

kill the well. If the BOP and well stack are heavily compromised, the only 

intervention method may be relief wells. Greatest possibility for recovery of oil 

at the source, until the well is capped or killed. 

Below the seafloor, outside the 

wellbore (i.e., broached) 

Disturbance of a large amount of sediments resulting in the burial of benthic 

resources in the immediate vicinity of the blowout. The use of subsea dispersants 

would likely be more difficult (PCCI, 1999). Stopping this kind of blowout 

would probably involve relief wells. Any recovery of oil at the seabed would be 

very difficult. 

2.2. MOST LIKELY AND MOST SIGNIFICANT IMPACTS

Impacts during Phase 1 would be limited to environmental resources in the immediate vicinity of the 

blowout. The most recent EIS’s prepared by MMS for oil and gas lease sales in the Gulf of Mexico detail 

the potential impacts from reasonably foreseeable blowouts (USDOI, MMS, 2007 and 2008). In addition 

to the impacts described in those documents, the most likely and most significant impacts resulting from a 

catastrophic blowout outside the wellbore are described below. 

2.2.1. Physical Resources 

2.2.1.1. Air Quality 

A catastrophic blowout close to the water surface would initially emit large amounts of methane and 

other gases into the atmosphere. If high concentrations of sulfur are present in the produced gas, hydrogen 

sulfide (H2S) could present a hazard to personnel. The natural gas H2S concentrations in the Gulf of 

Mexico OCS are generally low; however, there are areas such as the Norphlet formation in the 

northeastern Gulf of Mexico, for example, that contain levels of H2S up to 9 percent. Ignition of the 

blowout gas and subsequent fire would result in emissions of nitrogen oxides (NOx), sulfur oxides (SOx), 

carbon monoxide (CO), volatile organic compounds (VOC’s), particulate matter (PM10), and fine 

particulate matter (PM2.5). The fire could also produce polycyclic aromatic hydrocarbons (PAH’s), which 

are known to be hazardous to human health. The pollutant concentrations would decrease with downwind 

distance. A large plume of black smoke would be visible at the source and may extend a considerable 

distance downwind. However, with increasing distance from the fire, the gaseous pollutants would 
Catastrophic Spill Event Analysis B-7 

undergo chemical reactions, resulting in the formation of fine particulate matter (PM2.5) that includes 

nitrates, sulfates, and organic matter. The PM2.5 concentrations in the plume would have the potential to 

temporarily degrade visibility in any affected Prevention of Significant Deterioration (PSD) Class I areas 

(i.e., National Wilderness Areas and National Parks) and other areas where visibility is of significant 

value.

2.2.1.2. Offshore Water Quality 

During the initial phase of a catastrophic blowout, water quality impacts include disturbance of 

sediments and release and suspension of oil and natural gas (methane) into the water column. These 

potential impacts are discussed below. As this section deals with the immediate effects of a blowout that 

would be located at least 3 nautical mi from shore, it is assumed that there would be no impacts on coastal 

water quality during this initial stage. 

Disturbance of Sediments 

A catastrophic blowout below the seafloor, outside the wellbore (Table 1) has the potential to 

resuspend sediments and disperse potentially large quantities of bottom sediments. Some sediment could 

travel several kilometers, depending on particle size and subsea current patterns. In the deep Gulf of 

Mexico, surficial sediments are mostly composed of silt and clay, and, if resuspended, could stay in the 

water column for several hours to even days. Bottom currents in the deep Gulf of Mexico have been 

measured to reach 30 centimeters/second (cm/sec) with mean flows of 1.5-2.5 cm/sec (Hamilton, 1990). 

At these mean flow rates, resuspended sediment could be transported 1.3-2.1 kilometers/day. Sediment 

resuspension can lead to a temporary change in the oxidation-reduction chemistry in the water column, 

including a localized and temporal release of any formally sorbed metals, as well as nutrient recycling 

(Caetano et al., 2003; Fanning et al., 1982). Sediments also have the potential to become contaminated 

with oil components. 

A subsea release also has the potential to destabilize the sediments and create slumping or larger scale 

sediment movements along depth gradients. These types of events would have the potential to move 

and/or damage any infrastructure in the affected area. 

Release and Suspension of Oil into the Water Column 

As the Deepwater Horizon incident showed, a subsea release of hydrocarbons at a high flow rate has 

the potential to disperse and suspend oil droplets (chemically dispersed or otherwise) within the water 

column and to induce large patches of sheen and oil on the surface. These dispersed hydrocarbons may 

adsorb onto marine detritus (marine snow) or may be mixed with drilling mud and deposited near the 

source. Mitigation efforts such as burning may introduce hydrocarbon byproducts into the marine 

environment, which would be distributed by surface currents. The acute and chronic sublethal effects of 

these dilute suspended “plumes” are not well understood and require future research efforts. 

Large amounts of oil put into offshore water may alter the chemistry of the sea with unforeseeable 

results. The VOCs, including benzene, can have acutely toxic effects. The components of crude oil that 

are water soluble are more available than some of the heavier components to exert a toxic effect on 

marine life. The PAHs are present in crude oil and include carcinogenic compounds and compounds that 

pose various risks to marine organisms and possibly to the higher trophic level species, including humans 

that feed on these organisms. The PAHs are also persistent in the environment. Impacts from the 

subsequent extended oil spill on offshore water quality are discussed further in Section 3.2.1.2. 

Release of Natural Gas (Methane) into the Water Column 

A catastrophic blowout could release natural gas into the water column; the amount of gas released is 

dependent upon the water depth, the natural gas content of the formation being drilled, and its pressure. 

Methane is the primary component of natural gas (NaturalGas.org, 2010). Methane may stay in the 

marine environment for long periods of time (Patin, 1999; p. 237), as methane is highly soluble in 

seawater at the high pressures and cold temperatures found in deepwater environments (NRC, 2003; p. 

108). However, methane diffusing through the water column would likely be oxidized in the aerobic zone 
B-8 Central Planning Area Supplemental EIS 

and would rarely reach the air-water interface (Mechalas, 1974; p. 23). In addition to methane, natural 

gas contains smaller percentages of other gases such as ethane and propane. It may also contain VOCs 

(including benzene, toluene, ethylbenzene, and xylene) and H2S, which have individual toxic 

characteristics. Methane and other natural gas constituents are carbon sources, and their introduction into 

the marine environment could result in reducing the dissolved oxygen levels due to microbial degradation 

of the methane potentially creating hypoxic or “dead” zones. Depletion of dissolved oxygen in the Gulf of 

Mexico due to the release of natural gas from the Macondo well (Deepwater Horizon incident) is 

currently being examined as a result of the Deepwater Horizon incident (Schenkman, 2010). 

Unfortunately, little is known about methane toxicity in the marine environment, but there is concern as to 

how methane in the water column might affect fish (see Section 3.2.2.2). 

2.2.2. Biological Resources 

Impacts during the initial event would be limited to environmental resources in the immediate vicinity 

of the blowout as described below. 

2.2.2.1. Marine and Migratory Birds 

Many migratory birds use offshore platforms or rigs as rest sites during migration (Russell, 2005). In 

addition, seabirds are attracted to offshore platforms and rigs (Tasker et al., 1986; Weise et al., 2001). The 

numbers of birds present at a platform or rig are greater when platforms or rigs are closer to shore during 

drilling operations (Baird, 1990). Birds resting on the drilling rig or platform during a catastrophic 

blowout are likely to be killed by an explosion. While it is assumed that most birds in trans-Gulf 

migration would likely avoid the fire and smoke plume during the day, it is conceivable that the light 

from the fire could interfere with nocturnal migration, especially during poor visibility conditions. It has 

been documented that seabirds are attracted to natural gas flares at rigs and platforms (Russell, 2005; 

Wiese et al., 2001); therefore, additional bird fatalities could result from the fire following the blowout. 

Though different species migrate throughout the year, the largest number of species migrates from March 

through November. A blowout during this time would cause a greater number of bird fatalities. While the 

number and species of birds killed depends on the blowout location and time of year, these initial 

fatalities would likely not result in population-level impacts for species present at the time of the blowout 

and resulting fire (Russell, 2005: Table 6.12). 

2.2.2.2. Fish, Fisheries, and Essential Fish Habitat 

Depending on the type of blowout and the proximity of marine life to it (Table 1), an eruption of 

gases and fluids may generate not only a toxic effect but also pressure waves and noise significant enough 

to injure or kill local biota. Within a few thousand meters of the blowout, resuspended sediments may 

clog fish gills and interfere with respiration. Settlement of resuspended sediments may, in turn, smother 

invertebrates or interfere with their respiration. Offshore benthic habitats that support fisheries could also 

be impacted, as discussed below. 

2.2.2.3. Marine Mammals 

Depending on the type of blowout, the pressure waves and noise generated by the eruption of gases 

and fluids would likely be significant enough to harass, injure, or kill marine mammals, depending on the 

proximity of the animal to the blowout. A high concentration of response vessels could result in 

harassment or displacement of individuals and could place marine mammals at a greater risk of vessel 

collisions, which would likely cause fatal injuries. 

In addition to the above, the presence of hydrocarbons and other materials generated from a spill 

through which marine mammals swim may result in direct harm by clogging blowholes, etc. 

2.2.2.4. Sea Turtles 

Five species of sea turtles are found in the waters of the Gulf of Mexico: green, leatherback, 

hawksbill, Kemp’s ridley, and loggerhead. All species are protected under the Endangered Species Act 
Catastrophic Spill Event Analysis B-9 

(ESA), and all are listed as endangered except the loggerhead turtle, which is listed as threatened. 

Depending on the type of blowout (Table 1), an eruption of gases and fluids may generate significant 

pressure waves and noise that may harass, injure, or kill sea turtles, depending on their proximity to the 

accident. A high concentration of response vessels could place sea turtles at a greater risk of fatal injuries 

from vessel collisions. 

Further, mitigation by burning puts turtles at risk because they tend to be gathered up in the corralling 

process necessary to concentrate the oil in preparation for the burning. Trained observers should be 

required during any mitigation efforts that include burning. 

2.2.2.5. Offshore Benthic Habitats 

Gulf of Mexico benthic resources are divided into shelf habitats and deepwater habitats. Shelf habitats 

of the Gulf of Mexico include soft-bottom habitats (sandy and muddy substrate) and hard-bottom habitats 

(rock or salt outcroppings that provide habitat for encrusting organisms). Deepwater benthic communities 

of the Gulf of Mexico include soft-bottom, coral, and chemosynthetic habitats. The impacts to these 

benthic communities depend on the location and the type of catastrophic blowout that occurs. 

Introduction 

Sediment disturbance as a result of the blowout above the seafloor would not occur. A catastrophic 

blowout that occurs above the seabed (at the rig, along the riser between the seafloor and sea surface, or 

through leak paths on the BOP/wellhead) would result in released oil rising to the sea surface. However, 

if the leak is deep in the water column and the oil is ejected under pressure, oil droplets may become 

entrained deep in the water column. The upward movement of the oil may be reduced if methane in the 

oil is dissolved at the high underwater pressures, reducing the oil’s buoyancy (Adcroft et al., 2010). The 

large oil droplets will rise to the sea surface, but the smaller droplets, formed by vigorous turbulence in 

the plume or the injection of dispersants, may remain neutrally buoyant in the water column, creating a 

subsurface plume (Adcroft et al., 2010). Oil droplets less than 100 micrometers in diameter may remain in 

the water column for several months (JAG, 2010) where they will not be in contact with benthic habitats; 

similarly, large oil drops on the sea surface will not be in contact with benthos. However, oil in the water 

column or at the sea surface may sometimes sink, contact benthos, and have impacts, as discussed below. 

As discussed below, a catastrophic blowout outside the well casing and below the seafloor or at the 

seafloor water interface could resuspend large quantities of bottom sediments and create a large crater, 

destroying many organisms within a few hundred meters of the wellhead. Some of the sediment could 

travel up to a few thousand meters before redeposition, negatively impacting a localized area of benthic 

communities. 

The use of subsea dispersants would increase the exposure of offshore benthic habitats to dispersed 

oil droplets in the water column, as well as the chemicals used in the dispersants. The use of subsea 

dispersants is not likely to occur for seafloor blowouts outside the well casing. 

Soft-Bottom Shelf Habitats 

The vast majority of the Gulf of Mexico seabed is comprised of soft sediments. Microbes to 

metazoans (e.g., polychaete worms and crabs) inhabit the soft-bottom benthos, many forming the base of 

the food chain for several species. When soft-bottom infaunal communities are physically impacted by a 

blowout (either lost to the crater formation or smothered by sediment), recolonization by populations 

from neighboring soft-bottom substrate is expected within a relatively short period of time. Many of the 

organisms on soft bottoms live within the sediment and have the ability to migrate upward in response to 

burial by sedimentation. A blowout that occurs outside the well casing can rapidly deposit 30 cm (12 

inches) or more of sediment within a few hundred meters and may smother much of the soft-bottom 

community in a localized area. In situations where soft-bottom infaunal communities are negatively 

impacted, recolonization by populations from neighboring soft-bottom substrate would be expected over a 

relatively short period of time for all size ranges of organisms, in a matter of days for bacteria, and 

probably less than 1 year for most macrofauna and megafauna species. Recolonization could take longer 

for areas affected by direct contact of concentrated oil. Initial repopulation from nearby stocks of 

pioneering species, such as tube-dwelling polychaetes or oligochaetes, may begin with the next 
B-10 Central Planning Area Supplemental EIS 

recruitment event (Rhodes and Germano, 1982). Full recovery would follow as later stages of 

successional communities overtake the pioneering species (Rhodes and Germano, 1982). The time it takes 

to reach a climax community may vary depending on the species and degree of impact. Full benthic 

community recovery may take years to decades if the benthic habitat is heavily oiled (Gesteira and 

Dauvin, 2000; Sanders et al., 1980; Conan, 1982). A slow recovery rate will result in a community with 

reduced biological diversity and possibly a lesser food value for predatory species. 

Hard-Bottom Shelf Habitats 

The Gulf of Mexico shelf has several hard-bottom features upon which encrusting and epibenthic 

organisms attach. Though there are varying degrees of relief on the hard bottom, the impacts from a 

catastrophic blowout are similar for the banks of varying relief because similar organisms occur on these 

features. Thus, they are discussed as a single grouping under “hard-bottom communities,” with references 

to specific communities where impacts may differ. 

Topographic features are isolated areas of moderate to high relief that provide habitat for hard-bottom 

communities of high biomass and moderate diversity. These features provide shelter and food for large 

numbers of commercially and recreationally important fish. There are 37 named topographic features in 

the Gulf of Mexico with specific BOEMRE protections, including the Flower Garden Banks National 

Marine Sanctuary. The BOEMRE has created “No Activity Zones” around topographic features in order 

to protect these habitats from disruption due to oil and gas activities. A “No Activity Zone” is a protective 

perimeter drawn around each feature that is associated with a specific isobath (depth contour) surrounding 

the feature in which structures, drilling rigs, pipelines, and anchoring are not allowed. These “No Activity 

Zones” are areas where activity is prohibited based on BOEMRE policy. Notice to Lessees and Operators 

(NTL) 2009-G39 recommends that drilling should not occur within 152 meters ([m]; 500 ft) of a “No 

Activity Zone” of a topographic feature. 

The northeastern portion of the central Gulf of Mexico is a region of low to moderate relief known as 

the “Pinnacle Trend” at the outer edge of the Mississippi-Alabama shelf between the Mississippi River 

and De Soto Canyon. These outcrops provide hard substrate for sessile invertebrate attachment that 

attracts fish. The NTL 2009-G39 recommends that no bottom-disturbing activities occur within 30 m (100 

ft) of any hard bottoms/pinnacles with a relief of 8 ft or greater. 

Potentially sensitive biological features are features that have moderate to high relief (8 feet or 

higher), provide hard surface for sessile invertebrates, attract fish, but are not located within Pinnacledesignated blocks or the “No Activity Zone” of topographic features. No bottom-disturbing activities that 

may cause impact to these features are permitted. 

Impacts that occur to hard-bottom shelf habitats as a result of a blowout would depend on the type of 

blowout, distance from the blowout, relief of the biological feature, and surrounding physical 

characteristics of the environment (e.g., turbidity). The NTL 2009-G39 recommends the use of buffers to 

prevent blowouts in the immediate vicinity of a hard-bottom habitat or its associated biota. Much of the 

oil released from a blowout would rise to the sea surface, therefore minimizing the impact to benthic 

communities by direct oil exposure. However, small droplets of oil that are entrained in the water column 

for extended periods of time may migrate into “No Activity Zones.” Although these small oil droplets 

will not sink themselves, they may attach to suspended particles in the water column and then be 

deposited on the seafloor (McAuliffe et al., 1975). These long-term impacts, such as reduced recruitment 

success, reduced growth, and reduced coral cover, as a result of impaired recruitment, are discussed in 

Section 3.2.2.6. Also, if the blowout were to occur beneath the seabed, suspension and subsequent 

deposition of disturbed sediment may smother localized areas of benthic communities, possibly including 

organisms within No Activity Zones or other hard-bottom substrate. 

Benthic communities on a hard-bottom feature exposed to large amounts of resuspended and 

deposited sediments following a catastrophic, subsurface blowout could be subject to sediment 

suffocation, exposure to resuspended toxic contaminants, and reduced light availability. Impacts to corals 

as a result of sedimentation would vary based on coral species, the height to which the coral grows, 

degree of sedimentation, length of exposure, burial depth, and the coral’s ability to clear the sediment. 

Impacts may range from sublethal effects such as reduced growth, alteration in form, and reduced 

recruitment and productivity to slower growth to death (Rogers, 1990). 
Catastrophic Spill Event Analysis B-11 

The initial blowout impact would be greatest to communities located in clear waters that experience 

heavy sedimentation. Reef-building corals are sensitive to turbidity and may be killed by heavy 

sedimentation (Rogers, 1990; Rice and Hunter, 1992). However, it is unlikely that reef-building corals 

would experience heavy sedimentation as a result of a blowout because drilling activity would not be 

allowed near sensitive organisms in the “No Activity Zones,” based on the NTL 2009-G39. The most 

sensitive organisms are also typically elevated above soft sediments, making them less likely to be buried. 

It is possible, however, for potentially sensitive biological features outside of “No Activity Zones” or 

Pinnacle-designated blocks to experience some turbidity or sedimentation impacts. Corals may also 

experience discoloration or bleaching as a result of sediment exposure, although recovery from such 

exposure may occur within 1 month (Wesseling et al., 1999). 

Initial impacts would be much less extreme in a turbid environment (Rogers, 1990). For example, the 

Pinnacle Trend community exists in a relatively turbid environment, starting just 65 kilometers ([k]; 40 

mi) east of the mouth of the Mississippi River and trending to the northeast. Sediment from a blowout, if 

it occurred nearby, may have a reduced impact on these communities compared with an open-water reef 

community, as these organisms are more tolerant of suspended sediment (Gittings et al., 1992). Many of 

the organisms that predominate in this community also grow tall enough to withstand the sedimentation 

that results from their turbid environment or they have flexible structures that enable the passive removal 

of sediments (Gittings et al., 1992). 

A portion or the entire rig may sink to the seafloor as a result of a blowout. The benthic communities 

(hard- or soft-bottom communities) on the seafloor upon which the rig settles would be destroyed or 

smothered. A settling rig may suspend sediments, which may smother nearby benthic communities as the 

sediment is redeposited on the seafloor. The habitats beneath the rig may be permanently lost; however, 

the rig itself may become an artificial reef upon which epibenthic organisms may settle. The surrounding 

benthic communities that were smothered by sediment would repopulate from nearby stocks through 

spawning recruitment and immigration. 

Deepwater Habitats 

The effects of a catastrophic blowout event on Gulf of Mexico benthic resources in deep water 

(>1,000 ft; 300 m) are similar to those on the shelf communities. The main factors are the type of blowout 

and the proximity to the habitat. Known deepwater communities include soft bottoms and two types of 

hard-bottom communities: chemosynthetic communities and deep coral communities. Many of the 

organisms on soft bottoms live within the sediment and have the ability to migrate upward in response to 

burial by sedimentation. A blowout that occurs outside the well casing can rapidly deposit 30 cm (12 

inches) or more of sediment within a few hundred meters and may smother much of the soft-bottom 

community in a localized area. In situations where soft-bottom infaunal communities are negatively 

impacted, recolonization by populations from neighboring soft-bottom substrate would be expected over a 

relatively short period of time for all size ranges of organisms, in a matter of days for bacteria, and 

probably less than 1 year for most macrofauna and megafauna species. Recolonization could take longer 

for areas affected by direct contact of concentrated oil. 

BOEMRE restrictions applicable to work near deepwater hard-bottom areas (as described in NTL 

2009-G40) would prevent direct negative effects from a seafloor blowout. The established policy 

prohibits location of wells within 2,000 ft (610 m) of a suspected hard-bottom habitat. Geophysical 

analyses have achieved a high degree of reliability in detecting the potential presence of hard-bottom 

communities in the Gulf of Mexico. In rare instances, the subtle geophysical signatures of hydrocarbon 

seepage, conducive to the development of a chemosynthetic deepwater community development at the 

seabed that are a probable indicator of a community are not discovered during routine environmental 

analysis. Therefore, it is possible that a well could be drilled close enough for a hard-bottom community 

to be damaged in the event of a catastrophic blowout. 

Blowouts at points above the seafloor (in the riser or on the drill platform) would have little 

immediate effect on deepwater seafloor communities unless the structure sinks and physically impacts the 

seafloor. If a structure sank directly on a hard-bottom community, at least 2,000 ft (610 m) from the well, 

organisms could be crushed and smothered. 
B-12 Central Planning Area Supplemental EIS 

2.2.3. Socioeconomic Resources 

2.2.3.1. Offshore Archaeological Resources 

BOEMRE protects all known, discovered, and potentially historic and prehistoric archaeological 

resources on the OCS by requiring appropriate avoidance criteria as well as directives to investigate these 

resources. 

Onshore archaeological resources, prehistoric and historic sites, would not be immediately impacted 

during the initial phase of a catastrophic blowout because the distance of a blowout site from shore is at 

least 3 nautical miles. However, offshore catastrophic blowouts, when compared with spills of lesser 

magnitude, may initially impact multiple archaeological resources. Resources adjacent to a catastrophic 

blowout could be damaged by the high volume of escaping gas, buried by large amounts of dispersed 

sediments, crushed by the sinking of the rig or platform, destroyed during emergency relief well drilling, 

or contaminated by the hydrocarbons. 

Based on historical information, over 2,100 potential shipwreck locations have been identified in the 

Gulf of Mexico OCS (USDOI, MMS, 2007). This number is a conservative estimate and is heavily 

weighted toward post-19th century, near-shore shipwrecks, where historic records documenting the loss of 

the vessels were generated more consistently. Of the 2,100 recorded wrecks, only 233 records were 

determined to have associated spatial data possessing sufficient accuracy for BOEMRE’s needs. 

The inadequacy of data related to these historic ship losses creates uncertainty in determining how 

many shipwrecks might be located near existing or planned oil and gas wells. If undiscovered shipwrecks 

are adjacent to a catastrophic blowout, the potential for impacting these nonrenewable resources is high. 

However, the potential of a well being drilled close enough to damage or bury a known prehistoric or 

historic resource, such as a shipwreck, is low when archaeological surveys are required prior to any 

exploration or development activities. 

2.2.3.2. Commercial Fishing 

The initial explosion and fire could endanger commercial fishermen in the immediate vicinity of the 

blowout. Although commercial fishing vessels in the area would likely aid in initial search-and-rescue 

operations, the subsequent fire could burn for over a month, during which time commercial vessels would 

be expected to avoid the area so as to not interfere with response activities. This could impact the 

livelihood and income of these commercial fishermen. 

2.2.3.3. Recreational Resources and Fishing 

A substantial amount of recreational activity is associated in the immediate area around shallow water 

oil and gas structures because these structures function as artificial reefs, promote coral growth, and 

attract fish. About 20 percent of the recreational fishing activity and 90 percent of the recreational diving 

activity in the Gulf of Mexico occurs within 300 feet of oil and gas structures (Hiett and Milon, 2002). 

Therefore, an explosion and fire within 100 miles of shore could endanger recreational fishermen and 

divers in the immediate vicinity of the blowout, especially if the blowout is located between water depths 

of 100 and 200 feet. Recreational vessels in the area would likely aid in initial search-and-rescue 

operations but would also be in danger during the explosion and subsequent fire. The subsequent fire 

could burn for more than a month, during which recreational vessels would be expected to avoid the area 

and not interfere with response activities. This will impact the income of recreational fishing and diving 

businesses. Also, if the fire and smoke is visible from recreational beaches, their recreational use may be 

impacted. 

2.2.3.4. Human Resources, Land Use, and Environmental Justice 

Fatalities and serious injuries would likely occur during the initial explosion and/or fire. Due to the 

large number of people (>100) working on a deepwater drilling rig or platform, dozens of fatalities and 

serious injuries could occur. 

With the explosion (>3 nautical miles) from the shore and the likelihood that the resulting fire will 

burn for a short duration, the initial fire and/or explosion is not expected to impact land use, 
Catastrophic Spill Event Analysis B-13 

demographics, or economics, although some recreational beach use may be impacted (Section 2.2.2.3). 

Thus, the initial fire and explosion should not disproportionately affect low-income persons or minorities, 

and therefore, will not raise environmental justice concerns. 

3. OFFSHORE SPILL (PHASE 2) 

3.1. IMPACT-PRODUCING FACTORS AND SCENARIO

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. 

3.1.1. Duration of Spill 

The duration of the offshore spill from a blowout depends on time needed for intervention and time 

the remaining oil persists offshore. If a blowout occurs and the damaged surface facilities preclude well 

reentry operations, a relief well may be needed to regain control. The time required to drill the relief well 

depends on the complexity of the intervention, the location of a suitable rig, the type of operation that 

must be terminated to release the rig (e.g., casing may need to be run before releasing the rig), and 

problems mobilizing personnel and equipment to the location. A blown-out well may also be successfully 

capped prior to completion of relief wells, as occurred in the Deepwater Horizon incident. Assuming the 

duration of previous spills including the Deepwater Horizon and the type of oil and water temperatures 

found in the Gulf of Mexico, the majority of visibly spilled oil on the surface of the water would not 

persist more than 30 days after the oil flow stopped (Inter-agency, 2010a). 

3.1.1.1. Shallow Water 

If a blowout occurs in shallow water the entire intervention effort including drilling relief wells could 

take 1 to 3 months. This includes 1-3 weeks to transport the drilling rig to the well site. Spilled surface oil 

is not expected to persist more than 1 month after the flow is stopped. Therefore, the estimated spill 

duration resulting from a shallow water blowout in is 2-4 months. 

3.1.1.2. Deepwater 

If a blowout occurs in deepwater, the entire intervention effort including drilling relief wells could 

take 3 to 4 months. (USDOI, MMS, 2000; Regg, 2000). This includes 2-4 weeks to transport the drilling 

rig to the well site. Spilled surface oil is not expected to persist more than 1 month after the flow is 

stopped. Therefore, the estimated spill duration from a deep water blowout is 4-5 months. 

3.1.2. Area of Spill 

When oil reaches the sea surface, it spreads. The speed and extent of spreading depends on the type 

and volume that is spilled. However, a catastrophic spill would likely spread hundreds of square miles. 

Also, the oil slick may break into several smaller slicks, depending on local wind patterns that drive the 

surface currents in the spill area. 

3.1.3. Volume of Spill 

For this analysis, a higher flow rate is assumed for a blowout in deep water for the following reasons: 

After 50 years of Gulf of Mexico development most, if not all, of the largest shallow water prospects have 

been developed. As a result, reservoir pressures in shallow water are generally reduced. Although under 

certain conditions oil may be present with the natural gas, deeper shelf wells target natural gas. Also, 

because deepwater development is costly, only larger prospects with higher flow rates are currently 

targeted for exploration. 
B-14 Central Planning Area Supplemental EIS 

3.1.3.1. Shallow Water 

For this analysis, an uncontrolled flow rate of 30,000 barrels per day is assumed for a catastrophic 

blowout in shallow water. This assumption is based upon the results of well tests in shallow water (see 

Section 3.1.3 above) and the maximum flow rate from the 1979 Ixtoc blowout, which occurred in shallow 

water. Using this flow rate, the total volume of oil spilled from a catastrophic blowout in shallow water is 

estimated at 900,000 to 3 million barrels for a spill lasting 1-3 months. In addition to the flow rate, it is 

assumed that any remaining diesel fuel from a sunken drilling rig would also leak. 

3.1.3.2. Deep Water 

For the purposes of this analysis, an uncontrolled flow rate of 30,000-60,000 barrels per day is 

assumed for a catastrophic blowout in deep water. This flow rate is based on the assumption in Section 

3.1.3 above, well test results, and the maximum expected flow rate of the 2010 Deepwater Horizon

blowout, which occurred in deep water. Therefore, total volume of oil spilled is estimated to be 2.7-7.2 

million barrels over 3-4 months. In addition, deepwater drilling rigs hold a large amount of diesel fuel 

(10,000-20,000 barrels). Therefore, it is assumed that any remaining diesel fuel from a sunken drilling rig 

would also leak and add to the spill. 

3.1.4. Oil in the Environment: Properties and Persistence 

The fate of oil in the environment depends on many factors, such as the source and composition of the 

oil, as well as its persistence (NRC, 2003). Persistence can be defined and measured in different ways 

(Davis et al., 2004), but the National Research Council (NRC) generally defines persistence as how long 

oil remains in the environment (NRC, 2003; p. 89). Once oil enters the environment, it begins to change 

through physical, chemical, and biological weathering processes (NRC, 2003). These processes may 

interact and affect the properties and persistence of the oil through 

 evaporation (volatilization), 

 emulsification (the formation of a mousse), 

 dissolution, 

 biodegradation 

 oxidation, and 

 transport processes (NRC, 2003; Scholz et al., 1999). 

Horizontal transport takes place via spreading, advection, dispersion, and entrainment while vertical 

transport takes place via dispersion, entrainment, Langmuir circulation, sinking, overwashing, 

partitioning, and sedimentation (NRC, 2003). The persistence of an oil slick is influenced by the 

effectiveness of oil-spill response efforts and affects the resources needed for oil recovery (Davis et al., 

2004). The persistence of an oil slick may also affect the severity of environmental impacts as a result of 

the spilled oil. 

Crude oils are not a single chemical, but instead are complex mixtures with varied compositions. 

Thus, the behavior of the oil and the risk the oil poses to natural resources depends on the composition of 

the specific oil encountered (Michel, 1992). Generally, oils can be divided into three groups of 

compounds: (1) light-weight, (2) medium-weight, and (3) heavy-weight components. On average, these 

groups are characterized as outlined below in Table 2. 
Catastrophic Spill Event Analysis B-15 

Table 2 

 

Properties and Persistence by Oil Component Group 

Properties and 

Persistence Light-weight Medium-weight Heavy-weight 

Hydrocarbon 

compounds 

Up to 10 carbon atoms 10-22 carbon atoms >20 carbon atoms 

API o >31.1o 31.1o-22.3 o <22.3 o 

Evaporation rate Rapid (within 1 day) 

and complete 

Up to several days; not 

complete at ambient 

temperatures 

Negligible 

Solubility in water High Low (at most a few mg/L) Negligible 

Acute toxicity High due to 

monoaromatic 

hydrocarbons (BTEX) 

Moderate due to diaromatic 

hydrocarbons 

(naphthalenes—2 ring 

PAH’s) 

Low except due to 

smothering (i.e., heavier oils 

may sink) 

Chronic toxicity None, does not persist 

due to evaporation 

PAH components (e.g., 

naphthalenes—2 ring 

PAH’s) 

PAH components (e.g., 

phenanthrene, anthracene—

3 ring PAH’s) 

Bioaccumulation 

potential 

None, does not persist 

due to evaporation 

Moderate Low, may bioaccumulate 

through sediment sorption 

Compositional 

majority 

Alkanes and 

cycloalkanes 

Alkanes that are readily 

degraded (specify, as done 

for others) 

Waxes, asphaltenes, and 

polar compounds (not 

significantly bioavailable or 

toxic) 

Persistence Low due to evaporation Alkanes readily degrade, but 

the diaromatic hydrocarbons 

are more persistent 

High; very low degradation 

rates and can persist in 

sediments as tarballs or 

asphalt pavements 

Sources: Michel, 1992; Canadian Center for Energy Information, 2010. 

Of the oil reservoirs sampled in the Gulf of Mexico OCS, the majority fall within the light-weight 

category, while less than one quarter are considered medium-weight and a small portion are considered 

heavy-weight. Oil with an API gravity of 10.0 or less would sink and has not been encountered in the 

Gulf of Mexico OCS and, therefore, it is not analyzed in this paper (USDOI, BOEMRE, 2010c).

Heavy-weight oil may persist in the environment longer than the other two types of oil, but the 

medium-weight components within oil present the greatest risks to organisms because, with the exception 

of the alkanes, these medium-weight components are persistent, bioavailable, and toxic (Michel, 1992). 

Previous studies (e.g., Johansen et al., 2001) supported the assumption that most, if not all, released 

oil would reach the surface of the water column. However, data and observations from the Deepwater 

Horizon incident challenge that assumption. While analyses are in their preliminary stages, it appears that 

measurable amounts of hydrocarbons (dispersed or otherwise) are being detected in the water column as 

subsurface “plumes” and on the seafloor in the vicinity of the release. While not all of these hydrocarbons 

have been definitively traced back to releases from the Macondo well (Deepwater Horizon incident), 

these early measurements and results warrant a reassessment of previous assumptions of the ultimate fate 

of hydrocarbons from unintended subsurface releases. 

3.1.5. Release of Natural Gas 

The quality and quantity of components in natural gas vary widely by the field, reservoir, or location 

from which the natural gas is produced. Although there is not a “typical” makeup of natural gas, it is 

primarily composed of methane (NaturalGas.org, 2010). 
B-16 Central Planning Area Supplemental EIS 

3.1.6. Offshore Cleanup Activities 

As demonstrated by the Ixtoc and Deepwater Horizon spill responses, a large-scale response effort is 

certain to follow a catastrophic blowout. The number of vessels and responders would increase 

exponentially as the spill continued. 

3.1.6.1. Shallow Water 

Within the first week of an oil spill originating in shallow water, 25 vessels are estimated to respond, 

which would steadily increase to over 3,000 by the end of the spill. This includes about 25 skimmers in 

the vicinity of the well at a time. In addition, recovered oil may be barged to shore from recovery vessels. 

Within the first week, over 500 responders are estimated to be deployed to a spill originating in 

shallow water, which would steadily increase up to 25,000 before the well is capped or killed within 2-4 

months. 

Response to an oil spill in shallow water is expected to involve over 10,000 feet of boom within the 

first week and would steadily increase up to 5 million feet (1,000 miles) for use offshore and nearshore, 

the amount dependent upon the location of the potentially impacted shoreline, environmental 

considerations, and agreed upon protection strategies involving the local potentially impacted 

communities. 

Up to 25 planes and 50 helicopters are estimated to respond per day by the end of a shallow-water 

spill. 

Along the Gulf Coast, dispersants are have been preapproved for use greater than 3 nautical miles 

from shore and in water depths greater than 33 feet, with the exception of Florida where the water depth 

must be 65 feet (USCG, 2010). However, the USEPA is presently examining these preapprovals and 

restrictions are anticipated regarding the future use of dispersants for ongoing spills as a result. Changes 

to the dispersant use preapprovals would be expected to limit this use in the future. Under pre-existing 

preapprovals it is estimated that up to a total of 35,000 barrels of dispersant would be used.1

 Aerial 

dispersants would likely be applied from airplanes as a mist, which settles on the oil on the water’s 

surface. In addition to dispersants, controlled burns may also occur. 

3.1.6.2. Deep Water 

Within the first week of oil spill originating in deep water, 50 vessels are estimated to respond, which 

would steadily increase to over 7,000 by the end of the spill. This includes about 25 skimmers in the 

vicinity of the well at a time. In addition, recovered oil may be shuttle tankered to shore from recovery 

vessels. 

For an oil spill in deep water, over 1,000 responders are estimated to be deployed within the first 

week, which would steadily increase up to 50,000 before capping or killing the well within 4-5 months. 

Over 20,000 feet of boom is estimated to be deployed within the first week of a deepwater spill, 

which would steadily increase up to 11 million feet (2,100 miles) offshore and nearshore, the amount 

dependent upon the location of the potentially impacted shoreline, environmental considerations, and 

agreed upon protection strategies involving the local potentially impacted communities. 

Up to 50 planes and 100 helicopters are estimated to respond per day by the end of a deepwater spill. 

With the exception of special Federal management areas or designated exclusion areas, dispersants 

have been preapproved in the vicinity of a deepwater blowout (USCG, 2010). However, the USEPA is 

presently examining these preapprovals and restrictions are anticipated regarding the future use of 

dispersants as a result. Under pre-existing preapprovals it is estimated that up to 50,000 barrels of 

dispersant would could be applied (2/3 on the water surface and 1/3 subsurface, if possible). Changes to 

the dispersant use preapprovals would be expected to limit this use. No preapproval presently exists for 

the use of subsea dispersants and approval must be obtained before each use of this technology. The use 

of subsea dispersants depends on the location of the blowout, as discussed in Table 1. Aerial dispersants 

are applied from airplanes as a mist, which settles on the oil on the water’s surface. In addition to 

 

1

 At the IXTOC-I Well Blowout in 1979, between 1 million and 2.5 million gallons of mostly Corexit dispersant 

products were applied over a 5-month period on the oil discharge. However, this scenario assumes a spill from a 

blowout in shallow water would last up to 3 months. 
Catastrophic Spill Event Analysis B-17 

dispersants, it is estimated that 5-10 controlled burns would be conducted per day in suitable weather. 

About 500 burns in all would remove 5-10 percent of the oil. 

3.1.6.3. Vessel Decontamination Stations 

To avoid contaminating inland waterways, multiple vessel decontamination stations may be 

established offshore in Federal and State waters. Vessels responding to the spill and commercial and 

recreational vessels passing through the spill would anchor, awaiting inspection. If decontamination is 

required, work boats would use fire hoses to clean oil from the sides of the vessels. This could result in 

some oiling of otherwise uncontaminated waters. While these anchorage areas would be surveyed for 

buried pipelines that could be ruptured by ship anchors, they may not be surveyed adequately for benthic 

communities or archaeological sites. Therefore, some damage to benthic communities or archaeological 

sites may occur due to vessel decontamination activities associated with an oil spill in deep water 

(Alabama State Port Authority, 2010; Office of the Governor, State of Florida, 2010; Nodar, 2010; 

Unified Incident Command, 2010a-c; USDOC, NOAA, 2010a; USEPA, 2010a).

3.1.7. Severe Weather 

A hurricane could accelerate biodegradation, increase the area affected by the spill, and/or slow the 

response effort. The Atlantic hurricane season runs from June 1st through November 30th, peaking in 

September. In an average Atlantic season, there are eleven named storms, six hurricanes, and two 

Category 3 or higher storms (USDOC, NOAA, National Weather Service, 2010a). As a result of a 

hurricane, high winds and seas would mix and “weather” the oil from an oil spill. This can help accelerate 

the biodegradation process (USDOC, NOAA, National Weather Service, 2010b). The high winds may 

distribute oil over a wider area (USDOC, NOAA, National Weather Center, 2010b). In the event of a 

hurricane, vessels would evacuate the area, delaying response efforts, including the drilling of relief wells 

and any well capping or collection efforts. 

3.2. MOST LIKELY AND MOST SIGNIFICANT IMPACTS

The most recent EISs prepared by BOEMRE for oil and gas lease sales in the Gulf of Mexico identify 

in detail the potential impacts from reasonably foreseeable oil spills (USDOI, MMS, 2007 and 2008). In 

addition to the impacts described in those documents, the most likely and most significant impacts due to 

the magnitude of shoreline oil as a result of a catastrophic spill are described below. 

3.2.1. Physical Resources 

3.2.1.1. Air Quality 

In the Gulf of Mexico, evaporation from the oil spill would result in concentrations of volatile organic 

compounds (VOCs) in the atmosphere, including chemicals that are classified as being hazardous. The 

VOC concentrations would occur anywhere where there is an oil slick, but would be highest at the source 

of the spill because the rate of evaporation depends on the volume of oil present at the surface. VOC 

concentrations would and decreases with distance as the layer of oil gets thinner. The lighter fractions of 

VOC’s would be most abundant in the immediate vicinity of the spill site. The heavier compounds would 

be emitted over a longer period of time and over a larger area. Some of the compounds emitted could be 

hazardous to workers in close vicinity of the spill site. The hazard to workers can be reduced by 

monitoring and using protective gear, including respirators. During the Deepwater Horizon incident, air 

samples collected by individual offshore workers by British Petroleum (BP), Occupational Safety and 

Health Administration (OSHA), and U.S. Coast Guard showed levels of benzene, toluene, ethylbenzene, 

and xylene that were mostly under detection levels. All samples had concentrations below the OSHA 

Occupational Permissible Exposure Limits (PELs) and the more stringent ACGIH (American Conference 

of Governmental Industrial Hygienists) Threshold Limit Values (TLVs) (U.S. Department of Labor, 

OSHA, 2010a). 

The VOC emissions that result from the evaporation of oil contribute to the formation of particulate 

matter (PM2.5) in the atmosphere. In addition, VOCs could cause an increase in ozone levels, especially if 
B-18 Central Planning Area Supplemental EIS 

the release were to occur on a hot, sunny day with sufficient concentrations of NOx present in the lower 

atmosphere. However, due to the distance from shore, the oil slick would not normally have any effects 

on onshore ozone concentrations. 

It is assumed that response efforts would include hundreds of in-situ or controlled burns, which would 

remove an estimated 5-10 percent of the volume of oil spilled. This could be as much as 720,000 barrels 

of oil for a spill of 60,000 barrels per day for 120 days. In-situ burning would result in ambient 

concentrations of CO, NOx, SO2, PM10, and PM2.5 very near the site of the burn and would generate a 

plume of black smoke. The levels of PM2.5 could be a hazard to personnel working in the area, but this 

could be effectively mitigated through monitoring and relocating vessels to avoid areas of highest 

concentrations. In an experiment of an in-situ burn off Newfoundland, it was found that CO, SO2, and 

NO2 were measured only at background levels and were frequently below detection levels (Fingas et al., 

1995). Limited amounts of formaldehyde and acetaldehyde were measured, but concentrations were close 

to background levels. Measured values of dioxins and dibenzofurans were at background levels. 

Measurements of PAH in the crude oil, the residues, and the air indicated that the PAH in the crude oil are 

largely destroyed during combustion (Fingas et al, 1995). 

While containment operations may be successful in capturing some of the escaping oil and gas, 

recovery vessels may not be capable of storing the crude oil or may not have sufficient storage capacity. 

In this case, excess oil would be burned; captured gas cannot be stored or piped to shore so it would be 

flared. For example, in the Deepwater Horizon incident, gas was flared at the rate of 100-200 million 

cubic feet per day and oil burned at the rate of 10,000-15,000 barrels per day. The estimated NOx

emissions are about 13 tons per day. The SO2 emissions would be dependent on the sulfur content of the 

crude oil. For crude oil with a sulfur content of 0.5 percent, the estimated SO2 emissions are about 16 tons 

per day. Particulate matter in the plume would also affect visibility. Flaring or burning activities upwind 

of a PSD Class I area, e.g., the Breton National Wilderness Area, could be adversely affected due to SO2

concentrations and reduced visibility. 

3.2.1.2. Offshore Water Quality 

The water offshore of the Gulf’s coasts can be divided into two regions: the continental shelf and 

slope (<1,000 ft; 305 m) and deep water (>1,000 ft; 305 m). Waters on the continental shelf and slope are 

heavily influenced by the Mississippi and Atchafalaya Rivers, the primary sources of freshwater, 

sediment, nutrients, and pollutants from a huge drainage basin encompassing 55 percent of the continental 

U.S. (Murray, 1998). Lower salinities are characteristic nearshore where freshwater from the rivers mix 

with Gulf waters. The presence or extent of a nepheloid layer, a body of suspended sediment at the sea 

bottom (Kennett, 1982; p. 524), affects water quality on the shelf and slope. Deep waters east of the 

Mississippi River are affected by the Loop Current and associated warm-core (anti-cyclonic) eddies, 

which flush the area with clear, low-nutrient water (Muller-Karger et al., 2001). However, cold-core 

cyclonic eddies (counter-clockwise rotating) also form at the edge of the Loop Current and are associated 

with upwelling and nutrient-rich, high-productivity waters, although the extent of this flushing can vary 

seasonally. 

While response efforts would decrease the fraction of oil remaining in Gulf waters, significant 

amounts of oil would remain (Inter-agency, 2010a). Natural processes will physically, chemically, and 

biologically aid the degradation of oil (NRC, 2003). The physical processes involved include evaporation, 

emulsification, and dissolution, while the primary chemical and biological degradation processes include 

photooxidation and biodegradation (i.e., microbial oxidation). Water quality would not only be impacted 

by the oil, gas, and their respective components but also to some degree from cleanup and mitigation 

efforts, such as from increased vessel traffic and the addition of dispersants and methanol to the marine 

environment. 

In the case of a catastrophic subsea blowout in deep water, it is assumed that large quantities of 

subsea dispersants would be used. As a result, clouds or plumes of dispersed oil may occur near the 

blowout site. Reports thus far from the Deepwater Horizon incident have found such plumes and have 

shown that the concentrations of these clouds decrease to undetectable levels within a few miles of the 

source (USDOC, NOAA, 2010b). Additional reporting in the coming months will enhance the 

understanding of the effects of subsurface plumes. Dissolved oxygen levels are a concern with any release 

of a carbon source, and these levels became a particular concern during the Deepwater Horizon incident, 
Catastrophic Spill Event Analysis B-19 

since dispersants were used in deep waters for the first time. Thus, the U.S. Environmental Protection 

Agency (USEPA) required monitoring protocols in order to use subsea dispersants (USDOC, NOAA, 

2010c). In areas where plumes of dispersed oil were previously found, dissolved oxygen levels decreased 

by about 20 percent from long-term average values in the Gulf of Mexico; however, scientists reported 

that these levels have stabilized and are not low enough to be considered hypoxic (USDOC, NOAA, 

2010d). The temporary decrease in oxygen content has been attributed to microbial degradation of the oil. 

Over time, as the oil continues to be degraded and diffuses, hypoxia becomes less of a concern. As 

reported for the Deepwater Horizon incident, dissolved oxygen levels would likely remain above levels of 

immediate concern, but there would still be a need to monitor dissolved oxygen levels over time. 

Toxicity of dispersed oil in the environment would depend on many factors, including the 

effectiveness of the dispersion, temperature, salinity, degree of weathering, type of dispersant, and degree 

of light penetration in the water column (NRC, 2005). The toxicity of dispersed oil is primarily due to the 

toxic components of the oil itself (Australian Maritime Safety Authority, 2010). 

3.2.2. Biological Resources 

The most recent EISs prepared by BOEMRE for oil and gas lease sales in the Gulf of Mexico detail 

potential localized impacts to specific species from reasonably foreseeable oil spills. However, a 

catastrophic event, such as a high-volume, extended-duration spill resulting from a blowout, has the 

potential to cause population-level impacts. Multiple Federal and State-listed, threatened and endangered 

species could be impacted from an extended offshore spill (USDOI, FWS, 2010a and 2010b). 

3.2.2.1. Marine and Migratory Birds 

During Phase 2 of a catastrophic spill, the primary concern for marine and migratory birds would be 

their vulnerability to oiling or ingesting oil, which is related to their behavior. Wading birds (e.g., herons, 

egrets, etc.) and species that feed by plunge-diving into the water to catch small fish (e.g., pelicans, 

gannets, terns, gulls, and pelagic birds) and those that use water as a primary means of locomotion, 

foraging, or resting and preening (e.g., diving ducks, cormorants, pelicans, etc.) are highly vulnerable to 

becoming oiled and also to ingesting oil, as are black skimmers. These birds tend to feed and concentrate 

in convergence zones, places in the ocean where strong opposing currents meet. In addition to 

concentrating prey, these zones also aggregate oil (Unified Incident Command, 2010d). Oiling interferes 

with the birds’ ability to fly (thus to obtain food) and compromises the insulative characteristics of down 

and contour feathers making it difficult to maintain body heat. Attempts by the birds to remove the oil by 

preening causes oiled birds to ingest oil and may result in mortality. 

3.2.2.2. Fish, Fisheries, and Essential Fish Habitat 

Early life stages of animals are usually more sensitive to oil than adults (Boesch and Rabalais, 1987; 

NRC, 2005). Weathered crude oil has been shown in laboratory experiments to cause malformation, 

genetic damage, and even mortality at low levels in fish embryos of Pacific herring (Carls et al., 1999). 

There is a high probability of mortality for the eggs and larvae of Gulf fishes that come in contact with 

spilled oil. 

Adult fish may be less at risk than earlier life stages in part because they are less likely to concentrate 

at the surface and may avoid contact with floating oil. There were, however, sightings of whale sharks 

(which are defined as “threatened” by the International Union for Conservation of Nature) swimming 

among slicks from the Deepwater Horizon spill. They were not visibly oiled, but there was concern that 

they could be affected because they are surface feeders (Howell, 2010). Effects of oil on organisms can 

include direct lethal toxicity, sublethal disruption of physiological processes (internal lesions), effects of 

direct coating by oil (suffocation by coating gills), incorporation of hydrocarbons in organisms causing 

tainting or accumulation in the food chain, and changes in biological habitat (decreased dissolved oxygen) 

(Moore and Dwyer, 1974). 

Because oil found in the Gulf of Mexico would generally float on the surface, fish species whose eggs 

and larvae are found at or near the water surface are most at risk from an offshore spill. Species whose 

spawning periods coincide with the timing of the highest oil concentrations would be at greatest risk. If 

there is a subsea catastrophic blowout, it is assumed dispersants would be used. Then there could be 
B-20 Central Planning Area Supplemental EIS 

effects on multiple life history stages and trophic levels. There is limited knowledge of the toxicity of 

dispersants mixed with oil to specific species or life stages of ichthyoplankton, and the likely extent of 

mortality due to the combination of factors is difficult to determine. The combined toxic effects of the oil 

and any dispersants that may be used may not be apparent unless a significant portion of a year-class is 

absent from next year’s fishery (e.g., shrimps, crabs, snapper, and tuna). 

Recent studies by USEPA using representative species provide some indication of the relative toxicity 

of Louisiana sweet crude oil, dispersants, and oil/dispersant mixes. Bioassays were conducted using two 

Gulf species—a mysid shrimp (Amercamysis bahia) and a small estuarine fish, the inland silverside 

(Menidia beryllinina)—to evaluate the acute toxic effects of oil, eight dispersants, and oil/dispersant 

mixtures. In addition, USEPA used standard in vitro techniques using the same dispersants to (1) evaluate 

acute toxicity on three cell lines over a range of concentrations and (2) evaluate effects of these 

dispersants on androgen and estrogen function using human cell lines (to see if they are likely to disrupt 

hormonal systems). All dispersants showed cytotoxicity in at least one cell type at concentrations between 

10 and 110 parts per million (ppm). Results of the in vitro toxicity tests were similar to the whole animal 

tests, showing generally low dispersant toxicity. Lethal concentration (LC50) values (the concentration at 

which half of the test subjects die) were lower than the cell-based assays. For all eight dispersants, for 

both species, the dispersants alone were less toxic than the dispersant/oil mixture. Louisiana sweet crude 

oil alone was determined to be more toxic to both the silverside fish and the mysid shrimp than the 

dispersants alone. The results of the testing for disruption of androgen and estrogen function indicate that 

the dispersants do not show biologically significant endrocrine activity via androgen or estrogen pathways 

(USEPA, Office of Research and Development, 2010a and 2010b). 

The North Atlantic bluefin tuna is an example of a fish/fishery in the Gulf of Mexico that could be at 

risk to lose a year-class. It has a relatively narrow peak spawning period in April and May and floating 

eggs. A catastrophic blowout during the spring season could cause a negative effect to this population. 

The Gulf of Mexico is one of only two documented spawning grounds for the Atlantic bluefin tuna; the 

other is in the Mediterranean Sea. Spawning is clustered in a specific type of habitat along the continental 

slope. Bluefin tuna are among the most valuable fish in global markets. The International Commission for 

the Conservation of Atlantic Tunas (ScienceDaily, 2010) currently manages the Atlantic bluefin tuna as 

two distinct populations, with western Atlantic spawners of the Gulf of Mexico forming a population 

genetically distinct from the eastern spawners of the Mediterranean Sea. The western Atlantic stock has 

suffered, and a significant and a long-term rebuilding plan has failed to revive the population or the 

fishery. The failure of the Gulf of Mexico spawning population to rebuild and the scope of illegal and 

under-reported catches are of such concern that the species was considered for Appendix 1 listing (most 

endangered status) by the Convention of International Trade in Endangered Species (CITES) in March 

2010. 

A catastrophic deepwater spill could release natural gases with methane as the primary component 

(NaturalGas.org, 2010) into the water column, but little is known about the effects of elevated methane 

levels on fish. Patin (1999) studied the elevated concentrations of methane resulting from a gas blowout 

from drilling platforms in the Sea of Asov on fish. The pathological changes reported were species 

specific and included damages to cell membranes, organs, and tissues; modifications of protein synthesis; 

and other anomalies typical for acute poisoning of fish. These impacts, however, were observed at levels 

of 4-6 milligrams/liter of methane near the accidental well. The full effect of elevated methane levels on 

Gulf of Mexico fishes is currently unknown. 

3.2.2.3. Marine Mammals 

An oil spill and related spill-response activities can impact marine mammals that come into contact 

with oil and remediation efforts. The marine mammals’ exposure to hydrocarbons persisting in the sea 

may result in sublethal impacts (e.g., decreased health, reproductive fitness, longevity, and increased 

vulnerability to disease), some soft tissue irritation, respiratory stress from inhalation of toxic fumes, food 

reduction or contamination, direct ingestion of oil and/or tar, and temporary displacement from preferred 

habitats or migration routes. More detail on the potential range of effects to marine mammals from 

contact with spilled oil can be found in Geraci and St. Aubin (1990). The best available information does 

not provide a complete understanding of the effects of the spilled oil and active response/cleanup 
Catastrophic Spill Event Analysis B-21 

activities on marine mammals. For example, it is expected that the large amount of chemical dispersants 

being used on the oil may act as an irritant on the marine mammals’ tissues and sensitive membranes. 

The increased human presence after an oil spill (e.g., vessels) would likely add to changes in behavior 

and/or distribution, thereby potentially stressing marine mammals further and perhaps making them more 

vulnerable to various physiologic and toxic effects. In addition, the large number of response vessels 

could place marine mammals at a greater risk of vessel collisions, which could cause fatal injuries. 

The Potential Biological Removal (PBR) level is defined by the Marine Mammal Protection Act 

(MMPA) as the maximum number of animals, not including natural mortalities that may be removed 

from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable 

population. However, in the Gulf of Mexico, many marine mammal species have either entirely unknown 

PBRs or population size estimates that are more than 8 years old and therefore considered unknown. The 

biological significance of any injury or mortality would depend, in part, on the size and reproductive rates 

of the affected stocks, as well as the number, age, and size of the marine mammals affected. 

According to the Consolidated Fish and Wildlife Collection Reports from the Deepwater Horizon

incident, 103 marine mammals have been collected (9 alive and 94 deceased as of September 22, 2010). 

Thus, a high-volume oil spill lasting 120 days, could directly impact as many individuals or more. The 

majority would likely be coastal or estuarine bottlenose dolphins, as was the case with the Deepwater 

Horizon incident. This number represents only those marine mammals collected (either dead or alive) and 

does not address all potential impacts to the population. Based on these data, it is reasonable to assume 

that a catastrophic oil spill lasting up to 120 days could have population-level effects on many species of 

marine mammals (e.g., sperm whales, Bryde’s whales, etc.). 

3.2.2.4. Sea Turtles 

Sea turtles are more likely to be affected by a catastrophic spill in shallow water than in deep water 

because not all sea turtles occupy a deepwater habitat. For example, Kemp’s ridley sea turtles are unlikely 

to be in water depths of 160 feet or greater. Hawksbill sea turtles are commonly associated with coral 

reefs, ledges, caves, rocky outcrops, and high energy shoals. Green sea turtles are commonly found in 

coastal benthic feeding grounds, although they may also be found in the convergence zones of the open 

ocean. Convergence zones are areas that also may collect oil. Leatherback sea turtles are commonly 

pelagic and are the sea turtle species most likely to be affected by a deepwater oil spill. As the spilled oil 

moves toward land, additional species of sea turtles are more likely to be affected. 

Based on the Consolidated Fish and Wildlife Collection Reports from the Deepwater Horizon

incident, a few to over two dozen sea turtles could be impacted daily through oiling and/or collection. A 

high-volume oil spill lasting 120 days could impact greater than 1,000 sea turtles, and the majority could 

be Kemp's ridley turtles, which are listed as endangered under the ESA (USDOC, NOAA, NMFS, 2010a; 

Unified Incident Command, 2010e). In addition, the large number of response vessels could place sea 

turtles at a greater risk of vessel collisions, which could cause fatal injuries. 

3.2.2.5. Offshore Habitats 

Sargassum mats, which are mats made from a free-floating seaweed, provide habitat for juvenile sea 

turtles and developing invertebrates, spawning sites for hundreds of fish species, and feeding sources for 

manatees. “In offshore waters, both free-floating patches of sargassum seaweed and spilled oil tend to 

accumulate in convergence zones, places in the ocean where strong opposing currents meet. Sea turtles, 

especially juveniles, use these areas for food and cover. Burn operations sometime occur there because of 

the aggregated oil” (Unified Incident Command, 2010d). Benthic resources are discussed below. 

3.2.2.6. Continental Shelf Benthic Resources 

A spill from a shallow-water blowout could impact benthic communities on the continental shelf due 

to the blowout’s proximity to these habitats. A spill from a deepwater blowout could also impact shelf 

communities if oil that was chemically dispersed at the seafloor is transported to these areas. 
B-22 Central Planning Area Supplemental EIS 

Soft-Bottom Benthic Communities 

Soft-bottom infaunal communities that come into direct contact with oil or dispersed oil may 

experience sublethal and/or lethal effects. Localized areas of lethal effects would be recolonized by 

populations from neighboring soft-bottom substrate once the oil in the sediment has been sufficiently 

reduced to a level able to support marine life (Sanders et al., 1980). This initial recolonization process 

may be fairly rapid, but full recovery may take up to 10 years depending on the species present, substrate 

in the area, toxicity of oil spilled, concentration and dispersion of oil spilled, and other localized 

environmental factors that may affect recruitment (Kingston et al., 1995; Gesteira and Dauvin, 2000; 

Sanders et al., 1980; Conan, 1982). Opportunistic species would take advantage of the barren sediment, 

repopulating impacted areas first. These species may occur within the first recruitment cycle of the 

surrounding populations or from species immigration from surrounding stocks and may maintain a 

stronghold in the area until community succession begins (Rhodes and Germano, 1982; Sanders et al., 

1980). 

Long-term or low-level exposure may occur to benthic infauna as a result of oil adhering to sediment. 

Mesocosm experiments using long-term, low-level concentrations of No. 2 fuel oil indicate acute toxicity 

to meiofauna due to direct oil contact and sublethal effects from sedimented oil and byproducts of the 

decomposition of the sedimented oil (Frithsen et al., 1985). Long-term exposure to low levels of fuel oil 

was shown to affect recruitment success; meiofaunal population recovery took between 2 and 7 months 

(Frithsen et al., 1985). Oil entrained within sediments at the seafloor could create a layer toxic to infaunal 

species. This layer will persist through burial unless it is sufficiently degraded over time. Continued 

deposition of pelagic material could bury the layer, but it will remain intact over some timeframe as a 

potentially toxic or lethal horizon. 

Continued localized disturbance of soft-bottom communities may occur during oil-spill response 

efforts. Anchors used to set booms to contain oil or vessel anchors in decontamination zones may affect 

infaunal communities in the response activity zone. Infaunal communities may be altered in the anchor 

scar and deposition of suspended sediment may result from the setting and resetting of anchors. The 

disturbed benthic community should begin to repopulate from the surrounding communities during their 

next recruitment event and through immigration of organisms from surrounding stocks. Any 

decontamination activities, such as cleaning vessel hulls of oil, may also contaminate the sediments of the 

decontamination zone, as some oil may settle to the seabed, impacting the underlying benthic community. 

If a blowout occurs at the seafloor, drilling muds (primarily barite) may be pumped into a well in 

order to “kill” it. If a kill is not successful, the mud (possibly tens of thousands of barrels) may be forced 

out of the well and deposited on the seafloor near the well site. Any organisms beneath heavy layers of 

the extruded drilling mud would be buried. Base fluids of drilling muds are designed to be low in toxicity 

and biodegradable in offshore marine sediments (Neff et al., 2000). However, as bacteria and fungi break 

down the drilling fluids, the sediments may be come anoxic (Neff et al., 2000). Benthic macrofaunal 

recovery would occur when drilling mud concentrations are reduced to levels that enable the sediment to 

become re-oxygenated (Neff et al., 2000). Complete community recovery from drilling mud exposure 

may take 3-5 years, although microbial degradation of drilling fluids, followed by an influx of tolerant 

opportunistic species is anticipated to begin almost immediately (Neff et al., 2000). In addition, the 

extruded mud may bury hydrocarbons from the well, making them a hazard to the infaunal species and 

difficult to remove. 

Hard-Bottom Benthic Communities 

Sensitive reef communities flourish wherever hard bottoms occur in the Gulf of Mexico. Several 

categories are protected by BOEMRE. The eastern Gulf of Mexico contains scattered, low-relief livebottoms including areas of flat limestone shelf rock. Potentially sensitive biological features are 8 feet or 

more above the seafloor. The Pinnacle Trend area includes low- and high-relief features and is 60-120 m 

(200-400 ft) below the sea surface, and topographic features are high relief and generally 15 m (49 ft) or 

more below the sea surface. Their depth below the sea surface protects all of these habitats from a surface 

oil spill. 

Although hard-bottom benthic communities are initially buffered from surface oil slicks by their 

depth below the sea surface, surface oil may be brought to depth through physical processes. Rough seas 

may mix the oil into subsurface water layers, where it may impact sessile biota. The total time during 
Catastrophic Spill Event Analysis B-23 

which seas are rough would help affect the amount of oil from a surface slick that would be mixed into 

the water column. Measurable amounts of oil have been documented down to a 10-m (33-ft) depth, 

although modeling exercises have indicated such oil may reach a depth of 20 m (66 ft). At this depth, 

however, the oil is found at concentrations several orders of magnitude lower than the amount shown to 

have an effect on corals (Lange, 1985; McAuliffe et al., 1975 and 1981; Knap et al., 1985). 

The presence of a subsurface oil plume may affect hard-bottom communities. A portion of the oil 

released is expected to rise rapidly to the sea surface. However, upward movement of the oil may be 

reduced if methane in the oil is dissolved under high pressures, and oil droplets may become entrained 

deep in the water column (Adcroft et al., 2010). Subsurface plumes generated by high-pressure 

dissolution of oil may come in contact with hard-bottom features. A sustained spill would continuously 

create surface slicks and possibly subsurface spill plumes. Some of the oil in the water column will 

become diluted or evaporated over time, reducing any localized transport to the seafloor (Vandermeulen, 

1982). In addition, microbial degradation of the oil occurs in the water column so that the oil would be 

less toxic when it contacts the seafloor (Hazen et al., 2010). However, a sustained spill may result it 

elevated exposure concentrations to hard-bottom features if the plume reaches them. The longer the spill 

takes to stop, the longer the exposure time and concentration may be. 

Low-level exposures of corals to oil from a subsea plume may result in chronic or temporary impacts. 

For example, feeding activity or reproductive ability may be reduced when coral is exposed to low levels 

of oil; however, impacts may be temporary or unable to be measured over time. Experiments indicated 

that normal feeding activity of Porites porites and Madracis asperula were reduced when exposed to 50 

ppm oil (Lewis, 1971). Reefs of Siderastrea sidereal that were oiled in a spill produced smaller gonads 

than unoiled reefs, resulting in reproductive stress (Guzmán and Holst, 1993). 

Elevated concentrations of oil may be necessary to measure reduced photosynthesis or growth in 

corals. Photosynthesis of the zooxanthellae in Diplora strigosa exposed to approximately 18-20 ppm 

crude oil for 8 hours was not measurably affected, although other experiments indicate that 

photosynthesis may be impaired at higher concentrations (Cook and Knap, 1983). Measurable growth of 

Diploria strigosa exposed to oil concentrations up to 50 ppm for 6-24 hours did not show any reduced 

growth after 1 year (Dodge et al., 1984). 

Corals exposed to subsea oil plumes may incorporate petroleum hydrocarbons into their tissue. 

Records indicate that Siderastrea siderea, Diploria strigosa, and Montastrea annularis accumulate oil 

from the water column and incorporate petroleum hydrocarbons into their tissues (Burns and Knap, 1989; 

Knap et al., 1982; Kennedy et al., 1992). Most of the petroleum hydrocarbons are incorporated into the 

coral tissues, not their mucus (Knap et al., 1982). However, hydrocarbon uptake may also modify lipid 

ratios of coral (Burns and Knap, 1989). If lipid ratios are modified, mucus synthesis may be impacted, 

adversely affecting the coral’s ability to protect itself from oil through mucus production (Burns and 

Knap, 1989). 

If dispersants are used on the seafloor or at the surface, oil may mix into the water column well below 

the surface, can travel with currents through the water, and may contact settle on hard bottoms. If near the 

source, the dispersed oil could be concentrated enough to harm the community. If the oil remains 

suspended for a longer period of time, it would be more dispersed and present at lower concentrations. 

Reports on dispersant usage on surface plumes indicates that a majority of the dispersed oil remains in the 

top 10 m of the water column, with 60 percent of the oil in the top 2 m (McAuliffe et al., 1981). 

Dispersant usage also reduces the oil’s ability to stick to particles in the water column, minimizing 

sedimented oil traveling to the seafloor (McAuliffe et al., 1981). 

Dispersed oil reaching the benthic hard-bottom communities in the Gulf of Mexico would be 

expected to be at very low concentrations (less than 1 part per million) (McAuliffe et al., 1981). Such 

concentrations would not be life threatening to larval or adult stages at depth based on experiments 

conducted with coral. Any dispersed oil in the water column that comes in contact with corals may evoke 

short-term negative responses by the organisms (Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 

1984). 

Reductions in feeding and photosynthesis are some impacts that may occur to coral exposed to 

dispersed oil. Short-term, sublethal responses of Diploria strigosa were reported after exposure to 

dispersed oil at a concentration of 20 ppm for 24 hours. Although concentrations in this experiment were 

higher than what is anticipated for dispersed oil at depth, effects exhibited included mesenterial filament 

extrusion, extreme tissue contraction, tentacle retraction, and localized tissue rupture (Wyers et al., 1986). 
B-24 Central Planning Area Supplemental EIS 

Normal behavior resumed within 2 hours to 4 days after exposure (Wyers et al., 1986). Diploria strigosa

exposed to dispersed oil (20:1, oil:dispersant) showed an 85 percent reduction in zooxanthellae 

photosynthesis after 8 hours of exposure to the mixture (Cook and Knap, 1983). However, the response 

was short-term, as recovery occurred between 5 and 24 hours after exposure and return to clean seawater. 

Investigations 1 year after Diploria strigosa was exposed to concentrations of dispersed oil between 1 and 

50 ppm for periods between 6 and 24 hours did not reveal any impacts to growth (Dodge et al., 1984). 

Dispersed oil does appear to be more toxic to coral species than oil or dispersant alone. The greater 

toxicity may be a result of and increased number of oil droplets caused by the use of dispersant, resulting 

in greater contact area between oil, dispersant, and water (Elgershuizen and Kruijf, 1976). The dispersant 

causes a higher water-soluble amount of oil to contact the cell membranes of the coral (Elgershuizen and 

Kruijf, 1976). The mucus produced by coral, however, can protect the organism from oil. Both hard and 

soft corals have the ability to produce mucus, and mucus production has been shown to increase when 

corals are exposed to crude oil (Mitchell and Chet, 1975; Ducklow and Mitchell, 1979). Dispersed oil 

however, which has very small oil droplets, does not appear to adhere to coral mucus, and larger untreated 

oil droplets may become trapped by the mucus barrier (Knap, 1987; Wyers et al., 1986). However, 

entrapment of the larger oil droplets may increase the coral’s long-term exposure to oil if the mucus is not 

shed in a timely manner (Knap, 1987; Bak and Elgershuizen, 1976). 

Although dispersed oil may be more toxic than untreated oil to corals during exposure experiments, 

untreated oil may remain in the ecosystem for long periods of time, while dispersed oil does not (Baca et 

al., 2005; Ward et al., 2003). Twenty years after an experimental oil spill in Panama, oil and impacts from 

untreated oil were still observed at oil treatment sites, but no oil or impacts were observed at dispersed oil 

or reference sites (Baca et al., 2005). Long-term recovery of the coral at the dispersed oil site had already 

occurred as reported in a 10-year monitoring update, and the site was not significantly different from the 

reference site (Ward et al., 2003). 

The BOEMRE policy prevents wells from being placed immediately adjacent to sensitive 

communities. In the event of a seafloor blowout however, some oil could be carried to hard bottoms as a 

result of oil droplets sedimenting to suspended particles in the water column. Oiled sediment that settles 

to the seafloor may affect organisms attached to hard-bottom substrates. Impacts may include reduced 

recruitment success, reduced growth, and reduced coral cover as a result of impaired recruitment. 

Experiments have shown that the presence of oil on available substrate for larval coral settlement has 

inhibited larval metamorphosis and larval settlement in the area. There were also an increased number of 

deformed polyps after metamorphosis due to oil exposure (Kushmaro et al., 1997). 

The majority of organisms exposed to sedimented oil however, are anticipated to experience lowlevel concentrations because as the oiled sediments settle to the seafloor they are widely dispersed. Coral 

may also be able to protect itself from low concentrations of sedimented oil that settles from the water 

column. Coral mucus may not only act as a barrier to protect coral from the oil in the water column but it 

has also been shown to aid in the removal of oiled sediment on coral surfaces (Bak and Elgershuizen, 

1976). Coral may use a combination of increased mucus production and ciliary action to rid themselves of 

oiled sediment (Bak and Elgershuizen, 1976). 

Oil-spill response activity may also impact sessile benthic features. Booms anchored to the seafloor 

are sometimes used to control the movement of oil at the water surface. Boom anchors can physically 

impact corals and other sessile benthic organisms, especially when booms are moved around by waves 

(Tokotch, 2010). Vessel anchorage and decontamination stations set up during response efforts may also 

break or kill hard-bottom features as a result of setting anchors. Injury to coral reefs as a result of anchor 

impact may result in long-lasting damage or failed recovery (Rogers and Garrison, 2001). Effort should 

be made to keep vessel anchorage areas as far from sensitive benthic features as possible to minimize 

impact. 

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 

buried. Based on NTL 2009-G39, a well should be far enough away from a hard-bottom community to 

prevent extruded drilling muds from smothering benthic communities. However, if drilling muds were to 

travel far enough or high enough in the water column to contact a hard-bottom community, the fluid 

would smother the existing community. Experiments indicate that corals perish faster when buried 

beneath drilling mud than when buried beneath carbonate sediments (Thompson, 1980). As discussed 
Catastrophic Spill Event Analysis B-25 

earlier, as the drilling fluids biodegrade, an anoxic zone surrounding the activity may occur. 

Recolonization would occur from the surrounding community once the area has enough oxygen to 

support new growth, which may take 3-5 years (Neff et al., 2000). 

3.2.2.7. Deepwater Benthic Communities 

It is not likely that deepwater benthic communities would be impacted by a spill from a shallow water 

blowout. However, a spill resulting from a catastrophic blowout in deep water has the potential to impact 

offshore benthic communities due to the blowout’s proximity to these habitats and the use of subsea 

dispersants. 

Much of the oil is expected to be treated with dispersants at the sea surface and possibly subsea at the 

source in the event of a deep water blowout. The dispersed oil is mixed with the water, and its movement 

is then dictated by local currents and the physical, chemical, and biological degradation pathways. The oil 

would become more dispersed, less concentrated, and more biodegraded the longer it remains suspended 

in the water column. Depending on how long it remained suspended in the water column, it may be 

thoroughly degraded by biological action before contact with the seafloor and its sensitive resources 

occurs (Hazen et al., 2010; Valentine et al., 2010). Biodegradation rates in colder, deepwater 

environments are not well understood at this time. Oil may reach the seafloor in the following ways: as 

microbes begin to consume the oil particles; when the dispersed oil particles may flocculate (flocculation 

is suspended particles collecting into larger suspended flakes),), thus increasing the density of the 

particles such that they are no longer in isostatic balance with the surrounding water and thus, sink to the 

seafloor; when larger plankton consume the bacteria-rich oil particles and their fecal pellets are excreted 

and distributed over the seafloor; when water currents carry a plume to contact the seafloor directly; or 

most likely, where the dispersed oil to adhere to other particles and sink to the seafloor. This last scenario 

would result in a wide distribution of small amounts of oil. This oil could be in the process of 

biodegradation from bacterial action that would continue on the seafloor, resulting in scattered 

microhabitats with an enriched carbon environment. Biodegradation processes, both on the bottom and in 

the water column, would be expected to cause at least some reduction of normal ambient dissolved 

oxygen levels; however, this has yet to be observed at a level that would be detrimental to animal 

respiration (Hazen et al., 2010). 

Deepwater Soft-Bottom Benthic Communities 

Soft bottoms are the overwhelming majority of the deep-sea environment. Large amounts of oil 

would only affect these deep environments if dispersants are used. As described above, the toxic effects 

of dispersed oil would continue to reduce as the concentration of oil is reduced via dispersion, localized 

mixing, and biodegradation. As with shelf habitats, the only soft bottom that is expected to suffer 

significant effects would be soft bottoms in the immediate vicinity of a seafloor blowout in which some 

oil is mixed into the sediment. In situations where soft-bottom infaunal communities are negatively 

impacted, recolonization by populations from neighboring soft-bottom substrate would be expected over a 

relatively short period of time for all size ranges of organisms—a matter of days for bacteria and probably 

less than 1 year for most macrofauna and megafauna species. This could take longer for areas affected by 

direct oil contact in higher concentrations. 

Deepwater Coral Benthic Communities 

There have been no experiments showing the response of deepwater corals to oil exposure. 

Experiments with shallow tropical corals indicate that corals have a high tolerance to oil exposure. The 

mucus layers on coral resist penetration of oil and slough off the contaminant. Longer exposure times and 

areas of tissue where oil adheres to the coral are more likely to result in tissue damage and death of 

polyps. Corals with branching growth forms appear to be more susceptible to damage from oil exposure 

(Shigenaka, 2001). The most common deepwater coral, Lophelia pertusa, is a branching species. Tests 

with shallow tropical gorgonians indicate relatively low toxic effects to the coral (Cohen et al., 1977), 

suggesting deepwater gorgonians may have a similar response. Response of deepwater coral to oil 

exposure from a catastrophic spill would vary, depending on the level of exposure. Exposure to widely 

dispersed oil adhering to organic detritus and partially degraded by bacteria may be expected to result in 
B-26 Central Planning Area Supplemental EIS 

little effect. Direct contact with plumes of relatively fresh dispersed oil droplets in the vicinity of the 

incident could cause death of affected coral polyps through exposure and potential feeding on oil droplets 

by polyps. Median levels of exposure to dispersed oil in a partly degraded condition may result in effects 

similar to those of shallow tropical corals, with often no discernable effects other than temporary 

contraction and some sloughing. The health of corals may be degraded by the necessary expenditure of 

energy as the corals respond to oiling (Shigenaka, 2001). Communities exposed to more concentrated oil 

may experience detrimental effects, including death of affected organisms, tissue damage, lack of growth, 

interruption of reproductive cycles, and loss of gametes. Many invertebrates associated with deepwater 

coral communities, particularly the crustaceans, would likely be more susceptible to damage from oil 

exposure. The recolonization of severely damaged or destroyed communities could take years or decades. 

However, because of the scarcity nature of deepwater hard bottoms and the comparatively low surface 

area, it is unlikely that a sensitive habitat would be located near a seafloor blowout, or if near, that 

concentrated oil would contact the site. 

Deepwater Chemosynthetic Benthic Communities 

Chemosynthetic communities, which are adapted to gas seeps which sometimes release oil also. 

They may receive. . . , low quantities of well-dispersed oil undergoing biodegradation may and 

experience little negative effect. Exposure may be similar to normal conditions for these communities and 

may be within the normal variation of habitat conditions. However, oil contact could cause some 

fluctuation in organism health, resulting in slower growth or delayed spawning. Since these organisms 

grow slowly, sublethal effects could eliminate a year or more of normal growth. Communities exposed to 

more concentrated oil may experience detrimental effects, including death of affected organisms, tissue 

damage, lack of growth, interruption of reproductive cycles, and loss of gametes. Other invertebrates 

associated with chemosynthetic communities, particularly the crustaceans, would likely be more 

susceptible to damage from oil exposure. Recolonization of severely damaged or destroyed communities 

could take years or decades. 

3.2.3. Socioeconomic Resources 

3.2.3.1. Offshore Archaeological Resources 

Due the response methods (i.e., subsea dispersants) and magnitude of the response (i.e., thousands of 

vessels), a catastrophic blowout and spill have a greater potential to impact offshore archaeological 

resources than other accidental events. 

Deep Water 

In contrast to smaller spills or spills in shallow water, the use of large quantities of subsea dispersants 

could be used for a catastrophic subsea blowout in deep water. This could result in currently unknown 

effects from dispersed oil droplets settling to the seafloor. Though information on the actual impacts to 

submerged cultural resources is inconclusive at this time, oil settling to the seafloor could come in contact 

with archaeological resources. At present, there is no evidence of this having occurred. A recent 

experimental study has suggested that, while the degradation of wood in terrestrial environments is 

initially retarded by contamination with crude oil, at later stages, the biodeterioration of wood was 

accelerated (Ejechi, 2003). While there are different environmental constraints that affect the degradation 

of wood in terrestrial and waterlogged environments, soft-rot fungal activity, one of the primary wood 

degrading organisms in submerged environments, was shown to be increased in the presence of crude oil. 

There is a possibility that oil from a catastrophic blowout could come in contact with wooden shipwrecks 

and artifacts on the seafloor and accelerate their deterioration. 

Ancillary damages from vessels associated with oil-spill response activities (e.g., anchoring) in deep 

water are unlikely due to the use of dynamically positioned vessels responding to a deepwater blowout. If 

response and support vessels were to anchor near a deepwater blowout site, the potential to damage 

undiscovered vessels in the area would be high due to the required number and the size of anchors and the 

length of mooring chains needed to safely secure vessels. Additionally, multiple offshore vessel 

decontamination stations would likely be established in shallow water outside of ports or entrances to 
Catastrophic Spill Event Analysis B-27 

inland waterways, as seen for the Deepwater Horizon incident. The anchoring of vessels could result in 

damage to both known and undiscovered archaeological sites; the potential to impact archaeological 

resources increases as the density of anchoring activities in these areas increases. 

Shallow Water 

The potential for damaging archaeological resources increases as the oil spill and related response 

activities progress landward. In shallower waters, most of the damage would be associated with oil 

cleanup and response activities. Thousands of vessels would respond to a shallow-water blowout and 

would likely anchor, potentially damaging both known and undiscovered archaeological sites. Additional 

anchoring would be associated with offshore vessel decontamination stations, as described above. As the 

spill moves into the intertidal zone, the chance of direct contact between the oil and archaeological 

resources increases. As discussed above, this could result in increased degradation of wooden shipwrecks 

and artifacts. 

Additionally, in shallower waters, shipwrecks often act as a substrate to corals and other organisms, 

becoming an essential component of the marine ecosystem. These organisms often form a protective layer 

over the shipwreck, virtually encasing the artifacts and hull remains. If these fragile ecosystems were 

destroyed as a result of the oil spill and the protective layer removed, the shipwreck would then be 

exposed to increased degradation until it reaches a new level of stasis with its surroundings. 

Regardless of water depth, because oil is a hydrocarbon, heavy oiling could contaminate organic 

materials associated with archaeological sites, resulting in erroneous dates from standard radiometric 

dating techniques (e.g., 14C-dating). Interference with the accuracy of 14C-dating would result in the loss 

of valuable data necessary to understand and interpret the sites. 

3.2.3.2. Commercial Fishing 

In 2008, the Gulf of Mexico provided over 33 percent of the commercial fishery landings in the 

continental U.S. (excluding Alaska), with nearly 1.3 billion pounds valued at nearly $660 million. 

(USDOC, NMFS, 2010). 

Even though sensory and chemical testing may show no detectable oil or dispersant odors or flavors 

and the results could be well below the levels of concern, NOAA Fisheries would be expected to close 

large portions of the Gulf of Mexico during a high-volume spill as a precautionary measure to ensure 

public safety and to assure consumer confidence in Gulf seafood (USDOC, NOAA, NOAA Fisheries 

Service, 2010a). Up to 30-40 percent of Gulf of Mexico Exclusive Economic Zone (EEZ) could be closed 

to commercial fishing as the spill continues and expands (USDOC, NOAA, NOAA Fisheries Service, 

2010b). This area could represent 50-75 percent of the Gulf seafood production (Flynn, 2010). The 

closure area may peak about 50 days into the spill and persist another 2-3 months until the well is killed 

or capped and the remaining oil is recovered or dissipates. During this period, portions or all of individual 

State waters would also be closed to commercial fishing. 

The economic impacts of closures on commercial fishing are difficult to predict because they are 

dependent on the season and would vary by fishery. If fishers cannot make up losses throughout the 

remainder of the season, a substantial part of their annual income would be lost. In some cases, 

commercial fishers will move to areas still open to fishing, but at a greater cost due to longer transit times. 

Marketing issues are also possible; even if the catch is uncontaminated, the public may lack confidence in 

the product. 

3.2.3.3. Recreational Fishing 

Up to 30-40 percent of the Gulf of Mexico EEZ could be closed to recreational fishing as the spill 

continues and expands (USDOC, NOAA Fisheries, 2010b). The closure area could peak about 50 days 

into the spill and continue for another 2-3 months until the well is killed or capped and the remaining oil 

is recovered or dissipates. During this period, portions or all of individual State waters would also be 

closed to recreational fishing. 

In 2008, over 24 million recreational fishing trips were taken, which generated about $12 billion in 

sales, over $6 billion in value-added impacts, and over 100,000 jobs (USDOC, NOAA, NMFS, 2010b). 

About 33 percent of the total Gulf catch came on trips that fished primarily in Federal and State waters 
B-28 Central Planning Area Supplemental EIS 

(Pritchard, 2009). Recreational fishing is focused in the summer months. During this time, scheduled 

tournaments would be hard to reschedule. If the spill affected that time of year, normal direct income and 

indirect income to the communities that host these tournaments would be lost for that year. If a 

catastrophic spill occurs in the summer, a substantial number of recreational fishing trips would not occur 

and the economic benefits they generate would be lost for that year. 

3.2.3.4. Tourism and Recreational Resources 

While the spill is still offshore, there could be some ocean-dependent recreation that is affected (e.g., 

fishing, diving), as discussed above. In addition, there may be some effects due to either perceived 

damage to onshore recreational resources that has not yet materialized or to general hesitation on the part 

of travelers to visit the overall region due to the spill. For example, studies during the Deepwater Horizon

oil spill show that perceptions can influence recreational activity, even if an oil spill has not yet damaged 

physical resources in an area (The Knowland Group, 2010; Market Dynamics Research Group, 2010). 

However, the majority of the impacts of a catastrophic spill would occur once the spill has contacted 

shore, as discussed in Section 4.2.3.4. 

3.2.3.5. Employment and Demographics 

In contrast to a less severe accidental event, suspension of some oil and gas activities would be likely 

following a catastrophic event. Depending on the duration and magnitude, this could impact hundreds of 

oil-service companies that supply the steel tubing, engineering services, drilling crews, and marine supply 

boats critical to offshore exploration. An interagency economic report estimated that the 6-month 

suspension, as a result of the Deepwater Horizon incident, may have directly and indirectly resulted in up 

to 8,000-12,000 fewer jobs along the Gulf Coast (Inter-agency, 2010b). Most of these jobs were not 

permanently lost as a result of the suspension and returned following the resumption of deepwater drilling 

in the Gulf of Mexico. These estimates are lower than earlier estimates of 15,000-60,000 rig and 

associated service jobs being at risk (Hargreaves, 2010; LMOGA, 2010; Zeller, 2010; Jindal, 2010). 

Whatever the number, much of the employment loss would be concentrated in coastal oil-service 

parishes in Louisiana (St. Mary, Terrebonne, Lafourche, Iberia, and Plaquemines) and counties/parishes 

where drilling-related employment is most concentrated (Harris County, Texas, in which Houston is 

located, and Lafayette Parish, Louisiana) (Nolan and Good, 2010; U.S. Department of Labor, BLS, 2010). 

There would be additional economic impacts to commercial and recreational fishing, as discussed in 

Sections 3.2.3.2 and 3.2.3.3. This impact is also expected to be more heavily concentrated in smaller 

businesses than in the larger companies (Inter-agency, 2010b). 

Demographic impacts are unlikely from temporary job losses. 

3.2.3.6. Land Use and Coastal Infrastructure 

Impacts to tourism and recreational resources are addressed in Section 3.2.3.4. Possible fisheries 

closures are addressed in Sections 3.2.3.2 and 3.2.3.3. While still offshore, a catastrophic oil spill would 

not impact other land use or coastal infrastructure. 

3.2.3.7. Environmental Justice 

The environmental justice policy, based on Executive Order 12898 of February 11, 1994, directs 

agencies to incorporate into NEPA documents an analysis of potentially disproportionate and detrimental 

environmental and health effects of their proposed actions on minorities and low-income populations and 

communities. While the spill is still offshore, the primary environmental justice concern would be large 

commercial fishing closures disproportionately impacting minority fishers. In the event of a catastrophic 

spill, Federal and State agencies would be expected to close substantial portions of the Gulf to 

commercial and recreational fishing (USDOC, NOAA, 2010g). While oystering occurs “onshore,” oyster 

beds are also likely to be closed to harvests during Phase 2 of a catastrophic spill due to concerns about 

oil contamination and increased freshwater diversions to mitigate oil intrusion into the marshes (see 

Sections 3.2.3.2 and 3.2.3.3). These closures would directly impact commercial fishermen and oysterers, 

and indirectly impact such downstream activities as shrimp processing facilities and oyster shucking 
Catastrophic Spill Event Analysis B-29 

houses. The mostly African-American communities of Phoenix, Davant and Point a la Hache in 

Plaquemines Parish are home to families with some of the few black-owned oyster leases, which because 

of freshwater diversion projects for coastal restoration have already been threatened (Mock, 2010). 

The Gulf Coast hosts multiple minority and low-income groups whose use of natural resources of the 

offshore and coastal environments make them vulnerable to fishing closures. While not intended as an 

inventory of the area’s diversity, we have identified several Gulf Coast populations of particular concern. 

An estimated 20,000 Vietnamese fishermen and shrimpers live along the Gulf Coast; by 1990, over 1 in 

20 Louisiana fishers and shrimpers had roots in Southeast Asia even though they comprised less than half 

a percent of the state’s workforce (Bankston and Zhou, 1996). Vietnamese account for about one-third of 

all the fishermen in the central Gulf of Mexico (Ravitz, 2010). Islaños, African Americans, and Native 

American groups are also engaged in commercial fishing and oystering. Historically, Vietnamese and 

African Americans have worked in the fish processing and oyster shucking industries. Shucking houses 

particularly, have provided an avenue into the mainstream economy for minority groups. 

Therefore, fishing closures during Phase 2 of a catastrophic spill impacting the central Gulf of 

Mexico would disproportionately affect such minority groups as the Vietnamese, Native Americans, 

African Americans, and Islaños (Hemmerling and Colten, 2003). 

4. ONSHORE CONTACT (PHASE 3) 

4.1. IMPACT-PRODUCING FACTORS AND SCENARIO

4.1.1. Duration 

The duration of the shoreline oiling is measured from initial shoreline contact until the well is capped 

or killed and the remaining oil dissipates offshore. The time needed to cap or kill a well may vary, 

depending on the well’s water depth. Depending on the spill’s location in relation to winds and currents 

and the well’s distance to shore, oil could reach the coast within 1 week to 1 month, based on evidence 

from previous spills in the Gulf of Mexico OCS. While it is assumed that the majority of spilled oil would 

dissipate offshore within 30 days of stopping the flow, some oil may remain in coastal areas until cleaned, 

as seen in Louisiana following the Deepwater Horizon blowout (The State of Louisiana, 2010a-d). 

4.1.1.1. Shallow Water 

Due to the distance from shore, oil spilled as a result of a blowout in shallow water could reach shore 

within 1-3 weeks and could continue until the well is killed or capped (1-3 months) and the oil dissipates 

offshore (1 month). Therefore, it is estimated that shoreline oiling would likely occur for 1-4 months 

following a catastrophic blowout. 

4.1.1.2. Deep Water 

As discussed in Section 3.1.1, intervention is more difficult and would take longer in deeper water. In 

general, most of the deep water in the Gulf of Mexico is located far from shore and therefore, it is 

assumed that oil would reach shore within 2-4 weeks. While most deep water is located far from shore, 

some areas of deep water are located relatively near shore so that oil could reach shore earlier. 

The length of shoreline oiled would continue to increase until the well is killed or capped (3-4 

months) and oil dissipates offshore (1 month). Therefore, shoreline oiling could occur for 3 to more than 

4 months following a catastrophic blowout. 

4.1.2. Volume of Oil 

In the event of a catastrophic spill, not all of the oil spilled would contact shore. The amount of oil 

recovered and chemically or naturally dispersed would vary. For example, the following are recovery and 

cleanup rates from previous high-volume, extended spills: 

 10-40 percent of oil recovered or cleaned up (including burned, chemically dispersed, 

and skimmed); 
B-30 Central Planning Area Supplemental EIS 

 25-40 percent of oil naturally dispersed, evaporated, or dissolved; and 

 20-65 percent of the oil remains available for biodegradation offshore or in shore 

contact 

In the case of the Deepwater Horizon incident, “it is estimated that burning, skimming and direct 

recovery from the wellhead removed one quarter (25%) of the oil released from the wellhead. One quarter 

(25%) of the total oil naturally evaporated or dissolved, and just less than one quarter (24%) was 

dispersed (either naturally or as a result of operations) as microscopic droplets into Gulf waters. The 

residual amount—just over one quarter (26%)—is either on or just below the surface as light sheen and 

weathered tar balls, has washed ashore or been collected from the shore, or is buried in sand and 

sediments” (Inter-agency, 2010a). 

For planning purposes, USCG estimates that 5-30 percent of oil will reach shore in the event of an 

offshore spill (33 C.F.R. Part 154, Appendix C, Table 2.). Using the USCG assumptions, a catastrophic 

spill could still result in a large amount of oil reaching shore. 

4.1.3. Length of Shoreline Contacted 

While larger spill volumes increase the chance of oil reaching the coast, other factors that influence 

the length and location of shoreline contacted include the duration of the spill and the well’s location in 

relation to winds, currents, and the shoreline. As seen with the Deepwater Horizon spill, as the spill 

continued, the length of oiled shoreline at any one time increased exponentially as follows: 

Duration of Spill Length of Shoreline Oiled1 

30 days 0-50 miles 

60 days 50-100 miles 

90 days 100-1,000 miles 

120 days >1,000 miles2

1

 Not cumulative. 

2

 Length was extrapolated. 

Dependent upon winds and currents throughout the spill event, already impacted areas could be reoiled. 

4.1.3.1. Shallow Water 

While a catastrophic spill from a shallow-water blowout is expected to be lower in volume than a 

deepwater blowout, as explained in Section 3.1, the site would be closer to shore, allowing less time for 

oil to be weathered, dispersed, and recovered. This could result in a more concentrated and toxic oiling of 

the shoreline. 

4.1.3.2. Deep Water 

While a catastrophic spill from a deepwater blowout is expected to have a much greater volume than 

a shallow-water blowout (see Section 3.1), the site would be farther from shore, allowing more time for 

oil to be weathered, dispersed, and recovered. This could result in a broader, patchier oiling of the 

shoreline. 

Translocation of the spilled oil via winds and currents is also a factor in the length of shoreline 

contacted. For example, oil could enter the Loop Current and then the Gulf Stream. However, the longer 

it takes oil to travel, the more it would degrade, disperse, lose toxicity, and break into streamers and 

tarballs (USDOC, NOAA, Office of Response and Restoration, 2010d). 

4.1.4. Severe Weather 

The Atlantic hurricane season runs from June 1st through November 30th, peaking in September. In 

an average Atlantic season, there are 11 named storms, 6 hurricanes, and 2 Category 3 or higher storms 

(USDOC, NOAA, National Weather Service, 2010a). In the event of a hurricane, vessels would evacuate 
Catastrophic Spill Event Analysis B-31 

the area, delaying response efforts, including the drilling of relief wells. The storm surge may push oil to 

the coastline and inland as far as the surge reaches, or the storm surge may remove the majority of oil 

from shore, as seen in some of the previous spills reviewed. 

Movement of oil during a hurricane would depend greatly on the track of the hurricane in relation to 

the slick. A hurricane’s winds rotate counter-clockwise. In general, a hurricane passing to the west of the 

slick could drive oil to the coast, while a hurricane passing to the east of the slick could drive the oil away 

from the coast. 

4.1.5. Onshore Cleanup Activities 

As described in Section 3.1, a large-scale response effort would be expected for a catastrophic 

blowout. The number of vessels and responders would increase exponentially as the spill continued. In 

addition to the response described in the Section 3.1.6, the following response is also estimated to occur 

once the spill contacts the shore. 

An exponential increase in the length of shoreline impacted would likely overwhelm response efforts. 

4.1.5.1. Shallow Water 

 There would be 5-10 staging areas established. 

 Weathering permitting, about 200-300 skimmers could be deployed near shore to 

protect coastlines. 

4.1.5.2. Deep Water 

 There would be 10-20 staging areas established. 

 Weather permitting, about 500-600 skimmers could be deployed near shore to protect 

coastlines. As seen in Louisiana following the Deepwater Horizon, a few hundred 

coastal skimmers could still be in operation a few months after the well is capped or 

killed (The State of Louisiana, 2010e). 

4.2. MOST LIKELY AND MOST SIGNIFICANT IMPACTS

The most recent EISs prepared by BOEMRE for oil and gas lease sales in the Gulf of Mexico identify 

in detail the potential impacts from reasonably foreseeable oil spills (USDOI MMS, 2007 and 2008). The 

most likely and significant onshore impacts caused by a catastrophic spill are described below. 

4.2.1. Physical Resources 

4.2.1.1. Air Quality 

As the spill nears shore, there would be low-level concentrations of odor-causing pollutants 

associated with evaporative emissions from the oil spill. These may cause temporary eye, nose, or throat 

irritation, nausea, or headaches, but the doses are not thought to be high enough to cause long-term harm 

(USEPA, 2010b). However, responders could be exposed to levels higher than OSHA permissible 

exposure levels (PEL) (U.S. Department of Labor, OSHA, 2010b). During the Deepwater Horizon oil 

spill, USEPA took air samples at various onshore locations along the length of the Gulf coastline. All 

except three measurements of benzene were below 3 parts per billion (ppb). The highest level was 91 ppb. 

During the Deepwater Horizon incident, air samples collected by BP, OSHA, and USCG near shore 

showed levels of benzene, toluene, ethylbenzene, and xylene that were mostly under detection levels. 

Among the 15,000 samples taken by BP, there was only one sample where benzene exceeded the OSHA 

Occupational PELs. All other sample concentrations were below the more stringent American 

Conference of Governmental Industrial Hygienists (ACGIH®) threshold limit values (TLVs) (U.S. 

Department of Labor, OSHA, 2010a). All measured concentrations of toluene, ethylbenzene, and xylene 

were well within the OSHA PELs and ACGIH TLVs. 
B-32 Central Planning Area Supplemental EIS 

4.2.1.2. Coastal Water Quality 

Water quality governs the suitability of waters for plant, animal, and human use. Water quality is 

important in the bays, estuaries, and nearshore coastal waters of the Gulf because these waters provide 

feeding, breeding, and/or nursery habitat for many commercially significant invertebrates and fishes, as 

well as sea turtles, birds, and marine mammals. A catastrophic spill would significantly impact coastal 

water quality in the Gulf of Mexico. In the Gulf of Mexico, water quality prior to the Deepwater Horizon

incident was rated as fair while sediment quality was rated as poor (USEPA, 2008). In addition, the 

coastal habit index, a rating of wetlands habitat loss, was also rated as poor. Both the sediment quality and 

the coastal habitat index affect water quality. 

Though response efforts would decrease the amount of oil remaining in Gulf waters and reduce the 

amount of oil contacting the coastline, significant amounts of oil would remain. Coastal water quality 

would be impacted not only by the oil, gas, and their respective components, but also to some degree 

from cleanup and mitigation efforts. Increased vessel traffic, hydromodification, addition of dispersants 

and methanol in an effort to contain, mitigate, or clean up the oil may also tax the environment. 

The use of dispersants as a response tool involves a tradeoff. The purpose of chemical dispersants is 

to facilitate the movement of oil into the water column in order to encourage weathering and biological 

breakdown of the oil (i.e., biodegradation) (NRC, 2005; Australian Maritime Safety Authority, 2010). 

Thus, the tradeoff is generally considered to be between the shoreline and surface of the water versus the 

water column and benthic resources (NRC, 2005). If the oil moves into the water column and is not on 

the surface of the water, it is less likely to reach sensitive shore areas (USEPA, 2010c). Since sea birds 

are often on the surface of the water or in shore areas, dispersants are also considered to be very effective 

in reducing the exposure of sea birds to oil (Australian Maritime Safety Authority, accessed 2010, http://

www.amsa.gov.au/Marine_Environment_Protection/National_plan/General_Information/

Dispersants_Information/FAQ_Oil_Spills_Dispersants.asp). In addition to dispersion being enhanced by 

artificial processes, oil my also be dispersed from natural processes. For instance, microbial metabolism 

of crude oil results in the dispersion of oil (Bartha and Atlas, 1983). Dispersion has both positive and 

negative effects. The positive effect is that the oil, once dispersed, is more available to be degraded. The 

negative effect is that the oil, once dispersed, is more available to microorganisms which temporarily 

increases the toxicity (Bartha and Atlas, 1983). Toxicity of dispersed oil in the environment will depend 

on many factors, including the effectiveness of the dispersion, temperature, salinity, the degree of 

weathering, type of dispersant and degree of light penetration in the water column (NRC, 2005). The 

toxicity of dispersed oil is primarily due to the toxic components of the oil itself (Australian Maritime 

Safety Authority, accessed 2010, http://www.amsa.gov.au/Marine_Environment_Protection/

National_plan/General_Information/Dispersants_Information/FAQ_Oil_Spills_Dispersants.asp). 

Oxygen and nutrient concentrations in coastal waters vary seasonally. The zone of hypoxia (depleted 

oxygen) on the Louisiana-Texas shelf occurs seasonally and is affected by the timing of freshwater 

discharges from the Mississippi and Atchafalaya Rivers, which carry nutrients to the surface waters. The 

hypoxic conditions continue until local wind-driven circulation mixes the water again. The 2010 hypoxic 

zone could not be linked to the Deepwater Horizon incident in either a positive or a negative manner 

(LUMCON, 2010). Nutrients from the Mississippi River fueled enhanced phytoplankton and attributed to 

the formation of the hypoxic zone. 

4.2.2. Biological Resources 

Recent EISs prepared by BOEMRE for oil and gas lease sales in the Gulf of Mexico detail the 

potential localized impacts to individuals from reasonably foreseeable oil spills. However, a catastrophic 

event, such as a high-volume, extended-duration spill resulting from a blowout has the potential to cause 

population level impacts, as described below. 

Dozens of Federal and State-listed threatened and endangered species could continue to be impacted 

during Phase 3 of a catastrophic oil spill as oil and response activities persist, including marine mammals, 

sea turtles, fish, and birds. Additional species could be impacted in extreme conditions (i.e., oil is pushed 

onto beaches or into rivers or marshes due to a hurricane) (USDOI, FWS, 2010a and 2010b). 
Catastrophic Spill Event Analysis B-33 

4.2.2.1. Coastal and Marine Birds 

Gulf coastal habitats are essential to the annual cycles of many species of breeding, wintering and 

migrating waterfowl, wading birds, shorebirds, and songbirds. For example, the northern Gulf Coast 

supports a disproportionately high number of beach-nesting bird species (USDOI, FWS, 2010c). Once oil 

contacts shore, a few dozen to over a hundred birds could be impacted daily by oiling and/or collection. 

By extrapolating the number of birds impacted as a result of the Deepwater Horizon incident, a spill 

lasting 120 days could result in direct mortality of over 7,000 birds (USDOI, FWS, 2010d). This number 

does not reflect total realized mortality but rather only the actual number of birds recovered to date. This 

number represents a small fraction of total bird mortality due to carcasses sinking, being scavenged, 

drifting outside the search zone, or simply going undetected due to wind, current, weather, and habitat 

factors (Ford et al., 1987, Piatt et al., 1990, Fowler and Flint, 1997; Flint et al., 1999; Wiese and 

Robertson, 2004; Byrd et al., 2009). In an early review of oil-related mortality for seabirds, Dunnett et al. 

(1982) provided an estimate of 10 percent, and 60 percent of the dead birds may be recovered under 

typical field conditions. Piatt and Ford (1996: Table 1) summarized recovery rates from 17 carcass-drift 

experiments, indicating a range of 0-59 percent of carcasses being recovered. Using data from the Exxon 

Valdez oil spill, Piatt and Ford (1996) estimated recovery rates from joint probability and Monte Carlos 

simulations of only 8.0 percent and 6.9 percent, respectively. 

Timing and location of the spill are the two primary factors for determining the severity of impacts on 

birds. The worst impacts to oiled birds or to those birds that have ingested oil with their prey would be if 

the oil spill occurs during the nesting season. An oil spill during nesting season could result in the loss of 

entire colonies of breeding birds on barrier islands surrounded by oil, along with the potential loss of all 

eggs and nestlings. Losses of shorebirds could occur through direct oiling of beaches on which nests are 

located, by oil covering the feeding sites near the nesting locations, or by the deaths of oiled parents, 

leaving eggs or hatchlings unprotected and unfed. 

Endangered and Threatened Birds 

Two species listed as endangered or threatened by the U.S. Fish and Wildlife Service that could be 

impacted by a catastrophic oil spill are the endangered least tern (Sterna antillarum) and the piping plover 

(Charadrius melodus). The Midwest Population of piping plovers, which nests along the Great Lakes, is 

listed as endangered while the Atlantic Coast and Northern Great Plains Populations are listed as 

threatened. The critical habitat for the plover is found within the wintering area which includes areas 

along the Gulf Coast from Texas to Florida (LeDee et al., 2008:Figure 1; Haig et al., 2005:Figure 1) 

where they feed on aquatic insects, invertebrates, and small crustaceans along the advancing and 

retreating water line of the beaches. Unknown numbers of piping plovers could therefore become oiled or 

have their feeding areas oiled if a spill occurred during the time of year, roughly October through March, 

when plovers are present (Haig et al., 2005: fig. 1, table 2). Least terns breed in isolated, smaller colonies 

along the Gulf Coast (primarily in Texas and Louisiana) and apparently in greater numbers at more inland 

riverine sites (e.g., Rio Grande River, Texas; Lower Mississippi River, Tennessee) (Kirsch and Sidle, 

1999; Szell and Woodrey, 2003), so oiling that occurs during the nesting season could not only affect 

least tern feeding areas (least terns are piscivorous) but also cause oiling and loss of eggs and young. 

4.2.2.2. Fish, Fisheries, and Essential Fish Habitat 

Estuarine-dependent fish species spawn on the continental shelf. transport eggs, larvae, or juveniles 

back to the estuary nursery grounds, and the adults migrate back to the sea for spawning (Deegan, 1989; 

Beck et al., 2001). All of these estuaries in the GOM are extremely important nursery areas and 

considered EFH for fish and aquatic life (Beck et al., 2001). Oiling of these areas, depending on the 

severity, can destroy nutrient-rich marshes and erode coastlines that have been significantly damaged by 

recent hurricanes. 

The Gulf of Mexico supports a wide variety of finfish, and most of the commercial finfish resources 

are linked either directly or indirectly to the estuaries that ring the Gulf of Mexico. Darnell et al. (1983) 

observed that the density distribution of fish resources in the Gulf was highest nearshore off of the central 

Gulf Coast. For all seasons, the greatest abundance occurred between Galveston Bay and the mouth of the 

Mississippi River. Monthly ichthyoplankton collections over the years 2004-2006 offshore of Alabama 
B-34 Central Planning Area Supplemental EIS 

have confirmed that peak seasons for ichthyoplankton concentrations on the shelf are spring and summer 

(Hernandez et al., 2010). Therefore, if a catastrophic blowout occurs in the spring and summer seasons, it 

could cause greater harm to fish populations, not just individual fish. 

Oyster beds could be damaged by freshwater diversions that release tens of thousands of cubic feet of 

freshwater per second for months in an effort to keep oil out of the marshes. Adult oysters survive well 

physiologically in salinities from those of estuarine waters (about 7.5 parts per thousand sustained) to full 

strength seawater (Davis, 1958). While oysters may tolerate small changes in salinity for a few weeks, a 

rapid decrease in salinity over months would kill oysters. In the event of a catastrophic oil spill, the year’s 

oyster production would be lost because of exposure to freshwater and/or oil. . . . Depending on the 

severity, oyster beds could take 2-5 years to recover (Burdeau, 2010). 

4.2.2.3. Marine Mammals 

Section 3.2.2 discusses the most likely and most significant impacts to the offshore marine mammal 

community. A high-volume oil spill lasting 120 days could directly impact almost 100 species of marine 

mammals. As the spill enters coastal waters, manatees and coastal and estuarine dolphins would be the 

most likely to be impacted. 

Manatees primarily inhabit open coastal (shallow nearshore) areas and estuaries, and they are also 

found far up in freshwater tributaries. During warmer months, manatees are common along the Gulf 

Coast of Florida from the Everglades National Park northward to the Suwannee River in northwestern 

Florida, and they are less common farther westward. In winter, the Gulf of Mexico subpopulations move 

southward to warmer waters. The winter range is restricted to waters at the southern tip of Florida and to 

waters near localized warm-water sources, such as power plant outfalls and natural springs in west-central 

Florida. Manatees are infrequently found as far west as Texas (Powell and Rathbun, 1984; Rathbun et al., 

1990; Schiro et al., 1998). If a catastrophic oil spill reached the Florida coast when manatees were in or 

near coastal waters, the spill could have population-level effects. 

It is possible that manatees could occur in coastal areas where vessels traveling to and from the spill 

site could affect them. A manatee present where there is vessel traffic could be injured or killed by a 

vessel strike (Wright et al., 1995). Due to the large number of vessels responding to a catastrophic spill 

both in coastal waters and traveling through coastal waters to the offshore site, manatees would have an 

increased risk of collisions with boats. Vessel strikes are the primary cause of death of manatees. 

There have been no experimental studies and only a few observations suggesting that oil impacts have 

harmed any manatees (St. Aubin and Lounsbury, 1990). Types of impacts to manatees and dugongs from 

contact with oil include (1) asphyxiation due to inhalation of hydrocarbons, (2) acute poisoning due to 

contact with fresh oil, (3) lowering of tolerance to other stress due to the incorporation of sublethal 

amounts of petroleum components into body tissues, (4) nutritional stress through damage to food 

sources, and (5) inflammation or infection and difficulty eating due to oil sticking to the sensory hairs 

around their mouths (Preen, 1989, in Sadiq and McCain, 1993; Australian Maritime Safety Authority, 

2003). For a population whose environment is already under great pressure, even a localized incident 

could be significant (St. Aubin and Lounsbury, 1990). Spilled oil might affect the quality or availability 

of aquatic vegetation, including seagrasses, upon which manatees feed. The 2009 Stock Assessment 

Report (USDOI, FWS, 2009) for the Florida stock of west Indian manatees estimates that there is a 

minimum population estimate of 3,802 individuals based on a single synoptic survey of warm-water 

refuges in January 2009. The manatee’s potential biological removal (PBR) is the maximum number of 

animals, not including natural mortalities, that may be removed from the population or stock while 

allowing that stock to reach or maintain its optimum sustainable population and is approximately 12 

individuals. Therefore, if a catastrophic spill and response vessel traffic occurred near manatee habitats in 

the eastern Gulf of Mexico, population level impacts could occur, because the possibility exists for the 

number of mortalities to exceed PBR. 

Bottlenose dolphins were the most affected species of marine mammals from the Deepwater Horizon

oil spill. Ninety to 96 dolphins were collected; 4 bottlenose dolphins were alive, 86 were dead. (The other 

species of dolphin affected from the Deepwater Horizon spill was spinner dolphins). Bottlenose dolphins 

can be found throughout coastal waters in the Gulf of Mexico. Like manatees, dolphins could be affected, 

possibly to population level, by a catastrophic oil spill if it reaches the coast (as well as affecting them in 
Catastrophic Spill Event Analysis B-35 

the open ocean), through direct contact, inhalation, ingestion, and stress, as well as through collisions 

with cleanup vessels. 

4.2.2.4. Sea Turtles 

Out of the five species of sea turtle that occur in the Gulf of Mexico, only three nest in this area. The 

largest nesting location for the Kemp’s ridley sea turtle is in Rancho Nuevo, Mexico, but they also nest in 

Texas. Loggerhead sea turtles nest in all states around the Gulf of Mexico. There are also records of 

nesting colonies of hawksbill sea turtles in the Yucatan Peninsula of Mexico (Plotkin et al., 1995). 

Kemp’s ridley, loggerhead, and hawksbill sea turtles are therefore most likely to be affected by a 

catastrophic oil spill when there is onshore contact. 

Female sea turtles emerge during the warmer summer months to nest Seasonally, females must 

emerge periodically from the ocean to nest on beaches. Thousands of sea turtles nest along the Gulf 

Coast, and turtles could build nests on oiled beaches. Nests could also be disturbed or destroyed by 

cleanup efforts. Untended booms could wash ashore and become a barrier to sea turtles adults and 

hatchlings (USDOC, NOAA, 2010e). Hatchlings, with a naturally high mortality rate, could walk through 

oiled sand and swim through oiled water to reach preferred habitats of sargassum floats. Response efforts 

could include mass movement of eggs from hundreds of nests or thousands of hatchlings from Gulf Coast 

beaches to the east coast of Florida or to the open ocean to prevent hatchlings entering oiled waters 

(Jernelöv and Lindén, 1981; USDOI, FWS, 2010e). Due to poorly understood mechanisms that guide 

female sea turtles back to the beaches where they hatched, it is uncertain if relocated hatchlings would 

eventually return to the Gulf Coast to nest (Florida Fish and Wildlife Conservation Commission, 2010). 

Therefore, shoreline oiling and response efforts may affect future population levels and reproduction 

(USDOI, NPS, 2010). Sea turtle hatchling exposure to, fouling by, or consumption of tarballs persisting 

in the sea following the dispersal of an oil slick would likely be fatal. 

4.2.2.5. Terrestrial Mammals and Reptiles 

Beach Mice 

Seven subspecies of the field mouse, collectively known as beach mice, live along the Gulf Coast. 

Five subspecies of beach mice (Alabama, Perdido Key, Choctawhatchee, St. Andrew, and Anastasia 

Island) are listed as State and federally endangered; the southeastern beach mouse is listed as federally 

threatened; and the Santa Rosa beach mouse is a Federal species of concern. Beach mice are restricted to 

the coastal barrier sand dunes along the Gulf Coast of Alabama and Florida. Erosion caused by the loss of 

vegetation due to oiling would likely cause more damage than the direct oiling of beach mice, due to 

degradation or loss of habitat. In addition, vehicular traffic and activity associated with cleanup can 

trample or bury beach mice nests and burrows or cause displacement from preferred habitat. Improperly 

trained personnel and vehicle and foot traffic during shoreline clean up of a catastrophic spill would 

disturb beach mouse populations and would degrade or destroy habitat. 

The Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice are already designated as 

protected species under the Endangered Species Act (ESA) because of the loss of coastal habitat (USDOI, 

MMS, 2007). The species’ coastal habitat is designated as their critical habitat. For example, the 

endangered Alabama beach mouse’s (Peromyscus polionotus ammobates) habitat is 1,211 acres of frontal 

dunes covering just 10 miles of shoreline designated as critical habitat (USDOI, FWS, 2007). Critical 

habitat is the specific geographic areas that are essential for the conservation of a threatened or 

endangered species. With the potential oiling of over 1,000 miles of shoreline, the entire critical habitat 

for a subspecies of beach mice could be completely oiled. Thus, destruction of the remaining habitat due 

to a catastrophic spill and cleanup activities would increase the threat of extinction of several subspecies 

of beach mice.

Diamondback Terrapin 

The Texas diamondback terrapin (Malaclemys terrapin littoralis) and the Mississippi diamondback 

terrapin (Malaclemys terrapin pileata) are two subspecies of terrapin that occur in the Gulf of Mexico 
B-36 Central Planning Area Supplemental EIS 

andare Federal species of concern. The former’s range runs from Louisiana through Texas, while the 

latter’s includes Louisiana, Mississippi, Alabama, and Florida (USDOI, FWS, 2010f). Terrapins inhabit 

brackish waters including coastal marshes, tidal flats, creeks, and lagoons behind barrier beaches (Hogan, 

2003). Their diet consists of fish, snails, worms, clams, crabs, and marsh plants (Cagle, 1952). Spending 

most of their lives at the aquatic-terrestrial boundary in estuaries, terrapins are susceptible to habitat 

destruction from oil spill cleanup efforts as well as direct contact with oil. However, most impacts cannot 

be quantified at this time. Even after the oil is no longer visible, terrapins may still be exposed while they 

forage in the salt marshes lining the edges of estuaries where oil may have accumulated under the 

sediments and within the food chain. Terrapin nests can also be disturbed or destroyed by cleanup efforts. 

Chronic effects from oil contact including lethal or sublethal oil-related injuries, such as . . . may persist 

through the generations, potentially reducing population levels. 

4.2.2.6. Coastal Habitats 

A spill from a catastrophic blowout lasting up to 120 days could impact over 1,000 miles of shoreline. 

Shoreline oiling would vary between heavy, moderate, light, and occasional tarballs. Due to the length of 

shoreline that could potentially be oiled and the sensitivity of the Gulf Coast, a high-volume, extendedduration spill could cause extensive habitat degradation. Loss of vegetation could lead to erosion and 

permanent landloss. 

In some previous spills reviewed, a strong storm removed the majority of oil from shore. However, 

storm surges may carry oil into the coastline and inland as far as the surge reaches. In addition, four 

significant hurricanes (Katrina, Rita, Gustav, and Ike) have made landfall along the Texas/Louisiana coast 

in the last 5 years, greatly degrading the coastal beaches, marshes, and barrier islands, making them more 

susceptible to a catastrophic spill. 

Coastal Barrier Beaches and Associated Dunes 

Barrier islands make up more than two-thirds of the northern Gulf of Mexico shore. Each of the 

barrier islands is either high profile or low profile, depending on the elevations and morphology of the 

island (Morton et al., 2004). The distinguishing characteristics of the high and low profile barriers relates 

to the width of the islands along with the continuity of the frontal dunes. Low profile barriers are narrow 

with discontinuous frontal dunes easily overtopped by storm surge which makes the island susceptible to 

over wash and secondarily to erosion. This over wash can create channels to bring sand onto the island or 

into lagoons formed on these islands. High profile barriers islands are generally wider than the low 

profile islands and have continuous, vegetated, frontal dunes with elevations high enough to prevent over 

wash from major storm surge and therefore are less susceptible to erosion. The sand stored in these high 

profile dunes allows the island to withstand prolonged erosion and therefore prevent breaching which 

could result in damaging the island core. 

As a result of a catastrophic spill, many of the barrier islands and beaches would receive varying 

degrees of oiling. Oil disposal on sand and vegetated sand dunes would have little deleterious effects on 

the existing vegetation or on the recolonization of the oiled sands by plants (Webb, 1988). The depth of 

oiling would be variable, based on the wave environment and sediment source at a particular beach head. 

Layering of oil and sand could occur if it was not cleaned before another tidal cycle. However, most areas 

of oiling are expected to be light and sand removal during cleanup activities should be minimized. In 

areas designated as natural wilderness areas e.g., Breton National Wildlife National Refuge and Gulf 

Islands National Seashore land managers may require little to no disruption of the natural system. In 

these environments it is preferred to let the oil degrade naturally without aggressive and intrusive cleanup 

procedures. Manual rather than mechanized removal techniques will be used in these areas and only if 

heavy oiling has occurred. The exceptions occur in areas designated as natural wilderness areas (e.g., 

Breton National Wildlife National Refuge and Gulf Islands National Seashore) where the land managers 

want as little disruption to the “natural” system as possible. Thus, these areas may not be treated as 

thoroughly as other shorelines. 

Once oil has reached the beaches and barrier islands and becomes buried or sequestered, it becomes 

difficult to treat. During wave events when the islands and beaches erode, the oil can become remobilized 

and transported. Thus, the fate of oil is not as simple as either reaching land, becoming sequestered or 
Catastrophic Spill Event Analysis B-37 

being treated, but must be considered in terms of a continuing process of sequestration, remobilization, 

and transport. 

For spilled oil to move onto beaches or across dunes, strong southerly winds must persist for an 

extended time prior to or immediately after the spill to elevate water levels. Strong winds, however, 

would reduce the impact severity at a landfall site because they would accelerate the processes of oil-slick 

dispersal, spill spreading, and oil weathering. 

Due to the distance of beaches from deepwater blowout and the combination of weathering and 

dispersant treatment of the oil offshore, the toxicity of the oil reaching shore should be greatly reduced, 

thereby minimizing the chances of irreversible damage to the impacted areas. A blowout in shallower 

waters near shore may have equal or greater impacts due to a shorter period of weathering and dispersion 

prior to shoreline contact, even though a smaller volume of spilled oil is expected. 

Vessel traffic in close proximity to barrier islands has been shown to move considerably more bottom 

sediment than tidal currents, thus increasing coastal and barrier island erosion rates. If staging areas are in 

close proximity to these islands, recovery time of the barrier islands could be greatly extended due to the 

magnitude of vessels responding to a catastrophic spill. 

Wetlands 

Coastal wetland habitats in the Gulf of Mexico occur as bands around waterways, broad expanses of 

saline, brackish, and freshwater marshes, mud and sand flats, and forested wetlands of cypress-tupelo 

swamps and bottomland hardwoods. A spill from a catastrophic blowout could oil a few to several 

hundreds of acres of wetlands depending on the depth of inland penetration (Burdeau and Collins, 2010). 

This would vary from moderate to heavy oiling. 

The NOAA Environmental Sensitivity Index (ESI) ranks shorelines according to their sensitivity to 

oil, the natural persistence of oil, and the expected ease of cleanup after an oil spill. These factors cause 

oil to persist in coastal and estuarine areas (DOI, MMS, 2010). According to the ESI, the most sensitive 

shoreline types (i.e., sheltered tidal flats, vegetated low banks, salt/brackish-water marshes, freshwater 

marshes/swamps, and scrub-shrub wetlands) tend to accumulate oil and are difficult to clean, thus causing 

oil to persist in these coastal and estuarine areas (USDOI, MMS, 2010). 

Precautions such as oil booms, skimmer ships, and barge barriers would be deployed to protect the 

beaches and the wetlands behind them or on the beach fringe from oil. However, if not maintained, these 

booms can cause significant harm to fragile wetlands. In most cases, the beach face would take the most 

oil; however, in areas where the marsh is immediately adjacent to the beach face or embayments, or in the 

case of small to severe storms, marshes would be oiled. For example, in Alabama, Mississippi and 

Florida, severe weather could push oil into the tidal pools and back beach areas that support tidal marsh 

vegetation. 

Previous studies of other large spills have shown that when oil has a short residence time in the marsh 

and it is not incorporated into the sediments, the marsh vegetation has a good chance of survival, even 

though aboveground die-off of marsh vegetation may occur (Mendelssohn et al., 2002). However, if 

reoiling occurs after the new shoots from an initial oiling are produced, such that the new shoots are 

killed, then the marsh plants may not have enough stored energy to produce a second round of new 

shoots. Longer term damage may result from continued reoiling than from a temporally continuous oiling 

(Lin et al, 2002; Lin and Mendelssohn, 2009). Other studies noted the utilization of dispersants in the 

proper dosages results in a reduction in marsh damage from oiling (Lin and Mendelssohn, 2009).). The 

works of several investigators (Webb et al., 1981 and 1985; Alexander and Webb, 1983 and 1987; Lytle, 

1975; Delaune et al., 1979; Fischel et al., 1989) evaluated the effects of potential spills to area wetlands. 

For wetlands along the central Louisiana coast, the critical oil concentration is assumed to be 0.025 gallon 

per ft2

 (1.0 liter per m2) of marsh. Concentrations less than this may cause diebacks for one growing 

season or less, depending upon the concentration and the season during which contact occurs. The 

duration and magnitude of a spill resulting from a catastrophic blowout could result in concentrations 

above this critical level and would result in longer-term effects to wetland vegetation, including some 

plant mortality and loss of land. 

Due to the distance of deep water from shore, the possibility of a spill from a deepwater blowout 

reaching coastal wetlands with the toxicity to significantly impact the coastal wetlands is low due to the 

response procedures implemented during a catastrophic spill. The utilization of nearshore booming 
B-38 Central Planning Area Supplemental EIS 

protection for beaches and wetlands, in combination with offshore skimming, burning, and dispersal 

treatments for the oil near the spill site, would result in capture and detoxification of the majority of oil 

reaching shore. Therefore, a spill from a shallow-water blowout is more likely to contribute to wetland 

damage. 

The impact of oil cleanup can result in additional impacts to wetlands, if not done properly. 

Aggressive onshore and marsh cleanup methods have not yet been utilized and probably would not be 

initiated until the oil spill has been stopped. Depending on the marsh remediation methods used, further 

impacts to the wetlands may occur from cleanup activities. 

Submerged Vegetation 

Approximately 500,000 hectares (1.25 million acres) of submerged seagrass beds are estimated to 

exist in exposed, shallow coastal waters and embayments of the northern Gulf of Mexico, and over 80 

percent of this area is in Florida Bay and Florida coastal waters (Beck et al., 2006; Carlson and Madley, 

2006). Submerged vegetation distribution depends on an interrelationship between a number of 

environmental factors that include temperature, water depth, turbidity, salinity, turbulence, and substrate 

suitability (Sheridan and Minello, 2003). Marine seagrass beds generally occur in shallow, relatively 

clear, protected waters with predominantly sand bottoms (Short et al., 2001). Freshwater submerged 

aquatic vegetation (SAV) species occur in the low-salinity waters of coastal estuaries (Castellanos and 

Rozas, 2001). Seagrasses and freshwater SAVs provide important habitat for immature shrimp, black 

drum, spotted sea trout, juvenile southern flounder, and several other fish species and provide a food 

source for species of wintering waterfowl (Castellanos and Rozas, 2001; Short et al., 2001; Caldwell, 

2003). These areas would have considerable impact from various cleanup efforts, such as increased vessel 

traffic. Although many of the beds are protected by extensive barrier islands, severe storms can cause 

inundation and overwashing of these islands, resulting in oiling of the seagrass beds if the storm occurred 

during an oil spill. In addition, boom anchors could damage seagrass beds (USDOC, NOAA, 2010e). It is 

assumed that there would be a decrease in submerged vegetation and a negative impact on the bed 

communities in a highly affected area. If bays and estuaries accrue oil, there is an assumption that there 

would be a decrease in seagrass cover and negative community impacts. Depending on the species and 

environmental factors, seagrasses may exhibit minimal impacts from a spill; however, communities 

within the beds could accrue greater negative outcomes (Jackson et al., 1989; Taylor et al., 2006). 

Community effects could range from direct mortality due to smothering or indirect mortality from loss of 

food sources and loss of habitat due to a decrease in ecological performance of the entire system (Zieman 

et al., 1984). 

4.2.3. Socioeconomic Resources 

4.2.3.1. Onshore Archaeological Resources 

Regardless of the water depth in which the catastrophic blowout occurs, it is assumed that more than 

1,000 miles of shoreline could be oiled to some degree. Onshore prehistoric and historic sites would be 

impacted to some extent by a high-volume spill from a catastrophic blowout that reaches shore. Sites on 

barrier islands could suffer the heaviest impact (McGimsey, personal communication, 2010). A few 

prehistoric sites in Louisiana, located inland from the coastline in the marsh and along bayous, could 

experience some light oiling. As discussed above, impacts would include the loss of ability to accurately 

date organic material from archeological sites due to contamination. Efforts to prevent coastal cultural 

resources from becoming contaminated by oil would likely be overwhelmed in the event of a hurricane 

and by the magnitude of shoreline impacted. The most significant damage to archaeological sites could be 

related to cleanup and response efforts. Fortunately, important lessons were learned from the Exxon 

Valdez spill in Alaska in 1989, in which the greatest damage to archaeological sites was related to cleanup 

activities and looting by cleanup crews rather than from the oil itself (Bittner, 1996). As a result, cultural 

resources were recognized as significant early in the response, and archaeologists are, at present, 

embedded in Shoreline Cleanup Assessment Teams (SCAT) and are consulting with cleanup crews. 

Historic preservation representatives are present at both the Joint Incident Command as well as each Area 

Command under the general oversight of the National Park Service to coordinate response efforts (Odess, 

personal communication, 2010). Despite these efforts, some archaeological sites suffered damage from 
Catastrophic Spill Event Analysis B-39 

looting or from spill clean-up activities (most notably the parade ground at Fort Morgan) (Odess, personal 

communication, 2011). 

4.2.3.2. Commercial Fishing 

In addition to closures in Federal waters, portions of individual State waters would also be closed to 

commercial fishing. The economic impacts of closures on commercial fishing are complicated to predict 

because it is dependent on season and would vary by fishery. If fishers cannot make up losses in the 

remainder of the season, a substantial part of their annual income will be lost. In some cases, commercial 

fishers may move to areas still open to fishing, but at a greater cost due to longer transits. 

4.2.3.3. Recreational Fishing 

In addition to closures in Federal waters, portions to of individual State waters would also be closed 

to recreational fishing. More than 67 percent of the total Gulf catch came on trips that fished primarily in 

inland waters (Pritchard, 2009). In 2008, over 24 million recreational fishing trips were taken, which 

generated about $12 billion in sales, over $6 billion in value added impacts, and over 100,000 jobs 

(USDOC, NOAA, NMFS, 2010b). The majority of recreational fishing occurs in the summer months. 

During this time, scheduled fishing tournaments are held and would be hard to reschedule. If the spill 

affected the summer months, normal direct income and indirect income to the communities that host these 

tournaments would be lost for that year. If a catastrophic spill occurs in the summer, the majority of 

recreational fishing trips would not occur and economic benefits they generate would be lost for that year. 

4.2.3.4. Tourism and Recreational Resources 

Tourism and recreation are integral components of the economy of the Gulf of Mexico. Visitors to 

Texas, Louisiana, Mississippi, Alabama, and Florida spent approximately $145 billion in 2008. (U.S. 

Travel Association (2008)). This spending helped to support approximately 2.4 million jobs in 

recreation-based industries statewide (U.S. Dept. of Labor, 2010a). Roughly 600,000 of these jobs are in 

counties that are directly along the coast, making them particularly vulnerable to a catastrophic event and 

the likely associated decrease in tourism. Recreation jobs account for 14.8 percent of Gulf Coast 

employment, greater than the national average of 12.4 percent (QCEW Fact Sheet). The coastal counties 

and parishes that have the highest concentration of recreation workers (over 10,000 workers) in each state 

are as follows: Cameron, Nueces, and Galveston Counties (Texas); Jefferson and Orleans 

Parishes(Louisiana); Harrison County (Mississippi); Mobile and Baldwin Counties (Alabama); and 

Escambia, Okaloosa, Bay, Pasco, Pinellas, Hillsborough, Manatee, Sarasota, Lee, Collier, Broward, and 

Miami-Dade Counties (Florida). Gulf Coast recreational employment is reasonably cyclical, with the peak 

months during the past few years occurring between March and June (U.S. Dept. of Labor, 2010b). 

A catastrophic spill has the potential to significantly impact the Gulf Coast recreation and tourism 

industries. The water-dependent and beach-dependent components of these industries would be 

particularly vulnerable. This is particularly true for some of the nature parks and island resources directly 

along the coast, such as Padre Island National Seashore (Texas), Dauphin Island (Alabama), and the Gulf 

Islands National Seashore (Mississippi/Florida). Kaplan and Whitman (2008) attempt to isolate the 

economic significance of the recreational resources in the Gulf of Mexico that are particularly relevant to 

OCS oil and gas activities. They found roughly 60,000 jobs that were dependent on these activities in 

2005, although there is uncertainty with this estimate, due to measurement issues and due to events that 

have occurred since their data collection period (most notably Hurricane Katrina). 

In analyzing the potential impacts of a catastrophic spill, one must also consider the range of activities 

that depend on the base resources that may be affected. For example, the restaurant and lodging industries 

are particularly important to the Gulf economy. They are also sensitive to general tourism trends in any 

particular area. However, the economic impacts on these sectors from a spill may be partially offset due 

to an influx of cleanup and relief workers. Finally, one should consider the economic context in which a 

catastrophic event occurs. The Deepwater Horizon incident occurred in the context of an economy that 

was only beginning to recover from a very deep recession. In difficult economic times, recreation workers 

may be more prone to being laid off in response to a catastrophic event. Workers may also find it more 

difficult to transition between jobs, which can increase the severity of the economic effects. In a 
B-40 Central Planning Area Supplemental EIS 

recession, tourism also may be more sensitive both to actual damage and to perceptions of economic 

problems within a region. 

4.2.3.5. Employment and Demographics 

By the end of a catastrophic spill, up to 50,000 personnel would be expected to respond to protect the 

shoreline and wildlife and to cleanup vital coastlines. The degree to which new cleanup jobs offset job 

losses would vary greatly from county to county (or parish to parish). However, these new jobs would not 

make up for lost jobs, in terms of dollar revenue. In most cases, cleanup personnel are paid less (e.g., $15-

$18 an hour compared with roughly $45 an hour on a drilling rig), resulting in consumers in the region 

having reduced incomes overall and thus, investing less money in the economy (Aversa, 2010). 

Permanent demographic impacts are unlikely from these temporary jobs. 

There would be additional economic impacts to tourism and both recreational and commercial 

fishing, as discussed in Sections 4.2.3.2 through 4.2.3.4 above. 

4.2.3.6. Land Use and Coastal Infrastructure 

In the event of a catastrophic spill, impacts on land use and infrastructure would be temporary and 

variable in nature. These impacts include land use in staging areas, waste disposal locations and 

capacities, and potential delays due to vessel decontamination stations near ports, as described below. 

Up to 20 staging areas and as many as 50,000 responders would likely result in increased traffic 

congestion and some possible competing land use issues near the staging areas, depending on the real 

estate market at the time of the event. Some infrastructure categories, such as vessels, ports, docks and 

wharves would likely become very engaged in response activities and this could result in a shortage of 

space and functionality at infrastructure facilities if ongoing drilling activities were simultaneously 

occurring. However, if a drilling suspension was enacted, like the Deepwater Horizon incident, 

conflicting demands on infrastructure facilities would likely fail to materialize (Dismukes, personal 

communication, 2010a). 

In the category of waste disposal, the impacts would be more visible as thousands of tons of oily 

liquid and solid wastes from the oil-spill cleanup are disposed of in onshore landfills. The USEPA the 

U.S. Coast Guard would likely issue solid waste management directives to address the issue of 

contaminated materials and solid or liquid wastes that are recovered as a result of cleanup operations 

(USEPA, 2010d and 2010e). 

For navigation and port use, there is also the potential for delays in cargo handling and slow vessel 

traffic due to decontamination operations at various sites along the marine transportation system 

(USDOT, 2010). However, most cleanup activities would be complete within a year of the event, so 

impacts would be expected to be limited in duration (Dismukes, personal communication, 2010b). 

4.2.3.7. Environmental Justice 

While most coastal populations of along the Gulf of Mexico coast are not generally minority or low 

income, several communities on the coasts of St. Mary, Lafourche, Terrebonne, St. Bernard, and 

Plaquemines Parishes have minority or low-income population percentages that are higher than their 

respective state averages. are predominately Native American, Islaños, or African American. For 

example, a few counties or parishes along the Gulf Coast have more than a 2-percent Native American 

population (USDOI, MMS, 2007); about 2,250 Houma Indians (a State of Louisiana recognized tribe) are 

concentrated in Lafourche Parish, Louisiana comprising 2.4% of the parish’s population, and about 800 

Chitimacha (a federally recognized tribe) make up 1.6% of St. Mary Parish’s population. While these 

aren’t significant numbers on their own, viewed in the context of Louisiana’s overall 0.6 percent Native 

American average, these communities take on greater environmental justice importance. 

Gulf Coast minority and low-income groups are particularly vulnerable to the coastal impacts of a 

catastrophic oil spill due to their dependence on the natural resources in the offshore and coastal 

environments. Besides their economic reliance on commercial fishing and oystering, coastal low-income 

and minority groups rely heavily on these fisheries and other traditional subsistence fishing, hunting, 

trapping, and gathering activities to augment their diets and household incomes (see Hemmerling and 

Colton, 2003, for an evaluation of environmental justice considerations for south Lafourche Parish). 
Catastrophic Spill Event Analysis B-41 

Regular commuting has continued this reliance on the natural resources of the coastal environments even 

when populations have been forced to relocate because of landloss and the destruction from recent 

hurricane events. 

State fishery closures due to a catastrophic oil spill would disproportionately affect minority and lowincome groups. Shoreline impacts would generate additional subsistence-related effects. Therefore, these 

minority groups would be disproportionately affected if these coastal areas were impacted by a 

catastrophic spill and the resulting response. 

5. POST-SPILL, LONG-TERM RECOVERY (PHASE 4) 

5.1. IMPACT-PRODUCING FACTORS AND SCENARIO

During the final phase a catastrophic blowout and spill, it is presumed that the well has been capped 

or killed and cleanup activities are concluding. While it is assumed that the majority of spilled oil would 

be dissipated within 30 days of stopping the flow (Inter-agency, 2010a), oil has the potential to persist in 

the environment long after a spill event and has been detected in sediment 30 years after a spill (USDOI, 

FWS, 2004). On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt marshes, oil 

may seep into the muddy bottoms (USDOI, FWS, 2010g). 

5.2. MOST LIKELY AND MOST SIGNIFICANT IMPACTS

At this point in the scenario, the spill has been stopped and long-term recovery begins. There is a 

great deal of uncertainty regarding the long-term impacts of a catastrophic spill in the Gulf of Mexico. 

The most likely and most significant impacts, as described below, will likely relate to the continued 

exposure of organisms to the spilled oil, oil components, and dispersants remaining in the air, water, and 

sediments, as well as the effects of continued cleanup efforts. 

A catastrophic spill can have long-term impacts on Gulf of Mexico ecosystems. An ecosystem is a 

geographically specified system of organisms, including humans, their environment, and the processes 

that control their dynamics. Ecosystems involve complex connections between organisms, their 

environment, and the processes that drive the system (USDOC, NOAA, 2010f). In some cases, marine 

ecosystems may take decades to fully recover or may recover to alternative states (Ragen, 2010). 

5.2.1. Physical Resources 

5.2.1.1. Air Quality 

There would be some residual air quality impacts after the well is capped or “killed”. As most of the 

oil would have been burned, evaporated, or weathered over time, air quality would return to pre-oil spill 

conditions. While impacts to air quality are expected to be localized and temporary, as discussed in 

Sections 2.2.1.1, 3.2.1.1, and 4.2.1.1, adverse effects that may occur from the exposure of humans and 

wildlife to air pollutants could have long-term consequences. 

5.2.1.2. Coastal and Offshore Water Quality 

The leading source of contaminants that impairs coastal water quality in the Gulf of Mexico is urban 

runoff. Urban runoff can include suspended solids, heavy metals, pesticides, oil, grease, and nutrients 

(such as from lawn fertilizer). Urban runoff increases with population growth, and the Gulf Coast region 

has experienced a 103 percent population growth since 1970 (USDOC, NOAA, NOS, 2008). Other 

pollutant source categories include (1) agricultural runoff, (2) municipal point sources, (3) industrial 

sources, (4) hydromodification (e.g., dredging), and (5) vessel sources (e.g., shipping, fishing, and 

recreational boating). The NRC (2003; Table I-4, p. 237) estimated that, on average, approximately 

26,324 barrels of oil per year entered Gulf waters from petrochemical and oil refinery industries in 

Louisiana and Texas. The Mississippi River introduced approximately 3,680,938 barrels/year (NRC, 

2003; Table I-9, p.242) into the waters of the Gulf. Hydrocarbons also enter the Gulf of Mexico through 

the result of natural seeps in the Gulf of Mexico at a rate of approximately 980,392 barrels per year (a 

range of approximately 560,224-1,400,560 barrels/year) (NRC, 2003; p. 191). Produced water (formation 
B-42 Central Planning Area Supplemental EIS 

water) is, by volume, the largest waste stream from the oil and gas industry that enters Gulf waters. The 

NRC has estimated the quantity of oil in produced water entering the Gulf per year to be 473,000 bbl 

(NRC, 2003; p. 200, Table D-8).2

 These sources total about 5.5 million barrels of oil per year that 

routinely enters Gulf of Mexico waters. In comparison, a catastrophic spill of 30,000-60,000 barrels per 

day for 90-120 days would spill a total of 2.7-7.2 million barrels of oil. When added to the other sources 

of oil listed above, this would result in a 48- to 129-percent increase in the volume of oil entering the 

water during the year of the spill. In addition, the oil from a spill will be much more concentrated in some 

locations than the large number of other activities that release oil into the Gulf of Mexico. Section 3.1.4. 

of this document discusses the properties and persistence of oil in the environment. 

5.2.2. Biological Resources 

As described below, long-term consequences on biological resources can include impaired 

reproduction, which can potentially impact population levels. Oil has the potential to persist in the 

environment long after a spill event and has been detected in sediment 30 years after a spill (FWS, 2004). 

On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt marshes, oil may seep into 

the muddy bottoms. Oil in these systems has the potential to have long-term impacts on fish and wildlife 

populations. 

Some animals may survive initial exposure to spilled oil but may accumulate high levels of 

contaminants in their bodies that can be passed on to predators, in a process known as bioaccumulation 

(USDOI, FWS, 2010g). 

5.2.2.1. Coastal and Marine Birds 

There is a high probability of underestimating the impacts of oil spills on avian species potentially 

encountering oil, particularly seabirds. Often overlooked and understudied are the long-term, sublethal, 

chronic effects due to sublethal exposure to oil. These effects may persist for years after exposure, 

reducing the capacity of affected individuals within the population to recover, due to effects that may 

range from minor physiological disorders through damage to vital organs (i.e., liver and kidney) (AlonsoAlvarez et al., 2007). Sublethal effects of oil could ultimately result in reductions in long-term survival or 

lower reproductive success for some species of birds (Fry et al., 1986; Leighton, 1993; Esler et al., 2000; 

Golet et al., 2003; Velando et al., 2010). In addition, even light oiling of avian eggs transferred via contact 

with contaminated breast feathers from an incubating female can be toxic to developing embryos (Albers, 

1980; Albers and Heinz, 1983). Effects such as delayed sexual maturity of most seabird species, loss of 

breeding-age individuals, particularly females, may have long-term, population-level effects. Long-term, 

sublethal, chronic effects may exceed immediate losses due to direct mortality (i.e., oiled birds) if such 

residual effects influence a significant proportion of the population or disproportionately impact an 

important population segment (Newton, 1998; Peterson et al., 2003; Alonso-Alvarez et al., 2007). 

5.2.2.2. Fish, Fisheries, and Essential Fish Habitat 

In addition to possible small fish kills due to direct impacts (as described under Phases 2 and 3), a 

catastrophic spill could affect fish populations in the long term. Due to a catastrophic spill, a significant 

portion of a year class of fish could be absent from the following year’s fishery, reducing overall 

population numbers. However, sublethal impacts, especially for long-lived species (e.g., snapper and 

grouper), could be masked by reduced fishing pressure due to closures. In addition, healthy fish resources 

and fishery stocks depend on ideal habitat (EFH) for spawning, breeding, feeding, and growth to maturity. 

Thus, a catastrophic spill that affects these areas could result in long-term impacts, including destruction 

to a portion of their habitats. 

 

2

 These numbers were generated from converting the units reported in the noted reference and do not imply any 

level of significance. 
Catastrophic Spill Event Analysis B-43 

5.2.2.3. Marine Mammals 

Even after the spill is stopped, oilings or deaths of marine mammals would still likely occur due to oil 

and dispersants persisting in the water, past marine mammal/oil or dispersant interactions, and ingestion 

of contaminated prey. The animals’ exposure to hydrocarbons persisting in the sea may result in sublethal 

impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) 

and some soft tissue irritation, respiratory stress from inhalation of toxic fumes, food reduction or 

contamination, direct ingestion of oil and/or tar, and temporary displacement from preferred habitats or 

migration routes. These long-term impacts could have population-level effects (USDOC, NOAA, NMFS, 

2010c). 

5.2.2.4. Sea Turtles 

Sea turtles take many years to reach sexual maturity. Green sea turtles reach maturity between 20 and 

50 years of age; loggerheads may be 35 years old before they are able to reproduce; and hawksbill sea 

turtles typically reach lengths of 27 inches for males and 31 inches for females before they can reproduce 

(USDOC, NOAA, NMFS, 2010d). In most foreseeable cases, exposure to hydrocarbons persisting in the 

sea following the dispersal of an oil slick would result in sublethal impacts (e.g., decreased health, 

reproductive fitness, and longevity and increased vulnerability to disease) to sea turtles. As discussed in 

Section 4.2.2, shoreline oiling and response efforts may affect future population levels and reproduction 

(USDOI, NPS, 2010). The deaths of subadult and adult sea turtles may also drastically reduce the 

population. 

5.2.2.5. Terrestrial Mammals and Reptiles 

Beach Mice 

Within the last 20-30 years, the combination of habitat loss due to beachfront development, isolation 

of remaining beach mouse habitat areas and populations, and destruction of remaining habitat by tropical 

storms and hurricanes has increased the threat of extinction of several subspecies of beach mice. 

Destruction of the remaining habitat due to a catastrophic spill and cleanup activities would increase the 

threat of extinction. 

Diamondback Terrapin 

Habitat destruction, road construction, and drowning in crab traps are the most recent threats to 

diamondback terrapins. Tropical storms, hurricanes, and beach erosion threaten their preferred nesting 

habitats. Destruction of the remaining habitat due to a catastrophic spill and response efforts could 

drastically affect future population levels and reproduction. 

5.2.2.6. Coastal Habitats 

Coastal habitats serve important ecological functions, and the loss of vegetation in coastal areas could 

lead to erosion and permanent land loss. 

Coastal Barrier Beaches and Associated Dunes 

Oil or its components that remain in the sand after cleanup may be (1) released periodically when 

storms and high tides resuspend or flush beach sediments, (2) decomposed by biological activity, or (3) 

volatilized and dispersed. 

The protection once afforded to inland marshes by coastal barrier beaches has been greatly reduced 

due to decreased elevations and the continued effect of subsidence, sea-level rise, and saltwater intrusion. 

A catastrophic spill has the potential to contribute to this reduction. 

The cleanup impacts of a catastrophic spill could result in short-term (up to 2 years) adjustments in 

beach profiles and configurations as a result of sand removal and disturbance during cleanup operations. 

Some oil contact to lower areas of sand dunes is expected. These contacts would not result in significant 
B-44 Central Planning Area Supplemental EIS 

destabilization of the dunes. The long-term stressors to barrier beach communities caused by the physical 

effects and chemical toxicity of an oil spill may lead to decreased primary production, plant dieback, and 

hence further erosion. 

Wetlands 

Wetlands serve a number of important ecological functions. For example, Louisiana’s coastal 

wetlands support more than two-thirds of the wintering waterfowl population of the Mississippi Flyway, 

including 20-25 percent of North America’s puddle duck population. Therefore, loss of wetlands would 

also impact a significant portion of the waterfowl population. 

The duration and magnitude of a spill resulting from a catastrophic blowout could result in high 

concentrations of oil that would result in long-term effects to wetland vegetation, including some plant 

mortality and loss of land. This would add to continuing impacts of other factors, such as hurricanes, 

subsidence, saltwater intrusion, and sea-level rise. The wetlands along the Gulf Coast have already been 

severely damaged by the 2005 and 2008 hurricane seasons, leaving the mainland less protected. It was 

estimated in 2000 that coastal Louisiana would continue to lose land at a rate of approximately 2,672 

ha/yr (10 mi2

/yr) over the next 50 years. Further, it was estimated that an additional net loss of 132,794 ha 

(512 mi2

) may occur by 2050, which is almost 10 percent of Louisiana’s remaining coastal wetlands 

(Barras et al., 2003). Barras (2006) indicated an additional 217 mi2

 (562 km2) of land lost during the 2005 

hurricane season. A catastrophic spill occurring nearshore would contribute further to this landloss. 

Following Hurricanes Katrina and Rita, another series of hurricanes (Gustav and Ike) made landfall along 

the Louisiana and Texas coasts in September 2008. Hurricane Gustav made landfall as a Category 2 storm 

near Cocodrie, Louisiana, pushing large surges of saline water into the fresh marshes and coastal swamps 

of Louisiana from Grand Isle westward. While Hurricane Gustav did not impact the quantity of wetlands 

that Hurricanes Katrina and Rita impacted, it did have a severe and continuing effect on the coastal barrier 

islands and the wetlands associated with backshore (back of the island) and foreshore (front of the island). 

While Hurricane Gustav affected the eastern portion of the Louisiana coast closer to Grand Isle and 

Houma, Hurricane Ike concentrated on Louisiana’s western coast. The Texas coast received the brunt of 

Hurricane Ike where it made landfall slightly east of Galveston. The storm surge basically removed the 

dune systems and significantly lowered the beach elevations along the eastern portion of the Texas coast 

near Galveston and the Bolivar Peninsula. The erosion and wash-over associated with Ike’s tidal surge 

breeched beach ridges opened the inland freshwater ponds and their associated wetlands to the sea. As a 

result of the four successive storms, the Louisiana and Texas coasts have lost protective elevations, 

barrier islands, and wetlands and they now have the potential for transitioning to a less productive saltmarsh system in areas where fresh-marsh systems once existed. 

In addition, a poorly executed oil cleanup can result in additional impacts. Aggressive onshore and 

marsh cleanup methods have not yet been utilized and probably would not be initiated until the oil spill 

has been stopped. Depending on the marsh remediation methods used, further impacts to the wetlands 

may occur from cleanup activities. Boat traffic in marsh areas from the thousands of response vessels 

associated with a catastrophic spill would produce an incremental increase in erosion rates, sediment 

resuspension, and turbidity (i.e., an adverse but not significant impact to coastal wetland and seagrass 

habitats.) 

5.2.2.7. Open Water Habitats 

Submerged Vegetation 

If bays and estuaries accrue oil, there is an assumption that there would be a decrease in seagrass 

cover and negative community impacts. Submerged vegetation serves important ecological functions. For 

example, seagrasses and freshwater SAVs provide important habitat for immature shrimp, black drum, 

spotted sea trout, juvenile southern flounder, and several other fish species, and they provide a food 

source for species of wintering waterfowl (Castellanos and Rozas, 2001; Short and Coles, 2001; Caldwell, 

2003). Therefore, loss of submerged vegetation would impact these species. 
Catastrophic Spill Event Analysis B-45 

Sargassum 

Oceanographic processes that concentrate sargassum into mats and rafts would also concentrate toxic 

substances. Therefore, it may be assumed that sargassum would be found in areas where oil, dispersants, 

and other chemicals have accumulated following a catastrophic spill. The ultimate effects oftoxins to 

sargassum are unclear; however, it is evident that the accumulation provides a toxic environment for 

associated species, especially those that use the sargassum as areas of refuge for larvae or other 

developmental stages (Unified Incident Command, 2010d). There would be noticeable effects on species 

that eat the plant material, such as sea turtles, and the death rate of sargassum may be increased due to 

toxic substances, which would contribute to a major decline in its biomass. This would decrease available 

habitat for associated organisms and indirectly affect the survival rate and recruitment for associated fish 

species. The severity and duration of any toxic effects would be dependent on both the physical properties 

of the toxic components and their biological effects, such as how long it might take them to degrade, their 

solubility in water, and the degree that they accumulate in biological tissue.

5.2.2.8. Benthic Habitats 

Shelf Habitats 

In situations where soft-bottom infaunal communities are negatively impacted, recolonization by 

populations from neighboring soft-bottom substrate would be expected over a relatively short period. 

Recolonization would begin with recruitment and immigration of opportunistic species from surrounding 

stocks. More complex communities would follow with time. Repopulation could take longer for areas 

affected by direct oil contact in higher concentrations. 

Hard-bottom communities exposed to large amounts of resuspended sediments following a 

catastrophic, subsurface blowout could be subject to sediment suffocation, exposure to resuspended toxic 

contaminants, and reduced light penetration. The greatest impacts would occur to communities that exist 

in clear water with very low turbidity. The consequences of a blowout along, directly on, or near one of 

these features could be long lasting, although the occurrence of a blowout near such sensitive 

communities is unlikely because NTL 2009-G39 prevents drilling activity near sensitive hard-bottom 

habitats. Impacts would more likely be from low level or long-term exposure. This type of exposure has 

the potential to greatly impact reef coral communities, resulting in impaired reef health. Impacts to a 

community in more turbid waters would be greatly reduced, as the species are tolerant of suspended 

sediments, and recovery would occur quicker. 

Deepwater Soft-Bottom Benthic Communities 

In situations where soft-bottom infaunal communities are negatively impacted, recolonization by 

populations from neighboring soft-bottom substrate would be expected over a relatively short period of 

time for all organisms ranging from a matter of days for bacteria and probably less than 1 year for most 

macrofauna and megafauna species. This could take longer for areas affected by direct oil contact in 

higher concentrations. 

Deepwater Coral Benthic Communities 

Deepwater corals are expected to be resistant to oiling, with little effect from low exposure. Many 

invertebrates associated with deepwater coral communities, particularly the crustaceans, would likely be 

more susceptible to damage from oil exposure. Recolonization of severely damaged or destroyed 

communities could take years to decades. 

Deepwater Chemosynthetic Benthic Communities 

While chemosynthetic communities that receive low quantities of well-dispersed oil undergoing 

biodegradation would likely experience little negative effect, recolonization of severely damaged or 

destroyed communities could take years to decades. 
B-46 Central Planning Area Supplemental EIS 

5.2.3. Socioeconomic Resources 

5.2.3.1. Offshore and Onshore Archaeological Resources 

While it is unlikely (Section 2.2.3.1), a known shipwreck could be impacted by the blowout itself or 

the subsequent oil spill, impacts (i.e., contamination) from the release of large quantities of dispersants 

associated with a deepwater, catastrophic blowout are possible. Because a site cannot be avoided unless 

its location in known, undiscovered shipwrecks are at a much higher risk as a result of a blow out. Longterm effects of oiling of prehistoric and historic archaeological resources are poorly understood; however, 

damage to the protective layer of corals and other organisms on shipwreck sites by oiling could alter the 

surrounding site dynamics and increase their degradation. In addition, onshore habitat degradation could 

lead to erosion, which would increase exposure to and subsidence of prehistoric and historic sites. Unlike 

biological resources that have the potential to recover, damage to archaeological resources from the spill 

or cleanup activities would be irreversible, leading to loss of important archaeological data needed for 

proper study and interpretation. Archaeological sites also provide recreational opportunities both offshore 

and onshore; therefore, the loss of a site would also have impacts on recreation. 

5.2.3.2. Commercial Fishing 

The Gulf is an important biologic and economic area in terms of seafood production and recreational 

fishing. According to NOAA, there are 3.2 million recreational fishermen in the Gulf of Mexico region 

who took 24 million fishing trips in 2008. Commercial fishermen in the Gulf harvested more than 1 

billion pounds of finfish and shellfish in 2008 (USDOC, NOAA, 2010g). The economic impacts of 

closures on commercial fishing are complicated to predict because the economic effects are dependent on 

season and would vary by fishery. If fishers cannot make up losses in the remainder of the season, a 

substantial part of their annual income could be loss. While the commercial fishing industry of Texas did 

not sustain measurable direct or indirect economic effects following the 1979 Ixtoc blowout and spill 

(Restrepo et al., 1982), there is a documented phenomenon that, long after an incident, the perception of 

tainted fish and shellfish from the impacted area persists (Keithly and Diop, 2001). It is reasonable to 

assume that a negative perception could impact the value of commercial fish resources for several 

seasons. 

5.2.3.3. Recreational Fishing 

In 2008, over 24 million recreational fishing trips were taken in the Gulf of Mexico, which generated 

about $12 billion in sales, over $6 billion in value added impacts, and over 100,000 jobs (USDOC, 

NOAA, NMFS, 2010b). Unlike commercial fishing, recreational fishing is concentrated during the 

summer months. Therefore, a catastrophic spill occurring at the beginning of the recreational fishing 

season and continuing through the season would result in the loss of millions of recreational fishing trips 

and billions in subsequent sales. For example, during the summer months, scheduled fishing tournaments 

are held that would be hard to reschedule. Normal direct income and indirect income to the communities 

that host these tournaments would be lost for that year. 

5.2.3.4. Tourism and Recreational Resources 

The longer-term implications of a catastrophic event on tourism would depend on the extent to which 

any structural/ecological damage can be repaired, as well as on the extent to which public confidence in 

the tourism industry can be restored. For example, a catastrophic oil spill would likely affect the fish 

populations in the affected waters to some extent. The most direct impact of this would be to lessen 

recreational fishing activity in a region to the extent that the fish population has decreased. However, a 

region would not fully recover from the event until confidence in fishing is restored and the remaining 

fish population recovers. In addition, restaurants in the region would be impacted to the extent to which 

they are perceived to use seafood products caught or raised in contaminated waters. Similarly, although 

beaches can be decontaminated not long after a spill has been stopped, lingering perceptions can be 

expected to negatively impact tourism. 
Catastrophic Spill Event Analysis B-47 

Oxford Economics (2010) conducted a study of recent catastrophic events in order to estimate the 

longer-term economic implications of the Deepwater Horizon Oil Spill. They estimate that the long-term 

economic damage from the spill could be between $7.6 and $22.7 billion. Analyzing previous oil spills 

and other catastrophic events, they also suggest that it could take 15-36 months for the tourism industry to 

recover to pre-spill levels. Given Florida’s dependence on fishing and beach activities (as well as the 

overall size of its economy), this study suggests that the State would bear the majority of the economic 

damage from the spill. This study also points out the complicated set of economic and psychological 

forces ultimately determine the extent to which the tourism and recreation industries would recover from 

a catastrophic oil spill. 

5.2.3.5. Employment and Demographics 

While a catastrophic spill could immediately impact several Gulf States for several months through 

fishing closures, loss of tourism, and any suspension of oil and gas activities, anticipating the long-term 

economic and employment impacts in the Gulf of Mexico is a difficult task. Many of the potentially 

affected jobs, like fishing charters, are self-employed. Thus, they would not necessarily file for 

unemployment and will not be included in business establishment surveys used to estimate State 

unemployment levels. In addition, unemployment numbers in states are based on nonagricultural jobs, 

and the fishing industry is considered within the agriculture category. On the other side, it is also a 

challenge to estimate how many of these displaced workers have been hired to clean up the spill. For 

example, while thousands of vessels of opportunity would be active in the spill response, not all of these 

would be displaced commercial fishermen from the affected areas. The positive employment impacts 

related to response activities are likely to be shorter term than the negative impacts discussed above. 

Catastrophic spills have a huge regional economic impact, as seen recently in the Deepwater Horizon

incident. It is estimated that the total economic consequences of the Deepwater Horizon incident will lead 

to a net loss of just under $20 billion for the U.S. economy in 2010, which would lower U.S. economic 

growth in 2010 by roughly 0.1 percent and would reduce growth to a greater extent in the four states most 

affected. 

5.2.3.6. Land Use and Coastal Infrastructure 

Based on the rapid recovery of infrastructure that was heavily damaged by the catastrophic 2005 

hurricane season, there are not expected to be any long-term impacts to land use and coastal infrastructure 

as a result of a catastrophic oil-spill event. However, BOEMRE would continue to monitor the post-spill, 

long-term recovery phase of the Deepwater Horizon incident for any changes that indicate otherwise. A 

catastrophic spill could generate up to 60,000 tons of oil-impacted solid materials disposed in landfills 

along the Gulf Coast. This waste may contain debris, beach or marsh material (sand/silt/clay), vegetation, 

and personal protection equipment collected during cleanup activities. This would be equivalent to 2-6 

years of waste produced from OCS oil and gas activities in the Gulf of Mexico (Dismukes et al., 2007). 

However, landfill capacity is not expected to be an issue at any phase of the oil-spill event or the longterm recovery. According to USEPA, existing landfills that are receiving oil-spill waste from the 

Deepwater Horizon incident have plenty of capacity to handle the expected waste volumes. The oil-spill 

waste that is being disposed in landfills represents less than 7 percent of the total daily waste normally 

accepted at these landfills (USEPA, 2010a). 

It is not expected that any long-term, land-use impacts would arise from properties that are utilized 

for restoration activities and would somehow have their future economic use compromised. The rise or 

fall of property values would not be solely a function of some kind of economic impact from a 

catastrophic oil spill event. There are many other factors that influence the value of property and its best 

economic use. It is not clear from past experiences whether vegetation loss or erosion created by a spill 

could result in changes in land use. The amount and location of erosion and vegetation loss can be 

influenced by the time of year the spill occurs, its location, and weather patterns, including hurricane 

landfalls (Dismukes, personal communication, 2010a). 
B-48 Central Planning Area Supplemental EIS 

5.2.3.7. Environmental Justice 

After the spill is stopped, the primary environmental justice concerns relate to possible long-term 

health impacts to cleanup workers, a predominately minority population, and to possible disposal of oilimpacted solid waste in predominantly minority areas. 

Suspension of Oil and Gas Activities 

An analysis of socioeconomic characteristics shows that people of Cajun ethnicity in the Gulf states, 

often found to be of a comparatively low socioeconomic status and work jobs in the textile and oil 

industries (Henry and Bankston, 1999). Past studies suggest that a healthy offshore petroleum industry 

also indirectly benefits low-income and minority populations (Tolbert, 1995). One BOEMRE study in 

Louisiana found income inequality decreased during the oil boom of the 1980’s and increased with the 

decline (Tolbert, 1995). Although we know that many oil- and gas-related service industries are cutting 

costs and putting off maintenance to defer massive layoffs in response to the oil-spill-caused deepwater 

drilling suspension and the slowed schedule for shallow-water drilling permits, we do not fully 

understand their long-term impacts. 

Onshore and Offshore Cleanup Workers 

By the end of a catastrophic spill, up to 50,000 personnel would be expected to be responding to the 

spill. The majority of these are field responders (United Incident Command, 2010f). As seen with the 

Deepwater Horizon incident, the racial composition of cleanup crews was so conspicuous that Ben 

Jealous, the president of the National Association for the Advancement of Colored People (NAACP), sent 

a public letter to BP Chief Operations Officer Tony Hayward on July 9, 2010, demanding to know why 

African Americans were over-represented in "the most physically difficult, lowest paying jobs, with the 

most significant exposure to toxins" (NAACP, 2010). While regulations require the wearing of protective 

gear and only a small percentage of cleanup workers suffer immediate illness and injuries (CDC, 2010), 

exposure could have long-term health impacts (e.g., increased rates of some types of cancer) (Savitz and 

Engel, 2010; Kirkeleit et al., 2008). Of the 38 accidents involving supertankers and resulting in large oil 

spills throughout the world, only seven studies on the repercussions of the exposure of spilled oils on 

human health have been completed. Aguilera et al. (2010) compiled and reviewed these studies for 

patterns of health effects and found evidence of the relationship between exposure and “acute physical, 

psychological, genotoxic, and endocrine effects in the exposed individuals.” Acute symptoms from 

exposure to oil, dispersants, and degreasers include headaches, nausea, vomiting, diarrhea, sore eyes, 

runny nose, sore throat, cough, nose bleeds, rash, blisters, shortness of breath, and dizziness 

(Sathiakumar, 2010). USEPA monitoring data has so far shown that the use of dispersants during the 

DWH event did not result in a presence of chemicals that surpassed human health benchmarks (Trapido, 

Health Presentation, 2010). Longitudinal epidemiological studies of possible long-term health effects 

from exposure to either the DWH event oil or dispersants, such as the possible bioaccumulation of toxins 

in tissues and organs, are lacking and potential for the long-term human health effects are largely 

unknown (although the National Institutes of Health has proposed such a study). 

Prior research on post-spill cleanup efforts, found that the duration of cleaning work was a risk factor 

for acute toxic symptoms and that seamen had the highest occurrence of toxic symptoms compared to 

volunteers or paid workers. Therefore, participants in the DWH “Vessels of Opportunity” program, 

which recruited local boat-owners (including Cajun, Houma Indian, and Vietnamese fishermen) to assist 

in cleanup efforts, would likely be one of the most exposed groups. African Americans are thought to 

have made up a high percentage of the cleanup workforce. As seen with the Deepwater Horizon incident, 

the racial composition of cleanup crews was so conspicuous that Ben Jealous, the president of the 

National Association for the Advancement of Colored People (NAACP), sent a public letter to BP Chief 

Operations Officer Tony Hayward on July 9, 2010, demanding to know why African Americans were 

over-represented in “the most physically difficult, lowest paying jobs, with the most significant exposure 

to toxins” (NAACP, 2010). The Occupational Safety & Health Administration (OSHA) released two 

matrices of gear requirements for on- and off-shore Gulf operations that are organized by task (OSHA). 

Of past oil-spill workers, uninformed and poorly-informed workers were at more risk of exposure and 
Catastrophic Spill Event Analysis B-49 

symptoms, demonstrating the importance of education and proper training of workers (Sathiakumar, 

2010). 

Therefore, a catastrophic spill could disproportionately affect seamen and onshore workers such as 

Cajuns, Vietnamese, Houma Indian, and African Americans. 

During a recent National Institute of Environmental Sciences (NIEHS) workshop regarding the health 

effects of the BP Deepwater Horizon oil spill, Chairperson Nancy E. Adler pointed to the uncertainty 

regarding health effects and these types of events, “While studies of previous oil spills provide some basis 

for identifying and mitigating the human health effects of these exposures, the existing data are 

insufficient to fully understand and predict the overall impact of hazards from the Deepwater Horizon oil 

spill on the health of individuals—including workers, volunteers, residents, visitors, and special 

populations” (Institute of Medicine, 2010). In order to address these data gaps, NIEHS plans to begin a 

prospective study of the mental and physical health of about 50,000 workers who helped battle the spill. 

Solid-Waste Disposal 

Following a catastrophic spill, environmental justice concerns related to the disposal of cleanuprelated wastes near minority and/or low-income communities (Schleifstein, 2010). It is estimated a 

catastrophic spill could generate up to 60,000 tons of oil-impacted solid materials that would be disposed 

in landfills along the Gulf Coast. While no new landfills would be built due to a catastrophic spill, the use 

of existing landfills might exacerbate existing environmental justice issues. For example, Mobile, 

Alabama and Miami, Florida are majority minority urban centers with a majority of minority residents 

living with a 1-mile radius of chosen landfills or liquid processing centers. While only a small percentage 

of DWH waste was sent to these facilities: 13% of liquid waste to Liquid Environmental Solutions in 

Mobile and only .28% of the total liquid waste to Cliff Berry in Miami, they could potentially receive 

more for future spills. For example, of the nine landfills approved by USEPA for oil-impacted solid 

materials, more than half of the waste was disposed in four landfills that were located in areas where 

minority groups comprised the majority of the population (Hernandez, 2010). Disposal procedures for the 

DWH event involved sorting waste materials into standard “waste stream types” at small, temporary 

stations, and then, sending each type to existing facilities that were licensed to dispose of them. The 

location of temporary sorting stations was linked to the location of containment and cleanup operations. 

Hence, future locations of any sorting stations are not predictable since they would be determined by the 

needs of cleanup operations. However, waste disposal locations were determined by the specializations 

of existing facilities and by contractual relationships between them and the cleanup and containment 

firms. Louisiana received about 82 percent of the DWH liquid waste recovered; of this, 56 percent was 

manifested to mud facilities located in Venice, Plaquemines Parish, Louisiana, and Port Fourchon, 

Lafourche Parish, Louisiana, and then transferred to a processing facility in Port Arthur, Texas. The 

waste remaining after processing was sent to deep well injection landfills located in Fannett and Big Hill, 

Texas. The sites located in Venice and Port Fourchon, Louisiana, and Port Arthur, Fannett, and Big Hill, 

Texas, have low minority populations but a few of these areas have substantial poverty rates relative to 

state and county means. Although, in the case of the DWH event, most of the cleanup occurred in the 

CPA, disposal occurred in both the CPA and WPA, and this would likely happen should a future event 

occur. 

6. CUMULATIVE ENVIRONMENTAL AND SOCIOECONOMIC IMPACT 

Like the recent, devastating hurricane seasons of 2005 and 2008, the Deepwater Horizon incident has 

changed the environmental baseline of the Gulf of Mexico. Another catastrophic oil spill would make the 

resources of the Gulf even more susceptible to further impacts, adding to the cumulative effects of an 

already sensitive ecosystem. 

The Gulf Coast has survived major natural and manmade disasters (i.e., hurricanes and oil spills), 

through which the people and environmental resources of the Gulf of Mexico and the Gulf Coast have 

repeatedly demonstrated their resiliency. While environmental and socioeconomic resources may recover 

from a natural or manmade disaster if given enough time between disasters, disasters happening in unison 

or within short periods of each other would make recovery more difficult. 
B-50 Central Planning Area Supplemental EIS 

The magnitude of OCS and non-OCS activity in the Gulf of Mexico is so immense that routine 

activities associated with a single OCS oil and gas activity (e.g., single lease sale, single well) have a 

minor to no incremental contribution to the impacts of cumulative activities. However, a catastrophic 

blowout and spill would have a major contribution to cumulative impacts. 

7. SUMMARY OF IMPACTS 

7.1. SUMMARY OF IMPACTS FROM PHASE 1 (INITIAL EVENT) 

The initial phase of the catastrophic event analyzed in the Gulf of Mexico is a blowout causing an 

explosion and fire, possibly resulting in the sinking of the drilling rig or platform. Impacts during Phase 1 

would be limited to workers on the platform and environmental resources offshore in the immediate 

vicinity of the blowout. Air quality impacts include the emission of pollutants from the oil and the fire 

that are hazardous to human health and can possibly be fatal. Water quality impacts include localized 

water quality effects, which could include the release of a large amount of methane gas and the 

disturbance of a large amount of sediments over an extended area, if the blowout occurs outside the 

wellbore, below the seafloor. 

An explosion would kill any birds resting on the platform, including birds protected under the 

Migratory Bird Treaty Act. Eruption of gases and fluids may generate significant pressure waves and 

noise to injure or kill individual animals in the vicinity, including federally listed threatened and 

endangered species under the ESA or MMPA. A shock wave under water may also impact commercial 

and recreational fisheries in the area. Benthic communities beyond avoidance zones could be smothered. 

In addition to a large number of fatalities and injuries of people on the drilling rig or platform itself, 

commercial and recreational fishers and divers near the blowout could be injured or killed. The blowout 

could also damage any unidentified archaeological sites nearby.

7.2. SUMMARY OF IMPACTS FROM PHASE 2 (OFFSHORE SPILL) 

The second phase of the catastrophic event analyzed is an extended, offshore spill estimated to last 1-

4 months for a blowout in shallow water and 3-5 months for a blowout in deepwater, due to more difficult 

intervention. A large-scale response effort would be expected for a catastrophic spill, including tens of 

thousands of responders, several thousand vessels, and the release of a large amount of dispersants. 

A catastrophic spill has the potential to cause population level impacts to offshore biological 

resources. Multiple Federal and State-listed, threatened and endangered species could be impacted in the 

water column or at the sea surface. In addition, natural processes (e.g., flocculation) and human 

intervention (i.e., subsea dispersants) could expose benthic communities and archaeological sites to oil. 

Additionally, known and previously undiscovered archaeological sites and benthic habitats could be 

damaged by bottom-disturbing activities associated with the response effort, including anchoring of 

vessels. Pollutants in the spilled oil that are hazardous to response workers without protective equipment 

would be emitted into the air through evaporation and through in-situ or controlled burns of oil slicks. 

Socioeconomic impacts would begin while the spill is still offshore. A large portion of the Gulf of 

Mexico EEZ and most of State waters could be closed to commercial and recreational fishing for several 

months, possibly causing the loss of revenue for an entire season or year. These closures may 

predominately affect minority or ethnic groups. Tourism may also be impacted due to either perceived 

damage to recreational resources that has not yet materialized or to general hesitation on the part of 

travelers to visit the overall region due to the spill. Suspension of some oil and gas activities would be 

possibly follow a catastrophic event, temporarily affecting jobs in the oil and gas industry. 

7.3. SUMMARY OF IMPACTS FROM PHASE 3 (ONSHORE CONTACT) 

The third phase of the catastrophic event analyzed is oiling of the shoreline. Exponential increase of 

the length of shoreline impacted is expected as the spill would continue over several months, which 

would likely overwhelm response efforts. Due to longer intervention times, a deepwater blowout and spill 

could impact over 1,000 miles of shoreline. While a catastrophic spill from a shallow-water blowout is 

expected to be a lower volume than a deepwater blowout, the site would generally be located closer to 
Catastrophic Spill Event Analysis B-51 

shore, allowing less time for oil to be weathered, dispersed, and recovered. This could result in more 

concentrated and toxic oiling of several hundred miles of shoreline for more than 2 months. 

The severity of oiling would vary between heavy, moderate, light, and occasional tarballs. However, 

due to the length of shoreline that could be potentially oiled and the sensitivity of the Gulf Coast, a 

catastrophic spill could cause extensive habitat degradation. Loss of vegetation could lead to erosion and 

permanent landloss. Though response efforts (including the use of skimmers and booms) would decrease 

the amount of oil contacting the coastline, significant amounts of oil would remain to impact coastal 

water quality. Gulf of Mexico water quality is already rated as fair to poor, according to USEPA. 

Depending on timing and location, a catastrophic spill has the potential to cause population-level impacts 

on biological resources. Dozens of Federal and State-listed, threatened and endangered species could be 

impacted. Impacts on air quality may have adverse effects on oil spill responders. 

While cultural resources were recognized as significant early in the response and archaeologists are at 

present embedded in SCAT teams and consulting with cleanup crews, efforts to prevent coastal cultural 

resources from becoming contaminated by oil would likely be overwhelmed by the magnitude of 

shoreline impacted and/or in the event of a hurricane during the spill cleanup efforts. In addition to 

closures in Federal waters, portions to all of individual State waters would also be closed to commercial 

and recreational fishing. The economic impact of these closures would have a disproportional effect on 

minority and low-income groups, and shoreline impacts would generate additional subsistence-related 

effects. A catastrophic spill also has the potential to significantly impact the Gulf Coast recreation and 

tourism industries, particularly water-dependent and beach-dependent components of these industries. An 

influx of cleanup and relief workers would not fully offset economic impacts. The influx a large number 

of responders and the creation of staging areas due to a catastrophic spill would have temporary impacts 

(e.g., increased traffic congestion and some possible competing land use issues) on land use and 

infrastructure. In addition, there is a potential for delays in cargo handling and slow vessel traffic due to 

decontamination operations at various sites along the marine transportation system. 

7.4. SUMMARY OF IMPACTS FROM PHASE 4 (LONG-TERM IMPACTS) 

Phase 4 focuses on the long-term impacts of a catastrophic oil spill. While impacts to air and water 

quality may be shorter term, a catastrophic spill can have impacts on Gulf of Mexico ecosystems long 

after the well is capped or killed and cleanup activities have concluded. In some cases, marine ecosystems 

may take decades to fully recover or may recover to alternative states. 

Coastal and offshore habitats serve important ecological functions. Onshore, the loss of vegetation 

could lead to erosion and permanent landloss. Offshore, repopulation of benthic communities could take 

longer for areas affected by direct oil contact in higher concentrations. For birds, fish, marine mammals 

and sea turtles, damage of habitats, loss of reproductively capable adults as well as juveniles, and 

sublethal impacts from oil exposure can lead to impaired reproduction. This can potentially reduce 

population levels. For example, a catastrophic spill could decrease available habitat for associated 

organisms and indirectly affect the survival rate and recruitment for associated fish species. In the case of 

birds, long-term, sublethal, chronic effects may exceed immediate losses due to direct mortality (i.e., oiled 

birds) if such residual effects influence a significant proportion of the population or disproportionately 

impact an important population segment. A catastrophic spill could cause the destruction of the remaining 

habitat of certain onshore species, such as the diamondback terrapin or beach mice. 

A catastrophic spill can also have long-term impacts on socioeconomic resources. Positive 

employment impacts related to response activities are likely to be shorter term than the negative impacts. 

Catastrophic spills have a huge regional economic impact (billions of dollars) as recently seen with the 

Deepwater Horizon incident. The longer-term implications for commercial and recreational fishing and 

tourism depend on the extent and perception of environmental damage. After the spill is stopped, the 

primary environmental justice concerns would be long-term health impacts of predominately minority 

workers and the disposal of oil-impacted solid waste in predominantly minority areas. Long-term impacts 

to land use and coastal infrastructure are not expected. Unlike biological or other socioeconomic 

resources that have the potential to recover, damage to archaeological resources from the spill or cleanup 

activities would be irreversible, leading to loss of important archaeological data needed for proper study 

and interpretation.
B-52 Central Planning Area Supplemental EIS 

8. PREPARERS 

James F. Bennett, Chief, Environmental Assessment Branch 

Brad J. Blythe, Oceanographer 

Gregory S. Boland, Biological Oceanographer 

Darice Breeding, Physical Scientist 

Sindey Chaky, Social Scientist 

Deborah Epperson, Biologist 

Jeff Gleason, Biologist 

Donald (Tre) W. Glenn III, Protected Species Biologist 

Gary D. Goeke, Chief, Environmental Assessment Section 

Larry M. Hartzog, Biologist 

Dirk Herkhof, Meteorologist 

Chester Huang, Meteorologist 

Chris Horrell, Marine Archeologist 

Tim Holder, Socioeconomic Specialist 

Jack Irion, Supervisor, Marine Archaeologist, Social Sciences Unit 

Mark D. Jensen, Economist 

Brian Jordan, Archaeologist 

Arie R. Kaller, Biologist 

Greg Kozlowski, Environmental Scientist 

Daniel (Herb) Leedy, Supervisor, Biological Sciences Unit 

Harry Luton, Social Scientist 

Lissa Lyncker, Environmental Scientist 

Robert Martinson, NEPA/CZM Unit Supervisor, Senior Environmental Scientist 

Margaret Metcalf, Supervisor, Physical Scientist, Physical Science Unit 

Deborah H. Miller, Technical Publications Editor 

David P. Moran, Biologist 

Michelle V. Morin, Environmental Protection Specialist 

Maureen Mulino, Biologist 

Constance E. Murphy, Editor 

Michelle K Nannen, Biologist 

Erin O’Reilly, Physical Scientist 

James Sinclair, Biologist 

Kimberly A. Skrupky, Marine Biologist 

Kristen L. Strellec, Economist 

Sally Valdes, Fisheries Biologist 

James R. Woehr, Avian Biologist 

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U.S. Department of the Interior. Bureau of Ocean Energy Management, Regulation and Enforcement 

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website: http://www.boemre.gov/incidents/SigPoll70.htm. 

U.S. Department of the Interior. Bureau of Ocean Energy Management, Regulation and Enforcement 

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U.S. Department of the Interior. Fish and Wildlife Service (FWS). 2004. Effects of oil spills on wildlife 

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B-66 Central Planning Area Supplemental EIS 

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West Indian manatee Florida stock. U.S. Dept. of the Interior, Fish and Wildlife Service, Jacksonville, 

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OCS EIS/EA MMS 2007-018. 

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lease sales: 2009-2012; Central Planning Area Sales 208, 213, 216, and 222; Western Planning Area 

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Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS 

EIS/EA MMS 2008-041. Internet website http://www.gomr.mms.gov/PDFs/2008/2008-041.pdf. 

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Continental Shelf Oil and Gas Leasing Program, 2007-2012. Internet website: http://

www.boemre.gov/5-year/PDFs/PRP2007-2012.pdf. 

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Catastrophic Spill Event Analysis B-67 

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Boston, MA: Butterworth Publishers. 
APPENDIX C 

 

BOEMRE-OSRA CATASTROPHIC RUN
BOEMRE-OSRA Catastrophic Run C-3 

APPENDIX C. BOEMRE-OSRA CATASTROPHIC RUN 

A special Oil-Spill Risk Analysis (OSRA) run was conducted in order to estimate the impacts of a 

possible future catastrophic or high-volume, long-duration oil spill. Thus, assuming a hypothetical highvolume, long-duration oil spill occurred, this analysis emphasized modeling a spill that continued for 90 

consecutive days, with each trajectory tracked for up to 120 days. The OSRA for this analysis was 

conducted for only the trajectories of oil spills from five hypothetical spill locations to various land 

segments. The probability of an oil spill contacting a specific land segment within a given time of travel 

from a certain location or spill point is termed a conditional probability; the condition being that a spill is 

assumed to have occurred. Each trajectory was allowed to continue for as long as 120 days. However, if 

the hypothetical spill contacted shoreline sooner than 30 days after the start of the spill, the spill trajectory 

was terminated, and the contact was recorded. Although, overall OSRA is designed for use as a riskbased assessment, for this analysis, only the conditional probability, the probability of contact to the 

resource, was calculated. The probability of a catastrophic spill occurring was not calculated; thus, the 

combination of the probability of a spill and the probability of contact to the resources from the 

hypothetical spill locations were not performed. Results from this trajectory analysis provide input to the 

final product by estimating where spills might travel on the ocean’s surface and what land segments might 

be contacted if and when another catastrophic spill occurs, but it does not provide input on the probability 

of another catastrophic spill occurring. 

OSRA Overview 

The OSRA model, originally developed by Smith et al. (1982) and enhanced by this Agency over the 

years (Ji et al., 2002, 2004a, and 2004b), simulates oil-spill transport using model-simulated winds and 

ocean currents in the Gulf of Mexico. An oil spill on the ocean surface moves around by the complex 

surface ocean currents exerting a shear force on the spilled oil from below. In addition, the prevailing 

wind exerts an additional shear force on the spill from above, and the combination of the two forces 

causes the transportation of the oil spill away from its initial spill location. In the OSRA model, the 

velocity of a hypothetical oil spill is the linear superposition of the surface ocean current and the wind 

drift caused by the winds. The model calculates the movement of hypothetical spills by successively 

integrating time sequences of two spatially gridded input fields: the surface ocean currents and the sealevel winds. Thus, the OSRA model generates time sequences of hypothetical oil-spill locations—

essentially, oil-spill trajectories. 

At each successive time step, the OSRA model compares the location of the hypothetical spills against 

the geographic boundaries of shoreline. The frequencies of oil-spill contact are computed for designated 

oil-spill travel times (e.g., 3, 10, 30, or 120 days) by dividing the total number of oil-spill contacts by the 

total number of hypothetical spills initiated in the model from a given hypothetical spill location. The 

frequencies of oil-spill contact are the model-estimated probabilities of oil-spill contact. The OSRA 

model output provides the estimated probabilities of contact to segments of shoreline from the five launch 

points (LP) in the Gulf of Mexico, which are explained below. 

There are factors not explicitly considered by the OSRA model that can affect the transport of spilled 

oil as well as the dimensions, volume, and nature of the oil spills contacting environmental resources or 

the shoreline. These include possible cleanup operations, chemical composition or biological weathering 

of oil spills, or the spreading and splitting of oil spills. The OSRA analysts have chosen to take a more 

environmentally conservative approach by presuming persistence of spilled oil over the selected time 

duration of the trajectories. 

In the trajectory simulation portion of the OSRA model, many hypothetical oil-spill trajectories are 

produced by numerically integrating a temporally and spatially varying ocean current field, and 

superposing on that an empirical wind-induced drift of the hypothetical oil spills (Samuels et al., 1982). 

Collectively, the trajectories represent a statistical ensemble of simulated oil-spill displacements produced 

by a field of numerically derived winds and ocean currents. The winds and currents are assumed to be 

statistically similar to those that will occur in the Gulf during future offshore activities. In other words, 

the oil-spill risk analysts assume that the frequency of strong wind events in the wind field is the same as 

what will occur during future offshore activities. By inference, the frequencies of contact by the 
C-4 Central Planning Area Supplemental EIS 

simulated oil spills are the same as what could occur from actual oil spills during future offshore 

activities. 

Another portion of the OSRA model tabulates the contacts by the simulated oil spills. A contact to 

shore will stop the trajectory of an oil spill; no re-washing is assumed in this model. After specified 

periods of time, the OSRA model will divide the total number of contacts to the coastline segments by the 

total number of simulated oil spills from each of the five LP’s. These ratios are the estimated 

probabilities of oil-spill contact from offshore activities at that geographic location, assuming spill 

occurrence. 

Conducting an oil-spill risk analysis needs detailed information on ocean currents and wind fields 

(Ji, 2004). The ocean currents used are numerically computed from an ocean circulation model of the 

Gulf of Mexico driven by analyzed meteorological forces (the near-surface winds and the total heat 

fluxes) and observed river inflow into the Gulf of Mexico (Oey et al., 2004; Oey, 2005). The models 

used are versions of the Princeton Ocean Model, which is an enhanced version of the earlier constructed 

Mellor-Blumberg Model. 

The ocean model calculation was performed by Princeton University (Oey et al., 2004). This 

simulation covered the 7-year period, 1993 through 1999, and the results were saved at 3-hour intervals. 

This run included the assimilation of sea-surface altimeter observations to improve the ocean model 

results. The surface currents were then computed for input into the OSRA model, along with the 

concurrent wind field. The OSRA model used the same wind field to calculate the empirical wind drift of 

the simulated spills. The statistics for the contacts by the trajectories forced by the currents and winds 

were combined for the average probabilities. 

Catastrophic OSRA Run Overview 

A special OSRA run was conducted in order to estimate the impacts of a possible future catastrophic 

spill. Thus, assuming a hypothetical catastrophic oil spill occurred, this analysis emphasized modeling a 

spill that continued for 90 consecutive days with each trajectory tracked for up to 120 days. The OSRA 

for this analysis was conducted for only the trajectories of oil spills from five hypothetical spill locations 

to various land segments (Figure C-1 and C-2). The probability that an oil spill will contact a specific 

land segment within a given time of travel from a certain location or spill point is termed a conditional 

probability; the condition being that a spill is assumed to have occurred. Each trajectory was allowed to 

continue for as long as 120 days. However, if the hypothetical spill contacted shoreline sooner than 30 

days after the start of the spill, the spill trajectory was terminated, and the contact was recorded. 

Although, overall the OSRA is designed for use as a risk-based assessment, for this analysis, only the 

conditional probability, the probability of contact to the resource, was calculated. The probability of a 

catastrophic spill occurring was not calculated, thus the combination of the probability of a spill and the 

probability of contact to the resources from the hypothetical spill locations was not performed. Results 

from this trajectory analysis provide input to the final product by estimating where spills might travel on 

the ocean’s surface and what land segments might be contacted if and when another catastrophic spill 

occurs, but it does not provide input on the probability of another catastrophic spill occurring. 

Trajectories of hypothetical spills were initiated every 1.0 day from each of the launch points over the 

simulation period from January 1, 1993, to December 31, 1998 (Figure C-1). The chosen number of 

trajectories per site was small enough to be computationally practical and large enough to reduce the 

random sampling error to an insignificant level. Also, the weather-scale changes in the winds are at least 

minimally sampled, with simulated spills started every 1.0 day. 

These launch point locations were developed within the Gulf of Mexico region for the purpose of this 

analysis. Five launch points were identified and encompassed the approximate areas with the possibility 

of finding the largest oil volume within the following regions: 

 Central Gulf of Mexico shelf area west of the Mississippi River; 

 Central Gulf of Mexico shelf area east of the Mississippi River; 

 Central Gulf of Mexico slope area; 
BOEMRE-OSRA Catastrophic Run C-5 

 Western Gulf of Mexico shelf area; and 

 Western Gulf of Mexico slope area. 

Longitude Latitude Launch Point 

(LP) 

-92.17851 28.98660 1 

-88.15338 29.91388 2 

-90.22203 27.31998 3 

-96.76627 27.55423 4 

-94.51836 27.51367 5 

The methodology used for launch point selection is not part of the OSRA model in the manner it has 

been typically run for this Agency’s spill analyses. Gulf of Mexico OCS Region geologists and engineers 

used the following methodology to select the five points. For each geologic play currently recognized, 

the undiscovered technically recoverable resource volume was allocated throughout the play area based 

on the likelihood of future oil discovery potential. The probability factor used to allocate undiscovered 

oil volumes to areas within the geologic play was based on the density of existing discoveries, the density 

of undrilled prospects on leased acreage, and the results from recent exploration activity. In areas where 

the potential for undiscovered technically recoverable resource volume exists for more than one geologic 

play, the oil volumes were aggregated. Results from the aggregation were used to identify five 

geographic areas of high potential for future oil discoveries: three in the Central Planning Area and two 

in the Western Planning Area of the Gulf of Mexico. Although these areas may encompass hundreds of 

square miles, the coordinates for the five launch points were selected qualitatively to correspond with the 

centroid of these areas. After their selection, the five points were given to the OSRA analysts for use with 

the OSRA model. 

Additionally, the total estimated oil-contacted area of water was also determined. The OSRA model 

integrates the spill velocities (a linear superposition of surface ocean currents and empirical wind drift) by 

integrating in time to produce the spill trajectories. The time step selected was 1 hour to fully utilize the 

spatial resolution of the ocean current field and to achieve a stable set of trajectories. The velocity field 

was bilinearly interpolated from the 3-hour grid to get velocities at 1-hour intervals. 

The trajectories simulated by the model represent only hypothetical pathways of oil slicks; they do not 

involve any direct consideration of cleanup, dispersion, or weathering processes that could alter the 

quantity or properties of oil that might eventually contact the environmental resource locations. However, 

an implicit analysis of weathering and spill degradation can be considered by choosing a travel time for 

the simulated oil spills when they contact environmental resource locations that represent the likely 

persistence of the oil slick on the water surface. Therefore, OSRA model trajectories were analyzed up to 

120 days. Any spill contacts occurring during this elapsed time are reported in the probability tables. 

Conditional probabilities of contact with land segments within 120 days of travel time were calculated for 

each of the hypothetical spill sites. 

The probability estimates were tabulated as 90-day groupings of the 120-day trajectories, as averages 

for the 6 years of the analysis from 1993 to 1998. These groupings were treated as seasonal probabilities 

that corresponded with quarters of the year: Winter, Q1 (January, February, and March); Spring, Q2 

(April, May, and June); Summer, Q3 (July, August, and September); and Fall, Q4 (October, November, 

and December). These 3-month probabilities can be used to estimate the average number of land 

segments (counties/parishes) contacted during a spill, treated as one spill occurring each day for 90 days, 

within the quarter. The seasonal quarterly groupings take account of the differing meteorological and 

oceanographic conditions (wind and current patterns) during the year. The latest meteorological and 

oceanographic information in the Gulf of Mexico available to BOEMRE were for the years 1993-1998. 

The area of ocean surface contacted by oil from the hypothetical spills was estimated by creating a 

grid of 1/6 degree longitude by 1/6 degree latitude. As the trajectories were computed, contact to the grid 

cells was tabulated. To estimate the area, the number of grid cells was multiplied by the approximate area 

of 342 square kilometers per grid cell. The number of grid cells and the approximate area of the ocean 

contacted by the spills were summarized at the same time intervals that were used for the land segment 

(county/parish boundary) tables (3, 10, 30, and 120 days). 
C-6 Central Planning Area Supplemental EIS 

Catastrophic OSRA Results and Discussion 

It should be noted that the study area only extends somewhat into the Atlantic Ocean, where oil spills 

in the Gulf might be transported via the exiting Loop Current. However, on average, less than 0.5 percent 

of the simulated spills made it across the northern or southern Florida Straits boundary within 30 days, 

and only 1-2 percent within 120 days. The hypothetical spill trajectories from launch points in the 

western Gulf of Mexico (e.g., LP1, LP4, and LP5) have a much less chance of being transported through 

the Florida Straits than those in the central Gulf of Mexico (LP2 and LP3). 

As one might expect, land segments closest to the spill sites had the greatest risk of contact. As the 

model run duration increases, more of the shoreline segments could have meaningful probabilities of 

contact (0.5%) (See Tables C-1 through C-5 for the probabilities expressed as percent chance of one or 

more offshore spills 1,000 bbl contacting the areas noted in Figure C-2.). It should be reiterated that 

these are conditional probabilities; the condition being that a spill is assumed to have occurred. The 

longer transit times up to 120 days allowed by the model enable hypothetical spills to reach the 

environmental resources and the shoreline from more distant spill locations. With increased travel time, 

the complex patterns of wind and ocean currents produce eddy-like motions of the oil spills and multiple 

opportunities for a spill to make contact with shoreline segments. For some launch points and for the 

travel times greater than 30 days, the probability of contact to land decreases very slowly or remains 

constant because the early contacts to land have occurred within 30 days, and the trajectories that have not 

contacted land within 30 days will remain at sea for 120 days or more. 

To summarize the differences between the LP’s, a chart showing the estimated square area of each 

launch point for the 6-day intervals is shown (see Figures C-3 through C-7 corresponding to LP’s 1-5, 

respectively). The differences between the estimated spill areas from each LP can be explained by 

meteorological and oceanographic conditions. 

 LP1—CPA, shelf area, west of the Mississippi River Delta, offshore south-central 

Louisiana, deepwater. Launch Point 1 is located near the Louisiana coast, and the 

fall circulation results in persistent and recurring coastal current from Louisiana 

waters toward Texas waters. 

 LP2—CPA, shelf edge area, east of the Mississippi River Delta, south of the 

Alabama-Mississippi border, ultra-deepwater. Launch Point 2 is located near the 

Mississippi River Delta on the eastern side. The trajectories contact the coastline of 

Louisiana, Mississippi, Alabama, and Florida. Many of the trajectories are forced 

offshore by the wind drift and interact with the Loop Current and Loop Current 

eddies. 

 LP3—CPA, shelf area, west of the Mississippi River delta, due south of New 

Orleans, deepwater. Launch Point 3 is located relatively far offshore and west of the 

Mississippi River Delta. The estimated area contacted by the spill is the largest of all 

the selected points, and the trajectories are influenced by the deepwater Loop Current 

eddies and offshore currents. 

 LP4—WPA, shelf area, deepwater. Launch Point 4 is near the Texas coast in the 

western Gulf of Mexico. The trajectories from this launch point frequently contact 

land. The coastal flow near Texas, but to the south of the U.S./Mexico border, has a 

high fraction of northward currents, the wind is relatively persistent with a westward 

component, and the trajectories remain in a relatively smaller area. 

 LP5—WPA, slope area, ultra-deepwater. Launch Point 5 is in the western Gulf of 

Mexico between the coast (LP4) and the central Gulf (LP3). The trajectories are 

forced by the Loop Current eddies that are somewhat weaker in this part of the Gulf 

of Mexico because these eddies dissipate kinetic energy as they drift to the west from 

their original separation zone. 
BOEMRE-OSRA Catastrophic Run C-7 

References Cited 

Ji, Z.-G. 2004. Use of physical sciences in support of environmental management. Environmental 

Management 34(2). Pp. 159-169. 

Ji, Z.-G., W.R. Johnson, C.F. Marshall, G.B. Rainey, and E.M. Lear. 2002. Oil-spill risk analysis: Gulf 

of Mexico outer continental shelf (OCS) lease sales, Central Planning Area and Western Planning 

Area, 2003-2007, and Gulfwide OCS program, 2003-2042. U.S. Dept. of the Interior, Minerals 

Management Service, Herndon, VA. OCS Report MMS 2002-032. 61 pp. 

Ji, Z.-G., W.R. Johnson, and C.F. Marshall. 2004a. Deepwater oil-spill modeling for assessing 

environmental impacts. Coastal Environment V. Southampton, MA: WIT Press. Pp. 349-358. 

Ji, Z.-G., W.R. Johnson, C.F. Marshall, and E.M. Lear. 2004b. Oil-spill risk analysis: Contingency 

planning statistics for Gulf of Mexico OCS activities. U.S. Dept. of the Interior, Minerals 

Management Service, Herndon, VA. OCS Report MMS 2004-026. 62 pp. 

Oey, L.-Y. 2005. Circulation model of the Gulf of Mexico and the Caribbean Sea: Development of the 

Princeton Regional Ocean Forecast (& Hindcast) System—PROFS and Hindcast experiment for 

1992-1999: Final report. U.S. Dept. of the Interior, Minerals Management Service, Environmental 

Division, Herndon, VA. OCS Study MMS 2005-049. 174 pp. 

Oey, L.-Y., P. Hamilton, and H.C.-Lee. 2004. Modeling and data analyses of circulation processes in the 

Gulf of Mexico: Final report. U.S. Dept. of the Interior, Minerals Management Service, Gulf of 

Mexico OCS Region, New Orleans, LA. OCS Study MMS 2003-074. 129 pp. 

Samuels, W.B., N.E. Huang, and D.E. Amstutz. 1982. An oil spill trajectory analysis model with a 

variable wind deflection angle. Ocean Engineering 9:347-360. 

Smith, R.A., J.R. Slack, T. Wyant, and K.J. Lanfear. 1982. The oil spill risk analysis model of the U.S. 

Geological Survey. U.S. Dept. of the Interior, Geological Survey Professional Paper 1227. 
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Figure C-1. Location of Five Hypothetical Oil-Spill Launch Points for OSRA within the Study Area. 















	












 





 





	
























	

  	

 









	

  

 










	

	



	









	


	


 





	









	

	

	 	

		


 



 



 

	 
 

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Figure C-2. Locations of Parishes, Counties, and Coastlines Examined in the Special OSRA Run Conducted in 

Order to Estimate the Impacts of a Possible Future Catastrophic Spill.
BOEMRE-OSRA Catastrophic Run C-9 

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1000000

3d area 10d area 30d area 120d area

Square Kilometers (km2

) of Oil Contacted Area

Winter Spring Summer Fall

Figure C-3. Estimated Square Area of Launch Point One (LP 1) for 3, 10, 30, and 120 Days in Winter, 

Spring, Summer, and Fall. 
C-10 Central Planning Area Supplemental EIS 

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1000000

3d area 10d area 30d area 120d area

Square Kilometers (km2

) of Oil Contacted Area

Winter Spring Summer Fall

Figure C-4. Estimated Square Area of Launch Point Two (LP 2) for 3, 10, 30, and 120 Days in Winter, 

Spring, Summer, and Fall. 
BOEMRE-OSRA Catastrophic Run C-11 

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1000000

3d area 10d area 30d area 120d area

Square Kilometers (km2

) of Oil Contacted Area

Winter Spring Summer Fall

Figure C-5. Estimated Square Area of Launch Point Three (LP 3) for 3, 10, 30, and 120 Days in Winter, 

Spring, Summer, and Fall. 
C-12 Central Planning Area Supplemental EIS 

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1000000

3d area 10d area 30d area 120d area

Square Kilometers (km2

) of Oil Contacted Area

Winter Spring Summer Fall

Figure C-6. Estimated Square Area of Launch Point Four (LP 4) for 3, 10, 30, and 120 Days in Winter, 

Spring, Summer, and Fall. 
BOEMRE-OSRA Catastrophic Run C-13 

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1000000

3d area 10d area 30d area 120d area

Square Kilometers (km2

) of Oil Contacted Area

Winter Spring Summer Fall

Figure C-7. Estimated Square Area of Launch Point Five (LP 5) for 3, 10, 30, and 120 Days in Winter, 

Spring, Summer, and Fall. 
C-14 Central Planning Area Supplemental EIS 

Table C-1 

 

Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at Launch Point One 

Will Contact a Certain Parish, County, or Coastline within 120 Days 

 Season Winter Spring Summer Fall 

 Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120

ID Name Percent Chance 

1 Cameron, TX - - 1 2 - - - - - - - 1 - - - 2

2 Willacy, TX - - 1 1 - - - - - - - - - - - -

3 Kenedy, TX - - 1 3 - - - - - - 1 1 - - 2 4

4 Kleberg, TX - - - 1 - - - 1 - - 1 1 - - 1 3

5 Nueces, TX - - 1 4 - - - - - - 1 2 - - 1 3

6 Aransas, TX - - 2 4 - - - - - - 2 2 - - 2 4

7 Calhoun, TX - - 5 10 - - - - - - 4 4 - - 2 3

8 Matagorda, TX - 1 13 17 - - 1 1 - - 3 4 - 1 9 11

9 Brazoria, TX - 1 9 10 - 1 3 3 - - 4 6 - - 6 6

10 Galveston, TX - 2 9 11 - 2 8 9 - 2 12 15 - 1 9 9

11 Chambers, TX - - - - - - - - - - 1 1 - - - -

12 Jefferson, TX - 2 5 6 - 5 9 9 - 2 9 10 - 3 6 6

13 Cameron, LA 2 10 13 15 5 35 41 41 - 7 18 20 2 13 16 19

14 Vermilion, LA 4 9 10 10 8 22 24 24 1 9 12 12 4 8 9 9

15 Iberia, LA 1 2 3 3 1 5 6 6 - 5 7 7 1 2 3 3

16 St. Mary, LA - 1 1 1 - 1 1 1 - - - - - - - -

17 Terrebonne, LA - 1 1 1 - 2 2 2 - - 5 6 - 1 1 1

18 Lafourche, LA - - - - - - - - - - 1 1 - - - -

19 Jefferson, LA - - 1 1 - - - - - - - - - - - -

21 St. Bernard, LA - - - - - - - - - - - 1 - - - -

 

62 Texas Coastline - 6 45 68 - 8 23 24 - 5 37 47 - 6 38 52

63 Louisiana Coastline 8 23 28 30 14 64 75 76 2 21 43 49 6 23 30 32

64 Mississippi Coastline - - - - - - - - - - - 1 - - - -

67 Tamaulipas, Mexico - - - 1 - - - - - - 2 2 - - 1 3

Note: Values of <0.5% are indicated by “-”. Any areas where the percent chance within 120 days of all seasons 

are all <0.5% are not shown. See Figure C-1 for the location of Launch Point One. See Figure C-2 for the 

location of the named land areas. 
BOEMRE-OSRA Catastrophic Run C-15 

Table C-2 

 

Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at Launch Point Two 

Will Contact a Certain Parish, County, or Coastline within 120 Days 

 Season Winter Spring Summer Fall 

 Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120

ID Name Percent Chance 

1 Cameron, TX - - - - - - - - - - - 1 - - - -

2 Willacy, TX - - - - - - - - - - - 1 - - - -

3 Kenedy, TX - - - 1 - - - - - - - - - - - 1

4 Kleberg, TX - - - 1 - - - - - - - - - - - -

7 Calhoun, TX - - - 1 - - - - - - - - - - - 1

8 Matagorda, TX - - - 2 - - - - - - - 1 - - - 2

9 Brazoria, TX - - - 1 - - - - - - - - - - - 1

10 Galveston, TX - - - 1 - - - - - - - 1 - - - -

12 Jefferson, TX - - - 1 - - - - - - - - - - - -

13 Cameron, LA - - - 1 - - - - - - - - - - - -

14 Vermilion, LA - - - 2 - - - - - - - - - - - -

17 Terrebonne, LA - - 3 4 - - - - - - - 1 - - - 1

18 Lafourche, LA - - - 1 - - - - - - - - - - 1 1

19 Jefferson, LA - - - - - - - - - - - 1 - - 1 1

20 Plaquemines, LA 1 14 21 23 - 3 4 6 1 8 20 25 2 21 27 28

21 St. Bernard, LA - 4 5 5 - 1 2 3 1 7 14 16 - 8 9 10

22 Hancock, MS - 1 2 4 - 2 2 2 - 2 3 3 1 3 5 5

23 Harrison, MS 2 3 4 5 - 4 4 4 1 3 4 4 1 2 3 3

24 Jackson, MS 7 11 11 13 5 11 12 12 1 3 4 4 6 12 13 14

25 Mobile, AL 11 14 14 15 11 16 17 17 4 8 9 10 8 11 12 13

26 Baldwin, AL 4 7 7 9 6 14 16 17 1 8 10 10 1 2 2 3

27 Escambia, FL - 1 1 2 1 5 11 13 1 3 5 6 - - 1 1

29 Okaloosa, FL - - - 1 - 1 2 3 - - 1 1 - - - -

30 Walton, FL - - - - - 1 1 1 - - - - - - - 1

31 Bay, FL - - - 1 - 2 3 5 - - 1 2 - - - -

32 Gulf, FL - - - - - 1 3 5 - - 1 1 - - - -

33 Franklin, FL - - - - - - - 3 - - 1 2 - - - -

34 Wakulla, FL - - - - - - - 1 - - - - - - - -

36 Taylor, FL - - - - - - - 1 - - - - - - - -

38 Levy, FL - - - - - - - 1 - - - - - - - -

49 Monroe, FL - - - 1 - - - 1 - - - - - - - -

50 Dade, FL - - - - - - - 1 - - - - - - - -

 

62 Texas Coastline - - - 7 - - - - - - - 5 - - 1 6

63 Louisiana Coastline 2 18 29 37 - 4 6 9 1 15 34 43 2 29 39 41

64 Mississippi Coastline 9 15 17 22 5 16 18 19 3 7 11 12 7 16 21 22

65 Alabama Coastline 15 21 21 24 18 30 34 34 5 16 19 20 9 13 14 15

66 Florida Coastline - 2 2 6 1 10 20 36 1 3 10 14 - - 1 2

67 Tamaulipas, Mexico - - - 1 - - - - - - - 1 - - - 1

Note: Values of <0.5% are indicated by “-”. Any areas where the percent chance within 120 days of all seasons are all <0.5% 

are not shown. See Figure C-1 for the location of Launch Point Two. See Figure C-2 for the location of the named land 

areas. 
C-16 Central Planning Area Supplemental EIS 

Table C-3 

 

Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at Launch Point Three 

Will Contact a Certain Parish, County, or Coastline within 120 Days 

 Season Winter Spring Summer Fall 

 Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120

ID Name Percent Chance 

1 Cameron, TX - - - 2 - - - - - - - 2 - - - 2

2 Willacy, TX - - - 3 - - - - - - - 2 - - - 3

3 Kenedy, TX - - - 8 - - - 1 - - - 9 - - - 5

4 Kleberg, TX - - 1 6 - - - - - - - 4 - - 1 6

5 Nueces, TX - - 1 6 - - - - - - - 2 - - 1 2

6 Aransas, TX - - - 5 - - - 1 - - - 3 - - - 2

7 Calhoun, TX - - 1 6 - - - - - - - 6 - - 1 4

8 Matagorda, TX - - 2 17 - - 3 4 - - - 11 - - 1 6

9 Brazoria, TX - - 3 12 - - 1 3 - - 2 8 - - 1 5

10 Galveston, TX - - 3 10 - - 3 6 - - 2 5 - - 1 4

12 Jefferson, TX - - 1 4 - - 7 9 - - 1 1 - - - 2

13 Cameron, LA - - 1 4 - - 11 12 - 1 1 4 - - - 4

14 Vermilion, LA - - 1 2 - - 5 6 - 1 1 2 - - - -

15 Iberia, LA - - - 1 - - 4 4 - - - - - - - -

17 Terrebonne, LA - 1 2 3 - 4 12 14 - - - 2 - - - -

18 Lafourche, LA - - 1 1 - 2 8 10 - - 1 2 - - - -

19 Jefferson, LA - - - 1 - - 2 2 - - 1 1 - - - -

20 Plaquemines, LA - - - 1 - 2 10 12 - - 1 2 - - - -

24 Jackson, MS - - - - - - 1 1 - - - - - - - -

26 Baldwin, AL - - - - - - 1 1 - - - - - - - -

31 Bay, FL - - - - - - - 1 - - - - - - - -

33 Franklin, FL - - - 1 - - - - - - - - - - - -

49 Monroe, FL - - - - - - - - - - - 1 - - - 1

50 Dade, FL - - - - - - - - - - - 1 - - - -

 

62 Texas Coastline - - 12 78 - - 14 24 - - 6 54 - - 4 41

63 Louisiana Coastline - 1 6 14 - 9 52 60 - 1 4 13 - - - 6

64 Mississippi Coastline - - - - - - 1 1 - - - - - - - -

65 Alabama Coastline - - - - - - 1 1 - - - - - - - -

66 Florida Coastline - - - 1 - - 1 4 - - - 2 - - - 2

67 Tamaulipas, Mexico - - - 4 - - - 1 - - - 10 - - - 10

68 Veracruz-Llave, Mexico - - - - - - - - - - 1 7 - - - 1

69 Tabasco, Mexico - - - - - - - - - - - 1 - - - -

Note: Values of <0.5% are indicated by “-”. Any areas where the percent chance within 120 days of all seasons 

are all <0.5% are not shown. See Figure C-1 for the location of Launch Point Three. See Figure C-2 for the 

location of the named land areas. 
BOEMRE-OSRA Catastrophic Run C-17 

Table C-4 

 

Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at Launch Point Four 

Will Contact a Certain Parish, County, or Coastline within 120 Days 

 Season Winter Spring Summer Fall 

 Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120

ID Name Percent Chance 

1 Cameron, TX 1 3 3 3 - - - - - - - - - 2 3 3

2 Willacy, TX 3 4 4 4 1 1 1 1 - 1 1 1 3 7 8 8

3 Kenedy, TX 10 22 23 23 7 9 9 9 3 9 9 9 10 21 22 23

4 Kleberg, TX 9 14 15 16 12 14 14 14 9 17 17 17 7 13 14 14

5 Nueces, TX 10 16 17 18 21 26 26 26 8 17 18 18 11 16 17 17

6 Aransas, TX 11 15 16 16 28 33 33 33 17 26 26 26 9 12 13 13

7 Calhoun, TX 7 12 13 14 12 15 15 15 18 25 26 26 7 11 12 12

8 Matagorda, TX 1 3 3 4 1 2 2 2 - 2 2 2 - 1 2 3

9 Brazoria, TX - - - - - - - - - - - - - - 1 1

 

62 Texas Coastline 51 90 94 98 82 99 100 100 56 98 100 100 48 84 91 93

67 Tamaulipas, Mexico - 1 2 2 - - - - - - - - - - 1 1

Note: Values of <0.5% are indicated by “-”. Any areas where the percent chance within 120 days of all seasons 

are all <0.5% are not shown. See Figure C-1 for the location of Launch Point Four. See Figure C-2 for the 

location of the named land areas. 
C-18 Central Planning Area Supplemental EIS 

Table C-5 

 

Conditional Probabilities Expressed as Percent Chance that an Oil Spill Starting at Launch Point Five 

Will Contact a Certain Parish, County, or Coastline within 120 Days 

 Season Winter Spring Summer Fall 

 Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120

ID Name Percent Chance 

1 Cameron, TX - - 2 4 - - - - - - 2 3 - - 3 5

2 Willacy, TX - - 1 4 - - - - - - 2 3 - - 2 3

3 Kenedy, TX - 1 8 14 - - 1 1 - - 4 7 - - 6 9

4 Kleberg, TX - - 5 7 - 1 2 2 - - 1 3 - - 4 5

5 Nueces, TX - 1 5 9 - 1 2 2 - - 1 1 - - 3 5

6 Aransas, TX - 1 5 10 - - 3 3 - - 2 3 - - 4 6

7 Calhoun, TX - 2 10 20 - 3 11 12 - - 7 9 - 1 5 7

8 Matagorda, TX - 1 8 14 - 18 29 30 - 2 12 21 - 2 9 15

9 Brazoria, TX - - 3 4 - 9 13 13 - - 7 12 - 1 4 6

10 Galveston, TX - 1 2 4 - 3 11 13 - - 5 12 - 1 2 3

12 Jefferson, TX - - - 1 - - 12 15 - - 1 4 - - - 1

13 Cameron, LA - - - 1 - 1 5 6 - - 6 8 - - - -

14 Vermilion, LA - - - - - - 2 3 - - 1 2 - - - -

20 Plaquemines, LA - - - - - - - - - - - 1 - - - -

 

62 Texas Coastline - 7 50 91 - 35 85 90 - 2 43 79 - 5 43 65

63 Louisiana Coastline - - - 1 - 1 8 9 - - 8 11 - - - -

67 Tamaulipas, Mexico - - 1 6 - - - - - - 3 7 - - 2 11

68 Veracruz-Llave, Mexico - - - - - - - - - - - 1 - - - -

Note: Values of <0.5% are indicated by “-”. Any areas where the percent chance within 120 days of all seasons 

are all <0.5% are not shown. See Figure C-1 for the location of Launch Point Five. See Figure C-2 for the 

location of the named land areas. 
APPENDIX D 

 

DEEPWATER HORIZON EVENT CHRONOLOGY
Deepwater Horizon Event Chronology D-3 

APPENDIX D. DEEPWATER HORIZON EVENT CHRONOLOGY 

On April 20, 2010, the Deepwater Horizon (DWH) mobile offshore drilling unit (MODU), a 

dynamically positioned semisubmersible exploratory drilling rig owned by Transocean Ltd. and leased to 

BP Public Liability Company, exploded at approximately 9:48 p.m. CDT and began to burn 

uncontrollably. The Deepwater Horizon was in the process of temporarily abandoning an exploratory 

well that had reached a total depth below mudline of approximately 13,000 feet (ft) (3,962 meters [m]; 

2.46 miles [mi]; 3.96 kilometers [km]). British Petroleum’s (BP’s) exploration prospect, Macondo, was 

located on a lease acquired in 2006 (OCS-G 32306) in Mississippi Canyon Block 252 located about 53 mi 

(85 km) southeast of the nearest land at the end of the Mississippi River’s “birdfoot” delta. BP as the 

lease owner had contracted with Transocean to drill the well to BP’s specifications for $533,000 per day 

(Urbina, 2010). 

In the immediate aftermath of the explosion and fire, dozens of survivors were recovered from the 

water and from emergency escape craft and were airlifted to area medical facilities onshore. In the hours 

after the explosion, the U.S. Coast Guard (USCG) managed a firefighting effort among vessels on the 

scene. The rig burned for 36 hours and, after a final explosion, sank on April 22, 2010, at 10:22 a.m. 

CDT in 4,992 ft (1,521 m) of water with approximately 700,000 gallons of diesel fuel on board. Eleven 

members of the 126-member crew were unaccounted for. After a search mission with 28 aircraft and 

vessels reported to have covered 5,375 mi2

 (13,920 km2) (Polson, 2010), on April 23, the 11 crew 

members were presumed dead by the USCG. Their bodies were never found. The spill that resulted from 

the rig’s explosion and sinking before the well was finally capped on July 15, 2010, would become the 

largest spill caused by a blowout (Table D-1) and was almost twice as large as the largest tanker spill 

(Table D-2). 

On April 24, 2010, search and recovery vessels on site reported oil at the surface, which was later 

determined to be from two subsurface leaks; one from the collapsed riser assembly lying on the sea 

bottom at the point of detachment from the sunken rig and one from the top of the blowout preventer 

(BOP) at a point where the riser ruptured at a kink that formed as it folded over after the rig sank. BP 

believed that about 85 percent of the leak was coming from the end of the riser lying on the sea bottom, 

with the rest coming from the kinked riser above the BOP. The first estimate of a spill rate—1,000 

barrels (bbl)/day—was made by BP and the USCG on April 24, 2010. From this first estimate, 

disagreements were reported in print media, but the trend line was that all subsequent estimates were 

consistently higher (see “Amount of Oil Spilled” below).

BP managed well control operations with a command center located at their facilities in Houston, 

Texas, from where engineers could monitor and control activity on the scene. Efforts to activate the BOP 

by remotely operated vehicles (ROV’s), among them the 3-ton, 220-horsepower Millennium Plus, began 

on April 25 and were abandoned as ineffective during the first week in May. Webb (2010) reported on 

July 18, 2010, that field modifications to the BOP were made by Transocean in 2005, the design drawings 

for which were not readily available, making it difficult for engineers to understand its configuration with 

ROV’s. On April 28, 2010, Robertson (2010) reported that a third leak had been discovered in the riser 

near the wellhead. This leak was stopped on May 5 when an ROV closed a shut-off valve (Mowbray, 

2010). Also on April 28, the National Oceanic and Atmospheric Administration (NOAA) estimated a 

leak rate of 5,000 bbl/day based on observations made in flights over the slick and by studying its 

trajectory. 

The first in-situ surface burns of oil were carried out on April 28, 2010. Surface burns first required 

vessels to skim the water surface with floating, fireproof booms to corral oil into concentrated areas. 

Collected slicks were then set alight with an improvised gasoline torch system. Under 40 CFR 300.323, a 

“spill of national significance” may be declared by the Administrator of the U.S. Environmental 

Protection Agency (USEPA) for discharges occurring in the inland zone and by the Commandant of the 

USCG for discharges occurring in the coastal zone. On April 29, 2010, when it was clear the sinking 

caused an uncontrolled blowout, Department of Homeland Security Secretary, Janet Napolitano, declared 

the event a spill of national significance to allow response personnel and equipment from other parts of 

the country to be more easily mobilized and moved into the area. On the same day, the Governor of 

Louisiana, Bobby Jindal, declared a state of emergency. BP mobilized two MODU’s during the first 

week of May 2010 to drill relief wells as the final stage for shutting down the well. Transocean’s 
D-4 Central Planning Area Supplemental EIS 

Development Driller III began the first relief well about a one-half mile from the Macondo well on 

May 2, 2010. A second relief well was begun by Transocean’s Development Driller II on May 16, 2010. 

The Oil Pollution Act of 1990 places liability for spills on the lease operator and charges the Federal 

Government with oversight for spill-response activity, the details for which were unspecified. Soon after 

the explosion and sinking of the Deepwater Horizon evidence for an oil spill was observed on April 24. 

On April 24, a Unified Incident Command (UIC) Center was first established in Robert, Louisiana. 

On June 15, plans were announced to move UIC from Robert to New Orleans, Louisiana. The UIC 

managed response operations, prepared maps and status reports, maintained an official Deepwater 

Horizon Response website, and provided a forum for consensus decisionmaking among the organizations 

responsible for spill response. The UIC had Incident Command Centers in Houma, Louisiana; Mobile, 

Alabama; and Miami, Florida. Together, these Centers were referred to as the Unified Area Command. 

On May 1, 2010, Admiral Thad Allen (USCG, retired) was designated by Department of Homeland 

Security Secretary Napolitano as National Incident Commander. Each Federal agency involved with 

spill-response activity reported to the National Incident Commander. Rear Admiral Mary Landry 

(USCG) was responsible for on-scene offshore response activity and Administrator Lisa Jackson 

(USEPA) was responsible for response activity onshore. The UIC included management and staff 

representatives from the Department of Homeland Security, Department of Defense, Department of the 

Interior (DOI), Department of Commerce (DOC), USEPA, and other Federal departments and agencies, 

in addition to BP as the responsible party. As many as 2,400 people staffed the Unified Area Command 

in August that dropped quickly to 550 people in September (White, 2010). Table D-3 shows the number 

of people managed by UIC during spill response activities from April 2010 through January 2011. The 

National Incident Commander responsibilities were transferred from Thad Allen to USCG Rear Admiral 

Paul Zukunft on October 1, 2010 (White, 2010). 

Early Response and Containment Efforts 

On April 30, the Department of Defense approved a request by USCG for two C-130 aircraft with 

Modular Aerial Spray Systems to begin application of dispersants at the surface (The White House Blog, 

2010), and also on April 30, UIC authorized a new technique to break up spilling oil before it reached the 

surface by using an ROV to inject subsurface dispersant into the flow stream at the top of the BOP. An 

application of 9 gallons of dispersant per minute was applied (Gelsi, 2010). The USEPA Administrator, 

Lisa Jackson, was concerned about the open-ended use of dispersant chemicals designed to break oil into 

particles that can be digested by bacteria. The spill was requiring BP to use unprecedented amounts of 

dispersant. One dispersant, Corexit 9500 (Corexit), was available in large quantities; therefore, BP was 

deploying it on the surface and at the subsurface spill site. On May 20, USEPA and the Department of 

Homeland Security gave BP 24 hours to find a less biotoxic alternative and to apply the new dispersant(s) 

within 48 hours of submitting the list of alternatives, or explain why they could not do so (U.S. Dept. of 

Homeland Security and USEPA, 2010). At the time, it was believed that Corexit may have been one of 

the more biotoxic dispersant options among those available. BP responded by letter on May 20 that 

makers of other dispersants would not be able to supply large volumes of alternative dispersants for 10-14 

days and intended to keep using Corexit. On May 24, USEPA reauthorized BP to inject Corexit into the 

spill stream at the wellhead, but determined that BP’s response to USEPA’s directive to find substitute 

dispersants was “insufficient” and that surface applications of dispersant be minimized (Cart and Simon, 

2010). On May 26, 2010, USEPA (2010) informed BP that, given the lack of alternatives, the Agency 

would not stop BP from using Corexit, but that BP would have to “significantly” reduce dispersant use 

and to look for alternatives for Corexit. As of July 15, 2010, the last time subsurface dispersants were 

used, the Unified Area Command reported that 771,272 gallons were injected at the wellhead. As of 

July 20, 2010, the last date surface dispersants were used, the Unified Area Command reported 

(Deepwater Horizon Response, 2010a) that BP had sprayed 1,072,514 gallons of dispersant on the surface 

of the water. 

On May 5, 2010, a barge towed a purpose-built 40 ft x 24 ft x 14 ft (12 m x 7 m x 4 m) 100-ton steel 

Cofferdam containment dome to the site of the spill. At the top of the dome, there was a riser system to 

carry leaking oil to the Discoverer Enterprise drillship at the rate of ~15,000 bbl/day. The 

semisubmersible Helix Q4000, a dynamically positioned MODU specifically designed for well 

intervention, began to lower the Cofferdam containment dome on May 6, 2010. On May 7, it was placed 
Deepwater Horizon Event Chronology D-5 

over the BOP stack. The Cofferdam containment dome system and procedure was abandoned the next 

day after methane hydrates (methane gas incorporated in an ice matrix) formed at the riser opening, made 

the Cofferdam containment dome buoyant, lifted it off of the well, and made it uncontrollable at the 

surface, rendering this containment strategy useless. 

On May 16, 2010, BP sought to begin capture, flowing subsurface oil by siphoning it from the broken 

riser pipe. A riser insertion tube tool was designed to recover and collect oil in the Transocean 

dynamically positioned drillship Discoverer Enterprise, which had been deployed to the scene. A tube 

was inserted into the end of the broken riser lying on the bottom and a rubber diaphragm seated the riser 

insertion tube tool against the riser walls to form a seal. Nitrogen gas was injected to reduce methane 

hydrate formation. The riser insertion tube tool system was partially successful. It captured 

approximately 22,000 bbl of oil, but it never captured the total flow of oil from the riser opening, which at 

that time was estimated to be ~5,000 bbl/day. Based partly on the results of the riser insertion tube tool 

system capturing oil, the spill rate was revised to approximately 12,000-19,000 bbl/day (USDOI, 2010a). 

On May 25, 2010, the riser insertion tube tool system was abandoned in preparation for a well shutdown procedure called “top kill.” Top kill involved pumping heavy drilling mud under pressure through 

two 3-in-diameter flowlines into the BOP to force the oil downhole. BP began the “top kill” procedure on 

May 26 at 1:00 p.m. CDT and followed initiation with the first of two “junk shots,” an operation 

involving the injection of pieces of rope, shredded rubber, golf balls, and other materials into the flow 

lines of the BOP in an effort to clog it. Neither the top kill nor the junk shot came close to succeeding 

because the pressure of oil and gas escaping from the well was greater than the pressure that could be 

applied by force-injected drilling mud. On May 30, Kaufman and Krauss (2010) quoted a BP source as 

stating that engineers never had a complete enough understanding of the drill pipe casing configuration or 

the field modifications that had been made to the BOP mechanism to be confident in success of the 

procedures. Krauss et al. (2010) recounted that, for the first hours of the first top kill procedure, 

downhole pressure began to decrease; a sign that the pumped-in drilling mud was succeeding in 

overcoming the pressure of the oil venting from the reservoir. Shortly thereafter, the pressure readings 

leveled off, indicating that drilling fluid was leaking into the formation or venting through the BOP. Had 

the junk shot and top kill worked in combination to equalize the pressure, flowing gas and oil would have 

been arrested and the well-killing operation would be completed by downhole injection of cement to seal 

the well. The first top kill attempt was followed shortly by a second on May 28, 2010, but at 1:30 a.m. 

CDT, BP announced that this procedure had failed to equalize pressure, with oil and gas venting from the 

wellbore; and the cementing phase was not attempted. 

In a June 22, 2010, interview in the Los Angeles Times (Tankersley, 2010a), Energy Secretary Steven 

Chu stated that engineers working to cap the Macondo oil spill should have acted sooner to attempt the 

top kill method to overpower and seal the well in order to boost its chances for success. Tankersley 

(2010b) reported that imaging equipment use by DOE detected not one but two drill pipes, side by side, 

inside the wreckage of the well’s BOP and hypothesized that either the well casing or part of the drill 

string was explosively forced up the well by the erupting gas bubble, violently telescoping the pipe while 

slamming it into the bottom of the BOP. 

The next containment option was to deploy a system called the lower marine riser package cap 

containment system, also called “top hat.” On May 12, 2010, the top hat, called “top hat No. 4,” was 

placed on the seabed near the wellhead while the drillship Discoverer Enterprise was constructing and 

lowering the riser system that would bring captured oil to the surface after failure of the Cofferdam 

containment dome. On June 3, 2010, an ROV cut off the end of the broken riser pipe at the top of the 

BOP to leave a cleanly cut pipe. After a 20-hour procedure, the sealing cap was affixed to the top of the 

riser, and captured oil and gas began to flow through the riser to the Discoverer Enterprise. The amount 

of oil recovered by this system was ~10,000 bbl/day, much more than expected and beyond the capacity 

of the Discoverer Enterprise. The oil that could not be captured was vented through the “top hat” to the 

ocean. The result of a fitting “top hat” was that downhole pressure from the well could be measured more 

accurately and as a result the UIC revised the estimate for well flow rate to between 25,000 and 40,000 

bbl/day. 

By mid-June 2010, a small fleet of vessels had been contracted by BP as part of the spill response and 

had assembled on the surface. On June 16, BP connected the choke lines that were used to pump mud 

into the BOP for the “top kill” procedure to a separate riser system connected to the Helix Q4000 vessel 

as an addition to the lower marine riser package collection system. A specialized clean-burning flare 
D-6 Central Planning Area Supplemental EIS 

system was installed on the Deepwater Discoverer to burn a combination of oil and gas at the surface, and 

the Helix Q4000 flared gas collected through the choke line system. On June 23, Robbins (2010) reported 

that an ROV impacted the top hat cap and caused it to dislodge and come off. After eight attempts the 

cap was re-affixed onto the lower marine riser package, and the system was again capturing oil and gas 

released from the well. By late June and early July, BP’s website was reporting that the “top hat” cap on 

the lower marine riser package and the Deepwater Discoverer and Helix Q4000 flare systems in 

combination were collecting or burning over 25,000 bbl/day and about 50 Mcf of gas. The loose-fitting 

top hat collected most of the oil and operated until July 10, but the system never could accommodate the 

total flow of oil from the well head, and part of the flow still vented into the ocean during the entire 

period of its use from June 3 to July 10, 2010. The Department of Energy’s (DOE’s) spill-response 

website includes spreadsheets reporting the quantity of oil and gas captured by the riser insertion tube 

tool, and “top hat’ systems (USDOE, 2010). The spill flow rate estimate was revised by the Flow Rate 

Technical Group to 20,000-40,000 bbl/day by examining the flow plume after the riser pipe was cleanly 

cut before emplacement of the top hat and lower marine riser package. 

Hurricane Alex made landfall at Matamoros, Mexico, on June 30, 2010, and moved inland. The 

storm raised high seas and winds in the spill area, bringing oil skimming, application of aerial dispersants, 

and burning operations to a halt until July 5, 2010. The rigs drilling the relief wells remained on station 

throughout the weather stand down. On July 2, USCG officials began flying over the oil-spill site to 

assess the damage left by Hurricane Alex, noting dislodged boom along the shoreline. 

On June 17, 2010, the Associated Press (2010) reported that BP had committed to deploy 32 

centrifugal-based oil separation systems from Ocean Therapy Solutions, a company that was co-founded 

by Kevin Costner. The first three devices were barged to the spill site for testing. The system, called 

Ocean Therapy, skims and pumps oily water onto barges, where a centrifuge unit separates oil from water 

that is then returned to the sea. Each device can process approximately 200,000 gallons (4,762 bbl) of 

oily water per day. 

On June 25, 2010, with no assurances it would be contracted by BP or allowed by UIC to join the 

Gulf of Mexico oil-spill cleanup, a Taiwanese-owned ship billed as the world’s largest skimming vessel, 

A Whale, embarked from Norfolk, Virginia, for the Gulf of Mexico. A Whale is approximately 1,050 ft 

(320 m) long and 10 stories high. It is designed to collect up to 500,000 bbl of oily water a day through 

six intake vents on each side of its bow. Skimmed oily water was designed to be processed and separated, 

with oil stored in holding tanks and with processed water eventually discharged back to the sea. Approval 

from USEPA was needed because of the residual oil in discharged water. A Whale arrived at the spill site 

on July 2, 2010, and deployed to a location north of the source to begin ballasting to intake water level for 

skimming. Testing of the system began on July 6 and a series of modifications were made to adjust 

system performance until July 16 when the evaluation was ended. On July 17, 2010, A Whale departed 

the area after not performing as expected. Fountain (2010a) reported that the dispersed nature of the spill 

tended to work against A Whale’s skimming system, which was designed to intake a more dense and 

concentrated oil slick. 

The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling released 

periodic staff working papers on topical issues that were within the Oil Spill Commission’s area of 

investigation. Staff Working Paper 6 (Oil Spill Commission, 2011a) presented a detailed explanation of 

the 5-month effort to permanently plug the Macondo spill. 

Engineered Shoreline Barriers 

On May 11, 2010, the State of Louisiana submitted an emergency application to the Corps of 

Engineers (COE) for the dredging of sand to build a “barrier berm” system to prevent oil from entering 

coastal marsh lands. The berms were proposed to be emergent structures extending along the length of 

the Chandeleur Islands and the barrier islands from East Grand Terre Island eastward to Sandy Point. The 

dimensions are approximately 50 ft (15 m) wide at the base and 20 ft (6 m) wide at the top, built at the toe 

of existing barrier islands or in tidal inlets between existing islands. Originally, the borrow sources for 

the berm material were to be a shore-parallel trench dredged approximately 1 mi (1.6 km) offshore of the 

Chandeleur Islands, Ship Shoal on the OCS, the Mississippi River offshore disposal site, and the Pass a 

Loutre hopper disposal area. On May 14, 2010, the consulted Federal agencies provided written feedback 

to COE on the nature of the State’s proposed action, and on that same date, the State submitted a revised 
Deepwater Horizon Event Chronology D-7 

plan to COE. This revised plan extended the reach westward to Timbalier Island and removed the 

nearshore borrow trench along the Chandeleur Islands. The COE requested additional information, and 

on May 21 and May 24, 2010, that information was provided by the State. On May 27, COE approved 

elements of the State’s proposal, which includes six segments of barriers about 40 mi (64 km) long that 

included, from the State’s application, Segments E3 and E4 (25.8 mi; 41.5 km) along the northern part of 

the Chandeleur chain east of the Mississippi River and Segments W8, W9, W10, and W11 (14.5 mi; 

22.3 km) along the Plaquemines Parish barrier island shoreline west of the Mississippi River. The UIC 

gave immediate go-ahead on just one of those six segments, i.e., a 2-mi (3-km) barrier berm off Scofield 

Island (Segment W9) in Plaquemines Parish, where oil was already reported, and using sand from the 

Pass a Loutre Hopper Dredge Disposal Site. On June 1, 2010, UIC convened a meeting in New Orleans 

to discuss the State’s proposal. The State had proposed that BP be required to pay the estimated $360 

million for the barrier berm project as part of the integrated spill response. After a variety of viewpoints 

were expressed in the June 1 meeting, UIC required BP to pay for only the Scofield Island segment in 

western Plaquemines Parish. 

Federal officials permitted the project after the State agreed to dredge sand to build the berms from a 

borrow site north of the Chandeleur chain, Hewes Point. From Hewes Point, sand was to be transported 

by slurry through a submerged pipeline to the berm construction site. On June 2, UIC ordered BP to pay 

for all 40 mi (64 km) of berm authorized, and on June 13, construction work on the first berm segment 

began at the Chandeleur Islands. Despite the borrow site agreement, on June 13, 2010, the State asked the 

Federal Government for permission to dredge sand from a nearshore location positioned over the preKatrina footprint of the Chandeleur Islands (south of Hewes Point) and within the boundaries of the 

Breton National Wildlife Refuge, after apparently having trouble procuring the length of pipeline needed 

to pump from Hewes Point. The COE and FWS agreed to let the State dredge from this nearshore 

location for 1 week while waiting on dredge pipe, provided they backfilled the dredge pit immediately. 

On June 14, the cutterhead dredge California arrived and began to set pipe between the dredge at the 

nearshore borrow site and the berm construction site. Over 10 support vessels, including barges, crew 

quarters, and ferries, were mobilized at the site. On June 22, the State asked for permission for another 

5-10 days of sand borrowing from the nearshore borrow site, promising to eventually replace the sand 

borrowed. Assistant Secretary of the Interior, Thomas Strickland, rejected Louisiana’s request for the 

additional 10 days to construct 2 mi (3 km) of pipeline and ordered the dredging from the nearshore 

location to stop while the pipeline was constructed to Hewes Point. On June 30, 2010, COE gave the 

go-ahead for the State to resume dredging after the additional pipeline was laid to transport sand from the 

designated borrow site at Hewes Point. The State’s contractors did not resume dredging because of 

inclement weather caused by the passage of Hurricane Alex. In an open letter to UIC released on July 21, 

2010, a group of 21 coastal scientists called for a halt to large-scale engineering projects, such as 

Louisiana’s barrier berms and rock armoring, aimed at protecting wetlands from oil from Macondo 

(Spotts, 2010). 

On May 14, 2010, Louisiana’s Office of Coastal Protection and Restoration requested a lease from 

BOEMRE to use Ship Shoal and St. Bernard Shoals sand for the emergency berm construction. A 

negotiated emergency sand agreement was executed between the Office of Coastal Protection and 

Restoration and BOEMRE on July 16, 2010, for the use of OCS sand from St Bernard Shoals for 

construction of the E3 and E4 berm segments along Chandeleur Islands. However, no OCS sand was 

used during berm construction because of Endangered Species Act issues related to hopper dredging and 

sea turtle takes, as well as DWH’s Federal on-scene coordinator’s denial of Louisiana’s request for 

concurrence with planned OCS sand mining activity as part of the spill response. 

On August 3, 2010, the UIC Daily Report reported that 1,330,309 yd3 (1,017,094 m3

) (Hewes Point) 

were borrowed for Chandeleur Segment E4 and that 134,042 yd3 (102,483 m3

) were borrowed for 

Scofield Island Segment W9 (Pass a Loutre borrow site) (U.S. Dept. of Homeland Security, CG, 2010). 

In addition to the sand berm project, multiple smaller-scale efforts were initiated by the State in an 

attempt to block oil from entering estuaries and interior wetlands. Blackhawk and Chinook helicopters 

manned by the Louisiana National Guard dropped 7,000-lb sandbags one by one into the sea (Muir, 

2010). On May 26, 2010, the Governor’s office website posted that the National Guard dropped over 

1,075 sandbags on Pelican Island, east of Grand Isle, filling five of the eight gaps in the island and that 

bags were also dropped in the first gap out of six expected to be filled on Scofield Island (State of 

Louisiana, Office of the Governor, 2010). 
D-8 Central Planning Area Supplemental EIS 

With oil reported in Barataria Bay as early as May 2010, local parish officials proposed a plan, 

supported by the Governor of Louisiana, to build rock dikes across several major tidal inlets between the 

bay and the Gulf of Mexico to block and then capture the oil. Rudolf (2010a) reported that by early June, 

about 100,000 tons of rock had been loaded onto barges on the Mississippi River for transport to the 

coast; however, on July 3, 2010, COE denied a permit for the project, citing concerns that rock barriers 

could alter tidal flow patterns and cause widespread erosion and breaching of Barataria Bay’s existing 

barrier islands. 

On August 5, 2010, Scott (2010) reported that the State’s dredging contractors had moved about 

5,000,000 yd3

 (3,822,774 m3) of sediment to construct 4 mi (6.5 km) of berm near Scofield Island 

(Segments W9 and W10) to create narrow artificial islands to block oil moving into coastal wetlands, at a 

cost to BP of $120 million. On September 15, the Louisiana Governor’s Office of Coastal Activities 

posted a website update of the State’s berm construction activities and reported that an estimated 8.5 mi 

(13.6 km) of berm had been constructed (State of Louisiana, Office of Coastal Protection and Restoration, 

2010). 

On October 6, Ball (2010) reported that the State was scaling back their extensive dredging program 

that had been designed for, and justified as, part of the spill response to contain oil. Rudolf (2010b) 

reported that the State had significantly altered its original proposal, allowing for large gaps between the 

berm segments to ease concerns that tidal circulation in estuaries would be adversely affected. The article 

contained a graphic that showed completed, under construction, and planned berm in the following two 

focus areas: Scofield Island and the northern Chandeleur Islands. 

During a November 10, 2010, multiagency teleconference that included the State, BOEMRE, and 

COE, the State’s emphasis on the berms as an oil-spill-response measure transitioned to an emphasis on 

the berms as a coastal restoration measure. The State reported the following: (1) their desire to cease 

berm work by November 30; (2) their desire to use the remainder of berm funding (~$100 million) on 

new or continued barrier island restoration projects at Shell Island, Pelican Island (CWPPRA Project 

BA-38), Scofield Island (CWPPRA Project BA-40), and the northern part of the Chandeleur chain; (3) 

that construction of the western Plaquemines berm Segments W8, W9, and W10 were completed; (4) that 

dredging at Hewes Point continued; and (5) that the State was requesting to shift the Chandeleur E4 berm 

footprint landward (Ashworth, written communication, 2010). Berm construction ended in March 2011. 

A total of approximately 10,300,000 yd3

 of sand was placed to construct 20.5 mi (33 km) of berm, of 

which 8.8 mi (14.2 km) were constructed along the Segment E-4 along the northern Chandeleur Islands in 

St. Bernard Parish and 11.7 mi (18.8 km) were constructed along Segments W-8, W-9, and W-10 in 

Plaquemines Parish. All sand used to construct the berm was mined from Hewes Point north of the 

Chandeleur Islands (Louisiana State waters) and from the lower Mississippi River. 

The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling has 

periodically released staff working papers on topical issues the Commission dealt with. On December 16, 

Staff Working Paper 8 was posted to the Commission’s website (Oil Spill Commission, 2011b). It 

contains a more detailed summary of the Louisiana sand berms project. The working paper concludes 

that, “From a long-term coastal restoration perspective, the berms may indeed be a significant step 

forward,” as Governor Jindal has claimed, but they were not successful for oil-spill response” (Oil Spill 

Commission, 2011b, p. 39). 

The Louisiana Governor’s Office of Coastal Activities reported that at least 1,000 bbl of oil were 

captured by the berms (Oil Spill Commission, 2011b, p. 37). The staff working paper details the pressure 

exerted by Governor Jindal and Parish leaders to approve and expedite the berm projects, how President 

Obama acceded to the State’s sense of urgency, and how National Incident Commander Thad Allen’s 

approval for the State’s May 27 request for the initial 40 mi (64 km) of berms was a “borderline call.” 

Power (2010) reported on December 17 that the pleas of Louisiana’s politicians “overwhelmed” the 

Government’s scientific analysis. In a USGS evaluation of the effects of the barrier berms, Lavoie et al. 

(2010, p. 6) recommended long term monitoring for the berms completed and emphasized that although 

sand berms are intended to be sacrificial, the sand used to build them will be redistributed as berms erode 

and that berms should not be confused with and will not have the longevity of a barrier-island restoration. 

As of December 8, 2010, COE had not received permit applications from the State for any of the 

newly identified restoration projects (Ashworth, written communication, 2010). The only project with the 

potential to use OCS sand would be the Pelican Island project, which identifies the Empire and Sandy 

Point borrow sites in West Delta leasing area as an alternative. 
Deepwater Horizon Event Chronology D-9 

Permanently Plugging the Macondo Well 

To resolve the spill, a tightly fitting “capping stack” was needed on the BOP; but first, what was left 

of the severed riser pipe had to be removed from the top of the BOP. On July 10, 2010, the “top hat 

No. 4” system was removed to replace it with a better-fitting cap consisting of a flange transition spool 

and a 3-ram stack, known informally as “top hat No. 10.” Krauss et al. (2010) reported that the procedure 

involved loosening five large bolts to remove the broken riser pipe and to provide a clean connection 

between it and the capping stack, which could be bolted down to withstand reservoir pressure. At 

12:00 p.m. CDT on July 15, oil and gas recovery activity stopped and an “integrity test” of well pressure 

was carried out by slowly closing the valves on the stack. Pressure in the wellbore rose and choked off 

the flow on July 15—after 87 days. On that day, separate press conferences were held by BP and UIC to 

announce that the Macondo well had been “shut in.” 

On July 19, Fountain (2010b) reported that the recently capped well was maintaining pressure and 

that BP hoped to keep the well shut in until it could be permanently plugged with the “bottom kill” 

technique with one or both relief wells. By July 7, the Development Driller III had drilled the first relief 

well to a depth of 12,780 ft (3,895 m) below mudline, and the Development Driller II had drilled the 

second relief well to a depth of approximately 8,900 ft (2,713 m) below mudline. Since shutting in the 

well, BP continued the “ranging” process, i.e., periodically withdrawing the drill pipe and sending an 

electrical signal down to determine how close they were getting to the metal casing string in the Macondo 

well. 

Between July 20 and 25, 2010, all UIC spill operations were shut down because of Tropical Storm 

Bonnie. Reconnaissance after Bonnie showed that, out of the 508 mi (817 km) of boom in the Louisiana 

area, 95 mi (153 km) of boom was displaced (18%), 32 mi (51 km) of boom was stranded on the beach 

(6%), and 381 mi (613 km) of boom remained set in place (75%). 

On August 3, a “static kill” procedure was initiated; this procedure involved equalizing pressure from 

the reservoir with mud pumped downhole through the wellhead. Over a period of 8 hours, drilling mud 

was slowly pumped into the well at ~2 bbl per minute until a static condition was achieved. On August 4, 

BP began pumping cement from the top, permanently sealing the upper part of the casing string. On 

September 3, 2010, the 300-ton failed BOP was removed from the wellhead and was lifted slowly to the 

surface. Later that day, a replacement BOP was affixed to the wellhead. On September 4, the failed BOP 

reached the surface and was placed in a special container on board the vessel Helix Q4000 and sealed as 

evidence by the Department of Justice for the spill investigation. The failed BOP was taken to NASA’s 

Michoud Facility in New Orleans, Louisiana, for forensic examination.

Drilling of the first relief well by Development Driller III was halted in early August while the static 

kill procedure was carried out. Bad weather and concerns about how an increase in pressure inside the 

well during the bottom kill would affect the well structure and stability delayed drilling for 6 weeks. 

Drilling on the first relief well resumed on September 13, 2010. At that time, the drill bit was spatially 

located about 3.5 ft (1 m) horizontally and 50 ft (15 m) vertically from the intersection point with the 

damaged well casing, a target size reported to be 8-10 in (20-25 cm) in size. Television reports 

commonly used a dinner plate as a handy reference for the target size. Engineers drilled about 30 ft (9 m) 

initially, retracted the drill pipe, and then inserted another tool to conduct a “ranging” exercise to make 

sure the well was in the right position to penetrate the wellbore. 

Fountain (2010c) that the wellbore was intersected on September 17, allowing the “bottom kill” 

operation to begin; however, before penetrating the casing, engineers first determined the nature of the 

well-bottom environment. Tests showed there was no cement or oil in the annulus at the intersection 

point. The casing was then penetrated with a special tool called a mill, after which about 100 bbl of 

cement was used in the bottom kill to seal the annulus area and what remained of the open hole in the 

casing bore itself after the static kill operation on August 3 had filled most of it. On September 19, 2001, 

after allowing time for the cement to cure, crew aboard the Development Driller III conducted a pressure 

test on the integrity of the seal for the cement that had been pumped into the Macondo well. On 

September 19, at 5:54 a.m. CDT, the test confirmed that the cement formed an effective and final seal for 

the well. On September 19 at 10:37 a.m. CDT, National Incident Commander Thad Allen declared the 

well dead (RestoreTheGulf.gov, 2010a) and that responsibility and oversight for the well would pass from 

the National Incident Commander to BOEMRE.
D-10 Central Planning Area Supplemental EIS 

Amount of Oil Spilled 

The rate at which oil was spilling from the Macondo well was a point of intense controversy from the 

very beginning because no flow meter at the wellhead could directly account for it. The Oil Spill 

Commission’s Working Paper 3 (2011c) summarized the Government’s published estimates: 

(1) April 24, 2010—1,000 bbl/day (p. 3); 

(2) April 28, 2010—5,000 bbl/day (p. 3); 

(3) May 27, 2010—12,000-19,000 bbl/day (p. 14); 

(4) June 3, 2010—20,000-40,000 bbl/day (p. 14); 

(5) June 10, 2010—25,000-40,000 bbl/day (p. 15); 

(6) June 15, 2010—35,000-60,000 bbl/day (p. 16); and 

(7) August 2, 2010—52,700-62,200 bbl/day (p.17) 

Estimates that are Government or UIC sanctioned represent a trend of ever-increasing flow rate 

estimates with the final flow rate estimate based on direct pressure measurement. After BP and the 

USCG estimated 1,000 bbl/day on April 24, 2010, and NOAA estimated 5,000 bbl/day, on May 19, the 

UIC assembled a number of interagency expert scientific teams of government and nongovernment 

specialists to estimate the quantity of oil that had been released from the well and ultimately the fate of 

that oil. A Flow Rate Technical Group, led by Secretary of Energy Steven Chu and USGS Director 

Marcia McNutt, was assembled by UIC in May 2010 to calculate the flow rate and to estimate the total 

volume of oil released. On May 27, the Flow Rate Technical Group reported their first estimated flow 

rate of 12,000-19,000 bbl/day based on the following three separate methodologies: (1) mass balance for 

visible and infrared imaged surface oil; (2) plume modeling of oil and gas escaping from the marine riser 

before the riser insertion tube tool; and (3) with 1 and 2 checked by a minimum flow rate based on the 

riser insertion tube tool and from oil escaping the tool and from the top of the kinked riser pipe. After the 

riser pipe was cut on June 3, visual examination of the flow plume through one opening allowed the Flow 

Rate Technical Group to revise upward the estimated daily flow rate to 20,000-40,000 bbl/day. After 

examining direct pressure measurements of the flow in the top hat system, on June 15, the Flow Rate 

Technical Group revised upward the estimated daily flow rate to 35,000-60,000 bbl/day. A final estimate 

of 52,770-62,200 bbl/day was made on August 2, just prior to release of the Oil Budget Calculator on 

August 4 (Lubchenco et al., 2010). 

After the well was capped on August 2, 2010, the Flow Rate Technical Group announced that an 

estimated 4.9 million bbl of oil had been released by the Macondo spill. A second interagency team, led 

by DOI and NOAA, developed a tool called the Oil Budget Calculator to determine the short term fate of 

spilled oil. The Calculator used the 4.93 million bbl estimate as its input and used direct measurements 

and the best scientific estimates then available to determine the fate of the oil (Lubchenco et al., 2010). 

On August 4, 2010, Lubchenco et al. (2010) reported that an estimated 25 percent of total spilled oil 

was removed by burning, skimming, and direct recovery from the wellhead; 25 percent of the total oil had 

naturally evaporated or dissolved; and just less than 25 percent was dispersed naturally or as a result of 

the use of dispersant chemicals. The residual amount—just over one-quarter (26%)—was reported to be 

either on or just below the surface as light sheen. Weathered tar balls in the water column are in the 

process of being degraded, have been washed ashore or have been collected from the shore, or is buried in 

sand and sediments. Lubchenco et al. (2010) did not provide the mathematical basis for how the oil was 

partitioned. That is, the tool was described, but not explained so as to be independently verifiable. 

Lubchenco et al. reported that estimates would continue to be revised based on new information and for 

the Natural Resource Damage Assessment (NRDA) being prepared by NOAA. 

The first peer-reviewed study of oil quantity from the Macondo spill was released on September 23, 

2010, by researchers at Columbia University. The Earth Institute (Nerenberg, 2010) is now referring to 

the DWH event as “the largest marine oil accident ever.” They found that 56,000-68,000 bbl/day were 

released between April and July, a total equaling 4.4 million bbl of oil, slightly less than the official 

Government estimate of 4.9 million bbl made to date. 
Deepwater Horizon Event Chronology D-11 

On November 23, 2010, the Oil Budget Calculator, the results from which were first released in 

August 4, 2010 by Lubchenco et al. (2010), was subjected to further peer review at the request of the 

National Incident Commander. The report (Federal Interagency Solutions Group, 2010) was prepared by 

a team of 15 international academic institutions, government agencies, industry experts, and others who 

called themselves the Federal Interagency Solutions Group. The report documents for the scientific 

community and other interested parties the technical underpinnings of the Calculator and provides 

recommendations for future research and refinement of the tool for possible use in future spills. 

The Federal Interagency Solutions Group (2010) developed an extensive review of the initial findings 

and revised, as necessary, the estimated short-term fate of the oil discharged from the Macondo wellhead 

through July 15, the date the well was capped. The Oil Budget Calculator’s purpose was to describe the 

short-term fate of the oil and to guide immediate efforts to respond to the emergency, guide operational 

response decisions, and provide clarity on how much oil could be captured or mitigated and how much oil 

was not recoverable (RestoreTheGulf.gov, 2010b). The Calculator was not intended to provide 

information about the impacts of the oil or indicate where the oil may now be. The Oil Budget Calculator 

used collected or reported data, such as the amount captured at the wellhead, combined with modelprojected estimates based on historical oil-spill data for similar types of oil, as well as the expertise of the 

Federal Interagency Solutions Group’s participants. 

Improvements were made to the Calculator since it was first used in August 2010. The revised Oil 

Budget Calculator was adjusted based on modified calculations and modeling, as well as additional 

knowledge about the Macondo spill provided by the science team. The revised calculations provide the 

basis for the updated budget issued in the report, as well as the best- and worst-case scenarios. The 

Federal Interagency Solutions Group’s (2010) report is largely consistent with early results released by 

the first interagency estimate (Lubchenco et al., 2010). The most significant change is a doubling of the 

expected amount of oil classified as “chemically dispersed”—revised from 8 percent to an estimated 16 

percent, with a possible range of between 10 and 29 percent. Additional data and studies during the past 

months have led the Federal Interagency Solutions Group to relax certain initial conservative assumptions 

with regard to the effectiveness of dispersant operations. The early estimate of the percentage of “other” 

(or “residual”) oil was 26 percent; the current version of the Calculator estimate is 23 percent and 

qualifies this estimate with the belief that, with high confidence, the true percentage should be between 11 

and 30 percent. A comparison between the two iterations of the Oil Budget Calculator is below. 

Oil Budget Calculator—August 4, 2010 

Category Percent of Total 

Direct recovery 17 

Burned 5 

Skimmed 3 

Chemically dispersed 8 

Naturally dispersed 16 

Evaporated or dissolved 25 

Other 26 

Source: Lubchenco et al., 2010. 

Oil Budget Calculator—November 23, 2010 

Category Percent of Total Percent Change from August 4 

Direct recovery 17 None 

Burned 5 None 

Skimmed 3 None 

Chemically dispersed 16 +8 

Naturally dispersed 13 -3 

Evaporated or dissolved 23 -2 

Other 23 -3 

Source: Federal Interagency Solutions Group, 2010. 
D-12 Central Planning Area Supplemental EIS 

The report specifically recommends future research and planning to be directed to three areas that 

would reduce the uncertainty of the estimates and that would improve future response activities. 

First, develop protocols for surface and subsurface sampling. Although oil samples were collected 

for impact assessment, samples were not systematically collected to support the development of the Oil 

Budget Calculator. For example, samples often came from skimming barges where oil and water 

mixtures in different states of degradation were blended together. Future response plans should specify 

methods for gathering proper representative samples. 

Second, develop tools for dispersed oil droplet size characterization. A major improvement in 

estimating dispersant efficiency would be possible if practical operational tools and methods existed to 

characterize droplet size distribution of subsurface oil. 

Third, develop basic models for longer-term processes. Although longer-term processes such as 

biodegradation often happen outside the timeframes of the response, understanding and being able to 

predict such longer-term changes may be useful in making response decisions. 

Cause of the Explosion and Spill 

The official record of legal causation and responsibility for the DWH event has yet to be written. 

Legal proceedings to affix responsibility and damages for the spill will proceed for years. The outputs for 

all of the official inquiries initiated after the Macondo spill are summarized below. 

On September 5, Hammer (2010a) reported a sequential summary of the five key human errors and 

the culminating mechanical failure of the BOP that combined to cause the DWH event. The graph was 

prepared on the basis of the following: more than 100 hours of testimony since May 11 before the joint 

investigative panel meeting chaired by USCG and this Agency that convened in Kenner, Louisiana two 

dozen Congressional hearings; and several internal company reports. Hammer (2010a) reported that there 

was no single fatal mistake causing the spill; rather, it was a scenario of events that led to the spill that 

proceeded sequentially: 

(1) there were fewer barriers to gas flow because of the well casing design, the so-called 

“long string” configuration; 

(2) there were fewer than customary casing centralizers to keep cement distribution even; 

(3) there was no bond log run to test cement integrity; 

(4) a key pressure test was misinterpreted; 

(5) the drilling mud barrier was removed too early; and 

(6) the BOP failed.

On January 6, 2011, the National Commission on the BP Deepwater Horizon Oil Spill and Offshore 

Drilling posted an advanced chapter (Chapter 4) on their website one week before release of their final 

report (Oil Spill Commission, 2011d). The immediate cause of the DWH event was a failure to contain 

hydrocarbon pressures in the well. The following three barriers could have contained well pressures: the 

cement at the bottom of the well; the mud in the wellbore and in the riser; and the blowout preventer. 

However, mistakes and failures to appreciate the risk involved compromised each of these barriers, 

steadily depriving the rig crew of safeguards until the blowout was inevitable and, at the very end, 

uncontrollable. The Commission concluded in Chapter 4 (Oil Spill Commission, 2011d, p. 115), “that the 

mistakes and oversights at Macondo cumulatively overwhelmed the safeguards meant to prevent just such 

a loss in well control from happening can be traced back to a single overarching failure—a failure of 

management. Better management by BP, Halliburton, and Transocean would almost certainly have 

prevented the blowout by improving the ability of individuals involved to identify the risks they faced, 

and to properly evaluate, communicate, and address them.” Among the key findings from Chapter 4 

include the following: 

 The Macondo blowout was the product of several individual missteps and oversights 

by BP, Halliburton, and Transocean, which Government regulators lacked the 

authority, the necessary resources, and the technical expertise to prevent; 
Deepwater Horizon Event Chronology D-13 

 The blowout was not the product of a series of aberrational decisions made by rogue 

industry or Government officials that could not have been anticipated or expected to 

occur again. Rather, the root causes are systemic and, absent significant reform in 

both industry practices and Government policies, might well recur; and 

 Each of the mistakes made on the rig and onshore by industry and Government 

increased the risk of a well blowout, the cumulative risk that resulted from these 

decisions and actions was both unreasonably large and avoidable, and the risk of a 

catastrophic blowout was ultimately realized on April 20; several of the mistakes 

were contributing causes of the blowout. 

Chapter 4 (Oil Spill Commission, 2011d, Table 4.10) showed a matrix of decisions that increased the 

risk at the Macondo well, while potentially saving time and money. Among the examples of engineering 

mistakes and management failures highlighted in the chapter are given below: 

(1) inadequate risk evaluation and management of late-stage, well design decisions; 

(2) a flawed design for the cement slurry used to seal the bottom of the well, which was 

developed without adequate engineering review or operator supervision; 

(3) a “negative pressure test,” conducted to evaluate the cement seal at the bottom of the 

well, identified problems but was incorrectly judged a success because of 

insufficiently rigorous test procedures and inadequate training of key personnel; 

(4) flawed procedures for securing the well that called for unnecessarily removing 

drilling mud from the wellbore. (If left in place, that drilling mud would have helped 

prevent hydrocarbons from entering the well and causing the blowout.); 

(5) apparent inattention to key initial signals of the impending blowout; and 

(6) an ineffective response to the blowout once it began, including but not limited to, a 

failure of the rig’s blowout preventer to close off the well. 

None of the Oil Spill Commission’s findings are in conflict with the September 5, 2010, account by 

Hammer (2010a). The Oil Spill Commission’s account, however, provides technical detail with 

explanations written for general public. It includes insight informed by the experts from whom the Oil 

Spill Commission received testimony and criticism in hindsight for the decisions taken by everyone 

involved in the process—from BP as operator, Transocean as the rig and crew contractor, and Halliburton 

as the cement contractor. 

On September 8, 2010, BP completed and released the company’s interpretation of the event scenario 

in the report titled “Deepwater Horizon Accident Investigation Report” (BP, 2010a).

Blowout Preventer Failure Scenario 

As explained in the Oil Spill Commission’s report, Chapter 4 (2011d, p. 93), the Deepwater 

Horizon’s BOP had multiple rams and preventers designed to seal the well. From top to bottom, 

Macondo’s 400-ton BOP was configured with the following: topmost were two large, donut-shaped, 

rubber annular preventers to seal off the annular space around the drill pipe; next were five sets of metal 

rams—the first was the blind shear ram that was designed to cut through drill pipe inside the BOP to seal 

off the well in an emergency situation and that could be activated manually by drillers on the rig, by an 

ROV, or by an automated emergency “deadman” system; next was a casing shear ram that was designed 

to cut through thicker tubulars such as casing in order to seal off the well; and at the bottom were three 

sets of pipe rams to close off the space around the drill pipe. 

The Oil Spill Commission (2011d, pp. 114-115) reported that, minutes before the first explosion on 

the Deepwater Horizon (April 20, 2010, ~9:49 p.m. CDT), the drilling rig crew activated one of the 

annular preventers; however, flow rates at this point in the loss of well-control event may have been too 

high for the annular preventer to prevent a blowout. After the first explosion, crewmembers on the bridge 

attempted to engage the rig’s emergency disconnect system, which should have closed the blind shear 
D-14 Central Planning Area Supplemental EIS 

ram, severed the drill pipe, sealed the well, and disconnected the rig from the BOP; however, none of that 

happened. Although the emergency disconnect system panel indicators lit up, the rig never disconnected. 

It is possible that the first explosion had already damaged the cables to the BOP, preventing the 

disconnect sequence from starting. 

The BOP’s automatic mode function (the “deadman” system) should have triggered the blind shear 

ram after the power, communication, and hydraulics connections between the rig and the BOP were cut; 

however, the deadman system failed too. Although Chapter 4 of the Oil Spill Commission’s report 

(2011d, p. 115) stated it was too early to tell, the deadman system failure may have been the result of poor 

maintenance. Post-incident testing of the two redundant “pods” controlling the deadman system revealed 

low battery charge in one pod and defective solenoid valves in the other. If those problems existed at the 

time of the blowout, they would have prevented the deadman system from working. 

Official Inquiries and Suspensions on OCS Oil and Gas Operations 

In the aftermath of the DWH event, four independent reviews, outside of BOEMRE, were carried out 

on OCS oil and gas operations. The BOEMRE undertook a joint investigation with USCG. 

 On April 30 2010, the President directed Secretary Salazar to conduct a thorough 

review of the DWH event and to report, within 30 days, on what, if any, additional 

precautions and technologies should be required to improve the safety of oil and gas 

exploration and production operations on the OCS. The Increased Safety Measures 

for Energy Development on the Outer Continental Shelf, the so-called “30-day 

Report” or “Safety Measures Report,” was delivered on May 27 (USDOI, 2010b) and 

included a recommendation of a program of immediate recertification of BOP’s. 

 On April 30 2010, Secretary Salazar asked for the creation of an OCS Safety 

Oversight Board to provide recommendations for improving and strengthening the 

Department’s overall management, regulation, and oversight of OCS operations, 

including undertaking further audits or reviews, and reviewing existing authorities 

and procedures. The Board completed its report on September 1 (USDOI, 2010c) 

and Director Bromwich made it publically available, with an implementation plan in 

a press release on September 8, 2010. 

 On May 11 2010, Secretary Salazar asked for an independent study by the National 

Academy of Engineering to analyze root causes of the DWH event and to provide 

recommendations (USDOI, 2010d). As part of his announcement Secretary Salazar 

undertook several initiatives: (1) ordered immediate inspections of all deepwater 

operations; (2) announced a joint investigation of the DWH event with USCG; (3) 

announced that no permits to drill would be processed until DOI completed the 

“30-day Report”; and (4) established the OCS Safety Oversight Board within DOI, 

consisting of the Assistant Secretary Lands and Mineral Management, Assistant 

Secretary Policy, Management, and Budget, and the Office of the Inspector General. 

The Academy released its final report on November 16, 2010 (National Academy of 

Engineers, 2010). 

 On May 11, 2010, this Agency and the USCG began a joint investigation into the 

causes of the DWH event that was convened at the Crown Plaza Hotel in Kenner, 

Louisiana. As of February 2011 this investigation was not completed. 

 On May 14 2010, Secretary Salazar requested that the Office of the Inspector General 

(OIG) expand on an OIG inquiry and report that found several ethics violations by 

employees at this Agency’s District Office in Lake Charles, Louisiana, to include an 

investigation into any deficiencies in this Agency’s policies and practices that may 

have contributed to the DWH event. The OIG released its final report on 

December 7, 2010 (USDOI, OIG, 2010).
Deepwater Horizon Event Chronology D-15 

 On May 21 2010, President Obama created the National Commission on the BP 

Deepwater Horizon Oil Spill and Offshore Drilling. The Commission began work on 

July 12 and their final report was posted on the Commission’s website January 11, 

2011 (Oil Spill Commission, 2011a). 

On May 6, 2010, this Agency announced a deepwater drilling moratorium to last through the month, 

but which was eventually extended 6 months to November 30. The moratorium affected exploration 

activity in water depths greater than 500 ft (152 m), which at that time affected 33 exploration or 

workover well projects. On June 2, Governor Jindal wrote to Secretary Salazar and the President 

claiming that a 6-month moratorium risked losing more than 20,000 existing and potential new Louisiana 

jobs over the next 12-18 months (Jindal, 2010). By September 14, The Times-Picayune reported that only 

160 deepwater rig workers applied for aid from $100-million fund BP set aside on June 16 as part of the 

$20-billion escrow fund to cover economic damages related to the DWH event (Hammer, 2010b). A 

September 16 study by an interagency group lead by DOC (USDOC, 2010, p. 15) concluded that roughly 

2,000 of the 9,700 workers aboard the more than 3 dozen offshore rigs affected by the moratorium had 

lost their jobs or moved away from the Gulf since the moratorium was imposed in late May and that 

another 8,000-12,000 workers (USDOC, 2010, p. 7) in related industries also lost work because of the 

moratorium. Figure 3-7 reports the drilling activity levels in the Gulf of Mexico in the months after the 

DWH event 

On May 11, 2010, a joint investigation by USCG and this Agency began to identify the factors 

leading to the DWH event began meeting in Kenner, Louisiana. David Dykes of this Agency and Capt. 

Hung Nguyen of USCG were co-chairs of the investigation. The USCG and this Agency shared 

jurisdiction for the investigation because the casualties aboard the Deepwater Horizon took place on the 

OCS. Upon completion, the investigation will issue a single report to the DOI Secretary and the Coast 

Guard Commandant. A projected completion date for the report is not available. 

On May 19, 2010, DOI Secretary Salazar announced (USDOI, 2010e) that this Agency would be 

renamed and reorganized as the Bureau of Ocean Energy Management, Regulation and Enforcement. 

On May 28, 2010, the Secretary directed this Agency to exercise its authority under the OCSLA to 

suspend certain drilling activities in water depths of 500 ft (152 m) and deeper for a period of up to 

6 months. The May 28th suspension was intended to provide sufficient time to (1) ensure that drilling 

operations similar to conditions that apply to the DWH event operate in a safe manner when drilling 

resumes, (2) account for the expected timeline for killing the Macondo well so that the extensive spill 

response resources directed toward the spill would start to become available for other spill events, and (3) 

provide adequate time to obtain input from ongoing investigations of the accident and to develop and 

promulgate regulations that address issues described in the Safety Measures Report. 

On June 22, 2010, the United States Federal District Court in the Eastern District of Louisiana 

enjoined enforcement of the May 28th suspension. On July 12, 2010, the Secretary issued a decision 

memorandum rescinding the May 28th suspension and imposing a second suspension of certain drilling 

operations in deep water; this suspension was effective until November 30, 2010. In particular, the 

July 12th suspension applied, with certain exceptions, to the drilling of wells using a subsea BOP or a 

surface BOP on a floating facility. Three primary issues supported this temporary pause in drilling 

operations. The suspension (1) allowed time for BOEMRE to implement appropriate workplace and 

drilling safety measures; (2) was intended to provide BOEMRE, the industry, and others time to develop 

strategies and methods of containment of wild wells in deep water; and (3) was necessary to ensure that 

appropriate and sufficient response resources would be available in the event of another major oil spill. 

The BOEMRE reduced the duration of the July 12, 2010, suspension insofar as it applies to 

deepwater development drilling operations and wrote an environmental assessment with a Finding of No 

Significant Impact (USDOI, BOEMRE, 2010a). The Secretary of the Interior thereafter directed that the 

July 12 suspension on the drilling of deepwater development wells be lifted as of October 12, 2010. 

Deepwater drilling is defined as drilling operations using a subsea BOP or a surface BOP on a floating 

facility. After October 12, 2010, BOEMRE began to review and approve pending and future applications 

for permits to drill deepwater development wells using a subsea BOP or a surface BOP on a floating 

facility. 

The BOEMRE has addressed, through multiple strategies, the three issues posed as necessary 

prerequisites to terminating the July 12, 2010, activity suspension early. The BOEMRE has collected a 
D-16 Central Planning Area Supplemental EIS 

large amount of information through public hearings and other meetings held specifically on the DWH 

event and through public comments on rulemaking efforts. The information collection, review, and 

analysis efforts resulted in new regulations and planned Notices to Lessees and Operators (NTL’s) and 

BOEMRE procedures that address drilling safety, oil-spill response, and enhanced inspection procedures. 

These regulations, NTL’s, and procedures were not in effect at the time of the DWH event, but they will 

apply to all future applicable drilling activities. The regulations, NTL’s, and procedures include the 

following: 

 NTL 2010-N05, “Increased Safety Measures for Energy Development,” effective 

June 8, 2010 (“Safety NTL”). 

 NTL 2010-N06, “Information Requirements for Exploration Plans, Development and 

Production Plans, and Development Operations Coordination Documents on the 

OCS,” effective June 18, 2010 (“Plans NTL”). 

 NTL 2010-N10, “Statement of Compliance with Applicable Regulations and 

Evaluation of Information Demonstrating Adequate Spill Response and Well 

Containment Resources,” effective November 8, 2010 (“Certification NTL”). 

 The Drilling Safety Rule, Interim Final Rule to Enhance Safety Measures for Energy 

Development on the Outer Continental Shelf (“Drilling Safety Rule”). This rule 

strengthens requirements for safety equipment, well control systems, and blowout 

prevention practices on offshore oil and gas operations. 

 The Workplace Safety Rule on Safety and Environmental Management Systems 

(“SEMS Rule”). This rule requires operators to develop and implement a 

comprehensive SEMS for identifying, addressing, and managing operational safety 

hazards and impacts; promoting both human safety and environmental protection; 

and improving workplace safety by reducing the risk of human error. 

 Enhanced Inspection Procedures. The BOEMRE is developing plans and schedules 

for conducting safety inspections of all deepwater drilling facilities. These plans and 

schedules will be implemented upon the recommencement of deepwater drilling 

operations. 

On February 28 2011, BOEMRE approved the first deepwater drilling permit since the Deepwater 

Horizon explosion and resulting oil spill. The BOEMRE has worked diligently to help industry adapt and 

conform to new and rigorous safety practices. The permittee provided adequate information to 

demonstrate that the proposed action met new safety regulations and information requirements in 

NTL 2010-N06, NTL 2010-N10, and the Interim Final Safety Rule. This permit added to the increasing 

number of permits that have been approved since new safety regulations have been put in place, including 

37 permits for new shallow-water wells. 

Spill Inquiries and Immediate Aftermath 

On June 16, 2010, as part of a speech to the Nation, President Obama announced that Secretary of the 

Navy Ray Mabus, a former Mississippi governor, was to prepare a long-term recovery plan for the Gulf 

Coast in the aftermath of the DWH event. After extensive travel and many meetings, Mabus’s report, 

America’s Gulf Coast: A Long-Term Recovery Plan after the Deepwater Horizon Oil Spill, 

(RestoreTheGulf.gov, 2010c) was released on September 28, 2010. The plan recommended that 

Congress dedicate a significant amount of any civil penalties obtained from parties responsible for the 

DWH event into a Gulf Coast Recovery Fund to go toward addressing long-term recovery and restoration 

efforts in the Gulf. To manage the funds and to coordinate recovery projects, the Mabus report 

recommends that Congress authorize a Gulf Coast Recovery Council that includes representatives from 

the states and federally recognized Gulf tribes. The Recovery Council would work to ensure that local 

governments and citizen stakeholders also play a critical role. 
Deepwater Horizon Event Chronology D-17 

The September 28 press release accompanying the plan forecasted that the President would sign, and 

on October 5 did sign, an Executive Order (The White House, 2010) to establish the Gulf Coast 

Ecosystem Restoration Task Force (Chapter 3.3.4). A bridge to the Gulf Coast Recovery Council, this 

intergovernmental advisory body consists of 12 executive office agencies and groups, with provisions for 

State and tribal participation. The Gulf Coast Ecosystem Restoration Task Force would coordinate 

restoration programs and projects in the Gulf region, focus on efforts to create more resilient and healthy 

Gulf Coast ecosystems, and encourage support for economic recovery. The President named USEPA 

Administrator Lisa Jackson to serve as presiding officer of the Gulf Coast Ecosystem Restoration Task 

Force. 

Effective as of October 12, 2010, Secretary of the Interior Secretary Ken Salazar directed that the 

July 12 suspension of operations for deepwater oil and gas drilling could be lifted, provided that operators 

certify compliance with all existing rules and requirements, including those that recently went into effect 

(Chapter 1.3.1), and demonstrate the availability of adequate blowout containment resources. In the 

July 12 Decision Memorandum imposing the suspension for deepwater operators that deploy a subsurface 

BOP or a floating MODU with a BOP on the rig floor, the Secretary requested BOEMRE to report its 

findings and recommendations as to whether or not modifications to the scope or duration of the 

deepwater drilling suspension would be appropriate. 

Director Bromwich prepared his October 1 report (Bromwich, 2010) and recommendations based on 

extensive public outreach and information gathering, including the eight public forums he held around the 

country to assess safety, spill response, and blowout containment issues. Secretary Salazar reached his 

decision after reviewing BOEMRE’s Director Bromwich’s report (Bromwich, 2010) and after considering 

other information on the progress of offshore oil and gas safety reforms, the availability of spill-response 

resources, and improved blowout containment capabilities. The BOEMRE announced its intention to 

conduct inspections of each deepwater drilling operation for compliance with regulations, including, but 

not limited to, the testing of BOP’s before an individual deepwater drilling operation is resumed. 

On November 16, 2010, the National Academy of Engineers released a preliminary report on the 

DWH event (National Academy of Engineers, 2010) and forecast a final report in June 2011. Some of the 

panel’s findings are as follows: (1) it was a critical mistake not to shut down the well despite warnings 

that the cement job had failed, suggesting an insufficient consideration of risk; (2) too many procedures 

were being run simultaneously; (3) there are questions about the adequacy of operating knowledge on the 

part of key personnel; and (4) many decisions were less expensive and time consuming than other 

options. Other issues highlighted in the report were concern among DWH crew members about who was 

in charge, important members of the rig crew suffered from insufficient training, and this Agency had 

failed to put in place the oversight systems that could have helped prevent such an event and lacked 

important in-house expertise and technical capabilities. 

On December 7, 2010, the DOI’s Office of the Inspector General released the inquiry requested by 

Secretary Salazar on May 25 (USDOI, OIG, 2010). The OIG’s charter was to investigate performance of 

BOEMRE’s regulatory functions, policies, or practices to see if deficiencies needed to be addressed to 

ensure that OCS operations are conducted in a safe manner that is protective of human life, health, and the 

environment. Because the OIG investigation and the OCS Safety Oversight Board were asked to perform 

somewhat similar investigations, the OIG and Safety Board performed this investigation as a team in the 

early stages, with the Safety Board issuing its report with the most pressing finding on September 1, 2010 

(USDOI, 2010c). The OIG conducted site visits and interviewed BOEMRE staff and management about 

inspections, permitting, environmental and cultural resource protection, and safety programs. The OIG 

also conducted two online surveys targeting the BOEMRE staff involved in inspections and 

environmental and cultural resources, respectively. The OIG reported both their of the surveys and raw 

survey outputs (USDOI, OIG, 2010) and the OIG’s independent view and analysis of many of the same 

issues advanced by the Board. The OIG’s report contains 64 recommendations, 55 of which were also 

contained in the OCS Safety Oversight Board’s September 1 report (USDOI, 2010c). The OIG did not 

raise substantive new issues; rather, it expounded upon those issues identified in summary fashion in the 

Safety Oversight Board report, and the OIG recognized that many of the recommendations contained in 

its report were already being addressed by BOEMRE. 

The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling called for by 

President Obama on May 21, 2010, was chaired by Fran Ulmer, Chancellor of the University of Alaska

Anchorage. He and six members brought a broad spectrum of expertise to the work of the Commission 
D-18 Central Planning Area Supplemental EIS 

that included expertise in engineering, oil industry, environmental science, and law. Subject areas 

considered included spill response, restoration, regulatory oversight, corporate culture, safety, and the 

Arctic. Since the first meeting in July, the Oil Spill Commission has held multiple site visits in all the 

Gulf Coast States. In public meetings in New Orleans, Louisiana, and Washington, DC, comments were 

collected from community members, small business owners, and State and local officials, and testimony 

was taken from industry and government representatives who also provided extensive background 

information and papers describing the factors that contributed to the DWH event. 

On January 11, 2011, the Oil Spill Commission released their full report (Oil Spill Commission, 

2011d). It presents the Commission’s complete examination of the causes of the DWH event, the 

Macondo spill response, and consequences of the spill based on the witness record and documentation 

reviewed by the Commission. In a separate summary for decisionmakers, it includes recommendations 

for Congress, the Executive Branch, DOI, and industry (Oil Spill Commission, 2011e). 

Recommendations are grouped in nine distinct categories: 

(1) Improving the Safety of Offshore Operations: Government’s Role; 

(2) Improving the Safety of Offshore Operations: Industry’s Role; 

(3) Safeguarding the Environment; 

(4) Strengthening Oil-Spill Response, Planning, and Capacity; 

(5) Advancing Well-Containment Capabilities; 

(6) Overcoming the Impacts of the Deepwater Horizon Spill and Restoring the Gulf; 

(7) Ensuring Financial Responsibility; 

(8) Promoting Congressional Engagement to Ensure Responsible Offshore Drilling; and 

(9) Moving to Frontier Regions. 

Six of the nine recommendations pertain to issues of governance, national policy, the OCS Program, 

and regulatory philosophy that are beyond the scope of this Supplemental EIS. Three recommendations 

that are applicable to OCS leasing and operations, oil-spill response, and well control are addressed here. 

Recommendations under Category 3 (Oil Spill Commission, 2011e, p. 18), “Safeguarding the 

Environment,” are within the scope of this Supplemental EIS or the National Environmental Policy Act 

(NEPA) process as implemented by BOEMRE. The Commission reported that the adequacy of the 

existing regulatory regime to assure the environmental safety of offshore drilling (as distinct from worker 

or occupational safety) had come under a great deal of scrutiny since the Deepwater Horizon event. The 

Commission focused on two issues: (1) the application of NEPA requirements to the offshore leasing 

process; and (2) the need for better science and greater interagency consultation to improve 

decisionmaking concerning the management of offshore resources. 

The Oil Spill Commission recommended a need to revise and strengthen NEPA policies and practices 

in the offshore drilling context and for greater interagency consultation (Oil Spill Commission, 2011e, 

pp. 18-22). The Commission offered observations on BOEMRE’s implementation of NEPA, which 

included the following: 

(1) the manner in which this Agency applied the concept of “tiering” was not always 

consistent with its original purpose and that this Agency created a system where 

deeper environmental analysis at more geographically targeted and advanced 

planning stages did not always take place; 

(2) the use of NEPA’s “categorical exclusions” was inconsistent among this Agency’s 

regional offices and that how categorical exclusions were applied to major drilling 

and development projects were clearly shown, post-Macondo spill, to not be the type 

of activity NEPA envisioned for these exclusions (“activities involving limited 

environmental risk”); 
Deepwater Horizon Event Chronology D-19 

(3) the lack of a NEPA requirements and implementation handbook for use within this 

Agency was regarded as a critical oversight; and 

(4) smaller OCS areas should be offered for leasing, especially in frontier areas, which 

could receive more detailed attention during a NEPA review. 

Following on these observations, the Oil Spill Commission’s (2011e, pp. 18-22) more particular 

recommendations included the following: 

(1) the Council on Environmental Quality and DOI should revise and strengthen NEPA 

policies, practices, and procedures to improve the level of environmental analysis, 

transparency, and consistency at all stages of the OCS planning, leasing, exploration, 

and development process; and 

(2) the DOI should reduce the risk to the environment from OCS oil and gas activities by 

strengthening science and interagency consultations in the OCS oil and gas 

decisionmaking process, and improvements to interagency cooperation should be 

supported by industry fees. 

Recommendations under Category 4 (Oil Spill Commission, 2011e, pp. 26-33), “Strengthening Oil 

Spill Response, Planning, and Capacity,” included those that responded to a need for a new approach to 

handling spills of national significance, a need to strengthen State and local involvement, a justification 

for increased research and development to improve spill response, a need for new regulations to govern 

the use of dispersants, and a need to reevaluate the use of offshore barrier berms in spill response. More 

particular recommendations included the following: 

(1) the USEPA and USCG should establish distinct plans and procedures for responding 

to a “Spill of National Significance;” 

(2) the USEPA and USCG should bolster State and local involvement in oil-spill 

contingency planning and training and should create a mechanism for local 

involvement in spill planning and response similar to the Regional Citizens’ 

Advisory Councils mandated by the Oil Pollution Act of 1990; 

(3) Congress should provide mandatory funding for oil-spill-response research and 

development and provide incentives for private-sector research and development; 

(4) the USEPA should update and periodically review its dispersant testing protocols for 

product listing or preapproval, and modify the pre-approval process to include 

temporal duration, spatial reach, and volume of the spill; 

(5) the DOI should require offshore operators to provide detailed plans for source control 

as part of their oil-spill-response plans and applications for permits to drill; and 

(6) the USCG should issue guidance to establish that offshore barrier berms and similar 

dredged barriers generally will not be authorized as an oil-spill-response measure in 

the National Contingency Plan or in any Area Contingency Plan. 

Recommendations under Category 5 (Oil Spill Commission, 2011e, pp. 31-36), “Advancing WellContainment Capabilities,” included those that responded to a need for government to develop greater 

source-control expertise, a need to strengthen industry’s spill preparedness, a need for improved 

capability to develop accurate flow rate estimates, and a need for a more robust well design and approval 

process. More particular recommendations included the following: 

(1) the National Response Team (formed after a “spill of national significance”) should 

develop and maintain expertise within the Federal Government to oversee sourcecontrol efforts (source control = understanding and controlling a persistent spill); 
D-20 Central Planning Area Supplemental EIS 

(2) the DOI should require offshore operators to provide detailed plans for source control 

as part of their oil-spill-response plans and applications for permits to drill; 

(3) the National Response Team should develop and maintain expertise within the 

Federal Government to obtain accurate estimates of flow rate or spill volume early in 

a source-control effort; and 

(4) the DOI should require offshore operators seeking its approval of proposed well 

design to demonstrate that (a) well components, including blowout preventer stacks, 

are equipped with sensors or other tools to obtain accurate diagnostic information 

(e.g., regarding pressures and the position of blowout preventer rams); and (b) wells 

are designed to mitigate risks to well integrity during post-blowout containment 

efforts. 

The BOEMRE continues to address the recommendations from the Oil Spill Commission’s report 

regarding safety, oil-spill response, well-containment capabilities, etc., as well as the recommendations 

from other agencies and investigations. As previously stated, BOEMRE created 11 Implementation

Teams tasked with analyzing various aspects of BOEMRE’s regulatory structure and helping to 

implement the reform agenda (USDOI, BOEMRE, 2010b). Teams are considering the various 

recommendations for improvement received from multiple investigations and analyses, including the 

Safety Oversight Board, National Commission on the BP Deepwater Horizon Oil Spill, and National 

Academy of Engineering. Permit applications for drilling projects must meet new standards for welldesign, casing, and cementing, and be independently certified by a professional engineer. Standards are 

being strengthened in the drilling and production stages for equipment, safety practices, environmental 

safeguards, and oversight. There will be performance-based standards for offshore drilling and 

production operations, including for equipment, safety practices, environmental safeguards, and 

management oversight of operations and contractors. New comprehensive environmental analyses of the 

Gulf of Mexico and the Arctic will be conducted to help inform future leasing and development decisions 

(USDOI, BOEMRE, 2010c). In addition, new NTL’s and regulations are also under development and are 

in the process of being implemented. The most up-to-date NTL’s and new regulations are cited 

throughout Chapter 3, e.g. Chapter 3.1.1.1.1 (“Seismic Surveying Operations”), Chapter 3.1.1.1.2

(“Exploration and Delineation Drilling”), Chapter 3.1.1.2.1 (“Development and Production Drilling”), 

Chapter 3.1.1.6.3 (“New and Unusual Technology”). 

With respect to the Commission’s observations on BOEMRE’s implementation of NEPA, these 

recommendations have been taken into consideration in the preparation of this Supplemental EIS and will 

continue to be considered and acknowledged as this Agency publishes future pre and post lease NEPA 

documents. This Supplemental EIS is a prelease NEPA document that supplements the Multisale EIS and 

the 2009-2012 Supplemental EIS, which tier from the 5-Year Program EIS. Tiering in this manner is still 

valid for prelease documents. The NEPA concept of tiering identified in the Oil Spill Commission Report 

recommendation targets postlease NEPA activity, specifically categorical exclusions, which are not used 

in the prelease NEPA process and are not currently being used as part of the approval process for 

deepwater drilling projects. The Commission’s recommendations for postlease activity are being taken 

into consideration and will be addressed throughout the postlease NEPA process. 

Natural Resource Damage Assessment 

The mission of the Department of the Interior’s NRDA is to restore natural resources injured as a 

result of oil spills or hazardous substance releases into the environment. Congress authorizes States, 

Tribes, and Federal resource management agencies to act on behalf of the public as a “trustee” for the 

purpose of bringing a claim to recover damages necessary to restore or replace injured public resources 

managed or controlled by the respective States, Tribes, or Federal agency. A damage assessment 

addresses the public’s use of injured resources and their loss, and is the first step toward determining the 

restoration needs for injured natural resources for the American public. They have a purpose-driven 

outcome and are not done just for the sake of science. 

The Comprehensive Environmental Response, Compensation and Liability Act defines “natural 

resource damage assessment” as the process of collecting, compiling, and analyzing information, 
Deepwater Horizon Event Chronology D-21 

statistics, or data through prescribed methodologies to determine damages for injuries to natural 

resources. “Injury” refers to the actual adverse impact or loss of the natural resource resulting either 

directly or indirectly from exposure to a release or threat of release of oil or a discharge or release of a 

hazardous substance. An injury assessment investigates and explains the extent of adverse impact to the 

natural resource. “Damage” is the amount of money sought by the natural resource trustee as appropriate 

to compensate for the injury through natural resource restoration or replacement projects. 

For the DWH event, NOAA Fisheries is coordinating the NRDA and is leading data collection efforts 

with partners in five states (i.e., Louisiana, Mississippi, Alabama, Florida, and Texas) and DOI. BP is 

also participating in many of the data collection efforts. Information is now being collected on potential 

impacts to fish, shellfish, marine mammals, turtles, birds, and other sensitive resources as well as their 

habitats, including wetlands, beaches, mudflats, bottom sediments, corals, and the water column. The 

NRDA will also assess any lost human uses of these resources, such as fishing, hunting, and beach 

closures. Among the many teams now in the field conducting surveys and collecting samples are those 

programs listed below: 

 surveying over 1,800 mi (2,897 km) of shoreline and collecting over 19,500 water, 

sediment, and animal tissue samples; 

 characterizing environmental conditions during more than 70 offshore research 

cruises, oil on and below the water surface, and the exposure to biological 

communities; 

 documenting the presence of oil and collecting samples for fingerprinting to confirm 

its origin. (Teams have been conducting initial injury assessment studies at more 

than 50 shoreline sites a day to collect data on the degree and extent of habitat 

oiling.); 

 monitoring populations of marine mammals and turtles in flyovers, documenting 

their presence in the impacted areas, and locating stranded animals; and 

 evaluating loss of human use, such as recreational beach days, charter boat or diving 

boat trips, resulting from the spill. 

Natural resource restoration is paid for by funds recovered from settlements with responsible parties 

and are not at the expense of the taxpayer. In addition, settlements often include the recovery of the costs 

incurred in assessing the damages. These funds are then used to fund further damage assessments. There 

is no prescribed amount of time set by the Comprehensive Environmental Response, Compensation and 

Liability Act for the damage assessment to be prepared or for the subsequent restoration process to take 

place. Each assessment is unique and the amount of time can vary significantly. Damage assessments are 

often quite complex and can take years to complete. In the case of the DWH event, the acute impacts on 

resources are liable to be the focus for the NRDA, at least for the initial issue. 

Acute Impacts 

Acute impacts are primarily those that can be readily identified and measured in the short term. On 

May 2, 2010, NOAA Fisheries Service announced the first closure of 17,648 km2

 (6,817 mi2) of coastal 

and offshore fisheries in State and OCS waters (USDOC, NOAA, 2010). The areas closed to fishing 

were to rise steadily to a maximum of 225,290 km2

 (86,985 mi2) on June 21, 2010. Thereafter, closed 

areas began to reopen until 82,659 km2

 (31,915 mi2) remained closed on September 21 (USDOC, NOAA, 

2010), or approximately 13 percent of Gulf waters. By October 15, 2010, 42,686 km2 (16,481 mi2

) 

remained closed, or approximately 7 percent of Gulf waters (USDOC, NOAA, 2010), and by 

November 15, 2010, 2,697 km2 (1,041 mi2

) remained closed, or 0.4 percent of Gulf waters (USDOC, 

NOAA, 2010). Throughout the DWH event, NOAA produced spill trajectory graphics to inform the 

public about the extent and surface expression of the spill and how it changed over time. The NOAA 

posted their complete archive of maps on September 16, 2010, shortly before the Macondo well was 

killed (USDOC, NOAA, NOS, 2010). 
D-22 Central Planning Area Supplemental EIS 

On May 2, 2010, the first oiled bird began rehabilitation (Bearden, 2010), and by May 21 early 

stranding reports identified 186 dead turtles, 43 birds, and 18 marine mammals as being possible spill 

casualties (Winter, 2010). On May 28, FWS began to keep track of dead and oiled animals that were 

collected or recovered for rehabilitation at designated stations along the Gulf Coast. The FWS prepared 

and posted daily Consolidated Fish and Wildlife Collection Reports on the total number and condition of 

marine mammals, birds, and sea turtles collected in each Gulf State’s coastal zone (Deepwater Horizon

Response, 2010b). The consolidated report for September 17 (USDOI, FWS, 2010a) reported cumulative 

totals (Table D-4). 

On May 6, 2010, a Shoreline Cleanup and Assessment Team confirmed the first oil landfall on the 

beach at Chandeleur Islands. The first tarballs washed ashore on Dauphin Island, Alabama, on May 12, 

and oil appeared on Pensacola Beach, Florida, and the Gulf Islands National Seashore, Florida and 

Mississippi, on June 23. On June 4, Dunlap (2010) reported what are probably the best known images of 

dead and dying birds heavily oiled by the spill, i.e., pelicans and other seabirds from East Grand Terre 

Island, Louisiana. 

On May 26, 2010, the Associated Free Press (2010) reported that UIC recalled 125 boats working on 

the spill east of New Orleans after workers on three boats reported experiencing nausea, dizziness, 

headaches, and chest pains; this was the first of the intermittent reports of human health effects of 

unknown origin that may or may not have been spill-related (working under high heat conditions and 

dehydration may have been aggravating factors). By June 9, Landau (2010) reported 71 cases of spillrelated illnesses and complaints; 50 by workers on offshore rigs or spill cleanup crews and 21 by non-spill 

workers. 

On June 1, 2010, the Federal Government authorized 17,500 National Guard troops from the Gulf 

Coast States to be paid for by BP: Louisiana (6,000); Mississippi (6,000); Alabama (3,000); and Florida 

(2,500). The eligible states eventually authorized only small fractions of the total manpower made 

available. The UIC’s spill-response operations began to mobilize ever-increasing numbers of personnel, 

vessels, aircraft, and shoreline containment boom that serves as level-of-effort metric for responding to 

the Macondo spill (Table D-3). After the well was capped on July 15, 2010, the number of people 

reported by UIC for spill response peaked at 46,500 on July 10; after that, a gradual ramp-down began in 

people and equipment deployed. 

As of May 25, 2010, UIC reported 85 mi (136 km) of shoreline that had been oiled. By July 27, 

11 days after the well was capped, a joint press conference with National Incident Commander Thad 

Allen and NOAA Administrator Jane Lubchenco reported that approximately 650 mi (1,030 km) of Gulf 

Coast shoreline had been oiled; 362 mi (583 km) of that in Louisiana (Joint Information Center, 2010). 

On September 13, Kaufman and Dewan (2010) reported that, as of August 31, NOAA had surveyed 

1,796 mi (2,890 km) of Louisiana coast and found 35 mi (56 km) of shoreline to be heavily oiled, 71 mi 

(114 km) to be moderately oiled, and 115 mi (185 km) to be lightly oiled. 

There is disagreement about the amount of Louisiana wetlands oiled by the spill. Robert Barham, 

Secretary of Louisiana’s Department of Wildlife and Fisheries, was quoted in The Washington Post on 

July 26 that 200 mi2

 (128,000 ac; 51,800 ha) of Louisiana’s shoreline had been oiled, most of which was 

wetlands (Fahrenthold, 2010). On July 29, however, Grunwald (2010) reported that UIC’s Shoreline 

Cleanup and Assessment Team found that only about 350 ac (142 ha) of marshes had been oiled to 

various degrees in Louisiana. On August 2, Jervis (2010) reported that about 108 mi2 (27,972 ha) of 

Louisiana marshland were “hit” by oil, with no qualification as to degree of oiling. 

On July 31, 2010, two weeks after the flow of oil had stopped from the Macondo well, NOAA’s 

Office of Response of Restoration reported no recoverable surface oil was observable (USDOC, NOAA, 

NOS, 2010). By July 21, the UIC burn teams found no surface oil to skim and burn. The spill response 

had involved a total of 411 burns. 

The Unified Area Command’s Daily Report for August 30 (Deepwater Horizon Response, 2010c) 

reported that approximately 57,000 cumulative tons of solid and oily solid waste had been disposed of in 

authorized landfills and that 450,000 cumulative barrels of oil and water mixtures or emulsions (e.g., from 

skimming or oil recovery operations) had been collected during response activities. 

Concern remains, however, about the longer-term impact of at-large underwater oil, its fate, and 

possible ecological damage that could result from it. Several research teams have been in the vanguard to 

take measurements, among them are Texas A&M, University of Georgia, Woods Hole Oceanographic 

Institute, and the University of South Florida. On May 16, Gillis (2010) reported that a researcher from 
Deepwater Horizon Event Chronology D-23 

the University of Georgia on the NOAA R/V Pelican detected the first underwater plumes of fine droplets 

of suspended oil at various depth levels. On May 27, scientists from the University of South Florida and 

the Florida Fish and Wildlife Research Institute reported an area of dissolved hydrocarbons in the 

subsurface near the Macondo spill (Chachere, 2010a). On June 22, Steenhyusen (2010) reported that 

John Kessler at Texas A&M had found elevated concentrations of methane dissolved in seawater. On 

September 10, Harris (2010) reported that Samantha Joye of the University of Georgia on the 

R/V Oceanus had discovered accumulations of oil and oily residues up to 5 cm (2 in) thick in cores from 

the sea bottom in water depths of 300-2,000 ft (91-609 m). A similar find was reported by David 

Hollander on August 17 on the University of South Florida’s website (Chachere, 2010b). Dr. Joye 

hypothesized that the mucosa secreted from marine bacteria, perhaps in combination with dispersant 

chemicals, attached to floating oil droplets, entrained the oil, and caused it to sink (Joye, 2010). On 

September 16, Valentine et al. (2010) reported that microbes were consuming propane and ethane, 

components of dissolved gas that are more easily consumed by low-diversity bacterial blooms, and not 

consuming much methane. On September 17, 2010, John Kessler and Texas A&M’s team on the NOAA 

R/V Pisces completed a 10-day mission to track the fate of oil and methane that may remain in the deep 

water of the Gulf, and by January 6, 2011, they reported that levels of methane in the Gulf of Mexico had 

returned to near-normal levels (Kessler et al., 2011). 

Further discussion of impacts on each resource is reported in the impacts analysis for each affected 

resource in Chapter 4. 

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the-press-office/2010/10/05/executive-order-gulf-coast-ecosystem-restoration-task-force. 

The White House Blog. 2010. Secretary of Defense approves request for two C-130 aircrafts to respond. 

April 30, 2010. Internet website: http://www.whitehouse.gov/blog/2010/05/05/ongoingadministration-wide-response-deepwater-bp-oil-spill. Accessed January 13, 2011. 

Urbina, I. 2010. BP used riskier method to seal well before blast. The New York Times. Internet 

website: http://www.nytimes.com/2010/05/27/us/27rig.html. Posted May 26, 2010. Accessed 

February 14, 2011 

U.S. Dept. of Commerce. 2010. Estimating the economic effect of the deepwater drilling moratorium on 

the Gulf Coast economy: Inter-agency report, September 16, 2010. Report presented at the 

Department of Commerce Testimony—111th Congress by Rebecca Blank, Under Secretary for 

Economic Affairs, U.S. Dept. of Commerce. 25pp. Internet website: http://www.commerce.gov/

sites/default/files/documents/2010/november/blank091610_report.pdf. Accessed December 12, 2010. 
D-28 Central Planning Area Supplemental EIS 

U.S. Dept. of Commerce. National Oceanic and Atmospheric Administration. 2010. Deepwater 

Horizon/BP oil spill: Size and percent coverage of fishing area closures due to BP oil spill. Internet 

website: http://sero.nmfs.noaa.gov/ClosureSizeandPercentCoverage.htm. Updated November 15, 

2010. Accessed January 13, 2011. 

U.S. Dept. of Commerce. National Oceanographic and Atmospheric Administration. National Ocean 

Service. 2010. Deepwater Horizon trajectory map archive. Office of Response and Restoration. 

Internet website: http://response.restoration.noaa.gov/topic_subtopic_entry.php?RECORD_KEY%28

entry_subtopic_topic%29=entry_id,subtopic_id,topic_id&entry_id(entry_subtopic_topic)=830&

subtopic_id(entry_subtopic_topic)=2&topic_id(entry_subtopic_topic)=1. Posted September 16, 

2010. Accessed February 14, 2011. 

U.S. Dept. of Energy. 2010. Deepwater Horizon response. Internet website: http://www.energy.gov/

open/oilspilldata.htm. Posted July 28, 2010. Accessed September 15, 2010. 

U.S. Dept. of Homeland Security. Coast Guard. 2010. Deepwater Horizon response daily report. 

August 3, 2010. Coast Guard Unified Area Command. 

U.S. Dept. of Homeland Security and U.S. Environmental Protection Agency. 2010. Letter to Dr. Tony 

Hayward from Janet Napolitano and Lisa P. Jackson. May 20, 2010 Internet website: 

http://www.epa.gov/bpspill/dispersants/bp-hayward-dhs-epa.pdf. Accessed January 13, 2011. 

U.S. Dept. of the Interior. 2010a. Flow rate group provides preliminary best estimate of oil flowing from 

BP oil well. Press Release. Internet website: http://www.doi.gov/news/pressreleases/Flow-RateGroup-Provides-Preliminary-Best-Estimate-Of-Oil-Flowing-from-BP-Oil-Well.cfm. Updated June 7, 

2010. Accessed February 14, 2011. 

U.S. Dept. of the Interior. 2010b. Increased safety measures for energy development on the outer 

continental shelf, May 27, 2010. U.S. Dept. of the Interior, Washington, DC. 44 pp. Internet 

website: http://www.doi.gov/deepwaterhorizon/loader.cfm?csModule=security/

getfile&PageID=33598. 

U.S. Dept. of the Interior. 2010c. Outer Continental Shelf Safety Oversight Board, report to Secretary of 

the Interior Ken Salazar. U.S. Dept. of the Interior, Washington, DC. September 1, 2010. 37 pp. 

Internet website: http://www.doi.gov/news/pressreleases/loader.cfm?csModule=security/

getfile&PageID=43677.

U.S. Dept. of the Interior. 2010d. Salazar launches safety and environmental protection reforms to 

toughen oversight of offshore oil and gas operations. Press Release. May 11, 2010. U.S. Dept. of 

the Interior. Internet website: http://www.doi.gov/news/pressreleases/Salazar-Launches-Safety-andEnvironmental-Protection-Reforms-to-Toughen-Oversight-of-Offshore-Oil-and-Gas-Operations.cfm. 

U.S. Dept. of the Interior. 2010e. Salazar divides MMS’s three conflicting missions. Press Release. 

May 19, 2010. Internet website: http://www.doi.gov/news/pressreleases/Salazar-Divides-MMSsThree-Conflicting-Missions.cfm. Accessed January 13, 2011. 

U.S. Dept. of the Interior. Bureau of Ocean Energy Management, Regulation and Enforcement. 2010a. 

Modifications to suspension of deepwater drilling operations: Environmental assessment and finding 

of no significant impact (October 12, 2010). U.S. Dept. of the Interior, Bureau of Ocean Energy 

Management, Regulation and Enforcement, Herndon, VA. 43 pp. Internet website: 

http://www.boemre.gov/eppd/PDF/EAModificationsSuspension10122010.pdf. 

U.S. Dept. of the Interior. Bureau of Ocean Energy Management, Regulation and Enforcement. 2010b. 

BOEMRE Director testifies before the National Commission on the BP Deepwater Horizon Oil Spill. 

Press Release. November 9, 2010. Internet website: http://www.boemre.gov/ooc/press/

2010/press1109.htm. Accessed March 25, 2011. 

U.S. Dept. of the Interior. Bureau of Ocean Energy Management, Regulation and Enforcement. 2010c. 

Reorganization and regulatory reform—supplemental environmental impact statement (SEIS). 

Internet website: http://www.boemre.gov/ReorganizationRegulatoryReform_SEIS.htm. Accessed 

March 25, 2011. 
Deepwater Horizon Event Chronology D-29 

U.S. Dept. of the Interior. Fish and Wildlife Service. 2010a. FWS Deepwater Horizon oil spill response. 

Weekly bird impact data and consolidated wildlife reports. Internet website: http://www.fws.gov/

home/dhoilspill/collectionreports.html#wildlifetable. Posted September 17, 2010. Accessed 

September 20, 2010. 

U.S. Dept. of the Interior. Fish and Wildlife Service. 2010b. Bird impact data from DOI-ERDC 

database download 30 Nov. 2010: Weekly bird impact data and consolidated wildlife reports. 3 pp. 

Internet website: http://www.fws.gov/home/dhoilspill/pdfs/Bird%20Data%20Species%20

Spreadsheet%2011302010.pdf. 

U.S. Dept. of the Interior. Office of the Inspector General. 2010. A new horizon: Looking to the future 

of the Bureau of Ocean Energy Management, Regulation and Enforcement. No. CR-EV-MMS-0015-

2010. Washington DC. 82 pp. Internet website: http://www.doioig.gov/images/stories/reports/pdf/

A%20New%20Horizon%20Public.pdf. 

U.S. Environmental Protection Agency. 2010. Letter from L. Jackson to D. Rainey. May 26, 2010. 

Internet website: http://www.epa.gov/bpspill/dispersants/Rainey-letter-052610.pdf. Accessed 

January 13, 2011. 

U.S. Dept. of Homeland Security and U.S. Environmental Protection Agency. 2010. Letter to Dr. Tony 

Hayward from Janet Napolitano and Lisa P. Jackson. May 20, 2010 Internet website: 

http://www.epa.gov/bpspill/dispersants/bp-hayward-dhs-epa.pdf. Accessed January 13, 2011. 

Valentine, D.L., J.D. Kessler, M.C. Redmond, S.D. Mendes, M.B. Heintz, C. Farwell, L. Hu, 

F.S. Kinnaman, S. Yvon-Lewis, M. Du, E.W. Chan, F. Garcia Tigreros, and C.J. Villaneuva. 2010. 

Propane respiration jump-starts microbial response to a deep oil spill. Science Express. Internet 

website: http://www.sciencemag.org/cgi/content/abstract/science.1196830. Posted September 16, 

2010. 

Webb, T. 2010. BP oil spill: Failed safety device on Deepwater Horizon rig was modified in China. 

The Observer. Internet website: http://www.guardian.co.uk/environment/2010/jul/18/deepwaterhorizon-blow-out-preventer-china. Posted July 18, 2010. Accessed September 22, 2010. 

White, J. 2010. Gulf of Mexico oil spill response leader Thad Allen to step down Oct. 1. The Times 

Picayune. September 24, 2010. Internet website: http://www.nola.com/news/gulf-oil-spill/index.ssf/

2010/09/gulf_of_mexico_oil_spill_respo_2.html. Accessed January 13, 2011. 

Winter, A. 2010. Gulf oil spill creates ‘giant experiment’ in marine toxicology. The New York Times. 

May 21, 2010. Internet website: http://www.nytimes.com/gwire/2010/05/21/21greenwire-gulf-oilspill-creates-giant-experiment-in-mari-1284.html. Accessed January 13, 2011. 
Weekly Rig Activity 43 37 41 42 40 32 37 32 32 29 23 22 17 17 9 10 10 10 9 10 10 11 11 11 10 11 10 10 11 12 13 14 

56 53 55 58 51 54 49 47 45 41 34 30 23 22 14 9 14 14 17 20 22 21 20 20 20 19 20 19 21 20 20 22 

89 82 89 91 87 76 82 77 77 72 65 62 53 54 39 41 40 39 42 43 50 50 48 44 43 43 42 38 40 41 43 50 

0102030405060708090 100 4/10/2010 4/24/2010 5/8/2010 5/15/2010 5/29/2010 6/12/2010 6/26/2010 7/10/2010 7/24/2010 8/7/2010 8/21/2010 9/4/2010 9/18/2010 10/2/2010 10/16/2010 10/30/2010 11/13/201

Number of Rigs

Deepwater Drilling Activity Total Wells Drilling Total Rigs Working

Figure D-1. Deepwater Drilling Activity, Total Wells Drilling, and Total Rigs Working from mid-April to December 2010. 
Deepwater Horizon Event Chronology D-31 

Table D-1 

 

Largest Marine Blowouts Prior to the Deepwater Horizon Event 

Well Country Year Amount Spilled (bbl)* Circumstances 

Ixtoc I Mexico 1979 3,467,500 From PEMEX 

Nuwruz Iran 1983-1985 730,000 After attack by Iraqi planes 

Nowruz Iran 1983 292,000 After oil platform hit by a tanker 

Ecofisk Norway 1977 197,100 Not reported 

Funiwa 5 Nigeria 1980 189,800 Not reported 

Montara Australia 2009 146,000 Not reported 

* From Jernelöv (2010) who reported amount spilled in tons, converted here to bbl: 1 ton = 7.3 U.S. bbl. 

Table D-2 

 

Largest Oil Spills from Tankers 

Rank Ship Year Amount Spilled (bbl)* Location 

1 Atlantic Empress 1979 2,095,100 Off Tobago, West Indies 

2 ABT Summer 1991 1,898,000 700 nautical miles off Angola 

3 Castillo de 

Bellver 1983 1,839,600 Off Saldanha Bay, South Africa 

4 Amoco Cadiz 1978 1,627,900 Off Brittany, France 

5 Haven 1991 1,051,200 Genoa, Italy 

6 Odyssey 1988 963,600 700 nautical miles off Nova Scotia, Canada 

7 Torrey Canyon 1967 868,700 Isles of Scilly, United Kingdom 

8 Sea Star 1972 839,500 Gulf of Oman 

9 Irenes Serenade 1980 730,000 Navarino Bay, Greece 

10 Urquiola 1976 730,000 A Corun ̃a, Spain 

11 Hawaiian Patriot 1977 693,500 300 nautical miles off Honolulu 

12 Independenta 1979 693,500 Bosphorus, Turkey 

13 Jakob Maersk 1975 642,400 Oporto, Portugal 

14 Braer 1993 620,500 Shetland Islands, United Kingdom 

15 Khark 5 1989 584,000 120 nautical miles off Atlantic coast of 

Morocco 

* From Jernelöv (2010) who reported amount spilled in tons, converted here to bbl: 1 ton = 7.3 U.S. bbl. 
D-32 Central Planning Area Supplemental EIS 

Table D-3 

 

Personnel, Vessels, Aircraft, and Containment Boom Deployed for Deepwater Horizon Spill Response Activity* 

Date Personnel Vessels Aircraft Containment Boom Deployed (ft) 

April 22 N/R 2 5 N/R 

April 25 500 30 N/R 21,340 

April 30 2000 75 N/R 217,000 

May 5 7,900 200 N/R 564,991 

May 10 10,000 290 N/R 1,000,000 

May 15 17,500 600 N/R 1,250,000 

May 20 24,000 1,000 N/R 1,990,000 

May 25 22,000 1,200 N/R 1,800,000 

May 30 20,000 1,400 N/R 1,900,000 

June 5 20,000 2,600 N/R 2,100,000 

June 10 24,000 4,400 64 2,200,000 

June 15 29,000 5,000 93 2,370,000 

June 20 33,000 6,100 107 2,470,000 

June 25 37,000 6,510 96 2,600,000 

June 30 42,000 6,850 122 2,760,000 

July 5 45,000 7,040 113 2,950,000 

July 10 46,500 6,840 120 3,060,000 

July 15 44,000 6,870 119 3,270,000 

July 20 42,000 5,300 120 3,460,000 

July 25 30,000 3,600 108 3,410,000 

July 30 32,600 4,400 97 3,400,000 

August 5 31,800 4,800 90 3,000,000 

August 10 31,100 4,900 75 2,400,000 

August 15 28,200 4,300 75 2,200,000 

August 20 30,200 4,300 72 2,300,000 

August 25 30,294 4,375 72 2,300,000 

August 28+ 29,705 5,059 64 2,300,000 

September 5 28,000 ++4,000 N/R 1,570,000 

September 10 27,000 3,600 N/R 999,000 

September 15 25,900 4,700 N/R 714,000 

September 17** 25,200 2,600 N/R 670,000 

October 12 16,292 N/R N/R 19,540 

November 22 8,198 552 N/R N/R 

December 1 6,471 451 N/R N/R 

December 10 6,579 382 N/R N/R 

December 23 6,170 260 N/R N/R 

January 6 5,428 345 N/R N/R 

January 13 5,428 348 N/R N/R 

N/R = Not reported. 

* Compiled from UIC Daily Operations Reports from the official Deepwater Horizon Spill Response 

website or from the RestoreTheGulf.gov website (RestoreTheGulf.gov, 2011). 

** Last date of daily and itemized reporting. 

+ No reports for August 29 or September 1. 

++ Aircraft included in vessel count from this point forward. 
Deepwater Horizon Event Chronology D-33 

Table D-4 

 

Cumulative Totals for Oiled and Nonoiled Animals Collected 

as Part of Deepwater Horizon Spill Response Activity* 

Animal Visibly Oiled, Alive Visibly Oiled, Dead Not Visibly Oiled, Alive Not Visibly Oiled, Dead

Birds 2,071 2,240 0 3,705 

Sea Turtles 453 17 75 121 

Marine Mammals 2 4 7 84 

As of September 17, 2010. 

Source: USDOI, FWS, 2010b. 
APPENDIX E 

 

RECENT PUBLICATIONS OF THE ENVIRONMENTAL STUDIES 

PROGRAM, GULF OF MEXICO OCS REGION, 2006—PRESENT
Recent Publications of the Environmental Studies Program E-3 

APPENDIX E. RECENT PUBLICATIONS OF THE ENVIRONMENTAL 

STUDIES PROGRAM, GULF OF MEXICO OCS 

REGION, 2006–PRESENT 

Published in 2010 

Study Number Title 

MMS 2010-001 Proceedings: USA-Mexico Workshop on the Deepwater Physical 

Oceanography of the Gulf of Mexico, June 2007 

MMS 2010-002 Proof of Concept for Platform Recruited Reef Fish, Phase 1: Do Platforms 

Provide Habitat for Subadult Red Snapper? 

MMS 2010-007 Assessment of Marginal Production in the Gulf of Mexico and Lost Production 

from Early Decommissioning 

MMS 2010-015 Low-Frequency Variability of Currents in the Deepwater Eastern Gulf of 

Mexico 

MMS 2010-016 Trophic Aspects of Sperm Whales (Physeter macrocephalus) in the Northern 

Gulf of Mexico Using Stable Isotopes of Carbon and Nitrogen 

BOEMRE 2010-039 Bank Erosion of Navigation Canals in the Western and Central Gulf of Mexico 

Published in 2009 

Study Number Title 

MMS 2009-010 Quality Control and Analysis of Acoustic Doppler Current Profiler Data 

Collected on Offshore Platforms of the Gulf of Mexico 

MMS 2009-013 Foraminiferal Communities of Bathyal Hydrocarbon Seeps, Northern Gulf of 

Mexico: A Taxonomic, Ecologic, and Geologic Study 

MMS 2009-023 Loop Current Frontal Eddies Based on Satellite Remote Sensing and Drifter 

Data 

MMS 2009-032 Post-Hurricane Assessment of Sensitive Habitats of the Flower Garden Banks 

Vicinity 

MMS 2009-039 Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology 

Study: Final Report 

MMS 2009-043 

Blue Crab (Callinectes sapidus) Use of the Ship/Trinity/Tiger Shoal Complex as 

a Nationally Important Spawning/Hatching/Foraging Ground: Discovery, 

Evaluation, and Sand Mining Recommendations Based on Blue Crab, Shrimp, 

and Spotted Seatrout Findings 

MMS 2009-046 Investigations of Chemosynthetic Communities on the Lower Continental Slope 

of the Gulf of Mexico, Interim Report 2 

MMS 2009-048 

Outer Continental Shelf (OCS)-Related Pipelines and Navigation Canals in the 

Western and Central Gulf of Mexico: Relative Impacts on Wetlands Habitats 

and Effectiveness of Mitigation 

MMS 2009-050 Observation of the Deepwater Manifestation of the Loop Current and Loop 

Current Rings in the Eastern Gulf of Mexico 
E-4 Central Planning Area Supplemental EIS 

MMS 2009-051 Proceedings: Twenty-fifth Gulf of Mexico Information Transfer Meeting, 

January 2009 

MMS 2009-055 

MMS 2009-056 

MMS 2009-057 

MMS 2009-058 

Synthesis, Analysis, and Integration of Meteorological and Air Quality Data for 

the Gulf of Mexico Region 

Volume I: User’s Manual for the Gulf of Mexico Air Quality Database 

(Version 1.0) 

Volume II: Technical Reference Manual for the Gulf of Mexico Air Quality 

Database 

Volume III: Data Analysis 

Volume IV: Cart Analysis of Modeling Episode Days 

MMS 2009-059 Evaluation of Oil and Gas Platforms on the Louisiana Continental Shelf for 

Organisms with Biotechnology Potential 

MMS 2009-060 Modeling Waves and Currents Produced by Hurricanes Katrina, Rita, and 

Wilma 

Published in 2008 

Study Number Title 

MMS 2008-001 Deepwater Currents in the Eastern Gulf of Mexico: Observations at 25.5°N 

and 87°W 

MMS 2008-006 Sperm Whale Seismic Study in the Gulf of Mexico: Synthesis Report 

MMS 2008-009 Investigations of Chemosynthetic Communities on the Lower Continental Slope 

of the Gulf of Mexico: Interim Report 1 

MMS 2008-012 Proceedings: Twenty-Fourth Gulf of Mexico Information Transfer Meeting, 

January 2007 

MMS 2008-015 

Lophelia Reef Megafaunal Community Structure, Biotopes, Genetics, Microbial 

Ecology, and Geology (2004-2006) 

NOTE: This study was conducted by the U.S. Geological Survey (USGS) for 

the Agency’s Headquarters’ Office, and it was funded by USGS.

MMS 2008-017 Examination of the Development of Liquefied Natural Gas on the Gulf of 

Mexico 

MMS 2008-018 Viosca Knoll Wreck: Discovery and Investigation of an Early NineteenthCentury Wooden Sailing Vessel in 2,000 Feet of Water 

MMS 2008-019 Post-Hurricane Assessment at the East Flower Garden Bank Long-Term 

Monitoring Site: November 2005 

MMS 2008-022 Effects of Subsea Processing on Deepwater Environments in the Gulf of Mexico 

MMS 2008-024 Executive Summary: 3rd International Deep-Sea Coral Symposium in Miami 

MMS 2008-027 

MMS 2008-028 

Long-Term Monitoring at the East and West Flower Garden Banks, 2004-

2005—Interim Report 

Volume I: Technical Report 

Volume II: Appendices 

MMS 2008-029 Five-Year Meteorological Datasets for CALMET/CALPUFF and OCD5 

Modeling of the Gulf of Mexico Region 

MMS 2008-030 

MMS 2008-031 

Study of Deepwater Currents in the Northwestern Gulf of Mexico 

Volume I: Executive Summary 

Volume II: Technical Report 
Recent Publications of the Environmental Studies Program E-5 

MMS 2008-042 

MMS 2008-043 

MMS 2008-044 

MMS 2008-045 

MMS 2008-046 

MMS 2008-047 

History of the Offshore Oil and Gas Industry in Southern Louisiana 

Volume I: Papers on the Evolving Offshore Industry 

Volume II: Bayou Lafourche—Oral Histories of the Oil and Gas Industry 

Volume III: Morgan City’s History in the Era of Oil and Gas—Perspectives of 

Those Who Were There 

Volume IV: Terrebonne Parish 

Volume V: Guide to the Interviews 

Volume VI: A Collection of Photographs 

MMS 2008-048 

Platform Debris Fields Associated with the Blue Dolphin (Buccaneer) Gas and 

Oil Field Artificial Reef Sites Offshore Freeport, Texas: Extent, Composition, 

and Biological Utilization 

MMS 2008-050 

MMS 2008-051 

Labor Needs Survey 

Volume I: Technical Report 

Volume II: Survey Instruments 

MMS 2008-052 Benefits and Burdens of OCS Activities on States, Labor Market Areas, Coastal 

Counties, and Selected Communities 

MMS 2008-058 Cumulative Increment Analysis for the Breton National Wilderness Area 

Published in 2007 

Study Number Title 

MMS 2007-015 Archaeological and Biological Analysis of World War II Shipwrecks in the Gulf 

of Mexico; Artificial Reef Effect in Deepwater 

MMS 2007-019 Mixtures of Metals and Polynuclear Aromatic Hydrocarbons May Elicit 

Complex, Nonadditive Toxicological Interactions 

MMS 2007-022 Full-Water Column Current Observations in the Central Gulf of Mexico: Final 

Report

MMS 2007-030 Incorporation of Gulf of Mexico Benthic Survey Data into the Ocean 

Biogeographic Information System

MMS 2007-031 Idle Iron in the Gulf of Mexico

MMS 2007-033 Cooperative Research to Study Dive Patterns of Sperm Whales in the Atlantic 

Ocean

MMS 2007-034 Competition and Performance in Oil and Gas Lease Sales and Development in 

the U.S. Gulf of Mexico OCS Region, 1983-1999

MMS 2007-035 

Seafloor Characteristics and Distribution Patterns of Lophelia pertusa and 

Other Sessile Megafauna at Two Upper-Slope Sites in the Northeastern Gulf of 

Mexico 

MMS 2007-044 Characterization of Northern Gulf of Mexico Deepwater Hard-Bottom 

Communities with Emphasis on Lophelia Coral

MMS 2007-056 

Full-Water Column Currents Near the Sigsbee Escarpment (91-92o W. 

Longitude) and Relationships with the Loop Current and Associated Warm- and 

Cold-Core Eddies 

MMS 2007-061 Study of Barite Solubility and the Release of Trace Components to the Marine 

Environment 

MMS 2007-067 Year 2005 Gulfwide Emission Inventory Study
E-6 Central Planning Area Supplemental EIS 

MMS 2007-068 User’s Guide for the 2008 Gulfwide Offshore Activities Data System 

(GOADS-2008)

Published in 2006 

Study Number Title 

MMS 2006-005 Fidelity of Red Snapper to Petroleum Platforms and Artificial Reefs in the 

Northern Gulf of Mexico 

MMS 2006-011 Sustainable Community in Oil and Gas Country: Final Report 

MMS 2006-028 Degradation of Synthetic-Based Drilling Mud Base Fluids by Gulf of Mexico 

Sediments, Final Report 

MMS 2006-030 Accounting for Socioeconomic Change from Offshore Oil and Gas: Cumulative 

Effects on Louisiana’s Coastal Parishes, 1969-2000 

MMS 2006-034 Sperm Whale Seismic Study in the Gulf of Mexico, Summary Report: 2002-

2004 

MMS 2006-035 Long-Term Monitoring at the East and West Flower Garden Banks National 

Marine Sanctuary, 2002-2003 

MMS 2006-036 Study to Conduct National Register of Historic Places Evaluations of 

Submerged Sites on the Gulf of Mexico Outer Continental Shelf 

MMS 2006-037 

Effect of Depth, Location, and Habitat Type, on Relative Abundance and 

Species Composition of Fishes Associated with Petroleum Platforms and 

Sonnier Bank in the Northern Gulf of Mexico 

MMS 2006-044 

MMS 2006-045 

MMS 2006-046 

Effects of Oil and Gas Exploration and Development at Selected Continental 

Slope Sites in the Gulf of Mexico; 

Volume I: Executive Summary 

Volume II: Technical Report 

Volume III: Appendices 

MMS 2006-063 Economic Effects of Petroleum Prices and Production in the Gulf of Mexico 

OCS on the U.S. Gulf Coast Economy 

MMS 2006-064 Capital Investment Decisionmaking and Trends in Petroleum Resource 

Development in the U.S. Gulf of Mexico 

MMS 2006-067 Sperm Whale Seismic Study in the Gulf of Mexico, Annual Report: Years 3 and 

4 

MMS 2006-071 

Annotated Bibliography of the Potential Environmental Impacts of Chlorination 

and Disinfection Byproducts Relevant to Offshore Liquefied Natural Gas Port 

Facilities 

MMS 2006-072 Mica Shipwreck Project Report: Deepwater Archaeological Investigation of a 

19th Century Shipwreck in the Gulf of Mexico 

MMS 2006-073 

MMS 2006-074 

Exploratory Study of Deepwater Currents in the Gulf of Mexico 

Volume I: Executive Summary 

Volume II: Technical Report 
APPENDIX F 

 

AGENCY-FUNDED HURRICANE RESEARCH AND STUDIES
Agency-Funded Hurricane Research and Studies F-3 

APPENDIX F. AGENCY-FUNDED HURRICANE RESEARCH AND 

STUDIES 

Project/Study Number Title 

Hurricanes Katrina and Rita 

BOEMRE 2011-003 

(in press) 

Impacts of Recent Hurricane Activity on Historic Shipwrecks in the Gulf of 

Mexico Outer Continental Shelf 

MMS 2009-060 Modeling Waves and Currents Produced by Hurricanes Katrina, Rita, and 

Wilma 

MMS 2009-032 Post-Hurricane Assessment of Sensitive Habitats of the Flower Garden 

Banks Vicinity 

MMS 2008-019 Post-Hurricane Assessment at the East Flower Garden Bank Long-Term 

Monitoring Site: November 2005 

GM-07-x12 Assessing Impact of OCS Activities on Public Infrastructure, Service, and 

Population in Coastal Communities Following Hurricanes Rita and Katrina 

GM-92-42-124 Post-Hurricane Assessment of OCS-Related Infrastructure and Communities 

in the Gulf of Mexico Region 

GM-92-42-125 Spatial Restructuring and Fiscal Impacts in the Wake of Disaster: The Case 

of the Oil and Gas Industry Following Hurricanes Katrina and Rita 

GM-92-42-137 Socioeconomic Responses to Coastal Landloss and Hurricanes: Measuring 

Resilience Among OCS-Related Coastal Communities in Louisiana 

GM-92-42-131 Gulf Coast Subsidence and Wetland Loss: A Synthesis of Recent Research 

Project No. 578 Assessment of Fixed Offshore Platform Performance in Hurricanes Katrina 

and Rita 

Project No. 580 Hindcast Data on Winds, Waves and Currents in Northern Gulf of Mexico 

in Hurricanes Katrina and Rita 

Project No. 581 Pipeline Damage Assessments from Hurricanes Katrina and Rita 

Project No. 591 

(completed December 5, 

2007) 

Evaluate Accuracy of Polyester Subrope Damage Detection Performed by 

Remotely-Operated Vehicles (ROV’s) Following Hurricanes and Other 

Events 

Project No. 593 Evaluate and Assess the Performance of Jackup Rigs That Were Subject to 

Hurricanes Katrina or Rita 

Project No. 599 JIP to Quantify Risks in Deepwater Production Facilities and Flowlines in 

the GOM 

Project No. 603 Stability of Tension-Leg Platforms (TLP’s) with Damaged Tendons 
F-4 Central Planning Area Supplemental EIS 

Project No. 604 Evaluation of Fatigue Life Models and Assessment Practice for Tension-Leg 

Platforms (Phase 1: Tendon System Fatigue) 

Project No. 605 Cooperative Research on Extreme Seas and Their Impact to Floating 

Structures 

Project No. 609 Reliability vs. Consequence of Failure for API RP 2A Platforms Using 

RP2MET 

Hurricane Ivan 

GM-05-x12 Ocean Currents under Hurricane Ivan on the Mississippi/Alabama Shelf 

Project No. 548 

Examination and Review of Mobile Offshore Drilling Unit (MODU) Loss 

of Station-keeping Ability during Hurricane Ivan and Assessment of Current 

Mooring Standards and Criteria to Prevent Similar Failures 

Project No. 549 Assessment of Fixed Offshore Platforms in Hurricane Ivan, Andrew 

Project No. 550 A Pilot Study for Regionally-Consistent Hazard Susceptibility Mapping of 

Submarine Mudslides, Offshore Gulf of Mexico 

Project No. 551 Assessment of Drilling and Workover Rig Storm Sea Fastenings on 

Offshore Floating Platforms during Hurricane Ivan 

Project No. 552 Mudslides during Hurricane Ivan and an Assessment of the Potential for 

Future Mudslides in the GOM 

Project No. 553 Pipeline Damage Assessment from Hurricane Ivan 

Project No. 559 Offshore Hurricane Readiness and Recovery Conference 

Hurricane Lili 

Project No. 466 Validation and Calibration of API RP2A Using Hurricane Lili to Update the 

Hurricane Andrew JIP Results that Provided the Basis for API Section 17 

Project No. 467 Hindcast Study of Winds, Waves, and Currents in Northern GOM in 

Hurricane Lili (2002) 

Project No. 469 Post-Mortem Failure Assessment of Drilling Rigs during Hurricane Lili 

Project No. 471 Assessment of Performance of Deepwater Floating Production Facilities 

Project No. 503 Evaluate and Compare Hurricane-Induced Damage to Offshore Pipelines for 

Hurricane Lili—Rev. A 

Hurricane Andrew 

Project No. 193 Study and Hindcast of Wind and Wave Fields for Hurricane Andrew 

Project No. 199 Hurricane Andrew Calibration Study 

Project No. 201 Evaluation of Hurricane Pipeline Damage 
Agency-Funded Hurricane Research and Studies F-5 

Project No. 203 

Performance of Safety and Pollution Control Devices in the Aftermath of 

Hurricane Andrew (Part of the Hurricane Andrew OCS Damage Assessment 

Program) 

Project No. 204 Post-Mortem Platform Failure Evaluation Study 

Project No. 206 Shallow-Water Wave and Current Field Study 

Project No. 207 API/Hurricane Foundation Study 

Project No. 209 Development of Acceptance Criteria for Caisson Structures Damaged 

during Hurricane Andrew 

Project No. 210 Hurricane Andrew Effects on Offshore Platforms 

Project No. 224 Dynamic Nonlinear Loading Effects on Offshore Platforms 

Project No. 229 Hurricane Andrew Effects on Offshore Platforms (Phase II – JIP) 
KEYWORD INDEX
Keyword Index Keyword-1 

KEYWORD INDEX 

Air Quality, x, 1-13, 1-15, 1-16, 1-18, 1-26, 1-31, 2-6, 2-8, 2-9, 3-20, 3-22, 4-6, 4-7, 4-8, 4-9, 4-11, 4-12, 

4-13, 4-14, 4-15, 4-16, 4-17, 4-18, 4-19, 4-227, 4-235, 4-254, 4-385, 4-387, 4-393 

Alternative Energy, 4-390 

Annular Preventer, 1-23, 3-47 

Archaeological Resources, x, xiii, 1-14, 1-16, 1-18, 1-21, 1-27, 2-6, 2-21, 2-22, 2-23, 3-5, 3-6, 3-8, 3-25, 

4-52, 4-301, 4-302, 4-303, 4-304, 4-305, 4-306, 4-307, 4-308, 4-309, 4-310, 4-311, 4-312, 4-313, 4-

314, 4-385, 4-387, 4-388, 4-394, 4-395 

Artificial Reefs, 1-13, 1-30, 2-6, 2-20, 2-21, 3-11, 3-54, 3-59, 3-63, 4-95, 4-98, 4-120, 4-123, 4-149, 4-

265, 4-276, 4-282, 4-285, 4-286, 4-288, 4-289, 4-292, 4-294, 4-295, 4-308, 4-309, 4-368, 4-370, 4-377, 

4-396 

Beach Mice, x, xii, 2-18, 4-213, 4-214, 4-215, 4-216, 4-217, 4-218, 4-385, 4-387, 4-393 

Blowout Preventer, 1-7, 1-8, 1-9, 1-10, 1-20, 1-23, 1-25, 3-24, 3-38, 3-46, 3-47, 3-48, 3-49, 3-50, 3-51, 4-

100, 4-125, 4-151, 4-371 

Blowouts, viii, xi, xii, xiii, 1-7, 1-8, 1-9, 1-16, 1-20, 1-22, 1-23, 1-25, 1-33, 2-9, 2-10, 2-12, 2-13, 2-14, 2-

15, 2-16, 2-20, 2-21, 2-24, 2-25, 3-11, 3-24, 3-31, 3-32, 3-34, 3-38, 3-39, 3-40, 3-45, 3-46, 3-47, 3-48, 

3-51, 4-11, 4-14, 4-16, 4-20, 4-24, 4-26, 4-28, 4-34, 4-38, 4-39, 4-40, 4-41, 4-53, 4-93, 4-100, 4-103, 4-

105, 4-106, 4-107, 4-108, 4-109, 4-111, 4-112, 4-113, 4-116, 4-118, 4-124, 4-128, 4-130, 4-131, 4-132, 

4-133, 4-136, 4-137, 4-146, 4-149, 4-151, 4-157, 4-158, 4-159, 4-160, 4-162, 4-167, 4-168, 4-169, 4-

182, 4-183, 4-184, 4-185, 4-186, 4-190, 4-191, 4-192, 4-193, 4-194, 4-195, 4-200, 4-202, 4-205, 4-210, 

4-211, 4-259, 4-261, 4-265, 4-266, 4-267, 4-268, 4-269, 4-270, 4-271, 4-277, 4-278, 4-279, 4-281, 4-

282, 4-288, 4-315, 4-321, 4-326, 4-328, 4-335, 4-345, 4-363, 4-370, 4-371, 4-376, 4-377, 4-378, 4-380, 

4-381, 4-386, 4-387, 4-388, 4-392, 4-393 

Chemosynthetic Communities, xii, 1-13, 1-14, 2-6, 2-15, 3-24, 4-171, 4-172, 4-173, 4-175, 4-177, 4-178, 

4-180, 4-181, 4-182, 4-183, 4-184, 4-185, 4-186, 4-187, 4-188, 4-189, 4-190 

Chemosynthetic Deepwater Benthic Communities, 2-15, 4-171 

Coastal And Marine Birds, x, xii, 1-3, 2-3, 2-18, 3-4, 4-3, 4-5, 4-219, 4-223, 4-225, 4-227, 4-228, 4-229, 

4-233, 4-234, 4-235, 4-236, 4-237, 4-240, 4-241, 4-242, 4-385, 4-387, 4-393, 5-3 

Coastal Barrier Beaches, x, xi, 2-10, 4-43, 4-44, 4-51, 4-54, 4-56, 4-59, 4-319, 4-385, 4-387 

Coastal Infrastructure, xiii, 2-22, 2-23, 3-27, 3-28, 3-30, 3-56, 4-226, 4-306, 4-312, 4-314, 4-315, 4-317, 

4-318, 4-321, 4-322, 4-323, 4-325 

Coastal Zone Management, x, 1-4, 1-5, 1-21, 1-27, 4-19, 4-58, 5-5, 5-7 

Collisions, viii, xiii, xiv, 1-33, 2-9, 2-10, 2-17, 2-18, 2-24, 2-25, 3-31, 3-52, 3-53, 4-26, 4-28, 4-38, 4-40, 

4-41, 4-53, 4-54, 4-71, 4-79, 4-84, 4-183, 4-191, 4-200, 4-203, 4-206, 4-208, 4-209, 4-210, 4-212, 4-

221, 4-228, 4-229, 4-235, 4-236, 4-240, 4-241, 4-242, 4-255, 4-315, 4-321, 4-322, 4-326, 4-328, 4-335, 

4-345, 4-346, 4-349, 4-392, 4-393 

Commercial Fishing, x, xiii, 1-13, 1-23, 2-6, 2-20, 3-11, 3-12, 3-54, 3-55, 4-4, 4-20, 4-109, 4-133, 4-134, 

4-160, 4-201, 4-203, 4-205, 4-212, 4-254, 4-258, 4-268, 4-271, 4-272, 4-274, 4-275, 4-276, 4-277, 4-

279, 4-280, 4-281, 4-282, 4-285, 4-286, 4-287, 4-288, 4-294, 4-300, 4-307, 4-309, 4-316, 4-330, 4-334, 

4-335, 4-340, 4-379, 4-385, 4-387, 4-394, 4-396 

Consultation and Coordination, viii, 1-4, 1-6, 4-337 

Cumulative Activities, viii, 3-54, 3-55, 3-56, 3-57, 3-58, 3-59, 3-60, 3-62, 3-63, 3-65, 3-67, 3-68, 3-69, 3-

70, 3-72, 3-76, 4-3, 4-75, 4-80, 4-212, 4-213, 4-218, 4-219, 4-236, 4-237, 4-241, 4-308, 4-326, 4-329, 

4-330, 4-384, 4-385 
Keyword-2 Central Planning Area Supplemental EIS 

Cumulative Impacts, viii, x, 3-54, 3-56, 3-65, 3-70, 4-3, 4-4, 4-6, 4-16, 4-17, 4-19, 4-20, 4-28, 4-29, 4-30, 

4-41, 4-42, 4-43, 4-54, 4-59, 4-60, 4-74, 4-79, 4-80, 4-86, 4-109, 4-133, 4-136, 4-138, 4-145, 4-160, 4-

169, 4-171, 4-183, 4-184, 4-185, 4-186, 4-191, 4-192, 4-193, 4-194, 4-202, 4-203, 4-204, 4-205, 4-211, 

4-212, 4-213, 4-217, 4-218, 4-219, 4-222, 4-223, 4-234, 4-238, 4-241, 4-242, 4-254, 4-255, 4-259, 4-

260, 4-268, 4-269, 4-271, 4-279, 4-288, 4-289, 4-299, 4-300, 4-301, 4-307, 4-313, 4-315, 4-323, 4-325, 

4-326, 4-329, 4-330, 4-336, 4-349, 4-351, 4-352, 4-354, 4-355, 4-378, 4-380, 4-381, 4-384, 4-385, 4-

386, 4-388, 4-395 

Deepwater, vii, x, 1-3, 1-6, 1-7, 1-9, 1-10, 1-15, 1-16, 1-17, 1-18, 1-25, 1-32, 1-33, 2-16, 2-19, 2-25, 3-4, 

3-7, 3-9, 3-11, 3-14, 3-17, 3-18, 3-20, 3-23, 3-28, 3-29, 3-31, 3-32, 3-34, 3-35, 3-38, 3-39, 3-40, 3-42, 

3-46, 3-48, 3-49, 3-50, 3-51, 3-53, 3-54, 3-56, 3-58, 3-59, 3-63, 3-64, 3-70, 3-76, 4-10, 4-23, 4-32, 4-

33, 4-39, 4-44, 4-48, 4-68, 4-82, 4-103, 4-112, 4-116, 4-117, 4-128, 4-136, 4-141, 4-145, 4-151, 4-154, 

4-172, 4-173, 4-175, 4-176, 4-178, 4-180, 4-181, 4-182, 4-183, 4-184, 4-185, 4-186, 4-187, 4-188, 4-

189, 4-190, 4-191, 4-192, 4-193, 4-194, 4-197, 4-211, 4-223, 4-242, 4-245, 4-253, 4-255, 4-257, 4-260, 

4-265, 4-266, 4-271, 4-276, 4-280, 4-284, 4-289, 4-293, 4-301, 4-302, 4-303, 4-304, 4-305, 4-308, 4-

316, 4-317, 4-319, 4-322, 4-324, 4-325, 4-332, 4-333, 4-338, 4-339, 4-340, 4-341, 4-342, 4-343, 4-346, 

4-350, 4-354, 4-355, 4-360, 4-364, 4-365, 4-371, 4-381, 4-382, 4-384, 4-385, 4-386, 4-389, 4-390, 4-

391, 4-396, 5-4 

Deepwater Horizon Event, vii, x, xiii, xiv, 1-6, 1-7, 1-10, 1-19, 1-23, 1-25, 2-3, 2-4, 2-7, 2-16, 2-17, 2-19, 

2-20, 2-21, 2-23, 2-25, 3-3, 3-4, 3-13, 3-14, 3-18, 3-22, 3-24, 3-27, 3-30, 3-31, 3-32, 3-33, 3-34, 3-35, 

3-37, 3-39, 3-40, 3-41, 3-43, 3-45, 3-46, 3-47, 3-48, 3-50, 3-51, 3-56, 3-62, 3-73, 4-3, 4-4, 4-5, 4-6, 4-7, 

4-8, 4-14, 4-15, 4-16, 4-17, 4-18, 4-20, 4-22, 4-23, 4-24, 4-32, 4-33, 4-34, 4-39, 4-43, 4-44, 4-45, 4-47, 

4-48, 4-49, 4-50, 4-52, 4-53, 4-54, 4-55, 4-56, 4-57, 4-60, 4-61, 4-62, 4-63, 4-65, 4-66, 4-67, 4-70, 4-

72, 4-73, 4-75, 4-78, 4-80, 4-81, 4-82, 4-84, 4-85, 4-86, 4-92, 4-100, 4-109, 4-112, 4-116, 4-117, 4-136, 

4-138, 4-145, 4-146, 4-154, 4-155, 4-162, 4-165, 4-166, 4-170, 4-171, 4-175, 4-176, 4-180, 4-182, 4-

184, 4-185, 4-187, 4-190, 4-193, 4-194, 4-195, 4-196, 4-199, 4-202, 4-203, 4-204, 4-205, 4-208, 4-210, 

4-211, 4-212, 4-213, 4-216, 4-219, 4-220, 4-221, 4-223, 4-233, 4-242, 4-247, 4-252, 4-253, 4-254, 4-

255, 4-258, 4-259, 4-261, 4-262, 4-266, 4-267, 4-268, 4-270, 4-271, 4-272, 4-273, 4-274, 4-275, 4-278, 

4-279, 4-281, 4-282, 4-283, 4-284, 4-285, 4-287, 4-288, 4-289, 4-290, 4-291, 4-292, 4-293, 4-294, 4-

296, 4-297, 4-298, 4-299, 4-301, 4-306, 4-313, 4-315, 4-317, 4-318, 4-320, 4-321, 4-322, 4-323, 4-324, 

4-325, 4-326, 4-327, 4-330, 4-331, 4-332, 4-333, 4-337, 4-338, 4-340, 4-341, 4-344, 4-345, 4-346, 4-

347, 4-348, 4-349, 4-354, 4-355, 4-360, 4-361, 4-362, 4-363, 4-364, 4-381, 4-382, 4-384, 4-389, 4-390, 

4-391, 5-3, 5-8, 5-9 

Demographics, xiii, 2-24, 4-325, 4-326, 4-327, 4-329 

Diamondback Terrapins, x, xiv, 2-26, 4-355, 4-382, 4-383, 4-384, 4-385, 4-387 

Discharges, x, xi, xii, 1-23, 2-9, 2-12, 2-13, 2-14, 2-15, 2-17, 2-18, 2-26, 3-13, 3-19, 3-25, 3-31, 3-33, 4-

19, 4-20, 4-21, 4-24, 4-25, 4-26, 4-28, 4-29, 4-30, 4-31, 4-35, 4-37, 4-39, 4-40, 4-41, 4-42, 4-43, 4-92, 

4-93, 4-95, 4-96, 4-99, 4-109, 4-110, 4-112, 4-113, 4-118, 4-120, 4-121, 4-124, 4-133, 4-135, 4-137, 4-

146, 4-147, 4-148, 4-149, 4-150, 4-151, 4-161, 4-162, 4-163, 4-166, 4-167, 4-168, 4-169, 4-178, 4-181, 

4-182, 4-184, 4-185, 4-186, 4-188, 4-189, 4-190, 4-192, 4-193, 4-194, 4-197, 4-200, 4-202, 4-203, 4-

208, 4-210, 4-211, 4-212, 4-225, 4-227, 4-235, 4-238, 4-241, 4-247, 4-248, 4-249, 4-251, 4-253, 4-254, 

4-257, 4-259, 4-263, 4-264, 4-265, 4-268, 4-269, 4-270, 4-271, 4-276, 4-279, 4-281, 4-282, 4-288, 4-

294, 4-346, 4-364, 4-366, 4-367, 4-370, 4-371, 4-378, 4-380, 4-381, 4-392, 4-393 

Dispersant, 1-24, 2-8, 2-10, 2-15, 2-16, 3-38, 3-39, 3-41, 3-42, 3-43, 3-51, 4-7, 4-15, 4-16, 4-18, 4-23, 4-

24, 4-27, 4-29, 4-33, 4-34, 4-39, 4-43, 4-52, 4-53, 4-54, 4-57, 4-66, 4-71, 4-73, 4-75, 4-85, 4-100, 4-

101, 4-103, 4-104, 4-107, 4-111, 4-112, 4-117, 4-125, 4-126, 4-127, 4-128, 4-129, 4-132, 4-133, 4-136, 

4-137, 4-145, 4-151, 4-152, 4-154, 4-155, 4-156, 4-165, 4-168, 4-175, 4-176, 4-182, 4-183, 4-184, 4-

185, 4-187, 4-190, 4-191, 4-193, 4-201, 4-210, 4-230, 4-231, 4-247, 4-252, 4-253, 4-255, 4-256, 4-261, 

4-265, 4-266, 4-267, 4-278, 4-306, 4-313, 4-345, 4-347, 4-348, 4-354, 4-360, 4-361, 4-362, 4-371, 4-

372, 4-373, 4-374, 4-392, 4-393 

Dispersants, 1-24, 2-8, 2-10, 2-15, 2-16, 3-38, 3-39, 3-41, 3-42, 3-43, 3-51, 4-7, 4-15, 4-16, 4-18, 4-23, 4-

24, 4-27, 4-29, 4-33, 4-34, 4-39, 4-43, 4-52, 4-53, 4-54, 4-57, 4-66, 4-71, 4-73, 4-75, 4-85, 4-100, 4-
Keyword Index Keyword-3 

101, 4-103, 4-104, 4-107, 4-111, 4-112, 4-117, 4-125, 4-126, 4-127, 4-128, 4-129, 4-132, 4-133, 4-136, 

4-137, 4-145, 4-151, 4-152, 4-154, 4-155, 4-156, 4-165, 4-168, 4-175, 4-176, 4-182, 4-183, 4-184, 4-

185, 4-187, 4-190, 4-191, 4-193, 4-201, 4-210, 4-230, 4-231, 4-247, 4-252, 4-253, 4-255, 4-256, 4-261, 

4-265, 4-266, 4-267, 4-278, 4-306, 4-313, 4-345, 4-347, 4-348, 4-354, 4-360, 4-361, 4-362, 4-371, 4-

372, 4-373, 4-374, 4-392, 4-393 

Dunes, x, xi, 2-10, 3-61, 4-43, 4-44, 4-45, 4-46, 4-47, 4-49, 4-50, 4-51, 4-52, 4-53, 4-54, 4-55, 4-56, 4-57, 

4-58, 4-59, 4-63, 4-65, 4-89, 4-213, 4-214, 4-215, 4-216, 4-217, 4-222, 4-224, 4-301, 4-353, 4-382, 4-

385, 4-387 

Economic Factors, xiv, 2-24, 4-295, 4-319, 4-322, 4-330, 4-334, 4-335, 4-336, 4-342, 4-350 

Employment, xiii, xiv, 2-21, 2-24, 4-274, 4-290, 4-291, 4-292, 4-293, 4-295, 4-296, 4-316, 4-319, 4-326, 

4-328, 4-329, 4-330, 4-331, 4-332, 4-333, 4-334, 4-335, 4-336, 4-337, 4-340, 4-342, 4-343, 4-344, 4-

350 

Environmental Justice, x, xiv, 1-6, 2-24, 3-31, 4-320, 4-337, 4-338, 4-340, 4-341, 4-342, 4-343, 4-344, 4-

345, 4-346, 4-347, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355 

Essential Fish Habitats, x, xii, 1-5, 2-19, 2-20, 4-4, 4-117, 4-139, 4-145, 4-152, 4-159, 4-164, 4-259, 4-

260, 4-261, 4-262, 4-263, 4-264, 4-265, 4-266, 4-267, 4-268, 4-269, 4-270, 4-271, 4-272, 4-277, 4-285, 

4-286, 4-385, 4-387, 5-8, 5-9 

Explosive Removals, 2-6, 2-18, 3-26, 4-110, 4-150, 4-162, 4-199, 4-209, 4-248, 4-249, 4-251, 4-254, 4-

269, 4-370 

Fish Resources, x, xii, 2-19, 2-20, 4-78, 4-259, 4-260, 4-263, 4-264, 4-265, 4-266, 4-267, 4-268, 4-269, 4-

270, 4-271, 4-276, 4-279, 4-281, 4-288, 4-385, 4-387, 4-393, 4-394 

Fisheries, xiii, 1-3, 1-12, 1-13, 1-15, 1-16, 1-18, 2-3, 2-20, 2-21, 3-4, 3-29, 3-53, 4-3, 4-5, 4-109, 4-133, 

4-144, 4-183, 4-191, 4-196, 4-198, 4-200, 4-202, 4-203, 4-204, 4-207, 4-211, 4-212, 4-235, 4-241, 4-

243, 4-244, 4-245, 4-246, 4-252, 4-253, 4-254, 4-259, 4-260, 4-262, 4-265, 4-266, 4-267, 4-268, 4-270, 

4-271, 4-272, 4-273, 4-274, 4-275, 4-276, 4-277, 4-278, 4-279, 4-280, 4-281, 4-282, 4-284, 4-285, 4-

286, 4-287, 4-288, 4-289, 4-296, 4-309, 4-320, 4-332, 4-340, 4-345, 4-350, 4-378, 4-393, 4-394, 5-3, 5-

5, 5-6, 5-7, 5-8 

Flaring, 1-20, 1-26, 3-22, 3-23, 4-9, 4-10, 4-11, 4-15, 4-16, 4-17 

Flower Garden Banks, 2-6, 4-102, 4-103, 4-117, 4-126, 4-128, 4-138, 4-139, 4-140, 4-143, 4-144, 4-145, 

4-152, 4-153, 4-155 

Gulf Sturgeon, x, xii, 2-18, 2-19, 4-242, 4-243, 4-244, 4-245, 4-246, 4-247, 4-248, 4-249, 4-250, 4-251, 

4-252, 4-253, 4-254, 4-255, 4-256, 4-257, 4-258, 4-259, 4-385, 4-387, 4-393 

Human Resources, 2-23, 3-54, 4-315, 4-385, 4-387 

Hurricanes, x, 1-17, 1-19, 2-18, 2-20, 2-26, 3-14, 3-15, 3-24, 3-26, 3-27, 3-28, 3-29, 3-48, 3-52, 3-53, 3-

55, 3-60, 3-63, 3-64, 3-71, 3-72, 3-75, 3-76, 4-3, 4-8, 4-17, 4-28, 4-29, 4-41, 4-43, 4-44, 4-45, 4-46, 4-

47, 4-48, 4-49, 4-50, 4-52, 4-56, 4-57, 4-59, 4-60, 4-61, 4-62, 4-63, 4-65, 4-66, 4-67, 4-68, 4-70, 4-72, 

4-75, 4-77, 4-79, 4-80, 4-81, 4-86, 4-87, 4-90, 4-109, 4-112, 4-137, 4-144, 4-145, 4-155, 4-160, 4-163, 

4-164, 4-169, 4-170, 4-171, 4-187, 4-203, 4-205, 4-213, 4-214, 4-215, 4-217, 4-218, 4-222, 4-223, 4-

241, 4-242, 4-245, 4-246, 4-247, 4-250, 4-256, 4-257, 4-258, 4-260, 4-261, 4-268, 4-272, 4-277, 4-279, 

4-280, 4-281, 4-282, 4-286, 4-288, 4-289, 4-290, 4-291, 4-293, 4-300, 4-303, 4-307, 4-309, 4-311, 4-

314, 4-319, 4-324, 4-339, 4-340, 4-343, 4-349, 4-353, 4-354, 4-355, 4-359, 4-379, 4-381, 4-382, 4-383, 

4-384 

Income, xiv, 2-24, 2-25, 4-275, 4-284, 4-296, 4-328, 4-329, 4-331, 4-337, 4-338, 4-339, 4-340, 4-341, 4-

342, 4-343, 4-344, 4-345, 4-346, 4-347, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-390 

Infrastructure, viii, x, xi, xiii, xiv, 2-10, 2-23, 2-24, 2-26, 3-3, 3-10, 3-12, 3-16, 3-17, 3-18, 3-23, 3-24, 3-

25, 3-26, 3-27, 3-28, 3-30, 3-31, 3-34, 3-52, 3-54, 3-55, 3-56, 3-58, 3-60, 3-61, 3-67, 3-73, 3-75, 4-3, 4-

17, 4-26, 4-49, 4-50, 4-51, 4-56, 4-57, 4-58, 4-59, 4-60, 4-66, 4-68, 4-69, 4-77, 4-92, 4-93, 4-98, 4-118, 
Keyword-4 Central Planning Area Supplemental EIS 

4-122, 4-146, 4-149, 4-150, 4-235, 4-249, 4-260, 4-272, 4-295, 4-300, 4-308, 4-315, 4-317, 4-318, 4-

319, 4-320, 4-321, 4-322, 4-323, 4-324, 4-325, 4-337, 4-338, 4-339, 4-340, 4-342, 4-343, 4-344, 4-347, 

4-349, 4-350, 4-351, 4-352, 4-354, 4-355, 4-364, 4-365, 4-369, 4-384, 4-392, 4-396 

Kick, 1-23, 3-49, 3-50 

Land Use, x, xiii, 2-21, 2-23, 3-54, 3-66, 4-252, 4-296, 4-315, 4-316, 4-317, 4-318, 4-321, 4-322, 4-323, 

4-324, 4-325, 4-338, 4-342, 4-351, 4-385, 4-387 

Live Bottoms, ix, x, xi, 1-13, 1-14, 1-15, 1-16, 1-18, 2-5, 2-12, 2-13, 2-14, 2-26, 4-87, 4-88, 4-90, 4-92, 4-

93, 4-94, 4-95, 4-96, 4-97, 4-98, 4-99, 4-100, 4-101, 4-103, 4-104, 4-105, 4-106, 4-107, 4-108, 4-109, 

4-110, 4-111, 4-112, 4-113, 4-114, 4-117, 4-118, 4-119, 4-120, 4-121, 4-122, 4-123, 4-124, 4-125, 4-

126, 4-127, 4-128, 4-129, 4-130, 4-131, 4-132, 4-133, 4-134, 4-135, 4-136, 4-137, 4-262, 4-263, 4-264, 

4-266, 4-268, 4-269, 4-270, 4-271, 4-282, 4-288, 4-385, 4-387, 4-392, 5-9 

Louisiana Highway 1, 2-7, 4-325, 4-343, 4-351 

Low Relief, x, xi, 2-13, 2-14, 2-26, 4-89, 4-113, 4-117, 4-118, 4-119, 4-120, 4-121, 4-123, 4-124, 4-125, 

4-126, 4-131, 4-132, 4-133, 4-135, 4-136, 4-137, 4-271, 4-385 

Macondo, 1-3, 1-6, 3-4, 3-22, 3-42, 3-45, 3-46, 3-49, 4-71, 4-175, 4-306, 4-313, 5-3, 5-4 

Marine Mammals, x, xii, 1-3, 1-4, 1-5, 1-13, 1-29, 1-30, 2-3, 2-6, 2-16, 2-17, 3-4, 3-15, 3-19, 3-25, 3-26, 

3-53, 4-3, 4-194, 4-195, 4-197, 4-198, 4-199, 4-200, 4-201, 4-202, 4-203, 4-209, 4-210, 4-384, 4-385, 

4-387, 4-392, 4-393, 5-3, 5-5, 5-6 

Mercury, 4-21, 4-31, 4-32, 4-96, 4-120, 4-166, 4-252, 4-264, 4-270, 4-276, 4-277, 4-282, 4-366 

Meteorological Conditions, 3-34, 4-7, 4-26, 4-29, 4-38, 4-39, 4-43 

Mitigating Measures, vii, ix, 1-11, 1-13, 2-3, 2-5, 2-6, 2-26, 2-28, 4-13, 4-73, 4-92, 4-107, 4-108, 4-161, 

4-351, 4-385, 4-387, 5-9 

NEPA, vii, 1-4, 1-11, 1-15, 1-18, 1-21, 1-31, 1-32, 2-3, 2-5, 2-6, 2-7, 2-17, 3-31, 3-33, 4-4, 4-5, 4-163, 4-

210, 4-337, 4-382, 4-391, 5-3, 5-4, 5-8 

Noise, 2-16, 2-17, 2-21, 3-12, 3-19, 3-22, 4-196, 4-197, 4-198, 4-199, 4-200, 4-201, 4-203, 4-208, 4-209, 

4-210, 4-212, 4-220, 4-225, 4-226, 4-227, 4-234, 4-236, 4-238, 4-241, 4-242, 4-294, 4-295, 4-296, 4-

300, 4-393 

Nonchemosynthetic Deepwater Benthic Communities, xii, 2-15, 4-186, 4-188, 4-190, 4-387 

Oil Spills, viii, x, xi, xii, xiii, xiv, 1-7, 1-24, 1-25, 1-27, 2-3, 2-11, 2-12, 2-13, 2-14, 2-15, 2-16, 2-18, 2-

19, 2-20, 2-21, 2-22, 2-23, 2-25, 3-13, 3-14, 3-18, 3-27, 3-31, 3-32, 3-33, 3-34, 3-35, 3-36, 3-37, 3-39, 

3-40, 3-41, 3-42, 3-43, 3-44, 3-48, 4-4, 4-5, 4-11, 4-13, 4-14, 4-16, 4-17, 4-18, 4-19, 4-22, 4-26, 4-28, 

4-32, 4-38, 4-39, 4-40, 4-41, 4-44, 4-48, 4-51, 4-52, 4-53, 4-55, 4-57, 4-59, 4-60, 4-61, 4-65, 4-66, 4-

70, 4-71, 4-72, 4-73, 4-74, 4-75, 4-77, 4-79, 4-80, 4-84, 4-86, 4-87, 4-93, 4-100, 4-101, 4-103, 4-104, 

4-105, 4-107, 4-108, 4-109, 4-111, 4-112, 4-113, 4-117, 4-118, 4-124, 4-125, 4-126, 4-128, 4-129, 4-

132, 4-133, 4-136, 4-137, 4-145, 4-146, 4-149, 4-151, 4-152, 4-154, 4-155, 4-156, 4-159, 4-160, 4-161, 

4-162, 4-167, 4-175, 4-176, 4-182, 4-183, 4-184, 4-185, 4-190, 4-191, 4-193, 4-195, 4-200, 4-201, 4-

202, 4-203, 4-210, 4-212, 4-217, 4-218, 4-219, 4-229, 4-232, 4-233, 4-234, 4-235, 4-237, 4-240, 4-241, 

4-242, 4-249, 4-251, 4-252, 4-253, 4-254, 4-255, 4-258, 4-259, 4-265, 4-266, 4-267, 4-268, 4-271, 4-

273, 4-275, 4-277, 4-278, 4-279, 4-282, 4-283, 4-284, 4-286, 4-287, 4-288, 4-289, 4-290, 4-291, 4-293, 

4-294, 4-296, 4-297, 4-298, 4-299, 4-300, 4-301, 4-306, 4-308, 4-310, 4-313, 4-314, 4-315, 4-321, 4-

322, 4-323, 4-335, 4-341, 4-345, 4-346, 4-347, 4-349, 4-354, 4-355, 4-360, 4-361, 4-363, 4-370, 4-371, 

4-372, 4-373, 4-374, 4-375, 4-376, 4-378, 4-380, 4-381, 4-382, 4-383, 4-384, 4-385, 4-386, 4-388, 4-

392, 4-393, 4-394, 4-395, 4-396 

OSRA, 3-34, 3-35, 4-84, 4-217, 4-237, 4-255 

Physical Oceanography, 3-76, 4-20, 4-30 
Keyword Index Keyword-5 

Pinnacle Trend, x, xi, 2-12, 2-13, 2-26, 4-87, 4-88, 4-90, 4-91, 4-92, 4-93, 4-94, 4-95, 4-97, 4-98, 4-99, 4-

100, 4-101, 4-102, 4-103, 4-107, 4-108, 4-109, 4-110, 4-111, 4-112, 4-113, 4-115, 4-117, 4-120, 4-266, 

4-269, 4-385, 4-387 

Pipelines, ix, xii, 1-14, 1-16, 1-18, 1-20, 1-21, 1-23, 1-24, 1-25, 1-32, 2-6, 2-10, 2-11, 2-15, 2-19, 2-27, 3-

11, 3-14, 3-15, 3-16, 3-17, 3-23, 3-25, 3-26, 3-27, 3-28, 3-30, 3-36, 3-52, 3-56, 3-58, 3-59, 3-60, 3-70, 

4-17, 4-25, 4-35, 4-37, 4-49, 4-53, 4-54, 4-58, 4-59, 4-66, 4-67, 4-69, 4-70, 4-72, 4-74, 4-75, 4-76, 4-

77, 4-79, 4-82, 4-83, 4-84, 4-86, 4-98, 4-111, 4-123, 4-135, 4-139, 4-146, 4-150, 4-152, 4-158, 4-189, 

4-226, 4-236, 4-248, 4-249, 4-251, 4-255, 4-268, 4-269, 4-270, 4-276, 4-277, 4-305, 4-307, 4-308, 4-

311, 4-313, 4-314, 4-317, 4-319, 4-320, 4-321, 4-323, 4-338, 4-365, 4-380, 4-387, 4-393, 4-394 

Port Fourchon, xiii, 2-7, 2-24, 3-28, 4-22, 4-49, 4-50, 4-68, 4-75, 4-78, 4-296, 4-317, 4-322, 4-324, 4-325, 

4-326, 4-328, 4-330, 4-338, 4-341, 4-342, 4-343, 4-351 

Produced Waters, xii, 2-12, 2-13, 2-18, 3-13, 3-20, 4-69, 4-77, 4-78, 4-96, 4-97, 4-99, 4-109, 4-110, 4-

112, 4-121, 4-123, 4-133, 4-135, 4-137, 4-147, 4-148, 4-150, 4-162, 4-166, 4-170, 4-185, 4-193, 4-229, 

4-248, 4-252, 4-259, 4-263, 4-268, 4-269, 4-270, 4-271, 4-279, 4-281, 4-282, 4-288, 4-366, 4-367, 4-

378, 4-380, 4-381, 4-392 

Public Services, x, 2-24, 4-335, 4-336 

Recreational Fishing, x, xiii, 2-21, 3-54, 4-236, 4-254, 4-268, 4-269, 4-272, 4-282, 4-283, 4-284, 4-285, 

4-286, 4-287, 4-288, 4-289, 4-292, 4-293, 4-294, 4-295, 4-299, 4-330, 4-334, 4-335, 4-379, 4-385, 4-

387, 4-396 

Recreational Resources, x, xiii, 2-21, 3-54, 4-289, 4-290, 4-292, 4-294, 4-295, 4-296, 4-297, 4-299, 4-

301, 4-385, 4-388 

Resource Estimates, 3-3, 3-4, 3-33 

Sargassum, x, xi, 2-14, 4-142, 4-163, 4-164, 4-165, 4-166, 4-167, 4-168, 4-169, 4-170, 4-171, 4-385, 4-

387, 4-392 

Sea Turtles, x, xii, 1-3, 1-13, 1-29, 1-30, 2-3, 2-6, 2-17, 3-4, 3-25, 4-3, 4-163, 4-164, 4-168, 4-199, 4-204, 

4-205, 4-206, 4-207, 4-208, 4-209, 4-210, 4-211, 4-212, 4-387, 4-393, 5-3 

Seagrass Communities, x, xi, 2-11, 2-26, 4-74, 4-79, 4-80, 4-84, 4-86, 4-113 

Service base, 3-18, 3-19, 3-21, 3-26, 3-27, 3-28, 4-22, 4-68, 4-79, 4-217, 4-269, 4-317, 4-318, 4-319, 4-

324, 4-325, 4-334, 4-338, 4-342, 4-343 

Site Clearance, 1-29, 2-6, 3-26, 4-150, 4-304, 4-309 

Soft Bottoms, x, xiv, 2-25, 4-138, 4-140, 4-142, 4-176, 4-188, 4-189, 4-260, 4-355, 4-361, 4-365, 4-378, 

4-380, 4-381, 4-385 

Spill of National Significance, 4-13 

Submerged Vegetation, 2-11, 4-44, 4-67, 4-80, 4-81, 4-82, 4-83, 4-84, 4-85, 4-86, 4-87, 4-248, 4-262, 4-

377 

Synthetic-Based Drilling Fluids, xi, 3-20, 3-54, 4-20, 4-36, 4-40, 4-365, 4-368 

Topographic Features, ix, x, xi, 2-4, 2-5, 2-6, 2-14, 2-26, 2-28, 4-101, 4-105, 4-114, 4-130, 4-137, 4-138, 

4-139, 4-143, 4-144, 4-145, 4-146, 4-147, 4-148, 4-149, 4-150, 4-151, 4-152, 4-154, 4-155, 4-156, 4-

157, 4-158, 4-159, 4-160, 4-161, 4-162, 4-163, 4-197, 4-260, 4-264, 4-269, 4-365, 4-370, 4-385, 4-386, 

4-387, 5-9 

Tourism, x, xiii, 2-21, 2-24, 3-12, 4-21, 4-55, 4-58, 4-207, 4-285, 4-287, 4-289, 4-290, 4-291, 4-292, 4-

293, 4-294, 4-295, 4-296, 4-297, 4-298, 4-299, 4-300, 4-301, 4-316, 4-326, 4-329, 4-330, 4-332, 4-334, 

4-335, 4-336, 4-346, 4-351, 4-396, 5-5 

Trash, x, xii, 1-29, 1-30, 2-18, 2-26, 3-10, 3-21, 4-199, 4-203, 4-209, 4-213, 4-216, 4-218, 4-225, 4-228, 

4-234, 4-237, 4-238, 4-242, 4-276, 4-383, 4-384, 4-385, 4-388, 4-393 
Keyword-6 Central Planning Area Supplemental EIS 

Unified Area Command, 4-211 

Waste Disposal, 2-23, 3-27, 3-30, 3-31, 4-66, 4-69, 4-70, 4-228, 4-238, 4-315, 4-317, 4-318, 4-320, 4-

321, 4-323, 4-325, 4-341, 4-343, 4-347, 4-352 

Wastes, xi, 3-17, 3-19, 3-21, 3-30, 3-31, 3-60, 4-28, 4-30, 4-35, 4-36, 4-37, 4-41, 4-42, 4-43, 4-60, 4-66, 

4-69, 4-70, 4-79, 4-185, 4-193, 4-228, 4-276, 4-296, 4-317, 4-320, 4-322, 4-341 

Water Quality, x, xi, 1-15, 2-9, 2-14, 2-18, 3-19, 3-25, 3-34, 4-19, 4-20, 4-21, 4-22, 4-25, 4-26, 4-27, 4-

28, 4-29, 4-30, 4-31, 4-32, 4-33, 4-35, 4-37, 4-38, 4-39, 4-40, 4-41, 4-42, 4-43, 4-83, 4-94, 4-96, 4-116, 

4-119, 4-121, 4-147, 4-165, 4-167, 4-168, 4-169, 4-171, 4-197, 4-203, 4-208, 4-212, 4-225, 4-227, 4-

229, 4-234, 4-235, 4-238, 4-242, 4-243, 4-246, 4-248, 4-249, 4-251, 4-263, 4-265, 4-268, 4-269, 4-270, 

4-276, 4-282, 4-285, 4-288, 4-361, 4-385, 4-387, 4-388, 4-392, 4-393, 4-396 

Wetlands, x, xi, 1-6, 2-6, 2-10, 2-11, 2-19, 3-29, 3-58, 3-61, 3-70, 3-71, 4-5, 4-20, 4-21, 4-22, 4-27, 4-44, 

4-49, 4-50, 4-51, 4-52, 4-53, 4-55, 4-56, 4-60, 4-61, 4-62, 4-63, 4-64, 4-65, 4-66, 4-67, 4-69, 4-70, 4-

71, 4-72, 4-73, 4-74, 4-75, 4-76, 4-77, 4-78, 4-79, 4-80, 4-221, 4-222, 4-223, 4-225, 4-226, 4-228, 4-

237, 4-239, 4-241, 4-256, 4-262, 4-263, 4-264, 4-265, 4-268, 4-276, 4-280, 4-286, 4-293, 4-301, 4-316, 

4-319, 4-320, 4-324, 4-325, 4-340, 4-353, 4-385, 4-387, 4-392, 4-394, 4-396