U.S. Department of the Interior

Bureau of Ocean Energy Management 

Gulf of Mexico OCS Region 

OCS EIS/EA 

BOEM 2012-058 

Gulf of Mexico OCS 

Oil and Gas Lease Sale: 2012 

Central Planning Area Lease Sale 216/222 

Final Supplemental Environmental Impact Statement 

Volume I: Chapters 1-4 
U.S. Department of the Interior

Bureau of Ocean Energy Management 

Gulf of Mexico OCS Region 

OCS EIS/EA 

BOEM 2012-058 

Gulf of Mexico OCS 

Oil and Gas Lease Sale: 2012 

Central Planning Area Lease Sale 216/222 

Final Supplemental Environmental Impact Statement 

Volume I: Chapters 1-4 

Author 

Bureau of Ocean Energy Management 

Gulf of Mexico OCS Region 

Published by 

New Orleans

January 2012 

iii

v 

COVER SHEET 

Supplemental Environmental Impact Statement 

for 

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

Draft ( ) Final (x) 

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 

Gulf of Mexico OCS Region 

MS 5410 

1201 Elmwood Park Boulevard 

New Orleans, LA 70123-2394 

Bob Martinson (MS 4042) 

U.S. Department of the Interior 

Bureau of Ocean Energy Management 

381 Elden Street 

Herndon, VA 20170-4817 

(703) 787-1574 

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 potentially 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 BOEM, 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: 

(1) blocks that were previously included within the Gulf of Mexico’s EPA and are within 

100 miles (mi) (161 kilometers [km]) of the Florida coast; 

(2) blocks east of the Military Mission line (86 degrees, 41 minutes West longitude) 

under an existing moratorium until 2022, as a result of the Gulf of Mexico Energy 

Security Act of 2006 (December 20, 2006); 
Summary ix

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

northern portion of the Eastern Gap; and 

(4) and whole and partial blocks that lie within the former Western Gap and are within 

1.4 nautical miles (nmi) north of the continental shelf boundary between the U.S. and 

Mexico. 

The proposed CPA lease sale area encompasses about 63 million ac of the total CPA area of 

66.45 million acres (ac). This area is located offshore Louisiana, Mississippi, and Alabama from 3 to 

about 230 nmi (3.5 to 265 mi; 5.6 to 426 km) offshore in water depths of about 3 to >3,400 meters (m) 

(9 to >11,115 feet [ft]) (Figure 2-1). As of November 2011, about 38.6 million ac of the CPA lease sale 

area are 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’s (BOEM’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 BOEM 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 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. 

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, case-by-case reviews of the seafloor for any proposed activity, and a community adapted to 

sedimentation makes damage to the ecosystem unlikely from routine activities associated with the 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, if applied, 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. 

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 clarifying 
xii Central Planning Area Supplemental EIS

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

communities, as required. 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: Potential effects on marine mammal species may occur from routine activities 

associated with the CPA proposed action and may be direct or indirect. Routine events related to the 

CPA proposed action, particularly when mitigated as required by BOEM, are not expected to have longterm 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 

hydrocarbons persisting in the sea following the dispersal of a large oil slick may result in sublethal 

impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) 

to marine mammals. 

Sea Turtles: Routine activities resulting from the CPA proposed action have the potential to harm sea 

turtles, although this potential is unlikely to rise to a level of significance due to the activity already 

present in the GOM and mitigations that are in place. Accidental events associated with the CPA 

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 are expected to most often result in sublethal 

impacts (e.g., decreased health and/or reproductive fitness and increased vulnerability to disease) to sea 

turtles. 

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. If spills due to the CPA proposed action were to occur in open waters of the OCS 
Summary xiii

proximate to mobile adult finfish or shellfish, the impacts of the spill would depend on the amount 

spilled, the areal extent of the spill, the distance of the spill from estuaries, and the type and toxicity of oil 

spilled. Much of the extent of damage to fish populations would be reduced due to the capability of adult 

fish to avoid the area of 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. Large spills may 

impact commercial fisheries by area closures. The extent of impact depends on the areal extent and 

length of the closure. The impact of spills on catch or value of catch would depend on the volume and 

location (i.e., distance from shore) of a spill, as well as the physical properties of the oil spilled. 

Recreational Fishing: 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, which would also negatively impact recreational 

fishing activity. However, these minor negative effects would be offset by the beneficial role that oil 

platforms serve as artificial reefs for fish populations. An oil spill would likely lead to recreational 

fishing closures in the vicinity of the oil spill. Except for a catastrophic spill such as the DWH event, oil 

spills should not affect recreational fishing to a large degree due to the likely availability of substitute 

fishing sites in neighboring regions. 

Recreational Resources: Routine OCS actions in the CPA can cause minor disturbances to 

recreational resources, particularly beaches, through increased levels of noise, debris, and rig visibility. 

Oil 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, except for a catastrophic spill such as the DWH event, these effects are likely to be small 

in scale and of short duration. 

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 
xiv Central Planning Area Supplemental EIS

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. 

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 

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. Impacts on diamondback terrapins from smaller 

accidental events are likely to affect individual diamondback terrapins in the spill area, but are they 

unlikely to rise to the level of population effects (or significance) given the probable size and scope of 

such spills. Due to the distance of most terrapin habitat from offshore, OCS-energy-related activities, 

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

impact terrapins or their habitat. 

Catastrophic Spill Analysis 

Following the DWH event, BOEM prepared a catastrophic spill analysis (Appendix B). The purpose 

of this technical analysis is to assist BOEM in meeting CEQ requirements. The CEQ regulations address 

impacts with catastrophic consequences in the context of evaluating reasonably foreseeable significant 

adverse effects in an EIS when they address the issue of incomplete or unavailable information (40 CFR 

1502.22). “‘Reasonably foreseeable’ impacts include impacts which have catastrophic consequences 

even if their probability of occurrence is low, provided that the analysis of the impacts is supported by 

credible scientific evidence, is not based on pure conjecture, and is within the rule of reason” (40 CFR 

1502.22(b)(4)). Therefore, this analysis, which is based on credible scientific evidence, 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 not be confused with 

the scenario and impacts anticipated to result from routine activities or more reasonably foreseeable 

accidental events of a CPA proposed action. 
Table of Contents xv

TABLE OF CONTENTS 

Volume I 

Page 

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

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

LIST OF TABLES..................................................................................................................................xxvii

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 ............................................................................................................1-5

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

1.4. Prelease Process .....................................................................................................................1-12

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

1.6. Other OCS-Related Activities................................................................................................1-31

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 ................................................................................2-9

2.3.1.3. Mitigating Measures ..............................................................................2-32

2.3.1.3.1. Topographic Features Stipulation .......................................2-32

2.3.1.3.2. Live Bottom (Pinnacle Trend and Low Relief) 

Stipulation ...........................................................................2-32

2.3.1.3.3. Military Areas Stipulation...................................................2-32

2.3.1.3.4. Evacuation Stipulation ........................................................2-33

2.3.1.3.5. Coordination Stipulation .....................................................2-33

2.3.1.3.6. Blocks South of Baldwin County, Alabama, 

Stipulation ...........................................................................2-33
xvi Central Planning Area Supplemental EIS

2.3.1.3.7. Protected Species Stipulation ..............................................2-33

2.3.1.3.8. Law of the Sea Convention Royalty Payment 

Stipulation ...........................................................................2-33

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

the Biologically Sensitive Topographic Features....................................................2-33

2.3.2.1. Description.............................................................................................2-33

2.3.2.2. Summary of Impacts ..............................................................................2-34

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

15 Miles of the Baldwin County, Alabama, Coast..................................................2-34

2.3.3.1. Description.............................................................................................2-34

2.3.3.2. Summary of Impacts ..............................................................................2-34

2.3.4. Alternative D—No Action ......................................................................................2-35

2.3.4.1. Description.............................................................................................2-35

2.3.4.2. Summary of Impacts ..............................................................................2-35

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...................................................................3-9

3.1.1.2.1. Development and Production Drilling ..................................3-9

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 ..............................................................................3-17

3.1.1.4.2. Barges..................................................................................3-18

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

3.1.1.4.4. Service Vessels....................................................................3-19

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

3.1.1.5. Operational Wastes and Discharges.......................................................3-20

3.1.1.6. Safety Issues...........................................................................................3-23

3.1.1.6.1. Hydrogen Sulfide and Sulfurous Petroleum........................3-23

3.1.1.6.2. Shallow Hazards..................................................................3-24

3.1.1.6.3. New and Unusual Technology ............................................3-25

3.1.1.7. Decommissioning and Removal Operations..........................................3-25

3.1.2. Coastal Impact-Producing Factors and Scenario.....................................................3-27

3.1.2.1. Service Bases .........................................................................................3-28

3.1.2.2. Gas Processing Plants ............................................................................3-30

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

3.1.2.4. Disposal Facilities for Offshore Operations...........................................3-31
Table of Contents xvii

3.2. Impact-Producing Factors and Scenario—Accidental Events ...............................................3-32

3.2.1. Oil Spills..................................................................................................................3-32

3.2.1.1. Risk Analysis for Offshore Spills 1,000 bbl ........................................3-34

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

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

3.2.1.5.1. BOEM and BSEE 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.....................................................................................................3-53

3.2.5. Chemical and Drilling-Fluid Spills .........................................................................3-54

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

3.3.1. OCS Program ..........................................................................................................3-57

3.3.2. State Oil and Gas Activity.......................................................................................3-57

3.3.3. Other Major Factors Influencing Offshore Environments ......................................3-60

3.3.4. Other Major Factors Influencing Coastal Environments.........................................3-68

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 .......................................................................4-7

4.1.1.1. Air Quality ...............................................................................................4-7

4.1.1.1.1. Description of the Affected Environment .............................4-8

4.1.1.1.2. Impacts of Routine Events ..................................................4-10

4.1.1.1.3. Impacts of Accidental Events..............................................4-14

4.1.1.1.4. Cumulative Impacts.............................................................4-17

4.1.1.2. Water Quality.........................................................................................4-20

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 ........................4-27

4.1.1.2.1.4. Cumulative Impacts .......................................4-29

4.1.1.2.2. Offshore Waters ..................................................................4-31

4.1.1.2.2.1. Description of the Affected Environment......4-31

4.1.1.2.2.2. Impacts of Routine Events.............................4-36

4.1.1.2.2.3. Impacts of Accidental Events ........................4-39

4.1.1.2.2.4. Cumulative Impacts .......................................4-42

4.1.1.3. Coastal Barrier Beaches and Associated Dunes.....................................4-45

4.1.1.3.1. Description of the Affected Environment ...........................4-45

4.1.1.3.2. Impacts of Routine Events ..................................................4-51
xviii Central Planning Area Supplemental EIS

4.1.1.3.3. Impacts of Accidental Events..............................................4-55

4.1.1.3.4. Cumulative Impacts.............................................................4-58

4.1.1.4. Wetlands.................................................................................................4-64

4.1.1.4.1. Description of the Affected Environment ...........................4-64

4.1.1.4.2. Impacts of Routine Events ..................................................4-71

4.1.1.4.3. Impacts of Accidental Events..............................................4-76

4.1.1.4.4. Cumulative Impacts.............................................................4-81

4.1.1.5. Seagrass Communities ...........................................................................4-87

4.1.1.5.1. Description of the Affected Environment ...........................4-87

4.1.1.5.2. Impacts of Routine Events ..................................................4-90

4.1.1.5.3. Impacts of Accidental Events..............................................4-92

4.1.1.5.4. Cumulative Impacts.............................................................4-94

4.1.1.6. Live Bottoms..........................................................................................4-96

4.1.1.6.1. Live Bottoms (Pinnacle Trend) ...........................................4-96

4.1.1.6.1.1. Description of the Affected Environment......4-96

4.1.1.6.1.2. Impacts of Routine Events...........................4-104

4.1.1.6.1.3. Impacts of Accidental Events ......................4-112

4.1.1.6.1.4. Cumulative Impacts .....................................4-122

4.1.1.6.2. Live Bottoms (Low Relief) ...............................................4-126

4.1.1.6.2.1. Description of the Affected Environment....4-127

4.1.1.6.2.2. Impacts of Routine Events...........................4-133

4.1.1.6.2.3. Impacts of Accidental Events ......................4-140

4.1.1.6.2.4. Cumulative Impacts .....................................4-149

4.1.1.7. Topographic Features...........................................................................4-154

4.1.1.7.1. Description of the Affected Environment .........................4-154

4.1.1.7.2. Impacts of Routine Events ................................................4-163

4.1.1.7.3. Impacts of Accidental Events............................................4-170

4.1.1.7.4. Cumulative Impacts...........................................................4-181

4.1.1.8. Sargassum ............................................................................................4-184

4.1.1.8.1. Description of the Affected Environment .........................4-184

4.1.1.8.2. Impacts of Routine Events ................................................4-187

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

4.1.1.8.4. Cumulative Impacts...........................................................4-191

4.1.1.9. Chemosynthetic Deepwater Benthic Communities..............................4-193

4.1.1.9.1. Description of the Affected Environment .........................4-193

4.1.1.9.2. Impacts of Routine Events ................................................4-202

4.1.1.9.3. Impacts of Accidental Events............................................4-203

4.1.1.9.4. Cumulative Impacts...........................................................4-205

4.1.1.10. Nonchemosynthetic Deepwater Benthic Communities........................4-208

4.1.1.10.1. Description of the Affected Environment .........................4-208

4.1.1.10.2. Impacts of Routine Events ................................................4-211

4.1.1.10.3. Impacts of Accidental Events............................................4-212

4.1.1.10.4. Cumulative Impacts...........................................................4-214

4.1.1.11. Marine Mammals .................................................................................4-217

4.1.1.11.1. Description of the Affected Environment .........................4-217

4.1.1.11.2. Impacts of Routine Events ................................................4-224

4.1.1.11.3. Impacts of Accidental Events............................................4-227

4.1.1.11.4. Cumulative Impacts...........................................................4-230
Table of Contents xix

4.1.1.12. Sea Turtles............................................................................................4-231

4.1.1.12.1. Description of the Affected Environment .........................4-231

4.1.1.12.2. Impacts of Routine Events ................................................4-237

4.1.1.12.3. Impacts of Accidental Events............................................4-239

4.1.1.12.4. Cumulative Impacts...........................................................4-241

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

Mice .....................................................................................................4-243

4.1.1.13.1. Description of the Affected Environment .........................4-244

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

4.1.1.13.3. Impacts of Accidental Events............................................4-248

4.1.1.13.4. Cumulative Impacts...........................................................4-249

4.1.1.14. Coastal and Marine Birds.....................................................................4-250

4.1.1.14.1. Description of the Affected Environment .........................4-250

4.1.1.14.2. Impacts of Routine Events ................................................4-262

4.1.1.14.3. Impacts of Accidental Events............................................4-267

4.1.1.14.4. Cumulative Impacts...........................................................4-272

4.1.1.15. Gulf Sturgeon.......................................................................................4-283

4.1.1.15.1. Description of the Affected Environment .........................4-283

4.1.1.15.2. Impacts of Routine Events ................................................4-290

4.1.1.15.3. Impacts of Accidental Events............................................4-293

4.1.1.15.4. Cumulative Impacts...........................................................4-295

4.1.1.16. Fish Resources and Essential Fish Habitat...........................................4-301

4.1.1.16.1. Description of the Affected Environment .........................4-302

4.1.1.16.2. Impacts of Routine Events ................................................4-305

4.1.1.16.3. Impacts of Accidental Events............................................4-308

4.1.1.16.4. Cumulative Impacts...........................................................4-311

4.1.1.17. Commercial Fishing.............................................................................4-314

4.1.1.17.1. Description of the Affected Environment .........................4-315

4.1.1.17.2. Impacts of Routine Events ................................................4-320

4.1.1.17.3. Impacts of Accidental Events............................................4-322

4.1.1.17.4. Cumulative Impacts...........................................................4-325

4.1.1.18. Recreational Fishing.............................................................................4-328

4.1.1.18.1. Description of the Affected Environment .........................4-329

4.1.1.18.2. Impacts of Routine Events ................................................4-331

4.1.1.18.3. Impacts of Accidental Events............................................4-332

4.1.1.18.4. Cumulative Impacts...........................................................4-334

4.1.1.19. Recreational Resources ........................................................................4-336

4.1.1.19.1. Description of the Affected Environment .........................4-336

4.1.1.19.2. Impacts of Routine Events ................................................4-342

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

4.1.1.19.4. Cumulative Impacts...........................................................4-347

4.1.1.20. Archaeological Resources....................................................................4-349

4.1.1.20.1. Historic..............................................................................4-349

4.1.1.20.1.1. Description of the Affected Environment....4-349

4.1.1.20.1.2. Impacts of Routine Events...........................4-352

4.1.1.20.1.3. Impacts of Accidental Events ......................4-354

4.1.1.20.1.4. Cumulative Impacts .....................................4-355

4.1.1.20.2. Prehistoric..........................................................................4-359

4.1.1.20.2.1. Description of the Affected Environment....4-359

4.1.1.20.2.2. Impacts of Routine Events...........................4-360
xx Central Planning Area Supplemental EIS

4.1.1.20.2.3. Impacts of Accidental Events ......................4-362

4.1.1.20.2.4. Cumulative Impacts .....................................4-362

4.1.1.21. Human Resources and Land Use .........................................................4-364

4.1.1.21.1. Land Use and Coastal Infrastructure .................................4-364

4.1.1.21.1.1. Description of the Affected Environment....4-365

4.1.1.21.1.2. Impacts of Routine Events...........................4-367

4.1.1.21.1.3. Impacts of Accidental Events ......................4-370

4.1.1.21.1.4. Cumulative Impacts .....................................4-373

4.1.1.21.2. Demographics....................................................................4-376

4.1.1.21.2.1. Description of the Affected Environment....4-376

4.1.1.21.2.2. Impacts of Routine Events...........................4-377

4.1.1.21.2.3. Impacts of Accidental Events ......................4-378

4.1.1.21.2.4. Cumulative Impacts .....................................4-379

4.1.1.21.3. Economic Factors..............................................................4-380

4.1.1.21.3.1. Description of the Affected Environment....4-381

4.1.1.21.3.2. Impacts of Routine Events...........................4-384

4.1.1.21.3.3. Impacts of Accidental Events ......................4-385

4.1.1.21.3.4. Cumulative Impacts .....................................4-386

4.1.1.21.4. Environmental Justice .......................................................4-388

4.1.1.21.4.1. Description of the Affected Environment....4-388

4.1.1.21.4.2. Impacts of Routine Events...........................4-392

4.1.1.21.4.3. Impacts of Accidental Events ......................4-395

4.1.1.21.4.4. Cumulative Impacts .....................................4-402

4.1.1.22. Additional Resources Considered due to the Deepwater Horizon 

Event ....................................................................................................4-408

4.1.1.22.1. Soft Bottoms......................................................................4-408

4.1.1.22.1.1. Description of the Affected Environment....4-408

4.1.1.22.1.2. Impacts of Routine Events...........................4-420

4.1.1.22.1.3. Impacts of Accidental Events ......................4-429

4.1.1.22.1.4. Cumulative Impacts .....................................4-436

4.1.1.22.2. Diamondback Terrapins ....................................................4-440

4.1.1.22.2.1. Description of the Affected Environment....4-440

4.1.1.22.2.2. Impacts of Routine Events...........................4-442

4.1.1.22.2.3. Impacts of Accidental Events ......................4-443

4.1.1.22.2.4. Cumulative Impacts .....................................4-445

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

Biologically Sensitive Topographic Features........................................................4-446

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

15 Miles of the Baldwin County, Alabama, Coast................................................4-448

4.1.4. Alternative D—No Action ....................................................................................4-450

4.2. Unavoidable Adverse Impacts of the Proposed Action .......................................................4-453

4.3. Irreversible and Irretrievable Commitment of Resources....................................................4-456

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

and Enhancement of Long-term Productivity......................................................................4-457
Table of Contents xxi

Volume II 

Page 

LIST OF FIGURES .....................................................................................................................................xi

LIST OF TABLES.....................................................................................................................................xiii

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

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................................................................................................5-8

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

5.8. Magnuson-Stevens Fishery Conservation and Management Act ............................................5-9

5.9. National Historic Preservation Act ........................................................................................5-10

5.10. Major Differences Between the Draft and Final Supplemental EIS’s ...................................5-10

5.11. Letters of Comment on the Draft Supplemental EIS and BOEM’s Responses .....................5-11

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-1

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

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

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

Appendix E Agency-Funded Hurricane Research and Studies .................................................... E-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 (location of the Deepwater Horizon Event in 

Mississippi Canyon Block 252) 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. Infrastructure and Transitioning Pipelines from Federal OCS and Louisiana State 

Waters. .................................................................................................................................A-8

Figure 3-3. Air Quality Jurisdictional Boundary for BOEM and USEPA..............................................A-9

Figure 3-4. OCS-Related Service Bases in the Gulf of Mexico. ..........................................................A-10

Figure 3-5. Major Ports and Domestic Waterways in the Gulf of Mexico...........................................A-11

Figure 3-6. Oil-Spill Events (2008) in the Central Planning Area. ......................................................A-12

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

Western Planning Areas.....................................................................................................A-13

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

Depths. ...............................................................................................................................A-14

Figure 4-3. Seagrass Locations of the Northern Gulf of Mexico..........................................................A-15

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

Areas. .................................................................................................................................A-16

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

Visualized from Sidescan Sonar and Remotely Operated Vehicle Information................A-17

Figure 4-6. Sketch of a Submerged Ridge............................................................................................A-18

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

Oblique View of the 36 Fathom Ridge within the Alabama Alps (C)...............................A-19

Figure 4-8. Location of Roughtongue Reef (A & B) and Oblique View of Roughtongue 

Reef (C)..............................................................................................................................A-20

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

Alabama-Florida Continental Shelf. ..................................................................................A-21

Figure 4-10. Block-Like, Hard-Bottom Substrate North of the Head of De Soto Canyon.....................A-22

Figure 4-11. Location of Topographic Features in the Gulf of Mexico. ................................................A-23

Figure 4-12. Location of Known Chemosynthetic Communities in the Gulf of Mexico. ......................A-24

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............................................................................A-25
xxiv Central Planning Area Supplemental EIS

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

Wildlife Service as Part of the NRDA Process through November 30, 2010....................A-26

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..............................................................................................A-27

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..............................................................................................A-28

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......................................................................................................A-29

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......................................................................................................A-30

Figure 4-19. Location of All Deepwater Horizon Waste Disposal Sites................................................A-31

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...............................A-32

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
List of Tables xxv

LIST OF TABLES 

 Page 

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

Table 1-2. Overview of the Assignment of Regulations between the Bureau of Ocean Energy 

Management and the Bureau of Safety and Environmental Enforcement.........................A-36

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

and Spill .............................................................................................................................A-38

Table 3-1. Projected Oil and Gas in the Gulf of Mexico OCS............................................................A-38

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

Planning Area.....................................................................................................................A-39

Table 3-3. Deepwater Rig Counts, Day Rates, and Annual Drill Rates in the Gulf of Mexico ..........A-40

Table 3-4. Oil Spilled from Pipelines on the Federal OCS, 2002-2009..............................................A-40

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

Planning Area Waters from an Accident Related to Rig/Platform and Pipeline 

Activities Supporting a CPA Proposed Action Over a 40-Year Time Period....................A-41

Table 3-6. Properties and Persistence by Oil Component Group........................................................A-42

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-43

Table 3-8. Primary Cleanup Options Used during the Deepwater Horizon Response........................A-43

Table 3-9. Pipelines Damaged after 2004-2008 Hurricanes Passing through the WPA and CPA......A-44

Table 3-10. Causes of Hurricane-Related Pipeline Spills Greater Than 50 Barrels..............................A-44

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

Parishes of Louisiana in 2009 ............................................................................................A-45

Table 3-12. Designated Ocean Dredged-Material Disposal Sites in the Cumulative Impact Area.......A-46

Table 3-13. Projected OCS Sand Borrowing Needs for Planned Restoration Projects.........................A-48

Table 3-14. Vessel Calls at U.S. Gulf Coast Ports in 2004 and 2009 ...................................................A-48

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-49

Table 3-16. Coastal Impact Assistance Program Allocations for all Eligible States ($).......................A-50

Table 3-17. Coastal Impact Assistance Program Grants Status for Gulf of Mexico States ($).............A-50

Table 3-18. Hurricane Landfalls in the Northern Gulf of Mexico from 1995 through 2010 ...............A-51

Table 3-19. OCS Facility Damage after the 2004-2008 Hurricanes in the WPA and CPA ..................A-51

Table 4-1. National Ambient Air Quality Standards...........................................................................A-52

Table 4-2. Estimated Abundance of Cetaceans in the Northern Gulf of Mexico...............................A-53

Table 4-3. Sea Turtle Taxa of the Northern Gulf of Mexico...............................................................A-54

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-55
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-57

Table 4-6. Birds Collected and Summarized by the U.S. Fish and Wildlife Service PostDeepwater Horizon Event in the Gulf of Mexico.............................................................A-58

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

along the Gulf Coast ..........................................................................................................A-62

Table 4-8. Economic Significance of Commercial Fishing in the Gulf of Mexico.............................A-62

Table 4-9. Top Species Caught by Recreational Fishers in the Gulf Coast States..............................A-63

Table 4-10. Percentage of Species Landings that are Ocean Based......................................................A-64

Table 4-11. Recreational Fishing Participation 2009 ............................................................................A-65

Table 4-12. Angler Trips in the Gulf of Mexico during Certain Months of 2009 and 2010.................A-66

Table 4-13. Angler Trips in the Gulf of Mexico by Location and Mode in 2009 .................................A-67

Table 4-14. Economic Impact of Recreational Fishing in the Gulf of Mexico in 2008 ........................A-68

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

and 2010.............................................................................................................................A-69

Table 4-16a. Employment in the Leisure/Hospitality Industry in Selected Geographic Regions...........A-70

Table 4-16b. Monthly Employment in the Leisure/Hospitality Industry during 2010............................A-71

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

Geographic Regions...........................................................................................................A-72

Table 4-17b. Quarterly Wages in the Leisure/Hospitality Industry in 2009 and 2010............................A-73

Table 4-18. Total Tourism Spending in Gulf Coast States....................................................................A-74

Table 4-19. Coastal Travel, Tourism, and Recreation Estimates in 2004 .............................................A-74

Table 4-20. Number of Beaches and Beach Participation in Gulf States..............................................A-74

Table 4-21. Shipwrecks in the Gulf of Mexico’s Central Planning Area..............................................A-75

Table 4-22. OCS and Non-OCS Program Spill Rates...........................................................................A-76

Table 4-23. Classification of the Gulf Economic Impact Areas............................................................A-77

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

TX-1...................................................................................................................................A-79

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

TX-2...................................................................................................................................A-81

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

TX-3...................................................................................................................................A-83

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

LA1 ....................................................................................................................................A-85

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

LA-2...................................................................................................................................A-87

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

LA-3...................................................................................................................................A-89

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

LA-4...................................................................................................................................A-91
List of Tables xxvii

Table 4-31. Demographic and Employment Baseline Projections for Economic Impact Area 

MS-1 ..................................................................................................................................A-93

Table 4-32. Demographic and Employment Baseline Projections for Economic Impact Area 

AL-1...................................................................................................................................A-95

Table 4-33. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-1....................................................................................................................................A-97

Table 4-34. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-2....................................................................................................................................A-99

Table 4-35. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-3..................................................................................................................................A-101

Table 4-36. Demographic and Employment Baseline Projections for Economic Impact Area 

FL-4..................................................................................................................................A-103

Table 4-37. Baseline Population Projections (in thousands) by Economic Impact Area....................A-105

Table 4-38. Baseline Employment Projections (in thousands) by Coastal Subarea............................A-106

Table 4-39. Liquid Waste Collected from the Deepwater Horizon Event ..........................................A-107

Table 4-40. Solid Waste Collected from the Deepwater Horizon Event ............................................A-108

Table 4-41. Deepwater Horizon Waste Destination Communities .....................................................A-109

Table 4-42. Gulf Coast Claims Facility — Deepwater Horizon Claimant Data by State (status 

report as of April 27, 2011)..............................................................................................A-110

Table 5-1. Scoping Comments ..........................................................................................................A-112

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

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 

BOEM Bureau of Ocean Energy Management 

BOEMRE Bureau of Ocean Energy Management, Regulation and Enforcement 

BOP blowout preventer 

B.P. before present 

BP British Petroleum 

BSEE Bureau of Safety and Environmental Enforcement 

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 
xxx Central Planning Area Supplemental EIS 

CZM Coastal Zone Management 

CZMA Coastal Zone Management Act 

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 
Abbreviations and Acronyms xxxi 

in inch 

ITOPF International Tanker Owners Pollution Federation Limited 

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 

MC 252 Mississippi Canyon Block 252 

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 
xxxii Central Planning Area Supplemental EIS 

NOS National Ocean Service 

NPDES National Pollutant and Discharge Elimination System 

NPR Notice of Proposed Rulemaking 

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 

ONRR Office of Natural Resource Revenue 

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 
Abbreviations and Acronyms xxxiii 

Tcf trillion cubic feet 

TX Texas 

U.S. United States 

U.S.C. United States Code 

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 Western Planning Area (WPA) and one in the 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 (MC 252) 

[Figure 1-2]); (2) the potentially acute impacts that have been reported or surveyed since that time; and 

(3) any new information that may be available since publication of the Multisale EIS or the 2009-2012 

Supplemental EIS. The environmental resources that may be impacted 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. It is important to note that this 

Supplemental EIS was prepared using the best information that was publicly available at the time this 

document was prepared. 

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 19.5 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 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 
1-4 Central Planning Area Supplemental EIS 

bidder(s) on the basis of sealed competitive bids and to formulate such regulations as necessary to carry 

out the provisions of the Act. 

On May 19 2010, USDOI Secretary Salazar announced in Secretarial Order 3299 (USDOI, 2010a) 

that the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) would 

reorganize into two new bureaus within DOI, each reporting to the Assistant Secretary Land and Minerals 

Management. These bureaus were to be known as the Bureau of Ocean Energy Management (BOEM) 

and the Bureau of Safety and Environmental Enforcement (BSEE). The mission of these new bureaus 

was announced by the Secretary (USDOI, 2010a). The mission of BOEM is to administer leasing and 

plans, environmental studies, National Environmental Policy Act (NEPA) analysis, resource evaluation, 

economic analysis, and the renewable energy and marine mineral programs. The mission of BSEE is to 

administer all field operations, including permitting and research, inspections, research, offshore 

regulatory programs, oil-spill response, and newly formed training and environmental compliance 

functions (Federal Register, 2011). The BOEM and BSEE will complete joint Endangered Species Act 

(ESA) consultations, given that the proposed action covered in this Supplemental EIS is authorized by 

both bureaus. Effective October 1, 2011, BOEMRE was reorganized and separated into the two separate 

bureaus, BOEM and BSEE. 

At the completion of the NEPA process, the Secretary will decide if proposed CPA Lease Sale 

216/222 will take place. 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, 

2007b), 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, 2007c), 

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 BOEM’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 BOEM 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 would be scheduled to be held in 2012. The proposed CPA lease 

sale area encompasses about 63 million ac of the total CPA area of 66.45 million ac. This area is located 

offshore Louisiana, Mississippi, and Alabama from 3 to about 230 nmi (3.5 to 265 mi; 5.6 to 426 km) 

offshore in water depths of about 3 to >3,400 m (9 to >11,115 ft) (Figure 1-1). As of November 2011, 

about 38.6 million ac of the CPA sale area are currently unleased. 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 that were previously included within the Eastern GOM Planning Area and are 

within 100 miles of the Florida coast; 

(2) blocks east of the Military Mission line (86 degrees, 41 minutes West longitude) 

under an existing moratorium until 2022, as a result of the Gulf of Mexico Energy 

Security Act of 2006 (December 20, 2006); 
The Proposed Action 1-5 

(3) blocks that are beyond the United States Exclusive Economic Zone in the area known 

as the northern portion of the Eastern Gap; and 

(4) whole and partial blocks that lie within the former Western Gap and are within 

1.4 nmi north of the continental shelf boundary between the U.S. and Mexico. 

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; the stipulations are 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 

on the OCS must comply with other applicable 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, 

regulations, and Executive Orders are summarized in OCS Regulatory Framework for the Gulf of Mexico 

Region (Matthews and Cameron, 2010): 

Regulation, Law, and Executive Orders 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. 
1-6 Central Planning Area Supplemental EIS 

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 

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 61 FR 26771-26772(1996) 

Executive Order 13089: Coral Reef Protection 63 FR 32701-32703(1998) 

Executive Order 13112: Invasive Species 

64 FR 6183 (1999), amended by 

Executive Order 13286 

(2/28/2003) 

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 
The Proposed Action 1-7 

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, 2010a). 

On a separate track and beginning long before the DWH event, the Minerals Management Service 

(MMS, the predecessor agency name to BOEMRE and BOEM) 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 recommendations 

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 BOEM 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 in conditions similar to those associated with 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 be available in the event of 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 originally announced to be effective until November 30, 

2010. 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 BOEMRE wrote an environmental assessment with a Finding of No Significant Impact related to the 

early lifting of the suspension (USDOI, BOEMRE, 2010a). On October 12, 2010, the July 12th 

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 (now BSEE) 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-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”). 
1-8 Central Planning Area Supplemental EIS 

 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 SEMS 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 human safety and environmental protection; and 

improving workplace safety by reducing the risk of human error. 

 Enhanced Inspection Procedures. The BSEE 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. 

Drilling Safety Rule 

The BOEMRE determined issuance of an interim rule was needed; this rule implements 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 revised selected 

sections of 30 CFR 250 Subparts D, E, F, O, and Q. Only a portion of the proposed changes in Subpart D 

add material capital or operating costs (some of which may be significant). For example, identical costly 

new requirements for subsea function testing of remotely operated vehicle (ROV) intervention during 

drill operations (Subpart D) 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 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 confirm that a well will be secured in an emergency situation and prevent a 

possible loss of well control. The ROV test requirement ensures 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 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 incurs additional rig time, but we do not expect the ROV intervention function stump testing to 
The Proposed Action 1-9 

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 requires 

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 

the autoshear and deadman stump tests take close to the same time required to test the LMRP seafloor 

disconnect. The regulation does 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 BSEE data show that two-thirds of deepwater wells drilled are 

exploratory wells, and approximately 23 percent of exploratory wells are completed. 

Negative Pressure Tests

The 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 BSEE within 30 days after installation. These new 

requirements 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, BSEE 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 
1-10 Central Planning Area Supplemental EIS 

250.420(a)(6) 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 adds 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 ensures the integrity of the BOP and that the 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 (2010), 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 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 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 it 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 was implemented on November 15, 2011. 

The BOEMRE was preparing to finalize the SEMS 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 determined that it was appropriate to incorporate all 

of API RP 75. The BSEE intends to address additional safety management system provisions considered 

appropriate in light of the DWH event in additional future rulemakings. 

The implementation of the SEMS Rule has the following benefits: (1) it will 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 limited their effectiveness.); (2) it will impose the 

requirement for a SEMS program on all OCS operators; (3) it will address human factors behind accidents 

not reached by previous regulations; and (4) it will provide a flexible approach to systematic safety and 

environmental oversight that can keep up with evolving technologies. 
The Proposed Action 1-11 

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; 

 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. 

1.3.2. Rule Changes for Reorganization of Title 30: Bureau of Safety and 

Environmental Enforcement and Bureau of Ocean Energy Management 

As of this writing, all regulatory citations in this chapter and in all subsequent chapters of this 

Supplemental EIS are concordant with the regulation changes made following the effectiveness date of 

October 1, 2011, for the creation of BOEM and BSEE (Federal Register, 2011). 

On May 19 2010, USDOI Secretary Salazar announced in Secretarial Order 3299 (USDOI, 2010b) 

that BOEMRE would be reorganized into two new bureaus within DOI, each reporting to the Assistant 

Secretary Land and Minerals Management. On June 18, 2010 (USDOI, 2010c), the Secretary issued 

Secretarial Order 3302 that, for the interim, announced the name change of the former Minerals 

Management Service (MMS) to the Bureau of Ocean Energy Management, Regulation and Enforcement 

(BOEMRE). In the period between the Secretary’s announcement (USDOI, 2010c) and the beginning of 

Fiscal Year 2012 on October 1, 2011, BOEMRE planned the reorganization and the separation of 

responsibilities for the regulations under Title 30, Minerals Resources that had pertained to the former 

MMS. Regulations that are to be administered by BSEE remain in Title 30 CFR Chapter II, and 

regulations that are to be administered by BOEM were put into a new Title 30 CFR Chapter V. A direct 

final rule (Federal Register, 2011) was promulgated; it mapped the Title 30 regulations that will be under 

the authority of each of the two newly formed bureaus among those now existing. The rule pertained 

solely to the organization and codification of existing rules and related technical changes necessitated by 

the division of one agency into two separate bureaus, and it made no changes to the substantive legal 

rights, obligations, or interests of the affected parties and therefore had no public comment period. A 

summary breakdown of responsibility for the regulations under Title 30 is provided in Table 1-2. A 

future proposed rulemaking in support of the Title 30 reorganization is planned for joint issue by BOEM 

and BSEE to address regulatory issues created by splitting functions between the new bureaus. 
1-12 Central Planning Area Supplemental EIS 

1.4. PRELEASE PROCESS

Scoping for this Supplemental EIS was conducted in accordance with the Council on Environmental 

Quality (CEQ) regulations implementing NEPA at 40 CFR 1501.7. Scoping provides those with an 

interest in the OCS Program an opportunity to provide comments on the proposed action. In addition, 

scoping provides BOEM 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 BOEM’s requests for information, comments, input, and 

review on other Bureau of Ocean Energy Management 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 

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); the U.S. Fish and Wildlife Service (FWS); State Governors’ offices; and 

industry groups. 

The BOEMRE provided copies of the Draft Supplemental EIS for review and comment to public and 

private agencies, interest groups, and local libraries from July 1, 2001, through August 16, 2011. To 

initiate the public review and comment period on the Draft Supplemental EIS, BOEMRE published a 

Notice of Availability (NOA) in the Federal Register. Additionally, public notices were mailed with the 

Draft Supplemental EIS and placed on the BOEMRE, Gulf of Mexico OCS Region’s Internet website. In 

accordance with 30 CFR 556.26, BOEMRE held public hearings to solicit comments on the Draft 

Supplemental EIS. The hearings provided 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 were 

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. 
The Proposed Action 1-13 

A consistency review will be performed and a Consistency Determination (CD) will be prepared for 

each affected State prior to proposed CPA Lease Sale 216/222, in accordance with the requirements of the 

CZMA (15 CFR 930.36). To prepare the CD’s, BOEM 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 BOEM 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 BOEM’s CD, the State is required to do the 

following under CZMA: (1) indicate how BOEM’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 BOEM’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 BOEM or the State may request mediation. The regulations provide for an opportunity to 

resolve any differences with the State, but CZMA allows BOEM 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. 

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 NEPA process, will identify the alternative 

chosen. 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 (if the decision is to hold a lease sale), including proposed 

lease sale configuration and terms and conditions. 

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 BOEM and BSEE are 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 550, 30 CFR 251, 30 CFR 551, and 30 CFR 254. 

Measures to prevent or minimize potential impacts are an integral part of the OCS Program. These 

measures are implemented through lease stipulations, 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; 
1-14 Central Planning Area Supplemental EIS 

 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 BSEE issues NTL’s to provide clarification, description, or interpretation of a regulation; to 

provided guidelines on the implementation of a special lease stipulation or regional requirement; or to 

convey administrative information. Since an NTL is a national guidance document, it addresses submittal 

information for development and production plans (DPP’s), which are required for 

development/production activities outside of the western Gulf of Mexico (as defined under 30 CFR 

250.105). A detailed listing of current Gulf of Mexico OCS Region NTL’s is available through BSEE’s 

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 BOEM 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 BOEM and BSEE 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-ofuse 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. 

Geological and Geophysical Activities 

A geological and geophysical (G&G) permit must be obtained from BOEM prior to conducting offlease geological or geophysical exploration or scientific research on unleased OCS lands or on lands 

under lease to a third party (30 CFR 551.4 (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 and 30 CFR 550.105, with regulations outlined in 

30 CFR 550.207 through 550.210. Ancillary activities are activities conducted on-lease and include G&G 

exploration and development 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 BSEE, 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 related to G&G exploration or development activity: 

 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. 
The Proposed Action 1-15 

Additionally, NTL 2009-G34 clarifies that the BSEE, Gulf of Mexico OCS Region, Regional 

Supervisor, Field Operations should be notified in writing 15 days in advance before conducting the 

following types of other 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 BOEM 

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, BOEM conducts a categorical exclusion review (CER), an 

EA, or an EIS in accordance with the G&G Programmatic EA’s conclusions, NEPA guidelines, and other 

applicable BOEM policies. When required under an approved coastal management program, proposed 

G&G permit activities must receive State concurrence prior to BOEM permit approval. 

Exploration and Development Plans 

To ensure conformance with the OCSLA, other laws, applicable regulations, and lease provisions, 

and to enable BOEM to carry out its functions and responsibilities, formal plans (30 CFR 550.211 and 

250.541) with supporting information must be submitted for review and approval by BOEM 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 offshore and onshore impacts that may occur as a result 

of the activities. The BOEM may require additional specific supporting information to aid in the 

evaluation of the potential environmental impacts of the proposed activities. The BOEM can require 

amendment of an OCS plan based on inadequate or inaccurate supporting information. The 30 CFR 250 

and 30 CFR 550 Subpart B regulations were revised to update the information that must be submitted and 

were published in the Federal Register on August 30, 2005 (Federal Register, 2005). 

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, BOEM and 
1-16 Central Planning Area Supplemental EIS 

BSEE operating regulations, and other requirements. Federal agencies, including FWS, NOAA Fisheries 

Service, USEPA, the U.S. Navy, the U.S. Air Force, and the U.S. Coast Guard, 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 BOEM, Gulf of Mexico OCS Region’s Public Information Office. 

In response to increasing deepwater activities in the GOM, this Agency 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 BOEM reviews of the OCS plan, the findings of the proposal-specific CER, EA, 

or EIS, and other applicable BOEM studies and NEPA documents, the OCS plan is approved or 

disapproved by BOEM, or modified and resubmitted. Although very few OCS plans are ultimately 

disapproved, many must be amended prior to approval to fully comply with BOEM’s operating 

regulations and requirements, or other Federal laws; to address the reviewing agencies’ concerns; or to 

avoid potential hazards or impacts to environmental resources. 

Exploration Plans 

An EP must be submitted to BOEM for review and approval 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 550.211 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 550 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 worst-case discharge scenarios, and it provided national 

guidance regarding the content of information in a blowout and worst-case discharge scenario 

descriptions. The NTL 2009-G27 clarifies guidance for submitting OCS plans and DOCD’s to the 

BOEM, Gulf of Mexico OCS Region.

After receiving an EP, BOEM determines if the plan is complete and adequate before technical and 

environmental reviews. The BOEM 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, NOAA Fisheries Service, and/or internal BOEM 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). 
The Proposed Action 1-17 

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 

technology. Based on the Deepwater Task Force’s recommendation, NTL 2000-N06 was developed and 

then 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 BSEE regulatory framework, and it is intended to initiate an early dialogue between BSEE 

and industry before major capital expenditures on deepwater and subsea projects are committed. 

Deepwater technology has been evolving faster than BSEE’s ability to revise OCS regulations; the 

DWOP was established through the NTL process, which provides for a more timely and flexible approach 

to provide guidance on regulatory requirements and 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 BSEE with information specific 

on 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 BSEE operating regulations at 

30 CFR 250. The BSEE 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 (including 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 BSEE 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 BSEE the opportunity to assure that the production system is suitable for the conditions in which 

it will operate. 

The BSEE 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 BSEE 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 BOEM’s primary responsibilities is to ensure development of economically producible 

reservoirs according to sound conservation, engineering, and economic practices as cited in 30 CFR 

550.202(c), 550.203, 250.204, 250.205, 550.210, 550.296, 550.297, 550.298, 550.299, and 550.1101. 

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 BOEM for review and approval. A DOCD describes the proposed development 
1-18 Central Planning Area Supplemental EIS 

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 550.241-550.242, and information guidelines for DOCD’s are provided in NTL’s 2008-G04, 

2009-G27, and 2010-N06. 

After receiving a DOCD, the Bureau of Ocean Energy Management performs technical and 

environmental reviews. The BOEM 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, NOAA Fisheries Service, and/or internal BOEM 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 may be identified by the operator in its EP, 

DWOP, and DOCD, or through BOEM’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 BOEM 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 from established technologies 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 BOEM through 

technical and environmental reviews. New technologies may be outside the framework established by 

BOEM regulations and, thus, their performance (safety, environmental protection, efficiency, etc.) has not 

been addressed by BOEM. 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 BOEM has developed a new or unusual technologies’ 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 new and unusual technologies’ 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 BOEM does not have sufficient 

information to determine its potential impacts to the environment. In this later case, BOEM 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 BSEE’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 BSEE regulations, the operations are evaluated for 
The Proposed Action 1-19 

alternative compliance or departure determination. Any new technologies or equipment that represent an 

alternative compliance or departure from existing BSEE regulation must be fully described and justified 

before they would be approved for use. For BSEE and BOEM 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 and 30 CFR 550.141. Comparative analysis with other approved systems, 

equipment, and procedures is one tool that BSEE uses to assess the adequacy of protection provided by 

alternative technology or operations. Actual operational experience is necessary with alternative 

compliance measures before BSEE would consider them as proven technology. 

Emergency Plans 

Criteria, models, and procedures for shutdown operations and the orderly evacuation of platforms and 

rigs 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. Pre-installation 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 decision-making 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 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 BSEE 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 
1-20 Central Planning Area Supplemental EIS 

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 

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 for the 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 BSEE 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 BSEE 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 for BSEE’s evaluation of operational safety and 

pollution-prevention measures. The APD is reviewed for conformance with the engineering requirements 

and other technical considerations. 

The BSEE 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 BSEE 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, BSEE 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 BSEE with an annual report summarizing plans to permanently abandon the 

well or to bring the well into production. 

Platforms and Structures 

The BSEE 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 
The Proposed Action 1-21 

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 

BSEE 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 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, 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 BSEE is responsible for regulatory oversight of the design, installation, and maintenance of OCS 

producer-operated oil and gas pipelines. The BSEE 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-of-way 

for pipelines that cross other lessees’ leases or unleased areas of the OCS. Pipeline permit applications to 

BSEE 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 BSEE 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 BOEM 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 
1-22 Central Planning Area Supplemental EIS 

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 

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 BSEE 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 BSEE to provide for 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 BSEE 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 

BSEE-approved plan. The BSEE 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 BSEE and BOEM administer an active civil penalties program (30 CFR 250 Subpart N and 

30 CFR 550 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 BSEE 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 550.185(c) to cancel a nonproductive lease with no compensation. 

Exploration and development activities may be canceled under 30 CFR 550.182 and 550.183. 

Pollution Prevention, Oil-Spill Response Plans, and Financial Responsibility 

Pollution Prevention 

Pollution prevention is addressed through proper design and requirements for safety devices. The 

BSEE regulations at 30 CFR 250.400 require that the operator take all necessary precautions to keep its 
The Proposed Action 1-23 

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 

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, BSEE 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, BSEE 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, BSEE 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 BSEE 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 BSEE 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 BSEE 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 BSEE 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 an open hole. A blind ram is 

a straight-edged ram 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 
1-24 Central Planning Area Supplemental EIS 

usually used together to create redundancy in a BOP stack. 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 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 BSEE 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 BSEE 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) that 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 BSEE can grant an exception to this requirement during the BSEE 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 BSEE that it is capable of responding to a “worst-case” 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 BSEE-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 BSEE Gulf 

of Mexico 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 BSEE 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 BSEE-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, training and drills, identification of potentially impacted environmental resources 

and areas of special economic concern and environmental importance, and strategies for the protection of 

these resources and areas. 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, 
The Proposed Action 1-25 

and periodic drills described in the OSRP. All BSEE-approved OSRP’s must be reviewed at least every 

2 years. In addition, revisions must be submitted to BSEE within 15 days whenever 

(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 BSEE 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 BSEE 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, DPP’s, or DOCD’s. The required supplemental information includes the following: 

(1) a description of the blowout scenario as required by 30 CFR 550.213(g) and 550.243(h); (2) a 

description of their assumptions and calculations used in determining the volume of the worst-case 

discharge required by 30 CFR 550.219(a)(2)(iv) (for EP’s) or 30 CFR 550.250(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 must submit a certification 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 BSEE 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 BSEE’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 

As required by 30 CFR 553.11, a designated applicant must demonstrate oil-spill financial 

responsibility (OSFR) for covered offshore facilities (COF’s). A designated applicant may be a 

responsible party or another person authorized under 30 CFR 553. 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 553.3, 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 BSEE 
1-26 Central Planning Area Supplemental EIS 

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. 

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 BOEM 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. 

This Agency issued NTL 2009-N11 to clarify that its regulatory authority and the implementing 

regulations in 30 CFR 250 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 if 

an air quality review is required (30 CFR 550.218 and 550.249). The BOEM 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 BOEM significance levels and to identify appropriate emissions 

controls to mitigate potential onshore air quality degradation. 

Emissions data for new or modified onshore facilities directly associated with proposed OCS 

activities are required to be included in development plans submitted to BSEE so that the affected States 

can determine the potential impacts on their air quality. 

The BOEM 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 annual emissions to the 

BOEM 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 BOEM 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. For those facilities required to submit OCD modeling by exceeding NOx exemption levels, 

BOEM requires those operators to also demonstrate compliance with the new 1-hour NAAQS standards 

for NOx. 

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 
The Proposed Action 1-27 

reservoir development options during unloading/testing operations and/or in emergency situations. The 

BSEE regulates flaring/venting to minimize the loss of revenue producing natural gas resources. The 

BSEE regulations (30 CFR 250.1160) allow, without prior BSEE 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 BSEE. Records must always be prepared by the operator for all 

flaring/venting, and justification must be provided for flaring/venting not expressly authorized by BSEE 

regulations. 

Hydrogen Sulfide Contingency Plans 

The operator of a lease must request a BSEE area classification for the presence of hydrogen sulfide 

(H2S) gas. The BSEE 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 BSEE. 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, wellcompletion, well-workovers, and production operations. The NTL 2009-G31, “Hydrogen Sulfide (H2S) 

Requirements,” provides clarification, guidance, and information regarding BSEE’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 or under the seabed, including archaeological resources such as 

historic shipwrecks. The archaeological resources regulation at 30 CFR 550.194 grants authority in 

certain cases to each BOEM 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 BOEM Regional Supervisor, 

Office of Environment, within 48 hours of its discovery. 

High-resolution surveys, where required, 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 Gulf of Mexico, 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 additional archaeological resource surveys and 

mitigation are 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 BOEM, a 

consistency certification and necessary data and information for the State to determine that the proposed 

activities comply with the enforceable policies of the States’ coastal management program (CMP), 

approved by NOAA, and that such activities will be fully consistent with the enforceable policies 

(16 U.S.C. 1456(c)(3)(A) and 15 CFR 930.76). Except as provided in 15 CFR 930.60(a), State agency 

consistency review begins when the State receives the OCS plan, consistency certification, and necessary 

data and information 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 
1-28 Central Planning Area Supplemental EIS 

required by 15 CFR 930.76 will not extend the date of commencement of review (15 CFR 930.58). The 

information requirements for CZM purposes are found at 30 CFR 550.226 and 250.260 and are discussed 

in NTL 2006-G21, “Regional and Subregional Oil Spill Response Plans”; NTL 2007-G20, “Coastal Zone 

Management Program Requirements for OCS Right-of-Way Pipeline Applications”; NTL 2008-G04, 

“Information Requirements for Exploration Plans and Development Operations Coordination 

Documents”; NTL 2009-G27, “Submitting Exploration Plans and Development Operations Coordination 

Documents”; NTL 2010-N06, “Information Requirements for Exploration Plans, Development and 

Production Plans, and Development Operations Coordination Documents on the OCS”; and NTL 

2010-N10, “Statement of Compliance with Applicable Regulations and Evaluation of Information 

Demonstrating Adequate Spill Response and Well Containment Resources.” 

All of the Gulf States have approved CMP’s. Requirements for the CZM consistency information for 

Texas, Louisiana, Mississippi, Alabama, and Florida are given in NTL’s 2006-G21, 2007-G20, 

2008-G04, 2009-G27, and 2010-N06. In accordance with the requirements of 15 CFR 930.76, BOEM’s 

Gulf of Mexico OCS Region sends copies of an OCS plan, including the consistency certification and 

other necessary data and 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, BOEM shall presume consistency concurrence by the State (15 CFR 930.78(b)). The BOEM can 

require modification of a plan if the operator has agreed to certain requirements requested by the State. 

If BOEM receives a written consistency objection from the State, BOEM 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 BSEE 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 BSEE 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. The BAST 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 BSEE, 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 BSEE 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 BSEE 

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 BSEE 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 
The Proposed Action 1-29 

systems of the past to the large-diameter, high-capacity systems found on drilling rigs operating on the 

OCS today. 

Production Facilities 

The BSEE 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 

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, BSEE 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, BSEE 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 BSEE’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 
1-30 Central Planning Area Supplemental EIS 

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 of 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, 

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 BSEE 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, BSEE 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 
The Proposed Action 1-31 

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 BOEM and BSEE have 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 environmental and technical studies, and cooperative agreements with other 

Federal and State agencies for NEPA work, joint jurisdiction over cooperative efforts, inspection 

activities, and regulatory enforcement. The BOEM 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 Gulf of Mexico 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 D. Studies completed since 1974 are available on the BOEM, Gulf of Mexico OCS Region’s 

Internet website under “Environmental Program.” The BOEM’s Environmental Studies Program 

Information System (ESPIS) provides immediate access to all completed BOEM 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 BOEM 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 BOEM’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 
1-32 Central Planning Area Supplemental EIS 

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 BSEE regulations, rules, and 

operational guidelines ensure the use of BAST (Chapter 1.5, New and Unusual 

Technology). 

 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 

Memoranda 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 BOEM, as lead agency, has requested other Federal agencies to 

become cooperating agencies, while other agencies have requested BOEM 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. Consultation and 

coordination activities for this Supplemental EIS are described in Chapter 5. 

Memoranda of Understanding and Memoranda of Agreement between MMS (BSEE) and 

USCG 

Since BSEE 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 current MOU, 

dated September 30, 2004, supersedes the August 1989 and December 1998 versions of the interagency 

agreement. The MOU is being revised to reflect the October 1, 2011, reorganization of BOEMRE, 

centering on the BSEE role in the coordination and oversight. The MOU is designed to minimize 

duplication and promote consistent regulation of facilities under the jurisdiction of USCG and BSEE. A 

Memorandum of Agreement (MOA), OCS No. 1—Agency Responsibilities, between MMS and USCG, 

dated September 30, 2004, further clarifies the technical and process section of the 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, 
The Proposed Action 1-33 

BSEE has established a full-time position within the Office of Offshore Regulatory Programs to provide 

liaison between the agencies. As with the MOU, the MOA is currently under revision to reflect the recent 

reorganization efforts. 

Generally, the MOU identifies BSEE 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 BSEE), OSFR (i.e., 

BSEE determines and provides OSFR-related information to USCG upon request), oil-spill preparedness 

and response planning (i.e., BSEE requires responsible parties to maintain approved oil-spill-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., BSEE 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. 

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. As per the recommendation by the Council on 

Environmental Quality in the August 16, 2010, report titled Report Regarding the Minerals Management 

Service’s National Environmental Policy Act Policies, Practices, and Procedures as They Relate to Outer 

Continental Shelf Oil and Gas Exploration and Development (Council on Environmental Quality, 2010), 

an analysis of the impacts of low-probability catastrophic spills has been prepared and is included as 

Appendix B. 

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 BOEM study on alternative approaches to leasing. 

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 that were previously included within the Gulf of Mexico’s EPA and are within 

100 mi of the Florida coast; 

(2) blocks east of the Military Mission line (86 degrees, 41 minutes West longitude) 

under an existing moratorium until 2022, as a result of the Gulf of Mexico Energy 

Security Act of 2006 (December 20, 2006); 

(3) blocks that are beyond the United States Exclusive Economic Zone in the area known 

as the northern portion of the Eastern Gap; and 
2-4 Central Planning Area Supplemental EIS 

(4) whole and partial blocks that lie within the former Western Gap and are within 

1.4 nmi north of the continental shelf boundary between the U.S. and Mexico. 

The proposed CPA sale area encompasses about 63 million ac of the total CPA area of 

66.45 million ac. This area is located offshore Louisiana, Mississippi, and Alabama from 3 to about 

230 nmi (3.5 to 265 mi; 5.6 to 426 km) offshore in water depths of about 3 to >3,400 m (9 to >11,115 ft) 

(Figure 2-1). As of November 2011, about 38.6 million ac of the CPA sale area are currently unleased 

and considered for this proposed action. 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 August 2009 (Opaluch et al., 2011a). 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, half the areawide annual, 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 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, BOEMRE modified the original contract to have an additional scenario (growth in 

resource size from the most current estimates combined with effective tax rates half the nominal level) 

run through the original contractor’s model. This additional work was delivered in December 2010 

(Opaluch et al., 2011b). Results under this optimistic scenario, together with those under the more 

pessimistic scenario of the August 2009 version, should bracket the likely future. Major results in both 

versions of the study generally confirm the anticipated tradeoffs between fiscal revenue and production, 

and the results indicate that, in the long run, reduced sale sizes would sacrifice substantial activity for 

increased high bids but would generate little or no fiscal gain because the loss and delay of royalty, rental, 

and tax revenues would offset the higher bonus promised by nomination and tract selection relative to 

areawide leasing. The study also found that negative effects on spending and jobs in coastal States far 

exceed the increase in environmental costs associated with areawide leasing relative to nomination tractselection sale sizes. Informed by this study and other analyses, BOEM has chosen to test an option of 
Alternatives Including the Proposed Action 2-5 

higher minimum bids, which would more simply and directly serve some of the same purposes as tract 

nomination sales without the problems raised by administrative actions to reduce sale sizes or numbers. 

Pending leasing results under the recently increased minimum bid, along with the additional 

regulatory changes following the DWH event, BOEM 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 an 

understanding of environmental consequences and to take actions that protect, restore, and enhance the 

environment. Agencies are required to identify and include in the chosen alternative all relevant and 

reasonable mitigation measures that could improve the action. The CEQ regulation 40 CFR 1508.20 

defines mitigation as follows: 

 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 for 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 BSEE 

and BOEM have the authority to monitor and enforce these conditions, and under 30 CFR 250 Subpart N 

and 30 CFR 550 Subpart N, respectively, they 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 may be applied by BOEM. Mitigating measures 

have been proposed, identified, evaluated, or developed through previous BOEM 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 structure-removal 

applications) go through rigorous BOEM review and approval to ensure compliance with established laws 

and regulations. Existing mitigating measures must be incorporated and documented in plans submitted 

to BOEM. Operational compliance of these mitigating measures is enforced through BSEE’s onsite 

inspection program. 

Mitigating measures that are a standard part of BOEM’s program ensure that the operations are 

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 BOEM-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 BOEM during plan and permit reviews. The 

BOEM 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 BOEM 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; and safety precautions. In addition to 

standard mitigations, BOEM may also apply nonrecurring mitigating measures that are developed on a 

case-by-case basis. 

The BOEM 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 BSEE (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 the No Action Alternative for each issue due to the relevant actions related to the proposed 

action and action alternatives. 

For example, 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 BOEM to be appropriate for this evaluation of the 

one remaining CPA lease sale in the 5-Year Program. 

Following the DWH event, BOEM prepared a catastrophic spill analysis (Appendix B). The purpose 

of this technical analysis is to assist BOEM in meeting CEQ requirements. The CEQ regulations address 

impacts with catastrophic consequences in the context of evaluating reasonably foreseeable significant 

adverse effects in an EIS when they address the issue of incomplete or unavailable information (40 CFR 

1502.22). “‘Reasonably foreseeable’ impacts include impacts which have catastrophic consequences 

even if their probability of occurrence is low, provided that the analysis of the impacts is supported by 

credible scientific evidence, is not based on pure conjecture, and is within the rule of reason” (40 CFR 

1502.22(b)(4)). Therefore, this analysis, based on credible scientific evidence, 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 not be confused with the 

scenario and impacts anticipated to result from routine activities or more reasonably foreseeable 

accidental events of the proposed action. 

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 BOEM and BSEE, 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 
2-8 Central Planning Area Supplemental EIS 

(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. 

On October 1, 2010, the revenue collection function of BOEMRE became the independent Office of 

Natural Resource Revenue (ONRR). The ONRR 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 

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 related to the proposed action and 

alternatives 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 2.2.1.2, the Use of a Nomination and Tract Selection 

Leasing System Alternative was not included for analysis in this Supplemental EIS. 

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 (38.6 million ac) for oil and 

gas operations (Figure 1-1), except the following: 

(1) blocks that were previously included within the Gulf of Mexico’s EPA and are within 

100 mi of the Florida coast; 

(2) blocks east of the Military Mission line (86 degrees, 41 minutes West longitude) 

under an existing moratorium until 2022, as a result of the Gulf of Mexico Energy 

Security Act of 2006 (December 20, 2006); 

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

northern portion of the Eastern Gap; and 

(4) whole and partial blocks that lie within the former Western Gap and are within 

1.4 nmi north of the continental shelf boundary between the U.S. and Mexico.. 

The proposed CPA sale area encompasses about 63 million ac of the total CPA area of 

66.45 million ac. This area is located offshore Louisiana, Mississippi, and Alabama from 3 to about 

230 nmi (3.5 to 265 mi; 5.6 to 426 km) offshore in water depths of about 3 to >3,400 m (9 to >11,115 ft) 

(Figure 1-1). As of November 2011, about 38.6 million ac of the CPA sale area are currently unleased 

and considered for this proposed action. 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. 
Alternatives Including the Proposed Action 2-9 

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 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. 

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. 

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. 

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 also localized and temporary in nature. The impacts to coastal water quality 

from routine activities associated with the CPA proposed action should be minimal because of the 

distance to shore of most routine activities, USEPA’s regulations that restrict discharges, and the few, if 

any, new pipeline landfalls or onshore facilities that would be constructed. 

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 through, for example, increased 

vessel traffic, hydromodification, and the application of dispersants. 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 would not be 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 
2-10 Central Planning Area Supplemental EIS 

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 

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 

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 usually 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 (Appendix B). Although response efforts may decrease the amount of 

oil in the environment, the response efforts may also impact the environment through, for example, 

increased vessel traffic and application of dispersants. Natural physical, chemical, and biological 

processes would decrease the amount of spilled oil over time through dilution, weathering, and 

degradation of the oil. Chemicals used in the oil and gas industry are not a significant risk for a spill 

because they are either nontoxic, are 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 

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. These dredging activities 

are permitted, regulated, and coordinated by COE with the appropriate State and Federal resource 

agencies. Impacts from these operations are minimal due to requirements for the beneficial use of the 

dredged material for wetland and beach construction and restoration where appropriate. Permit 

requirements further mitigate dredged material placement in approved disposal areas by requiring the 

dredged material to be placed in such a manner that it neither disrupts hydrology nor changes elevation in 

the surrounding marsh. Because these impacts occur regardless of the proposed action, the proposed 

action would account for a small percentage of these impacts from routine events. There could be a slight 

chance of disturbing or resuspending buried, remnant oil from the DWH event through channel 

maintenance or trenching associated with pipeline placement. However, based on sediment analyses in 

the OSAT report (2010), there were no exceedances of USEPA’s aquatic life benchmarks for PAH’s in 

sediment beyond 3 km (~2 mi) from the wellhead that were linked to the oil from the DWH event. Since 

dredging, vessel traffic, and pipeline emplacement activities would be far removed from most affected 

areas, the chance of resuspension of toxic sediment would be improbable. 

Based on the findings of the OSAT-2 report (2011), weathered oil samples showed PAH’s were 

depleted by 86-98 percent in most beach locations. The PAH model predictions also predict that PAH 

concentrations in subtidal buried oil will decrease to 20 percent of current levels within 5 years (OSAT-2, 

2011). 

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 
Alternatives Including the Proposed Action 2-11 

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 because of their concentration and lack of weathering by the time they hit the shore and 

because dispersants are not utilized in inshore waters due to negative effects on the shallow-water coastal 

habitats. 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 (historical data indicate that coastal spills 

average <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, such as disturbance of sands through foot traffic and mechanized 

cleanup equipment (e.g., sifters), dispersal oil deeper into sands and sediments, and foot traffic in marshes 

impacting the distribution of oils and marsh vegetation. Close monitoring and restrictions on the use of 

bottom-disturbing equipment would be needed to avoid or minimize those impacts. 

The BOEM 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). Although 

monitoring is still ongoing, the current data show that the toxic components of remnant oil is expected to 

continue to decline as noted above (OSAT-2, 2011). 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 proposed action will not pose a significant 

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 could cause the 

loss of 0-8 ha (0-20 ac) of wetlands habitat. It is expected that these impacts would be reduced or 

eliminated 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. 

Offshore oil spills resulting from the CPA proposed action would have a low probability of 

contacting and damaging any wetlands along the Gulf Coast, except in the case of a catastrophic event 

(Appendix B). This is because of the distance of the spill to the coast, because of the likely weathered 

condition of oil (through evaporation dilution and biodegradation) should it reach 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 nearshore vessel accident or pipeline rupture. Wetlands in the northern Gulf of 

Mexico are 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 
2-12 Central Planning Area Supplemental EIS 

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 that may impact seagrasses are not expected to significantly 

increase in occurrence and range in the near future. Requirements of other Federal and State programs, 

such as avoidance of the seagrass and vegetation communities or the use of turbidity curtains, reduce 

undesirable effects on submerged vegetation beds from dredging activities. Federal and State 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 and implemented programs, along with the beneficial effects of natural flushing (e.g., from 

winds and currents), any potential effects from routine activities on submerged vegetation in the CPA are 

expected to be localized and not significantly adverse. 

As noted in Chapter 4.1.1.5.1, there remains uncertainty regarding the impacts of the DWH event on 

submerged vegetation. At least for submerged vegetation in Louisiana, Mississippi, and Alabama, 

BOEM cannot definitively determine that the incomplete or unavailable information being developed 

through the NRDA process may be essential to a reasoned choice among alternatives. Nevertheless, the 

ongoing research on submerged vegetation after the DWH event is being conducted through the NRDA 

process. These research projects may be years from completion, and data and conclusions have not been 

released to the public. Regardless of the costs involved, it is not within BOEM’s ability to obtain this 

information from the NRDA process within the timeline of this Supplemental EIS. In light of this 

incomplete and unavailable information, BOEM subject-matter experts have used credible scientific 

information that is available and applied it using scientifically accepted methodology. Nevertheless, 

impacts to submerged vegetation from routine activities of the proposed action are expected to be 

minimal because of the distance of most activities from the submerged vegetation beds and because the 

0-1 pipeline landfall and maintenance dredging are heavily regulated and permitted; mitigations (such as 

turbidity curtains and siting away from beds) may be required. 

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 are expected to continue to 

improve and will decrease the detrimental effects to submerged vegetation from the CPA proposed action. 

There remains uncertainty regarding the impacts of the DWH event on submerged vegetation. At 

least for submerged vegetation in Louisiana, Mississippi, and Alabama, BOEM cannot definitively 

determine that the incomplete or unavailable information being developed through the NRDA process 

may be essential to a reasoned choice among alternatives. Nevertheless, the ongoing research on 

submerged vegetation after the DWH event is being conducted through the NRDA process. These 

research projects may be years from completion, and data and conclusions have not been released to the 

public. Regardless of the costs involved, it is not within BOEM’s ability to obtain this information from 

the NRDA process within the timeline of this Supplemental EIS. In light of this incomplete and 

unavailable information, BOEM subject-matter experts have used credible scientific information that is 

available and applied it using scientifically accepted methodology. Nevertheless, impacts to submerged 

vegetation from an accidental event related to the proposed action are expected to be minimal because of 
Alternatives Including the Proposed Action 2-13 

the distance of most activities from the submerged vegetation beds and because the likelihood of an 

accidental event of size, location, and duration reaching submerged vegetation spills remains small. 

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 (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, could have 

localized impacts on the benthos nearby the well; however, impacts would be reduced with distance from 

the well. 

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. Produced waters 

also rapidly disperse and remain in the surface layers of the water column, far above the peaks of 

Pinnacles. 

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 experience 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. 

Live-bottom (Pinnacle Trend) features represent a small fraction of the continental shelf area in the 

CPA. The small portion of the seafloor covered by these features, 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 features. 

The proposed Live Bottom (Pinnacle Trend) Stipulation (Chapter 2.4.1.3.2), if applied, would 

prevent most of the potential impacts from oil and gas operations, including accidental oil spills and 

blowouts, on the biota of Pinnacle Trend features by increasing the distance of such events from the 

features. It would be expected that the majority of oil would rise to the surface and that the most heavily 

oiled sediments would likely be deposited before reaching the Pinnacle 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. 
2-14 Central Planning Area Supplemental EIS 

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 near the sensitive 

features. 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) (Chapter 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 (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. 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, could have localized impacts on the benthos near the well, 

which should be located away from live-bottom features according to BOEM policy, and additionally, 

impacts would be reduced with distance from the well. 

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 BOEM’s site-specific seafloor review prior to any bottom-disturbing activity 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. Produced waters also rapidly disperse and 

remain in the surface layers of the water column, far above the live-bottom features. 

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 BOEM policy, 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 BOEM sitespecific seafloor review and required distancing of seafloor disturbance from live-bottom features 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 BOEM policy, 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. 
Alternatives Including the Proposed Action 2-15 

Live-bottom (low-relief) 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 BOEM case-by-case review of the seafloor in areas where bottom-disturbing activities are 

planned would prevent most of the potential impacts from oil and gas operations, including accidental oil 

spills and blowouts, on the biota of live-bottom features by increasing the distance of such events from 

the features. Also, note that none of the blocks with live bottoms are included in the area to be offered in 

the CPA proposed action. However, operations that occur in blocks adjacent to live-bottom habitat may 

affect live-bottom features. It would be expected though that the majority of oil would rise to the surface 

and that the most heavily oiled sediments would likely be deposited before reaching the live-bottom 

features. 

The limited relief of many live-bottom features 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. Also, features in water shallower than 

10 m (33 ft) would be located 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 BOEM site-specific review of seafloor habitats during the review of 

project plans would limit the potential impact of any activities that may approach low-relief habitats (such 

as pipeline right-of-ways) because BOEM policy 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 that would be easily removed by the organism. 

Many of these organisms are located within the influence of the Mississippi River plume and are more 

tolerant of turbidity and sedimentation, allowing them to withstand a degree of these impacts. 

The BOEM site review would assist in preventing most of the potential impacts on live-bottom 

communities from blowouts, surface, and subsurface oil spills and the associated effects because BOEM 

policy requires that bottom-disturbing activity be distanced from live-bottom features. In addition, 

because no live-bottom (low-relief) blocks are included in the proposed action, the live-bottom features 

are distanced from oil-producing activity. 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, if applied, 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 through avoidance, by requiring 

individual activities to be located at specified distances from the feature or zone. 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 BOEM acknowledges that 
2-16 Central Planning Area Supplemental EIS 

impacts from routine activities without the proposed Topographic Features Stipulation could be greater 

for those topographic features that may have been already impacted by the DWH event. 

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. Construction 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 exclusion zones would 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 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). 

The proposed Topographic Features Stipulation, if applied, 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. It 

would be expected that the majority of oil would rise to the surface and that the most heavily oiled 

sediments would likely be deposited before reaching 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 more susceptible to 

adverse 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, 

along with oil-spill-response activities such as the use of dispersants. 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; 
Alternatives Including the Proposed Action 2-17 

Wyers et al., 1986). In most cases, recovery from disturbances would take 10 years or more (Fucik et al., 

1984; Rogers and Garrison, 2001). The use of dispersants near or above protected features, such as the 

topographic features, could result in impacts to the features because dispersants allow floating oil to mix 

with water. Nevertheless, it is up to the sole discretion of the Federal On-Scene Coordinator on whether 

dispersants will be used near topographic features during an accidental event. 

Disturbances, including oil spills and blowouts, could 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. Accidental events related to the proposed 

action could cause long-term (10 years or more) adverse impacts to the biota of the topographic 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 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. 

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]). 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 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 it 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. 

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. Without mitigation measures, 

these activities could result in smothering by the suspension of sediments or the crushing of organisms 

residing in these communities. 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. Information included in required hazards surveys for oil and gas activities depicts areas 

that could potentially harbor chemosynthetic communities. This allows BOEM to require avoidance of 

any areas that are conducive to chemosynthetic growth. 
2-18 Central Planning Area Supplemental EIS 

The BOEM 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. 

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 

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. The 2,000-ft (610-m) 

avoidance required would protect sensitive communities from heavy sedimentation, with only light 

sediment components able to reach the communities in small quantities. 

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 or if oil is ejected into 

deep water under high pressure, resulting in vigorous turbulence and the formation of micro-droplets, oil 

would mix into the water column, would be carried by underwater currents, and would eventually contact 

the seafloor where it may impact patches of chemosynthetic community habitat in its path. Any 

epibenthic organisms that protrude up into the water column would be particularly susceptible to damage 

from a passing oil plume (if the oil plume is at the seafloor). These potential impacts would be localized 

because of the directional movement of oil plumes by the water currents and because the sensitive 

habitats have a scattered, patchy distribution. 

The BOEM 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 (Appendix B) 

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. If such an event were to 

occur, it could take hundreds of years to reestablish the chemosynthetic community in that location. 

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. 

Information included in required hazards surveys for oil and gas activities depicts areas that could 

potentially harbor nonchemosynthetic communities. This allows BOEM to require avoidance of any 

areas that are conducive to the growth of sensitive hard-bottom habitats. Impacts to hard-bottom 

communities are expected to be avoided as a consequence of the application of 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 communities are generally avoided in exploration and development planning. 
Alternatives Including the Proposed Action 2-19 

Based on the additional information presented above, BOEM 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. 

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 or if oil is ejected into deep water under high pressure, resulting in 

vigorous turbulence and the formation of micro-droplets, oil would mix into the water column, would be 

carried by underwater currents, and would eventually contact the seafloor where it may impact patches of 

sensitive deepwater community habitat in its path. Any epibenthic organisms that protrude up into the 

water column would be particularly susceptible to damage from a passing oil plume (if the oil plume is at 

the seafloor). 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 BOEM 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 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. Periods as long as hundreds of years are required to reestablish a 

nonchemosynthetic seep community once it has disappeared (depending on the community type), 

although it may reappear relatively quickly once the process begins. 

Marine Mammals (Chapter 4.1.1.11) 

The BOEM has reexamined the analysis for marine mammals presented in the Multisale EIS, the 

2009-2012 Supplemental EIS, and the cited new information within the discussions above. Based on this 

evaluation, our analysis of the effects from routine activities on marine mammals remains unchanged 

from what was concluded in the Multisale EIS and the 2009-2012 Supplemental EIS. Effects from 

routine activities from 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, if they were to occur, could result from chance collisions with OCS service vessels or the 

ingestion of any accidentally released plastic materials. However, there have been no reports of mortality 

from these occurrences in the GOM, and vessel strikes are considered unlikely (also see USDOC, NMFS, 

2007b). Instead, most routine OCS activities are expected to have sublethal effects, such as behavioral 

effects, that are not expected to rise to the level of significance to the populations. 

Although there will always be some level of incomplete information relevant to the effects from 

routine activities under this proposed action on marine mammals, BOEM does not believe it is essential to 

a reasoned choice among alternatives. There is credible scientific information available, and applied 

using acceptable scientific methodologies, to support the conclusion that any realized impacts would be 

sublethal in nature and not in themselves be expected to rise to the level of reasonably foreseeable 

significant adverse (population level) effects. As noted in Chapter 4.1.1.11.1, however, BOEM cannot 

rule out that incomplete or unavailable information on the effects of the unusual mortality event (UME) or 
2-20 Central Planning Area Supplemental EIS 

the DWH event on certain species may be essential to a reasoned choice among alternatives (and that this 

information cannot be obtained within the timeframe of this Supplemental EIS). As such, BOEM 

acknowledges that impacts from routine activities could be greater on individuals or populations already 

impacted by the DWH event or UME. Nevertheless, routine activities are ongoing in the proposed action 

area (CPA) as a result of existing leases and related activities (there are 4,503 active leases in the CPA as 

of November 2011). Within the CPA, there is a long-standing and well-developed OCS Program (more 

than 50 years); there are no previous data to suggest that routine activities from the pre-existing OCS 

Program were significantly impacting marine mammal populations. 

The analysis of the effects from accidental spills (noncatastrophic) on marine mammals remains 

unchanged from what was concluded in the Multisale EIS and the 2009-2012 Supplemental EIS. Impacts 

on marine mammals from smaller accidental events are likely to affect individual marine mammals in the 

spill area, as described above and within the Multisale EIS and the 2009-2012 Supplemental EIS, but are 

unlikely to rise to the level of population effects (or significance) given the likely size and scope of such 

spills. Further, the potential remains for smaller accidental spills to occur in the proposed action area, 

regardless of any alternative selected under this Supplemental EIS, given there are 4,503 active leases 

already in this area with either ongoing or the potential for exploration, drilling, and production activities. 

For low-probability catastrophic spills, the Multisale EIS, 2009-2012 Supplemental EIS, and 

Appendix B of this Supplemental EIS conclude that there is a potential for a low-probability catastrophic 

event to result in significant, population level effects on affected marine mammal species. The BOEM 

continues to concur with the conclusions from these analyses. 

The BOEM concludes that there is incomplete or unavailable information that may be relevant to 

reasonably foreseeable significant adverse impacts to marine mammals from noncatastrophic 

spills/accidental events. For example, there is incomplete information on the impacts to marine mammal 

populations from the DWH event and whether individuals or populations may be susceptible to greater 

impacts in light of the UME or DWH event. Relevant data on the status of and impacts to marine 

mammal populations from the UME and DWH event may take years to acquire and analyze, and impacts 

from the DWH event may be difficult or impossible to discern from other factors. For example, 20 years 

after the Exxon Valdez incident, investigations are still identifying data regarding impacts to killer whales. 

The NMFS has jurisdiction for the investigation of marine mammal strandings and, to date, has only 

released raw data on the number of strandings. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in this Supplemental EIS, regardless of the cost or resources 

needed. In the absence of this information, BOEM subject-matter experts have used what scientifically 

credible information is available and applied using accepted scientific methodologies. The BOEM cannot 

rule out that unavailable or incomplete information on accidental impacts may be essential to a reasoned 

choice among the alternatives in light of the UME and DWH event. Activities that could result in an 

accidental spill in the CPA would be ongoing whether or not the lease sale under the proposed action of 

this Supplemental EIS occurred. As of November 2011, there are 4,503 active leases in the CPA that are 

engaged, or have the potential to be engaged, in drilling and/or production activities that could result in an 

accidental spill. 

Sea Turtles (Chapter 4.1.1.12) 

In this Supplemental EIS, BOEM 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. Because of the mitigations (e.g., BOEM proposed compliance with NTL’s) 

described in the above analysis, routine activities (e.g., operational discharges, noise, vessel traffic, and 

marine debris) related to the CPA proposed action 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 

could occur from chance collisions with OCS service vessels or ingestion of accidentally released plastic 

materials from OCS vessels and facilities. However, there have been no reports to date on such 

incidences. Most routine OCS energy-related activities are then expected to have sublethal effects that 

are not expected to rise to the level of significance. 

Although there will always be some level of incomplete information relevant to the effects from 

routine activities under this proposed action on sea turtles, BOEM does not believe it is essential to a 

reasoned choice among alternatives. There is credible scientific information available, and applied using 
Alternatives Including the Proposed Action 2-21 

acceptable scientific methodologies, to support the conclusion that any realized impacts would be 

sublethal in nature and not in themselves be expected to rise to the level of reasonably foreseeable 

significant adverse (population level) effects. As noted in Chapter 4.1.1.12.1, however, BOEM cannot 

rule out that incomplete or unavailable information on effects of the increased stranding event or DWH 

event on sea turtles may be essential to a reasoned choice among alternatives (and that this information 

cannot be obtained within the timeframe of this Supplemental EIS). As such, BOEM acknowledges that 

impacts from routine activities could be greater on individuals or populations already impacted by the 

DWH event or increased stranding event. Nevertheless, routine activities are ongoing in the proposed 

action area (CPA) as a result of existing leases and related activities (as of November 2011, there are 

4,503 active leases in the CPA). Within the CPA, there is a long-standing and well-developed OCS 

Program (more than 50 years); there are no previous data to suggest that routine activities from the preexisting OCS Program were significantly impacting sea turtles. 

The analysis of the effects from accidental spills (noncatastrophic) on sea turtles remains unchanged 

from what was concluded in the Multisale EIS and the 2009-2012 Supplemental EIS. Impacts on sea 

turtles from smaller accidental events are likely to affect individual sea turtles in the spill area, as 

described above and within the Multisale EIS and the 2009-2012 Supplemental EIS, but they are unlikely 

to rise to the level of population effects (or significance) given the size and scope of such spills. Further, 

the potential remains for smaller accidental spills to occur in the proposed action area, regardless of any 

alternative selected under this Supplemental EIS, given there are 4,503 active leases already in this area 

with either ongoing or the potential for exploration, drilling, and production activities. 

For low-probability catastrophic spills, the Multisale EIS, the 2009-2012 Supplemental EIS, and 

Appendix B of this Supplemental EIS conclude that there is a potential for a low-probability catastrophic 

event to result in significant, population-level effects on affected sea turtle species. The BOEM continues 

to concur with the conclusions from these analyses. 

The BOEM concludes that there is incomplete or unavailable information that may be relevant to 

reasonably foreseeable significant adverse impacts to sea turtles from noncatastrophic spills/accidental 

events. For example, there is incomplete information on the impacts to sea turtle populations from the 

DWH event and whether individuals or populations may be susceptible to greater impacts in light of the 

increased stranding event or DWH event. Relevant data on the status of and impacts to sea turtle 

populations from the increased stranding event and DWH event may take years to acquire and analyze, 

and impacts from the DWH event may be difficult or impossible to discern from other factors. The 

NMFS to date has only released raw data on the number of strandings, and BOEM does not have the 

ability to investigate these strandings independently. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in this Supplemental EIS, regardless of the cost or resources 

needed. In the absence of this information, BOEM subject-matter experts have used what scientifically 

credible information that is available and applied using accepted scientific methodologies. The BOEM 

cannot rule out that unavailable or incomplete information on accidental impacts may be essential to a 

reasoned choice among the alternatives in light of the increased stranding event and DWH event. 

Activities that could result in an accidental spill in the CPA would be ongoing whether or not the lease 

sale under the proposed action of this Supplemental EIS occurred. As of November 2011, there are 4,503 

active leases in the CPA that are engaged, or have the potential to be engaged, in drilling and/or 

production activities that could result in an accidental spill. 

Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice (Chapter 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. 
2-22 Central Planning Area Supplemental EIS 

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 BOEM 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. 

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/threatened coastal and marine birds are expected to be intermittent, of 

small spatial scale, and short term. The ability to fly will often result in avoidance and quick 

reestablishment. These intermittent effects include behavioral effects, exposure to or intake of OCSrelated 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. 

Impacts from pipeline and navigation canals to coastal habitats will occur over the long term and may 

ultimately displace species. 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. 

Although there will always be some level of incomplete information on the effects from routine 

activities under this proposed action on birds, there is credible scientific information, applied using 

acceptable scientific methodologies, to support the conclusion that any realized impacts would be 

generally sublethal in nature and not in themselves rise to the level of reasonably foreseeable significant 

adverse (population level) effects. With the exception of piping plovers, wood storks, whooping cranes, 

and Mississippi sandhill cranes (which, due to their habitat location, are unlikely to have been impacted 

by the DWH event or to be impacted by routine activities), BOEM cannot definitively determine that the 

incomplete or unavailable information will not be essential for certain individual species or populations. 

This information is currently unavailable, is being developed through the NRDA process (which takes 

years), and there is no timeline for this information becoming available and certainly not within the 

timeline of this Supplemental EIS. Nevertheless, it is not expected that other species will have been 

impacted by the DWH event to such an extent that the conclusions on impacts from routine activities will 

change. Routine activities will be ongoing in the proposed action area (CPA) as a result of existing leases 

and related activities. (In the CPA, there are 4,503 active leases as of November 2011.) Within the CPA, 

there is a long-standing and well-developed OCS Program (more than 50 years); there are no data to 

suggest that routine activities from the pre-existing OCS Program are significantly impacting coastal and 

marine bird populations. 

Oil spills may have serious direct and indirect impacts to coastal and marine bird health and habitat 

for feeding, roosting, sleeping, and nesting. In shallow water, such spills would have impacts on birds 

directly through contamination of skin and plumage, interfering with their ability to maintain body 

temperature, buoyancy, waterproofing, and the ability to fly. Impacts on individuals are much more 

serious for populations of endangered or threatened species (such as the piping plover and the whooping 

crane) than for nonlisted species because low populations of listed species may be more likely to face 
Alternatives Including the Proposed Action 2-23 

extinction because of the disappearance of a relatively small number of individuals. The lighter PAH’s 

have the greatest impacts on birds because of their persistence and high concentration. They are harmful 

to cell membranes. 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. Exposure to 

oil in the water column was modeled to be minor. When oil gets into vegetated or unvegetated sediment, 

it may remain in its unweathered toxic state indefinitely. However, oil weathering as it travels to the 

coast ameliorates toxicity at the shoreline. Small amounts of oil can affect the health of birds. Birds may 

have reduced reproductive effort, causing temporary declines in population abundance. 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. With properly trained 

and supervised personnel, impacts of oil-spill cleanup from the proposed action are also expected to be 

negligible. Although a low-probability catastrophic event like the DWH event remains a remote 

possibility, such a large-scale effort could increase the potential impacts from oil-spill cleanup 

(Appendix B). 

Among accidental events related to the proposed action, oil spills have the greatest potential to impact 

coastal and marine bird populations. Nevertheless, oil-spill 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 

(combined probabilities are always <15%), not rising to the level of population impacts. An exception 

would be the piping plover, where impact on a small number of birds could considerably reduce a 

population. The piping plover is in low abundance but its wintering habitat is plentiful in the Gulf of 

Mexico. An oil spill would likely only contact a small portion of this wintering habitat in the GOM; thus, 

the greatest threats to the recovery of the piping plover remain at its breeding habitat in the Great Plains 

and Great Lakes and not with the OCS Program or this proposed action. 

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 

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 the vessels are 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. 

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 from an offshore spill coming into 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. Even in a catastrophic spill the proximity, 

type oil, weather conditions as well as the amount and location (distance off shore and water depth) of the 

dispersant treatment may contribute to the severity of the spill impact to the sturgeon and its habitat. 

Currently reduced toxicity of PAH in both the nearshore and offshore water and sediments have been 

reported in the OSAT report (OSAT, 2010). These conclusions, coupled with the findings of the OSAT-2 

report noting large reductions in PAH toxicity in the beach sediments, as well as the continual 
2-24 Central Planning Area Supplemental EIS 

degradation of PAH in the tidal zone sediment (OSAT-2, 2011), would indicate the toxicity levels are not 

likely to interfere with Gulf sturgeon or their critical habitat. In addition, the dispersant emulsified the oil, 

which encouraged evaporation, dilution, and biodegradation of toxic components including PAH’s. 

Contamination was limited to within 3 km (~2 mi) of the wellhead, well away from the Gulf sturgeon 

critical habitat (OSAT, 2010). The dispersed oil was rendered into a cloud-like mass within the water 

column, which was readily available for biodegradation. 

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. 

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 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 BOEM 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 because impacts to the habitat would generally be temporary; fish tend to avoid areas of impact 

(thus reducing mortality effects), and most fish species are prolific reproducers. Recovery from the loss 

of wetlands habitat would probably not occur, but it would likely result in conversion of the lost wetland 

habitats into open water or mudflats, which may qualify as other forms of EFH. 

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 expected to cause a nondetectable 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 that would not deleteriously affect fish resources or EFH. This is because of 

regulations, mitigations, and practices that reduce the undesirable effects on coastal habitats from 

dredging and other construction activities. 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. 

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 
Alternatives Including the Proposed Action 2-25 

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 (Chapter 4.4.10 of the Multisale EIS). 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, where fish populations are most concentrated, and this probability is 

generally low. Also, much of the coastal northern Gulf of Mexico is a moderate- to high-energy 

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. 

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 the most common spill events would be small in 

scale and localized; therefore, they would affect generally only a small potion of fish 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. Although there remains incomplete or unavailable information on the impacts of the 

DWH event on fish resources and EFH, the Bureau of Ocean Energy Management has determined that it 

is impossible to obtain this information, regardless of cost and within the timeframe of this NEPA 

analysis. This information is being developed through the NRDA process, data is still incoming and has 

not been made publicly available, and it is expected to be years before the information is available. In 

addition, as described in Chapter 4.1.1.16.1, where this incomplete information is relevant to reasonably 

foreseeable impacts, what scientifically credible information is available was used in its stead and applied 

using accepted scientific methodologies. Nevertheless, BOEM believes that this information is not 

essential to a reasoned choice among alternatives with regard to an accidental event analysis. The likely 

size of an accidental event resulting from the CPA proposed action would be small and unlikely to impact 

coastal and estuarine habitats where juvenile and larval stages of fish resources are found, and adult fish 

tend to avoid adverse water conditions (Wannamaker and Rice, 2000). 

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 significant impacts to commercial fisheries. Operations 

such as production platform emplacement, underwater OCS impediments, and explosive platform 

removal would cause displacement of commercial fishing while operations are ongoing. These 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. 

The BOEM 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, because the most typical events 

are small and of short duration, and because the effects are so localized that fish are typically able to 

avoid the area adversely impacted. 

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 because many fish spend a portion of 
2-26 Central Planning Area Supplemental EIS 

their life cycle there. The probability of an offshore spill impacting these nearshore environments is also 

low, and oil would generally be volatilized or is dispersed by currents in the offshore environment. The 

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. 

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 be offset 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 

remediated. 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 activities in the CPA can cause minor disturbances to recreational resources, 

particularly beaches, through increased levels of noise, debris, and rig visibility. The OCS activities can 

also change the composition of local economies through changes in employment, land-use, and 

recreational demand. A CPA proposed action has the potential to directly and indirectly impact 

recreational resources along the entire Gulf Coast. However, the small scale of the proposed action 

relative to the scale of the existing oil and gas industry suggests 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 because 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 is becoming better understood in the aftermath 

of the spill. 

Archaeological Resources (Chapter 4.1.1.20) 

Historic (Chapter 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, dredging, pipeline project, or decommissioning and site clearance) and a historic site. 
Alternatives Including the Proposed Action 2-27 

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), 30 CFR 550.194(c), and 30 CFR 250.1010(c), lessees are required 

to notify BOEM and/or BSEE 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 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, 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. 

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 

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 and in 

Table 3-5 of this Supplemental EIS, it is not very likely for an oil spill to occur, and it would not be likely 

to 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 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. 

Prehistoric (Chapter 4.1.1.20.2) 

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. 

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 
2-28 Central Planning Area Supplemental EIS 

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. 

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, the effects of the drilling suspension, the changes in Federal requirements for 

drilling safety, and the current pace of permit approvals. The BOEM 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 only 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, official communication, 2011). The BOEM 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 gas 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 BOEM anticipates these changes would become 

apparent over time. Therefore, BOEM recognizes the need to continue monitoring all resources for 

changes that are applicable for land use and infrastructure. From the information described above 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. 

Accidental events associated with the CPA proposed action occur at different levels of severity, based 

in part on the location and size of event. The typical types of accidental events that could affect land use 

and coastal infrastructure include oil spills, vessel collisions, and chemical/drilling fluid spills. These 

may occur anywhere across the spectrum of severity. Typically, accidental events related to OCS 

activities are generally smaller in scale based on historic experience, and they must be distinguished from 

low-probability, high-impact catastrophic events such as the DWH event. Typically, the impact of smallscale oil spills, vessel collisions, and chemical/drilling fluid spills are not likely to last long enough to 

adversely affect overall land use or coastal infrastructure in the analysis area. 

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 (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 regard to land use and infrastructure, the post-DWH event environment remains somewhat dynamic, 

and BOEM 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. 

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 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 
Alternatives Including the Proposed Action 2-29 

population and available labor force, with the exception of some in-migration projected to occur in focal 

areas, such as Port Fourchon. 

Accidental events may cause short-term population movements, but they would not be expected to 

affect demographic characteristics as a whole in the affected area. 

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. 

The CPA proposed action is not expected to have disproportionate high/adverse environmental or 

health effects on minority or low-income people. 

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 
2-30 Central Planning Area Supplemental EIS 

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 be 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 BOEM 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. As such, 

information regarding reasonably foreseeable impacts of the DWH event remains incomplete or 

unavailable at this time. Studies regarding environmental justice concerns in light of the DWH event are 

only in their infancy, and it may be years before data are available and certainly not within the timeframe 

of this NEPA analysis. Although most criteria related to environmental justice may not be essential to a 

reasoned choice among the alternatives, health impacts would generally be essential. Nevertheless, longterm health studies are pending and may not be available for use for several years or longer. Other 

ongoing studies may help to inform issues relating to subsistence and other indigenous reliance on natural 

resources. This information is unavailable and unobtainable at this time, regardless of costs. In its places, 

the subject-matter experts have used credible information that is available and applied using accepted 

socioeconomic methodologies. 

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 populations more than the general 

population, at least in the shorter term. These higher risk groups may lack the appropriate 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 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 

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). 

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 be expected to experience lethal impacts 

during an accidental event as a result of blowouts, surface and subsurface oil spills, and their 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 
Alternatives Including the Proposed Action 2-31 

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. 

Diamondback Terrapins (Chapter 4.1.1.22.2) 

Adverse impacts due to 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 plastics in the ocean are decreasing and 

the devastating effects on offshore and coastal marine life are minimizing. 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 Gulf of Mexico. 

Although there will always be some level of incomplete information on the effects from routine 

activities under this proposed action on diamondback terrapin, there is credible scientific information, 

applied using acceptable scientific methodologies, to support the conclusion that any realized impacts 

from routine activities would be sublethal in nature and not in themselves rise to the level of reasonably 

foreseeable significant adverse (population level) effects. Because completion of the NRDA process may 

be years away, BOEM cannot definitively determine if the information resulting from that process may be 

essential to a reasoned choice among alternatives. Routine activities, however, will be ongoing in the 

CPA as a result of existing leases and related activities. (In the CPA, there are 4,503 active leases as of 

November 2011.) Within the CPA, there is a long-standing and well-developed OCS Program (more than 

50 years); there are no data to suggest that routine activities from the pre-existing OCS Program are 

significantly impacting diamondback terrapin populations. As such, even with this uncertainty, the 

potential impacts from routine activities associated with the proposed action are unlikely to result in 

significant, population-level impacts on diamondback terrapins due to their distance from most offshore 

activities and the limited potential for activities occurring in or near their habitat (0-1 pipeline landfalls 

and other coastal infrastructure, which is subject to permitting and location requirements). Therefore, a 

full understanding of any incomplete or unavailable information on the effects of routine activities is 

likely not essential to make a reasoned choice among the alternatives. 

Impacts on diamondback terrapins from smaller accidental events are likely to affect individual 

diamondback terrapins in the spill area, as described above, but are unlikely to rise to the level of 

population effects (or significance) given the probable size and scope of such spills. Further, the potential 

remains for smaller accidental spills to occur in the proposed action area, regardless of any alternative 

selected under this Supplemental EIS, given there are 4,503 active leases already in this area with either 

ongoing or the potential for exploration, drilling, and production activities. 

The analyses within this Supplemental EIS and in Appendix B conclude that there is a low 

probability for catastrophic spills, and Appendix B concludes that there is a potential for a lowprobability catastrophic event to result in significant, population-level effects on affected diamondback 

terrapin species. The BOEM continues to concur with the conclusions from these analyses. 

The BOEM concludes that there is incomplete or unavailable information that may be relevant to 

reasonably foreseeable significant adverse impacts from noncatastrophic spills/accidental events to 

terrapins that were potentially impacted by the DWH event. For example, there is incomplete information 

on impacts to terrapin populations from the DWH event and whether individuals or populations may be 

susceptible to greater impacts in light of the DWH event. Relevant data on the status of and impacts to 

terrapin populations from the DWH event is being developed through the NRDA process and may take 

years to acquire and analyze, and impacts from the DWH event may be difficult or impossible to discern 

from other factors. No data on terrapins impacted by the DWH event have been released. It is not 

possible for BOEM to obtain this information within the timeline contemplated in this Supplemental EIS, 

regardless of the cost or resources needed. In the absence of this information, BOEM subject-matter 

experts have used what scientifically credible information is available, applied using accepted scientific 

methodologies. Activities that could result in an accidental spill in the CPA would be ongoing whether or 

not the lease sale under the CPA proposed action of this Supplemental EIS occurred. As of November 
2-32 Central Planning Area Supplemental EIS 

2011, there are 4,503 active leases in the CPA that are engaged, or have the potential to be engaged, in 

drilling and/or production activities that could result in an accidental spill. 

For those terrapin populations that may not have been impacted by the DWH event, it is unlikely that 

a future accidental event related to the CPA proposed action would result in significant impacts due to the 

distance of most terrapin habitat from offshore OCS energy-related activities. A low-probability, largescale catastrophic event of the size and type that could reach these habitats is discussed in Appendix B. 

2.3.1.3. Mitigating Measures 

The following eight environmental and military mitigations, referred to as lease stipulations, were 

included for analysis in 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 Bottom (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 

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. 
Alternatives Including the Proposed Action 2-33 

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 it 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, 

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 limits of the United States jurisdiction over the continental shelf (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 
2-34 Central Planning Area Supplemental EIS 

(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, 

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, Alabama, coast (Figure 2-1). The number of blocks that would not be 

offered under Alternative C 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 C would be 

essentially the same as those projected for the proposed action. As a result, 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. 
Alternatives Including the Proposed Action 2-35 

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), BOEM 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 impact-producing 

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 (3.5 mi; 5.6 km) offshore Louisiana, Mississippi, and Alabama; it generally extends seaward to the 

limits of the United States’ jurisdiction over the continental shelf (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, BOEM 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 BOEM 

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 BOEM 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 was prepared because of the potential changes to the 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 since the Multisale EIS or the 

2009-2012 Supplemental EIS. The environmental resources analyzed 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. It is important to note that this 

Supplemental EIS was prepared using the best information that was publicly available at the time this 

document was prepared. 

The BOEM, Gulf of Mexico OCS Region, Resource 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 BOEM 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 
Impact-Producing Factors and Scenario 3-5 

would take place over an 8-year period, beginning within 1 year after the lease sale. Final 

decommissioning and removal activities generally occur from the 15th year to the 40th year. 

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 Tables 3-4 and 3-5 of the 2009-2012 

Supplemental EIS. Because of variation by water depth, exploration and production activity is staggered 

over time, taking on average approximately 2-41⁄2 years after a lease sale before exploration begins and 

31⁄2-8 years before first production (Chapter 3.1.1 of the 2009-2012 Supplemental EIS). 

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, are focused most 

commonly (but not always) on deeper targets, and are collectively authorized under BOEM’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, buried channels and faults, and archaeological resources. Highresolution 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 timelapse, deep-focused, three-dimensional (3-D) surveying, four-dimensional (4-D) 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-dimensional (2-D) or 3-D 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. Ocean-bottom systems may be deployed instead of streamers in shallow 

water, areas of dense infrastructure, or when 4-D seismic is used to aid in reservoir management. This 

methodology utilizes hydrophones placed statically on the seafloor, and the energy source (airgun arrays) 

remains the same as streamer methods and is towed behind a source vessel. 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 3-D 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 3-D seismic surveys. For a typical 

3-D 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). 
3-6 Central Planning Area Supplemental EIS

A 4-D or time-lapse survey is used to monitor reservoir production to optimize the amount of 

hydrocarbon recovered. These surveys consist of a series of 3-D 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 

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 survey 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 environmental impact analysis required with the EP, DOCD, or DPP, 30 CFR 

550.227(b)(6) and 30 CFR 550.261(b)(6) require the applicant to submit archaeological information. In 

certain circumstances, the BOEM Regional Director may require the preparation of an archaeological 

report to accompany the EP, DOCD, or DPP under 30 CFR 550.194. The requirements for 

archaeological reports are clarified in NTL 2005-G07, “Archaeological Resource Surveys and Reports.” 

If the archaeological report, where required, 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 
Impact-Producing Factors and Scenario 3-7 

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 BOEM Regional Supervisor, Office of 

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. Based on an amalgam of historical trends in G&G 

permitting and industry input for the Gulf of Mexico G&G Programmatic EIS (USDOC, NMFS and 

USDOI, BOEM, in preparation), BOEM projects that the CPA proposed action would result in 

1,500-2,500 mi (2,400-4,000 km) of 2-D deep seismic and 1,500-2,000 OCS blocks surveyed annually by 

3-D deep seismic. For postlease seismic surveys, information obtained from high-resolution seismic 

contractors operating in the Gulf of Mexico projects the CPA proposed action would result in about 

3-6 VSP operations and about 3,000-4,000 mi (4,828-6,437 km) of near-surface and shallow-penetration 

seismic during the life of the proposed action.

OCS Program Scenario: Seismic surveys in the CPA 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, BOEM 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 2-D deep seismic, and 2,500-3,000 OCS blocks surveyed by 3-D 

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 2-D deep seismic, and 1,500-2,500 OCS blocks surveyed by 3-D 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 mobile offshore drilling units 

(MODU’s); e.g., jack-up rigs, semisubmersible rigs, submersible, platform rigs, or drillships. NonMODU 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. 
3-8 Central Planning Area Supplemental EIS

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 BSEE regulations require that operators conduct their offshore operations 

in a safe manner. Subpart D of BSEE’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. 

Exploration Plans 

The regulation at 30 CFR 550 Subpart B specifies the requirements for the exploration plans (EP’s) 

that operators must submit to BOEM for approval prior to deploying an exploration program. An EP 

must be submitted to BOEM 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 550.211 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 in NTL 2009-G27, “Submitting Exploration Plans and Development 

Operations Coordination Documents.” The requirements for shallow hazard surveys and their reports are 

clarified in NTL 2008-G05, “Shallow Hazards Program.” 

As part of the environment impact analysis required with EP, DOCD, or DPP, 30 CFR 550.227(b)(6) 

and 30 CFR 550.261(b)(6) require the applicant to submit archaeological information. In certain 

circumstances, BOEM’s Regional Director may require the preparation of an archaeological report to 

accompany the EP, DOCD, or DPP, under 30 CFR 550.194. The requirements for archaeological reports 

are clarified in NTL 2005-G07, “Archaeological Resource Surveys and Reports.” If the archaeological 

report, where required, 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 BOEM’s Regional Supervisor, Office of 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 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 BOEM 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 for the CPA over the 40-year period remains 

the same as the originally forecasted program scenario in the Multisale EIS. The BOEM 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 waterdepth ranges and deeper (>200 m; 656 ft). 
Impact-Producing Factors and Scenario 3-9 

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 

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’s and BSEE’s 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 BSEE. The DWOP provides BSEE 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 BSEE 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 BOEM estimates that 87-89 percent of development wells would become 

producing wells. 

CPA Proposed Action Scenario: The BOEM 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 water-
3-10 Central Planning Area Supplemental EIS

depth 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 for the CPA over the 40-year period remains 

the same as the originally forecasted program scenario in the Multisale EIS. The BOEM 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. 

3.1.1.2.2. 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). 
Impact-Producing Factors and Scenario 3-11 

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 

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 loss of well 

control 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 March 2011. 

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. 
3-12 Central Planning Area Supplemental EIS

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 

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 for the CPA over the 40-year period 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 OCS 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 over the 40-year period (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 
Impact-Producing Factors and Scenario 3-13 

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, BOEM 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 

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 for the CPA over the 40-year period 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. With the exception of the DWH event, which 

released 4.9 million bbl of oil in 2010, the estimates and contributions for major sources of oil inputs 

remain as described in Tables 4-11 and 4-12 of the Multisale EIS. 

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 typically provide the largest annual 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 20 percent 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). 
3-14 Central Planning Area Supplemental EIS

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. 

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. 

At the national level, tankers and tank barges were responsible for 45 percent of the reported total 

spillage in the years 1969 through 2008 (U.S. Dept. of Homeland Security, CG, 2010a). The type of oil 

reported spilled nationally was as follows: 47 percent crude oil; 17 percent heavy fuel oil; 16 percent 

intermediate fuel oil; and 9 percent gasoline. Other reported 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 most common reported spill 

source of oil to the coastal waters of the western GOM. Spills from tankers are the most common 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 BOEM 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. This Supplemental EIS and the Multisale EIS and the 

2009-2012 Supplemental EIS, from which this Supplemental EIS tiers, reference Anderson and Labelle 

(2000) throughout these documents. Anderson and Labelle (2000) have been updated by DOI’s draft 

report, Update of Oil Spill Occurrence Rates for Offshore Oil Spills (USDOI, BOEMRE, 2011a). 

Platform and pipeline spill rates and likely spill sizes published in the Multisale EIS have thus become 

outdated. Readers should note that Tables 4-13, 4-14, 4-16, and 4-35 of the Multisale EIS and Table 3-6 

of the 2009-2012 Supplemental EIS use the 2000 spill rates and sizes rather than the 2011 spill rates and 

sizes. 

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). The reader should bear in 

mind that these are reported spills, not necessarily all spills that occur. 

Table 3-4 indicates that spills caused by hurricane-damaged pipelines result in the vast majority of 

total oil spilled in the GOM. The BSEE 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. 
Impact-Producing Factors and Scenario 3-15 

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. 

 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 
3-16 Central Planning Area Supplemental EIS

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 likely given historical data, 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 BSEE. 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 BOEM’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. 

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, where a spill size of 4,200 bbl is assumed. Smaller spills occur 

more often. 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 upon USCG data collected 

from 1969 to 2001, BOEM performed an analysis 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 upon 

USCG data collected from 1969 to 2008, BOEM performed an analysis on all 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. 
Impact-Producing Factors and Scenario 3-17 

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 number of pipeline landfalls 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 BSEE and DOT share responsibility for pipeline 

regulation on the OCS in the transition between Federal and State waters. The BSEE 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. At present, all gas production and >99 percent of oil production from the offshore GOM is 

transported to shore by pipeline. 

The BSEE’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 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 BSEE 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 BOEM 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 BSEE 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 BSEE determines that the pipeline may constitute a hazard to other uses of 

the OCS in the GOM. The BSEE requires 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 
3-18 Central Planning Area Supplemental EIS

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 BOEM 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 for the CPA over the 40-year period 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 

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 BOEM 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 for the CPA over the 40-year period 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 March 2011. Tankering related to FPSO systems 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 BOEM projects 0-1 FPSO systems could result from the CPA proposed action. For an FPSO 
Impact-Producing Factors and Scenario 3-19 

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 upon BOEM 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 

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 for the CPA over the 40-year period 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). 
3-20 Central Planning Area Supplemental EIS

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 for the CPA over the 40-year period 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 CWA requires that all discharges of pollutants to surface waters be authorized by a permit issued 

under the NPDES program. The USEPA, under Section 402 of the CWA, issues individual and general 

NPDES permits to regulate all waste streams generated from offshore oil and gas activities. The permits 

are issued regionally. Each USEPA Region has promulgated general permits for discharges that 

incorporate the 1993 and 2001 effluent limitations guidelines as a minimum. The current Region 6 

general permit (GMG290000) was issued on June 7, 2007, and expires September 30, 2012 (USEPA, 

2007a). This permit is for the western portion of the Gulf of Mexico OCS. The NPDES general permit 

for existing and new source discharges in the eastern portion of the Gulf of Mexico OCS (GEG460000) 

was issued on March 15, 2010, and expires on March 31, 2015. This permit applies to operators of leases 

seaward of the 200-m (656-ft) water depth for offshore Alabama and Florida in the EPA and for offshore 

Mississippi and Alabama in the Mobile and Viosca Knoll lease areas in the CPA. 

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. Figure 3-3 shows the 

areas of the GOM where BOEM and USEPA have jurisdiction for air emissions. The area of the CPA 

proposed action is under BOEM’s jurisdiction for air emissions. 

In accordance with BOEM’s air quality regulations, BOEM 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 the U.S. Environmental 
Impact-Producing Factors and Scenario 3-21 

Protection Agency’s NPDES permit requirements that include limits on trace metal concentrations, free 

oil, and toxicity. The USEPA regulates the NPDES permit program in the CPA. 

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. The oil 

wells in the OCS waters off the State of Louisiana generated greater volumes of produced water than the 

other CPA states. 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 

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, 
3-22 Central Planning Area Supplemental EIS

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 

supplies, equipment, and personnel; therefore, drilling operations generate more solid trash than 

production operations. Chapter 1.3 of the Multisale EIS describes laws and regulations, including the 

Marine Plastic Pollution Research and Control Act and the Marine Debris Research, Prevention and 

Reduction Act, which are related to collecting, processing, storing, and discharging garbage generated by 

oil and gas operators. 

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) 
Impact-Producing Factors and Scenario 3-23 

air quality jurisdiction for OCS operations west of 87.5o W longitude in the GOM. The area of the CPA 

proposed action is under BOEM’s jurisdiction for air emissions. 

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. 

Certain air pollutants subject to the NAAQS 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 BSEE regulations provide for some limited volume, short duration flaring or venting of oil 

and natural gas upon approval by BSEE (2-14 days, typically). Through 30 CFR 250.1162, BSEE 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 

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 BSEE 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 
3-24 Central Planning Area Supplemental EIS

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 BOEM regulations (30 CFR 550.214 and 30 CFR 

550.244); 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. 

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 BOEM. 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. 
Impact-Producing Factors and Scenario 3-25 

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 BSEE 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 BSEE will 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 BSEE’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 stormdamaged 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 or even on their financial 

viability to operate on the OCS. 

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. 

As per 30 CFR 250.1725 (with guidance from NTL 2010-G05), 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-
3-26 Central Planning Area Supplemental EIS

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 

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, 

with the subsequent public comment period ending on 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 BSEE requires 

site clearance over the assumed areal extent over which debris will fall. It is assumed that lost debris will 
Impact-Producing Factors and Scenario 3-27 

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 BSEE 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 BSEE. 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 quick-disconnect 

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 for the CPA over the 40-year period 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 

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 BOEM has reexamined the scenario analysis presented in the Multisale EIS and in the 2009-2012 

Supplemental EIS based on new information available since those documents were completed and 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. Chapter 4.1 addresses incomplete or 

unavailable information, including that related to or as a result of the DWH event. The presence of 

coastal infrastructure is not subject to rapid fluctuations. Infrastructure projections reflect long-term 

industry trends. Changes to these trends cannot be determined from the current amount of post-DWH 

data that are available, and more complete data could be years away. While changes (if any) to the 

current scenario analysis due to the DWH event and its aftermath are not expected, BOEM will continue 
3-28 Central Planning Area Supplemental EIS

to collect new data and to monitor changes in infrastructure demands in order to support scenario 

projections that reflect current and future industry conditions. 

According to the scenario analysis in Chapter 4.1.2.1.4.2 of the Multisale EIS and in Chapter 3.1.2.2 

of 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 because, while many of the 

existing gas processing facilities along the coast were upgraded in the aftermath of Hurricanes Katrina 

and Rita, most of those upgrades were limited to the capacity utilization realities of the current operating 

environment that has continued to see decreased gas production on both the shelf and the slope. Many 

existing gas processing facilities are already around 20 years old, if not older, and these are typically 

long-lived assets, and they can be retired. The current scenario assumes that at least one of these major 

facilities will retire and likely need to be replaced in 40 years. As described in Chapter 4.1.2.1.4.1 of the 

Multisale EIS, no new refineries are expected to be constructed as a result of the CPA proposed action. 

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 effects of the drilling suspension, changes in Federal requirements for drilling safety, 

and the current pace in the permit approval process have depressed the demand for gas processing 

facilities and pipeline landfalls. Given this uncertain environment post-DWH, the application of the 

Multisale EIS scenario to the CPA proposed action remains very conservative; that is, 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, official communication, 2011). 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 solidwaste 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 the current pace of activity will continue or how it might 

affect later years. Following the DWH event, activity levels have decreased, and it is unclear how long it 

will take for activity to return to pre-DWH levels. As such, this scenario continues to consider a new 

waste facility unlikely, but possible. 

The source of the majority of the information on coastal infrastructure and activities presented in the 

Multisale EIS is this Agency 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 

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 BOEM. The 

ports of Fourchon, Cameron, Venice, and Morgan City, Louisiana, are the primary service bases for GOM 
Impact-Producing Factors and Scenario 3-29 

mobile rigs. Major platform service bases in the CPA are Cameron, Fourchon, Intracoastal City, Morgan 

City, and Venice, Louisiana; Pascagoula, Mississippi; and Theodore, Alabama. 

Exploration and development plans received by BOEM 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), 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 

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 
3-30 Central Planning Area Supplemental EIS

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 in the CPA. 

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 July 1, 2011, there were 94 OCSrelated gas processing plants in the BOEM-identified 13 EIA’s along the Gulf Coast (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, official communication, 2011). 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, official communication, 2011). 

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, official communication, 2011). 

OCS Program Scenario: Expectations for new gas processing facilities being built during the period 

2007-2046 as a direct result of the OCS Program in the CPA are dependent on long-term market trends 

that are not easily predicable over the next 40 years. Existing facilities will experience equipment switchouts or upgrades during this time. 

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 
Impact-Producing Factors and Scenario 3-31 

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 (Chapter 4.1.2.1.7 of the Multisale EIS). Therefore, 

BOEM 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 would likely be because there are no existing pipelines reasonably close and it is more cost 

effective to construct a pipeline to shore; although it is highly unlikely for an operator to choose this 

contingency (Dismukes, official communication, 2011). 

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, official 

communication, 2011). 

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 in the CPA. 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 

existing facilities. However, it is now unclear whether this will remain true; therefore, more research is 

needed (Dismukes, official communication, 2011). Due to the current pace of permitting and 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, BOEM cannot predict how 

long this pace 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, BOEM 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. 
3-32 Central Planning Area Supplemental EIS

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 in the 

CPA. 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, official communication, 2011). 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 potential 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 

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: 
Impact-Producing Factors and Scenario 3-33 

 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) 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). 

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; and USDOI, BOEMRE, 2011a). In general 

terms, coastal waters adjacent to the CPA are expected to be impacted by many frequent small spills 

(≤1 bbl); few, infrequent, moderately-sized 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. 

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. The BOEM has not 

performed this validation because USCG records do not attribute a spill back to a BOEM lease sale. 

When spills are reported to USCG, the location of the spill, the type of vessel, and the volume and the 

material spilled is identified. 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 
3-34 Central Planning Area Supplemental EIS

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. 

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) was recently updated by DOI’s draft report, Update of Oil Spill Occurrence Rates for 

Offshore Oil Spills (USDOI, BOEMRE, 2011a), which provides 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. 

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) (1.13 as per DOI’s draft report [USDOI, BOEMRE, 2011a]) 

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, during 

1996-2010, it is 2,200 bbl. 

Estimates of Spill Numbers 

As shown on Table 3-5, the mean number of spills estimated for the CPA proposed action is 

<1-1 spill 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 

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, which is 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 BOEM 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 
Impact-Producing Factors and Scenario 3-35 

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 BOEM 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. 

Summary of the Catastrophic Spill OSRA Run 

After the DWH event, BOEM 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. Model runs were conducted to track oil-spill trajectories for 90 days in order to simulate a longduration spill from a given point. 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 BOEM). 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; 
3-36 Central Planning Area Supplemental EIS

 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. 

These modeling results are based on a special OSRA run, which was designed to estimate the impacts 

of a possible future catastrophic or high-volume, long-duration oil spill. The unique methodology used 

for launch point selection is further discussed in Appendix C, along with a greater explanation of the 

catastrophic spill OSRA run. 

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 to1 for 

the CPA proposed action. In the spill size range of >50-499.9 bbl, 5-10 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. 

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 
Impact-Producing Factors and Scenario 3-37 

BOEM 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 reported 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 reported 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, 

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 for the CPA over the 40-year period 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 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 

BOEM’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 it presents 

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. BOEM and BSEE Spill-Response Requirements and Initiatives 

As a result of the Oil Pollution Act of 1990, BOEM and BSEE are tasked with a number of oil-spillresponse duties and planning requirements. 
3-38 Central Planning Area Supplemental EIS

According to BSEE’s regulations at 30 CFR 250 and 254, BSEE implements these requirements as 

follows: 

 requires immediate notification for spills >1 bbl—all spills require notification to 

USCG and BSEE 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; 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. The spill-response-related NTL 2010-N10 and the 

December 13, 2010, guidance document issued by BOEMRE fall under the responsibility of BSEE. 

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. 
Impact-Producing Factors and Scenario 3-39 

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 

 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, BSEE will 

examine the Mudline Shut-in Pressure for the proposed well. The BSEE will also evaluate factors such as 

debris removal from the site. 

According to BOEM’s regulations at 30 CFR 553, BOEM requires industry to show financial 

responsibility to respond to possible spills. The information requirements in NTL 2010-N10, which was 

issued by BOEMRE, fall under the responsibility of BOEM. 

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 550.213(g) and 550.243(h); (2) a description of their assumptions and calculations used in 

determining the volume of the worst-case discharge required by 30 CFR 550.219(a)(2)(iv) (for EP’s) or 

30 CFR 550.250(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 BOEM will begin reviewing to ensure that the measures are adequate to 

promptly respond to a blowout or other loss of well control. 

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 
3-40 Central Planning Area Supplemental EIS

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 area 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). 

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 

Spring 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, 2010). 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. The MWCC interim 

capability was available on February 17, 2011. The MWCC’s initial response system includes a subsea 

capping stack with the ability to shut-in flow or to flow the oil via flexible pipes and risers to surface 

vessels. This interim system can operate in water depths up to 10,000 ft (2,438 m) and has storage and 

processing capacity for up to 60,000 bbl/day of liquids (MWCC, 2011). 

Another option for source control and containment is through the use of the equipment contracted by 

another nonprofit organization, Helix Well Containment Group (HWCG) (Driver, 2010). The HWCG 

initiative involves more than 24 smaller energy companies. The HWCG has contracted the equipment 

that it found useful in the DWH response and, beginning January 1, 2011, has offered it to oil and gas 

producers for use. This system focuses on the utilization of the Helix Producer I and the Q4000 vessels. 

Each of these vessels played a role in the DWH response and is continually working in the Gulf. The 

HWCG system has the ability to fully operate in up to 10,000 ft (3,048 m) of water and has intervention 

equipment to cap and contain a well with the mechanical integrity to be shut-in. The HWCG system also 

has the ability to capture and process 55,000 bbl of oil per day (Helix Well Containment Group, 2011). 

In addition, industry has a multitude of vendors available within the GOM region that can provide the 

services and supplies necessary for debris removal capability, dispersant injection capability, and top-hat 

deployment capability. Many of these vendors are already cited for use by MWCC and HWCG. 

The BOEM will not allow an operator to begin drilling operations until adequate subsea containment 

and collection equipment, as well as subsea dispersant capability, is determined by BOEM to be available 

to the operator and is sufficient for use in response to a potential incident from the proposed well(s). 

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 
Impact-Producing Factors and Scenario 3-41 

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; Federal Interagency Solutions Group, 2010). 

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 
3-42 Central Planning Area Supplemental EIS

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 

that the oil biodegraded quickly; however, there are still ongoing studies assessing this issue. It may be 

years before this data is developed and made available to the public. 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 Mesa, 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 
Impact-Producing Factors and Scenario 3-43 

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 310,000 bbl of oil from the water surface (Allen, 2011; 

Federal Interagency Solutions Group, 2010), approximately 5 percent of the Macondo oil spilled 

(Lubchenco et al., 2010; Federal Interagency Solutions Group, 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 

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 within a range of 30o

and 35o

 API, which are typical for the Gulf of Mexico. 

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 
3-44 Central Planning Area Supplemental EIS

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 they 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 that hard boom often did more damage than anticipated to the marsh it was intended to protect, 

after weather conditions ended up stranding the boom back into the marsh (USDOC, NOAA, 2010a; 

Allen, 2010). 

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 of the type typically found in the GOM, 

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 
Impact-Producing Factors and Scenario 3-45 

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 to avoid 

additional damage to the marsh ecosystem. 

 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. 

 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 BSEE requires that all losses of well control be reported to BSEE. 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). 
3-46 Central Planning Area Supplemental EIS

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. A blowout may include any one or more of the 

three loss of well control events above, but it is most commonly thought of as a release into 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). 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 

BOEM has made an estimate of 15 Bcf of gas released by Macondo, in absence of any other attempt at 

quantifying the release (DeCort, official 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 since that time. 

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 

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. 
Impact-Producing Factors and Scenario 3-47 

The major difference 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 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. 

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 fewer 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. 
3-48 Central Planning Area Supplemental EIS

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. 

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. 
Impact-Producing Factors and Scenario 3-49 

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, 2011a, 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, 2011a, pp. 7-8). 

Blowout Preventer Effectiveness 

The Technology Assessment & Research (TA&R) Program is a research element within BSEE’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 BSEE 

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 it 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 nor has such a program been proposed in recent BSEE, 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. 

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 they 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 250.516 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 
3-50 Central Planning Area Supplemental EIS

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, BSEE 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. 

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 overthickened 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. 

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 
Impact-Producing Factors and Scenario 3-51 

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 to this Agency: (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. 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, which is a 

response to West Engineering Services’ (2004) recommendation 1. The remaining recommendations 

exceed requirements in the new safety rules for BOP’s. Contractor recommendations are made at the 

discretion of the contractor for this Agency to consider and are not binding on this Agency. 

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. 

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 

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 
3-52 Central Planning Area Supplemental EIS

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 Drilling Safety Rule (Federal 

Register, 2010b). The NTL also informs lessees that BSEE would 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 BSEE’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 BSEE 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. 

3.2.3. 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 of a pipeline are 

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. 
Impact-Producing Factors and Scenario 3-53 

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 where a spill size of 

4,200 bbl is assumed, and it would 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, 

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 
3-54 Central Planning Area Supplemental EIS

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 spill 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). 

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. 

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). 

Because the frequency of these accidental SBF spills has been decreasing, BOEM has not funded further 

studies into the environmental impacts of accidental SBF releases. 

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, 
Impact-Producing Factors and Scenario 3-55 

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, 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 

 Alabama 

 Florida 

 Louisiana 

 Mississippi 

 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 

 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 
3-56 Central Planning Area Supplemental EIS

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, present, and reasonably foreseeable future activities 

that have taken or will take 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 

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 USCG or BSEE have no officially designated safety zones requiring activity setbacks from OCS facilities, although 500 m (1,640 ft) is a generally recognized safety buffer set-back from 

floating structures. 
Impact-Producing Factors and Scenario 3-57 

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 BOEM, 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 

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]); 
3-58 Central Planning Area Supplemental EIS

(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 BOEM 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 BOEM 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 BOEM 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, 

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 BOEM 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. 
Impact-Producing Factors and Scenario 3-59 

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 

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 
3-60 Central Planning Area Supplemental EIS

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 in the CPA 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 in ocean dredgedmaterial 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. 

If funds are available, dredged materials disposed offshore are 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 several 

ODMDS’s offshore Louisiana and Mississippi that are utilized for disposal of dredged material 

(U.S. Dept of the Army, COE, 2008, Table 1). The ODMDS’s are designated by USEPA and are utilized 

by COE for disposal of dredged material from maintenance channels. A list of designated ocean dredgedmaterial disposal sites are 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). 

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). 
Impact-Producing Factors and Scenario 3-61 

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 BOEM 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 the 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, BOEM uses the following two types of lease 

conveyances: a noncompetitive negotiated agreement that can only be used for obtaining sand and gravel 

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 BOEM has issued 

29 noncompetitive negotiated agreements, but it 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. 

The BOEMRE, and now BOEM as a successor 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 the 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, 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 
3-62 Central Planning Area Supplemental EIS

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) 

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. 
Impact-Producing Factors and Scenario 3-63 

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. 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 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 BOEM 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, 2009b, 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 and 2010, saw 101 and 89 cruise ship departures, respectively 

(USDOT, MARAD, 2011). 

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 BOEM 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 

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 
3-64 Central Planning Area Supplemental EIS

coexisted without conflict for many years. Several military stipulations are planned for leases issued 

within identified military areas. 

Cumulative Activities Scenario: The BOEM 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, BOEM 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. All five Gulf Coast States (Texas, 

Louisiana, Mississippi, Alabama, and Florida) have artificial reef programs and plans. 

Even though there have been many proponents to the concept of artificial reefs as an enhancement to 

an ecosystem, some argue that artificial reefs are merely fish attractors. Bohnsack and Southerland (1985, 

found in Macreadie et al., 2011) found direct evidence of fish attraction during the first few years after 

artificial reef installations, although it is suggested that this should not constitute a body of evidence 

against production because of the short time scale involved. An observed increase in the abundance of 

large fish around artificial reefs is clearly the result of attraction, but initial attraction does not preclude 

the possibility of later production, which is occurring over several decades (Macreadie et al., 2011). 

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. 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. 

“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 hydraulic fracturing tight geologic 

formations has opened the shale gas frontier. Shale gas is held in fine-grain formations such as shale, 

which is difficult to produce without introducing artificial fractures (fracking) 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 
Impact-Producing Factors and Scenario 3-65 

price of natural gas between 2002 and 2007 fluctuated between $5.00 and $8.00 per Mcf. The price 

spiked to $15.00 per Mcf after the 2005 GOM hurricanes, and a speculative bubble peak high price of 

$13.00 per 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 per 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 

mechanically challenging 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, 

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 
3-66 Central Planning Area Supplemental EIS

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, 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. The 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 BOEM 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. 

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 
Impact-Producing Factors and Scenario 3-67 

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 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 

BOEM has had conversations with developers about conceptual ideas for alternative use projects, no 

developer has stepped forward with an application to actualize one. 

Cumulative Activities Scenario: The BOEM 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. 
3-68 Central Planning Area Supplemental EIS

3.3.4. Other Major Factors Influencing Coastal Environments 

Naturally 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. 

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
Impact-Producing Factors and Scenario 3-69 

(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 BOEM 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 sea-level 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, which 

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 (1987, 

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. 

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, 
3-70 Central Planning Area Supplemental EIS

(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 BOEM 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 nine 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) GIWW between 

the Atchafalaya and Mississippi Rivers; (3) GIWW West of Atchafalaya River; (4) Barataria Bay 

Waterway; (5) Bayou Lafourche; (6) Houma Navigation Canal; (7) Mermentau Navigation Channel; 

(8) Freshwater Bayou; and (9) 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 BOEM staff compiled Table 3-15 using the 

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 
Impact-Producing Factors and Scenario 3-71 

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 a beneficial use of dredged 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 

dredged 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, 2009b, 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 OCSrelated 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). 
3-72 Central Planning Area Supplemental EIS

The BOEM anticipates that, over the next 40 years, if current trends in use of dredged sand and 

sediment for the beneficial use of dredged 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, 2009c). The 

Appropriations Act required Louisiana to create a State organization to sponsor the hurricane protection 

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 
Impact-Producing Factors and Scenario 3-73 

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 BOEM 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 that will feed into the Coastal 

Protection and Restoration Authority’s Annual Plan for authorization and what projects 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 up 

until September 30, 2011. In 2011, it was announced that FWS will take over administration of CIAP, 

effective October 1, 2011, since the program aligns with the FWS conservation mission and similar grant 

programs run by FWS. The eligibility requirements for States, CPS’s, and fundable projects are expected 

to remain largely the same after the transfer. 

The CIAP provides Federal grant funds derived from Federal offshore lease revenues to oil-producing 

states for conservation, protection, or restoration of coastal areas. This includes wetlands; mitigation of 

damage to fish, wildlife, or natural resources; planning assistance and the administrative costs of 

complying with these objectives; implementation of a federally approved marine, coastal, or 

comprehensive conservation management plan; and mitigation of the impact of OCS activities through 

the funding of onshore infrastructure projects and public service needs. Under Section 384 of EPAct, the 

Secretary of the Interior 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). 
3-74 Central Planning Area Supplemental EIS

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 BOEM 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 
Impact-Producing Factors and Scenario 3-75 

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. 

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 Lugo-
3-76 Central Planning Area Supplemental EIS

Fernandez, 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). 

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, 2007c). 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 there are significant new circumstances or 

information bearing on the CPA proposed action or its impacts, as stated in the Multisale EIS and the 

2009-2012 Supplemental EIS, and, if so, to disclose those changes and conclusions. 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 proposed CPA lease sale 

area encompasses about 63 million ac of the total CPA area of 66.45 million ac. This area is located 

offshore Louisiana, Mississippi, and Alabama from 3 to about 230 nmi (3.5 to 265 mi; 5.6 to 426 km) 

offshore in water depths of about 3 to >3,400 m (9 to >11,115 ft). As of November 2011, about 

38.6 million ac of the CPA lease sale area are currently unleased. This proposed CPA lease sale 

(Alternative A) would offer for lease all unleased blocks in the CPA for oil and gas operations (Figure 

2-1), with the following exceptions: 

(1) blocks that were previously included within the Gulf of Mexico’s EPA and are within 

100 mi (161 km) of the Florida coast; 

(2) blocks east of the Military Mission line (86 degrees, 41 minutes West longitude) 

under an existing moratorium until 2022, as a result of the Gulf of Mexico Energy 

Security Act of 2006 (December 20, 2006); 

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

northern portion of the Eastern Gap; and 

(4) whole and partial blocks that lie within the former Western Gap and are within 

1.4 nmi north of the continental shelf boundary between the U.S. and Mexico. 

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 
4-4 Central Planning Area Supplemental EIS 

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. 

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 as well as the sensitivity of the 

environment in which the resource is located. 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 post-DWH credible scientific information that was publicly 

available at the time this Supplemental EIS was prepared, applied using accepted methodologies. 

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. The conservative approach would be to 

expect that impacts from the lease sale may be greater than prior to the DWH event, although the 

magnitude of those impacts cannot yet be fully determined (Chapter 4.1, “Incomplete or Unavailable 

Information”). The BOEM 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. 
Description of the Environment and Impact Analysis 4-5 

In order to accomplish this task, BOEM 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 BOEM’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 BOEM’s Environmental Studies Program. The results of these studies feed directly 

into our NEPA analyses. To date, since 1973, approximately $350 million has been spent on physical, 

environmental, and socioeconomic studies in the Gulf of Mexico OCS Region. There are currently 

89 ongoing studies in the Gulf of Mexico OCS Region, at a cost of about $48 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, BOEM also has a Scientific Advisory 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 credible scientific information available since the DWH event and applied using 

accepted methodologies. Where relevant information on reasonably foreseeable significant adverse 

impacts is incomplete or unavailable, the need for the information was evaluated to determine if it was 

essential to a reasoned choice among the alternatives and, if so, was either acquired or in the event it was 

impossible or exorbitant to acquire the information, accepted scientific methodologies were applied in its 

place. This approach is described in the next subsection on “Incomplete or Unavailable Information.” 

Over the years, a suite of lease stipulations and mitigation measures has been developed to eliminate 

or ameliorate potential environmental effects, where implemented. 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 BOEM 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 

references to incomplete or unavailable information, particularly in relation to the DWH event and the 

associated oil spill. The subject-matter experts for each resource used what scientifically credible 

information was publicly available at the time this Supplemental EIS was written and acquired, when 

possible, new information that has become available since the Multisale EIS and the 2009-2012 

Supplemental EIS. This new information is included in the description of the affected environment and 

impact analyses throughout Chapter 4. Where necessary, the subject-matter experts extrapolated from 

existing or new information, using accepted methodologies, to make reasoned estimates and developed 

conclusions regarding the current CPA baseline for resource categories and expected impacts from the 

proposed action given any baseline changes. Since this document supplements the Multisale EIS and the 

2009-2012 Supplemental EIS, the subject-matter experts were tasked with determining if the conclusions 

made in the previous EIS’s on the significance of impacts had changed based upon the new information. 

The most notable information changes since the Multisale EIS and the 2009-2012 Supplemental EIS 

relates to the DWH event in the CPA. Credible scientific data regarding the potential short-term and 

long-term impacts on CPA resources is slowly becoming available but remains incomplete at this time, 

and it could be many years before this information becomes available via the Natural Resource Damage 
4-6 Central Planning Area Supplemental EIS 

Assessment (NRDA) process, BOEM’s Environmental Studies Program, and numerous studies by 

academia. Nonetheless, the subject-matter experts acquired and used new scientifically credible 

information that was available, determined that additional information was not available absent exorbitant 

expenditures or could not be obtained regardless of cost in a timely manner, and where gaps remained, 

exercised their best professional judgment to extrapolate baseline conditions and impact analyses using 

accepted methodologies based on credible information. 

It is important to note that, barring another catastrophic oil spill, which is a low-probability accidental 

event, the adverse impacts associated with the proposed CPA lease sale are small, even in light of the 

DWH event. This is because of BOEM’s lease sale stipulations and mitigations, site-specific mitigations 

that become conditions of plan or permit approval at the postlease stage, and mitigations required by other 

State and Federal agencies. Lease sale stipulations used to avoid environmental impacts may include the 

Topographic Features Stipulation; Live Bottom (Pinnacle Trend and Low Relief) Stipulation; Blocks 

South of Balwin County, Alabama, Stipulation; and Protected Species Stipulation. Site-specific postlease 

mitigations may include buffer zones and avoidance criteria to protect sensitive resources such as areas of 

topographic relief, chemosynthetic communities, deepwater corals, and historic shipwrecks. Mitigations 

may also be required by other agencies (i.e., the U.S. Army Corps of Engineers and State CZM agencies) 

to reduce or avoid impacts from OCS activities; these mitigations include boring under beach shorelines 

and the rerouting of pipelines to reduce or eliminate impacts from OCS pipelines that make landfall. 

For the following resources, the subject-matter experts determined that there is incomplete or 

unavailable information that is relevant to reasonably foreseeable significant adverse impacts; however, it 

is not essential to a reasoned choice among alternatives. 

 Air Quality (Chapter 4.1.1.1) 

 Coastal and Offshore Water Quality (Chapters 4.1.1.2.1 and 4.1.1.2.2, respectively) 

 Coastal Barrier Beaches and Associated Dunes (Chapter 4.1.1.3) 

 Wetlands (Chapter 4.1.1.4) 

 Sargassum (Chapter 4.1.1.8) 

 Chemosynthetic and Nonchemosynthetic Deepwater Benthic Communities 

(Chapters 4.1.1.9 and 4.1.1.10, respectively) 

 Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice (Chapter 

4.1.1.13) 

 Recreational Fishing (Chapter 4.1.1.18) 

 Recreational Resources (Chapter 4.1.1.19) 

 Historic and Prehistoric Archaeological (Chapters 4.1.1.20.1 and 4.1.1.20.2, 

respectively) 

 Land Use and Coastal Infrastructure (Chapter 4.1.1.21.1) 

 Economic Factors (Chapter 4.1.1.21.3) 

 Soft Bottoms (Chapter 4.1.1.22.1) 

For the following resources, the subject-matter experts determined that there is incomplete or 

unavailable information that is relevant to reasonably foreseeable significant adverse impacts and may be 

essential to a reasoned choice among alternatives. 

 Seagrass Communities (Chapter 4.1.1.5) 

 Live Bottoms (Pinnacle Trend and Low Relief) (Chapters 4.1.1.6.1 and 4.1.1.6.2, 

respectively) 

 Topographic Features (Chapter 4.1.1.7) 
Description of the Environment and Impact Analysis 4-7 

 Marine Mammals (Chapter 4.1.1.11) 

 Sea Turtles (Chapter 4.1.1.12) 

 Coastal and Marine Birds (Chapter 4.1.1.14) 

 Gulf Sturgeon (Chapter 4.1.1.15) 

 Fish Resources and Essential Fish Habitat (Chapter 4.1.1.16) 

 Commercial Fisheries (Chapter 4.1.1.17) 

 Environmental Justice (Chapter 4.1.1.21.4) 

 Diamonback Terrapins (Chapter 4.1.1.22.2) 

This chapter has thoroughly examined the existing credible scientific evidence that is relevant to 

evaluating the reasonably foreseeable significant adverse impacts of the proposed CPA lease sale on the 

human environment. The subject-matter experts that prepared this Supplemental EIS conducted a diligent 

search for pertinent information, and BOEM’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. Throughout this chapter, where information was incomplete or 

unavailable, BOEM complied with its obligations under NEPA to determine if the information was 

relevant to reasonably foreseeable significant adverse impacts; if so, whether it was essential to a 

reasoned choice among alternatives; and, if it is essential, whether it can be obtained and whether the cost 

of obtaining the information is exorbitant, or whether scientifically credible information can be applied 

using accepted scientific methodologies in its place (40 CFR 1502.22). 

Incomplete or unavailable information is identified and addressed in the individual analyses for each 

resource in Chapter 4. The BOEM subject-matter experts have provided the analysis for whether the 

incomplete or unavailable information was relevant to reasonably foreseeable significant adverse impacts, 

whether it was essential to a reasoned choice among alternatives, whether the information could be 

obtained under any circumstance or whether it could only be obtained with exorbitant cost; and applied 

scientifically credible information using accepted scientific methodologies where information remained 

incomplete or unavailable. 

4.1.1. Alternative A—The Proposed Action 

4.1.1.1. Air Quality 

The BOEM 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 cumulative impact from all offshore and onshore emissions (such as vehicle traffic, 

power generation, and industrial activities) may continue to be significant in the ozone nonattainment 
4-8 Central Planning Area Supplemental EIS 

areas in southeast Texas and the parishes near Baton Rouge, Louisiana. The emissions from the proposed 

action would result in an insignificant contribution to ozone levels in the nonattainment areas. 

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. 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. The NAAQS address 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, 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/m3

 to 35 g/m3. On May 27, 2008, USEPA promulgated a new, more restrictive 

NAAQS 8-hour O3 standard of 0.075 ppm. 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 (see Chapter 4.1.1.21.4, 

Environmental Justice). 

Although final summary information and reports on air quality impacts from the DWH event may be 

forthcoming, USEPA, NOAA, and other agencies obtained and released to the public a large number of 

air quality measurements indicating that air impacts tended to be minor and below USEPA’s health-based 

standards. As there are no continuing sources of air pollution related to the DWH event, BOEM would 

not expect any additional measurements or information to alter the conclusions from currently existing 

data. As such, although there is incomplete or unavailable information on air quality impacts that may be 

relevant to reasonably foreseeable adverse impacts, this information is not essential to a reasoned choice 

among alternatives. 

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. 
Description of the Environment and Impact Analysis 4-9 

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 BOEM 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 NAAQS 8-hour ozone standard of 0.075 ppm has been 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 the pollutants CO, SO2, NO2, and PM, and nonattainment for O3. The 

O3 nonattainment parishes in Louisiana are in the Baton Rouge area and 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 (Federal Register, 2010e). A steady decline in 

ozone concentration 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 Prevention of Significant Deterioration (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/m3

 annual increment for NO2; 25 gm3

3-hour increment, 5 g/m3

 24-hour increment, and 2 g/m3 annual increment for SO2; and 8 g/m3

24-hour increment and 4 g/m3

 annual increment for PM10. In October 2011, a PSD increment went into 

effect for PM2.5. For a Class I area, the 24-hour increment for PM2.5 is 2 μg/m3

. 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 air-quality-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 BOEM has addressed FWS concerns with a 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). However, there is uncertainty in the emission inventories for the 

baseline year. 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 

because of the unavailability of air quality data specific to the area. However, it is expected that the effect 

of the DWH event on the air quality at the BNWA was small since the air emissions from the DWH event 

were temporary sources and since all air quality data for other areas of the Gulf Coast remained below 

USEPA’s health-based standards. 

Jurisdiction 

The responsibilities of BOEM 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. Section 328 of the 1990 Clean Air Act Amendments transferred 

jurisdiction over OCS air emission sources from BOEM to USEPA, except for the Gulf of Mexico OCS 

west of 87.5o W. longitude. 

The USEPA promulgated the OCS air quality regulations to implement the statutory directives 

(40 CFR 55). Over the past several years, BOEM has leased some blocks that are east of 87.5o

 W. 
4-10 Central Planning Area Supplemental EIS 

longitude. Lessees planning to drill exploration wells are currently working with USEPA to obtain 

permits for air emissions (USEPA, 2010b). 

Emission Inventories 

The CAAA requires BOEM 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 BOEM has completed three air emissions inventory studies for calendar years 2000 (Wilson et 

al., 2004), 2005 (Wilson et al., 2007), and 2008 (Wilson et al., 2010). 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. The 

2008 study was completed in December 2010 (Wilson et al., 2010). In the summer of 2010, BOEM 

funded another cycle of this air emissions inventory to be conducted during 2011. These emissions 

inventories 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 may 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 by owners of industrial facilities. 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 as well as flaring. The USEPA has determined that the activity data 

(Gulfwide Offshore Activities Data System [GOADS]) that has been collected to fulfill BOEM’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, BOEM’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). 

General Conformity Regulations 

New General Conformity Regulations were promulgated on March 24, 2010 (USEPA, 2011c). This 

regulation applies only to emissions within State waters in a nonattainment area. It does not apply to 

emissions generated on the OCS, except for OCS-related emissions that may occur within State waters, 

such as emissions from vessels. The BOEM has not had to produce any conformity determinations in the 

Gulf of Mexico. 

4.1.1.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the impacts 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 
Description of the Environment and Impact Analysis 4-11 

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. 

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 reported to BSEE and are evaluated individually for compliance with safety and flaring 

requirements. 

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. 

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 and lower stack heights. During exploratory drilling operations, air emissions may be high 

enough to contribute to exceedances of the new, short-term, 1-hour NOx and SOx National Ambient Air 

Quality Standards (NAAQS) and, hence, these emissions may affect onshore air quality. 

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 

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 BSEE operating 

regulations provide for some limited volume, short duration flaring or venting of some natural gas 

volumes upon approval by BSEE. 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 
4-12 Central Planning Area Supplemental EIS 

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 during daytime hours, 

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). Although for the summer months the 

wind regime in the CPA is predominantly onshore during the day, OCS activities would not be expected 

to impact air pollutant levels in the CPA because any pollutants emitted would be dispersed and 

recirculated prior to reaching shore. The majority of OCS Program-related emissions occur offshore 

anywhere from the State/Federal waters boundary to 200 mi (322 km) offshore, which limits the potential 

for emissions to result in impacts onshore. 

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 nitrogen oxides (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 each 

installation generally occurs over a period of 3-4 months. Typical construction emissions result from the 

derrick barge placing the jacket and modular components, and from 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. 

The BOEM regulations (30 CFR 550.302-304) establish 1-hour and 8-hour significance levels for 

CO; annual, 24-hour, and 3-hour significance levels for surphur dioxide (SO2); annual and 24-hour 

significance levels for TSP; and annual significance levels for NO2. The regulations established emission 

exemption levels to determine whether the exemption levels may be exceeded. A comparison of the 

projected emission rate with BOEM’s exemption levels was used to assess impacts. While the exemption 
Description of the Environment and Impact Analysis 4-13 

levels apply only to individual facilities, to be conservative in the analysis, the sum of all facilities was 

used in this comparison. The formula to compute the emission rate in tons/for CO, E is 3,400•D2⁄3; 

D represents distance in statute miles from the shoreline to the source; and E=33.3D for total suspended 

particulates (TSP), SO2, NOx, and VOC. The sum of all emissions were calculated and is applied to each 

facility. 

The VOC emissions are best addressed as their corresponding ozone impacts, which were studied in 

the Gulf of Mexico 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 of the standard ( 120 ppb at the time) were less than 2 ppb. In 

the GMAQS, the model was also run using double emissions from OCS petroleum development 

activities, and the resulting contribution to ozone concentrations for the episode modeled was still small, 

ranging from 2 to 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 550.303(g)(2) requires that, if a facility would 

significantly impact (defined as exceeding BOEM’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. In response to the revised 1997 ozone standard 

(0.08 ppm), 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 produced pursuant to the proposed action 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]). 

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, BOEM 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 
4-14 Central Planning Area Supplemental EIS 

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. 

The subjects of the contribution of OCS activities to greenhouse gas emissions and climate change 

have been discussed in the 5-Year Program (USDOI, MMS, 2007a). Climate change effects have been 

observed to be occurring on all continents and oceans, and these observations have provided insights on 

relationships among atmospheric concentrations of carbon dioxide and other greenhouse gases, mean 

global temperature increases, and observed effects on physical and biological systems. There are many 

impacts associated with climate change processes that have been observed in U.S. coastal regions, and 

these impacts include changing air and water temperatures, rising sea levels, more intense storms, ocean 

acidification, coastal erosion, sea ice loss, declining coral reef conditions, and loss of critical habitats such 

as estuaries, wetlands, barrier islands, and mangroves. 

Climate change in the GOM is expected to affect coastal ecosystems, forests, air and water quality, 

fisheries, and business sectors such as industry and energy. The GOM region has experienced increasing 

atmospheric temperatures since the 1960’s, and from 1900 to 1991 sea-surface temperatures have 

increased in coastal areas and decreased in offshore regions. In addition to temperature changes, the 

northern coast of the GOM is experiencing impacts associated with sea-level rise; these impacts include 

the loss of coastal wetland and mangrove habitats, saltwater intrusion into coastal aquifers and forests, 

and increases in shoreline erosion. Climate change associated sea-level rise is occurring in combination 

with altered hydrology and land subsidence, which has resulted in measures of relative sea-level rise 

ranging between 0.002 m/yr (0.007 ft/yr) along Texas and up to 0.01 m/yr (0.03 ft/yr) along the 

Mississippi River Delta. The climate change would also likely affect the precipitation changes. 

The 5-Year Program’s emissions were averaged over a 40-year period. The projected CO2 emissions 

from the proposed 5-Year Program are about 0.06-0.12 percent of all current CO2 emissions in the United 

States. The 5-Year Program’s CH4 emissions are about 0.43-0.82 percent of the current CH4 emissions in 

the United States. If one combines the CO2 and CH4 emissions, the 5-Year Program’S emissions are 

about 0.09-0.18 percent of the emissions in the United States. The estimated 5-Year Program’S CO2

emissions are about 0.08-0.016 percent of the global CO2 emissions from fossil fuel combustion. Gulf of 

Mexico offshore oil and gas production is responsible for about 0.45 percent of the Nation’s GHG 

emissions. Flaring, venting, and fugitive emissions account for <0.1 percent of this amount, the majority 

of the 0.45 percent comes from supply boats, helicopters (neither regulated by DOI), and platform 

equipment. Therefore, the CPA proposed action contributes minimally to climate change. Nevertheless, 

several activities to more accurately report and possibly reduce GHG emissions from the Gulf of Mexico 

OCS are in progress. 

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 

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, vapor, condensate, or 

natural gas or chemicals used offshore or the pollutants from the burning of these products. Typical 

emissions from OCS accidents consist of hydrocarbons and possibly 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 pollutants, including NO2, CO, 
Description of the Environment and Impact Analysis 4-15 

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). 

Proposed Action Analysis 

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, offshore 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 likely not affect onshore ozone concentrations. 

The VOC emissions from the evaporation of oil spill can contribute to the formation of particulate 

matter (PM2.5) through chemical transformation in the atmosphere. In-situ burning also generates 

particulate matter. Particulate matter can cause adverse human respiratory effects and can also result in a 

reduction in visibility (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 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 the air. The BTEX level is one commonly used measurement 

to provide an indication of the level of 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, offshore 

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 a very high concentration of 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 BSEE’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. 

In-situ Burning 

In-situ burning of a spill results in emissions of NOx, SO2, CO, PM10, and PM2.5 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 they were significantly lower than those 
4-16 Central Planning Area Supplemental EIS 

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. The 

measurements taken from the NOAA WP-3D aircraft during the DWH oil spill are different from the 

monitoring described in Fingas et al. (1995), i.e., 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/m3

beyond about 5 km (3 mi) downwind of an in-situ burn at that time; it has since been determined by 

USEPA that a 24-hour concentration of 35 μg/m3

 is more protective of human health. 

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 (Fingas et al., 1995) and in Alaska (McGrattan et al., 1995). 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). The shoreline dioxin concentration from the in-situ burns would be much less than the 

measured air concentration in rural locations of the United States and, thus, concerns about 

bioaccumulation in seafood were alleviated (Schaum et al., 2010). 

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. 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 would 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 dispersant components were 

identified. It should be noted that the COREXIT ingredients monitored are also common ingredients in a 

number of household products. Therefore, their detection onshore does not equate to the detection of 

dispersants. The USEPA has noted that there is no evidence that dispersant application resulted in a 

significant impact to onshore air quality. 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. 

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 
Description of the Environment and Impact Analysis 4-17 

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. 

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. 

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 

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 
4-18 Central Planning Area Supplemental EIS 

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 H2S 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 H2S greater than 20 ppm from the source or a platform. In the event of H2S 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 caused effects on air quality, which occurred from the application of 

dispersants to the oil spill, in-situ oil burning, evaporation of toxic chemicals from the oil spill, and 

cleanup activities. Onshore air quality data indicate that USEPA’s health-based standards were not 

exceeded, although there were public complaints regarding health concerns (Chapter 4.1.1.21.4). 

An oil spill could cause the release and transport of 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, 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. The effects of the 

DWH event on public health and the environment can be classified as the short-term and long-term 

effects. The short-term effects includes watery and irritated eyes, skin itching and redness, coughing, and 
Description of the Environment and Impact Analysis 4-19 

shortness of breath or wheezing. As yet, little is know about any long-term health effects of direct 

exposure to oil from the DWH event (Chapter 4.1.1.21.4). 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 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). 

In summary, there is no study of the long-term, air quality-related health effects on humans in the 

assessments of historic oil spills. The Kuwaiti oil-field fires are one instance in which air quality effects 

from oil burning have been further researched. In the Kuwaiti event, 600 oil wells on land were set in 

flames. These uncontrolled 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 symptoms attributed to 

their exposures, including asthma and bronchitis (Lange et al., 2002). 

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, such emissions 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 the applicability of air quality 

regulations. 
4-20 Central Planning Area Supplemental EIS 

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 BOEM, 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. 

The BOEM 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 expected to be minimal in 

the current regulatory environment. 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. 

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 
Description of the Environment and Impact Analysis 4-21 

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 

(USDOC, NOAA, 2008a). The natural resources of the Gulf of Mexico are also important for tourism 

and recreation. 

More than 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, nutrients, and organic matter. 

Urban runoff increases with population growth, and the Gulf Coast region has experienced a 109 percent 

population growth since 1970, with an additional 15 percent increase expected by 2020 (USDOC, NOAA, 

2011a). 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 
4-22 Central Planning Area Supplemental EIS 

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, 2010). 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). 

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). 

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. The 

Government estimated that approximately 4.9 million barrels of oil were released during the DWH event 

(Oil Spill Commission, 2011b). As well, the corresponding emission of methane from the wellhead 

during the DWH event was estimated between 9.14 x 109

 and 1.25 x 1010 moles (Kessler et al., 2011). In 

coastal waters, the maximum extent of surface water and shoreline oiling stretched from roughly the 

Louisiana-Texas border to Apalachicola, Florida (Oil Spill Commission, 2011b, Figure 7.1). Also, a 

subsurface oil and gas plume was discovered in deep water between ~1,100 and 1,300 m (3,609 and 

4,265 ft) (e.g., Diercks et al., 2010). Based on in-situ fluorescence and oxygen measurements (proxies for 

oil concentration and biodegradation, respectively), the subsurface plume traveled to the northeast of the 

wellhead and much farther to the southwest, reaching as far west as approximately 93° W. longitude (e.g., 

Kessler et al., 2011). 

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 

(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). 
Description of the Environment and Impact Analysis 4-23 

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, 2011a). 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, 2011a). Because alkanes are simple hydrocarbons, these oils are likely to 

undergo biodegradation more easily (USDOC, NOAA, 2011a). 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, the oil from 

the DWH event is less toxic than other crude oils in general because this oil is lower in PAH’s than many 

crude oils (USDOC, NOAA, 2011a). 

Extensive water and sediment sampling was performed in coastal waters during the DWH response. 

Water and sediment samples were collected in the nearshore zone at multiple sites from Texas to Florida 

for quantitative analysis of oil and oil-related compounds, dispersants, or by-products (OSAT, 2010). 

The main nearshore sampling efforts were conducted by USEPA, USGS, and the Center for Toxicology 

and Environmental Health (a BP contractor), with additional samples provided by other Federal and State 

agencies. A total of 6,090 water samples were considered for comparison with USEPA’s human health 

benchmarks. None of the samples exceeded USEPA’s benchmark for human health (child swimmer 

scenario). A total of 6,909 water and sediment samples were considered for comparison with USEPA’s 

aquatic life benchmarks. Of these samples, a total of 41 nearshore water benchmark exceedances were 

observed throughout the event. Based on oil fingerprinting, 13 of these samples were of indeterminate 

origin, 19 were considered not consistent with MC 252 oil, and 9 were deemed consistent with MC 252 

oil. Only a small subset of the analyzed samples targeted areas of observed surface oil, such as samples 

collected during the Dispersant Environmental Effects Project (DEEP). A total of 24 nearshore sediment 

benchmark exceedances were observed throughout the event. As with water, fewer sediment benchmark 

exceedances were observed in USEPA Region 6 (Texas and Louisiana) than in USEPA Region 4 

(Alabama, Mississippi, and Florida). Of the total sediment exceedances, 9 samples were of indeterminate 

origin, 11 were considered not consistent with MC 252 oil, and 4 were consistent with MC 252 oil. 

Notably, no water or sediment benchmark exceedances in the nearshore measured after August 3, 2010 

(the last overflight observation of surface oil), were consistent with MC 252 oil. 

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). Theoretically, methane could 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). During the DWH event, methane 

and oxygen distributions were measured at 207 stations throughout the affected region (Kessler et al., 

2011). Based on these measurements, it was concluded that, within ~120 days from the onset of release, 

~3.0 x 1010 to 3.9 x 1010 moles of oxygen were respired, primarily by methanotrophs, and left behind a 

residual microbial community containing methanotrophic bacteria. The researchers further suggested that 

a vigorous, deepwater bacterial bloom respired nearly all the released methane within this time and that, 

by analogy, large-scale releases of methane from hydrate in the deep ocean are likely to be met by a 

similarly rapid methanotrophic response. 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). 

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, 2010f). 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 through natural processes. For instance, microbial metabolism of 

crude oil results in the dispersion of oil (Bartha and Atlas, 1983). Oil dispersion, as a spill-response 

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, which temporarily increases the toxicity (Bartha and Atlas, 1983). The toxicity of 
4-24 Central Planning Area Supplemental EIS 

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). 

The Government estimated that approximately 1.84 million gallons of dispersant were used to 

breakup and dilute the oil subsea at the wellhead and on the surface (Oil Spill Commission, 2011a). 

COREXIT 9500 and 9527 were used in response to the DWH event and resulting spill (USEPA, 2010f). 

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, 2011d). 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). 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. A recent study assessed the impacts of COREXIT 

EC9500A, which was widely deployed during the DWH event, on microbial communities from a beach 

impacted by the spill (Hamdan and Fulmer, 2011). The findings suggest that hydrocarbon-degrading 

bacteria from the oiled beach were inhibited by chemical dispersants and that the use of dispersants has 

the potential to diminish the capacity of the environment to bioremediate spills. However, there was 

evidence that the dispersants worked in dispersing oil at the wellhead in the case of the DWH event 

(USDOC, NOAA, 2010b; USEPA, 2010f). 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 DWH event have 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). 

During the DWH response, sediment and water samples collected in the nearshore zone were 

analyzed for a number of dispersant-related chemicals, including, but not limited to dipropylene glycol 

n-butyl ether (DPnB), propylene glycol, and dioctylsulfosuccinate (DOSS). Between May 13 and 

October 20, 2010, 4,850 water and 412 sediment samples were collected in the nearshore zone (OSAT, 

2010). None of the concentrations of dispersant-related chemicals found in water samples collected 

during the response exceeded USEPA’s benchmarks. Only 66 samples (60 water and 6 sediment) had 

detectable levels of dispersant-related chemicals. DPnB was the most common detectable dispersantcompound and was found in 57 of the 60 water samples; however, concentrations never exceeded 3 μg/L 

(cf., USEPA screening level 1 mg/L). The presence of dispersant-related chemicals in water occurred all 

along the Gulf Coast; however, a majority of the nearshore detects were encountered around Louisiana. 

Propylene glycol was the only dispersant-related chemical detected in the sediments. Unfortunately, no 

benchmark for dispersant indicator compounds in sediment exists; thus, the significance of these 

concentrations is unknown. 

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, 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 
Description of the Environment and Impact Analysis 4-25 

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, 2010). 

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, 2010a). 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, official communication, 2011). 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 BOEM 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. 

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 are 

underway. 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, oil still remains in the environment (SCAT, 2011a and 2011b; OSAT-2, 2011). As such, there 

remains some incomplete or unavailable information that may be relevant to reasonably foreseeable 

impacts on coastal water quality. Much of this information is continuing to be collected and developed 

through the NRDA process. These data collection and research projects may be years from completion. 

Few data or conclusions have been released to the public to date. Regardless of the costs involved, it is 

not within BOEM’s ability to obtain this information from the NRDA process within the timeline of this 

Supplemental EIS. In light of this incomplete and unavailable information, BOEM subject-matter experts 

have used credible scientific information that is available and applied it using scientifically accepted 

methodology. Given the available data described above, however, BOEM believes that this incomplete or 

unavailable information is not essential to a reasoned choice among alternatives. 

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; 
4-26 Central Planning Area Supplemental EIS 

 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). 

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 

U.S. Environmental Protection Agency’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 because of the 

distance to shore of most routine activities, USEPA’s regulations that restrict discharges, and the few, if 

any, new pipeline landfalls or onshore facilities that would be constructed. 
Description of the Environment and Impact Analysis 4-27 

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 

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 into 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 
4-28 Central Planning Area Supplemental EIS 

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 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, 2010f). 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 

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 would 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 
Description of the Environment and Impact Analysis 4-29 

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 through, for example, increased 

vessel traffic, hydromodification, and application of dispersants. 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 would not be 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, 

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 
4-30 Central Planning Area Supplemental EIS 

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, 2010g). 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. 

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 because non-OCS Program-related activities, including vessel traffic, erosion, 

and nonpoint source runoff, are cumulatively responsible for a majority of coastal water impacts. 

Increased turbidity and discharge from the CPA proposed action would be temporary in nature and 

minimized by regulations and mitigation. Since a catastrophic OCS Program-related accident would be 

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. 
Description of the Environment and Impact Analysis 4-31 

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). More than 

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. 

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 
4-32 Central Planning Area Supplemental EIS 

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 the 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, 2010). 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 with coastal waters, shallow waters and sediments on the shelf and slope are also greatly affected 

by runoff. Runoff may include any number of pollutants such as nutrients, pesticides and other organic 

chemicals, and metals. 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 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 produced water entering the Gulf per year 

to be 473,000 bbl, with a resulting oil and grease discharge of approximately 11,905 bbl per year (NRC, 

2003, p. 200, Table D-8). 

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 biogenically derived (e.g., from biological sources), in 
Description of the Environment and Impact Analysis 4-33 

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). 

Several studies have addressed offshore water and sediment 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 it captured the drilling-related changes that 

occur in sediments and sediment pore water. Chemical impacts of drilling were detected at all four sites. 

Impacts noted within the near-field zone included elevated barium, synthetic-based fluid (SBF), total 

organic carbon (TOC) concentrations, and low sediment oxygen levels. 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, mean concentrations of sediment barium increased by ~30-fold at near-field 

stations following exploratory drilling (from 0.108% to 3.32%). As well, mean concentrations of 

sediment mercury and total PAH increased in the near-field from 71 to 90 nanograms/gram and from 

232 to 279 nanograms/gram, respectively. At this site, sediment cadmium concentrations did not change 

significantly following exploratory drilling. 

The condition of offshore waters of the Gulf of Mexico was altered by the DWH event and associated 

oil spill. The Government estimated that approximately 4.9 million barrels of oil were released during the 

event (Oil Spill Commission, 2011b). As well, the corresponding emission of methane from the wellhead 

during the DWH event was estimated between 9.14 x 109

 and 1.25 x 1010 moles (Kessler et al., 2011). In 

shelf waters, surface water oiling stretched from a maximum westward extent at roughly the LouisianaTexas border to an eastward extent around Apalachicola, Florida (Oil Spill Commission, 2011b, 

Figure 7.1). Surface oiling was also observed stretching southward from the spill site, farther over deep 

waters, as oil was advected by cyclones at the northern edge of the Loop Current (e.g., USDOC, NOAA, 

2010e). Also, a subsurface oil and gas plume was discovered in deep water between ~1,100 and 1,300 m 

(3,609 and 4,265 ft) (e.g., Diercks et al., 2010). Based on in-situ fluorescence and oxygen measurements 

(proxies for oil concentration and biodegradation, respectively), the subsurface plume traveled to the 

northeast of the wellhead and much farther to the southwest, reaching as far west as approximately 

93° W. longitude (e.g., Kessler et al., 2011). 

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 
4-34 Central Planning Area Supplemental EIS 

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, 2011a). 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, 2011a). Because alkanes are simple hydrocarbons, these oils are likely to 

undergo biodegradation more easily (USDOC, NOAA, 2011a). 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, the oil from the 

DWH event is less toxic than other crude oils in general because this oil is lower in PAH’s than many 

crude oils (USDOC, NOAA, 2011a). 

As in coastal waters, extensive water and sediment sampling was performed in offshore waters by the 

DWH response (OSAT, 2010). Note that the following is a synthesis of data from the offshore (shelf) 

and deepwater sampling zones in the OSAT report, separated by the 200-m (656-ft) isobath. 

Approximately 700 water and 250 sediment samples collected in shelf waters from May-October 2010 

were analyzed in the OSAT report. Chronic and acute aquatic life ratios were calculated for all samples 

in which PAH compounds were analyzed. Six water samples in shelf waters exceeded USEPA’s chronic 

aquatic life benchmark, and one of these exceeded the acute aquatic life benchmark during May-June 

2010. No shelf water samples exceeded the benchmark after August 3, 2010. In shelf sediment samples, 

none of the samples exceeded USEPA’s chronic aquatic life benchmark. In the deepwater sampling zone, 

water and sediment samples were collected by a number of vessels (NOAA, BP contract, and academic) 

operating both in the vicinity of the wellhead and in the far field. Approximately 4,000 water and 

sediment samples from the deepwater zone were analyzed in the OSAT report. In the deepwater zone, 

there was a total of 70 exceedances of aquatic life benchmarks for PAH’s in water and 7 exceedances in 

sediment. Chronic exceedances in water samples in deepwater potentially associated with MC 252 oil 

were constrained to within approximately 70 km (43 mi) of the wellhead and to approximately two depths 

(the near-surface and the subsurface between ~1,100 and 1,300 m [3,609 and 4,265 ft]). Quantitative 

results indicate that deposits of drilling mud-entrained oil remained near the wellhead. Seven sediment 

samples within 3 km (2 mi) of the wellhead, collected since August 3, 2010, exceeded aquatic life 

benchmarks for PAH’s, with oil concentrations of 2,000-5,000 ppm. 

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). Theoretically, methane could 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). During the DWH event, 

methane and oxygen distributions were measured at 207 stations throughout the affected region (Kessler 

et al., 2011). Based on these measurements, it was concluded that, within ~120 days from the onset of 

release, ~3.0 x 1010 to 3.9 x 1010 moles of oxygen were respired, primarily by methanotrophs, and left 

behind a residual microbial community containing methanotrophic bacteria. The researchers further 

suggested that a vigorous, deepwater bacterial bloom respired nearly all the released methane within this 

time and that, by analogy, large-scale releases of methane from hydrate in the deep ocean are likely to be 

met by a similarly rapid methanotrophic response. However, these findings are the subject of debate 

(Joye et al., 2011; Kessler et al., 2011b). 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). 

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, 

2010f). In addition to dispersion being enhanced by artificial processes, oil my also be dispersed through 

natural processes. For example, microbial metabolism of crude oil results in the dispersion of oil (Bartha 
Description of the Environment and Impact Analysis 4-35 

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, 2010f). 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, 2010f). 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). A recent study 

assessed the impacts of COREXIT EC9500A on microbial communities from a beach impacted by the 

spill and suggested that hydrocarbon-degrading bacteria from an oiled beach were inhibited by chemical 

dispersants (Hamdan and Fulmer, 2011). There is other evidence that the dispersants worked in 

dispersing the oil at the wellhead in the case of the DWH event (USDOC, NOAA, 2010a; USEPA, 

2010f). 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 have 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). 

As part of the DWH response, the OSAT (2010) report analyzed results from water and sediment 

samples analyzed for dispersant-related chemicals collected from June through October 2010. Deepwater 

samples were analyzed for the dispersant-related chemicals 2-Butoxyethanol, DPnB, and propylene 

glycol. Screening levels exist for dispersant compounds in water only. The dispersant-related chemical 

measured predominantly in the deepwater zone was DPnB, with a benchmark for DPnB in water of 

1,000 μg/L (1 ppm). Of the 4,114 total water samples that were analyzed for dispersants in deep water, 

353 samples contained measurable amounts of DPnB. The range in detected DPnB concentrations was 

0.0170-113.4 μg/L (mean 4.3 μg/L), with all samples significantly below the chronic screening level. 

Peaks in DPnB detects were observed in two distinct layers, at the surface and in the subsurface 

(1,100-1,300 m; 3,609-4,265 ft), similar to distributions of exceedances of the aquatic life benchmark for 

PAH’s. Of 440 shelf water samples analyzed, there were no exceedances of dispersant-related chemical 

benchmarks. Approximately half of these samples did have detections of dispersant-related chemicals. In 

shelf sediment samples, there was only one detection of a dispersant-related chemical out of 243 samples. 

As a result of the use of subsea dispersants and natural dispersion, subsurface plumes of dispersed oil 

will likely occur near blowout sites in deep, offshore waters. During the DWH event, a subsurface oil and 

gas plume was first discovered in deep waters between ~1,100 and 1,300 m (3,609 and 4,265 ft) in early 

May 2010 (Diercks et al., 2010). 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, 2010b). 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 stabilized and were not low enough to be 

considered hypoxic (USDOC, NOAA, 2010c). The drop in oxygen, which did not continue over time, 

has been attributed to microbial degradation of the oil. Studies during the spill indicated that bacteria 

were degrading hydrocarbons from both gas and oil in the subsurface plume, with degradation rates 

varying based on time and location (Camilli et al., 2010; Hazen et al., 2010; Valentine et al., 2010). Over 

time, as the oil continued to degrade and diffuse, hypoxia became 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, 

2010). 
4-36 Central Planning Area Supplemental EIS 

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.” The top kill involved using a top kill mud mix that was primarily composed 

of barite, the heavy mineral used for its mass to hold pressure in the well string, as well as small amounts 

of other components for hydrate control (Boland, official communication, 2011). This top kill mud mix 

was really not a “drilling” mud at all, neither oil-based nor water-based, because there was no reason to 

have lubricating or other qualities needed for drilling, as it was simply for weighting to try to contain the 

blowout. This procedure was not successful and resulted in the release of some mud mix used for this 

operation. However, BOEM research has shown that drilling mud discharges do not move very far, even 

when discharged at the surface (CSA, 2006a). 

It is currently impossible to estimate precisely the long-term impacts that the spill from the DWH 

event will have on offshore water quality. The DWH event and resulting spill occurred in offshore waters 

and was of considerable magnitude. Various monitoring efforts and environmental studies are underway. 

Although response efforst decreased the fraction of oil remaining in Gulf waters and reduced the amount 

of oil contacting the coastline, oil still remains in the offshore environment, albeit at levels that were 

considered not actionable by the USCG (OSAT, 2010). As such, there is incomplete or unavailable 

information that may be relevant to reasonably foreseeable impacts on offshore water quality. This 

information is continuing to be collected and developed through the NRDA process. These data 

collection and research projects may be years from completion. Few data or conclusions have been 

released to the public to date. Regardless of the costs involved, it is not within BOEM’s ability to obtain 

this information from the NRDA process within the timeline of this Supplemental EIS. In light of this 

incomplete and unavailable information, BOEM subject-matter experts have used credible scientific 

information that is available and applied it using scientifically accepted methodology. Given the data 

samples that are available and described above, however, BOEM believes that this incomplete or 

unavailable information is not essential to a reasoned choice among alternatives. 

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.
Description of the Environment and Impact Analysis 4-37 

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 U.S. Environmental Protection Agency’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 BOEM’s planning area boundaries. The permit 

will expire on September 30, 2012. The USEPA’s 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’s 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, 2010h). 

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) 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, which 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 
4-38 Central Planning Area Supplemental EIS 

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 

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 and state that bilge and ballast water may only be 

discharged with an oil content of <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. 
Description of the Environment and Impact Analysis 4-39 

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 

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. Most of the oil spills that may 

occur as a result of the CPA proposed action are expected to be 1 bbl (Table 3-7). 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 
4-40 Central Planning Area Supplemental EIS 

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 into 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 

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 
Description of the Environment and Impact Analysis 4-41 

likely to reach sensitive shore areas (USEPA, 2010f). 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). 

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 

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 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. 
4-42 Central Planning Area Supplemental EIS 

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 would 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 

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 are usually 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 are usually 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 (Appendix B). Although response efforts may decrease the amount of 

oil in the environment, the response efforts may also impact the environment through, for example, 

increased vessel traffic and the application of dispersants. 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 
Description of the Environment and Impact Analysis 4-43 

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 

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, 2010g). 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 
4-44 Central Planning Area Supplemental EIS 

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 

produced water entering the Gulf per year to be 473,000 bbl, with a resulting oil and grease discharge of 

approximately 11,905 bbl per year (NRC, 2003, p. 200, Table D-8). 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. 

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 may 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 
Description of the Environment and Impact Analysis 4-45 

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, when compared with inputs from natural 

hydrocarbon inputs (seeps), coastal factors (such as erosion and runoff), and other non-OCS industrial 

discharges. 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. 

4.1.1.3. Coastal Barrier Beaches and Associated Dunes 

The BOEM 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 

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. 

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 the 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 
4-46 Central Planning Area Supplemental EIS 

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. 

Since the last NEPA 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 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 

Shoreline Cleanup Assessment Team (SCAT) maps and reports that are publicly available; newspaper 

interviews; scientific magazines; and public, State, and Federal resource agency Deepwater Horizon oilspill-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 

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, with a storm surge of 1-3 m (3-10 ft) that overtopped 

the beach. 
Description of the Environment and Impact Analysis 4-47 

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 Louisiana/Mississippi State boundary was exposed to oil. A year later 

(September 28, 2011), the shoreline was not identified by SCAT as showing oiling from the Chenier Plain 

to just east of the Rockefeller Wildlife Refuge and Game Preserve (LA State Highway 3147) (USDOC, 

NOAA, 2011b). 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 

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 
4-48 Central Planning Area Supplemental EIS 

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 (14.6 km2 to 6.5 km2) and then to 2.0 mi2 (5.2 km2) 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 oyster-shell 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 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 (Schales and Soileau, official 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). 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. (See Chapter 3.3.3, “OCS Sand Borrowing,” regarding berms constructed in 

Louisiana as part of the DWH response.) 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. 

Based on the review of currently available SCAT maps (USDOC, NOAA, 2011b) and field 

observations, the majority of the shoreline from the Atchafalaya Delta to the Mississippi River Delta are 
Description of the Environment and Impact Analysis 4-49 

either categorized as not oiled or with small areas (2.8 km; 1.8 mi) that have a mixture of no oil and 

lightly oiled (USDOC, NOAA, 2011b). 

Mississippi and Alabama Coasts 

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, 1979). 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 

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. 
4-50 Central Planning Area Supplemental EIS 

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. 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). Based on the review of the 

September 28, 2011, SCAT maps and observations (USDOC, NOAA, 2011b), no oil was observed along 

the Mississippi coastline, with the exception of small amounts of lightly oiled bayside beaches of the 

outer barrier islands of Ship, Horn, and Petit Bois. There were very small (less than a mile) areas of 

moderate oiling on the back side of both Horn and Petit Bois Islands; these beaches were cleaned. The 

September 28, 2011, SCAT maps and observations (USDOC, NOAA, 2011b) did not identify any oiled 

Alabama coastline. 

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 EIS, there remains incomplete and unavailable 

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, only select portions 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 

(USDOC, NOAA, 2011b). 

Initially, 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 the 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. Of this distance of moderately to heavily oiled shoreline, 158 km (98 mi) was in Louisiana 

and 18 km (11 mi) was 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 3 ft (1 m) 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 of the subsampling methods used by the teams. 

By comparison, the latest available SCAT observations (USDOC, NOAA, 2011b) note barrier islands 

from the Texas border to the Alabama/Florida border with much less remnant oil than was reported a year 
Description of the Environment and Impact Analysis 4-51 

ago (September 2010). Based on an additional review of current SCAT observation maps (USDOC, 

NOAA, 2011b), the remnant oil along these shorelines continues to be greatly reduced and is expected to 

be further removed through cleanup efforts, weathering, and the high-energy wave action in these areas. 

All of the following estimates of oiled shorelines were created from the measurement tool associated with 

the SCAT maps (USDOC, NOAA, 2011b). Based on these latest SCAT observations (September 28, 

2011) the Louisiana coast from the Texas State line (Sabine) to the Mississippi State line continues to 

improve. 

Observations on the Chandeleur Islands indicated no oil on the seaward side of the islands, a small 

area of moderate to heavy remnant oil on the back side of the islands, and a small heavily oiled area in the 

interior of the island (USDOC, NOAA, 2011b). Grand Isle still has a moderate oiling on the eastern tip 

of the island (USDOC, NOAA, 2011b). Grand Terre Island has either traces or is lightly oiled on its Gulf 

side, with the exception of a small area (approximately 33 m [108 ft]) that is still heavily oiled on the 

eastern end of the Island (USDOC, NOAA, 2011b). The Gulf Islands National Seashore chain (Cat, 

Horn, Petit Bois, etc.) off the Mississippi Gulf Coast is primarily free of remnant oil, except for a small 

segment that is lightly oiled (USDOC, NOAA, 2011b). While all of these coastlines previously received 

various degrees of oiling, the remnant oil that is currently observed is weathered oil that has been treated 

and has either no or much reduced toxic components. Because these coastlines encountered some degree 

of oiling, oil may now be part of the existing condition of the resource. As noted in the new SCAT 

observations, this oil is expected to continue to be removed from the shoreline by cleanup efforts, 

weathering, and the high-energy wave action in these coastal environments that continuously reworks the 

shoreline. The SCAT maps and new data available since the DWH event, which are incorporated into 

this Supplemental EIS, provide valuable information on the status of coastal barrier beaches and dunes 

that may have been impacted by the DWH event. 

As identified in this chapter, BOEM acknowledges that there remains incomplete and unavailable 

information related to coastal barrier beaches and associated dunes that may be relevant to reasonably 

foreseeable significant impacts on these resources. For example, although there is substantial information 

available since the DWH event included in this Supplemental EIS, additional information will likely be 

cultivated and developed through the NRDA process. The BOEM believes that the incomplete or 

unavailable information regarding coastal barrier beaches and dunes would likely not be essential to a 

reasoned choice among alternatives, particularly in the cumulative effects analysis. The bulk of this 

information is expected to be developed through the ongoing NRDA process. To date, relatively little 

raw data have been released publicly by the NRDA process, and it may be years before studies are 

completed and results are released. This information will certainly not be available within the timeframe 

contemplated in this Supplemental EIS. Regardless of the costs involved, it is not within BOEM’s ability 

to obtain this information from the NRDA process within the timeline of this Supplemental EIS. The 

BOEM subject-matter experts have used what scientifically credible information is available in their 

analyses, including the recent SCAT data, and applied this information using accepted scientific 

methodology. 

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. 
4-52 Central Planning Area Supplemental EIS 

Pipeline Emplacements 

Where a pipeline crosses the shoreline is referred to as a pipeline landfall. Many OCS Programrelated 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 OCS Program-related 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 

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 would 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 an earlier study 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). 

Remnant oil is still being found intermittently in coastal areas. This remnant oil has been treated with 

dispersants and weathered, but it has the potential for resuspension as a result of the routine activities 

noted above. If encountered, the remnant oil is expected to be nontoxic due to natural weathering, 

microbial breakdown, and post-spill dispersant treatments. In terms of water samples and sea surface 

observations, which had the last overflight reconnaissance of potentially recoverable oil on the ocean 
Description of the Environment and Impact Analysis 4-53 

surface and sampling event on August 3, 2010, the OSAT report made several conclusions (OSAT, 2010). 

The OSAT report concluded, based on samples tested since August 3, 2010, that no exceedances of the 

aquatic life benchmark for PAH’s that were fingerprinted as oil from the DWH event were found in 

nearshore waters. In addition, since August 3, 2010, no exceedances of the USEPA aquatic life 

benchmark for PAH’s in sediment beyond 3 km (~2 mi) of the wellhead were consistent with oil from the 

DWH event. Subsurface tar mats were found in some nearshore sampling areas, and they could 

temporarily be remobilized and could become a source of shoreline reoiling (OSAT, 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, and disturbance from routine activities is unlikely to 

significantly impact coastal barrier beaches and associated dunes. 

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 would 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 

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 (1987) found 

that OCS traffic in general comprises a relatively small percentage (~9%) 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 (3-4%). 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 
4-54 Central Planning Area Supplemental EIS 

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. 

The SCAT maps and new data available since the DWH event that are incorporated into this 

Supplemental EIS provide valuable information on the status of coastal barrier beaches and dunes that 

may have been impacted by the event. There remains incomplete and unavailable information that may 

be relevant to reasonably foreseeable significant impacts on these resources. Nevertheless, there is 

substantial information available since the DWH event included in this Supplemental EIS. The BOEM 

believes that the incomplete or unavailable information regarding effects of the DWH event on coastal 

barrier beaches and dunes would likely not be essential to a reasoned choice among alternatives. The 

bulk of this information is expected to be developed through the ongoing NRDA process. To date, 

relatively little raw data have been released publicly by the NRDA process, and it may be years before 

studies are completed and results are released. This information will certainly not be available within the 

timeframe contemplated in this Supplemental EIS. Regardless of the costs involved, it is not within 

BOEM’s ability to obtain this information from the NRDA process within the timeline of this 

Supplemental EIS. The BOEM subject-matter experts have used what scientifically credible information 

is available in their analyses and applied it using accepted scientific methodology. As noted above, even 

if there remain unknown impacts to coastal barrier beaches and dunes from the DWH event, impacts from 

routine activities related to the proposed action would not be expected to be substantial since most routine 

activities are located far from coastal beaches (e.g., vessel traffic) or would be subject to permitting and 

location siting requirements (e.g., dredging and pipeline landfalls). 

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. These dredging activities 

are permitted, regulated, and coordinated by COE with the appropriate State and Federal resource 

agencies. Impacts from these operations are minimal due to requirements for the beneficial use of the 

dredged material for wetland and beach construction and restoration where appropriate. Permit 

requirements further mitigate dredged material placement in approved disposal areas by requiring the 

dredged material to be placed in such a manner that it neither disrupts hydrology nor changes elevation in 

the surrounding marsh. Because these impacts occur regardless of the proposed action, the proposed 

action would account for a small percentage of these impacts from routine events. There could be a slight 

chance of disturbing or resuspending buried, remnant oil from the DWH event through channel 

maintenance or trenching associated with pipeline placement. However, based on sediment analyses in 

the OSAT report (2010), there were no exceedances of USEPA’s aquatic life benchmarks for PAH’s in 

sediment beyond 3 km (~2 mi.) from the wellhead that were linked to the oil from the DWH event. Since 

dredging, vessel traffic, and pipeline emplacement activities would be far removed from most affected 

areas, the chance of resuspension of toxic sediment would be improbable. 

Based on the findings of the OSAT-2 report (2011), weathered oil samples showed PAH’s were 

depleted by 86-98 percent in most beach locations. The PAH model predictions also predict that PAH 

concentrations in subtidal buried oil will decrease to 20 percent of current levels within 5 years (OSAT-2, 

2011). 
Description of the Environment and Impact Analysis 4-55 

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. A low-probability 

catastrophic spill is discussed in Appendix B. 

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 

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. 

Oil-Spill Impacts 

While it is possible that unweathered oil may reach shorelines, it not probable from the CPA proposed 

action. 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 conditions, if 

winds bring the oil shoreward. If the unweathered oil and its toxic components reached the fine and soft 

sediment beaches, the interstitial microfauna associated with the beach face may be affected. The effects 

could be changes in species diversity that could result in changes in forage areas for species using these 

microfauna as a food base (Teal and Howarth, 1984). 

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 there is sufficient distance and contributing weather 

conditions between the spill and landfall, the spill can be dispersed, thinned, and emulsified. This would 

allow for optimal conditions for biodegradation, volatilization, and photooxidation. Therefore, due to the 

distance from shore of the spill, the weather, the time oil remains offshore, and dispersant use (see 

discussion of dispersants in Chapter 3.2.1.5.2), offshore-based light Louisiana crude oil would be less 

toxic when it reaches the coastal environments. In addition, the GOM has more natural oil seeps 

(provides 400,000 bbl/yr) than any other marine environment in North America; therefore, the GOM has 

a resident population of microbiota, including oil-biodegrading bacteria, that are adapted to this 

environment and that rapidly respond to degrade any additional oil that enters the environment (Atlas and 

Hazen, 2011). The resiliency of coastal beaches and the effect of oil on these beaches are in part based on 

the toxicity of the oil’s components once it reaches the beaches. Recent insight into the fate of oil that 

may reach beaches from an offshore spill has been noted in the OSAT-2 report (2011). Based on the 

OSAT-2 report (2011), even the oil that reached the shore from the catastrophic DWH event was 

weathered to the point that no USEPA exceedances were observed for aquatic life or wildlife in the 

sediments or water samples from 3 km (~2 mi) from the wellhead shoreward (OSAT, 2010). Beach 

samples indicated a 86-98 percent depletion of total PAH and, in most locations, it was estimated that 

buried supratidal oil (most resilient due to no oxidation) would decrease to 20 percent of current levels 

within 5 years (OSAT-2, 2011). 
4-56 Central Planning Area Supplemental EIS 

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 

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 (Chapter 3.3.3). 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. 

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 photooxidation, 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). 

Through cleanup efforts, 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. Certain 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) have undergone 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 due to the distance of most OCS Program activities from barrier 

beaches, and sand removal during cleanup activities is expected to be minimized because current spillresponse activities discourage physical cleanup methods in beaches and marshes. Residual oils from the 

DWH event are still being cleaned in various locations. Based on the more recent SCAT information 

(September 2011), remnant oil on barrier and mainland beaches ranges from no oil/lightly oiled to only a 

few moderately oiled sites noted in sections above. The findings of the OSAT-2 report (2011) indicate 

that, in most beach locations, weathered oil samples showed PAH’s depleted by 86-98 percent. The PAH 

model predictions also showed that PAH concentrations in supratidal buried oil will decrease to 

20 percent of current levels within 5 years (OSAT-2, 2011). The report further noted that there was a 

greater potential for impact to wildlife and aquatic resources from aggressive cleanup than from the 

remnant oil on the beaches (OSAT-2, 2011). The Net Environmental Benefits Analysis, which was done 

as part of the OSAT-2 report (2011), noted that the environmental effects of residual oil remaining after 

cleanup are relatively minor when compared with the effects of continued cleanup efforts on both the 

beach habitats and associated resources. This is because, as both mechanical and manual methods are 

used to remove smaller amounts of oil, they are physically altering the state of the environment. 

The SCAT maps and new data available since the DWH event that are incorporated into this 

Supplemental EIS provide valuable information on the status of coastal barrier beaches and dunes that 

may have been impacted by the event. The BOEM acknowledges that there remains incomplete and 

unavailable information that may be relevant to reasonably foreseeable significant impacts on these 

resources. As there is substantial information available since the DWH event included in this 

Supplemental EIS, the Bureau of Ocean Energy Management believes that the incomplete or unavailable 
Description of the Environment and Impact Analysis 4-57 

information regarding effects of the DWH event on coastal barrier beaches and dunes would likely not be 

essential to a reasoned choice among alternatives. The bulk of this information is expected to be 

developed through the ongoing NRDA process. To date, relatively little raw data have been released 

publicly by the NRDA process, and it may be years before studies are completed and results are released. 

This information will certainly not be available within the timeframe contemplated in this Supplemental 

EIS. Regardless of the costs involved, it is not within BOEM’s ability to obtain this information from the 

NRDA process within the timeline of this Supplemental EIS. The BOEM subject-matter experts have 

used what scientifically credible information is available in their analyses and applied it using accepted 

scientific methodology. The likelihood of any accidental event reaching coastal barrier beaches remains 

remote due to the fact that most routine activities are far removed from coastal barrier beaches and dunes. 

Most activities that could result in inshore spills (e.g., vessel traffic) would also likely be in navigational 

channels at some distance from most barrier beaches and dunes. 

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 

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 (Table 3-7) are estimated to occur within Gulf 

coastal waters from activities supporting the CPA proposed action over the 40-year life of the lease sale, 

of which 44-114 of these spills are expected to be 1 bbl. The greatest risk of contact would be from an 

assumed 3,000-bbl spill should it occur within or near wetlands. The incremental increase in oil 

production from this proposed 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 

substantially 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 3.2.1.1 of the 2009-2012 Supplemental EIS. 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 10-16 percent (Chapter 3.2.1.1 and Figure 3-7 of the 

2009-2012 Supplemental 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 are discussed in Appendix B to the extent possible with the current data available. 

Summary and Conclusion 

Because of the proximity of inshore spills to barrier islands and beaches, inshore spills pose the 

greatest threat because of their concentration and lack of weathering by the time they hit the shore and 

because dispersants are not utilized in inshore waters due to the negative effects on the shallow-water 

coastal habitats. 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 (historical data indicate that coastal 

spills average <5 bbl; Table 4-13 of the Multisale EIS). Offshore-based crude oil would be less in 
4-58 Central Planning Area Supplemental EIS 

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, such as disturbance of sands through foot traffic and 

mechanized cleanup equipment (e.g., sifters), dispersal oil deeper into sands and sediments, and foot 

traffic in marshes, impacting the distribution of oils and marsh vegetation. Close monitoring and 

restrictions on the use of bottom-disturbing equipment would be needed to avoid or minimize those 

impacts. 

The BOEM 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). Although 

monitoring is still ongoing, the current data show that the toxic components of remnant oil is expected to 

continue to decline as noted above (OSAT-2, 2011). 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 proposed action will not pose a significant 

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. 

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 sediment reduction, 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 
Description of the Environment and Impact Analysis 4-59 

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 were 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. 

Lavoie et al. (2010) suggested that long-term monitoring of the berms and the associated habitats would 

be needed to determine both possible future impacts and benefits to the surrounding environment and if 

the berm is performing as proposed. Long-term monitoring should include a combination of repetitive 

surveys of bathymetry, topography, and seabed imagery, along with sediment sampling to determine 

changes through time that are needed for documenting the movement and degradation of oil. In addition, 

the study suggested that salinity and turbidity be monitored in the back barrier to provide general 

information on estuary health and the suitability for the continued existence of aquatic grass beds (Lavoie 

et al., 2010). 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 due to anthropogenic attempts to control catastrophic floods and change 

the natural environment to better accommodate navigation on waterways used to support OCS Program 

and non-OCS Program-related vessel traffic. Sea-level rise and coastal subsidence with tropical and 

extra-tropical storms exacerbate 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 
4-60 Central Planning Area Supplemental EIS 

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 and because no pipeline 

routes are planned that would involve emplacement on barrier islands. 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 could 

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 

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 would be increases in production wells over the 40-year period of OCS exploration 

because older wells would 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 vessel activities associated with the entire current 5-Year Program account 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 
Description of the Environment and Impact Analysis 4-61 

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 because response techniques discourage their use in coastal waters 

to protect habitat and species. 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. Favorable winds and currents could 

further diminish the volume of oil that might contact a beach. For example, 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. Based on current analysis associated with the DWH 

event, oil from offshore spills can lose much of its volatile and toxic components prior to onshore contact, 

which would render the residual beached oil to being low in PAH and other toxic compounds (OSAT-2, 

2011). The form of the residual oil (tarballs, supratidal buried oil, or surfzone submerged oil mats) could 

affect its rate of weathering and biodegradation. Some oil may 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. Long-term 

stressors, including physical effects and the chemical toxicity of hydrocarbons, could lead to decreased 

primary production, plant dieback, and further erosion (Ko and Day, 2004b). The OSAT-2 report (2011) 

found an 86-98 percent depletion of PAH’s in the weathered samples that were beached. The buried 

supratidal samples underwent less biodegradation due to lack of oxygen, but they were estimated to 

decrease to 20 percent of current levels within 5 years (OSAT-2, 2011). The weathered oils measured in 

the beach sediment did not surpass any USEPA exceedances for aquatic wildlife, and the National 

Environmental Benefits Analysis performed by the OSAT report (2010) determined that the residual oil 

remaining after cleanup efforts would be less damaging to the habitat and associated resources than 

continuing the cleanup effort. 

Protective measures such as berm building (as discussed in the river channelization and beach 

protection section in this chapter) to prevent oiling may further 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 
4-62 Central Planning Area Supplemental EIS 

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. 

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 of the newer superstructure designed to 

withstand major storms. To the extent that improperly abandoned and marked shallow-water wells exist 

in State waters, they may increase the potential for spills through vessel contact and leaks. Without closer 

monitoring and inspection by the states responsible for regulating State waters, the cumulative effect of 

the old improperly abandoned wells and infrastructure could potentially result in more frequent spills 

impacting barrier beaches and dunes. 

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 

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. 
Description of the Environment and Impact Analysis 4-63 

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, one 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 would continue to cause barrier beaches to narrow and breach. The CPA 

proposed action projects 0-1 pipeline landfall, and, in the event that a pipeline landfall occurs, there 

would likely be no effect to barrier islands due to permitting and siting requirements and current 

construction techniques. 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 SCAT maps and new data available since the DWH event that are incorporated into this 

Supplemental EIS provide valuable information on the status of coastal barrier beaches and dunes that 

may have been impacted by the event. The BOEM acknowledges that there remains incomplete and 

unavailable information that may be relevant to reasonably foreseeable significant impacts on barrier 

beachs and associated dunes. This incomplete or unavailable information includes potential data on the 

DWH event that may be forthcoming. As there is substantial information available since the DWH event 

included in this Supplemental EIS, BOEM believes that the incomplete or unavailable information 

regarding effects of DWH on coastal barrier beaches and dunes would likely not be essential to a 

reasoned choice among alternatives. The bulk of this information is expected to be developed through the 

ongoing NRDA process. To date, relatively little raw data have been released publicly by the NRDA 

process, and it may be years before studies are completed and results are released. This information will 

certainly not be available within the timeframe contemplated in this Supplemental EIS. Regardless of the 
4-64 Central Planning Area Supplemental EIS 

costs involved, it is not within BOEM’s ability to obtain this information from the NRDA process within 

the timeline of this Supplemental EIS. The BOEM subject-matter experts have used what scientifically 

credible information is available in their analyses and applied it using accepted scientific methodology. 

Compared with the historic and ongoing threats to coastal barrier beaches and dunes, such as development 

threats, natural factors such as hurricanes, and channelization, any remaining effects of the DWH event on 

coastal barrier beaches and dunes is expected to be small in comparison. 

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. 

4.1.1.4. Wetlands 

The BOEM 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 energy-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 a greater loss of wetland habitat than the rest of the Gulf Coast, 

primarily from sources unrelated to OCS energy production. Wetland loss is similarly 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. 
Description of the Environment and Impact Analysis 4-65 

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 

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 (Britsch and Dunbar, 1993), 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 (U.S. 

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 by 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 (Barras2006). 

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 
4-66 Central Planning Area Supplemental EIS 

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 

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. 

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 cause 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 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 (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. The portion of the Chenier Plain previously 

exposed to oil from the DWH event is currently identified as oil free, with no oil observed from the 

Texas/Louisiana border through the Atchafalaya Basin in Louisiana (USDOC, NOAA, 2011b). 

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. Further inland, extensive intermediate and freshwater marshes occur. In freshwater areas, cypresstupelo 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, 2007c). 
Description of the Environment and Impact Analysis 4-67 

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 (which is historically naturally occurring but which has been altered recently 

by anthropogenic actions) 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 actively 

building 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 shallow bay (America’s Wetland Resource Center 2011). 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 Gulf of Mexico. 

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. Based on the review of currently available 

SCAT maps (USDOC, NOAA, 2011b) and field observations, the majority of the shoreline from the 

Atchafalaya Delta to the Mississippi River Delta, with the exception of the Bay Jimmy, is currently either 

categorized as not oiled or with small areas (2.8 km; 1.8 mi) that have a mixture of no oil and lightly oiled 

(USDOC, NOAA, 2011b). In the Bay Jimmy area as described above in “General Existing Conditions of 

Louisiana Coastal Wetlands,” there are some remnants of heavy to moderate oiling in the fringe marshes 

along interior canals and inland cove shorelines of the backside and gulf side islands that form Bay 

Jimmy. Only some of the NRDA data is publicly available, and there are currently no publicly available 

NRDA data analyses or interpretations. Therefore, the effects of the oil exposure can only be discussed 

with publicly available data such as the OSAT and OSAT-2 reports (OSAT, 2010; OSAT-2, 2011) and 

publicly available independent research reports. 
4-68 Central Planning Area Supplemental EIS 

Findings of the OSAT and OSAT-2 reports (OSAT, 2010; OSAT-2, 2011) provide insight as to the 

condition of the weathered oil that reached the shoreline. The weathered samples collected showed a 

86-98 percent depletion of total PAH’s (OSAT-2, 2011). It was also noted that, since August 2010, there 

have been no USEPA exceedances for aquatic life benchmarks in sediment or water samples, including 

those samples taken near beaches and inland. Sediment contamination was limited to areas up to 3 km 

(~2 mi) from the wellhead of the DWH event (OSAT, 2010). In most locations, the modeling results 

indicate that PAH concentrations will decrease by 20 percent of their current level (OSAT, 2010). The 

DWH event was a deep-sea spill under high pressure; therefore, the oil released underwent rapid 

dispersion and dilution, so it was in a form available for biodegradation (Atlas and Hazen, 2011). Over 

40 percent of the oil was lost between the wellhead and the surface due to dissolution, mixing, and 

evaporation as it reached the surface. Surface oil analysis indicated that the volatile organic compounds 

were dissolved or evaporated before reaching shore (Atlas and Hazen, 2011). Even though the oil 

reaching vegetated shorelines had been greatly reduced in toxicity, the lack of oxygen in marsh soils may 

require a longer time for complete weathering through biodegradation to occur. 

Oiled shorelines along Bay Jimmy in Barataria Bay and the Birdsfoot Delta of the Mississippi River 

were evaluated for effects related to the DWH event (Koklay et al., 2011). Findings of this study indicate 

that the Bay Jimmy area was dominated by Spartina alterniflora and Juncus roemerianus marsh grasses, 

which are both short in height and susceptible to being fully oiled depending on tidal conditions (Koklay 

et al., 2011). The average inland or “oil-damage penetration zone” in this area extended inland to 6.7 m 

(22 ft); however the maximum “oil-damaged penetration zone” was up to 19 m (62 ft) inland in some 

areas. In Barataria Bay, oil effects on vegetation ranged from lightly oiled sections of stems to oildamaged canopies. There were also broken stems due to incoming surface oil on higher tides (Koklay et 

al., 2011). In the Birdsfoot Delta, the predominant marsh grass is taller and less susceptible to complete 

oiling; thus, vegetative damage appears minimized. Indicators of both further degradation and recovery 

were seen at both Barataria Bay and the Birdsfoot Delta. Some wetlands showed great reductions in live 

vegetation and evidence of sediment erosion. However, in other wetlands, damaged zones had signs of 

growth and recovery. This was evident with regrowth of vegetation of up to 10 percent of the area 

assessed (Koklay et al., 2011). Further study is being initiated to determine if the underground root mass 

sustains a more complete recovery of these marshes. 

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 

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 (29,137 ha) 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 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 
Description of the Environment and Impact Analysis 4-69 

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 ac (15,625 mi2

) of marshes in the 1780’s dwindling to approximately 4 million ac (6,250 mi2) 

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 in coastal Mississippi reflect this 

discrepancy in habitat with losses of 64,000 ac (100 mi2

) of salt marsh and only 800 ac (1 mi2) of fresh 

marsh (Swann, 2010). In Alabama approximately 15,000 ac (23 mi2

) of salt marsh was lost as opposed to 

11,000 ac (17 mi2

) of fresh marsh. Based on historical records Alabama had approximately 7.6 million ac 

(11,875 mi2

) of marsh in the 1780’s and by the 1980’s was left with 3.6 million ac (5,625 mi2) 

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 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 to 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 by October 

2010. 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 2010 report date, but 114 mi (183 km) of light to traces of oil were found 

along the Alabama shoreline at that time. Based on the review of the September 28, 2011, SCAT maps 

(USDOC, NOAA, 2011b) and observations, no oil was observed along the Mississippi coastline, with the 

exception of small amounts of lightly oiled bayside beaches of the outer barrier islands of Ship, Horn, and 

Petit Bois. There were very small (less than a mile) areas of moderate oiling on the back side of both 

Horn and Petit Bois Islands; these beaches were cleaned. The September 28, 2011, SCAT maps 

(USDOC, NOAA, 2011b) and observations are likewise not identifying any Alabama coastline as 

showing any oiling. While NRDA findings are still not publicly available, there is now more known 

about the fate and condition of this oil based on the OSAT and OSAT-2 reports (OSAT, 2010; OSAT-2, 
4-70 Central Planning Area Supplemental EIS 

2011). These reports noted that, since August 2010, there have been no exceedances for USEPA aquatic 

life benchmark for PAH’s in either sediments or water sampled at distances >3 km (~2 mi) from the 

DWH wellhead (OSAT, 2010). In addition, it was noted that 86-96 percent of the total PAH’s was 

depleted during the weathering process while being transported to shore (OSAT-2, 2011). 

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. 

Deepwater Horizon Event 

Another factor that is now superimposed on the hurricane damage is the currently unknown, longterm effect of the oil spill from the DWH event. 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. A review of the current SCAT maps 

(USDOC, NOAA, 2011b) indicate that the coastline from the Louisiana/Texas State line (Sabine) to 

Panama City, Florida, continues to improve and is being categorized as shoreline with no oiling to lightly 

oiled, with the exception of the Bay Jimmy area in southeastern Louisiana. From Cameron, Louisiana, 

east to Terrebonne Bay, there was either no oil or small patches of light oiling along the Isle Dernieres 

and the Terrebonne Bay shoreline. There were also small patches of marsh in Terrebonne Bay that were 

lightly oiled. Moving farther east, the shoreline adjacent to Barataria Bay only had trace to light oiling 

observed, with the exception of the initially heavily oiled Bay Jimmy area. The marsh fringe on the back 

side of the two large gulfward islands forming the entrance to Bay Jimmy are currently not oiled to lightly 

oiled. Approximately 2 km (1.2 mi) of the shorelines along the interior canals of these islands are still 

categorized as heavily oiled and are currently undergoing evaluation for further cleaning (USDOC, 
Description of the Environment and Impact Analysis 4-71 

NOAA, 2011b). The island forming the western shore of Bay Jimmy varies from having no observed oil 

to having observations of light to very light oil, and it only has small patches of moderate to heavily oiled 

shoreline. Approximately 1.6 km (1 mi) of marsh bordering the eastern cove of the island that creates the 

back side of Bay Jimmy also remains heavily oiled (USDOC, NOAA, 2011b). The oil penetration in 

these marshes is estimated to be 5.5 m (18 ft) inland (Kokaly et al., 2011). While the SCAT maps 

graphically depict 5.7 km (3.5 mi) of shoreline as heavily oiled, in most cases, this represents only the 

area surveyed and not necessarily the total amount of area oiled. 

As noted above, BOEM recognizes that there remains incomplete and unavailable information related 

to wetlands, including impacts from the DWH event. Here, BOEM concludes that the unavailable or 

incomplete information may be relevant to foreseeable significant adverse impacts to wetlands. Relevant 

data on the status of wetlands and marshes after the DWH event may take years to acquire and analyze, 

and impacts from the DWH event may be difficult or impossible to discern from other factors. The 

NRDA process is ongoing, and to date much of the information collected as part of the process has not 

been fully analyzed and conclusions have not been released to the public. It may be years before NRDA 

data and conclusions are available. Therefore, it is not possible for BOEM to obtain this information 

within the timeframe contemplated in this Supplemental EIS, regardless of the cost or resources needed. 

In light of the incomplete or unavailable information, BOEM subject-matter experts have used available 

scientifically credible evidence in this analysis, based upon accepted scientific methods and approaches. 

Nevertheless, BOEM believes that incomplete or unavailable information regarding heretofore unknown 

effects of the DWH event on wetlands and marshes is not essential to a reasoned choice among 

alternatives in the cumulative effects analysis. Although there may still be incoming information, there is 

significant available data on shoreline oiling and the current status of wetlands and marshes from the 

SCAT and ERMA databases that have assisted BOEM subject-matter experts in their analyses. Future 

incoming data are not expected to significantly alter these conclusions, and future impacts are not 

expected. 

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. 

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 

in the event of disturbed 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 include dredging, 

waste disposal, trenching associated with pipeline emplacement, entrainment and shallow-water vessel 

traffic. 

Pipeline Emplacement 

For the CPA proposed action, there would be 390-1,162 km (241-722 mi) of installed pipeline in 

Federal waters (Table 3-3). 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 
4-72 Central Planning Area Supplemental EIS 

Louisiana Coastal Permit Program in 1981, have caused direct landloss averaging between 2.5 ha/yr 

(10 ac/yr) and 4 ha/yr (16 ac/yr) 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. 

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 in Federal waters. The recent OSAT report (OSAT, 2010) found that there was no 

evidence of toxic components of oil (such as PAH’s or dispersant chemicals) in the sediments that 

exceeded USEPA’s aquatic life benchmarks in sediments (in either offshore or coastal waters). 

Therefore, the potential one pipeline landfall estimated for the CPA proposed action would not be 

expected to resuspend contaminants in these areas. 

Dredging 

Maintenance dredging of navigation channels and canals is expected to occur with minimal impacts 

except in areas that have been previously contaminated. However, the proposed action is expected to 

only contribute minimally to the need for this dredging. As described below, <10 percent of traffic using 

navigation channels in the GOM is related to the OCS Program (Tables 3-36 and 4-4 of the Multisale 

EIS). Thus, vessel traffic related to the proposed action is only a small portion of the traffic that would 

require maintenance dredging of channels. Alternative dredged-material disposal methods can be used to 

enhance and create coastal wetlands after the 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. 

The COE’s New Orleans District annually removes approximately 46-53 million m3

(60-70 million yd3

) of dredged material from 10 Federal navigational channels throughout coastal 

Louisiana. Approximately 12,000,000 million m3

 (16 million yd3), or 26 percent, of this material is used 

for coastal wetland restoration projects (Creef, official communication 2011). 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 dredged material, 

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 environments and associated 

fish and wildlife that use these areas for nursery grounds and protection. These impacts may include 

increased erosion rates, turbidity, and changes in salinity. Many of these impacts are reduced through the 

use of modern disposal practices. Maintenance dredging of navigation channels deposits material on 

existing disposal banks and areas. The current COE policy for dredged-material placement associated 

with channel maintenance is to either utilize the dredged material for marsh creation or restoration in the 

adjacent open waters along the navigation canals or to use alternate bank disposal to maintain the existing 

hydrological connections within the marsh (Creef, official communication, 2011). These dredge 
Description of the Environment and Impact Analysis 4-73 

management practices are expected to remain in effect for the duration of the CPA proposed action, and 

drainage is expected to continue unchanged, except if there is 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 

area. The dredged sediments are released into the area specified for disposal. This method usually 

produces positive topographic relief in the placement area, although the effects may often be temporary. 

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 to accelerate 

marsh erosion and conversion to open water (Turner and Cahoon, 1987; Rozas, 1992; Turner et al., 1994; 

Kuhn et al., 1999). 

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. Findings of the OSAT report (OSAT, 

2010) indicate that sediment and water toxicity associated with remnant oil in these coastal areas is 

minimal and does not exceed USEPA’s benchmarks for aquatic life. Three types of oil residue (supratidal 

buried oil, small surface residue balls, and submerged oil mats) were examined and evaluated in a report 

prepared by the Operational Science Advisory Team (OSAT- 2, 2011) and submitted to the Gulf Coast 

Incident Management Team. Their findings indicated that the oil residues were well weathered and 

showed a 86-98 percent depletion of total PAH’s. The PAH’s are one of the more toxic components of 

oil and can weaken marsh sediment by eliminating interstitial fauna. In addition, the marsh plants uptake 

these toxins from the soils where they are now available to the portion of the food chain that utilizes 

marsh plants in their diets. They also noted that, due to the effects of weathering, biodegradation, and the 

location of the buried oil, there would be a minimal risk of leaching from supratidal buried oil. Based on 

modeling information, PAH concentration of buried oil in most locations will decrease by 20 percent 

within 5 years. In some isolated conditions, the PAH’s could persist longer (OSAT-2, 2011). As such, 

BOEM believes that maintenance dredging operations that may be related to vessel traffic from the 

proposed action would result in negligible impacts to wetland habitat due to the extensive weathering of 

oil residues in the dredged sediments. 

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, 1987; 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 
4-74 Central Planning Area Supplemental EIS 

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) 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/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. 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/yr (741 ac/yr) of landloss. 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 

BOEM- 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. 

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 disposal. 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 
Description of the Environment and Impact Analysis 4-75 

facilities in wetlands. Any impacts upon wetlands are mitigated in accordance with Clean Water Act 

requirements and the Corps 404 permit and State permitting programs.

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). These methods may 

include selective placement of the pipelines in existing rights-of-way, directional drilling to route under 

rather than through wetlands, push-pull pipe installation, and new restoration and revegetation methods. 

The BOEM 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) of 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 most 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. 

On average, 9 percent of traffic using 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 3-4; and Table 4-6 of the Multisale EIS), the proposed action is 

expected to contribute 3-4 percent of the total OCS Program usage of navigation channels. So, the 

proposed action would contribute 0.2-0.4 percent to the total commercial traffic using these navigation 

channels. All estimated navigational use is expected to contribute approximately 1.5 m/yr (4.9 ft/yr) to 

the widening to the roughly 2,000 km (1,243 mi) of unarmored navigation channels used by OCS 

Program-related vessels, or about 300 ha/yr (741 ac/yr), of landloss per year (Johnson and Gosslink, 

1982). An evaluation of landloss rates suggests that landloss related to navigation channel usage had 

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). 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), and widening rates have slowed based on maintenance 

techniques. The reduced percentage of vessel traffic, in combination with armoring and regular 
4-76 Central Planning Area Supplemental EIS 

maintenance along the waterways, should minimize the impacts related to vessel traffic from the CPA 

proposed action. 

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 could cause the 

loss of 0-8 ha (0-20 ac) of wetlands habitat. It is expected that these impacts would be reduced or 

eliminated 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 for accidental events that would affect wetlands are 

oil spills. 

With the reduced protection of the barrier islands lost due to hurricanes and anthropogenic factors, 

there is a greater potential for the oiling of coastal wetlands during an accidental event. Both coastal and 

offshore oil spills can be caused by large tropical cyclone events such as Hurricanes Katrina, Rita, 

Gustav, and Ike. 

Areas of the Louisiana coast have been further stressed through shoreline oiling associated with the 

DWH event. While extensive areas 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., DWH event spill), are not 

expected to significantly damage any wetlands along the Gulf Coast. See Appendix B for an analysis of 

impacts from a low-probability catastrophic spill event. 

It must be noted that, even with offshore spills, the degree of coastal impact is a function of the source 

oil type (e.g., Macondo involved a light crude 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. 

Primary Impacts of Oil Spills 

While there are concerns that offshore spills may contribute to wetland damage, the distance of these 

production facilities from the wetland makes the probability of toxic oil reaching coastal wetlands low. 

With the DWH event, which was a catastrophic spill, the OSAT report (2010) noted that contamination 

for both toxic hydrocarbon components (including PAH’s and alkanes) and dispersant related chemicals 
Description of the Environment and Impact Analysis 4-77 

were limited to within an approximate 3 km (~2 km) radius of the wellhead. There were no EPA 

exceedances for aquatic wildlife in either sediments or water samples beyond the 3 km (~2 mi) distance 

from the DWH wellhead in the affected areas sampled (OSAT, 2010). 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, as 

well as wetland habitats elsewhere. Often, seemingly contradictory conclusions are generated from these 

impact assessments. These contradictions can be explained by differences in 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 Environmental Sensitivity Indices, (ESI) 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 long-term 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 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/m2 (0.026 gal/10.76ft2

). Concentrations less than this typically 

cause dieback of the aboveground vegetation for one growing season, but limited mortality (Alexander 

and Webb, 1987). 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 depending on types of soil nitrogen and oxygen 

availability. 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 could 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. 

A current study associated with the DWH event notes that there is evidence of recovery within 1 year 

after the spill, with shoot production in heavily oiled areas along the Louisiana coast (Delaune and 

Wright, 2011). This recovery held true in heavily oiled areas where the stems of and leaves of the marsh 

vegetation were oiled, although depending on vegetation type amount of recovery varied (Delaune and 

Wright, 2011; Kokaly et al., 2011). Kokaly et al. (2011) noted oiling and, to some degree, the rate of 

recovery in their comparative study of oiling in the Mississippi Birsdfoot Delta and Bay Jimmy in 

Barataria Bay. They examined species and the height of marsh vegetation, as well as water level 

fluctuation, marsh damage, and amount of recovery. In the Birdsfoot Delta the predominant marsh grass 

is tall and less susceptible to being completely oiled thus damage is minimized. However, Bay Jimmy is 

dominated by Spartina alterniflora and J. roemerianus marsh grasses are both short in height and 

susceptible to being fully oiled depending on tidal conditions. While inshore penetration of oil was 
4-78 Central Planning Area Supplemental EIS 

further inland at Bay Jimmy than the Birdsfoot Delta site, the study found indicators of further 

degradation and recovery at both sites after one year with little to no remediation (Koklay et al., 2011). 

Some areas showed great reductions in live vegetation and evidence of sediment erosion. While in other 

areas at these sites, damaged zones had signs of growth and recovery, with regrowth of vegetation 

identified in up to 10 percent of the areas assessed (Koklay et al., 2011). 

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 Louisiana 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 S. alterniflora marsh grass 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 (official 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. These 

findings were further documented by Koklay et al. (2011) in the comparative study of the Birdsfoot Delta 

and Bay Jimmy discussed in the previous paragraph. 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. 

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 that 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 

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 
Description of the Environment and Impact Analysis 4-79 

benefits of cleaning. The compaction of the soil, in combination with the oiling, may further stress the 

plants and result in greater 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 

ecologists 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 as follows: (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 weathered oils measured in the sediments and reported in the OSAT report (2010) did not 

surpass any USEPA exceedences for aquatic wildlife benchmarks, and the National Environmental 

Benefits Analysis performed by OSAT determined that the residual oil remaining after cleanup efforts 

would be less damaging to the habitat and the resources using them than continuing the cleanup effort. 

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). A study (Nyman and Patrick, 1996) involving fertilization, dispersant, and 

chemical cleaning of fresh marshes indicated that, while oil was removed from the plant or site, no longterm enhancement resulted from utilizing any of these response methods. There was no indication of 

decreased soil respiration from the cleaning methods noted above, and all three cleaning methods 

temporarily lowered the soil Eh, which indicated that these response options stimulated the already 

adapted soil microbial community to biodegrade the oils. Both the light crude (DWH surrogate) and 

heavier crude used in this study lowered soil Eh, therefore confirming that these oils stimulated the soil 

microbial community and initiated biodegradation as long as the soils remain oxygenated. 
4-80 Central Planning Area Supplemental EIS 

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. 

The increase in oil production from this proposed 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 proposed lease sale would cause a negligible increase 

in the risk of a large spill occurring and contacting wetlands. If oil should reach the wetlands from this 

distance, it would likely be sufficiently weathered and detoxified through biodegradation, mixing, and the 

weathering process by the time it reached shorelines. The probabilities of an offshore spill ≥1,000 bbl 

occurring and contacting environmental features are described in Chapter 3.2.1.1.1. In addition, the 

results of a risk analysis estimating the likelihood of a <1,000 bbl occurring and contacting environmental 

resources (including wetlands) can be found in Chapters 3.2.1.2 and 3.2.1.3. Eight parishes in Louisiana 

have a chance of a spill ≥1,000 bbl occurring and contacting their shores. For these parishes, the 

probability of an OCS offshore spill ≥1,000 bbl ranges from <0.5 to 8 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 3-8 percent (Figure 4-14 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. A few (5-11) 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 (Table 3-5). 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 wetland, oiling is expected to be light. The potential 

impacts of a catastrophic spill such as the DWH event is discussed in Appendix B to the extent possible 

with the current data available. However the probability of a catastrophic spill such as the DWH event is 

low. If a catastrophic spill such as the DWH event should occur, the extent of the oiling may vary 

depending on sea conditions, dispersant use, and response time and methods. As seen with the DWH 

event, physical alterations to hydrological conditions through berm construction may result in changes to 

future barrier island behavior. (See Chapter 3.3.3, “OCS Sand Borrowing,” regarding berms constructed 

in Louisiana as part of the DWH response). The end result of island modification as a result of changed 

hydrologic conditions due to berm construction will only be known through the results of long-term 

monitoring. 

Summary and Conclusion 

Offshore oil spills resulting from the CPA proposed action would have a low probability of 

contacting and damaging any wetlands along the Gulf Coast, except in the case of a catastrophic event 

(Appendix B). This is because of the distance of the spill to the coast, the likely weathered condition of 

oil (through evaporation, dilution, and biodegradation) should it reach 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 nearshore vessel accident or pipeline rupture. Wetlands in the northern Gulf of Mexico are 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. 
Description of the Environment and Impact Analysis 4-81 

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 

The main factors that cumulatively affect wetlands from are dredging, navigation channels and 

canals, pipelines, oil spills, and the development of wetlands. The contribution of the OCS Program and 

the proposed action’s activities to these cumulative impacts remains small. 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 

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 

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 Program-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. 

There are 10 Federal channels totaling 2,000 km (1,243 mi) that are used in support of OCS Program 

activities (Chapter 4.5.3.2 of the Multisale EIS). Out of these 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 BOEM has used a widening rate for OCS Program-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 Program-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. On average, 12 percent of traffic using OCS-related navigation channels is 

related to the OCS Program (Tables 3-36 and 4-4). Based on the numbers of service-vessel trips 

projected for the proposed action and the OCS Program (Tables 4-3 and 4-6), the CPA proposed action is 

expected to contribute 2.5-4.1 percent of the total OCS Program usage; therefore, the proposed action 

would contribute 0.3-0.5 percent to the total commercial traffic using these navigation channels (USDOI, 

MMS, 2007c). 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 
4-82 Central Planning Area Supplemental EIS 

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 exposed both inland and offshore navigation channels to treated 

oil. This exposure could result in submerged oil mats in certain areas of coastal waters; however, these 

submerged oil mats were found nearshore and not necessarily in coastal navigation channels (OSAT, 

2010). Further sampling associated with this and other studies concerning the DWH event reported no 

exceedances of USEPA’s benchmarks for aquatic life, including total PAH’s, beyond 3 km (~2 mi) from 

the wellhead (OSAT, 2010; Atlas and Hazen, 2011). Therefore, even if submerged oil mats or residual 

oil were to be encountered during the proposed action, the impact would be minimal to none. Additional 

information on the condition of the oil resulting from the DWH event will be made publicly available as 

the NRDA assessment process progresses and analyses are completed. Dredging in these areas could 

resuspend remnant oiled sediments, but these sediments are not expected to be toxic. This is because of 

dispersant treatment, weathering, and natural biodegradation that occurred. 

Impacts from State onshore oil and gas activities are expected to occur as a result of dredging for new 

canals, maintenance, the usage of existing rig access canals and drill slips, and the 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 northwest-southeast 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 OCS Program-related navigation channels accounts for 10 percent of the 

dredged material produced. 

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 

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, Canals, and Coastal Infrastructure 

The effects of pipelines, canal dredging, and 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 
Description of the Environment and Impact Analysis 4-83 

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. The proposed action may include 3-18 new onshore pipeline facilities, other than 

pipelines (26-39 landfalls) that could be constructed in wetlands for the estimated life time (40 years) of 

the proposed action (Table 4-9 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 Program-related direct landloss is estimated to be from pipelines 

(Turner and Cahoon, 1987). Since the beginning of OCS Program 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 Program-related 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 Program-related pipeline canals does not appear to be an important factor 

contributing to OCS-related 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 Program 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 Program-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 contributed to significant habit changes. Through proper 

construction methods, mitigation and maintenance, impacts can be minimized or altogether avoided. The 

BOEM is not a permitting agency for onshore pipelines. The permitting agency would be COE and the 

State in which the activity has or 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, regardless of the source. This creates the 

greatest concern for coastal wetlands depending on the spill’s proximity to these vegetated areas. The 

potential for vessel contact with improperly marked and abandoned wells in State nearshore waters could 
4-84 Central Planning Area Supplemental EIS 

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 OCS Program and State oil and gas platforms and pipelines, 

will continue to be a 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 Program-related 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 Program-related coastal spills are provided in Chapter 4.3.1.7 of the 

Multisale EIS. Non-OCS Program-related 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. 

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 Program-related activity. Of the 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 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). One offshore spill >1,000 bbl 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. 
Description of the Environment and Impact Analysis 4-85 

The DWH event was the largest spill recorded in the GOM and resulted in the oiling of an extensive 

portion of the Gulf Coast shoreline from east of the Texas/Louisiana 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 and its contribution to 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). In their review of available literature on oil impacts 

in Gulf Coast wetlands, DeLaune and Wright (2011) found that marsh vegetation, under most conditions, 

will recover naturally after exposure to oil, without receiving enhanced oil cleanup treatments. The 

recovery rate will depend on the amount of oiling, penetration of oil into the soil profile, and the 

sensitivity of a particular plant or the plant’s vulnerability (height) to oil or depth of oiling. 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. 

Periodic Wetlands Loss 

It was estimated in 2000 that coastal Louisiana would continue to lose land at a rate of approximately 

44 km2

/year (17 mi2/year) over the next 50 years. This would be expected to result in an additional net 

loss of 1,326 km2

 (512 mi2) by 2050 and represents approximately 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 openwater 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 open-water 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 (see also U.S. Dept. of the Army, COE, 2004a). 

Development in Wetlands 

The development of wetlands for agricultural, residential, and commercial uses would continue with 

more regulatory and planning constraints. 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. 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. 
4-86 Central Planning Area Supplemental EIS 

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 

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 Katrina and Rita in 2005, the demand for large quantities of earthen 

construction materials for hurricane-protection levee construction or restoration resulted in either 

removing or damaging marginal wetlands that could be highly productive. These wetland damages are 

required to be mitigated through the COE regulatory process, which means that wetland functions are 

restored preferably either on the impacted site or that wetland functions are restored at secondary 

locations. 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 tend to be 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 and weather conditions, and the implementation of a timely and 

appropriate spill-response effort. 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, the loss attributed to the proposed action would also be minimal. The CPA proposed 

action would not require any channel maintenance destined from that attributable to all vessel traffic 

regardless of source; 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 to the extent 

practicable. Disposal of OCS wastes and drilling by-products would be delivered to existing facilities. 

Because of existing capacity and the location of infrastructure, no additional expansion into wetland areas 

is expected. 
Description of the Environment and Impact Analysis 4-87 

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 to minimize 

future impacts. 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, 2007c). 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 due to natural factors and 

anthropogenic activities. 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 in light of these other natural and non-OCS Program 

related factors. 

4.1.1.5. Seagrass Communities 

The BOEM 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 

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 
4-88 Central Planning Area Supplemental EIS 

investigated include BOEM, 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). 

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 
Description of the Environment and Impact Analysis 4-89 

(USDOC, NOAA, 2010e). There is the potential for significant shifts in community structure, but the 

current health of the community in unknown. It is expected 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 through the NRDA process 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. To date, the NRDA process 

is incomplete, and it may be years before these data and conclusions are released to the public. 

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, 

2010e). The current health of the system is unknown, and research is being conducted through the NRDA 

process to assess the effects from the DWH 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 & 

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, 2010e). At this 

time, it is believed 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, 2010e). 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. 

As noted above, there remains uncertainty regarding the impacts of the DWH event on submerged 

vegetation. Although the information remains incomplete or unavailable, it appears that the majority of 

submerged vegetation beds in Florida were not significantly impacted and that the baseline for this 

submerged vegetation remains roughly the same after the DWH event. Submerged vegetation in 

Louisiana, Mississippi, and Alabama may have been more significantly impacted. As such, at least for 
4-90 Central Planning Area Supplemental EIS 

submerged vegetation in Louisiana, Mississippi and Alabama, this incomplete or unavailable information 

may be essential to a reasoned choice among alternatives. Nevertheless, the ongoing research on 

submerged vegetation after the DWH event is being conducted through the NRDA process. These 

research projects may be years from completion, and data and conclusions have not been released to the 

public. Regardless of the costs involved, it is not within BOEM’s ability to obtain this information from 

the NRDA process within the timeline of this Supplemental EIS. In light of this incomplete and 

unavailable information, BOEM subject-matter experts have used credible scientific information that is 

available and applied it using scientifically accepted methodology. 

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. The proposed action, 

however, is only likely to result in 0-1 pipeline landfalls. Pipelines are heavily regulated and permitted, 

and they are likely to be required to be sited away from submerged vegetation. 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, and no new canals are expected to be required for the proposed action. In Louisiana, some 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. 

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 
Description of the Environment and Impact Analysis 4-91 

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 require pipeline routes that avoid high-salinity beds, as well as reduce and 

maintain water turbidity within tolerable limits for submerged vegetation. Most activities would use 

existing inshore structures, so less than one pipeline would make landfall under the proposed action. 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 significance 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 nearshore 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. 

Summary and Conclusion 

Routine OCS activities in the CPA that may impact seagrasses are not expected to significantly 

increase in occurrence and range in the near future. Requirements of other Federal and State programs, 

such as avoidance of the seagrass and vegetation communities or the use of turbidity curtains, reduce 

undesirable effects on submerged vegetation beds from dredging activities. Federal and State 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 and implemented programs, along with the beneficial effects of natural flushing (e.g., from 

winds and currents), any potential effects from routine activities on submerged vegetation in the CPA are 

expected to be localized and not significantly adverse. 

As noted in the affected environment section above, there remains uncertainty regarding the impacts 

of the DWH event on submerged vegetation. At least for submerged vegetation in Louisiana, Mississippi, 

and Alabama, BOEM cannot definitively determine that the incomplete or unavailable information being 

developed through the NRDA process would not be essential to a reasoned choice among alternatives. 

Nevertheless, the ongoing research on submerged vegetation after the DWH event is being conducted 

through the NRDA process. These research projects may be years from completion, and data and 
4-92 Central Planning Area Supplemental EIS 

conclusions have not been released to the public. Regardless of the costs involved, it is not within 

BOEM’s ability to obtain this information from the NRDA process within the timeline of this 

Supplemental EIS. In light of this incomplete and unavailable information, BOEM subject-matter experts 

have used credible scientific information that is available and applied it using scientifically accepted 

methodology. Nevertheless, any additional impacts to submerged vegetation from routine activities of the 

proposed action are expected to be minimal due to the distance of most activities from the submerged 

vegetation beds and that the 0-1 pipeline landfall and maintenance dredging are heavily regulated and 

permitted, and that mitigations (such as turbidity curtains and siting away from beds) may be required. 

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; such low-probability catastrophic spills are addressed in 

Appendix B.

The risk of an offshore spill 1,000 bbl occurring and contacting coastal counties and parishes was 

calculated by BOEM’s oil-spill trajectory model (Chapter 4.3.1.5 of the Multisale EIS). 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 

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 
Description of the Environment and Impact Analysis 4-93 

waves, storms, or vessel traffic breaks apart the surface oil sheen and disperses some oil into the water 

column or mixes 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 available since the DWH event and that is 

about the current state of the submerged vegetation from Louisiana, Mississippi, Alabama, and Florida is 

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 are expected to continue to 

improve and will decrease the detrimental effects to submerged vegetation from the CPA proposed action. 

As noted above in the affected environment section above, there remains uncertainty regarding the 

impacts of the DWH event on submerged vegetation. At least for submerged vegetation in Louisiana, 

Mississippi, and Alabama, BOEM cannot definitively determine that the incomplete or unavailable 

information being developed through the NRDA process may be essential to a reasoned choice among 

alternatives. Nevertheless, the ongoing research on submerged vegetation after the DWH event is being 

conducted through the NRDA process. These research projects may be years from completion, and data 

and conclusions have not been released to the public. Regardless of the costs involved, it is not within 

BOEM’s ability to obtain this information from the NRDA process within the timeline of this 
4-94 Central Planning Area Supplemental EIS 

Supplemental EIS. In light of this incomplete and unavailable information, BOEM subject-matter experts 

have used credible scientific information that is available and applied it using scientifically accepted 

methodology. Nevertheless, impacts to submerged vegetation from an accidental event related to the 

proposed action are expected to be minimal due to the distance of most activities from the submerged 

vegetation beds and that the likelihood of an accidental event of size, location, and duration reaching 

submerged vegetation spills remains small. 

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. Maintenance dredging and vessel traffic 

related to the proposed action remains a subset of all dredging and traffic issues from all sources in the 

Gulf. 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. Mitigation may be 

required to reduce undesirable impacts of dredging to submerged vegetation. Maintenance dredging of 

navigation channels helps sustain 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 sediment-
Description of the Environment and Impact Analysis 4-95 

laden 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, 

1987). 

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 

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 bedsThe combined influences from the implementation of proposed lease sale 

stipulations, the current mitigation policies in place, and the natural flow regime along with the small 

probablility of an oil spill are expected to further reduce the incremental contribution of stress from the 

CPA proposed action on submerged vegetation. 

Unavailable information on the effects to submerged vegetation from the DWH event (and thus 

changes to the submerged vegetation baseline in the affected environment) makes an understanding of the 
4-96 Central Planning Area Supplemental EIS 

cumulative effects less clear. The BOEM concludes that the unavailable information from these events 

may be relevant to foreseeable significant adverse impacts to submerged vegetation. Relevant data on the 

status of submerged vegetation beds after the DWH event may take years to acquire and analyze, and 

impacts from the DWH event may be difficult or impossible to discern from other factors. Therefore, it is 

not possible for BOEM to obtain this information within the timeframe contemplated in this 

Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable 

information, BOEM subject-matter experts have used available scientifically credible evidence in this 

analysis and based upon accepted methods and approaches. Nevertheless, BOEM believes that 

incomplete or unavailable information regarding effects of the DWH event on submerged vegetation is 

not essential to a reasoned choice among alternatives in the cumulative effects analysis. In light of this, 

the incremental contribution of the proposed action remains minor compared with the cumulative effects 

of other factors, including dredging, hurricanes, and vessel traffic. 

4.1.1.6. Live Bottoms 

4.1.1.6.1. Live Bottoms (Pinnacle Trend) 

The BOEM has protected Pinnacle Trend features that support sensitive benthic communities since 

1974 and recommends that oil and gas operators avoid contact with these features by providing a 100-ft 

(30-m) buffer zone as described in NTL 2009-G39, “Biologically-Sensitive Underwater Features and 

Areas” (USDOI, MMS, 2009b). The Gulf of Mexico seafloor in the CPA is mostly mud bottoms with 

varying mixtures of sand in some areas; however, there are some rock features that protrude into the water 

column that form a reef that may support organisms that are different from those on typical soft bottoms. 

These reefs are relatively rare on the seafloor compared with the ubiquitous soft bottoms and provide 

habitat for sensitive species (Parker et al., 1983). 

Pinnacle features are located on 74 OCS lease blocks in the northeastern CPA of the Gulf of Mexico. 

They are defined in this Agency’s NTL 2009-G39, “Biologically-Sensitive Underwater Features and 

Areas,” as “small, isolated, low to moderate relief carbonate reefal features or outcrops of unknown origin 

or hard substrates exposed by erosion that provide surface area for the growth of sessile invertebrates and 

attract large numbers of fish.” 

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 Pinnacle habitats and their associated communities. 

These protections have developed into stipulations applied to OCS leases. The lease stipulations establish 

protection zones around the core of the feature and prohibit any contact with the seafloor. Details of the 

restrictions are described in NTL 2009-G39. The Biological Stipulation Map Package (http://

www.gomr.boemre.gov/homepg/regulate/regs/ntls/2009NTLs/09-G39.pdf) includes maps and lists of the 

protected features. 

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 BOEM 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 

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 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 
Description of the Environment and Impact Analysis 4-97 

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 that provide hard surfaces for encrusting and attached epifauna. These low-relief, hardbottom areas are discussed in Chapter 4.1.1.6.2.1. 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 (3 to 16-20 ft) across also add 

complexity to the overall character of the Pinnacle Trend area. 

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). 

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 BOEM 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 BOEM 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 BOEM 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. 

Features of the Pinnacle Trend Area 

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). 

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). 
4-98 Central Planning Area Supplemental EIS 

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 and scarps (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 

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). 
Description of the Environment and Impact Analysis 4-99 

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. 

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 high-
4-100 Central Planning Area Supplemental EIS 

density, 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). 

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). 
Description of the Environment and Impact Analysis 4-101 

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). 

Essential Fish Habitat 

The NMFS has designated essential fish habitat (EFH) for coral species within the Pinnacle Trend 

area that are managed under fishery management plans (FMP’s) (USDOC, NMFS, 2010a). The EFH is 

defined as “waters—aquatic areas and their associated physical, chemical, and biological properties that 

are used by fish and may include aquatic areas historically used by fish where appropriate; substrate—

sediment, hard bottom, structures underlying the waters, and associated biological communities; 

necessary—the habitat required to support a sustainable fishery and the managed species’ contribution to 

a healthy ecosystem; and spawning, breeding, feeding, or growth to maturity—stages representing a 

species’ full life cycle” (USDOC, NMFS, 2010a). Groups of coral protected under the Coral and Coral 

Reef FMP include octocorals, fire corals, stinging corals, stony corals, black corals, and deepwater corals 

(GMFMC and South Atlantic Fishery Management Council, 1982). The EFH for coral in the Gulf of 

Mexico is designated for all life stages. The Magnuson-Stevens Act requires Federal agencies to consult 

with NMFS on actions that are to be federally permitted, funded, or undertaken that may have an adverse 

affect on EFH. Adverse affects are defined as “any impact that reduces quality and/or quantity of 

EFH . . . [and] may include direct (e.g., contamination or physical disruption), indirect (e.g., loss of prey, 

reduction of species’ fecundity), site-specific or habitat wide impacts, including individual, cumulative, or 

synergistic consequences of actions” (USDOC, NMFS, 2010a). The BOEM is in the process of 

consulting with NMFS on this CPA proposed action. (See also Chapter 4.1.1.16, “Fish Resources and 

Essential Fish Habitat”). 

Baseline Conditions following the Deepwater Horizon Event 

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 altered; however, impacts to hard-bottom areas farther from the well, including the Pinnacle Trend 

area, are still unknown. 

The potential oiling footprint as reported through NOAA’s Environmental Response Management 

Application (ERMA) indicated that oil was recorded in surface waters above the Pinnacle Trend area 

(USDOC, NOAA, 2011b). The oil was distributed in patches and ribbons rather than a continuous 

blanket of petroleum, and it migrated over time so that it did not have a continuous cover over the entire 

area for the duration of the spill (USDOC, NOAA, 2011b). The crests of the Pinnacle features rise up to 
4-102 Central Planning Area Supplemental EIS 

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, which help to protect the epibenthic species from physical oil contact because their crests are 

deeper than the physical mixing ability of surface oil (Lange, 1985; McAuliffe et al., 1975 and 1981a; 

Tkalich and Chan, 2002; Thompson et al., 1999; Schroeder, 2000). 

Larger pinnacle formations, the Alabama Alps (including the 36 Fathom Ridge) and Roughtongue 

Reef, were located beneath a portion of the oil on the water’s surface 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 beginning April 29, 2010; and the Roughtongue Reef, 100 nmi (185 km; 115 mi) northeast of 

the well, was beneath the oil beginning May 20, 2010 (Boland et al., 2010). Surface oil was still in the 

area at the time of the writing of the Boland et al. (2010) document (July 2, 2010). The NRDA has been 

approved to conduct an impact assessment of features to determine if they have been impacted (Boland et 

al., 2010). Studies at the pinnacles include a comparison of new ROV video and digital imagery with 

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. 

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 (Figures 4-7 and 4-8) 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). 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, 

based on the concentrations of oil measured in the area, any impacts to coral 40 nmi (74 km; 46 mi) north 

and 100 nmi (185 km; 115 mi) northeast of the well would likely be sublethal and may include reduced 

recruitment success, reduced reproductive 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). 

The DWH event may have impacted some hard-bottom features located much closer to the well on 

the Mississippi-Alabama shelf than the Pinnacle Trend. Oil was detected in the CPA in a subsurface 

plume in water depths between 1,100 and 1,300 m (3,609 and 4,265 ft) and moving southwest along those 

depth contours (OSAT, 2010). Epibenthic organisms that protrude above the sediment may have been 

exposed to oil droplets in the water column or at the seafloor/water interface near the subsea plume. The 

strata where the subsea plume occurred were a place that scientists recorded visible impact to benthic 

organisms. A recent report documents damage to a deepwater (1,400 m; 4,593 ft) coral (gorgonian) 

community 11 km (7 mi) to the southwest of the well; the direction of travel of the subsea oil plume. The 

BOEM and NOAA dedicated part of their collaborative Lophelia II Expedition: Oil Seeps and Deep 

Reefs to investigating damage to deep corals as a result of the DWH event. Results are still pending but it 

appears that a coral community in the CPA about 15 m x 40 m (50 ft x 130 ft) in size was severely 

damaged and may have been the result of contact with the subsea oil plume (Fisher, 2010; USDOI, 

BOEMRE, 2010j). Many of the gorgonians in the affected area were dead or dying, had areas bare of 

tissue, were covered with brown material, and had tissue falling off their skeletons (Fisher, 2010 and 

2011). Refer to Chapter 4.1.1.10 for a detailed description of the affected deepwater coral community. 

Water and sediment samples collected during and after the spill were analyzed as part of the OSAT 

(2010) report. A handful of samples collected off the Gulf Coast did reveal some PAH’s as a result of the 

DWH event; however, there were no exceedences of USEPA aquatic life benchmarks measured near 

Pinnacle features in either water or sediment (OSAT, 2010). There were 6 water samples out of 
Description of the Environment and Impact Analysis 4-103 

481 collected that exceeded USEPA’s chronic toxicity benchmarks for PAH’s in the offshore waters 

(>3 nmi [3.5 mi; 5.6 km] offshore to the 200-m [656-ft] bathymetric contour), all of which occurred 

within 1 m (3 ft) of the water surface (OSAT, 2010). There were 63 water samples out of 3,605 collected 

from deep water (>200 m; 656 ft) that exceeded USEPA’s aquatic life benchmarks for PAH’s (OSAT-2, 

2010). Exceedances occurred near the water surface or in the southwest traveling deepwater plume 

within 70 km (43 mi) of the well. Oil detected in the subsurface plume was in water depths between 

1,100 and 1,300 m (3,609 and 4,265 ft) and moving southwest along those depth contours (OSAT, 2010), 

which is deeper than and in the opposite direction of the Pinnacle Trend features on the continental shelf. 

The oil in the deepwater plume was carried by deepwater currents, which do not transit up onto the 

continental shelf (Pond and Pickard, 1983; Inoue et al., 2008), protecting the Pinnacle features. No 

sediment samples collected offshore (>3 nmi [3.5 mi; 5.6 km] offshore to the 200-m [656–ft] depth 

contour) and seven sediment samples collected in deep water (>200 m; 656 ft) exceeded USEPA’s 

aquatic life benchmarks for PAH exposure (OSAT, 2010). All chronic aquatic life benchmark 

exceedances in the sediment occurred within 3 km (2 mi) of the well, and samples fell to background 

levels at a distance of 10 km (6 mi) from the well (OSAT, 2010). Dispersants were also detected in 

waters off Louisiana, but they were below USEPA benchmarks of chronic toxicity. No dispersants were 

detected in sediment on the Gulf floor (OSAT, 2010). The Pinnacle Trend features, therefore, are not 

expected to be acutely impacted by PAH’s in the water column or sediment, as they are located much 

farther from the well than measured benchmark exceedances. However, chronic impacts may have 

occurred as a result of low-level or long-term exposure to dispersed, dissolved, or neutrally buoyant oil 

droplets in the water column. 

The MC 252 oil weathered as it traveled to the sea surface, floated on the sea surface, and traveled in 

the subsea plume, and it became depleted in lower molecular weight PAH’s (which are the most acutely 

toxic components) (Brown et al., 2010; Eisler, 1987). The longer the oil spent in the water column or at 

the sea surface, the more diluted and weathered it became (The Federal Interagency Solutions Group, 

2010). Chronic impacts that may result to species that came in contact with the diluted and weathered oil 

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). These types of 

possible impacts may be investigated in future studies if deemed necessary by NRDA. It should be noted 

that it may be difficult to distinguish between possible low-level impacts to invertebrates as a result of 

exposure to DWH oil and numerous natural seeps in the CPA that are constantly releasing oil into the 

water (MacDonald, 2002). 

Once more data are released, we will have a better understanding of the measured impacts and 

possible long-term effects of this event. The implementation of the proposed Live Bottom (Pinnacle 

Trend) Stipulation into lease sales, 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 Live Bottom (Pinnacle Trend) Stipulation protects hard-bottom 

features in the Gulf of Mexico from routine and accidental impacts of petroleum production are discussed 

below. 

Limited data are currently available on the potential impacts of the DWH event on Pinnacle Trend 

features in the CPA. This incomplete or unavailable information may be relevant to reasonably 

foreseeable significant impacts to Pinnacle Trend features. The BOEM has determined that this 

incomplete or unavailable information may be essential to a reasoned choice among alternatives. 

Relevant data on the status of Pinnacle Trend features after the DWH event, however, may take years to 

acquire and analyze. Much of this data is being developed through the NRDA process, which may take 

years to complete. Little data from the NRDA process have been made available to date. Therefore, it is 

not possible for BOEM to obtain this information within the timeframe contemplated in this 

Supplemental EIS, regardless of the cost or resources needed. In the place of this incomplete or 

unavailable information, BOEM subject-matter experts have used available scientifically credible 

evidence in this analysis and applied it using accepted scientific methods and approaches. 
4-104 Central Planning Area Supplemental EIS 

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 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. 

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 (Figure 4-4). 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 BOEM 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 BOEM 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 

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 BOEM flexibility to request any surveys or monitoring information for the 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 
Description of the Environment and Impact Analysis 4-105 

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 lease stipulations, as 

described in 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 them 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. 

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. 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). The heaviest concentrations of well cuttings 

and drilling fluids have been reported within 100 m (328 ft) of wells and are shown to decrease beyond 

that distance (CSA, 2004b; Kennicutt et al., 1996). The thickness of the deposition, however, is the 

potentially greater impacting factor for Pinnacle Trend features rather than the distance the cuttings are 

dispersed from the well. The cuttings rarely accumulate thicknesses >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. They 

are usually distributed unevenly in gradients and in patches, often dependent on prevailing currents (CSA, 

2004b). A gradient of deposition is generally limited to about 250 m (820 ft) from the well site, but it 

may reach up to 500 m (1,640 ft) from the well, depending on prevailing currents and surrounding 

environmental conditions (Kennicutt et al., 1996; CSA, 2004b). Cuttings that accumulate on the seafloor 

should not completely cover organisms on pinnacles because the pinnacles have several meters relief 

above the seafloor and because the organisms are adapted to high levels of sedimentation. 

In order to protect Pinnacle Trend features, the relocation of operations to avoid live-bottom areas and 

monitoring to assess the impact of the activity may be required. These measures would limit or prevent 

well drilling activities from occurring in sensitive live-bottom areas. Also, the USEPA’s general NPDES 

permit sets special restrictions on discharge rates for muds and cuttings to protect biological features. 

Chapter 4.1.1.2.2 details the NPDES permit’s general restrictions and the impacts of drilling muds and 

cuttings on offshore water quality and seafloor sediments. Due to the Live Bottom (Pinnacle Trend) 

Stipulation and USEPA’s 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) settles 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., 1980a; 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 
4-106 Central Planning Area Supplemental EIS 

measured only a few milligrams/liter above background suspended sediment concentrations (Shinn et al., 

1980a). 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. 

Drilling mud concentrations at 6 m (20 ft) from the discharge were often less than those produced 

during storms or from boat wakes, and at 96 m (315 ft), they were less than suspended sediment 

concentrations measured on a windy day in coral reefs off Florida, and they were far below 

concentrations measured to cause physiological impacts to corals (Shinn et al., 1980a and 1980b; 

Thompson et al., 1980; Szmant-Froelich et al., 1981; Kendall et al., 1983). The toxic effects measured as 

a result of exposure to drilling mud are not caused by turbidity alone, but by the compounds in the drilling 

mud (Kendall et al., 1983). Extrapolation of data collected from bioassays indicates the no-effect 

concentration of drilling mud to be 3.99 ppm, which is above the average concentration of drilling mud 

measured in the water column 96 m (315 ft) from platforms (Kendall et al., 1983; Shinn et al., 1980b). 

Based on those values, there should be no effects from drilling mud 96 m (315 ft) from a platform and 

possible limited effects at 6 m (20 ft) from the well. 

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., 1980a; 

Hudson and Robbin, 1980a). 

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 
Description of the Environment and Impact Analysis 4-107 

and anemones were sparse on artificial reef habitats and the community had still not reached “climax” 

state (MRRI, 1984). 

The MRRI has noted that 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 hard-bottom 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 hard-bottom 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 BOEM 

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. 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. Sublethal impacts to infauna have been reported out to 100 m (328 ft) from the 

platform. The impacts included reduced abundances, reduced survival, increased reproductive effort 

paired with reduced recruitment, and reduced genetic diversity (Montagna and Harper, 1996; Carr et al., 

1996; Montagna and Li, 1997; Kennicutt, 1995). 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). Similar impacts could be expected for Pinnacle-associated 

organisms exposed to drill cuttings and muds. 

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, 
4-108 Central Planning Area Supplemental EIS 

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 in the sediment beneath the platform because the elements in the produced water 

may remain in the water column or attach to particles and settle to the seafloor (Burns et al., 1999). 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 and Chapter 4.1.1.2 of this Supplemental EIS). 

Produced waters are rapidly diluted and impacts are generally only observed within proximity of the 

discharge point (Gittings et al., 1992a). Models have indicated that the vertical descent of a surface 

originating plume should be limited to the upper 50 m (164 ft) of the water column, and maximum 

concentrations of surface plume water have been measured in the field between 8 and 12 m (26 and 39 ft) 

(Ray, 1998; Smith et al., 1994). Plumes have been measured to dilute 100 times within 10 m (33 ft) of 

the discharge and 1,000 times within 103 m (338 ft) of the discharge (Smith et al., 1994). Modeling 

exercises showed hydrocarbons to dilute 8,000 times within 1 km (0.6 mi) of a platform and constituents 

such as benzene and toluene to dilute 150,000 and 70,000 times, respectively, within that distance (Burns 

et al., 1999). 

The less soluble fractions of the constituents in produced water associate with suspended particles and 

may sink (Burns et al., 1999). Particulate components were reported to fall out of suspension within 

0.5-1 nmi (0.6-1.2 mi; 0.9-1.9 km) from the source outfall (Burns et al., 1999). The particulate fraction 

disperses widely with distance from the outfall, and soluble components dissolve in the water column, 

leaving the larger, less bioavailable compounds on the settling material (Burns et al., 1999). Due to the 

distance requirement for production platforms from Pinnacle Trend features, dispersion of particles in the 

water column, and currents around Pinnacle Trend features, the particulate constituents of produced 

waters should not impact biological communities on these live bottoms (Burns et al., 1999). 

Waterborne constituents of produced waters can influence biological activity at a greater distance 

from the platform than particulate components can (Osenberg et al., 1992). The waterborne fractions 

travel with currents; however, data suggest that these fractions remain in the surface layers of the water 

column (Burns et al., 1999). Measurements of toluene, the most common dissolved hydrocarbon in 

produced waters, revealed rapid dilution with concentrations between 1 and 10 ng/L (0.000001-0.00001 

ppm) less than 2 km (1.2 mi) directly down current from the source and rapid dispersion much closer to 

the source opposite the current (King and McAllister, 1998). Monitoring studies of the Flower Garden 

Banks located less than 2 km (1.2 mi) from a production platform did not indicate negative effects 

throughout the duration of the platform’s operation, most likely due to the influence of currents (Gittings 

at al., 1992a). Many currents sweep around banks in the GOM instead of over them, which would protect 

reef organisms from contact with a produced-water plume (King and McAllister, 1998; Gittings at al., 

1992a; Rezak et al., 1983; McGrail, 1982). A similar current action may occur around Pinnacle features. 

Modeling data for a platform in Australia indicated the plume would remain in the surface mixed layer 

(top 10 m; 33 ft) of the water column, which would further protect Pinnacle Trend features from produced 

water traveling with currents because crests of the Pinnacle features 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), placing them 40 m (130 ft) or 

more below the sea surface (Thompson et al., 1999; Schroeder, 2000; Burns et al., 1999). 

Acute effects caused by produced waters are likely only to occur within the mixing zone around the 

outfall (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). Another study in Australia reported that the average total concentration of 20 

aromatic hydrocarbons measured in the water column 20 m (66 ft) from a discharge was less than 0.5μg/L 
Description of the Environment and Impact Analysis 4-109 

(0.0005 mg/L or 0.0005 ppm) due to the rapid dispersion of the produced-water plume (Terrens and Tait, 

1996). 

Compounds found in produced waters are not anticipated to bioaccumulate in marine organisms. 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. 

Metals including barium, cadmium, mercury, nickel, lead, and valadium in the tissue of the clam, Chama 

macerophylla, and the oyster, Crassostrea virginica, collected within 10 m (33 ft) of discharge pipes on 

oil platforms, were not statistically different from reference stations (Trefry et al., 1995). Because highmolecular weight 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). 

Chronic effects including decreased fecundity; altered larval development, viability, and settlement; 

reduced recruitment; reduced growth; reduced photosynthesis by phytoplankton; reduced bacterial 

growth; alteration of community composition; and bioaccumulation of contaminants were reported for 

benthic organisms close to discharges and out to 1,000 m (3,281 ft) from the discharge (Holdway, 2002; 

Burns et al., 1999). Effects were greater closer to the discharges and responses varied by species. High 

concentrations of produced waters may have a chronic effect on corals. The Australian coral, Plesiastrea 

versipora, when exposed to 25 percent and 50 percent produced water, had a significant decrease in 

zooxanthellae photosynthesis and often bleached (Jones and Heyward, 2003). Experiments using the 

water accommodated fractions (WAF’s) of produced waters indicated that coral fertilization was reduced 

by 25 percent and that metomorphosis was reduced by 98 percent at 0.0721 ppm total hydrocarbon (Negri 

and Heyward, 2000). The WAF, however, is based on a closed experimental system in equilibrium and 

may be artificially low for the Gulf of Mexico, which will not reach equilibrium with contaminants. The 

experimental value can be considered a conservative approach that would overestimate impacts if the 

entire Gulf were to come in equilibrium with oil inputs. 

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, any elevated concentrations of compounds measured near outfalls 

should not reach Pinnacle Trend features due to the high dilution rates of produced waters (King and 

McAllister, 1998), influence of currents around features, and drilling distance required by the proposed 

Live Bottom (Pinnacle Trend) Stipulation. Also, USEPA’s general NPDES permit restrictions on the 

discharge of produced water, which require the effluent concentration 100 m (328 ft) from the outfall to 

be less than the 7-day “no observable effect concentration” based on laboratory exposures, would help to 

limit the impacts on biological resources of Pinnacle Trend features (Smith et al., 1994). Measurements 

taken from a platform in the Gulf of Mexico showed discharge to be diluted below the no observable 

effect concentration within 10 m (33 ft) of the discharge (Smith et al., 1994). Such low concentrations 

would be even further diluted at greater distances from the well, limiting 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 loss of habitat. Both explosive and nonexplosive removal 

operations would disturb the seafloor by generating considerable turbidity that could impact surrounding 

live-bottom environments. 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. 
4-110 Central Planning Area Supplemental EIS 

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. Very few crabs died when 

exposed to 14-kg (31-lb) charges in open water 46 m (151 ft) away from the explosions. 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 BSEE 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 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 
Description of the Environment and Impact Analysis 4-111 

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 between the coastline and 60 m (197 ft) of water 

(Subarea C0-60) (east of the Mississippi River Delta) and between 60 and 200 m (197 656 ft) (Subarea 

C60-200). Table 3-2 provides information regarding the level of proposed-action-related activities. 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/

delineation wells, 23-33 development wells, and 2-3 production structures projected for offshore Subarea 

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, incidences of anchor damage from support vessels to pinnacle features would be avoided. 

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 

enforcement of the Live Bottom (Pinnacle Trend) Stipulation would help to minimize the impacts of 

pipeline-laying activities throughout the pinnacle region. 

Effects of the Proposed Action without the Proposed Stipulation 

The Pinnacle Trend features and associated biota of the CPA could be adversely impacted by oil and 

gas activities resulting from the proposed action in the absence of the proposed Live Bottom (Pinnacle 

Trend) Stipulation (Chapter 2.3.1.3.2). This would be particularly true should operations occur directly 

on top of or in the immediate vicinity of otherwise protected CPA Pinnacle Trend features. 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 

biota found within the Pinnacle Trend. 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. 

Recovery from such disturbances could take 10 years or more in these deep environments (MRRI, 

1984). 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. Construction discharges would cause 

substantial and prolonged turbidity and sedimentation, greater than natural conditions, 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 
4-112 Central Planning Area Supplemental EIS 

the vicinity of or on the Pinnacle Trend features could cause turbidity, sedimentation, and shock-wave 

impacts that would affect benthic biota. 

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, could have 

localized impacts on the benthos nearby the well; however, impacts would be reduced with distance from 

the well. 

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. Produced waters 

also rapidly disperse and remain in the surface layers of the water column, far above the peaks of 

Pinnacles. 

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 experience 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. 

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 

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. A catastrophic event analysis is provided in 

Appendix B; nevertheless, the type and kind of expected impacts to Pinnacle Trend features from a 

catastrophic event would be similar to those described below as impacts from accidental events. 

A Live Bottom (Pinnacle Trend) Stipulation similar to the one described in Chapter 2.3.1.3.2 has 

been included in appropriate leases since 1973 and may, at the option of the ASLM, be made a part of 
Description of the Environment and Impact Analysis 4-113 

appropriate leases resulting from this proposed action. Although the lease stipulation was created to 

protect live-bottom features from routine impacts of drilling and production, it also protects the features 

from accidental impacts by distancing wells from them. The impact analysis of accidental events 

associated with the CPA proposed action presented here includes the proposed Live Bottom (Pinnacle 

Trend) Stipulation. As noted in Chapter 2.3.1.3.2, the proposed stipulation establishes that no bottomdisturbing activities may occur within 30 m (100 ft) of any hard bottoms/Pinnacles that have a vertical 

relief of 8 ft (2 m) or more, which distances these features from possible accidental impacts that could 

occur. Clarification on how the proposed Live Bottom (Pinnacle Trend) Stipulation applies to operators 

is detailed in NTL 2009-G39 (USDOI, MMS, 2009b). 

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 adhere 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. 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 3.2.1.5.4, 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 

benthic 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 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 impacts to 

the seafloor 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 majority of the oil released from a spill would 

be expected to 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 livebottom habitat. Although these small oil droplets would not sink themselves, they may also attach to 
4-114 Central Planning Area Supplemental EIS 

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. 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 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, 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 livebottom 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 stipulations written 

into lease sales; these stipulations distance these activities from Pinnacle features by creating a 30-m 

(100-ft) buffer around the features, as described in NTL 2009-G39 (USDOI, MMS, 2009b). 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 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. Subsea oil plumes 

transported by currents also 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. Low-level exposure impacts may vary from chronic to temporary, or 

even immeasurable. 
Description of the Environment and Impact Analysis 4-115 

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 (reef-building) and 

ahermatypic (non reef-building) corals, although ahermatypic corals are those that are found on Pinnacle 

features. 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 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., 1992b), 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-associated 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 
4-116 Central Planning Area Supplemental EIS 

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). 

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 biological impacts that 

may occur from dispersant usage are greatest within the first hour of application and occur primarily to 

organisms living near the water’s surface (Guillen et al., 1999). 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, 2010j) as a 

result of exposure to oil from the DWH event may have resulted from the use of subsea 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). It appears that density-bounded plume eventually contacted the 

coral community. The decision to use dispersants is carefully weighed against the surrounding 

environment and anticipated environmental impacts, and the use of 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). There is, however, no written policy for the 
Description of the Environment and Impact Analysis 4-117 

application of dispersants near Pinnacle Trend features. The use of dispersants near protected features is 

left to the discretion of the Federal On-Scene Coordinator on a case-by-case basis. 

Sublethal impacts that may occur to coral and other invertebrates exposed to dispersed oil may 

include reduced feeding, 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). 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 is 

what is anticipated to be possible if Pinnacle-associated organisms experience impacts from dispersed oil. 

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 some experiments indicated that dispersed oil may be more toxic to corals than untreated oil 

during some 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. For example, the Flower Gardens Oil Spill Mitigation Workgroup discourages the use 

of dispersants near the Flower Garden Banks, especially from May to September when coral is spawning 

(Guillen et al., 1999). Mechanical oil cleanup is suggested during this time of year because coral larvae is 

sensitive to dispersants and the sea state is calm, allowing for mechanical removal (Guillen et al., 1999). 

A similar consideration might be made near the Pinnacles, but the use of dispersants near protected 

features is left to the discretion of the Federal On-Scene Coordinator on a case-by-case basis. 
4-118 Central Planning Area Supplemental EIS 

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). Oil may also reach the seafloor through consumption by plankton with excretion 

distributed over the seafloor (ITOPF, 2002). 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 Live Bottom (Pinnacle Trend) stipulation which implements a 30-m (100-ft) buffer 

zone around pinnacle 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; Deleersnijder 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 BOEM 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. Should oil or condensate be present in the blowout flow, 

liquid hydrocarbons could be an added source of negative impact on the benthos. The reduction of light 

that occurs during periods of sediment suspension will not impact the corals that live on Pinnacles 

because they are ahermatypic (they do not have zooxanthellae and do not require light for 

photosynthesis). 

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 
Description of the Environment and Impact Analysis 4-119 

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 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, and causing physical abrasion (Wilber et al., 2005). Corals 

may experience sublethal impacts such as reduced colony 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; 

Rogers, 1990). 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, the degree of 

sedimentation, the length of exposure, and the coral’s ability to clear the sediment. 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). 

Solitary octocorals and gorgonians, which are abundant on many hard-bottom features, are tolerant of 

sediment deposition because these 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). 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 that could 

result from an accidental event (Gittings et al., 1992a). 

Since BOEM’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 
4-120 Central Planning Area Supplemental EIS 

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 BOEM 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 routine petroleum-producing 

activities from damaging the Pinnacle Trend features. Under the stipulation, plans will be reviewed on a 

case-by-case basis to determine whether a proposed operation could impact a Pinnacle Trend area. If it is 

determined from site-specific information derived from BOEM studies, published information from other 

research programs, geohazards survey information, or another source that the operation would impact a 

Pinnacle Trend area, the operator may be required to relocate the proposed operation. 

Although the BOEM 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 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 live-bottom 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 

As described above, a subsurface spill or plume may impact Pinnacle Trend communities. As 

described in Table 3-5, BOEM estimated the potential number of accidental events likely to occur during 

the 40-year leasing scenario for the OCS Program. The likelihood of a catastrophic spill remains remote; 

however, the types and kinds of impacts to Pinnacle Trend communities from such a low-probability 

catastrophic spill would likely be similar to those expected from a more typical accidental event at a 

community level if that small spill were to occur close enough to reach a Pinnacle community. Oil or 

dispersed oil may cause lethal or sublethal impacts to epibenthic organisms wherever a plume may 

contact them. 

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 
Description of the Environment and Impact Analysis 4-121 

ejected under pressure may produce tiny droplets that become entrained in the water column and could 

possibly affect the Pinnacle Trend communities. As stated above, the use of dispersants near protected 

features is left to the discretion of the Federal On-Scene Coordinator on a case-by-case basis. The BOEM 

considers it unlikely that concentrated dispersants would be applied near Pinnacle Trend features, but the 

decision on how and where to use dispersants is outside of BOEM’s control. 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. 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 and blowouts on the biota of the Pinnacle Trend. 

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 and Pinnacle Trend 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 project-specific mitigating measures. These impacting factors would include 

blowouts, surface oil spills, and subsea oil spills, along with oil-spill-response activities such as the use of 

dispersants. 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). As stated above, the use 

of dispersants near protected features is left to the discretion of the Federal On-Scene Coordinator on a 

case-by-case basis. The BOEM considers it unlikely that concentrated dispersants would be applied near 

Pinnacle Trend features, but the decision on how and where to use dispersants is outside of BOEM’s 

control. 

Indeed, disturbances, including oil spills and blowouts, would alter benthic substrates and their 

associated communities, especially close to the discharge. 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 Live Bottom (Pinnacle Trend) Stipulation, the proposed action could 

cause long-term (10 years or more) adverse impacts to the biota of the live-bottom features in the event of 

a spill. 

Summary and Conclusion 

Live-bottom (Pinnacle Trend) features represent a small fraction of the continental shelf area in the 

CPA. The small portion of the seafloor covered by these features, 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 features. 

The proposed Live Bottom (Pinnacle Trend) Stipulation (Chapter 2.4.1.3.2), if applied, would 

prevent most of the potential impacts from oil and gas operations, including accidental oil spills and 

blowouts, on the biota of Pinnacle Trend features by increasing the distance of such events from the 

features. It would be expected that the majority of oil would rise to the surface and that the most heavily 

oiled sediments would likely be deposited before reaching the Pinnacle 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 
4-122 Central Planning Area Supplemental EIS 

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 near the sensitive 

features. 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. 

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 

BOEM jurisdiction (i.e., commercial fishing, tanker and shipping operations, or recreational activities). 

OCS Leasing-Related Impacts 

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 OCS oil- and gasrelated 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 the 

crushing and breaking of live bottoms and associated communities. It may also result in community 
Description of the Environment and Impact Analysis 4-123 

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 larvae great distances (Lissner et al., 1991). Such anchoring 

damage, however, should be minimized on pinnacle habitats, as stipulations amended to leases do not 

allow bottom-disturbing activities 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 stipulation-required buffer distances of 30 m 

(100 ft) and because many sessile benthic organisms are known to resist the concussive force of structureremoval-type blasts (O’Keeffe and Young, 1984). Also, BOEM 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 effects (impacts to growth and reproduction). The Live 

Bottom (Pinnacle Trend) Stipulation, however, requires 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., 1980a; 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., 1980a). Deposition of drilling muds and cuttings in pinnacle habitats is not 

expected to greatly impact the biota of the surrounding habitat for three 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, BOEM’s 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. Third, USEPA’s discharge regulations and permits would further reduce 

discharge-related impacts. Any exposure that may occur from muds and cuttings discharged as a result of 

the cumulative scenario would be temporary and primarily sublethal in nature, and the effects would be 

limited to small areas. 

Produced waters from petroleum operations that are released at the water’s surface are not likely to 

have a great impact on pinnacles. 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). Also, USEPA’s general NPDES permit restrictions on the discharge of produced water, 

which require the effluent concentration 100 m (328 ft) from the outfall to be less than the 7-day “no 

observable effect concentration” based on laboratory exposures (Smith et al., 1994). 

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 and 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 the burial of pipelines is 
4-124 Central Planning Area Supplemental EIS 

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. 

Oil spills may have an impact on the Pinnacle communities of the Gulf of Mexico. 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) of 

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 live-bottom 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 (<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 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 because BOEM 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. Subsea oil 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 of physical contact 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 Pinnacle 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 

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. 

The greatest impact from an oil spill could result from dispersed oil trapped in stratified layers of 

water, such as that which occurred during the DWH event. A recent report documents damage to a 

deepwater coral community 11 km (7 mi) southwest of the DWH event (USDOI, BOEMRE, 2010j) at a 

depth where a dispersed plume of oil was trapped in a stratified water layer (OSAT, 2010). A probable 

explanation for the detrimental impacts to corals is that the coral community forms structures that 

protrude up into the water column that would be affected by a passing oil plume. The DWH event was 

the first usage of subsea dispersants, but if subsea dispersants are ever applied on the continental shelf, a 

similar occurrence may happen. A stratified nepheloid (turbid) layer exists near the seafloor and rises to 

20 m (66 ft) from the seafloor and, if a dispersant is used in that layer near the Pinnacles, dispersed oil 

could affect the sensitive communities. As stated above, the use of dispersants near protected features is 

left to the discretion of the Federal On-Scene Coordinator on a case-by-case basis. The BOEM considers 

it unlikely that concentrated dispersants would be applied near Pinnacle Trend features, but the decision 

on how and where to use dispersants is outside of BOEM’s control. 
Description of the Environment and Impact Analysis 4-125 

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. 

As noted in the affected environment description, limited data are currently available on potential 

impacts of the DWH event on Pinnacle Trend features in the CPA. This incomplete or unavailable 

information may be relevant to reasonably foreseeable significant impacts to Pinnacle Trend features. 

The BOEM has determined that this incomplete or unavailable information may be essential to a reasoned 

choice among alternatives. Relevant data on the status of Pinnacle Trend features after the DWH event, 

however, may take years to acquire and analyze. Much of this data is being developed through the 

NRDA process, which is expected to take years to complete. Little data from the NRDA process have 

been made available to date. Therefore, it is not possible for BOEM to obtain this information within the 

timeframe contemplated in this Supplemental EIS, regardless of the cost or resources needed. In the place 

of this incomplete or unavailable information, as noted above, BOEM subject-matter experts have used 

available scientifically credible evidence in this analysis and applied it using accepted scientific methods 

and approaches. 

The cumulative impact of possible oil spills, along with the DWH event, is not anticipated to affect 

the overall Pinnacle Trend habitat. The BOEM 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 of a blowout and 

allowing most of the oil to rise to the sea surface without contacting pinnacle features. If oil is released 

near a pinnacle feature and if concentrated or dispersed oil is entrained in the water column, 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. 

Non-OCS Leasing-Related Impacts 

Although lease stipulations prohibit bottom-disturbing activities for OCS production-related 

construction, these stipulations do not apply to non-OCS-related activity. 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 that are 

created by the wave action 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, 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. 
4-126 Central Planning Area Supplemental EIS 

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 

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). 

Summary and Conclusion 

Non-OCS activities that may occur in the vicinity of the pinnacle communities include recreational 

boating and fishing, import tankering, fishing and trawling, 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 to individual 

formations. 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 minimal because of primarily localized 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 (Pinnacle 

Trend) Stipulation and the dilution of discharges and resuspended sediments in the area. Potential 

impacts from discharges would be further reduced by USEPA’s 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 Supplemental EIS; this 

chapter has been added since the publication of the Multisale EIS and the 2009-2012 Supplemental EIS. 

Although no blocks with live-bottom (low-relief) areas would be offered for lease under the proposed 

action, several live-bottom (low-relief) areas are adjacent to blocks that would be offered for lease under 

the proposed action (Figure 4-4). Therefore, an analysis of potential impacts is being included in this 

Supplemental EIS. It includes a summary of new information and the description of the biology of livebottom (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, 2001b). 
Description of the Environment and Impact Analysis 4-127 

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 BOEM 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 BOEM 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. 

Because no blocks with live-bottom (low-relief) features will be leased as part of the CPA proposed 

action, the Live Bottom (Low Relief) Stipulation will not be applied to a lease. However, routine 

environmental reviews for areas of the CPA that are for lease and adjacent to live-bottom (low-relief) 

blocks will reveal any potential sites of live-bottom habitat that may overlap with planned seafloor 

impacts. Survey information must cover the entire area of planned seafloor impacts, including blocks 

adjacent to the lease if needed. During the review process, seafloor surveys will be analyzed to determine 

that all activity is adequately distanced from sensitive benthic features. Particular attention will be paid to 

making sure that anchor spreads will completely avoid all hard bottoms. Therefore, any activity that 

occurs in an area adjacent to a live-bottom (low-relief) block will be reviewed to make sure that any 

routine activity (i.e., discharges from drilling or production, infrastructure emplacement, or anchoring for 

infrastructure emplacement) does not impact organisms in a protected block. These BOEM site-specific 

reviews would minimize potential impacts on the biota of live bottoms from operations resulting from a 

proposed lease sale. All proposed OCS-related activities are submitted to BOEM for evaluation and 

approval. Exploration plans, development plans, and pipeline applications will be thoroughly reviewed to 

ensure that all bottom disturbances would avoid impacting sensitive live bottoms. 

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). A fine-grained quartz sand sheet covers most of the MississippiAlabama 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). 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). 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). 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 
4-128 Central Planning Area Supplemental EIS 

and flora grow on the exposed hard grounds. Some species, such as sea whips and other gorgonians, are 

tall enough to survive sand movement and accretion. 

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 

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 is 100 m (328 ft) long, 35 m (115 ft) wide, and 2 m (7 ft) high. A mound-like 

feature is made of rock rubble, covers a 300 m2

 (3,228 ft2) area, and rises 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 Pinnacle Trend area (Chapter 4.1.1.6.1.1) 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). 
Description of the Environment and Impact Analysis 4-129 

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 

tropical fish community was associated with the hard bottom. Benson et al. (1997) found another 

important hard-bottom community, 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). The Sticky Grounds 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, official 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 
4-130 Central Planning Area Supplemental EIS 

(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 

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). 

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. According to Executive Order 

13112, “invasive species” are defined as an alien species whose introduction does or is likely to cause 

economic or environmental harm or harm to human health. Tubastraea coccinea, which is reported on 

many oil and gas platforms in the northern Gulf of Mexico, has been reported on several artificial reefs 

off the Florida coast (Fenner and Banks, 2004). It was first reported in 2001 and believed to have been 

introduced on hulls of ships used for artificial reefs (Fenner and Banks, 2004). The lionfish was 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 sightings were noted at several artificial reefs and oil and 

gas platforms in the CPA (USDOI, GS, 2010b). 

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 patch reefs off Florida. 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, 2010f). 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.

Essential Fish Habitat 

The NMFS has designated EFH for coral species within the Florida Middle Grounds, southwest tip of 

the Florida reef tract, and in predominant, patchy, hard bottom offshore of Florida from approximately 

Crystal River south to the Keys that are managed under the Coral and Coral Reef FMP (USDOC, NMFS, 

2010a). The EFH is defined as “waters – aquatic areas and their associated physical, chemical, and 

biological properties that are used by fish and may include aquatic areas historically used by fish where 

appropriate; substrate – sediment, hard bottom, structures underlying the waters, and associated 

biological communities; necessary – the habitat required to support a sustainable fishery and the managed 

species’ contribution to a healthy ecosystem; and spawning, breeding, feeding, or growth to maturity – 

stages representing a species’ full life cycle” (USDOC, NMFS, 2010a). Groups of coral protected under 

the Coral and Coral Reef FMP include octocorals, fire corals, stinging corals, stony corals, black corals, 

and deepwater corals (GMFMC and South Atlantic Fishery Management Council, 1982). The EFH for 

coral in the Gulf of Mexico is designated for all life stages. The Magnuson-Stevens Act requires Federal 

agencies to consult with NMFS on actions that are to be federally permitted, funded, or undertaken and 

that may have an adverse affect on EFH. Adverse affects are defined as “any impact that reduces quality 

and/or quantity of EFH . . .[and] may include direct (e.g., contamination or physical disruption), indirect 

(e.g., loss of prey, reduction of species’ fecundity), site-specific or habitat wide impacts, including 
Description of the Environment and Impact Analysis 4-131 

individual, cumulative, or synergistic consequences of actions” (USDOC, NMFS, 2010a). The BOEM is 

in the process of consulting with NMFS on proposed projects (Chapter 4.1.1.2). 

Habitat Areas of Particular Concern 

The NOAA has designated habitat areas of particular concern (HAPC’s) within identified EFH. The 

HAPC’s provide important habitat for federally managed fish species and are areas for conservation 

priorities. Areas designated as hard-bottom HAPC’s in the CPA are the Florida Middle Grounds, 

Madison-Swanson Marine Reserve, Tortugas North and South Ecological Reserves, and Pulley Ridge 

(Dale and Santos, 2006; GMFMC, 2005). Elkhorn coral, a federally listed threatened species, is found in 

patch reefs off the Florida Keys and Florida reef tract (GMFMC, 2005; USDOC, NOAA, 2011c). The 

Florida patch reefs are one of four NMFS-designated critical habitats for elkhorn coral (USDOC, NOAA, 

2011c). 

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 altered; however, impacts to hard-bottom areas farther from the well are still unknown.. 

The potential oiling footprint as reported through NOAA’s Environmental Response Management 

Application (ERMA) indicated that oil was recorded in surface waters above hard-bottom features in the 

northern Gulf of Mexico (USDOC, NOAA, 2011b). The oil footprint extended from approximately Lake 

Charles, Louisiana, to Panama City, Florida. The oil was distributed in patches and ribbons rather than a 

continuous blanket of petroleum, and it migrated over time so that it did not have a continuous cover over 

the entire area for the duration of the spill (USDOC, NOAA, 2011b). The relief of the hard-bottom 

features do not rise much above the seafloor and are, therefore, far below the sea surface, which helps to 

protect the epibenthic species from physical oil contact because their crests are deeper than the physical 

mixing ability of surface oil (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002; 

Thompson et al., 1999; Schroeder et al., 1988; Schroeder, 2000). Small, low-relief features in shallow 

water near the coast at the northern extent of the Gulf of Mexico may have had a greater chance of oil 

exposure than the deeper features. However, the greatest area of low-relief, hard-bottom features occurs 

off the western Florida coast, to the south and east or the footprint of oil coverage. 

The DWH event may have impacted some deepwater, hard-bottom features located 11 km (7 mi) 

from the well. Oil was detected in the CPA in a subsurface plume in water depths between 1,100 and 

1,300 m (3,609 and 4,265 ft) and moving southwest along those depth contours (OSAT, 2010). 

Epibenthic organisms that protrude above the sediment may have been exposed to oil droplets in the 

water column or at the seafloor/water interface near the subsea plume. The strata where the subsea plume 

occurred was a place that scientists recorded visible impact to benthic organisms. A recent report 

documents damage to a deepwater (1,400 m; 4,593 ft) coral (gorgonian) community 11 km (7 mi) to the 

southwest of the well, the direction of travel of the subsea oil plume. The BOEM and NOAA dedicated 

part of their collaborative Lophelia II Expedition: Oil Seeps and Deep Reefs to investigating damage to 

deep corals as a result of the DWH event. Results are still pending but it appears that a coral community 

in the CPA about 15 m x 40 m (50 ft x 130 ft) in size was severely damaged and may have been the result 

of contact with the subsea oil plume (Fisher, 2010; USDOI, BOEMRE, 2010j). Refer to Chapter 

4.1.1.10 for a detailed description of the affected deepwater coral community. 

Water and sediment samples collected during and after the spill were analyzed as part of the OSAT 

(2010) report. A handful of samples collected off the Gulf Coast did reveal some PAH’s as a result of the 

DWH event, although those samples were not collected in the vicinity of protected hard-bottom, lowrelief features (OSAT, 2010). There were 6 water samples out of 481 collected that exceeded USEPA’s 

chronic toxicity benchmarks for PAH’s in the offshore waters (>3 nmi [3.5 mi; 5.6 km] offshore to the 

200-m [656–ft] bathymetric contour), all of which occurred within 1 m (3 ft) of the water surface (OSAT, 

2010). There were 63 water samples out of 3,605 collected from deep water (>200 m; 656 ft) that 
4-132 Central Planning Area Supplemental EIS 

exceeded USEPA’s aquatic life benchmarks for PAH’s (OSAT, 2010). Exceedances occurred near the 

water surface or in the southwest traveling deepwater plume within 70 km (43 mi) of the well. Oil 

detected in the subsurface plume was in water depths between 1,100 and 1,300 m (3,609 and 4,265 ft) and 

moving southwest along those depth contours (OSAT, 2010), which is deeper than and in the opposite 

direction of the low-relief, hard-bottom features on the continental shelf. The oil in the deepwater plume 

was carried by deepwater currents, which do not transit up onto the continental shelf (Pond and Pickard, 

1983; Inoue et al., 2008), protecting the low-relief features. No sediment samples collected offshore 

(>3 nmi [3.5 mi; 5.6 km] offshore to the 200-m [656-ft] depth contour) and seven sediment samples 

collected in deep water (>200 m; 656 ft) exceeded USEPA’s aquatic life benchmarks for PAH exposure 

(OSAT, 2010). All chronic aquatic life benchmark exceedances in the sediment occurred within 3 km 

(2 mi) of the well, and samples fell to background levels at a distance of 10 km (6 mi) from the well 

(OSAT, 2010). Dispersants were also detected in waters off Louisiana, but they were below USEPA’s 

benchmarks of chronic toxicity. No dispersants were detected in sediment on the Gulf floor (OSAT, 

2010). The low-relief features, therefore, are not expected to be acutely impacted by PAH’s in the water 

column or sediment, as they are located much farther from the well than measured benchmark 

exceedances. However, chronic impacts may have occurred as a result of low-level or long-term 

exposure to dispersed, dissolved, or neutrally buoyant oil droplets in the water column. 

The MC 252 oil weathered as it traveled to the sea surface, floated on the sea surface, and traveled in 

the subsea plume, and it became depleted in lower molecular weight PAH’s (which are the most acutely 

toxic components) (Brown et al., 2010; Eisler, 1987). The longer the oil spent in the water column or at 

the sea surface, the more diluted and weathered it became (The Federal Interagency Solutions Group, 

2010). Chronic impacts that may result to species that came in contact with the diluted and weathered oil 

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). These types of 

possible impacts may be investigated in future studies if deemed necessary by NRDA. It should be noted 

that it may be difficult to distinguish between possible low-level impacts to invertebrates as a result of 

exposure to DWH oil, and numerous natural seeps in the CPA that are constantly releasing oil into the 

water (MacDonald, 2002). 

Harbor Branch Oceanographic Institute and the NOAA Cooperative Institute for Ocean Exploration, 

Research, and Technology conducted the Florida Shelf-Edge Expedition (FLoSEE) following the DWH 

event from July 9 to August 9, 2010. The expedition focused on the following: (1) the assessment and 

documentation of deepwater coral reefs, shelf-edge mesophotic reefs, and hard-bottom essential fish 

habitat; (2) stress responses of corals and other marine invertebrates exposed to oil and chemical 

dispersants; (3) assessment of zooplankton and linkages between pelagic and benthic ecosystems; 

(4) chemical analysis of sessile benthic taxa and biomedical resources; and (5) education and outreach 

(Reed and Rogers, 2011). Survey sites along the east, south, and west Florida shelf and slope were 

partially selected based on the path of the oil plume. Particular sites of interest included the Miami 

Terrace, Pourtales Terrace, Tortugas Ecological Reserve, Florida Keys National Marine Sanctuary, Pulley 

Ridge, Naples sinkhole, Lophelia Reefs, Sticky Grounds, Florida Middle Grounds, and Madison-Swanson 

Marine Protection Area. Videotape and photographs were taken from a submersible, and specimens were 

collected and catalogued. 

Once more data are released, we will have a better understanding of the measured impacts and 

possible long-term effects of this event. Limited data are currently available on the potential impacts of 

the DWH event on low-relief features in the CPA. This incomplete or unavailable information may be 

relevant to reasonably foreseeable significant impacts to low-relief features. The BOEM has determined 

that this incomplete or unavailable information may be essential to a reasoned choice among alternatives. 

Relevant data on the status of low-relief features after the DWH event, however, may take years to 

acquire and analyze. Much of this data is being developed through the NRDA process, which may take 

years to complete. Little data from the NRDA process have been made available to date. Therefore, it is 

not possible for BOEM to obtain this information within the timeframe contemplated in this 

Supplemental EIS, regardless of the cost or resources needed. In the place of this incomplete or 

unavailable information, BOEM subject-matter experts have used available scientifically credible 

evidence in this analysis and applied it using accepted scientific methods and approaches. The BOEM 

case-by-case seafloor review of areas where bottom-disturbing activities are proposed for OCS petroleum 

production, however, would serve to protect sensitive habitat from accidental impacts from oil and gas 
Description of the Environment and Impact Analysis 4-133 

production, such as oil spills, by distancing production from the protected habitat. Details of how the 

site-specific reviews protect hard-bottom features in the Gulf of Mexico from routine and accidental 

impacts of petroleum production are discussed below. 

4.1.1.6.2.2. Impacts of Routine Events 

Background/Introduction 

The Live Bottom (Low Relief) Stipulation (described in NTL 2009-G39 [USDOI, MMS, 2009b]) 

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, and therefore, the stipulation will not apply to this lease sale. No lease sales since 

the 1980’s have included blocks in areas where this stipulation applies. However, CPA blocks adjacent to 

this area are included in the CPA proposed action. 

Although the Live Bottom (Low Relief) Stipulation will not be applied to the proposed lease sale 

(because the live-bottom [low-relief] blocks are not included in this proposed lease sale), BOEM will still 

be conducting reviews of proposed OCS activities so that any live bottoms that could be impacted by 

proposed activity are protected. The case-by-case reviews are 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 lowrelief area. If it is determined from site-specific information derived from BOEM 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 routine 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, and produced-water discharges 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 accidental events such as 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 they 

are the greatest threats associated with the routine activities of the proposed action 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 distances (Lissner et al., 1991). Such anchoring damage, however, should 

be minimized on low-relief hard bottoms since BOEM conducts site-specific reviews of OCS activity so 

that bottom disturbances are distanced from sensitive live-bottom habitat. Because only a few CPA 
4-134 Central Planning Area Supplemental EIS 

blocks for lease are adjacent to live-bottom (low-relief) blocks (Figure 4-33), any damage from routine 

activity should only be possible if construction activities take place immediately adjacent to designated 

live-bottom (low-relief) areas (i.e., drilling a well inside but at the edge of a bordering block and having 

the anchor spread of the drilling vessel extend into a block that is designated as having live-bottom [lowrelief] features). 

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 hardbottom 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. 

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 surface released well cuttings and drilling fluids have 

been reported within 100 m (328 ft) of wells and are shown to decrease beyond that distance (CSA, 

2004b; Kennicutt et al., 1996). The cuttings rarely accumulate thicknesses >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. They are usually distributed unevenly in gradients and in patches, often dependent on prevailing 

currents (CSA, 2004b). A gradient of deposition is generally limited to about 250 m (820 ft) from the 

well site, but it may reach up to 500 m (1,640 ft) from the well depending on prevailing currents and 

surrounding environmental conditions (Kennicutt et al., 1996; 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 (low-relief) features, BOEM conducts site-specific reviews of all planned 

wells and pipelines. If a hard-bottom feature is discovered during the review process, BOEM may require 

the relocation of operations to avoid live-bottom areas. This review process prevents well drilling 

activities from occurring near sensitive live-bottom areas. Other mitigation may be imposed on an 

operator, such as the bottom shunting of cuttings, to protect live-bottom areas from burial, including those 

of low relief. Also, USEPA’s 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 BOEM’s site-specific 

review process and USEPA’s discharge regulations, possible turbidity and smothering impacts of sessile 

invertebrates on hard-bottom features caused by drilling muds and cuttings are anticipated to be 

minimized. 

Suspended sediment concentrations at 6 m (20 ft) from the drilling discharge were often less than 

those produced during storms or from boat wakes, and at 96 m (315 ft), they were less than suspended 

sediment concentrations measured on a windy day in the coral reefs off Florida and were far below the 

concentrations measured to cause physiological impacts to corals (Shinn et al., 1980a and 1980b; 

Thompson et al., 1980; Szmant-Froelich et al., 1981; Kendall et al., 1983). The toxic effects measured as 

a result of exposure to drilling mud are not caused by turbidity alone, but by the compounds in the drilling 

mud (Kendall et al., 1983). Extrapolation of data collected from bioassays indicates the no-effect 

concentration of drilling mud to be 3.99 ppm, which is above the average concentration of drilling mud 

measured in the water column 96 m (315 ft) from platforms (Kendall et al., 1983; Shinn et al., 1980b). 

Based on those values, there should be no effects from drilling mud 96 m (315 ft) from a platform and 

possible limited effects at 6 m (20 ft) from the well. 
Description of the Environment and Impact Analysis 4-135 

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., 

1980a). 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 

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., 1980a; Hudson and Robbin, 1980a). 

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 BOEM 

case-by-case review of planned OCS activity protects hard-bottom features on the Gulf floor by requiring 

bottom-disturbing activity to be distanced from live-bottom features. 
4-136 Central Planning Area Supplemental EIS 

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 

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 in the sediment beneath the platform because the elements in the produced water 

may remain in the water column or attach to particles and settle to the seafloor (Burns et al., 1999). 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. 

Produced waters are rapidly diluted and impacts are generally only observed within proximity of the 

discharge point (Gittings et al., 1992a). Models have indicated that the vertical descent of a surface 

originating plume should be limited to the upper 50 m (164 ft) of the water column and that the maximum 

concentrations of surface plume water have been measured in the field between 8 and 12 m (26 and 39 ft) 

(Ray, 1998; Smith et al., 1994). Plumes have been measured to dilute 100 times within 10 m (33 ft) of 

the discharge and 1,000 times within 103 m (338 ft) of the discharge (Smith et al., 1994). Modeling 

exercises showed hydrocarbons to dilute 8,000 times within 1 km (0.6 mi) of a platform and constituents 

such as benzene and toluene to dilute 150,000 and 70,000 times, respectively, within that distance (Burns 

et al., 1999). 

The less soluble fractions of the constituents in produced water associate with suspended particles and 

may sink (Burns et al., 1999). Particulate components were reported to fall out of suspension within 

0.5-1 nmi (0.6-0.9 mi; 1.2-1.9 km) from the source outfall (Burns et al., 1999). The particulate fraction 

disperses widely with distance from the outfall, and soluble components dissolve in the water column, 

leaving the larger, less bioavailable compounds on the settling material (Burns et al., 1999). Due to 

BOEM policy, which does not allow bottom-disturbing activity to impact low-relief live bottoms and 

dispersion of particles in the water column, the particulate constituents of produced waters should not 

impact biological communities on these live bottoms (Burns et al., 1999). 

Waterborne constituents of produced waters can influence biological activity at a greater distance 

from the platform than particulate components can (Osenberg et al., 1992). The waterborne fractions 

travel with currents; however, data suggest that these fractions remain in the surface layers of the water 

column (Burns et al., 1999). Modeling data for a platform in Australia indicated the plume to remain in 

the surface mixed layer (top 10 m; 33 ft) of the water column, which would protect low-relief, live-
Description of the Environment and Impact Analysis 4-137 

bottom features from produced water traveling with currents because most of these features are in water 

deeper than the surface mixed layer. 

Acute effects caused by produced waters are likely only to occur within the mixing zone around the 

outfall (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). Another study in Australia reported that the average total concentration of 

20 aromatic hydrocarbons measured in the water column 20 m (66 ft) from a discharge was <0.5μg/L 

(0.0005 mg/L or 0.0005 ppm) due to the rapid dispersion of the produced-water plume (Terrens and Tait, 

1996). 

Compounds found in produced waters are not anticipated to bioaccumulate in marine organisms. 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. 

Metals including barium, cadmium, mercury, nickel, lead, and valadium in the tissue of the clam, Chama 

macerophylla, and the oyster, Crassostrea virginica, collected within 10 m (33 ft) of discharge pipes on 

oil platforms were not statistically different from reference stations (Trefry et al., 1995). Because highmolecular weight 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). 

Chronic effects including decreased fecundity; altered larval development, viability, and settlement; 

reduced recruitment; reduced growth; reduced photosynthesis by phytoplankton; reduced bacterial 

growth; alteration of community composition; and bioaccumulation of contaminants were reported for 

benthic organisms close to discharges and out to 1,000 m (3,281 ft) from the discharge (Holdway, 2002; 

Burns et al., 1999). Effects were greater closer to the discharges, and responses varied by species. High 

concentrations of produced waters may have a chronic effect on corals. The Australian coral, Plesiastrea 

versipora, when exposed to 25 percent and 50 percent produced water, had a significant decrease in 

zooxanthellae photosynthesis and often bleached (Jones and Heyward, 2003). Experiments using the 

WAF’s of produced waters indicated that coral fertilization was reduced by 25 percent and that 

metomorphosis was reduced by 98 percent at 0.0721 ppm total hydrocarbon (Negri and Heyward, 2000). 

The WAF, however, is based on a closed experimental system in equilibrium and may be artificially low 

for the Gulf of Mexico, which will not reach equilibrium with contaminants. The experimental value can 

be considered a conservative approach that would overestimate impacts if the entire Gulf were to come in 

equilibrium with oil inputs. 

Produced waters may have some impact on live-bottom features, but BOEM’s site-specific review of 

planned OCS activities and required distancing of activity from sensitive habitats 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 <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, which occurs rapidly (King and McAllister, 1998), reducing the concentration of 

discharged material to which the live bottoms may be exposed. The USEPA’s general NPDES permit 

restrictions on the discharge of produced water would also limit the impacts on biological resources of 

live bottoms. The USEPA’s general NPDES permit restrictions on the discharge of produced water 

requires the effluent concentration 100 m (328 ft) from the outfall to be less than the 7-day “no observable 

effect concentration” based on laboratory exposures (Smith et al., 1994). This would help to limit the 

impacts on biological resources of live-bottom features. Measurements taken from a platform in the Gulf 

of Mexico showed discharge to be diluted below the “no observable effect concentration” within 10 m 
4-138 Central Planning Area Supplemental EIS 

(33 ft) of the discharge (Smith et al., 1994). Such low concentrations would be even farther diluted at 

greater distances from the well, limiting 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 loss of habitat. Both explosive and nonexplosive removal 

operations would disturb the seafloor by generating considerable turbidity that could impact surrounding 

live-bottom environments. 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. Very few crabs died when exposed to 14-kg 

(31-lb) charges in open water 46 m (150 ft) away from the explosions. 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 BSEE 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 BOEM’s site-specific 

reviews 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, 
Description of the Environment and Impact Analysis 4-139 

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 

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 (between the coastline and 60 m [197 ft] of water). There are 

9-14 exploration wells, 23-33 development wells, and 2-3 production structures projected for offshore 

Subareas C60-200 (between 60 and 200 m [197 and 656 ft] of water). 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. In addition, BOEM conducts 

project-specific reviews of planned activity and requires the activity to be distanced from any hard-bottom 

areas near the proposed activity. 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, BOEM’s sitespecific project review of the surrounding seafloor 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 projectspecific seafloor reviews 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. 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 
4-140 Central Planning Area Supplemental EIS 

discharge. The drilling of a well, therefore, could have localized impacts on the benthos near the well, 

which should be located away from live-bottom features according to BOEM’s policy, and additionally, 

impacts would be reduced with distance from the well. 

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 BOEM’s site-specific seafloor review prior to any bottom-disturbing activity 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. Produced waters also rapidly disperse and 

remain in the surface layers of the water column, far above the live-bottom features. 

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 BOEM policy’s of 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 

BOEM site-specific seafloor review and required distancing of seafloor disturbance from live-bottom 

features 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 BOEM policy, 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. 

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 located in 

water depths <100 m (328 ft) and 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. However, 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. 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 live-bottom features of the CPA. 

A catastrophic event analysis is provided in Appendix B; nevertheless, the type and kind of expected 

impacts to low-relief features from a catastrophic event would be similar to those described below as 

impacts from accidental events. 

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 adhere 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 
Description of the Environment and Impact Analysis 4-141 

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 3.2.1.5.4, 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 

benthic 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 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 BOEM’s case-by-case review of OCS 

activity will help to prevent impacts to live-bottom habitats by distancing petroleum-producing activity 

from the habitat. The distance requirements from the habitat, however, are based on routine production 

activity, and oil released during accidental events may reach the locations of live-bottom features. 

However, unless dispersants are used, spilled oil would not be expected to mix into the water column in 

water depths >10 m (33 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981; Knap et al., 1985). As 

described above, a majority 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 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 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, 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, nearshore lowrelief, live-bottom habitats are not located in lease blocks of the CPA proposed action, distancing them 

from potential activities. If dispersants are used, they would enable oil to mix into the water column and 
4-142 Central Planning Area Supplemental EIS 

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. Such subsurface plumes are not expected under normal conditions unless 

dispersants are used to cause oil to mix with the water. 

Live-bottom (low-relief) features are protected from bottom-disturbing activity through site-specific 

seafloor reviews that require activity to be distanced from live bottoms. This buffer zone, in turn, results 

in petroleum-producing activities occurring away from low-relief features. In addition, live-bottom, lowrelief 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. Low-level exposure impacts may vary from chronic to temporary, or 

even immeasurable. 

Although the areas open for lease are distanced from a majority of the live-bottom (low-relief) 

features, 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, both of which can be found on live-bottom (low-relief) features. Although not 

all of the same species studied are present on low-relief, 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., 1992b), 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 
Description of the Environment and Impact Analysis 4-143 

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 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). 
4-144 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 biological impacts that 

may occur from dispersant usage are greatest within the first hour of application and occur primarily to 

organisms living near the water’s surface (Guillen et al., 1999). 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 close enough to a livebottom 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, and the distance of the areas offered in a lease sale from these features increases the dispersion 

factors. Weathering will also be accelerated, and biological toxicity will be reduced with distance from 

the source (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, 2010j) as a 

result of exposure to oil from the DWH event may have resulted from the use of subsea 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). It appears that the density-bounded plume eventually contacted 

the coral community. The use of dispersants near protected features is left to the discretion of the Federal 

On-Scene Coordinator on a case-by-case basis. For example, NOAA policy says that the application of 

dispersants must occur as far as possible from the Flower Garden Banks (Gittings, 2006). There is, 

however, no written policy for the application of dispersants near low-relief live bottoms. The BOEM 

considers it unlikely that concentrated dispersants would be applied near Pinnacle Trend features, but the 

decision on how and where to use dispersants is outside of BOEM’s control. 

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 
Description of the Environment and Impact Analysis 4-145 

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 is what is anticipated to be possible if live-bottom associated organisms 

experience impacts from dispersed oil. 

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 some 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., 1992b 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). Oil may also reach the seafloor through consumption by plankton, with excretion 

distributed over the seafloor (ITOPF, 2002). 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 BOEM policy prohibits bottom-disturbing activity on low-relief, live-bottom features 

and because of 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; Deleersnijder 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 BOEM’s restrictions and the settling rates and 
4-146 Central Planning Area Supplemental EIS 

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 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 in the water column may not impact the benthic 

organisms on live-bottom features. Low-relief features may experience slightly more deposition of 

sediment that settles out of upper layers of the water column. 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 

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 
Description of the Environment and Impact Analysis 4-147 

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 the 

increased sediment input that could result from an accidental event (Gittings et al., 1992a). 

Since BOEM’s policy would preclude bottom-disturbing activity near a low-relief, live-bottom 

feature and because the blocks that have these features are currently not offered in a lease sale, 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. 

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 BOEM’s site-specific 

reviews to determine if hard bottoms are located near proposed bottom-disturbing activity and because the 

areas with live bottoms are not currently offered in a lease sale, 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 hardbottom community, the fluid may smother the existing community. Low-relief communities would be 

more at risk for burial than the higher features in the GOM. 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). 

Protection of Live-Bottom (Low-Relief) Communities 

Although the Live Bottom (Low Relief) Stipulation will not be applied to the proposed lease sale 

(because live-bottom [low-relief] blocks are not included in this proposed sale area), BOEM will still be 

conducting reviews of proposed OCS activities so that any live bottoms that could be impacted by 
4-148 Central Planning Area Supplemental EIS 

proposed activity are protected. A BOEM seafloor review is designed to prevent routine petroleumproducing activities from damaging the low-relief features. Under BOEM’s review, plans will be 

reviewed on a case-by-case basis to determine whether a proposed operation could impact a live bottom. 

If it is determined from site-specific information derived from BOEM studies, published information 

from other research programs, geohazards survey information, or another source that the operation would 

impact a live-bottom area, the operator may be required to relocate the proposed operation or conduct 

additional mitigation measures. 

Although BOEM’s case-by-case seafloor review will prevent bottom-disturbing activities from 

impacting live-bottom 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 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 live-bottom 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 

As described above, a subsurface spill or plume may impact live-bottom benthic communities. As 

described in Table 3-5, BOEM estimated the potential number of accidental events likely to occur during 

the 40-year leasing scenario for the OCS Program. The likelihood of a catastrophic spill remains remote; 

however, the types and kinds of impacts to live-bottom communities from such a low-probability 

catastrophic spill would likely be similar to those expected from a more typical accidental event at a 

community level, if the small spill were to occur close enough to reach a low-relief, hard-bottom 

community. Oil or dispersed oil may cause lethal or sublethal impacts to benthic organisms wherever a 

plume may contact them. 

The BOEM blocks for which the Live Bottom (Low Relief) Stipulation applies are found in the EPA 

in water depths of <100 m (328 ft) 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 BOEM 

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. 

If a surface oil spill is mixed into the water column, the oil is not expected to penetrate below a depth 

of about 10 m (33 ft). The limited depth of oil penetration into the water column shields the bottom 

habitats from oil fouling. Also, the low probabilities of oil reaching the surface waters above these 

features, based on the OSRA model, combined with the limited depth of mixing of surface oil to the 

crests of these features, function to protect these features. However, 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 would only reach a live-bottom (low-relief) community 

if both the spill 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 BOEM policies for live-bottom (low-relief) areas 

would assist in preventing most of the potential impacts from oil and gas operations, including accidental 
Description of the Environment and Impact Analysis 4-149 

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 (low-relief) 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 BOEM case-by-case review of the seafloor in areas where bottom-disturbing activities are 

planned would prevent most of the potential impacts from oil and gas operations, including accidental oil 

spills and blowouts, on the biota of live-bottom features by increasing the distance of such events from 

the features. Also, note that none of the blocks with live bottoms are included in the area to be offered in 

the CPA proposed action. However, operations that occur in blocks adjacent to live-bottom habitat may 

affect live-bottom features. It would be expected though that the majority of oil would rise to the surface 

and that the most heavily oiled sediments would likely be deposited before reaching the live-bottom 

features. 

The limited relief of many live-bottom features 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. Also, features in water shallower than 

10 m (33 ft) would be located 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 BOEM’s site-specific review of seafloor habitats during the review of 

project plans would limit the potential impact of any activities that may approach low-relief habitats (such 

as pipeline right-of-ways) because BOEM’s policy 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. Many of these organisms are located within the influence of the Mississippi River plume and 

are more tolerant of turbidity and sedimentation, allowing them to withstand a degree of these impacts. 

The BOEM site review would assist in preventing most of the potential impacts on live-bottom 

communities from blowouts, surface, and subsurface oil spills and the associated effects because BOEM’s 

policy requires that bottom-disturbing activity be distanced from live-bottom features. In addition, 

because no live-bottom (low-relief) blocks are included in this proposed lease sale, the live-bottom 

features are distanced from oil-producing activity. 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 livebottom 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 livebottom features were reached, resulting in sub-impacts. 

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 productionrelated, 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, 
4-150 Central Planning Area Supplemental EIS 

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 BOEM conducts seafloor reviews of 

proposed OCS activities prior to granting permits for seafloor-disturbing activity. The permit granted 

following the site-specific review requires that the bottom-disturbing activity be distanced from the livebottom habitat to protect the organisms. However, BOEM’s seafloor reviews, stipulations, and 

mitigations do not protect the resources from activities outside of BOEM jurisdiction (i.e., commercial 

fishing, tanker and shipping operations, or recreational activities). 

OCS Leasing-Related Impacts 

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 the 

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 the anchor 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). Such anchoring 

damage, however, should be minimized on live-bottom habitats since BOEM reviews OCS activity on a 

case-by-case basis and does not allow bottom-disturbing activities to impact hard-bottom areas. Also, the 

blocks that house the live-bottom (low-relief) habitat are not currently being offered for leases. 

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, BOEM’s 

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 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 

any areas that may experience seafloor disturbance as part of OCS-related production will be reviewed by 

BOEM for the presence of hard-bottom communities. 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 (low-relief) 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., 1980a; 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., 1980a). Deposition of drilling muds and cuttings in lowrelief areas is not expected to greatly impact the biota of the surrounding habitat for four 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, BOEM’s policy does not allow the disturbance of lowrelief, hard-bottom communities and often requires bottom shunting of drilling material away from the 
Description of the Environment and Impact Analysis 4-151 

sensitive habitat or requires that it be transported to approved disposal sites. Third, USEPA’s discharge 

regulations and permits would further reduce discharge-related impacts. Fourth, the blocks containing 

low-relief habitats are not currently being offered for lease. Any exposure that may occur from muds and 

cuttings discharged as a result of the cumulative scenario would be temporary and primarily sublethal in 

nature, and the effects would be limited to small areas. 

Produced waters from petroleum operations are not likely to have a great impact on live bottoms. 

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). Also, USEPA’s 

general NPDES permit restrictions on the discharge of produced water, which require the effluent 

concentration 100 m (328 ft) from the outfall to be less than the 7-day “no observable effect 

concentration” based on laboratory exposures (Smith et al., 1994). 

Because the low-relief live bottoms are not included in the area to be offered in the CPA proposed 

action and because of BOEM’s site-specific seafloor review and possible 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 and 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). 

Because the low-relief live bottoms are not included in the area to be offered in the CPA proposed 

action and because of the other BOEM 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 hardbottom 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 (low-relief) communities farther offshore (out to 100 m [328 ft]) would be protected 

from direct physical oil contact by depth below the sea surface due to their depth below the water’s 

surface and oil’s limited depth of mixing. 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 (low-relief) features because 

they are not in the area to be offered in the CPA proposed action and because BOEM’s 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 lowrelief 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 
4-152 Central Planning Area Supplemental EIS 

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). 

The greatest impact from an oil spill could result from dispersed oil trapped in stratified layers of 

water, such as that which occurred during the DWH event. A recent report documents damage to a 

deepwater coral community 11 km (7 mi) southwest of the DWH event (USDOI, BOEMRE, 2010j) at a 

depth where a dispersed plume of oil was trapped in a stratified water layer (OSAT, 2010). A probable 

explanation for the detrimental impacts to corals is that the coral community forms structures that 

protrude up into the water column that would be affected by a passing oil plume. DWH was the first 

usage of subsea dispersants, but if subsea dispersants are ever applied on the continental shelf, a similar 

occurrence may happen. A stratified nepheloid (turbid) layer exists near the seafloor and rises to 20 m 

from the seafloor and if a dispersant is used in that layer near a live bottom, dispersed oil could affect the 

sensitive communities. But as stated above, the use of dispersants near protected features is left to the 

discretion of the Federal On-Scene Coordinator on a case-by-case basis. Also, NOAA policy requests 

that dispersants be applied as far as possible from the Flower Gardens National Marine Sanctuary, and 

although there is no policy to protect the live bottoms form dispersant usage, similar requests may be 

made. BOEM considers it unlikely that concentrated dispersants would be applied near live bottom (lowrelief) features, but the decision on how and where to use dispersants is outside of BOEM’s control. 

As noted in the affected environment description, limited data are currently available on potential 

impacts of the DWH event on live-bottom (low-relief) features in the CPA. This incomplete or 

unavailable information may be relevant to reasonably foreseeable significant impacts to live-bottom 

(low-relief) features. The BOEM has determined that this incomplete or unavailable information may be 

essential to a reasoned choice among alternatives. Relevant data on the status of live-bottom (low-relief) 

features after the DWH event, however, may take years to acquire and analyze. Much of this data is 

being developed through the NRDA process, which is expected to take years to complete. Little data 

from the NRDA process have been made available to date. Therefore, it is not possible for BOEM to 

obtain this information within the timeframe contemplated in this Supplemental EIS, regardless of the 

cost or resources needed. In the place of this incomplete or unavailable information, as noted above, 

BOEM subject-matter experts have used available scientifically credible evidence in this analysis and 

applied it using accepted scientific methods and approaches. 

The cumulative impact of possible oil spills, along with the DWH event, is not anticipated to affect 

the overall live-bottom (low-relief) habitat. The BOEM policy would not allow wells to be drilled in 

these habitats, and currently, the locations of these habitats are not being offered for lease. These two 

factors separate the habitat from the worst of the sediment deposition of a blowout and allow most of the 

oil to rise to the sea surface without contacting live-bottom features. If oil is released near a live-bottom 

feature and if concentrated or dispersed oil is entrained in the water column, it could contact nearby lowrelief habitats 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 low-relief 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. 

Non-OCS Leasing-Related Impacts 

Although BOEM policy prohibits bottom-disturbing activities for OCS-related construction, these 

regulations do not apply to non-OCS-related activity. 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). 
Description of the Environment and Impact Analysis 4-153 

Non-OCS activities have a greater potential to affect the hard-bottom communities of the region than 

BOEM-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 northeastern 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 that 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). 

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, fishing and trawling, 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, on 

occasion, in the general area of live bottoms, 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 northeastern 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 
4-154 Central Planning Area Supplemental EIS 

low-relief, hard-bottom communities. Impacts from these factors should be minimized based on BOEM’s 

policy and case-by-case review of proposed OCS-activity and the fact that live-bottom (low-relief) blocks 

are not currently offered for lease. The physical distance between any routine OCS activity or accidental 

spill would minimize any possible impacts from the activity. The impact to the live-bottom resource as a 

whole is expected to be minimal because of the distance of any OCS-related activity from these habitats. 

The incremental contribution of the proposed action to the cumulative impact is expected to be 

minimal, 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 BOEM’s site-specific seafloor review, the fact BOEM is not currently offering the low-relief habitats 

for lease, and the distance of live-bottom habitats from the source of most OCS-related impacts. 

4.1.1.7. Topographic Features 

The BOEM 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 

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 BOEM 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 
Description of the Environment and Impact Analysis 4-155 

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 may 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 deep in the 

water (causing too dark of an environment) or have too much sedimentation for hermatypic (reefbuilding) 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. 

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 BOEM 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 BOEM 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 

BOEM 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 EFH 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 BOEM from impacts of oil and gas activities as described by NTL 
4-156 Central Planning Area Supplemental EIS 

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 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 

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 most 

abundant 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). There are areas where coralline algae 

are abundant, 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
Description of the Environment and Impact Analysis 4-157 

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). 

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 reeffish, 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 reeffish, 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). 
4-158 Central Planning Area Supplemental EIS 

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 

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 
Description of the Environment and Impact Analysis 4-159 

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 

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. The overall coral cover of 

the area 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. 
4-160 Central Planning Area Supplemental EIS 

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 

(262 ft) 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 (66 ft), 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 

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. According to Executive Order 

13112, invasive species are defined as “an alien species whose introduction does or is likely to cause 

economic or environmental harm or harm to human health.” 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 sightings were noted at Sonnier Bank and several oil and gas platforms in the 

CPA (USDOI, GS, 2010b). 

Proposed Candidates for Threatened and Endangered Species 

In 2009, a petition was submitted to NOAA Fisheries by the Center for Biological Diversity to list 

82 species of coral under the ESA (USDOC, NOAA, 2010f). 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. 

Habitat Areas of Particular Concern 

The NOAA has designated HAPC’s within identified essential fish habitat. The HAPC’s provide 

important habitat for federally managed fish species and are areas for conservation priorities. The only 

bank designated as coral HAPC in the CPA is McGrail Bank (Dale and Santos, 2006; GMFMC, 2005). 
Description of the Environment and Impact Analysis 4-161 

Hard-bottom HAPC’s in the CPA are Sonnier Bank, Geyer Bank, Bouma Bank, Rezak Bank, Sinder 

Bank, Alderice Bank, Jakkula Bank, and additional parts of McGrail Bank (Dale and Santos, 2006; 

GMFMC, 2005). 

Recent 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. Hurricane Rita passed the closest to and caused the greatest damage to topographic features of 

all recent hurricanes. The BOEM 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). 

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 most of 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. It is possible 

that Sackett Bank experienced some oiling as a result of the DWH event; this is discussed later. Beyond 

that, the next nearest feature is Diaphus Bank, approximately 240 km (150 mi) away, and it probably did 

not experience the possible impacts that Sackett Bank may have experienced. The oil that was dispersed 

in deep water off the shelf was directed by water currents into deeper water. These currents do not 

typically transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 2008). 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 most of the banks. As a result, it is 

anticipated that there will be no change in existing baseline conditions to most of the bank habitats, except 

possibly Sackett Bank, which is discussed later. The benthic communities on most of 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. 

The potential oiling footprint as reported through NOAA’s Environmental Response Management 

Application (ERMA) posted on the GeoPlatform.gov website indicated that oil was recorded in surface 

waters of the CPA from approximately the western Louisiana border east to Panama City, Florida 

(USDOC, NOAA, 2011b). Sackett Bank appeared to be the only bank beneath the oil slick, while only 
4-162 Central Planning Area Supplemental EIS 

small surface patches of oil were reported in water near other banks. These small patches were 

discontinuous and scattered (USDOC, NOAA, 2011b). The crests of the topographic features, however, 

are deeper than the physical mixing ability of surface oil (Lange, 1985; McAuliffe et al., 1975 and 1981a; 

Tkalich and Chan, 2002; Rezak et al., 1983). Also, most of the oil that migrated west in the CPA, where 

most of the banks are located, was primarily observed close to Louisiana’s Gulf Coast, farther inshore of 

the banks (USDOC, NOAA, 2011b). Based on the location of the surface oil, its mixing abilities, the 

depth of the features, and the trajectory of the dispersed subsea plume, most of the topographic features of 

the CPA would likely not have been impacted by oil from the DWH event. 

Water and sediment samples collected during and after the spill were analyzed as part of the OSAT 

(2010) report. A handful of samples collected off the Gulf Coast did reveal some PAH’s as a result of the 

DWH event; however, there were no exceedances of USEPA’s aquatic life benchmarks measured near 

topographic features in either water or sediment (OSAT, 2010). There were 6 water samples out of 

481 collected that exceeded USEPA’s chronic toxicity benchmarks for PAH’s in the offshore waters 

(>3 nmi [3.5 mi’ 5.6 km] offshore to the 200-m [656-ft] bathymetric contour), all of which occurred 

within 1 m (3 ft) of the water surface (OSAT, 2010). There were 63 water samples out of 3,605 collected 

from deep water (>200 m; 656 ft) that exceeded USEPA’s aquatic life benchmarks for PAH’s (OSAT, 

2010). Exceedances occurred near the water surface or in the deepwater plume within 70 km (44 mi) of 

the well. Oil detected in the subsurface plume was in water depths between 1,100 and 1,300 m 

(3,609 and 4,265 ft) and moving southwest along those depth contours (OSAT, 2010), which is deeper 

than the topographic features. No sediment samples collected offshore (>3 [3.5 mi’ 5.6 km] offshore to 

the 200-m [656-ft] depth contour) and seven sediment samples collected in deep water (>200 m; 656 ft) 

exceeded USEPA’s aquatic life benchmarks for PAH exposure (OSAT, 2010). All chronic aquatic life 

benchmark exceedances in the sediment occurred within 3 km (2 mi) of the well, and samples fell to 

background levels at a distance of 10 km (6 mi) from the well (OSAT, 2010). Dispersants were also 

detected in waters off Louisiana, but they were below USEPA’s benchmarks of chronic toxicity. No 

dispersants were detected in sediment on the Gulf floor (OSAT, 2010). Topographic features in the CPA, 

therefore, are not expected to be impacted by PAH’s in the water column or sediment, as they are located 

much farther from the well than measured benchmark exceedances. 

If any impacts did occur, they would be a result of low-level or long-term exposure to dispersed, 

dissolved, or neutrally buoyant oil droplets. These forms of oil weathered as they traveled to the sea 

surface or in the subsea plume and they became depleted in their lower molecular weight PAH’s (which 

are the most acutely toxic components) (Brown et al., 2010; Eisler, 1987). The longer the oil spent in the 

water column or at the sea surface, the more diluted and weathered it became (The Federal Interagency 

Solutions Group, 2010). Impacts to species the oil may come in contact with 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). These types of possible 

impacts may be investigated in future studies if deemed necessary by NRDA. It should be noted that it 

may be difficult to distinguish between possible low-level impacts to invertebrates as a result of exposure 

to DWH oil and the numerous natural seeps in the CPA that are constantly releasing oil into the water 

(MacDonald, 2002). 

Possible Impacts to Sackett Bank as a Result of the Deepwater Horizon Event 

As mentioned above, Sackett Bank may have been affected by oil released during the DWH event 

based on the trajectory of the subsurface plume of oil. Sackett Bank is the nearest protected topographic 

feature to the blowout; 116 km (72 mi) from the spill site. Records have indicated that Sackett Bank was 

beneath the surface oil slick for 11-20 days (USDOC, NOAA, 2011b). Although the crest of this bank 

lies at 63 m (207 ft) below the Gulf surface (Rezak et al., 1983), which is far below the depth of surface 

oil mixing (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 2002), it is 16 mi (26 km) 

southwest of the Mississippi Delta’s Southwestern Pass, which is still within the influence of the 

Mississippi River’s outflow. Suspended material, including sediment that flows from the River into the 

Gulf and a very productive plankton community near the water’s surface, supplies abundant material to 

which oil may adhere. There remains the possibility that the surface oil adhered to suspended material in 

the water column and subsequently settled over the Bank, affecting the benthic and epibenthic organisms 

there. Because of this potential, for purposes of this Supplemental EIS, the Bureau of Ocean Energy 
Description of the Environment and Impact Analysis 4-163 

Management is assuming this area was impacted to be conservative in this analysis. In addition, there is 

an existing No Activity Zone around Sackett Bank that mandates OCS energy-related, bottom-disturbing 

activities be located away from the bank. 

Impacts to Deepwater Corals as a Result of the Deepwater Horizon Event 

Although some corals on topographic features may have been impacted by oil that had adhered to 

organic material in the water column, as described above for Sackett Bank, or by low levels of oil in the 

water column, the benthic organisms on topographic features should not have been impacted as some 

deepwater corals were following the DWH event. A recent report documents damage to a deepwater 

(1,400-m; 4,593-ft) coral (gorgonian) community 11 km (7 mi) to the southwest of the well, in the 

direction of travel of the dispersed subsea oil plume. Results are still pending but it appears that a coral 

community in the CPA about 15 m x 40 m (50 ft x 130 ft) in size was severely damaged and may have 

been the result of contact with the dispersed subsea oil plume (Fisher, 2010; USDOI, BOEMRE, 2010j). 

Refer to Chapter 4.1.1.1.10 for a detailed description of the affected deepwater coral community. 

Coral communities and other benthic organisms on the topographic features should not have been 

affected by the subsea plume, as was the deepwater coral community, because of topographic feature 

structure, location on the continental shelf, and the currents in the Gulf. Topographic features are hard 

substrates that rise above the seafloor, and epibenthic growth is greatest towards the peak of the 

structures. The DWH subsea dispersed plume traveled downslope on the seafloor into deeper water away 

from the topographic features located on the continental shelf (OSAT, 2010). Therefore, the direction of 

travel of the plume was away from and much deeper than the growth on the topographic features. In 

addition, deep currents do not typically transit from deep water up onto the shelf where the topographic 

features are located (Pond and Pickard, 1983; Inoue et al., 2008). Based on these facts, it is unlikely that 

the organisms on the topographic features were exposed to the environmental conditions of the dispersed 

subsea plume to which the deepwater corals were exposed. 

Limited data are currently available on potential impacts of the DWH event on the topographic 

features in the CPA. This incomplete or unavailable information may be relevant to reasonably 

foreseeable significant impacts to topographic features. Relevant data on the status of topographic 

features after the DWH event may take years to acquire and analyze. Much of this data is being 

developed through the NRDA process, which may take years to complete. Little data from the NRDA 

process have been made available to date. Therefore, it is not possible for BOEM to obtain this 

information within the timeframe contemplated in this Supplemental EIS, regardless of the cost or 

resources needed. The BOEM has determined that this incomplete or unavailable information may be 

essential to a reasoned choice among alternatives. In the place of this incomplete or unavailable 

information, BOEM subject-matter experts have used available scientifically credible evidence in this 

analysis and applied it using accepted scientific methods and approaches. 

As a conservative approach, BOEM is assuming for purposes of this Supplemental EIS that the 

Sackett Bank feature was likely impacted. In addition, implementation of the proposed Topographic 

Features Stipulation would be expected to protect sensitive habitat (including those that may have been 

impacted by the DWH event) from routine impacts from oil and gas production, 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. 
4-164 Central Planning Area Supplemental EIS 

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 ASLM, 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. 

Clarification on how the proposed Topographic Features Stipulation applies to operators is detailed in the 

NTL 2009-G39 (USDOI, MMS, 2009b). 

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. 

Potential construction impacts to reefs and banks can be substantially reduced by the proposed 

Topographic Features Stipulation, which requires all bottom-disturbing activity to be at least 152 m 

(500 ft) away from the boundaries of No Activity Zones. The proposed Topographic Features Stipulation 

limits impact through the No Activity Zone and shunting restrictions imposed within the 1,000-Meter 

Zone, 1-Mile Zone, 3-Mile Zone, and 4-Mile 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, the U.S. Environmental Protection Agency’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 

proposed Topographic Features Stipulation and USEPA’s discharge regulations, turbidity and smothering 

impacts of sessile invertebrates on topographic features caused by drilling muds and cuttings are unlikely 

(Neff, 2005). 

The proposed Topographic Features Stipulation would protect sensitive reef species from smothering 

and turbidity through physical distance from drilling activities. The greatest impacts from drilling occur 

close to the well where a majority of the cuttings settle (Kennicutt, 1995). Reduced coral cover was 

reported out to 65 m (213 ft) from a well in Puerto Rico, which was probably a result of cuttings 

deposition (Hudson et al., 1982). Corals beyond this distance did not show reduced surface cover 

(Hudson et al., 1982). Impacts to benthic communities as a result of drilling operations in the Gulf of 
Description of the Environment and Impact Analysis 4-165 

Mexico are generally localized and have been reported 100-200 m (328-656 ft) from the production 

platform (Montagna and Harper, 1996; Kennicutt at al., 1996; Hart et al., 1989; Kennicutt, 1995; CSA, 

2004b). 

Differences in the dispersal patterns for well cuttings and drilling muds would result from differences 

in disposal methodology (i.e., 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 physically dispersing 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). Deeper water wells that 

use bottom shunting have exhibited deposition up to 500 m (1,640 ft) from a well due to the low-energy 

environment in deep water (Kennicutt et al., 1996). Deepwater bottom-shunted cuttings, however, would 

not affect the organisms on topographic features because the cuttings are deposited on the seafloor, far 

below the active zone of growth on the topographic features. 

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., 1980a; 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., 1980a). 

The measured concentration of drilling mud in the water at 1 m (3 ft) from the source was far below 

that which caused mortality to several species of coral in bioassays (Shinn et al., 1980b; Thompson et al., 

1980; Raimondi et al., 1997). Concentrations of drilling muds were measured between 10.2 and 

79.78 mg/L at 1 m (3 ft) from the source, which is below the concentration (100 ppm, 100 mg/L) reported 

to cause polyp retraction; reduced feeding; and decreased calcification, growth, respiration, 

photosynthesis, and NO3 and NH4 uptake; and possible impaired sediment rejection abilities in 

Montastrea annularis after 6-7 weeks of exposure (Shinn et al., 1980b; Thompson et al., 1980; SzmantFroelich et al., 1981; Dodge, 1982). These physiological impacts, however, sometimes led to death 

(Szmant-Froelich et al., 1981; Dodge, 1982). The measured concentrations are also less than those 

observed to cause excessive zooxanthellae loss in Acropora cervicornis (500 ppm) over 24 hours, death 

of Paracyathus stearnsii (200 ppm) after 6 days, reduced growth in Montastrea annularis over 7.5 hours 

(18 ppg in 200-mL doses, applied 2-4 mm thick directly on coral), and increased oxygen consumption and 

ammonium excretion, reduced feeding, expulsion of photosynthetic zooxanthellae, and bacterial 

infections paired with algal overgrowth in Madracis decactis (100 ppm drilling mud enriched with 

ferrochrome lignosulfonate [clay thinning agent]) over 17 days (Kendall et al., 1983; Raimondi et al., 

1997; Hudson and Robbin, 1980a; 1980b; 1980c; Krone and Biggs, 1980). Coral sensitivity to drilling 

mud, however, is both species and drilling mud specific (Thompson and Bright, 1980). Exposures to 

drilling mud concentrations that result in mortality in some coral species may only cause sublethal 

responses or no response at all from other corals (Thompson et al., 1980). 

Drilling mud concentrations at 6 m (20 ft) from the discharge were often less than those produced 

during storms or from boat wakes, and at 96 m (315 ft), they were less than suspended sediment 

concentrations measured on a windy day in coral reefs off Florida and far below concentrations measured 

to cause physiological impacts to corals (Shinn et al., 1980a and 1980b; Thompson et al., 1980; SzmantFroelich et al., 1981; Kendall et al., 1983). The toxic effects measured as a result of exposure to drilling 

mud are not caused by turbidity alone but by the compounds in the drilling mud (Kendall et al., 1983). 

Extrapolation of data collected from bioassays indicates the no-effect concentration of drilling mud to be 

3.99 ppm, which is above the average concentration of drilling mud measured in the water column 96 m 
4-166 Central Planning Area Supplemental EIS 

(315 ft) from platforms (Kendall et al., 1983; Shinn et al., 1980b). Based on those values, there should be 

no effects from drilling mud 96 m (315 ft) from a platform. 

It is not anticipated that muds drifting in the water column would settle on or smother 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., 1980a and 1980b; Hudson and Robbin, 

1980a and 1980c). 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., 1980a; Hudson and Robbin, 1980a; Thompson et al., 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 emergent reefs. Both distance from drilling operations and 

the 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. 

Long-Term and Operational Impacts on Topographic Features 

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 because the elements in the produced water 

may remain in the water column or attach to particles and settle to the seafloor (Burns et al., 1999). 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. 

Produced waters are rapidly diluted and impacts are generally only observed within proximity of the 

discharge point (Gittings et al., 1992a). Models have indicated that the vertical descent of a surface 

originating plume should be limited to the upper 50 m (164 ft) of the water column and that the maximum 

concentrations of surface plume water have been measured in the field between 8 and 12 m (26 and 39 ft) 

(Ray, 1998; Smith et al., 1994). Plumes have been measured to dilute 100 times within 10 m (33 ft) of 

the discharge and 1,000 times within 103 m (338 ft) of the discharge (Smith et al., 1994). Modeling 

exercises showed hydrocarbons to dilute 8,000 times within 1 km (0.6 km) of a platform and constituents 

such as benzene and toluene to dilute 150,000 and 70,000 times, respectively, within that distance (Burns 

et al., 1999). 

The less soluble fractions of the constituents in produced water associate with suspended particles and 

may sink (Burns et al., 1999). Particulate components were reported to fall out of suspension within 

0.5-1 nmi (0.6-1.2 mi; 0.9-1.9 km) from the source outfall (Burns et al., 1999). The particulate fraction 

disperses widely with distance from the outfall and soluble components dissolve in the water column, 

leaving the larger, less bioavailable compounds on the settling material (Burns et al., 1999). Due to the 

distance requirement for production platforms from topographic features, dispersion of particles in the 

water column, and currents around topographic features, the particulate constituents of produced waters 

should not impact biological communities on topographic features (Burns et al., 1999; Rezak et al., 1983; 

McGrail, 1982). 

Waterborne constituents of produced waters can influence biological activity at a greater distance 

from the platform than particulate components can (Osenberg et al., 1992). The waterborne fractions 

travel with currents; however, data suggest that these fractions remain in the surface layers of the water 

column (Burns et al., 1999). Measurements of toluene, the most common dissolved hydrocarbon in 
Description of the Environment and Impact Analysis 4-167 

produced waters, revealed rapid dilution with concentrations between 1 and 10 ng/L (0.000001-0.00001 

ppm) <2 km (1.2 mi) directly downcurrent from the source and rapid dispersion much closer to the source 

opposite the current (King and McAllister, 1998). Monitoring studies of the Flower Garden Banks 

located <2 km (1.2 mi) from a production platform did not indicate negative effects throughout the 

duration of the platform’s operation, most likely due to the influence of currents (Gittings at al., 1992a). 

Many currents sweep around banks in the GOM instead of over them, which would protect reef 

organisms from contact with a produced-water plume (King and McAllister, 1998; Gittings at al., 1992a; 

Rezak et al., 1983; McGrail, 1982). Modeling data for a platform in Australia indicated the plume to 

remain in the surface mixed layer (top 10 m [33 ft]) of the water column, which would further protect 

topographic features from produced water traveling with currents because crests of features are generally 

15 m (49 ft) or more below the sea surface (Burns et al., 1999; Rezak et al., 1983). 

Acute effects caused by produced waters are likely only to occur within the mixing zone around the 

outfall (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). Another study in Australia reported that the average total concentration of 

20 aromatic hydrocarbons measured in the water column 20 m (66 ft) from a discharge was <0.5μg/L 

(0.0005 mg/L or 0.0005 ppm) due to the rapid dispersion of the produced water plume (Terrens and Tait, 

1996). 

Compounds found in produced waters are not anticipated to bioaccumulate in marine organisms. 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. 

Metals including barium, cadmium, mercury, nickel, lead, and valadium in the tissue of the clam, Chama 

macerophylla, and the oyster, Crassostrea virginica, collected within 10 m (33 ft) of discharge pipes on 

oil platforms were not statistically different from reference stations (Trefry et al., 1995). Because highmolecular 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). 

Chronic effects including decreased fecundity; altered larval development, viability, and settlement; 

reduced recruitment; reduced growth; reduced photosynthesis by phytoplankton; reduced bacterial 

growth; alteration of community composition; and bioaccumulation of contaminants were reported for 

benthic organisms close to discharges and out to 1,000 m (3,281 ft) from the discharge (Holdway, 2002; 

Burns et al., 1999). Effects were greater closer to the discharges, and responses varied by species. High 

concentrations of produced waters may have a chronic effect on corals. The Australian coral, Plesiastrea 

versipora, when exposed to 25 percent and 50 percent produced water, had a significant decrease in 

zooxanthellae photosynthesis and often bleached (Jones and Heyward, 2003). Experiments using the 

WAF’s of produced waters indicated that coral fertilization was reduced by 25 percent and that 

metamorphosis was reduced by 98 percent at 0.0721 ppm total hydrocarbon (Negri and Heyward, 2000). 

The WAF, however, is based on a closed experimental system in equilibrium and may be artificially low 

for the Gulf of Mexico, which will not reach equilibrium with contaminants. The experimental value can 

be considered a “worst-case scenario” if the entire Gulf were to come in equilibrium with oil inputs. 

Produced waters should not impact 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, elevated concentrations of compounds measured near outfalls would not reach corals on 

banks in the GOM due to the high dilution rates of produced waters (King and McAllister, 1998), 

influence of currents around topographic features (Rezak et al., 1983; McGrail, 1982), and drilling 

distance required by the proposed Topographic Features Stipulation. Also, USEPA’s general NPDES 

permit restrictions on the discharge of produced water, which require the effluent concentration 100 m 
4-168 Central Planning Area Supplemental EIS 

(328 ft) from the outfall to be less than the 7-day “no observable effect concentration” based on 

laboratory exposures, would help to limit the impacts on biological resources of topographic features 

(Smith et al., 1994). Measurements taken from a platform in the Gulf of Mexico showed discharge to be 

diluted below the “no observable effect concentration” within 10 m (33 ft) of the discharge (Smith et al., 

1994). Such low concentrations would be even farther diluted at greater distances from the well. 

Structure-Removal Impacts 

The impacts of structure removal on soft-bottom benthic communities surrounding topographic 

features 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 that could impact surrounding reef environments. 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 of coral 

zooxanthellae (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 have some ability to rid themselves of some 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, lesions, increased mucus production, alterations in growth rates and forms, 

decreased calcification, decreased photosynthesis, increased respiration, reduced areal coverage, changes 

in species diversity and dominance patterns, reduced recruitment, reduced reef development, and 

mortality (Marszalek, 1981; Rice and Hunter, 1992; 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). 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., 1992c). 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). Corals on reefs surrounded by strong, complex currents are further protected from 

sedimentation because the currents help prevent the settling of fine particles onto the reef (Hudson and 

Robbin, 1980a, 1980b, and 1980c). 

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-kg 

(298-lb) charges in open water incurred a 5-percent mortality rate. Very few crabs died when exposed to 

14-kg (31-lb) charges in open water 46 m (150 ft) away from the explosions. 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 
Description of the Environment and Impact Analysis 4-169 

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 BSEE’s 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 since all the steps 

for removal, except final extraction from the water, would still occur. 

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 (coastline to 60 m [197 ft] of water). 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 (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 

(coastline to 60 m [197 ft] of water) 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 
4-170 Central Planning Area Supplemental EIS 

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 BSEE as needed in the activity permitting process. 

Summary and Conclusion 

The proposed Topographic Features Stipulation, if applied, 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 through avoidance, by requiring 

individual activities to be located at specified distances from the feature or zone. 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 BOEM acknowledges that 

impacts from routine activities without the Proposed Topographic Features Stipulation could be greater 

for those topographic features that may have been already impacted by the DWH event. 

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. Construction 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 exclusion zones would 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 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 
Description of the Environment and Impact Analysis 4-171 

spills and blowouts, have the potential to disrupt and alter the environmental, commercial, recreational, 

and aesthetic values of topographic features of 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 ASLM, be made a part of appropriate leases resulting from this proposed action. Although 

the lease stipulation was created to protect topographic features from routine impacts of drilling and 

production, they also protect topographic features from accidental impacts by distancing wells from the 

features. The impact analysis of accidental events 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 around topographic features, which distances these 

features from possible accidental impacts that could occur. Clarification on how the proposed 

Topographic Features Stipulation applies to operators is detailed in NTL 2009-G39 (USDOI, MMS, 

2009b). 

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 

benthic 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 BOEM 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 
4-172 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 BOEM’s 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 on topographic features. 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. Studies have indicated that, even if a surface oil slick were to occur above 

the topographic features, including the Flower Garden Banks, the impacts of the oil would be limited to 

the upper layers of the water column (Guillen et al., 1999). 

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 stipulations that are 

written into lease sales, which distances these activities from topographic features by creating No Activity 

Zones around the features and by placing an additional 152-m (500-ft) buffer beyond the No Activity 

Zone, as described in the NTL 2009-G39 (USDOI, MMS, 2009b). As distance increases, this allows for 

several physical and biological changes to begin to occur to the oil before it reaches sensitive benthic 

organisms. Dilution of oil may occur 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 

would be (Vandermeulen, 1982; Tkalich and Chan, 2002). Microbial degradation of the oil would begin 

in the water column, reducing toxicity (Hazen et al., 2010; McAuliffe et al., 1981b). In addition, oil can 
Description of the Environment and Impact Analysis 4-173 

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 reefs and banks should 

be physically protected because currents generally move around the topographic features, which may help 

sweep the subsea oil clear of the banks (Bright and Rezak et al., 1978; Rezak 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 responses 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., 1992b), 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). 
4-174 Central Planning Area Supplemental EIS 

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). 

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. 

There was, however, a recent report that indicated damage to a deepwater coral community in the 

CPA (11 km [7 mi] from the Macondo well) in water far deeper than the reef organisms on the 

topographic features (USDOI, BOEMRE, 2010j). This deepwater coral community appears to have been 

impacted by contact with oil resulting from the DWH event (USDOI, BOEMRE, 2010j). Refer to 

Chapter 4.1.1.10 for a detailed description of the affected deepwater coral community. The 

circumstances of the deepwater coral exposure appear to be unique because the release of oil was 

approximately 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 (1,100-1,300 m; 3,600-4,265 ft) 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. This situation identified with this deepwater coral community in the CPA 

would not be expected to occur on the continental shelf where the topographic features are located. 

Stratified waters (nepheloid layer) found on the continental shelf are normally restricted to near the 

seafloor 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 <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 typically travel around, not over, 

topographic features, directing oil away from topographic highs rather than over them (Rezak et al., 

1983). It is possible, however, that some of the banks with lower relief, which may frequently be covered 

by the nepheloid layer (Bright and Rezak, 1977), could encounter oil trapped in this density layer. 

It is important to note that the lease stipulations described in NTL 2009-G39 protect topographic 

features from both routine and accidental impacts that may occur during petroleum production. These 

stipulations focus OCS activities at specified distances from the topographic features, thereby increasing 

the distance between the topographic features and a possible accidental event. In the case of a spill, this 

distance would reduce the potential for contact with the features, as the released oil would be expected to 

rise to the surface and disperse in the water. 

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). 
Description of the Environment and Impact Analysis 4-175 

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 biological impacts that 

may occur from dispersant usage are greatest within the first hour of application and occur primarily to 

organisms living near the water’s surface (Guillen et al., 1999). 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 

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 or other 

topographic features, could result in impacts to the features because dispersants allow floating oil to mix 

with water. The Flower Gardens Oil Spill Mitigation Workgroup, for example, discourages the use of 

dispersants near the Flower Garden Banks, especially from May to September when coral is spawning 

(Guillen et al., 1999). Mechanical oil cleanup is suggested during this time of year because coral larvae is 

sensitive to dispersants and the sea state is calm, allowing for mechanical removal (Guillen et al., 1999). 

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; however, 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. But, as stated above, the use of 

dispersants near protected features is left to the discretion of the Federal On-Scene Coordinator on a caseby-case basis. 

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 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 topographic features would 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). As discussed above, 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), bounded by stratified density 

layers of water (Joint Analysis Group, 2010a). Stratification on the continental shelf, such as that 

observed in the turbid nepheloid layer, is normally restricted to 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 
4-176 Central Planning Area Supplemental EIS 

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). 

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 

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 toxic to corals during some 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). Longterm 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., 1992b 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 
Description of the Environment and Impact Analysis 4-177 

Aurand, 1997). Oil may also reach the seafloor through consumption by plankton with excretion 

distributed over the seafloor (ITOPF, 2002). 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; 1977; Deleersnijder 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 BOEM’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 on topographic 

features 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 organisms. 

Turbid waters have less light penetrating to depth, which may result in reduced photosynthesis by the 

symbiotic zooxanthellae that live in hermatypic 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 
4-178 Central Planning Area Supplemental EIS 

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). 

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 BOEM-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 so 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. 
Description of the Environment and Impact Analysis 4-179 

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 BOEM’s proposed 

stipulation (described in 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 distance requirements of bottom-disturbing activity written in BOEM’s proposed 

stipulations. 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 

topographic feature’s No Activity Zone to prevent adverse effects from nearby drilling. The BOEM has 

created a No Activity Zone around topographic features in order to protect these habitats from routine 

activity disruption due to oil and gas activities. The No Activity Zone also creates a buffer between 

drilling activity and sensitive organisms. Although the buffer was created to distance routine oil and gas 

activity from topographic features, it also provides some protection from an accidental event. For 

example, if a blowout were to occur at a well, a majority of the oil would rise to the water’s surface 

before it traveled horizontally toward a topographic feature. The surface oil would then float above the 

features, substantially reducing the possibility of physical oiling due to the distance of the features below 

the water’s surface and the physical mixing ability of oil into the water column (Lange, 1985; McAuliffe 

et al., 1975 and 1981a; Tkalich and Chan, 2002; Guillen et al., 1999). The oil should remain above the 

zones of active biologic growth, provided that dispersants are not used near the topographic features. The 

Flower Gardens Oil Spill Mitigation Workgroup, for example, discourages the use of dispersants near the 

Flower Garden Banks, especially from May to September when coral is spawning (Guillen et al., 1999). 

However, the use of dispersants near protected features is left to the discretion of the Federal On-Scene 

Coordinator on a case-by-case basis. 

Although BOEM’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 despite this 152-m (500-ft) buffer. 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 

As described above, a subsurface spill or plume may impact topographic features. As described in 

Table 3-5, BOEM estimated the potential number of accidental events likely to occur during the 40-year 

leasing scenario for the OCS Program. Oil or dispersed oil from an accidental event may cause lethal or 

sublethal impacts to reef organisms wherever a plume may contact them. The likelihood of a lowprobability, large-impact catastrophic spill, however, remains remote and is described in Appendix B.

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 result in a limited impact to these features. Also, the low probabilities of 
4-180 Central Planning Area Supplemental EIS 

oil reaching the surface waters above these banks, based on the OSRA model, combined with the limited 

depth of mixing of surface oil to the crests of these features function to protect 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. Other policies, such as the one implemented by NOAA for 

the Flower Gardens National Marine Sanctuary, requires dispersants to be applied as far from the Flower 

Gardens as possible. 

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, if applied, 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. It 

would be expected that the majority of oil would rise to the surface and that the most heavily oiled 

sediments would likely be deposited before reaching 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 more susceptible to 

adverse 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, 

along with oil-spill-response activities such as the use of dispersants. 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). The use of dispersants near or above protected features, such as the 

topographic features, could result in impacts to the features because dispersants allow floating oil to mix 

with water. Nevertheless, it is up to the sole discretion of the Federal On-Scene Coordinator as to 

whether or not dispersants will be used near topographic features during an accidental event. 

Disturbances, including oil spills and blowouts, could 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 
Description of the Environment and Impact Analysis 4-181 

oil have a prolonged or recurrent contact with the organisms. Accidental events related to 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. 

OCS Leasing-Related Impacts 

Mechanical damage, including anchoring, is considered to be a catastrophic threat to the biota of 

topographic features. 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., 1983). The proposed Topographic Features Stipulation (Chapter 2.4.2.3.1) 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 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). The shunting of drill muds and cutting to within 10 m (33 ft) of the seabed 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 where 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 it can be physically removed by currents that can shed the mucustrapped particles from the coral (Shinn et al., 1980a; Hudson and Robin, 1980a). 

The USEPA, through its NPDES discharge permit, also enacts further mitigating measures on 

discharges. As noted in Chapter 4.2.1.7.2 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 have minimal effects on the biota. 

With the inclusion of the proposed Topographic Features Stipulation, no discharges of produced 

water would take place within the No Activity Zone. The rapid dispersion of produced waters into the 

surrounding waters, combined with USEPA’s discharge regulations and permits, should eliminate the 

threat of discharges reaching and affecting the biota of a topographic high. Any impacts that these 

discharges could cause would be primarily sublethal, and 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 physical mixing depths of surface oil, paired with 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 
4-182 Central Planning Area Supplemental EIS 

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 shortterm 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 

the peaks of topographic features 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 most of the topographic features of the CPA 

were impacted by the DWH event because of their distance from the blowout. The bank that was closest 

to the spill, Sackett Bank, may have been impacted by oil that adhered to organic material settling out of 

the water column onto the bank. This bank, however, should not have experienced physical oiling 

because it has a crest 63 m (207 ft) below the surface, far below the physical mixing depth of oil. If any 

impacts did occur to the other topographic features in the CPA, they were sublethal and may include 

reduced recruitment success, reduced growth, and reduced coral cover as a result of impaired recruitment. 

These impacts, if they occurred, 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 3-3). 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. 

Non-OCS Leasing-Related Impacts 

Although the 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, 

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; and treasure hunters have damaged the 

bank as recently as 2001 (Schmahl and Hickerson, 2006). 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). The 

recovery from such destructive activity may take in excess of 10 years (Fucik et al., 1984; Rogers and 
Description of the Environment and Impact Analysis 4-183 

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-Hurricane 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 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. 

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. 

Application of 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’s 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. The majority of oil released below the sea surface rises and 

should not physically contact organisms on topographic features inside a No Activity Zone. In the 

unlikely event that oil from a subsurface spill would reach the biota of a topographic feature, it would be 

physically or chemically dispersed to low concentrations by the time it reached the feature, and the effects 

would be primarily sublethal. In the very unlikely 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. 
4-184 Central Planning Area Supplemental EIS 

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 when compared with non-OCS impacts. Where the proposed Topographic Features Stipulation 

is applied, mechanical impacts (anchoring and structure emplacement) and impacts from operational 

discharges (produced waters, drilling fluids, cuttings) or accidental discharges (oil spills, blowouts) would 

be removed from the immediate area surrounding the topographic features. 

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 BOEM. 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 

oxygen. Recent findings suggest that Sargassum provides essential 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 
Description of the Environment and Impact Analysis 4-185 

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. 

Sea 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. 

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 
4-186 Central Planning Area Supplemental EIS 

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. Sargassum has been noted to have higher levels of toxins than 

in surrounding water samples in polluted areas. Note that there are scores of natural hydrocarbon seeps in 

the GOM that contribute hydrocarbons to oceanic waters. Oceanographic processes that concentrate 

Sargassum into mats and rafts may also concentrate toxic substances. 

The DWH event released an estimated 4.9 million bbl of oil into the water over a period of 87 days. 

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 at the sea surface was dictated by 

wind, water currents, density, and the physical processes of degradation and dissolution. Hydrocarbon 

concentrations in the water column (Adcroft et al., 2010; Joint Analysis Group, 2010a; Lubchenco et al., 

2010; OSAT, 2010) were close to, and below, the values reported by others for dispersed oil in the upper 

water column after oil spills. Field studies on dispersants have indicated that dispersed surface oil may be 

between 20 ppm and 50 ppm at 1-5 m (3-16 ft) from the water’s surface (McAuliffe et al., 1981a; Lewis 

and Aurand, 1997). McAuliffe et al. (1981a) reported dispersed oil concentrations between 1 and 3 ppm 

at 9 m (30 ft) below the sea surface at 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. 

Since Sargassum is a floating pelagic algae that is ubiquitous in the northern GOM, the portion of the 

population affected by DWH oil would be similar to the portion of the surface waters affected. The 

highest concentration of Sargassum in the GOM during the months of June and July was in the vicinity of 

the DWH event in the CPA. Numerous anecdotal accounts, photos, blogs, and news stories reported 

Sargassum mixed with surface oil, but no study results are available at this time (USDOC, NOAA, 

2010g; GMFMC, 2011a). Sargassum populations in the CPA at the time would have been affected, while 

populations in the WPA were unaffected. Spill and cleanup efforts may have affected Sargassum in the 

spill area to some extent. Efforts to collect and burn oil on the sea surface would have taken Sargassum
Description of the Environment and Impact Analysis 4-187 

as well. Efforts to skim oil from the sea surface may have exacerbated the effect on Sargassum by 

sweeping the algae into oil and/or collecting it with oil. 

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. Impacts to Sargassum from the DWH event may have induced measurable 

changes in 2010. The algae population may be expected to recover in 1-2 seasons, but results are not 

available yet to make this determination. 

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. 

There remains incomplete or unavailable information on the effects of the DWH event on Sargassum 

that may be relevant to reasonably foreseeable significant adverse impacts. What scientifically credible 

information is available has been applied by BOEM subject-matter experts using accepted scientific 

methodologies. Samples and results developed as part of the NRDA process have not been released and 

there is no timeline for this information becoming available. Nevertheless, BOEM has determined that 

this incomplete or unavailable information is not essential to a reasoned choice among alternatives, 

because Sargassum are widely distributed throughout the Gulf and the yearly cycle of replenishment for 

Sargassum indicates that impacts from the DWH event would be significantly reduced or eliminated 

within a year or two. 

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 factors 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 
4-188 Central Planning Area Supplemental EIS 

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 

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 would 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. Because these discharges are highly regulated for toxicity and 

because they would continue to be diluted in the Gulf water, reducing concentrations of any toxic 
Description of the Environment and Impact Analysis 4-189 

component, produced-water impacts on Sargassum would be minimal. 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 

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 would 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. This emulsion floats 

on the sea surface and would be carried by wind and currents, likely coinciding with at least some of the 

Sargassum community. 

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 until it dissolves, 

flocculates with particulate matter until it becomes heavy enough to sink to the seafloor, or is 

biodegraded. Oil treated with dispersant at depth would form underwater plumes that would not rise to 

the sea surface. Oil treated with dispersant on the sea surface would mix 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). Field studies on dispersants have indicated that dispersed surface oil may be between 20 ppm 

and 50 ppm at 1-5 m (3-16 ft) from the water’s surface (McAuliffe et al., 1981a; Lewis and Aurand, 

1997). McAuliffe et al. (1981a) reported dispersed oil concentrations between 1 and 3 ppm at 9 m (30 ft) 

below the sea surface at 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. As time passes, the oil would 

begin to adhere to particles in the water column, form clumps, and sink toward the seafloor and to 

biodegrade (ITOPF, 2002; Kingston, 1995). 

The effects of oil contact with Sargassum communities would 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 
4-190 Central Planning Area Supplemental EIS 

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 by surface oil 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 into 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 

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]). 

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 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 
Description of the Environment and Impact Analysis 4-191 

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 unique 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 

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., 1992c). 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. 
4-192 Central Planning Area Supplemental EIS 

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 

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. 

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. 

Impacts from the DWH event on Sargassum are expected to be significantly reduced or eliminated within 

the next few years. Due to the ubiquitous nature and widespread distribution of Sargassum in the Gulf 

and its annual cycle of growth, the overall population of Sargassum is expected to recover quickly. 

Summary and Conclusion 

Because of the ephemeral nature of Sargassum communities, many activities associated with the 

proposed action would have a localized and short-term effect. Sargassum occurs seasonally in almost 
Description of the Environment and Impact Analysis 4-193 

every part of the northern GOM, resulting in a wide distribution over a very large area. However, its 

occurrence is patchy, drifting in floating mats that are occasionally impinged on ships and on oil and gas 

structures. The large, scattered, patchy distribution results in only a small portion of the total population 

contacting ships, structures, or drilling discharges. There is also a low probability of a catastrophic spill 

to occur with the CPA proposed action. If such a spill did occur, Sargassum in that area is expected to 

suffer mortality. However, Sargassum resilience is good, and recovery is expected within one or two 

growing seasons. The incremental contribution of the proposed action to the overall cumulative impacts 

on Sargassum communities that would result from the OCS Program, environmental factors (such as 

hurricanes and coastal water quality), and non-OCS-related activities (such as non-OCS vessel traffic and 

commercial shipping) are expected to be minimal. 

4.1.1.9. Chemosynthetic Deepwater Benthic Communities 

The BOEM 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. 

4.1.1.9.1. 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 
4-194 Central Planning Area Supplemental EIS 

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. Nutrients in the system act as fertilizer, producing blooms in 

phytoplankton (single-celled algae). There is a time lag after each algae bloom as the zooplankton catch 

up with a corresponding bloom as they feed on the phytoplankton. The zooplankton then egests a high 

percentage of their food intake as feces that sink toward the bottom and provide nutrients to benthic 

(seafloor) communities. 

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 seven zones 

[Table 3-3 of the Multisale EIS] previously described by 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.) 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 

the 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 constitute 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). 

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. 
Description of the Environment and Impact Analysis 4-195 

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 

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 
4-196 Central Planning Area Supplemental EIS 

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 

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 an 87-day period 

following the event. Extensive literature, Internet, and database searches have been conducted for results 
Description of the Environment and Impact Analysis 4-197 

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, 2002). Oil also would have reached the 

seafloor through consumption by plankton with excretion distributed over the seafloor (ITOPF, 2002). 

Distribution of the dispersed oil was dictated by water currents, density, 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). 

Following the spill, oil was detected in the CPA in a subsurface plume between water depths of 

1,100 and 1,300 m (3,600 and 4,265 ft) to the southwest of the spill site (Camilli et al., 2010; OSAT, 

2010). It is important to note that the movement of oil was directional, with the water currents, thus 

potentially affecting only habitats downcurrent from the well. 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). Of approximately 

1,000 water samples collected in deep water (up to 350 km [220 mi] from the well site) and analyzed for 

volatile organic compounds (benzene, toluene, ethylbenzene, and xylene), 1.7 percent (63 samples) 

exceeded USEPA’s chronic aquatic life benchmark and 0.4 percent (16 samples) exceeded the acute 

toxicity benchmark (OSAT, 2010). All of these exceedances were within a 70-km (43-mi) radius of the 

spill site. Exceedances in sediment samples were confined to within 3 km (2 mi) of the spill site (OSAT, 

2010). Depending on how long it remained in the water column, subsea oil plumes may have been welldispersed and thoroughly degraded by biological action before contact with the seafloor. 

Lubchenco et al. (2010) and The Federal Interagency Solutions Group (2010) estimated that up to 

52 percent of the total spill volume remained at large in the GOM shortly after the Macondo well was 

capped on July 16, 2010 (in various forms: 16% chemically dispersed; 13% naturally dispersed; and 

23% other). The majority of the seafloor of the Gulf of Mexico is 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 
4-198 Central Planning Area Supplemental EIS 

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. As noted above, only sediments sampled within 3 km (2 mi) of the well site exceeded USEPA’s 

chronic aquatic life benchmark. 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 November 2010 report documents damage to a deepwater (1,400 m; 4,600 ft) coral (gorgonian) 

community 11 km (7 mi) to the southwest of the well, in the direction of travel and depth range of the 

subsea oil plume. Results are still pending but it appears that a coral community in the CPA about 

15 m x 40 m (50 ft x 130 ft) in size was severely damaged, likely the result of contact with the subsea oil 

plume (Fisher, 2010; USDOI, BOEMRE, 2010j; OSAT, 2010). (For more details about this site, see 

Chapter 4.1.1.10.1) 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. Some 

chemosynthetic organisms (tubeworms) similarly form structure that is elevated above the seafloor, 

making them also susceptable to oiling from a passing oil plume. The oil plume would pass over smooth 

soft bottom without adhering to the sediment, continuing the process of biodegradation in mid-water and 

continuing to be dispersed over a wide area. 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. The OSAT (2010) report 

verifies high concentrations of oil in 6 percent of sediment samples, confined to an area within 3 km 

(2 mi) of the well site. 

Due to the transient nature of the plume, it may not be possible to determine the concentrations of oil 

or dispersant to which the deep-sea corals were exposed or for how long they were exposed. The 

hydrocarbon concentrations in the water column and subsea plume (Adcroft et al., 2010; Joint Analysis 

Group, 2010a; Lubchenco et al., 2010) were close to, and below, the values reported by others for 

dispersed oil in the upper water column after oil spills. Field studies on dispersants have indicated that 

dispersed surface oil may be between 20 ppm and 50 ppm at 1-5 m (3-16 ft) from the water’s surface 

(McAuliffe et al., 1981a; Lewis and Aurand, 1997). 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). It is possible that seafloor communities that produce structural relief, such as chemosynthetic and 

coral communities, were exposed to concentrations of oil in this range, or higher, which could induce 

negative impacts. 

Studies and data are continuing to be developed in response to the DWH event. This information will 

likely be developed through the NRDA process. Unavailable information on the effects to 

chemosynthetic communities from the DWH event may be relevant to reasonably foreseeable significant 

impacts on chemosynthetic communities. The NRDA process is investigating impacts to chemosynthetic 

communities, but information collected to date has not been made available to the public. It may be years 

before this information becomes available, and certainly not within the timeframe of this Supplemental 

EIS process. It is not within BOEM’s ability to obtain this information, regardless of the costs involved. 

Nevertheless, BOEM believes that this incomplete or unavailable information would not be essential to a 

reasoned choice among alternatives because chemosynthetic communities are found throughout the Gulf 
Description of the Environment and Impact Analysis 4-199 

and because they are in patchy distributions, minimizing the number that would be likely to be impacted 

by any single event. The BOEM subject-matter experts have included what credible scientific 

information is available, and applied it using accepted scientific methodologies. 

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 
4-200 Central Planning Area Supplemental EIS 

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 

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 
Description of the Environment and Impact Analysis 4-201 

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 

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). 
4-202 Central Planning Area Supplemental EIS 

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 

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. 

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. 

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 
Description of the Environment and Impact Analysis 4-203 

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 BOEM’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. Without mitigation measures, 

these activities could result in smothering by the suspension of sediments or the crushing of organisms 

residing in these communities. Because of the avoidance policies described in NTL 2009-G40, the risk of 

these physical impacts is greatly reduced by requiring the avoidance of potential chemosynthetic 

communities. Information included in required hazards surveys for oil and gas activities depicts areas 

that could potentially harbor chemosynthetic communities. This allows BOEM to require avoidance of 

any areas that are conducive to chemosynthetic growth. 

The BOEM 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. 

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 
4-204 Central Planning Area Supplemental EIS 

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 oil is ejected into deep water under high pressure, resulting in 

vigorous turbulence and the formation of micro-droplets or if dispersants are applied on the sea surface or 

at depth (Appendix B). The dispersed oil would be suspended in the water column and would begin to 

dissolve, flocculate with particulate matter until it becomes heavy enough to sink and contact the seafloor, 

or biodegrades. 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. Epibenthic 

organisms that protrude above the sediment may be exposed to oil droplets in the water column or at the 

sediment/water interface. Oil plumes reaching chemosynthetic communities could cause oiling of 

organisms, resulting in the death of entire populations on localized sensitive habitats. Chemosynthetic 

communities form structure that protrudes up into the water column that could 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 without adhering to the sediment, continuing the process of biodegradation in mid-water and 

continuing to be dispersed over a wide area. Dispersed oil could also come in contact with burrowing 

benthic organisms that protrude up into the water column (e.g., bivalves, sea pens, burrowing cerianthid 

anemones, etc). However, during periods of poor water quality (e.g., the passage of an oil plume), 

benthic filter or suspension feeders have the ability to simply withdraw into the substrate until water 

quality improves. 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 

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. The 2,000-ft (610-m) 

avoidance required would protect sensitive communities from heavy sedimentation, with only light 

sediment components able to reach the communities in small quantities. 
Description of the Environment and Impact Analysis 4-205 

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 or if oil is ejected into 

deep water under high pressure, resulting in vigorous turbulence and the formation of micro-droplets, 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. Any epibenthic organisms 

that protrude up into the water column would be particularly susceptible to damage from a passing oil 

plume (if the oil plume is at the seafloor). 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 BOEM 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 (Appendix B) 

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. If such an event were to 

occur, it could take hundreds of years to reestablish the chemosythetic community in that location. 

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. 

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 
4-206 Central Planning Area Supplemental EIS 

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. 

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 could happen if oil is ejected into deep water under high pressure, resulting in vigorous turbulence 

and the formation of micro-droplets, but it 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 BOEM 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. 
Description of the Environment and Impact Analysis 4-207 

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 communities. 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 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 
4-208 Central Planning Area Supplemental EIS 

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. 

Although OCS activities are the primary impact-producing factors for these communities, the 

incremental contribution of the CPA proposed action to cumulative impacts is expected to be minimal. 

The BOEM’s protective measures would minimize the possible impacts caused by physical disturbance of 

the seafloor and minor impacts from sediment resuspension or drill cutting discharges, through avoidance. 

Adverse impacts will 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 BOEM used this location as a starting point and utilized the BOEM 

in-house 3-D 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 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 
Description of the Environment and Impact Analysis 4-209 

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 

BOEM 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, 

density, and the physical processes of degradation. Following the spill, oil was detected in the CPA in a 

subsurface plume between water depths of 1,100 and 1,300 m (3,600 and 4,265 ft) to the southwest of the 

spill site (OSAT, 2010). It is important to note that the movement of oil was directional, with the water 

currents, thus potentially affecting only habitats downcurrent from the well. Of approximately 

1,000water samples collected in deep water (up to 350 km [220 mi] from the well site) and analyzed for 

volatile organic compounds (benzene, toluene, ethylbenzene, and xylene), 1.7 percent (63 samples) 

exceeded USEPA’s chronic aquatic life benchmark and 0.4 percent (16 samples) exceeded the acute 

toxicity benchmark (OSAT, 2010). All of these exceedences were within a 70-km (43-mi) radius of the 

spill site. Exceedances in sediment samples were confined to within 3 km (2 mi) of the spill site (OSAT, 

2010). Depending on how long it remained in the water column, subsea oil plumes may have been welldispersed 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 scleractinian 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 in the GOM, Lophelia pertusa, is 

also a branching species. In addition, tests on a shallow tropical soft coral indicate relatively low toxic 

effects to the coral, suggesting that deepwater soft corals 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. 

Epibenthic organisms that protrude above the sediment may have been exposed to oil droplets in the 

water column or at the sediment/water interface. A recent report documents damage to a deepwater 

(1,400 m, 4,600 ft) coral (gorgonian) community 11 km (7 mi) to the southwest of the well, in the 
4-210 Central Planning Area Supplemental EIS 

direction of travel and depth range of the subsea oil plume. Results are still pending but it appears that a 

coral community in the CPA about 15 m x 40 m (50 ft x 130 ft) in size was severely damaged, likely the 

result of contact with the subsea oil plume (Fisher, 2010; USDOI, BOEMRE, 2010j; OSAT, 2010). 

Many of the gorgonians in the affected area were dead or dying, had areas bare of tissue, were covered 

with brown material, and had tissue falling off their skeletons (Fisher, 2010; Fisher, 2011). A colony of 

stony coral, Madrepora sp. (400 m; 1,300 ft away), did not appear to be as severely impacted, but there 

was some brown material on the coral along with sloughing tissue and abundant mucous (Fisher, 2010 

and 2011; USDOI, BOEMRE, 2010j). Two repeat visits to the gorgonian site in December 2010 and 

March 2011 revealed that the impacted coral did not appear to be improving, and hydrozoans were 

beginning to grow on the areas where corals died, which could introduce competition and secondary 

infection into the area (Fisher, 2011). 

Although coral was damaged 11 km (7 mi) from the well, sediment cores collected from this location 

did not contain levels of oil that exceeded USEPA’s aquatic life benchmarks (OSAT, 2010). A probable 

explanation for the detrimental impacts to corals, in the absence of USEPA’s aquatic life benchmark 

exceedances, is that the coral community forms structure that protrudes up into the water column that 

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 without adhering to the sediment, continuing the process of 

biodegradation in mid-water and continuing to be dispersed over a wide area. Dispersed oil could also 

come in contact with burrowing benthic organisms that protrude up into the water column (e.g., bivalves, 

sea pens, burrowing cerianthid anemones, etc). However, during periods of poor water quality (e.g., the 

passage of an oil plume), benthic filter or suspension feeders have the ability to simply withdraw into the 

substrate until water quality improves. 

Due to the transient nature of the plume, it may not be possible to determine the concentrations of oil 

or dispersant to which the deep-sea corals were exposed or for how long they were exposed. Field studies 

on dispersants have indicated that dispersed surface oil may be between 20 ppm and 40-50 ppm at 1-5 m 

(3-16 ft) from the water’s surface (McAuliffe et al., 1981a; Lewis and Aurand, 1997). It is possible that 

the gorgonians were exposed to concentrations of oil in this range, or higher, which could induce negative 

impacts in corals (Lewis, 1971; Cohen et al., 1977; Reimer, 1975; Peters et al., 1981; Loya and 

Rinkevich, 1979; Rinkevivh and Loya, 1977; Guzmán and Holst, 1993; Cook and Knap, 1983; Dodge et 

al., 1984; Burns and Knap, 1989; Jackson et al., 1989; Loya, 1976b; Guzmán et al., 1994; Kushmaro et 

al., 1997; Loya, 1975; Wyers et al., 1986; Knap et al., 1983; Elgershuizen & De Kruijf, 1976; Bak and 

Elgershuizen, 1976; Shafir et al., 2007). 

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 of mucus. 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. 

Benthic organisms in the CPA, including those emergent in the water column, greater than 70 km 

(43 mi) from the well should not have been exposed to lethal concentrations of oil because oil in the 

plume was diluting with distance from the well, decreasing in concentration with time, and there were no 

exceedances of USEPA’s aquatic life benchmarks for PAH measured in the water column more than 

70 km (43 mi) from the well (OSAT, 2010). The lower molecular weight aromatic compounds are those 

with the greatest toxicity and were the compounds that dissolved most readily into the water (The Federal 

Interagency Solutions Group, 2010; Brown et al., 2010; Eisler, 1987). The dissolution of oil, and 

especially the most toxic components, into surrounding water allowed for dilution that farther decreased 

the probability that concentrated oil could impact organisms farther than 70 km (43 mi) from the well. 

Studies and data are continuing to be developed in response to the DWH event. This information will 

likely be developed through the NRDA process. Unavailable or incomplete information on the effects to 
Description of the Environment and Impact Analysis 4-211 

nonchemosynthetic communities from the DWH event may be relevant to reasonably foreseeable 

significant impacts. The NRDA process is investigating impacts to nonchemosynthetic communities, but 

not all information collected to date is available to the public. It may be years before this information 

becomes available, and certainly not within the timeframe of this Supplemental EIS process. It is not 

within BOEM’s ability to obtain this information, regardless of the costs involved. Nevertheless, BOEM 

believes that this incomplete or unavailable information would not be essential to a reasoned choice 

among alternatives because nonchemosynthetic communities are found throughout the Gulf and are in 

patchy distributions, minimizing the number that would be likely be impacted by any single event. In 

addition, available data indicate significant impacts to one coral community that was only identified in 

one location 11 km (7mi) downcurrent from the Macondo well site. The BOEM subject-matter experts 

have included what credible scientific information is available and applied it using accepted scientific 

methodologies. 

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. Sediment from drilling discharges 

can clog feeding mechanisms of filter and suspension feeders such as mussels, clams, and tube worms. 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. The result of this dispersion is that seafloor habitats receive little additional 

sedimentation from drilling discharges in areas where it settles to the seafloor. Small amounts of 

sedimentation are normal for these environments. Structure placement, anchoring, and pipeline activities 

can physically crush organisms on or in the seafloor sediments. 

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 
4-212 Central Planning Area Supplemental EIS 

(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. 

Information included in required hazards surveys for oil and gas activities depicts areas that could 

potentially harbor nonchemosynthetic communities. This allows BOEM to require avoidance of any 

areas that are conducive to the growth of sensitive hard-bottom habitats. Impacts to hard-bottom 

communities are expected to be avoided as a consequence of the application of the guidelines for 

chemosynthetic communities in existing NTL 2009-G40. The same geophysical conditions associated 

with the potential presence of chemosynthetic communities also result in the potential occurrence of hard 

carbonate substrate and nonchemosynthetic communities. Because of the NTL 2009-G40 guidelines, 

these communities are generally avoided in exploration and development planning. 

Based on the additional information presented above, BOEM 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 
Description of the Environment and Impact Analysis 4-213 

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. 

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 oil is ejected into deep water under high pressure, resulting in 

vigorous turbulence and the formation of micro-droplets or if dispersants are applied on the sea surface or 

at depth (Appendix B). The dispersed oil would be suspended in the water column and would begin to 

dissolve, flocculate with particulate matter until it becomes heavy enough to sink and contact the seafloor, 

or biodegrade. 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. Epibenthic 
4-214 Central Planning Area Supplemental EIS 

organisms that protrude above the sediment may be exposed to oil droplets in the water column or at the 

sediment/water interface. Oil plumes reaching nonchemosynthetic communities could cause oiling of 

organisms resulting in the death of entire populations on localized sensitive habitats. Coral communities 

form structure that protrudes up into the water column that could 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 

without adhering to the sediment, continuing the process of biodegradation in mid-water and continuing 

to be dispersed over a wide area. Dispersed oil could also come in contact with burrowing benthic 

organisms that protrude up into the water column (e.g., bivalves, sea pens, burrowing cerianthid 

anemones, etc). However, during periods of poor water quality (e.g., the passage of an oil plume), 

benthic filter or suspension feeders have the ability to simply withdraw into the substrate until water 

quality improves. 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 

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 

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 or if oil is ejected into deep water under high pressure, resulting in 

vigorous turbulence and the formation of micro-droplets, 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. Any epibenthic organisms that protrude up into the water 

column would be particularly susceptible to damage from a passing oil plume (if the oil plume is at the 

seafloor). 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 BOEM 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 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. Periods as long as hundreds of years are required to reestablish a 

nonchemosynthetic seep community once it has disappeared (depending on the community type), 

although it may reappear relatively quickly once the process begins. 

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. 
Description of the Environment and Impact Analysis 4-215 

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. 

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 
4-216 Central Planning Area Supplemental EIS 

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 (6 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 could happen if oil is ejected into deep water under high pressure, resulting in vigorous turbulence 

and the formation of micro-droplets, or it 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 BOEM 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 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 
Description of the Environment and Impact Analysis 4-217 

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 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 BOEM’s biological review process and the 

use of NTL 2009-G40, which physically distances petroleum-producing activities from sensitive 

deepwater benthic communities. 

Although OCS activities are the primary impact-producing factors for these communities, the 

incremental contribution of the CPA proposed action to cumulative impacts is expected to be minimal. 

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 BOEM has reexamined the analysis 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. 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. 

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 

2009-2012 Supplemental EIS, and new information that has become available since both documents were 

prepared. 

The U.S. Gulf of Mexico marine mammal community is diverse and distributed throughout the 

northern Gulf waters. Twenty-one species of cetaceans regularly occur in the Gulf of Mexico (Jefferson 

et al., 1992; Davis et al., 2000) and are identified in the NMFS Gulf of Mexico Stock Assessment Reports 

(Waring et al., 2009), in addition to one species of Sirenian. 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. Most GOM cetacean species have worldwide distributions; however, two 
4-218 Central Planning Area Supplemental EIS 

exceptions are Atlantic spotted dolphins (Stenella frontalis) and Clymene dolphins (Stenella clymene). 

Common in the Gulf, these two species are found only in the Atlantic Ocean and its associated waters. 

There are species that have been reported from Gulf waters, either by sighting or stranding, that, due 

to their rarity in the CPA, are not considered further in this document. These species include the blue 

whale (Balaenoptera musculus), the North Atlantic right whale (Eubalaena glacialis), and the Sowerby’s 

beaked whale (Mesolplodon bidens), all considered extralimital in the GOM; and the humpback whale 

(Megaptera novaeangiliae), the fin whale (Balaenoptera physalus), the sei whale (Balaenoptera 

borealis), and the minke whale (Balaenoptera acutorostrata), all considered rare occasional migrants in 

the GOM (Wursig et al., 2000; Mullin and Fuling, 2004). Because these species are uncommon in the 

GOM (and by extension the CPA), they are not included in the most recent NMFS Stock Assessment 

Reports for the Gulf of Mexico (Waring et al., 2009). 

Threatened and Endangered Species 

There is only one cetacean, the sperm whale (Physeter macrocephalus), and one sirenian, the West 

Indian manatee (Trichechus manatus), that regularly occur in the GOM and that are listed as endangered 

under the ESA. The sperm whale is common in oceanic waters of the northern Gulf of Mexico and 

appears to be a resident species. 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. 

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 Johnson, 2007). Jochens et al. (2008) 

published a synthesis of work conducted as the Sperm Whale Seismic Study in the Gulf of Mexico. 

Genetic data from this study confirm that the Gulf of Mexico sperm whales constitute a 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 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 (Waring et al., 2009). For example, the Recovery Plan states that the 

impacts from fisheries are low since sperm whales may break through fishing gear. However, they may 

die later as a result of the entanglement, but the death would go unreported. Further, it states, “During 

2001-2005, human-caused mortality was estimated at 0.2 sperm whales per year (0.0 sperm whales per 

year from fisheries and 0.2 from ship strikes) off the east coast of the U.S. (Waring et al., 2009).” In 

regards to the effects of anthropogenic noise, the Recovery Plan states that it is “difficult to ascertain and 

research on this topic is ongoing. The possible impacts of the various sources of anthropogenic noise, 

described below, have not been well studied on sperm whales. The threat occurs at an unknown severity 

and there is a high level of uncertainty associated with the evidence described below. Thus, the relative 

impact of anthropogenic noise to the recovery of sperm whales is ranked as “unknown.” 

Manatees primarily inhabit open coastal (shallow nearshore) areas and estuaries, and they are also 

found far up in freshwater tributaries. During warmer months (June to September), manatees are 

common along the Gulf Coast of Florida from the Everglades National Park northward to the Suwannee 

River in northwestern Florida. Although manatees are less common farther westward, manatee sightings 

increase during the warmer summer months. 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 
Description of the Environment and Impact Analysis 4-219 

Florida. Florida manatees have been divided into four distinct regional management units: the Atlantic 

Coast Unit that occupies the east coast of Florida, including the Florida Keys and the lower St. Johns 

River north of Palatka, Florida; the Southwest unit that occurs from Pasco County, Florida, south to 

Whitewater Bay in Monroe County, Florida; Upper St. Johns River Unit that occurs in the river south of 

Palatka, Florida; and the Northwest Unit that occupies the Florida Panhandle south to Hernando County, 

Florida (Waring et al., 2009). Manatees from the Northwest Unit are more likely to be seen in the 

northern GOM and can be found as far west as Texas; however, most sightings are in the eastern Gulf of 

Mexico (Fertl et al., 2005). 

The best available count of Florida manatees is 3,802 animals, based on a January 2009 aerial survey 

of warm-water refuges (Waring et al., 2009). In 2010, of the 767 manatee carcasses collected in Florida, 

88 of these animals died of human causes (Florida Fish and Wildlife Conservation Commission, 2010a). 

Human causes included water control structures, entanglement in and ingestion of marine debris, 

entrapment in pipes/culverts, and collisions with watercraft. Ninety-four percent of manatees that died of 

human causes were killed by watercraft (Florida Fish and Wildlife Conservation Commission, 2010a). 

Recent Section 7 Endangered Species Consultation 

As mandated by the ESA, BOEM 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 (USDOC, NMFS, 2007b). 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 ESA consultation with FWS was 

concluded with a letter dated September 14, 2007. The FWS concurred with the BOEM 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. 

Following the DWH event, BOEM requested reinitiation of ESA Section 7 consultation with NMFS 

and FWS on July 30, 2010. The NMFS responded with a letter to BOEM on September 24, 2010; FWS 

responded with a letter to BOEM on September 27, 2010. The reinitiated consultations are not complete 

at this time, although BOEM, as lead agency, and BSEE are in discussions with both agencies. In the 

meantime, the current consultation remains in effect and recognizes that BOEM- and BSEE-required 

mitigations and other reasonable and prudent measures should reduce the likelihood of impacts from 

BOEM- and BSEE-authorized activities. Further, BOEM has determined, under Section 7(d) of the ESA, 

that the proposed action of this Supplemental EIS is not an irreversible or irretrievable commitment of 

resources, which has the effect of foreclosing the formulation or implementation of any reasonable and 

prudent alternative measures. The BOEM and BSEE are also developing an interim coordination 

program with NMFS and FWS while consultation is ongoing. 

Non-ESA Listed Marine Mammals 

One baleen cetacean (Bryde’s whale) and 19 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. 
4-220 Central Planning Area Supplemental EIS 

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 River), wind stress, and the Loop Current and its derived 

circulation phenomena. Circulation on the continental shelf is largely wind-driven, with localized effects 

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). 

Unusual Mortality Event for Cetaceans in the Gulf of Mexico 

On December 13, 2010, NMFS declared an unusual mortality event (UME) for cetaceans (whales and 

dolphins) in the Gulf of Mexico. An UME is defined under the Marine Mammal Protect Act as a 

“stranding that is unexpected, involves a significant die-off of any marine mammal population, and 

demands immediate response.” Evidence of the UME was first noted by NMFS as early as February 

2010. As indicated in the table below, a total of 550 cetaceans (4% stranded alive and 96% stranded 

dead) have stranded since the start of the UME, with a vast majority of these strandings involving 

premature, stillborn, or neonatal bottlenose dolphins between Franklin County, Florida, and the 

Louisiana/Texas border. The 562 includes 6 dolphins killed during a fish-related scientific study and 1 

dolphin killed incidental to a dredging operation. More detail on the UME can be found on NMFS’ 

website (USDOC, NMFS, 2011a). 

Unusual Mortality Event Cetacean Data for the Northern Gulf of Mexico 

(Numbers are preliminary and may be subject to change. As October 10, 2011, the UME 

involves 562 cetacean “strandings” in the northern Gulf of Mexico [USDOC, NMFS, 2011a]). 

Cetaceans Stranded Phase of Oil-Spill Response Dates 

113 cetaceans stranded prior to the response phase for the oil 

spill 

February 1, 2010 - 

April 29, 2010 

115 cetaceans stranded or were 

reported dead offshore 

during the initial response phase to the 

oil spill 

April 30, 2010 - 

November 2, 2010 

322 cetaceans stranded* after the initial response phase ended November 3, 2010 - 

October 10, 2011** 

*This number includes 6 dolphins that were killed incidental to fish-related scientific data collection and 

1 dolphin killed incidental to trawl relocation for a dredging project. 

**The initial response phase ended for all four states on November 3, 2010, but then re-opened for 

eastern and central Louisiana on December 3, 2010. 

It is unclear at this time whether the increase in strandings is related partially, wholly, or not at all to 

the DWH event. The NMFS has also documented an additional 11 UME’s that have been previously 
Description of the Environment and Impact Analysis 4-221 

declared in the GOM for cetaceans since 1991. However, the current data in the table above also shows a 

marked increase in strandings during the DWH event response and afterwards. According to the website, 

NMFS considers the investigation into the cause of the UME and the potential role of the DWH event to 

be “ongoing and no definitive cause has yet been identified for the increase in cetacean strandings in the 

northern Gulf in 2010 and 2011.” It is therefore unclear whether increases in stranded cetaceans during 

and after the DWH event response period are or are not related to impacts from the DWH event and will 

likely remain unclear until NMFS completes its UME and NRDA evaluation processes. 

All marine mammals collected either alive or dead were found east of the Louisiana/Texas border 

through Franklin County, Florida. The highest concentration of strandings has occurred off eastern 

Louisiana, Mississippi and Alabama with a significantly lesser number off western Louisiana and western 

Florida (USDOC, NMFS, 2011a, Map of Cetacean (Dolphin and Whale) Strandings in the Northern Gulf 

of Mexico).

Deepwater Horizon Event 

The DWH event in Mississippi Canyon Block 252 and resulting oil spill and related spill-response 

activities (including use of dispersants) have impacted marine mammals that have come into contact with 

oil and remediation efforts. According to NOAA, within the designated DWH spill area, 171 marine 

mammals (89% of which were deceased) were reported (USDOC, NMFS, 2011b). This includes 

155 bottlenose dolphins, 2 Kogia spp., 2 melon-headed whales, 6 spinner dolphins, 2 sperm whales, and 

4 unknown species (USDOC, NOAA, 2011b). All marine mammals collected either alive or dead were 

found east of the Louisiana/Texas border through Apalachicola, Florida. The highest concentration of 

strandings has occurred off eastern Louisiana, Mississippi, and Alabama, with a significantly lesser 

number off western Louisiana and western Florida (USDOC, NMFS, 2011b, Map of Cetacean (Dolphin 

and Whale) Strandings in the Northern Gulf of Mexico). Due to known low detection rates of carcasses, 

it is possible that the number of deaths of marine mammals is underestimated (Williams et al., 2011). It is 

also important to note that evaluations have not yet confirmed the cause of death, and it is possible that 

many, some, or no carcasses were related to the DWH oil spill.

Marine Mammal Resources in the Central Planning Area 

The final determinations on damages to marine mammal resources from the DWH event will 

ultimately be made through the NRDA process. The DWH event will allow a better understanding of any 

realized effects from such a low-probability catastrophic spill. However, the best available information 

on impacts to marine mammals does not yet provide a complete understanding of the effects of the oil 

spilled and of the active response/cleanup activities from the DWH event on marine mammals as a whole 

in the GOM and whether these impacts reach a population level. There is also an incomplete 

understanding of the potential for population-level impacts from the ongoing UME. 

Here, BOEM concludes that the unavailable information from these events may be relevant to 

reasonably foreseeable significant adverse impacts to marine mammals. In some specific cases, such as 

with bottlenose dolphins, the unavailable information may also be essential to a reasoned choice among 

the alternatives based on the discussion below. The costs for obtaining data on the effects from the UME 

and/or the DWH event are considerable, duplicative efforts are already being undertaken by other 

agencies (such as NMFS) that may be years away from conclusion, and it would likewise take BOEM 

years to acquire and analyze through the existing NRDA and UME processes. Further, impacts from the 

DWH event may be difficult or impossible to discern from other factors. For example, even 20 years 

after the Exxon Valdez spill, long-term impacts to marine mammal populations are still being investigated. 

(Matkin et al., 2008). Therefore it is not possible for BOEM to obtain this information within the timeline 

contemplated in this Supplemental EIS, regardless of the cost or resources needed. In light of the 

incomplete or unavailable information, BOEM subject-matter experts have used available scientifically 

credible evidence in this analysis and based upon accepted scientific methods and approaches. 

The BOEM does, however, provide the following analyses for select marine mammal species and as 

they relate to the CPA, relevant to the DWH event and UME discussion: 
4-222 Central Planning Area Supplemental EIS 

 Sperm whales are found in oceanic waters throughout the GOM and appear to be a 

resident species. During and following the DWH event and response, two sperm 

whales have been documented as oiled within the DWH affected area (USDOC, 

NMFS, 2011b). It is yet unknown whether the DWH event was the cause of death 

for these two individuals. Waring et al. (2009) reported the estimated population size 

of the northern GOM sperm whale population to be 1,665 individuals. Further, the 

potential biological removal for this population is 2.8 animals, based on a minimum 

population estimate of 1,409. The potential biological removal is defined 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” (Waring et al., 2009). If a protective assumption is 

made that the two sperm whales detected above were removed from the population as 

a result of the spilled oil and not natural causes (and coincidentally found floating in 

oiled areas), then the potential biological removal was not reached. Given that other 

sperm whales may have been killed but gone undetected (again this is a protective 

assumption due to low detection rates as described above), then there is the potential 

that the potential biological removal was reached and the population would no longer 

be operating at its optimum sustainable level. 

 It is important to note that “optimum sustainable level” does not mean jeopardy to the 

population (i.e., a change leading to extinction). Rather, it is defined under the 

MMPA to mean “a population size that falls within a range from the population level 

of a given species or stock, which is the largest supportable within the ecosystem to 

the population level that results in maximum net productivity. Maximum net 

productivity is the greatest net annual increment in population numbers or biomass 

resulting from additions to the population due to reproduction and/or growth less 

losses due to natural mortality” (50 CFR 216.3). In contrast, the term “jeopardy” 

under the ESA means “to engage in an action that reasonably would be expected, 

directly or indirectly, to reduce appreciably the likelihood of both the survival and 

recovery of a listed species in the wild by reducing the reproduction, numbers, or 

distribution of that species” (50 CFR 402.02). So, exceeding the potential biological 

removal does not imply jeopardizing the continued existence of the population but 

rather that it may no longer be operating as its optimum sustainable level. 

 The BOEM concludes that the unavailable information resulting from the DWH 

event and its impact to the sperm whale population baseline could be relevant to 

reasonably foreseeable significant adverse effects. Although activities will be 

ongoing under existing leases (there are 4,503 active leases in the CPA as of 

November 2011) whether or not the proposed action takes place, BOEM at this point 

cannot determine if potential incoming data and information from the DWH event 

would be essential to a reasoned choice among the alternatives. As noted above, this 

data is being developed through the NRDA process and at the direction of NMFS 

(which has jurisdiction over marine mammal strandings). It will be years before the 

studies currently under way produce available data. Little data, beyond raw numbers 

of strandings, have been made public through the NRDA process. For example, new 

data are still being investigated and developed 20 years after the Exxon Valdez event. 

In any event, this information will not be available within the timeframe of this 

Supplemental EIS. In its place, the scientifically credible information that is 

available has been incorporated using accepted scientific methodologies. In addition, 

the ESA consultation, which includes sperm whales, has been reinitiated and is 

ongoing; an interim coordination program, which may inform additional mitigations, 

is being developed with NMFS and FWS. 

 Bryde’s whales is the only known baleen whale species to occur regularly in the 

GOM. The NMFS treats Bryde’s whales found in the northern GOM as a separate 
Description of the Environment and Impact Analysis 4-223 

stock and estimates a minimum population size at 15 animals. Most sightings have 

occurred (based on limited survey effort) within De Soto Canyon, which are deeper 

waters off the coasts of Alabama and the western panhandle of Florida (Waring et al., 

2009). It is unknown whether any individuals of this stock were affected by the 

DWH event, although no reports of effects to Bryde’s whales have been made at this 

time. There is then the potential that this unavailable information could be relevant 

to reasonably foreseeable significant adverse effects. Activities will be ongoing 

under existing leases (4,503 active leases in CPA as of November 2011) whether or 

not the proposed action takes place. However, baseline information about this 

population even prior to the DWH event was minimal, and BOEM at this point 

cannot determine if potential incoming data and information from the DWH event 

would be essential to a reasoned choice among the alternatives. Due to difficulties 

inherent in researching this species in the Gulf (e.g., small population size), it is 

unlikely that research could be initiated, completed, and analyzed within the 

timeframe of this Supplemental EIS. The NRDA process may provide additional 

information about this species and potential impacts from the DWH event; however, 

these data are not currently available, and it may be years before such data are 

released or known. What scientifically credible information is available has been 

incorporated and applied using accepted scientific methodologies. 

 The major concentrations of stranded bottlenose dolphins from the ongoing UME 

occur within the eastern Louisiana, Mississippi, and Alabama coasts (USDOC, 

NMFS, 2011a, Map of Cetacean (Dolphin and Whale) Strandings in the Northern 

Gulf of Mexico). The proposed lease sale under this proposed action also covers 

these same areas. 

 For bottlenose dolphins, BOEM concludes that the unavailable information resulting 

from the DWH event and UME could be relevant to reasonably foreseeable 

significant adverse effects. The OCS activities will be ongoing under existing leases 

(4,503 active leases in CPA as of November 2011) whether or not the proposed 

action or any other alternative is selected. However, BOEM believes that the 

unavailable information may be essential to a reasoned choice among alternatives, 

particularly regarding the dolphin stocks affected by the UME and/or the DWH 

event. The NMFS is the lead agency investigating marine mammal strandings, 

including both the current UME and the DWH event. To date, NMFS has released 

only raw data on strandings. We are therefore unable to determine, at this point and 

time, what effect (if any) the DWH event had on bottlenose dolphins also affected by 

the UME. Due to legal constraints with marine mammal strandings (left solely 

within NMFS’ jurisdiction), BOEM does not have the ability to obtain its own data 

on stranded animals. The NMFS process will attempt to determine the cause of the 

UME, but this may take years to complete. Impacts from the DWH event may be 

difficult or impossible to discern from other factors. Therefore, it is not possible for 

BOEM to obtain this information within the timeline contemplated in this 

Supplemental EIS, regardless of the cost or resources needed. In light of the 

incomplete or unavailable information, BOEM subject-matter experts have used 

available scientifically credible evidence in this analysis and applied it using accepted 

scientific methods and approaches.

 Manatees generally occur in the GOM along the Gulf Coast of Florida from the 

Everglades National Park northward to the Suwannee River in northwestern Florida 

during the warmer months (June to September) and southward during the winter. 

They are less common farther west; however, individuals have been increasingly 

spotted as far as Texas during the summer months (Fertl et al., 2005). Further, there 

have not been any reported cases of manatees within areas affected by the DWH 

event. The BOEM concludes that available information is sufficient to conclude 

there was likely little to no effect to manatees from the DWH event and that the 
4-224 Central Planning Area Supplemental EIS 

potential for impacts from the current proposed action or alternatives also remains 

insignificant given the distance and the low number of manatees likely to occur 

within the proposed action area. 

The analyses in the Multisale EIS, the 2009-2012 Supplemental EIS, and this Supplemental EIS 

(Chapter 4.1.1.11.1 [affected environment], Chapter 4.1.1.11.2 [accidental spills], and Appendix B) 

conclude that there is a potential for low-probability catastrophic events to result in significant, 

population-level effects on certain affected marine mammal species. The BOEM continues to agree with 

these conclusions irrespective of any new or incomplete information, changes to the existing environment 

from the DWH event, or the effectiveness of implementation of the improved post-DWH safety and oilspill-response requirements 

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; anthropogenic noise generated by helicopters, vessels, operating platforms, 

and drillships; vessel traffic and potential for vessel strikes; 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). However, marine mammals are generally not considered good bioaccumulators 

of petroleum compounds from eating contaminated prey due to rapid metabolism and excretion rates 

(Neff, 1990). As such, impacts from discharges related to the proposed action would not be expected to 

result in long-term impacts to marine mammals because these compounds would not be assimilated. 

Deep-diving whales, such as the sperm whale, 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 (due to BOEM’s requirement under NTL 2007-G04 that 

vessels maintain a distance of 90 m [295 ft] from sperm whales) 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. Further, there have been no reports of 

mortality of marine mammals from ship strikes related to offshore oil and gas activities in the Gulf of 

Mexico. Although manatees have been killed by vessel strikes (e.g., Schiro et al., 1998), they are rare in 

the offshore GOM waters, 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 (Jochens et al., 2008). 

It is possible that anthropogenic noise can cause 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. 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. 
Description of the Environment and Impact Analysis 4-225 

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 activities resulting from the proposed 

action will 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. 

As a result, NMFS’s 2007 ESA Biological Opinion concluded that the effects to sperm whales from 

vessel noise are “discountable” due to BOEM’s requirement under NTL 2007-G04 that vessels maintain a 

distance of 90 m (295 ft) from sperm whales (USDOC, NMFS, 2007b). The BOEM 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 avoid 

entirely or minimize the chance of significant impacts to marine mammals from both the presence of a 

vessel and the noise it produces. 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. Based on the physics of sound propagation discussed here and with the addition of the 

BOEM requirements under NTL 2007-G04, behavioral disruptions potentially caused by noise and the 

presence of service-vessel traffic will therefore have negligible effects on cetacean populations in the 

northern Gulf of Mexico. 

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. 

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; however, there are occasional transient bangs and clangs from 

various impacts during operations (Richardson et al., 1995). Estimated frequencies from drilling by 

semisubmersible vessels 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 has 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 of 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), 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 effects increases when 

received levels increase from 120 to 160 dB. Marine mammals may exhibit some avoidance behaviors, 
4-226 Central Planning Area Supplemental EIS 

but their behavioral or physiological responses to noise associated with the proposed action, however, are 

unlikely to have population-level impacts to marine mammals in the northern Gulf of Mexico. 

The BOEM 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 BOEM 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 550 Subpart B, BOEM 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 Protected Species 

Stipulation and 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. 

These mitigations include onboard observers, airgun shut-downs for whales in the exclusion zone, rampup procedures, and the use of a minimum sound source. 

Mysticetes, as low-frequency hearing specialists, are the species group 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 (Southall et al., 2007). However, most 

mysticete species that could occur in the GOM (i.e., North Atlantic right, blue, fin, sei, humpback, and 

minke whales) are considered either “extralimital,” “rare,” or “uncommon” within the GOM (Wursig 

et al., 2000; Waring et al., 2009). The Bryde’s whale is the only resident baleen whale and is found 

primarily in the eastern GOM (Waring et al. 2009). 

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 these marine 

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 range of hearing between 5 and 20 kHz. Since there is some overlap in the sound levels 

produced and the hearing thresholds of these marine mammals, there is potential for the drilling noise 

produced to cause auditory and nonauditory effects (i.e., behavioral disruptions), permanent threshold 

shift, temporary threshold shift, behavioral changes, or masking; but, it is expected to be limited because 

these levels are under the NMFS 160-dB level B harassment criteria under the MMPA. 

The NMFS sets the 180-dB root-mean-squared (rms) isopleth where the on-set of auditory injury or 

mortality (level A harassment) to cetaceans may occur. Southall et al. (2007) suggest a level of 230 dB 

peak flat for a nonpulsed, discrete single event 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 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. 

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 
Description of the Environment and Impact Analysis 4-227 

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 

The BOEM has reexamined the analysis for marine mammals presented in the Multisale EIS, the 

2009-2012 Supplemental EIS, and the cited new information within the discussions above. Based on this 

evaluation, our analysis of the effects from routine activities on marine mammals remains unchanged 

from what was concluded in the Multisale EIS and the 2009-2012 Supplemental EIS. Effects from 

routine activities from 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, if they were to occur, could result from chance collisions with OCS service vessels or the 

ingestion of any accidentally released plastic materials. However, there have been no reports of mortality 

from these occurrences in the GOM, and vessel strikes are considered unlikely (also see USDOC, NMFS, 

2007b). Instead, most routine OCS activities are expected to have sublethal effects, such as behavioral 

effects, that are not expected to rise to the level of significance to the populations. 

Although there will always be some level of incomplete information relevant to the effects from 

routine activities under this proposed action on marine mammals, BOEM does not believe it is essential to 

a reasoned choice among alternatives. There is credible scientific information available, and applied 

using acceptable scientific methodologies, to support the conclusion that any realized impacts would be 

sublethal in nature and not in themselves be expected to rise to the level of reasonably foreseeable 

significant adverse (population level) effects. As noted above in the affected environment section, 

however, BOEM cannot rule out that incomplete or unavailable information on effects of the UME or the 

DWH event on certain species may be essential to a reasoned choice among alternatives (and that this 

information cannot be obtained within the timeframe of this Supplemental EIS). As such, BOEM 

acknowledges that impacts from routine activities could be greater on individuals or populations already 

impacted by the DWH event or UME. Nevertheless, routine activities are ongoing in the proposed action 

area (CPA) as a result of existing leases and related activities (there are 4,503 active leases in the CPA as 

of November 2011). Within the CPA, there is a long-standing and well-developed OCS Program (more 

than 50 years); there are no previous data to suggest that routine activities from the preexisting OCS 

Program were significantly impacting marine mammal populations. 

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. This section treats both the expected accidental spill as well as the lowprobability, large-volume spill with catastrophic events. Further, general analyses of a catastrophic event 

in the GOM can also be found in Appendix B. 

Proposed Action Analysis 

For water depths >200 m (656 ft), 84-102 blowouts are estimated for the CPA proposed action over 

the 2007-2046 period (Table 4-6 of the Multisale EIS). The risk of various sizes of oil spills occurring in 

the CPA is presented in Table 3-5. 

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 
4-228 Central Planning Area Supplemental EIS 

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). Since there are reports of oiled marine mammals 

(see the DWH assessment in the Chapter 4.1.1.10.4, “Cumulative Impacts,” to follow), exposure to 

hydrocarbons persisting in the sea following the dispersal of a large oil slick may result in sublethal 

impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) 

to marine mammals. The potential effects associated with a low-probability large spill may be more 

severe than a smaller accidental spill and could potentially contribute to longer-lasting and potentially 

population-level effects. Appendix B discusses, in general, the magnitude and duration of effects 

possible if the low-probability, large-volume spill were to occur in the GOM. 

The oil from an oil spill can adversely affect cetaceans by causing soft tissue irritation, fouling of 

baleen plates (although Bryde’s whales are the only baleen whale species regularly found in the GOM and 

Waring et al. [2009] estimate there to be 15 individuals in that stock), 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. 

Impacts from dispersants are unknown but may be irritants to tissues and sensitive membranes (NRC, 

2005). One assumption concerning the use of dispersants is that the chemical dispersion of oil will 

considerably reduce the impacts to marine mammals, primarily by reducing their exposure to petroleum 

hydrocarbons (French-McCay, 2004; NRC, 2005). However, the impacts to marine mammals from 

chemical dispersants could include nonlethal injury (e.g., tissue irritation, inhalation), long-term exposure 

through bioaccumulation, and potential shifts in distribution from some habitats. 

Information on the effects of spilled oil on marine mammals was gathered as a result of the 1989 

Exxon Valdez tanker oil spill in Prince William Sound, Alaska. Of the marine mammal species affected 

by this spill, the killer whale is the only species to also occur in the GOM. The 2010 Injured Resources & 

Services Update (Matkin, et al., 2008) provided by the Exxon Valdez Oil Spill Trust Council determined, 

although still circumstantial, that declines immediately following the spill in killer whale numbers 

(primarily the AB and AT1 populations) were likely a result of the inhalation of petroleum or petroleum 

vapors and possible eating of contaminated fish or oiled harbor seals. Twenty years later, the Exxon 

Valdez Oil Spill Trust Council determined these populations to still be recovering (Exxon Valdez Oil Spill 

Trust Council, 2010; Matkin et al., 2008). 

There have been no experimental studies and only a handful of observations suggesting that oil has 

harmed any manatees (St. Aubin and Lounsbury, 1990). The 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 an endangered 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. Also, since 

this species is known to be easily struck by passing boats, manatees may be at risk for injury if cleanup 

activities were happening in their habitat. 

Manatees primarily inhabit open coastal (shallow nearshore) areas and estuaries, and they are also 

found far up in freshwater tributaries. During warmer months (June to September), 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 west (although individuals have been 

sighted as far as Texas). 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. However, 

as stated previously, manatees are very unlikely to occur in the proposed action area. 
Description of the Environment and Impact Analysis 4-229 

As noted previously, BOEM has consulted with NMFS and FWS regarding the effects to ESA-listed 

marine mammal species from spilled oil (USDOC, NMFS, 2007b; USDOI, FWS, 2007). These previous 

consultations concluded that the proposed lease sale and associated activities (1) were not likely to affect 

ESA-listed species or habitat in the GOM under FWS jurisdiction (namely manatees and nesting sea 

turtles) and (2) were not likely to jeopardize the continued existence of ESA-listed species under NMFS 

jurisdiction or destroy or adversely modify designated critical habitat (mainly Gulf sturgeon, cetaceans 

and sea turtles in the water). The NMFS Biological Opinion did find that spilled oil resulting from this 

CPA proposed action could cause up to 11 nonlethal takes of sperm whales over the 40-year lifetime of 

the proposed action. However, NMFS did not include an incidental take statement for sperm whales 

given an oil spill is an “otherwise unlawful activity.” 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. (As discussed previously, BOEM has requested reinitiation of ESA consultation with both NMFS 

and FWS. Pending completion of this reinitiated consultation, BOEM and BSEE are working with both 

agencies to develop an interim coordination policy and the current consultation remains in effect.) 

Summary and Conclusion 

The analysis of the effects from accidental spills (noncatastrophic) on marine mammals remains 

unchanged from what was concluded in the Multisale EIS and the 2009-2012 Supplemental EIS. Impacts 

on marine mammals from smaller accidental events are likely to affect individual marine mammals in the 

spill area, as described above and within the Multisale EIS and the 2009-2012 Supplemental EIS, but are 

unlikely to rise to the level of population effects (or significance) given the likely size and scope of such 

spills. Further, the potential remains for smaller accidental spills to occur in the proposed action area, 

regardless of any alternative selected under this Supplemental EIS, given that, as of November 2011, 

there are 4,503 active leases in the CPA with either ongoing or the potential for exploration, drilling, and 

production activities. 

For low-probability catastrophic spills, the Multisale EIS, 2009-2012 Supplemental EIS, and 

Appendix B of this Supplemental EIS conclude that there is a potential for a low-probability catastrophic 

event to result in significant, population-level effects on affected marine mammal species. The BOEM 

continues to concur with the conclusions from these analyses. 

The BOEM concludes that there is incomplete or unavailable information that may be relevant to 

reasonably foreseeable significant adverse impacts to marine mammals from noncatastrophic 

spills/accidental events. For example, there is incomplete information on impacts to marine mammal 

populations from the DWH event, and whether individuals or populations may be susceptible to greater 

impacts in light of the UME or the DWH event. Relevant data on the status of and impacts to marine 

mammal populations from the UME and the DWH event may take years to acquire and analyze, and 

impacts from the DWH event may be difficult or impossible to discern from other factors. For example, 

20 years after the Exxon Valdez event, investigations are still identifying data regarding impacts to killer 

whales. The NMFS has jurisdiction for the investigation of marine mammal strandings and, to date, has 

only released raw data on the number of strandings. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in this Supplemental EIS, regardless of the cost or resources 

needed. In the absence of this information, BOEM subject-matter experts have used what scientifically 

credible information is available and applied it using accepted scientific methodologies. The BOEM 

cannot rule out that unavailable or incomplete information on accidental impacts may be essential to a 

reasoned choice among the alternatives in light of the UME and the DWH event. Activities that could 

result in an accidental spill in the CPA would be ongoing whether or not the lease sale under the proposed 

action occurred. As of November 2011, there are 4,503 active leases in the CPA that are engaged, or 

have the potential to be engaged, in drilling and/or production activities that could result in an accidental 

spill. 
4-230 Central Planning Area Supplemental EIS 

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. 

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 energy-related activities include marine debris, contaminant spills and spillresponse activities, vessel traffic, noise, seismic surveys, and explosive structure removals. Non-OCS 

energy-related activities that may affect marine mammal populations include vessel traffic and related 

noise (including from commercial shipping, research vessels), military operations, commercial fishing, 

and pollution. A detailed cumulative impact analysis of marine mammals for proposed CPA Lease Sale 

216/222 can be found in Chapter 4.5.5 of the Multisale EIS and Chapter 4.1.6.4 of the 2009-2012 

Supplemental EIS. There is no new information regarding effects of non-OCS energy-related activities 

since the prior NEPA analyses that would alter the conclusions contained in the Multisale EIS and the 

2009-2012 Supplemental EIS. Activities considered under the cumulative scenario could affect protected 

cetaceans and sirenians (manatees). 

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). 

Disturbance (noise from vessel traffic and drilling operations) 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). As discussed in Appendix B, a lowprobability, large-scale catastrophic event could have population-level effects on marine mammals. 

The effects of the proposed action, when viewed in light of the effects associated with other past, 

present, and reasonably foreseeable future activities may result in greater impacts to marine mammals 

than before the DWH event; however, the magnitude of those effects cannot yet be determined. 

Nonetheless, operators are required to follow all applicable lease stipulations and regulations, as clarified 

by NTL’s, to minimize these potential interactions and impacts. The operator’s reaffirmed compliance 

with NTL 2007-G04 (“Vessel-Strike Avoidance”) and NTL 2007-G03 (“Marine Trash and Debris”), as 

well as the limited scope, timing, and geographic location of the proposed action, would result in 

negligible effects from the proposed drilling activities on marine mammals. In addition, NTL 2007-G02, 

“Implementation of Seismic Survey Mitigation Measures and Protected Species Observer Program,” 

minimizes the potential of harm from seismic operations to marine mammals. These mitigations include 

onboard observers, airgun shut-downs for whales in the exclusion zone, ramp-up procedures, and the use 

of a minimum sound source. 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 ongoing activities in the area. 

Summary and Conclusion 

The BOEM has considered this assessment and reexamined the cumulative analysis for marine 

mammals presented in the Multisale EIS, the 2009-2012 Supplemental EIS, and the cited new 

information. Based on this evaluation, conclusions in these analyses on effects to marine mammals 

remain unchanged in regards to Routine Activities (no potential for significant adverse effects) and 

Accidental Spills (potential for significant adverse effects). 
Description of the Environment and Impact Analysis 4-231 

Unavailable information on the effects to marine mammals from the DWH and UME events (and thus 

changes to the marine mammal baseline in the Affected Environment) makes an understanding of the 

cumulative effects less clear. Here, BOEM concludes that the unavailable information from these events 

may be relevant to foreseeable significant adverse impacts to marine mammals. For marine mammals 

occurring in the CPA, BOEM cannot rule out that incomplete or unavailable information may be essential 

to a reasoned choice among the alternatives for this Supplemental EIS (including the No Action and 

action alternatives). Relevant data on the status of marine mammal populations after the UME and the 

DWH event may take years to acquire and analyze, and impacts from the DWH event may be difficult or 

impossible to discern from other factors. Further, there are already scientific processes in place through 

the NRDA and UME responses to investigate these remaining questions. The NMFS has jurisdiction for 

the investigation of marine mammal strandings and has only released raw data on stranding numbers to 

date. Therefore, it is not possible for BOEM to obtain this information within the timeline contemplated 

in this Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or 

unavailable information, BOEM subject-matter experts have used available scientifically credible 

evidence in this analysis and applied it using accepted scientific methods and approaches. 

Nevertheless, as of November 2011, there are 4,503 active leases in the CPA with ongoing (or the 

potential for) exploration, drilling, and production activities. In addition, non-OCS energy-related 

activities will continue to occur in the CPA irrespective of this proposed lease sale (i.e., fishing, military 

activities, and scientific research). The potential for effects from changes to the affected environment 

(post-DWH), routine activities, accidental apills (including low-probability catastrophic spills), and 

cumulative effects remains whether or not the No Action or an action alternative is chosen under this 

Supplemental EIS. 

Overall, within the CPA, there is a long-standing and well-developed OCS Program (more than 

50 years); there are no data to suggest that activities from the preexisting OCS Program are significantly 

impacting marine mammal populations. Therefore, in light of the above analysis on the proposed action 

and its impacts, the incremental effect of the proposed action on marine mammal populations is not 

expected to be significant when compared with all other past, present, and reasonably foreseeable future 

activities. 

4.1.1.12. Sea Turtles 

The BOEM has reexamined the analysis for the five sea turtles species that inhabit the Gulf of 

Mexico (GOM) in the Multisale EIS and the 2009-2012 Supplemental EIS based on the additional 

information presented below and in consideration of the DWH event. 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 

and 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. 

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. Any new 

information since the publication of the Multisale EIS is also 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 and 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 

Ocean, GOM, and the Caribbean Sea. Although migratory, these migration patterns are not well defined. 

All five species of sea turtles found in the GOM have been federally listed as endangered or threatened 

since the 1970’s. There is currently no critical habitat designated in the GOM or along the Gulf Coast. 
4-232 Central Planning Area Supplemental EIS 

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 GOM and 

Atlantic Ocean. The NMFS is currently reviewing the petition. 

In August 2007, FWS and NMFS published 5-year status reviews for federally listed sea turtles in the 

GOM (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 with frequency 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 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 GOM 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 (GMFMC), 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). 

Leatherback Sea Turtle 

The leatherback is the most abundant sea turtle in waters over the northern GOM 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 GOM (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 GOM during both summer and winter (Mullin 

and Hoggard, 2000). 

On the Atlantic side of 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, 2010b). Although nesting is very rare on GOM beaches, leatherbacks occur in GOM 
Description of the Environment and Impact Analysis 4-233 

waters. Satellite telemetry and tag returns have shown that some of the leatherbacks present in the GOM 

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 GOM 

and are known to nest on GOM beaches, but in very small numbers (USDOC, NMFS and USDOI, FWS, 

2007b). 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, 

2010b). 

After emerging from the nest, hatchlings swim to offshore areas, where they are believed to live for 

several years, feeding close to the surface on a variety of pelagic plants and animals. Once the juveniles 

reach a certain age/size range, they leave the pelagic habitat and travel to nearshore foraging grounds. 

Once they move to these nearshore benthic habitats, adult green turtles are almost exclusively herbivores, 

feeding on seagrasses and algae. Adult females migrate from foraging areas to mainland or island nesting 

beaches and may travel hundreds or thousands of kilometers each way (USDOC, NMFS and USDOI, 

FWS, 2007b). 

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. 

Hawksbill sea turtles are highly migratory and use a wide range of habitats during their lifetime. As 

with most sea turtle species, hatchlings and early juveniles are often found in association with oceanic 

sargassum floats. As later juveniles, they move nearshore for feeding habitat and may associate with the 

same feeding locality for more than a decade (Musick and Limpus, 1997). In the continental U.S., 

hawksbills are found primarily in Florida and Texas, though they have been recorded in all the GOM 

States and along the east coast as far north as Massachusetts. 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). 
4-234 Central Planning Area Supplemental EIS 

Kemp’s Ridley Sea Turtle 

The nearshore waters of the GOM are believed to provide important developmental habitat for 

juvenile Kemp’s ridley and loggerhead sea turtles. 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 GOM. 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; 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 GOM and Atlantic Ocean. The NMFS is currently 

reviewing the petition. 

The species occurs mainly in coastal areas of the GOM 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, 2011d). 

Loggerhead Sea Turtle 

Loggerhead sea turtles are considered a threatened species. In the GOM loggerheads nest primarily 

in southwest Florida with minimal nesting outside of this range westward to Texas. 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. Hatchlings 

emerge from the nest and swim away from land for several days. Offshore, they reside for months in the 

oceanic zone in Sargassum floats, generally along the Loop Current and the Gulf Coast of Florida. 

Somewhere between 7 and 12 years old, oceanic juveniles migrate to nearshore coastal areas to mature 

into adults. These nearshore waters become important foraging and migratory habitat for juveniles and 

adults. Juveniles may also spend time in bays, sounds, and estuaries. Adult loggerheads are known to 

make extensive migrations between foraging areas and nesting beaches. During non-nesting years, adult 

females from U.S. beaches are distributed in waters off the eastern U.S. and throughout the GOM, 

Bahamas, Greater Antilles, and Yucatán (Conant et al., 2009). 

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, 2011d). 

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, 2010c). 

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. 

The NMFS has issued a proposed rule to list nine distinct population segments of loggerhead sea 

turtles under the ESA (76 FR 15932). The comment period is set to close on September 16, 2011, but 

none of the distinct population segments are located in the GOM. 

Recent Section 7 Endangered Species Act Consultation 

As mandated by the Endangered Species Act, BOEM consulted with NMFS and FWS on possible 

and potential impacts from the CPA proposed action on endangered/threatened species and designated 
Description of the Environment and Impact Analysis 4-235 

critical habitat under their jurisdiction (USDOC, NMFS, 2007b). 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 consultation with the FWS concluded that activities occurring as a result of the proposed action 

may affect nesting and hatchlings of the threatened loggerhead and endangered Kemp’s ridley; however, 

no direct loss of habitat is anticipated. The anticipated effects from the major impact-producing factors 

are sublethal, causing discountable insignificant effects. The consultation went on to identify an oil spill 

reaching sea turtle nesting habitat during the nesting season as the greatest threat to sea turtles. However, 

FWS concurred, based on the probabilities identified by BOEM of a spill reaching nesting habitat at the 

time (0.5% to 9%) that the potential for contact was greatly reduced. Overall, FWS concurred that the 

proposed action would not adversely affect nesting and hatchling loggerhead or Kemp’s ridley turtles 

(USDOI, FWS, 2007). 

The formal ESA consultation with NMFS (the agency with oversight on sea turtles in the water) 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 GOM under 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. 

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 FWS responded with a letter to BOEMRE on September 27, 2010. The reinitiated consultations are 

not complete at this time, although BOEM, as lead agency, and BSEE are in discussions with both 

agencies. In the meantime, the current consultation remains in effect and recognizes that BOEM- and 

BSEE-required mitigations and other reasonable and prudent measures should reduce the likelihood of 

impacts from BOEM- and BSEE-authorized activities. Further, BOEM has determined, under Section 

7(d) of the ESA, that the proposed action is not an irreversible or irretrievable commitment of resources 

that has the effect of foreclosing the formulation or implementation of any reasonable and prudent 

alternative measures. The BOEM and BSEE are also developing an interim coordination program with 

NMFS and FWS while consultation is ongoing. 

Deepwater Horizon Event 

The DWH event and resulting oil spill in Mississippi Canyon Block 252, and related spill-response 

activities (including use of dispersants), have impacted sea turtles that have come into contact with oil and 

remediation efforts. 

According to NMFS, 1,146 sea turtles have been collected (537 alive, 609 deceased) as of 

February 15, 2011 (USDOC, NMFS, 2011c). Of these, 201 were greens, 16 Hawksbills, 809 Kemp’s 

ridleys, 88 loggerheads, and the remaining 32 unknown (USDOC, NMFS, 2011c). Individuals were 

documented either through strandings or directed offshore captures. Due to low detection rates of 

carcasses in prior events, it is possible that the number of deaths of sea turtles is underestimated (Epperly 

et al., 1996). It is also important to note that evaluations have not yet confirmed the cause of death, and it 

is possible that not all carcasses were related to the DWH event oil spill. 

As a preventative measure during the DWH response, NMFS and FWS translocated a number of sea 

turtle nests and eggs that were located on beaches affected or potentially affected by spilled oil. 

According to the latest information, a total of 274 nests were translocated from GOM beaches to the east 

coast of Florida. These nests were mainly for hatchlings that would enter waters off Alabama and 

Florida’s northwest Gulf Coast. Of these, 4 were from green turtles, 5 from Kemp’s ridley and 265 from 

loggerheads, as indicated in the table below. The translocation effort ended August 19, 2010, at the time 

when biologists determined that risks to hatchlings emerging from beaches and entering waters off 

Alabama and Florida’s northwest Gulf Coast had diminished significantly and that the risks of 

translocating nests during late incubation to the east coast of Florida outweighed the risks of letting 

hatchlings emerge into the GOM. The hatchlings resulting from the translocations were all released as of 

September 9, 2010. 
4-236 Central Planning Area Supplemental EIS 

Final Data on Nesting Translocation, updated on August 25, 2011 

(USDOC, NMFS, 2011c) 

Species Translocated Nests Hatchlings Released 

Green turtle 

(Chelonia mydas) 

4 455 

Kemp’s ridley turtle 

(Lepidochelys kempii) 

5 125 

Loggerhead turtle 

(Caretta caretta) 

265* 14,216 

*Does not include one nest that included a single hatchling and no eggs. 

Note: All data is preliminary. 

As of August 3, 2010, in open water, there was no evidence that sea turtles were still being exposed to 

chemicals from the DWH event (OSAT, 2010). This report states, “Since 3 August [2010], no 

exceedances of the aquatic life benchmark for PAHs in water that were consistent with MC 252 oil.” It is 

likely that there were effects on individual sea turtles in the vicinity of the DWH event spill caused by 

spilled oil and/or response activities. Depending upon the species’ sensitivity and/or low resiliency, 

individual sea turtles may be experiencing residual effects provided sufficient exposure. Further, it is 

uncertain whether or how many sea turtle individuals affected by the spill would be present in the CPA 

when activities first occur as a result of this proposed lease sale. Without any further data than what exist 

from NMFS and FWS (which have jurisdiction over sea turtles in water and on land, respectively), it is 

impossible to determine if the spill has led to population-level effects or if sea turtles are experiencing 

chronic effects or persistent adverse impacts from the spill at the population level. Information is still 

being gathered to develop a more complete picture of impacts and the length of time for any changed 

baseline conditions to return to pre-spill conditions (see “Sea Turtle Resources in the Central Planning 

Area” below). It is also important to note that evaluations have not yet confirmed the cause of death, 

including whether or not related to the DWH event oil spill. 

Sea Turtle Strandings in the GOM 

Since March 15, 2011, a notable increase in sea turtle strandings has occurred in the northern GOM, 

primarily in Mississippi. While turtle strandings in this region typically increase in the spring, the recent 

increase is a cause for concern. The Sea Turtle Stranding and Salvage Network (STSSN) is monitoring 

and investigating this increase. The network encompasses the coastal areas of the 18 states from Maine 

through Texas and includes portions of the U.S. Caribbean. There are many possible reasons for the 

increase in strandings in the northern GOM, both natural and human caused (USDOC, NMFS, 2011c). 

No visible external or internal oil was observed in these animals. These sea turtle species include 

loggerhead, green, Kemp’s ridley and unidentified. As of September 16, 2011, NMFS has identified 

84 strandings in Alabama, 108 strandings in Louisiana, and 272 strandings in Mississippi. The increased 

stranding event in Alabama represents approximately 18 percent of the total strandings to date. The lease 

sale under the proposed action also cover these same areas. 

Sea Turtle Resources in the Central Planning Area 

The final determinations on damages to sea turtle resources from the DWH event will ultimately be 

made through the NRDA process. For sea turtles, investigations as part of the NRDA process are under 

the jurisdiction of NMFS and FWS. The DWH event will allow a better understanding of any realized 

effects from such a low-probability catastrophic spill. However, the best available information on 

impacts to sea turtles does not yet provide a complete understanding of the effects of the oil spilled and of 

the active response/cleanup activities from the DWH event on sea turtles in the GOM and whether these 

impacts reach a population level. There is also an incomplete understanding of the potential for 

population-level impacts from the ongoing increased stranding event. 

The BOEM concludes that the unavailable or incomplete information resulting from the DWH event 

and increased stranding events could be relevant to reasonable foreseeable significant adverse effects. 

The OCS activities will be ongoing under existing leases (4,503 active leases in CPA as of November 
Description of the Environment and Impact Analysis 4-237 

2011) whether or not the proposed action or any other alternative are selected. However, BOEM believes 

that the unavailable information may be essential to a reasoned choice among alternatives, particularly 

regarding sea turtles affected by the increased stranding event and/or the DWH event. The NMFS and 

FWS have jurisdiction for investigating sea turtle impacts, including both the current increased stranding 

event and the DWH event. To date, NMFS has released only raw data on strandings. We are therefore 

unable to determine, at this point and time, what effect (if any) the DWH event had on sea turtles also 

affected by the increased stranding event. Due to NMFS’s and FWS’s role in the investigation, BOEM 

does not have the ability to obtain its own data on stranded animals. The NRDA process and the 

increased stranding investigation may take years to complete. Impacts from the DWH event may be 

difficult or impossible to discern from other factors. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in this Supplemental EIS, regardless of the cost or resources 

needed. In light of the incomplete or unavailable information, BOEM subject-matter experts have used 

available scientifically credible evidence in this analysis and based it upon accepted scientific methods 

and approaches.

Further, the analyses in the Multisale EIS, the 2009-2012 Supplemental EIS, and this Supplemental 

EIS (Chapter 4.1.1.12.1 [affected environment], Chapter 4.1.1.12.2 [accidental spills], and 

Appendix B) conclude that there is a potential for low-probability catastrophic events to result in 

significant, population-level effects on affected sea turtle species. The BOEM continues to agree with 

these conclusions irrespective of any incomplete information, changes to the existing environment from 

the DWH event, or even the effectiveness of implementation of the improved post-DWH event safety and 

oil-spill-response requirements. 

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 and 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 and 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, 

although this potential is unlikely to rise to a level of significance due to the activity already present in the 

GOM and mitigations that are in place and discussed below. 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, 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 rapid dilution of the discharges which are regulated by NPDES permits, and due to the wide-ranging 

habits of sea turtle species in the GOM. 

Another 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 activities resulting 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 
4-238 Central Planning Area Supplemental EIS 

sea turtles are not thought to rely on acoustics. 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 their 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, 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 GOM 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, this Agency issued NTL 2007-G04, which clarifies 30 CFR 250.282 (and now the companion 

regulation at 30 CFR 550.282) 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’ 2007 Biological Opinion 

concluded that the risk of collisions between oil/gas-related vessels (including those for G&G, drilling, 

production, decommissioning, and transport) and sea turtles is appreciably reduced, but strikes may still 

occur. The BOEM and BSEE monitor 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, 

30 CFR 250.582, 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. 

Seismic operations have the potential to harm sea turtles in close proximity to firing airgun arrays, 

especially if they are directly beneath airguns when surveying begins. The Protected Species Stipulation 

and NTL 2007-G02, “Implementation of Seismic Survey Mitigation Measures and Protected Species 

Observer Program,” minimize the potential of harm from seismic operations to sea turtles. These 

mitigations include onboard observers, airgun shut-downs for whales in the exclusion zone, ramp-up 

procedures, and the use of a minimum sound source. 

This Agency 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 

energy related resources, particularly upon marine mammals and sea turtles. Pursuant to 30 CFR 250 

Subpart Q, operators must obtain a permit from BSEE before beginning any platform removal or wellseverance 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 the possible impacts from any potential activities resulting from the 

proposed lease sale. 

In 30 CFR 550 Subpart B, BOEM 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 energy-related activities to be conducted in a manner that is consistent with the provisions 
Description of the Environment and Impact Analysis 4-239 

of the ESA. Actual sea turtle impacts from explosive removals in recent years have been small. The 

updated pre- and post-detonation 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 attributable to OCS 

energy-related activities and is 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 BOEM 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. 

Summary and Conclusion 

In this Supplemental EIS, BOEM 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. Because of the mitigations (e.g., BOEM proposed compliance with NTL’s) 

described in the above analysis, routine activities (e.g., operational discharges, noise, vessel traffic, and 

marine debris) related to the CPA proposed action 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 

could occur from chance collisions with OCS service vessels or ingestion of accidentally released plastic 

materials from OCS vessels and facilities. However, there have been no reports to date on such 

incidences. Most routine OCS energy-related activities are then expected to have sublethal effects that 

are not expected to rise to the level of significance. 

Although there will always be some level of incomplete information relevant to the effects from 

routine activities under the proposed action on sea turtles, BOEM does not believe it is essential to a 

reasoned choice among alternatives. There is credible scientific information available, applied using 

acceptable scientific methodologies, to support the conclusion that any realized impacts would be 

sublethal in nature and not in themselves be expected to rise to the level of reasonably foreseeable 

significant adverse (population-level) effects. As noted above in the affected environment section, 

however, BOEM cannot rule out that incomplete or unavailable information on effects of the increased 

stranding event or the DWH event on sea turtles may be essential to a reasoned choice among alternatives 

(and that this information cannot be obtained within the timeframe of this Supplemental EIS). As such, 

BOEM acknowledges that impacts from routine activities could be greater on individuals or populations 

already impacted by the DWH event or the increased stranding event. Nevertheless, routine activities are 

ongoing in the proposed action area (CPA) as a result of existing leases and related activities (there are 

4,503 active leases in the CPA as of November 2011). Within the CPA, there is a long-standing and welldeveloped OCS Program (more than 50 years); there are no previous data to suggest that routine activities 

from the preexisting OCS Program were significantly impacting sea turtles. 

4.1.1.12.3. Impacts of Accidental Events 

A detailed impact analysis of sea turtles for proposed CPA Lease Sale 216/222 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. This section treats both the expected accidental spill as well as the low-probability, largevolume spill with catastrophic events. Further, general analyses of a catastrophic event in the GOM can 

also be found in Appendix B. 

Proposed Action Analysis 

Accidental activities resulting from the 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 
4-240 Central Planning Area Supplemental EIS 

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 and 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. Sea turtle eggs are likely to be lethally impacted by contact with spilled oil 

(USDOI, NPS, 2010). The potential effects associated with a low-probability large spill may be more 

severe than a smaller accidental spill and could potentially contribute to longer-lasting and larger-scale 

effects. Appendix B discuses, in general, the magnitude and duration of effects possible if the lowprobability, large-volume spill was to occur in the GOM. 

The 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) of oil and transport of this oil into the 

GOM (ERCO, 1982). Three million gallons of oil impacted Texas beaches (ERCO, 1982). According to 

the ERCO study, “Whether or not hypoxic conditions could, in fact, be responsible for area-wide 

reductions in [invertebrate] faunal abundance is unclear, however.” 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). Therefore, the effects of the Ixtoc spill 

on sea turtles in waters off Texas are still unknown. 

For water depths >200 m (656 ft), 84-102 blowouts are estimated for the CPA proposed action over 

the 2007-2046 period (Table 4-6 of the Multisale EIS). The risk of various sizes of oil spills occurring in 

the CPA is presented in Table 3-5. 

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, the degree of sensitivity to oil hydrocarbons, and the effects of cleanup activities on sea turtles 

are unknown. Impacts from the dispersants may have similar impacts as oil, such as being an irritant to 

tissues and sensitive membranes as they are known to be in seabirds and marine mammals (NRC, 2005). 

Sea turtles are vulnerable to oil and dispersants at all life stages (i.e., eggs, post-hatchlings, juveniles, subadults, and adults), and there is no demonstrated avoidance behavior (Shigenaka et al., 2010). The 

impacts to sea turtles from chemical dispersants could include nonlethal injury (e.g., tissue irritation, 

chemical burns, and inhalation), long-term exposure through bioaccumulation, infection, and potential 

shifts in distribution from some habitats (USDOC, NOAA, 2010h; Shigenaka et al., 2010). 

During the oil-spill response related to the DWH event, NMFS and FWS undertook an unprecedented 

attempt to relocate a number of sea turtle nests and eggs that were located on beaches affected, or that 

were believed to be at risk of, spilled oil (see the discussion in Chapter 4.1.1.11.1). This experimental 

approach had not been attempted on a large scale for any prior spill. The fate of these relocated 

hatchlings may never be known, since none of the individuals were tagged and tracked. There are 

concerns over the potential success of this program, given that these species tend to return to their natal 

beaches as adults to nest. In addition, sea turtle species require at least a decade before they reach sexual 

maturity. Even in 10 years, data on nestings would likely be inconclusive as it would be impossible to tell 

which returning females, if any, are from this relocation experiment. 

In the 2007 Biological Opinion 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 the proposed action (USDOC, NMFS, 2007b). However, 

NMFS did not include incidental take of listed species due to oil exposure in this Incidental Take 

Statement, as it is an otherwise unlawful activity. 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; USDOI, FWS, 2007) considered the effects on 

listed species by oil spills that may result from the proposed actuion, those takings that would result from 
Description of the Environment and Impact Analysis 4-241 

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. As discussed previously, BOEM has requested 

reinitiation of ESA consultation with both NMFS and FWS. Pending completion of this reinitiated 

consultation, BOEM, as lead agency, and BSEE are working with both agencies to develop an interim 

coordination policy and the current consultation remains in effect. 

Summary and Conclusion 

The analysis of the effects from accidental spills (noncatastrophic) on sea turtles remains unchanged 

from what was concluded in the Multisale EIS and the 2009-2012 Supplemental EIS. Impacts on sea 

turtles from smaller accidental events are likely to affect individual sea turtles in the spill area, as 

described above and within the Multisale EIS and the 2009-2012 Supplemental EIS, but they are unlikely 

to rise to the level of population effects (or significance) given the size and scope of such spills. Further, 

the potential remains for smaller accidental spills to occur in the proposed action area, regardless of any 

alternative selected under this Supplemental EIS, given that, as of November 2011, there are 4,503 active 

leases in the CPA with either ongoing or the potential for exploration, drilling, and production activities. 

For low-probability catastrophic spills, the Multisale EIS, the 2009-2012 Supplemental EIS, and 

Appendix B of this Supplemental EIS conclude that there is a potential for a low-probability catastrophic 

event to result in significant, population-level effects on affected sea turtle species. The BOEM continues 

to concur with the conclusions from these analyses. 

The BOEM concludes that there is incomplete or unavailable information that may be relevant to 

reasonably foreseeable significant adverse impacts to sea turtles from noncatastrophic spills/accidental 

events. For example, there is incomplete information on impacts to sea turtle populations from the DWH 

event and whether individuals or populations may be susceptible to greater impacts in light of the 

increased stranding event or the DWH event. Relevant data on the status of and impacts to sea turtle 

populations from the increased stranding event and the DWH event may take years to acquire and 

analyze, and impacts from the DWH event may be difficult or impossible to discern from other factors. 

The NMFS to date has only released raw data on the number of strandings, and BOEM does not have the 

ability to investigate these strandings independently. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in this Supplemental EIS, regardless of the cost or resources 

needed. In the absence of this information, BOEM subject-matter experts have used what scientifically 

credible information that is available and applied it using accepted scientific methodologies. The BOEM 

cannot rule out that unavailable or incomplete information on accidental impacts may be essential to a 

reasoned choice among the alternatives, in light of the increased stranding event and thte DWH event. 

Activities that could result in an accidental spill in the CPA would be ongoing whether or not the lease 

sale under the proposed action occurred. As of November 2011, there are 4,503 active leases in the CPA 

that are engaged, or have the potential to be engaged, in drilling and/or production activities that could 

result in an accidental spill. 

4.1.1.12.4. Cumulative Impacts 

A detailed impact analysis of sea turtles for the 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. 

Proposed Action Analysis 

The major impact-producing factors resulting from cumulative OCS energy-related activities 

associated with the CPA proposed action that may affect loggerhead, Kemp’s ridley, hawksbill, green, 

and leatherback turtles and their habitats include marine debris, contaminant spills and spill-response 

activities, vessel traffic, noise, seismic surveys, and explosive structure removals. Non-OCS energyrelated activities that may affect sea turtle populations include vessel traffic and related noise (including 

from commercial shipping and research vessels), military operations, commercial fishing, and pollution. 

The cumulative impact of these ongoing OCS energy-related 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 
4-242 Central Planning Area Supplemental EIS 

intake of OCS-related contaminants or discarded debris) because these activities may stress and/or 

weaken individuals of a local group or population and may predispose them to infection from natural or 

anthropogenic sources. There is no new information regarding effects of non-OCS energy-related 

activities since the prior NEPA analyses that would alter the conclusions contained in the Multisale EIS 

and 2009-2012 Supplemental EIS. These non-OCS energy program-related activities include historic 

overexploitation (which led to listing of the species), commercial fishery interactions, habitat loss, 

dredging, pollution, vessel strikes, and pathogens. 

As described in Chapter 4.1.1.11.2, 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) 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. As discussed in Appendix B, a low-probability, large-scale catastrophic 

event could have population-level effects on sea turtles. 

The effects of the proposed action, when viewed in light of the effects associated with other past, 

present, and reasonably foreseeable future activities, may result in greater impacts to sea turtles than 

before the DWH event; however, the magnitude of those effects cannot yet be determined. Nonetheless, 

operators are required to follow all applicable lease stipulations and regulations, as clarified by NTL’s, to 

minimize these potential interactions and impacts. The operator’s reaffirmed compliance with NTL 2007-

G04 (“Vessel-Strike Avoidance”) and NTL 2007-G03 (“Marine Trash and Debris”), as well as the limited 

scope, timing, and geographic location of the proposed action, would result in negligible effects from the 

proposed drilling activities on sea turtles. In addition, NTL 2007-G02, “Implementation of Seismic 

Survey Mitigation Measures and Protected Species Observer Program,” minimizes the potential of harm 

from seismic operations to sea turtles and marine mammals; these mitigations include onboard observers, 

airgun shut-downs for whales in the exclusion zone, ramp-up procedures, and the use of a minimum 

sound source. Therefore, no significant cumulative impacts to sea turtles 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 ongoing activities in the area. 

Adverse effects may result from the incremental contribution of the CPA proposed action combined 

with non-OCS energy-related activities. The biological significance of any mortality or adverse impact 

would depend, in part, on the size and reproductive rates of the affected populations, as well as the 

number, age, and size of animals affected. However, as the analyses above indicate, the potential for 

impacts is mainly focused on the individual, and population-level impacts are not anticipated based on the 

best available information. 

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 it 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 rely on acoustics; 

therefore, vessel noise and related activities would have limited 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. 

Even taking into account additional effects resulting from non-OCS energy-related activities, the potential 

for impacts from the proposed action is mainly focused on the individual. Population-level impacts are 

not anticipated based on the best available information. 
Description of the Environment and Impact Analysis 4-243 

Summary and Conclusion 

The BOEM has considered this assessment and reexamined the cumulative analysis for sea turtles 

presented in the Multisale EIS, in the 2009-2012 Supplemental EIS, and the cited new information. 

Based on this evaluation, conclusions in these analyses on effects to sea turtles remain unchanged in 

regards to Routine Activities (no potential for significant adverse effects) and Accidental Spills (potential 

for significant adverse effects). 

Unavailable information on the effects to sea turtles from the DWH event and the increased stranding 

event (and thus changes to the sea turtle baseline in the affected environment) makes an understanding of 

the cumulative effects less clear. Here, BOEM concludes that the unavailable information from these 

events may be relevant to reasonably foreseeable significant adverse impacts to sea turtles. For sea turtles 

occurring in the CPA, the Bureau of Ocean Energy Management cannot rule out that incomplete or 

unavailable information may be essential to a reasoned choice among the alternatives for this 

Supplemental EIS (including the No Action and action alternatives). Relevant data on the status of the 

sea turtle population after the increased stranding event and the DWH event may take years to acquire and 

analyze, and impacts from the DWH event may be difficult or impossible to discern from other factors. 

Further, there are already scientific processes in place through the NRDA process and increased stranding 

responses to investigate these remaining questions. The NMFS has only released raw data on stranding 

numbers to date. The BOEM does not have the ability to investigate the sea turtle strandings 

independently. Therefore, it is not possible for BOEM to obtain this information within the timeline 

contemplated in this Supplemental EIS, regardless of the cost or resources needed. In light of the 

incomplete or unavailable information, BOEM subject-matter experts have used available scientifically 

credible evidence in this analysis and based it upon accepted scientific methods and approaches. 

Nevertheless, as of November 2011, there are 4,503 active leases in the CPA with ongoing (or the 

potential for) exploration, drilling, and production activities. In addition, non-OCS energy-related 

activities will continue to occur in the CPA irrespective of this proposed lease sale (i.e., fishing, military 

activities, and scientific research). The potential for effects from changes to the affected environment 

(post-DWH), routine activities, accidental spills (including low-probability catastrophic spills), and 

cumulative effects remains whether or not the No Action or an action alternative is chosen under this 

Supplemental EIS. 

In any event, the incremental contribution of the proposed action would not be likely to result in a 

signtificant incremental impact on sea turtles within the CPA; in comparison, non-OCS-related activities, 

such as overexploitation, commercial fishing, and pollution, have historically proved to be a greater threat 

to sea turtles. 

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

The BOEM 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. 
4-244 Central Planning Area Supplemental EIS 

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 

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 
Description of the Environment and Impact Analysis 4-245 

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 

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 
4-246 Central Planning Area Supplemental EIS 

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. 

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, official communication, 

2010). Assessment of the efficacy of shoreline cleanup in supratidal Alabama beach mouse habitat 

showed 60 percent “no oil observed,” 37 percent “light-very light oiling,” and 3 percent “moderate-heavy 

oiling” (OSAT-2, 2011). Much of the supratidal habitat of the Perdido Key beach mouse and 

Choctawhatchee beach mouse showed “no oil observed” (OSAT-2, 2011). Supratidal habitat of the 

St. Andrew beach mouse was not affected by the DWH event (OSAT-2, 2011). A toxicity reference 

value was developed by USEPA for low (2-3 ring) and high (4-7 ring) molecular weight PAH’s. Two 

scenarios for the PAH’s oral uptake by Alabama beach mouse were reported: 10 percent contribution and 

a worst-case 100 percent contribution of small surface residue balls to the overall ingestion of soil. 

Estimated daily dose from oral uptake following the DWH event did not exceed the toxicity reference 

value for low molecular weight PAH’s in the Alabama beach mouse (OSAT-2, 2011). No changes have 

been identified 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. A peer-reviewed computer model 

from NOAA (USDOC, NOAA, 2010i) predicted that a probability of shoreline threat from the DWH 

event to northeast Florida, including the Anastasia Island beach mouse (listed as endangered) and the 

southeastern beach mouse (listed as threatened), would be only 1-20 percent (USDOC, NOAA, 2010i). 

Any shoreline impacts would be in the form of scattered tarballs and not a large surface slick of oil. The 

model showed results 120 days after the spill began and assumed a 33,000-bbl/day release of oil for 

90 days (USDOC, NOAA, 2010i). 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 
Description of the Environment and Impact Analysis 4-247 

destroy habitat. A study is pending in part investigating events where bulldozers in Florida allegedly 

breached possible beach mouse dune habitat so cleanup vehicles could reach oiled beaches (Frater, 

official communication, 2010 and 2011) Preliminary data suggest that impact to beach mouse habitat was 

very minor (Frater, official communication, 2011). The impacts to beach mouse habitat during the DWH 

response probably have not caused significant impacts to the population levels of beach mice (Frater, 

official communication, 2011). The habitat that was damaged was primarily young dunes; the damage 

may restrict population expansion and recovery for a few years, but anticipated restoration activities will 

probably offset this impact in the near future (Frater, official communication, 2011). 

There is scientifically credible information regarding the likelihood that beach mice were minimally 

impacted by oil and related tarballs from the DWH event. There is a pending study investigating the 

effects of the DWH event’s cleanup activities on beach mice and their habitat. The ongoing research on 

the potential impacts from the cleanup activities to beach mice is being conducted through the NRDA 

process. The NRDA research projects may be years from completion, and data and conclusions have not 

been released to the public. Regardless of the costs involved, it is not within BOEM’s ability to obtain 

this information from the NRDA process within the timeline of this Supplemental EIS. In its place, 

BOEM has included what scientifically credible information is available and applied it using accepted 

scientific methodologies. Although information resulting from this study may be relevant to reasonably 

foreseeable adverse impacts on beach mice and their habitat, BOEM subject-matter experts have 

determined that it is not essential to a reasoned choice among alternatives. The BOEM has conservatively 

considered the potential for impacts from cleanup activities in the analysis below. 

Following the DWH event, BOEM requested reinitiation of ESA consultation with FWS on July 30, 

2010. The FWS responded with a letter to BOEM on September 27, 2010. The reinitiated consultation is 

not complete at this time, although BOEM, as lead agency, and BSEE are working with FWS to develop 

an interim coordination program in the interim (Chapter 5.7). 

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, official communication, 2010). No impacts of coastal and nearshore OCS support activities on 

beach mice are expected for the following reasons: (1) beach mouse critical habitat is protected from 

pipeline landfalls, terminals, and other onshore OCS-related construction; (2) any coastal discharges into 

water will not affect beach mice, which rely on fresh rather than saline drinking water; (3) boat traffic will 

have no impact on beach mouse habitat, which is above high tide; and (4) helicopter traffic is expected to 

occur only well to the west of beach mouse habitat. 
4-248 Central Planning Area Supplemental EIS 

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 

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. The beaches, dunes with their vegetation, and climate of Prince William 

Sound may be quite a bit different from those in areas with beach mice in the Gulf of Mexico. Even if oil 

had been found above high tide in Prince William Sound, the fate of oil there would not necessarily be 

comparable to fate of oil in beach mouse habitat in the Gulf of Mexico. 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. 
Description of the Environment and Impact Analysis 4-249 

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 BOEM 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. 

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 
4-250 Central Planning Area Supplemental EIS 

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 

spills and cleanup operations. When 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. 

4.1.1.14. Coastal and Marine Birds 

The BOEM 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 Chapters 4.2.1.1.7, 4.2.2.1.8, 4.4.8, and 4.5.8 of 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/threatened and nonendangered/nonthreatened 

coastal and marine birds are expected to be sublethal. In the case of a catastrophic spill, both lethal and 

sublethal impacts would be expected to be substantial, with sublethal impacts likely being more frequent. 

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 CPA 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 
Description of the Environment and Impact Analysis 4-251 

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 in the CPA was found from these information sources and/or the available resources relating to 

the DWH event that would alter the conclusions of the Multisale EIS or the 2009-2012 Supplemental EIS. 

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. 

Most bird species are protected by the Migratory Bird Treaty Act; only birds that are not native or a 

very few that are designated as nonmigratory are not protected by the Treaty. 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). 

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). Many 

seabirds, such as the brown pelican, dive; however, they are traditionally called seabirds, as they are in 

this analysis. 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 seasons of occurrence, feeding behavior, 

and diet in Table 3-6 of the Multisale EIS. 

Diving birds typically live in bays and coastal habitats. They do not generally migrate laterally from 

east to west along the Gulf Coast. They are mostly winter residents that migrate north for the summer to 

breed or they are permanent residents (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. For example, Biggs and Ressler (2001) state that “regions 

of convergence are generally regarded as biological “ocean deserts.” They go on to state that “cyclones 

are generally regarded as biological ‘oases’ whereas the interior of the loop current eddies are biological 

‘deserts’.” Certain oceanic conditions including upwelling, convergences, divergences, specific 
4-252 Central Planning Area Supplemental EIS 

sea-surface temperatures, thermal fronts, salinities, areas of high planktonic productivity, or current 

activity create veritable oases for foraging seabirds. Biggs and Ressler (2001) also state that “the same 

cyclones and fronal zones of both cyclonic and anticyclone eddies shown to support enriched 

zoooplankton and micronekton biomass . . . have been identified as deepwater concentrating mechanisms 

for apex predators.” Seabirds obtain their food through a variety of behaviors including kleptoparasitism, 

scavenging, dipping, plunge diving, and surface feeding. 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, official 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. 

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. Oil slicks from the spill covered substantial amounts 

of offshore pelagic bird habitat in the CPA. The seasonal distribution of offshore seabirds is little studied, 

and seasonal offshore movements are almost unknown. Seabirds oiled far offshore would be unlikely to 

persist long enough to wash ashore and be recorded as impacted by oil. 

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. Shorebird habitat and species in the CPA comprise mostly 

coastal wetlands and beaches. Along the central Gulf Coast (Louisiana, Mississippi, and Alabama), 

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 

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 important 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 long term by the spill and cleanup operations. Some shorebirds 

stopping over on the Gulf Coast in the CPA before trans-Gulf migration south in the fall would likely be 

impacted by oil from the DWH event. Shorebirds stopping over on the Gulf Coast after trans-Gulf 
Description of the Environment and Impact Analysis 4-253 

migration in spring would likely follow a clockwise path mostly over the western Gulf, which is taken by 

the heaviest migration of birds in general (Russell, 2005). In spring, those making landfall on the coast of 

Texas likely would continue inland to minimize migration time for prompt arrival on breeding grounds 

(optimizing reproductive success) and would not be affected by oil from the DWH event (Russell, 2005). 

Any delay in migration would disturb the synchronization of breeding with the cycle of food resource 

availability on the breeding grounds. 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. For example, Harrington 

(1996) notes in a natural history account, “. . . for shorebirds like the red knot that forage for food on 

intertidal flats, few spots can rival Patagonia [in Argentina], where an enormous tidal flux of thirty feet or 

more creates a vast intertidal zone.” Harrington (1996) also states, “. . . sediment . . . is uncovered at low 

tide at Golfo San Jorge, Argentina, providing the red knot’s favorite feeding sites from November to 

February. Because the tidal flux is a dramatic thirty feet or more, whales will be swimming over this area 

at high tide.” Further, Skagen and Knopf (1993) state, “Whereas populations of shorebirds in coastal 

systems appear to concentrate at sites of seasonally predictable and abundant food sources, we propose 

that transcontinental shorebirds disperse and use wetlands opportunistically.” 

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. Passerines must cross the Gulf nonstop and are at risk for exhaustion and 

starvation. 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). Mitigation for this mortality has 

not been developed. Platforms may serve as stopover sites for migrating birds tired from nocturnal 

circulation. 

Passerine migrants stopping over on the Gulf Coast in the CPA before trans-Gulf migration south in 

the fall or after trans-Gulf migration north in the spring are not aquatic or associated with beach or dune 

habitat, and they would not likely be impacted by oil from the DWH event, with the possible exception of 

the seaside sparrow (USDOI, FWS, 2011). Of about 21 species of songbirds collected alive or dead after 

the DWH event, only 4 (including the seaside sparrow) were found more than twice; a total of 9 seaside 

sparrows were collected (USDOI, FWS 2011). The heaviest trans-Gulf migration of birds in general is 

from the stretch of the northern Gulf Coast running eastward from Alabama (Russell, 2005). Seaside 

sparrows stopping over on the Gulf Coast after trans-Gulf migration in spring would likely follow a 

clockwise path mostly over the western Gulf, which is taken by the heaviest migration of birds in general 

(Russell, 2005). 
4-254 Central Planning Area Supplemental EIS 

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 

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. A total of 10 whooping cranes were reintroduced to 

Louisiana in the White Lake Conservation Area during the winter of 2011 as a nonessential experimental 

population. 

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. They are elusive and rarely seen within the low vegetation of fresh and saline marshes, 

swamps, and rice fields, where they walk on long toes (Bent, 1926; Ripley and Beehler, 1985, Eddleman 

et al., 1988; National Geographic Society, 1999). They run, rather than fly, through the marsh when 

disturbed. 

Marsh and tall wading birds spend the majority of their lifecycles in wetlands and marshes. These 

birds do not laterally migrate from east to west, and tall wading birds do not typically migrate any 

distance. All tall waders, with the exception of the least bittern, white faced ibis, and roseate spoonbill, 

are permanent residents. 

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., 1982; 

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). Flyways are somewhat abstract generalizations of migratory behavior. Some birds at 

some latitudes migrate laterally (along an east-west axis) within or between flyways. Waterfowl are 
Description of the Environment and Impact Analysis 4-255 

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 falcon’s foraging habitats include estuarine marshes and 

beaches with adequate places to perch (Vermillion, official communication, 2011). The foraging habitat 

of short-eared owl and osprey (both raptors) includes coastal marshes (Vermillion, official 

communication, 2011; Firmin, official communication, 2011). The bald eagle was delisted on August 8, 

2007. It is still afforded some protection under the Migratory Bird Treaty Act and the Bald and Golden 

Eagle Protection Act. The Northern harrier is listed as a species of concern in Louisiana. It forages in 

salt, brackish, intermediate, and fresh marsh and coastal dune-grassland shrub thicket habitat (Vermillion, 

official communication, 2011; Firmin, official communication, 2011). 

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 

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, official 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, official 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 possible presence of oil in intertidal sediment may occur on a long-term time 

scale and require long-term monitoring to assess the fate of the oil. While awaiting long-term assessment 

of impacts of the DWH spill, substantial long-term information is available from another incident (Teal et 

al., 1978). The barge Florida grounded off West Falmouth Harbor, Buzzards Bay, Massachusetts, 

spilling No. 2 fuel oil in 1969; booms were unable to keep the oil out of Wild Harbor. In the intertidal 
4-256 Central Planning Area Supplemental EIS 

sediments, the spilled oil persisted for at least 8 years. Sediments from the Wild Harbor station yielded 

1-3 milligrams per gram (mg/g) aromatic hydrocarbons per gram of dry weight until at least July 1976, 

compared with 0.02-0.04 mg/g for control stations (Teal et al., 1978). In support of a conclusion that 

cleanup has been successful, in a short-term analysis, the Operational Science Advisory Team (2010) 

found no deposits of liquid-phase DWH event oil in sediments beyond the shoreline. The situation may 

be different for marshes and tidal flats. The oil may remain in its unweathered toxic state indefinitely. 

However, oil weathering as it travels to the coast ameliorates toxicity at the shoreline. Oiled sediments 

could expose birds that feed in muddy areas (e.g., shorebirds) and oil could be resuspended in changing 

weather conditions. 

The oil from the DWH event has had serious direct and indirect impacts to coastal and marine birds 

(USDOI, FWS, 2011), but it is premature to report the welfare of any population as altered over a long 

period. As of May 12, 2011 (the last publicly available report on collected birds), 6,381 total birds 

(visibly oiled, not visibly oiled, or oiling unknown) were found dead or found alive and later died, of 

which an unknown number were killed by the DWH event (USDOI, FWS, 2011). Modeling of bird 

impacts is underway by NRDA, but the results have yet to be publicly released. However, peer-reviewed 

modeling of bird mortality was completed by Antonio et al. (2011). Carcasses were collected along 

2,600 km (1,616 mi) of the U.S. coast. The spill was on April 22, 2010, and dead birds began to be 

collected on May 28, 2010, 37 days later. Cumulative carcass numbers, and consequently the daily 

mortality rate, increased exponentially with time until the daily mortality rate began to decline about 

110 days after the spill; cumulative carcass numbers stopped increasing seriously 140 days after the spill. 

The collected animals were a small subset of the total number of birds actually killed and, therefore, they 

are an underestimated measure of the overall impact of the DWH event. 

Although the Exxon Valdez spill happened under different conditions, the need for adequate modeling 

was the same. A total of 30,000 dead oiled birds were found on the beaches, but total mortality was 

estimated at 100,000-300,000—up to 10 times more than the number found (Piatt and Anderson, 1996). 

Several populations had not fully recovered about 7 years after the spill (Piatt and Anderson, 1996). 

Some birds may leave a region after being oiled, causing a downward bias in oil impacts. 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). In this 

Supplemental EIS, the bald eagle is addressed under the section on raptors above. 
Description of the Environment and Impact Analysis 4-257 

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). In this Supplemental EIS, the brown pelican is addressed 

under the section on seabirds above. 

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, whooping crane, Mississippi sandhill crane, and the wood stork. 

Following the DWH event, BOEM requested reinitiation of ESA consultation with FWS on July 30, 

2010. The FWS responded with a letter to BOEM on September 27, 2010. The reinitiated consultation is 

not complete at this time, although BOEM, as lead agency, and BSEE are working with FWS to develop 

an interim coordination program in the interim (Chapter 5.7). 

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. The FWS indicates that the presence of vegetation on 

the breeding grounds in the Great Plains, the Great Lakes, and along the Atlantic Coast (Newfoundland to 

North Carolina) imposes an extreme threat of predators on breeding adults (USDOI, FWS, 2003). 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. Unlike the breeding grounds in the 

Great Plains, the Great Lakes and along the Atlantic Coast, there are far fewer stresses to the piping 

plover at its wintering grounds, including those in the CPA, as there are far more suitable habitats in the 

CPA. 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 

final rule on the critical habitat for piping plover was published July 10, 2001; there are 20 critical habitat 

units in western Florida south to Tampa Bay, 3 areas in Alabama, 15 areas in Mississippi, 7 areas in 

Louisiana, and 37 areas in Texas (Federal Register, 2001). 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). 

Although there is no specific information on impacts on the piping plover since the DWH event, those 

piping plover that winter in the CPA would not be expected to have been directly impacted by the spill. 

These birds use the GOM as wintering habitat; therefore, they are not believed to have been in residence 
4-258 Central Planning Area Supplemental EIS 

during the spill event. At this time, there is limited information on indirect impacts to the species, such as 

habitat loss and reductions in prey, that may have resulted from the DWH event. The NRDA process is 

continuing to investigate the potential for secondary impacts. 

Whooping Crane 

The whooping crane (Grus americana) is an omnivorous, wading bird. Whooping cranes currently 

exist in three wild populations and at twelve captive locations (USDOI, FWS, 1994; Louisiana Dept. of 

Wildlife and Fisheries, 2011). All of the populations are listed as endangered. A catastrophic event such 

as a hurricane could destroy the world’s only naturally occurring flock (which is migratory) when it is 

present in Texas at the Aransas National Wildlife Refuge (Canadian Wildlife Service and USDOI, FWS, 

2007). These whooping cranes originate from only six to eight birds in the 1940’s, so their tiny gene pool 

with lack of genetic variation (variation needed to adapt to any variation in the environment) could harm 

reproduction in the future (Canadian Wildlife Service and USDOI, FWS, 2007). 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). This nonmigratory population is 

not expected to have been impacted by the DWH event due to its location. The 2007 wild populations 

were estimated to total 355; the captive population contained 148 birds (Stehn, official communication, 

2007). The 2010 wild populations were estimated to total 401; the 2010 captive populations were 

estimated to total 166 (Stehn, official communication, 2011). 

A total of 10 whooping cranes were reintroduced to Louisiana in the White Lake Conservation Area 

during the winter of 2011 as a nonessential experimental population. The last previous whooping crane in 

Louisiana was recorded in 1950. Reintroduction efforts in the Conservation Area will focus on using 

young hatched from whooping cranes at captive breeding sites. The Conservation Area was chosen 

because whooping cranes historically occurred in Louisiana in both a resident nonmigratory flock and a 

migratory over-wintering flock, because they were historically documented to raise young there, and 

because of exceptional support from the public (Louisiana Dept. of Wildlife and Fisheries, 2011). The 

Deepwater Horizon incident did not affect the release area, which is a fresh-to-brackish estuarine marsh 

about 17 miles from the coast. The flock will be nonmigratory to establish a flock as it occurred naturally 

in Louisiana and to avoid interaction with the existing Aransas-Wood Buffalo populationin Texas and the 

eastern migratory population (Louisiana Dept.of Wildlife and Fisheries, 2011). Birds in the conservation 

area will be closely monitored (Louisiana Dept.of Wildlife and Fisheries, 2011). The population is 

designated “non-essential” because the likelihood of survival of the whooping crane as a species would 

not be reduced if the entire population was not successful and was lost (Louisiana Dept.of Wildlife and 

Fisheries, 2011). The population is further designated as “experimental” because it is being introduced 

into suitable habitat that is outside of the whooping crane’s normal range but within its historical range 

(Louisiana Dept.of Wildlife and Fisheries, 2011). 

Mississippi Sandhill Crane 

The Mississippi sandhill crane population was listed (June 4, 1973) as endangered under the 

Endangered Species Act for a nonmigratory subspecies in Mississippi only, and it is only located in the 

area of the Mississippi Sandhill Crane National Wildlife Refuge (USDOI, FWS, 1973 and 1991; Tacha et 

al., 1992). Until 1972, all resident-breeding sandhill cranes were considered the same subspecies 

(USDOI, FWS, 1991). The Mississippi sandhill crane is now designated as a distinct subspecies. The 

subspecies was originally listed due to habitat degradation and fragmentation related to timber harvest, 

highways development, and commercial and residential development, as well as associated human 

disturbance of nest, roost, and foraging sites (Matthews and Moseley, 1990). From the 1950’s to the 

present, savannas declined from 74 percent to 14 percent of habitat in the area (Tacha et al., 1992). 
Description of the Environment and Impact Analysis 4-259 

Currently, the breeding range of the “listed” population is extremely limited geographically, and much of 

it is protected as part of the Mississippi Sandhill Crane National Wildlife Refuge (~19,000 ac; 7,689 ha) 

in Jackson County, Mississippi. Its main winter roost is in the marshes of Bluff Creek, Bayou Castelle, 

and Paige Bayou (Matthews and Moseley, 1990). In spring, summer, and fall the birds feed on the 

breeding grounds in savannas, swamps, and open pine fields. In winter, the species flies to small corn 

fields and pastures to feed (Tacha et al., 1992). Cultivated grains are a major food item when available. 

Nest sites are usually in marshes, bogs, or swales (Tacha et al., 1992). Although they typically nest in 

attached or floating nests over water, they will nest on dry ground (Tacha et al., 1992). Nut-rush (Scleria 

baldwinii) is a key indicator species for nest sites (Tacha et al., 1992). They feed primarily on land or in 

shallow marshes with emergent vegetation. A captive-rearing program (release of immatures) continues, 

but this augmentation appears to simply offset “natural” mortality of first- and second-year birds; the 

population is apparently stable at a very low level, but restricted numbers and distribution increase 

extinction risk (USDOI, FWS, 1991). The most recent revision (3rd Revision) to the recover plan was 

completed on September 6, 1991 (USDOI, FWS, 1991). 

Sandhill cranes are perennially monogamous and typically raise one young a year to fledging (Tacha 

et al., 1992). Young leave the nest soon after hatching (Tacha et al., 1992). Pesticides have not been 

implicated in egg shell thinning. Although capable of wading, Mississippi sandhill cranes are 

omnivorous, exploiting subsurface food items by probing with bills (Tacha et al., 1992). 

Recently, there was Notice of Initiation for Review and Request for Information for 10 listed species 

in the southeastern U.S. (April 9, 2010; USDOI, FWS, 2010b). An emergency determination of critical 

habitat was originally provided on June 30, 1975 (USDOI, FWS, 1977). A Final Rule was designated on 

August 8, 1977 (42 FR 39985-39988) and included only areas within Jackson County, Mississippi. As of 

November 30, 2010, no sandhill cranes had been collected as part of monitoring efforts related to the 

DWH event. 

At the time of the Biological Assessment (September 14, 2007), the Mississippi sandhill crane was 

listed, but FWS acknowledged that “The following species may occur within the coastal counties or 

parishes of the action area, but inland of the GOM, and therefore, are not likely to be impacted by the 

proposed action.” Therefore, this species was not actually analyzed as part of the Biological Assessmetn 

by FWS relative to the Multisale EIS (USDOI, MMS, 2007c). Although the Mississippi sandhill crane 

likely has a low probability of oiling due its selection of more inland freshwater marshes, it may forage in 

coastal, brackish, or saltwater marshes, thus increasing its probability of oiling in the case where spilled 

oil is pushed into the rivers and marshes due to hurricanes, tropical storms, and the associated storm 

surge. In addition, this crane appears to select more coastal marsh areas during the wintering period. As 

of May 12, 2011, 6,381 total birds (visibly oiled, not visibly oiled, or oiling unknown) were found dead or 

found alive and later died, of which an unknown number were killed by the DWH event (USDOI, FWS, 

2011). To date, none of the birds collected were identified as Mississippi sandhill cranes. In light of the 

“take” of a substantial number of birds associated with the DWH event (USDOI, FWS, 2011) and the 

potential for negative impacts to some of the sandhill crane’s foraging and roosting habitat, BOEM 

believes it is conservative to consider this species as part of this Supplemental EIS. 

Wood Stork

The U.S. population of wood storks was listed as endangered for Alabama, Florida, Georgia, and 

South Carolina (not listed elsewhere) under the Endangered Species Act on February 28, 1984, because of 

the overall impact of human activities on breeding colonies. The activities resulted primarily in loss of 

feeding habitat and diverse effects of water-level manipulations on habitat (Coulter et al., 1999; USDOI, 

FWS, 1984). Known breeding is in the southeastern U.S., Mexico, Central and South America, 

El Salvador, Panama, and Costa Rica (Coulter et al., 1999, Figure 1). Within the U.S., the current 

breeding range appears to be limited to Florida (which is its primary range, with the largest number of 

colonies and largest number of breeding pairs), Georgia, and South Carolina; however, they can be found 

at various times of years in other coastal states including Texas, Louisiana, Mississippi, and Alabama 

(Coulter et al., 1999; Frederick and Meyer, 2008). Wood storks often nest in woody swamps or 

mangroves and often prefer some species of trees for nesting (Coulter et al., 1999). The species is not a 

typical migrant, and movements are probably in response to local environmental conditions (Coulter et 

al., 1999). Beginning in late May, following breeding in Florida, most fledglings, immatures, and adults 
4-260 Central Planning Area Supplemental EIS 

disperse in peninsular Florida and northward, primarily along coastlines and in vicinity of large rivers on 

the coastal plain (Coulter et al., 1999). Birds from Florida colonies disperse throughout central and 

northern Florida, as well as into Georgia and South Carolina (Coulter et al., 1999). The number of storks 

dispersing north from Mexico to summer in Texas and Louisiana varies greatly between years. This is 

based on the following observations: (1) all U.S. breeding colonies are in the Southeast; (2) no marked 

bird from these colonies has been sighted west of eastern Mississippi; (3) marked birds from southern 

Florida colonies move primarily north along the Atlantic Coast; and (4) large numbers of storks have been 

reported in Louisiana and the lower Mississippi flood plain, with large possible source colonies in Mexico 

and Central America, and large flocks have been seen flying north along the Gulf Coast of Mexico in 

June (Coulter et al., 1999). Storks in southern Louisiana, the lower Mississippi Valley, Texas, and other 

western states are probably moved there from Mexico and possibly from Central America (Coulter et al., 

1999). Coastal colony sites are usually flooded by tidal activity or are located on islands (Coulter et al., 

1999). Wood storks probably do not bond for more than one breeding season. They feed in flocks, 

usually with other waterbirds and often in open wetlands. No statistical differences in vegetation 

characteristics, water quality, or prey densities between used and adjacent unused wetlands suggest an 

abundance of suitable forging sites (Coulter et al., 1999). In southern Florida, the species obtains most 

food from water 15-50 cm (6-20 in) deep. Wood storks wade and feed on aquatic organisms, mostly fish. 

The use of foraging habitat may depend on tidal stage; storks were observed to use estuarine and tidal 

creeks during low tide and palustrine sites during high tide (Coulter et al., 1999). 

Population declines of the wood stork in southern Florida have been balanced to some extent by 

increased movement into central and northern Florida, Georgia, and South Carolina (Coulter et al., 1999). 

From northern Florida through coastal South Carolina, wetlands are smaller and fish are not as 

concentrated as they are in southern Florida. Colony size is smaller in central and northern Florida, 

southern Georgia, and coastal South Carolina than historic colony size was in southern Florida. The area 

of linear coastal or riverine wetlands to the north may be smaller than the area of wetlands that 

historically surrounded large colonies in south Florida and may limit colony size to the north of south 

Florida (Coulter et al., 1999). The ecology of this stork differs to the north (Coulter et al., 1999). The 

birds feed alone or in small groups, among low densities of larger prey, and they usually breed 

successfully. They may encounter more dry years to the north because wetlands may be smaller and, 

therefore, may be dry more often. In northern Florida and east-central Georgia, prey densities are lower 

during dry years than during years with substantial rainfall. In addition, in dry years in impounded 

colonies there, water under nest trees may dry and alligators may leave, allowing raccoons to move in and 

destroy almost all fledglings in a few days. In the Everglades of southern Florida, birds depend on high 

concentrations of fish in pools resulting from evaporative drawdowns. When a rainy season occurs before 

fledging, prey concentration does not occur and young do not survive. 

The population was originally listed due to apparent major declines from the 1960’s through the late 

1970’s (Coulter et al., 1999). Since that time, the population appears to be increasing and has exhibited a 

geographical shift (Ogden et al., 1987; Rodgers et al., 1987; Borkhataria et al., 2008; Frederick and 

Ogden, 1997), with substantial increases in northern Florida, Georgia, and South Carolina (USDOI, FWS, 

1996). Habitat loss and degradation, contaminants (DDT, PCB’s, and mercury; references in Coulter et 

al., 1999), and disturbance at nesting colonies and foraging and roost sites likely caused historical 

declines and its subsequent listing (USDOI, FWS, 1984; Coulter et al., 1999). 

The Florida population of wood stork was considered for redesignation from endangered to 

threatened on September 21, 2010 (90-day review initiated; USDOI, FWS, 2010c). No critical habitat 

rules have been published for this species. The wood stork is considered a State Species of Conservation 

Concern in Alabama, Florida, and Mississippi. 

Although it likely has a low probability of oiling due its selection of more inland freshwater marshes, 

it may forage in coastal, brackish, or saltwater marshes, thus increasing its probability of oiling in the case 

where spilled oil is pushed into the rivers and marshes due to hurricanes, tropical storms, and the 

associated storm surge. As of May 12, 2011, 6,381 birds (visibly oiled, not visibly oiled, or oiling 

unknown) were found dead or found alive and later died, of which an unknown number were killed by the 

DWH event (USDOI, FWS, 2011). As of November 30, 2010, no wood storks had been collected as part 

of monitoring efforts related to the DWH event. In light of the “take” of a substantial number of birds 

associated with the DWH event (USDOI, FWS, 2011) and the potential negative impacts to some of the 

wood storks’ foraging habitat and potential prey (relatively large centrarchid fishes), BOEM believes it is 
Description of the Environment and Impact Analysis 4-261 

conservative to consider this species as part of this Supplemental EIS. Given that FWS only recognizes 

wood storks occurring in Alabama and Florida as listed, it should only be considered for potential impacts 

relative to OCS activities in the far northeastern portion of the CPA. 

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 

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 the 

abundance and distribution of some species. 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, official 

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 and amphibians were also killed by flooding saltwater 

moving inland. We can expect a possible impact on birds whose populations are contolled by the 

availability of food. Experimental reasoning tells us from gut contents’ analysis experiments and bird 

distribution studies that birds use the food resources destroyed by the hurricanes. However, no studies on 

the impacts of hurricanes on bird populations have been done. Hurricanes are regularly experienced by 

birds in the Gulf of Mexico, and some bird populations may have initially declined. Some bird 

populations may have had a reduced baseline abundance from hurricane-induced mortality. Such 

mortality may have been compensatory. Recovery may have begun immediately, due to reduced 

crowding, and may by now be complete. 

Effect of the Deepwater Horizon Event on Baseline Conditions 

The use of waterbird feeding areas at the sea surface and intertidal wetland zone, where spilled oil 

tends to accumulate, makes them vulnerable to exposure to oil from the DWH event. Currently, known 

impacts or potential impact to specific bird groups and bird species are described above; nevertheless, 

information specific to birds and potential impacts in the CPA remains incomplete or unavailable at this 

time. This information is being developed through the NRDA process, which may take many years, and 

much of the information NRDA has compiled to date is not publicly available at this time. As there is a 

process ongoing that may take years, given the realities of the DWH event, cost is not a relevant factor in 

BOEM’s ability to obtain this information; it cannot be obtained at this time under any circumstances. 

This incomplete and unavailable information may be relevant to reasonably foreseeable significant 

impacts on birds, and BOEM believes it may be essential to a reasoned choice among alternatives for 

many bird species or populations. However, this incomplete or unavailable information will likely not be 

essential for piping plovers (which were at their summer breeding habitat to the north at the time of the 

event), whooping cranes (which were introduced in Louisiana after the event in habitat unaffected by the 

spill), wood stork populations that are listed as endangered (because their Florida habitat was unlikely to 

be affected by the spill), and Mississippi sandhill cranes (because the area in and around their primary 

habitat at Mississippi Sandhill Crane National Wildlife Refuge was unaffected by the spill). In light of 

the incomplete or unavailable information, BOEM subject-matter experts have used available 

scientifically credible evidence in this analysis, based upon accepted methods and approaches. 
4-262 Central Planning Area Supplemental EIS 

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 their 

habitat in 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, pipeline landfalls and other onshore OCS-related 

construction, discarded trash and debris from service-vessels and OCS structures, and structure presence 

and associated light and presence. Any effects on birds may be especially important 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. Chronic sublethal stress 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. However, whooping crane, piping plover, Mississippi sandhill 

crane, and wood storks (i.e., the listed species in the CPA) tend to be removed from most routine 

activities, and these species have not demonstrated a clear inability to complete migration; as such, at the 

present time, these species are not showing visible signs of stress. 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 to 

neighboring areas. 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. 

Chapter 4.2.1.1.7 of the Multisale EIS provides an indepth discussion of air pollution pathways and 

impacts on birds. Air pollution may cause physiological impairment and further lead to diseases. Impacts 

may include direct mortality, debilitating injury, disease, physiological stress, anemia, hypocalcemic 

condition, bioaccumulation of air pollutants with associated decrease in resistance to debilitating factors, 

and population declines and changes in distribution. Levels of sulfur oxide (mainly sulfur dioxide, SO2) 

emissions from hydrocarbon combustion from OCS-related activities are of concern in relation to birds. 

Research specific to birds has elucidated both acute and chronic effects from SO2 inhalation (Fedde and 

Kuhlmann, 1979; Okuyama et al., 1979). 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 foraging 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. Chapter 4.1.1.1.2 

provides an analysis of the effects of the CPA proposed action on air quality and notes that emissions of 

pollutants into the atmosphere from the activities associated with the proposed action would have minimal 

effects on offshore and onshore air quality because of the prevailing atmospheric conditions, emission 

heights and rates, and pollutant concentrations. 

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. 
Description of the Environment and Impact Analysis 4-263 

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. A major 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 exert 

additional pressure on the habitat, as a result of intra- and interspecific competition for space or food. 

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. 

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. Impacts to coastal habitats from 

pipeline canals and from navigation canals used by OCS-related service vessels will occur over the long 

term and may ultimately displace species of 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. 

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. 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. Routine 

impacts of platform presence and lighting on trans-Gulf migrants are discussed in the “Proposed Action 

Analysis” below. 

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 
4-264 Central Planning Area Supplemental EIS 

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. 

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. Habituation occurs when the central nervous system of an individual is 

presented with a highly repetitious stimulus and eventually no longer responds to the stimulus. 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. 
Description of the Environment and Impact Analysis 4-265 

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 

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). 

Impacts of OCS-related facilities such as pipeline landfalls and gas processing plants may occur. 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 for feeding, cover from 

predators, or nesting. Birds could suffer from lack of food, increased predation, or impacts on 

reproduction. 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. A new gas processing plant would not be expected to be constructed on a barrier 

beach. Existing facitities originally built inland may, due to natural erosion and shoreline recession, 

eventually be located in the barrier beach and dune zone and contribute to erosion there. Erosion may 

cause loss of vital bird nesting, feeding, and roosting habitat on dunes and beaches. The CPA proposed 

action may contribute to the continued use of existing gas processing plants. 

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 BSEE prohibitions on the disposal of equipment, containers, 
4-266 Central Planning Area Supplemental EIS 

and other materials into offshore waters by lessees (30 CFR 250.300). 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 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/

threatened and nonendangered/threatened coastal and marine birds are expected to be intermittent, of 

small spatial scale, and short term. The ability to fly will often result in avoidance and quick 

reestablishment. These intermittent effects include behavioral effects, exposure to or intake of OCSrelated 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. 

Impacts from pipeline and navigation canals to coastal habitats will occur over the long term and may 

ultimately displace species. 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 
Description of the Environment and Impact Analysis 4-267 

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. 

Although there will always be some level of incomplete information on the effects from routine 

activities under this proposed action on birds, there is credible scientific information, applied using 

acceptable scientific methodologies, to support the conclusion that any realized impacts would be 

generally sublethal in nature and not in themselves rise to the level of reasonably foreseeable significant 

adverse (population-level) effects. With the exception of piping plovers, wood storks, whooping cranes, 

and Mississippi sandhill cranes (which due to their habitat location are unlikely to have been impacted by 

the DWH event or to be impacted by routine activities), BOEM cannot definitively determine that the 

incomplete or unavailable information will not be essential for certain individual species or populations. 

This information is currently unavailable and is being developed through the NRDA process, which will 

take years. There is no timeline for this information becoming available and certainly not within the 

timeline of this Supplemental EIS. Nevertheless, it is not expected that other species will have been 

impacted by the DWH event to such an extent that the conclusions on impacts from routine activities will 

change. Routine activities will be ongoing in the proposed action area (CPA) as a result of existing leases 

and related activities. (In the CPA, there are 4,503 active leases as of November 2011). Within the CPA, 

there is a long-standing and well-developed OCS Program (more than 50 years); there are no data to 

suggest that routine activities from the preexisting OCS Program are significantly impacting coastal and 

marine bird populations. 

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 section 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 physiological impacts of oil 

spills are potentially similar for both. However, impacts on individuals are more likely to lead to 

population impacts, including local extinction for the small populations of listed species. 

No peer-reviewed studies of the impacts of oil spills on birds in the Gulf of Mexico, including 

impacts of cleanup of the spill from the DWH event and long-term impacts on forage food supplies for 

birds, are now publicly available. This information is being developed through the NRDA process, which 

may take many years, and what information NRDA has compiled to date is not publicly available at this 

time. As there is a process ongoing that may take years, given the realities of the DWH event, cost is not 

a relevant factor in BOEM’s ability to obtain this information; it cannot be obtained at this time under any 

circumstances. The BOEM has applied what additional scientifically credible information is available 

using accepted methodologies as described above. In place of Gulf-specific studies, investigations of 

spills in other areas, mathematical modeling, and laboratory tests (e.g., toxicity tests and veterinarian 

studies of rehabilitation) are used for insight into DWH impacts on all life history stages of birds. This 

section on accidental impacts concerns the proposed action only; the DWH event is discussed in relation 

to bird baseline conditions in the description of the affected environment for birds. Also, this section 

discusses accidental impacts relative to estimated baseline conditions (Chapter 4.1.1.12.1). Although 

relevant to a discussion of reasonably foreseeable significant adverse impacts, information on the DWH 

event is not essential to a reasoned choice among alternatives, given the existing body of scientific 

evidence related to oil-spill impacts on birds. Although information from the DWH event would be 

useful, it is not expected to significantly change this existing body of science. 
4-268 Central Planning Area Supplemental EIS 

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 

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, 

phenanthrene, and anthracene are significantly less volatile and water soluble than hydrocarbons like 

benzene; however, they are somewhat volatile and water soluble, and they are more persistent in seawater 

than compounds like benzene. The lighter PAH’s 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 not been extensively characterized, but some symptoms have 

been recorded (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 would also diffuse 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 
Description of the Environment and Impact Analysis 4-269 

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 would 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 would, 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. 

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). Dispersant contact with most birds is unlikely because dispersants, including those applied to the 

sea surface, have a fate that is similar to dispersed oil. They are mixed into the water column well below 

the sea surface where their concentration is extremely diluted, even from the point of view of a seabird 

diving into the water column for food. Wave action may remove all dispersed oil from a slick into the 

water column, well below the sea surface where contact with birds is less of an issue. 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 would 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 would penetrate the hydrophobic core 

of the plasma membrane of cells and would 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. 
4-70 Central Planning Area Supplemental EIS 

2011). These reports noted that, since August 2010, there have been no exceedances for USEPA aquatic 

life benchmark for PAH’s in either sediments or water sampled at distances >3 km (~2 mi) from the 

DWH wellhead (OSAT, 2010). In addition, it was noted that 86-96 percent of the total PAH’s was 

depleted during the weathering process while being transported to shore (OSAT-2, 2011). 

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. 

Deepwater Horizon Event 

Another factor that is now superimposed on the hurricane damage is the currently unknown, longterm effect of the oil spill from the DWH event. 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. A review of the current SCAT maps 

(USDOC, NOAA, 2011b) indicate that the coastline from the Louisiana/Texas State line (Sabine) to 

Panama City, Florida, continues to improve and is being categorized as shoreline with no oiling to lightly 

oiled, with the exception of the Bay Jimmy area in southeastern Louisiana. From Cameron, Louisiana, 

east to Terrebonne Bay, there was either no oil or small patches of light oiling along the Isle Dernieres 

and the Terrebonne Bay shoreline. There were also small patches of marsh in Terrebonne Bay that were 

lightly oiled. Moving farther east, the shoreline adjacent to Barataria Bay only had trace to light oiling 

observed, with the exception of the initially heavily oiled Bay Jimmy area. The marsh fringe on the back 

side of the two large gulfward islands forming the entrance to Bay Jimmy are currently not oiled to lightly 

oiled. Approximately 2 km (1.2 mi) of the shorelines along the interior canals of these islands are still 

categorized as heavily oiled and are currently undergoing evaluation for further cleaning (USDOC, 
Description of the Environment and Impact Analysis 4-71 

NOAA, 2011b). The island forming the western shore of Bay Jimmy varies from having no observed oil 

to having observations of light to very light oil, and it only has small patches of moderate to heavily oiled 

shoreline. Approximately 1.6 km (1 mi) of marsh bordering the eastern cove of the island that creates the 

back side of Bay Jimmy also remains heavily oiled (USDOC, NOAA, 2011b). The oil penetration in 

these marshes is estimated to be 5.5 m (18 ft) inland (Kokaly et al., 2011). While the SCAT maps 

graphically depict 5.7 km (3.5 mi) of shoreline as heavily oiled, in most cases, this represents only the 

area surveyed and not necessarily the total amount of area oiled. 

As noted above, BOEM recognizes that there remains incomplete and unavailable information related 

to wetlands, including impacts from the DWH event. Here, BOEM concludes that the unavailable or 

incomplete information may be relevant to foreseeable significant adverse impacts to wetlands. Relevant 

data on the status of wetlands and marshes after the DWH event may take years to acquire and analyze, 

and impacts from the DWH event may be difficult or impossible to discern from other factors. The 

NRDA process is ongoing, and to date much of the information collected as part of the process has not 

been fully analyzed and conclusions have not been released to the public. It may be years before NRDA 

data and conclusions are available. Therefore, it is not possible for BOEM to obtain this information 

within the timeframe contemplated in this Supplemental EIS, regardless of the cost or resources needed. 

In light of the incomplete or unavailable information, BOEM subject-matter experts have used available 

scientifically credible evidence in this analysis, based upon accepted scientific methods and approaches. 

Nevertheless, BOEM believes that incomplete or unavailable information regarding heretofore unknown 

effects of the DWH event on wetlands and marshes is not essential to a reasoned choice among 

alternatives in the cumulative effects analysis. Although there may still be incoming information, there is 

significant available data on shoreline oiling and the current status of wetlands and marshes from the 

SCAT and ERMA databases that have assisted BOEM subject-matter experts in their analyses. Future 

incoming data are not expected to significantly alter these conclusions, and future impacts are not 

expected. 

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. 

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 

in the event of disturbed 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 include dredging, 

waste disposal, trenching associated with pipeline emplacement, entrainment and shallow-water vessel 

traffic. 

Pipeline Emplacement 

For the CPA proposed action, there would be 390-1,162 km (241-722 mi) of installed pipeline in 

Federal waters (Table 3-3). 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 
4-272 Central Planning Area Supplemental EIS 

Northern Hemisphere so they would be vulnerable to any outside impacts as opposed to just those in the 

CPA or Gulf of Mexico. Impacts of the CPA proposed action on all coastal birds are expected to be 

negligible because any reductions in populations likely would not be sustained. Oil-spill cleanup is not 

expected to affect coastal birds if all personnel are completely trained, reducing the potential impacts 

from the scaring of feeding, roosting, or nesting birds or from the destruction of nests. Reduced impacts 

of oil slicks after dispersant application would likely more than offset the impacts from dispersants and 

chemically dispersed oil, which do not remain on the sea surface where they would contact birds or bird 

shoreline habitat. 

Summary and Conclusion 

Oil spills may have serious direct and indirect impacts to coastal and marine bird health and habitat 

for feeding, roosting, sleeping, and nesting. In shallow water, such spills would have impacts on birds 

directly through contamination of skin and plumage, interfering with their ability to maintain body 

temperature, buoyancy, waterproofing, and the ability to fly. Impacts on individuals are much more 

serious for populations of endangered or threatened species (such as the piping plover and the whooping 

crane) than for nonlisted species because low populations of listed species may be more likely to face 

extinction because of the disappearance of a relatively small number of individuals. The lighter PAH’s 

have the greatest impacts on birds because of their persistence and high concentration. They are harmful 

to cell membranes. 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. Exposure to 

oil in the water column was modeled to be minor. When oil gets into vegetated or unvegetated sediment, 

it may remain in its unweathered toxic state indefinitely. However, oil weathering as it travels to the 

coast ameliorates toxicity at the shoreline. Small amounts of oil can affect the health of birds. Birds may 

have reduced reproductive effort, causing temporary declines in population abundance. 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. With properly trained 

and supervised personnel, impacts of oil-spill cleanup from the proposed action are also expected to be 

negligible. Although a low-probability catastrophic event like the DWH event remains a remote 

possibility, such a large-scale effort could increase the potential impacts from oil-spill cleanup 

(Appendix B). 

Among accidental events related to the proposed action, oil spills have the greatest potential to impact 

coastal and marine bird populations. Nevertheless, oil-spill 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 

(combined probabilities are always <15%), not rising to the level of population impacts. An exception 

would be the piping plover, where impact on a small number of birds could considerably reduce a 

population. The piping plover is in low abundance, but its wintering habitat is plentiful in the Gulf of 

Mexico. An oil spill would likely only contact a small portion of this wintering habitat in the GOM; thus, 

the greatest threats to the recovery of the piping plover remain at its breeding habitat in the Great Plains 

and Great Lakes, not the OCS Program or this proposed action. 

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. 
Description of the Environment and Impact Analysis 4-273 

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; 

 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). 
4-274 Central Planning Area Supplemental EIS 

Proposed Action Analysis 

OCS-Related and Non-OCS-Related Air Emissions 

Chapter 4.2.1.1.7 of the Multisale EIS and Chapter 4.1.1.12.2 of this Supplemental EIS provide an 

overview of air pollution pathways and impacts on birds. As described there, air pollution may cause 

physiological impairment and may further lead to diseases. Impacts may include direct mortality, 

debilitating injury, disease, physiological stress, anemia, hypocalcemic condition, bioaccumulation of air 

pollutants with associated decrease in resistance to debilitating factors, and population declines and 

changes in distribution. Effects may vary from lethal to sublethal and from short term to long term. 

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 would have a negligible effect on coastal and marine birds. 

OCS-Related Impacts 

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. As described in Chapter 4.5.8 of the Multisale EIS, toxic effects on birds from impaired 

water quality could include reduced survival, loss of habitat and food sources, and reduced reproduction. 

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 

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). 
Description of the Environment and Impact Analysis 4-275 

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. Terrestrial birds 

cannot stopover to feed on the water so they must have the energy to fly nonstop across 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 

platform collision or it may cause acute sublethal stress or death from exhaustion, 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. Although construction of this 

potential gas processing plant would necessitate some associated habitat loss, the contribution of 

development from non-OCS-related urban and other industrial growth would be substantial in 

comparison, causing both the permanent loss of lands and increased levels of disturbance associated with 

new construction and facilities. A large variety of wild birds usually cannot exist in suburban or urban 

areas. 
4-276 Central Planning Area Supplemental EIS 

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. Impacts to birds would be indirect (loss of 

wetland, feeding, and nesting habitat). The regulatory apparatus for mitigation of pipeline canal dredging 

in wetlands is managed by the U.S. Army Corps of Engineers. Mitigation would likely prevent 

substantial impact on wetland bird populations. Mitigation includes avoidance, restoration, use of 

existing pipeline corridors, back-filling, directional drilling, push-pull trenchless pipeline installation, and 

careful dredge spoil disposal to avoid blocking water flow across wetlands. 

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 where individual impacts may reach 

population impacts), making them susceptible to infection and disease. Chronic sublethal stress is often 

undetectable in birds. It can serve to weaken individuals (especially serious for migratory species that 

must rely on strength and endurance for long-range flight), 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 sometimes become entangled in or 

ingest OCS-related trash and debris, but impacts are expected to be considerably reduced as a result of 

BSEE prohibitions on the disposal of equipment, containers, and other materials into offshore waters by 

lessees (30 CFR 250.300). 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; therefore, a threat to individual birds remains within these areas. 

Non-OCS-Related Impacts 

Habitat Degradation 

The contribution of development from urban and industrial growth will be substantial because of an 

expanding economy, causing both the permanent loss of lands and increased levels of disturbance 

associated with new construction and facilities. Habitat alteration has the potential to disrupt social 

behavior, food supply, and the health of birds that occur in the Gulf of Mexico. Real estate development 

in coastal and other habitat 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 
Description of the Environment and Impact Analysis 4-277 

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 from non-OCS Program-related vessels in 

the cumulative case have the greatest potential to impact coastal and marine birds. Oil-spill impacts on 

birds from the total cumulative scenario are expected to be moderate. The increment of oil spills from the 

CPA proposed action to the total cumulative impacts of all potential spills (including those not related to 

the OCS Program) is expected to be negligible because OSRA shows a low probability of OCS Programrelated spill occurrence and shoreline habitat contact. This spill impact is not substantially altered by 

possible tanker spills. Tanker spills may have moderate impacts because of the vast expanse of shoreline 

habitat that would be unlikely to be contacted by any import tanker spill, and this habitat could serve as a 

refuge habitat for bird species from the spill. 

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. The level of impact depends on the frequency, location, season, and quantity of pollutant 

discharges. 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. Such contamination may have lethal or sublethal impacts on 

birds, and it may come from pesticides used in agriculture, excess nutrients in treated sewage discharge, 

and contaminants and motor oil discharged into municipal storm sewers. 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). Although not all species resident in the CPA 

were identified in these studies, those species studied are likely representative for potential impacts to 

birds in general, and impacts would be expected to be similar among these species. Aircraft noise may 

have impacts on coastal and marine birds in the CPA, but quantitative ranges of noise for aircraft and 

military operations specifically measured in the CPA were not identified. 

Nonconsumptive Recreation 

Impacts of nonconsumptive recreation depend on many factors including species and type of 

recreation. Nonconsumptive recreation includes activities that do not harvest wildlife, such as bird 
4-278 Central Planning Area Supplemental EIS 

watching, boating, and nature photography. Quantitative data specific to the Gulf of Mexico on the extent 

of various types of nonconsumptive recreation were not identified. 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). Impacts had to be 

extrapolated from studies of avoidance of human disturbance caused by adaptations, such as flocking for 

predator avoidance. 

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 requirements (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. No 

quantitative data were found on recreational use of coastal areas by non-OCS vessel traffic. 

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). 

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 would 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. 
Description of the Environment and Impact Analysis 4-279 

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 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). Some birds may be constrained to maximize feeding time per 

bird, which then requires a trade off with available vigilance time against predation per bird (i.e., reducing 

protections from predators). Increased flock size may result in food dilution (reduction in food 

abundance) and may result in reduced vigilance time per bird based on group reliance for protection 

(Beauchamp, 2008). In a meta-analysis, increasing group size was important in increasing vigilance time 

per bird, but it explained generally less than 20 percent of the variation in vigilance time per bird 

(Beauchamp, 2008). The degree of vigilance at the flock level will dictate the frequency of unnecessary 

flushing by nonconsumptive recreation users, causing impacts on energy consumption (feeding) that, in a 

popular recreational area, may be far more costly than the necessary natural flushing by predators. 

Maintenance and Use of Navigation Waterways 

Adverse impacts of navigation canals that support many types of vessels 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 required. Periodic maintenance dredging is expected in existing OCS-related 

navigation channels through barrier passes and associated bars. The major use of navigation channels, 

and therefore the driving force behind canal maintenance (including dredging), is by non-OCS-related 

traffic. Insignificant adverse impacts upon wetlands from maintenance dredging are expected because the 

large majority of the material would be disposed upon existing disposal areas. Wetland loss would 

impact waterbirds dependent on wetland habitat for nesting and feeding, and any permanent loss could 

cause irreversible reductions in populations of vulnerable wetland waterbirds. 

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 
4-280 Central Planning Area Supplemental EIS 

mandatory in the United States (Drewitt and Langston, 2008). Such lights may attract birds, especially at 

night or under conditions of low visibility, and birds may fatally collide with the lights. 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 of birds in the United States, at least an order 

of magnitude greater than the combined impacts of 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 

in aquatic birds, based on broad trends in aquatic bird mortality (Newman et al., 2007). A study much 

more narrow in scope notes that 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). The Newman et al. 

study was done before the DWH event and represents a far greater time span (1971-2005), divided into 

5-year intervals as part of the analysis. A USGS database for the entire United States was used for 

analysis. Single oil spills such as the DWH event cannot be compared with the results of Newman et al. 

(2007) because the latter is on a different, much broader time and spatial scale. 

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 because of storms and hurricanes in coastal wetlands and waters expose 

resident birds to chronic physiological stress. Storms and hurricanes are part of the natural environment 

(specifically, climate) of all ecosystems of the Gulf of Mexico, and any adaptations to them will have 

occurred through natural selection of surviving and reproducing organisms over millions of years. 
Description of the Environment and Impact Analysis 4-281 

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). Any loss of habitat from facility construction will be 

permanent, causing possible permanent reductions in population density of some species of birds. Urban 

and suburban expansion will exclude a large variety of wild bird species from their habitat because urban 

and suburban conditions do not generally support such species. Adequate habitat for wild birds has 

greatly declined as human development continues to require more and more land outside of the parks and 

other areas set aside for bird conservation. 

Fisheries Interactions 

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, official communication, 2009; Hale et 

al., 2009; Beerkircher, official 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 (reducing the abundance of the prey base). Commercial, 

and to a lesser extent recreational, fisheries introduce a pressing concern over competition for fish that 

also serve as food for many birds. Given that the commercial fisheries in the GOM are a relatively recent 

phenomenon and that the pressures on commercially sought fish are increasing, birds continue to be 

impacted by this competition and have not been able to adapt as yet. Birds would adapt by becoming 

more efficient in their exploitation of food resources so they could survive and reproduce successfully 

with a prey base of lower abundance. Increased food resources from discarded fishery bycatch may have 

the opposite (positive) impact. 

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. However, 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. 
4-282 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 from proposed action activities 

on birds. However, the impacts from these activities with the CPA proposed action would be minimal 

compared with non-OCS-related activities. This is in part because an oil spill would affect a small 

portion of a bird group and because there would be a low number of pipeline landfalls and the regulations, 

technologies, and mitigation requirements that are in place for dredging and construction activities. 

Impacts of an oil spill on whooping crane or piping plover would be more substantial than for the impact 

of other species, which would have large unaffected populations that could serve as sources for 

recolonizing areas where lethal impacts of oil occur. Piping plover has the advantage that, even if spillrelated mortality occurs, the amount of suitable unscathed habitat in the GOM would likely be substantial 

(on a scale similar to much more abundant species). Factors that have reduced piping plover population 

abundance occurred only on the breeding grounds, well to the north of the Gulf of Mexico. 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 bird-watching 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; therefore, this analysis is 

based on credible scientific information available since the DWH spill and was applied using accepted 

methodologies. Some bird populations in the CPA were almost certainly affected over at least the short 

term by the DWH event. 

The BOEM has considered this assessment and has reexamined the cumulative analysis for birds 

presented in the Multisale EIS, the 2009-2012 Supplemental EIS, and the cited new information. Based 

on this evaluation, conclusions in these analyses on effects to birds remain unchanged in regards to 

routine activities (no potential for significant adverse effects) and accidental spills (no potential for 

significant adverse effects). 

Unavailable information on effects to seabirds from the DWH event (and thus changes to the seabird 

baseline in the affected environment) makes an understanding of the cumulative effects less clear. 

However, as noted above in the description of the affected environment, the endangered piping plover, 

whooping crane, Mississippi sandhill crane, and wood stork were likely unaffected by the DWH event 

(due to their habitat location or migration pattern). For other bird species and populations, BOEM 

concludes that the unavailable information from this event may be relevant to foreseeable significant 

adverse impacts. Relevant data developed through the NRDA process on the status of bird populations 

after the DWH event may take years to acquire and analyze, and impacts from the DWH event may be 
Description of the Environment and Impact Analysis 4-283 

difficult or impossible to discern from other factors. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in this Supplemental EIS, regardless of the cost or resources 

needed. In light of the incomplete or unavailable information, however, BOEM subject-matter experts 

have used available scientifically credible evidence in this analysis and based upon accepted methods and 

approaches. 

Nevertheless, a complete understanding of the missing information, as it relates to cumulative 

impacts, is not essential to a reasoned choice among alternatives for this Supplemental EIS (including the 

No Action and Action Alternatives). As of November 2011, there are 4,503 active leases in the CPA with 

ongoing (or the potential for) exploration, drilling, and production activities. In addition, non-OCS 

energy-related activities will continue to occur in the CPA irrespective of this proposed lease sale (i.e., 

fishing, military activities, and scientific research). The potential for effects from changes to the affected 

environment (post-DWH), routine activities, accidental spills (including low-probability catastrophic 

spills), and cumulative effects remain small whether or not the No Action or an Action alternative is 

chosen under this Supplemental EIS. Compared with the cumulative impacts of other non-OCS energyrelated activities, the incremental contribution of the proposed action remains small. 

Within the CPA, there is a long-standing and well-developed OCS Program. There are no data to 

suggest that activities from the pre-existing OCS Program are significantly impacting seabird populations. 

Therefore, in light of the above analysis on the proposed action and its impacts, the incremental effect of 

the proposed action on seabird populations is not expected to be significant when compared with nonOCS energy-related activities. 

4.1.1.15. Gulf Sturgeon 

The description of the existing condition of the resource and its habitat that follows best describes 

current conditions, as affected by both the series of intense hurricanes (Katrina, Rita, Gustav, and Ike) 

over the last several years and the DWH event. 

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. 

Historically, Gulf sturgeon (Acipenser oxyrinchus desotoi) 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 anadromous—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 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 designated 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 (official 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 
4-284 Central Planning Area Supplemental EIS 

sufficient sampling to determine if the populations along this portion of the Gulf Coast have returned to 

pre-Katrina levels. The Gulf sturgeon (A. oxyrinchus desotoi), a subspecies of the Atlantic sturgeon 

(A. oxyrinchus oxyrhinchus), 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. 

Protected Status 

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 and recovery 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, 

estuarine, and marine habitats. The critical habitat for Gulf sturgeon encompasses approximately 
Description of the Environment and Impact Analysis 4-285 

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. 

Life Cycle 

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 sturgeons 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 near the island passes 

between Horn and Ship islands well as between Horn and Petit Bois islands (Ross et al., 2001). Gulf 

sturgeon from the Choctawhatchee, Yellow, and Apalachicola Rivers has 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, Florida (Wooley and Crateau, 1985). In Florida, Gulf sturgeons are still found in the Escambia, 

Yellow, Black water, 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). 
4-286 Central Planning Area Supplemental EIS 

Stocks and Distribution 

Based on the latest population estimates from the Pearl River (Rogillio, official communication, 

2007; Kirk official 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. 

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, official 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, sturgeons 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 sturgeons 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 
Description of the Environment and Impact Analysis 4-287 

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 

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 et 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, official communication, 

1997). 

Sturgeons are bottom suction feeders that have ventrally located, highly extrudable 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). 

According to Parauka (official communication, 2008), studies 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. Earlier studies noted above verified only 

coastal movements and moderate offshore usage possibly due to the limitation of tagging and tracking 

equipment. A more recent study (Fox et al., 2002a) tracked and confirmed adult sturgeon that 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 the Fox et al. (2002b) 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 conditions resulting from diverse habitats and the dynamic nature of main stems of 

watersheds that would otherwise reduce survival rates of juveniles. 

Threats to Gulf Sturgeon 

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 that occurred mostly after 1950 restricted access to 

historic spawning areas (Wooley and Crateau, 1985), which exacerbated 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, and physiological alterations in other fish (White et al., 1983). In addition, 

Gulf sturgeons 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, 
4-288 Central Planning Area Supplemental EIS 

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, clearing/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 Impacts 

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 (2008) did initially 

displace some of the Gulf sturgeon in the Louisiana/Mississippi area, much like what happened in Florida 

during 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. The 2008 sampling effort in the Pascagoula river system and estuary was 

insufficient to conclude if any change in composition or spawning in that year (Slack, official 

communication, 2008). More recent information from the Pascagoula Sturgeon Team from the 

University of Southern Mississippi Gulf Coast Research Laboratory reported that five Ggulf sturgeon 

were caught in 2010 and ranged in size from 570 to 1,500 mm (22 to 59 in) total length, which may be 

indicative of recovery under post Katrina conditions (Havrylkoff, official communication, 2010). While a 

complete assessment of habitat damage due to hurricanes has not been fully executed for Gulf sturgeon, 

based on recent sampling results, the effects are hypothesized to be temporary (Parauka, official 

communication, 2007a). Todd Slack noted that Hurricanes Gustav and Ike did initially displaced some of 

the Gulf Sturgeon in the Louisiana/Mississippi area much like what happened in Florida during Katrina 

(Slack, official communication 2008). More recent information from the Pascagoula Sturgeon Team 

from the University of Southern Mississippi Ocean Springs Research Laboratory (Havrylkoff, official 

communication, 2010) reported that five Gulf sturgeon were caught in 2010 and ranged in size from 

570 to 1,500 mm (22 to 59 in) total length, which may be indicative of recovery under post-Katrina 

conditions. 

The areas most impacted from tropical cyclonic events 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 Atlantic 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. However, spreading and dilution should mitigate any threat to sturgeon 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 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 (U.S. Dept. 

of the Army, COE, 2005a). 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 

Panama City, Florida, after Hurricane Ivan (2004) 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, and 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. 
Description of the Environment and Impact Analysis 4-289 

Deepwater Horizon Event 

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. Comparisons of oil-spill overlay maps 

with the Gulf sturgeon critical habitat maps indicate that all but the most eastern regions of the sturgeon 

habitat had been exposed to oil (USDOC, NOAA, 2010e). 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, 2010e). 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, 2010e) 

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. Based on the publicly available information 

found in the OSAT and OSAT-2 reports (OSAT, 2010; OSAT-2, 2011), it was noted that, after August 

2010, the more toxic oil components were limited to an area within 3 km (~2 mi) of the wellhead from 

this area; both water column and sediment samples did not reach USEPA’s exceedances for aquatic life 

benchmarks (including PAH’s) (OSAT, 2010). The most current shoreline oiling data (USDOC, NOAA, 

2011b) is not delineated by shoreline miles and qualitatively (mapping graphics) indicates light to no 

remnant oil in the Gulf sturgeon critical habitat. The very light remnant oil observed is only in a small 

area west of the Rigolets Pass in Louisiana. From the Rigolets Pass in Louisiana to Panama City, Florida, 

there is no remnant oil indicated in Gulf sturgeon critical habitat or nearshore waters. As NRDA data are 

analyzed and released, along with independent study data, a more refined assessment of the existing 

conditions of this resource and its habitat will be forthcoming. 

Endangered Species Act Consultation 

After the DWH event, BOEM reinitiated ESA Section 7 consultation with NMFS and FWS. The 

NMFS responded with a letter to BOEM on September 24, 2010; FWS responded with a letter on 

September 27, 2010. Consultation is ongoing, with BOEM serving as lead agency and with BSEE 

involvement. The agencies are working jointly to develop an interim coordination program while 

consultation remains ongoing. The existing consultations will remain in effect until the reinitiated 

consultations are completed. The existing consultation recognizes that BOEM- and BSEE-required 

mitigations and other reasonable and prudent measures should reduce the likelihood of impacts from 

BOEM- and BSEE-authorized activities (Chapter 5). 

As noted above, BOEM acknowledges that there remains incomplete or unavailable information on 

Gulf sturgeon, including potential impacts from the DWH event (and thus changes to the Gulf sturgeon 

baseline in the affected environment). This makes an understanding of the affected environment and 

impacts from the proposed action less clear. Here, BOEM concludes that the unavailable information 

from these events may be relevant to foreseeable significant adverse impacts to Gulf sturgeon. The 

BOEM believes that this incomplete or unavailable information regarding effects of the DWH event on 

Gulf sturgeon may be essential to a reasoned choice among alternatives. Relevant data on the status of 

Gulf sturgeon populations after the DWH event may take years to acquire and analyze, and impacts from 

the DWH event may be difficult or impossible to discern from other factors. Therefore, it is not possible 

for BOEM to obtain this information within the timeframe contemplated in this Supplemental EIS, 

regardless of the cost or resources needed. In light of the incomplete or unavailable information, BOEM 

subject-matter experts have used available scientifically credible evidence in this analysis (including data 

on related fish species such as the Caspian Sea sturgeon) and applied this information based upon 

accepted scientific methods and approaches. 
4-290 Central Planning Area Supplemental EIS 

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. 

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 from platforms and onshore 

infrastructure, 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. 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); although 

critical habitat may be impacted directly or indirectly, such impacts are expected to be negligible due to 

the distance of Gulf sturgeon habitat and life cycles from most activities related to the proposed action. 

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). The produced waters associated with OCS activities have various chemical constituents that have 

varying potential for concern to the Gulf sturgeon. Produced water and drilling muds are regulated by 

NPDES permits, which mandate maximum contaminant levels within the discharges. Due to these 

restrictions and rapid dilution within offshore waters, significant impacts are not expected. 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 discharges 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) to benthic sediments. 

Most Gulf sturgeon would not be expected to be encountered on the OCS in the area of produced 

discharges, although it has not been definitively studied. 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 including muscle atrophy, abnormality of gonad, sperm and egg developmental issues, 

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 affects their ability to produce adverse effects in the marine 
Description of the Environment and Impact Analysis 4-291 

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). The Neff (2002) study noted that copper and cadmium were typically the metals 

identified in GOM produced water. Any adverse effects of these metals, if they occur at all, are likely to 

be highly localized. 

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 (Neff et al., 1987). 

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 that 

impacts reproduction and osmoregulation, immune system suppression, inhibition of the olfactory system, 

inhibition of the nervous system that interferes 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). 

However, offshore discharges of drilling muds and produced waters are expected to dilute to 

background levels within 1,000 m (3,281 ft) (CSA 1997b). These structures would be located well 

offshore of the designated critical habitat. Sturgeon is 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 Program-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. On average, 9 percent of traffic using 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 CPA proposed action and the OCS Program (Table 3-4 

of this Supplemental EIS and Table 4-6 of the Multisale EIS), the proposed action is expected to 
4-292 Central Planning Area Supplemental EIS 

contribute 3-4 percent of the total OCS Program usage of navigation channels. Therefore, the proposed 

action would contribute 0.2-0.4 percent to the total commercial traffic using these navigation channels. 

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, away from OCS platforms in Federal waters. Most 

OCS platform removal activity occurs from late spring to fall which coincides with the inland migration 

of the Gulf Sturgeon to their natal rivers where they overwinter thus excluding them from the deeper 

waters where OCS platforms are being removed. 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 could impact the nearshore 

critical habitat of 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 to 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. 

All of the gas production and most of the oil production from the CPA proposed action is expected to 

be mingled in offshore pipelines with other OCS production at sea before going ashore, and most would 

use 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. 

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 the vessels are 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. 
Description of the Environment and Impact Analysis 4-293 

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 primarily 

from oil spills, drilling, and degradation of estuarine and marine water quality by nonpoint runoff from 

estuarine OCS-related facilities. Potential impacts to fish resources from a low-probability catastrophic 

event are also discussed in Appendix B. 

Proposed Action Analysis 

Potential accidental impacts on Gulf sturgeon and the designated critical habitat may occur from oil 

spills. The dilution and low toxicity of this pollution is expected to result in negligible impacts on Gulf 

sturgeon as a result of the CPA proposed action due to the distance these spills would be expected to 

remain from Gulf sturgeon critical habitat. 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). 

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, including 

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 its long lifespan, its extended residence in riverine and estuarine habitats, and its benthic feeding 

habitats. These factors 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. 

Studies specifically involving Gulf sturgeon and PAH’s were not found in the current literature, 

although a past study found that Gulf sturgeon tissue samples contain concentrations of PAH’s 

(Batemann and Brim, 1994). The PAH toxicity to fish in general (shortnose sturgeon, salmonids) varies 

substantially, although conclusions on impacts of PAH’s on fish are often generalized due to the difficulty 

in testing any specific chemical (Berg, 2006). 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). The reproductive problems noted above relates 

to the effect of oil and its components on the less mobile eggs, larvae, and juvenile sturgeon that do not 

have fully developed physiological systems to deal with the oil components, especially PAH. In general 

specific reproductive abnormalities that have been seen in Gulf sturgeon as a result of pollution from oil 

components are abnormal gonad formation, sperm and egg developmental issues, and disruption of 

hormone production (USDOI, FWS, and USDOC, NMFS, 2009). In Berg’s (2006) “Review of 

Contaminant Impacts on the Gulf of Mexico Sturgeon” he noted some sturgeon studies from the Caspian 

Sea that indicate unlike salmonids, sturgeon actively avoided areas contaminated with oil. 

There is also speculation that exposure to PAH’s may suppress the immune system. 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 
4-294 Central Planning Area Supplemental EIS 

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 may also 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. Most activities related to the proposed action would occur in Federal waters; however, 

critical habitat may be impacted directly or indirectly. Gulf sturgeons are primarily benthic feeders and 

inhabit mostly nearshore, coastal water environments of moderate depth, except during the riverine 

spawning period. Based on recent studies (Parauka, official 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 that for the adjoining coastal area and diminishes even 

further as one moves upstream. Spilled oil is unlikely to impact eggs, juvenile, and adult Gulf sturgeon 

when they are in the inland during the 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. 

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 use, compared with an 

accidental event resulting from the proposed action. 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. Based on OSAT 

Reports (OSAT, 2010 and OSAT -2, 2011) the treated oil associated with the DWH event that reached 

coastal waters and beaches did not exceed USEPA’s benchmarks for aquatic life in either sediments or 

water. In addition the dispersant emulsified the oil, which encouraged evaporation, dilution and 

biodegradation of toxic components including PAH’s. Contamination was limited to within 3km (~2 mi) 

of the wellhead well away from the Gulf sturgeon critical habitat. The dispersed oil was rendered into a 

cloud-like mass within the water column which was readily available for biodegradation. 

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 
Description of the Environment and Impact Analysis 4-295 

the DWH event on Gulf sturgeon and their coastal habitat. The likelihood of another catastrophic spill 

event of sufficient size and duration to impact coastal environments, however, remains exceedingly low. 

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 

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 from an offshore spill. 

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. Even in a catastrophic spill, the 

proximity, type of oil, weather conditions, as well as the amount and location (distance off shore and 

water depth) of the dispersant treatment, may contribute to the severity of the spill impact to the sturgeon 

and its habitat. Currently reduced toxicity of PAH in both the nearshore and offshore water and 

sediments have been reported in the OSAT report (OSAT, 2010). These conclusions, coupled with the 

findings of the OSAT-2 report noting large reductions in PAH toxicity in the beach sediments as well as 

the continual degradation of PAH in the tidal zone sediment (OSAT -2, 2011), would indicate the toxicity 

levels are not likely to interfere with Gulf sturgeon or their critical habitat. In addition the dispersant 

emulsified the oil which encouraged evaporation, dilution and biodegradation of toxic components 

including PAH’s. Contamination was limited to within 3km (~2 mi) of the wellhead well away from the 

Gulf sturgeon critical habitat (OSAT, 2010). The dispersed oil was rendered into a cloud-like mass 

within the water column which was readily available for biodegradation 

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. 

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. 

This cumulative analysis summary considers the impacts of all past, present, and reasonably 

foreseeable future activities, plus the contribution of the proposed action, that may 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, sea level 

rise, 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 (locks and dams, controlled water releases, floodway operations, diversions), as well as natural 

phenomena. Specific types of impact-producing factors considered in this cumulative analysis include 

coastal and marine environmental degradation by nonpoint source runoff including pesticides and 

herbicides as well as incidental introduction of pharmaceuticals, produced-water discharges, pipeline 
4-296 Central Planning Area Supplemental EIS 

emplacements, oil spills, dredge-and-fill operations, natural catastrophes that alter or destroy habitat, 

commercial fishing techniques that result in sturgeon bycatch, and other anthropogenic factors (including 

river damming and flood-control projects). 

Vessel traffic would generally only pose a risk to Gulf sturgeon when vessels are 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 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. As a result of the DWH event, subsurface submerged oil 

mats were found (OSAT, 2010) in some subtidal nearshore waters. Depending on location and depth and 

toxicity of these submerged oil mats, Gulf sturgeon may potentially come in contact or ingest portions of 

these submerged oil mats while foraging. The make up of the submerged oil mats ranged from 83 to 

90 percent sand, with the weathered oil component ranging from 9 to 17 percent (OSAT-2, 2011). The 

degree of weathering, biodegradation, and high energy of the environment would all contribute to the 

lower toxicity of these submerged oil mats. As found in other beach sediments along the coast, toxin 

levels should not exceed USEPA benchmarks for aquatic life (OSAT, 2010). Public data are not readily 

available at this time. In order to determine the toxicity of these submerged oil mats and therefore the 

threat to sturgeon, the current OSAT and OSAT-2 (OSAT, 2010; OSAT-2, 2011) results are utilized to 

hypothesize the potential for permanent impact to the sturgeon or its critical habitat. These submerged oil 

mats are normally found in very shallow water near beaches or shallow shorelines, which would not 

normally be considered as preferred habitat for Gulf Sturgeon. 

However, several factors influence the probability of spilled oil contacting 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 to 

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 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 
Description of the Environment and Impact Analysis 4-297 

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. There are currently no 

official publicly available NRDA data regarding the quantity, toxicity, or areal extent of surface or 

subsurface oil reaching sturgeon critical habitat. 

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, effect it has had on the benthic forage base of the 

Gulf sturgeon. Based on current data from the SCAT observations (USDOC, NOAA, 2011b), remnant 

light oiling is still being observed on the Gulfward fringe of the Gulf sturgeon’s critical habitat, which is 

located near the Gulf Islands National Seashore (Cat, Ship, Horn and Petit Bois Islands) along the 

Mississippi Coast. No oil was observed in Gulf sturgeon’s critical habitat eastward of the Alabama/ 

Florida border as of September 28, 2011 (USDOC, NOAA, 2011b). The last surface oil was reported 

after August 3, 2010, and the Operational Science Advisory Team did flyovers and sampled sediment and 

water in both the nearshore and offshore environment (OSAT, 2010). The resulting OSAT report 

concluded from those samples that there were no exceedances in either water or sediment of the any of 

USEPA’s aquatic life benchmark including PAH’s in these nearshore waters and that there were no 

USEPA exceedances for the aquatic life benchmarks including PAH’s in sediment beyond 3 km (~2 mi) 

of the wellhead that were consistent with MC 252 oil (DWH event) (OSAT, 2010). This result indicates 

that portions of the Gulf sturgeon’s critical habitat that were potentially exposed to oiling would not 

remain toxic to life essential components of the sturgeon. What is not known is the condition of the oil 

and how much, if any, 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 and would be 

emulsified and separated into droplets within the water column where it is readily available for 

biodegradation. 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. These activities along with other non-OCS 

activities, such as riverine sand and gravel operations and construction of emergency berms for the 

prevention of beach and marsh oiling (DWH event), indirectly impact Gulf sturgeon through the loss or 

disturbance of inland spawning and nearshore nursery habitat. 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 for 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 
4-298 Central Planning Area Supplemental EIS 

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 sturgeon life-history time periods (i.e., spawning, 

migration, staging, and feeding), as this is 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, BOEM’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, official 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 may destroy or temporarily impair Gulf sturgeon habitat. Natural catastrophes 

including storms, floods, droughts, and hurricanes can result in substantial habitat damage. 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 caused by Hurricane Ivan (2004). This lack of habitat caused Gulf sturgeon to 

temporarily abandon this feeding area. Parauka (official communication, 2007a and 2008) noted an 

absence of Gulf sturgeon following Hurricanes Katrina and Rita (2005) 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. In an interview after Hurricane Gustav (2008), Parauka (official 

communication 2008) explained that Gulf sturgeon were not only returning to Santa Rosa Sound but were 

migrating between Mississippi Sound and Santa Rosa Sound. 

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 

Hurricanes Katrina (2005), Rita (2005), Gustav (2008), and Ike (2008), 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, official 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 (official communication, 2007a and 2008) 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, official 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 
Description of the Environment and Impact Analysis 4-299 

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 (official 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 (official 

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 Panama City, Florida, in the 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, official 

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. 

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 
4-300 Central Planning Area Supplemental EIS 

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. 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, industrial and urban land use. An 

example of impacts from an industrial spill is the fish kill that was a result of the Bogalusa Paperboard 

Mill, which discharged a byproduct of the papermaking process into the Pearl River during a plant 

malfunction in August 2011. 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, official 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 

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 little public 

data to ascertain the short-term and long-term effects of the DWH event on Gulf sturgeon or their critical 

habitat. Critical habitat was exposed to oil. 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. However based on the publically available information found in the 

OSAT and OSAT-2 reports (OSAT, 2010; OSAT-2, 2011) it was noted that after August 2010 the more 

toxic oil components were limited to an area within 3 km (~2 mi) of the wellhead; from this area, both 

water column and sediment samples did not reach USEPA’s exceedances for aquatic life benchmarks 

(including PAH’s) (OSAT, 2010). In addition, the oil underwent evaporation and was quickly emulsified 
Description of the Environment and Impact Analysis 4-301 

and diluted at the wellhead by dispersants, which made it readily available for biodegradation. 

Biodegradation further reduces the toxicity of the oil before it reaches any critical habitat. 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. 

As noted above, BOEM acknowledges that there remains incomplete or unavailable information on 

Gulf sturgeon, including potential impacts from the DWH event (and thus changes to the Gulf sturgeon 

baseline in the affected environment). This makes an understanding of the affected environment and 

cumulative impacts less clear. Here, BOEM concludes that the unavailable information from these events 

may be relevant to foreseeable significant adverse impacts to Gulf sturgeon. Relevant data on the status 

of Gulf sturgeon populations after the DWH event may take years to acquire and analyze, and impacts 

from the DWH event may be difficult or impossible to discern from other factors. Therefore, it is not 

possible for BOEM to obtain this information within the timeframe contemplated in this Supplemental 

EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable information, 

BOEM subject-matter experts have used available scientifically credible evidence in this analysis 

(including data on related fish species such as the Caspian Sea sturgeon) and applied this information 

based upon accepted scientific methods and approaches. Nevertheless, BOEM believes that this 

incomplete or unavailable information regarding effects of the DWH event on Gulf sturgeon is likely not 

essential to a reasoned choice among alternatives, when considering cumulative impacts. Non-OCS 

Program-related impacts are seen as the primary cumulative impacts on this resource, compared with the 

proposed action, even in light of incomplete or unavailable information. 

The incremental contribution of the CPA proposed action to the cumulative impacts on Gulf sturgeon 

is negligible. This is because the effect of contact between sale-specific oil spills and Gulf sturgeon is 

expected to be sublethal and usually lasts less than 1 month, and regulations and mitigations decrease 

impacts from routine events. Other non-OCS Program-related activities, including storms and 

anthropogenic factors on habitat, are expected to result in more cumulative impacts to this species. 

4.1.1.16. Fish Resources and Essential Fish Habitat 

The BOEM 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 Chapter 4.5.10 of 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 related to the proposed action 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 gas blowout would have a negligible 

effect on Gulf of Mexico fish resources because it would be expected to cause only localized sediment 

disturbance but no release of oil. If a subsurface oil blowout or spill due to the CPA proposed action were 
4-302 Central Planning Area Supplemental EIS 

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 bycatch 

associated with fisheries, and to a lesser degree, coastal petroleum spills and coastal pipeline trenching. 

At the estimated level of cumulative impact, the resultant influence of the proposed action on fish 

resources and EFH is not expected to be 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. The EFH regulations (50 CFR 600) require NMFS to describe and identify habitats determined to 

be EFH for each life stage of each managed species. A large portion of the GOM is designated EFH 

because of the number of managed species and their different life-history stages and the variety of habtats 

in the GOM. 

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 (official communication, 2009) estimated revenue losses from 

Hurricanes Gustav and Ike on Louisiana fisheries and aquaculture sectors in excess of $98 million. The 
Description of the Environment and Impact Analysis 4-303 

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. 

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. The addition of COREXIT 9500 at the seafloor spill site and the 

surface resulted in the dispersion of oil in the water column. Although COREXIT 9500 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. The USEPA and NOAA have proposed a monitoring program that will 

assess the toxicity of 20:1 oil/COREXIT to Atlantic silversides. The information from the monitoring 

program and specific impacts of dispersants to fish in the CPA is currently unknown. 

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., 2011a) revealed that a large amount of methane was 

released the during the DWH event and, based upon the methane and oxygen distributions measured at 
4-304 Central Planning Area Supplemental EIS 

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 in the CPA have changed or will change as a result of the DWH event is 

unknown at this time and studies are ongoing. Based on existing research, adult fish have been observed 

to actively avoid contact with oil in the water column (Wannamaker and Rice, 2000). Nevertheless, 

information on effects of the DWH event on fisheries is unavailable or incomplete at this time and may 

take years to obtain and analyze. This information will be developed through the NRDA process, is not 

expected to be complete or released to the public for years, and will certainly not be available during the 

timeline of this Supplemental EIS. Regardless of cost, it is not within BOEM’s ability to obtain this 

information from the ongoing NRDA process. This information may be relevant to reasonably 

foreseeable significant impacts, and BOEM cannot definitively state at the present time whether this 

information may be essential to a reasoned choice among alternatives. The BOEM subject-matter 

experts, however, have used the scientifically credible information that is available and applied it using 

accepted scientific methodologies. 

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. A more detailed description of the EFH program in the Gulf of Mexico is 

in Chapter 3.2.8.2 of the Multisale EIS. 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. 

The EFH is defined as the waters and substrate necessary to fish for spawning, breeding, feeding, and 

growth to maturity. The Gulf of Mexico waters out to 100 fathoms (600 m; 183 ft) have EFH described 

and identified for managed species. These EFH’s, including the status of the affected environment and 

impacts from DWH, are discussed in various sections of the Multisale EIS and this Supplemental EIS: 

the water column (Chapter 3.1.2 of the Multisale EIS and Chapter 4.1.1.2.1 of this Supplemental EIS); 

wetlands (Chapter 3.2.1 of the Multisale EIS and Chapter 4.1.1.4.1 of this Supplemental EIS); 

submerged vegetation (Chapter 3.2.1 of the Multisale EIS and Chapter 4.1.1.5.1 of this Supplemental 

EIS); live bottoms (Chapter 4.1.1.6.1.1 and 4.1.1.1.6.2.1 of this Supplemental EIS); topographic features 

(Chapter 3.2.2 of the Multisale EIS and Chapter 4.1.1.7.1 of this Supplemental EIS); Sargassum

(Chapter 4.1.1.8.1 of this Supplemental EIS); chemosynthetic and nonchemosynthetic communities 

(Chapter 3.2.2 of the Multisale EIS and Chapters 4.1.1.9.1 and 4.1.1.10.1 of this Supplemental EIS); and 

soft bottoms (Chapter 4.1.1.22.1 of this Supplemental EIS). 

A new EFH consultation has been initiated between BOEM’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. 
Description of the Environment and Impact Analysis 4-305 

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). 

Chapters 4.2.1.1.3.2 and 4.2.1.1.3.3 of the Multisale EIS and Chapters 4.1.1.4.2 and 4.1.1.5.2 of this 

Supplemental EIS consider the effects from the proposed action on wetlands and submerged vegetation. 

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. Due to the resuspension of bottom sediments associated with dredging, fish would likely avoid the 

area during the event and would temporarily relocate to another area; these fish typically return to the area 

once the event has ceased, and EFH would only be temporarily affected but not lost. Recovery of fish 

resources or EFH can occur from most, but not all, of the potential coastal environmental degradation. 

Most fish populations, if left undisturbed, would regenerate quickly because impacts to the habitat would 

generally be temporary; fish tend to avoid areas of impact (thus reducing mortality effects) and most are 

prolific reproducers. The loss of wetlands as EFH could be permanent. In the case of wetlands that may 

be permanently lost, for example, this would likely be converted to another form of EFH, such as 
4-306 Central Planning Area Supplemental EIS 

conversion to open water or submerged aquatic habitat. At this expected low 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 proposed action could potentially impact the marine environment through activities such as 

discharges, bottom disturbance, and structure removal. 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 and would be limited in geographic scope, and 

therefore not rise to any population-level impacts across the CPA or Gulf of Mexico generally. 

The projected length of offshore 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 avoid areas of excessive turbidity 

because the population’s typical behavior is to avoid any adverse conditions in water quality. At the 

expected level of impact, the resultant influence of the proposed action 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). 

Therefore, it appears that methylmercury concentrations near OCS activities are not significantly different 

from background levels in the Gulf of Mexico. 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 

not 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. Most fish populations, if left undisturbed, regenerate 

quickly because impacts to the habitat would generally be temporary; fish tend to avoid areas of impact 

(thus reducing mortality effects) and most are prolific reproducers. Most fish populations, if left 
Description of the Environment and Impact Analysis 4-307 

undisturbed, would regenerate quickly given the absence of catastrophic events. Offshore live bottoms 

and topographic features are not expected to be impacted. 

Offshore discharges are regulated by the U.S. Environmental Protection Agency’s NPDES permits. 

At the expected low level of effect, the resultant influence on fish resources or EFH would be negligible 

and indistinguishable from natural population variations. 

In addition, the Topographic Features and Live Bottom Stipulations (discussed in Chapters 2.2.2 and 

2.3.1.3.1 of the Multisale EIS, Chapter 2.2.1.3 of the 2009-2012 Supplemental EIS, and Chapter

2.3.1.3.1 and 2.3.1.3.2 of this Supplemental EIS) may be applied to the proposed action. 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. The lease stipulation and NTL 2009-G39 protect sensitive 

EFH from both routine and accidental impacts that may occur during petroleum production. This 

stipulation and NTL, among other things, focus OCS activities at specified distances from the topographic 

features, a sensitive EFH, thereby increasing the distance between the features and their associated fish 

populations. 

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 BOEM 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 because impacts to the habitat would generally be temporary; fish tend to avoid areas of impact 

(thus reducing mortality effects) and most fish species are prolific reproducers. Recovery from the loss of 

wetlands habitat would probably not occur, but it would likely result in conversion of the lost wetland 

habitats into open water or mudflats, which may qualify as other forms of EFH. 

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 expected to cause a nondetectable 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 that would not deleteriously affect fish resources or EFH. This is because of 
4-308 Central Planning Area Supplemental EIS 

regulations, mitigations, and practices that reduce the undesirable effects on coastal habitats from 

dredging and other construction activities. 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. 

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. These previous documents are mentioned because 

they provide important background information on fisheries species. Accidental events that could impact 

fish resources and EFH include blowouts and oil or chemical spills. 

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 because they would generally be limited to vessel and shore-based storage tanks with 

limited capacity. 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 due to the smaller size of these spills generally, volatilization, and quicker 

response times for cleanup activities. A total of 46-102 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 
Description of the Environment and Impact Analysis 4-309 

of Mexico fisheries. These species are highly migratory and would, based on typical observed behavior, 

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 for those fish that happen to 

be in the area at the time of the blowout. 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. Other fish not in the immediate area at the time of the blowout would be expected to 

avoid the impacted area, based on their typical observed behavior to avoid adverse conditions. 

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. 

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 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 and west (closer to the spill) of the sampling station. 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. This depends on the timing of the spawn and the area 

influenced by the spill. 

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), 

incorporation of hydrocarbons in organisms causing tainting or accumulation in the food chain, and 

changes in biological habitat (Moore and Dwyer, 1974). 

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 2002). 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 
4-310 Central Planning Area Supplemental EIS 

related to the water temperature and type of bacteria involved. Physical toxicity of oil to fishes depends, 

at least in part, 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 were observed in Louisiana (Bourgeois, official 

communication, 2010a), Mississippi (Devers, official communication, 2010), and Alabama (Denson, 

official 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. 

More recently, as a result of a petition by the Center for Biological Diversity, NMFS announced a 90-day 

finding for a petition to list Atlantic bluefin tuna as endangered or threatened under the Endangered 

Species Act and to designate critical habitat concurrently with the listing (Federal Register, 2010f). On 

May 27, 2011, NOAA announced that, at this time, the Atlantic bluefin tuna does not warrant species 

protection under the ESA (USDOC, NOAA, 2011e). The NOAA has, however, committed to review this 

decision in early 2013 based on a Stock Assessment to be completed in 2012 and pending more 

information on the DWH event (Federal Register, 2011b). 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 Atlantic blue fin tuna. 

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 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., 2011a) 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 effect of petroleum spills on fish resources as a result of the proposed action is expected to cause 

a minimal decrease in most 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 (Chapter 4.4.10 of the Multisale EIS). 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, where fish populations are most concentrated, and this probability is 

generally low. Also, much of the coastal northern Gulf of Mexico is a moderate- to high-energy 
Description of the Environment and Impact Analysis 4-311 

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. 

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 the most common spill events would be small in 

scale and localized; therefore, they would affect generally only a small potion of fish 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. Although there remains incomplete or unavailable information on the impacts of the 

DWH event on fish resources and EFH, the Bureau of Ocean Energy Management has determined that it 

is impossible for BOEM to obtain this information, regardless of cost, within the timeframe of this NEPA 

analysis. This information is being developed through the NRDA process, data are still incoming and 

have not been made publicly available, and it is expected to be years before the information is available. 

In addition, as described above, where this incomplete information is relevant to reasonably foreseeable 

impacts, what scientifically credible information is available was used in its stead and applied using 

accepted scientific methodologies. Nevertheless, BOEM believes that this information is not essential to 

a reasoned choice among alternatives with regard to an accidental event analysis. The likely size of an 

accidental event resulting from the proposed action would be small and unlikely to impact coastal and 

estuarine habitats where juvenile and larval stages of fish resources are found, and adult fish tend to avoid 

adverse water conditions (Wannamaker and Rice, 2000). 

4.1.1.16.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts on fish resources and EFH 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 primarily from the population increase, and associated development relating 

to this 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. 
4-312 Central Planning Area Supplemental EIS 

In comparison to the large area of wetland loss to commercial and recreational (such as marinas and 

camps) 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 based on impacts from these non-OCS-related impacts 

described above. Localized, minor degradation of coastal water quality is expected from the proposed 

action within the immediate vicinity of the waterbodies proximate to the 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 and Live Bottom Stipulations 

(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 by 

focusing OCS activities at specified distances from the live-bottom features, thereby increasing the 

distance between these features and routine activities and potential accidental event. In the case of a spill, 

this distance would reduce the potential for contact with the features, as the released oil would be 

expected to rise to the surface and disperse in the water. The OCS Program activities impacting livebottom communities include bottom-disturbing 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 more prevalent natural factors and non-OCS sources that can affect live bottoms 

and because the OCS factors that can affect live bottoms have been mitigated by BOEM, the OCS factors 

are anticipated to be a small portion of impacts to live bottom features in the CPA. Therefore, the 

incremental impact of the proposed action would be small in comparison. 

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). However, this effect would be limited to the immediate 

area of the structure removal and would not rise to the level of a population impact. 
Description of the Environment and Impact Analysis 4-313 

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 (Chapter 

4.4.10 of the Multisale EIS). 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-OCSrelated 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 

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 proposed 

action’s incremental cumulative impact on EFH and fish populations in the CPA is not anticipated to be 

significantly 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. Impacts on fish populations from these events are expected to be undetectable 

because they would be localized and temporary in nature. 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, again because they would be localized and temporary and would not rise to 

population level impacts. 

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). Although in shallower 

waters pipeline installation may involve trenching, in waters over 200 ft (61 m), pipelines are typically 

laid on the surface without resorting to trenching, thereby limiting suspension of sediments in waters over 

200 ft (61 m). 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 and suspension of sediments (e.g., currents, tidal influences, and hurricanes) on the 

seafloor is very small, the effect on fish resources from pipeline trenching is expected to be minimal. 
4-314 Central Planning Area Supplemental EIS 

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 at the wellhead 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, 

but there is no documentation that this mercury comes from OCS sources compared with the many other 

sources of mercury in these waters. 

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, bycatch 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 proposed stipulations 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 non-OCS-related impacts and natural population variability. 

As noted above (in Chapter 4.1.1.16.1, Affected Environment), most of the Gulf of Mexico is 

designated as EFH and encompasses many different types of habitats and resources described in this 

Supplemental EIS. The extent of impacts from the DWH event to EFH and fish resources remains 

unclear at this time. This information is being developed through the NRDA process, data are still 

incoming and have not been made publicly available, and it is expected to be years before the information 

is available. In addition, as described above, where this incomplete information is relevant to reasonably 

foreseeable impacts, what scientifically credible information is available was used in its stead and applied 

using accepted scientific methodologies. Although it may be relevant to reasonably foreseeable adverse 

impacts, this incomplete or unavailable information is not essential to a reasoned choice among 

alternatives. Compared with other impacting factors on EFH and fish resources, including those related 

to coastal and marine degradation, wetland loss, vessel traffic, and coastal development, the proposed 

action is not likely to result in an incremental increase in impacts to EFH and fish resources, regardless of 

any lingering impacts from the DWH event. 

4.1.1.17. Commercial Fishing 

The BOEM 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 
Description of the Environment and Impact Analysis 4-315 

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 non-OCS energyrelated 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 and other pressures 

affecting the resource. 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 GMFMC provides the 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 (official 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. 

The DWH event 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, 2010j). 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, 2011f). 
4-316 Central Planning Area Supplemental EIS 

As a result of the DWH event and the closures related to it, NMFS’ (USDOC, NMFS, 2011d) 

statistics released for 2010 show decreased landings of in most, although not all, commercially important 

species. A total of 1.283 billion pounds of finfish and shellfish combined were landed from Gulf Coast 

States in 2010, an 18.5 percent drop in harvest from 2009 (1.574 billion pounds) but a 0.6 percent 

increase over 2008 total landings (1.278 billion pounds). All of the Gulf Coast States showed decreased 

2010 total landings compared with 2009 total landings. Texas total landings dropped from 102.7 million 

pounds in 2009 to 89.9 million pounds in 2010 (12.5%). Louisiana landings dropped from 1.15 billion 

pounds in 2009 to 1.0 billion pounds on 2010 (13%). Mississippi landings dropped from 230.3 million 

pounds in 2009 to 111.2 million pounds in 2010 (52%). Alabama landings dropped from 28.8 million 

pounds in 2009 to 14.5 million pounds in 2010 (50%). West Florida landings dropped from 65.3 million 

pounds in 2009 to 63.5 million pounds in 2010 (2.8%). The losses were not even in all states nor were 

they even in all species fished. Some species showed decreased landings and some showed increased 

landings over previous years (USDOC, NMFS, 2011d). 

The Gulf menhaden harvest, the largest cash crop in the Gulf of Mexico, which is limited to the States 

of Louisiana, Mississippi, Alabama, and the West Coast of Florida, and most predominant in Louisiana 

and Mississippi was 0.97 billion pounds, down approximately 30 percent from the 2009 harvest of 

1.3 billion pounds but up approximately 4 percent from the 2008 harvest of 0.93 billion pounds. Bluefin 

tuna harvest in Gulf waters, limited to the West Coast of Florida and Louisiana, increased from 

17.4 million tons in 2009 to 20.5 million tons in 2010. The 2010 landings data of some species decreased 

over 2009 data such as king and cero mackerel (-11%). Landings of other species such as black drum 

(+1%) remained nearly static, and landings of some species such as red snapper increased (28%) over the 

2009 landings data (USDOC, NMFS, 2011d). The resulting impacts for the 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). On May 27, 2011, NOAA announced that, at this time, the Atlantic bluefin tuna does 

not warrant species protection under the ESA (USDOC, NOAA, 2011e). The NOAA has, however 

committed to review this decision in early 2013 based on a Stock Assessment to be completed in 2012 

and pending more information on the DWH event (Federal Register, 2011b). 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 Atlantic blue fin tuna. A 

catastrophic spill, such as the DWH event, during the spring season may cause a negative effect on future 

generations of 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. 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. 

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. In these various kills between August 24 and September 24, 2010, 

most of the species that died were menhaden (Bourgeois, official communication, 2010a; Blanchet, 

official communication, 2010).. 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 oxygen depletion is a somewhat common occurrence in the Gulf, 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 
Description of the Environment and Impact Analysis 4-317 

some fish kills in Mobile Bay, all of which had been attributed to low dissolved oxygen and high 

temperatures (Denson, official communication, 2010). 

Information from the Louisiana Dept. of Wildlife and Fisheries on fish kills in the summer of 2011 

(Adriance, official communication. 2011) lists eight fish kills in Louisiana in 2011, beginning on May 11, 

2011. All of the kills involved menhaden, with the exception of a single fish kill of unknown causes on 

Elmer’s Island involving 500,000+ fish, mostly 5- to 6-in croaker. The other kills involved between 

1,000 and 100,000 menhaden, and the causes were listed as unknown or low dissolved oxygen. 

Recent analysis of early stage survival of fish species inhabiting seagrass nursery habitat from 

Chandeleur Islands, Louisiana, to St. Joseph Bay, Florida, pre- and post-DWH show that immediate 

catastrophic losses of 2010 cohorts were largely avoided, and no shifts in species composition occurred 

following the spill (Fodrie and Heck, 2011). 

Shellfish 

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 and its resultant closures may be evident in future harvests 

White shrimp harvest in 2010 decreased approximately 11 percent in the Gulf of Mexico from 

101.7 million pounds in 2009 to 90.7 million pounds in 2010. The two states showing an increase in the 

2010 harvest over the 2009 harvest were Texas and the West Coast of Florida (USDOC, NMFS, 2011d). 

The 2010 brown shrimp harvest of 73.3 million pounds was down approximately 37.6 percent from 

the 2009 season of 117 million pounds and 7 percent from the 2008 season landing of 141.7 million 

pounds. Both Louisiana and Texas had increased landings in 2010 over 2009, although Texas’ landings 

were much larger in 2010 than in 2009, indicating a possible shift of shrimpers to Texas waters where 

there were no closures (USDOC, NMFS, 2011d). 

The blue crab harvest in the Gulf Coast States decreased from 58.9 million pounds in 2009 to 

41.0 million pounds in 2010 (30.4%). This represented a decreased harvest in Louisiana, Mississippi, and 

Alabama, and an increased harvest in Texas and the West Coast of Florida (USDOC, NMFS, 2011d). 

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 did have an effect on this year’s crop. Many of the beds have been closed for most 

of the season. Oyster harvest from the Gulf Coast was down 31 percent from 22.6 million pounds in 2009 

to 15.6 million pounds in 2010, with most of the loss attributable to the losses in Louisiana (USDOC, 

NMFS, 2011d). The public seed ground openings in Louisiana 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. 

Texas was the only state with an increase in oyster landings in 2010 (USDOC, NMFS, 2011d). 

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 

demonstrated by Mackin and Sparks (1961), but it does affect their taste and render them unmarketable. 
4-318 Central Planning Area Supplemental EIS 

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, official 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. 

Banks (2011) released a report on oyster mortality in the Breton Sound and Barataria Basins that 

resulted from low salinities and high temperatures experienced in both basins during the summer of 2010. 

Low salinities in these basins resulted from the operation of the Davis Pond Diversion (Barataria Basin) 

and the Caernervon Diversion (Breton Sound Basin). Both diversions were opened to allow Mississippi 

River water to flow in the basins and to keep oil from the DWH event from penetrating the estuaries. 

Breton Sound Basin sampling showed an overall mortality of 77 percent. Mortality on private leases that 

are primarily located in the upper basin showed an overall mortality of 85.6 percent as compared with 

56.3 percent mortality on public grounds that are mostly located downbasin. 

Basinwide mortality in the Barataria Basin was estimated at 32.5 percent, with mortalities being fairly 

evenly distributed across public and private grounds. Upbasin locations showed more mortality than 

downbasin stations, with one downbasin station in Bay Jacques located near the mouth of the Mississippi 

River showing 100 percent mortality. 

Between May 9 and June 20, 2011, the Bonnet Carre’ Spillway was opened, allowing Mississippi 

River water to flow through Lakes Pontchartrain and Borgne into the Mississippi Sound. In Mississippi 

Sound, the percent oyster mortalities between samplings in May and June increased at Pass Christian 

(16-54%), at Pass Marianne Reef (18-43%), and at St. Joseph’s Reef (7-99%). Sacks per acre decreased 

from 448 to 36.4 at the Pass Christian Complex, from 91 to 43.8 at Pass Marianne Reef, and from 121 to 

2.7 at St. Joseph’s Reef. Telegraph Reef was apparently unaffected, with mortalities dropping from the 

May level of 40 percent to the July level of 36 percent, and the sacks per acre rose from 8.1 in May to 

15.5 in July (Gordon, official communication, 2011). 

Between May 14 and June 24, 2011, 17 bays of the Morganza Floodway were opened, allowing 

freshwater to flow into the Atchafalaya Basin. The effects of the freshwater on oyster mortalities in 

southeastern Louisiana and on the mortalities on the beds in the southern portion of the Atchafalaya Basin 

are currently unknown; however, given the species’ intolerance for freshwater, it appears that the recent 

opening on the floodways will result in further mortalities and stresses to the species. The Louisiana 

Dept. of Wildlife and Fisheries is conducting sampling in potentially affected areas, and the results will be 

incorporated as they become available. 

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 2009 status report (USDOC, NMFS, 2010c), they reviewed 

522 individual stocks and stock complexes and made determinations of overfishing and overfished for 
Description of the Environment and Impact Analysis 4-319 

193 stocks complexes; an additional 67 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, and gray triggerfish. 

All of these species occur throughout the GOM in and around reefs. 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 

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). 
4-320 Central Planning Area Supplemental EIS 

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 (Chapter 

4.1.1.16. 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 onethird 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 (2011g). 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. 

Despite the publication of the preliminary studies cited above, there remains incomplete or 

unavailable information regarding the effects of the DWH event on commercial fishing and the species on 

which the industry depends. Here, BOEM concludes that the unavailable information from this event 

may be relevant to foreseeable significant adverse impacts to the commercial fishing industry. The 

BOEM believes that some of the incomplete or unavailable information regarding effects of the DWH 

event on the commercial fishing industry may be essential to a reasoned choice among alternatives. 

Relevant data on the status of the industry and commercially important fish populations after the DWH 

event may take years to acquire and analyze through the NRDA process and other studies, and impacts 

from the DWH event may be difficult or impossible to discern from other factors. Therefore, it is not 

possible for BOEM to obtain this information within the timeframe contemplated in this Supplemental 

EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable information, 

BOEM subject-matter experts have used available scientifically credible evidence in this analysis and 

based upon accepted methods and approaches. 

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 BOEM has reexamined the impacts of CPA activities on the 

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 
Description of the Environment and Impact Analysis 4-321 

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. These impacts are limited to the immediate area of the decommissioning activity and to those 

fish that happen to be at the platform at the time of the use of explosives. As such, these impacts are 

limited geographically and temporally, and would not be expected to rise to population-level impacts. 

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. 

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. 

Seismic surveys would occur in both shallow and deep waters of the CPA. Seismic survey vessels 

are of temporary presence in any commercially fished area of the CPA. Temporal and spatial 
4-322 Central Planning Area Supplemental EIS 

distributions of commercial species are not affected in areas adjacent to seismic surveys. The locations 

and schedules of seismic surveys are published in the USCG’s “Local Notice to Mariners.” Seismic 

surveys have a negligible impact on commercial fisheries because surveys are limited in time and space, 

and the observed fish response is to avoid the area of the survey for a short period of time. As such, these 

impacts would be limited to a small area and a matter of days. 

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 (e.g., it is not significantly different from background 

concentrations). 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). As such, any 

impact to commercial fisheries would likely be indistinguishable from exposure to background 

concentrations. 

Despite the publication of some data since the DWH event, there remains incomplete or unavailable 

information regarding the effects of the DWH event on commercial fishing and the species on which the 

industry depends. The BOEM concludes that the unavailable information from this event may be relevant 

to foreseeable significant adverse impacts to the commercial fishing industry. Although impacts from 

routine activities are expected to be small for most commercially important fish resources, BOEM 

nevertheless cannot definitively determine at the present time that some of the incomplete or unavailable 

information regarding effects of the DWH event on the commercial fishing industry may be essential to a 

reasoned choice among alternatives. Relevant data on the status of the industry and commercially 

important fish populations, particularly if there are any disruptions to reproduction or life cycles, after the 

DWH event may take years to acquire and analyze through the NRDA process and other studies, and 

impacts from the DWH event may be difficult or impossible to discern from other factors. Therefore, it is 

not possible for BOEM to obtain this information within the timeframe contemplated in this 

Supplemental EIS, regardless of the cost or resources needed. In light of the incomplete or unavailable 

information, BOEM subject-matter experts have used available scientifically credible evidence in this 

analysis and based upon accepted methods and approaches. 

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 significant impacts to commercial fisheries. Operations 

such as production platform emplacement, underwater OCS impediments, and explosive platform 

removal would cause displacement of commercial fishing while operations are ongoing. These 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. 
Description of the Environment and Impact Analysis 4-323 

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 shore-based spills would be very small, limited to the storage 

capacity, and of shorter response time. 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 low-level 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 

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 where they spend a 

portion of their life cycle. 

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 a catastrophic event, such as the DWH event, on commercial fisheries are preliminary 

and mostly speculative at this point. Data gaps are unavoidable, and it may take several years to acquire 

the necessary data and analyze it regarding long-term effects of the DWH event on all Gulf of Mexico 

commercial fisheries populations. The NRDA action will spearhead these efforts, but at this time, it has 

not published much relevant data. Regardless of the costs of acquiring these data, given the realities of 

the NRDA process, these data will not be available within the timeframe contemplated for this NEPA 

analysis. In any event, this information is not essential to a reasoned choice among the alternatives 

because catastrophic events remain extremely low-probability events (Appendix B). 

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., 2011a) 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. Any impacts are expected to have been temporary and, in general, 

fish, including commercial stocks, typically avoid areas of low dissolved oxygen. 

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 
4-324 Central Planning Area Supplemental EIS 

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. Impacts of oil spills can be via hydrocarbon uptake of prey, direct exposure of dissolved petroleum 

products through the gills and epithelium of adults and juveniles, decreased survival of larvae, and death 

of eggs (NRC, 1985 and 2002). 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 

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, official communication, 2010). Area closure may, therefore, have a somewhat positive 

impact on inshore commercial fisheries populations, even in the context of an accidental event. 

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. Here, BOEM concludes that the unavailable information from this event may be 

relevant to reasonably foreseeable significant adverse impacts to the commercial fishing industry. 

Although the likelihood of an accidental event being of such size and duration to impact commercial 

fishing areas and fish resources is remote, BOEM notes that the incomplete or unavailable information 

regarding the effects of the DWH event on the commercial fishing industry may be essential to a reasoned 

choice among alternatives. Relevant data on the status of the industry and commercially important fish 

populations after the DWH event may take years to acquire and analyze through the NRDA process and 

other studies, and impacts from the DWH event may be difficult or impossible to discern from other 

factors. Therefore, it is not possible for BOEM to obtain this information within the timeframe 

contemplated in this Supplemental EIS, regardless of the cost or resources needed. In light of the 

incomplete or unavailable information, BOEM subject-matter experts have used available scientifically 

credible evidence in this analysis and based upon accepted methods and approaches. 

Summary and Conclusion 

The BOEM 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 
Description of the Environment and Impact Analysis 4-325 

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, the most typical events are small 

and of short duration, and the effects are so localized that fish are typically able to avoid the area 

adversely impacted. 

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 because many fish spend a portion of 

their life cycle there. The probability of an offshore spill impacting these nearshore environments is also 

low, and oil would generally be volatilized or is dispersed by currents in the offshore environment. The 

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. 

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) wetland loss; (3) hurricanes; 

(4) installation of production platforms and underwater OCS obstructions; (5) production platform 

removals; (6) seismic surveys; (7) petroleum spills; (8) subsurface blowouts; (9) pipeline trenching; and 

(10) offshore discharges of drilling mud and produced waters. 

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. This is a significant 

problem as evidenced in the recent report (USDOC, NMFS, 2011e). 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. 

Wetland Loss 

The most serious impact to commercial fisheries is the cumulative effects on wetlands that are 

occurring at an ever-increasing rate. This is primarily from the population increase, and associated 

development relating to this population increase, of the Gulf Coast States and the recent effects of major 

storms and sea-level rise on wetland loss. Wetland conversion to open water would result in a permanent 

loss of nursery and foraging habitat for many commercial fish stocks. In comparison to the large area of 

wetland loss to commercial and recreational (such as marinas and camps) development as well as to 

natural forces such as hurricanes, any incremental wetland loss due to the CPA proposed action would be 

minimal. 
4-326 Central Planning Area Supplemental EIS 

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 footprint area of OCS structures is small and easily 

avoided by fishing vessels, 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, but these impacts would be localized to the 

immediate area of concern and would be short term. 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. Seismic 

surveys are limited in time and space, and the observed fish response is to avoid the area of the survey for 

a short period of time (Wannamaker and Rice. 2000). 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. 

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, 
Description of the Environment and Impact Analysis 4-327 

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. 

Offshore live bottoms would not be impacted. Offshore discharges and subsequent changes to marine 

water quality are regulated by USEPA NPDES permits. 

Methylmercury is the bioavailable form of mercury. Biomagnification of mercury in large fish of 

higher trophic levels is a problem in the Gulf of Mexico. 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. 
4-328 Central Planning Area Supplemental EIS 

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. Sampling results of 

methylmercury in the vicinity of OCS structures do not vary significantly from background 

concentrations. 

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 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. 

The impacts of a catastrophic oil spill, such as the DWH event recently experienced in the Gulf of 

Mexico and based on limited data now available, are discussed in Appendix B. Information available on 

the effects to 2010 commercial fisheries from the DWH event (and thus changes to the commercial 

fisheries baseline in the affected environment) makes an understanding of the cumulative effects 

somewhat clearer, although all effects are not yet defined. Here, BOEM concludes that the unavailable 

information from these events may be relevant to foreseeable significant adverse impacts to the 

commercial fishing industry and commercially important fish resources. Relevant data on the status of 

commercially important fish populations and the commercial fishing industry after the DWH event may 

take years to acquire and analyze, and impacts from the DWH event may be difficult or impossible to 

discern from other factors. Therefore, it is not possible for BOEM to obtain this information within the 

timeframe contemplated in this Supplemental EIS, regardless of the cost or resources needed. In light of 

the incomplete or unavailable information, BOEM subject-matter experts have used available 

scientifically credible evidence in this analysis and based upon accepted methods and approaches. 

Nevertheless, BOEM believes that incomplete or unavailable information regarding the effects of the 

DWH event on the commercial fishing industry is not essential to a reasoned choice among alternatives in 

the cumulative effects analysis. The expected incremental effect of the proposed action remains small, 

when viewed in light of other historic, ongoing, and reasonably foreseeable future factors impacting 

commercial fishing, such as fishing pressures, habitat loss, and hurricanes described above. 

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 a relatively small footprint, 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. Compared with non-OCS activities (such as commercial fishing 

practices, wetland loss, and hurricanes), the incremental effect of the proposed action is not expected to 

be significant. 

4.1.1.18. Recreational Fishing 

The BOEM 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 
Description of the Environment and Impact Analysis 4-329 

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 

substantially increase the likelihood of an additional low-probability, large-scale catastrophic 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, 

the 2009-2012 Supplemental EIS, and new information that has become available since both documents 

were prepared. 

This section discusses the baseline environment for recreational fishing along the coasts of Louisiana, 

Mississippi, Alabama, and Florida. 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 2006 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. 

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 
4-330 Central Planning Area Supplemental EIS 

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. 

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 Federal waters in the Gulf of Mexico; this percentage fell dramatically by 

mid-November to less than 1 percent. There are currently no closures in the Gulf. 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 in 
Description of the Environment and Impact Analysis 4-331 

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. The IEM (2010) provides an overview 

of the factors that will determine the extent to which some fish species will be able to adapt to the spill. 

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. Fish resources important in recreational fishing, and the effects and 

potential effects of the DWH event on these resources, as well as what information remains incomplete or 

unavailable, are described in Chapters 4.1.1.16 and 4.1.1.17. 

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. The 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. 
4-332 Central Planning Area Supplemental EIS 

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 develop 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-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 D 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. 

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. The website of NOAA’s Center for Coastal Monitoring and 

Assessment provides a set of maps that outline the areas in the Gulf of Mexico in which certain fish 

species are prevalent. 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 be offset 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 
Description of the Environment and Impact Analysis 4-333 

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. 

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). The two primary types of methods to evaluate the impacts of 

changes to fisheries available to anglers are revealed preference models and stated preference models. 

Revealed preference models infer the value anglers attach to certain fishery attributes through their 

observed behavior, while stated preference approaches ask anglers how they would adjust their fishing 

behavior in hypothetical situations. The features of a particular fishing site that will determine its value to 

anglers include its travel distance, species densities, catch rates, and the level of support facilities. Haab 

et al. (2000 and 2010) 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. This study arrives at a rough estimate of $31 million in 

damage due to the spill. However, this study also discusses the numerous sources of uncertainty in 

arriving at this estimate. 

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. Greater New Orleans, Inc (2011) conducted a 

survey-based study to determine the effects of perception on seafood and tourism in Louisiana. This 

study found that perceptions of fishing and seafood in Louisiana were more negatively impacted than 

perceptions of the region more generally. This particular impact of oil spills on perceptions of seafood 

would likely impact recreational fishing activity. However, the effects on recreational fishing activity are 

more complex than on commercial fishing since anglers are less focused on direct consumption of their 
4-334 Central Planning Area Supplemental EIS 

catch. In particular, the aesthetic effects of fishing in waters that are perceived to be tainted will 

determine the extent to which anglers curtail their activities in areas in the vicinity of a spill. 

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. 

The website of NOAA’s Center for Coastal Monitoring and Assessment provides a set of maps that 

outline the areas in the Gulf of Mexico in which certain fish species are prevalent. A spill farther from 

shore would have more of an impact on species such as king mackerel and red snapper. 

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 

remediated. 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. 

4.1.1.18.4. 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 would arise 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 would arise from State and 

Federal fisheries management plans, the role of oil platforms as artificial reefs, and the lingering impacts 

of the DWH event. 
Description of the Environment and Impact Analysis 4-335 

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, 2011b). 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 (2010d). 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 that OCS platforms 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, which would also affect recreational fishing 

activity in the 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-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, the ultimate long-term outcome of which is not yet clear (Chapters 4.1.1.16 and 

4.1.1.17). 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 fishingbased tourism could have broader impacts to a local economy. 
4-336 Central Planning Area Supplemental EIS 

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, the likelihood of this type of catastrophic spill event 

remains remote in the context of the proposed action. 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 compared with other non-OCS energy-related factors such 

as wetland loss, coastal water quality degradation, and FMP’s (which would help keep overall 

recreational fishing activity reasonably stable through time). 

4.1.1.19. Recreational Resources 

The BOEM 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. The DWH event did have impacts to recreational resources and tourism 

activity in the CPA and in Florida. However, the fact that the spill was a low-probability event leads the 

impact conclusions for recreational resources to be similar to those reached in the Multisale EIS and the 

2009-2012 Supplemental EIS. Namely, routine OCS actions can lead to low levels of space-use conflict 

and can cause some minor aesthetic impacts. Oil spills will generally have short-term impacts to beaches 

and to local economies that depend on beach recreation. The DWH event also highlighted the fact that a 

catastrophic spill can have complex effects on tourism activity in a broader economic area. However, the 

overall impacts of the proposed action are still expected to be minimal since the proposed action does not 

substantially increase the likelihood of a large oil spill. 

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, and Louisiana 

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. 
Description of the Environment and Impact Analysis 4-337 

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 BOEM-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-1 in 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 4-16a 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 4-16a, 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 4-16a presents data on the total number of jobs in the recreation and 

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 4-17a presents data on total 

wages earned in the leisure/hospitality industry for the same geographic regions discussed in Table 

4-16a. In 2009, workers in the leisure and hospitality industries in the Florida, Alabama, Mississippi, and 

Louisiana EIAs earned approximately $14 billion. The trends for each EIA over time are similar as was 

seen in Table 4-16a. 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 4-17a. 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. 
4-338 Central Planning Area Supplemental EIS 

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 4-16a 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. 

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 

$172.9million 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 
Description of the Environment and Impact Analysis 4-339 

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 De Soto 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, 2010e). 

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, FWS and USDOC, Census Bureau, 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. 

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, 2010b). 

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 
4-340 Central Planning Area Supplemental EIS 

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, 2010e). 

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 Federal fishing areas in the Gulf 

of Mexico (this occurred on June 2); as of April 19, 2011, all Federal waters have been reopened to 

fishing activity (USDOC, NOAA, 2011f). Chapter 4.1.1.18 contains more information on the impacts of 

the oil spill on recreational fishing activity. In addition, several beaches between eastern Louisiana and 

the northeast corner of Florida experienced either advisories or closures due to the spill (a list of these 

advisories/closures can be found at National Resources Defense Council [2010]). The National Oceanic 

and Atmospheric Administration’s ERMA mapping system provides a graphical representation of the 

status of shoreline cleanup operations on Gulf Coast beaches. This site categorizes shorelines into the 

following categories: (1) work required; (2) work in progress; (3) cleaned to Shoreline Treatment 

Recommendation levels; and (4) verified to be clean. As of the most recent NOAA report on shoreline 

cleanup status (January 11, 2011), a fair amount of progress has been made towards cleaning affected 

shorelines. However, areas such as Bon Secour (Alabama), Gulf Islands National Seashore (Florida), and 

Barataria Bay (Louisiana) still had a number of areas in which cleanup work is still in progress. The 

OSAT-2 report (2011) provides a more detailed analysis of the status of cleanup operations in four areas 

of particular interest: Grand Isle (Louisiana); Petit Bois Island (Mississippi); Bon Secour (Alabama); and 

Fort Pickens (Florida). 

The damage to the aforementioned recreational resources caused a number of immediate impacts to 

the economies in the Gulf of Mexico. A decrease in tourism to affected areas caused a number of impacts 

to hotels and other firms in certain areas. A broad summary of the impacts to tourism felt along the Gulf 

Coast is presented in U.S. House of Representatives (2010). This report documents that the effects of the 

spill on tourism activity were felt in areas beyond those with damage to physical recreational resources. 

Market Dynamics Research Group (2011) provides additional evidence on the effects of the DWH event 

on public perceptions of Louisiana. This study finds that the DHW event initially raised a number of 

concerns among the public regarding traveling to Louisiana; this study also finds that these concerns have 

generally diminished over time. Press Register (2010) provides data on the change in hotel and sales tax 

receipts for individual Gulf Coast counties during the summer of 2010 compared with the summer of 

2009; Barker (2011) provides similar data for the 6 months following the DWH event. During the 

summer of 2010, the spill caused substantial declines in hotel receipts in the following counties: 

Baldwin, Alabama (33.2% decline); Santa Rosa, Florida (24.8% decline); Okaloosa, Florida (24.1% 

decline); Walton, Florida (12.3% decline); and Bay, Florida (7.4% decline). However, coastal counties 

west of Baldwin, Alabama, generally experienced noticeable increases in hotel receipts. This was 

particularly true in Mobile, Alabama; Jackson, Mississippi; and in the coastal parishes of Louisiana. For 

example, in Louisiana, St. Mary Parish, Terrebonne Parish, and Lafourche Parish each reported increases 

in hotel tax receipts of over 80 percent in the summer of 2010. These effects are likely due to the influx 

of oil-spill relief workers to these areas in the immediate aftermath of the spill. Overall sales tax receipts 

in counties from Baldwin, Alabama, eastward also generally fell during 2010, although to a lesser extent 

than hotel tax receipts. Sales tax receipts in counties west of Baldwin, Alabama, did not show as clear a 

pattern as did hotel tax receipts. For example, overall sales tax receipts fell by 12.5 percent in Hancock 

County (Mississippi), were almost unchanged in Harrison County (Mississippi), and increased by 

8.3 percent in Orleans Parish (Louisiana). The 6-month data provided by Barker (2011) suggest that the 

negative effects of the spill on tourism moderated to some extent towards the end of 2010. For example, 
Description of the Environment and Impact Analysis 4-341 

in Florida, combined sales and hotel tax receipts during the 6 months following the spill ranged from a 

fall of 5 percent in Walton County to an increase of 4 percent in Jefferson County. 

Data on damage claims through the Gulf Coast Claims Facility provide measures of the extent of the 

damage from the spill to date. Through May 16, 2011, Florida has had the largest level of damage claims 

($1.6 billion), followed by Louisiana ($1.3 billion), Alabama ($750 million), and Mississippi 

($350 million). The bulk of the total dollar value of claims in these four states have occurred in the retail, 

sales, and service industry ($1.4 billion); the food, beverage, and lodging industry ($1.2 billion); the 

fishing industry ($646 million); and the rental property industry ($469 million). Direct losses in the 

recreation industry were $88 million, although the losses in the other industries were tourism related. 

Data on employment and wages provide another perspective from which to view the impacts of the 

oil spill on recreation and tourism along the Gulf Coast. Table 4-16b presents monthly data on total 

employment in the leisure/hospitality industry during 2010. This data is presented for the same 

geographic regions as in Table 4-16; all employment and wage data were obtained through the U.S. Dept. 

of Labor, Bureau of Labor Statistics. The definition of the leisure/hospitality industry corresponds to the 

definition used by the North American Industrial Classification System; this definition includes subindustries such as entertainment providers, lodging services, and food/beverage services. In Table 4-16b, 

it can sees that overall employment in the leisure/hospitality industry did not noticeably fall during the 

months following the DWH event in any geographic region. Indeed, employment in most regions was 

strikingly stable. The only region with a notable fall in employment was FL-4, although this fall was 

likely partially seasonally related. Table 4-17b presents quarterly data on total wages earned by workers 

during 2009 and 2010 in the leisure hospitality industry for the same geographic regions as were 

presented in Table 4-17. Wages generally exhibited the stability seen in overall employment. Indeed, the 

only EIA that exhibited a fall in wages from the third quarter of 2009 to the third quarter of 2010 was 

FL-1, which experienced a decline in wages of 2.3 percent. This overall stability exhibited in recreational 

employment is likely due to the effects of the spill relief workers and the damage payments received by 

affected parties. While this overall stability in employment surely masks some variation in particular 

industries and regions, it does suggest that, as of yet, the oil spill has not drastically changed the structure 

of the recreation industry in the Gulf Coast. 

For the purposes of discussing the baseline environment, there is an important distinction between 

those effects that occurred during the spill versus those that will persist in the aftermath of the spill. 

Although some cleanup operations are ongoing in some areas, the majority of the oil has been removed 

from the recreational resources along the Gulf Coast. However, the speed at which tourism activity will 

return to the Gulf Coast remains unclear. 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. Analyzing previous oil spills and other catastrophic events, they suggest that it could 

take 15-36 months for the tourism industry to recover to pre-spill levels. Anecdotal evidence suggests 

that tourism activity is indeed gradually recovering from the spill; for example, see Nelson (2011), 

National Public Radio (2011), and Stacy (2011). However, it will take some time to more accurately 

gauge the speed at which tourism activity is returning to pre-spill levels. The BOEM will continue to 

monitor this issue and will update its assessment of baseline conditions for recreational resources as new 

information becomes available. 

While there remains some uncertainty regarding the impacts of the DWH event on recreational 

resources, and this incomplete or unavailable information may be relevant to reasonably foreseeable 

significant impacts, BOEM does not believe that this incomplete information is essential to a reasoned 

choice among alternatives. Even after the DWH event, the types of impacts to recreational resources 

were largely foreseeable (e.g., reductions in local tourism, reduced angler trips, a shifting of recreational 

activities to nearby areas) but recent data indicate that most of these impacts were generally short term or 

are continuing to improve. While there remains some uncertainty as to the geographical scope of these 

impacts based on the size and timing of the spill, and the impact of public perception in the short and long 

term, BOEM has taken these concerns into account in its analysis in the Supplemental EIS. 
4-342 Central Planning Area Supplemental EIS 

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. However, 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. 

Beaches and other coastal recreational resources are the most vulnerable to routine OCS operations. 

One concern is the extent to which discharges of marine debris from OCS actions could reach these areas. 

Debris can noticeably affect the aesthetic value of coastal areas, particularly beaches. This is particularly 

true given the significant levels of marine debris that already exist in some areas. Marine debris 

originates from OCS operations, sewage treatment plants, recreational and commercial fishing, industrial 

manufacturing, and various forms of vessel traffic. The United Nations Environment Programme (2009) 

presents a broad overview of the nature of the marine debris problem. 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 Interagency Marine 

Debris Coordinating Committee (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) 

describes the structure of the National Marine Debris Monitoring Program; Ocean Conservancy (2011) 

presents the results from the most recent round of debris monitoring. McIlgorm et al. (2009) presents an 

economic analysis of the costs of marine debris and of programs designed to minimize debris. Finally, 

Barnea et al. (2009) outlines some issues regarding debris removal that are unique to the Gulf of Mexico. 

The discharge of marine debris is subject to a number of laws and treaties. These include the Marine 

Debris Research, Prevention, and Reduction Act; the Marine Plastic Pollution Research and Control Act; 

and the MARPOL-Annex V Treaty. Regulation and enforcement of these laws are conducted by a 

number of agencies, such as USEPA, NOAA, and USCG. The BOEM’s policy regarding marine debris 

prevention is outlined in NTL 2007-G03, “Marine Trash and Debris Awareness and Elimination” 

(USDOI, MMS, 2007g). This NTL requires that OCS operators post informational placards that outline 

the legal consequences and potential ecological harms of discharging marine debris. This NTL also 

instructs OCS workers to complete annual marine debris prevention training, and operators are also 

instructed to develop a certification process for the completion of this training by their workers. These 

various laws, regulations, and NTL’s will likely minimize the potential damage to recreational resources 

from the discharge of marine debris from OCS operations. 

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 minimize these effects. First, most OCS-related vessel traffic 

moves between onshore support bases 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 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. Even if a platform were visible, the scale of its impact on tourism 

would likely be small unless it interrupted the vision of other important landscape features. 

Oil platforms 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 to serve as artificial reefs after oil 
Description of the Environment and Impact Analysis 4-343 

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. More 

information regarding the effects of OCS platforms on recreational fishing activity can be found in 

Chapter 4.1.1.18.2. 

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 the CPA, the 

potential for space-use conflicts would be greatest along coastal Louisiana, particularly near Port 

Fourchon (LaFourche Parish). Chapter 4.2.1.23.1 provides more detailed information regarding the 

ports and other facilities that support OCS activities in the CPA. The vessel traffic near these facilities 

could cause space-use conflicts with boating activities and with recreational fishing activities. However, 

even if a space-use conflict was to arise in a particular instance, it is likely that a number of substitute 

recreational sites would be available. In addition, given the entrenched nature of the OCS oil and gas 

industry in coastal Louisiana, it is unlikely that any particular OCS action would significantly add to 

space-use conflicts in this area. 

The OCS activities also have the potential to increase or decrease the demand for recreational 

resources in certain 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. 

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 particularly the case for recreational resources that require 

investments in real estate or other long-term fixed assets. CoreLogic (2010) and Bloomberg (2010) 

provide estimates of the extent to which the DWH event will negatively impact property values in the 

Gulf of Mexico. Bloomberg (2010) forecasts a loss of $4.3 billion in property values, while CoreLogic 

(2010) forecasts a loss of $3 billion in the 15 most affected coastal counties/parishes over 5 years. 

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 
4-344 Central Planning Area Supplemental EIS 

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 can cause minor disturbances to recreational resources, particularly 

beaches, through increased levels of noise, debris, and rig visibility. The OCS activities can also change 

the composition of local economies through changes in employment, land use, and recreational demand. 

A CPA lease sale has the potential to directly and indirectly impact recreational resources along the entire 

Gulf Coast. However, the small scale of the proposed action relative to the scale of the existing oil and 

gas industry suggests that these potential impacts on recreational resources are likely to be minimal. 

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 the National Oceanic and Atmospheric Administrtion’s ERMA mapping system (USDOC, NOAA, 

2010e). 

The effects of an oil spill on a particular beach region would depend on the success of the 

containment and cleanup operations following an oil spill. A broad overview of the procedures used to 
Description of the Environment and Impact Analysis 4-345 

assess oiled beaches is presented in NOAA’s shoreline assessment manual (USDOC, NOAA, 2000). 

Both manual and machine-based techniques can be used to clean oil; the cleaning technique chosen for a 

particular beach would depend on the nature of the oiling of a particular beach area. The nature of 

cleanup operations will also depend on whether a particular beach serves as a habitat to particular animal 

species. This is because removing oil deep below a beach surface can sometimes do more ecological 

harm than good. As a result, ecological beaches are often only cleaned to a shallow depth, while 

nonecological (“amenity”) beaches are often cleaned more extensively. The same is true around cultural 

and archaeological sites, such as shipwrecks embedded in the beach, where manual cleaning techniques 

may be dictated. The cleanup plan for any particular beach is determined by a Shoreline Treatment 

Recommendation, which is prepared by the relevant State and Federal agencies for a particular spill. An 

example of a Shoreline Treatment Recommendation following the DWH event for Grande Isle can be 

found at RestoreTheGulf.gov (2010b). The Operational Science Advisory Team (OSAT-2, 2011) 

presents an overview of the cleanup operations during the DWH oil spill. This report also indicates the 

beach areas for which work is still progressing and those that have been cleaned to the extent prescribed 

by the relevant Shoreline Treatment Recommendation. Wang and Roberts (2010) presents an analysis of 

field examinations of beach areas following the DWH oil spill. This study found a number of beach areas 

in which oil remained buried under the surface. This study also points out that beach cleaning techniques 

can leave remnant oil on beach surfaces. This study found examples of beaches where less than 

25 percent of overall oil contamination had been removed. However, since this study was based on 

samples of certain beach segments, the study does not attempt to quantify the level of oil contamination in 

broad beach regions. 

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 

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, Press Register (2010) 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. 
4-346 Central Planning Area Supplemental EIS 

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 would 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. Recreational resources that require investment in real estate or other long-term 

fixed assets may likewise be impacted by public perceptions. CoreLogic (2010) and Bloomberg (2010) 

provide estimates of the extent to which the DWH event will negatively impact property values along the 

Gulf Coast. Bloomberg (2010) forecasts a loss of $4.3 billion in property values, while CoreLogic (2010) 

forecasts a loss of $3 billion in the 15 most affected coastal counties/parishes over 5 years. It is possible 

that some of these effects would be magnified if additional OCS activity added to fears of another oil 

spill. While the effects of an oil spill on tourism and recreational resources 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. 

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, 2010e). 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. 
Description of the Environment and Impact Analysis 4-347 

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. 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 because 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 is becoming better understood in the aftermath 

of the spill. 

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. 

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. One concern is the extent to which discharges of marine 

debris from OCS actions would contribute to the existing marine debris problems experienced along the 

Gulf Coast. Debris can noticeably affect the aesthetic value of coastal areas, particularly beaches. This is 

particularly true given the significant levels of marine debris that already exist in some areas. Marine 

debris originates from OCS operations, sewage treatment plants, recreational and commercial fishing, 

industrial manufacturing, and various forms of vessel traffic. The United Nations Environment 

Programme (2009) presents a broad overview of the nature of the marine debris problem. 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 

Interagency Marine Debris Coordinating Committee (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) describes the structure of the National Marine Debris Monitoring Program; Ocean 

Conservancy (2011) presents the results from the most recent round of debris monitoring. McIlgorm et 

al. (2009) present an economic analysis of the costs of marine debris and of programs designed to 

minimize debris. Finally, Barnea et al. (2009) outline some issues regarding debris removal that are 

unique to the Gulf of Mexico. 
4-348 Central Planning Area Supplemental EIS 

The discharge of marine debris is subject to a number of laws and treaties. These laws and treaties 

include the Marine Debris Research, Prevention, and Reduction Act; the Marine Plastic Pollution 

Research and Control Act; and the MARPOL-Annex V Treaty. Regulation and enforcement of these 

laws are conducted by a number of agencies, such as USEPA, NOAA, and USCG. The BOEM’s policy 

regarding marine debris prevention is outlined in NTL 2007-G03 (USDOI, MMS, 2007g). This NTL 

requires that OCS operators post informational placards that outline the legal consequences and potential 

ecological harms of discharging marine debris. This NTL also instructs OCS workers to complete annual 

marine debris prevention training, and operators are also instructed to develop a certification process for 

the completion of this training by their workers. These various laws, regulations, and NTL’s will likely 

minimize the potential damage to recreational resources from the discharge of marine debris from OCS 

operations. 

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 

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. 
Description of the Environment and Impact Analysis 4-349 

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 remediation 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 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 located at some distance 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. 

The incremental contribution of the CPA proposed action is expected to be minima, in light of all nonOCS-related activities such as aesthetic impacts (including from other industrial sources), wetland loss, 

and space-use conflicts. 

4.1.1.20. Archaeological Resources 

The BOEM 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 and 

30 CFR 550.105). 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 BOEM-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 were 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 additional archaeological resource surveys and mitigation are 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 

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 
4-350 Central Planning Area Supplemental EIS 

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. Based on the results 

of this study, BOEM constructed a high-probability model for potential shipwreck locations of 

archaeological potential to guide decisions regarding which OCS lease blocks would require the operator 

to submit an archaeological report with their EP, DOCD, DPP, or other permit application. 

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. 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, BOEM 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 BOEM 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. 

In fact, in the last 5 years, over a dozen shipwrecks have been discovered through oil industry sonar 

surveys in the northern Gulf of Mexico in water depths up to 7,600 ft (2,316 m), 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. 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 BOEM 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 

35 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 BOEM-mandated oil industry surveys. The discoveries include two late 18th- to 

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. 

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. 
Description of the Environment and Impact Analysis 4-351 

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. Due to the high levels of preservation and the decrease in impacts 

from anthropogenic and meteorological events (diving, looting, trawling, hurricanes, etc.), the potential 

for recovery of archaeological data is considerably higher for shipwrecks discovered at depth as opposed 

to those found in nearshore environments. 

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 BOEM (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 and that older wooden wrecks that had achieved some level of 

equilibrium in their environment were less affected than more recent, steel-hulled wrecks (Gearhart et al., 

in press). This study on the impacts to shipwrecks from hurricanes or other storm activity was limited to 

SCUBA-diving depths of less than 130 ft (40 m). A potential result of hurricane activity in water depths 

>130 ft (40 m) may include mud flows, erosion, and the generation of strong underwater currents or 

mega-furrows (Bryant and Liu, 2000, p. 52). The study also concluded that older, wooden-hulled vessels 

became less affected by recent storm events after having settled into equilibrium within their 

environment, despite being periodically exposed and reburied. 

To date, there have been no data made publicly available regarding potential impacts from the DWH 

event on archaeological resources. No archaeological resources have been determined to be impacted to 

date. Raw data and reports relating to these samples have not been released to the public. Spill-response 

activities may have impacted archaeological resources as well, but this appears to have been of limited 

concern on the OCS, as opposed to archaeological resources on land. There is anecdotal evidence that 

cleanup activities (such as the use of trucks) in the area of Fort Morgan may have impacted historic 

resources there (Borrell, 2010). 
4-352 Central Planning Area Supplemental EIS 

Although there is incomplete or unavailable information on reasonably foreseeable impacts to historic 

archaeological resources, BOEM feels that this information is not essential to a reasoned choice among 

alternatives. The location of many archaeological resources remains unknown; some resources are 

heavily sedimented or buried and are therefore protected from many impacts; and archaeological surveys, 

where required, are expected to be highly effective in identifying resources to allow for the protection of 

the resource during oil and gas activities. Nevertheless, this incomplete or unavailable information is not 

likely to be available within the timeframe of this Supplemental EIS. Hundreds of known historic 

archaeological resources are scattered throughout the Gulf and thousands more may exist, but their 

locations are unknown to date. The costs of a Gulfwide study would be exorbitant, and it could take years 

before data confirming the presence of additional historic archaeological resources and the status of each 

could be compiled and analyzed. In place of this incomplete or unavailable information, BOEM subjectmatter experts have included what credibly scientific information is available, applied using accepted 

scientific methodologies. 

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. 

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, in this case oil and gas development activities. 

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 BOEM shipwreck database contains 
Description of the Environment and Impact Analysis 4-353 

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 archaeological 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 sidescan-sonar 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 550.194. 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 additional 

archaeological resource surveys and mitigation are warranted. 

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 historic shipwrecks. Impacts from maintenance dredging can be attributed proportionally to the 

users of the navigation channels. The BOEM 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 and removal, as well as with servicevessel 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 steel 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, where required, 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 

side-scan 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 the magnetometer. 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 sail-powered, are unlikely to be detected by 300-m (984-ft) 
4-354 Central Planning Area Supplemental EIS 

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 they are surveyed at a 300-m (984-ft) 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 (984-ft) 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, dredging, pipeline project, or decommissioning and site clearance) 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), 30 CFR 550.194(c) and 30 CFR 250.1010(c), lessees are required 

to notify BOEM and/or BSEE 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 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, 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 

CPA 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. Impacts from a lowprobability, high-volume catastrophic event are included in Appendix B. 

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. A description of the impacted corals is described in 

Chapter 4.1.1.9.1. 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. (2007, p. 205), 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. It is unknown at this time, but it is hypothesized that microbial activity may 

be accelerated or retarded by compounds and elements associated with the release of millions of gallons 

of hydrocarbons and dispersants in the water column. At this time, little information is available on the 
Description of the Environment and Impact Analysis 4-355 

condition of these shipwreck sites and the reaction to the oil spill. Additionally, there is also no 

information about the impacts of microbial activity on wooden shipwreck sites in deep water. 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. 

As noted above in the affected environment discussion, although information on the impacts of a 

potential spill to archaeological resources is incomplete or unavailable at this time and although it may be 

relevant to reasonably foreseeable adverse impacts on these resources, the information is not essential to a 

reasoned choice among alternatives. An oil spill occurring and contacting an archaeological resource is 

unlikely, given that oil released tends to rise to the surface quickly and that the average size of any spill 

would be small. 

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, official 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 

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 and in 

Table 3-5 of this Supplemental EIS, it is not very likely for an oil spill to occur, and it would not be likely 

to 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 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, where required prior to an operator beginning oil and gas activities on a 

lease, are assumed to be highly effective in reducing the potential for an interaction between an impactproducing 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 
4-356 Central Planning Area Supplemental EIS 

more likely to be exposed at the seafloor where they can be detected by the side-scan 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 currently designated, high-potential areas 

for archaeological 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 site surveys, where required, 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. 

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 metallic (e.g., iron, steel, etc.) 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 BOEM with respect to the archaeological resource protection requirements of the NHPA. Under the 

NHPA, other Federal agencies, such as COE, which issues permits associated with pipelines in State 

waters, are responsible for taking into consideration the effects of agency-permitted actions on 

archaeological resources. 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 
Description of the Environment and Impact Analysis 4-357 

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, glass, 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 BOEM for the borrow site lease. No new disturbance of historic shipwrecks would be 

expected when the results of predeployment archaeological surveys of sand borrow sites are first 

examined for sea-bottom anomalies by BOEM 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 BOEM, 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. 

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 BOEM for the borrow site lease. No new disturbance of historic shipwrecks would be 

expected when the results of predeployment archaeological surveys of sand borrow sites are first 

examined for sea-bottom anomalies by BOEM so that the proper setback distances can be required that 

allow potential resources to be avoided. 

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 
4-358 Central Planning Area Supplemental EIS 

have been impacted by treasure hunters and sport divers represent a localized loss of significant or unique 

archaeological information. 

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 

BOEM 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 550.194 grants authority in certain cases to 

each BOEM 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 additional archaeological resource survyes and mitigation 

are warranted. 

The loss or discard of metallic (e.g., iron, steel, etc.) 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. 

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 localized 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 BOEM 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 bottom-disturbing activities begin. When surveys are not required, it is impossible to anticipate 

what might be imbedded in or lying directly on the seafloor; 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 
Description of the Environment and Impact Analysis 4-359 

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; Rees, 2010). 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 BOEM 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 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. 
4-360 Central Planning Area Supplemental EIS 

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 CPA 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. 

As noted in Chapter 4.1.1.20.1.1, to date, no data have been made publicly available regarding the 

potential impacts of the DWH event on archaeological resources. No archaeological resources have been 

determined to be impacted to date. Spill-response activities may have impacted archaeological resources 

as well, but this appears to have been of limited concern on the OCS, as opposed to archaeological 

resources on land or near the coast. For example, there is anecdotal evidence that cleanup activities (such 

as the use of trucks) in the area of Fort Morgan may have impacted historic resources there (Borrell, 

2010). 

Although there is incomplete or unavailable information on reasonably foreseeable impacts to 

prehistoric archaeological resources, BOEM feels that this information is not essential to a reasoned 

choice among alternatives. The location of many prehistoric archaeological resources remains unknown, 

and those that have been identified are subject to Federal and State protections. Nevertheless, this 

incomplete or unavailable information is not likely to be available within the timeframe of this 

Supplemental EIS. There are numerous prehistoric archaeological resources scattered throughout the 

Gulf Coast and more may exist, but their location and condition is unknown to date. The costs of a 

Gulfwide study would be exorbitant and it could take years before data confirming the presence of 

additional historic archaeological resources and the status of each could be compiled and analyzed. In 

place of this incomplete or unavailable information, BOEM subject-matter experts have included what 

credibly scientific information is available and applied it using accepted scientific methodologies. 

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, BOEM 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 
Description of the Environment and Impact Analysis 4-361 

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 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 prehistoric 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 BOEMpermitted activity, BOEM 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 
4-362 Central Planning Area Supplemental EIS 

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. 

4.1.1.20.2.3. 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 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, official communication, 2010). 

As noted above in the affected environment discussion, although information on the impacts of a 

potential spill to archaeological resources is incomplete or unavailable at this time and although it may be 

relevant to reasonably foreseeable adverse impacts on these resources, the information is not essential to a 

reasoned choice among alternatives. Most OCS activities are far removed from prehistoric sites, and an 

oil spill occurring and contacting an archaeological resource is unlikely, given that oil released tends to 

rise to the surface quickly, would generally not reach coastal and nearshore areas, and the average size of 

any spill would be small. 

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, 
Description of the Environment and Impact Analysis 4-363 

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 

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 BOEM does not have jurisdiction over pipelines in State waters, the archaeological resource 

protection requirements of the NHPA are not within BOEM’s jurisdiction. Under the NHPA, other 

Federal agencies, such as COE, which lets permits associated with pipelines in State waters, are 

responsible for taking into consideration the effects of permitted activities on archaeological resources. 

Therefore, the impacts that might occur to archaeological resources by pipeline construction within State 

waters should be mitigated under the requirements of the NHPA. 
4-364 Central Planning Area Supplemental EIS 

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, 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 

pipeline construction, platform installation, drilling rig emplacement and operation, dredging, anchoring 

activities, decommissioning, and site clearance) 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 BOEM 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 ultimately 

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 suspension. The BOEM anticipates that 

there will be some long-term consequences and these will become apparent over time. The BOEM 

continues to monitor resources for changes that are applicable to 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 post-DWH environment, 

increased scrutiny of industry practices, and 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, official 

communication, 2011). 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 
Description of the Environment and Impact Analysis 4-365 

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, 

official communication, 2011). This excess capacity substantially diminishes the likelihood of new 

facility construction. Existing solid-waste 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.

4.1.1.21.1.1. 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), 19 as manufacturing dependent, 24 as government 

employment centers, 20 as tied to service employment, and 18 as nonspecialized. 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 BOEM 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 Chapter 3.3.5.1.1 of 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 BOEM-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, BOEM’s impact analysis analyzes the 

potential impacts in all 13 EIA’s regardless of where the proposed action is taking place. 
4-366 Central Planning Area Supplemental EIS 

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. 

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 

2009, 8 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, 2009). 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 

suspensions on certain offshore drilling. The initial suspension was modified on May 27, 2010, to allow 

drilling in shallow waters <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 

BOEM 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 last 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 BOEM continues to review and approve permits and plans. The impacts of the 

suspensions and permitting delays were experienced at Port Fourchon, where rental rates were cut by 

30 percent as an incentive for businesses to stay. In the months following the blowout and the declared 

suspensions, companies removed a large portion of their equipment from Port Fourchon, and there was a 

substantial decrease in helicopter flights and servicing of rigs. Many companies trimmed their budgets by 

cutting hours and salaries. Support services companies, such as chemical suppliers, and welders were 

also negatively affected (Lohr, 2010). The effects of this decreased demand rippled through the various 

infrastructure categories (e.g., fabrication yard, shipyards, port facilities, pipecoating facilities, gas 
Description of the Environment and Impact Analysis 4-367 

processing facilities, waste management facilities, etc.) and also affected the oil and gas support sector 

businesses (e.g., drilling contractors, offshore support vessels, helicopter hubs, mud/drilling 

fluid/lubricant suppliers, etc.) because the decrease in offshore drilling activity translates into a decrease 

in demand for services. For example, the impacts of the suspensions and permitting delays have been 

experienced at Port Fourchon, where rental rates were cut by 30 percent through June 30, 2011, as an 

incentive for businesses to stay. This amounted to a $3 million revenue loss for the Greater Lafourche 

Port Commission. As of June 2011, businesses operating out of Port Fourchon were collectively 

operating at about 30 percent capacity compared with pre-DWH levels. Activity levels are slowly 

improving at Port Fourchon, and according to the Executive Port Director at Fourchon, the main concern 

now is the current pace of exploration plan approvals. While production has been ongoing since the 

DWH event, the majority of the Port’s business is in drilling and exploration activities (Chaisson, official 

communication, 2011). Because petroleum activities on the OCS and in State waters and coastal areas are 

driven by market forces, the DWH event and related events are not expected to have long-term 

consequences on petroleum activities. Hence, these events are not expected to affect land use and 

infrastructure in the cumulative case. 

The BOEM continues to monitor these infrastructure effects as they evolve over time. Although this 

information on land-use and infrastructure effects is evolving and may be relevant to reasonably 

foreseeable significant impacts to the Gulf economy, this information would not be essential to a reasoned 

choice among the alternatives because regardless of whether the decisionmaker chooses to hold a lease 

sale under the action alternatives or chooses the No Action alternative, there are still preexisting OCS 

leases in the CPA and WPA that would continue to support the economy. Any individual lease sale 

would not be expected to, on its own, result in significant impacts. The incomplete or unavailable 

information, even if available, would not be expected to change these conclusions. 

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, 2010i and 2010j). 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, 

mainly concerns over leaking receptacles and waste management practices during the immediate 

aftermath of the spill, but nothing that would appear to cause a long-term impact (USEPA, 2010k). 

Additional description of the DWH event’s waste stream is found in Chapter 4.1.1.21.4. 

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 
4-368 Central Planning Area Supplemental EIS 

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 BOEM 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 BOEM 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 effects of the drilling 

suspensions, changes in Federal requirements for drilling safety, and the current pace of permit approvals 

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, official communication, 2011). However, BOEM continues to monitor resources for 

changes that are applicable to 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 several 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. 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, official communication, 2011). 

The BOEM 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, BOEM 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, BOEM projected up to one pipeline landfall per lease sale. Between the Multisale EIS and the 

2009-2012 Supplemental EIS, BOEM 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 
Description of the Environment and Impact Analysis 4-369 

incentives to move new production into existing systems and to avoid creating new landfalls (USDOI, 

MMS, 2007d). This analysis confirms BOEM’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, official communication, 2011). 

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 BOEM. 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 various types of OCS offshore support. The most prevalent categories 

of OCS offshore support include supply vessels, crewboats, and helicopters. 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 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 BOEM 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 because 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 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. 
4-370 Central Planning Area Supplemental EIS 

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. 

Focused scenario analysis research into onshore waste disposal 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, BOEM 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 would remain true and 

more research is needed (Dismukes, official communication, 2011). In recent months, due to the drilling 

suspensions and temporary interruption in permit approval slowdown, there has been some reduction in 

offshore drilling activity, which is slowly ramping back up. Given this situation, demand for waste 

disposal facilities may not be likely to increase. However, at this time BOEM cannot predict how long 

this current pace will continue or how long it will take for activity levels to recover. The BOEM 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, the effects of the drilling suspensions, the changes in Federal requirements for 

drilling safety, and the current pace of permit approvals. The BOEM 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 only 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, official communication, 2011). The BOEM 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 gas 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 BOEM anticipates these changes would become 

apparent over time. Therefore, BOEM recognizes the need to continue monitoring all resources for 

changes that are applicable for land use and infrastructure. From the information described above 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 
Description of the Environment and Impact Analysis 4-371 

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 the 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 BOEM-recognized coastal infrastructure categories. For example, if 

waterways are closed to traffic, this may result in impacts to upstream and downstream business interests 

as it impedes the flow of commerce. 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 BOEM data show that, from 1996 through 2009, there were 226 OCS-related 

collisions. The majority of vessel collisions involve service vessels colliding with platforms or pipeline 

risers, although sometimes vessels collide with each other. Human error accounted for about half of all 

reported vessel collisions from 1996 to 2009. 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 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). On Tuesday July 27, 2010, a dredge vessel ran into a wellhead in 

the Barataria Waterway. The wellhead leaked a mixture of oil, natural gas, and water into Barataria Bay. 

A sheen covered more than 6 mi2

 (16 km2) of water. Over 150 spill-response personnel and 31 boats 

initially responded to the accident (USDHS, CG, 2010e). As of August 3, 2010, approximately 35 bbl of 

oily-water mix were recovered (OffshoreEnergyToday, 2010). 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, information is 

gradually becoming available, particularly on short-term impacts. In the months following the DWH 

event, there were 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 changes in Federal 
4-372 Central Planning Area Supplemental EIS 

requirements for drilling safety and the pace of the permit approval process. Drilling resumed in shallow 

and deep waters but it depends on meeting new drilling application requirements as clarified in NTL 

2010-N06. 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. Companies removed a large portion of 

their equipment from the port and there was a substantial decrease in helicopter flights and servicing of 

rigs. As of June 2011, businesses operating out of Port Fourchon were collectively operating at about 

30 percent capacity compared with pre-DWH levels (Chaisson, official communication, 2011). 

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, official communication, 2011). 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 would 

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 BOEM will continue to monitor these infrastructure effects as they 

evolve over time. Although this information on land-use and infrastructure effects is evolving and may 

be relevant to reasonably foreseeable significant impacts to the Gulf economy, this information would not 

be essential to a reasoned choice among the alternatives because regardless of whether the decisionmaker 

chooses to hold a lease sale under the action alternatives or chooses the No Action alternative, there are 

still preexisting OCS leases in the CPA that would continue to support the economy. Any individual 

lease sale would not be expected to, on its own, result in significant impacts. 

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, 2010i and 2010j). 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, mainly concerns over 

leaking receptacles and waste management practices during the immediate aftermath of the spill, but 

nothing that would appear to cause a long-term impact (USEPA, 2010k). Additional description of the 

DWH event’s waste stream is located in Chapter 4.1.1.21.4. Detailed analysis of a high-impact, lowprobability catastrophic event such as the DWH event may be found in Appendix B. 

Summary and Conclusion 

Accidental events associated with the CPA proposed action occur at different levels of severity, based 

in part on the location and size of event. The typical types of accidental events that could affect land use 

and coastal infrastructure include oil spills, vessel collisions, and chemical/drilling-fluid spills. These 

may occur anywhere across the spectrum of severity. Typically, accidental events related to OCS 

activities are generally smaller in scale based on historic experience, and they must be distinguished from 

low-probability, high-impact catastrophic events such as the DWH event. Typically, the impact of smallscale oil spills, vessel collisions, and chemical/drilling fluid spills are not likely to last long enough to 

adversely affect overall land use or coastal infrastructure in the analysis area. 

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 (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 regard to land use and infrastructure, the post-DWH event environment remains somewhat dynamic, 

and BOEM will continue to monitor these resources over time and to document short- and long-term 
Description of the Environment and Impact Analysis 4-373 

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 BOEM 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. Research based on the analysis of historical data further 

validated BOEM’s 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 projections also are likely to be conservative (Dismukes, official 

communication, 2011). 

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 petroleum activities. Hence, these events are 

not expected to affect land use and infrastructure in the cumulative case. The BOEM continues to 

monitor resources for changes that are applicable to land use and infrastructure. 

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 BOEM 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 would be developed at existing 

facilities, through future investments in expansions, and/or replacement of depreciated capital equipment. 

Also, these BOEM scenario projections are conservative; i.e., they likely overestimate the additional 

capacity that would be required. 

Over the past several 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 
4-374 Central Planning Area Supplemental EIS 

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. Combined with this, existing facilities that were already operating at about 50 percent of capacity 

prior to the 2005 hurricane season are now 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, official communication, 2011). 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 BOEM analysis areas that have strong industrial bases. Shore-based OCS and State servicing is 

expected to increase in the ports of Port Fourchon, Louisiana; and Mobile, Alabama. There is sufficient 

land designated in commercial and industrial parks and adjacent to the Mobile port area. 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). 

In the months following the DWH event and the May 2010 drilling suspension, port tenants were 

struggling with the drop in exploration drilling. Even after the drilling suspension was lifted on 

October 12, 2010, activity levels remained depressed. This was due to more stringent Federal 

enforcement, industry’s efforts to fulfill new safety requirements, and the current pace for drilling 

application approvals. Cleanup and decontamination work was keeping companies busy, but this has 

been gradually declining, with the exception of continued cleanup at Fourchon Beach, which was slowed 

down by piping plover nesting. Deepwater exploratory drilling is a huge economic driver for jobs, 

investments, vessels, etc. at Port Fourchon (Chaisson, official communication, 2011). There has been 

much uncertainty about what is going to happen at Port Fourchon from an economic standpoint. 

However, BOEM expects this uncertainty to be short term and, because the economic prospectivity of the 

Gulf has not changed, deepwater activity at the port will be expected to gradually increase to pre-DWH 

event levels. 

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 
Description of the Environment and Impact Analysis 4-375 

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 port 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 BOEM 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, official communication 2011). There may be new increased 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 

BOEM scenario projections, the cumulative impacts on land use and coastal infrastructure are expected to 

be minor. The coastal infrastructure supporting the proposed action represents only a tiny portion of the 

coastal land and infrastructure throughout the CPA and Gulf of Mexico, and little change is expected to 

occur due to changing agricultural and extractive (e.g., lumbering, petroleum) uses of onshore land. 

Many non-OCS-related factors contribute substantially to the cumulative impacts to land use and coastal 

infrastructure, including the following: housing and other residential developments; the development of 

private and publicly owned recreational facilities; the construction and maintenance of industrial 

factilities and transportation systems; urbanization; city planning and zoning; changes to public facilities 

such as water, sewer, educational, and health facilities; changes to military bases and reserves; changes in 

population density; changes in State and Federal land-use regulations; and changes in non-OCS-related 

demands for water transportation systems and ports. Given the overwhelming contribution of these nonOCS-related factors to the cumulative impacts on land use and coastal infrastructure and the small 

incremental contribution of the CPA proposed action, the cumulative impacts on land use and coastal 

infrastructure are also expected to be minor. 
4-376 Central Planning Area Supplemental EIS 

4.1.1.21.2. Demographics 

In light of the recent DWH event, BOEM 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 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), BOEM anticipates that there will not be 

any substantial long-term population and demographic changes. However, BOEM 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 outmigration 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 BOEM 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 BOEM 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 BOEM 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 BOEM 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 
Description of the Environment and Impact Analysis 4-377 

comprise the 13 BOEM-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 

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, over the long term, 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 longterm 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. 
4-378 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, BOEM 

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. Job 

creation is analyzed in Chapter 4.1.1.21.3.2. The identified increase in employment is expected to be 

met primarily with the existing population and labor force, and it would not significantly impact the 

population, with the possible 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 may cause short-term population movements as individuals seek employment 

related to the event or have their existing employment displaced during the event. Such population 

movements tend to be relatively small and short term. The economic impacts of an accidental event 

(Chapter 4.1.1.21.), 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 
Description of the Environment and Impact Analysis 4-379 

individual sections. Therefore, 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. 

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. 

Summary and Conclusion 

Accidental events may cause short-term population movements, but they would not be expected to 

affect demographic characteristics as a whole in the affected area. 

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) as a reasonable approximation 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, BOEM 

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. 
4-380 Central Planning Area Supplemental EIS 

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 would likely continue throughout the analysis period. 

Race and Ethnic Composition 

Cumulative activities are projected to leave the racial distribution of the analysis area 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 in comparison with other factors influencing population growth, such as the status of the overall 

economy, fluctuations in workforce, net migration, and changes in income. 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, BOEM 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, 

BOEM 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. Short-term 

employment impacts and potential long-term employment impacts related to the DWH event in general 

and to 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. While there remains some uncertainty regarding the 

economic impacts of the DWH event, and this incomplete or unavailable information may be relevant to 

reasonably foreseeable significant impacts, BOEM does not believe that this incomplete information is 

essential to a reasoned choice among alternatives. Many of these potential impacts are discussed in the 

chapters cited above, and any individual lease sale is expected to have only a small impact on 

employment and other economic factors in the Gulf. 

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. 
Description of the Environment and Impact Analysis 4-381 

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 

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 BOEM 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 BOEM 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 BOEM 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 BOEM 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 BOEM-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 in terms of levels of employment for the individual states. 

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 the Wealth Index. 
4-382 Central Planning Area Supplemental EIS 

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 

(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, BOEM 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 makeup. 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. For example, the extent 

to which the recreational fishing and commercial fishing industries will recover will depend, in part, on 

how the fish populations in the Gulf of Mexico evolve following the spill. More information on the 

impacts of the DWH event on fishing activity can be found in Chapter 4.1.1.17 (commercial fishing) and 

Chapter 4.1.1.18 (recreational fishing). 

On May 6, 2010, Secretary Salazar announced a deepwater drilling suspension to last through the 

month; however, it was extended 6 months to November 30, 2010. The May suspension 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 suspensions 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 

suspensions 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 
Description of the Environment and Impact Analysis 4-383 

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 suspensions 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, during the peak of 

response efforts, more than 45,000 personnel were working on the response effort (RestoreTheGulf.gov, 

2011a). 

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 suspensions on the Gulf Coast 

economy in September found that there had not been large increases in unemployment. Recipients of 

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 

suspensions, 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. 

The suspension was lifted in its entirety on October 12, 2010, and new 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 1 of 11 drillships were working (Greenberg, 2010). Day rates 

for large, deepwater, supply vessel operators dropped from an average $14,787 a day in October 2010 to 

$9,920 in March 2011, and utilization fell from 89 percent to 78 percent (Greenberg, 2011). In March 

2011, Gulf rig activity was up a net five rigs, primarily due to jackup rigs going to work as more shallowwater drilling permits were issued. Rig utilization was at 56.5 percent (Greenberg, 2011). Deepwater 

drilling activity is expected to increase as BOEM has awarded deepwater drilling permits to eight 

operators during March 2011. As of December 2010, only three deepwater rigs had exited the Gulf since 

the deepwater suspensions were 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 loss of 1,500 jobs (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 suspensions have not triggered the significant economic impacts that were originally 

forecasted (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. 
4-384 Central Planning Area Supplemental EIS 

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 increased demand for assistance in the affected areas (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 (Dezember 2010). Shallowwater 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 

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, official 

communication, 2010). 

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). 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. 

Information regarding the impacts of the DWH event on the region’s economy and employment is 

still being developed and compiled. However, while this incomplete or unavailable information may be 

relevant, it would not be essential to a reasoned choice among alternatives. The incremental impact of the 

proposed action would be small (<1%) even in light of how the DWH event changed the economic 

baseline. The expected incremental effects from the proposed action would occur 3-7 years from the 

proposed lease sale and would likely occur long after the impacts to the economy from the DWH event 

are stabilized. In any event, the existing data indicate that the DWH event did not cause a significant 

change to the economic baseline, except potentially in the short term. 

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. 
Description of the Environment and Impact Analysis 4-385 

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. 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, 

BOEM 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, BOEM 

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, 

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 
4-386 Central Planning Area Supplemental EIS 

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 BOEM 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. 

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 
Description of the Environment and Impact Analysis 4-387 

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, BOEM 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 BOEM-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 BOEM-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 

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 BOEM does expect some employment will be 

met through in-migration; however, this level is projected to be small and localized and, thus, BOEM 

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 would 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 

LA-3, 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 a 

minimal incremental contribution when compared with non-OCS energy-related factors, translating to 

<1 percent to the employment level in any of the EIA’s. 
4-388 Central Planning Area Supplemental EIS 

4.1.1.21.4. Environmental Justice 

The BOEM 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 BOEM 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, development, 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, development, extraction, and production. An extensive upstream support infrastructure 

system exists to 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 bulk-storage 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 BOEM decisionmaking, and BOEM 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 BOEM’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. 

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 
Description of the Environment and Impact Analysis 4-389 

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 more than 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 BOEM 

focuses on counties/parishes with a high or medium concentration of OCS-related infrastructure and 

defines minority populations as those counties/parishes with a higher percentage of their population that is 

minority relative to their respective State averages. Because U.S. Census data aggregated at the 

county/parish level are very broad, this environmental justice analysis also considers population 

distributions at the smaller, more detailed census tract level to assess relationships between OCS leasing 

effects and geographic distributions of minority populations. While this allows for a consistent metric for 

all Gulf States, it is important to keep in mind that Texas’ minority population makes up more than half of 

the State at 54.67 percent. Because U.S. Census data aggregated at the county/parish level are very broad, 

this environmental justice analysis also considers population distributions at the smaller, more detailed 

Census tract level to assess relationships between OCS leasing effects and geographic distributions of 

minority and low-income populations, 

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 

parishes based on U.S. Census data from 2010 (USDOC, Census Bureau, 2010) and on a BOEM-funded 

study on Gulf Coast OCS infrastructure (Kaplan et al., in preparation). 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 

BOEM-funded study (Hemmerling and Colten, in preparation), 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 
4-390 Central Planning Area Supplemental EIS 

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 Kaplan et al. 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, 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 

have high concentrations of oil-related infrastructure. Damage to Mississippi and Alabama coastal areas 

was less severe, but the National Weather Service reported 14 confirmed tornadoes from Biloxi, 

Mississippi, to Mobile, Alabama. 

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, 

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 
Description of the Environment and Impact Analysis 4-391 

(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 due to 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 lowincome 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 since 1956 (Liu and Plyer, 2010). 

Besides 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 crisis 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 Related to 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 determined largely by the 
4-392 Central Planning Area Supplemental EIS 

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. 

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). Information regarding the reasonably foreseeable impacts of the DWH event remains incomplete 

or unavailable at this time. Studies regarding environmental justice concerns in light of the DWH event 

are only in their infancy, and it may be years before data are available and certainly not within the 

timeframe of this NEPA analysis. Although most criteria related to environmental justice may not be 

essential to a reasoned choice among the alternatives, health impacts would generally be essential. 

Nevertheless, long-term health studies are pending and may not be available for use for several years or 

longer. Other studies that are ongoing may help to inform issues relating to subsistence and other 

indigenous reliance on natural resources. This information is unavailable and unobtainable at this time, 

regardless of costs. In its place, the subject-matter experts have used credible information that is available 

and applied it using accepted socioeconomic methodologies. What credible scientific information is 

available was applied using accepted scientific methodologies in the health analysis below. 

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 

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 
Description of the Environment and Impact Analysis 4-393 

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 influence. 

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 BOEM 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 CPA and 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. The 0-1 pipeline landfalls and 0-1 processing facilities that may result from the CPA 

proposed action are likely to be sited in existing industrial areas, and therefore would not be expected to 

raise new environmental justice concerns. 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 BOEM 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 

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 
4-394 Central Planning Area Supplemental EIS 

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. An Agency-funded study compared the 

percentage of different minority populations within an affected area with the percentage of that population 

for the State (Hemmerling and Colten, 2003). 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 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. An entire 

proposed lease sale usually represents <1 percent of the total current permitted landfill capacity in the 

GOM economic impact area. The BOEM 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. 

See Chapter 4.1.1.21.3 for a discussion of employment projections as a result of the proposed lease sale. 

As has been the case with several prior lease sales, Lafourche Parish, Louisiana, is likely to experience 

the greatest concentration of these benefits. The BOEM 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 
Description of the Environment and Impact Analysis 4-395 

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 BOEM 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 events 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. 

Human Impacts from Oil Spills 

While it is still too early to determine the long-term impacts that may result from the DWH event, 

anecdotal evidence from media coverage and public responses to phone survey studies suggest possible 

trends that may demonstrate that low-income and minority communities were more sensitive to the DWH 

event. Impacts, such as loss of income from the NOAA fishing closures and drilling suspensions, were 

partially mitigated by the Gulf Coast Claims Facility and Gulf businesses’ efforts to maintain payrolls. 

The NOAA fishing closures may have impacted low-income or minority communities if they lacked an 

alternative for the loss of access to subsistence resources or performance of traditional activities. While 

these impacts were concentrated in Louisiana and Alabama with regard to the DWH event, they may be 

indicative of expected impacts should another catastrophic spill occur in the future. 
4-396 Central Planning Area Supplemental EIS 

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) 

found that cultural differences could play 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 April 29, 2011, are divided by state and at 

what stage the claimant is within the claims process. A total of 507,965 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. 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. Impacted industries may 

employ low-income and/or minority workers, and as a result, this analysis will consider both businesses 

and individuals within a parish or county because both could result in potential environmental justice 

consequences. 

There is no observable relationship between low-income or high-minority communities and the 

number of claims. Generally, parishes and counties directly along the Gulf Coast had a higher number of 

individuals and businesses claiming losses because of the DWH event. As discussed in Chapter 

4.1.1.21.4.1, the DWH event had differential impacts along the Gulf Coast. Some county and parish 

coastlines received oil and were host to disruptive cleanup efforts. Others only received DWH waste or 

were impacted economically because of fishing closures or consumer perception, which is discussed in 

greater detail in “Tourism and Recreation” in Chapter 4.1.1.19. Figure 4-20 displays the distribution of 

the GCCF Program’s claimants and the average amount paid to each claimant by county/parish. Several 

high- or medium-OCS infrastructure counties/parishes of environmental justice concern had high 

numbers of residents, workers, or both claiming losses. Individual claimants could claim damages based 

on removal and cleanup costs, real or personal property, lost earnings or profits, loss of subsistence use of 

natural resources, physical injury or death, or other claims. In Mobile County, Alabama, the GCCF 

Program awarded a little over $275 million to 22,000 claimants. In Florida, 1,273 claimants were 

awarded close to $11 million in Miami-Dade County, and 1,876 claimants were awarded close to 

$20 million in Hillsborough County. In Louisiana, a little over 50,000 claimants were awarded a total of 

$441 million in Orleans Parish; 3,362 claimants were awarded a total $115,651,040 in Plaquemines 

Parish; 4,082 claimants were awarded close to $60 million in St. Bernard Parish; and 3,387 claimants 

were awarded close to $72 million in Lafourche Parish. Harrison County, Mississippi, which 

encompasses Biloxi and Gulfport and which is home to a 33 percent minority population, had 

17,901 claimants who were awarded $204 million.
Description of the Environment and Impact Analysis 4-397 

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. A representative sample of affidavits submitted to the Gulf Coast Claims Facility (responsible 

for administrating DWH event claims) indicates that Louisiana commercial fishermen customarily take 

home approximately 5-15 percent of their total catch for subsistence use (United Louisiana Vietnamese 

American Fisherfolks, 2010). 

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). Following negotiations with nonprofit lawyers and community 

advocates, the Gulf Coast Claims Facility developed a new method for calculating subsistence claims 

beginning on March 28, 2011 (Hammer, 2011). The GCCF said it would use scholarly studies, such as 

the United Louisiana Vietnamese American Fisherfolks white paper (2010), to determine consumption 

amounts of different groups of commercial fishers and so-called “true subsistence fishermen,” namely 

affected Indian tribes like the United Houma Nation. As of April 27, 2011, a total of 40 claimants had 

been awarded close to $384,000. Most claimants received between $0.01 and $5,000. The BOEM is 

currently funding 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 the available 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. 

It is important to note that the toxicity of dispersed oil in the environment will depend on many 

factors, including the effectiveness of the dispersion, mixing energy, type of oil, the degree of weathering, 

type of dispersant, temperature, salinity, duration of exposure, and degree of light penetration into the 

water column (NRC, 2005). Data results for air quality and water quality samples taken during and after 
4-398 Central Planning Area Supplemental EIS 

the DWH event are summarized in Chapters 4.1.1.1 (air quality) and 4.1.1.2 (water quality). The BTEX, 

the collective name for benzene, toluene, ethyl benzene, and xylenes, are the volatile aromatic compounds 

often found in discharges, and petroleum oils and products. In well-flushed, dispersive and deeper water 

environments of the Louisiana coast, the BTEX chemical contaminant signal may be negligible as close 

as 50-100 m (164-328 ft) from the point of discharge (Rabalais et al. 1991). Avens et al. (2011) analyzed 

airborne BTEX concentrations from the DWH event and found that 99 percent of their measurements 

taken prior to capping the well were lower than the U.S. Occupational Safety and Health Administration 

Permissible Exposure Limits (PEL’s) for BTEX (Avens, 2011). The researchers found that the magnitude 

of these data were similar to measurements from ships not involved in oil-slick remediation. There has 

also been concern regarding the use of the dispersants such as COREXIT 9500, which works the same 

way dishwashing liquid works on grease, but it is also toxic at 2.61 ppm. Dispersants in use today are 

much less toxic than early-generation dispersants, and an abundant literature exists on the toxicity of 

COREXIT dispersants currently approved for use in the United States (NRC, 2005). The USEPA 

monitoring data have so far shown that the mix of Louisiana light crude oil and COREXIT 9500 was no 

more or less toxic than the other available alternatives, displaying no biologically significant endocrine 

disrupting activity, and it did not result in a presence of chemicals that surpassed human health 

benchmarks (USEPA, 2010l). The USEPA, in coordination with the U.S. Dept. of Health and Human 

Services, developed benchmarks to assess potential human health risks from exposure to oil-contaminated 

water. Human health benchmarks are based on potential cancer and noncancer risks associated with 

exposure to oil-contaminated water in the Gulf. Where applicable, the benchmarks account for both skin 

contact and incidental ingestion of water by a child swimmer, assuming 90 hours of exposure. The OSAT 

report on water column, sediment, and beach conditions explains that “Benchmarks (based on dissolved 

seawater concentrations) for the individual compounds are used to explain the relevance of measured 

concentrations of individual compounds. . . These benchmarks are based on available biological effects 

data and are conservatively designed to protect aquatic life’ (OSAT, 2010, p. 13). The OSAT sampling 

found “No exceedance of EPA’s dispersant benchmarks” (OSAT, 2010, p. 2). Of the 4,850 water and 

412 sediments samples collected in the nearshore zone between May 13 and October 20, 2010, “[o]nly 

66 samples (60 water and 6 sediment) had detectable levels of dispersant-related chemicals. DPnB was 

the most common detectable dispersant-compound and was found in 57 of the 60 water samples; 

however, concentrations never exceeded 3ug/L (cf. EPA screening level of 1 mg/L)” (OSAT, 2010, 

p. 25). It is too early to know of any possible long-term health effects from exposure to either the DWH 

event’s oil or dispersants (although the National Institutes of Health has proposed such a study). 

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 April 27, 

2011, 85 claimants had been paid a total of $412,494. 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 (USEPA, 2010m). Tulane University’s Disaster Resilience Leadership 

Academy, along with the nonprofit health advocacy organization, the Louisiana Bucket Brigade, 

conducted a door-to-door health and economic impact survey in coastal Louisiana (Jefferson, Terrebonne, 

St. Bernard, and Plaquemines Parishes) during the summer of 2010 (Louisiana Bucket Brigade, 2010). 

While no medical tests were administered and this type of survey likely suffers from self-selection bias, it 

does provide us a snapshot of what residents reported and their perceptions of exposure. Surveyors asked 

a total of 954 people a series of questions regarding their exposure to the spill event, abnormal health 

symptoms, and medications sought to treat ailments. Of those surveyed, 46 percent reported believing 

that they were exposed to oil or dispersant; of those, 72 percent reported experiencing one symptom. 

Sudden onset symptoms included nausea, dizziness, and skin irritation. The Centers for Disease Control 

and Prevention state that an “occasional brief contact with a small amount of oil will do no harm. 

However, some people are especially sensitive to chemicals, including the hydrocarbons found in crude 

oil and petroleum products. They may have an allergic reaction, or develop dermatitis or a skin rash, 

even from brief contact with oil” (Centers for Disease Control and Prevention, 2010). 
Description of the Environment and Impact Analysis 4-399 

Sathiakumar’s review (2010) 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, 2010b). 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). 

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 vice versa. Facilities located on the coasts of the CPA may provide support for 

offshore activities on the WPA, and vice versa. Oil and chemical spills on the CPA may be carried by 

winds and currents to the coasts of the WPA, and vice versa. As a result, a discussion of a potential 
4-400 Central Planning Area Supplemental EIS 

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 analyses of 

offshore oil spills  1,000 bbl, 1,000 bbl, and coastal spills associated with the CPA proposed action are 

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 BOEM 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 and 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. Harris County, for example, has clusters of low-income minority communities along the 

Houston Ship Channel, which is a major conduit for OCS product and would likely receive any captured 

oil from an accidental event. Additionally, the 2000 Census found that 13.9 percent of Texans spoke 

English less than “very well” (USDOC, Census Bureau, 2003). In 2005, Texas joined Hawaii, New 

Mexico, and California as majority-minority states. The fastest growing key segment of the population is 

Hispanics (USDOC, Census Bureau, 2005, in Green, 2008). While low-income and minority populations 

already run the danger of being disenfranchised from a response effort and any resulting compensation for 

losses sustained because of an accidental event, limited English proficiency will likely create greater 

obstacles. The Deepwater Horizon Incident Command Center, which collected and distributed news and 

information from all Federal, State, local, and private responders, which is as of summer 2011 

(RestoreTheGulf.gov, 2011c), has translations in the following languages: Cambodian, Croatian, 

Spanish, French, Korean, Greek, Laotian, Russian, Thai, and Vietnamease. The Gulf Coast Claims 

Facility website and other Gulf Coast Claims Facility’s resources can be translated into Spanish, Laotian, 

and Vietnamese, and it also has utilizes translators to assist limited English proficiency claimants.

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 

concern for human health because, while dispersants are a relatively common product used to clean and 
Description of the Environment and Impact Analysis 4-401 

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 effects on low-income and 

minority communities. 

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 may be 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 BOEM will continue to monitor these populations over time and to document short- and long-term 

DWH event impacts, if any. 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. 

As such, information regarding reasonably foreseeable impacts of the DWH event remains incomplete or 

unavailable at this time. Studies regarding environmental justice concerns in light of the DWH event are 

only in their infancy, and it may be years before data are available and certainly not within the timeframe 

of this NEPA analysis. Although most criteria related to environmental justice may not be essential to a 

reasoned choice among the alternatives, health impacts would generally be essential. Nevertheless, longterm health studies are pending and may not be available for use for several years or longer. Other studies 

that are ongoing may help to inform issues relating to subsistence and other indigenous reliance on natural 

resources. This information is unavailable and unobtainable at this time, regardless of costs. In its place, 

the subject-matter experts have used credible information that is available and applied it using accepted 

socioeconomic methodologies. 

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 communities 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. 
4-402 Central Planning Area Supplemental EIS 

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 than other 

groups to the consequences of an oil spill, such as interruptions to municipal services or fisheries 

closures, and they may be less equipped to cope with these consequences. 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 BOEM 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 would result in only minor economic changes. 

Generally, effects would be widely yet thinly distributed across the Gulf Coast and would 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 
Description of the Environment and Impact Analysis 4-403 

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 would 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 would generate 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). Up to one new pipeline and up to 

one onshore facility are projected for the proposed action. 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 

permit approval and concurrence. The BOEM 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, BOEM 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 would 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, 2001c), 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 
4-404 Central Planning Area Supplemental EIS 

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. 

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 BOEM 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, 2004). 

Downstream Activities 

Existing onshore 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 BOEM 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 BOEM cannot predict and does not regulate 

the siting of future gas processing plants. The BOEM 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 
Description of the Environment and Impact Analysis 4-405 

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 lowincome or minority communities. 

Public Health 

The Natural Resources Defense Council and the National Disease Clusters Alliance identify and track 

disease clusters in the U.S. An unusually large number of people sickened by a disease in a certain place 

and time is known as a “disease cluster” (Natural Resources Defense Council and the National Disease 

Clusters Alliance, 2011). The underlying causes of a disease cluster can be genetic, environmental, or 

both. The State of Louisiana’s Center for Environmental Health defines an environmental disease cluster 

when evidence of a known connection between the hazard and the disease or health outcome of concern is 

established (Louisiana Dept. of Health and Hospitals, 2008). The Natural Resources Defense Council and 

the National Disease Clusters Alliance identified disease clusters in 13 states, with four clusters in 

Louisiana and three clusters in Florida. The four locations in Louisiana include Mossville in Calcasieu 

Parish, Amelia in St. Mary Parish, Coteau in Iberville Parish, and New Orleans in Orleans Parish. The 

Agency for Toxic Substances and Disease Registry identified a cluster of breast cancer in an urban census 

tract at the Agricultural Street Landfill Superfund Site in New Orleans in a 2003 study (Natural Resources 

Defense Council and the National Disease Clusters Alliance, 2011). According to the Agency for Toxic 

Substances and Disease Registry, the site and the neighborhood is contaminated with metals, PAH’s, 

volatile organic compounds, and pesticides. Through 1986-1987, researchers from Louisiana State 

University’s Medical School identified a cluster of neuroblastoma, a type of brain cancer adjacent to a 

marine shale processor plant. There was insufficient data to link a hazardous waste incinerator at the 

marine shale processor plant, but in 2007 the owners paid the State government a settlement to close and 

remediate the site. The three disease clusters in Florida were unrelated to OCS activities, but they were 

industrial in nature (Natural Resources Defense Council and the National Disease Clusters Alliance). 

Due to the distance of OCS Program activities offshore, routine events related to the proposed action 

would not be expected to affect public health in these communities. Both of these sites are far from a 

coastline where an OCS oil spill could directly impact these people, but it is not unlikely that members of 

these communities could participate in cleanup efforts. An environmental justice analysis seeks to 

identify populations that, through a variety of mechanisms, may become disproportionately impacted by 

the proposed action and its associated activities. Research such as this suggests that there may be a 

correlation between downstream oil and gas processing (after any OCS Program-related oil and gas 

comes ashore) and diminished health in adjacent populations. As a result, communities appearing to have 

disease clusters are probably more sensitive to potential impacts in a cumulative scenario. 

Waste 

Based on operator data provided in filed plans, BOEM estimates that there is an average of 2,000 ft3

(57 m3

) of trash and debris generated per exploration well drilled, 102 ft3 (3 m3) of trash and debris 

generated per development well drilled, and 1,000 ft3

 (28 m3) of trash and debris generated per year per 

manned platform of its 25-year life (Dismukes et al., 2007). An entire proposed lease sale usually 

represents <1 percent of the total current permitted landfill capacity in the GOM economic impact area. 

Because of technological improvements on how waste is compacted, landfill capacity has increased, with 

Texas landfills having increased useful life by 19 years from the mid-1990’s to 2005. Drilling muds and 

wastewater streams can be used as landfill cover, and landfills will often accept these materials at a 

reduced price or even at no charge (The Louis Berger Group, 2004). The occurrence of hazardous 

offshore, oil-field waste is minimal and infrequent. Industry representatives contacted for a BOEM study 

indicated that the need for hazardous storage could occur as infrequently as once in 5 years for a typical 

offshore facility with drilling and production activities (Dismukes et al., 2007). 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 
4-406 Central Planning Area Supplemental EIS 

cumulative case (The Louis Berger Group, Inc., 2004). Therefore, no changes in impacts to minority and 

low-income communities are expected. 

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 

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). 

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. 

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 
Description of the Environment and Impact Analysis 4-407 

conducted by a team of LSU sociologists during July 2010 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). Longitudinal epidemiological 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). Information regarding the reasonably foreseeable impacts of the DWH event remains incomplete 

at this time. Although most criteria related to environmental justice may not be essential to a reasoned 

choice among the alternatives, health impacts would generally be essential. Studies regarding 

environmental justice concerns in light of the DWH event are only in their infancy, and it may be years 

before data are available and certainly not within the timeframe of this NEPA analysis. Studies are 

ongoing and may help to inform issues relating to subsistence and other indigenous reliance on natural 

resources. This information is unavailable and unobtainable at this time, regardless of costs. In its places, 

the subject-matter experts have used credible information that is available and applied it using accepted 

socioeconomic methodologies. Although most criteria related to environmental justice may not be 

essential to a reasoned choice among the alternatives, health impacts may be essential. Nevertheless, 

long-term health studies are pending and may not be available for use for several years or longer. What 

credible scientific information is available was applied using accepted scientific methodologies. 

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 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 
4-408 Central Planning Area Supplemental EIS 

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 added to existing State and Federal 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 BOEM 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 organisms found on the seafloor 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 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) 
Description of the Environment and Impact Analysis 4-409 

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 (Rhodes, 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). 

 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. 
4-410 Central Planning Area Supplemental EIS 

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 

(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.). 
Description of the Environment and Impact Analysis 4-411 

 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 

(Byrnes 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). 

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: hypoxic to 

anoxic bottom conditions on the Louisiana-Texas continental shelf 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). 
4-412 Central Planning Area Supplemental EIS 

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. See Chapters 4.1.1.2.1.1 and 4.1.1.2.2.1 for a detailed description of 

the Gulf of Mexico’s hypoxic zone. 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). See Chapters 4.1.1.2.1.1 and 4.1.1.2.2.1 for a 

detailed description of runoff impacts in the Gulf of Mexico. 

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 

environmental threats tend to produce communities with lower biodiversity and biomass since longerlived species tend to be eliminated. 

It is also important to note that the Gulf floor is influenced by many sources of anthropogenic 

pollution and natural oil seeps that contribute PAH’s to the sediments (MacDonald, 2002). Benthic 

organisms experience low-level hydrocarbon exposure through all of these inputs. For example, PAH’s 

have been detected in sediments throughout the Gulf seafloor, these are from natural seeps as well as 

other human inputs (OSAT, 2010). The PAH’s were detected in 321 of the 388 samples collected from 

many different sources for the OSAT (2010) study. 

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. Water and sediment samples collected 

during and after the spill were analyzed as part of the OSAT (2010) report. A handful of samples 
Description of the Environment and Impact Analysis 4-413 

collected off the Gulf Coast did reveal some PAH’s as a result of the DWH event; however, very few of 

the total number of water or sediment samples collected revealed exceedences of USEPA’s aquatic life 

benchmarks (OSAT, 2010). There were 6 water samples out of 481 collected that exceeded USEPA’s 

chronic toxicity benchmarks for PAH’s in the offshore waters (>3 nmi [3.5 mi; 5.6 km] offshore to the 

200-m [656-ft] bathymetric contour), all of which occurred within 1 m (3 ft) of the water surface (OSAT, 

2010). There were 63 samples collected from deep water (>200 m; 656 ft) out of 3,605 samples collected 

that exceeded USEPA’s aquatic life benchmarks for PAH’s (OSAT, 2010). Exceedances occurred near 

the water surface or in the deepwater plume within 70 km (43 mi) of the well. Oil detected in the 

subsurface plume was in water depths between 1,100 and 1,300 m (3,609 and 4,265 ft) and was moving 

southwest along those depth contours (OSAT, 2010). No sediment samples collected offshore (>3 nmi 

[3.5 mi; 5.6 km] offshore to the 200-m [656-ft] depth contour) and seven sediment samples collected in 

deep water (>200 m; 656 ft) exceeded USEPA’s aquatic life benchmarks for PAH exposure (OSAT, 

2010). All chronic aquatic life benchmark exceedances in the sediment occurred within 3 km (2 mi) of 

the well and samples fell to background levels at a distance of 10 km (6 mi) from the well (OSAT, 2010). 

Refer to the “Sediment Water Interface Exposure” and “Sedimented Oil (Oil Adsorbed to Sediments)” 

sections in this chapter for further details on sediment studies related to the DWH event. Dispersants 

were also detected in waters off Louisiana, but they were below USEPA benchmarks of chronic toxicity. 

No dispersants were detected in sediment on the Gulf floor (OSAT, 2010). Benthic communities in the 

CPA located within 70 km (43 mi) of the well, therefore, may have been impacted by PAH’s in the water 

column or sediment, as they are located within the radius of benchmark exceedances. However, the entire 

70-km (43-mi) radius is not expected to be affected, as samples with exceedances were patchy and few. 

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 Gulf of Mexico seafloor. Although approximately 

4.64 million bbl of oil were released into the Gulf waters, not all of that oil reached the seafloor. Reports 

estimated that, as of November 2010, 23-26 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; The Federal Interagency Solutions 

Group, 2010). Currently, the bulk deposits of oil have been removed from beaches, and the remaining oil 

that reached shorelines has been buried (e.g., through wave action and hurricanes) and is weathering over 

time (OSAT-2, 2011). Oil that has been deposited on the floor of the Gulf has also weathered (OSAT, 

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. 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. 

The weathering process began as the oil traveled from the well to the sea surface or horizontally in 

the subsea plume. The parent oil became depleted in its lower molecular weight PAH’s (which are the 

most acutely toxic components), and the longer the oil spent in the water column or at the sea surface, the 

more diluted and weathered it became (Brown et al., 2010; Eisler, 1987; The Federal Interagency 

Solutions Group, 2010; OSAT-2, 2011). The greatest concentrations of oil that settled to the seafloor are 

expected to be near the wellhead and to 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. Infaunal benthic organisms may have been exposed to 

hydrocarbons that settled to the seafloor on sediments and detrital material, epifaunal benthic organisms 

may have been exposed to oil in the subsea plume that traveled along depth contours, and mobile benthic 

organisms that use the water column for parts of their life cycle may have been exposed to hydrocarbons 

at the sea surface. 

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 

close to the well, and lower concentration exposures may have resulted in sublethal impacts to individuals 

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. 

A majority of the impacts to soft-bottom benthic communities in the CPA will be a result of low-level 

or long-term exposure to dispersed sedimented oil. Impacts to benthic communities may include reduced 
4-414 Central Planning Area Supplemental EIS 

recruitment success and shift in community dominance. The PAH’s were detected in sediments 

throughout the Gulf seafloor, from both the MC 252 oil and other undetermined sources, in 321 of the 

388 samples collected for the OSAT (2010) study; however, the PAH concentrations were below 

USEPA’s aquatic life benchmarks. A relatively small portion of the entire CPA is anticipated to have 

been impacted by the MC 252 oil, and discussions of possible impacts as a result of the spill are included 

in this section. 

Water Column and Sediment Water Interface Exposure 

A portion of the oil that was released from the well rose to the sea surface, but because the oil was 

ejected under pressure, oil droplets became 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 <100 μm (0.0036 in) in diameter remained in the water column for several months (Joint 

Analysis Group, 2010a). Oil detected in the subsurface plume was between 1,100 and 1,300 m deep 

(3,609 and 4,265 ft) and was moving southwest along those depth contours (OSAT, 2010). Epibenthic 

organisms that protrude above the sediment or those that feed at the sediment water interface may have 

been exposed to oil droplets in the water column or at the seafloor/water interface near the subsea plume. 

Concentrations of dispersed and dissolved oil in the subsea plume were reported to be in the parts 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. Oil concentrations ranged from <1 to 3 ppm at approximately 10 m (33 ft) below the sea 

surface (McAuliffe et al. 1981a; Lewis and Aurand, 1997). 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 strata 1,100-1,400 m (3,609-4,593 ft) below the sea surface, where the subsea plume occurred, 

however, was a place that scientists recorded visible impact to benthic organisms. A recent report 

documents damage to a deepwater (1,400 m; 4,593 ft) coral (gorgonian) community 11 km (7 mi) to the 

southwest of the well, which is the direction of travel of the subsea oil plume. 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 

and may have been the result of contact with the subsea oil plume (Fisher, 2010; USDOI, BOEMRE, 

2010j). See Chapter 4.1.1.10 for a detailed description of the affected deepwater coral community. 

Although coral was damaged 11 km (7 mi) from the well, sediment cores collected from this location 

did not contain levels of oil that exceeded USEPA’s aquatic life benchmarks (OSAT, 2010). Based on 

the samples collected by OSAT (2010) and USEPA’s aquatic life benchmarks, infaunal benthic organisms 

should not have experienced fatality as did the deepwater corals. A probable explanation for the 

detrimental impacts to corals, in the absence of USEPA’s aquatic life benchmark exceedances in the 

sediment, is that the coral community forms structures that protrude up into the water column that would 

be affected by a passing oil plume in a way that a typical smooth soft bottom would not. Also, even 

though the sediment samples in the area did not exceed USEPA’s aquatic life benchmarks, the corals 

were within a 70-km (43-mi) radius where water samples did exceed USEPA’s aquatic life benchmarks 

(OSAT, 2010). Therefore, an 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, not affecting the organisms 

below the sediment surface. Dispersed oil, however, may come in contact with benthic organisms that 

move into the water column or at the sediment/water interface. Also, 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, which corals cannot do. 

Benthic organisms in the CPA, especially those emergent in the water column, >70 km (43 mi) from 

the well should not have been exposed to lethal concentrations of oil because oil in the plume was diluting 

with distance from the well and was decreasing in concentration with time and because there were no 

exceedances of USEPA’s aquatic life benchmarks for PAH’s measured in the water column more than 
Description of the Environment and Impact Analysis 4-415 

70 km (43 mi) from the well (OSAT, 2010). Also, tiny droplets of oil dissolved in the water column as 

they rose to the sea surface due to the depth and pressure of their release (The Federal Interagency 

Solutions Group, 2010). The lower molecular weight aromatic compounds (those with the greatest 

toxicity) were the compounds that dissolved most readily, and dissolution continued with continued 

exposure to uncontaminated surrounding water (The Federal Interagency Solutions Group, 2010; Brown 

et al., 2010; Eisler, 1987). The dissolution of oil into surrounding water allowed for dilution that further 

decreased the probability that concentrated oil could impact organisms farther than 70 km (43 mi) from 

the well. 

Water Column Exposure 

Several commercially important benthic organisms (crabs and shrimp for example) utilize the water 

column for part of their life cycle and may have been exposed to petroleum hydrocarbons in the water. 

Since petroleum hydrocarbon concentrations were higher near the water surface and closer to the well, the 

greatest impact to any mobile benthic organisms would be at the water surface with increasing exposure 

closer to the well. Organisms that are distanced from the well have a much reduced probability of 

contacting surface oil, but since currents can transport larvae great distances, there is a possibility that 

larvae in the water column may have been exposed to oil. 

The larval zoea of blue crab develop during the spring and early summer in offshore waters, where 

they are subject to distribution by currents before the megalopal stage moves into coastal habitat in late 

summer and early fall (Perry and McIlwain, 1986). Brown shrimp spawn offshore in water depths 

between 18 and 137 m (59 and 450 ft) during two spawning peaks (September through November and 

April through May) in the northern GOM (Lassuy, 1983). Postlarval recruitment into estuaries may take 

several months (Lassuy, 1983). White shrimp spawn offshore from April to August, with peaks in June 

and July, and postlarvae move inshore to estuaries (Muncy, 1984). All three of these species spawned in 

offshore Gulf waters during the time of the oil spill, and their larvae may have been exposed to 

hydrocarbons in the water column. 

Newly recruited blue crabs and peneaid (white and brown) shrimp were collected from Alabama salt 

marshes after the spill and were shown to have declined in abundances as compared with the previous 

year (Moody et al., 2011). However, resident salt marsh species also declined in abundance, although 

overall species diversity in the marsh did not decline, indicating a possible interannual variability in 

recruitment success of several species rather than oil toxicity to offshore spawners (Moody et al., 2011). 

Analysis of water and sediment samples are necessary to determine if there was an oil spill-related impact 

to reduced recruitment in 2010 (Moody et al., 2011). Another study reported blue crab megalope 

recruitment from nine estuary locations between Galveston, Texas, and Apalachicola, Florida (Grey et al., 

2011a). Results indicated that the 2010 recruitment year did not appear to be substantially different from 

previous years; however, orange fatty droplets were observed inside the carapaces of some megalope and 

are under investigation (Grey et al., 2011a and 2011b). 

There are some data available on hydrocarbons and dissolved oxygen levels in the water column 

during the DWH event (Chapter 4.1.1.2, water quality). 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). Any water samples that had 

PAH concentrations that exceeded USEPA’s aquatic life benchmarks occurred within 1 m (3 ft) of the 

water surface and within 70 km (43 mi) of the wellhead (OSAT, 2010). 

The hydrocarbon concentrations measured in the water column after the DWH event 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. 

The available data suggest that, except for samples taken close to the well, the concentrations of oil in 

the water column were low and the oil was dispersed. These data suggest that benthic organisms in the 

CPA that were exposed to oil as a result of the DWH event were probably most affected close to the well 
4-416 Central Planning Area Supplemental EIS 

and the concentrations farther from the well were very low (in the part per million range or less), resulting 

in a much reduced impact. Even larvae exposed to hydrocarbons in the CPA, except for those close to the 

well, should have experienced low-level exposure. 

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; OSAT, 2010). 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 

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. See Chapters 4.1.1.2.1.1 and 4.1.1.2.2.1 for detailed descriptions of the coastal and 

offshore water quality in the GOM following the DWH event. 

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). In 2010, the 

“dead zone” was one of the largest measured, covering approximately 20,000 km2

 (7,722 mi2), and it 

affected both Louisiana and Texas waters (LUMCON, 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 adhering to and sedimenting with 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 
Description of the Environment and Impact Analysis 4-417 

toxic hydrocarbons. The greatest concentration of sedimented oil occurred close to the well, and oil 

dispersed over wider areas with lower concentrations as it traveled farther from the source (Haddad and 

Murawski, 2010; Joint Analysis Group, 2010a; OSAT, 2010). 

There is little direct data available on the impacts of the DWH event on benthic communities or 

benthic community structure on the seafloor of the Gulf of Mexico after this event. There are some data 

on the concentrations of hydrocarbons in sediments. The PAH’s were detected in sediment on the Gulf 

floor in almost every sample collected by OSAT (2010) offshore of Louisiana to Florida; however, not all 

of the PAH’s measured in sediment were a result of the DWH oil spill (OSAT, 2010). Only 7 of the 

388 samples collected in the offshore zone (>3 nmi [3.5 mi; 5.6 km] offshore to the 200-m [656–ft] depth 

contour) and in deep water (>200 m; 656 ft) were determined to have the MC 252 signature and exceeded 

USEPA’s chronic aquatic life benchmark (OSAT, 2010). These samples were collected within 3 km 

(2 mi) of the wellsite. Sediment PAH concentrations reached background levels within 10 km (6 mi) 

from the well (OSAT, 2010). These data indicate that impacts to soft-bottom benthic communities in the 

CPA should generally occur within 3 km (2 mi) of the well, possibly out to 10 km (6 mi) in areas where 

PAH’s were slightly elevated. 

The preliminary results of one study reported that sediment toxicity was greater near the wellhead 

than at a distance (Arismendez et al., 2011a). Toxic effects were reported to benthic organisms in 

laboratory exposures using sediment collected out to 25 and 50 km (16 and 31 mi) to the southwest of the 

wellsite (the direction of the subsea plume flow) (Arismendez et al., 2011b). Concentrations of oilcontaminated sediment required to kill 50 percent of the test populations ranged from 575.8 to 

94,699 mg/L, with the lower values occurring in sediments collected closer to the well (translating to 

higher toxicity) (Arismendez et al., 2011a). Another study, which looked at meiofauna collected 

throughout the GOM, from 2007 through 2010, from the Mexico border around to the tip of Florida, 

including areas affected by the oil spill, reported that meiofauna populations varied considerably within 

years (Romano and Landers, 2011). Variability from 2007 through 2010 was determined to be due to 

patchy distributions in meiofauna throughout the years rather than oil-spill related (Romano and Landers, 

2011). The results of these two studies indicate that impacts to benthos were localized and that the 

populations throughout the Gulf are more likely impacted by recruitment variability than toxic exposure, 

especially at great distances from sources of contamination. 

Also, some chemically dispersed surface oil may have reached the seafloor, but this is likely 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 adsorb 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 (<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 to decrease with distance from the wellhead (Lubchenco et al., 2010; Adcroft et al., 2010; Joint 

Analysis Group, 2010a). 

The presence of dispersants were detected in very few sediment samples (8 out of 775) collected from 

the seabed of the GOM between Louisiana and Florida nearshore (shoreline to 3 nmi [3.5 mi; 5.6 km] 

offshore), offshore (3 nmi [3.5 mi; 5.6 km] to 200-m [656–ft] depth contour), and in deep water (deeper 

than 200 m [656 ft]) after the DWH event (OSAT, 2010). Six of those samples were found in nearshore 

waters. Of the eight samples, there were no instances of dispersant levels in the sediment exceeding 

USEPA’s established aquatic life benchmarks for PAH (OSAT, 2010). Therefore, infaunal benthic 

organisms should not have experienced toxicity as a result of exposure to dispersants in the sediment. 
4-418 Central Planning Area Supplemental EIS 

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 were 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, especially within 3 km (2 mi) of the well, where 

PAH concentrations exceeded USEPA’s aquatic life benchmarks (OSAT, 2010). 

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). Opportunistic species, such as tube-dwelling polychaetes or oligochaetes, would be the first to 

appear. These species would occur within the first recruitment cycle of the surrounding populations and 

from species immigrating from surrounding stocks (Rhodes and Germano, 1982). These pioneering 

species would 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 perpetually in early successional stages (Gaston et al., 1998; Diaz and Solow, 1999). These 

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. The small footprint of impact was reported by OSAT (2010) where only 7 of 

the 388 sediment samples collected were determined to have the MC 252 signature and to exceed 

USEPA’s chronic aquatic life benchmark (OSAT, 2010). These samples were collected within 3 km 

(2 mi) of the wellsite. Sediment PAH concentrations reached background levels within 10 km (6 mi) 

from the well (OSAT, 2010). Additionally, there were no instances of dispersant levels in the sediment 

exceeding USEPA’s established aquatic life benchmarks for PAH (OSAT, 2010). In areas farther from 

the well where low levels of oil could 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 would behave the same way and weather similarly. 
Description of the Environment and Impact Analysis 4-419 

The Ixtoc oil spill in the Bay of Campeche, Gulf of Mexico, was much more on scale with the volume 

of oil as a result of the DWH spill 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 occurred with the DWH event, as indicated by the results of sediment testing (OSAT, 2010). 

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 

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 

would 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 would 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, such as the pioneering species described above 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 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 
4-420 Central Planning Area Supplemental EIS 

less stable and productive food source for higher trophic levels (Diaz and Solow, 1999). Exposure (to the 

extent it might have occurred) could result in slightly altered benthic communities with opportunistic 

species. Recolonization and immigration for successive communities would likely then either supplant or 

supplement these opportunistic species. 

Currently, there is only limited data available on potential impacts of the DWH event on soft bottoms 

in the CPA. This incomplete or unavailable information may be relevant to reasonably foreseeable 

significant impacts to Pinnacle Trend features. Relevant data on the status of Pinnacle Trend features 

after the DWH event, however, may take years to acquire and analyze. Much of this data is being 

developed through the NRDA process, which may take years to complete. Little data from the NRDA 

process have been made available to date. Therefore, it is not possible for BOEM to obtain this 

information within the timeframe contemplated in this Supplemental EIS, regardless of the cost or 

resources needed. In the place of this incomplete or unavailable information, BOEM subject-matter 

experts have used available scientifically credible evidence in this analysis applied using accepted 

scientific methods and approaches. The BOEM believes, however, that this incomplete or unavailable 

information is not essential to a reasoned choice among alternatives. Because soft bottoms are ubiquitous 

in the Gulf of Mexico, are not considered essential fish habitat, and are repopulated relatively quickly 

from neighboring communities when they are impacted, this incomplete or unavailable information is not 

likely to be essential to a reasoned choice among alternatives. 

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. Potential impact-producing factors 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 alterations to 

infaunal communities and 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. 

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 
Description of the Environment and Impact Analysis 4-421 

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. 

Structure placement and anchor damage from support boats and ships, floating drilling units, and 

pipeline-laying vessels are OCS oil- and gas-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). 

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 sweeps 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). 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). 

Another major impact of OCS-related construction 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). 

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 areas where currents are 

strong, cuttings may be so widely dispersed that they are not visible on the seafloor near the platform 

(Zingula and Larson, 1977). 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). 
4-422 Central Planning Area Supplemental EIS 

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 

(Zingula and Larson, 1977). A gradient of cuttings generally 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 likely 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. 

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. The shift back to fine-grained sediment 

can occur fairly rapidly as local marine sediment accumulates on top of the cuttings (Zingula and Larson, 

1977). 

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). 

The seafloor begins to change once drilling is completed. Piles of cuttings are often flattened within 

several months of the completion of drilling, and layers of sediment blanket them (Monaghan et al., 

1980). Observations recorded 8.5 months after drilling was completed at a site off Louisiana, indicated 

that marine sediment had covered over the cuttings deposits. In addition, the fauna present at the 

impacted site had similar species and abundance of organism to a nearby location that did not experience 

cuttings deposition (Zingula and Larson, 1977). Observations at another platform in the Gulf of Mexico 

indicated a complex benthic community, including burrowing organisms, 2 years after drilling was 

completed (Zingula and Larson, 1977). After 10-15 years, the cuttings themselves were not distinguished 

from surrounding sediments (Monaghan et al., 1977). As the cuttings break down, recolonization by 

benthic organisms increases. 

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 
Description of the Environment and Impact Analysis 4-423 

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 an increased but less successful reproductive effort 

paired with reduced 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). Although concrete information on the link of hydrocarbon contamination and benthic 

impacts would be relevant, it is not essential to a reasoned choice among alternatives. As described 
4-424 Central Planning Area Supplemental EIS 

below, there is scientificly credible information, applied using accepted scientific methodologies, 

regarding what the potential impacts to benthic communities may be from hydrocarbons and related 

contaminants. 

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). 

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 obtain 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 that 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) 
Description of the Environment and Impact Analysis 4-425 

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 

synthetic-based 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. 

Produced Waters 

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 because the elements in the produced water 

may remain in the water column or attach to particles and settle to the seafloor (Burns et al., 1999). A 

detailed description of the impacts of produced waters on water quality and seafloor sediments is 

presented in Chapter 4.1.1.2. 

Produced waters are rapidly diluted and impacts are generally only observed within proximity of the 

discharge point (Gittings et al., 1992a). Models have indicated that the vertical descent of a surface 

originating plume should be limited to the upper 50 m (164 ft) of the water column, and maximum 

concentrations of surface plume water have been measured in the field between 8 and 12 m (26 and 39 ft) 

(Ray, 1998; Smith et al., 1994). Plumes have been measured to dilute 100 times within 10 m (33 ft) of 

the discharge and 1,000 times within 103 m (338 ft) of the discharge (Smith et al., 1994). Modeling 

exercises showed hydrocarbons to dilute 8,000 times within 1 km (0.6 mi) of a platform and constituents 

such as benzene and toluene to dilute 150,000 and 70,000 times, respectively, within that distance (Burns 

et al., 1999). 

The less soluble fractions of the constituents in produced water associate with suspended particles and 

may sink (Burns et al., 1999). Particulate components were reported to fall out of suspension within 

0.5-1 nmi (0.6-1.2 mi; 0.9-1.9 km) from the source outfall (Burns et al., 1999). The particulate fraction 

disperses widely with distance from the outfall, and soluble components dissolve in the water column, 

leaving the larger, less bioavailable compounds on the settling material (Burns et al., 1999). 

Waterborne constituents of produced waters can influence biological activity at a greater distance 

from the platform than can particulate components (Osenberg et al., 1992). The waterborne fractions 

travel with currents; however, data suggest that these fractions remain in the surface layers of the water 

column (Burns et al., 1999). Measurements of toluene, the most common dissolved hydrocarbon in 

produced waters, revealed rapid dilution with concentrations between 1 and 10 ng/L (0.000001-0.00001 
4-426 Central Planning Area Supplemental EIS 

ppm) <2 km (1 mi) directly downcurrent from the source and rapid dispersion much closer to the source 

opposite the current (King and McAllister, 1998). Modeling data for a platform in Australia indicated the 

plume to remain in the surface mixed layer (top 10 m [33 ft]) of the water column, which would protect 

seafloor organisms from encountering the waterborne constituents of produced waters. 

Acute effects caused by produced waters are likely only to occur within the mixing zone around the 

outfall (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). Another study in Australia reported that the average total concentration of 

20 aromatic hydrocarbons measured in the water column 20 m (66 ft) from a discharge was <0.5μg/L 

(0.0005 mg/L or 0.0005 ppm) due to the rapid dispersion of the produced-water plume (Terrens and Tait, 

1996). 

Compounds found in produced waters are not anticipated to bioaccumulate in marine organisms. 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. 

Metals including barium, cadmium, mercury, nickel, lead, and valadium in the tissue of the clam, Chama 

macerophylla, and the oyster, Crassostrea virginica, collected within 10 m (33 ft) of discharge pipes on 

oil platforms were not statistically different from reference stations (Trefry et al., 1995). Because highmolecular weight 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). 

Chronic effects including decreased fecundity; altered larval development, viability, and settlement; 

reduced recruitment; reduced growth; reduced photosynthesis by phytoplankton; reduced bacterial 

growth; alteration of community composition; and bioaccumulation of contaminants were reported for 

benthic organisms close to discharges and out to 1,000 m (3,281 ft) from the discharge (Holdway, 2002; 

Burns et al., 1999). Effects were greater closer to the discharges and responses varied by species; 

therefore, high concentrations of produced waters may have a chronic effect on organisms on or adjacent 

to the platform. 

Produced waters should only impact localized populations of the soft-bottom biota. The greatest 

impacts are reported adjacent to the discharge and are substantially reduced <100 m (328 ft) from the 

discharge. Also, USEPA’s general NPDES permit restrictions on the discharge of produced water, which 

require the effluent concentration 100 m (328 ft) from the outfall to be less than the 7-day “no observable 

effect concentration” based on laboratory exposures, would help to limit the impacts on biological 

resources nearby (Smith et al., 1994). Measurements taken from a platform in the Gulf of Mexico 

showed discharge to be diluted below the “no observable effect concentration” within 10 m (33 ft) of the 

discharge (Smith et al., 1994). Such low concentrations would be expected to be even further diluted at 

greater distances from the well. 

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 
Description of the Environment and Impact Analysis 4-427 

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. 

Very few crabs died when exposed to 14-kg (31-lb) charges in open water 46 m (150 ft) away from the 

explosions. 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 BSEE 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 

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 
4-428 Central Planning Area Supplemental EIS 

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). Routine operations may affect soft-bottom benthic communities 

through infrastructure emplacement, turbidity, sedimentation, drilling effluent discharges and producedwater discharges, blowouts, and oil spills. Of the small area affected, the resultant impacts from drilling 

and produced-water discharges 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 widespread 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 resulting from shunted cuttings have been measured a distance of 1,000 m (3,281 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 

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). 
Description of the Environment and Impact Analysis 4-429 

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. The soft-bottom substrate is ubiquitous throughout the Gulf of Mexico. 

Although the likelihood of a low-probability, large-volume catastrophic spill remains remote 

(Appendix B), the types or kinds of impacts to soft-bottom communities would likely be the same for a 

smaller-scale accidental event. As such, the analysis below addresses both types of spills. 

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 adhere 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 

benthic 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 be expected to 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 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- to 20-m (33- to 66-ft) water depth are protected from surface oil 
4-430 Central Planning Area Supplemental EIS 

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 the adherence 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 if it 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 should 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 adults, 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). Based on the above data, any dissolved petroleum hydrocarbon constituents that 

reach larval benthic organisms may cause acute toxicity and other developmental effects to this life stage. 

The WAF, however, is based on a closed experimental system in equilibrium and may be artificially low 

for the Gulf of Mexico, which will not reach equilibrium with contaminants. These experimental values 

should therefore be considered a conservative approach that would tend to overestimate impacts. 

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 would become 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, 2002; Kingston 
Description of the Environment and Impact Analysis 4-431 

et al., 1995). Oil also would reach the seafloor through consumption by plankton with excretion 

distributed over the seafloor (ITOPF, 2002). The longer and farther a subsea plume travels in the sea, the 

more dilute the oil would 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 would move in the direction of prevailing currents (S.L. Ross Environmental Research 

Ltd., 1997) and although the oil would weather with the distance it travels, low levels of oil transported in 

subsea plumes may impact benthic communities. These mechanisms would result in a wide distribution 

of small amounts of oil. The oil would be in the process of biodegradation from bacterial action that 

would continue on the seafloor. The movement of biodegrading oil would result in scattered 

microhabitats with an enriched carbon environment may result (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, 2002; 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 

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 
4-432 Central Planning Area Supplemental EIS 

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). 

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, 2002). 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 from 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 from 

neighboring or nearby areas 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 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 
Description of the Environment and Impact Analysis 4-433 

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 would 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 

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 
4-434 Central Planning Area Supplemental EIS 

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; 

Deleersnijder 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 released 

approximately 475,000 metric tons of oil, which 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 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). 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 detected 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). 

Field measurements after the Ixtoc blowout 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 (ERCO, 1982). 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 result 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 

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. 
Description of the Environment and Impact Analysis 4-435 

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 

As described above, a subsurface spill or plume may impact soft-bottom benthic communities. As 

described in Table 3-5 of this Supplemental EIS and in Table 4-35 of the Multisale EIS, BOEM 

estimated the potential number of accidental events likely to occur during the 40-year leasing scenario for 

the OCS Program. The likelihood of a catastrophic spill remains remote; however, the types and kinds of 

impacts to soft-bottom communities from such a low-probability catastrophic spill would likely be similar 

to those expected from a more typical accidental event at a community level. Oil or dispersed oil may 

cause lethal or sublethal impacts to benthic organisms wherever a plume may contact them. 
4-436 Central Planning Area Supplemental EIS 

Oil or dispersed oil may cause lethal or sublethal impacts to benthic organisms. Impacts may include 

loss of habitat and biodiversity, contamination of substrate, change in community structure, toxicity to 

larvae and embryos, and failed reproductive success. Oil adhered to sediment 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, as soon as 

1 year in some cases (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 be expected to experience lethal impacts 

in an accidental event as a result of blowouts, surface and subsurface oil spills, and their 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 OCS-related 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. Other non-OCS-related impacts that may 

occur and adversely affect soft-bottom benthic communities include the following: commercial fishering; 

natural disturbances; anchoring by recreational boats and other non-OCS commercial vessels; spillage 

from import tankering; cable laying; bottom trawling; hypoxia (low oxygen levels 2 ppm); and storm 

events. 

Most of the 268,922 km2

 (103,831 mi2) of the CPA are soft mud bottoms, and 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. 
Description of the Environment and Impact Analysis 4-437 

OCS Leasing-Related Impacts 

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). 

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 sweeps 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). 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). 

Another major impact of OCS-related construction is pipeline burial. In waters 60 m (200 ft), the 

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). 

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” as a result of experiments with explosives. Impacts to invertebrates are 

anticipated to be minimal as they do not have air bladders inside their bodies that may burst with 

explosions, as do some fish (Schroeder and Love, 2004). 

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 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 nearby topographic 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, 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). Impacts 

to sediment and marine organisms are generally reported within a 100-m (328-ft) range of the producedwater discharge (Neff and Sauer, 1991; Trefry et al., 1995). Also, USEPA’s general NPDES permit 

restrictions on the discharge of produced water, which require the effluent concentration 100 m (328 ft) 

from the outfall to be less than the 7-day “no observable effect concentration” based on laboratory 
4-438 Central Planning Area Supplemental EIS 

exposures (Smith et al., 1994). Therefore, impacts to infauna are anticipated to be localized and only 

affect a small portion of the entire seafloor of the Gulf of Mexico. 

Oil spills may have an impact on the benthic communities of the Gulf of Mexico. Surface oil spills 

released from tankers may impact shallow, nearshore benthic communities through physical contact. 

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; 

Inoue et al., 2008). 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 or exposure to water soluble fractions for shallow nearshore benthic 

communities, resulting in lethal impacts to organisms (Suchanek, 1993; Beiras and Saco-Álvarez, 2006; 

Byrne, 1989) or impaired embryonic development (Byrne and Calder, 1977; Nicol et al., 1977; 

Vashchenko, 1980). 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 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). Benthic communities farther offshore, in deeper water, however, 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 >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 

biodegradation. These plumes would continue to be dispersed over a wide area in low concentrations 

with sublethal to immeasurable effect. If concentrated oil was 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). 

In November 2010, it was estimated that 26 percent of the released oil from the DWH event remained 

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 was in the sediments (Lubchenco et al., 2010). 

Currently, the bulk deposits of oil have been removed from beaches, and the remaining oil that reached 

shorelines has been buried (e.g., through wave action and hurricanes) and is weathering over time 

(OSAT-2, 2011). Oil that has been deposited on the floor of the Gulf has also weathered (OSAT, 2010). 

The greatest concentrations of oil on the seabed are expected to be near the wellhead and to 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 from the well. Evidence 

shows that gas and oil from the DWH event in the water column rapidly deteriorated as they traveled to 

their final destination (Hazen et al., 2010; OSAT, 2010). 

A recent report documents damage to a deepwater coral community 11 km (7 mi) southwest of the 

blowout (USDOI, BOEMRE, 2010j). Soft bottoms in this area were also likely exposed to oil, but 

sediment cores collected from this location did not contain levels of oil that exceeded USEPA’s aquatic 

life benchmarks (OSAT, 2010). A probable explanation for the detrimental impacts to corals, in the 

absence of USEPA’s aquatic life benchmark exceedances is that the coral community forms structures 

that protrude up into the water column that would be affected by a passing oil plume in a way that a 

typical smooth soft bottom would not because infaunal species remain below the sediment. The oil plume 

probably passed over smooth soft bottom, continuing the process of biodegradation in mid-water and 

continuing to be dispersed over a wide area. 
Description of the Environment and Impact Analysis 4-439 

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). Also, seafloor samples indicated that 

the only sediment exceedances of USEPA’s chronic aquatic life benchmarks occurred within 3 km (2 mi) 

of the well, and samples fell to background levels at a distance of 10 km (6 mi) from the well (OSAT, 

2010). Therefore, the acute impacts of any large-scale blowout to soft-bottom benthic communities 

would likely be limited in scale and influenced by directional currents, 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.

Non-OCS Leasing Impacts 

Severe physical damage may occur to soft-bottom sediments and the associated benthic communities 

as a result of non-OCS production activities. Infauna associated with soft-bottom sediments of the CPA 

are often exposed to, and can be well adapted to, natural disturbances such as turbidity and storms. 

However, human disturbance, such as trawling or non-OCS activity-related oil spills, may cause damage 

to infauna, possibly leading to changes of physical integrity, species diversity, or biological productivity. 

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 

BOEM-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 shallowbottom 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 to 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 ppm. Such low concentrations are lethal to many benthic 

organisms and may result in the loss of some benthic populations. However, because the Gulf of Mexico 

soft-bottom benthic habitats are ubiquitous throughout the Gulf, recolonization of devastated areas by 

populations from unaffected soft-bottom substrate would be expected to occur within a relatively short 

period of time, once the hypoxic event is over, through planktonic larval dispersal in the water column 

(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 soft-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 
4-440 Central Planning Area Supplemental EIS 

diversity compared with untrawled seafloor (McConnaughey et al., 2000). Trawl trails may scour 

sediment, killing infauna, and possibly physically removing epifaunal organisms (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). 

Summary and Conclusion 

Non-OCS activities that may occur on soft-bottom benthic substrate include recreational boating and 

fishing, import tankering, 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. Oil spills 

from non-OCS import tankering or other activity may result in oiled benthic communities that will only 

repopulate once the concentration of oil in the sediment has decreased. 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 and because impacted communities are repopulated relatively quickly. 

Also, USEPA’s general NPDES permit restrictions on the discharge of produced water, which require the 

effluent concentration 100 m (328 ft) from the outfall to be less than the 7-day “no observable effect 

concentration” based on laboratory exposures, would help to limit the impacts on benthic communities 

(Smith et al., 1994). 

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; 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. Non-OCS factors such as storms, trawling, nonOCS-related spills, and hypoxia are likely to impact the soft-bottom communities on a more frequent 

basis. Impacts from OCS activities are also somewhat minimized by the fact that these communities are 

ubiquitous through the CPA and can recruit quickly from neighboring areas. 

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 BOEM’s Gulf of Mexico OCS Region. Therefore, there is no prior 

discussion in the Multisale EIS or the 2009-2012 Supplemental EIS upon which to tier this information. 

However, the diamondback terrapin is a Federal species of concern and is currently being assessed under 

the NRDA process for potential post-DWH impacts and is thus included within this Supplemental EIS. 

4.1.1.22.2.1. Description of the Affected Environment 

Diamondback terrapins occur in 16 states along the Atlantic and Gulf of Mexico Coasts; the coastline 

of Florida represents approximately 20 percent of their full range (Butler et al., 2006). The primary 
Description of the Environment and Impact Analysis 4-441 

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. 

Another subspecies that occurs in part of the CPA and that is a Federal species of concern is the Texas 

diamondback terrapin (Malaclemys terrapin littoralis; listed November 15, 1994), which has a range from 

Louisiana through Texas (USDOI, FWS, 2011). 

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 (e.g. low skin permeability to salts, powerful lachrymal salt 

gland, sloping jaw to drink water in thin layers, feed in fresh water more than salt water) (Cowan, 1990; 

U.S. Dept. of the Army, COE, 2002b). Their diet consists of fish, snails, worms, clams, crabs, and marsh 

plants (Cagle, 1952; Butler et al., 2006). 

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). Although not definitively known, Texas terrapins are expected to have similar life cycles. 

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, including 

development and erosion, and they could be affected by accidental events such as direct catastrophic oil 

contact and cleanup efforts. 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. 

Deepwater Horizon Event 

The DWH event and associated oil spill may have impacted the terrapin community and associated 

brackish habitats in the CPA. According to OSAT-2 (2011), possible environmental effects from the 

DWH event could occur within terrapin marsh habitat via food or from nesting habitat since no active 

intervention (natural remediation) is the preferred protocol. Terrapins are omnivores, preferring snails, 

clams, mussels, crabs, insects, fish, worms, and vegetation (Butler et al., 2006). 

The Deepwater Horizon Unified Command reports daily fish and wildlife collection reports 

(RestoreTheGulf, 2011b). As of September 22, 2011, two other reptiles (not yet identified as terrapin and 

other than sea turtles) have been collected in the CPA (RestoreTheGulf.gov, 2011b). No known terrapins 

have been collected to date. Potential impacts to the terrapins’ habitat is addressed in Chapter 4.1.1.4

(wetlands). 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. 

Diamondback Terrapin Resources in the Central Planning Area 

The final determinations on damages to diamondback terrapin resources from the DWH event will 

ultimately be made through the NRDA process. The DWH event will ultimately allow a better 
4-442 Central Planning Area Supplemental EIS 

understanding of any realized effects from such a low-probability catastrophic spill. However, the best 

available information on impacts to diamondback terrapins does not yet provide a complete understanding 

of the effects of the oil spilled and of the active response/cleanup activities from the DWH event on 

diamondback terrapins as a whole in the GOM and whether these impacts reach a population level. 

The BOEM concludes that the unavailable information resulting from the DWH event could be 

relevant to reasonable foreseeable significant adverse effects. The OCS activities will be ongoing under 

existing leases (4,503 active leases in CPA as of November 1, 2011), whether or not the proposed action 

or any other alternative is selected. However, BOEM believes that the unavailable information may be 

essential to a reasoned choice among alternatives, particularly to the extent that diamondback terrapins 

were affected by the DWH event. The FWS has jurisdiction for investigating terrrapin impacts from the 

DWH event. To date, no data are available on impacts to terrapins from the DWH event. We are 

therefore unable to determine, at this point and time, what effect (if any) the DWH event had on terrapins. 

The NRDA process may take years to complete. Impacts from the DWH event may be difficult or 

impossible to discern from other factors. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in this Supplemental EIS, regardless of the cost or resources 

needed. In light of the incomplete or unavailable information, BOEM subject-matter experts have used 

available scientifically credible evidence in this analysis, applied using accepted scientific methods and 

approaches. 

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) and 

Texas diamondback terrapin (Malaclemys terrapin littoralis) include beach trash and debris generated by 

service vessels and OCS facilities; efforts undertaken for the removal of marine debris or for beach 

restoration; and vessel traffic with associated habitat erosion. 

Proposed Action Analysis 

The major routine impact-producing factors associated with the CPA proposed action that may affect 

terrapins include beach trash and debris generated by service vessels and OCS facilities; efforts 

undertaken for the removal of marine debris or for beach restoration; and vessel traffic with associated 

habitat erosion. 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 wildlife. The incidental ingestion of marine debris and 

entanglement could adversely affect terrapins. The BOEM proposes compliance with the established 

guidelines provided in NTL 2007-G03, “Marine Trash and Debris Awareness and Elimination,” which 

appreciably reduces the likelihood of encountering marine debris from the proposed activity. 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, most impacts associated with the OCS 

Program are not expected to impact terrapins or their habitat. 

There have been no documented terrapin collisions with drilling and service vessels in the GOM. To 

further minimize the potential for vessel strikes, BOEM issued NTL 2007-G04, which clarifies 30 CFR 

250.282 and 30 CFR 550.282 and provides NMFS guidelines for monitoring procedures related to vessel 

strike avoidance measures. The BOEM and BSEE monitor for any takes that have occurred as a result of 

vessel strikes and also require that any operator immediately report the striking of any marine animal (see 

30 CFR 250.282, 30 CFR 550.282, and NTL 2007-G04). Other potential impacts that are indirectly 

associated with OCS energy-related activities are wake erosion of terrapin habitat resulting from vessel 

traffic and additional onshore development. However, only a small amount of the routine dredging done 

in coastal areas would be directly or indirectly due to the proposed action. 

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. The potential impacts to terrapin habitat from 

routine activities are discussed in Chapters 4.1.1.4 (wetlands), 4.1.1.2.1 (coastal water quality), and 
Description of the Environment and Impact Analysis 4-443 

4.1.1.3 (coastal barrier islands). Because onshore impacts from routine impacts are not expected to be 

significant, it is not expected that terrapin habitat would be significantly impacted by routine activities 

associated with the proposed action.

Summary and Conclusion 

Adverse impacts due to 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 plastics in the ocean are decreasing and 

the devastating effects on offshore and coastal marine life are minimizing. 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 Gulf of Mexico. 

Although there will always be some level of incomplete information on the effects from routine 

activities under this proposed action on diamondback terrapin, there is credible scientific information, 

applied using acceptable scientific methodologies, to support the conclusion that any realized impacts 

from routine activities would be sublethal in nature and not in themselves rise to the level of reasonably 

foreseeable significant adverse (population level) effects. Because completion of the NRDA process may 

be years away, BOEM cannot definitively determine if the information resulting from that process may be 

essential to a reasoned choice among alternatives. Routine activities, however, will be ongoing in the 

proposed action area (CPA) as a result of existing leases and related activities. (In the CPA, there are 

4,503 active leases as of November 2011.) Within the CPA, there is a long-standing and well-developed 

OCS Program (more than 50 years); there are no data to suggest that routine activities from the preexisting OCS Program are significantly impacting diamondback terrapin populations. As such, even with 

this uncertainty, the potential impacts from routine activities associated with the proposed action are 

unlikely to result in significant, population-level impacts on diamondback terrapins due to their distance 

from most offshore activities and the limited potential for activities occurring in or near their habitat 

(0-1 pipeline landfalls and other coastal infrastructure, which is subject to permitting and location 

requirements). Therefore, a full understanding of any incomplete or unavailable information on the 

effects of routine activities is likely not essential to make a reasoned choice among the alternatives. 

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) and 

Texas diamondback terrapin (Malaclemys terrapin littoralis) include offshore and coastal oil spills and 

spill-response activities. 

Proposed Action Analysis 

Accidental blowouts, oil spills, and spill-response activities resulting from the CPA proposed action 

have the potential to impact small to large numbers of terrapins within their habitat, 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. Populations of terrapins in the Gulf may 

be exposed to residuals of oils spilled as a result of the proposed action during their lifetimes. Chronic or 

acute exposure may result in the harassment, harm, or mortality to terrapins occurring in the Gulf. In the 

most likely scenarios, exposure to hydrocarbons persisting within the wetlands following the dispersal of 

an oil slick could result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; 

and increased vulnerability to disease). Terrapin hatchling exposure to, fouling by, or consumption of 

tarballs persisting inland following the dispersal of an oil slick could likely be fatal but unlikely. 

Burger (1994) described the behavior of 11 female diamondback terrapins that were oiled during the 

January 1990 spill of No. 2 fuel oil in Arthur Kill, New York. The terrapins were hibernating at the time 

of the spill, and when they emerged from hibernation, they were found to be oiled. The terrapins voided 

oil from their digestive tracks for 2 weeks in rehabilitation. At 3 weeks, the terrapins scored low on 

strength tests and were slow to right themselves when placed on their backs. At 4 weeks, they developed 
4-444 Central Planning Area Supplemental EIS 

edema and appetite suppression. Eight of the 11 died; these animals had traces of oil in their tissues and 

exhibited lesions in their digestive tract consistent with oil exposure (Burger, 1994). 

The DWH event and associated oil spill may have potentially impacted the terrapin community. 

Impacts from a catastrophic spill may impact terrapin communities (Appendix B). 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 potentially affected terrapin 

environment. 

Accidental blowouts, oil spills, and spill-response activities resulting from the CPA proposed action 

have the potential to impact small to large numbers of terrapins within their habitat, 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. Populations of terrapins in the Gulf may 

be exposed to residuals of oils spilled as a result of the proposed action during their lifetimes. Chronic or 

acute exposure may result in the harassment, harm, or mortality to terrapins occurring in the Gulf. In 

most foreseeable cases, exposure to hydrocarbons persisting within the wetlands following the dispersal 

of an oil slick could result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; 

and increased vulnerability to disease). Terrapin hatchling exposure to, fouling by, or consumption of 

tarballs persisting inland following the dispersal of an oil slick would likely be fatal but unlikely. Impacts 

from the dispersants are unknown, but they may have similar irritants to tissues and sensitive membranes 

as they are known to have had on seabirds and sea turtles (NRC, 2005). The impacts to diamondback 

terrapins from chemical dispersants could include nonlethal injury (e.g., tissue irritation, inhalation), longterm exposure through bioaccumulation, and potential shifts in distribution from some habitats. 

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 oil contact. 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. 

Summary and Conclusion 

Impacts on diamondback terrapins from smaller accidental events are likely to affect individual 

diamondback terrapins in the spill area, as described above, but are unlikely to rise to the level of 

population effects (or significance) given the probable size and scope of such spills. Further, the potential 

remains for smaller accidental spills to occur in the proposed action area, regardless of any alternative 

selected under this Supplemental EIS, given that, as of November 2011, there are 4,503 active leases in 

the CPA with either ongoing or the potential for exploration, drilling, and production activities. 

The analyses within this Supplemental EIS and in Appendix B conclude that there is a low 

probability for catastrophic spills, and Appendix B also concludes that there is a potential for a lowprobability catastrophic event to result in significant, population-level effects on affected diamondback 

terrapin species. The BOEM continues to concur with the conclusions from these analyses. 

The BOEM concludes that there is incomplete or unavailable information that may be relevant to 

reasonably foreseeable significant adverse impacts from noncatastrophic spills/accidental events to 

terrapins that were potentially impacted by the DWH event. For example, there is incomplete information 

on impacts to terrapin populations from the DWH event and whether individuals or populations may be 

susceptible to greater impacts in light of the DWH event. Relevant data on the status of and impacts to 

terrapin populations from the DWH event are being developed through the NRDA process; it may take 

years to acquire and analyze, and impacts from the DWH event may be difficult or impossible to discern 

from other factors. No data on terrapins impacted by the DWH event have been released. It is not 

possible for BOEM to obtain this information within the timeline contemplated in this Supplemental EIS, 

regardless of the cost or resources needed. In the absence of this information, BOEM subject-matter 

experts have used what scientifically credible information is available, applied using accepted scientific 

methodologies. Activities that could result in an accidental spill in the CPA would be ongoing whether or 

not the lease sale under the proposed action of this Supplemental EIS occurred. As of November 2011, 

there are 4,503 active leases in the CPA that are engaged, or have the potential to be engaged, in drilling 

and/or production activities that could result in an accidental spill. 
Description of the Environment and Impact Analysis 4-445 

For those terrapin populations that may not have been impacted by the DWH event, it is unlikely that 

a future accidental event related to the proposed action would result in significant impacts due to the 

distance of most terrapin habitat from offshore OCS energy-related activities. A low-probability, largescale catastrophic event of the size and type that could reach these habitats is discussed in the 

Appendix B. 

4.1.1.22.2.4. Cumulative Impacts 

Background/Introduction 

The major impact-producing factors that may affect the Mississippi diamondback terrapin 

(Malaclemys terrapin pileata) and Texas diamondback terrapin (Malaclemys terrapin littoralis) include 

oil spills and spill-response activities, alteration and reduction of habitat and consumption of 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 terrapins or their habitats. Cumulative activities 

posing the greatest potential harm to terrapins are non-OCS energy related 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 incremental contribution of the CPA proposed 

action to cumulative impacts on the terrapin 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 (i.e., urban development, subsidence/sea-level 

rise, direct oil contact, and associated cleanup efforts). Habitat loss has the potential to increase terrapin 

vulnerability to predation and increase competition. Behavioral effects and nonfatal exposure to or intake 

of OCS energy-related contaminants or discarded debris may stress and/or weaken individuals of a local 

group or population and predispose them to infection from natural or anthropogenic sources. 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 

(Burger, 1994; Roosenburg et al., 1999). 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 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 overharvesting and habitat loss. These characteristics include low reproductive 

rates, low survivorship, limited population movements, and nest site fidelity year after year. 

Impacts can be either direct (mortality or injury) or indirect (e.g., reduced prey availability); however, 

most impacts cannot be quantified at this time. As discussed in Appendix B, a low-probability, largescale catastrophic event could have population-level effects on diamondback terrapins. The best available 

information does not provide a complete understanding of the effects of the spilled oil and active 

response/cleanup activities related to the DWH event on the potentially affected terrapin environment; 

however, the CPA estuarine environments were affected by the DWH event (Chapter 4.1.1.4 [wetlands]). 

The effects of the proposed action, when viewed in light of the effects associated with other past, 

present, and reasonably foreseeable future activities, may result in greater impacts to diamondback 

terrapins than before the DWH event; however, the magnitude of those effects cannot yet be determined. 

Nonetheless, to mitigate potential impacts from OCS-related energy activities, operators are required to 

follow all applicable lease stipulations and regulations, as clarified by NTL’s, to minimize these potential 

interactions and impacts. The operator’s reaffirmed compliance with NTL 2007-G04 (“Vessel-Strike 

Avoidance”) and NTL 2007-G03 (“Marine Trash and Debris”), as well as the limited scope, timing, and 

geographic location of the proposed action, would result in negligible effects from the proposed drilling 

activities on diamondback terrapins. Therefore, no significant cumulative impacts to diamondback 

terrapins 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 ongoing 

activities in the area. 
4-446 Central Planning Area Supplemental EIS 

Summary and Conclusion 

Diamondback terrapins have experienced impacting pressures from habitat destruction, road 

construction, drowning in crab traps, and past overharvesting resulting in historical reductions in their 

habitat range and declines in populations. Inshore oil spills from non-OCS energy-related sources are 

potential threats to terrapins in their brackish coastal marshes. Pipelines from offshore oil and gas and 

other shoreline crossings have contributed to marsh erosion. However, the current proposed action 

includes only limited shoreline crossings, and modern regulations require mitigation of wetland impacts. 

Low-probability, large-scale catastrophic offshore oil spills could affect the coastal marsh environment, 

but such events are rare occurrences and may not reach the shore, even if they do occur. Therefore, the 

incremental contribution of the proposed action is expected to be minimal compared with non-OCS 

activities. 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, and consumption of trash and debris. As described in 

Chapter 4.1.1.4 (wetlands), direct impacts to terrapin habitat from pipeline landfalls and infrastructure 

are expected to be minimal, highly regulated, and likely to be located around existing infrastructure. Due 

to the extended distance from shore, impacts associated with activities occurring in the OCS Program are 

not expected to impact terrapins or their habitat. 

Unavailable information on the effects to diamondback terrapins from the DWH event (and thus 

changes to the diamondback terrapin baseline in the Affected Environment) makes an understanding of 

the cumulative effects less clear. Here, BOEM concludes that the unavailable information from these 

events may be relevant to foreseeable significant adverse impacts to diamondback terrapins. Relevant 

data on the status of diamondback terrapin populations after the DWH event may take years to acquire 

and analyze, and impacts from the DWH event may be difficult or impossible to discern from other 

factors. Therefore, it is not possible for BOEM to obtain this information within the timeframe 

contemplated in this Supplemental EIS, regardless of the cost or resources needed. In light of the 

incomplete or unavailable information, BOEM subject-matter experts have used available scientifically 

credible evidence in this analysis and applied it using accepted scientific methods and approaches. 

Nevertheless, BOEM believes that incomplete or unavailable information regarding effects of the DWH 

event on terrapins is not essential to a reasoned choice among alternatives in the cumulative effects 

analysis. The rate of current and historic loss of terrapin habitat in Louisiana, for example, far exceeds 

the potential impacts to terrapin habitat from the DWH event. 

Overall, within the CPA, there is a long-standing and well-developed OCS Program (more than 

50 years); there are no data to suggest that activities from the preexisting OCS Program are significantly 

impacting diamondback terrapin populations. Non-OCS energy-related activities will continue to occur 

in the CPA irrespective of this proposed lease sale (i.e., crabbing, fishing, military activities, scientific 

research, and shoreline development). Therefore, in light of the above analysis on the proposed action 

and its impacts, the incremental effect of the proposed action on diamondback terrapins populations is not 

expected to be significant when compared with historic and current non-OCS energy-related activities, 

such as habitat loss, overharvesting, crabbing, and fishing. 

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 subject 

to 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 
Description of the Environment and Impact Analysis 4-447 

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. 

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 
4-448 Central Planning Area Supplemental EIS 

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. 

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: 
Description of the Environment and Impact Analysis 4-449 

— 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 

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 
4-450 Central Planning Area Supplemental EIS 

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 mi 

(24 km) of the 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 

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. 
Description of the Environment and Impact Analysis 4-451 

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 BOEM’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 

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, 2007b); and Energy Alternatives and the Environment (King, 2007). 
4-452 Central Planning Area Supplemental EIS 

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 is 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 BOEM’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 

covered by the suspensions, 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. 

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 
Description of the Environment and Impact Analysis 4-453 

inquiries following the DWH event 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 

BOEM’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 

collisions and oil spills. The quantity spilled in tanker accidents or collisions could be large, and such a 

spill could take place instantaneously for the most part, with wide-ranging consequences to the GOM 

environment. 

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. Adverse impacts from catastrophic events could 

be of longer duration and extend beyond the local area. 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. 
4-454 Central Planning Area Supplemental EIS 

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 

completely understood, particularly in subsurface environments.

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 gas released from solution, 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 

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: Because this is a proposed lease sale that does not in and of 

itself make any irreversible or irretrievable commitment of resources that would foreclose the 

development or implementation of any reasonable and prudent measures to comply with the Endangered 

Species Act, BOEM may proceed with publication of this Supplemental EIS and finalize a decision 

among these alternatives even if consultation is not complete, consistent with Section 7(d) of the ESA. 

Irreversible loss of individuals that are ESA-listed 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. 

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 
Description of the Environment and Impact Analysis 4-455 

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 

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 and cause 

temporary aesthetic or cosmetic impacts until the oil is cleaned or degrades. 
4-456 Central Planning Area Supplemental EIS 

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.

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. 
Description of the Environment and Impact Analysis 4-457 

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, 

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 
4-458 Central Planning Area Supplemental EIS 

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. Additionally, the OCS Program 

continues to improve the knowledge and mitigation practices used in offshore development. 

Approximately 10 percent of the oil and gas structures removed from the OCS are eventually used for 

State artificial reef programs. 
The Department of the Interior Mission

As the Nation’s principal conservation agency, the Department of the Interior has 

responsibility for most of our nationally owned public lands and natural 

resources. This includes fostering the sound use of our land and water 

resources, protecting our fish, wildlife and biological diversity; preserving the 

environmental and cultural values of our national parks and historical places; and 

providing for the enjoyment of life through outdoor recreation. The Department 

assesses our energy and mineral resources and works to ensure that their 

development is in the best interests of all our people by encouraging stewardship 

and citizen participation in their care. The Department also has a major 

responsibility for American Indian reservation communities and for people who 

live in island communities. 

The Bureau of Ocean Energy Management 

The Bureau of Ocean Energy Management (BOEM) works to manage the 

exploration and development of the nation's offshore resources in a way that 

appropriately balances economic development, energy independence, and 

environmental protection through oil and gas leases, renewable energy 

development and environmental reviews and studies.