OCS EIS/EA 

MMS 2008-011 

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 

Draft Supplemental Environmental Impact Statement 

U.S. Department of the Interior

Minerals Management Service 

Gulf of Mexico OCS Region 
OCS EIS/EA 

MMS 2008-011 

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 

Draft Supplemental Environmental Impact Statement 

Author 

Minerals Management Service 

Gulf of Mexico OCS Region 

Published by 

U.S. Department of the Interior

Minerals Management Service 

Gulf of Mexico OCS Region 

New Orleans

April 2008 
iii
v 

COVER SHEET 

Supplemental Environmental Impact Statement 

for Proposed Central Gulf of Mexico OCS Oil and Gas Lease Sales 208, 213, 216, and 222, 

and Proposed Western Gulf of Mexico OCS Oil and Gas Lease Sales 210, 215, and 218 

Draft (x) Final ( ) 

Type of Action: Administrative (x) Legislative ( ) 

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

Louisiana, Mississippi, Alabama, and northwestern Florida 

Agency: Washington Contact: Region Contacts: 

U.S. Department of the Interior 

Minerals Management Service 

Gulf of Mexico OCS Region 

MS 5410 

1201 Elmwood Park Boulevard 

New Orleans, LA 70123-2394 

Mary Boatman (MS 4042) 

U.S. Department of the Interior 

Minerals Management Service 

381 Elden Street 

Herndon, VA 20170-4817 

(703) 787-1662 

Michelle Morin 

 (504) 736-2797 

Casey Rowe 

 (504) 736-2781 

Dennis Chew 

 (504) 736-2793 

ABSTRACT

This Draft Supplemental Environmental Impact Statement (SEIS) covers the proposed 2009-2012 

Gulf of Mexico OCS oil and gas lease sales in the Central and Western Planning Areas. The proposed 

Central Planning Area lease sales are Sale 208 in 2009, Sale 213 in 2010, Sale 216 in 2011, and Sale 222 

in 2012; and the proposed Western Planning Area lease sales are Sale 210 in 2009, Sale 215 in 2010, and 

Sale 218 in 2011. 

This SEIS supplements 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). The Gulf of Mexico Energy Security 

Act of 2006 (P.L. 109-432, December 20, 2006) repeals the Congressional moratorium on certain areas of 

the Gulf of Mexico. One of those areas, the 181 South Area, was not analyzed in the Multisale EIS. 

Therefore, MMS has prepared this SEIS to analyze the potential environmental effects of oil and natural 

gas leasing, exploration, development, and production in the 181 South Area for the proposed Central 

Planning Area sales. This SEIS also analyzes any new information available for the Central and Western 

Planning Areas since the publication of the Multisale EIS. 

The proposed actions are major Federal actions 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 actions, identification of the alternatives, description of the affected 

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

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

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

analyzed. 

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

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

associated with a proposed action on biological, physical, and socioeconomic resources are considered in 

the analyses. 

Additional copies of this SEIS, the Multisale EIS, and the other referenced MMS publications may be 

obtained from the MMS, 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 are 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 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) 

repeals the Congressional moratorium on certain areas of the Gulf of Mexico, places a moratorium on 

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

coastal States. 

One of the areas the GOMESA defines is referred to as the 181 South Area (Figure 1-1). This area is 

located in the CPA and is approximately 5.8 million acres (ac). The Minerals Management Service 

(MMS) is proposing the sale area for proposed CPA Sales 208 (2009), 213 (2010), 216 (2011), and 222 

(2012) be expanded to include 4.3 million ac of the 181 South Area. The remaining acreage of the 181 

South Area (1.5 million ac) is located beyond the U.S. Exclusive Economic Zone (EEZ) and, therefore, 

would not be offered. While GOMESA repealed the Congressional moratorium on the 181 South Area in 

December 2006, MMS has decided, because of the limited geological and geophysical data available to 

industry and the limited environmental review for this area, it would be premature to offer this area prior 

to Sale 208 (2009). The Multisale EIS did not include the 181 South Area. Therefore, MMS has 

performed this separate National Environmental Policy Act (NEPA) review to reevaluate the expanded 

CPA sale area. 

This supplemental environmental impact statement (SEIS) supplements the Multisale EIS. Not only 

does this SEIS analyze the potential environmental effects of oil and natural gas leasing, exploration, 

development, and production in the 181 South Area for the proposed CPA sales, but it also analyzes any 

and all new information available for the CPA and WPA since the publication of the Multisale EIS. 

The proposed Federal actions addressed in this SEIS are the remaining seven areawide oil and gas 

lease sales in the CPA and WPA. The proposed CPA lease sales are Sale 208 in 2009, Sale 213 in 2010, 

Sale 216 in 2011, and Sale 222 in 2012; the proposed WPA lease sales are Sale 210 in 2009, Sale 215 in 

2010, and Sale 218 in 2011. 

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

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

in this SEIS. 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 SEIS as described below. 

• Chapter 1, The Proposed Actions, describes the purpose of and need for the 

proposed lease sales and describes the prelease process. 

• Chapter 2, Alternatives Including the Proposed Actions, describes the environmental 

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

discussed are potential mitigation measures to avoid or minimize impacts. 

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

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

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

the Gulf of Mexico. 

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

describes offshore infrastructure and activities (impact-producing factors) 

associated with the proposed lease sales that could potentially affect the 

biological, physical, and socioeconomic resources of the Gulf of Mexico.
viii Central and Western Gulf of Mexico Multisale Supplemental EIS

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 a 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, which may affect the biological, physical, and 

socioeconomic resources of the Gulf of Mexico. 

• Chapter 4, Environmental and Socioeconomic Consequences, describes the analysis 

of the routine, accidental, and cumulative impacts of a CPA or WPA proposed action 

and the alternatives on environmental and socioeconomic resources of the Gulf of 

Mexico. 

Chapter 4.1, Alternative A – The Proposed Actions, describes the impacts of 

Alternative A on the biological, physical, and socioeconomic resources of the 

Gulf of Mexico. 

Chapter 4.2, Alternatives to the Proposed Actions, describes the impacts of 

the three alternatives to the proposed action in the CPA and two alternatives 

to the proposed action in the WPA on the biological, physical, and 

socioeconomic resources of the Gulf of Mexico. 

Chapter 4 also includes Chapter 4.3, Unavoidable Adverse Impacts of the 

Proposed Actions; Chapter 4.4, Irreversible and Irretrievable Commitment 

of Resources; and Chapter 4.5, 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 SEIS. 

• Chapter 6, References, is a list of literature cited throughout this SEIS. 

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

for preparing and reviewing this SEIS. 

• Chapter 8, Glossary, is a list of definitions of selected terms used in this SEIS. 

Proposed Actions and Alternatives 

The following alternatives were included for analysis in the Multisale EIS. As explained in Chapter 

2.1.3.2, the Use of a Nomination and Tract Selection Leasing System Alternative was not included for 

analysis in this SEIS due to an ongoing MMS study on alternative approaches to leasing. No new 

alternatives were proposed due to the addition of the 181 South Area to the proposed CPA lease sales. 

Alternatives for Proposed Central Planning Area Sales 208, 213, 216, and 222 

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

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

(1) blocks that were previously included within the Eastern Planning Area (EPA) and 

that are within 100 miles (mi) (161 kilometers (km)) of the Florida coast; 

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

northern portion of the Eastern Gap; and 
Summary ix

(3) for Sales 208 and 213 only, whole and partial blocks that lie within the 1.4-nautical 

mile (nmi) buffer zone north of the continental shelf boundary between the U.S. and 

Mexico. 

The CPA sale area encompasses about 63 million ac of the CPA’s 66.3 million ac. Approximately 

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

projected to be developed as a result of any one proposed CPA lease sale is 0.807-1.336 billion barrels of 

oil (BBO) and 3.365-5.405 trillion cubic feet (Tcf) of gas. 

Alternative B—The Proposed Actions 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 actions, with the exception of any unleased blocks subject to the Topographic 

Features Stipulation. 

Alternative C—The Proposed Actions 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 actions, 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 one or more proposed CPA lease 

sales. The opportunity for development of the estimated 0.807-1.336 BBO and 3.365-5.405 Tcf of gas 

that could have resulted from a proposed CPA lease sale would be precluded or postponed. Any potential 

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

is analyzed in the Final EIS for the 5-Year Program. 

Alternatives for Proposed Western Planning Area Sales 210, 215, and 218 

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

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

(1) whole and partial blocks within the boundary of the Flower Garden Banks National 

Marine Sanctuary; and 

(2) for Sales 210 and 215 only, whole and partial blocks that lie within the 1.4-nmi 

buffer zone north of the continental shelf boundary between the U.S. and Mexico. 

The WPA encompasses about 28.7 million ac. Approximately 18.3 million ac (64%) of the WPA sale 

area is currently unleased. The estimated amount of resources projected to be developed as a result of any 

one proposed WPA lease sale is 0.242-0.423 BBO and 1.644-2.647 Tcf of gas. 

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

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

described for the proposed actions, with the exception of any unleased blocks subject to the Topographic 

Features Stipulation. 

Alternative C—No Action: This is the cancellation of one or more proposed WPA lease sales. The 

opportunity for development of the estimated 0.242-0.423 BBO and 1.644-2.647 Tcf of gas that could 

have resulted from a proposed WPA lease sale would be precluded or postponed. Any potential 

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

is analyzed in the Final EIS for the 5-Year Program. 

Mitigating Measures 

All of the proposed actions include 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, and visual impacts from development operations south of Baldwin 

County, Alabama. Seven lease stipulations are proposed for the CPA sales—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; and the Protected 

Species Stipulation. The MMS has proposed no new mitigations to the CPA lease sales due to the 

addition of the 181 South Area. Four lease stipulations are proposed for the WPA sales—the 
x Central and Western Gulf of Mexico Multisale Supplemental EIS

Topographic Features Stipulation, the Military Areas Stipulation, the Operations in the Naval Mine 

Warfare Area Stipulation, and the Protected Species 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 actions 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 warrant. Any stipulations or 

mitigation requirements to be included in a lease sale will be described in the Final Notice of Sale for that 

lease 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 actions (Chapter 3.1) 

and for the OCS Program (Chapter 3.3). The MMS’s Gulf of Mexico OCS Region developed these 

scenarios to provide a framework for detailed analyses of potential impacts of the proposed lease sales. 

The scenarios are presented as ranges of the amounts of undiscovered, unleased hydrocarbon resources 

estimated to be leased and discovered as a result of a 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. 

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

result from the incremental impact of the lease sales 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, including the most 

recent Lease Sale 206 (March 2008), 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 SEIS are the result of concerns raised 

during years of scoping for 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 determined through the scoping process to warrant an 

environmental analysis are water and air quality, sensitive coastal environments (coastal barrier beaches 

and associated dunes, wetlands, and seagrass communities), sensitive offshore resources, marine 

mammals, sea turtles, beach mice, endangered and threatened fish, coastal and marine birds, fisheries, 

recreational fishing, recreational resources, archaeological resources, and socioeconomic conditions. 

Other issues include impacts 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 several 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 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 actions to the resources and the environment (Chapter 4.1). 
Summary xi

Impact Conclusions 

The MMS has reexamined the analysis presented in the Multisale EIS, based on the additional 

information available since the publication of the Multisale EIS and the addition of the 181 South Area to 

the proposed CPA sale area. No significant new information was found that would alter the impact 

conclusions as presented in the Multisale EIS. In some cases, new information that supported these 

conclusions was found. 

Although the size of the proposed CPA sale area was increased due to the addition of the 181 South 

Area, there would be a negligible increase in environmental and socioeconomic impacts of an individual 

CPA lease sale. This negligible increase in impacts is the result of a number of different factors. The 181 

South Area is located at the southeastern edge of the CPA sale area nearly 130 mi (209 km) from the 

nearest coast. A relatively minor amount of additional sale-related activity for the 181 South Area is 

projected because of the extreme water depths, the amount of interest in these water depths in recent lease 

sales, and the lack of recent seismic data.. Drilling rig availability is still a limiting factor for exploration 

and development activity in the Gulf, and the 181 South Area would encounter the same rig availability 

issues as the rest of the Gulf. The minor increases in OCS activities in the 181 South Area could be 

handled adequately by existing personnel and infrastructure. Increases in indirect and secondary impacts 

of an individual CPA lease sale are also expected to be negligible. Therefore, the addition of the 181 

South Area is expected to have minimal, if any, impacts on environmental and socioeconomic resources. 

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

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

described in Chapter 4.1. A summary of the potential impacts from the proposed CPA and WPA 

proposed actions on each environmental and socioeconomic resource and the conclusions of the analyses 

can be found below. 

Air Quality: Because the 181 South Area is nearly 130 mi (209 km) from the nearest coast, routine 

activities occurring in the area are expected to have minimal impact on onshore air quality. In addition, 

no additional large spills or blowouts are projected as a result of the addition of the 181 South Area. 

Emissions of pollutants into the atmosphere from the routine activities associated with the proposed 

actions in the CPA or WPA 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 a proposed action are not expected to have concentrations 

that would change onshore air quality classifications. 

Coastal and Marine Waters: The 181 South Area is located nearly 130 mi (209 km) from the nearest 

coast and is projected to result in a relatively minor amount of additional activity; therefore, no additional 

impacts on coastal water quality are projected as a result of the inclusion of the 181 South Area. 

Impacts from routine activities associated with a CPA or WPA proposed action would be minimal if 

all existing regulatory requirements are met. Coastal water impacts associated with routine activities 

include increases in turbidity resulting from pipeline installation and navigation canal maintenance, 

discharges of bilge and ballast water from support vessels, and run-off from shore-based facilities. 

Marine 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, marine water impacts result from supply and 

service-vessel bilge and ballast water discharges. 

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

waters. Larger spills, however, could impact water quality in coastal waters. Accidental chemical spills, 

release of synthetic-based fluid (SBF), and blowouts would have temporary localized impacts on water 

quality. 
xii Central and Western Gulf of Mexico Multisale Supplemental EIS

Coastal Barrier Beaches and Associated Dunes: Due to both the distance from the proposed offshore 

activity (approximately 130 mi; 209 km) and the prevailing easterly winds, activities associated with the 

181 South Area are expected to have little to no effect on barrier islands. 

Routine activities in the CPA and WPA such as increased vessel traffic, maintenance dredging of 

navigation canals, and pipeline installation will cause negligible impacts and will 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 either a CPA or WPA proposed action are anticipated to be minimal. 

Wetlands: Since the181 South Area is located nearly 130 mi (209 km) from the nearest coast, the 

area has little potential for direct impact to coastal wetlands as a result of the proposed activities in that 

area. 

Routine activities in the CPA and WPA 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: The 181 South Area is located nearly 130 mi (209 km) from the nearest coast 

and is projected to result in a relatively minor amount of additional activity; therefore, no significant 

additional impacts on seagrass communities are projected as a result of the inclusion of the 181 South 

Area. 

Turbidity impacts from pipeline installation and maintenance dredging associated with a proposed 

action would be temporary and localized. The increment of impacts from service-vessel transit associated 

with a 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): The 181 South Area is located 127 mi (204 km) from the Pinnacle 

Trend region and the pinnacle habitat is in water depths of (200-400 ft or 60-120 m); therefore, activity 

associated with the 181 South Area would not impact live bottoms. 

The combination of its depth (200-400 ft or 60-120 m), separation from sources of impacts as 

mandated by the Live Bottoms (Pinnacle Trend) Stipulation, and a community adapted to sedimentation 

makes damage to the ecosystem unlikely from routine activities associated with a CPA proposed action. 

In the unlikely event that oil from a subsurface spill would reach the biota of Pinnacle Trend 

communities, the effects would be primarily sublethal for adult sessile biota and there would be limited 

incidences of mortality. 

No impacts are expected from a WPA proposed action because the Pinnacle Trend is over 300 mi 

(480 km) away; therefore, a WPA proposed action is not analyzed. 

Topographic Features: Since the 181 South Area is 129 mi (207 km) from the nearest topographic 

feature, transiting service vessels would be the only likely impact from the 181 South Area on 

topographic features. Since the closest topographic feature habitats are deep, >184 ft (56 m) to their tops, 

it is unlikely that the 181 South Area would result in any effect unless a transiting vessel has a 

catastrophic accident near a bank. 

The routine activities associated with a CPA or WPA 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 

Feature Stipulation would make damage to the ecosystem unlikely. Contact with accidentally spilled oil 

would cause lethal and sublethal effects in benthic organisms, but the oiling of benthic organisms is not 

likely because of the small area of the banks, the scattered occurrence of spills, the depth of the features, 

and because the proposed Topographic Features Stipulation would keep subsurface sources of spills away 

from the immediate vicinity of topographic features. 

Chemosynthetic and Nonchemosynthetic Deepwater Benthic Communities: The 181 South Area is 

not expected to have any chemosynthetic or hard-bottom nonchemosynthetic communities (such as 

deepwater corals) that would be exposed to any kind of impacts from routine activities or accidental 

events associated with a proposed action. There are no known surface amplitude anomalies in the 181 
Summary xiii

South Area, and this deep area is not underlain by salt structures that create conditions conducive to 

faulting and hydrocarbon flows similar to other areas of the Gulf. 

Chemosynthetic and nonchemosynthetic communities are susceptible to physical impacts from 

structure placement, anchoring, and pipeline installation associated with a proposed action; however, the 

provisions of Notice to Lessees and Operators (NTL) 2000-G20 greatly reduce the risk of these physical 

impacts by requiring avoidance of potential chemosynthetic communities and by consequence avoidance 

of other hard-bottom communities. Even in situations where substantial burial of typical benthic infaunal 

communities occurred, recolonization from populations from widespread, neighboring, soft-bottom 

substrate would be expected over a relatively short period of time for all size ranges of organisms. 

Potential accidental events associated with a 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: With the exception of manatees, any of the marine species that occur in the Gulf 

of Mexico may be found in the 181 South Area. However, the 181 South Area is not unique in regards to 

marine mammal distribution. Impacts from routine activities and accidental events occurring in the 181 

South Area are similar to the rest of the sale area, and are not expected to have long-term adverse effects. 

Routine events related to a CPA or WPA proposed action, particularly when mitigated as required by 

MMS, are not expected to have long-term adverse effects on the size and productivity of any marine 

mammal species or population endemic to the northern Gulf of Mexico. Characteristics of impacts from 

accidental events depend on chronic or acute exposure resulting in harassment, harm, or mortality to 

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

Sea Turtles: Because the 181 South Area is nearly 130 mi (209 km) from the nearest coast, all five 

species of sea turtles may potentially exist within the 181 South Area, and it appears to be an important 

habitat for leatherbacks. Impacts from routine activities and accidental events occurring in the 181 South 

Area are similar to the rest of the sale area. In most foreseeable cases, exposure to hydrocarbons 

persisting in the sea following the dispersal of an oil slick will result in sublethal impacts (e.g., decreased 

health, reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles. 

The routine activities of a proposed action are unlikely to have significant adverse effects on the size 

and recovery of any sea turtle species or population in the Gulf of Mexico. Accidental events associated 

with a 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 a 

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 will result in sublethal impacts. 

Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice: Due to the extended distance 

from shore, impacts associated with activities occurring in the 181 South Area are not expected to impact 

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

Because beach mice are located such a far distance from the proposed WPA sale area, the impacts of 

a WPA proposed action have not been analyzed. 

Coastal and Marine Birds: Use of the 181 South Area by breeding or nonbreeding seabirds is 

unknown; however, the 181 South Area is located nearly 130 mi (209 km) from the nearest coast and is 

projected to result in a relatively minor amount of additional activity; therefore, no additional impacts on 

coastal and marine birds are projected as a result of the inclusion of the 181 South Area. Disturbance to 

seabirds in the 181 South Area would be similar to disturbance to the birds in the other offshore waters of 

the proposed lease sale areas. Endangered or threatened bird species (i.e., piping plover, whooping crane, 

and brown pelican) that inhabit or frequent the north-central and western Gulf of Mexico coastal areas are 

not expected to occur in the 181 South Area. 

The majority of effects resulting from routine activities associated with a CPA or WPA proposed 

action on endangered/threatened and nonendangered/nonthreatened coastal and marine birds are expected 

to be sublethal. These effects include behavioral effects, exposure to or intake of OCS-related 
xiv Central and Western Gulf of Mexico Multisale Supplemental EIS

contaminants or discarded debris, temporary disturbances, and displacement of localized groups from 

impacted habitats. Impacts from potential oil spills associated with a 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: The 181 South Area is nearly 130 mi (209 km) from the nearest coast and is not 

located within the designated critical habitat for Gulf sturgeon. It is extremely unlikely that there will be 

any sturgeon in the 181 South Area due to water depths that far exceed the recorded depths preferred by 

this sturgeon species. In addition, the substrate type and potential forage base associated with bottom 

types at these depths are not conducive for sustaining a Gulf sturgeon food base. 

Routine activities in the CPA such as installation of pipelines, maintenance dredging, potential vessel 

strikes, and nonpoint-source runoff from onshore facilities will cause negligible impacts and will 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. 

The Gulf sturgeon has been infrequently noted in some of the extreme easternmost portions of the 

WPA, but there has been no critical habitat designated west of the Mississippi River. Because of the 

infrequency of occurrence of Gulf sturgeon in the WPA, the analysis of impacts to Gulf sturgeon is 

limited to the CPA. 

Fish Resources and Essential Fish Habitat: The 181 South Area is located in very deep water 

(>2,600 m; 8,530 ft) and limited activities in that area would not have any measurable additional impacts 

to fish resources or essential fish habitat (EFH) for highly migratory species (the only managed species 

group that far offshore). 

Fish resources and EFH could be impacted by coastal environmental degradation, marine 

environmental degradation, pipeline trenching, and offshore discharges of drilling discharges and 

produced waters associated with routine activities. The impact of coastal and marine environmental 

degradation is expected to cause an undetectable decrease in fish resources or in EFH. Impacts of routine 

discharges are localized in time and space and are regulated by USEPA permits and will have minimal 

impact. Accidental events that could impact fish resources and EFH include blowouts and oil or chemical 

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

due to a 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. 

Commercial Fishing: The 181 South Area is located nearly 130 mi (209 km) from the nearest 

coastline. There are no special regulations designated within this area that would indicate any difference 

in the commercial fisheries than what is found in adjacent areas of the Gulf. 

Routine activities in the CPA and WPA such as seismic surveys and pipeline trenching will cause 

negligible impacts and will 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 either a CPA or WPA proposed action are anticipated to be minimal. Commercial 

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

of catch would be insignificant compared with natural variability. 

Recreational Fishing: The inclusion of 181 South Area will have no direct routine impacts on 

recreational fishing due to its distance (nearly 130 mi; 209 km) from the nearest shore. Indirect impacts 

resulting from an incremental increase of vessel trips from activities in the 181 South Area is expected to 

be negligible. 

Routine activities in the CPA and WPA such as seismic surveys and pipeline trenching will cause 

negligible impacts and will not deleteriously affect recreational fishing activities. Indirect impacts to 

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

commercial recreational fisheries. Temporary localized impacts from oil spills are anticipated as a result 

of a CPA or WPA proposed action, which would include temporary inconvenience to recreational 

fishermen and possibly some loss of revenue to facilities supported by recreational fishermen such as boat 

launches and bait shops. 
Summary xv

Recreational Resources: The 181 South Area is located nearly 130 mi (209 km) from the nearest 

coast, far distant from recreational beaches, out of sight from land, and out of range for most recreational 

fishing. The inclusion of the 181 South Area is projected to result in a relatively minor amount of 

additional activity, limiting potential impacts from traffic and from trash and debris. The location of the 

181 South Area and the limited activities that are expected to result also limit the potential impacts from 

oil spills. Therefore, no additional impacts on recreational resources are projected as a result of the 

inclusion of the 181 South Area. 

While marine debris and nearshore operations, either individually or collectively, may adversely 

affect the quality of some recreational experiences, they are unlikely to reduce the number of recreational 

visits to Gulf coastal beaches. It is unlikely that a spill would be a major threat to recreational beaches 

because any impacts would be short term and localized, and should have no long-term effect on tourism. 

Historic and Prehistoric Archaeological Resources: Given the extreme water depths in the 181 South 

Area, no prehistoric archaeological resources would likely be encountered in this area. Areas considered 

by MMS to have a high probability for historic period shipwrecks are located throughout the Gulf of 

Mexico, including the 181 South Area. 

The greatest potential impact to an archaeological resource as a result of routine activities associated 

with a CPA or WPA 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 or 

historic 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 

will 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 a 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: Although the addition of the 181 South Area resulted in some 

increases in the activity scenario for a typical CPA proposed action, these minor increases in activity were 

not significant enough to affect the long-term (i.e., 40-year) forecasts of coastal infrastructure needs to 

support either a typical CPA sale or the OCS Program.

A proposed action in the CPA (i.e., including the 181 South Area) or the WPA 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 a 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 181 South Area is located nearly 130 mi (209 km) from the nearest coast and is 

projected to result in a relatively minor amount of additional activity; therefore, no additional impacts on 

employment, or the resulting population and demographics, are projected as a result of the inclusion of 

the 181 South Area.

A proposed action in the CPA (including the 181 South Area) or the WPA is projected to minimally 

affect the demography of the analysis area. Population impacts from a proposed action are projected to be 

minimal (<1% of total population) for any economic impact area (EIA) 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 a 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) projected to move into focal areas, 

such as Port Fourchon. Accidental events associated with a proposed action such as oil or chemical spills, 
xvi Central and Western Gulf of Mexico Multisale Supplemental EIS

blowouts, and vessel collisions would have likely no effects on the demographic characteristics of the 

Gulf coastal communities. 

Economic Factors: New economic and demographic data (Woods & Poole Economics, Inc., 2007) 

analyzed and the addition of the 181 South Area does not change the conclusions in the Multisale EIS, 

which stated that there would be only minor economic changes in the Texas, Louisiana, Mississippi, 

Alabama, and Florida EIA’s should a proposed CPA or WPA lease sale occur. 

A CPA or WPA 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 a proposed action is expected to occur in Texas and 

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

Environmental Justice: The 181 South Area is located at the eastern edge of the CPA sale area nearly 

130 mi (209 km) from the nearest coast. Also, the 181 South Area is projected to result in a relatively 

minor amount of additional sale-related activity. This limited activity will have few impacts; the location 

of the 181 South Area means that any impacts that may result are unlikely to be concentrated in an area 

that could disproportionately impact minority or low income people. Therefore, no additional impacts on 

minority or low-income people are projected as a result of the inclusion of the 181 South Area. 

Because the proposed CPA sale area lies 3 or more miles (4.8 or more kilometers) offshore, no 

activities that occur on the resulting leases (and that are regulated by MMS) will impact directly 

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 actions are not expected to have disproportionately high or adverse environmental or health 

effects on minority or low-income people. The CPA and WPA proposed actions would help to maintain 

ongoing levels of activity rather than expand them. 
Table of Contents xvii 

TABLE OF CONTENTS 

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

FIGURES.................................................................................................................................................xxiii 

TABLES ...................................................................................................................................................xxv 

1. THE PROPOSED ACTIONS ..............................................................................................................1-3

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

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

1.3. Regulatory Framework ............................................................................................................1-5

1.4. Prelease Process .......................................................................................................................1-6

1.5. Postlease Activities ..................................................................................................................1-7

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

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

2.1.1. Alternatives ...............................................................................................................2-3

2.1.1.1. Alternatives for Proposed Central Planning Area Sales 208, 213, 

216, and 222.............................................................................................2-3

2.1.1.2. Alternatives for Proposed Western Planning Area Sales 210, 

215, and 218.............................................................................................2-4

2.1.2. Mitigating Measures..................................................................................................2-4

2.1.2.1. Proposed Mitigating Measures Analyzed ................................................2-4

2.1.2.2. Existing Mitigating Measures ..................................................................2-5

2.1.3. Issues .........................................................................................................................2-6

2.1.3.1. Issues to be Analyzed...............................................................................2-6

2.1.3.2. Issues Considered but Not Analyzed .......................................................2-6

2.2. Proposed Central Planning Area Lease Sales 208, 213, 216, and 222.....................................2-7

2.2.1. Alternative A—The Proposed Actions......................................................................2-8

2.2.1.1. Description...............................................................................................2-8

2.2.1.2. Summary of Impacts ................................................................................2-8

2.2.1.3. Mitigating Measures ..............................................................................2-16

2.2.2. Alternative B—The Proposed Actions Excluding the Unleased Blocks Near 

the Biologically Sensitive Topographic Features....................................................2-18

2.2.2.1. Description.............................................................................................2-18

2.2.2.2. Summary of Impacts ..............................................................................2-18

2.2.3. Alternative C—The Proposed Actions Excluding the Unleased Blocks 

within 15 Miles of the Baldwin County, Alabama, Coast.......................................2-18

2.2.3.1. Description.............................................................................................2-18

2.2.3.2. Summary of Impacts ..............................................................................2-18

2.2.4. Alternative D—No Action ......................................................................................2-19

2.2.4.1. Description.............................................................................................2-19

2.2.4.2. Summary of Impacts ..............................................................................2-19

2.3. Proposed Western Planning Area Lease Sales 210, 215, and 218 .........................................2-19

2.3.1. Alternative A—The Proposed Actions....................................................................2-19

2.3.1.1. Description.............................................................................................2-19

2.3.1.2. Summary of Impacts ..............................................................................2-20

2.3.1.3. Mitigating Measures ..............................................................................2-25
xviii Central and Western Gulf of Mexico Multisale Supplemental EIS

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

the Biologically Sensitive Topographic Features....................................................2-26

2.3.2.1. Description.............................................................................................2-26

2.3.2.2. Summary of Impacts ..............................................................................2-26

2.3.3. Alternative C—No Action.......................................................................................2-27

2.3.3.1. Description.............................................................................................2-27

2.3.3.2. Summary of Impacts ..............................................................................2-27

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 ....................................3-5

3.1.1.2. Development and Production...................................................................3-6

3.1.1.2.1. Development and Production Drilling ..................................3-6

3.1.1.2.2. Infrastructure Presence..........................................................3-8

3.1.1.2.2.1. Offshore Production Systems...........................................3-8

3.1.1.2.2.2. Space-Use Conflicts.........................................................3-9

3.1.1.2.2.3. Aesthetic Interference ......................................................3-9

3.1.1.2.2.4. Workovers and Abandonments ......................................3-10

3.1.1.3. Major Sources of Oil Inputs in the Gulf of Mexico ...............................3-10

3.1.1.4. Offshore Transport.................................................................................3-13

3.1.1.4.1. Pipelines ..............................................................................3-13

3.1.1.4.2. Barges..................................................................................3-14

3.1.1.4.3. Oil Tankers..........................................................................3-15

3.1.1.4.4. Service Vessels....................................................................3-15

3.1.1.4.5. Helicopters ..........................................................................3-16

3.1.1.5. Safety Issues...........................................................................................3-16

3.1.1.5.1. Hydrogen Sulfide and Sulfurous Petroleum........................3-16

3.1.1.5.2. Shallow Waterflows ............................................................3-17

3.1.1.5.3. Damage to Offshore Infrastructure as the Result of 

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

3.1.1.5.4. New and Unusual Technologies..........................................3-19

3.1.1.6. Decommissioning and Removal Operations..........................................3-19

3.1.2. Coastal Impact-Producing Factors and Scenario.....................................................3-21

3.1.2.1. Service Bases .........................................................................................3-21

3.1.2.2. Gas Processing Plants ............................................................................3-23

3.1.2.3. Coastal Pipelines ....................................................................................3-24

3.1.2.4. Disposal and Storage Facilities for Offshore Operations.......................3-24

3.2. Impact-Producing Factors and Scenario—Accidental Events ...............................................3-24

3.2.1. Oil Spills..................................................................................................................3-25

3.2.1.1. Risk Analysis for Offshore Spills ≥1,000 bbl ........................................3-25

3.2.1.2. Risk Analysis for Offshore Spills <1,000 bbl ........................................3-27

3.2.1.3. Risk Analysis for Coastal Spills............................................................3-28

3.2.1.4. Risk Analysis by Resource.....................................................................3-28

3.2.1.5. Spill Response........................................................................................3-29

3.2.1.5.1. MMS Spill-Response Requirements and Initiatives............3-29

3.2.1.5.2. Offshore Response and Cleanup Technology .....................3-29
Table of Contents xix 

3.2.1.5.3. Oil-Spill-Response Assumptions Used in the 

Analysis of a Most Likely Spill ≥1,000 bbl Incident 

Related to a Proposed Action ..............................................3-31

3.2.1.5.4. Onshore Response and Cleanup ..........................................3-31

3.2.2. Losses of Well Control............................................................................................3-33

3.2.3. Vessel Collisions.....................................................................................................3-33

3.2.4. Chemical and Drilling-Fluid Spills .........................................................................3-33

3.3. Cumulative Activities Scenario .............................................................................................3-34

3.3.1. OCS Program ..........................................................................................................3-34

3.3.2. State Oil and Gas Activity.......................................................................................3-34

3.3.3. Other Major Offshore Activities .............................................................................3-35

3.3.4. Other Major Influencing Factors on Coastal Environments....................................3-38

3.3.5. Coastal Restoration .................................................................................................3-39

3.3.6. Alternative Energy ..................................................................................................3-40

3.3.7. Natural Events and Processes..................................................................................3-41

3.3.7.1. Physical Oceanography..........................................................................3-41

3.3.7.2. Hurricanes ..............................................................................................3-42

4. ENVIRONMENTAL AND SOCIOECONOMIC CONSEQUENCES.................................................4-3

4.1. Alternative A – The Proposed Actions ....................................................................................4-3

4.1.1. Air Quality.................................................................................................................4-3

4.1.1.1. Description of the Affected Environment ................................................4-3

4.1.1.2. Impacts of Routine Events .......................................................................4-4

4.1.1.3. Impacts of Accidental Events...................................................................4-6

4.1.1.4. Cumulative Impacts .................................................................................4-8

4.1.2. Water Quality ............................................................................................................4-9

4.1.2.1. Coastal Waters .......................................................................................4-10

4.1.2.1.1. Description of the Affected Environment ...........................4-10

4.1.2.1.2. Impacts of Routine Events ..................................................4-11

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

4.1.2.1.4. Cumulative Impacts.............................................................4-14

4.1.2.1. Marine Waters........................................................................................4-15

4.1.2.1.1. Description of the Affected Environment ...........................4-15

4.1.2.1.2. Impacts of Routine Events ..................................................4-17

4.1.2.1.3. Impacts of Accidental Events..............................................4-19

4.1.2.1.4. Cumulative Impacts.............................................................4-20

4.1.3. Sensitive Coastal Environments..............................................................................4-21

4.1.3.1. Coastal Barrier Beaches and Associated Dunes.....................................4-21

4.1.3.1.1. Description of the Affected Environment ...........................4-22

4.1.3.1.2. Impacts of Routine Events ..................................................4-24

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

4.1.3.1.4. Cumulative Impacts.............................................................4-28

4.1.3.2. Wetlands.................................................................................................4-32

4.1.3.2.1. Description of the Affected Environment ...........................4-33

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

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

4.1.3.2.4. Cumulative Impacts.............................................................4-41

4.1.3.3. Seagrass Communities ...........................................................................4-45

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

4.1.3.3.2. Impacts of Routine Events ..................................................4-46
xx Central and Western Gulf of Mexico Multisale Supplemental EIS

4.1.3.3.3. Impacts of Accidental Events..............................................4-48

4.1.3.3.4. Cumulative Impacts.............................................................4-51

4.1.4. Continental Shelf Benthic Resources ......................................................................4-53

4.1.4.1. Live Bottoms (Pinnacle Trend)..............................................................4-53

4.1.4.1.1. Description of the Affected Environment ...........................4-53

4.1.4.1.2. Impacts of Routine Events ..................................................4-55

4.1.4.1.3. Impacts of Accidental Events..............................................4-57

4.1.4.1.4. Cumulative Impacts.............................................................4-59

4.1.4.2. Topographic Features.............................................................................4-62

4.1.4.2.1. Description of the Affected Environment ...........................4-62

4.1.4.2.2. Impacts of Routine Events ..................................................4-64

4.1.4.2.3. Impacts of Accidental Events..............................................4-66

4.1.4.2.4. Cumulative Impacts.............................................................4-69

4.1.5. Continental Slope and Deepwater Resources..........................................................4-72

4.1.5.1. Description of the Affected Environment ..............................................4-72

4.1.5.1.1. Chemosynthetic Communities ............................................4-72

4.1.5.1.2. Nonchemosynthetic Communities ......................................4-73

4.1.5.2. Impacts of Routine Events .....................................................................4-74

4.1.5.2.1. Chemosynthetic Communities ............................................4-74

4.1.5.2.2. Nonchemosynthetic Communities ......................................4-76

4.1.5.3. Impacts of Accidental Events.................................................................4-78

4.1.5.3.1. Chemosynthetic Communities ............................................4-78

4.1.5.3.2. Nonchemosynthetic Communities ......................................4-79

4.1.5.4. Cumulative Impacts ...............................................................................4-81

4.1.6. Marine Mammals ....................................................................................................4-84

4.1.6.1. Description of the Affected Environment ..............................................4-84

4.1.6.1.1. Factors Influencing Cetacean Distribution and 

Abundance...........................................................................4-85

4.1.6.2. Impacts of Routine Events .....................................................................4-86

4.1.6.3. Impacts of Accidental Events.................................................................4-90

4.1.6.4. Cumulative Impacts ...............................................................................4-92

4.1.7. Sea Turtles...............................................................................................................4-95

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

4.1.7.2. Impacts of Routine Events .....................................................................4-98

4.1.7.3. Impacts of Accidental Events...............................................................4-102

4.1.7.4. Cumulative Impacts .............................................................................4-105

4.1.8. Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice ...............4-107

4.1.8.1. Description of the Affected Environment ............................................4-108

4.1.8.2. Impacts of Routine Events ...................................................................4-109

4.1.8.3. Impacts of Accidental Events...............................................................4-109

4.1.8.4. Cumulative Impacts .............................................................................4-110

4.1.9. Coastal and Marine Birds......................................................................................4-111

4.1.9.1. Description of the Affected Environment ............................................4-112

4.1.9.2. Impacts of Routine Events ...................................................................4-115

4.1.9.3. Impacts of Accidental Events...............................................................4-120

4.1.9.4. Cumulative Impacts .............................................................................4-123

4.1.10. Endangered and Threatened Fish ..........................................................................4-124

4.1.10.1. Gulf Sturgeon.......................................................................................4-124

4.1.10.1.1. Description of the Affected Environment .........................4-125

4.1.10.1.2. Impacts of Routine Events ................................................4-128
Table of Contents xxi 

4.1.10.1.3. Impacts of Accidental Events............................................4-129

4.1.10.1.4. Cumulative Impacts...........................................................4-131

4.1.11. Fisheries and Essential Fish Habitat......................................................................4-134

4.1.11.1. Description of the Affected Environment ............................................4-135

4.1.11.2. Impacts of Routine Events ...................................................................4-137

4.1.11.3. Impacts of Accidental Events...............................................................4-141

4.1.11.4. Cumulative Impacts .............................................................................4-144

4.1.12. Commercial Fishing ..............................................................................................4-148

4.1.12.1. Description of the Affected Environment ............................................4-149

4.1.12.2. Impacts of Routine Events ...................................................................4-151

4.1.12.3. Impacts of Accidental Events...............................................................4-153

4.1.12.4. Cumulative Impacts .............................................................................4-155

4.1.13. Recreational Fishing..............................................................................................4-156

4.1.13.1. Description of the Affected Environment ............................................4-157

4.1.13.2. Impacts of Routine Events ...................................................................4-158

4.1.13.3. Impacts of Accidental Events...............................................................4-160

4.1.13.4. Cumulative Impacts .............................................................................4-161

4.1.14. Recreational Resources .........................................................................................4-162

4.1.14.1. Description of the Affected Environment ............................................4-162

4.1.14.2. Impacts of Routine Events ...................................................................4-164

4.1.14.3. Impacts of Accidental Events...............................................................4-165

4.1.14.4. Cumulative Impacts .............................................................................4-167

4.1.15. Archaeological Resources .....................................................................................4-169

4.1.15.1. Description of the Affected Environment ............................................4-170

4.1.15.2. Impacts of Routine Events ...................................................................4-172

4.1.15.3. Impacts of Accidental Events...............................................................4-176

4.1.15.4. Cumulative Impacts .............................................................................4-178

4.1.16. Human Resources and Land Use...........................................................................4-181

4.1.16.1. Land Use and Coastal Infrastructure....................................................4-181

4.1.16.1.1. Description of the Affected Environment .........................4-182

4.1.16.1.2. Impacts of Routine Events ................................................4-182

4.1.16.1.3. Impacts of Accidental Events............................................4-184

4.1.16.1.4. Cumulative Impacts...........................................................4-186

4.1.16.2. Demographics ......................................................................................4-187

4.1.16.2.1. Description of the Affected Environment .........................4-188

4.1.16.2.2. Impacts of Routine Events ................................................4-190

4.1.16.2.3. Impacts of Accidental Events............................................4-192

4.1.16.2.4. Cumulative Impacts...........................................................4-192

4.1.16.3. Economic Factors.................................................................................4-193

4.1.16.3.1. Decscription of the Affected Environment........................4-193

4.1.16.3.2. Impacts of Routine Events ................................................4-195

4.1.16.3.3. Impacts of Accidental Events............................................4-197

4.1.16.3.4. Cumulative Impacts...........................................................4-198

4.1.16.4. Environmental Justice ..........................................................................4-200

4.1.16.4.1. Description of the Affected Environment .........................4-201

4.1.16.4.2. Impacts of Routine Events ................................................4-203

4.1.16.4.3. Impacts of Accidental Events............................................4-205

4.1.16.4.4. Cumulative Impacts...........................................................4-206
xxii Central and Western Gulf of Mexico Multisale Supplemental EIS

4.2. Alternatives to the Proposed Actions...................................................................................4-209

4.2.1. Alternatives for Proposed Central Planning Area Sales 208, 213, 216, and 

222.........................................................................................................................4-209

4.2.1.1. Alternative B—The Proposed Actions Excluding the Unleased 

Blocks Near Biologically Sensitive Topographic Features..................4-209

4.2.1.2. Alternative C—The Proposed Actions Excluding Unleased 

Blocks within 15 Miles of the Baldwin County, Alabama, Coast .......4-211

4.2.1.3. Alternative D—No Action ...................................................................4-213

4.2.2. Alternatives for Proposed Western Planning Area Sales 210, 215, and 218.........4-215

4.2.2.1. Alternative B—The Proposed Actions Excluding the Unleased 

Blocks Near Biologically Sensitive Topographic Features..................4-215

4.2.2.2. Alternative C—No Action ...................................................................4-216

4.3. Unavoidable Adverse Impacts of the Proposed Actions......................................................4-218

4.4. Irreversible and Irretrievable Commitment of Resources....................................................4-219

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

Maintenance and Enhancement of Long-term Productivity ................................................4-220

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

5.1. Multisale EIS ...........................................................................................................................5-3

5.2. Development of the Proposed Actions.....................................................................................5-3

5.3. Notice of Intent to Prepare an SEIS and Call for Information and Nominations.....................5-3

5.4. Development of the Draft SEIS ...............................................................................................5-3

5.5. Distribution of the Draft SEIS for Review and Comment .......................................................5-4

5.6. Public Hearings........................................................................................................................5-8

5.7. Coastal Zone Management Act................................................................................................5-8

5.8. Endangered Species Act...........................................................................................................5-8

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

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

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

APPENDICES 

A. Figures .....................................................................................................................................A-3 

B. Tables ......................................................................................................................................B-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 Areas, 

the 181 South Area, and Locations of Major Cities..........................................................A-3 

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

Figure 2-2. Military Warning Areas in the Gulf of Mexico. ...............................................................A-5 

Figure 2-3. Economic Impact Areas in the Gulf of Mexico. ...............................................................A-6 

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

Figure 3-2. Leasing Activity and Infrastructure Near the 181 South Area..........................................A-8 

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

Figure 3-4. Probability (percent chance) of a Particular Number of Offshore Spills ≥1,000 bbl 

Occurring as a Result of Either Facility or Pipeline Operations Related to a CPA 

Proposed Action..............................................................................................................A-10 

Figure 3-5. Probability (percent chance) of a Particular Number of Offshore Spills ≥1,000 bbl 

Occurring as a Result of Either Facility or Pipeline Operations Related to a WPA 

Proposed Action..............................................................................................................A-10 

Figure 3-6. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days the 

Shoreline (counties and parishes) as a Result of a Proposed Action in the Western 

Planning Area (only counties and parishes with greater than a 0.5% risk of contact 

within 10 days are shown). .............................................................................................A-11 

Figure 3-7. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days the 

Shoreline (counties and parishes) as a Result of a Proposed Action in the Central 

Planning Area (only counties and parishes with greater than a 0.5% risk of contact 

within 10 days are shown). .............................................................................................A-11 

Figure 3-8. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

State Offshore Waters or Recreational Beaches as a Result of a CPA or WPA 

Proposed Action..............................................................................................................A-12 

Figure 3-9. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Endangered Beach Mice Habitats as a Result of a CPA or WPA Proposed Action. ......A-13 

Figure 3-10. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Known Locations of Gulf Sturgeon as a Result of CPA Proposed Action.....................A-14 

Figure 3-11. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days 

Gulf Sturgeon Critical Habitat as a Result of a CPA Proposed Action. .........................A-14 

Figure 3-12. Major Oil Pipeline Landfall Areas Developed for OSRA. .............................................A-15 

Figure 3-13. Spatial Frequency (%) of the Water Mass Associated with the Loop Current in the 

Eastern Gulf of Mexico Based on Data for the Period 1976-2003. ................................A-16 

Figure 4-1. Coastal and Marine Waters of the Gulf of Mexico.........................................................A-17 

Figure 4-2. Location of Topographic Features in the Gulf of Mexico. .............................................A-18 
List of Tables xxv 

LIST OF TABLES 

Page 

Table 3-1 Projected Oil and Gas Production in the Gulf of Mexico OCS.......................................... B-3 

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

Area .................................................................................................................................. B-4 

Table 3-3 Offshore Scenario Information Related to the Proposed Action in the Western 

Planning Area...................................................................................................................... B-5 

Table 3-4 Aggregate Average Lag in Months from Sales to First Spud for Leases Issued from 

1983 to 1999........................................................................................................................ B-6 

Table 3-5 Aggregate Average Lag in Months from Sales to First Production for Leases Issued 

from 1983 to 1999............................................................................................................... B-6 

Table 3-6 Mean Number and Sizes of Spills Estimated to Occur in OCS Offshore Waters from 

an Accident Related to Activities Supporting a Proposed Action Over a 40-Year Time 

Period .................................................................................................................................. B-7 

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

Accident Related to Activities Supporting a Proposed Action ........................................... B-8 

Table 3-8 Number and Volume of Chemical and Synthetic-Based Fluid Spills in the Gulf of 

Mexico during the Years 2001-2005................................................................................... B-9 

Table 3-9 Record of Past Spills Where >1,000 bbl of Synthetic-Based Fluid (SBF) was Released .. B-9 

Table 4-1 National Ambient Air Quality Standards (NAAQS)........................................................ B-10 

Table 4-2 Comparison of Hurricane-Induced Land to Water Changes by Hydrologic Basin in 

Coastal Louisiana during the 2005 Hurricane Season....................................................... B-11 

Table 4-3 Comparison of Habitats Affected by Storm-Induced Land/Water Change....................... B-11 

Table 4-4 Estimated Abundance of Cetaceans in the Northern Gulf of Mexico Oceanic Waters.... B-12 

Table 4-5 Sea Turtle Taxa of the Northern Gulf of Mexico.............................................................. B-13 

Table 4-6 2006 Top Species Commonly Caught by Recreational Fishers in the Marine 

Recreational Fisheries Statistics Gulf Coast States (except Texas) .................................. B-14 

Table 4-7 2006 Recreational Fishing Participation in the Marine Recreational Fisheries 

Statistics Gulf Coast States ............................................................................................... B-14

Table 4-8 2006 Mode of Fishing in the Marine Recreational Fisheries Statistics for the Gulf 

Coast States (except Texas)............................................................................................... B-15 

Table 4-9 Employment and Establishments in Tourism-Related Industries in 2005 by Coastal 

County and Parish ............................................................................................................. B-16 

Table 4-10 Number of Shipwrecks by Planning Area and Lease Area ............................................... B-17 

Table 4-11 Baseline Population Projections (in thousands) by Economic Impact Area ..................... B-18 

Table 4-12 Baseline Employment Projections (in thousands) by Economic Impact Area.................. B-19 
CHAPTER 1 

THE PROPOSED ACTIONS
The Proposed Actions 1-3 

1. THE PROPOSED ACTIONS 

1.1. PURPOSE OF AND NEED FOR THE PROPOSED ACTIONS

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

USDOI, MMS, 2007a), six annual areawide lease sales are 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 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 and are hereby incorporated by reference as the Multisale EIS (USDOI, MMS, 2007b). As of 

the publication of this draft supplemental environmental impact statement (SEIS), three of these sales 

have been held: WPA Sale 204 (August 2007), CPA Sale 205 (October 2007), and CPA Sale 206 (March 

2008). Environmental assessments were prepared for CPA Sale 206 (USDOI, MMS, 2007c) and WPA 

Sale 207 (USDOI, MMS, 2008). 

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

repeals the Congressional moratorium on certain areas of the Gulf of Mexico, places a moratorium on 

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

coastal States. 

The GOMESA defines two areas in the Gulf of Mexico – the 181 Area and the 181 South Area. 

Approximately 2 million acres (ac) of the 181 Area are located in the CPA. Because this portion was not 

previously under moratorium, it was included in the CPA proposed actions analyzed in the Multisale EIS 

and was available for lease starting with CPA Lease Sale 205 held on October 3, 2007. The remaining 

portion of the 181 Area is approximately 500,000 ac located in the Eastern Planning Area (EPA). The 

MMS published a Final SEIS in October 2007 on this eastern portion of the 181 Area, and it was offered 

in Lease Sale 224 on March 19, 2008. 

One of the areas the GOMESA defines is referred to as the 181 South Area (Figure 1-1). This area is 

located in the CPA and is approximately 5.8 million acres (ac). The Minerals Management Service 

(MMS) is proposing the sale area for proposed CPA Sales 208 (2009), 213 (2010), 216 (2011), and 222 

(2012) be expanded to include 4.3 million ac of the 181 South Area. The remaining acreage of the 181 

South Area (1.5 million ac) is located beyond the U.S. Exclusive Economic Zone (EEZ) and, therefore, 

would not be offered. While GOMESA repealed the Congressional moratorium on the 181 South Area in 

December 2006, MMS decided, because of the limited geological and geophysical data available to 

industry and the limited environmental review for this area, it would be premature to offer this area prior 

to CPA Sale 208 (2009). The Multisale EIS did not analyze the 181 South Area. Therefore, MMS has 

prepared this separate National Environmental Policy Act (NEPA) review to reevaluate the expanded 

CPA sale area. 

This SEIS supplements the Multisale EIS. Not only does this SEIS analyze the potential 

environmental effects of oil and natural gas leasing, exploration, development, and production in the 181 

South Area for the proposed CPA sales, but it also analyzes any new information available for the CPA 

and WPA (Sale 210 in 2009, Sale 215 in 2010, and Sale 218 in 2011) since the publication of the 

Multisale EIS. 

The purpose of these proposed Federal actions is to offer for lease those areas that may contain 

economically recoverable oil and gas resources. The proposed lease sales will provide qualified bidders 

the opportunity to bid upon and lease acreage in the Gulf of Mexico OCS in order to explore, develop, 

and produce oil and natural gas. This SEIS analyzes the potential impacts of the proposed actions on the 

marine, coastal, and human environments. No other NEPA documents will be prepared for proposed 

Lease Sale 208 in the CPA and proposed Lease Sale 210 in the WPA. An additional NEPA review will 

be conducted for each subsequent proposed lease sale in the 5-Year Program. Informal and formal 

consultations with other Federal agencies, the affected States, and the public will be carried out to assist 

in the determination of whether or not the information and analyses in this original SEIS are still valid 

and if there is sufficient NEPA review. These consultations and NEPA reviews will be completed before 

decisions are made on the subsequent sales. 
1-4 Central and Western Gulf of Mexico Multisale Supplemental EIS 

The Outer Continental Shelf Lands Act (OCSLA) of 1953 (67 Stat. 462), as amended (43 U.S.C. 

1331 et seq. (2008)), established Federal jurisdiction over submerged lands on the OCS seaward of the 

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 freemarket competition is maintained. The Act empowers the Secretary to grant leases to the highest 

qualified responsible bidder(s) on the basis of sealed competitive bids and to formulate such regulations 

as necessary to carry out the provisions of the Act. The Secretary has designated MMS as the 

administrative agency responsible for the mineral leasing of submerged OCS lands and for the 

supervision of offshore operations after lease issuance. 

The CPA and WPA constitute one of the world’s major oil- and gas-producing areas, and have proved 

a steady and reliable source of crude oil and natural gas for more than 50 years. Oil from the Gulf of 

Mexico can help reduce the Nation’s need for oil imports and reduce the environmental risks associated 

with oil tankering. Natural gas is generally considered to be an environmentally preferable alternative to 

oil, both in terms of the production and consumption. 

1.2. DESCRIPTION OF THE PROPOSED ACTIONS

The proposed actions are the remaining seven oil and gas lease sales in the CPA and WPA as 

scheduled for 2009-2012 under the 5-Year Program. Federal regulations allow for several related or 

similar proposals to be analyzed in one EIS (40 CFR 1502.4). Since the proposed lease sales in each 

lease sale area and their projected activities are very similar, MMS decided to prepare a single SEIS for 

the seven remaining CPA and WPA lease sales in the 5-Year Program. 

Proposed Central Planning Area Lease Sales 208, 213, 216, and 222 

The proposed CPA lease sales are Sale 208 in 2009, Sale 213 in 2010, Sale 216 in 2011, and Sale 222 

in 2012. The CPA sale area encompasses about 63 million ac of the CPA’s 66.3 million ac and is located 

3 nautical miles (nmi) offshore Louisiana, Mississippi, and Alabama and extends seaward to the limits of 

the U.S. OCS to 3,458 meters (m) (11,345 feet (ft)) (Figure 1-1). Each subsequent proposed CPA sale 

would offer for lease all unleased blocks in the CPA for oil and gas operations (Figure 1-1), with the 

following exceptions: 

(1) blocks directly south of Florida and within 100 miles (mi) of the Florida coast (north 

of the easternmost portion of the CPA sale area as shown on Figure 1-1); 

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

northern portion of the Eastern Gap; and 

(3) for Sales 208 and 213 only, whole and partial blocks that lie within the 1.4-nmi 

buffer zone 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 any one proposed CPA 

lease sale is 0.807-1.336 billion barrels of oil (BBO) and 3.365-5.405 trillion cubic feet (Tcf) of gas. The 

subsequent, proposed CPA lease sales include proposed lease stipulations designed to reduce 

environmental risks and are discussed in Chapter 2.3. 

Proposed Western Planning Area Lease Sales 210, 215, and 218 

The proposed WPA lease sales are Sale 210 in 2009, Sale 215 in 2010, and Sale 218 in 2011. The 

WPA encompasses about 28.7 million ac located 3 leagues (10.4 mi) offshore Texas and extends seaward 

to the limits of the U.S. OCS in water depths up to 3,346 m (10,978 ft) (Figure 1-1). Each WPA 

proposed lease sale would offer for lease all unleased blocks in the WPA for oil and gas operations 

(Figure 1-1), with the following exceptions: 
The Proposed Actions 1-5 

(1) whole and partial blocks within the boundary of the Flower Garden Banks National 

Marine Sanctuary; and 

(2) for Sales 210 and 215 only, whole and partial blocks that lie within the 1.4-nmi 

buffer zone north of the continental shelf boundary between the United States (U.S.) 

and Mexico. 

The estimated amount of resources projected to be developed as a result of any one proposed WPA 

lease sale is 0.242-0.423 BBO and 1.644-2.647 Tcf of gas. The proposed WPA lease sales include 

proposed lease stipulations designed to reduce environmental risks and are discussed in Chapter 2.4. 

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., National Environmental Policy Act). Several Federal regulations 

establish specific consultation and coordination processes with Federal, State, and local agencies (i.e., 

Coastal Zone Management Act, Endangered Species Act, the Magnuson Fishery Conservation and 

Management Act, and the Marine Mammal Protection Act). In addition, the OCS leasing process and all 

activities and operations on the OCS must comply with other Federal, State, and local laws and 

regulations. Chapter 1.3 of the Multisale EIS provided summaries of the major, applicable, Federal laws 

and regulations listed below: 

Outer Continental Shelf Lands Act 

National Environmental Policy Act 

Coastal Zone Management Act 

The Endangered Species Act 

The Magnuson Fishery Conservation and Management Act 

Essential Fish Habitat 

Essential Fish Habitat Consultation 

The Marine Mammal Protection Act 

The Clean Air Act 

The Clean Water Act 

Harmful Algal Bloom and Hypoxia Research and Control Act 

The Oil Pollution Act 

Comprehensive Environmental Response, Compensation, and Liability Act 

The Resource Conservation and Recovery Act 

Marine Plastic Pollution Research and Control Act 

National Fishing Enhancement Act 

Fishermen’s Contingency Fund 

Ports and Waterways Safety Act 

Marine and Estuarine Protection Acts 

Marine Protection, Research, and Sanctuaries Act 

National Estuarine Research Reserves 

The National Estuary Program 

Executive Order 11990 (May 24, 1977): Protection of Wetlands 

Coastal Barrier Resources Act 

The National Historic Preservation Act 

Rivers and Harbors Act 

Executive Order 12898: Environmental Justice 

Occupational Safety and Health Act 

Energy Policy Act of 2005 

Gulf of Mexico Energy Security Act of 2006 

Marine Debris Research, Prevention, and Reduction Act 
1-6 Central and Western Gulf of Mexico Multisale Supplemental EIS 

1.4. PRELEASE PROCESS

Scoping for this SEIS was conducted in accordance with CEQ regulations implementing NEPA. 

Scoping provides those with an interest in the OCS Program an opportunity to provide comments on the 

proposed lease sales. The scoping process officially commenced on September 10, 2007, with the 

publication of the Notice of Intent to Prepare an SEIS (NOI) and Scoping Meetings in the Federal 

Register. A 45-day comment period, which closed on October 25, 2007, was provided. 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 SEIS. Formal scoping meetings were held during 

October 2007 in Texas, Louisiana, and Alabama. All scoping comments received were considered in the 

preparation of the Draft SEIS. The comments (both verbal and written) have been summarized in 

Chapter 5.4, Development of the Draft SEIS. 

On August 10, 2006, the Area Identification (Area ID) decision was made for the proposed CPA and 

WPA lease sales in the 5-Year Program. On January 22, 2008, the Area ID decision was modified by 

adding the 181 South Area. The Area ID is an administrative prelease step that describes the 

geographical area of the proposed actions (proposed lease sale areas) and identifies the alternatives, 

mitigating measures, and issues to be analyzed in the appropriate NEPA document. As mandated by 

NEPA, this SEIS analyzes the potential impacts of the proposed actions on the marine, coastal, and 

human environments. 

The MMS is sending copies of this Draft SEIS for review and comment to public and private 

agencies, interest groups, and local libraries. To initiate the public review and comment period on this 

Draft EIS, MMS will publish a Notice of Availability (NOA) in the Federal Register. Additionally, 

public notices will be mailed with the Draft SEIS and placed on the MMS Internet website 

(http://www.gomr.mms.gov). In accordance with 30 CFR 256.26, MMS will hold public hearings to 

solicit comments on this Draft SEIS. The hearings provide the Secretary with information from interested 

parties to help in the evaluation of potential effects of the proposed lease sales. Notices of the public 

hearings are included in the NOA, posted on the MMS Internet website, and published in the Federal 

Register and local newspapers. 

The Final SEIS will be published approximately 5 months prior to the first proposed sale, CPA Sale 

208, which is scheduled for March 2009. To initiate the public review and 30-day minimum comment 

period on the Final EIS, MMS will publish a NOA in the Federal Register. The MMS will send copies of 

the Final EIS for review and comment to public and private agencies, interest groups, and local libraries. 

Additionally, public notices will be mailed with the Final EIS and placed on the MMS Internet website 

(http://www.gomr.mms.gov). 

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

each affected State prior to each proposed lease sale. To prepare the CD’s, MMS reviews each State’s 

Coastal Zone Management Program (CZMP) and analyzes the potential impacts as outlined in this SEIS, 

new information, and applicable studies as they pertain to the enforceable policies of each CZMP. Based 

on the analyses, the MMS Director makes an assessment of consistency, which is then sent to each State 

with the Proposed Notice of Sale (PNOS). If a State disagrees with MMS’s CD, the State is required to 

do the following under the Coastal Zone Management Act (CZMA): (1) indicate how the MMS presale 

proposal is inconsistent with their CZMP and suggest alternative measures to bring the MMS proposal 

into consistency with their CZMP or (2) describe the need for additional information that would allow a 

determination of consistency. Unlike the consistency process for specific OCS plans and permits, there is 

no procedure for administrative appeal to the Secretary of Commerce for a Federal CD for presale 

activities. Either MMS or the State may request mediation. Mediation is voluntary, and the Department 

of Commerce (DOC) would serve as the mediator. Whether there is mediation or not, the final CD is 

made by DOI and it is the final administrative action for the presale consistency process. Each Gulf 

State’s CZMP is described in Appendix B of the Multisale EIS (USDOI, MMS, 2007a). 

A PNOS will become available to the public 4-5 months prior to a proposed sale. A notice 

announcing the availability of the PNOS 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 Notice of Sale (FNOS), including lease sale configuration and terms and conditions. 
The Proposed Actions 1-7 

If the decision by the Assistant Secretary of the Interior for Land and Minerals (ASLM), under 

authority delegated by the Secretary of Interior, is to hold a proposed sale, a FNOS will be published in its 

entirety in the Federal Register at least 30 days prior to the sale date, as required by the OCSLA. 

This SEIS will be the only NEPA review conducted for CPA Sale 208 and WPA Sale 210. A lease 

sale EA will be conducted for each of the subsequent proposed lease sales to address any relevant new 

information. Informal and formal consultations with other Federal agencies, the affected States, and the 

public will be carried out to assist in the determination of whether or not the information and analyses in 

this EIS are still valid. Specifically, Information Requests will be issued soliciting input on the 

subsequent proposed lease sales. 

The EA will tier from this SEIS and will summarize and incorporate the material by reference. 

Because the EA will be prepared for a proposal that “is, or is closely similar to, one which normally 

requires the preparation of an EIS” (40 CFR 1501.4(e)(2)), the EA will be made available for public 

review for a minimum of 30 days prior to making a decision on the proposed lease sale. Consideration of 

the EA and any comments received in response to the Information Request will result in either a Finding 

of No New Significant Impact (FONNSI) or the determination that the preparation of an SEIS is 

warranted. If the EA results in a FONNSI, the EA and FONNSI will be sent to the Governors of the 

affected States. The availability of the EA and FONNSI will be announced in the Federal Register. The 

FONNSI will become part of the documentation prepared for the decision on the Notice of Sale. 

In some cases, the EA may result in a finding that it is necessary to prepare an SEIS (40 CFR 1502.9). 

Some of the factors that could justify an SEIS are a significant change in resource estimates, legal 

challenge on the EA/FONNSI, significant new information, significant new environmental issue(s), new 

proposed alternative(s), a significant change in the proposed action, or the analysis in this EIS is no longer 

deemed adequate. 

If an SEIS is necessary, it will also tier from this SEIS and will summarize and incorporate the 

material by reference. The analysis will focus on addressing the new issue(s) or concern(s) that prompted 

the decision to prepare the SEIS. The SEIS will include a discussion explaining the purpose of the SEIS, 

a description of the proposed action and alternatives, a comparison of the alternatives, a description of the 

affected environment for any potentially affected resources that are the focus of the SEIS and were not 

described in this EIS, an analysis of new impacts or changes in impacts from this SEIS because of new 

information or the new issue(s) analyzed in the SEIS, and a discussion of the consultation and 

coordination carried out for the new issues or information analyzed in the SEIS. 

1.5. POSTLEASE ACTIVITIES

The MMS is responsible for managing, regulating, and monitoring oil and natural gas exploration, 

development, and production operations on the Federal OCS to promote orderly development of mineral 

resources and to prevent harm or damage to, or waste of, any natural resource, any life or property, or the 

marine, coastal, or human environment. Regulations for oil, gas, and sulphur lease operations are 

specified in 30 CFR 250, 30 CFR 251, and 30 CFR 254. 

Measures to mitigate potential impacts are an integral part of the OCS Program. These measures are 

implemented through lease stipulations, operating regulations, Notices to Lessees and Operators (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, 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. A few examples of standard mitigation measures in the Gulf of Mexico 

OCS are 

• limiting the size of explosive charges used for structure removals; 

• requiring placement explosive charges at least 15 ft below the mudline; 

• requiring site-clearance procedures to eliminate potential snags to commercial 

fishing nets; 
1-8 Central and Western Gulf of Mexico Multisale 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 MMS issues NTL’s to provide clarification, description, or interpretation of a regulation; 

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

administrative information. A detailed listing of current Gulf of Mexico OCS Region NTL’s is available 

through the MMS, Gulf of Mexico OCS Region’s Internet website at 

http://www.gomr.mms.gov/homepg/regulate/regs/ntls/ntl_lst.html or through the Region’s Public 

Information Office at (504) 736-2519 or 1-800-200-GULF. 

Conditions of approval are mechanisms to control or mitigate potential safety or environmental 

problems associated with proposed operations. Conditions of approval are based on MMS technical and 

environmental evaluations of the proposed operations. Comments from Federal and State agencies (as 

applicable) are also considered in establishing conditions. Conditions may be applied to any OCS plan, 

permit, right-of-use of easement, or pipeline right-of-way grant. 

Some MMS-identified mitigation measures are implemented through cooperative agreements or 

efforts with the oil and gas industry and Federal and State agencies. These measures include the National 

Marine Fisheries Service (NMFS) 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. 

Chapter 1.5 of the Multisale EIS describes in detail these and other postlease activities, and associated 

regulations, review processes, and conditions of approval. 
CHAPTER 2 

ALTERNATIVES INCLUDING

THE PROPOSED ACTIONS
Alternatives Including the Proposed Actions 2-3 

2. ALTERNATIVES INCLUDING THE PROPOSED ACTIONS 

This SEIS addresses four areawide oil and gas lease sales in the CPA and three areawide oil and gas 

lease sales in the WPA of the Gulf of Mexico OCS (Figure 1-1), as scheduled in the proposed Outer 

Continental Shelf Oil and Gas Leasing Program: 2007-2012 (5-Year Program, USDOI, MMS, 2007a). 

Each of the proposed lease sales in a sale area is expected to be within the scenario ranges for the sale 

area; therefore, a CPA proposed action is representative of proposed CPA Lease Sales 208, 213, 216, and 

222, and a WPA proposed action is representative of proposed WPA Lease Sales 210, 215, and 218. 

Each proposed action (proposed lease sale) includes existing regulations and lease stipulations. 

The MMS has proposed no new alternatives or mitigations to the proposed CPA lease sales due to the 

addition of the 181 South Area. 

2.1. ALTERNATIVES, MITIGATING MEASURES, AND ISSUES

2.1.1. Alternatives 

2.1.1.1. Alternatives for Proposed Central Planning Area Sales 208, 213, 216, and 

222 

The following four alternatives were included for analysis in the Multisale EIS, and are described in 

detail in Chapter 2.2. As explained in Chapter 2.1.3.2, the Use of a Nomination and Tract Selection 

Leasing System Alternative was not included for analysis in this SEIS due to an ongoing MMS study on 

alternative approaches to leasing. No new alternatives were proposed due to the addition of the 181 South 

Area to the proposed CPA lease sales. 

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

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

(1) blocks that were previously included within the Eastern Planning Area (EPA) and 

that are within 100 mi of the Florida coast; 

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

as the northern portion of the Eastern Gap; and 

(3) for Sales 208 and 213 only, whole and partial blocks that lie within the 1.4-nmi 

buffer zone north of the continental shelf boundary between the U.S. and Mexico. 

The CPA sale area encompasses about 63 million ac of the CPA’s 66.3 million ac. Approximately 

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

projected to be developed as a result of any one proposed CPA lease sale is 0.807-1.336 BBO and 3.365-

5.405 Tcf of gas. 

Alternative B—The Proposed Actions 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 actions (Alternative A), with the exception of any unleased blocks subject to 

the Topographic Features Stipulation. No topographic features are located in the 181 South Area; 

therefore, no blocks located in the 181 South Area would be excluded under Alternative B. 

Alternative C—The Proposed Actions 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 actions (Alternative A), with the exception of any unleased blocks within 15 

mi (24 km) of the Baldwin County, Alabama, coast. The 181 South Area is located more than 90 mi (145 

km) south of the Baldwin County, Alabama; therefore, no blocks located in the 181 South Area would be 

excluded under Alternative C. 

Alternative D—No Action: This alternative is the cancellation of one or more proposed CPA lease 

sales, including leases that would be offered in the 181 South Area. The opportunity for development of 

the estimated 0.807-1.336 BBO and 3.365-5.405 Tcf of gas that could have resulted from a proposed 

CPA lease sale would be precluded or postponed. Any potential environmental impacts resulting from a 
2-4 Central and Western Gulf of Mexico Multisale Supplemental EIS

proposed lease sale would not occur or would be postponed. This is analyzed in the Final EIS for the 5-

Year Program. 

2.1.1.2. Alternatives for Proposed Western Planning Area Sales 210, 215, and 218 

The following four alternatives were included for analysis in the Multisale EIS, and are described in 

detail in Chapter 2.3. As explained in Chapter 2.1.3.2, the Use of a Nomination and Tract Selection 

Leasing System Alternative was not included for analysis in this SEIS due to an ongoing MMS study on 

alternative approaches to leasing. 

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

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

(1) whole and partial blocks within the boundary of the Flower Garden Banks National 

Marine Sanctuary; and 

(2) for Sales 210 and 215 only, whole and partial blocks that lie within the 1.4-nmi 

buffer zone north of the continental shelf boundary between the U.S. and Mexico. 

The WPA sale area encompasses about 28.7 million ac. Approximately 18.3 million ac (64%) of the 

WPA sale area is currently unleased. The estimated amount of resources projected to be developed as a 

result of any one proposed WPA lease sale is 0.242-0.423 BBO and 1.644-2.647 Tcf of gas. 

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

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

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

the Topographic Features Stipulation. 

Alternative C—No Action: This is the cancellation of one or more proposed WPA lease sales. The 

opportunity for development of the estimated 0.242-0.423 BBO and 1.644-2.647 Tcf of gas that could 

have resulted from a proposed WPA lease sale would be precluded or postponed. Any potential 

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

is analyzed in the Final EIS for the 5-Year Program. 

2.1.2. Mitigating Measures 

In 1978, Section 1508.20 of the Council on Environmental Quality (CEQ) defined mitigation as: 

• Avoidance—The avoidance of an impact altogether by not taking a certain action or 

part of an action. 

• Minimization—The minimizing of impacts by limiting the degree or magnitude of 

the action and its implementation. 

• Restoration—The rectifying of the impact by repairing, rehabilitation, or restoring 

the affected environment. 

• Maintenance—The reducing or eliminating of the impact over time by preservation 

and maintenance operations during the life of the action. 

• Compensation—The compensation for the impact by replacing or providing 

substitute resources or environments. 

2.1.2.1. Proposed Mitigating Measures Analyzed 

The potential mitigating measures included for analysis in this EIS were developed as the result of 

scoping efforts over a number of years for the continuing OCS Program in the Gulf of Mexico. Seven 

lease stipulations are proposed for all the CPA sales—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, and the Protected Species 

Stipulation. Four lease stipulations are proposed for the WPA sales—the Topographic Features 
Alternatives Including the Proposed Actions 2-5 

Stipulation, the Military Areas Stipulation, the Operations in the Naval Mine and Anti-Submarine 

Warfare Area Stipulation, and the Protected Species Stipulation. These measures will be considered for 

adoption by the ASLM, under authority delegated by the Secretary of Interior. The analysis of any 

stipulations as part of Alternative A does not ensure that the ASLM will make a decision to apply the 

stipulations to leases that may result from any proposed lease sale nor does it preclude minor 

modifications in wording during subsequent steps in the prelease process if comments indicate changes 

are necessary or if conditions change. 

Any stipulations or mitigation requirements to be included in a lease sale will be described for that 

lease sale. Mitigation 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 a lease sale, will undergo a NEPA review, and additional 

project-specific mitigations may be applied as conditions of plan approval. The MMS has the authority to 

monitor and enforce these conditions, and under 30 CFR 250 Subpart N, may seek remedies and penalties 

from any operator that fails to comply with the conditions of permit approvals, including stipulations and 

other mitigating measures. 

2.1.2.2. Existing Mitigating Measures 

This section discusses only mitigation measures that would be applied by MMS. Mitigating measures 

have been proposed, identified, evaluated, or developed through previous MMS 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 MMS review and approval to ensure compliance with established laws 

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

to MMS. Operational compliance of these mitigating measures is enforced through the MMS on-site 

inspection program. 

Mitigating measures that are a standard part of the MMS program ensure that the operations are 

always conducted in an environmentally sound manner (with a zero tolerance of pollution and with every 

regulatory effort to minimize any adverse impact of routine operations to the environment). For example, 

mitigating measures ensure site clearance procedures eliminate potential snags to commercial fishing nets 

and require surveys to detect and avoid archaeological sites and biologically-sensitive areas such as 

pinnacles, topographic features, and chemosynthetic communities. 

Some MMS-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 Service’s Observer Program to protect marine mammals and sea turtles during explosive 

removals, labeling operational supplies to track possible sources of accidental debris loss, development of 

methods of pipeline landfall to eliminate impacts to barrier beaches, and semiannual beach cleanup 

events. 

Site-specific mitigating measures are also applied by MMS during plan and permit reviews. The 

MMS 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 MMS in advance and may be applied whenever conditions warrant. Standard 

mitigation text is revised as often as is necessary (e.g., to reflect changes in regulatory citations, 

agency/personnel contact numbers, and internal policy). Site-specific mitigation categories include the 

following: air quality, archaeological resources, artificial reef material, chemosynthetic communities, 

Flower Garden Banks, topographic features, hard bottoms/pinnacles, military warning areas and Eglin 

Water Test Areas (EWTA’s), naval mine warfare areas, hydrogen sulfide, drilling hazards, remotely 

operated vehicle surveys, geophysical survey reviews, and general safety concerns. Site-specific 

mitigation types include the following: advisories, conditions of approval, hazard survey reviews, 

inspection requirements, notifications, post-approval submittals, reminders, and safety precautions. In 

addition to standard mitigations, MMS may also apply nonrecurring mitigating measures that are 

developed on a case-by-case basis. 

The MMS 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 
2-6 Central and Western Gulf of Mexico Multisale Supplemental EIS

requiring post-approval submittal of information within a specified timeframe after a triggering event that 

is currently tracked by MMS (e.g., end of operations reports for plans, construction reports for pipelines, 

and removal reports for structure removals). 

2.1.3. Issues 

Issues are defined by CEQ to represent those principal “effects” that an EIS should evaluate in-depth. 

Scoping identifies specific environmental resources and/or activities rather than “causes” as significant 

issues (CEQ Guidance on Scoping, April 30, 1981). The analysis in the EIS can then show the degree of 

change from present conditions for each issue due to the relevant actions related to the proposed actions. 

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 the scoping process or from 

comments on past EIS’s; 

• the resource/activity may be vulnerable to one or more of the impact-producing 

factors (IPF) associated with the OCS Program; a reasonable probability of an 

interaction between the resource/activity and IPF should exist; or 

• information that indicates a need to evaluate the potential impacts to a 

resource/activity has become available. 

2.1.3.1. Issues to be Analyzed 

Like the Multisale EIS, this SEIS 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. In addition, this SEIS addresses the potential 

environmental and socioeconomic effects of oil and natural gas leasing, exploration, development, and 

production in the 181 South Area, and any new information available for the remainder of the proposed 

sale areas since the publication of the Multisale EIS. 

2.1.3.2. Issues Considered but Not Analyzed 

As previously noted, the Council on Environmental Quality’s (CEQ’s) 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 and for this SEIS. After careful evaluation and study, the following categories were 

considered not to be significant issues related to the proposed actions 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 MMS, 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 actions and are forwarded to the appropriate program offices for their consideration. 

Programmatic issues including expansion of the sale areas, administrative boundaries, and royalty relief 

have been considered in the preparation of the EIS for the 5-Year Program. 
Alternatives Including the Proposed Actions 2-7 

Revenue Sharing 

A number of comments were received 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 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 Congress of the U.S. or the Department of 

the Interior, and their guiding regulations, statutes, and laws. 

The MMS 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 the Gulf of Mexico Energy Security Act of 2006 (GOMESA), the Gulf 

producing States (i.e., Texas, Louisiana, Mississippi, and Alabama) will receive an increased share of 

offshore oil and gas revenue. Beginning in FY 2007, and thereafter, Gulf producing States will receive 

37.5 percent of revenue from new leases issued in the 181 Area and 181 South Area. Beginning in FY 

2016, and thereafter, Gulf producing States will receive 37.5 percent from new leases in the existing areas 

available for leasing. The remaining 50 percent and 12.5 percent of the total revenues would be 

distributed to the U.S. Treasury and the Land and Water Conservation Fund (LWCF), respectively. 

The socioeconomic benefits and impacts to local communities are analyzed in Chapter 4 of this 

SEIS. 

Alternatives to Areawide Leasing 

The Multisale EIS analyzed the Use of a Nomination and Tract Selection Leasing System Alternative 

for both a CPA and WPA proposed action. Since the publication of the Multisale EIS, MMS has initiated 

a detailed analysis of alternative approaches to leasing that may serve to further the many goals of the 

OCSLA. As part of this analysis, specific criteria (“metrics”) based on statutory goals of the 5-year 

Program will be developed, and these criteria will be used to examine alternatives using statistical 

methods, laboratory experiments, and simulation. The analysis also will include the design of possible 

field tests and is expected to take about 2 years to complete. In addition, it is likely that MMS will spend 

another year on internal review, evaluation, and decisionmaking as the transition to a new administration 

is completed. If it is determined that some alternative approach to leasing is preferable, and depending on 

how long it takes to conduct and digest the analysis, the 5-Year Program for 2007-2012 could be adjusted 

accordingly, or the new approach could be subject to consideration through the public comment and 

review process leading to the subsequent 5-Year Program (2012-2017). 

The MMS must be cognizant of the effects any policy changes might have on the achievement of 

other statutory goals of the Federal OCS Program. Among these are expeditious and orderly development 

and maintaining a diverse and competitive industry. Areawide leasing allows smaller independent 

companies to rapidly produce low-resource, low-risk fields, while larger companies push technological 

development at a slower pace in deep water. Areawide leasing also encourages strong and innovative 

seismic exploration and geophysical contracting and processing industries. In addition, 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 may lead to undesirable socioeconomic disruptions in local coastal economies. The 

MMS expects our forthcoming, detailed analysis of alternatives to areawide leasing to address such 

possible consequences. Therefore, pending completion of that analysis, MMS believes that it is not 

appropriate to include the Use of a Nomination and Tract Selection Leasing System Alternative in this 

SEIS. 

2.2. PROPOSED CENTRAL PLANNING AREA LEASE SALES 208, 213, 216, AND 

222 

The following four alternatives were included for analysis in the Multisale EIS. As explained in 

Chapter 2.1.3.2, the Use of a Nomination and Tract Selection Leasing System Alternative was not 
2-8 Central and Western Gulf of Mexico Multisale Supplemental EIS

included for analysis in this SEIS due to an ongoing MMS study on alternative approaches to leasing. No 

new alternatives were proposed due to the addition of the 181 South Area to the proposed CPA lease 

sales. 

2.2.1. Alternative A—The Proposed Actions 

2.2.1.1. Description 

Alternative A would offer for lease all unleased blocks within the CPA including the 181 South Area 

(4.3 million ac) for oil and gas operations (Figure 1-1), except the following: 

(1) blocks that were previously included within the EPA and that are within 100 mi of 

the Florida coast; 

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

northern portion of the Eastern Gap; and 

(3) for Sales 208 and 213 only, whole and partial blocks that lie within the 1.4-nmi 

buffer zone north of the continental shelf boundary between the U.S. and Mexico. 

The CPA sale area encompasses about 63 million ac of the CPA’s 66.3 million ac. Approximately 

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

projected to be developed as a result of any one proposed CPA lease sale is 0.807-1.336 BBO and 3.365-

5.405 Tcf of gas. 

The analyses of impacts summarized below 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 impact-producing factors is included 

in Chapters 3.1.1, 3.1.2, and 3.2. 

2.2.1.2. Summary of Impacts 

Air Quality (Chapter 4.1.1) 

The MMS has reexamined the analysis for air quality presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS and the addition of the 181 

South Area to the proposed CPA sale area. No significant new information was found that would alter 

the impact conclusion for air quality presented in the Multisale EIS. Because the 181 South Area is 

nearly 130 mi (209 km) from the nearest coast, routine activities occurring in the area are expected to 

have minimal impact on onshore air quality. In addition, no additional large spills or blowouts are 

projected as a result of the addition of the 181 South Area. 

Emissions of pollutants into the atmosphere from the routine activities associated with the proposed 

action in the CPA 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 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 a proposed action are not expected to have 

concentrations that would change onshore air quality classifications. 

Water Quality 

Coastal Waters (Chapter 4.1.2.1) 

The MMS has reexamined the analysis for water quality presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS and on the addition of the 181 

South Area to the proposed CPA sale area. No significant new information was found that would alter 
Alternatives Including the Proposed Actions 2-9 

the impact conclusion for water quality presented in the Multisale EIS. The 181 South Area is located 

nearly 130 mi (209 km) from the nearest coast and is projected to result in a relatively minor amount of 

additional activity; therefore, no additional impacts on water quality are projected as a result of the 

inclusion of the 181 South Area. 

Impacts from routine activities associated with a proposed action would be minimal if all existing 

regulatory requirements are met. Coastal water impacts associated with routine activities include 

increases in turbidity resulting from pipeline installation and navigation canal maintenance, discharges of 

bilge and ballast water from support vessels, and run-off from shore-based facilities. Structure 

installation and removal and pipeline placement disturb the sediments and cause increased turbidity. 

Smaller spills (<1,000 barrels (bbl)) are not expected to significantly impact water quality in coastal 

waters. Larger spills, however, could impact water quality in coastal waters. Accidental chemical spills, 

release of SBF, and blowouts would have temporary localized impacts on water quality. 

Marine Waters (Chapter 4.1.2.2) 

The MMS has reexamined the analysis for water quality presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS and on the addition of the 181 

South Area to the proposed CPA sale area. No significant new information was found that would alter 

the impact conclusion for marine water quality presented in the Multisale EIS. The 181 South Area is 

located nearly 130 mi (209 km) from the nearest coast and is projected to result in a relatively minor 

amount of additional activity; therefore, no additional impacts on water quality are projected as a result of 

the inclusion of the 181 South Area. 

Impacts from routine activities associated with a proposed action would be minimal if all existing 

regulatory requirements are met. Marine 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 disturb the sediments and cause increased turbidity. In addition, marine water impacts 

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

Smaller spills (<1,000 bbl) are not expected to significantly impact water quality in marine waters. 

Larger spills, however, could impact water quality in marine waters. Accidental chemical spills, release 

of SBF, and blowouts would have temporary localized impacts on water quality. 

Sensitive Coastal Environments 

Coastal Barrier Beaches and Associated Dunes (Chapter 4.1.3.1) 

The MMS has reexamined the analysis for barrier islands and associated dunes presented in the 

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

and on the addition of the 181 South Area to the proposed CPA sale area. No significant new information 

was found that would alter the impact conclusion for barrier islands and associated dunes presented in the 

Multisale EIS. Due to both the distance from the proposed offshore activity (approximately 130 mi (209 

km)) and the prevailing easterly winds, activities associated with the 181 South Area are expected to have 

little to no affect on barrier islands. 

Routine activities in the CPA such as increased vessel traffic, maintenance dredging of navigation 

canals, and pipeline installation will cause negligible impacts and will 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 a CPA proposed action are anticipated to be minimal. 

Wetlands (Chapter 4.1.3.2) 

The MMS has reexamined the analysis for wetlands presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS and on the addition of the 181 
2-10 Central and Western Gulf of Mexico Multisale Supplemental EIS

South Area to the proposed CPA sale area. No significant new information was found that would alter 

the impact conclusion for wetlands presented in the Multisale EIS. Since the 181 South Area is 130 mi 

(209 km) from the nearest coast, the area has little potential for direct impact to coastal wetlands as a 

result of the proposed activities in that area. 

Effects to coastal wetlands from the primary impact-producing activities associated with a proposed 

action are expected to be low. The primary impact-producing activities associated with routine activities 

for the CPA proposed action that could affect wetlands include pipeline emplacement, construction, and 

maintenance; navigation channel use (vessel traffic) and maintenance; disposal of OCS-related wastes; 

and use and construction of support infrastructure in these coastal areas. Vessel traffic associated with a 

proposed action is expected to contribute minimally to the erosion and widening of navigation channels 

and canals. Deltaic Louisiana is expected to continue to experience the greatest loss of wetland habitat. 

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. 

Seagrass Communities (Chapter 4.1.3.3) 

The MMS has reexamined the analysis for seagrass communities presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS and on the 

addition of the 181 South Area to the proposed CPA sale area. No significant new information was found 

that would alter the impact conclusion for seagrass communities presented in the Multisale EIS. The 181 

South Area is located nearly 130 mi (209 km) from the nearest coast and is projected to result in a 

relatively minor amount of additional activity; therefore, no significant additional impacts on seagrass 

communities are projected as a result of the inclusion of the 181 South Area. 

Turbidity impacts from pipeline installation and maintenance dredging associated with a proposed 

action would be temporary and localized. The increment of impacts from service-vessel transit associated 

with a 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. 

Sensitive Offshore Benthic Resources 

Live Bottoms (Pinnacle Trend) (Chapter 4.1.4.1) 

The MMS has reexamined the analysis for live bottoms (Pinnacle Trend) presented in the Multisale 

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

addition of the 181 South Area to the proposed CPA sale area. No significant new information was found 

that would alter the impact conclusion for live bottoms (Pinnacle Trend) presented in the Multisale EIS. 

The 181 South Area is located 127 mi (204 km) from the Pinnacle Trend region, and the pinnacle habitat 

is deep, 200-400 ft (60-120 m); therefore, activity associated with the 181 South Area would not impact 

live bottoms. 

The combination of its depth (200-400 ft or 60-120 m), separation from sources of impacts as 

mandated by the Live Bottoms (Pinnacle Trend) Stipulation, and a community adapted to sedimentation 

makes damage to the ecosystem unlikely from routine activities associated with a CPA proposed action. 

In the unlikely event that oil from a subsurface spill would reach the biota of Pinnacle Trend 

communities, the effects would be primarily sublethal for adult sessile biota and there would be limited 

incidences of mortality. 

Topographic Features (Chapter 4.1.4.2) 

The MMS has reexamined the analysis for topographic features presented in the Multisale EIS, based 

on the additional information available since the publication of the Multisale EIS and on the addition of 
Alternatives Including the Proposed Actions 2-11 

the 181 South Area to the proposed CPA sale area. No significant new information was found that would 

alter the impact conclusion for topographic features presented in the Multisale EIS. New information was 

found that supports previous assessments and illustrates the potential effects of natural events, especially 

the cumulative impacts of hurricanes. Since the 181 South Area is 129 mi (207 km) from the nearest 

topographic feature, transiting service vessels would be the only likely impact from the 181 South Area 

on topographic features. Since the closest topographic feature habitats are deep, >183 ft (>56 m) to their 

tops, it is unlikely that the 181 South Area would result in any effect unless a transiting vessel has a 

catastrophic accident near a bank. 

The routine activities associated with a 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 Feature 

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 Stipulations would keep subsurface sources of spills away 

from the immediate vicinity of topographic features. 

Chemosynthetic and Nonchemosynthetic Deepwater Benthic Communities (Chapter 4.1.5) 

The MMS has reexamined the analysis for continental slope and deepwater resources presented in the 

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

and on the addition of the 181 South Area to the proposed CPA sale area. No significant new information 

was found that would alter the impact conclusion for continental slope and deepwater resources presented 

in the Multisale EIS. The 181 South Area is not expected to have any chemosynthetic or hard-bottom, 

nonchemosynthetic communities (such as deepwater corals) that would be exposed to any kind of impacts 

from routine activities or accidental events associated with a proposed action. There are no known 

surface amplitude anomalies in the 181 South Area, and this deep area is not underlain by salt structures 

that create conditions conducive to faulting and hydrocarbon flows similar to other areas of the Gulf. 

Chemosynthetic and nonchemosynthetic communities are susceptible to physical impacts from 

structure placement, anchoring, and pipeline installation associated with a proposed action; however, the 

provisions of NTL 2000-G20 greatly reduce the risk of these physical impacts by requiring avoidance of 

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

Even in situations where substantial burial of typical benthic infaunal communities occurred, 

recolonization from populations from widespread neighboring soft-bottom substrate would be expected 

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

associated with a 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 (Chapter 4.1.6) 

The MMS has reexamined the analysis of the 29 species of marine mammals occurring in the Gulf of 

Mexico presented in the Multisale EIS, based on the additional information available since the publication 

of the Multisale EIS and on the addition of the 181 South Area to the proposed CPA sale area. No 

significant new information was found that would alter the impact conclusion for marine mammals 

presented in the Multisale EIS. With the exception of manatees, any of the marine species that occur in 

the Gulf of Mexico may be found in the 181 South Area. However, the 181 South Area is not unique in 

regards to marine mammal distribution. Impacts from routine activities and accidental events occurring 

in the 181 South Area are similar to the rest of the sale area, and the impacts are not expected to have 

long-term adverse effects. 

Routine events related to a proposed action in the CPA, particularly when mitigated as required by 

MMS, are not expected to have long-term adverse effects on the size and productivity of any marine 

mammal species or population endemic to the northern Gulf of Mexico. Characteristics of impacts from 

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

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

sublethal impacts. 
2-12 Central and Western Gulf of Mexico Multisale Supplemental EIS

Sea Turtles (Chapter 4.1.7) 

The MMS has reexamined the analysis for the five sea turtles species that inhabit the Gulf of Mexico 

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

Multisale EIS and on the addition of the 181 South Area to the proposed CPA sale area. While 

information from the 5-year status reviews for federally listed sea turtles in the Gulf of Mexico was 

incorporated, there was no significant new information that would alter the impact conclusion for sea 

turtles presented in the Multisale EIS, and U.S. Fish and Wildlife Service (FWS) and NMFS 

recommended that the current listing classifications remain unchanged. Because the 181 South Area is 

nearly 130 mi (209 km) from the nearest coast, all five species of sea turtles may potentially exist within 

the 181 South Area, which appears to be an important habitat for leatherbacks. Impacts from routine 

activities and accidental events occurring in the 181 South Area are similar to the rest of the sale area. In 

most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil 

slick will result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and 

increased vulnerability to disease) to sea turtles. 

The routine activities of a proposed action are unlikely to have significant adverse effects on the size 

and recovery of any sea turtle species or population in the Gulf of Mexico. Accidental events associated 

with a 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 a 

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 will result in sublethal impacts. 

Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice (Chapter 4.1.8) 

The MMS has reexamined the analysis for beach mice presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS and on the addition of the 181 

South Area to the proposed CPA sale area. No significant 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, impacts associated with activities occurring in the 181 South Area are not expected to impact beach 

mice. 

An impact from consumption of beach trash and debris associated with a proposed action in the CPA 

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 (Chapter 4.1.9) 

The MMS has reexamined the analysis for coastal and marine birds presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS and on the 

addition of the 181 South Area to the proposed CPA sale area. No significant new information was found 

that would alter the impact conclusion for coastal and marine birds presented in the Multisale EIS. Use of 

the 181 South Area by breeding or nonbreeding seabirds is unknown; however, the 181 South Area is 

located nearly 130 mi (209 km) from the nearest coast and is projected to result in a relatively minor 

amount of additional activity. Therefore, no additional impacts on coastal and marine birds are projected 

as a result of the inclusion of the 181 South Area. Disturbance to seabirds in the 181 South Area would 

be similar to disturbance to the birds in the other offshore waters of the proposed lease sale areas. 

Endangered or threatened bird species (i.e., piping plover, whooping crane, and brown pelican) that 

inhabit or frequent the north-central and western Gulf of Mexico coastal areas are not expected to occur in 

the 181 South Area. 

The majority of effects resulting from routine activities associated with a proposed action in the CPA 

on endangered/threatened and nonendangered/nonthreatened coastal and marine birds are expected to be 

sublethal. These activities include behavioral effects, exposure to or intake of OCS-related contaminants 

or discarded debris, temporary disturbances, and displacement of localized groups from impacted 
Alternatives Including the Proposed Actions 2-13 

habitats. Impacts from potential oil spills associated with a 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. 

Endangered and Threatened Fish 

Gulf Sturgeon (Chapter 4.1.10.1) 

The MMS has reexamined the analysis for Gulf sturgeon presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS and on the addition of the 181 

South Area to the proposed CPA sale area. No significant new information was found that would alter 

the impact conclusion for Gulf sturgeon presented in the Multisale EIS. The 181 South Area is nearly 

130 mi (209 km) from the nearest coast, and it is not located within the designated critical habitat for Gulf 

sturgeon. It is extremely unlikely that there will be any sturgeon in the 181 South Area due to water 

depths that far exceed the recorded depths preferred by this sturgeon species. In addition, substrate type 

and potential forage base associated with bottom types at these depths are not conducive for sustaining a 

Gulf sturgeon food base. 

Routine activities in the CPA such as installation of pipelines, maintenance dredging, potential vessel 

strikes, and nonpoint source runoff from onshore facilities will cause negligible impacts and will 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 (Chapter 4.1.11) 

The MMS has reexamined the analysis for fisheries and EFH presented in the Multisale EIS, based on 

the additional information available since the publication of the Multisale EIS and on the addition of the 

181 South Area to the proposed CPA sale area. No significant new information was found that would 

alter the impact conclusion for fisheries and EFH presented in the Multisale EIS. Due to the extreme 

depths in this area, the only managed fish species (and their pelagic EFH) are some of the highly 

migratory species including sharks, billfish, and tuna. The 181 South Area is located in very deep water 

(> 2,600 m) and limited activities in that area would not have any measurable additional impacts to fish 

resources or EFH for highly migratory species (the only managed species group that far offshore). 

Fish resources and EFH could be impacted by coastal environmental degradation, marine 

environmental degradation, pipeline trenching, and offshore discharges of drilling fluids and produced 

waters associated with routine activities. The impact of coastal and marine environmental degradation is 

expected to cause an undetectable decrease in fish resources or in EFH. Impacts of routine discharges are 

localized in time and space and are regulated by U.S. Environmental Protection Agency (USEPA) permits 

and will have minimal impact. Accidental events that could impact fish resources and EFH include 

blowouts and oil or chemical spills. A subsurface blowout would have a negligible effect on Gulf of 

Mexico fish resources. If spills due to a 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. 

Commercial Fishing (Chapter 4.1.12) 

The MMS has reexamined the analysis for commercial fishing presented in the Multisale EIS, based 

on the additional information available since the publication of the Multisale EIS and on the addition of 

the 181 South Area to the proposed CPA sale area. New fishery statistics analyzed and the addition of the 

181 South Area do not change the conclusion in the Multisale EIS that impacts on the commercial 

fisheries from the proposed action would be minimal. 

Routine activities in the CPA such as seismic surveys and pipeline trenching will cause negligible 

impacts and will not deleteriously affect commercial fishing activities. Indirect impacts from routine 

activities to inshore habitats are negligible and indistinguishable from direct impacts of inshore activities 
2-14 Central and Western Gulf of Mexico Multisale Supplemental EIS

on commercial fisheries. The potential impacts from accidental events, a well blowout, or an oil spill 

associated with a 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 to natural variability. 

Recreational Fishing (Chapter 4.1.13) 

The MMS has reexamined the analysis for recreational fishing presented in the Multisale EIS, based 

on the additional information available since the publication of the Multisale EIS and on the addition of 

the 181 South Area to the proposed CPA sale area. New information was not significantly different from 

that provided in the Multisale EIS; therefore, no information was found that would alter the conclusions 

in the Multisale EIS that impacts on the recreational fisheries from accidental events associated with a 

CPA proposed action would be minimal. The inclusion of 181 South Area will have no direct routine 

impacts on recreational fishing due to its distance (130 mi (209 km)) from the nearest shore. Indirect 

impacts resulting from an incremental increase of vessel trips from activities in the 181 South Area are 

expected to be negligible. 

Routine activities in the CPA such as seismic surveys and pipeline trenching will cause negligible 

impacts and will not deleteriously affect recreational fishing activities. Indirect impacts to inshore 

habitats are negligible and indistinguishable from direct impacts of inshore activities on commercial 

recreational fisheries. Temporary localized impacts from oil spills are anticipated as a result of a CPA 

proposed action, which would include temporary inconvenience to recreational fishermen and possibly 

some loss of revenue to facilities supported by recreational fishermen such as boat launches and bait 

shops. 

Recreational Resources (Chapter 4.1.14) 

The MMS has reexamined the analysis for recreational resources presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS and on the 

addition of the 181 South Area to the proposed CPA sale area. No significant new information was found 

that would alter the impact conclusion for recreational resources presented in the Multisale EIS. The 181 

South Area is located nearly 130 mi (209 km) from the nearest coast, far distant from recreational 

beaches, out of sight from land, and out of range for most recreational fishing. The inclusion of the 181 

South Area is projected to result in a relatively minor amount of additional activity, limiting potential 

impacts from traffic and from trash and debris. The location of the 181 South Area and limited activities 

that are expected to result also limit potential impacts from oil spills. Therefore, no additional impacts on 

recreational resources are projected as a result of the inclusion of the 181 South Area. 

While marine debris and nearshore operations, either individually or collectively, may adversely 

affect the quality of some recreational experiences, they are unlikely to reduce the number of recreational 

visits to Gulf coastal beaches. It is unlikely that a spill would be a major threat to recreational beaches 

because any impacts would be short-term and localized, and should have no long-term effect on tourism. 

Archaeological Resources (Chapter 4.1.15) 

The MMS has reexamined the analysis for prehistoric and historic archaeological resources presented 

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

EIS and on the addition of the 181 South Area to the proposed CPA sale area. No significant new 

information was found that would alter the impact conclusion for archaeological resources presented in 

the Multisale EIS. Given the extreme water depths in the 181 South Area, no prehistoric archaeological 

resources would likely be encountered in this area. Areas considered by MMS to have a high probability 

for historic period shipwrecks are located throughout the Gulf of Mexico, including the 181 South Area. 

The greatest potential impact to an archaeological resource as a result of routine activities associated 

with a proposed action in the CPA would result from direct contact between an offshore activity (i.e., 

platform installation, drilling rig emplacement, and dredging or pipeline project) and a prehistoric or 

historic 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 
Alternatives Including the Proposed Actions 2-15 

significant and/or unique archaeological information. It is expected that coastal archaeological resources 

will 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 will occur and contact coastal prehistoric or historic 

archaeological sites from accidental events associated with a CPA 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. 

Human Resources and Land Use 

Land Use and Coastal Infrastructure (Chapter 4.1.16.1) 

The MMS has reexamined the analysis for land use and coastal infrastructure presented in the 

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

the supplemental information found since completion of the Multisale EIS, and the addition of the 181 

South Area to the proposed CPA sale area. Although the addition of the 181 South Area resulted in some 

increases in the activity scenario for a typical CPA proposed action, these minor increases in activity were 

not significant enough to affect the long-term (i.e., 40-year) forecasts of coastal infrastructure needs to 

support either a typical CPA sale or the OCS Program. To date, no new information has been found that 

necessitates a change to the coastal infrastructure scenario presented in the Multisale EIS. The MMS 

recently analyzed historical data and validated past scenario projections of new pipeline landfalls and new 

onshore waste disposal sites. Based on the lack of significant new information and MMS’s recent 

analysis, the coastal infrastructure projections have not changed for a proposed lease sale or for the OCS 

Program. 

A proposed action in the CPA (i.e., including the 181 South Area) 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 a 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 clean up of any oil or chemicals spilled. 

Demographics (Chapter 4.1.16.2) 

The MMS has reexamined the analysis for demographics presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS and on the addition of the 181 

South Area to the proposed CPA sale area. No significant new information was found that would alter 

the impact conclusion for demographics presented in the Multisale EIS. The 181 South Area is located 

nearly 130 mi (209 km) from the nearest coast and is projected to result in a relatively minor amount of 

additional activity; therefore, no additional impacts on employment, or the resulting population and 

demographics, are projected as a result of the inclusion of the 181 South Area. 

A CPA proposed action (including the 181 South Area) is projected to minimally affect the 

demography of the analysis area. Population impacts from a proposed action are projected to be minimal 

(<1% of total population) for any EIA 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 a 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) projected to move into focal areas, such as Port Fourchon. Accidental events 

associated with a 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. 
2-16 Central and Western Gulf of Mexico Multisale Supplemental EIS

Economic Factors (Chapter 4.1.16.3) 

The MMS has reexamined the analysis for economic factors presented in the Multisale EIS, based on 

the additional information available since the publication of the Multisale EIS and on the addition of the 

181 South Area to the proposed CPA sale area. New economic and demographic data (Woods & Poole 

Economics, Inc., 2007) analyzed and the addition of the 181 South Area does not change the conclusions 

in the Multisale EIS, which stated that there would be only minor economic changes in the Texas, 

Louisiana, Mississippi, Alabama, and Florida EIA’s should a proposed CPA lease sale occur. A proposed 

action is expected to generate less than a 1 percent increase in employment in any of these subareas, even 

when the net employment impacts from accidental events are included. Most of the employment related 

to a proposed action is expected to occur in Texas and Louisiana. The demand will be met primarily with 

the existing population and labor force. 

Environmental Justice (Chapter 4.1.16.4) 

The MMS has reexamined the analysis for environmental justice presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS and on the 

addition of the 181 South Area to the proposed CPA sale area. No significant new information was found 

that would alter the impact conclusion for environmental justice as presented in the Multisale EIS. The 

181 South Area is located at the eastern edge of the CPA sale area nearly 130 mi (209 km) from the 

nearest coast. Also, the 181 South Area is projected to result in a relatively minor amount of additional 

sale-related activity. This limited activity will have few impacts; the location of the 181 South Area 

means that any impacts that may result are unlikely to be concentrated in an area that could 

disproportionately impact minority or low income people. Therefore, no additional impacts on minority 

or low-income people are projected as a result of the inclusion of the 181 South Area. 

Because the proposed CPA sale area lies 3 or more miles (4.8 or more kilometers) offshore, no 

activities that occur on the resulting leases (and that are regulated by MMS) will impact 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 actions are 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. 

2.2.1.3. Mitigating Measures 

The following seven environmental and military mitigations, referred to as lease stipulations, were 

included for analysis in the Multisale EIS (Chapter 2.4.1.3 of the Multisale EIS). Any stipulations or 

mitigation requirements to be included in a lease sale will be described in detail in the FNOS for that 

lease sale. Stipulations or mitigation requirements in addition to the those analyzed in this SEIS can also 

be developed and applied, and will also be described in detail in the FNOS. 

No new lease stipulations were proposed due to the addition of the 181 South Area to the proposed 

CPA lease sales. Four of the seven stipulations are applicable to the 181 South Area. They are the 

Military Areas Stipulation, the Evacuation Stipulation, the Coordination Stipulation, and the Protected 

Species Stipulation (Figures 2-1 and 2-2). The Topographic Features Stipulation, the Live Bottom 

Stipulation, and the Blocks South of Baldwin County, Alabama, Coast Stipulation are not applicable to 

the 181 South Area. 

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 

muds and cuttings from impacting the biota of the banks. Although the deferral of blocks with 

topographic features has been analyzed as an alternative in EIS’s and EA’s for all recent CPA and WPA 
Alternatives Including the Proposed Actions 2-17 

sales, this alternative has never been selected. 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. 

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 2-2 shows the military warning areas in the Gulf of Mexico. 

The Protected Species Stipulation has been applied to all blocks leased in the GOM since December 

2001. This stipulation was developed in consultation with DOC, National Oceanic and Atmospheric 

Administration (NOAA), NMFS, and FWS in accordance with Section 7 of the Endangered Species Act 

of 1973 (ESA) and is designed to minimize or avoid potential adverse impacts to federally protected 

species. 

The Live Bottom (Pinnacle Trend) Stipulation covers a small portion of the northeastern CPA sale 

area that is characterized by a pinnacle trend, which is classified as a live bottom under the stipulation. 

The MMS developed the stipulation to protect biological resources in the Pinnacle Trend 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 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) Stipulation is shown on Figure 2-1. 

The Evacuation Stipulation would apply to any lease in the easternmost portion of the CPA 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 will serve to eliminate dangerous conflicts between oil and gas operations and military 

operations. 

The Coordination Stipulation would apply to any lease in the easternmost portion of the CPA sale 

area. This stipulation was developed in consultation with DOD to address specific potential use conflict 

issues between oil and gas operations and military operations in the GOM. A coordination stipulation has 

been applied to all blocks leased in this area since 2001. This stipulation would provide for the review of 

pending oil and gas operations by military authorities and could result in delaying oil and gas operations 

if military activities have been scheduled in the area that may put the oil and gas operations and personnel 

at risk. 

The Blocks South of Baldwin County, Alabama, Stipulation will 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 MMS, 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 Central Gulf of Mexico lease sales 

since 1999. 
2-18 Central and Western Gulf of Mexico Multisale Supplemental EIS

2.2.2. Alternative B—The Proposed Actions Excluding the Unleased Blocks Near 

the Biologically Sensitive Topographic Features 

2.2.2.1. Description 

Alternative B differs from Alternative A by not offering the blocks that are possibly affected by the 

proposed Topographic Features Stipulation (Chapter 2.2.1.3.1 and Figure 2-1). All of the assumptions 

(including the six other potential mitigating measures) and estimates are the same as for Alternative A. A 

description of Alternative A is presented in Chapter 2.2.1.1. 

No topographic features are located in the 181 South Area; therefore, no blocks located in the 181 

South Area would be excluded under Alternative B. 

2.2.2.2. Summary of Impacts 

The analyses of impacts summarized in Chapter 2.2.1.2 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 

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 assumption that the levels of activity for Alternative 

B are essentially the same as those projected for the proposed actions leads to the conclusion that the 

impacts expected to result from Alternative B would be very similar to those described under the 

proposed actions (Chapter 4.1). Therefore, the regional impact levels for all resources, except for the 

topographic features, would be similar to those described under the proposed actions. 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. 

2.2.3. Alternative C—The Proposed Actions Excluding the Unleased Blocks 

within 15 Miles of the Baldwin County, Alabama, Coast 

2.2.3.1. 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 six other potential mitigating 

measures) and estimates are the same as for Alternative A (Chapters 2.2.1.3 and 4.1). A description of 

Alternative A is presented in Chapter 2.2.1.1. The coastal region adjacent to the area considered under 

Alternative C is designated EIA AL-1 (Figure 2-3). 

The 181 South Area is located more than 90 mi (145 km) south of the Baldwin County, Alabama, 

coast; therefore, no blocks located in the 181 South Area would be excluded under Alternative C. 

2.2.3.2. Summary of Impacts 

The analyses of impacts summarized Chapter 2.2.1.2 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 coast (Figure 2-1). The assumption that the levels of activity for Alternative C are 

essentially the same as those projected for the proposed actions leads to the conclusion that the impacts 

expected to result from Alternative C would be very similar to those described under the proposed actions 

(Chapter 4.1). Therefore, the regional impact levels for all resources, except recreational beaches, would 
Alternatives Including the Proposed Actions 2-19 

be similar to those described under the proposed actions. This alternative, if adopted, would reduce the 

potential aesthetic impacts to recreational beaches along the Baldwin County coast. 

2.2.4. Alternative D—No Action 

2.2.4.1. Description 

Alternative D is the cancellation of one or more of the proposed CPA lease sales including leases that 

would be offered in the 181 South Area. The opportunity for development of the estimated 0.807-1.336 

BBO and 3.365-5.405 Tcf of gas that could have resulted from a proposed lease sale would be precluded 

or postponed. Any potential environmental impacts resulting from the proposed lease sales would not 

occur or would be postponed. 

2.2.4.2. Summary of Impacts 

If Alternative D is selected, all impacts, positive and negative, associated with the proposed lease 

sales discussed in Chapter 4.1 would be eliminated. . The incremental contribution of the proposed 

lease sales to cumulative effects would also be foregone, but effects from other activities, including other 

OCS lease sales, would remain. 

If a lease sale would be cancelled, 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. However, the cancellation of a 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. 

2.3. PROPOSED WESTERN PLANNING AREA LEASE SALES 210, 215, AND 218 

The following three alternatives were included for analysis in the Multisale EIS. As explained in 

Chapter 2.1.3.2 of this SEIS, the Use of a Nomination and Tract Selection Leasing System Alternative 

was not included for analysis in this SEIS due to an ongoing MMS study on alternative approaches to 

leasing. 

2.3.1. Alternative A—The Proposed Actions 

2.3.1.1. Description 

Alternative A would offer for lease all unleased blocks within the WPA for oil and gas operations 

(Figure 2-1), except the following: 

(1) whole and partial blocks within the boundary of the Flower Garden Banks National 

Marine Sanctuary; and 

(2) for Sales 210 and 215 only, whole and partial blocks that lie within the 1.4-nmi 

buffer zone north of the continental shelf boundary between the U.S. and Mexico. 

The WPA sale area encompasses about 28.7 million ac. Approximately 18.3 million ac (64%) of the 

WPA sale area is currently unleased. The estimated amount of resources projected to be developed as a 

result of any one proposed WPA lease sale is 0.242-0.423 BBO and 1.644-2.647 Tcf of gas. 

The analyses of impacts summarized below 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 impact-producing factors is included 

in Chapter 3. 
2-20 Central and Western Gulf of Mexico Multisale Supplemental EIS

2.3.1.2. Summary of Impacts 

Air Quality (Chapter 4.1.1) 

The MMS has reexamined the analysis for air quality presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS. No significant new 

information was found that would alter the impact conclusion for air quality presented in the Multisale 

EIS. 

Emissions of pollutants into the atmosphere from the routine activities associated with the proposed 

action in the WPA 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 H2S could result in deaths as well 

as environmental damage. These emissions from routine activities and accidental events associated with 

a proposed action are not expected to have concentrations that would change onshore air quality 

classifications. 

Water Quality 

Coastal Waters (Chapter 4.1.2.1) 

The MMS has reexamined the analysis for water quality presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS. No significant new 

information was found that would alter the impact conclusion for water quality presented in the Multisale 

EIS. 

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. Impacts from routine activities associated with a 

proposed action would be minimal if all existing regulatory requirements are met. Smaller spills (<1,000 

bbl) are not expected to significantly impact water quality in coastal waters. Larger spills, however, could 

impact water quality in coastal waters. Accidental chemical spills, release of SBF, and blowouts would 

temporary localized impacts on water quality. 

Marine Waters (Chapter 4.1.2.2) 

The MMS has reexamined the analysis for water quality presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS. No significant new 

information was found that would alter the impact conclusion for water quality presented in the Multisale 

EIS. 

Marine 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, marine water impacts result from supply and 

service-vessel bilge and ballast water discharges. Impacts from routine activities associated with a 

proposed action would be minimal if all existing regulatory requirements are met. Smaller spills (<1,000 

bbl) are not expected to significantly impact water quality in marine waters. Larger spills, however, could 

impact water quality in marine waters. Accidental chemical spills, release of SBF, and blowouts would 

have temporary localized impacts on water quality. 
Alternatives Including the Proposed Actions 2-21 

Sensitive Coastal Environments 

Coastal Barrier Beaches and Associated Dunes (Chapter 4.1.3.1) 

The MMS has reexamined the analysis for barrier islands and associated dunes presented in the 

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

No significant new information was found that would alter the impact conclusion for barrier islands and 

associated dunes presented in the Multisale EIS. 

Routine activities in the WPA such as increased vessel traffic, maintenance dredging of navigation 

canals, and pipeline emplacement will cause negligible impacts and will not deleteriously affect barrier 

beaches and associated dunes. Indirect impacts from routine impacts are negligible and indistinguishable 

from direct impacts of onshore activities. The potential impacts from accidental events, primarily oil 

spills, are anticipated to be minimal. 

Wetlands (Chapter 4.1.3.2) 

The MMS has reexamined the analysis for wetlands presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS. No significant new 

information was found that would alter the impact conclusion for wetlands presented in the Multisale EIS 

Effects to coastal wetlands from the primary impact-producing activities associated with a proposed 

action are expected to be low. The primary impact-producing activities associated with routine activities 

for the WPA proposed action that could affect wetlands include pipeline emplacement, construction and 

maintenance, navigation channel use (vessel traffic) and maintenance, disposal of OCS-related wastes, 

and the use and construction of support infrastructure in these coastal areas. Vessel traffic associated with 

a proposed action is expected to contribute minimally to the erosion and widening of navigation channels 

and canals. 

Routine activities in the WPA such as pipeline emplacement, navigational channel use, maintenance 

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

coastal wetlands 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. 

Seagrass Communities (Chapter 4.1.3.3) 

The MMS has reexamined the analysis for seagrass communities presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS. No significant 

new information was found that would alter the impact conclusion for seagrass communities presented in 

the Multisale EIS. 

Turbidity impacts from pipeline installation and maintenance dredging associated with a proposed 

action would be temporary and localized. The increment of impacts from service-vessel transit associated 

with a 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. 

Sensitive Offshore Benthic Resources 

Topographic Features (Chapter 4.1.4.2) 

The MMS has reexamined the analysis for topographic features presented in the Multisale EIS, based 

on the additional information available since the publication of the Multisale EIS. No significant new 

information was found that would alter the impact conclusion for topographic features presented in the 

Multisale EIS. New information was found that supports previous assessments and illustrates the 

potential effects of natural events, especially the cumulative impacts of hurricanes. 
2-22 Central and Western Gulf of Mexico Multisale Supplemental EIS

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

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

presented in Chapter 4.1. A summary of these potential impacts are as follows. The routine activities 

associated with a WPA 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 Feature Stipulation would 

make damage to the ecosystem unlikely. Contact with accidentally spilled oil would cause lethal and 

sublethal effects in benthic organisms but the oiling of benthic organisms is not likely because of the 

small area of the banks, the scattered occurrence of spills, the depth of the features, and because the 

proposed Topographic Features Stipulation would keep subsurface sources of spills away from the 

immediate vicinity of topographic features. 

Chemosynthetic and Nonchemosynthetic Deepwater Benthic Communities (Chapter 4.1.5) 

The MMS has reexamined the analysis for continental slope and deepwater resources presented in the 

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

No significant new information was found that would alter the impact conclusion for continental slope 

and deepwater resources presented in the Multisale EIS. 

Chemosynthetic and nonchemosynthetic communities are susceptible to physical impacts from 

structure placement, anchoring, and pipeline installation associated with a proposed action; however, the 

provisions of NTL 2000-G20 greatly reduce the risk of these physical impacts by requiring avoidance of 

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

Even in situations where substantial burial of typical benthic infaunal communities occurred, 

recolonization from populations from widespread neighboring soft-bottom substrate would be expected 

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

associated with a 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 (Chapter 4.1.6) 

The MMS has reexamined the analysis of the 29 species of marine mammals occurring in the Gulf of 

Mexico presented in the Multisale EIS, based on the additional information available since the publication 

of the Multisale EIS. No significant new information was found that would alter the impact conclusion 

for marine mammals presented in the Multisale EIS. 

Routine events related to a proposed action in the WPA, particularly when mitigated as required by 

MMS, are not expected to have long-term adverse effects on the size and productivity of any marine 

mammal species or population endemic to the northern Gulf of Mexico. Characteristics of impacts from 

accidental events depend on chronic or acute exposure resulting in harassment, harm, or mortality to 

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

Sea Turtles (Chapter 4.1.7) 

The MMS has reexamined the analysis for the five sea turtles species that inhabit the Gulf of Mexico 

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

Multisale EIS. While information from the 5-year status reviews for federally listed sea turtles in the Gulf 

of Mexico was incorporated, there was no significant new information that would alter the impact 

conclusion for sea turtles presented in the Multisale EIS, and FWS and NMFS recommended that the 

current listing classifications remain unchanged. 

The routine activities of a proposed action in the WPA, when mitigated as required by MMS, are 

unlikely to have significant adverse effects on the size and recovery of any sea turtle species or population 

in the Gulf of Mexico. Accidental events associated with a 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 a 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 
Alternatives Including the Proposed Actions 2-23 

most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil 

slick will result in sublethal impacts. 

Coastal and Marine Birds (Chapter 4.1.9) 

The MMS has reexamined the analysis for coastal and marine birds presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS. No significant 

new information was found that would alter the impact conclusion for coastal and marine birds presented 

in the Multisale EIS. 

The majority of effects resulting from routine activities associated with a proposed action in the WPA 

on endangered/threatened and nonendangered/nonthreatened coastal and marine birds are expected to be 

sublethal. The routine activities 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 a 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. 

Fish Resources and Essential Fish Habitat (Chapter 4.1.11) 

The MMS has reexamined the analysis for fisheries and EFH) presented in the Multisale EIS, based 

on the additional information available since the publication of the Multisale EIS. No significant new 

information was found that would alter the impact conclusion for fisheries and EFH presented in the 

Multisale EIS. 

Fish resources and EFH could be impacted by coastal environmental degradation, marine 

environmental degradation, pipeline trenching, and offshore discharges of drilling discharges and 

produced waters associated with routine activities. The impact of coastal and marine environmental 

degradation is expected to cause an undetectable decrease in fish resources or in EFH. Impacts of routine 

discharges are localized in time and space and are regulated by USEPA permits and will have minimal 

impact. Accidental events that could impact fish resources and EFH include blowouts and oil or chemical 

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

due to a 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. 

Commercial Fishing (Chapter 4.1.12) 

The MMS has reexamined the analysis for commercial fishing presented in the Multisale EIS, based 

on the additional information available since the publication of the Multisale EIS. New fishery statistics 

analyzed do not change the conclusion in the Multisale EIS that impacts on the commercial fisheries from 

the proposed action would be minimal. 

Routine activities in the WPA such as seismic surveys and pipeline trenching will cause negligible 

impacts and will 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 either a WPA action are anticipated to be minimal. Commercial fishermen are anticipated 

to avoid the area of a well blowout or an oil spill. Any impact on catch or value of catch would be 

insignificant compared with natural variability. 

Recreational Fishing (Chapter 4.1.13) 

The MMS has reexamined the analysis for recreational fishing presented in the Multisale EIS, based 

on the additional information available since the publication of the Multisale EIS. New information was 

not significantly different from that provided in the Multisale EIS; therefore, no information was found 

that would alter the conclusions in the Multisale EIS that impacts on the recreational fisheries from 

accidental events associated with a WPA action would be minimal. 
2-24 Central and Western Gulf of Mexico Multisale Supplemental EIS

Routine activities in the WPA such as seismic surveys and pipeline trenching will cause negligible 

impacts and will not deleteriously affect recreational fishing activities. Indirect impacts to inshore 

habitats are negligible and indistinguishable from direct impacts of inshore activities on commercial 

recreational fisheries. Temporary localized impacts from oil spills are anticipated as a result of a WPA 

action. These impacts would include temporary inconvenience to recreational fishermen and possibly 

some loss of revenue to facilities supported by recreational fishermen such as boat launches and bait 

shops. 

Recreational Resources (Chapter 4.1.14) 

The MMS has reexamined the analysis for recreational resources presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS. No significant 

new information was found that would alter the impact conclusion for recreational resources presented in 

the Multisale EIS. 

Routine impacts from marine debris and nearshore operations, either individually or collectively, may 

adversely affect the affect the quality of some recreational experiences but are unlikely to reduce the 

number of recreational visits to Gulf coastal beaches. It is unlikely that a spill would be a major threat to 

recreational beaches because any impacts would be short-term and localized, and should have no longterm effect on tourism. 

Archaeological Resources (Chapter 4.1.15) 

The MMS has reexamined the analysis for prehistoric and historic archaeological resources presented 

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

EIS. No significant new information was found that would alter the impact conclusion for archaeological 

resources presented in the Multisale EIS. 

The greatest potential impact to an archaeological resource as a result of routine activities associated 

with a proposed action in the WPA would result from direct contact between an offshore activity 

(platform installation, drilling rig emplacement, and dredging or pipeline project) and a prehistoric or 

historic 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 

will 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 will occur and contact coastal prehistoric or historic 

archaeological sites from accidental events associated with a 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. 

Human Resources and Land Use 

Land Use and Coastal Infrastructure (Chapter 4.1.16.1) 

The MMS has reexamined the analysis for land use and coastal infrastructure presented in the 

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

To date, no new information has been found that necessitates a change to the coastal infrastructure 

scenario presented in the Multisale EIS. The MMS recently analyzed historical data and validated past 

scenario projections of new pipeline landfalls and new onshore waste disposal sites. Based on the lack of 

significant new information and MMS’s recent analysis, the coastal infrastructure projections have not 

changed for a proposed lease sale or for the OCS Program. 

A proposed action in the WPA would not require additional coastal infrastructure, with the exception 

of possibly one new gas processing facility and one new pipeline landfall, and would not alter the current 

land use of the analysis area. The existing oil and gas infrastructure is expected to be sufficient to handle 
Alternatives Including the Proposed Actions 2-25 

development associated with a 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 clean up of any oil or chemicals spilled. 

Demographics (Chapter 4.1.16.2) 

The MMS has reexamined the analysis for demographics presented in the Multisale EIS, based on the 

additional information available since the publication of the Multisale EIS. No significant new 

information was found that would alter the impact conclusion for demographics presented in the Multisale 

EIS. 

A WPA proposed action is projected to minimally affect the demography of the analysis area. 

Population impacts from a proposed action are projected to be minimal (<1% of total population) for any 

economic impact area (EIA) in the Gulf of Mexico region. The baseline population patterns and 

distributions are expected to remain unchanged as the result of a 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) projected to move into focal areas, 

such as Port Fourchon. Accidental events associated with a proposed action such as oil or chemical spills, 

blowouts, and vessel collisions would have likely have no effects on the demographic characteristics of 

the Gulf coastal communities. 

Economic Factors (Chapter 4.1.16.3) 

The MMS has reexamined the analysis for economic factors presented in the Multisale EIS, based on 

the additional information available since the publication of the Multisale EIS. New economic and 

demographic data (Woods & Poole Economics, Inc., 2007) analyzed does not change the conclusions in 

the Multisale EIS, which stated that there would be only minor economic changes in the Texas, 

Louisiana, Mississippi, Alabama, and Florida EIA’s should a proposed WPA lease sale occur. 

A WPA proposed action is expected to generate less than a 1 percent increase in employment in any 

of these subareas, even when the net employment impacts from accidental events are included. Most of 

the employment related to a proposed action is expected to occur in Texas and Louisiana. The demand 

will be met primarily with the existing population and labor force. 

Environmental Justice (Chapter 4.1.16.4) 

The MMS has reexamined the analysis for environmental justice presented in the Multisale EIS, 

based on the additional information available since the publication of the Multisale EIS. No significant 

new information was found that would alter the impact conclusion for environmental justice as presented 

in the Multisale EIS. 

Because the proposed WPA sale area lies 3 or more miles (4.8 or more kilometers) offshore, no 

activities that occur on the resulting leases (and that are regulated by MMS) will impact 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 actions is not expected to 

have disproportionately high or adverse environmental or health effects on minority or low-income 

people. The WPA proposed action would help to maintain ongoing levels of activity rather than expand 

them. 

2.3.1.3. Mitigating Measures 

The following four environmental and military mitigations, referred to as lease stipulations, were 

included for analysis in the Multisale EIS (Chapter 2.3.1.3 of the Multisale EIS). Any stipulations or 

mitigation requirements to be included in a lease sale will be described in detail in the FNOS for that 
2-26 Central and Western Gulf of Mexico Multisale Supplemental EIS

lease sale. Stipulations or mitigation requirements in addition to the those analyzed in this SEIS can also 

be developed and applied, and will also be described in detail in the FNOS. 

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 

muds and cuttings from impacting the biota of the banks. Although the deferral of blocks with 

topographic features has been analyzed as an alternative in EIS’s and EA’s for all recent CPA and WPA 

sales, this alternative has never been selected. 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. 

The Naval Mine Warfare Area Stipulation (formerly the Operations in the Naval Mine Warfare 

Area Stipulation) would apply to whole and partial blocks located in the Naval Mine Warfare Command 

Operational Area D (Figure 2-1) to eliminate potential impacts from multiple-use conflicts on these 

blocks. The U.S. Navy’s Mine Warfare Training Program, based in Corpus Christi, Texas, conducts 

training exercises in waters offshore Corpus Christi. The MMS and the Navy entered into a formal 

agreement in 1994 providing that these blocks could be offered for lease with a special stipulation. The 

MMS continues to consult periodically with the Navy, and they request that MMS continue to apply the 

lease stipulation restricting oil and gas operations on these blocks to ensure the safe use of these areas for 

mine warfare training. 

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 2-2 shows the military warning areas in the Gulf of Mexico. 

The Protected Species Stipulation has been applied to all blocks leased in the Gulf of Mexico since 

December 2001. This stipulation was developed in consultation with DOC, NOAA, NMFS, and FWS in 

accordance with Section 7 of the ESA and is designed to minimize or avoid potential adverse impacts to 

federally protected species. 

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

the Biologically Sensitive Topographic Features 

2.3.2.1. Description 

Alternative B differs from Alternative A by not offering the blocks that are possibly affected by the 

proposed Topographic Features Stipulation (Chapter 2.3.1.3.1 and Figure 2-1). All of the assumptions 

(including the three 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 4.1 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 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 assumption that the levels of activity for 

Alternative B are essentially the same as those projected for the proposed actions leads to the conclusion 
Alternatives Including the Proposed Actions 2-27 

that the impacts expected to result from Alternative B would be very similar to those described under the 

proposed actions (Chapter 4.1). Therefore, the regional impact levels for all resources, except for the 

Topographic Features, would be similar to those described under the proposed actions. 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—No Action 

2.3.3.1. Description 

Alternative C is the cancellation of one or more of the proposed WPA lease sales. The opportunity 

for development of the estimated 0.242-0.423 BBO and 1.644-2.647 Tcf of gas that could have resulted 

from a proposed lease sale would be precluded or postponed. Any potential environmental impacts 

resulting from the proposed lease sales would not occur or would be postponed. 

2.3.3.2. Summary of Impacts 

If Alternative C is selected, all impacts, positive and negative, associated with the proposed lease 

sales discussed in Chapter 4.1 would be eliminated. The incremental contribution of the proposed lease 

sales to cumulative effects would also be foregone, but effects from other activities, including other OCS 

lease sales, would remain. 

If a lease sale would be cancelled, 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 WPA 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. However, the cancellation of a 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 a proposed action (i.e., 

proposed lease sale), MMS developed exploration and development activity scenarios. These scenarios 

provide a framework for analyses of potential environmental and socioeconomic impacts of a proposed 

lease sale. Chapter 4.1.1 of the Multisale EIS describes the offshore impact-producing factors and 

scenario associated with the proposed lease sales that could potentially affect the biological, physical, and 

socioeconomic resources of the Gulf of Mexico, while Chapter 4.1.2 of the Multisale EIS describes 

coastal impact-producing factors and scenario. Chapter 4.1.3 of the Multisale EIS discusses non-OCS 

activities that could potentially affect the same biological, physical, and socioeconomic resources. This 

information is summarized below, and new information and information specific to the 181 South Area 

has been incorporated. 

The potential impacts of the offshore and coastal activities associated with a proposed lease sale are 

considered in the environmental analysis sections in Chapter 4 of this SEIS. 

3.1. IMPACT-PRODUCING FACTORS AND SCENARIO—ROUTINE OPERATIONS

3.1.1. Offshore Impact-Producing Factors and Scenario 

Offshore is defined here as the OCS portion of the Gulf of Mexico that begins 10 mi (16 km) offshore 

Florida; 3 nmi (6 km) offshore Louisiana, Mississippi, and Alabama; and 3 leagues (17 km) offshore 

Texas; and it extends seaward to the limits of the U.S. OCS (Figure 1-1). Chapter 4.1.1 of the Multisale 

EIS describes the infrastructure and activities (impact-producing factors) that would occur offshore as a 

result of the proposed actions (i.e., proposed lease sales) 

The projections used to develop the offshore proposed action scenarios are based on resource 

estimates as summarized in the 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, MMS 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. 

Each proposed lease sale is represented by a set of ranges for resource estimates, projected 

exploration and development activities, and impact-producing factors. Each of the proposed lease sales is 

expected to be within the scenario ranges; therefore, a proposed lease sale is representative of the 

individual proposed sales in each sale area. Notwithstanding these unpredictable factors, the scenarios 

used in this SEIS represent the best assumptions and estimates of a set of future conditions that are 

considered reasonably foreseeable and suitable for presale impact analyses. These scenarios do not 

represent an MMS 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 and Western Gulf of Mexico Multisale Supplemental EIS 

Analysis Period 

The MMS 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 Gulf of Mexico. 

Addition of the 181 South Area 

As mandated by GOMESA, proposed CPA lease Sale 208 in 2009, Sale 213 in 2010, Sale 216 in 

2011, and Sale 222 in 2012 would include the 181 South Area. The 181 South Area is located in 

extremely deep water. Deepwater oil and gas infrastructure is less dense than shallow water with much 

higher production to structure and well ratios. As of November 2007, 68 wells have been drilled and one 

platform has been installed in water depths >2,400 m (7,874 ft). Production has not yet occurred in water 

depths >2,400 m (7,874 ft). 

The MMS, Gulf of Mexico OCS Region, Resource and Evaluation Office’s Modeling and 

Forecasting Team has reevaluated the exploration and development activity scenario for a CPA proposed 

action due to the addition of the 181 South Area. Relative to CPA and WPA sales, a very small amount 

of exploration and development activity is forecasted to occur as a result of the addition of this area per 

proposed CPA lease sale. The forecasted level of activity considered the extreme water depth of the 181 

South Area, the amount of interest in these water depths in recent lease sales, and the lack of recent 

seismic data for the 181 South Area. 

Up to one additional production structure and 9-12 additional wells are projected for an individual 

CPA sale as a result of the addition of the 181 South Area. Like other deepwater developments, this 

production structure would likely be a centrally located host facility, and the 9-12 additional wells would 

be subsea wells located within 10 mi (16 km) of the host facility. 

Resource Estimates 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) 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. Due to the inherent 

uncertainties associated with an assessment of undiscovered resources, probabilistic 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 the MMS brochure entitled, 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 assumed 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 profusion of historical 

databases and information derived from oil and gas exploration and development activities are available 

to MMS 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 action based on an actual range of historic observations. 

Table 3-1 presents the projected oil and gas production for the proposed lease sales. Major impactproducing factors including the number of exploration and delineation wells, production platforms, and 

development wells projected to develop and produce the estimated resources for a CPA or WPA proposed 

action are given in Tables 3-2 and 3-3, respectively. The tables show the distribution of these factors by 

offshore subareas in the proposed lease sale areas. The proposed lease sale areas were divided into 

offshore subareas based upon ranges in water depth (Figure 3-1) that reflect the technological 

requirements and related physical and economic impacts. 
Impact-Producing Factors and Scenario 3-5 

For purposes of analysis, the life of the leases resulting from a proposed action is assumed to not 

exceed 40 years. Sale areawide exploratory drilling activity would take place over an 8-year period, 

beginning within one year after the lease sale. Development activity takes place over a 39-year period, 

beginning with the installation of the first production platform and ending with the drilling of the last 

development wells. Production of oil and gas begins by the third year after the lease sale and continues 

through the 40th year. Final abandonment and removal activities occur in the 40th year. 

Activity as the result of a lease sale is assumed to be staggered over time. A recently published MMS 

study, which estimated physical and economic performance measures to characterize lease sales and 

development in the Gulf of Mexico, was used to further refine the scenario presented in the Multisale EIS 

(Iledare and Kaiser, 2007). The average lag of exploration and production from leases issued from 1983 

to 1999 increased by water depth and decreased over time as shown in the Tables 3-4 and 3-5. Due to 

variation by water depth, exploration and production activity is staggered over time, taking on average 

1.9-4.5 years after a lease sale before exploration begins and 3.4-8.3 years before first production. 

Therefore, it is likely that production from the 181 South Area would likely begin eight or more years 

after a lease sale. 

3.1.1.1. Exploration and Delineation 

3.1.1.1.1. Seismic Surveying Operations 

Chapter 4.1.1.2.1 of the Multisale EIS describes geophysical seismic surveys that are performed to 

obtain information on surface and near-surface geology and on subsurface geologic formations. Highresolution (shallow hazard) surveys are conducted as authorized under the terms and conditions of the 

lease agreement, and are referred to as postlease surveys. Prelease surveys take into account seismic 

work performed off-lease (or on otherwise leased areas), focused most commonly (but not always) on 

deeper targets and collectively authorized under MMS’s G&G 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 bottom-founded structures. They are also 

used to identify environmental resources such as chemosynthetic community habitat and associated 

hydrate production. 

Typical prelease seismic surveying operations tow an array of airguns and a streamer (signal receiver 

cable) behind the vessel 5-10 m (16-33 ft) below the sea surface. The airgun array produces a burst of 

underwater sound by releasing compressed air into the water column that creates an acoustical energy 

pulse. These streamers (acoustic receiver cables) are 3-6 mi (5-10 km) or greater in length. Vessel speed 

is typically 4.5-6 knots (kn) (about 4-8 miles per hour (mph)) with gear deployed. 

The 3D surveys carried out by seismic vendors can consist of several hundred OCS blocks. Multiplesource and multiple-streamer technologies are often used for 3D seismic surveys. A typical 3D survey 

might employ a dual array of 18 guns per array. Each array might emit a 3,000-in3

 burst of compressed 

air at 2,000 pounds per square inch (psi), generating approximately 4,500 kilojoule (kJ) of acoustic energy 

for each burst. At 10 m (33 ft) from the source, the pressure experienced is approximately ambient 

pressure plus 1 atmosphere (atm). A series of 3D surveys collected over time, simulating the exact 

acquisition parameters, commonly referred to as a four-dimensional (4D) or time-lapse survey, is used 

mainly for reservoir management. It is used to monitor how a reservoir has been drained to optimize the 

amount of hydrocarbon that is produced. 

At present, limited geophysical seismic data exist for the 181 South Area, which is one reason MMS 

has chosen not to offer the 181 South Area until 2009. A few 2D surveys, which typically have a life of 

8-10 years, have been conducted in the 181 South Area. The MMS recently received an application to 

conduct a 3D survey in the Lloyd Ridge Area (northern half of the 181 South Area). If approved, the 

survey would take about 1 year for acquisition and 6 months for processing. One to two 3D surveys are 

projected in the 181 South Area. The availability of the 181 South Area for leasing may encourage 

surveys of other adjacent areas of the CPA and EPA. 

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 
3-6 Central and Western Gulf of Mexico Multisale Supplemental EIS 

geologic structure to determine if a resource exists. If a resource is discovered in quantities appearing to 

be economic, one or more follow-up delineation wells help define the amount of resource or the extent of 

the reservoir. 

In the Gulf of Mexico, exploration and delineation wells are typically drilled with mobile offshore 

drilling units (MODU’s); for example, jack-up rigs, semisubmersible rigs, or drillships. 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 table below indicates the depth ranges for 

exploration rigs used in this analysis for Gulf of Mexico MODU’s. 

MODU or Drilling Rig Type Water-Depth Range 

Jack-up ≤100 m 

Semisubmersible 100-3,000 m 

Drillship ≥600 m 

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. Wells drilled in and near the 181 South Area 

could take 100-120 days to drill. The actual time required for each well depends on a variety of factors, 

including the depth of the prospect’s potential target zone, the complexity of the well design, and the 

directional offset of the wellbore needed to reach a particular zone. 

The cost of an ultra-deepwater well (>6,000-ft or >1,829-m water depth) can be $30-$50 million or 

more, without certainty that objectives can be reached. Some recent ultra-deepwater exploration wells in 

the Gulf of Mexico have been reported to have cost upwards of $100 million. 

The MMS requires that operators conduct their offshore operations in a safe manner. Subpart D of 

the MMS’s operating regulations (30 CFR 250) provides guidance to operators on drilling activities. For 

example, operators are required by 30 CFR 250.400 to take necessary precautions to keep their wells 

under control at all times using the best available and safest drilling technology (NTL 99-G01; 

“Deepwater Emergency Well Control Operations”). Deepwater areas pose some unique concerns 

regarding well-control activities. In 1998, the International Association of Drilling Contractors (IADC) 

published deepwater, well-control guidelines (IADC, 1998) to assist operators in this requirement. These 

guidelines address well planning, well-control procedures, equipment, emergency response, and 

specialized training for drilling personnel. 

Drilling rig availability is still a limiting factor for activity in the Gulf. The 181 South Area would 

encounter the same rig availability issues as the rest of the Gulf. 

Tables 3-2 and 3-3 show the estimated range of exploration and delineation wells by water depth 

subarea for a CPA and WPA proposed action, respectively. 

3.1.1.2. Development and Production 

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 the number of anticipated tie backs from other fields can also influence an operator’s 

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 increasingly in deep water, 

subsea. Due to the extreme water depths, production systems in and near the 181 South Area would be 

floating or subsea. 
Impact-Producing Factors and Scenario 3-7 

The MMS 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. In water 

depths of 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 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. 

Tables 3-2 and 3-3 show the estimated range of development wells and production structures by 

water depth subarea for a CPA and WPA proposed action, respectively. The MMS estimates that 87 

percent of development wells would become producing wells. 

Deepwater Operations Plans 

Deepwater Operations Plans (DWOP’s) are required of all deepwater development projects in water 

depths ≥1,000 ft (305 m) and for all projects proposing subsea production technology. The DWOP is 

designed to address industry and MMS 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 MMS. The DWOP provides MMS with information specific to 

deepwater/subsea equipment issues to demonstrate that a deepwater project is being developed in an 

acceptable manner. The MMS will review deepwater development activities from a total system 

perspective, emphasizing the operational safety, environmental protection, and conservation of natural 

resources. The DWOP was established through the NTL process, which provides for a more timely and 

flexible approach to keep pace with the expanding deepwater operations and subsea technology. On 

August 30, 2005, the DWOP requirements were incorporated into MMS operating regulations via 

revisions to 30 CFR 250 Subpart B. 

A conceptual DWOP is required initially and is usually followed by a Development Operations 

Coordination Document (DOCD). 

Development Operations and Coordination Document 

The chief planning document that lays out an operator’s specific intentions for development is the 

DOCD. Requirements for lessees and operators submitting a DOCD are addressed in 30 CFR 250.241-

250.242, and information guidelines for DOCD’s are given in NTL’s 2006-G14 and 2006-G15. 

Bottom Area Disturbance 

Chapters 4.1.1.3.2.1 and 4.1.1.3.3.1 of the Multisale EIS discuss in detail bottom area disturbance 

from structures emplaced or anchored on the OCS to facilitate oil and gas exploration and production 

including drilling rigs or MODU’s (jack-ups, semisubmersibles, and drillships), pipelines, and fixed 

surface, floating, and subsea production systems. The emplacement or removal of these structures 

disturbs small areas of the sea bottom beneath or adjacent to the structure. If mooring lines of steel, 

chain, or synthetic polymer are anchored to the sea bottom, areas around the structure can also be directly 

affected by their emplacement. This disturbance includes physical compaction or crushing beneath the 

structure or mooring lines and the resuspension and settlement of sediment caused by the activities of 

emplacement. Movement of floating types of facilities will also cause the movement of the mooring lines 

in its array. Small areas of the sea bottom will be affected by this kind of movement. Impacts from 

bottom disturbance are of concern near sensitive areas such as topographic features, pinnacles, low-relief 

live-bottom features, chemosynthetic communities, high-density biological communities in water depths 

≥400 m (1,312 ft), and archaeological sites. 

Drilling rigs, MODU’s, and production structures would individually disturb 1-3 ha (2.5-7 ac) of sea 

bottom. In water depths >600 m (1,969 ft) including the 181 South Area, dynamically-positioned (DP) 

drillships could be used, reducing the area of bottom disturbance. 
3-8 Central and Western Gulf of Mexico Multisale Supplemental EIS 

3.1.1.2.2. Infrastructure Presence 

3.1.1.2.2.1. Offshore Production Systems 

Chapters 3.3.5.7.1 and 4.1.1.3.3 of the Multisale EIS discuss in detail the offshore production systems 

that would be used to support a proposed lease sale. Tables 3-2 and 3-3 show the estimated range of 

production structures by water depth subarea for a CPA and WPA proposed action, respectively. These 

estimates include up to one additional production structure as a result of the addition of the 181 South 

Area. Of the production systems discussed, only spars, semisubmersibles, and floating production, 

storage, and offloading systems (FPSO’s) would be used in or near the 181 South Area. 

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. In July 2004, Kerr-McGee began production from the world’s first cell spar at Red Hawk 

(Garden Banks Block 877) in 1,626 m (5,334 ft) of water. 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 

(Natural Gas.org, 2006; USDOI, MMS, 2006b and c; Oynes, 2006). 

Semisubmersibles 

Semisubmersible production structures (semisubmersibles) resemble their drilling rig counterparts 

and are the most common type of offshore drilling rig (NaturalGas.org, 2006a). Semisubmersibles are 

partially submerged with pontoons that provide buoyancy. Their hull contains pontoons below the 

waterline and vertical columns 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, 2006; USDOI, MMS, 2006b and c; 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 Gulf of Mexico 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 comprises various bottomfounded components, among them: well templates, well heads, “jumper” connections between well 

heads, control manifolds, in-field pipelines and their termination sleds, and umbilicals and their 

termination assemblies. A subsea production system can range from a single-well template connected to 

a nearby manifold or pipeline, and then to a riser system at a distant production facility; or a series of 

wells that are tied into the system. Subsea systems rely on a “host” facility for support and well control. 

Centralized or “host” production facilities in deep water or on the shelf may support several satellite 

subsea developments. A drilling rig must be brought on location to provide surface support to reenter a 

well for workovers and other types of well maintenance activities. In addition, should the production 

safety system fail and a blowout result, surface support must be brought on location to regain control of 

the well. 
Impact-Producing Factors and Scenario 3-9 

Floating Production, Storage, and Offloading Systems 

The MMS has prepared an EIS on the potential use of FPSO systems on the Gulf of Mexico OCS 

(USDOI, MMS, 2002). 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, MMS 

announced its decision to accept applications for FPSO’s after a rigorous environmental and safety 

review. 

On June 12, 2007, MMS received a DOCD from Petrobras Americas Inc. proposing to use an FPSO 

in the Walker Ridge Area to develop two different prospects, Cascade and Chinook. This is the first and 

only proposal, at this time, to use an FPSO in the Gulf of Mexico. 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 MMS performed a site-specific environmental assessment (EA) for the Cascade-Chinook Prospects, 

and it was completed in March 2008. 

The FPSO system is an especially good production system candidate for deployment in ultradeepwater situations where the nearest pipeline tiebacks could be hundreds of miles or kilometers away. 

Operators making recent large discoveries in remote areas, such as in the edge of the Sigsbee Escarpment 

in the CPA and the Perdido Fold belt in the WPA, may have no recourse other than to deploy an FPSO 

system to produce discoveries in these areas. Among the challenges facing an FPSO deployment in these 

areas is the fate of produced gas from the reservoirs. The MMS has funded studies to examine options to 

safely produce the associated gas reserves. Compressed gas, gas to liquids, liquefied natural gas (LNG), 

and other options were considered. A new and evolving technology for deepwater development involves 

the use of minimal floating structures. These buoy-like structures allow the placement of minimal 

equipment at the surface. They have the advantages of relatively low cost and surface access to the 

well(s). These structures are dependent on “host” facilities for control and for final processing of the 

produced hydrocarbons. 

3.1.1.2.2.2. Space-Use Conflicts 

Chapter 4.1.1.3.3.2 of the Multisale EIS discusses space-use conflicts that may occur during OCS 

operations, where areas are occupied by seismic vessels, structures, anchor cables and safety zones are 

unavailable to commercial fishermen. In addition, OCS operations may pose a space-use conflict with 

potential dredging activities for sand and gravel extraction and military activities (Chapter 3.3.3). 

The 181 South Area is located within two Eglin Water Test Areas (EWTA’s) (Figure 2-2). The 

proposed Military Areas Stipulation would reduce potential impacts, particularly in regards to safety, but 

does not reduce or eliminate the actual physical presence of oil and gas operations in areas where military 

operations are conducted. The reduction in potential impacts resulting from this stipulation makes 

multiple-use conflicts most unlikely. Without the stipulation, some potential conflict 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 Gulf of Mexico. 

Commercial fisheries conflicts with platforms in the 181 South Area would be limited to the longline 

fishery. 

Of the production systems discussed, only spars, semisubmersibles, and FPSO’s would be used in or 

near the 181 South Area. The U.S. Coast Guard (USCG) has not yet determined what size navigational 

safety zone will be required during offloading operations. Factoring in various configurations of 

navigational safety zones, 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). 

3.1.1.2.2.3. Aesthetic Interference 

Chapter 3.1.1.2.2.3 of the Multisale EIS discusses in detail aesthetic interference from oil spills and 

residue, tarballs, trash and debris, noise, pollution, increased vessel and air traffic, and the presence of 

drilling and production platforms visible from land. Oil spills, oil residue from tankers cleaning their 

holding tanks, and tarballs could affect beaches, wetlands, and coastal residences. Increased vessel and 

air traffic may result in additional noise or in oil and chemical pollution of water in ports and out at sea. 
3-10 Central and Western Gulf of Mexico Multisale Supplemental EIS 

The potential visibility of fixed structures in local Gulf of Mexico waters is worrisome for local chambers 

of commerce and tourist organizations. 

An MMS-funded study investigated the abundance and sources of tarballs on the recreational beaches 

of the CPA (Henry et al., 1993). It was determined that the presence of tarballs along the Louisiana 

coastline is primarily related to marine transportation activities and that their effect on recreational use is 

below the level of social and economic concern. 

The 181 South Area is located nearly 130 mi (209 km) from the nearest coast, far distant from 

recreational beaches, out of sight from land, and out of range for most recreational fishing. However, a 

small increase in vessel traffic is estimated to result from the inclusion of the 181 South Area (Chapter 

3.1.1.4.4). 

3.1.1.2.2.4. Workovers and Abandonments 

Chapter 4.1.1.3.4 of the Multisale EIS discusses workovers and abandonments in more detail. 

Completed and producing wells may require periodic reentry that is designed to maintain or restore a 

desired 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 

stratum) 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 7 days. On the basis of 

historical data, MMS 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 temporarily abandon a well (30 CFR 250.703). 

Lessees are required to remove all seafloor obstructions from their leases within 1 year of lease 

termination or relinquishment. Decommissioning and removal operations are described in Chapter 

3.1.1.6. 

Tables 3-2 and 3-3 show the number of workovers and other well activities projected as a result of a 

proposed action. The projected number of workovers is a function of producing wells, including one 

permanent abandonment operation per well. 

3.1.1.3. Major Sources of Oil Inputs in the Gulf of Mexico 

Petroleum hydrocarbons can enter the Gulf of Mexico from a wide variety of sources. The major 

sources of oil inputs in the Gulf of Mexico 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. Numerical 

estimates of the contribution of these sources to the Gulf of Mexico coastal and offshore waters are 

presented in Tables 4-11 and 4-12 of the Multisale EIS, respectively. The information presented in the 

Multisale EIS is based on Oil in the Sea III: Inputs, Fates, and Effects (NRC, 2003) and is summarized 

below. 

Although the Gulf of Mexico comprises one of the world’s most prolific offshore oil-producing 

provinces as well as having heavily traveled tanker routes, inputs of petroleum from onshore sources far 

outweigh the contribution from offshore activities. Man’s use of petroleum hydrocarbons is generally 

concentrated in major municipal and industrial areas situated along coasts or large rivers that empty into 

coastal waters. 

Natural Seepage 

Natural seeps provide the largest petroleum input to the offshore Gulf of Mexico, 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 Gulf of Mexico, 

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 Gulf of Mexico at about 980,000 bbl 

(140,000 tonnes) per year. As seepage is a natural occurrence, the rate of about 980,000 bbl (140,000 

tonnes) per year is expected to remain the same throughout the 40-year analysis period. 
Impact-Producing Factors and Scenario 3-11 

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. The estimated average annual volume 

of 596 MMbbl per year of OCS-produced water would contribute 19,250 bbl (2,750 tonnes) of petroleum 

hydrocarbons to the Gulf of Mexico waters, or 2 percent to the total petroleum input but 11 percent of the 

anthropogenic petroleum hydrocarbons. 

Land-based Discharges 

Land-based sources provide the largest petroleum input to the coastal waters of the Gulf of Mexico. 

Land-based 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 Gulf of Mexico 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 of the Multisale EIS, which discusses offshore and coastal spills 

and spills related to and not related to OCS activity, is summarized below. Chapter 3.2.1 of this SEIS 

discusses potential spills associated with a proposed action, specifically. 

Naturally, spills will vary according to activities conducted in the area. Spills from pipelines are the 

largest spill source of oil to the coastal waters of the western Gulf of Mexico. Spills from tankers are the 

largest spill source to coastal waters of the eastern Gulf of Mexico. At the national level, tankers and tank 

barges were responsible for 82 percent of the total spillage. The type of oil spilled nationally was as 

follows: 36 percent crude oil; 36 percent heavy distillate (No. 6 fuel oil, bunker C); 25 percent light 

distillate (diesel, kerosene); and 3 percent gasoline. 

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 the MMS 

projects will occur within coastal and offshore waters of the Gulf of Mexico 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. Table 4-13 of the 

Multisale EIS shows the estimated number of OCS spills yearly rather than for the 40-year program. 

Figures 4-8, 4-9, and 4-10 of the Multisale EIS show that there is a great deal of uncertainty as to the 

number of future OCS spills that will occur. If the low resource estimate is realized, about 39 possible 

spills ≥1,000 bbl could occur. For the high resource estimate, about 49 possible spills ≥1,000 bbl could 

occur. 

Spills as the Result of Hurricanes 

Chapter 4.1.3.4.4.2 of the Multisale EIS discusses the cause and volume of spills that resulted from 

the 2004-2005 hurricanes. Since the publication of the Multisale EIS, MMS has revised information and 

quantities of oil spillage resulting from damages caused by Hurricanes Katrina and Rita in 2005 (USDOI, 

MMS, 2007d). The following is a summary of the revisions. 

As of July 2007, MMS has identified 154 spills of petroleum products of >1 bbl, totaling 17,077 bbl 

that were lost from platforms, rigs, and pipelines on the Federal OCS. This is up from MMS’s January 

2007 report that had identified 125 spills, totaling 16,302 bbl (USDOI, MMS, 2007e). 

The July 2007 report also discussed spills of <1 bbl. Between October 2005 and June 2007, there 

were approximately 600 petroleum spills of <1 bbl on the Federal OCS related to the 2005 hurricanes 

reported to the National Response Center (NRC). These NRC reports totaled to <50 bbl and averaged 

approximately 3 gallons each in size. These spills of <1 bbl dissipate quickly due to evaporation, 

dispersion by the winds and currents, and dilution by the ocean waters. Three gallons of crude oil can 
3-12 Central and Western Gulf of Mexico Multisale Supplemental EIS 

briefly create a sheen of an acre (43,560 ft2 or 4,047 m2) or more in size on the ocean surface. These 

small releases generally do not cause identifiable environmental impacts out in the open ocean. 

Unchanged from the earlier report, there were no accounts of environmental consequences resulting 

from spills from facilities: 

• 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 Hurricanes Katrina or 

Rita. 

The final estimation of the total spillage associated with Hurricanes Katrina and Rita will not be 

complete until all operators have completed recovery efforts associated with the repair and/or have 

completed decommissioning of all the damaged structures. These activities are continuing in 2008. 

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, respectively. One OCS-related offshore spill of ≥1,000 bbl 

per year due to a pipeline release is anticipated. Besides spills occurring from facilities and during 

pipeline transport, as was the only case for a proposed action, offshore spills could occur due to OCS 

future operations from an FPSO 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 OCSproduced crude oil. The scenario with the highest risk of spill occurrence is the high-case resource 

estimate for the OCS Program in the CPA, which assumes some shuttle-tanker transport of OCSproduced oil. Under that scenario, there is a 63 percent chance that a spill ≥1,000 bbl and a 29 percent 

chance that a spill ≥10,000 bbl would occur from an OCS-related shuttle tanker during the 40-year 

analysis period. Offshore spill sizes were estimated based on historical records for a representative future 

year (Anderson and LaBelle, 2000). 

Offshore OCS Program spills <1,000 bbl were estimated based on historical records collected from 

1985 to 2001 and about 450-500 spills <1,000 bbl occurred from OCS offshore sources yearly. Less 

documentation is available for spills <1,000 bbl because they are more routine, they do not persist on the 

water as long, and they are likely to pose less of an environmental threat than larger spills. Additionally, 

many of the reported spills are of an unknown origin. 

Non-OCS-related offshore spills ≥1,000 will occur from the extensive maritime barging and tankering 

operations that occur in offshore waters of the Gulf of Mexico. The analysis of spills from tankers and 

barges ≥1,000 bbl is based on data obtained from the USCG and analyzed by MMS. Less than one spill 

≥1,000 bbl is projected to occur in the offshore Gulf of Mexico 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 MMS’s projections of the number of spills that will occur in 

the coastal waters of the Gulf of Mexico (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 and non-OCS-related coastal spills are addressed in Chapters 

4.1.3.4.4.6 and 4.1.3.4.4.7 of the Multisale EIS, respectively. An OCS-related spill in coastal waters of 

≥1,000 bbl and related to the proposed activity will occur less than once per year. Such a spill would only 

occur about once every 6 years. An OCS spill ≥1,000 bbl would likely be from a pipeline accident for 

OCS coastal spills ≥1,000 bbl, and a spill size of 4,200 bbl is assumed. Smaller spills occur more 

regularly, and roughly 40-50 OCS-related spills in coastal waters of <1,000 bbl related to the future OCS 

Program proposed activity on the OCS are estimated to occur per year. It is assumed that the spill risk 

would be widely distributed in the coastal zone, but primarily within the Houston/Galveston area of Texas 
Impact-Producing Factors and Scenario 3-13 

and the deltaic area of Louisiana. Based on an MMS analysis of USCG data on all U.S. coastal spills by 

volume, 42 percent of the spills will occur in State offshore waters, 1.5 percent will occur in Federal 

offshore waters, and 57 percent will occur in inland waters. It is assumed all coastal spills will contact 

land and proximate resources. For OCS-related coastal spills <1,000 bbl, a spill size of 5 bbl is assumed. 

Non-OCS-related coastal spills 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 from 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 due 

to the infrequent occurrence of a spill of this size in coastal waters. Non-OCS-related coastal spills 

<1,000 bbl occurred annually at a rate of 400-600 per year in the 1996-2001 USCG data. Many of the 

reported spills are from an unknown source. Based on an MMS analysis of U.S. spill data maintained by 

the USCG (USDOT, Coast Guard, 2007), 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 

The following sections discuss the five likely methods to be used to transport production, supplies, 

and personnel as a result of a CPA or WPA proposed action. 

3.1.1.4.1. Pipelines 

A mature pipeline network exists in the Gulf of Mexico to transport oil and gas production from the 

OCS to shore. The OCS-related pipelines nearshore and onshore may merge with pipelines carrying 

materials produced in State territories 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 offshore 

Gulf of Mexico is transported to shore by pipeline. A small amount (<1%) of oil production is barged in 

shallow water (<60 m or <200 ft). Chapter 4.1.1.8.1 of the Multisale EIS describes in detail a description 

of the existing pipeline network in the Gulf of Mexico, installation trends, installation methods, pipeline 

burial, and issues related to deep water. The following is a summary of that information. 

Alternative transportation methods of natural gas discussed in Chapter 4.1.1.8.6 of the Multisale EIS 

involve transporting natural gas as LNG or compressed natural gas (CNG). However, it is reasonably 

foreseeable that gas production will continue to be transported by pipeline. 

Pipeline Landfalls 

It is expected that pipelines from most of the new offshore production facilities will connect to the 

existing pipeline infrastructure, which will result in few new pipeline landfalls. Production from a CPA 

and WPA proposed action will contribute to existing and future pipelines and pipeline landfalls. 

Projections of new landfalls are discussed in Chapter 3.1.2.3. 

Pipeline Burial 

According to MMS regulations (30 CFR 250.1003(a)(1)), pipelines with diameters ≥85/8 inches (22 

cm) that are installed in water depths <60 m (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 MMS 

determines that the pipeline may constitute a hazard to other uses of the OCS; in the Gulf of Mexico, 

MMS has determined that all pipelines installed in water depths <60 m (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. 

Where pipeline burial is necessary, a jetting sled will be used. Jetting disperses sediments over the 

otherwise undisturbed water bottom that flanks the jetted trench. The area covered by settled sediment 

and the thickness of the settled sediment depends upon variations in bottom topography, sediment 
3-14 Central and Western Gulf of Mexico Multisale Supplemental EIS 

density, and currents. Sediment displacement due to pipeline burial is further explained in Chapter 

4.1.1.3.2.2 of the Multisale EIS. 

Deepwater 

Newer installation methods have allowed the pipeline infrastructure to extend farther into deep water. 

At present, the deepest pipeline in the Gulf is in 2,700 m (8,858 ft) water depth. More than 500 pipelines 

reach water depths of 400 m (1,312 ft) or more, and over 400 of those reach water depths of 800 m (2,625 

ft) or more. 

New pipelines installed in and near the 181 South Area would encounter the same technical 

challenges as other deepwater areas. These technical challenges are described in more detail in the 

Multisale EIS and Deepwater Gulf of Mexico 2006: America’s Expanding Frontier (USDOI, MMS, 

2006b). 

Figure 3-3 shows the location of active pipelines near the 181 South Area. The nearest existing 

pipeline is located a little over 40 mi (64 km) from the 181 South Area. 

Production from the 181 South Area would likely begin 8 or more years after a lease sale. By that 

time it is anticipated that existing pipelines will have adequate capacity to transport gas production from 

the 181 South Area. If needed, capacity could be increased by adding compressors. 

Oil discovered in the 181 South Area will likely be heavier oil than most other areas of the CPA and 

WPA. It is not likely that oil production from this area would be transported by pipeline due to associated 

costs. Companies would most likely seek other alternatives (i.e., FPSO’s). If a pipeline is constructed, 

oil production would likely be transported to refineries in Texas, where there is existing pipeline capacity 

and heavier oil is currently being processed. It is assumed oil pipelines located near the 181 South Area 

would not be compatible with the heavier oil anticipated from the 181 South Area. 

Review and Approval Process 

Applications for pipeline decommissioning must also be submitted for MMS review and approval. 

Decommissioning applications are evaluated to ensure they will render the pipeline inert, 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. 

The MMS’s review of pipeline applications includes the evaluation of protective safety devices such 

as pressure sensors and automatic valves, and the physical arrangement of those devices proposed to be 

installed by the applicant. The purpose of the safety devices is to protect the pipeline from possible 

overpressure conditions and for detecting and initiating a response to abnormally low-pressure conditions. 

Once a pipeline is installed, operators conduct monthly overflights to inspect pipeline routes for leakage. 

Chapter 1.5, Postlease Activities (Pollution Prevention), of the Multisale EIS discusses this topic in depth. 

Scenario 

There are 130-1,700 km (81-1,056 mi) of new pipelines projected as a result of a CPA proposed 

action (Table 3-2) and 130-760 km (8-472 mi) as a result of a WPA proposed action (Table 3-3). For 

CPA and WPA proposed actions, about half of the new pipeline length would be in water depths <60 m 

(197 ft) requiring burial. There are 0-1 new landfalls for a CPA proposed action and 0-1 for a WPA 

proposed action. 

The length of new pipelines was estimated using the amount of production, the number of structures 

projected as a result of the proposed actions, 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 and which 

existing or proposed pipelines would be utilized. Many factors would affect the actual transport system, 

including company affiliations, amount of production, product type, and system capacity. 

3.1.1.4.2. Barges 

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 or <200 ft) of the Gulf of 
Impact-Producing Factors and Scenario 3-15 

Mexico. It is assumed that barging will continue to account for <1 percent of the oil transported for the 

entire OCS Program and the CPA and WPA proposed actions. Due to the distance offshore, no barging 

of production from the 181 South Area is anticipated. Detail discussions of barges and barging can be 

found in Chapters 4.1.1.8.2 and 3.3.5.8.6.2 of the Multisale EIS, respectively. 

3.1.1.4.3. Oil Tankers 

Chapter 4.1.1.8.3 of the Multisale EIS discusses in detail the use of FPSO’s and shuttle tankers for the 

transportation of OCS oil production. Shuttle tanker transport of Gulf of Mexico OCS-produced oil has 

not occurred to date. Tankering is projected for some future OCS operations located in deepwater beyond 

the existing pipeline network. The FPSO’s store crude oil in tanks located in the hull of the vessel and 

periodically offload the crude to shuttle tankers or ocean-going 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. 

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 (LOOP). The shuttle 

tanker design and systems would be in compliance with USCG regulations. Under the Jones Act and 

OPA 90 requirements, shuttle tankers would be required to be double hulled. Shuttle tankers are likely to 

be 500,000-550,000 bbl in cargo capacity. 

Safety features, such as marine break-away offloading hoses and emergency shut-off valves, would 

be incorporated in order to 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 release of fugitive emissions from cargo tanks during offloading operations. 

Oil discovered in the 181 South Area will likely be heavier oil than most other areas of the CPA and 

WPA. It is not likely that oil production from this area would be transported by pipeline due to the 

associated costs. Companies would most likely seek other alternatives (i.e., FPSO’s). 

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. Considering an FPSO operating at a peak 

production rate of 150,000 bbl/day, supported by shuttle tankers of 500,000-bbl capacity, offloading 

would occur once every 3.3 days. This would equate to a 54.75-MMbbl production with 110 offloading 

events and shuttle tanker transits to Gulf coastal or offshore ports annually per FPSO. 

3.1.1.4.4. Service Vessels 

Service vessels are one of the primary modes of transporting personnel between service bases and 

offshore platforms, drilling rigs, derrick barges, and pipeline construction barges. In addition to offshore 

personnel, service vessels carry cargo (i.e., freshwater, fuel, cement, barite, liquid drilling fluids, tubulars, 

equipment, and food) offshore. A trip is considered the transportation from a service base to an offshore 

site and back, in other words a round trip. Based on MMS 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 or 

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 or 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 service base.

Service-vessel trips projected for a CPA proposed action are 119,000-241,000 trips (Table 3-2). This 

equates to an average annual rate of 2,975-6,025 trips. This includes an additional 2,000-7,000 servicevessel trips or 50-175 trips annually that are projected from the addition of the 181 South Area. A WPA 

proposed action is estimated to generate 94,000-155,000 service-vessel trips or 2,350-3,875 trips annually 

(Table 3-3). 

Table 3-36 of the Multisale EIS shows over 1 million trips occurred on OCS-related waterways in 

2004. The number of service-vessel trips projected annually for a CPA or WPA proposed action would 

represent <1 percent of the total annual traffic on these OCS-related waterways. 
3-16 Central and Western Gulf of Mexico Multisale Supplemental EIS 

3.1.1.4.5. Helicopters 

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. Chapters 3.3.5.7.2.4 and 4.1.1.8.5 of the Multisale EIS discuss in 

detail the use of helicopter to support offshore oil and gas activities. 

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 noisesensitive 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 Marine Mammal Protection Act 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 (2008), from 1996 to 2006, helicopter 

operations (take offs and landings) in support of Gulfwide OCS operations have averaged, annually, about 

1.4 million operations, 3.0 million passengers, and 400,000 flight hours. There has been a decline in 

helicopter operations from 1,668,401 in 1996 to 1,246,172 in 2006 (Helicopter Safety Advisory 

Conference, 2008). 

The proposed action and OCS Program scenarios below use the current level of activity as a basis for 

projecting future helicopter operations. A CPA proposed action s projected to generate 1,004,000-

2,241,000 helicopter operations or 25,100-55,025 operations annually (Table 3-2). This includes an 

additional 4,000-41,000 helicopter operations or 100-1,025 operations annually that are projected from 

the addition of the 181 South Area. Helicopter operations projected for a WPA proposed action are 

400,000-900,000 operations (Table 3-3). This equates to an average annual rate of 10,000-22,500 

operations. 

3.1.1.5. Safety Issues 

3.1.1.5.1. Hydrogen Sulfide and Sulfurous Petroleum 

Chapter 4.1.1.9 of the Multisale EIS of describes in detail sulfur that may be present in oil as 

elemental sulfur, within hydrogen sulfide (H2S) gas, 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; outgassing from spilled oil and exposure to sulfur oxides produced by 

flaring; equipment and pipeline corrosion; and synergistic amplification of oil-spill impacts from 

outgassing. 

Sour oil and gas occur sporadically throughout the Gulf of Mexico OCS, primarily off the Louisiana, 

Mississippi, and Alabama coasts. Occurrences of H2S offshore Texas are in Miocene rocks and occur 

principally within a geographically narrow band. The next highest concentrations of H2S have been in the 

range of 20,000-55,000 parts per million (ppm) in some natural gas wells offshore Mississippi/Alabama. 

There is some evidence that petroleum from deepwater areas may be sulfurous, but there is no evidence 

that it is contains appreciable amounts of H2S. Data from petroleum wells drilled near the 181 South 

Area have confirmed this assumption. Deep gas reservoirs on the Gulf of Mexico continental shelf are 

likely to have high corrosive content, including H2S. 

The MMS reviews all proposed actions in the Gulf of Mexico OCS for the possible presence of H2S. 

Activities found to be associated with a presence of H2S are subjected to further review and requirements. 

Federal regulations at 30 CFR 250 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 
Impact-Producing Factors and Scenario 3-17 

required to file an H2S contingency plan. This plan delimits procedures to ensure the safety of the 

workers on the production facility. In addition, all operators are required to adhere to the National 

Association of Corrosion Engineers’ (NACE) Standard Material Requirement MR.01-75-96 for Sulfide 

Stress Cracking Resistant Metallic Materials for Oilfield Equipment (NACE, 1990). These engineering 

standards serve to enhance the integrity of the infrastructure used to produce the sour oil and gas, and 

further serve to ensure safe operations. The MMS has issued a final rule governing requirements for 

preventing hydrogen sulfide releases, detecting and monitoring hydrogen sulfide and sulfur dioxide, 

protecting personnel, providing warning systems, and establishing requirements for hydrogen sulfide 

flaring. The rule went into effect on March 28, 1997. An associated NTL (98-16) titled “Hydrogen 

Sulfide (H2S) Requirements” was issued on August 10, 1998, to provide clarification, guidance, and 

information on the revised requirements. The NTL provides guidance on sensor location, sensor 

calibration, respirator breathing time, measures for protection against sulfur dioxide, requirements for 

classifying an area for the presence of H2S, requirements for flaring and venting of gas containing H2S, 

and other issues pertaining to H2S-related operations. 

3.1.1.5.2. Shallow Waterflows 

Since 1987, operators have reported to MMS shallow waterflow events, which 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 around the annulus will 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 will form frozen gas hydrates 

on flat surfaces of seafloor drilling equipment. 

3.1.1.5.3. Damage to Offshore Infrastructure as the Result of Hurricanes 

During the past few years, the Gulf Coast States and Gulf of Mexico oil and gas activities have been 

impacted by several major hurricanes. Chapter 3.3.5.7.3 of the Multisale EIS summarized the latest 

reports by MMS on the damage to the OCS-related platforms, rigs, and pipelines caused by Hurricanes 

Ivan, Katrina, and Rita. Chapter 3.1.1.3 of this SEIS provides an update on the cause and volume spills 

that resulted from recent hurricanes. 

In preparation for the 2007 hurricane season, MMS announced operational and administrative 

improvements that have been implemented to prepare oil and gas infrastructure in the Gulf of Mexico for 

the possibility of hurricanes during the 2007 season (USDOI, MMS, 2007f). Both MMS and industry had 

to reassess what possible weather conditions could occur with a major hurricane moving through the Gulf 

of Mexico. The reassessment was done through American Petroleum Institute (API) committees, in 

which MMS was an active participant. The committees revised and updated the best practices and 

standards using the new information that had been collected following the 2005 hurricanes. 

Notices to Lessees 

In addition to several NTL’s that were specifically issued for the 2006 and 2007 hurricane seasons, 

MMS issued NTL 2007-G27 (“Assessment of Existing OCS Platforms and Related Structures for 

Hurricane Conditions”) and NTL 2007-G26 (“Design of New OCS Platforms and Related Structures for 

Hurricane Conditions”) to ensure that the assessment of existing and the design of new OCS platforms 

and related structures consider the specific environmental conditions, including hurricane metocean 

conditions, at the platform location as required by 30 CFR 250.900(a). 

Evacuation Plans 

The development of evacuation plans for OCS facilities is the responsibility of the operator. The 

OCS operators develop detailed evacuation plans that encompass evacuation procedures that go beyond 

just getting the personnel to shore; they also take measures to ensure that personnel associated with 

onshore infrastructure are out of harm’s way prior to storm landfall. 
3-18 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Hurricane-Induced Mudslides 

Near-bottom orbital velocities of waves generated by hurricanes can induce substantial changes in 

sediment engineering properties that result in increased magnitude of sediment motion and shear strain. 

These effects, along with sediment accumulation due to river runoff, can cause bottom instabilities 

(Teague et al., 2006). These bottom instabilities could result in mudslides. 

The area in the Gulf of Mexico most susceptible to underwater mudslides is located in the CPA, 

within about 25 mi (40 km) of the Mississippi Delta. In most parts of the Mississippi Delta region, 

mudslides are generally caused by very large storms and are therefore infrequent events. Only three 

major storms (Hurricanes Camille, Ivan, and Katrina) caused significant and widespread mudslide activity 

in the past 40 years. The majority of pipelines damaged by mudslides occurred during Hurricane Ivan in 

2004. Two platforms have been destroyed by mudslides in the Gulf of Mexico, one during Hurricane 

Camille in 1962 and the other during Hurricane Ivan in 2004. 

Two recent, MMS-funded studies examined wave-induced submarine mudslides in the Mississippi 

Delta region caused by these major hurricanes, and included the development of a model that can be used 

to analyze and predict these mudslides (Nodine et al., 2006 and 2007). Findings of these studies are 

presented below. 

Wave period was found to be an important factor in mudslide vulnerability. Hurricane Ivan produced 

relatively long wave periods compared with previous large hurricanes, which may have aggravated the 

impact and caused mudslides in deeper water than a typical hurricane would have. Slope angle was not 

found to be a significant factor in mudslide vulnerability except in the deeper parts of the mudslide prone 

area (>300 ft or >91 m). 

The study found that the simple, limit equilibrium model developed works well to predict the factor 

of safety against mudslide initiation for a given location, and is well-suited to quantify the effects of wave 

height and period, water depth, slope angle, and profile of undrained shear strength versus depth for 

potential mudslides. However, site-specific analyses of mudslide vulnerability are challenging due to 

substantial variations in soil shear strength over short distances. 

Mudslides are localized features, on the order of several thousand feet or meters in lateral extent and 

are about 50-150 ft (15-46 m) deep. During Hurricane Ivan, waves and strong near-bottom currents 

impacted bottom sediments on the outer shelf at water depths as deep as 90 m (295 ft) (Teague et al., 

2007). The areal extent and depth of mudslides are related to the lengths and widths of the storm waves 

that cause them. Mudslides are not likely to lead to large-scale, regional mudflows due to the very flat 

slopes in the mudslide prone area and the large amount of local variation in soil shear strength. 

The return periods for mudslides impacting facilities range from less than 10 years to greater than 

1,000 years and depend strongly on location. The risk for mudslides occurring and impacting facilities 

increases as the water depth decreases, the slope of the bottom increases, and the amount of infrastructure 

in a particular area increases. 

Future pipeline damage and platform losses could occur due to mudslides during major hurricanes. 

The MMS and industry have made efforts to mitigate risks to offshore infrastructure. 

Larger diameter pipelines and those perpendicular to the direction of mudslide direction would be 

more susceptible to damage (Zone, 2006). The MMS considers these factors when reviewing pipeline 

plans in the mudslide area. The MMS’s general policy is to recommend alternative routes that would 

decrease the surface area that would be encountered by a mudslide. In addition, the mudslide area is 

located in shallow water (<60 m or <200 ft), and under MMS regulations (30 CFR 250.1003(a)(1)), 

pipelines with diameters ≥85

/8 inches (22 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 the mudline. 

All OCS platforms are subject to regulations contained in 30 CFR 250.900-921, Subpart I, Platforms 

and Structures. Under 30 CFR 250.906(c), depending on the design and location of a structure, MMS 

may require an operator to perform a subsurface survey and testing, including investigating the 

stratigraphic and engineering properties of the soil that may affect the foundations or anchoring systems 

for the facility. The MMS regulations at 30 CFR 250.901(a)(4) require that all OCS platforms be 

designed, fabricated, and installed in accordance with the provisions of the API Recommended Practice 

for Planning, Designing, and Constructing Fixed Offshore Platforms – Working Stress Design, TwentyFirst Edition, December 2000 (API RP 2A-WSD; API, 2000). To reinforce structures in the mudslide 
Impact-Producing Factors and Scenario 3-19 

area, wells are routinely drilled and completed through the legs of platforms, and the annular space 

around the conductors is filled with grout. 

Federal regulations at 30 CFR 250.1700, Subpart Q, Decommissioning Activities, require that an 

offshore oil and gas lease be cleared of all structures within 1 year after production on the lease ceases, or 

when the facility is no longer useful. The MMS also has the authority to order operators to permanently 

plug a well if that well poses a hazard to the environment. At the end of 2003, there were 1,227 idle (nonproducing) structures in the Gulf of Mexico (Kaiser and Pulsipher, 2007). These idle structures pose a 

potential hazard to other structures in the event of a hurricane or mudslide. In recent years, MMS has 

begun to encourage operators to remove structures on producing leases that are no longer “economically 

viable.” On August 1, 2007, MMS issued Safety Alert No. 253, Plug and Abandonment of Nonproducing Wells and Facilities, which alerts operators to this potential problem. 

3.1.1.5.4. New and Unusual Technologies 

Operators must identify new or unusual technology in exploration and development plans. These 

technologies are reviewed by MMS for alternative compliance or departures that may trigger additional 

environmental review. Chapter 4.1.1.10 of the Multisale EIS discusses in detail the environmental and 

engineering safety review processes for new and unusual technology. No additional new or unusual 

technology has been identified for the 181 South Area. 

3.1.1.6. Decommissioning and Removal Operations 

In compliance with Section 22 of MMS’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), lessees are required 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. A detailed discussion of 

decommissioning and removal operations can be found in Chapter 4.1.1.11 of the Multisale EIS. The 

following is a summary of that information. 

Programmatic Environmental Assessment 

The MMS prepared a programmatic environmental assessment (PEA), Structure-Removal Operations 

on the GOM Outer Continental Shelf (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 

Sale 181/189 area in the EPA of the Gulf of Mexico. The activities analyzed in the PEA include vessel 

and equipment mobilization, structure preparation, nonexplosive- and explosive-severance activities, 

post-severance lifting and salvage, and site-clearance verification. The impact-producing factors of 

structure removals considered in the PEA include seafloor disturbances, air emissions and 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, and archaeological resources; or other OCS pipeline, navigation, and 

military uses. On the basis of this PEA, MMS determined that an EIS was not required and prepared a 

Finding of No Significant Impact (FONSI). 

On February 28, 2005, MMS submitted the new structure-removal PEA and a petition for new 

Incidental-Take Regulations under the MMPA to NMFS. After review of the petition and PEA, NMFS 

published a Notice of Receipt of MMS’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 Rule for the Incidental Take of marine mammals under the MMPA in the Federal Register. 

The subsequent public comment period ended May 22, 2006, and MMS expects the Final Rule to be 

published in the Federal Register in mid-2008. In addition, NMFS is also conducting a Section 7 ESA 

Consultation on their MMPA rulemaking efforts. The agency expects to issue a new Biological Opinion 

(BO) and Incidental Take Statement to supersede the current “generic” and “de-minimus” BO’s around 

the same timeframe as the publication of the Final MMPA rule. 
3-20 Central and Western Gulf of Mexico Multisale Supplemental EIS 

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. 

Tables 3-2 and 3-3 show platform removals by water-depth subarea as a result of the proposed 

actions. Of the 24-35 production structures estimated to be removed as a result of a CPA proposed action, 

14-16 production structures (installed landward of the 800-m or 2,625-m isobath) are likely to be removed 

using explosives. Of the 20-31 production structures estimated to be removed as a result of a WPA 

proposed action, 11-17 production structures (installed landward of the 800-m or 2,625-m isobath) are 

likely to be removed using explosives. It is anticipated that multiple appurtenances will not be removed 

from the seafloor if placed in waters exceeding 800 m (2,625 ft). An estimate of the well stubs and other 

various subsea structures that may be removed using explosives is not possible at this time. 

No explosive removals are projected in water depths >800 m (2,625 ft), including the 181 South 

Area, because OCS regulations would offer the lessees in those water depths the option to avoid the 

jetting 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 MMS—data necessary for subsequent 

reporting to the U.S. Navy. In some cases, industry has indicated that it could 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. 

Removal of Bottom Debris 

After bottom-founded objects are severed and the structures are removed, operators are required to 

verify that the site is clear of any obstructions that may conflict with other uses of the OCS. The MMS 

NTL 98-26, “Minimum Interim Requirements for Site Clearance (and Verification) of Abandoned Oil and 

Gas Structures in the GOM,” provides the requirements for site clearance. The lessee must develop, and 

submit to the MMS for approval, a procedural plan for the site clearance verification procedures. For 

platform and caisson locations in water depths of less than 91 m (300 ft), the sites must be trawled over 

100 percent of the designated area in two directions (i.e., N-S and E-W). Individual well-site clearances 

may use high-frequency (500 kHz) sonar searches for verification. Site-clearance verification must take 

place within 60 days after structure removal operations have been conducted. 

Chapter 4.1.1.3.3.4 of the Multisale EIS discusses 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 tossed 

overboard from fixed or floating facilities. The maximum quantity of bottom debris per operation is 

estimated to be several tons. The MMS requires site clearance over the assumed areal extent over which 

debris will fall. It is assumed that most of the future lost debris will be removed from the seafloor during 

the structure decommissioning, site clearance, and verification process. 

Chapter 4.1.1.11 of the Multisale EIS describes the requirements and guidelines for removing bottom 

debris and gear after structure decommissioning and removal operations. There are also requirements for 

verification that operational debris has been removed from the areas around the platform removal site 

(e.g., by trawling the area to verify that the site has, in fact, been cleared of debris). The Fishermen’s 

Contingency Fund was established to provide recourse for the recovery of commercial fishing equipment 

losses due to the entanglement on OCS oil and gas structures and debris. 
Impact-Producing Factors and Scenario 3-21 

3.1.2. Coastal Impact-Producing Factors and Scenario 

Over the years, a network of onshore support facilities, ports, roads, pipelines, and processing 

facilities have arisen to support offshore production. The primary coastal infrastructure and associated 

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

Mexico are 

• service bases; 

• helicopter hubs; 

• construction facilities (i.e., platform fabrication yards, shipyards, and pipecoating 

facilities and yards); 

• processing facilities (i.e., refineries and gas processing plants); 

• terminals (i.e., pipeline shore facilities, barge terminals, and tanker port areas); 

• disposal and storage facilities for offshore operations (i.e., nonhazardous oil-field 

waste sites and landfills); and

• transportation (i.e., coastal pipelines, coastal barging, and navigation channels). 

Chapter 3.3.5.8 of the Multisale EIS describes the existing OCS-related coastal infrastructure and 

activities. Chapter 4.1.2.1 of the Multisale EIS describes the potential need for the construction of new 

facilities and the use of existing ones, including facility expansions, that could result from a proposed 

lease sale and the OCS Program. Up to one new pipeline landfall and up to one new gas processing plant 

were projected as a result of an individual proposed lease sale. The MMS projected no other new coastal 

infrastructure as a result of an individual proposed lease sale. A CPA or WPA proposed action may 

contribute to the use of existing and projected facilities. Projected new coastal infrastructure as a result of 

the OCS Program is shown by State in Table 4-9 of the Multisale EIS. 

Much of the information on coastal infrastructure and activities presented in the Multisale EIS is from 

the MMS study, OCS-Related Infrastructure in the Gulf of Mexico Fact Book (Louis Berger Group, Inc., 

2004). An update of the fact book is currently in progress (Dismukes, personal communication, 2007). 

In addition, MMS recently analyzed historical data and validated past scenario projections of new 

pipeline landfalls and new onshore waste disposal sites (USDOI, MMS, 2007g; Dismukes, personal 

communication, 2007). To date, no new information has been found that necessitates a change to the 

coastal infrastructure scenario presented in the Multisale EIS for either a proposed action or the OCS 

Program. A relatively minor amount of additional support activity is projected as a result of the addition 

of the 181 South Area; therefore, the coastal infrastructure scenario is still representative of likely future 

activity from a CPA proposed action. 

The MMS is not a permitting agency of onshore infrastructure. The permitting agencies would be the 

U.S. Army Corps of Engineers (COE) and the State in which the activity has or would occur. 

The following coastal infrastructure types are highlighted for discussion because there is either new 

general information available, new facilities projected to be constructed as a result of a proposed action, 

or new information relevant to discussions of the 181 South Area. 

3.1.2.1. 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. Chapters 3.3.5.8.1 and 4.1.2.1.1 of the Multisale EIS 

present a detailed description of OCS-related service bases. While a proposed action is not projected to 

significantly change existing OCS-related service bases or require any additional service bases, it would 

contribute to the use of existing service bases. Figure 3-3 shows the 50 service bases the industry 

currently uses to service the OCS. These facilities were identified as the primary service base from plans 

received by MMS. 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 are Galveston, 
3-22 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Freeport, and Port O’Connor, Texas; Cameron, Fourchon, Intracoastal City, Morgan City, and Venice, 

Louisiana; Pascagoula, Mississippi; and Theodore, Alabama. 

Exploration and development plans received by MMS identify primary and secondary service bases 

for three types of support: supply vessel, crewboat, and helicopter. Supply vessels would be used to 

transport pipe and bulk supplies, and the supply vessel base would be the loading point and provide 

temporary storage. Crewboats would transport personnel and small supplies. Helicopters would be used 

to transport personnel and small supplies. Service bases can support one or more of these activities. An 

offshore facility could utilize one service base for all three uses or different service bases for different 

uses. 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, it is expected this will only be on a temporary basis 

and that vessel traffic and helicopter transport should return to the primary and secondary bases as timely 

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). 

The MMS reviewed exploration and development plans near the 181 South Area. All plans reviewed 

identified Port Fourchon as the primary service base; however, for some plans, other bases instead of Port 

Fourchon were identified for either crew or helicopter (i.e., Galliano and Venice, Louisiana), or as a 

backup to Port Fourchon (i.e., Venice, Louisiana). 

For the near term, Port Fourchon would most likely be the primary service base to support oil and gas 

activity in the 181 South Area. Because of the limited amount of land available at Port Fourchon, the port 

may face capacity constraints in the long term. Operators are also looking to diversify risk from 

shutdowns like those experienced after Hurricanes Katrina and Rita, and are therefore likely to look to 

other ports. Thus, in the longer term, other deepwater access ports such as Theodore and Mobile, 

Alabama, and Pascagoula, Mississippi, could also support the 181 South Area. 

For the 181 South Area scenario analysis, MMS estimates that there would be approximately 4 trips 

per week by supply vessels to a facility during drilling and production, approximately 8 trips per week by 

crewboats during drilling operations, and approximately 14 helicopter round trips per week to a 

production facility. 

Hurricane Impacts on Service Bases 

While some service bases only suffered minimal damage from the back-to-back Hurricanes Katrina 

and Rita in 2005, others did not fare so well. The Port of New Orleans and the Port of South Louisiana 

both were able to resume limited operations shortly after Hurricane Katrina. The Port of New Orleans 

suffered extensive damage, yet by the end of March 2006, approximately 70 percent of the Port of New 

Orleans was operational and 85 percent of workers had returned. Officials at the Port of South Louisiana 

assessed the damage at approximately $2 million (Louisiana Hurricane Resources, 2006). Port Fourchon 

suffered both wind and water damage during both hurricanes. It took on 2-8 ft (1-2 m) of water in both 

hurricanes and suffered $7 million in damage. However, within a week of the storm, the port was 

approaching 35-45 percent of pre-Katrina activity, and after a month, it was at 90 percent (Russell, 2006). 

Of the ports in Louisiana that service the offshore oil and gas industry, the Ports of Venice and 

Cameron were the hardest hit and took the longest to return to near normal operation levels. However, as 

of late August 2006, all of the U.S. Gulf Coast seaports impacted by Hurricanes Katrina and Rita have 

returned their operations up to, at, or near what they were before the storms hit (Dismukes, personal 

communication, 2006). Two years after the storms, all but two of the tenants had returned to the Port of 

Venice, and only one site out of 61 was not leased. In addition to the improvements made at the port to 

recover from the storm, Venice is planning $10 to $15 million in improvements during the next five years 

(Russell, 2007). 

The Venice Port Complex and officials in Plaquemines Parish, Louisiana have been working together 

to advance a project to deepen Baptiste Collette Bayou from its current authorized depth of 16-27 ft 
Impact-Producing Factors and Scenario 3-23 

(4.9-8.2 m) to handle the large vessels needed to service the deep waters of the Gulf of Mexico. While 

such a project can take about 15 years to even get started, the port and Plaquemines Parish officials are 

pressing to get that time compressed into five years. The Parish is paying for a $250,000 reconnaissance 

study, normally done by the USCOE, to determine whether dredging would be in the Federal interest. 

After that study, a $3 million feasibility study will be necessary. The dredging itself is expected to cost 

$30 to $40 million (Russell, 2007). 

Although operations at both Venice and Cameron, Louisiana are nearly back to normal, as of January 

2008, the surrounding communities still face challenges associated with normal day-to-day living 

requirements. Housing opportunities near Venice have improved from a year ago, primarily through the 

addition of trailers and other mobile homes, and some limited grocery and food service has been restored 

close to the port facilities. However, there are still few restaurants open and hours of operation are 

limited. The recovery near Cameron appears to be even slower than what is occurring in Venice, 

particularly in terms of housing opportunities (Dismukes, personal communication, 2007). It is still 

common for companies operating at the ports to provide housing and three meals a day while employees 

work typical offshore schedules such as 7 days on/7 days off or 14 days on/14 days off to allow for long 

commutes (Russell, 2007). 

Navigation Channels 

The analysis performed to identify current OCS service bases (Chapter 3.3.5.8.1 of the Multisale EIS) 

was also used to identify relevant navigation waterways that support OCS activities. Table 3-36 of the 

Multisale EIS identifies the waterways and their maintained depth, while Figure 3-17 of the Multisale EIS 

shows their locations throughout the analysis area. No new navigation channels are expected to be 

dredged as a result of a proposed action; however, a proposed action would contribute to maintenance 

dredging of existing navigational canals. 

3.1.2.2. Gas Processing Plants 

Chapter 4.1.2.1.4.2 in the Multisale EIS describes gas processing plants that process raw gas to 

remove impurities such as water, carbon dioxide, sulfur, and inert gases, and transform it into a sellable, 

useful energy source. At present, there are 249 gas processing plants in the Gulf States, representing 58 

percent of U.S. gas processing capacity (USDOE, EIA, 2006a). The distribution of these plants by state 

is shown in Table 3-38 of the Multisale EIS. 

More than half of the current natural gas processing plant capacity in the U.S. is located convenient to 

Federal offshore Texas and Louisiana. Four of the largest capacity natural gas processing/treatment 

plants are found in Louisiana, while the greatest number of individual natural gas plants is located in 

Texas. Louisiana continues to lead the U.S. states in processing capacity, followed closely by Texas. 

Between them, the two states hold more than 53 percent of the Nation’s natural gas processing capacity 

(USDOE, EIA, 2006a). 

The MMS projects that up to 14 new gas processing plants with a facility size of 1.75 billion cubic 

feet per day (Bcf/d) could be needed, assuming average retirement and no expansions and/or the addition 

of new capacity to replace what is physically depreciating over the next 40 years at all existing facilities 

(Table 4-9 of the Multisale EIS). Of these, two are in Texas, three are in Louisiana, and nine are in the 

Mississippi-Alabama area. In reality, it is likely that few (if any) new, greenfield gas processing facilities 

would be developed along the Central or Western Gulf of Mexico. It is much more likely that a large 

share of the natural gas processing capacity that is needed in the industry will be located at existing 

facilities, using future investments for expansions and/or to replace depreciated capital equipment for a 

variety of reasons. These reasons include lower development costs because of existing structures and 

utility services; existing interconnections to pipelines, natural gas liquid lines, and fractionators; 

incremental labor requirements that are low relative to new facility staffing; the advantages of existing 

support, logistical and supply relationships such a vendors and maintenance support; and general 

economies of scale (Dismukes, personal communication, 2007). An example of this likely gas processing 

development scenario can be seen with the Venice Gas Processing facility in Plaquemines Parish, which 

has expanded several times to a current maximum capacity of 1.3 Bcf/d since it was developed in 1996 as 

an 810 million cubic feet per day (MMcf/d) facility (Dismukes, personal communication, 2007). 
3-24 Central and Western Gulf of Mexico Multisale Supplemental EIS 

At present, there is considerable excess gas capacity in the Gulf of Mexico. Existing gas capacity is 

sufficient to handle the additional 0.129-0.176 Tcf of gas projected to be produced over 40 years as a 

result of the addition of the 181 South Area. However, near the end of the 40-year life of a proposed 

action, 0-1 new facilities are expected to be constructed as a result of a CPA (including the 181 South 

Area) or WPA proposed action. 

3.1.2.3. Coastal Pipelines 

Chapters 3.3.5.8.8 and 4.1.2.1.7 of the Multisale EIS discuss 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. 

The MMS projected the number of Federal OCS landfalls that may result from proposed lease sales in 

order to analyze the potential impacts to wetlands and other coastal habitats. In the Multisale EIS and 

other previous EIS’s and EA’s, MMS 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, MMS projected up to one pipeline landfall per lease sale; however, recent 

MMS analysis showed that even one landfall as a result of an individual lease sale may be unlikely 

(USDOI, MMS, 2007g). Although there will be some instances where new pipelines may need to be 

constructed, there is nothing to suggest any dramatic shifts in the trends in new Federal OCS landfalls 

given the current outlook for Gulf of Mexico development, particularly in coastal Louisiana (Dismukes, 

personal communication, 2007). While there are some opportunities for new pipeline landfalls from 

increased production activity, many of those will be limited due to a number of factors associated with 

basic pipeline economics. 

As discussed in Chapter 3.1.1.4.1, no additional pipeline landfalls are projected as a result of the 

addition of the 181 South Area. Production from the 181 South Area would likely begin eight or more 

years after a lease sale. By that time it is anticipated that existing pipelines will have adequate capacity to 

transport gas production from the 181 South Area. While it is not likely oil production from the 181 

South Area would be transported by pipeline due to costs associated with heavier oil, there is sufficient 

capacity in existing pipelines near Texas were heavier oil production would be transported. 

3.1.2.4. Disposal and Storage Facilities for Offshore Operations 

Chapters 3.3.5.8.7 and 4.1.2.1.6 of the Multisale EIS describe the infrastructure network needed to 

manage the spectrum of waste generated by OCS exploration and production activities and returned to 

land for management. The analyses of coastal infrastructure presented in the Multisale EIS and other 

previous EIS’s and EA’s concluded that no new solid-waste facilities would be built as a result of a single 

lease sale or as a result of the OCS Program. Recent research further supports these past conclusions that 

existing solid-waste disposal infrastructure is adequate to support both existing and projected offshore oil 

and gas drilling and production needs (Dismukes et al., 2007). 

Although the addition of the 181 South Area resulted in some increases in the activity scenario for a 

typical CPA proposed action, these minor increases in activity were not significant enough to affect the 

long-term (i.e., 40-year) forecasts of waste disposal and storage needs to support either a typical CPA sale 

or the OCS Program. 

3.2. IMPACT-PRODUCING FACTORS AND SCENARIO—ACCIDENTAL EVENTS

Regulatory requirements have been established since the 1980’s to help prevent accidents and spills. 

The MMS pollution-prevention requirements include features such as redundant safety systems, and 

periodic inspection and testing protocols. Chapter 4.3 of the Multisale EIS 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 a proposed lease sale, which are summarized below. Estimates of accidental 

events that could result from activities associated with a proposed action have been updated to take into 

account the addition of the 181 South Area. 
Impact-Producing Factors and Scenario 3-25 

3.2.1. Oil Spills 

Oil spills are unplanned, accidental events but their frequency and volume can be estimated from past 

occurrences. Chapter 4.3.1 of the Multisale EIS analyzes the risk of spills that could occur as a result of 

activities associated with a proposed action in the CPA or WPA. 

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. Chapter 4.1.3.4.4.2 of the Multisale EIS discusses the cause and volume of spills that resulted 

from the hurricanes in 2005. 

Oil also enters the Gulf of Mexico by pathways other than spills. These major sources of oil inputs to 

the Gulf of Mexico include natural seeps, permitted discharges, and sources related to human activities 

and are discussed in Chapter 4.1.3.4 of the Multisale EIS and Chapter 3.1.1.3 of this SEIS. 

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. Oil discovered in the 181 South Area will likely be heavier oil, 20o

-30o API, than 

the oil represented in the Multisale EIS. A spill of heavier oil may present additional response challenges. 

Heavier oils may have a higher viscosity and less dispersibility than lighter oils (Trudel et al., 2001). The 

“window of opportunity” for dispersant application could be shorter and the heavier oils may also be 

more likely to emulsify and form tarballs. 

As spill size increases, the occurrence rate decreases and so the number of spills estimated to occur 

decreases (Tables 3-6 and 3-7). In general terms, coastal waters adjacent to the CPA and WPA 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 a 

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 actions. 

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. A 

published paper by MMS authors provides more information on OCS spill-rate methodologies and trends 

(Anderson and LaBelle, 2000). A discussion of how the range of resource estimates was developed is 

provided in Chapter 4.1.1.1 of the Multisale EIS and Chapter 3.1.1 of this SEIS. 

The mean number of future offshore spills ≥1,000 bbl is calculated by multiplying the spill 

occurrence rate for spills ≥1,000 bbl (1.51) by the volume of oil estimated to be produced as a result of a 

proposed action. The median size of spills ≥1,000 bbl that occurred during 1985-1999 is 4,551 bbl, and 

the median size for spills ≥10,000 bbl is 15,000 bbl (Table 4-16 of the Multisale EIS). Based on these 

median sizes, MMS estimates that the most likely size of an offshore spill ≥1,000 bbl resulting from a 

proposed action would be 4,600 bbl. 

Probability Results 

As shown on Table 3-6 and Figures 3-4 and 3-5, the mean number of offshore spills ≥1,000 bbl 

estimated for a proposed action in the CPA is 1-2 spills (mean equal to 1.22-2.02) with a 70-87 percent 

chance of one or more spills occurring. The incremental increase in oil production from the addition of 

the 181 South Area 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 a CPA proposed action. The mean number of spills estimated for a proposed 

action in the WPA is <1 spill (mean equal to 0.37-0.62) with a 31-46 percent chance of one or more spills 

≥1,000 bbl occurring. 
3-26 Central and Western Gulf of Mexico Multisale Supplemental EIS 

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 summarized below. 

Tables 4-37 and 4-36 of the Multisale EIS provide a mass balance over time for a hypothetical spill 

related to a proposed action in the CPA and WPA, respectively. The MMS estimates that an offshore 

spill ≥1,000 bbl of a typical Gulf of Mexico oil would dissipate from the water surface in 2-10 days. As 

mentioned previously, the API gravities of the oil from the 181 South Area may be heavier and would 

therefore weather differently. 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 photo-oxidation of 

specific compounds creating new components that are often more soluble, and biodegradation. 

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; many Gulf of Mexico oils do not (Jefferies, 1979). 

The MMS uses the SINTEF model to numerically model weathering processes (Daling et al., 1997; 

Reed et al., 2000; Prentki et al., 2004). Model results from the SINTEF weathering model are presented 

in Tables 4-36 and 4-37 of the Multisale EIS. Four scenarios were modeled. Information on the SINTEF 

model can be found in Daling et al. (1997), Reed et al. (2000), and Prentki et al. (2004). 

Movement into the deep waters of the Gulf of Mexico increasingly relies on subsea production 

infrastructure, possibly increasing the risk of seafloor releases. All evidence to date indicates that 

accidental oil discharges that occur at the seafloor (e.g., from a loss of well control or a pipeline break) 

would rise in the water column, surfacing almost directly over the source location. Additional 

information about the fate of a seafloor release is presented in Chapter 4.3.1.5.4 of the Multisale EIS. 

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 representative spill ≥1,000 bbl 

is estimated to be 30-50 km (19-31 mi) of shoreline, assuming such a spill were to reach land within 12 

hours (hr). Some redistribution of the oil due to longshore currents and further smearing of the slick from 

its original landfall could also occur. 

Likelihood of Occurring and Contacting Environmental Resources 

The MMS uses the Oil Spill Risk Assessment (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. 

A more complete measure of spill risk was calculated by multiplying the probability of contact 

generated by the OSRA model by the probability of occurrence of one or more spills ≥1,000 bbl as a 

result of a proposed action. This provides a risk factor that represents the probability of a spill occurring 

as a result of a proposed action and contacting the environmental resource of concern. These numbers are 

often referred to as “combined probabilities” because they combine the risk of occurrence of a spill 

≥1,000 bbl from OCS sources and the risk of such a spill contacting environmental resources. The 

combined probabilities are provided for each resource of concern in Figures 4-13 through 4-31 of the 

Multisale EIS. 

To better reflect the geologic distribution of oil and gas resources and natural variances of 

meteorological and oceanographic conditions in the computation of combined probabilities, MMS also 

generated combined probabilities for smaller areas within the CPA and WPA. The MMS used a cluster 

analysis to analyze the contact probabilities generated for each of the 4,000 launch points. For this 

analysis, similar trajectories and contact to 10-mi (16-km) shoreline segments were used to identify 

offshore cluster areas. The estimated oil production from a proposed action was proportionally 

distributed to the cluster areas and the likelihood of spill occurrence was calculated for each cluster area. 

The probability of spill occurrence was combined with probabilities of contact from the trajectory 

modeling to estimate the combined risk of spills occurring and contacting various resources from spills in 
Impact-Producing Factors and Scenario 3-27 

each cluster area. To account for the risk of spills occurring from the transportation of oil to shore, 

generalized pipeline corridors originating within each of the offshore cluster areas and terminating at 

major oil pipeline landfall areas were developed. The oil volume estimated to be produced as a result of a 

proposed action within each cluster area was proportioned among the pipeline corridors. The mean 

number of spills and the probability of contact of spills from each pipeline corridor were then calculated 

and combined with the risk of spills occurring and contacting resources from OCS facility development 

and production operations to complete the analysis. 

Inclusion of the 181 South Area increased the estimate of oil production for a CPA proposed action 

by 0.031-0.044 BBO, and the proposed CPA sale area by 4.3 million ac (6,719 mi2

). For this SEIS, the 

OSRA model was rerun due to the revised geographic area and increased oil production estimates in 

comparison with those used for the Multisale EIS. Results from this OSRA run confirmed that the 

revised geographic area and increased oil production estimates did not substantially affect probabilities in 

comparison with those obtained from the previous OSRA run. Updated spill occurrence probabilities that 

were computed based on these higher production estimates are shown in Tables 1a and 1b of Ji et al. (in 

preparation). The additional oil production is not projected to substantially increase the probabilities for 

occurrence of offshore spills ≥1,000 bbl (Table 3-6). Activity that would result from the addition of the 

181 South Area would cause a negligible increase, if any, in the risk of an offshore spill ≥1,000 bbl 

occurring and contacting environmental resources (Figures 3-6 through 3-11). 

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

Methods 

Chapter 4.3.1.6 of the Multisale EIS addresses the risk of spills <1,000 bbl that could occur from 

accidents associated with activities resulting from a proposed action. 

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. 

Likelihood of Occurring and Contacting Environmental Resources 

The number of offshore spills <1,000 bbl estimated to occur over the next 40 years as a result of a 

proposed action is provided in Table 4-35 of the Multisale EIS and has been updated to reflect the 

addition of the 181 South Area (Table 3-6). 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 a proposed 

action (Table 3-1). As spill size increases, the occurrence rate decreases and so the number of spills 

estimated to occur decreases. The average spill size is used for spills with size <1 bbl. For the larger spill 

size ranges, the median spill size calculated for each category from MMS historical records is used. 

During the 40-year analysis period, 97 percent of spills <1,000 bbl estimated to occur as a result of a 

proposed action would be ≤1 bbl. 

In the spill size range of >50-500 bbl, 6-9 spills are estimated to occur from activities related to a 

CPA proposed action, and 2-3 spills are estimated to occur from activities related to a WPA proposed 

action. 

The number of spills >500 and <1,000 bbl estimated to occur is less than one for a CPA proposed 

action. The number of spills >500 and <1,000 bbl estimated to occur is less than one for a WPA proposed 

action. The chance of one spill between 500 and 1,000 bbl occurring is 26-34 percent for a CPA 

proposed action and 11-17 percent for a WPA proposed action. 

The incremental increase in oil production from the addition of the 181 South Area to the proposed 

CPA sale area resulted in a slight increase in the estimated number of oil spills <500 bbl likely to occur as 

a result of a CPA proposed action. The addition of the 181 South Area did not result in an increase in the 

estimated number of spills >500 bbl. 
3-28 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Fate 

For an offshore spill <1,000 bbl to make landfall, the spill would have to occur proximate to State 

waters (defined as 3-12 mi or 6-19 km from shore). If a spill were to occur proximate to State waters, 

only a spill >50 bbl would be expected to have a chance of persisting long enough to reach land. Spills 

>50 and <1,000 bbl size occur infrequently. Should such a spill occur, the volume that would make 

landfall would be expected to be extremely small (a few barrels). These assumptions are supported by a 

previous analysis of 3-day trajectory model runs, previous weathering analyses, and historical records of 

spill incidents. 

The persistence of slicks from spills <1,000 bbl ranges from a few minutes (<1 bbl original spill size) 

to a few days (10-1,000 bbl original spill size) on the open ocean. Spilled oil would rapidly spread out, 

evaporate, and weather, quickly becoming dispersed into the water column. Most spills <1,000 bbl are 

expected to be diesel, which dissipates very rapidly. Diesel is a distillate of crude oil and does not contain 

the heavier components that contribute to crude oil’s longer persistence in the environment. Because 

spills <1,000 bbl are not expected to persist as a slick on the surface of the water beyond a few days and 

because spills on the OCS would occur at least 3-10 nmi (6-19 km) from shore, it is unlikely that any 

spills would make landfall prior to breaking up. Only spills >50 bbl have a chance of remaining a 

cohesive mass long enough to be transported any distance. 

3.2.1.3. Risk Analysis for Coastal Spills 

Chapter 4.3.1.7 of the Multisale EIS addresses the risk of spills of all sizes that could occur from 

accidents associated with activities resulting from a proposed action. 

Spills in coastal waters could occur as a result of transportation and handling of OCS-produced oil as 

it passes through State offshore waters and along navigation channels, rivers, and through coastal bays. 

The MMS projects that almost all (>99%) oil produced in waters <800 ft as a result of a proposed action 

will be brought ashore via pipelines while 50-100 percent of oil produced in waters >800 ft will be 

brought ashore via 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. 

Records of spills in coastal waters and State offshore waters are maintained by the USCG (USDOT, 

CG, 2007), which does not identify the source of the oil (i.e., OCS and non-OCS). Several USCG 

resources were used to estimate the number of coastal oil spills attributable to a proposed action, 

including the USCG Polluting Incident Compendium and data obtained from the USCG. The estimated 

number of spills in coastal waters that could be due to the proposed action is presented in Table 4-38 of 

the Multisale EIS. More information on the estimated number and most likely sizes of coastal spills, and 

the likelihood of coastal spill contacting with various resources is presented in Chapters 4.3.1.7.1 and 

4.3.1.7.2 of the Multisale EIS. 

The coastal spill rate is based on historical spills and the projected amount of oil production. For the 

purpose of this analysis, coastal spills are assumed to occur where oil production is brought to shore. 

Figure 3-12 shows major oil pipeline landfall areas. It is projected that the majority of oil production for 

a CPA proposed action will be brought to shore in eastern Louisiana, from Atchafalaya Bay to east of the 

Mississippi River. Based on this assumption the majority of coastal spills are projected to occur in this 

area, including one spill ≥1,000 bbl (assumed size 3,000 bbl) estimated to occur as the result of a CPA 

proposed action. Because the majority of oil production from a WPA proposed action is projected to be 

brought to shore in the Galveston/Houston/Texas City Area, it is assumed the majority of coastal spills 

from a WPA proposed action will also occur in this area. 

3.2.1.4. Risk Analysis by Resource 

Chapter 4.3.1.8 of the Multisale EIS summarizes MMS’s information on the risk to resources from oil 

spills and oil slicks that could occur as a result of a proposed action in the CPA or WPA. The risk results 

are based on MMS’s estimates of likely spill locations, sources, sizes, frequency of occurrence, physical 

fates of different types of oil slicks, and probable transport. For offshore spills, the analysis presents 

combined probabilities, which include both the likelihood of a spill from a proposed action occurring and 
Impact-Producing Factors and Scenario 3-29 

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 by environmental and socioeconomic resource in Chapter 4.4 of the 

Multisale EIS. The coastal spill risk is estimated from historic rate, not a probability. 

3.2.1.5. Spill Response 

3.2.1.5.1. MMS Spill-Response Requirements and Initiatives 

To ensure that industry maintains effective oil-spill-response capabilities, MMS 

• requires immediate notification for spills >1 bbl—all spills require notification to the 

USCG and MMS receives notification from the USCG of all spills ≤1 bbl; 

• conducts investigations to determine the cause of a spill; 

• assesses civil and criminal penalties, if needed; 

• oversees spill source control and abatement operations by industry; 

• sets requirements and reviews and approves oil-spill-response plans for offshore 

facilities; 

• conducts unannounced drills to ensure compliance with oil-spill-response plans; 

• requires operators to ensure that their spill-response operating and management 

teams receive appropriate spill-response training; 

• conducts inspections of oil-spill-response equipment; 

• requires industry to show financial responsibility to respond to possible spills; and 

• provides research leadership to improve the capabilities for detecting and responding 

to an oil spill in the marine environment. 

3.2.1.5.2. Offshore Response and Cleanup Technology 

Chapter 4.3.5.2 of the Multisale EIS discusses a number of cleanup techniques that are available for 

response to an offshore oil spill. Open-water response options include mechanical recovery, chemical 

dispersion, in-situ burning, or natural dispersion. Single or multiple spill-response cleanup techniques 

may be used in abating a spill. The cleanup technique chosen for a spill response will vary depending 

upon the unique aspects of each situation. The selected mix of countermeasures will depend upon the 

shoreline and natural resources that may be impacted; the size, location, and type of oil spilled; weather; 

and other variables. The overall objective of on-water recovery is to minimize the risk of impact by 

preventing the spread of free-floating oil. The physical and chemical properties of crude oil can greatly 

affect the effectiveness of containment and recovery equipment, dispersant application, and in-situ

burning. It is expected that oil found in the majority of the proposed lease sale areas could range from a 

medium-weight oil to condensates. Although still a medium weight oil, the oil expected in the 181 South 

Area and other extremely deep areas of the proposed lease sale area would tend to be a somewhat heavier 

oil than is found elsewhere in the lease sale area, ranging from 20 to30° API. 

Mechanical Cleanup 

Generally, mechanical containment and recovery is the primary oil-spill-response method used (33 

CFR 153.305(a)). Mechanical recovery is the process of using booms and skimmers to pick up oil from 

the water surface. It is expected that the oil-spill-response equipment needed to respond to an offshore 

spill in the proposed lease sale areas could be called out from one or more of the following oil-spill 

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 
3-30 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Orleans, Sulphur, Houma, Fourchon, Fort Jackson, and Venice, Louisiana; Pascagoula, Mississippi; 

Theodore and Mobile, Alabama; or Pensacola, Ft. 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. For 

example, due to the location of the 181 South Area, it would be quicker to use equipment from 

established oil-spill equipment bases located within the State of Louisiana. 

It is assumed that 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). 

Should an oil spill occur 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. This 

allows normal wind and wave action to break the oil into tiny droplets, which are dispersed into the upper 

portion of the water column. Natural processes then break down these droplets much quicker than they 

would if the oil were allowed to remain on the water surface. 

Dispersant use must be in accordance with the Regional Response Teams’ Preapproved Dispersant 

Use Manual and any conditions outlined within a Regional Response Team 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. For a deepwater 

(>1,000 ft or >305 m water depth) spill ≥1,000 bbl, which could include the 181 South Area, 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 of these locations dependent upon the 

physical and chemical properties of these deeper oils, 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 

Gulf of Mexico, it is expected that the dispersant application aircraft initially called out for an oil-spill 

response to an offshore spill in the proposed lease sale area will come from Houma, Louisiana; Stennis, 

Mississippi; or Coolidge, Arizona. The dispersants will come from locations primarily in Texas and 

Louisiana. Response times for this equipment would vary, depending on the spill site and on the transport 

time for additional supplies of dispersants to arrive at a staging location. Based on historic information, 

this SEIS assumes that dispersant application will be effective on 20-50 percent (S.L. Ross Environmental 

Research Ltd., 2000) of the treated oil. 

Should an oil spill occur during a storm, dispersant application would occur following the storm. 

Aerial and vessel dispersant application would not be possible while storm conditions continued. 

However, oil released onto the ocean surface during a storm event would be subject to accelerated rates of 

weathering and dissolution (i.e., oil and water would be agitated, forcing oil into smaller droplets and 

facilitating dissolution of the high-end aromatic compounds present). 

In-situ Burning 

In-situ burning is an oil-spill cleanup technique that involves the controlled burning of the oil at or 

near a spill site. The use of this spill-response technique can provide the potential for the removal of large 

amounts of oil over an extensive area in less time than other techniques. In-situ burning involves the 

same oil collection process used in mechanical recovery, except instead of going into a skimmer, the oil is 

funneled into a fire-boom, 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 
Impact-Producing Factors and Scenario 3-31 

collected in a boom, this method is typically more effective than skimmers when the oil is highly 

concentrated. 

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. 

Should an oil spill occur during a storm, in-situ burning would occur following the storm. In-situ

burning would not be possible while storm conditions continued. 

Natural Dispersion 

In some instances, 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 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 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 a 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 4,600-bbl 

pipeline spill scenarios analyzed in the Multisale EIS. The scenarios assumed oils of 30o

 and 35o API; 

however, heavier oil (20-30 o API) will likely be found in the 181 South Area. 

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 United States is accomplished through a mandated set of 

interrelated plans. The ACP represents the third tier of the National Response Planning System and was 

mandated by OPA 90. The ACP’s cover subregional geographic areas. The ACP’s are a focal point of 

response planning, providing detailed information on response procedures, priorities, and appropriate 

countermeasures. The Gulf coastal area that falls within USCG District 8 is covered by the One Gulf 

Plan ACP, which includes separate Geographic Response Plans for areas covered by USCG Sector 

Corpus Christi, Sector Houston/Galveston, Sector Port Arthur, Sector Morgan City, Sector New Orleans, 

and Sector Mobile. The Miami ACP covers the remaining Gulf coastal area. The ACP’s are written and 

maintained by Area Committees assembled from Federal, State, and local governmental agencies that 

have pollution response authority; nongovernmental participants may attend meetings and provide input. 

The coastal Area Committees are chaired by respective Federal On-Scene Coordinators from the 

appropriate USCG Office and are comprised of members from local or area-specific jurisdictions. 

Response procedures identified within an ACP or its Geographic Response Plan(s) reflect the priorities 

and procedures agreed to by members of the Area Committees. 

The single most frequently recommended spill-response strategy for the areas identified for protection 

in all of the applicable ACP’s or it’s 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. 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 
3-32 Central and Western Gulf of Mexico Multisale Supplemental EIS 

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. 

Shoreline Cleanup Countermeasures 

The following assumptions regarding the cleanup 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 Gulf of Mexico. As stated in Chapter 4.3.1.4 of the 

Multisale EIS, for this analysis it is expected that a typical oil spilled as a result of an accident associated 

with a 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 4.3.5.3 of the Multisale EIS, 

cleanup countermeasures for a 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 its 

Geographic Response Plans: 

• Barrier Island/Fine Sand Beaches Cleanup: After the oiling of a barrier island/fine 

sand beach with a medium-weight oil, applicable cleanup options are manual 

removal, trenching (recovery wells), sediment removal, cold-water deluge flooding, 

shore removal/replacement, and warm-water washing. Other possible shoreline 

countermeasures include low-pressure cold-water washing, burning, and nutrient 

enhancement. Responders are requested to avoid the following countermeasures: no 

action; passive collection (sorbents); high-pressure, cold-water washing; hot-water 

washing; slurry sand blasting; vacuum; and vegetation cutting. 

• Fresh or Salt Marsh Cleanup: In all cases, cleanup options that avoid causing 

additional damage to the marshes will be selected. After the oiling of a fresh or salt 

marsh with a medium-weight oil, the 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 re-oiling of birds is 

possible. Chemical treatment, burning, and bacterial addition as countermeasures 

under consideration. Responders are advised to avoid manual removal, passive 

collection, debris removal/heavy equipment, sediment removal, cold-water flooding, 

high- or low-pressure cold-water washing, warm-water washing, hot-water washing, 

slurry sand blasting, and shore removal/replacement. 

• Coarse Sand/Gravel Beaches Cleanup: After the oiling of a coarse sand/gravel 

beach with a 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 lowpressure, cold-water 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 a 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 
Impact-Producing Factors and Scenario 3-33 

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 

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. Loss of well control is a broad term that includes very 

minor up to the most serious well control incidents, while blowouts are considered to be a subset of more 

serious incidents with greater risk of oil spill or human injury. Historically, most losses of well control 

have occurred during development drilling operations, but loss of well control can happen during 

exploratory drilling, production, well completions, or workover operations. Loss of well control may 

occur during drilling between zones in the wellbore or may occur at the seafloor. One-third of the losses 

of well control were associated with shallow gas flows. Most losses of well control last for a short 

duration, with half lasting less than a day. Chapter 4.3.3 of the Multisale EIS discusses losses of well 

control in detail. 

Loss of well control may result in the release of synthetic drilling fluid, chemicals, or loss of oil. 

From 1996 to 2005, 21 percent of losses of well control resulted in spilled oil or SBF, or released gas or 

condensate. In addition to spills, the loss of well control can resuspend and disperse bottom sediments. 

An additional 9-12 wells are projected to be drilled as a result of the addition of the 181 South Area 

per proposed CPA sale. Based on the blowout rate of 6 per 1,000 well starts, no additional blowouts are 

projected as a result of the addition of the 181 South Area. 

3.2.3. Vessel Collisions 

Safety fairways, traffic separation schemes, and anchorages are the most effective means of 

preventing vessel collisions with OCS structures. In general, fixed structures such as platforms and 

drilling rigs are prohibited in fairways. The MMS data show that, from 1996 to 2005, there were 129 

OCS-related collisions. 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. Chapter 

4.3.3.3 of the Multisale EIS provides a more detailed discussion of vessel collisions. 

Chapter 3.3.5.7.3 of the Multisale EIS discusses damage to platforms from recent hurricanes. 

Platforms destroyed by hurricane force winds and waves become potential obstructions to offshore 

operators and mariners in the Gulf of Mexico. To prevent any further collisions with submerged or 

destroyed platforms, MMS, in December 2005, published a safety alert that provided the location of all 

facilities that were destroyed by Hurricanes Katrina and Rita. 

3.2.4. Chemical and Drilling-Fluid Spills 

Chemicals are used to condition drill muds in completions, stimulation, and workover processes and 

during production. Chemicals are stored offshore in quantities related to their uses. Table 3-8 presents 

the number and volume of chemical and synthetic-based fluid (SBF) spills in the Gulf of Mexico during 

2001-2005. Only two chemical spills of ≥1,000 bbl have occurred between 1964 and 2005. 

Chemical Spills 

Between 5 and 15 chemical spills are anticipated each year as a result of the OCS Program, 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 hydrate 
3-34 Central and Western Gulf of Mexico Multisale Supplemental EIS 

formation is a possibility, but spill volumes are anticipated to remain the same because of advances in 

subsea processing. Chemical and drilling-fluid spills are discussed in greater detail in Chapter 4.3.4 of 

the Multisale EIS. 

Synthetic-Based Fluid Spills 

The SBF have been used since the mid 1990’s. Between 5 and 20 SBF releases are anticipated each 

year as a result of the OCS Program, with the majority being <50 bbl in size (Table 3-9). An SBF spill of 

1,061-bbl base fluid occurred in October 2007 due to a crack in the riser termination spool. This spill site 

will be studied using funds set aside and titled Synthetic-based Fluid Spill of Opportunity Environmental 

Impact and Recovery (Neff et al., 2000). The study explores recovery from a spill as opposed to recovery 

from permitted SBF-wetted cuttings discharges where most of the field research has been conducted. 

Resampling to document pollutant biodegradation and redistribution over time is presently not part of the 

study. The hurricanes in 2004 and 2005 resulted in increased chemical spills and the loss of containerized 

chemicals overboard. Mud slides and submerged and drifting rigs damaged pipelines and supply lines on 

the seafloor. Hurricane-related chemical and SBF releases may occur during the hurricane or afterwards 

when operations are brought back online. 

3.3. CUMULATIVE ACTIVITIES SCENARIO

The following cumulative scenario includes 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 impacts of cumulative activities on biological, physical, 

and socioeconomic resources are analyzed in Chapter 4.5 of the Multisale EIS and Chapter 4.1 of this 

SEIS. 

3.3.1. OCS Program 

Chapter 4.1 of the Multisale EIS also describes the scenario for the OCS Program (i.e., activity 

resulting from past and future lease sales). 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. Projected reserve/resource production for the OCS Program is 28.562-

32.570 BBO and 142.366-162.722 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. 

The MMS, 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. While the scenario for a typical CPA sale has been 

revised for the expanded sale area, the Gulfwide cumulative scenario has not changed. Relative to CPA 

and WPA sales, a very small amount of exploration and development activity is forecasted to occur as a 

result of the addition of the 181 South Area. Therefore, despite the additional acreage offered, the range 

of exploration and development activities forecasted to occur as a result of the OCS Program has not 

changed. The level of 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. The impacts of activities 

associated with the OCS Program on biological, physical, and socioeconomic resources are analyzed in 

the cumulative environmental analysis sections of Chapter 4.1. 

3.3.2. State Oil and Gas Activity 

The coastal infrastructure that supports the OCS Program also supports State oil and gas activities. 

Chapters 3.3.5.9 and 4.1.3.1 of the Multisale EIS discuss in detail State oil and gas activities. A summary 

is presented below. 
Impact-Producing Factors and Scenario 3-35 

Offshore Oil and Gas Leasing and Production 

Texas land extends 10.4 mi (16.7 km) offshore. The Railroad Commission of Texas is the agency 

charged by the Texas Legislature with the regulation of the oil and gas industry in the State of Texas. The 

Lands and Minerals Division of the Texas General Land Office holds lease sales quarterly in January, 

April, July, and October. Sales are usually held on the first Tuesday of the month; however, the January 

and July sales have been held in recent years on the second Tuesday of the month because of holidays. 

The territorial waters of Louisiana extend Gulfward for 3 nmi (5.6 km). The Office of Mineral 

Resources holds regularly scheduled lease sales on the second Wednesday of every month. As in Texas, 

the State of Louisiana’s offshore oil and gas leasing program is conducted on a regular basis irrespective 

of the Federal OCS mineral leasing program. 

In recent years, oil and gas production in the State of Louisiana, as in Texas, has been declining. The 

MMS projects that the State’s offshore production would continue this trend over the analysis period. 

Hurricanes Katrina and Rita (2005) also affected State oil and gas production. As of March 2006, 85.5 

percent of the daily oil production capacity of a 38-parish region had been restored, and 97 percent of the 

daily gas production capacity had been restored (LADNR, 2006c). 

The territorial waters of Mississippi extend Gulfward for 3 nmi (5.6 km). The State of Mississippi 

does not have an offshore oil and gas leasing program. The MMS does not expect the State to institute 

such a program in the near future. 

The territorial waters of Alabama extend Gulfward for 3 nmi (5.6 km) and its shoreline extends 52 mi 

(84 km). 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 MMS does not expect the State to institute such a program in the near future. 

The State of Florida has experienced very limited drilling in coastal waters. In 2005, Florida’s 

Governor Jeb Bush and the Florida Cabinet signed a historic settlement agreement to eliminate the 

potential for oil drilling in State waters. 

State Pipeline Infrastructure 

The existing pipeline network in the Gulf Coast States is developed and extensive, with spare 

capacity. Expansion is projected to be primarily small diameter pipelines to increase the interconnectivity 

of the existing network and a few major interstate pipeline expansions. Pipeline companies are taking 

steps to reduce impacts from future hurricanes by adding new interconnections to their pipeline networks 

to create alternate routes in case of damage to one part of the network (Federal Trade Commission, 2006). 

Any new larger diameter pipelines would likely be constructed to support onshore and offshore LNG 

terminals. However, as discussed in Chapter 4.1.3.2.6 of the Multisale EIS, there is spare capacity in the 

existing pipeline infrastructure to move the regasified natural gas to market, and deepwater ports can 

serve onshore facilities, including intrastate as well as interstate pipelines. 

3.3.3. Other Major Offshore Activities 

Dredged Material Disposal 

Chapter 4.1.3.2.1 of the Multisale EIS discusses in detail disposal of dredged material. Dredged 

material is described at 33 CFR 324 as any material excavated or dredged from navigable waters of the 

U.S. Virtually all ocean dumping occurring today is dredged material, sediments removed from the 

bottom of waterbodies in order to maintain navigation channels and berthing areas. The USEPA, COE, 

and other interested parties are working to identify appropriate uses for dredged material rather than 

disposing of the material offshore. These uses may include beach nourishment or wetland habitat 

development. 

Non-energy Minerals Program in the Gulf of Mexico 

Chapter 4.1.3.2.2 of the Multisale EIS discusses in detail MMS’s Marine Minerals Program, which 

provides policy direction for the development of marine mineral resources on the OCS. The Program 
3-36 Central and Western Gulf of Mexico Multisale Supplemental EIS 

continues to focus on identifying sand resources for coastal restoration, investigating the environmental 

implications of using those resources, and processing noncompetitive use requests. 

Numerous restoration projects have used sand resources from borrow areas on the OCS that were 

identified by the highly successful MMS-State cooperative offshore sand program that was in place from 

the mid 1990’s to 2005. Sand deposits identified and evaluated by the cooperative program have been 

used for three beach nourishment projects in Maryland, five projects in Virginia, and four in Florida. 

Sand sources identified through the MMS cooperative effort with Louisiana will likely serve as the major 

source of material for the restoration of the entire barrier island chain located in the southwestern and 

central Louisiana coastal area, identified in the Louisiana Coastal Area Ecosystem Restoration Plan. 

Although funding to continue the MMS-State cooperative program has been discontinued, MMS did 

receive earmark funds in 2005 to conduct offshore sand studies in support of coastal restoration efforts in 

the Gulf Coast States of Louisiana, Texas, Alabama, and Mississippi. The funds are currently being used 

to investigate available sources of OCS sand for the restoration of portions of coastal areas that were 

damaged by Hurricanes Katrina and Rita. The Louisiana Dept. of Natural Resources (LADNR) and 

Louisiana State University (LSU) are undertaking a joint effort to identify potential sand resources in the 

Trinity and Tiger Shoal complex, located in the Vermilion and South Marsh Island lease areas. 

Meanwhile, the General Lands Office in Texas is collecting new geologic and geophysical data to 

describe potential resources in buried Pleistocene Sabine and Colorado River paleochannels, located 

offshore Jefferson and Brazoria Counties. 

The OCS sand and gravel resources must be wisely managed to ensure that environmental damage to 

the marine and coastal environments is minimized, mitigated, or does not occur. The MMS has focused 

on integrating the collected sand resource data with environmental studies to provide needed 

environmental information to make decisions regarding the use of OCS sand for future coastal restoration 

activities. A number of projects are in progress with the State of Louisiana and LSU to examine the longterm effects of dredging sand on Ship Shoal, a large potential borrow area offshore central Louisiana, as 

well as on Trinity and Tiger Shoals and Sabine Bank, along the central and west coasts of Louisiana. The 

State, LSU, and MMS are also cooperating to provide real-time wind, wave, and current data in support 

of numerical modeling exercises to determine the physical effects of dredging offshore, as well as 

providing invaluable information for actual dredging operations. 

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, MMS initiated a regional 

offshore sand management program in Louisiana in 2003, which over the course of 4 years and several 

meetings has developed options and recommendations for an orderly process to manage OCS sand 

resources in areas of competing use. The Louisiana Sand Management Working Group is currently 

assisting MMS in developing 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. 

To date, two sand leases have been issued (and subsequently terminated) in the CPA (i.e., the Sabine 

Pass/West Cameron areas, offshore Holly Beach, Cameron Parish, Louisiana; and the South Pelto area, 

offshore Terrebonne Parish, Louisiana), whereas none have been issued in the WPA. The Holly Beach 

lease provided 4.2 million yd3

 of OCS sand from Sabine Bank and the buried Peveto paleochannel. The 

MMS is negotiating an agreement with NOAA and the State of Louisiana for a major coastal and 

wetlands restoration project at Pelican Island in Plaquemines Parish, Louisiana. The negotiated 

agreement is expected to be finalized and issued in early the spring of 2008. The project involves the use 

of approximately 5,500,000 yd3

 of OCS sand from the buried Sandy Point paleochannels (West Delta 

Area) in a planned shoreline stabilization and marsh creation project, authorized under the Coastal 

Wetlands Planning, Protection, and Restoration Act (CWPPRA). The project, at a total cost of $60 

million, is the largest funded CWPPRA project to date and will create 800 ac (1.25 mi2

) of beach and 

marsh habitat that will help protect Louisiana’s coastal communities and infrastructure from the 

devastating effects of wind, waves, and flooding. The project is of exceptionally high importance and 

priority to the State of Louisiana and has had major support from both Governor Jindal and Senator 

Landrieu. 
Impact-Producing Factors and Scenario 3-37 

Marine Transportation 

Chapter 4.1.3.2.3 of the Multisale EIS discusses the extensive maritime industry that exists in the 

northern Gulf of Mexico. Marine transportation within the analysis area should grow linearly based on 

historical freight traffic statistics given current conditions. The estimated number of vessel trips that 

would occur as a result of a proposed action is presented in Tables 3-2 and 3-3. Because this would 

represent a small percentage of marine transportation in the Gulf of Mexico, marine transportation is not 

expected to significantly change as a result of a CPA or WPA proposed action. 

Military Activities 

Chapter 4.1.3.2.4 discusses in detail the extensive use of the offshore Gulf of Mexico for military 

activities. The air space over the Central and Western Gulf of Mexico is used by the Department of 

Defense (DOD) for conducting various air-to-air and air-to-surface operations. Nine military warning 

areas and five EWTA are located within the Gulf (Figure 2-2). The 181 South Area is located within two 

EWTA’s. These warning and water test areas are multiple-use areas where military operations and oil 

and gas development have coexisted without conflict for many years. Based on that past experience, 

several military stipulations are planned for leases issued within identified military areas. All of the 

available CPA acreage identified for leasing consideration is west of the critical military mission zone of 

Eglin Air Force Base (i.e., a zone to the west of 86 ̊41' W. longitude) (Figure 2-2). 

Artificial Reefs and Rigs-to-Reefs Development 

Chapter 4.1.3.2.5 and Appendix A.4 of the Multisale EIS discusses in detail artificial reefs and rigsto-reefs development in the Gulf of Mexico. Artificial reefs have been used along the coastline of the 

U.S. since the early 19th century. Stone (1974) documented that the use of obsolete materials to create 

artificial reefs has provided valuable habitat for numerous species of fish in areas devoid of natural hard 

bottom. Stone et al. (1979) found reefs in marine waters not only attract fish, but in some instances also 

enhance the production of fish. All of the five Gulf Coast States—Texas, Louisiana, Mississippi, 

Alabama, and Florida—have artificial reef programs and plans. 

All OCS platforms have the potential to serve as artificial reefs. Offshore oil and gas platforms began 

providing artificial reef substrate in the Gulf of Mexico with the first platform installation in 1942. 

Historically, approximately 9 percent of the platforms decommissioned in the Gulf OCS have become 

used in the Rigs-to-Reefs (RTR) program. It is anticipated that approximately 10 percent of platforms 

installed as a result of a proposed action would become an RTR after decommissioning. For the OCS 

Program over the next 40 years, projections are that about twice as many platforms will be removed than 

those installed. 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 RTR program. 

Some of the 113 platforms destroyed by Hurricanes Katrina and Rita have been accepted into the 

RTR program. Louisiana has created numerous “Special Artificial Reef Sites” that use downed 

platforms. Due to the extreme water depths of the 181 South Area, it is not anticipated that any platforms 

installed in the 181 South Area would become RTR’s. 

Offshore Liquefied Natural Gas Projects 

Chapter 4.1.3.2.6 of the Multisale EIS discusses in detail offshore LNG terminals projected, 

approved, and existing in the Gulf of Mexico. At present in the Gulf of Mexico, the only existing 

offshore LNG terminal is Gulf Gateway located approximately 116 mi (187 km) offshore Louisiana. 

There have been an additional three licenses issued, three applications are under review, and three 

applications have been withdrawn or closed (USDOT, MARAD, 2008). 
3-38 Central and Western Gulf of Mexico Multisale Supplemental EIS 

3.3.4. Other Major Influencing Factors on Coastal Environments 

Submergence of Wetlands 

Chapter 4.1.3.3.1 of the Multisale EIS discusses in detail the submergence of wetlands. Other major 

factors contributing to submergence of wetlands along the Gulf Coast are eustatic sea-level rise and land 

subsidence. Eustatic sea-level rise is caused by the reduction of the volume of water stored in the polar 

ice caps and expansion of ocean waters because of global warming. Land subsidence is caused by a 

variety of localized natural and manmade events such as down-warping or horizontal movement of the 

earth’s crust; weighted surface compression; oxidation, consolidation, settling, and dewatering of surface 

sediments; and depressurization of subsurface reservoirs during oil and gas production (Swanson and 

Thurlow, 1973; Morton, 2003; Morton et al., 2002). In localized areas, subsidence and sea-level rise can 

be offset by sedimentation, placement of dredged material, and peat formation. 

During the past century, the rate of eustatic sea-level rise along the Louisiana coast was relatively 

constant at 2.3 mm/yr (0.9 in/yr or 23 cm/century), although the rate has varied from a sea-level decrease 

of 3 mm/yr (0.12 in/yr) to a maximum increase of 10 mm/yr (0.39 in/yr) over decade-long periods 

(Turner and Cahoon, 1988; Williams and Burkett, 2002). 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). One of the major factors causing greater submergence rates in Louisiana is reduced sedimentation, 

resulting from deltaic abandonment, flood control, and channelization of the Mississippi River. There is 

scientific consensus that sea-level rise will continue and is likely to increase into the next century. The 

Intergovernmental Panel on Climate Change (IPCC)’s currently estimates the global average sea level 

will rise between 0.6 and 2 ft (0.18 and 0.59 m) in the next century (IPCC, 2007). 

Subsidence or sinking of the land surface in southern Louisiana and the entire south-central U.S. is 

mainly attributed to the weight of Mississippi River mud that makes up the geography of the region, 

drainage and oxidation of organic soils, natural compaction and dewatering of surficial sediments, and 

tectonic activity (geosynclinal downwarping and movement along growth faults). The problem is 

aggravated in Louisiana by flood protection measures and disruption of natural drainage ways that reduce 

sediment deposition to the Deltaic region. Fluid withdrawal, including groundwater withdrawals and oil 

and gas production, can cause localized subsidence in the aquifer system and above the producing 

reservoirs. In coastal Louisiana, about 400 km2

 (98,842 ac) of wetlands have a subsidence potential 

greater than 10 cm (4 in) because of fluid withdrawal (Turner and Cahoon, 1988). Morton (2002) used 

geodetic releveling surveys to identify historical subsidence rates of 9.4 mm/yr (0.62 in/yr) and averaging 

6.4 mm/yr (0.25 in/yr) along Bayou Petit Caillou in Terrebonne Parish, Louisiana. The average 

subsidence rate for Terrebonne Parish over the last 5,000 years is calculated at <3 mm/year (0.12 in/yr) 

(Roberts et al., 1994). Thus, hydrocarbon production can induce local subsidence rates sufficient to result 

in significant landloss. 

River Development and Flood Control Projects 

Chapter 4.1.3.3.2 of the Multisale EIS discusses in detail river development and flood control 

projects. 

In recent decades, alterations in the upstream hydrology of the rivers draining into the northern Gulf 

of Mexico have resulted in a variety of coastal impacts. Dams and reservoirs on upstream tributaries trap 

much of the sediment load in the rivers. The suspended sediment load of the Mississippi River has 

decreased nearly 60 percent since the 1950’s, largely as a result of dam and reservoir construction 

upstream (Tuttle and Combe, 1981; Turner and Cahoon, 1988). 

In a natural system, over-bank flooding introduces sediments into adjoining wetlands. Flood control 

on the Mississippi and other rivers has largely eliminated flood-borne sedimentation in the Gulf coastal 

wetlands, contributing to their deterioration. 

Channelization of the Mississippi and other rivers in conjunction with flood control levees has also 

contributed to wetland loss and has interrupted wetland creation around the Gulf by preventing 

distribution of alluvial sediments across deltas and flood plains. Prior to channelization, the flow of rivers 

was distributed among several distributary channels that delivered sediment over a broad area during high 
Impact-Producing Factors and Scenario 3-39 

river stages. Today, sediment from the Mississippi River is primarily discharged through the main 

channel directly to the deep waters of the continental slope. The only significant exception to this 

scenario is the diversion of approximately 30 percent of the Mississippi River flow to the Atchafalaya 

River; this diversion does not capture 30 percent of the sediment flow, however, since most of the 

sediment is restricted to the deeper river channel. 

Dredging 

Chapter 4.1.3.3.3 of the Multisale EIS discusses dredging in detail. 

Dredging operations include sediment and gravel harvesting; pipeline installation; canal installation, 

maintenance, and modifications; harbor installation and maintenance; and stream channelization. 

Numerous channels are maintained throughout the onshore cumulative activity area by Federal, State, 

county, commercial, and private interests. Proposals for new and maintenance dredging projects are 

reviewed by Federal, State, and county agencies as well as by private and commercial interests to identify 

and mitigate adverse impacts upon social, economic, and environmental resources. 

Materials from maintenance dredging are primarily disposed within existing, confined, dredgedmaterial disposal facilities. 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. Some dredged sediments are dispersed into offshore waters at established 

offshore disposal sites. Materials may also be used in a beneficial manner to restore and create habitat, 

beach nourishment projects, and industrial and commercial development. 

Dredged materials from channels are often contaminated with toxic heavy metals, organic chemicals, 

pesticides, oil and grease, and other pollutants originating from municipal, industrial, and vessel 

discharges and nonpoint sources, and thus can result in contamination of areas formerly isolated from 

major anthropogenic sources (USEPA, 1979). The vicinities around harbors and industrial sites are most 

noted for this problem. Hence, sediment discharges from dredging operations can be major point sources 

of pollution in coastal waters in and around the Gulf. In addition, inland and shallow offshore disposal 

can change the navigability and natural flow or circulation of waterbodies. 

In 1989, USEPA estimated that more than 90 percent of the volume of material dumped in the oceans 

around the U.S. consisted of sediments dredged from U.S. harbors and channels (USEPA, 1989). As of 

February 1997, in response to the Marine Protection, Research, and Sanctuaries Act of 1972, USEPA had 

finalized the designation of eight dredged-material disposal sites in the cumulative activity area. Another 

four sites in the Gulf are considered interim sites for dredged-material disposal. These sites primarily 

facilitate the COE’s bar-channel dredging program. Generally, each bar channel of navigation channels 

connecting the Gulf and inland regions has 1-3 disposal sites used for disposal of maintenance dredged 

material. These are usually located in State waters. Some designated sites have never been used. 

Installation and maintenance of any navigation channel and many pipeline canals connecting two or 

more waterbodies changes the hydrodynamics in their vicinity. These changes are typically associated 

with saltwater intrusion, reduced freshwater retention, changed circulation patterns, changed flow 

velocities, and erosion. When these channels are permitted for construction through sensitive wetland 

habitats or when sites are permitted for dredged-material disposal, measures are required to mitigate 

unavoidable adverse environmental impacts. Structures constructed to mitigate adverse hydrodynamic 

impacts and accelerated erosion includes dams, weirs, bulkheads, rip-rap, shell/gravel mats, and gobi 

mats. 

Typically, little or no maintenance is performed on mitigation structures. Without maintenance, 

many mitigation facilities, particularly in regions where the soil is poorly consolidated and has a high 

organic content, are known to become ineffective within a few years of construction. The number of 

mitigation structures associated with navigation and pipeline channels is unknown. 

3.3.5. Coastal Restoration 

Chapter 4.1.3.3.4 of the Multisale EIS discusses coastal restoration efforts and funding by State. 

The coastal infrastructure that supports State and OCS oil and gas activities would benefit from 

coastal restoration. Coastal erosion could have a significant negative impact on this coastal infrastructure, 

including pipelines, navigation channels, and supply bases (U.S. Dept. of the Army, COE, 2004c). The 

extensive pipelines traversing coastal Louisiana are affected by coastal erosion as barrier islands and 
3-40 Central and Western Gulf of Mexico Multisale Supplemental EIS 

coastal wetlands erode and as open water scours away land-protecting pipelines. Exposed pipelines, once 

buried, are at increased risk from failure or damage because of lack of structural stability, anchor 

dragging, and boat collisions. Navigation infrastructure is also already being impacted by coastal erosion 

as shown in three areas of the Gulf Intracoastal Waterway (GIWW). In those areas there is increased 

shoaling, causing traffic moving on the waterway to slow down, increasing the time and cost of moving 

commodities. Annual dredging maintenance cost has increased to keep the channel at authorized depths. 

Supply bases servicing offshore OCS oil and gas activities are also impacted by coastal erosion. These 

bases provide necessary supplies and maintenance services to the offshore platforms and serve as 

“jumping-off” points for employees that work on offshore platforms. If one of the important supply 

bases, such as Port Fourchon, was severely impacted by coastal degradation, the operational cost of 

offshore production could go up significantly. 

In December 2007, the U.S. Government Accountability Office (GAO) published a report on lessons 

learned on coastal restoration in Louisiana (GAO, 2007). The GAO reviewed the CWPPRA program, 

and the following is a summary of its findings. 

Over the next 50 years, Louisiana is projected to lose almost 17 mi2

 (10,880 ac) of coastline each year 

due to storms, sea-level rise, and land subsidence. Coastal wetlands are an important wildlife and 

commercial resource, and provide a natural buffer against the storm surge that accompanies storms and 

hurricanes. Recently, Congress made billions in new funding available over the next 20 years for coastal 

Louisiana. 

Under CWPPRA, 147 projects have been designed and/or constructed to restore and protect over 

120,000 ac (188 mi2

) of coastal wetlands (about 3% of the Louisiana coast). Projects have included largescale efforts that reintroduce freshwater and sediment to declining wetlands, as well as smaller projects 

such as shoreline barriers and vegetation plantings to protect and restore the coastal landscape. As of 

June 2007, half have been completed. Costs can vary from about $9,000 per acre to plant marsh plants to 

almost $54,000 per acre to restore barrier islands. The estimated cost to complete all 147 projects was 

$1.78 billion. There are additional costs to maintain projects over their expected life spans, which, in 

most cases, is about 20 years. 

The GAO identified the following issues that will need to be addressed as coastal restoration becomes 

larger and more complex: 

• Increasing project costs can delay individual projects, as well as the overall 

program—currently 10 CWPPRA projects are on hold waiting for funds because 

estimated construction costs exceed funds available. 

• Without an integrated monitoring system, officials cannot determine whether goals 

and objectives are being met—even after 4 years such a system is not fully 

implemented for CWPPRA. 

• Identifying and addressing private landowner issues is critical in the project design 

phase—in some instances, these issues have led to costly project modifications or 

construction delays for some CWPPRA projects. 

• Some projects simply fail to perform as designed due to landscape, structural, or 

other causes beyond the designers’ control—some CWPPRA projects were 

terminated because such problems were not anticipated or could not be resolved. 

• Storms and hurricanes can result in significant setbacks to projects—large areas of 

both naturally occurring and restored wetlands can be destroyed in just a few days if 

hit by a powerful storm. 

3.3.6. Alternative Energy 

Chapter 4.1.3.3.5 of the Multisale EIS discusses in detail alternative energy. 

On August 8, 2005, President George W. Bush signed into law the Energy Policy Act of 2005 (the 

Act). Section 388 (a) of the Energy Policy Act of 2005 amended Section 8 of the Outer Continental Shelf 

Lands Act (OCSLA) (43 U.S.C. 1337) to authorize DOI to grant leases, easements, or right-of-ways on 

the OCS for the development and support of energy resources other than oil and gas and to allow for 
Impact-Producing Factors and Scenario 3-41 

alternate uses of existing structures on the OCS lands. The MMS is developing a comprehensive program 

and regulations to implement the new authority. As a part of this process, MMS has published an 

Advance Notice of Proposed Rulemaking (ANPR) in the Federal Register on December 30, 2005, and 

seeks comments on alternate energy-related uses on the OCS. In November 2007, MMS published the 

Final Programmatic Environmental Impact Statement for the OCS Alternative Energy and Alternate Use 

Program and the Request for Information and Nominations of Areas for Leases for Alternative Energy. 

The MMS also announced an interim policy for the authorization of the installation of offshore data 

collection and technology testing facilities in Federal waters. 

Two wind farm projects are currently going through the permitting process in the U.S. The Cape 

Wind project is located on Horseshoe Shoal in Nantucket Sound, Massachusetts, and the Long Island 

Power Authority project is located off the south shore of Long Island, New York. In January 2008, MMS 

published a draft EIS on the Cape Wind Energy Project. The MMS is awaiting the official decision from 

the Long Island Power Authority on the disposition of the Long Island Offshore Wind Park project. 

The wind resource potential of the Gulf of Mexico is not very well documented. Archer and 

Jacobson (2003) conducted a study of U.S. winds and wind power at 80 m (256 ft) height. Their study 

concluded that the Gulf of Mexico has a higher potential of wind resources than previously thought. 

These unexpected levels of wind velocity have led to interest in wind energy generation in the Gulf of 

Mexico. On October 24, 2005, the Texas General Land Office announced that the State of Texas has 

signed an agreement with Galveston-Offshore Wind, LLC, to allow the first offshore wind energy project 

on the Gulf of Mexico. 

In October 2007, the State of Texas awarded the U.S.’s first competitively bid leases for offshore 

wind power (Texas General Land Office, 2007). Four leases were awarded to Wind Energy Systems 

Technology, which allow work to begin immediately on the construction of meteorological testing 

towers. The four tracts total 73,098 ac (114 mi2

) and are located near Jefferson, Calhoun, Brazoria, and 

Cameron Counties. The company already holds the U.S.’s only offshore lease for wind power and is 

collecting data for a wind farm off the coast of Galveston, Texas. 

Until MMS promulgates the regulations under which these projects will operate, MMS will accept no 

proposals for alternate energy development or for alternate uses of the existing oil and gas facilities 

located on the Federal OCS. Once MMS finalizes appropriate regulations, the demands for projects of 

this type are expected to grow on the OCS. Evaluation of meteorological data collected in Texas State 

waters would also tell us in the near future about the possibility of siting wind farms on the Gulf’s OCS 

for generating electricity. 

3.3.7. Natural Events and Processes 

3.3.7.1. Physical Oceanography 

A detailed description of physical oceanography can be found in Appendix A.2 of the Multisale EIS. 

The following is a summary of the information presented in the Multisale EIS, incorporating new 

information found since publication of the Multisale EIS. 

The Gulf of Mexico is a semi-enclosed, subtropical sea with an area of approximately 1.5 million km2 

(about 600,000 mi2). The main physiographic regions of the Gulf Basin are the continental shelf 

(including the Campeche, Mexican, and U.S. shelves), continental slopes and associated canyons, abyssal 

plains, the Yucatan Channel, and Florida Straits. The depth of the central abyss ranges to approximately 

3,700 m (12,139 ft). The water volume of the entire Gulf is 2.3 million km3

 (over 0.5 million mi3). 

Gulf of Mexico physical oceanographic processes include the Loop Current (LC), Loop Current 

Eddies (LCE’s), Topographic Rossby Waves (TRW’s), and vortex-like and wave-like features underneath 

the LC and LCE’s that interact with bottom topography. Infrequently observed processes include a 

limited number of high-speed current events, at times approaching 100 cm/s (39 in/s), were observed at 

depths exceeding 1,500 m (4,921 ft) in the northern Gulf of Mexico (Hamilton and Lugo-Fernandez, 

2001; Hamilton et al., 2003), and 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 the 

Multisale EIS (USDOI, MMS, 2007b). Generally, current speed in the deepwater Gulf of Mexico has 

been observed to decrease with depth. Mean deep flow around the edges of the Gulf of Mexico circulates 
3-42 Central and Western Gulf of Mexico Multisale Supplemental EIS 

in a cyclonic (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 Gulf of Mexico shelf, and the West Florida shelf are described in 

Appendix A.2 of the Multisale EIS. These currents are primarily wind driven and also influenced by 

riverine outflow. Cold water from deeper offshelf regions moves onto and off the continental shelf by 

cross-shelf flow associated with upwelling and downwelling processes in some locations (Collard and 

Lugo-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. Waves as high as 91 ft (28 m) were measured under Hurricane 

Ivan (Wang et al., 2005). 

General Gulf of Mexico physical oceanography is discussed further and at greater length in Appendix 

A.2 of the Multisale EIS. 

Although physical oceanography of the 181 South Area is consistent with that of adjacent Gulf of 

Mexico regions, it was not specifically covered in the Multisale EIS. Circulation in the 181 South Area 

and adjacent regions is highly influenced by the Loop Current, a circulatory feature of the southeastern 

Gulf of Mexico. Spatial frequency of the LC water mass throughout the Gulf of Mexico is illustrated in 

Figure 3-13. In the 181 South Area, spatial frequency of the LC water mass ranges from 20 to 70 percent 

(Vukovich, 2005), and when the LC is in this area, it is the dominant circulatory feature. Loop Current 

domination of circulation in the 181 South Area has been observed in surface and deep drifter data 

(Weatherly, 2004; Sturges et al., 2001). Preliminary mooring results from the Eastern Gulf of Mexico 

Circulation Study that is being conducted by Evans-Hamilton for MMS agree, and observational data 

collected for this study in 2006-2007 show multiple incidents of currents being affected by the Loop 

Current, LCE’s, or passing storms in the area. Loop Current or LCE intrusions generated the strongest 

upper layer currents. The Loop Current or LCE generated currents also penetrated deeper into the water 

column than storm-induced currents (Cox, in press). 

3.3.7.2. Hurricanes 

Cycles in tropical climate patterns near the equator typically last several decades (20-30 years or even 

longer) (USDOC, NOAA, 2005). As a result, the North Atlantic experiences alternating periods (20-30 

years or even longer) 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. It is assumed hurricane activity from 

1995 to 2007 is representative of an era of above-normal hurricane activity. 

During the 1995-2007 hurricane seasons, 12 hurricanes passed through either the CPA or WPA, 

disrupting OCS oil and gas activity in the Gulf of Mexico. This is an average of about one hurricane per 

year. 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. During 

this 13-year period, 14 hurricanes made landfall along the Gulf Coast from Texas through the Florida 

Panhandle. Five of these hurricanes made landfall in Louisiana. 

The current era of heightened Atlantic hurricane activity began in 1995; therefore, the Gulf of Mexico 

could expect to see a continuation of above-normal hurricane activity during the first quarter to half of the 

40-year analysis period and below-normal activity during the remaining half to three-quarters of the 

40-year analysis period. 
CHAPTER 4 

ENVIRONMENTAL AND SOCIOECONOMIC 

CONSEQUENCES
Environmental and Socioeconomic Consequences 4-3 

4. ENVIRONMENTAL AND SOCIOECONOMIC CONSEQUENCES 

The impacts of 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 (USDOI, MMS, 2007b). 

The Final EIS is hereby incorporated by reference as the Multisale EIS. 

An analysis of the routine, accidental, and cumulative impacts of a CPA or WPA proposed action on 

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 MMS has reexamined those analyses based on the additional 

information available since the publication of the Multisale EIS and the addition of the 181 South Area to 

the proposed CPA sale area. The results of this reexamination are presented in the following chapters. 

4.1. ALTERNATIVE A – THE PROPOSED ACTIONS

4.1.1. Air Quality 

The MMS has reexamined the analysis for air quality presented in the Multisale EIS, based on the 

additional information presented below and the addition of the 181 South Area to the proposed CPA sale 

area. No significant new information was found that would alter the impact conclusion for air quality 

presented in the Multisale EIS. Because the 181 South Area is nearly 130 mi (209 km) from the nearest 

coast, routine activities occurring in the area are expected to have minimal impact on onshore air quality. 

However, there may be temporary and localized impacts to offshore air quality from activity within the 

181 South Area. In addition, no additional large spills or blowouts are projected as a result of the addition 

of the 181 South Area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Emissions of pollutants into the atmosphere from the routine 

activities associated with the proposed actions in the CPA or WPA 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 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 

a proposed action are not expected to have concentrations that would change onshore air quality 

classifications. Total impact from onshore and offshore emissions associated with cumulative activities 

would be significant to the ozone nonattainment areas in southeast Texas and the parishes near Baton 

Rouge, Louisiana. A 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. 

4.1.1.1. Description of the Affected Environment 

The detailed description of air quality in the Gulf of Mexico can be found in Chapter 3.1.1 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since the publication of the Multisale EIS. 

The Clean Air Act (CAA) established the NAAQS; the primary standards are to protect public health 

and the secondary standards are to protect public welfare, as shown in Table 4-1. Effective December 17, 

2006, USEPA revoked the annual PM10 standard of the current 50 μg/m3 and revised the 24-hr PM2.5 from 

the current level of 65 μg/m3

 to 35 μg/m3. The Clean Air Act Amendments of 1990 (CAAA) established 

classification designations based on regional monitored levels of ambient air quality. 
4-4 Central and Western Gulf of Mexico Multisale Supplemental EIS

Attainment 

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 Federal OCS waters’ attainment status is unclassified because there is no provision in the CAA 

for waters outside the seaward boundaries of State waters. Only areas within State boundaries are to be 

classified either attainment, nonattainment, or unclassifiable. Operations west of 87o30' W. longitude fall 

under MMS jurisdiction for enforcement of the Clean Air Act. The OCS waters east of 87o30' W. 

longitude are under the jurisdiction of USEPA. 

Gulf Coast States’ attainment status for criteria pollutants (i.e., carbon monoxide (CO), sulfur dioxide 

(SO2), nitrogen dioxide (NO2), particulate matter (PM), and ozone (O3)) is described in the Multisale EIS 

and has not changed (USEPA, 2007a). Gulf Coast States are in attainment for criteria pollutants except 

for 11 Texas coastal counties and 5 Louisiana coastal parishes that are in nonattainment for ozone 

(USEPA, 2007a). 

In 2008, it is probable that USEPA will propose to lower the 8-hr ozone standard from the current 

85 ppb to between 60 and 80 ppb. Should this change occur, additional Gulf Coast counties/parishes 

would 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 MMS to 

conduct additional air quality studies to more accurately determine the OCS contribution. 

Emission Inventories 

The CAAA requires MMS 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 summary of 

new information available since publication of the Multisale EIS. 

The MMS has completed two air emissions inventory studies for calendar years 2000 (Wilson et al., 

2004) and 2005 (Wilson et al., 2007). These studies estimated emissions for all OCS oil and gas 

production-related sources in the Gulf of Mexico, including non-platform sources, as well as other 

non-OCS-related emissions. The inventories included carbon monoxide (CO), nitrogen oxides (NOx), 

sulfur dioxide (SO2), particulate matter-10 (PM10), PM2.5, and volatile organic compounds (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 is ongoing for calendar year 2008. These 

emissions inventories will be used in air quality modeling to determine potential impacts of offshore 

sources to onshore areas. Therefore, a 2008 emission inventory study has been awarded and more 

inventory data will be collected for 2008. 

In 2008, it is probable that USEPA will propose to lower the 8-hr ozone standard from the current 

85 ppb to between 60 and 80 ppb. Should this change occur, additional Gulf Coast counties/parishes 

would 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 MMS to 

conduct additional air quality studies to more accurately determine the OCS contribution.

4.1.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from the routine activities associated with a CPA or 

WPA proposed action on air quality can be found in Chapters 4.2.2.1.1 and 4.2.1.1.1 of the Multisale EIS, 

respectively. 

The routine activities associated with the proposed action in the CPA or WPA that would potentially 

affect air quality include platform construction and emplacement, platform operations, drilling activities, 

flaring, seismic-survey and support-vessel operations, pipeline laying and burial operations, evaporation 

of volatile petroleum hydrocarbons during transfers and from surface oil slicks, and fugitive emissions. 
Environmental and Socioeconomic Consequences 4-5 

CPA Proposed Action Analysis 

The use of FPSO’s and tankering are projected for a CPA proposed action. Up to 0.49 billion barrels 

(Bbbl), or 37 percent, of oil production is projected to be transported by tankers as a result of a proposed 

action in the CPA. The MMS released a Final EIS on the potential use of FPSO’s in February 2001 

(USDOI, MMS, 2001b). The FPSO EIS concluded emissions from routine operations associated with 

FPSO’s and tankering may result in a long-term, significant impact on air quality at Breton Sound 

Wilderness Area (NWA) due to exceedances of the SO2 standard. The installation of up to five 

geographically dispersed FPSO’s may adversely affect air quality, depending upon the location and 

proximity to shore and one another. In the unlikely event that several FPSO’s would be placed near 

sensitive receptors (e.g., in Mississippi Canyon) in an area with a 50-km (31-mi) radius, significant air 

quality impacts are expected from SO2 emissions. The flaring/venting options for gas disposal could also 

have significant impacts on air quality.

Service-vessel round trips projected for a CPA proposed action 114,000-241,000 trips over the life of 

a proposed action. Based on current service base usage, it is assumed the majority of these trips would 

occur in Louisiana’s coastal waters. Impacts to onshore air quality should be minimal according to the 

Offshore and Coastal Dispersion (OCD) modeling results. 

Up to one new gas processing plant is projected as a result of a proposed action. In addition, a 

proposed action would contribute to the use of existing onshore facilities in Louisiana, Mississippi, and 

Alabama. These supporting onshore facilities would emit air pollutants into the air. However, these 

point-source emissions would be regulated by USEPA or the USEPA-authorized State agency, which 

would require point-source emissions to meet criteria prior to discharge of air pollutants into the 

atmosphere. These direct impacts would be minimal if all existing regulatory requirements are met. 

Portions of the Gulf Coast have ozone levels that exceed the Federal air quality standard, but the 

contribution from proposed activities is very small. Ozone levels are on a declining trend because of air 

pollution control measures that have been implemented by States. This downward trend is expected to 

continue as a result of local as well as nationwide air pollution control efforts. A 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. 

The flaring of natural gas containing hydrogen sulfide (H2S) and the burning of liquid hydrocarbons 

containing sulfur (Chapter 4.1.1.9 of the Multisale EIS) result in the formation of SO2. Flaring of sour 

gas is of concern because it could significantly impact onshore areas, particularly when considering the 

short-duration averaging periods (3 and 24 hr) for SO2. To prevent inadvertently exceeding established 

criteria for SO2 for the 3-hr and 24-hr averaging periods, all incinerating events involving H2S or liquid 

hydrocarbons are evaluated individually during the postlease process. 

The OCD modeling results show that increases in onshore annual average concentrations of NOx, 

SO2, and PM10 are estimated to be less than the maximum increases allowed in the Prevention of 

Significant Deterioration (PSD) Class II Areas. 

Because the 181 South Area is nearly 130 mi (209 km) from the nearest coast, routine activities 

occurring in the area are expected to have minimal impact on onshore air quality. However, there may be 

temporary and localized impacts to offshore air quality from activity within the 181 South Area. 

WPA Proposed Action Analysis 

The use of FPSO’s and tankering are projected for a WPA proposed action. Up to 0.25 Bbbl, or 59 

percent, of oil production is projected to be transported by tankers as a result of a proposed action in the 

WPA. The MMS released a Final EIS on the potential use of FPSO’s in February 2001 (USDOI, MMS, 

2001b). The FPSO EIS concluded emissions from routine operations associated with FPSO’s and 

tankering may result in a long-term, significant impact on air quality at Breton Sound NWA due to 

exceedances of the SO2 standard. The installation of up to five geographically dispersed FPSO’s may 

adversely affect air quality, depending upon the location and proximity to shore and one another. In the 

unlikely event that several FPSO’s would be placed near sensitive receptors (e.g., in Mississippi Canyon) 

in an area with a 50-km (31-mi) radius, significant air quality impacts are expected from SO2 emissions. 

The flaring/venting options for gas disposal could also have significant impacts on air quality. 

Service-vessel round trips projected for a WPA proposed action are 94,000-155,000 trips over the life 

of a proposed action. Based on current service base usage, it is assumed the majority of these trips would 
4-6 Central and Western Gulf of Mexico Multisale Supplemental EIS

occur in Louisiana’s coastal waters. Impacts on onshore air quality should be minimal according to the 

OCD modeling results. 

Up to one new gas processing plant is projected as a result of a WPA proposed action. In addition, a 

WPA proposed action would contribute to the use of existing onshore facilities in Texas, Louisiana, and 

Mississippi. These supporting onshore facilities would emit air pollutants into the air. However, these 

point-source emissions would be regulated by USEPA or the USEPA-authorized State agency, which 

would require point-source emissions to meet criteria prior to discharge of air pollutants into the 

atmosphere. These direct impacts would be minimal if all existing regulatory requirements are met. 

Portions of the Gulf Coast have ozone levels that exceed the Federal air quality standard, but the 

contribution from proposed activities is very small. Ozone levels are on a declining trend because of air 

pollution control measures that have been implemented by States. This downward trend is expected to 

continue as a result of local as well as nationwide air pollution control efforts. A WPA 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. 

The flaring of natural gas containing H2S and the burning of liquid hydrocarbons containing sulfur 

(Chapter 4.1.1.9 of the Multisale EIS) result in the formation of SO2. Flaring of sour gas is of concern 

because it could significantly impact onshore areas, particularly when considering the short-duration 

averaging periods (3 and 24 hr) for SO2. To prevent inadvertently exceeding established criteria for SO2

for the 3-hr and 24-hr averaging periods, all incinerating events involving H2S or liquid hydrocarbons are 

evaluated individually during the postlease process. 

The OCD modeling results show that increases in onshore annual average concentrations of NOx, 

SO2, and PM10 are estimated to be less than the maximum increases allowed in the PSD Class II Areas. 

Summary and Conclusion 

Emissions of pollutants into the atmosphere from the routine activities associated with the proposed 

actions in the CPA or WPA 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. Emissions from proposed action activities are expected to be well within the NAAQS. 

A 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. The OCD modeling 

results show that increases in onshore annual average concentrations of NOx, SOx, and PM10 are estimated 

to be less than the maximum increases allowed in the PSD Class II Areas. 

The CALPUFF modeling results also indicate that all concentrations are below the maximum 

allowable PSD increments, except for 24-hr SO2 and annual NO2 for the Class I Area. The impacts from 

the proposed actions are well within the PSD Class I allowable increment. 

Because the 181 South Area is nearly 130 mi (209 km) from the nearest coast, the area is expected to 

have minimal impact on onshore air quality. A relatively minor amount of additional activity is 

projected; therefore, no additional impacts on offshore air quality are projected as a result of the inclusion 

of the 181 South Area. 

The MMS has reexamined the analysis for air quality presented in the Multisale EIS based on the 

additional information presented above and ongoing studies. No significant new information was found 

that would alter the overall conclusion that impacts on air quality from routine activities associated with a 

CPA or WPA proposed action would be minimal. 

4.1.1.3. Impacts of Accidental Events 

Background/Introduction 

The accidental release of hydrocarbons or chemicals from a proposed action in the CPA or WPA 

would cause the emission of air pollutants. The accidents from oil and gas operations might involve oil 

spills, well blowouts, and burning of an oil spill. The pollutants considered here are NO2, CO, sulphur 

oxides (SOx), VOC’s, PM10, and PM2.5. The pollutant concentration levels are dependent on the 

atmospheric conditions. 
Environmental and Socioeconomic Consequences 4-7 

If the accidental release from blowouts involves high concentrations of H2S, it could result in deaths 

as well as environmental damage. While encounters with H2S during oil and gas operations have caused 

injury and death throughout the U.S., none, to date, have occurred in the GOM region. The H2S 

concentrations in the OCS vary from as low as a fraction ppm to as high as 650,000 ppm. The 

concentrations of H2S found to date are generally greatest in the eastern portion of the CPA. The 

Occupational Safety and Health Administration’s permissible exposure limit for H2S is 20 ppm, which is 

30 times lower than the “immediately dangerous to life and health” of 100 ppm set by the National 

Institute for Occupational Safety and Health. At about 500-700 ppm, loss of consciousness and possible 

death can occur in 30-50 minutes. H2S is a toxic gas; at lower concentrations, it is readily recognized by 

the “rotten egg” smell. 

The following information is a summary of the impact analysis incorporated by reference from 

Chapter 4.4.1 of the Multisale EIS. 

CPA Proposed Action Analysis 

The accidental release of hydrocarbons or chemicals from a CPA proposed action would cause the 

emission of air pollutants. Some of these pollutants are precursors to ozone, which is formed by complex 

photochemical reactions in the atmosphere. Accidents, such as oil spills and blowouts, are a source of 

emissions related to OCS operations. Typical emissions from OCS accidents consist of hydrocarbons; 

only fires produce a broad array of pollutants, including all NAAQS-regulated primary pollutants. The 

criteria pollutants considered here are NO2, CO, SOx, VOC, PM10, and PM2.5. 

Oil from the 181 South Area will likely be heavier oil than oil typically found in shallow water. 

Heavier oil is more likely to emulsify; therefore, the contribution of oil-spill emissions to the total VOC 

emission would be smaller than the emission given in the Multisale EIS, about 0.5 percent or less. 

In-situ burning of a spill results in emissions of NO2, SO2, CO, and PM10, and would generate a 

plume of black smoke. However, it was found that during the burn, CO, SO2, and NO2 were measured 

only at background levels and were frequently below detection levels (Fingas et al., 1995). 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. 

It has been estimated that 2-3 blowouts could occur from activities resulting from a proposed action. 

An additional 9-12 wells per proposed CPA sale are projected to be drilled as a result of the addition of 

the 181 South Area. Based on the blowout rate of 6 per 1,000 well starts, no additional blowouts are 

projected as a result of the addition of the 181 South Area. H2S is a toxic gas, and accidents involving 

high concentrations of H2S from blowouts could result in deaths as well as environmental damage. 

WPA Proposed Action Analysis 

The accidental release of hydrocarbons or chemicals from a WPA proposed action would cause the 

emission of air pollutants. Some of these pollutants are precursors to ozone, which is formed by complex 

photochemical reactions in the atmosphere. Accidents, such as oil spills and blowouts, are a source of 

emissions related to OCS operations. Typical emissions from OCS accidents consist of hydrocarbons; 

only fires produce a broad array of pollutants, including all NAAQS-regulated primary pollutants. The 

criteria pollutants considered here are NO2, CO, SOx, VOC, PM10, and PM2.5. 

In-situ burning of a spill results in emissions of NO2, SO2, CO, and PM10, and would generate a 

plume of black smoke. However, it was found that during the burn, CO, SO2, and NO2 were measured 

only at background levels and were frequently below detection levels (Fingas et al., 1995). 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. 

It has been estimated that 1-2 blowouts could occur from activities resulting from a WPA proposed 

action. H2S is a toxic gas, and accidents involving high concentrations of H2S from blowouts could result 

in deaths as well as environmental damage. 

Summary and Conclusion 

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 
4-8 Central and Western Gulf of Mexico Multisale Supplemental EIS

as environmental damage. Other emissions of pollutants into the atmosphere from accidental events as a 

result of a CPA or WPA proposed action are not projected to have significant impacts on onshore air 

quality because of the prevailing atmospheric conditions, emissions height, emission rates, and the 

distance of these emissions from the coastline. These emissions are not expected to have concentrations 

that would change onshore air quality classifications. 

The addition of the 181 South Area would not significantly increase the risk of impacts to air quality 

from accidental events. No additional blowouts are projected as a result of the addition of the 181 South 

Area. Heavier oil from the 181 South Area is more likely to emulsify; therefore, the contribution of oilspill emissions to the total VOC emission would be smaller than the emission given in the Multisale EIS, 

about 0.5 percent or less. 

4.1.1.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts on air quality can be found in Chapter 4.5.1 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS. This 

cumulative analysis summary considers OCS and non-OCS activities that could occur and adversely 

affect onshore air quality and Breton National Wilderness area from OCS sources during the 40-year 

analysis period. 

The activities for the OCS Program include the exploration, delineation, and development wells; 

platform installation; and service-vessel trips. 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 a recent 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., in preparation). The OCS contribution to the air quality problem in 

the coastal areas is small, but the total impact from onshore and offshore emissions would be significant 

to the ozone nonattainment areas in southeast Texas and the parishes near Baton Rouge, Louisiana. 

Other onshore emission sources include power generation, industrial processing, manufacturing, 

refineries, commercial and home heating, and motor vehicles. 

Impacts from oil spills for the cumulative case would be similar to those for the proposed 2007-2012 

leasing program. Impacts from individual spills would be localized and temporary. 

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. 

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. 

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 heights, and the resulting pollutant concentrations. Onshore impacts on air 

quality from emissions from OCS activities are estimated to be within Class II PSD 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., in preparation). 

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 air pollution control efforts. 
Environmental and Socioeconomic Consequences 4-9 

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 actions (as analyzed in Chapters 4.2.1.1.1 and 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. Portions of the Gulf Coast have ozone levels that exceed the Federal air quality 

standard, but the incremental contribution from the proposed actions are very small. The cumulative 

contribution to visibility impairment from a proposed action is also expected to remain very small. A 

proposed action, including the 181 South Area, 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. 

4.1.2. Water Quality 

For the purposes of this SEIS, 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 marine waters for the following discussion. 

Coastal waters, as defined by MMS, include all the bays and estuaries from the Rio Grande River to the 

Florida Bay (Figure 4-1). Marine water as defined in this document includes 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 MMS has reexamined the analysis for water quality presented in the Multisale EIS, based on the 

additional information presented below and the addition of the 181 South Area to the proposed CPA sale 

area. No significant new information was found that would alter the impact conclusion for water quality 

presented in the Multisale EIS. The 181 South Area is located nearly 130 mi (209 km) from the nearest 

coast and is projected to result in a relatively minor amount of additional activity; therefore, no additional 

impacts on water quality are projected as a result of the inclusion of the 181 South Area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Impacts from routine activities associated with a proposed action 

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

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

maintenance, discharges of bilge and ballast water from support vessels, and run-off from shore-based 

facilities. Marine 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, marine water impacts result from supply and 

service-vessel bilge and ballast water discharges. 
4-10 Central and Western Gulf of Mexico Multisale Supplemental EIS

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

waters. Larger spills, however, could impact water quality in coastal waters. Accidental chemical spills, 

release of SBF, and blowouts would have temporary localized impacts on water quality. 

The activity associated with a 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, add a small increase 

to the anticipated impacts. Furthermore, the vessel traffic and related discharges associated with a 

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 marine waters. 

4.1.2.1. Coastal Waters 

4.1.2.1.1. Description of the Affected Environment 

A detailed description of water quality in coastal marine waters can be found in Chapter 3.1.2.1 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since the publication of the Multisale EIS. Because the 181 South 

Area is nearly 130 mi (209 km) from the nearest coast, the area is not applicable to this coastal water 

quality discussion. 

Along the Gulf Coast lies one of the most extensive estuary systems in the world, which extends from 

the Rio Grande River to Florida Bay (Figure 4-1). Estuaries represent a transition zone between the 

freshwater of rivers and the higher salinity waters offshore. Estuaries provide habitat for plants, animals, 

and humans. Marshes, mangroves, and seagrasses surround the Gulf Coast estuaries and provide food 

and shelter for shorebirds, migratory waterfowl, fish, invertebrates (e.g., shrimp, crabs, and oysters), 

reptiles, and mammals. A search was conducted for new information related to coastal water quality 

published since completion of the Multisale EIS. An Internet search for relevant scientific journal 

articles was conducted using a publicly available search engine. In addition, the websites for Federal and 

State agencies, and the Gulf of Mexico Alliance were reviewed for newly released information. The Gulf 

of Mexico Alliance, a partnership between the Gulf States, was organized in 2005 as a collaborative 

means to solve regional problems to implement the U.S. Ocean Action Plan. 

Although new research and ongoing monitoring information is continuously available from many 

sources about various water quality parameters in the Gulf of Mexico, the new information located was 

related to issues that have already been presented in the Multisale EIS and are summarized in this SEIS; 

therefore, it was not incorporated (Ache, written communication, 2007; USEPA, 2007d-e; LADEQ, 

2007a; Texas Commission on Environmental Quality, 2007). 

Gulf Coast water quality was given a fair rating in the National Coastal Condition Report II (USEPA, 

2004a). Estuaries with a poor water quality rating comprised 9 percent of the Gulf Coast estuaries, while 

those ranked fair to poor comprised 55 percent. In Texas and Louisiana, estuaries that received a poor 

water quality rating in the report had low water clarity and high dissolved inorganic phosphorus in 

comparison with levels expected for that region. In Florida and Mississippi estuaries, the factors that 

contributed to a poor water quality rating were low water clarity and high chlorophyll relative to expected 

levels. Chlorophyll is one of several symptoms of eutrophic conditions. Dissolved oxygen levels in Gulf 

Coast estuaries are good and less than 1 percent of bottom waters exhibit hypoxia (dissolved oxygen 

below 2 milligrams (mg) per liter (L)). However, areas of low dissolved oxygen form around Chandeleur 

and Breton Sounds, some shoreline regions of Lake Pontchartrain, and small estuaries associated with 

Galveston Bay, Mobile Bay, and Mississippi Sound. 

In June 2007, USEPA issued the National Estuary Program Coastal Condition Report (USEPA, 

2007f). This report was the third in a series of coastal environmental assessments. However, the first two 

reports covered all U.S. coastal waters, whereas this report assessed just those estuaries in the National 

Estuary Program. The report described conditions at four Gulf Coast estuaries near the MMS CPA and 

WPA, Mobile Bay, Barataria Terrebonne Estuary, Galveston Bay, and Coastal Bend Bays and Estuaries 

(Corpus Christi Bay Estuary). A water quality rating was determined and Coastal Bend Bays, Barataria 

Terrebonne Estuary, and Mobile Bay were rated fair, but Galveston Bay was rated poor due to elevated 

dissolved phosphorus and higher turbidity. 
Environmental and Socioeconomic Consequences 4-11 

Sediments can serve as a sink for contaminants that were originally transported via water in either 

dissolved or particulate form or via atmospheric deposition. Sediments may contain pesticides, metals, 

and organics. The sediments of Gulf Coast estuaries were ranked as fair. Metals were the type of 

sediment contamination found to most frequently exceed toxicity guidance. 

Hurricanes Katrina and Rita caused extensive flooding and damage to industrial and municipal waste 

facilities and to residential and commercial structures. Industrial and agricultural chemicals, household 

chemicals, sewage, oil, and nutrients contained in the flood waters had the potential to degrade water 

quality in coastal areas. Testing following the storm identified low levels of fecal coliform in Mississippi 

Sound and Louisiana coastal waters. Very few toxics were detected in estuarine or coastal waters 

resulting from the hurricanes (USEPA, 2006a). 

4.1.2.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on coastal water quality is presented in Chapters 4.2.2.1.2.1 and 4.2.1.1.2.1 of the 

Multisale EIS, respectively. Because the 181 South Area is nearly 130 mi (209 km) from the nearest 

coast, the area is not applicable to this coastal water quality discussion. 

The routine activities associated with a proposed action that would impact coastal water quality 

include installation of pipelines in coastal waters, maintenance dredging of navigational canals, service 

vessel discharges, and nonpoint-source runoff from onshore facilities. 

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 

states, for the nearshore sections of OCS pipelines, State permits for constructing pipelines would require 

that turbidity impacts be mitigated through the use of turbidity screens and other turbidity reduction or 

confinement equipment. Maintenance dredging will also 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. The types of discharges and regulations were 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. The discharges would affect 

the water quality locally. Estimates of the volume of bilge and ballast water that may be discharged are 

not available. 

Supporting onshore facilities 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 the USEPA, the agency responsible for coastal water 

quality, or the USEPA-authorized State agency. The USEPA 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. Data are 

not available to make estimates of the impact from this type of discharge. 

CPA Proposed Action Analysis 

The routine activities associated with a CPA proposed action that would impact coastal water quality 

include installation of pipelines in coastal waters, maintenance dredging of navigational canals, servicevessel discharges, and nonpoint-source runoff from onshore facilities. 

One to three new pipelines are projected to be installed in State waters as a result of a CPA proposed 

action. These new installations could temporarily increase the local total suspended solids in the water. 

The 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 navigational channels are expected to be dredged as a result of a CPA proposed action; 

however, a CPA proposed action would contribute to maintenance dredging of existing navigational 
4-12 Central and Western Gulf of Mexico Multisale Supplemental EIS

canals. Maintenance dredging would temporarily increase turbidity levels in the vicinity of the dredging 

and disposal of materials. 

Service-vessel round trips projected for a CPA proposed action are 119,000-241,000 trips over the 

life of a proposed action. Based on current service base usage, it is assumed the majority of these trips 

would occur in Louisiana’s coastal waters. Allowable bilge and ballast water discharges would affect the 

water quality locally. Impacts should be minimal as long as existing regulations are met. 

Up to one new gas processing plant is projected as a result of a CPA proposed action. In addition, a 

CPA proposed action would contribute to the use of existing onshore facilities in Texas, Louisiana, 

Mississippi, and Alabama. These supporting onshore facilities would discharge into local wastewater 

treatment plants and waterways during routine operations. These point-source discharges would be 

regulated by the USEPA or the USEPA-authorized State agency, which would require point-source 

discharges to meet criteria prior to discharge. These direct impacts would be minimal if all existing 

regulatory requirements are met. Indirect impacts would occur from nonpoint-source runoff, such as 

rainfall, which has drained from infrastructure such as a public road or parking lot, and may contribute 

hydrocarbon and trace-metal pollutants. These indirect impacts would be minimal and difficult to discern 

from other sources. 

WPA Proposed Action Analysis 

The routine activities associated with a WPA proposed action that would impact coastal water quality 

include installation of pipelines in coastal waters, maintenance dredging of navigational canals, service 

vessel discharges, and nonpoint-source runoff from onshore facilities. 

One to three new pipelines are projected to be installed in State waters as a result of a WPA proposed 

action. These new installations could temporarily increase the local total suspended solids in the water. 

The 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 navigational channels are expected to be dredged as a result of a WPA proposed action; 

however, a WPA proposed action would contribute to maintenance dredging of existing navigational 

canals. Maintenance dredging would temporarily increase turbidity levels in the vicinity of the dredging 

and disposal of materials. 

Service-vessel round trips projected for a WPA proposed action are 94,000-155,000 trips over the life 

of a proposed action. Based on current service base usage, it is assumed the majority of these trips would 

occur in Texas’ coastal waters. Allowable bilge and ballast water discharges would affect the water 

quality locally. Impacts should be minimal as long as existing regulations are met. 

Up to one new gas processing plant is projected as a result of a WPA proposed action. In addition, a 

WPA proposed action would contribute to the use of existing onshore facilities in Texas, Louisiana, 

Mississippi, and Alabama. These supporting onshore facilities would discharge into local wastewater 

treatment plants and waterways during routine operations. These point-source discharges would be 

regulated by the USEPA or the USEPA-authorized State agency, which would require point-source 

discharges to meet criteria prior to discharge. These direct impacts would be minimal if all existing 

regulatory requirements are met. Indirect impacts would occur from nonpoint-source runoff, such as 

rainfall, which has drained from infrastructure such as a public road or parking lot, and may contribute 

hydrocarbon and trace-metal pollutants. These indirect impacts would be minimal and difficult to discern 

from other sources. 

Summary and Conclusion 

The routine activities associated with a CPA or WPA proposed action that would impact coastal water 

quality include installation of pipelines in coastal waters, maintenance dredging of navigational canals, 

service-vessel discharges, and nonpoint-source runoff from onshore facilities. Turbidity impacts from 

pipeline installation and maintenance dredging would be temporary and localized. Impacts from service 

vessel and onshore facility discharges would be minimal if all existing regulatory requirements are met. 

The MMS has reexamined the analysis for coastal water quality presented in the Multisale EIS, based 

on the additional information presented above. No significant new information was found that would 

alter the overall conclusion that impacts on coastal water quality from routine activities associated with a 

CPA or WPA proposed action would be minimal. A small increase in vessel traffic would result from the 
Environmental and Socioeconomic Consequences 4-13 

inclusion of the 181 South Area. This small increase in vessel traffic would have minimal impact on 

coastal water quality. 

4.1.2.1.3. Impacts of Accidental Events 

Accidental events associated with a CPA or WPA proposed action that could impact coastal water 

quality include spills of oil and refined hydrocarbons, spills of chemicals or drilling fluids, and collisions 

that result in spills. 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., movement of oil and rate 

and nature of weathering), which, in turn, depends on oceanographic and meteorological conditions at the 

time. The various fractions within the crude behave differently in water. The lighter ends 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. 

The National Academy of Sciences (NRC, 2003) and Boesch and Rabalais (1987) have reviewed the 

fate and effects of spilled oil. In general, the impacts to water quality are greatest when a spill occurs in a 

confined area where it persists for a long period of time. In an environment where the oil can be 

dispersed or diluted, the impacts are reduced. Spills of opportunity are few and difficult to sample on 

short notice. The evaluation of impacts from a large spill on water quality is based on qualitative and 

speculative information. 

CPA and WPA Proposed Action Analysis 

Oil Spills 

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. Chapter 4.3.1.7 of the Multisale EIS presents the 

risk of coastal spills associated with a proposed action. 

The ability of coastal waters to assimilate spilled oil is affected by the shallowness of the 

environment. Large volumes of water are not available to dilute suspended oil droplets and dissolved 

constituents. 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 contains toxic aromatic compounds such as benzene, toluene, xylenes, naphthalenes, 

and polynuclear aromatic hydrocarbons, which are soluble to some extent in water. The effect of these 

compounds on water quality depends on the circulation in the coastal environment, the composition of the 

spilled oil, and the length of time the oil is in contact with the water. 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. 

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 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 for time scales of hours to days. 

Collisions 

A collision may result in the spillage of crude oil, refined products such as diesel, or chemicals. 

Diesel is the type of refined hydrocarbon spilled most frequently as the result of a collision. Minimal 

impacts result from a spill since diesel is light and will evaporate and biodegrade within a few days. 
4-14 Central and Western Gulf of Mexico Multisale Supplemental EIS

Since collisions occur infrequently, the potential impacts to marine water quality are not expected to be 

significant. 

Summary and Conclusion 

Smaller spills (<1,000 bbl) are not expected to significantly impact water quality in coastal waters. 

Larger spills, however, could impact water quality in coastal waters. 

4.1.2.1.4. Cumulative Impacts 

A detailed description of cumulative impacts upon water quality can be found in Chapter 4.5.2 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS. 

The Gulfwide, OCS-related cumulative activities that would impact coastal water quality include the 

installation of pipelines in coastal waters, maintenance dredging of navigational canals, service-vessel 

discharges, and nonpoint-source runoff from onshore facilities. Existing and future non-OCS activities 

occurring in the Gulf of Mexico that would affect coastal water quality include the transportation of oil, 

gas, and commodities, and the activities of other Federal agencies. Discharges from domestic and foreign 

commercial and military vessels would adversely affect the quality of water in the Gulf of Mexico. 

The water quality of coastal environments will be affected by the cumulative input of hydrocarbons 

and trace metals from activities that support oil and gas extraction. These activities include bilge water 

from service vessels and point- and nonpoint-source discharges from supporting infrastructure. 

Discharges from service vessels are regulated by the USCG to minimize cumulative impacts. The 

USEPA 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 will adversely impact the overall water quality of the region. 

Inflows from rivers such as the Mississippi River also influence coastal water quality. When inflows 

transport constituents that degrade water quality, such as suspended sediments or nutrients, adverse 

effects can result. Such discharges impact water quality in the Gulf and, during periods of water-column 

stratification, have influenced the development of an extensive hypoxic zone. In comparison with the 

Mississippi and Atchafalaya Rivers’ input, it is estimated that produced water contributes from 0.02 to 0.2 

percent of the nitrogen to the hypoxic zone (Veil et al., 2005). 

Dredging and channel erosion can add to the suspended load of local waterways. Support vessels as 

well as other activities such as commercial fishing and shipping use the waterways. Specific information 

concerning the direct impacts from OCS activities is not available to evaluate the degradation of water 

quality in the waterways. However, MMS assumes that the existing water quality programs in each State 

would identify OCS-related activities that degrade water quality and correct the problem. 

Accidental releases of oil or chemicals would degrade water quality during the spill and after until the 

spill is either cleaned up or natural processes disperse the spill. Chapter 4.5.2.1 of the Multisale 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. As occurred in 2005, damage to infrastructure would delay response to the spills, 

and flooding may increase the dispersion of the spills. 

Summary and Conclusion 

Water quality in coastal waters would be impacted by sediment resuspension due to pipeline 

installation, maintenance dredging of navigational canals, discharges related to supply vessel usage, and 

shore-based infrastructure associated with a proposed action. The Gulf of Mexico coastal water is 

additionally impacted by numerous diverse factors including river inflows, urbanization, agricultural 

practices, municipal wastes discharges, and coastal industry. The impacts resulting from a proposed 

action are a small addition to the cumulative impacts on the coastal waters of the Gulf. The incremental 

contribution of the routine activities associated with a proposed action to the cumulative impacts to 

coastal water quality is not expected to be significant as long as all regulations are followed. The 

incremental contribution of accidents is also small. Using a rough estimate, OCS sources comprise about 
Environmental and Socioeconomic Consequences 4-15 

10 percent (40-50) of small coastal spills that occur each year in the Gulf of Mexico. It is important to 

note that the impacts of a spill are determined by factors such as season and location, in addition to size. 

4.1.2.1. Marine Waters 

4.1.2.1.1. Description of the Affected Environment 

A detailed description of water quality in marine waters can be found in Chapter 3.1.2.2 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since the publication of the Multisale EIS. 

The marine water within the area of interest can be divided into three regions: the continental shelf 

west of the Mississippi River, the continental shelf east of the Mississippi River, and deep water (>400 m 

or >1,312 ft). For this discussion, the continental shelf includes the upper slope to a water depth of 400 m 

(1,312 ft). While the various parameters measured to evaluate water quality do vary in marine waters, 

one parameter, pH, does not. The buffering capacity of the marine system is controlled by carbonate and 

bicarbonate, which maintain the pH at 8.2. 

A search was conducted for new information related to marine water quality published since 

completion of the Multisale EIS. An Internet search for relevant scientific journal articles was conducted 

using a publicly available Internet search engine. In addition, the websites for Federal agencies, and the 

Gulf of Mexico Alliance were reviewed for newly released information. The Gulf of Mexico Alliance, a 

partnership between the Gulf States, was organized in 2005 as a collaborative means to solve regional 

problems to implement the U.S. Ocean Action Plan. 

Continental Shelf West of the Mississippi River 

The Mississippi and Atchafalaya Rivers are the primary sources of freshwater, sediment, and 

pollutants to the continental shelf west of the Mississippi (Murray, 1997). The drainage basin that feeds 

the rivers covers 55 percent of the contiguous U.S. A turbid surface layer of suspended particles is 

associated with the freshwater plume from these rivers. A nepheloid layer composed of suspended clay 

material from the underlying sediment is always present on the shelf. 

During summer months, the low-salinity water from the Mississippi River spreads out over the shelf, 

resulting in a stratified water column. While surface oxygen concentrations are at or near saturation, 

hypoxia (dissolved oxygen less than 2 mg/L), is observed in bottom waters during the summer months 

(Figure 3-3 of the Multisale EIS). 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. 

New information is available on the hypoxic zone and efforts to reduce its size. In August 2007, the 

zone measured 20,500 km2 (7,900 mi2

), the third largest measured area since monitoring began in 1985 

(LUMCON, 2007). A reassessment of hypoxia in the northern Gulf of Mexico was begun in 2005. An 

independent panel, the Science Advisory Board, was convened to evaluate new studies and nutrient 

control actions. The Panel Draft Advisory Report (USEPA, 2007g) points out that the goal to reduce the 

size of the zone by 2015 may take longer than anticipated and that the Nation’s push towards corn-based 

ethanol production will alter agricultural practices, which, in turn, could increase rather than decrease 

nutrients in river water that contribute to hypoxia. A second area of hypoxia was found off the Texas 

coast in the summer of 2007. Following heavy inland rains, a 4,530-km2

 (1,750-mi2) area of hypoxia was 

discovered off the Brazos River (Graczyk, 2007). 

Continental Shelf East of the Mississippi River 

Water quality on the continental shelf from the Mississippi River Delta to Tampa Bay is influenced 

by river discharge, run-off from the coast, and eddies from the Loop Current. The outflow of the 

Mississippi River generally extends only 45 mi (75 km) to the east of the river mouth (Vittor and 

Associates, Inc., 1985) except under extreme flow conditions. The Loop Current intrudes in irregular 

intervals onto the shelf, and discharges from the Mississippi River can be easily entrained in the Loop 

Current. Hypoxia is rarely observed on the Mississippi-Alabama shelf, although low dissolved oxygen 
4-16 Central and Western Gulf of Mexico Multisale Supplemental EIS

values of 2.93-2.99 mg/L were observed during the Mississippi-Alabama Marine Ecosystem Study 

(MAMES) and northeastern Gulf of Mexico (NEGOM) cruises (Brooks, 1991; Jochens et al., 2002). 

The Mississippi-Alabama shelf sediments are strongly influenced by fine sediments and nutrients 

discharged from the Mississippi River. The shelf area is characterized by a bottom nepheloid layer and 

surface lenses of suspended particulates that originate from river outflow. The West Florida Shelf has 

very little sediment input with primarily high-carbonate sands offshore and quartz sands nearshore. The 

water clarity is higher towards Florida, where the influence of the Mississippi River outflow is rarely 

observed. 

A 3-year, large-scale marine environmental baseline study conducted from 1974 to 1977 in the 

Eastern Gulf of Mexico resulted in an overview of the Mississippi, Alabama, and Florida (MAFLA) OCS 

environment to 200 m (656 ft) (SUSIO, 1977; Dames and Moore, 1979). A decade later, the continental 

shelf off Mississippi and Alabama was revisited (Brooks, 1991). The source of petroleum hydrocarbons 

and terrestrial plant material is the Mississippi River. The SAIC (1997) summarized information about 

water quality on the shelf from DeSoto Canyon to Tarpon Springs and from the coast to a 200-m (656-ft) 

water depth. Several small rivers and the Loop Current are the primary influences on water quality in this 

region. Because there is relatively little onshore development in this area, the waters and surface 

sediments are uncontaminated. The Loop Current flushes the area with clear, low-nutrient water. 

The NEGOM chemical oceanography and hydrography study (1997-2000) noted that interannual 

variation in the parameters measured outweighed seasonal variation due to the influence of offshelf 

circulation features and interannual variation in wind (Jochens et al., 2002). The highest chlorophyll a

amounts measured in near-surface water were located in the areas influenced by the Mississippi and 

Apalachicola Rivers. Hypoxia was not observed on the shelf during the 3 years of the study. 

Although new research and ongoing monitoring information is continuously available from many 

sources about various water quality parameters in the Gulf of Mexico, the new information located was 

related to issues that have already been presented in the Multisale EIS and are summarized in this SEIS; 

therefore, it was not incorporated (Ache, written communication, 2007; USEPA, 2007d-e; LADEQ, 

2007a; Texas Commission on Environmental Quality, 2007). 

Deep Water 

Limited information is available on the deepwater environment. Water at depths greater than 1,400 m 

(4,593 ft), including the 181 South Area, is relatively homogeneous with respect to temperature, salinity, 

and oxygen (Nowlin, 1972; Pequegnat, 1983; Gallaway et al., 1988). The major source of oxygen in deep 

waters is the transport of oxygen-rich water through the Yucatan Channel. Available data indicate that 

oxygen replenishment is adequate to balance oxygen consumption in deep waters; however, localized 

areas of depleted oxygen could exist as the result of natural conditions or anthropogenic activities such as 

the discharge from oil and gas activities (Jochens et al., 2005). 

Limited analyses of trace metals and hydrocarbons for the water column and sediments exist (Trefry, 

1981; Gallaway et al., 1988). The MMS recently completed a field study of four drilling sites located in 

water depths of 1,033-1,125 m (3,389-3,691 ft) (CSA, 2006), results of which are summarized in Chapter 

3.1.2.2 of the Multisale EIS. The sampling design called for before and after exploratory or development 

drilling and captured the drilling-related changes that occur in sediments and sediment pore water. 

Hydrocarbon seeps are extensive throughout the continental slope and contribute hydrocarbons to the 

surface sediments and water column, especially in the Central Gulf of Mexico (Sassen et al., 1993a and 

b). MacDonald et al. (1993) observed 63 individual seeps using remote sensing and submarine 

observations. Estimates of the total volume of seeping oil vary widely from 29,000 bbl/yr (MacDonald, 

1998a) to 520,000 bbl/yr (Mitchell et al., 1999). 

Although new research and ongoing monitoring information is continuously available from many 

sources about various water quality parameters in the Gulf of Mexico, the new information located was 

related to issues that have already been presented in the Multisale EIS and are summarized in this SEIS; 

therefore, it was not incorporated (Ache, written communication, 2007; USEPA, 2007d-e; LADEQ, 

2007a; Texas Commission on Environmental Quality, 2007). 
Environmental and Socioeconomic Consequences 4-17 

4.1.2.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the potential impacts from routine activities associated with a CPA or WPA 

proposed action on marine water quality is presented in Chapters 4.2.2.1.2.2 and 4.2.1.1.2.2 of the 

Multisale EIS, respectively. 

The routine activities associated with a proposed action that would impact marine water quality 

include discharges of drilling muds and cuttings during the drilling of exploration and development wells, 

discharges during a workover, structure installation and removal, discharges during production, pipeline 

installation, and service-vessel discharges including bilge and ballast water and discharges from the 

marine sanitation device. 

The drilling of exploratory and development wells results in the discharges of drilling fluids, called 

“muds,” and cuttings. Muds are the weighted fluids used to lubricate the drill bit, and cuttings are the 

ground rock displaced from the well. The USEPA regulates the discharge of muds and cuttings to the 

Gulf of Mexico. Water-based muds and cuttings may be discharged. Synthetic-based drill fluids are 

manufactured hydrocarbons and have been increasingly used over the past 20 years because they perform 

well in deep water and reduce drilling time. The USEPA promulgated Effluent Limitations Guidelines, 

and the discharge of cuttings wetted with SBF was incorporated into the general NPDES permits of both 

Region 4 and Region 6. The SBF may not be discharged; it is recycled. 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. The SBF-wetted cuttings do not disperse as readily in water and descend in clumps to 

the seafloor. The SBF on the wetted cuttings gradually breaks down and may deplete the oxygen level at 

the sediment water interface as it degrades. Characteristics of drilling muds and cuttings, the impacts of 

discharge, and regulatory controls are discussed in greater detail in Chapter 4.1.1.4.1 of the Multisale EIS. 

Additional chemical products are used to “workover” or treat a well. A wide range of products fall 

into this category. Chemicals include 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 are just some examples. Some additives remain in the oil or gas 

phase while others remain in the produced water where they are diluted or neutralized. The USEPA 

regulates the discharge to waters of the Gulf of Mexico. 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. 

During structure installation and removal, impacts from anchoring, mooring, pipeline and flowline 

emplacement, and placement of subsea production structures may occur. The disturbance of the seafloor 

will increase turbidity in the surrounding water. Additional information on bottom-area disturbance is 

available in Chapter 4.1.1.3.2.1 of the Multisale EIS. 

During production, produced water is brought up from the hydrocarbon-bearing strata along with the 

oil and gas that is generated. It may contain dissolved solids in higher concentrations than Gulf waters, 

metals, hydrocarbons, and naturally-occurring radionuclides. Produced water may contain residuals from 

the treatment completion or workover compounds used, as well as additives used in the oil/water 

separation process. Produced water is treated before discharge to meet the NPDES discharge 

requirements. 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 installation of a pipeline would result in a temporary increase in turbidity. In waters <200 ft 

(61 m), MMS required burial to a depth of at least 3 ft (1 m) below the mudline. Jetting to dig the trench 

for the pipeline disturbs the bottom sediments and results in a temporary increase in turbidity. In deeper 

waters the pipeline is laid upon the seafloor. A description of the pipeline installation is provided in 

Chapter 4.1.1.8.1 of the Multisale EIS. 

Service-vessel discharges include bilge and ballast water and sanitary waste. Bilge water is often 

contaminated with oil. Regulations that set limits for oil in bilge water will minimize the impact to water 

quality. Ballast water is less likely to contain oil but is subject to the same limits. The marine sanitation 

device is required to treat sanitary waste generated on the service vessel so that surrounding water will not 

be impacted by possible bacteria or viruses in the waste. The discharge of treated sanitary waste will still 
4-18 Central and Western Gulf of Mexico Multisale Supplemental EIS

contribute some 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. 

CPA Proposed Action Analysis 

The routine activities associated with a CPA proposed action that would impact marine water quality 

include discharges of drilling muds and cuttings during drilling of exploration and development wells, 

discharges during a workover, structure installation and removal, discharges during production, and 

pipeline installations and discharges from service vessels. These activities in the 181 South Area would 

have the same impact as in the deep water of the rest of the CPA. 

Water-based drilling fluids and cuttings and SBF-wetted cuttings will increase turbidity in the water 

column and change the composition and grain size of sediments in the area of the seafloor where 

discharges accumulate. The inclusion of the 181 South Area is projected to result in the drilling of a total 

of 67-99 exploratory and delineation wells and 337-477 development wells. The MMS expects that 80 

percent of the wells will be drilled with SBF and that 20 percent will be drilled with WBF. A volume of 

213,892-472,265 bbl of cuttings wetted with SBF is projected. A volume of 160,800-343,800 bbl and 

557,815-1,111,620 bbl of water-based cuttings and WBF, respectively, are projected to be discharged. 

Additional chemicals that could intermingle with produced water and be discharged are used during 

workover activities. The 181 South Area is projected to result in 2,051-2,898 workovers and other well 

activities. 

Bottom disturbances and increased water turbidity result from structure installation and removal. 

The installation of 28-40 structures and the removal of 24-36 structures are projected to result from a 

proposed action in the CPA. This includes the installation and removal of up to one structure associated 

with the addition of the 181 South Area. 

Discharges associated with production include produced water, the water that comes up the wellbore 

with the oil, and sanitary and domestic waste discharges. These wastes must be treated prior to discharge 

so that impacts to water will be negligible. The scenario projects that 337-477 development wells will be 

drilled, of which 293 14, or 87 percent, are expected to produce. The average volume of produced water 

per well is 0.084 MMbbl per year. The concentration of oil and grease in produced water is 29 mg/L and 

the specific gravity of the oil is 0.9. Using these assumptions, the volume of oil discharged to the Gulf 

via produced-water discharge was estimated to be 793-1,123 bbl per year in the CPA. 

Ballast and bilge water and sanitary waste are generated during service-vessel trips. Approximately 

119,000-241,000 service-vessel round trips are projected to result from a proposed action in the CPA, 

including activities associated with the addition of the 181 South Area. 

The installation of pipelines results in bottom disturbances. The inclusion of the 181 South Area is 

projected to result in the installation of an additional 130-2,075 km (81-1,289 mi) of pipeline. 

WPA Proposed Action Analysis 

The routine activities associated with a WPA proposed action that would impact marine water quality 

include discharges of drilling muds and cuttings during drilling of exploration and development wells, 

discharges during a workover, structure installation and removal, discharges during production, and 

pipeline installations and discharges from service vessels. 

A WPA proposed action is projected to result in the drilling of a total of 42-66 exploratory and 

delineation wells and 155-221 development wells. The MMS expects that 80 percent of the wells will be 

drilled with SBF and that 20 percent will be drilled with WBF. A description of waste volumes is in 

Chapter 4.2.1.1.2.2 of the Multisale EIS. 

Additional chemicals that could intermingle with produced water and be discharged are used during 

workover activities. A WPA proposed action is projected to result in 945-1,344 workovers and other well 

activities. 

Bottom disturbances and increased water turbidity result for structure installation and removal. A 

WPA proposed action is projected to result in the installation of 28-41 structures and the removal of 

20-31 structures. 

Discharges associated with production include produced water, the water that comes up the wellbore 

with the oil, and sanitary and domestic waste discharges. These wastes must be treated prior to discharge 

so that impacts to water will be negligible. The scenario projects that 155-221 development wells will be 
Environmental and Socioeconomic Consequences 4-19 

drilled, of which 87 percent are expected to produce. The average volume of produced water per well is 

0.084 MMbbl per year. The concentration of oil and grease in produced water is 29 mg/L and the specific 

gravity of the oil is 0.9. Using these assumptions, the volume of oil discharged to the Gulf via producedwater discharge was estimated to be 363-516 bbl oil per year in the WPA. Greater volumes of produced 

water are associated with oil rather than gas production. Therefore, greater volumes of oil will likely be 

discharged in the oil-producing areas of the WPA than in the gas-producing areas. 

Ballast and bilge water and sanitary waste are generated during service-vessel trips. A WPA 

proposed action is projected to result in 94,000-155,000 service-vessel round trips. 

The installation of pipelines results in bottom disturbances. A WPA proposed action is projected to 

result in the installation of 130-760 km (81-472 mi) of pipeline. 

Summary and Conclusion 

During exploratory activities, the primary impacting sources to marine 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 include water with oil 

concentration of <15 ppm. Impacts to marine waters from routine activities associated with a proposed 

action in the CPA, including the 181 South Area, and WPA should be minimal as long as regulatory 

requirements are followed. 

4.1.2.1.3. Impacts of Accidental Events 

Accidental events associated with a CPA or WPA proposed action in the that could impact marine 

water quality include spills of oil and refined hydrocarbons, spills of chemicals or drilling fluids, and 

collisions and losses of well control that result in spills. 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. The various fractions within the crude 

behave differently in water. The lighter ends 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 

evaporate. 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. 

The National Academy of Sciences (NRC, 2003) and Boesch and Rabalais (1987) have reviewed the 

fate and effects of spilled oil. In general, the impacts to water quality are greatest when a spill occurs in a 

confined area where it persists for a long period of time. In an environment where the oil can be 

dispersed or diluted, the impacts are reduced. Spills of opportunity are few and difficult to sample on 

short notice. The evaluation of impacts from a large spill (>1,000 bbl) on water quality is based on 

qualitative and speculative information. 

CPA and WPA Proposed Action Analysis 

Oil Spills 

The Gulf of Mexico has numerous natural hydrocarbon seeps, as discussed in Chapters 3.1.2.2 and 

4.1.3.4. The marine environment can be considered adapted to handling small amounts of oil released 

over time. Most of the oil spills that may occur as a result of a proposed action are expected to be ≤1 bbl 

(Tables 3-6 and 3-7). 

An oil spill ≥1,000 bbl at the water surface may result from a platform accident. Subsurface spills 

would occur from subsea riser or pipeline failure or a loss of well control. Most of the oil from a 

subsurface spill would likely rise to the surface and would weather and behave similarly to a surface spill, 

depending upon a number of factors, particularly the characteristics of the released oil and oceanographic 
4-20 Central and Western Gulf of Mexico Multisale Supplemental EIS

conditions. Oil in the 181 South Area is reported to be denser than the typical Gulf of Mexico oil; 

therefore, it may rise to the surface more slowly. Some of the subsurface oil may also get dispersed 

within the water column, as in the case of the Ixtoc I seafloor blowout. Evidence from a recent 

experiment in the North Sea indicates that oil released during a deepwater blowout would quickly rise to 

the surface and form a slick (Johansen et al., 2001). Impacts from a deepwater oil spill would occur in the 

water column and at the surface where the oil would be mixed into the water and dispersed by wind 

waves. An additional discussion of the impacts of accidental spills to water quality is found in the 

Chapter 4.4.2.2 of the Multisale EIS. 

Chemical Spills 

A study of chemical spills from OCS activities determined that the 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 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 for time scales of hours to days. 

Accidental Releases of Drilling Fluids 

As a result of the specific gravity of SBF, an accidental release of synthetic-based drilling fluids 

would be expected to sink to the seafloor in the area immediately at and adjacent to the release site. 

Localized anoxic conditions at the seafloor would be expected to occur. This would be short term, lasting 

until the SBF decomposed. A study of an SBF spill-of-opportunity is currently in preparation (USDOI, 

MMS, in preparation(a)). 

Collisions 

A collision may result in the spillage of crude oil, refined products such as diesel, or chemicals. 

Diesel is the type of refined hydrocarbon spilled most frequently as the result of a collision. Minimal 

impacts result from a spill since diesel is light and will evaporate and biodegrade within a few days. 

Since collisions occur infrequently, the potential impacts to marine water quality are not expected to be 

significant. 

Loss of Well Control 

A loss of well control (LWC) includes events with no surface expression or impact on water quality 

to events with a release of oil or drilling fluids. A LWC event may result in localized suspension of 

sediments, thus affecting water quality temporarily. Results from a recent simulated experiment of a 

deepwater blowout indicated that the oil rose from 850 m (2,789 ft) to the surface in approximately 1 hr. 

Since LWC events and blowouts are rare events and are of short duration, potential impacts to marine 

water quality are not expected to be significant. 

Summary and Conclusion 

Smaller spills (<1,000 bbl) are not expected to significantly impact water quality in marine waters. 

Accidental chemical spills, release of SBF, and blowouts would have temporary localized impacts on 

water quality. 

4.1.2.1.4. Cumulative Impacts 

Water quality in marine waters will be impacted by the discharges from drilling, production, and 

removal activities. Sources not related to oil and gas activities that can impact marine water quality 

include bilge water discharges from large ships and tankers; coastal pollutants that are transported away 
Environmental and Socioeconomic Consequences 4-21 

from shore, including runoff, river input, sewerage discharges, and industrial discharges; and natural 

seepage of oil and trace metals. 

As discussed in Chapter 4.1.3.4 of the Multisale EIS, petroleum hydrocarbons can enter the Gulf of 

Mexico from a wide variety of sources. The major sources of oil inputs in the Gulf are natural seepage, 

produced waters, land-based discharges, and spills. Although the Gulf of Mexico comprises one of the 

world’s most prolific offshore oil-producing provinces as well as has heavily traveled tanker routes, 

inputs of petroleum from onshore sources far outweigh the contribution from offshore activities. The 

introduction of petroleum hydrocarbons resulting from human activity is generally concentrated in major 

municipal and industrial areas situated along coasts or large rivers that empty into coastal waters. 

The OCS-related cumulative activities that would impact marine water quality include discharges of 

drilling muds and cuttings during the drilling of exploration and development wells, discharges during a 

workover, structure installation and removal, discharges during production, pipeline installation, and 

service-vessel discharges including bilge and ballast water and discharges from the marine sanitation 

device. Chapter 4.5.2.2 of the Multisale EIS summarizes the drilling predicted to result from the OCS 

Program. From the MMS database, about 1,200 wells are spudded each year in the Gulf of Mexico. The 

inclusion of the 181 South Area in the proposed CPA sale area is projected to result in 9-12 additional 

wells above the projected 499-714 wells stated in the Multisale EIS. The impacts from drilling were 

discussed in Chapters 4.2.1.1.2.2 and 4.2.2.1.2.2 of the Multisale EIS. The impacts would be related to 

increased water turbidity in the vicinity of the operations and the addition of soluble contaminants to the 

water column. The additional impact to water quality from the proposed actions would be expected to be 

small compared with those derived from non-OCS activities, which are much more extensive. Studies 

thus far indicate that as long as discharge regulations are followed, impacts to the marine environment 

from drilling activities are not significant. 

Oil spills in the Gulf of Mexico also adversely affect water quality. Chapter 4.5.2.2 of the Multisale 

EIS summarizes the volumes of oil that originate from many different sources and enter Gulf waters. 

Accidental spills of chemicals and oil are expected to impact water quality on a temporary basis and only 

close to the spill. Winds, waves, and currents should rapidly disperse any spill and reduce impacts. 

Hurricanes may cause fuels and chemicals stored on platforms to enter the water when the structure is 

damaged or toppled. Structures that are blown off station may drag anchors and damage pipelines and 

subsea lines, resulting in the release of oil and chemicals. Loss of well control has not occurred as the 

result of hurricanes because of the built-in safety features. 

Summary and Conclusion 

Cumulative impacts on the water quality of the marine environment result from the addition of 

discharges from supply-vessel discharges and from the exploration, production, and removal activities to 

a relatively pristine environment. The incremental contribution of a proposed action to the cumulative 

impacts to marine water quality is not expected to be significant as long as all regulations are followed. 

4.1.3. Sensitive Coastal Environments 

4.1.3.1. Coastal Barrier Beaches and Associated Dunes 

The MMS has reexamined the analysis for barrier islands and associated dunes presented in the 

Multisale EIS, based on the additional information presented below and the addition of the 181 South 

Area to the proposed CPA sale area. No significant new information was found that would alter the 

impact conclusion for barrier islands and associated dunes presented in the Multisale EIS. Due to both 

the distance from the 181 South Area (over 130 mi or 209 km) and the prevailing easterly winds, 

activities associated with the 181 South Area are expected to have little to no affect on barrier islands and 

associated dunes. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Routine activities associated with a CPA or WPA proposed 
4-22 Central and Western Gulf of Mexico Multisale Supplemental EIS

action, such as increased vessel traffic, maintenance dredging of navigation canals, and pipeline 

installation, would cause negligible impacts and will 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 either a CPA or WPA proposed action are anticipated to be minimal. The incremental 

contribution of a proposed action to the cumulative impacts to barrier beaches and associated dunes is 

expected to be small. 

4.1.3.1.1. Description of the Affected Environment 

A detailed description of the physical location and formative processes that create the various coastal 

beaches and barrier island complexes are described in Chapter 3.2.1.1 of the Multisale EIS. A description 

of integrated shoreline environments, barrier islands, and dune zones that comprise and delineate the 

various vegetated habitats along these mainland and barrier beaches can also be found in the Multisale 

EIS. 

Barrier islands make up more than two-thirds of the northern Gulf of Mexico shore. Each of the 

barrier islands is either high profile or low profile depending on the elevations and morphology of the 

island (Morton et al., 2004). The height and continuity of these elevations determine the ability of the 

barriers to withstand storm-surge flooding and overwash. Barrier islands, particularly vegetated ones 

with freshwater and or saltwater pools, may serve as habitat for a wide variety of animal life, especially 

birds. The islands and spits protect the bays, lagoons, estuaries, salt marshes, seagrass beds, and other 

wetland environments, some of which may contain threatened or endangered species. 

A search was conducted for new information related to barrier island impacts published since 

completion of the Multisale EIS. An Internet search for relevant scientific journal articles was conducted 

using a publicly available search engine. In addition, the websites for Federal and State agencies were 

reviewed for newly released information, and academic researchers were contacted concerning any 

unpublished or forthcoming publications currently in review concerning the current state of the barrier 

islands and beaches along the Gulf of Mexico. Although new research and ongoing monitoring 

information is continuously being updated and will eventually be available from both State and Federal 

resource agencies, the new information found was related to issues that have already been presented in the 

Multisale EIS and summarized in this SEIS; therefore, it was not incorporated in its entirety in this 

document. However, pertinent refinements of barrier island impacts as noted in the newly released 

NMFS Hurricane Impact report on fishery habitat published in July 2007 (USDOC, NMFS, 2007a) is 

summarized below. 

The barrier islands from Texas to Florida all incurred some type of damage from the combination of 

Hurricanes Katrina and Rita and in some cases in combination with Hurricane Wilma as well. Hurricane 

Katrina in August 2005 caused severe erosion and landloss for the coastal barrier islands of the deltaic 

plain. 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. 

Texas 

The barrier islands along the northeast Texas coast were severely eroded, losing 1 ft (0.3 m) in 

elevation and retreating landward 98 ft (30 m) between 2001 and 2005, as a result of a combination of 

Hurricanes Katrina/Rita and other previous storms (Newby, 2007). The overall analysis showed gains 

and loses along the barrier beaches with a general landward retreat, but in some areas a parallel strip of 

elevation gain is also noted. In these areas the material from the beach was overwashed landward of the 

beach ridge with sediment deposited into low-lying areas (USDOC, NMFS, 2007a). The McFaddin 

NWR, Texas Point NWR, Sea Rim State Park, and J.D. Murphree State Wildlife Management Area 

comprise the McFaddin Complex, which contains approximately 60,000 ac (24,280 ha) of coastal marsh 

(i.e., fresh, intermediate, and brackish), coastal prairie (non-saline and saline), coastal woodlands, and 

beach/ridge habitats in Jefferson and Chambers Counties in southeast Texas (USDOC, NMFS, 2007a). 

The beaches and ridges along the McFaddin Complex were already experiencing a historic erosion rate of 

5-7 ft (1.5-2.1 m) per year prior to Hurricanes Katrina and Rita. Post-Hurricane Rita, a remnant 

dune/beach system still exists although much has been lost through erosion and shoreline retreat, leaving 
Environmental and Socioeconomic Consequences 4-23 

only a low-lying, washover terrace. Loss of the existing beach dunes and the lowering of beach ridge 

elevations along the Gulf shoreline of the McFaddin Complex from Hurricane Rita puts approximately 

30,000 ac (47 mi2

) of nationally significant wetlands at risk for saltwater intrusion. 

Louisiana 

The Louisiana barrier islands incurred the most damage from the 2005 hurricanes. In Louisiana, 

barrier islands were not only badly eroded, but elevations were reduced and the islands were moved 

shoreward. The Chandeleur Islands served as an important protective buffer for Louisiana’s wetlands. 

Already badly eroded by several hurricanes between 2002 and 2005 (i.e., Hurricanes Lili, Ivan, and 

Dennis), these islands were nearly destroyed by Hurricane Katrina (Graumann et al., 2005; Knabb et al., 

2006). The eye of Hurricane Katrina passed directly over the 50-mi (80-km) Chandeleur Island chain. 

The Chandeleur Islands suffered a nearly 50 percent permanent loss to both unvegetated and vegetated 

areas. The Chandeleur Islands were reduced by Hurricane Katrina from 5.64 mi2

 to 2.5 mi2 (3,610 to 

1,600 ac) and then to 2.0 mi2

 (1,280 ac) by Hurricane Rita (Di Silvestro, 2006). 

It is likely that seagrass habitat adjacent to the Chandeleur Islands also was severely impacted by 

scouring and burial. East Timbalier Island lost approximately 10 ac (4 ha) from the combined effects of 

Hurricanes Katrina and Rita. The FWS (USDOI, FWS, 2005) reported that the Breton NWR had been 

reduced by about half its previous size. 

Grand Isle was also heavily damaged by Hurricane Katrina. Although Hurricane Katrina made 

landfall more than 50 mi (80 km) to its east, Grand Isle received extremely high winds and a 12- to 20-ft 

(4- to 6-m) storm surge that caused tremendous structural damage to most of the island’s camps, homes, 

and business (Louisiana Sea Grant, 2005). 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 10-30 times per year. Under those 

conditions, the following would be overwashed: 67 percent of Timbalier Island; 100 percent of Isles 

Dernieres and the Barataria Bay Barriers (excluding Grand Isle); and 100, 89, and 64 percent of the 

southern, central, and northern portions of the Chandeleur Islands, respectively (Boyd and Penland, 

1981). 

Following Hurricane Katrina in August 2005, Hurricane Rita in September 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 that flattened coastal dunes, depositing sand and debris well into the backing 

marshes. 

Mississippi 

Along the Mississippi Gulf Coast the barrier islands were also severely eroded by Hurricane Katrina. 

The overall size and elevation and the vegetative cover were significantly reduced by about 15 percent 

(USDOC, NMFS, 2007c). Mississippi’s offshore barrier islands include Petit Bois, Horn, Ship, and Cat 

Islands. This island chain, located 12 mi (19 km) south of coastal Mississippi, provides a natural first line 

of defense against hurricanes and other tropical storm systems. Unfortunately, these natural barriers have 

suffered a series of onslaughts first by Hurricane Camille in 1969, which created a major cut through Ship 

Island; then by Hurricane Georges, which breached Horn Island; and several years later by Hurricanes 

Ivan and Katrina, which caused further damage. Hurricane Katrina alone destroyed more than 2,000 ac 

(809 ha) on these four islands and drastically reduced the functionality of the remaining acres (Barbour, 

2006). Importantly, their elevations have in many instances been reduced to near sea level and vegetative 

cover has been greatly reduced. The majority of permanent landloss (conversion to open water) occurred 

from what appears to be bare to slightly vegetated soil, with the exception of Petit Bois Island, which lost 

mostly denser vegetation (USDOC, NMFS, 2007c).

Alabama 

Portions of the barrier islands along the Alabama coast suffered from wind- and water-induced 

erosion as a result of the storm surge from Hurricane Katrina. The majority of the damage was on Isle 

Aux Herbes, a barrier island in Mississippi Sound on the southwest coast of Alabama. A biological 

survey report prepared for the Mobile Bay Estuary Program (Heck and Byron, 2006) indicated that land 
4-24 Central and Western Gulf of Mexico Multisale Supplemental EIS

loss had occurred on the island as a result of shoreline erosion. Vegetative debris from the storm event 

was also piled on some areas of the island. These barrier island beaches were important as sea turtle 

nesting sites. The FWS (USDOI, FWS, 2005) reported that about 50 sea turtle nests were lost along the 

Alabama coast. All 10 nests at the Bon Secour NWR were destroyed. 

Florida 

The storm surge from Hurricane Katrina caused minor beach erosion (loss of 1-3 ft or 0.3-0.9 m of 

beach or dune profile) along the south-facing shorelines of Dade and Monroe Counties in Florida (FDEP, 

2005). Hurricane Wilma, in addition to impacting the State directly, exposed the Florida Keys’ northfacing beaches from Key West to Lower Matecumbe Key and Curry Hammocks State Park to storm 

surge, flooding, and moderate (3- to 10-ft or 0.9- to 3-m vertical loss) to major (>10 ft or 3 m) beach 

erosion (FDEP, 2005). Major beach erosion is defined as the lowering of a beach profile with recession 

of dune vertical scarp >10 ft (3 m) or that the dunes are totally removed (FDEP, 2005). The island at 

Pelican Shoal Critical Wildlife Area (5 mi or 8 km south of Boca Chica Key) washed away. At Cape 

Sable, Hurricane Wilma devastated carbonate and shell beaches (FDEP, 2005). From Cape Sable 

northward along the west Florida coast to Sea Oat Island in Collier County, beach erosion also was major 

(FDEP, 2006).

In summary, the barrier islands throughout the Gulf of Mexico have all experienced varying degrees 

of erosion, land and vegetation loss, loss in elevation or beach profile, and in some cases movement 

toward shore as a result of previous highly active hurricane seasons. 

4.1.3.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on the coastal barriers and beaches is presented in Chapters 4.2.2.1.3.1 and 4.2.1.1.3.1 of 

the Multisale EIS, respectively. The following information is a summary of the impact analysis 

incorporated from the Multisale EIS that generally addresses the impacts of a proposed action. Because 

the 181 South Area is nearly 130 mi (209 km) from the nearest coast, it is unlikely that routine activities 

associated with the offshore exploration and drilling would affect these nearshore beaches or barrier 

islands. 

The routine impact-producing factors associated with a proposed action that could affect these 

environments include vessel traffic, maintenance dredging of navigational canals, and pipeline 

installation. 

CPA Proposed Action Analysis 

Effects on coastal barrier beaches and dunes as a result of channel maintenance or dredging related to 

a CPA proposed action are expected to be restricted to minor and very localized areas downdrift of the 

channel. If adverse impacts do occur as a result of any necessary channel maintenance, dredging of 

navigational 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 for wetland creation or beach restoration. 

A maximum of one new pipeline landfall is projected as a result of a CPA proposed action, even with 

the addition of the 181 South Area. Should a pipeline landfall occur in the immediate vicinity of a barrier 

island, the use of modern technologies, such as directional boring, would greatly reduce and perhaps 

eliminate impacts to coastal barrier islands and beaches. Therefore, the effects on barrier beaches and 

dunes from pipeline-laying activities associated with a CPA proposed action are expected to be minor or 

nonexistent. These impacts are considered to be negligible. 

There are 0-1 gas processing plants projected to be constructed as a result of a CPA proposed action. 

Should one be constructed, it will most likely be in Louisiana, where the large majority of the 

infrastructure exists for receiving oil and gas from the CPA. No gas processing facilities would be 

constructed on barrier beaches. Effects on coastal barrier beaches and associated dunes associated with 
Environmental and Socioeconomic Consequences 4-25 

construction of a gas processing plant from a CPA proposed action are expected to be restricted to minor 

and very localized areas downdrift of the channel. 

There is an expected increase in vessel traffic and helicopter support due to the addition of the 181 

South Area. This increased activity is not expected to require construction or expansion of onshore 

infrastructure. Port Fourchon and the armored navigation channels leading to the support-vessel bases are 

not expected to experience any increase in erosion as a result of the additional vessel trips required to 

support activity in the 181 South Area. For the near future, Port Fourchon would continue to be the 

primary base for both vessel and helicopter support for the CPA including the 181 South Area. In the 

long term, it is possible that coastal Alabama (Mobile, Theodore), Mississippi (Pascagoula), and Venice 

and Gagliano, Louisiana, may be used as support bases. Depending on the routing, number, and 

proximity of the existing navigation channels and sea lanes to the various barrier islands along these 

coasts, some potential may exist for erosion. This erosion potential cannot be determined until the exact 

locations of these additional locations are identified. At present, the average contribution of a CPA 

proposed action to OCS-related vessel traffic in navigation canals is expected to be small (2-3%). Turner 

and Cahoon (1988) found that OCS traffic in general comprises a relatively small percentage (~12%) of 

the total commercial traffic using navigation channels. Thus, the allocation of navigation channel impacts 

to OCS activities is small, and the contribution from a proposed action is even smaller. The erosion of 

coastal barrier beaches and associated dunes from vessel traffic associated with a CPA proposed action 

are expected to be negligible, especially considering OCS operations primarily staged from armored 

channels like Port Fourchon. 

WPA Proposed Action Analysis 

A proposed action will use existing navigation channels, which would require normally scheduled 

maintenance. Dredged material placement will be used for beach and marsh restoration where feasible. 

No dredged material will be placed on the barrier islands unless the action is restorative in nature. Port 

Fourchon is one of the primary vessel-based support base for the WPA. Since the navigation channels in 

this area are armored, the projected vessel traffic required for OCS in the WPA is not expected to increase 

channel erosion in the area. Lower post-storm elevations of several of the barrier islands have made them 

more susceptible to overtopping and increased erosion potential (USDOC, NMFS, 2007a). Because of 

this change in barrier island topography, there may be some indirect impacts due to sediment 

contributions from the eroding areas of these islands near a channel or sea lane. 

A maximum of one new pipeline landfall is expected to be constructed for each WPA proposed 

action. Should a pipeline landfall occur in the immediate vicinity of a barrier island, the use of modern 

technologies, such as directional boring, would greatly reduce and perhaps eliminate the impacts to 

coastal barrier islands and beaches. These impacts are considered to be negligible. 

The use of existing gas processing facilities built inland may, through natural storm-driven erosion 

and shoreline recession, be located in the barrier beach and dune zone and may contribute to the erosion. 

A WPA proposed action may contribute to the extended use of these facilities. There are 0-1 gas 

processing plants projected to be constructed as a result of a WPA proposed action. No gas processing 

facilities would be constructed on barrier beaches. 

Channel and inlet maintenance, as well as erosion protection works (jetties) required to assure access 

to the production and supply facilities, may contribute to minor and localized impacts on adjacent barrier 

beaches due to sediment deprivation. This would be most likely in the sediment-starved coasts of 

Louisiana. Based on use, a WPA proposed action would account for a very small percentage of these 

impacts, which would occur whether a proposed action is implemented or not. In conclusion, a WPA 

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. 

Summary and Conclusion 

The routine activities associated with a CPA or WPA proposed action that would impact barrier 

island beaches or their associated dunes include pipeline installation, construction or maintenance of 

navigation channels (dredging), navigation channel use (vessel traffic), and construction or expansion of 

oil- and gas-related infrastructure. Impacts are expected to be restricted to temporary and localized 

disturbances. Due to the proximity of the 181 South Area (130 mi or 209 km offshore) to the barrier 
4-26 Central and Western Gulf of Mexico Multisale Supplemental EIS

islands and beaches, it is unlikely that routine activities associated with this area would affect these 

nearshore beaches or barrier islands. 

The potential exists for modifications to channel training structures (jetties) to extend the life of 

onshore production facilities if necessary. Since these protective structures and onshore facilities are not 

located on barrier islands or barrier inlets and the magnitude of the work required to facilitate the 

proposed action, if needed, is minimal, no impact to barrier islands or beaches are expected as a result. 

Existing facilities originally built inland may, through natural erosion and shoreline recession, be located 

in the barrier beach and dune zone and may contribute to erosion there. A proposed action may 

contribute to the continued use of such facilities. Maintenance dredging of barrier inlets and bar channels 

is expected to occur, which, combined with channel jetties, generally causes minor and very localized 

impacts on adjacent barrier beaches downdrift of the channel due to sediment deprivation. The worst of 

these situations is found on the sediment-starved coasts of Louisiana where sediments are largely organic. 

Based on use, a CPA or WPA proposed action would account for a very small percentage of these 

impacts, which would occur whether a proposed action is implemented or not. Up to one processing plant 

and up to one new pipeline landfall are projected for a CPA and WPA proposed action. The avoidance of 

activities on barrier islands, as well as modern construction technologies, such as directional boring, 

would greatly reduce and perhaps eliminate impacts to coastal barrier islands and beaches. 

The MMS has reexamined the analysis for barrier islands and beaches presented in the Multisale EIS. 

Based on the additional information presented above, a CPA or WPA proposed action is not expected to 

adversely alter barrier beach configurations beyond existing, ongoing impacts in very localized areas 

downdrift of artificially jettied and maintained channels. A CPA or WPA 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 can 

mitigate adverse impacts upon those localized areas. No significant new information was found that 

would alter the overall conclusions that impacts to barrier island and beaches from routine activities 

associated with a CPA or WPA proposed action would be minimal. 

4.1.3.1.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts upon barrier beaches and dunes can be found in Chapter 

4.4.3.1 of the Multisale EIS. The following is a summary of the information presented in the Multisale 

EIS, which incorporates new information found since its publication. 

Accidental impacts associated with a CPA or WPA proposed action that could adversely affect barrier 

islands and beaches include oil spills associated with the transport and storage of oil (Chapter 4.3.1 of the 

Multisale EIS). Inland spills have the greatest potential for affecting the coastal barrier resources due to 

their proximity to the resources. Inland spills resulting from damage to pipelines, vessel collisions, 

malfunctions of onshore production or storage facilities, or blowouts have the greatest potential for 

contacting the barrier and mainland beach resources. The impact from these oil spills depends on the 

geographic location of the spill, volume, rate of spill, type of oil, oil-slick characteristics, oceanic 

conditions at the time of the spill, season, and oil-spill response and cleanup preparedness. Coastal spills 

in offshore coastal waters or in the vicinity of Gulf tidal inlets present a greater potential risk to barrier 

beaches because of their close proximity. Inland spills that occur away from Gulf tidal inlets are 

generally not expected to significantly impact barrier beaches and dunes. 

Impacts to the general vegetation and physical aspects of coastal environments by oil spills and 

cleanup response activities resulting from a CPA or WPA proposed action are considered in Chapters 

4.4.3.1, 4.4.3.2, and 4.4.3.3 of the Multisale EIS. Potential impacts from oil spills to barrier islands 

seaward of the barrier-dune system are considered in the coastal barrier beaches and associated dunes 

analysis. Potential impacts to barrier islands landward of the barrier-dune system are considered in 

Chapter 4.1.3.2 of the Multisale EIS. The types and sources of spills that may occur, their dissipation 

prior to contacting coastal resources, spill-response activities, and mitigation are described in Chapter 

4.3.1 of the Multisale EIS. 

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 a CPA or WPA proposed action. 
Environmental and Socioeconomic Consequences 4-27 

Although a resulting slick may cause beach oiling, equipment and personnel used to clean up an oil spill 

may generate the greatest direct 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. 

Should a spill contact a barrier beach, oiling is expected to be light and sand removal during cleanup 

activities minimized. However, the protection previously afforded the mainland beaches and the barrier 

islands and their associated wetlands pre-Katrina has been reduced. Hurricanes Katrina and Rita reduced 

barrier island elevations, removed significant areas of vegetation, eroded channels, and in some cases 

reduced the land mass (Chandeleur Island area reduced by 50%) of barrier islands along the Louisiana, 

Mississippi, and Alabama coasts (USDOC, NMFS, 2007a). In Mississippi, the overall size and elevation 

were reduced significantly by 15 percent (USDOC, NMFS, 2007a). The northeast Texas coast lost 1 ft 

(0.3 m) in elevation and retreated 98 ft (30 m) from 2001 to 2005 (USDOC, NMFS, 2007a). 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 by either removing or completely 

redistributing the sediments on the island so that the island becomes submerged. 

CPA Proposed Action Analysis 

Barrier islands and beaches adjacent to the CPA are restricted to the coastal waters of Louisiana, 

Mississippi, and Alabama. 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 being contacted by spills from 

operations related to a CPA proposed action. Spills that could occur in coastal waters from support 

operations associated with a CPA proposed action over its 40-year life are estimated at 46-102 spills. 

As explained in Chapter 3.2.1 of this SEIS, the incremental increase in oil production from the 

addition of the 181 South Area 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 a CPA proposed action. Activity that would result from the 

addition of the 181 South Area would cause a negligible increase in the risk of a large spill occurring and 

contacting barrier islands and beaches. If oil should reach the beaches from this distance, it would be 

sufficiently weathered and detoxified through biodegradation, mixing, and the weathering process. 

The probabilities of an offshore spill ≥1,000 bbl occurring and contacting environmental features are 

described in Chapter 4.3.1.8 of the Multisale EIS. Eight parishes in Louisiana and two counties in Texas 

have a chance of spill contact that is >0.5 percent. For these parishes and counties, the chance of an OCS 

offshore spill ≥1,000 bbl ranges from 1 to 16 percent. In Louisiana, the Deltaic Plain area has the highest 

risk from a CPA proposed action (Chapter 4.3.1 of the Multisale EIS). Except for two accidental 3,000-

bbl spills estimated to occur in Louisiana and Texas coastal waters under the high resource-estimate 

scenario over the 40-year life of a proposed action, MMS estimates that coastal spills ≥1,000 bbl resulting 

from a CPA proposed action will have a low probability of occurrence. 

Approximately 61-136 spills are estimated to occur within Gulf coastal waters from activities 

supporting the CPA and WPA proposed actions, over their 40-year life, combined. Most (about 90%) of 

these spills would be ≤1 bbl. The most likely locations of the estimated 6-15 coastal spills >1 bbl would 

be proximate to the major oil pipeline or shore facilities. 

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 a CPA proposed action. The greatest risk of contact would be from the assumed 3,000-bbl spill should 

it occur within or near wetlands. 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 a CPA proposed 

action. 
4-28 Central and Western Gulf of Mexico Multisale Supplemental EIS

WPA Proposed Action Analysis 

The barrier islands in the WPA are located primarily along the northeast coast of Texas (Chapter 

3.2.1.1 of the Multisale EIS) and, in general, are characterized by higher elevations and steeper shoreline 

beaches with elevated dune systems. These physical characteristics make these island beaches and the 

wetlands associated with the back beach areas less susceptible to oil spills. However, depending on the 

volume and proximity of inland or coastal spills to these beach resources, beach oiling could occur. With 

proper spill management and the use of proper cleanup techniques, the effects can be minimized and 

temporary. 

Because of the proximity to barrier islands and beaches, inshore spills pose the greatest threat. 

Inshore vessel collisions may release fuel and lubricant oils, and pipeline ruptures may release crude and 

condensate oil. The Galveston/Houston/Texas City area has the greatest risk of experiencing coastal 

spills related to a WPA proposed action. Spills that could occur in coastal waters from a proposed action 

support operations are estimated at 15-34 spills for a WPA proposed action over its 40-year life. 

Offshore oil spills that occur in the proposed action areas are much less likely to contact barrier island 

and beach resources than inshore spills. The probabilities of an offshore spill ≥1,000 bbl occurring and 

contacting environmental features are described in Chapter 4.3.1.8 of the Multisale EIS. Six counties in 

Texas and one parish in Louisiana have a chance of spill contact that is >0.5 percent. For these counties 

and parish, the chance of an OCS offshore spill ≥1,000 bbl occurring and reaching the shoreline ranges 

from 1 to 5 percent as the result of a proposed action over its 40-year life. 

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 a WPA proposed action. 

Summary and Conclusion 

Because of the proximity to barrier islands and beaches, inshore spills pose the greatest threat. Such 

spills may result from either vessel collisions that release fuel and lubricants or from pipelines that 

rupture. Most of the estimated number of nearshore spills are smaller in volume and would weather 

quickly. Should a nearshore spill occur, these impacts would be considered short term in duration and 

minor in scope. Although a resulting slick may cause beach oiling, equipment and personnel used to 

clean up an oil spill may generate the greatest direct 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. 

The MMS has reexamined the analysis for barrier island and beach resources presented in the 

Multisale EIS, based on the additional information presented above. The most current information did 

reveal that some of the barrier islands had experienced storm-induced reductions in beach shoreline 

elevations and erosion (USDOC, NMFS, 2007a). While this information may indicate some reduction in 

the protection provided by the affected barrier islands, the significance of this loss of protection is small 

in comparison with the overriding climatic forces. Therefore, this information would not alter the overall 

conclusion that impacts on barrier islands and beaches from accidental impacts associated with a CPA or 

WPA proposed action would be minimal. 

The addition of the 181 South Area would not pose a significant increase in risk to barrier island or 

beach resources. 

4.1.3.1.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts upon barrier beaches and associated dunes can be found 

in Chapter 4.5.3.1 of the Multisale EIS. The following is a summary of the information presented in the 

Multisale EIS, which incorporates new information found since publication of the Multisale EIS. 

This cumulative analysis considers the effects of impact-producing factors related to a 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 
Environmental and Socioeconomic Consequences 4-29 

the Mississippi River, beach protection and stabilization projects, oil spills, oil-spill response and clean up 

activities, pipeline landfalls, navigation channels, development and urbanization, natural processes, 

potential for nearshore salinity modifications (preparation of salt domes for oil storage), tourism and 

recreational activities. 

River Channelization and Beach Protection 

In the CPA, 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 rivers’ mouths. This reduction in sediment not only 

impedes delta building but also fails to provide the needed sediment transport required for nourishment of 

the eroding offshore barrier islands and their beaches. This, coupled with beach building and stabilization 

projects utilizing mined sands, jetties, groins, and other means of sediment capture, are depriving natural 

restoration of the barrier beaches normally accomplished through sediment nourishment and sediment 

transport. 

In the WPA, the Texas coast has experienced a natural decrease in sediment supply as a result of 

climatic changes (e.g., diminished rainfall, etc.) that have occurred during the past few thousand years 

(Morton, 1982) and dam construction, both of which have resulted in the loss of sediment and sediment 

transport. Seawall construction along eroding stretches of islands has reduced the amount of sediment 

introduced into the littoral system by shore erosion. The Texas Chenier Plain used reworked sediments 

from the Mississippi River depositions, which are now decreased by beach and channel stabilization 

work, as well as flood protection works. Reductions in sediment supply along the Texas coast will 

continue to have a significant adverse impact on barrier landforms there. Subsidence, erosion, and 

dredging of inland coastal areas and the concurrent expansion of tidal influences, 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 or inland waterbodies. These 

incremental changes will cause adverse impacts to barrier beaches and dunes. Efforts to stabilize the Gulf 

shoreline have adversely impacted barrier landscapes in Louisiana and Texas. Large numbers and 

varieties of stabilization techniques, such as groins, jetties, and seawalls, as well as artificially-maintained 

channels and jetties, 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, which 

accelerates erosion there (Morton, 1982), and by increasing or redirecting the erosional energy of waves. 

Over the last 20 years, dune and beach stabilization have been better accomplished by using more natural 

applications such as sand dunes, beach nourishment, and vegetative plantings. 

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 while trying to control catastrophic floods and change the natural environment to better 

accommodate navigation on waterways used to support OCS and non-OCS seaborne traffic. Sea-level 

rise and coastal subsidence, in combination with tropical and extra-tropical storms, exacerbate and speed 

up the erosion of coastal barrier beaches along the Gulf Coast of Louisiana in the CPA. Both the western 

edge of the CPA along the western Louisiana coast as well as the eastern Texas coast in the WPA all 

received major damage as a result of Hurricanes Katrina and Rita. Hurricane Rita in September 2005 

severely impacted the shoreface and beach communities of Cameron Parish in southwest Louisiana and 

the southeast Texas coast. Some small towns in the western portion of the CPA 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 backing marshes. These barriers both 

lost elevation and vegetative cover as a result of the erosion forces accompanying the storm surge and 

scour from storm-driven debris (Barras, 2007a). The removal of vegetative cover and scour scars that 

accompanies these over toppings as a result of storm surges also provides an avenue for additional erosion 

to occur as a result of inlet formations and tidal rivulets. These modifications to the topography on these 

islands may result in hydrological changes that enable further sediment transport from the islands, 
4-30 Central and Western Gulf of Mexico Multisale Supplemental EIS

providing pathways for further erosion and saltwater intrusion into the islands’ less salt-tolerant, interior 

vegetated habitats. 

The barrier islands of Texas underwent similar significant erosion and loss of dune elevation as a 

result of Hurricane Rita (USDOC, NMFS, 2007a). 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, lessening the pre-storm protection provided by these barrier islands. This reduction in 

island elevation results in less frontline protection to valuable marshes within the McFaddin Complex and 

also makes urban and industrial areas protected by these marshes more at risk (USDOC, NMFS, 2007a). 

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 a CPA or 

WPA proposed action are expected to be restricted to temporary and localized disturbances. The 0-1 

pipeline landfalls projected in support of a CPA or WPA proposed action are not expected to cause 

significant impacts to barrier beaches because of the use of non-intrusive installation methods. The 0-1 

gas processing plants would not be expected to be constructed on barrier beaches. Existing facilities 

originally built inland may, through natural erosion and shoreline recession, be located in the barrier 

beach and dune zone and contribute to erosion there. A proposed action may contribute to the continued 

use of such facilities. Maintenance dredging of barrier inlets and bar channels is expected to occur, 

which, combined with channel jetties, generally causes minor and very localized impacts on adjacent 

barrier beaches downdrift of the channel due to sediment deprivation. The worst of these situations is 

found on the sediment starved coasts of Louisiana, where sediments are largely organic. Based on use, a 

proposed action would account for a very small percentage of these impacts, which would occur whether 

a proposed action is implemented or not. The 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. A CPA proposed action may extend the life and presence of 

facilities in eroding areas, which would accelerate erosion in those areas. 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. 

While vessel traffic may cumulatively increase over the life of the estimated 40-year period of OCS 

exploration, it is doubtful that this increase in cumulative numbers is sustainable since some older wells 

will be coming 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 over time since vessel traffic 

would either decrease or reach a balance to meet the needs of the working wells. The entire current OCS 

Program accounts for only 12 percent of the commercial ship traffic. The additional amount added by a 

WPA proposed action accounts for 4.5-5.7 percent of the OCS Program’s usage and 0.5-0.7 percent of the 

total commercial usage. The CPA proposed action accounts for 2.5-4.1 percent of the OCS Program and 

0.3-0.5 percent of the total commercial traffic. Further details concerning vessel traffic can be found in 

Chapters 4.2.1.1.3.2, 4.2.2.1.3.2, and 4.1.1.8.4 of the Multisale EIS. Navigation channels projected to be 

used in support of a CPA or WPA 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 (Chapters 4.2.1.1.3.1 and 

4.2.2.1.3.1 of the Multisale EIS). 

Most spills occurring in offshore coastal waters are assumed to proportionally weather and dissipate 

similar to the weathering described in Tables 4-36 and 4-37 of the Multisale EIS. Dispersants are not 

expected to be used in coastal waters. The weathering model described in Chapter 4.3.5 of the Multisale 

EIS attributes the dispersal of about 65 percent of the volume of a spill to the use of dispersants. No 
Environmental and Socioeconomic Consequences 4-31 

calculation has been made to estimate how much oil might be deposited on a beach if dispersants are not 

used. Unfavorable winds and currents would further diminish the volume of oil that might contact a 

beach. A persistent, northwesterly wind might preclude contact. As discussed in Chapters 3.2.1.1, 

4.2.1.1.3.1, 4.2.2.1.3.1, and 4.3.1.8 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, depending 

on the particular coastal setting and the elevation of the vegetation. The strong winds that would be 

needed to produce unusually high tide levels would also disperse the slick over a larger area than is being 

considered in the current analysis. The probabilities of spill occurrence and contact to barrier beaches and 

sand-dune vegetation are considered very low. Hence, contact of sand-dune vegetation by spilled oil is 

not expected to occur. Furthermore, the Mississippi River discharge would help breakup a slick that 

might otherwise contact Plaquemines Parish. The spreading would reduce the oil concentrations 

contacting the beach and vegetation, greatly reducing impacts on vegetation. 

The barrier beaches of Deltaic Louisiana have the greatest rates of erosion and landward retreat of 

any known in the western hemisphere, and among the greatest rates on earth. Long-term impacts to 

contacted beaches from these spills could occur if significant volumes of sand were removed during 

cleanup operations. Removing sand from the coastal littoral environment, particularly in the sand-starved 

transgressive setting of coastal Louisiana, could result in accelerated coastal erosion. Spill cleanup is 

difficult in the inaccessible setting of coastal Louisiana. This analysis assumes that Louisiana would 

require the responsible party to clean the beach without removing significant volumes of sand or to 

replace the sand removed. Hence, cleanup operations are not expected to cause permanent effects on 

barrier beach stability. Within a few months, adjustments in beach configuration may result from the 

disturbance and movement of sand during cleanup. 

The results of an investigation on the effects of the disposal of oiled sand on dune vegetation in Texas 

showed no deleterious impacts on existing vegetation or colonization of the sand by new vegetation 

(Webb, 1988). Hence, projected oil contacts to small areas of lower elevation sand dunes are not 

expected to result in destabilization of the sand dune area or the barrier landform. 

Some oil will penetrate to depths beneath the reach of the cleanup methods. The remaining oil would 

persist in beach sands, periodically being released when storms and high tides resuspend or flush through 

beach sediments. During hot, sunny days, tarballs buried near the surface of the beach sand may liquefy 

and cause a seep to the sand surface. The long-term stressors, including physical effects and chemical 

toxicity of hydrocarbons, may lead to decreased primary production, plant dieback, and hence further 

erosion (Ko and Day, 2004). 

Recreational Use and Tourism 

Most barrier beaches in the CPA are relatively inaccessible for recreational use because they are 

either located a substantial distance offshore, as in Mississippi, or 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 Texas, Alabama, and Florida are accessible to people for recreational use 

because of road access, and their use is encouraged. The Texas Open Beaches Act (1959) guarantees the 

public’s right to unimpeded use of the State’s beaches. It also provides for public acquisition of private 

beach-front property. 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. Judd et al. (1988) documented that as much as 18 percent of the total dune area along 

parts of South Padre Island had experienced damage from vehicular traffic. Recreational vehicles and 

even hikers have been problems where road access is available and where the beach is wide enough to 

support vehicle use, as in Texas, Alabama, Florida, and a few places in Louisiana. Areas without road 

access will have very limited impacts by recreational vehicles. The CPA and WPA proposed actions 

would not provide any additional access that would result in an additive cumulative impact to the barrier 

beaches and dunes. 
4-32 Central and Western Gulf of Mexico Multisale Supplemental EIS

Summary and Conclusion 

River channelization, sediment deprivation, tropical and extra-tropical storm activity, sea-level rise, 

and rapid submergence have resulted in severe, rapid erosion of most of the barrier and shoreline 

landforms along the Louisiana coast. The barrier system of coastal Mississippi and Alabama is well 

supported on a coastal barrier platform of sand. The Texas coast has experienced landloss because of a 

decrease in the volume of sediment delivered to the coast because of dams on coastal rivers, a natural 

decrease in sediment supply as a result of climatic changes during the past several thousand years, and 

subsidence along the coast. 

Beach stabilization projects are considered by coastal geomorphologists and engineers to accelerate 

coastal erosion. Beneficial use of maintenance dredged materials 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 landform if 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 oil-spill 

landfalls because of their very high concentrations of oil production near those coasts. 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 cleanup operations. Some contact to 

lower areas of sand dunes is expected. These contacts would not result in significant destabilization of 

the dunes. The long-term stressors to barrier beach communities caused by the physical effects and 

chemical toxicity of an oil spill may lead to decreased primary production, plant dieback, and hence 

further erosion. 

Under the cumulative scenario, new OCS-related and non-OCS pipeline landfalls are projected. 

These pipelines are expected to be installed using modern techniques, which cause little to no impacts to 

the barrier islands and beaches. Existing pipelines, in particular those that are parallel and landward of 

beaches, that had been placed on barrier islands using older techniques that left canals or shore protection 

structures have caused and will continue to cause barrier beaches to narrow and breach. 

Recreational use of many barrier beaches in the Western Gulf is intense because of their accessibility 

by road. 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. Federal, State, and local governments 

have made efforts over the last 10 years to slow the landward retreat of Louisiana’s Gulf shorelines. 

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 as well as 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. 

A CPA or WPA 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. A 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 can mitigate adverse impacts upon those localized 

areas. Thus, the incremental contribution of a proposed action, including the 181 South Area, to the 

cumulative impacts on coastal barrier beaches and dunes is expected to be very small. 

4.1.3.2. Wetlands 

The MMS has reexamined the analysis for wetlands presented in the Multisale EIS, based on the 

additional information presented below and the addition of the 181 South Area to the proposed CPA sale 

area. No significant new information was found that would alter the impact conclusion for wetlands 

presented in the Multisale EIS. Because the 181 South Area is nearly 130 mi (209 km) from the nearest 

coast, the area has little potential for direct impact to coastal wetlands as a result of the proposed activities 

in that area. 
Environmental and Socioeconomic Consequences 4-33 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Effects to coastal wetlands from the primary impact-producing 

activities associated with a CPA or WPA proposed action are expected to be low. The primary impactproducing activities associated with routine activities for a proposed action that could affect wetlands 

include pipeline emplacement, construction and maintenance, navigational channel use (vessel traffic) 

and maintenance, disposal of OCS-related wastes, and use and construction of support infrastructure in 

these coastal areas. Vessel traffic associated with a proposed action is expected to contribute minimally 

to the erosion and widening of navigation channels and canals. Deltaic Louisiana is expected to continue 

to experience the greatest loss of wetland habitat. Wetland loss is also expected to continue in coastal 

Texas, Mississippi, Alabama, and Florida, but at slower rates. The incremental contribution of a proposed 

action to the cumulative impacts on coastal wetlands is expected to be very small. 

Routine activities in the CPA and WPA 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 a proposed action’s impacts to the cumulative 

impacts to wetlands is small and expected to be negligible. 

4.1.3.2.1. 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. The following is a summary of the information presented in the 

Multisale EIS, which incorporates new information found since the publication of the Multisale EIS. 

Coastal wetland habitats occur as bands around waterways; broad expanses of saline, brackish, and 

freshwater marshes; mud and sand flats; and forested wetlands of cypress-tupelo swamps and bottomland 

hardwoods. Saline and brackish habitats support sharply delineated, segregated stands of single plant 

species, while fresh and very low salinity environments support more diverse and mixed communities of 

plants. High organic productivity and efficient nutrient recycling are characteristic of coastal wetlands. 

They provide habitats for a great number and wide diversity of resident plants, invertebrates, fishes, 

reptiles, birds, and mammals. They 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. 

A search was conducted for new information related to coastal wetlands published since completion 

of the Multisale EIS. An Internet search for relevant scientific journal articles was conducted using a 

publicly available search engine. The journals of Environmental Management, Estuaries, and Journal of 

Wetland Science, along with the websites for Federal and State agencies, were reviewed for newly 

released information. The USGS Open File reports by Barras (2006) concerning post-Katrina/Rita land 

changes in coastal Louisiana were reviewed for new information, as were the FWS Wetlands Status and 

Trends website, the Louisiana Coast website, and the Louisiana Coastal Restoration Program website. In 

addition to website reviews, interviews were conducted with key personnel from the Texas Department of 

Economic Geology, Texas General Land Office, Texas Parks and Wildlife, and USGS concerning 

additional information on wetland loss in their particular area of work. The NMFS report to Congress 

(USDOC, NMFS, 2007a), prepared in July 2007, addressed the impacts of Hurricanes Katrina, Rita, and 

Wilma on fishery habitat (including wetlands). This report was reviewed for information pertinent to 

wetland loss and will be summarized later in this section. 

Louisiana 

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. Studies have shown that the landloss rate in coastal Louisiana for the 

period 1972-1990 slowed to between an estimated 6,475 ha/yr (25 mi2

/yr) (Louisiana Coastal Wetlands 
4-34 Central and Western Gulf of Mexico Multisale Supplemental EIS

Conservation and Restoration Task Force, 1993) and 9,072 ha/yr (35 mi2/yr) (USDOI, GS, 1998). Over 

the next 50 years, Louisiana is projected to lose almost 17 mi2

 (4,403 ha) of coastline each year due to 

storms, sea-level rise, and land subsidence (GAO, 2007). 

Pipelines and Navigation Canals 

The MMS-funded study Outer Continental Shelf (OCS)-Related Pipelines and Navigation Canals in 

the Western and Central Gulf of Mexico: Relative Impacts on Wetland Habitats and Effectiveness of 

Mitigation (Johnston et al., 2007) was recently published. The purpose of the study was to determine the 

direct and indirect effects of existing OCS-related pipelines and navigation canals on landloss and 

wetland habitat change. Preliminary data from this study was included in the Multisale EIS. The 

following is a summary of the study. 

Spatial analyses revealed that landloss was consistently higher in the vicinity of pipelines compared 

with more general, regional trends of landloss. The locations of OCS-related pipelines and navigation 

canals were associated with enhanced loss, suggesting that they contributed to the loss. However, the 

analysis was not able to disassociate trends uniquely related to pipeline or canal impacts from larger, 

regional trends related to a host of other contributing variables, such as other human activities or natural 

causes. 

Annual rates of landloss within 150 m (492 ft) to either side of OCS-related pipelines were highest in 

Louisiana, lowest in the Mississippi/Alabama coastal plain, and intermediate in Texas. Higher rates in 

Louisiana may be due to higher concentrations of pipelines and higher rates of subsidence. Direct 

impacts from pipelines were found to increase with the diameter and age of pipelines. However, recently 

built pipelines and pipeline canals are much narrower than in the past because of advances in technology 

and improved methods of installation due to a greater awareness among regulatory agencies and industry. 

The study also looked at the dominant techniques used to construct and mitigate OCS-related 

pipelines and navigation canals effective in minimizing their effects on landloss, wetland loss, and habitat 

change. It was found that the magnitude of impacts from OCS-related pipelines described is inversely 

proportional to the quantity and quality of mitigation techniques applied. Pipelines with extensive 

mitigation measures appeared to have minimal impacts, while pipelines not backfilled and/or that had 

spoil banks remaining after construction attributed to significant habit changes. Through proper 

construction methods, mitigation, and maintenance, impacts can be minimized or altogether avoided. 

There were strong spatial trends in habitat change within 500 m (1,640 ft) to either side of OCSrelated navigation channels from the 1950’s to the 1990’s in Louisiana and Texas, with minor changes in 

the Mississippi/Alabama coastal plain. Navigation canals had significant habitat impacts on the 

landscape, including significant widening. The study did not look at saltwater intrusion as a result of 

canals. A reduction of widening in recent years was noted, likely as a result of more aggressive 

management and the restoration of the canal edges to prevent erosion. Results indicate that management 

activities, including erosion protection and restoration along the edges of these canals, can significantly 

reduce canal-widening impacts on wetland loss. Besides the direct, uncontrollable impacts of a 

functioning navigation canal (i.e., saltwater intrusion), additional impacts can be mitigated with bank 

stabilization, and where possible, the beneficial use of dredged material (produced during maintenance 

dredging activities) to create wetland or upland habitats. The MMS is not a permitting agency of onshore 

infrastructure. The permitting agencies 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 properly mitigate and monitor 

onshore infrastructure impacts. 

Hurricanes 

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 areas following the storms, 

primarily comprised of wetlands being replaced by open water. These estimates were made utilizing 

analysis of satellite imagery (Landsat TM imagery) combined with periodic ground-truthing to monitor 

accuracy. These new water areas represent landlosses caused by direct removal of wetlands. They also 

indicate transitory changes in water area 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. Permanent landlosses cannot be estimated until several growing 
Environmental and Socioeconomic Consequences 4-35 

seasons have passed and the transitory impacts of the hurricanes are minimized. Table 4-2 summarizes 

the land/water changes for all coastal Louisiana hydrologic basins that were affected by the 2005 

hurricanes (Barras, 2006). 

Based on the analysis of the latest satellite imagery (Barras, 2007a and b), approximately 82 mi2

 (212 

km2

) of new open-water areas were in areas primarily impacted by Hurricane Katrina (Mississippi River 

Delta basin, Breton Sound basin, Pontchartrain basin, and Pearl River basin), whereas 117mi2

 (256 km2) 

were in areas primarily impacted by Hurricane Rita (Calcasieu/Sabine basin, Mermentau basin, 

Teche/Vermilion basin, Atchafalaya basin, and Terrebonne basin). Barataria basin contained new water 

areas caused by both hurricanes, resulting in some 18 mi2

 (46.6 km2) of new water areas. 

A comparison of the 2004 and 2005 imagery showed a total increase in water area of 300 mi2

 (777 

km2

), but this measurement includes 83 mi2 (214.97 km2) of flooded lands consisting of flooded/burned 

marsh and flooded agricultural and developed areas occurring after the hurricanes. Adjusting for these 

flooded lands, the estimated increase in water area (and decrease in land) is 217 mi2

 (562 km2). Direct 

correlations of land and water area changes are assumed. This coastwide 217 mi2 (562 km2

) area of new 

water occurring after the hurricanes contains (1) landlosses that may be permanent, caused by direct 

removal of wetlands by storm surge; and (2) transitory water area increases caused by (a) remnant 

flooding of marsh and impounded areas, including agricultural and developed areas, (b) removal of 

floating and submerged aquatic vegetation, (c) scouring of marsh vegetation, and (d) water level 

variations caused by normal tidal and meteorological variation between images. The new land occurring 

after the hurricanes contains land gains caused by (1) wrack deposition, (2) rearrangement of existing 

marsh areas moved by storm surge, (3) aquatic vegetation that is possibly misclassified, and (4) water 

level variations caused by normal tidal and meteorological variation between images. These transitory 

gains and losses are included in calculations of net land area change. The details of these pre- and postHurricane Katrina comparisons are noted in Table 4-3 (Barras, 2006). 

The fresh marsh and intermediate marsh communities’ land areas decreased by 122 mi2

 (316 km2) 

and 90 mi2

 (233.1 km2), respectively, and the brackish marsh and saline marsh communities’ land areas 

decreased by 33 mi2

 (85.5 km2) and 28 mi2 (72.5 km2), respectively. These new water areas represent 

landlosses caused by the direct removal of wetlands. They also indicate transitory changes in water area 

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. It was noted 

(Barras, 2006) that permanent losses cannot be estimated until several growing seasons have passed and 

the transitory impacts of the hurricanes are minimized; however, it is too early to estimate the actual 

overall marsh loss. 

Coastal Restoration 

The State of Louisiana has made a provision for wetlands protection and restoration to be part of the 

State’s plan for hurricane protection. The Louisiana State legislature established the Coastal Protection 

and Restoration Authority (CPRA) and charged it with coordinating the efforts of local, State, and Federal 

agencies to achieve long-term and comprehensive coastal protection and restoration that integrates flood 

control and wetland restoration. The following four objectives were defined for the plan: reduce the risk 

to economic assets; restore sustainability to the coastal ecosystem; maintain a diverse array of habitats for 

fish and wildlife; and sustain Louisiana’s unique heritage and culture. The Final Master Plan (State of 

Louisiana, CPRA, 2007) was submitted to the Louisiana legislature on April 30, 2007, and was approved 

on May 30, 2007.

Mississippi 

In Mississippi the overall land cover change noted by NOAA’s Coastal Change Analysis Program 

was much less severe than encountered in Louisiana. The total area that changed to open water is less 

than 5 mi2 (3,200 ac) (Herold and McCombs, personal communication, 2007). Compared with 

Louisiana, this loss of emergent marsh and unconsolidated shoreline was minimal. An estimated 1,890 ac 

(765 ha) of coastal marshes and forests were severely damaged or destroyed (USDOC, NMFS, 2007b). 

The greatest change was in coastal forests, especially bottomland hardwoods. While over 70 mi2

 of forest 

(mostly evergreen) was lost or converted to grasses, an estimated 10 mi2

 of bottomland hardwood forests 

were seen changing to palustrine scrub or emergent categories. There was also a conversion of 40 mi2

 of 
4-36 Central and Western Gulf of Mexico Multisale Supplemental EIS

evergreen forest to scrub/shrub cover. Estuarine marsh and wetlands suffered extensive damage from 

Hurricane Katrina (Mississippi Dept. of Marine Resources, 2005; Barbour, 2006). 

Alabama 

Along the Alabama coast there was some damage to wetlands due to erosion along the shores of some 

of the barrier islands. There was also some damage, although not quantified, from scoured or buried 

wetland habitats. The land cover changes in Alabama, observed by NOAA’s Coastal Change Analysis 

Program, highlight the loss of forested land and the related increase to grassland area, which was likely 

caused by the 2005 hurricanes (Herold and McCombs, personal communication, 2007). There was a loss 

of approximately 50 mi2

 (12,950 ha) of hardwood forests. The areas that were primarily evergreen stands 

were either damaged by Hurricane Katrina or intentionally harvested and now are dominated by 

scrub/shrub (approximately 15 mi2

 or 3,885 ha) or grassland (approximately 17 mi2 or 4,403 ha). 

Texas 

Most of the wetlands along the Texas coast are associated with the NWR’s and State wildlife 

management areas, such as Texas Point NWR, McFaddin NWR, Sea Rim State Park, and J.D. Murphree 

State Wildlife Management Area. These areas comprise the McFaddin Complex and contain over 60,000 

ac (24, 280 ha) of coastal marsh (fresh, intermediate, and brackish) coastal prairie (non-saline and saline), 

coastal woodlands, and beach/ridge habitat in Jefferson and Chambers Counties in southeast Texas 

(USDOC, NMFS, 2007a). The ridge/dune system that was the main buffer between the Gulf and the 

wetlands has been significantly lowered by the overwash of the past hurricanes. While a remnant 

dune/beach system still exists post-Hurricane Rita, much has been lost through erosion and shoreline 

retreat, leaving only a low-lying washover terrace. Loss of the existing beach dunes and the lowering of 

beach ridge elevations along the Gulf shoreline of the McFaddin Complex from Hurricane Rita imperils 

approximately 30,000 ac (12,140 ha) of nationally significant wetlands due to the increasing frequency of 

saltwater inundation from the Gulf of Mexico. Ongoing shoreline retreat along the Gulf of Mexico, 

which was exacerbated by Hurricane Rita, is resulting in a rapid loss of valuable coastal habitats, 

including emergent estuarine marshes and coastal prairies. In summary, the NWR’s in southeast Texas 

suffered wetland habitat loss, primarily as a result of wave erosion, during Hurricane Rita. Impacts to 

three Federal refuges were estimated to include direct marsh loss of more than 75 ac (33 ha), 

approximately 15,000 ac (6,070 ha) of marsh under increased threat by future storms, and erosion losses 

along 20 mi (32 km) of shoreline.

4.1.3.2.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of possible impacts associated with routine activities in a CPA or WPA 

proposed action on wetlands is presented in Chapters 4.2.2.1.3.2 and 4.2.1.1.3.2 of the Multisale EIS, 

respectively. Since 181 South Area is nearly 130 mi (209 km) from the nearest coast, the area has little 

potential for direct impact to coastal wetlands as a result of the proposed activities in that area. 

The primary impacts resulting from routine activities associated with a CPA or WPA proposed action 

that could affect wetlands and marshes include pipeline emplacement, construction and maintenance, 

navigation channel use (vessel traffic), 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 

and levee construction, which prevents necessary sedimentary processes. 

CPA Proposed Action Analysis 

The addition of the proposed routine activities associated with the inclusion of the 181 South Area in 

the CPA would have minimal effects on the coastal wetlands since the proposed action is located nearly 

130 mi (209 km) from the nearest shore. The potential for indirect impacts may exist due to the initial 

needs for shore-based supply vessel support. Only a slight increase in vessel traffic is expected to occur, 
Environmental and Socioeconomic Consequences 4-37 

but vessel size may increase due to supply needs and open sea conditions. Helicopter trips are also 

expected to increase as a result of providing timely transportation of crews to the offshore facility. 

Neither of the increases in support activity would require an expansion of onshore base support and, 

therefore, would not directly impact coastal wetlands. Existing ports, production facilities, and navigation 

channels would be used, thus eliminating the need for the expansion or construction of any facilities into 

wetland areas. 

Navigation canals have significant habitat impacts on the landscape, including significant widening. 

A reduction of widening in recent years was noted by Johnston et al. (2007), likely due to more 

aggressive management and the restoration of the canal edges to prevent erosion. Results indicate that 

management activities, including erosion protection and restoration along the edges of these canals, can 

significantly reduce canal-widening impacts on wetland loss. Impacts resulting from activities related to 

navigation canals can be mitigated with bank stabilization, and where possible, the beneficial use of 

dredged material (produced during maintenance dredging activities) to create wetland or upland habitats. 

Port Fourchon is projected to be the primary base of onshore support operations in the 181 South 

Area and can be accessed by an armored channel. Since the vessel support of a CPA proposed action will 

be utilizing primarily armored coastal channels, as well as existing offshore channels and sea lanes, 

vessel-related erosion should be minimal and the need for channel maintenance should not significantly 

increase as a result of the proposed activity. 

It is possible that up to one gas production facility may be required as a result of a CPA proposed 

action. If needed, the facility would be permitted in accordance with applicable State and Federal laws 

governing the use and protection of wetlands, as noted in the Clean Water Act, NEPA, and the applicable 

guidelines and regulations noted in the State Coastal Zone Management Program. If facility construction 

is in a wetland area, the construction will be done in such a way as to minimize and avoid impacts to 

wetlands. Unavoidable damages will be mitigated through the various Federal and State mitigation 

requirements in accordance with NEPA guidelines and the Clean Water Act regulations governing these 

actions. An expansion of an existing facility in a previously developed area is more likely than 

developing a completely new facility, which would further reduce potential impacts to wetlands. 

Zero to one pipeline landfall is projected as a result of a CPA proposed action. The construction 

of new pipelines and pipeline canals are much narrower than in the past because of advances in 

technology and improved methods of installation due to a greater awareness among regulatory agencies 

and industry. Johnston et al. (2007) found that the magnitude of impacts from OCS-related pipelines 

described is inversely proportional to the quantity and quality of mitigation techniques applied. Pipelines 

with extensive mitigation measures appeared to have minimal impacts, while pipelines not backfilled 

and/or that had spoil banks remaining after construction attributed to significant habit changes. Through 

proper construction methods, mitigation, and maintenance, impacts can be minimized or altogether 

avoided. The MMS is not a permitting agency of onshore pipelines. The permitting agencies 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 properly mitigate and monitor onshore pipeline impacts. 

If dredging is required as a result of channel maintenance or pipeline installation, the dredged 

material will be used for wetland creation or other beneficial use and will not be placed in wetlands in a 

manner that would fill or alter the hydrology of the area so that its wetland function would be lost. 

There are currently disposal sites designated for OCS-related waste products as well as oil and gas 

support facilities that are capable of supporting existing and proposed activity, including activity that 

would result from the addition of the 181 South Area (Dismukes et al., 2007). Up to one new pipeline 

landfall and up to one new gas processing plant are projected as a result of a CPA proposed action. No 

further expansion of existing onshore facilities should involve wetland development. 

Indirect impacts may occur as a result of increased maintenance dredging, channel improvements, and 

erosion control as a result of the slight increases in vessel traffic and size required to support the 181 

South Area. These impacts would be mitigated to minimal impacts since the State Coastal Zone 

Management Program guidance requires beneficial use of dredged material either for wetland creation or 

beach restoration. The addition of the 181 South Area is expected to result in a relatively minor amount 

of additional vessel trips. 
4-38 Central and Western Gulf of Mexico Multisale Supplemental EIS

WPA Proposed Action Analysis 

For a proposed action in the WPA, 0-1 pipeline landfalls are projected. Up to 2 km (1.2 mi) of 

onshore pipeline are projected to be constructed in coastal Texas in support of a WPA proposed action. 

Through proper construction methods, mitigation, and maintenance, impacts can be minimized or 

altogether avoided. The MMS is not a permitting agency of onshore pipelines. The permitting agencies 

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 properly mitigate and monitor onshore pipeline impacts. 

The Multisale EIS presented estimates of wake erosion due to vessel traffic as a result of a proposed 

action. However, these estimates do not consider that OCS operations primarily stage from armored 

channels like Port Fourchon; therefore, impacts from vessel traffic related to a WPA proposed action 

should remain minimal. For non-armored channels, wetland loss resulting from canal widening can be 

significantly reduced through management activities, including erosion protection and restoration along 

the edges of these canals. Impacts resulting from activities related to navigation canals can be mitigated 

with bank stabilization, and where possible, the beneficial use of dredged material (produced during 

maintenance dredging activities) to create wetland or upland habitats. 

There are no new navigation channels or pipeline canals planned for construction as a result of WPA 

activity; however, a WPA proposed action may contribute to maintenance of existing navigation 

channels. Dredged material disposal associated with these activities would be used either beneficially for 

wetland restoration, beach nourishment, or the construction or repair of erosion control features (e.g., 

jetties, finger dikes, groins etc). 

Because of wetland protection regulations, no new dredged material disposal sites will be developed 

in wetlands. Some seepage from disposal sites into adjacent wetland areas may occur and result in 

damage to wetland vegetation. State requirements are expected to be enforced to prevent and correct such 

occurrences. 

The one gas processing plant that may be constructed as a result of a WPA proposed action is not 

likely to be developed in a sensitive wetland area due to the current Federal and State permit process and 

wetland regulations. It is a more likely scenario that an expansion of an existing facility in a previously 

disturbed or developed area would be preferable to developing a new site and facility. If it is necessary to 

develop a wetland site, the area must be developed and mitigated in accordance with both the State and 

Federal regulations that are consistent with and comply with NEPA, the Clean Water Act, and State 

Coastal Zone Management Programs. Under these regulatory programs, the State, along with COE, are 

responsible for mitigation of the unavoidable impacts to wetlands. 

Summary and Conclusion 

In summary, the effects to coastal wetlands from the primary impact-producing factors associated 

with a CPA or WPA proposed action are expected to be low. The loss of 0-8 ha (0-20 ac) of wetlands 

habitat is estimated as a result of 0-2 km (0-1.2 mi) of new pipelines projected as a result of a proposed 

action. Maintenance dredging of navigation channels and canals is expected to occur with minimal 

impacts; a proposed action is expected to contribute minimally to the need for this dredging. Alternative 

dredged material disposal methods can be used to enhance and create coastal wetlands. Vessel traffic 

associated with a proposed action is expected to contribute minimally to the erosion and widening of 

navigation channels and canals. Overall, impacts from pipeline emplacement is expected to be low and 

could be further reduced through mitigation, such as horizontal, directional (trenchless) drilling 

techniques to avoid damages to these sensitive habitats. Secondary impacts to wetlands would be 

primarily from vessel traffic corridors and should remain minimal, considering OCS operations primarily 

stage service bases with armored channels like Port Fourchon.

4.1.3.2.3. Impacts of Accidental Events 

Background/ introduction 

A detailed description of the accidental impacts on wetlands can be found in Chapter 4.4.3.2 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 
Environmental and Socioeconomic Consequences 4-39 

The primary, accidental impact-producing factors with the potential to impact the coastal wetlands are 

generally oil spills and most specifically and significantly the coastal and inland spills adjacent to the 

coastal wetlands. Chapter 4.3 of the Multisale FEIS has a complete discussion of oil spills and the 

various impacting factors and risk analysis while Chapter 4.4.3.2 of the Multisale EIS specifically 

addresses the types and severity of wetland impacts. While there are concerns that offshore spills may 

contribute to wetland damage because of the distance offshore of these Federal facilities, the possibility of 

spills reaching coastal wetlands with the toxicity to significantly impact the coastal wetlands is low. The 

toxicity of the spilled oils is greatly reduced or eliminated by weathering, wave action, and the use of 

dispersants if used to contain the spill in the offshore environment. 

Although the probability of occurrence is low, the greatest threat to wetland habitat is from an inland 

spill resulting from a vessel accident or pipeline rupture. Coastal or inland spills are of greatest concern 

since these spills would be in much closer proximity to the wetland resource. While a resulting slick may 

cause minor impacts to wetland habitat, the equipment and personnel used to clean up a slick over the 

impacted area may 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 bottomdisturbing equipment would be needed to avoid or minimize those impacts. The fate and behavior of oil 

spills, availability and adequacy of oil-spill containment and cleanup technologies, oil-spill cleanup 

strategies, impacts of various oil-spill cleanup methods, effects of weathering on oil spills, toxicological 

effects of fresh and weathered oil, air pollution associated with spilled oil, and short-term and long-term 

impacts of oil on wetlands are additional accidental concerns. Numerous investigators have studied the 

immediate impacts of oil spills on wetland habitats in the Gulf area. Often, seemingly contradictory 

conclusions are generated from these impact assessments, which can be explained by differences in oil 

concentrations contacting vegetation, the chemical composition of the oil spilled, vegetation type and 

density, season of year, preexisting stress level on the vegetation, soil types, water levels, weather, and 

numerous other factors. In overview, the 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 (Webb et al., 1985; Alexander and Webb, 1987; Lytle, 1975; 

Delaune et al., 1979; Fischel et al., 1989). 

The already eroded Louisiana barrier island chain was significantly damaged by Hurricanes Katrina 

and Rita, thus further lowering the protection afforded the mainland marshes and beaches from oil spills 

that these barrier features previously provided. Breton NWR, one of the islands comprising the hard-hit 

Chandeleur barrier island chain, lost approximately 50 percent of its landmass (Hall, Congressional 

testimony, 2006). In addition, the coastal barrier islands along the Mississippi/Alabama coast were 

severely degraded by Hurricanes Katrina and Ivan. Approximately 200 ac (81 ha) on Petit Bois, Horn, 

Ship, and Cat Islands were destroyed, leaving the remaining acreage with a drastically reduced 

functionality (Barbour, 2006). With the reduced protection of the barrier islands, there is a greater 

potential for the oiling of coastal wetlands. 

CPA Proposed Action Analysis 

Wetlands in the CPA follow the Louisiana, Mississippi, and Alabama coastlines. The degraded 

barrier islands off the Louisiana and Mississippi coasts still afford some reduced degree of protection 

from offshore spills after being degraded by Hurricanes Katrina and Rita. The greatest threat to coastal 

wetlands would be from inland 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 being contacted by spills from 

operations related to a CPA proposed action. Spills that could occur in coastal waters from a proposed 

action support operations are estimated at 46-102 spills for a CPA proposed action over its 40-year life. 

Offshore oil spills are much less likely to contact coastal wetlands than are inshore spills because of the 

potential for spills resulting from inland pipelines and vessel accidents are in close proximity to the 

wetland resources. The probabilities of an offshore spill ≥1,000 bbl occurring and contacting 

environmental features are described in Chapter 4.3.1.8 of the Multisale EIS. Eight parishes in Louisiana 

and two counties in Texas have a chance of spill contact that is >0.5 percent. For these parishes and 

counties, the chance of an OCS offshore spill ≥1,000 bbl ranges from 1 to 16 percent. In Louisiana, the 

Deltaic Plain area has the highest risk from a CPA proposed action (Chapter 4.3.1 of the Multisale EIS). 
4-40 Central and Western Gulf of Mexico Multisale Supplemental EIS

As explained in Chapter 3.2.1, the incremental increase in oil production from the addition of the 181 

South Area is not expected to result in an overall increase in the numbers of oil spills ≥1,000 bbl likely to 

occur as a result of a CPA proposed action. Activity that would result from the addition of the 181 South 

Area would cause a negligible increase in the risk of a large spill occurring and contacting wetland 

habitats. Overall, impacts to wetland habitats from an oil spill associated with activities related to a CPA 

proposed action would be expected to be low and temporary. 

WPA Proposed Action Analysis 

Wetlands in the WPA are concentrated landward of the barrier beaches of Texas. Estuarine marshes 

largely occur as continuous and discontinuous bands around bays, lagoons, and river deltas. Broad 

expanses of emergent wetland vegetation do not commonly occur south of Baffin Bay because of the arid 

climate and hypersaline waters. In the vicinity of southern Padre Island, marshes are minimal and 

unstable, compared with the more northern Gulf. In Tamaulipas, marshes behind the barrier islands are 

even less abundant than seen in the vicinity of Padre Island. Detailed descriptions of these marshes and 

the impacts of oil on them can be found in Chapters 3.2.1.2.and 4.4.3.2 of the Multisale EIS, respectively. 

The McFaddin Complex comprises approximately 60,000 ac (24,280 ha) of coastal marsh (i.e., fresh, 

intermediate, and brackish), coastal prairie (non-saline and saline), coastal woodlands, and beach/ridge 

habitats in Jefferson and Chambers Counties in southeast Texas (USDOC, NMFS, 2007a) The NWR’s in 

southeast Texas suffered wetland habitat loss, primarily as a result of wave erosion, during Hurricane 

Rita. Impacts to three Federal refuges were estimated to include marsh loss of more than 75 ac, (30 ha) 

approximately 15,000 ac (6,070 ha) of marsh under increased threat by future storms, and erosion losses 

along 20 mi (32 km) of shoreline (USDOC, NMFS, 2007a). Due to the degraded shorelines and the 

reduction in elevation and vegetation on the Texas barrier islands that previously afforded some 

protection to these coastal fringe marshes, the vulnerability of these wetlands to oil spills has increased. 

These wetlands are generally more susceptible to contact by inshore spills, which have a low 

probability of occurrence. Inshore vessel collisions may release fuel and lubricant oils, and pipeline 

ruptures may release crude and condensate oil. Although the impact may occur generally over coastal 

regions, the impact has the highest probability of occurring in Galveston and Matagorda Counties in 

Texas in the vicinities where WPA oil is handled. Spills that could occur in coastal waters from proposed 

action support operations are estimated at 15-34 spills for a WPA proposed action over its 40-year life. 

Offshore oil spills are much less likely to contact these wetlands than are inshore spills because these 

areas are generally protected by barrier islands (although reduced due to storm damage), peninsulas, sand 

spits, and currents. The probabilities of an offshore spill ≥1,000 bbl occurring and contacting 

environmental features are described in Chapter 4.3.1.8 of the Multisale EIS. Six counties in Texas have 

a chance of spill contact that is >0.5 percent. For these counties, the chance of an OCS offshore spill 

≥1,000 bbl occurring and reaching the shoreline ranges from 1 to 5 percent as the result of a proposed 

action over its 40-year life. Weathering, wave action, and the use of offshore dispersants would reduce 

the amount of oil that would reach wetland areas and would result in minimal impacts. 

Summary and Conclusion 

Because of the location of the coastal wetlands in relation to a CPA or WPA proposed action, inshore 

spills pose the greatest threat. Such spills may result from either vessel collisions that release fuel and 

lubricants or from pipelines that rupture. Nearshore spills are much smaller in volume and weather 

quickly. Should they occur, these impacts would be considered short term in duration and minor in 

scope. If the spill makes landfall and a cleanup proceeds with approved procedures, impacts to wetlands 

would be minimal due to the weathered condition of the oil and the containment and cleanup techniques. 

While a resulting slick may cause minor impacts to wetland habitat, the equipment and personnel used to 

clean up a slick over the impacted area may 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 

The MMS has reexamined the analysis for wetland resources presented in the Multisale EIS, based on 

the additional information presented above. This new information supports the previous assessments 

contained in the Multisale EIS, which is incorporated by reference. No significant new information was 
Environmental and Socioeconomic Consequences 4-41 

found that would alter the overall conclusion that impacts on the wetland resources from accidental 

impacts associated with a CPA or WPA proposed action would be minimal. 

4.1.3.2.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts upon wetlands can be found in Chapter 4.5.3.2 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

Impacts from residential, commercial, and agricultural and silvicultural (forest expansion) 

developments are expected to continue in coastal regions around the Gulf. Existing regulations and 

development permitting procedures indicate that development-related wetland loss may be slowed and 

that very few (0-1 including the 181 South Area) new onshore OCS facilities, other than pipelines (0-1 

landfall including the 181 South Area), will be constructed in wetlands. Impacts from State onshore oil 

and gas activities are expected to occur as a result of dredging for new canals, maintenance and usage of 

existing rig access canals and drill slips, and preparation of new well sites. Locally, subsidence may be 

due to the extraction of large volumes of oil and gas from subsurface reservoirs, although subsidence 

associated with this factor seems to have slowed greatly over the last three decades as the reservoirs are 

depleted. Indirect impacts from dredging new canals for State onshore oil and gas development (Chapter 

4.1.3.3.3 of Multisale EIS) and from the maintenance of the existing canal network is expected to 

continue. Maintenance dredging of the OCS-related navigation channels accounts for 10 percent of the 

dredged material produced. Insignificant adverse impacts upon wetlands from maintenance dredging are 

expected because the large majority of the material would be disposed upon existing disposal areas. 

Alternative dredged material 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 reduce 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 a low of 9 percent (Britsch and Dunbar 1993) to 33 percent 

(Penland et al., 2001a and b) to estimates of greater than 50 percent (Turner et al., 1982; Bass and Turner, 

1997; Scaife et al., 1983). A panel review of scientific evidence suggests that wetland losses directly 

attributable to all 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 Fourchon Channel to accommodate larger, OCS-related service vessels 

has occurred within a saline marsh environment and will afford the opportunity for the creation of 

wetlands with the dredged materials. Also, deepening the Corpus Christi and Houston Ship Channels is 

non-OCS related and should also afford the opportunity to create wetlands with dredged material. 

Dredging 

Maintenance dredging of navigation channels and canals is expected to occur with minimal impacts; a 

CPA or WPA proposed action is expected to contribute minimally to the need for this dredging. 

Alternative dredged material disposal methods can be used to enhance and create coastal wetlands. A 

CPA or WPA proposed action is expected to use existing navigation channels and 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 disposed 

upon existing disposal areas. Alternative dredged material disposal methods can be used to enhance and 

create coastal wetlands. Depending upon the regions and soils through which they were dredged, 
4-42 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 a CPA or WPA proposed action are 

located along armored canals and waterways, thus minimizing marsh loss. 

Navigation Channels and Canals 

The effects of pipelines, canal dredging, navigation activities on wetlands are described in Chapters 

4.2.1.1.3.2 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 and 

WPA are expected to require some level of dredging, channel deepening, and maintenance of access 

canals. Onshore activity that would further accelerate wetland loss would include additional access 

channels, drill slips, and preparation required to construct new well sites and expand or construct 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., 2007). Impacts resulting from activities related 

to navigation canals can be mitigated with bank stabilization, and where possible, the beneficial use of 

dredged material (produced during maintenance dredging activities) to create wetland or upland habitats. 

Pipelines 

Modern pipeline installation methods and impacts are described in Chapters 4.1.1.8.1 and 4.1.2.1.7 of 

the Multisale EIS. While impacts are greatly reduced by mitigation techniques, remaining impacts may 

include expansion of tidal influence, saltwater intrusion, hydrodynamic alterations, erosion, sediment 

transport, and habitat conversion (Cox et al., 1997; Morton, 2003; Ko and Day, 2004). The majority 

(over 80%) of OCS-related direct landloss is estimated to be from OCS pipelines (Turner and Cahoon, 

1988). Since the beginning of OCS activities in the Gulf of Mexico, approximately 15,400 km (9,563 mi) 

of OCS pipelines have been constructed in Louisiana 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., 2007). The total length 

of non-OCS pipelines through wetlands is believed to be approximately twice that of the Gulf OCS 

Program, or about 15,285 km (9,492 mi) for 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 do not result in new landfalls. Pipeline maintenance activities that disturb 

wetlands are very infrequent and are mitigated to the maximum extent practicable. 

The widening of OCS pipeline canals does not appear to be an important factor contributing to OCSrelated direct landloss. This is because few pipelines are open to navigation, and the impact width does 

not appear to be significantly different than that for open pipelines closed to navigation. As a result of the 

OCS Program (2007-2046), up to 64-94 km (40-58 mi) of onshore pipeline are projected to be 

constructed in the CPA and WPA. The predicted landloss (based on an average of 4 ha (9 ac) of 

conversion to open water per linear kilometer of pipeline (300-m or 984-ft buffer zone) from the 

estimated 64-94 km (40-58 mi) of new OCS pipeline construction ranges from approximately 256-376 ha 

(633-929 ac) total over the 40-year analysis period. Based on the projected coastal Louisiana wetlands 

loss of 132,607 ha (327,679 ac) for the years 2000-2040 (Barras et al., 2003), this represents about 0.2 

percent of the total expected wetlands loss for that time period. 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 due to a greater awareness among regulatory agencies and industry (Johnston et al., 2007). 

The magnitude of impacts from OCS-related pipelines is inversely proportional to the quantity and 

quality of mitigation techniques applied. Pipelines with extensive mitigation measures appeared to have 

minimal impacts, while pipelines not backfilled and/or that had spoil banks remaining after construction 

attributed to significant habit changes. Through proper construction methods, mitigation, and 

maintenance, impacts can be minimized or altogether avoided. The MMS is not a permitting agency of 
Environmental and Socioeconomic Consequences 4-43 

onshore pipelines. The permitting agencies 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 oil spills will continue with coastal spills in the inland or coastal waters creating the 

greatest concern for coastal wetlands due to their proximity to these vegetated areas. Offshore spills are 

less likely to reach the coastal wetlands in a fully toxic condition due to weathering and the interception 

of spills by barrier islands. However, due to the reduced elevation and erosion of these barriers by 

Hurricanes Katrina and Rita, the level of protection afforded the mainland has been greatly reduced but 

not quantified (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, contributing less than 0.1 L/m2

 on wetland surfaces. Any 

adverse impacts that may occur to wetland plants are expected to be very short lived, probably less than 1 

year. Coastal OCS spills could occur as a result of pipeline accidents and barge or shuttle tanker 

accidents during transit or offloading. The frequency, size, and distribution of all coastal spills are 

provided in Chapter 4.1.3.4.of the Multisale EIS. Impacts of OCS coastal spills are also discussed in 

Chapter 4.3.1.6 of the Multisale EIS). Non-OCS spills can occur in coastal regions as a result of import 

tankers, coastal oil production activities, and petroleum product transfer accidents. Their distribution is 

believed to be similar to that described in Chapter 4.3.1 of the Multisale EIS. Numerous wetland areas 

have declined or have been destroyed as a result of oil spills caused by pipeline breaks or tanker 

accidents. The oil stresses the wetland communities, making them more susceptible to saltwater 

intrusion, drought, disease, and other stressors (Ko and Day, 2004). Spills that occur in or near 

Chandeleur or Mississippi Sounds could potentially impact 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, and they 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. Because the inlets that connect Mississippi Sound with the marsh-fringed estuaries and 

lagoons within the islands are narrow, a small percentage of the oil that contacts the Sound side of the 

islands will 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 

marshes (Morton, 2003). Discharging OCS-related produced water into inshore waters has been 

discontinued and all OCS-produced waters transported to shore will either be injected or disposed of in 

Gulf waters and will not affect coastal wetlands (Chapter 4.1.1.4.2 of the Multisale EIS).

The numbers and sizes of coastal spills are presented in Table 4-13 of the Multisale EIS. About 95 

percent of these spills are projected to be from non-OCS-related activity. Of coastal spills <1,000 bbl, the 

assumed size is 5 bbl; therefore, the great majority of coastal spills would affect a very small area and 

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. A total of 4-5 large 

(≥1,000 bbl) offshore spills are projected to occur annually from all sources Gulfwide. Of these offshore 

spills, one is estimated to occur every 1 to 2 years from the Gulfwide OCS Program (Table 4-15 of the 

Multisale EIS). A total of 1,550 to 2,150 smaller offshore spills (<1,000 bbl) are projected annually 

Gulfwide. The majority of these spills (1,350-1,900) would originate from OCS Program sources. 

Chapter 4.3.1 2 in the Multisale EIS describes projections of future spill events in more detail. The OCSrelated spills in the cumulative area are expected to cause a 1 percent or less decrease in fish resources. 

The impact of non-OCS-related spills in this area is expected to cause a 10 percent or less decrease in fish 

resources. Due the proximity of the 181 South Area and the current oil cleanup techniques, the chance of 

an oil spill making contact with coastal or barrier island wetlands is minimal. 
4-44 Central and Western Gulf of Mexico Multisale Supplemental EIS

Development of Wetlands 

The development of wetlands for agricultural, residential, and commercial uses will continue but with 

more regulatory and planning constraints. Wetland damage will be minimized through the 

implementation of Coastal Zone Management Guidelines, along with COE regulatory guidelines for 

wetland development combined with various State and Federal coastal development programs such as 

CIAP, and Louisiana’s CWPPRA and Louisiana Coastal Protection and Restoration Project (LACPR) 

programs. 

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 will 

either be injected or disposed of in Gulf waters and will not affect coastal wetlands (Chapter 4.1.1.4.2 of 

Multisale EIS). Dredged material will be deposited either in existing approved discharge sites or will 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 subsidence through compaction 

of Holocene strata (the rocks and deposits from 10,000 years ago to present), as well as human factors 

such as onshore oil and gas extraction, groundwater extraction, drainage of wetland soils, and burdens 

placed by buildings roads and levees. 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 marsh or changes in marsh types and plant 

diversity (Spalding and Hester, 2007). This study shows that the very structure of coastal wetlands will 

likely be altered by sea-level rise, as community shifts will be governed by the responses of individual 

species to new environmental conditions. Flood control and channel training along the Mississippi River 

will 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 Gulf Coast, but 

planned for the Louisiana and Texas coast, is the preparation of salt domes for 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). 

Summary and Conclusion 

Wetlands are most vulnerable to inshore or nearshore oil spills but are also at risk for offshore spills 

with risks minimized by distance, time, sea conditions, and weather. Spill sources include vessel 

collisions, pipeline breaks, and shore-based transfer and refining facilities and production facilities. The 

wetlands associated with a CPA or WPA 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 reduced post-Hurricane Katrina), and product transportation through existing 

pipelines or pipeline corridors. Offshore spills related to a CPA or WPA proposed action are not expected 

to reach wetlands in toxic conditions due to distance and weathering. If they do reach shore, only light 

localized impacts to inland wetlands would occur. If any spills occur, they will likely be small and at 

service bases or other support facilities, and they would not be expected to affect wetlands. 

While landloss will continue from saltwater intrusion, the State of Louisiana, along with COE, has 

implemented freshwater diversion projects to minimize the effect of this saltwater-induced landloss. 

Landloss will continue from vessel traffic; however, based on the minimal increase in traffic caused by a 

proposed action, loss would be minimal. A CPA or WPA proposed action will not require any channel 

maintenance; therefore, no additional wetland loss would result from dredged material disposal. If 

dredged material disposal is required, it may be beneficially used for marsh creation. Disposal of OCS 

wastes and drilling by-products will be delivered to existing facilities. Because of existing capacity, no 

additional expansion into wetland areas will be expected. 

Development pressures in the coastal regions of Louisiana, Mississippi, Alabama, and Florida have 

caused the destruction of large areas of wetlands. In coastal Louisiana, the most destructive 
Environmental and Socioeconomic Consequences 4-45 

developments have been the oil and gas industry projects, which have resulted in the dredging of huge 

numbers of access channels. In Mississippi, Alabama, and Florida, agricultural, residential, and 

commercial developments have caused the most destruction of wetlands. In Florida, recreational and 

tourist developments have been particularly destructive. These trends are expected to continue. During 

the period of 2001-2040, between 248,830 and 346,590 ha (614,872 and 856,443 ac) of wetlands will be 

lost from the Louisiana coastal zone and 1,600-2,000 ha (647-809 ac) will 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 will continue eroding, largely at the 

expense of wetlands; however, channel armor may be added at a later date. 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. The modern construction techniques and mitigative 

measures result in zero (0) to negligible impacts on wetland habitats. The current MMS/USGS pipeline 

study (Johnston et al., 2007) is continuing to develop models that will aid in quantifying habitat loss 

associated with OCS activities. A CPA and WPA proposed action represents about 1 and 3-4 percent, 

respectively, of the OCS impacts that will occur over the 40-year analysis period. Impacts associated 

with the 181 South Area are a minimal part of the overall OCS impacts that will occur during the lease 

period. The cumulative effects of human and natural activities in the coastal area have severely degraded 

the deltaic processes and have shifted the coastal area from a condition of net land building to one of net 

landloss. Deltaic Louisiana is expected to continue to experience the greatest loss of wetland habitat. 

Wetland loss is also expected to continue in coastal Texas, Mississippi, Alabama, and Florida, but at 

slower rates. The incremental contribution of any single proposed action to the cumulative impacts on 

coastal wetlands is expected to be very small. 

4.1.3.3. Seagrass Communities 

The MMS has reexamined the analysis for seagrass communities presented in the Multisale EIS, 

based on the additional information presented below and the addition of the 181 South Area to the 

proposed CPA sale area. No significant new information was found that would alter the impact 

conclusion for seagrass communities presented in the Multisale EIS. The 181 South Area is located 

nearly 130 mi (209 km) from the nearest coast and is projected to result in a relatively minor amount of 

additional activity; therefore, no significant additional impacts on seagrass communities are projected as a 

result of the inclusion of the 181 South Area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Turbidity impacts from pipeline installation and maintenance 

dredging associated with a CPA or WPA proposed action would be temporary and localized. The 

increment of impacts from service vessel transit associated with a CPA or WPA 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 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. A CPA or WPA proposed action would cause a minor incremental contribution to cumulative 

impacts due to dredging from maintenance of channels. 

4.1.3.3.1. Description of the Affected Environment 

A detailed description of seagrass communities can be found in Chapter 3.2.1.3 of the Multisale EIS. 

The following is a summary of the information presented in the Multisale EIS, which incorporates new 

information found since publication of the Multisale EIS. 

Three million hectares (7,400,000 ac) of submerged seagrass beds are estimated to exist in exposed, 

shallow coastal waters of the northern Gulf of Mexico. An additional 166,000 ha (410,000 ac) are found 

in protected, natural embayments and are not considered exposed to OCS impacts. The area off Florida 

contains approximately 98.5 percent of all coastal seagrasses in the northern Gulf of Mexico; Texas and 
4-46 Central and Western Gulf of Mexico Multisale Supplemental EIS

Louisiana contain approximately 0.5 percent. Mississippi and Alabama have the remaining 1 percent of 

seagrass beds. No seagrasses occur offshore in the CPA and WPA; the 181 South Area has no seagrasses 

because of its great depth and distance from shore. Primarily because of low salinity and high turbidity, 

robust seagrass beds along the Gulf of Mexico are found only within a few scattered, protected locations. 

These inshore seagrasses serve as important nursery and feeding habitat for many species of fish and 

birds. Seagrasses in the WPA are widely scattered beds in shallow, high-salinity coastal lagoons and 

bays. The most extensive seagrass beds in Texas are located behind barrier islands in south Texas. 

Lower-salinity submerged aquatic vegetation grows in the upper portions of some estuaries and in coastal 

lakes and rivers. 

In the CPA, the turbid waters and soft, highly organic sediments of Louisiana’s estuaries and offshore 

areas limit distribution of higher salinity seagrass beds. Consequently, only a few areas in coastal 

Louisiana, mostly in Chandeleur Sound, support seagrass beds. These beds have been repeatedly 

damaged by the natural processes of transgression from hurricane overwash of the barrier islands. Over 

time, seagrass recolonizes the new sand flats on the shoreward side, and the natural processes of sand 

movement rebuild the islands. However, the frequency of recent storms has led to a substantial reduction 

and change of seagrass habitat in the CPA. See Chapter 3.2.1.3 of the Multisale EIS for more information 

about hurricane impacts to seagrasses. 

A search was conducted for new information published since completion of the Multisale EIS. 

Various Internet sources were examined to determine any recent information regarding seagrass. Sources 

investigated include the USGS National Wetlands Research Center, the USGS Gulf of Mexico Integrated 

Science Data Information Management System, Gulf of Mexico Alliance workshops in the spring of 

2007, Florida Department of Environmental Protection, USEPA, and coastal universities. Other sites 

were found through general Internet searches. 

New information was discovered from these information sources. The workshops held by the Gulf of 

Mexico Alliance in the spring of 2007 revealed some new research and new collations of old information 

(May, 2007; Vittor, 2007; Hardegree, 2007). May (2007) discussed the distribution of seagrass in 

southeastern Mississippi waters, finding some burial of seagrass after Hurricane Katrina, seasonal 

fluctuation of Ruppia maritima, and persistent Halodule wrightii. Vittor (2007) discussed seagrass in 

Mississippi Sound and Alabama based on four aerial surveys from 1940 to 2002. His analysis showed 

seagrass declines of from 52 to 88 percent in these areas since 1940. Hardegree (2007) highlighted 

declines in seagrass in Christmas Bay and the Lower Laguna Madre. He also analyzed propeller scarring, 

recovery, and regulation. In 2006, a master’s thesis on seagrass communities in Biloxi Marsh, 

Mississippi reported fish communities at sites denuded of seagrass by Hurricane Katrina resembled those 

of sites with no seagrass before the hurricane (Maiaro, 2007). This new information on seagrass supports 

and reinforces the description of the environment presented in the Multisale EIS. 

The distribution of seagrass beds in coastal waters of the Gulf of Mexico have diminished during 

recent decades. Primary factors believed to be responsible include dredging, dredged material disposal, 

coastal development including shore armoring, trawling, water quality degradation, hurricanes, a 

combination of flood protection levees that have directed freshwater and sediments away from wetlands, 

saltwater intrusion that moved growing conditions closer inland, and infrequent freshwater diversions 

from the Mississippi River into coastal areas during flood stage. 

4.1.3.3.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on seagrass communities is presented in Chapters 4.2.2.1.3.3 and 4.2.1.1.3.3 of the 

Multisale EIS, respectively. The routine activities associated with a proposed action that would impact 

seagrass communities include construction of pipelines, vessel traffic, and dredging. 

Jetting of trenches for pipeline burial in water shallower than 200 ft (60 m) displaces sediments. The 

denser sediments fall out of suspension quickly; the finer sediments that decrease water clarity remain in 

suspension longer. Although the majority of materials resuspended by jetting return to the water bottom 

within a few feet or meters of the trench, lighter materials can be carried for several kilometers. The COE 

and State agencies review pipeline permits and require mitigation of turbidity by using screens and other 
Environmental and Socioeconomic Consequences 4-47 

confinement methods, turbidity monitoring, surveys for locating seagrass beds, and immediate action 

taken to correct turbidity problems. Adverse effect on seagrass would be temporary and localized. 

Seagrass would be impacted by navigation traffic due to wake erosion and prop wash. Most OCS 

support vessels have displacement hulls and create little wake. However, sediment is suspended in the 

water column by prop wash in shallow channels. Vessels that vary their inland route from established 

navigation channels can directly scar beds of submerged vegetation. 

Dredging temporarily increases turbidity levels and reduces light penetration through the water 

column in the vicinity of the dredging and disposal of materials. Reduced light has been linked to 

reductions of both seagrass cover and productivity (Orth and Moore, 1983; Kenworthy and Haunert, 

1991; Dunton, 1994; Czerny and Dunton, 1995). Dredging has been determined to be one of the major 

causes of light reduction that results in changes in seagrass cover, composition, and biomass. Changes in 

species composition are mostly the result of natural processes (i.e., succession) but have been prompted 

by moderation of salinity resulting from dredging. 

CPA Proposed Action Analysis 

The routine activities associated with a CPA proposed action that would impact seagrass communities 

include installation of pipelines in coastal waters, vessel traffic, and maintenance dredging of navigation 

canals. The 181 South Area would contribute incrementally to the amount of vessel traffic and required 

maintenance dredging. 

Up to one new pipeline is projected to be installed in State waters as a result of a CPA proposed 

action. A new installation would temporarily increase the local total suspended solids in the water. The 

COE and State permits would require turbidity mitigation, monitoring, surveys to locate grassbeds, and 

immediate correction of problems. Approved pipeline routes would avoid seagrass communities. The 

effects would be temporary and localized. 

Service-vessel round trips projected for a CPA proposed action are 119,000-241,000 trips over the 

life of a proposed action. Based on current service-base usage, it is assumed the majority of these trips 

would transit Louisiana’s coastal waters. The number of service-vessel trips projected annually for a 

CPA proposed action would represent less than 1 percent of the total annual traffic on these OCS-related 

waterways. Seagrasses in Louisiana are rare to nonexistent in areas around Port Fourchon and other high 

traffic areas that may be frequented by service vessels. Vessel traffic would have little to no impact on 

seagrass communities. See Chapter 4.1.1.8.4 of the Multisale EIS for information about vessel traffic. 

Dredging resuspends sediments and increases turbidity in nearby coastal waters. A CPA proposed 

action would contribute to maintenance dredging of existing navigation canals. The increment would be 

less than 1 percent, equal to the increment in vessel traffic for the navigation canals. Maintenance 

dredging would temporarily increase turbidity levels in the vicinity of dredging and disposal of materials. 

No new navigation channels are expected to be dredged as a result of a CPA proposed action. Due to the 

long distance from shore (130 mi or 209 km), the 181 South Area would be serviced primarily by large 

vessels with a deep draft. This would add disproportionately to use of deep navigation channels. See 

Chapters 4.1.2.1.9, 4.1.3.3.3, and 4.2.2.1.3.3 of the Multisale EIS for information about dredging and 

navigation channels. 

WPA Proposed Action Analysis 

The routine activities associated with a WPA proposed action that would impact seagrass 

communities include installation of pipelines in coastal waters, vessel traffic, and maintenance dredging 

of navigation canals. 

Up to one new pipeline is projected to be installed in State waters as a result of a WPA proposed 

action. A new installation would temporarily increase the local total suspended solids in the water. The 

COE and State permits would require turbidity mitigation, monitoring, surveys to locate grassbeds, and 

immediate correction of problems. Approved pipeline routes would avoid seagrass communities. The 

effects would be temporary and localized. 

Service-vessel round trips projected for a WPA proposed action are 94,000-155,000 trips over the life 

of a proposed action. The number of service-vessel trips projected annually for a WPA proposed action 

would represent less than 1 percent of the total annual traffic on these OCS-related waterways. 

Navigation canals and other areas of high vessel traffic experience constant high turbidity. Seagrass beds 
4-48 Central and Western Gulf of Mexico Multisale Supplemental EIS

near these areas will have already adjusted to turbid conditions. Vessel traffic related to a WPA proposed 

action would have little to no impact on seagrass communities. See Chapter 4.1.1.8.4 of the Multisale 

EIS for information about vessel traffic. 

Dredging resuspends sediments and increases turbidity in nearby coastal waters. A WPA proposed 

action would contribute to maintenance dredging of existing navigation canals. The increment would be 

less than 1 percent, equal to the increment in vessel traffic for the navigation canals. Maintenance 

dredging would temporarily increase turbidity levels in the vicinity of dredging and disposal of materials. 

No new navigation channels are expected to be dredged as a result of a WPA proposed action. See 

Chapters 4.1.2.1.9, 4.1.3.3.3, and 4.2.1.1.3.3 of the Multisale EIS for information about dredging and 

navigation channels. 

Summary and Conclusion 

The routine activities associated with a CPA or WPA proposed action that would impact seagrasses 

include installation of pipelines in coastal waters, maintenance dredging of navigation canals, and vessel 

traffic. Turbidity impacts from pipeline installation and maintenance dredging would be temporary and 

localized. Pipeline routes would avoid seagrass beds. The increment of impacts from service-vessel 

transit would be minimal. 

The MMS has reexamined the analysis for seagrasses presented in the Multisale EIS based on the 

additional information presented above. No significant new information was found that would alter the 

overall conclusion that impacts on seagrasses from routine activities associated with a CPA or WPA 

proposed action would be minimal. Because the 181 South Area is nearly 130 mi (209 km) from the 

nearest coast, its inclusion would add a minimal increment to the impacts on seagrasses. 

4.1.3.3.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts upon seagrass communities can be found in Chapter 

4.4.3.3 of the Multisale EIS. The following is a summary of the information presented in the Multisale 

EIS, which incorporates new information found since publication of the Multisale EIS. 

Accidental impacts associated with a CPA or WPA proposed action that could adversely affect 

seagrass beds include oil spills associated with the transport and storage of oil (Chapter 4.3.1 of the 

Multisale EIS). The degree of impact from oil spills depends on the location of the spill, oil-slick 

characteristics, water depth, currents, and weather. Offshore oil spills that occur in the proposed action 

areas are much 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. In this region of the 

Gulf, seagrass beds remain submerged due to the short range of the micro-tides (usually about 0.5 m or 

1.64 ft; Thieler and Hammar-Klose, 2006). During calm weather, oil on the sea surface would not contact 

most seagrass directly. Rough weather can produce increased mixing that would bring oil below the 

surface and result in oil contacting seagrass communities directly. Their regenerative roots and rhizomes 

are buried in the water bottom, where they are further protected (Chapter 3.2.1.3 of the Multisale EIS). 

Should an oil slick pass over these seagrass communities, damage would occur if an unusually low tide 

were to occur, causing contact between the two. This is more likely in the winter with cold fronts from 

the north accompanied by a strong north wind. A more damaging scenario would be that a slick might 

pass over and remain over a submerged bed of vegetation in a protected embayment during typical fairweather conditions. This would reduce light levels in the bed. If light reduction continues for several 

days, chlorophyll content in the leaves will be reduced (Wolfe et al., 1988), causing the grasses to yellow 

and reducing their productivity. Shading by an oil slick of the sizes described should not last long enough 

to cause mortality, depending upon the slick thickness, currents, weather, and the nature of the 

embayment. In addition, a slick that remains over seagrass beds in an embayment also will reduce or 

eliminate oxygen exchange between the air and the water of the embayment. Oxygen depletion is a 

serious problem for seagrasses (Wolfe et al., 1988). If currents flush little oxygenated water between the 

embayment and the larger waterbody and if the biochemical oxygen demand (BOD) is high, as it would 

be in a shallow water bed of vegetation, and then enhanced by an additional burden of oil, the grasses and 
Environmental and Socioeconomic Consequences 4-49 

related epifauna will be stressed and perhaps suffocated. In this situation, the degree of suffocation will 

depend upon the reduced oxygen concentration and duration of those conditions. Oxygen concentrations 

and their duration depend upon currents, tides, weather, temperature, percentage of slick coverage, and 

BOD. 

Should weather conditions or currents increase water turbulence sufficiently, a substantial amount of 

oil from the surface slick will be dispersed downward into the water column. There it will adsorb to 

suspended particles in the water column, becoming less buoyant. Submerged vegetation reduces water 

velocity, promoting sedimentation among the vegetation. Typically, this oily sedimentation will not 

cause long-term or permanent damage to the seagrass communities. Some dieback of leaves would be 

expected for one growing season. In a severe case where high concentrations of hydrocarbons are mixed 

into the water column, the diversity or population of epifauna and benthic fauna found in seagrass beds 

could be impacted. Seagrass epiphytes are sessile plants that grow attached to their seagrass host; they 

play an important role in the highly productive seagrass ecosystem. The small animals, such as 

amphipods, limpets and snails, would likely show more lethal effects than the epiphytic plant species. 

Some fauna are more susceptible to oil impacts than others. Crustaceans, such as amphipods, are more 

sensitive than most molluscs. Even some species of amphipods are more sensitive than others. Species 

with higher tolerance, fast growth, or high recruitment typically recover more quickly than sensitive 

species. The lack of grazers could cause stress to the seagrass as a result of epiphyte overgrowth and 

shading. No permanent loss of seagrass habitat is projected to result from a spill unless an unusually low 

tidal event allows direct contact between the slick and the vegetation. Seagrass stands usually recover 

from oil impacts in about a year, with subsequent rapid colonization by fauna. However, it may take as 

much as 5-10 years of community succession before faunal composition resembles pre-impact conditions 

(Chan, 1977; Zieman et al., 1984; NRC, 1985 and 2003; Marshall, 1996). 

Because of the location of most submerged aquatic vegetation, inshore spills pose the greatest threat 

to them. Such spills may result from either vessel collisions that release fuel and lubricants or from 

pipelines that rupture. If an oil slick settles into a protective embayment where seagrass beds are found, 

shading may cause reduced chlorophyll production; shading for more than about 2 weeks could cause 

thinning of leaf density. Under certain conditions, a slick could reduce dissolved oxygen in an 

embayment and cause stress to the bed and associated organisms due to reduced oxygen conditions. 

These light and oxygen problems can correct themselves once the slick largely vacates the embayment 

and light and oxygen levels are returned to pre-slick conditions. 

Increased water turbulence due to storms or vessel traffic will break apart the surface sheen and 

disperse some oil into the water column, as well as increase suspended particle concentration, which will 

adsorb the dispersed oil. Typically, these situations will not cause long-term or permanent damage to the 

seagrass beds, although some dieback of leaves is projected for one growing season. Although the 

probability of their occurrence is low, the greatest threat to inland, seagrass communities would be from 

an inland spill resulting from a vessel accident or pipeline rupture. Although a resulting slick may cause 

minor impacts to the bed, equipment and personnel used to clean up a slick over shallow seagrass beds 

may generate the greatest direct impacts to the area. Associated foot traffic may work oil farther into the 

sediment than would otherwise occur. Scarring may occur if an oil slick is cleaned up over a shallow 

submerged aquatic vegetation bed where vessels, booms, anchors, and personnel on foot would be used 

and scar the bed. Close monitoring and restrictions on the use of bottom-disturbing equipment would be 

needed to avoid or minimize those impacts. As mandated by OPA 90, seagrass beds and live-bottom 

communities are expected to receive individual consideration during spill cleanup. 

CPA Proposed Action Analysis 

Seagrass beds adjacent to the CPA are restricted to small shallow areas behind barrier islands in 

Mississippi and Chandeleur Sounds and to smaller, more scattered populations elsewhere. Lower-salinity 

seagrass beds are found inland and discontinuously throughout the coastal zone of Louisiana and 

Mississippi. 

The greatest threat to seagrass communities would be from inland 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 being contacted by spills from operations related to a CPA proposed action. Spills that 
4-50 Central and Western Gulf of Mexico Multisale Supplemental EIS

could occur in coastal waters from proposed action support operations are estimated at 46-102 spills for a 

CPA proposed action over its 40-year life. 

Offshore oil spills that occur in the proposed action area are much 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. The probabilities of an offshore spill ≥1,000 bbl occurring and 

contacting environmental features are described in Chapter 4.3.1.8 of the Multisale EIS and Chapter 

3.2.1 of this SEIS. Eight parishes in Louisiana and two counties in Texas have a chance of spill contact 

that is greater than 0.5 percent. For these parishes and counties, the chance of an OCS offshore spill 

≥1,000 bbl ranges from 1 to 16 percent. In Louisiana, the Deltaic Plain area has the highest risk from a 

CPA proposed action (Chapter 4.3.1 of the Multisale EIS). 

As explained in Chapter 3.2.1, the incremental increase in oil production from the addition of the 

181 South Area is not expected to result in an overall increase in the numbers of oil spills ≥1,000 bbl 

likely to occur as a result of a CPA proposed action. Activity that would result from the addition of the 

181 South Area would cause a negligible increase in the risk of a large spill occurring and contacting 

seagrass beds. 

WPA Proposed Action Analysis 

Seagrass communities in the WPA are widely scattered beds in shallow, high-salinity coastal lagoons 

and bays. The most extensive seagrass beds are found in both the Upper and Lower Laguna Madre along 

the Texas coast, as well as Baffin Bay. In the Texas Laguna Madre, seagrass meadows are the most 

common submerged habitat type. 

Inshore spills are the greatest threat to seagrass communities in the WPA. Inshore vessel collisions 

may release fuel and lubricant oils, and pipeline ruptures may release crude and condensate oil. The 

Galveston/Houston/Texas City area has the greatest risk of experiencing coastal spills related to a WPA 

proposed action. Spills that could occur in coastal waters from proposed action support operations are 

estimated at 15-34 spills for a WPA proposed action over its 40-year life. 

Offshore oil spills that occur in the proposed action area are much 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. The probabilities of an offshore spill ≥1,000 bbl occurring and 

contacting environmental features are described in Chapter 4.3.1.8 of the Multisale EIS. Six counties in 

Texas and one parish in Louisiana have a chance of spill contact that is greater than 0.5 percent. For these 

counties, the chance of an OCS offshore spill ≥1,000 bbl occurring and reaching the shoreline ranges 

from 1 to 5 percent as the result of a proposed action over its 40-year life. Should a spill ≥1,000 bbl occur 

offshore from activities resulting from a WPA proposed action, the seagrass communities with the highest 

probabilities of contact within 10 days would be those located within Matagorda County, Texas, for a 

WPA proposed action. 

Summary and Conclusion 

Because of the location of most submerged aquatic vegetation, inshore spills pose the greatest threat. 

Such spills may result from either vessel collisions that release fuel and lubricants or from pipelines that 

rupture. Nearshore spills are much smaller in volume and weather quickly. Should they occur, these 

impacts would be considered short term in duration and minor in scope. Although a resulting slick may 

cause minor impacts to the bed, equipment and personnel used to clean up a slick over shallow seagrass 

beds may generate the greatest direct impacts to the area. Associated foot traffic may work oil farther 

into the sediment than would otherwise occur. Scarring may occur if an oil slick is cleaned up over a 

shallow submerged aquatic vegetation bed where vessels, booms, anchors, and personnel on foot would 

be used and scar the bed. Close monitoring and restrictions on the use of bottom-disturbing equipment 

would be needed to avoid or minimize those impacts. 

The MMS has reexamined the analysis for seagrass communities presented in the Multisale EIS, 

based on the additional information presented above. This new information supports the previous 

assessments contained in the Multisale EIS, which is incorporated by reference. No significant new 

information was found that would alter the overall conclusion that impacts on seagrass communities from 

accidental impacts associated with a CPA or WPA proposed action would be minimal. 
Environmental and Socioeconomic Consequences 4-51 

4.1.3.3.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts upon seagrass communities can be found in Chapter 

4.5.3.3 of the Multisale EIS. The following is a summary of the information presented in the Multisale 

EIS, which incorporates new information found since publication of the Multisale EIS. 

This cumulative analysis considers the effects of impact-producing factors related to a CPA and WPA 

proposed action, prior and future OCS activities, State oil and gas activities, other governmental and 

private projects and activities, and pertinent natural processes and events that may adversely affect 

seagrass communities and associated habitat during the life of a proposed action. Impact-producing 

factors relevant to the cumulative analysis include pipelines, canal dredging, channelization and other 

water control structures, scarring from vessel traffic, oil spills, and hurricanes. Because the 181 South 

Area is nearly 130 mi (209 km) from the nearest coast, the only cumulative effect produced by its 

addition to a CPA or WPA proposed action is a small increase in the incremental impacts of vessel traffic. 

Pipeline construction projects can affect seagrass habitats in a number of ways. Jetting of trenches for 

pipeline burial in water shallower than 200 ft (61 m) displaces sediments. Although the majority of 

materials resuspended by jetting returns to the water bottom within a few feet or meters of the trench, 

lighter materials can be carried for several miles or kilometers. Permits from State agencies and COE for 

constructing pipelines require that turbidity impacts be mitigated. Pipeline installation is very infrequent 

and impacts are considered insignificant. About 100 active OCS pipelines currently make landfall and 

about 32-47 new pipelines are projected to make landfall during the 40-year life-span of the proposed 

actions. No additional new pipelines are projected to make landfall as a result of the addition of the 181 

South Area. 

Dredge and fill activities are the greatest threats to submerged vegetation and seagrass habitat (Wolfe 

et al., 1988). New canals and related disposal of dredged material create significant changes in regional 

hydrodynamics and associated erosion. Turbidity caused by dredging produces the most impacts to 

seabeds by sedimentation and reduction of light available to fuel photosynthesis. Canals also affect 

submerged vegetation inshore by increasing the shoreward penetration of high salinity water to areas that 

harbor estuarine and freshwater species. Channel dredging to facilitate, create, and maintain waterfront 

real estate, marinas, and waterways will continue to be a major impact-producing factor in the proposed 

cumulative activity area. 

Channelization of the Mississippi River diverted the natural flow of sediments away from the delta, 

funneling it into deep waters of the Gulf of Mexico. Compaction of previously deposited sediments and 

accumulated layers of marsh accretion lead to subsidence. Also, natural drainage patterns along many 

areas of the coast have been severely altered by construction of the Gulf Intracoastal Waterway and other 

channelization projects. Saltwater intrusion, as a result of river channelization and canal dredging, is a 

major cause of coastal habitat deterioration (including seagrass communities) (Tiner, 1984; National 

Wetlands Inventory Group, 1985). Further compounding this impact, 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 (Turner and Cahoon, 1988) and soil conservation practices in the drainage basin. 

Spillway openings cause sudden changes in the salinity regime and have been associated with as much as 

a 16 percent loss in seagrass vegetation acreage (Eleuterius, 1987). 

The scarring of seagrass beds by vessels is an increasing concern. The greatest scarring of seagrasses 

is caused by small boats and occurs in the vicinities of the greatest human population and boat registration 

densities. Scarring most commonly occurs in seagrass beds that occur in water depths shallower than 6 ft 

(2 m) as a result of boats of all classes operating in water that is too shallow. Other causes include anchor 

drags, trawling, trampling, and loggerhead turtles (especially in seagrass habitat off the coast of Florida) 

(Sargent et al., 1995; Preen, 1996). Recently, seismic activity in areas supporting seagrass nursery habitat 

has become a focus of concern for Texas State agencies. Scarring may have a more critical effect on 

habitat functions in areas with less submerged vegetation. Some local and State governments have 

instituted management programs to reduce scarring. Initial results indicate that scarring can be reduced. 

Oil spills alone would typically have very little impact on seagrass communities and associated 

epifauna. The floating nature of oil and the regional microtidal range serve to limit direct contact with 

seagrass. However, wave action can mix oil into the water column and increase impacts to seagrass 
4-52 Central and Western Gulf of Mexico Multisale Supplemental EIS

communities. Unusually low tidal events would also increase the risk of oil having direct contact with the 

vegetation. Epifauna residing in seagrass beds would be more heavily impacted than the vegetation itself. 

Oiling of seagrass beds would result in die-back of the vegetation and associated epifauna, which would 

be replaced for the most part in 1-2 growing seasons. Little or no direct mortality of seagrass beds is 

expected as a result of oil spills. Contact of seagrasses with crude or refined oil products has been 

implicated as a causative factor in the decline of seagrass beds and in the observed changes in species 

composition within them (Eleuterius, 1987). The cleanup of slicks in shallow, protected waters (<5 ft or 

1.5 m deep) can cause significant scarring and trampling of submerged vegetation beds. Oil spilled in 

Federal offshore waters is not projected to significantly impact submerged aquatic vegetation. Based on 

OCS spill rates, the incremental increase in oil production from the addition of the 181 South Area is not 

expected to result in an overall increase in the numbers of oil spills ≥1,000 bbl likely to occur as a result 

of a CPA proposed action. 

Seagrass beds have been repeatedly damaged by the natural processes of transgression from hurricane 

overwash of barrier islands. The Chandeleur Island chain has been hit by five storms in the past eight 

years (Michot and Wells, 2005). 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. Over time, seagrass recolonizes the new sand flats on the shoreward 

side, and the natural processes of sand movement rebuild the islands. Recent hurricane impacts have 

produced changes in seagrass community quality and composition (Heck and Byron, 2006; Poirrier and 

Cho, 2002; Anton et al., 2006; May, 2007; Maiaro, 2007). 

Summary and Conclusion 

Impact-producing factors relevant to the cumulative analysis include pipelines, canal dredging, 

channelization and other water control structures, scarring from vessel traffic, oil spills, and hurricanes. 

Pipeline construction creates turbidity that reduces light availability and can cause sedimentation and 

direct burial of seagrass communities. Dredging generates the greatest overall risk to seagrass 

communities. Channel dredging to create and maintain waterfront real estate, marinas, and waterways 

will continue to cause the greatest impacts to higher salinity submerged vegetation. Mitigation, such as 

the use of turbidity curtains, may be required to reduce undesirable impacts of dredging. Large water 

control structures influence salinities in coastal areas, which in turn influence the location of seagrass 

communities and associated epifauna. Seagrass beds can be scarred by anchor drags, trampling, trawling, 

loggerhead turtles, occasional seismic activity, and boats operating in water that is too shallow for their 

keels or propellers. The greatest scarring results from small boats operating in the vicinities of large 

populations of humans and registered boats. Inshore oil spills present greater risks of adversely impacting 

submerged vegetation than do offshore spills. Wave action and extreme low tide events during a spill can 

cause direct contact of oil on seagrass. This will result in die-back of the seagrass vegetation and 

supported epifauna, which will be replaced, for the most, part within 1-2 growing seasons. The cleanup 

of slicks can cause significant scarring and trampling of submerged vegetation and seagrass beds. 

Hurricanes generate substantial overall risk to submerged vegetation from burial and eroding channels 

through seagrass beds. When combined with other stresses, impacted seagrass beds may fail to recover. 

The most effective mitigation for direct impacts to submerged vegetation beds is avoidance. 

New information published since completion of the Multisale EIS is discussed above in the 

description of the affected environment and is incorporated into the impact analyses. No new OCS or 

non-OCS activities were found. New information supports the previous assessments contained in the 

Multisale EIS, which is incorporated by reference, and does not necessitate a reanalysis of the impacts for 

the proposed actions. The 181 South Area is nearly 130 mi (209 km) from the nearest coast and is 

expected to result in a small increase in the incremental impacts of vessel traffic. The analysis and 

potential impacts detailed in the Multisale EIS remains valid for this SEIS. 

In general, a CPA or WPA proposed action would cause a minor incremental contribution to impacts 

on submerged vegetation from dredging, boat scarring, pipeline installations, and possibly oil spills. 

Dredging generates the greatest overall risk to submerged vegetation, and hurricanes cause direct damage 

to seagrass beds, which may fail to recover in the presence of cumulative stresses. A CPA or WPA 

proposed action would have a minor contribution to dredging from the maintenance of channels. 
Environmental and Socioeconomic Consequences 4-53 

4.1.4. Continental Shelf Benthic Resources 

4.1.4.1. Live Bottoms (Pinnacle Trend) 

The MMS has reexamined the analysis for live bottoms (Pinnacle Trend) presented in the Multisale 

EIS, based on the additional information presented below and the addition of the 181 South Area to the 

proposed CPA sale area. No significant new information was found that would alter the impact 

conclusion for live bottoms (Pinnacle Trend) presented in the Multisale EIS. The 181 South Area is 

located 127 mi (204 km) from the Pinnacle Trend region, and the pinnacle habitat is deep, 200-400 ft 

(60-120 m); therefore, activity associated with the 181 South Area would not impact live bottoms. 

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

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

presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. The combination of its depth (200-400 ft or 60-120 m), separation 

from sources of impacts as mandated by the Live Bottoms (Pinnacle Trend) Stipulation, and a community 

adapted to sedimentation makes damage to the ecosystem unlikely from routine activities associated with 

a CPA proposed action. In the unlikely event that oil from a subsurface spill would reach the biota of 

Pinnacle Trend communities, the effects would be primarily sublethal for adult sessile biota and there 

would be limited incidences of mortality. Cumulative activities in the vicinity of the hard-bottom 

communities including natural disturbances, fishing, anchoring, and oil spills could cause severe damage 

that could threaten the survival of live-bottom communities. The incremental contribution of a CPA 

proposed action to the cumulative impacts is expected to be slight, and negative impacts should be 

restricted by the implementation of the Live Bottom (Pinnacle Trend) Stipulation and site-specific 

mitigations, the depths of the features, and water currents in the live-bottom area. No impacts are 

expected from a WPA proposed action because the Pinnacle Trend is over 300 mi (480 km) away; 

therefore, a WPA proposed action is not analyzed below. 

4.1.4.1.1. Description of the Affected Environment 

A detailed description of the biology of live bottoms can be found in Chapter 3.2.2.1.1 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since the publication of the Multisale EIS. 

The northeastern portion of the Central Gulf of Mexico exhibits a region of topographic relief known 

as the “Pinnacle Trend” at the outer edge of the Mississippi-Alabama shelf between the Mississippi River 

and DeSoto Canyon. The 181 South Area is 127 mi (204 km) from the Pinnacle Trend region. The MMS 

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 70 MMS lease blocks where the MMS has applied the Live Bottom (Pinnacle Trend) Stipulation 

to protect the ecosystem. This area includes portions of the continental shelf, shelf break, and upper 

continental slope. The area also spans differing sediment regimes. The eastern part of the pinnacles area 

is covered with a thin, well-sorted layer of fine- to medium-grained 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 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 (Rezak et al., 1985; Dennis and 

Bright, 1988; Rezak et al., 1990; Gittings et al., 1992; CSA and GERG, 2001; Weaver et al., 2001). The 

pinnacles generally have a southwest to northeast trend with many of the groups and linear features 

oriented in this direction. The heavily indurated 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. 
4-54 Central and Western Gulf of Mexico Multisale Supplemental EIS

Topography 

The pinnacle region contains a variety of features from low-relief rocky areas to major pinnacles, as 

well as ridges, scarps, and relict patch reefs. This includes thousands of carbonate mounds ranging in size 

from less than a few meters (feet) in diameter to nearly a kilometer (mile). Most of these features are of 

low relief, 1-2 m (3-6 ft) or less, and some occur in quite extensive groups. Shallow depressions are a 

type of low-relief feature common in the pinnacle area, particularly in the western portion. These occur 

in large fields that do not follow depth contours. They are usually 5-10 m (16-33 ft) across and less than a 

meter (3 ft) in depth. 

Reef-like mounds are the most widespread features in the pinnacle region. They range in height from 

1-20 m (3-66 ft) and in width from a few meters to over one-half kilometer (a few yards to over a quarter 

of a mile). They are mostly along two major depth bands: 74-82 m (243-269 ft) and 105-120 m (345-394 

ft). Patch reefs are small reef-like mounds about 2-12 m (6-39 ft) in diameter and 3-4 m (10-13 ft) in 

height that occur in many areas. Flat-topped reefs are large reef-like mounds that occur along the same 

isobath as patch reefs. They 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 pinnacles are 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). Some reef-like mounds also occur outside the two 

major depth bands. Several clusters are found shoreward in 60-70 m (197-230 ft) of water. 

Ridges are the largest features in the area. These ridges are typically about 20 m (66 ft) wide (up to 

250 m or 820 ft) and over 1 km (0.6 mi) long. Most of the ridges are low relief, around 1 m (3 ft) in 

height, but some have scarps up to 8 m (66 ft) high. They often occur in groups of 6-8 ridges (Brooks, 

1991). 

Ecology 

The pinnacle features provide a significant amount of hard substrate for colonization by suspensionfeeding invertebrates and support relatively rich live-bottom and fish communities. 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 or 3 ft height) typically having low faunal densities, and higher relief 

features having the more diverse faunal communities. Features tall enough to rise above the common 

effects of turbidity have higher community diversity and density. The crests of the pinnacles are perhaps 

slightly more diverse than the walls. 

Substrate characteristics and turbidity are 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. To the 

east, the crests and walls of pinnacles are dominated by low-growing ahermatypic hard corals. This is a 

matter of both substrate and turbidity. Resuspension of sediments is a major contributor to turbidity in 

the Pinnacle Trend. This is more severe in the western part of the area because of the silty sediments 

deposited by the Mississippi River. Resuspension is caused by currents and wave action. 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 communities closer to the Mississippi River are less diverse and communities near 

the bottom are less diverse. 

The characteristics of the substrate have a high degree of control over the composition of the 

biological communities that live on it. The more complex the shape of the substrate, the greater the 

variety of habitats for organisms. Assemblages of ahermatypic stony corals, 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). 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. 

Horizontal surfaces have a considerably higher biological cover with more species than vertical surfaces. 

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, such 

as many of the ahermatypic hard corals. 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. 

Diversity and density of epibenthic organisms varies considerably between features in the Pinnacle 

Trend area. Areas with more exposed hard bottom, vertical relief, rugosity, and complexity of the 
Environmental and Socioeconomic Consequences 4-55 

substrate have 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. The Pinnacle Trend reef tract forms a major ecosystem with 

an influence that pervades the wider regional ecosystem. The general trend is less turbid and has 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 relief, rugosity, and 

the incidence of light contribute to local differences in community structure. 

A search was conducted for new information published since completion of the Multisale EIS. 

Various Internet sources were examined to determine any recent information regarding the Pinnacle 

Trend. Sources investigated include USGS, NOAA, USEPA, and coastal universities. Other sites were 

found through general Internet searches. 

Additional information was found regarding ongoing USGS studies conducted to support MMS 

management (Gardner et al., 2002b; USDOI, GS, 2003; Weaver et al., 2001). The USGS Florida 

Integrated Science Center’s pinnacles project works to identify patterns of demersal fish distribution, 

community structure, and trophic relationships associated with reef-like carbonate banks and mounds in 

the Pinnacle Trend area (USDOI, GS, 2003). The present research seeks to further define the basis of 

physical-biological coupling, aspects of community structure and function, biotope affinities, and critical 

habitat parameters for hard-bottom areas in the eastern Gulf of Mexico. This work enhances the 

understanding of the Pinnacle Trend’s regional ecosystem to support MMS management and 

decisionmaking. This new information on the Pinnacle Trend supports and reinforces the description of 

the environment presented in the Multisale EIS. 

4.1.4.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA proposed 

action on Pinnacle Trend communities is presented in Chapters 4.2.2.1.4.1.1 of the Multisale EIS. No 

impacts are expected from a WPA proposed action because the Pinnacle Trend is over 300 mi (480 km) 

away. The routine activities associated with a 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 181 South Area is 127 mi (204 km) 

from the Pinnacle Trend region. Passing service vessels would be the only likely connection between the 

two areas. Since the pinnacle habitat is deep, 200-400 ft (60-120 m), it is unlikely that any effect could 

result unless a transiting vessel has a catastrophic accident in the Pinnacle Trend region. 

The Live Bottom (Pinnacle Trend) Stipulation is described in detail in Chapter 2.4.1.3.2 of the 

Multisale EIS. It is a mitigating measure for leases resulting from a proposed action. 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 pinnacles. 

Anchoring is potentially the most damaging impact, having the ability to destroy lush biological 

assemblages and damage the structure of the pinnacles themselves. Anchors can destroy a swath of 

habitat by being dragged over the seafloor, or the anchor chain can sweep a wide area of the seafloor. 

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. 

Infrastructure and pipelines could be placed over pinnacle habitat, crushing the benthic community 

and damaging the structure of the habitat itself. While damage from a pipeline would likely affect a very 

limited area, the associated anchors and anchor chain/cables of a traditional pipelaying barge could 

devastate a wide swath of habitat along each side of the pipeline route. 

Both explosive and nonexplosive structure-removal operations will disturb the seafloor and 

potentially affect nearby pinnacle communities. Structure removal using explosives suspends sediments 

that will settle on nearby biotic communities. However, since the pinnacle habitat is near the outflow of 

the Mississippi River, it is colonized by organisms that are adapted to high turbidity and sedimentation. 

Explosive structure removals create shock waves, which harm biota in the immediate vicinity. Organisms 

with swim bladders, such as fish, are most affected by blasts; most stationary benthic animals are 

remarkably resistant to these effects (O’Keeffe and Young, 1984). 
4-56 Central and Western Gulf of Mexico Multisale Supplemental EIS

Discharges of drilling cuttings and fluids can affect benthic organisms in the immediate vicinity of the 

activity. Cuttings can build layers up to 30 cm (12 in) thick near the well, smothering most sessile 

organisms. In addition, the cuttings can contain contaminants that are detrimental to the growth and 

development of organisms. However, studies have shown little effect of cuttings and fluids near 

communities of the Pinnacle Trend (Shinn et al., 1993). These organisms are adapted to environments 

with high sedimentation. The proposed Live Bottom (Pinnacle Trend) Stipulation would prohibit 

physical impacts to Pinnacle Trend features. Mitigations based on NTL 2004-G05 prohibit bottomdisturbing activities within 30 m (100 ft) to further ensure protection. 

Produced-water discharges contain high amounts of dissolved solids and total organic carbon, and 

low dissolved oxygen. Other common components include heavy metals, elemental sulfur and sulfide, 

organic acids, treating chemicals, and emulsified and particulate crude oil constituents. Salinity of 

produced water can vary from 0 to 300 ppt. These products, if discharged directly on Pinnacle Trend 

habitats, would have harmful effects on the community. The proposed Live Bottom (Pinnacle Trend) 

Stipulation would prohibit physical impacts to Pinnacle Trend features. Mitigations based on NTL 2004-

G05 prohibit bottom-disturbing activities within 30 m (100 ft) to further ensure protection. 

CPA Proposed Action Analysis 

The routine activities associated with a 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. 

For a CPA proposed action, 43-51 exploration/delineation and development wells and 5-6 production 

structures are projected for offshore Subareas C0-60 (east of the Mississippi River) and C60-200. The 

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. These areas are expected to have 5-6 structures removed, with four of them 

using explosives. About 10-130 km (6-81 mi) of new pipeline installation is projected in offshore 

Subarea C0-60 (east of the Mississippi River). Approximately 119,000-241,000 service-vessel trips are 

expected to result from the proposed action for the entire CPA. 

Anchoring is potentially the most damaging impact but, with the low number of structures to be 

installed near the Pinnacle Trend region, the likelihood of damage to the habitat is low. Most vessels will 

travel to other locations, only sometimes transiting the pinnacle region. The Live Bottom (Pinnacle 

Trend) Stipulation would prohibit activities from causing direct impacts to Pinnacle Trend communities. 

The Pinnacle Trend region comprises only a small percentage of its two larger subareas (2% and 6%). 

Very little new infrastructure is expected in the pinnacle region. If the proposed lease stipulation is 

applied and followed, the benthic community should suffer no damaging impacts. None have been 

reported in the past. Trenching is not required for pipelines in the depths found at the Pinnacle Trend (60-

120 m or 200-400 ft). 

Only 5-6 removals are projected for the larger subareas encompassing the Pinnacle Trend. Four of 

these could be explosive removals. Any removals requested in the Pinnacle Trend area will be 

scrutinized very carefully. Options will be explored for using alternative methods during removals to 

minimize potential impact to surrounding hard-bottom communities. Site clearance techniques will be of 

particular concern and may require remote-sensing surveys to identify and recover debris. The Live 

Bottom (Pinnacle Trend) Stipulation requirements to protect the habitat would take precedence. 

New drill cuttings and fluid discharges will be added by only the few new production structures (5-6) 

that are projected for the larger subareas as a result of a CPA proposed action. The comparatively small 

area of the Pinnacle Trend would be protected from direct discharges on sensitive habitat by the Live 

Bottom (Pinnacle Trend) Stipulation. The depth of the habitat (60-120 m or 200-400 ft) favors dispersion 

of surface discharges and dilution before it reaches sensitive organisms. 

Produced-water discharges would be separated from sensitive, hard-bottom habitat the same as drill 

cuttings and fluids. Discharges would disperse and dilute before reaching the relatively deep habitats. 

The proposed Live Bottom (Pinnacle Trend) Stipulation would prohibit physical impacts to Pinnacle 

Trend features. Mitigations based on NTL 2004-G05 prohibit bottom-disturbing activities within 30 m 

(100 ft) to further ensure protection. 
Environmental and Socioeconomic Consequences 4-57 

Summary and Conclusion 

The routine activities associated with a CPA proposed action that would impact Pinnacle Trend 

communities include anchoring, infrastructure and pipeline emplacement, infrastructure removal, drilling 

discharges, and produced-water discharges. The 181 South Area is 127 mi (204 km) from the Pinnacle 

Trend region; therefore, passing service vessels would be the only likely connection between the two 

areas. Since the pinnacle habitat is deep, 200-400 ft (60-120 m), it is unlikely that any effect could result 

unless a transiting vessel has a catastrophic accident in the Pinnacle Trend region. No impacts are 

expected from a WPA proposed action because the Pinnacle Trend is over 300 mi (480 km) away. The 

combination of its depth (200-400 ft or 60-120 m), separation from sources of impacts as mandated by the 

Live Bottom (Pinnacle Trend) Stipulation, and a community adapted to sedimentation makes damage to 

the ecosystem unlikely. Pipeline routes would avoid Pinnacle Trend habitat. Anchor damage and 

infrastructure emplacement is prohibited on the habitat. 

The MMS has reexamined the analysis for the Pinnacle Trend presented in the Multisale EIS, based 

on the additional information presented above. No significant new information was found that would 

alter the overall conclusion that impacts on the Pinnacle Trend from routine activities associated with a 

CPA proposed action would be minimal. 

4.1.4.1.3. 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. Chapter 2.4.1.3.2 of the Multisale EIS contains a 

complete description and discussion of the proposed Live Bottom (Pinnacle Trend) Stipulation. No 

impacts are expected from a WPA proposed action because the Pinnacle Trend is over 300 mi (480 km) 

away. The following is a summary of the information presented in the Multisale EIS, which incorporates 

new information found since publication of the Multisale EIS. 

Accidental disturbances resulting from a CPA proposed action, including oil spills, blowouts, 

chemical spills, and vessel collisions, have the potential to disrupt and alter the environmental, 

commercial, recreational, and aesthetic values of the Pinnacle Trend in the CPA. 

Oil spills potentially affecting the Pinnacle Trend and its biological communities could result from 

surface and seafloor spills. Both surface and subsurface spills could result in a steady discharge of oil 

over a long period of time. Surface oil spills may occur as a result of platform or tanker spills. The 

shallowest depth of the Pinnacle Trend features in the northern Gulf of Mexico (60 m or 200 ft) should 

protect the community from surface oil slicks. Oil from a surface spill can be driven into the water 

column; measurable amounts have been documented down to a 10-m (33-ft) depth, although modeling 

exercises have indicated such oil may reach a depth of 20 m (66 ft). At this depth, the oil is found at 

concentrations several orders of magnitude lower than the amount shown to have an effect on corals 

(Lange, 1985; McAuliffe et al., 1975 and 1981; Knap et al., 1985). Any dispersed oil that reaches the 

benthic community would be expected to be at concentrations of less than 1 ppm. Such low oil 

concentrations would not be life threatening to larval or adult stages at that depth (Fucik et al., 1994). 

Because the crests of Pinnacle Trend features in the northern Gulf are found well below 10 m (33 ft), no 

concentrated oil from a surface spill is expected to reach their sessile biota. 

Seafloor spills could be caused by a tanker accident, pipeline rupture, or well blowout. However, a 

subsurface spill should rise to the surface. Evidence from a recent experiment in the North Sea indicates 

that oil released during a deepwater blowout or pipeline rupture would quickly rise to the surface and 

form a slick (Johansen et al., 2001). Impacts from a deepwater oil spill would occur in the water column 

and at the surface where the oil would be mixed into the water and dispersed by wind waves. If some oil 

were to contact Pinnacle Trend habitat, the impacts would be primarily sublethal with the disruption or 

impairment of a few elements at the local scale, but no interference to the general system performance 

would occur. The sublethal effects 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). It is 

anticipated that potential recovery for such an event would occur within a period of 2 years (USDOC, 

NOAA, Office of Response and Restoration, 2007; Shigenaka, 2001; Rice et al., 1983). However, due to 
4-58 Central and Western Gulf of Mexico Multisale Supplemental EIS

the application of the proposed Live Bottom (Pinnacle Trend) Stipulation, drilling would not occur within 

30 m (100 ft) of a No Activity Zone, so blowouts would not occur in the immediate vicinity of the 

Pinnacle Trend and associated biota. Therefore, hazardous concentrations of oil would be unlikely to 

reach the Pinnacle Trend. 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. 

Therefore, sediment from a blowout, if it occurred nearby, would not harm the community. Oil adsorbed 

to the sediment would likely have a sublethal impact on biota. 

Common OCS-related chemicals spilled are methanol, ethylene glycol, zinc bromide, and ammonium 

chloride. Two chemicals could potentially impact the marine environment—zinc bromide and 

ammonium chloride (Boehm et al., 2001). Most other chemicals are either nontoxic or used in small 

quantities. Precipitation of zinc in marine waters would minimize the potential for impact. Ammonium 

chloride disassociates to temporarily elevate the levels of ammonia in the spill vicinity, but it is unlikely 

this would reach the depths of the Pinnacle features. Chemical dispersants can be used in remediation of 

oil spills to promote mixing with the water and faster degradation. This would be applied on the sea 

surface and would be thoroughly diluted before reaching the Pinnacle Trend community. 

Vessel collisions can result in spills of oils, fuels, and chemicals. Collision of a service vessel with a 

platform could result in spills from the vessel, the platform, or both. It could also cause a moored 

structure to drag anchors or break loose from anchors and subsequently impact a Pinnacle Trend feature. 

A collision could potentially result in the sinking of a vessel with direct physical impacts to a Pinnacle 

Trend feature. If a sunken vessel landed on or near a sensitive habitat, leaking fluids could contact the 

habitat directly. From 1996 to 2005, there were 129 OCS-related collisions, mostly with platforms or 

pipeline risers. Diesel fuel is the product most frequently spilled, while corrosion inhibitor, hydraulic 

fluid, lube oil, and methanol have also been released. Approximately 10 percent of vessel collisions with 

platforms in the OCS caused diesel spills. Minimal impacts result from a spill since diesel is light and 

will evaporate and biodegrade within a few days. 

A search was conducted for new information published since completion of the Multisale EIS. 

Various Internet sources were examined to determine any recent information regarding the Pinnacle 

Trend. Sources investigated include USGS, NOAA, USEPA, and coastal universities. Other sites were 

found through general Internet searches. 

Since Hurricanes Katrina and Rita in 2005, MMS has identified 154 spills of petroleum products of 

>1 bbl, totaling 17,077 bbl that were lost from platforms, rigs, and pipelines on the Federal OCS (USDOI, 

MMS, 2007e). Approximately 600 petroleum spills of <1 bbl on the Federal OCS related to the 2005 

hurricanes have been reported to the National Response Center (NRC). These NRC reports totaled to <50 

bbl and averaged approximately 3 gallons each in size. These spills of <1 bbl dissipate quickly due to 

evaporation, dispersion by the winds and currents, and dilution by the ocean waters. These small releases 

generally do not cause identifiable environmental impacts out in the open ocean. There were no accounts 

of environmental consequences resulting from spills on the OCS identified with Hurricanes Katrina and 

Rita. The final estimation of the total spillage associated with Hurricanes Katrina and Rita will not be 

complete until the conclusion of recovery efforts continuing through 2007 and into 2008. 

CPA Proposed Action Analysis 

The Pinnacle Trend is protected from impacts by oil and gas activity by MMS and it occupies 70 

MMS lease blocks in the northeastern portion of the CPA. These 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 200 ft 

(60 m). When surface spills are mixed into the water column, the oil is not expected to penetrate below a 

depth of about 33 ft (10 m). As explained in Chapter 3.2.1, the incremental increase in oil production 

from the addition of the 181 South Area is not expected to result in an overall increase in the numbers of 

oil spills ≥1,000 bbl likely to occur as a result of a CPA proposed action. Activity that would result from 

the addition of the 181 South Area would cause a negligible increase in the risk of a large spill occurring 

and contacting seagrass beds. 
Environmental and Socioeconomic Consequences 4-59 

Approximately 3-4 blowouts are projected to occur in the CPA during activities resulting from the 

proposed actions. With the application of the proposed stipulations, none of these blowouts should occur 

within 100 ft (30 m) of a Pinnacle Trend feature. Furthermore, blowouts near Pinnacle Trend features are 

unlikely to impact the biota because oil will rapidly float to the surface. 

Since collisions occur infrequently, the potential impacts to the Pinnacle Trend in the CPA are not 

expected to be significant. Chemical spills are also infrequent, of small quantity, and usually occur in 

surface waters. No significant impacts to the Pinnacle Trend in the CPA are expected. 

The proposed Live Bottom (Pinnacle Trend) Stipulation would assist in preventing most of the 

potential impacts from oil and gas operations including accidental oil spills, blowouts, vessel collisions, 

and chemical spills on the biota of Pinnacle Trend. 

Summary and Conclusion 

Contact with accidentally spilled oil would cause lethal and sublethal effects in benthic organisms. 

The oiling of benthic organisms is not likely because of the small area of the Pinnacle Trend compared 

with the entire CPA, the scattered occurrence of spills, the depth of the features, and because the proposed 

Live Bottom (Pinnacle Trend) Stipulation would keep subsurface sources of spills away from the 

immediate vicinity of Pinnacle Trend features. In the unlikely event that oil from a subsurface spill would 

reach the biota of Pinnacle Trend communities, the effects would be primarily sublethal for adult sessile 

biota and there would be limited incidences of mortality. 

The MMS has reexamined the analysis for the Pinnacle Trend presented in the Multisale EIS, based 

on the additional information presented above. This new information supports the previous assessments 

contained in the Multisale EIS, which is incorporated by reference. No significant new information was 

found that would alter the overall conclusion that impacts on Pinnacle Trend communities from accidental 

impacts associated with a CPA proposed action would be minimal. No impacts are expected from a WPA 

proposed action because the Pinnacle Trend is over 300 mi (480 km) away. 

4.1.4.1.4. 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. The following is a summary of the information presented 

in the Multisale EIS, which incorporates new information found since publication of the Multisale EIS. 

This cumulative analysis considers the effects of impact-producing factors related to the proposed 

actions plus those related to prior and future OCS lease sales, and to tanker and other shipping operations 

that may occur and adversely affect live bottom (Pinnacle Trend) communities. Non-OCS-related 

impacts, including natural disturbances, fishing, anchoring, and oil spills, have the potential to alter live 

bottoms. Specific OCS-related, impact-producing factors considered in the analysis are infrastructure 

emplacement and removal, anchoring, drilling discharges, produced waters, oil spills, blowouts, chemical 

spills, and vessel collisions. Because the 181 South Area is about 127 mi (204 km) from the Pinnacle 

Trend, the only cumulative effect produced by its addition to a CPA proposed action is a small increase in 

the incremental impacts of vessel traffic. 

It is assumed protective stipulations for live bottoms will be part of appropriate OCS leases and 

existing site/project-specific mitigations will be applied to OCS activities on these leases or supporting 

activities on these leases. 

Non-OCS activities have a greater potential to affect the hard-bottom communities of the region than 

MMS-regulated activities. Natural disturbances such as hurricanes and extreme fluctuations of 

environmental conditions (e.g., nutrient pulses, low dissolved oxygen levels, seawater temperature 

minima, and seasonal algal blooms) can affect live-bottom communities of the CPA. Because of the 

depth of the Pinnacle Trend area (200-400 ft or 60-120 m), waves seldom have a direct influence. Rather, 

wave action creates currents that can resuspend sediments to produce added turbidity and sedimentation. 

The animals in this region are well-adapted to the effects common to this frequently turbid environment. 

Recreational boating and fishing may severely impact live-bottom communities. Numerous 

fishermen take advantage of the relatively shallow and easily accessible resources of the region and 
4-60 Central and Western Gulf of Mexico Multisale Supplemental EIS

anchor at hard-bottom locations to fish. Bottom longlining could potentially result in cumulative impacts 

to live-bottom communities. If contact did occur, impacts from bottom longlines would be minimal. 

Damage resulting from bottom trawling would have a much greater impact. Ships anchoring near major 

shipping fairways of the CPA, on occasion, may impact sensitive areas located near these fairways. 

Oil and chemical spills from non-OCS-related impacts could result from vessel collisions and other 

accidents. While an unlikely event (<1/yr), import tanker accidents could produce the largest offshore 

spills. These oil and chemical spills will have the same effect as described below for OCS-related 

impacts. 

Oil and gas activities produce cumulative effects on the offshore environment. The Live Bottom 

(Pinnacle Trend) Stipulation prevents direct impacts to live-bottom communities. The placement of 

structures on the seafloor crushes organisms and can cause scouring of the surficial sediments (Caillouet 

et al., 1981). The effect of pipeline-laying activities on the biota of live-bottom communities would be 

restricted to the temporary resuspension of sediments, resulting in sublethal effects over small areas. 

Explosive and nonexplosive structure-removal operations disturb the seafloor. Structure removal 

using explosives (the most common removal method) can suspend sediments, which settle much in the 

same manner as discussed below for muds and cuttings discharges. Shock waves in the seafloor are 

attenuated within 100 m (328 ft) from the structure (Baxter et al., 1982). Resuspended sediments would 

impact an area within a radius of approximately 1,000 m (3,281 ft). The explosive removal of structures 

is expected to have minimal effects on live-bottom communities. 

Anchor damage from support boats and ships, floating drilling units, and pipeline-laying vessels are 

considered the greatest potential OCS-related threat to live-bottom areas. Anchoring can destroy a wide 

swath of habitat when a vessel drags or swings at anchor, causing the chain to drag across the seafloor. 

The proposed biological stipulation would limit the proximity of new activities to live bottoms and 

sensitive features. The misplacement of anchors could severely impact hard-bottom substrate, which has 

recovery rates (which are not well documented) estimated at 5-20 years depending on the severity. 

Routine discharges of drilling muds and cuttings by oil and gas operations could smother organisms 

or produce less obvious sublethal toxic effects. Lease stipulations and site-specific mitigations would 

prevent drilling discharges directly over pinnacle habitat. Drilling discharges should reach undetectable 

concentrations in the water column within 1,000 m (3,281 ft) of the discharge point, thus limiting 

potential toxic effects to benthic organisms. Effects would diminish rapidly with increasing distance from 

the discharge area. The levels of contaminants in the water column and sediments are expected to be well 

below the new USEPA discharge regulations and permits (Chapter 4.1.3.4 of the Multisale EIS). The 

deposition of drilling muds and cuttings in live-bottom and pinnacle trend areas are not expected to 

greatly impact the biota of the pinnacles or the surrounding habitat. The impact from muds and cuttings 

discharged as a result of the cumulative scenario would be temporary, primarily sublethal in nature, and 

the effects would be limited to small areas. Recovery to pre-impact conditions from these sublethal 

impacts would take place within 10 years. 

Produced waters would be discharged at the surface; the depth of the low-relief hard bottoms (>40 m 

or 131 ft), currents, and lateral offset of discharges would render the wastes harmless to any live-bottom 

habitat. Adverse impacts of cumulative activities would therefore be temporary, primarily sublethal in 

nature, and the effects would be limited to small areas. Predicted recovery to pre-impact conditions from 

these sublethal impacts would take place within 5 years. 

Surface spills of oil can be mixed into the water column by wave turbulence. Measurable amounts 

have been documented down to a 10-m (33 ft) depth, and models have indicated such oil may reach a 

depth of 20 m (66 ft). Concentrations at these depths would be several orders of magnitude lower than 

the amount required to effect marine organisms (Lange, 1985; McAuliffe et al., 1975 and 1981). Since 

Pinnacle Trend features reside below 20-m (66-ft) water depth, surface spills would not impact the biota. 

Evidence from Johansen et al. (2001) indicates that oil from subsurface pipeline spills are not 

expected to cause damage to live-bottom biota because the oil would rise rapidly to the sea surface. 

There is little probability that a subsurface oil spill will impact live bottoms since the proposed lease 

stipulation prevent the installation of pipelines in the immediate vicinity of live-bottom areas. The 

adverse impacts from subsurface oil spills on live bottoms would be minor in scope, primarily sublethal in 

nature, and the effects would be contained within a small area. Recovery to pre-impact conditions from 

these sublethal impacts could take place within 5-10 years. 
Environmental and Socioeconomic Consequences 4-61 

Subsurface blowouts can resuspend sediments and release hydrocarbons into the water column near 

Pinnacle Trend communities. The continued implementation of lease stipulations and mitigations should 

prevent blowouts from occurring directly on live bottoms. A severe subsurface blowout within 400 m 

(1,312 ft) of a live bottom could result in the smothering of the biota due to sedimentation. Since much of 

the live-bottom biota is adapted to turbid conditions, most impacts would probably be sublethal, with 

recovery taking place within 5 years. 

Common OCS-related chemicals spilled are methanol, ethylene glycol, zinc bromide, and ammonium 

chloride. The last two could potentially impact the marine environment; most other chemicals are either 

nontoxic or used in small quantities (Boehm et al., 2001). The effects of ammonium chloride would be 

rapidly diluted, and zinc quickly precipitates out of solution. Chemical dispersants used on the sea 

surface would be thoroughly diluted before reaching the Pinnacle Trend community. 

Vessel collisions can result in spills of oils, fuels, and chemicals. If a sunken vessel landed on or near 

a sensitive habitat, leaking fluids could contact the habitat directly. Diesel fuel is the product most 

frequently spilled, while corrosion inhibitor, hydraulic fluid, lube oil, and methanol have also been 

released. Minimal impacts result from a spill since diesel is light and will evaporate and biodegrade 

within a few days. In the unlikely event a freighter, tanker, or other ocean-going vessel related to OCS 

Program activities sank and proceeded to collide with the pinnacle features or associated habitat releasing 

its cargo, recovery capabilities from such a catastrophic scenario are unknown at this time. 

Should the Live Bottom (Pinnacle Trend) Stipulation not be implemented, OCS activities could have 

the potential to destroy part of the biological communities. 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. The OCS Program, with the benefit of protective lease stipulations 

and site-specific mitigations, would have little adverse impact on Pinnacle Trend communities and 

habitat. 

Summary and Conclusion 

Non-OCS activities in the vicinity of the hard-bottom communities include natural disturbances, 

fishing, anchoring, and oil spills. These activities could cause severe damage that could threaten the 

survival of live-bottom communities. Ships using fairways in the vicinity of live bottoms anchor in the 

general area of live bottoms on occasion, and numerous fishermen take advantage of the relatively 

shallow and easily accessible resources of regional live bottoms. These activities could lead to severe and 

permanent physical damage. During severe storms, such as hurricanes, large waves may reach deep 

enough to stir bottom sediments. 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. 

Impact-producing factors resulting from activities of OCS oil and gas operations include 

infrastructure emplacement and removal, anchoring, drilling discharges, produced waters, oil spills, 

blowouts, chemical spills, and vessel collisions. Long-term OCS activities are not expected to adversely 

impact the live-bottom environment if these impact-producing factors are restrained by the continued 

implementation of protective lease stipulations 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 live bottoms. The impact to the live-bottom 

resource as a whole is expected to be slight because of the projected lack of community-wide impacts. 

Because of the distance from the sensitive habitat, no effects are expected from activities located in the 

WPA. Activities associated with the 181 South Area would produce a small incremental increase in 

impacts due to navigational traffic. 

Potential impact from oil spills >1,000 bbl would be restricted because of the depth of the features 

(>20 m (66 ft)), because subsea pipeline spills are expected to rise rapidly, and because of the low 

prospect of pipelines being routed immediately adjacent to live bottoms. The frequency of impacts to live 

bottoms should be rare and the severity slight. Impacts from accidents involving the misplacement of 

anchors on live bottoms could be severe in small areas (those actually crushed or subjected to abrasions). 

The incremental contribution of a CPA proposed action to the cumulative impact is expected to be 

slight, with possible impacts from physical disturbance of the bottom, discharges of drilling muds and 

cuttings, other OCS discharges, structure removals, and oil spills. Negative impacts should be restricted 
4-62 Central and Western Gulf of Mexico Multisale Supplemental EIS

by the implementation of the Live Bottom (Pinnacle Trend) Stipulation and site-specific mitigations, the 

depths of the features, and water currents in the live-bottom area. 

New information published since completion of the Multisale EIS is discussed above in the 

description of the affected environment and incorporated into the impact analyses. No new OCS or nonOCS activities were found. New information supports the previous assessments contained in the 

Multisale EIS, which is incorporated by reference, and does not necessitate a reanalysis of the impacts for 

the proposed actions. The 181 South Area is about 127 mi (204 km) from the Pinnacle Trend area and is 

expected to result in a small increase in the incremental impacts of vessel traffic. The analysis and 

potential impacts detailed in the Multisale EIS remains valid for this SEIS. 

4.1.4.2. Topographic Features 

The MMS has reexamined the analysis for topographic features presented in the Multisale EIS, based 

on the additional information presented below and the addition of the 181 South Area to the proposed 

CPA sale area. No significant new information was found that would alter the impact conclusion for 

topographic features presented in the Multisale EIS. New information was found that supports the 

previous assessments contained in the Multisale EIS, which is incorporated by reference, and illustrates 

the potential effects of natural events, especially the cumulative impacts of hurricanes. Since the 181 

South Area is 129 mi (207 km) from the nearest topographic feature, transiting service vessels would be 

the only likely impact from the 181 South Area on topographic features. Since the closest topographic 

feature habitats are deep, >56 m (184 ft) to their tops, it is unlikely that the 181 South Area would result 

in any effect unless a transiting vessel has a catastrophic accident near a bank. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. The routine activities associated with a CPA or WPA proposed 

action that would impact topographic feature communities include anchoring, infrastructure and pipeline 

emplacement, infrastructure removal, drilling discharges, and produced-water discharges. However, 

adherence to the proposed Topographic Features Stipulation would make damage to the ecosystem 

unlikely. Contact with accidentally spilled oil would cause lethal and sublethal effects in benthic 

organisms, but the oiling of benthic organisms is not likely because of the small area of the banks, the 

scattered occurrence of spills, the depth of the features, and because the proposed Topographic Features 

Stipulation would keep subsurface sources of spills away from the immediate vicinity of topographic 

features. Cumulative activities including natural disturbances, fishing, anchoring, treasure salving, and 

oil spills could cause severe damage that could threaten the survival of topographic feature communities. 

The incremental contribution of a CPA or WPA proposed action to the cumulative impact is expected to 

be slight, and negative impacts should be restricted by the implementation of the Topographic Feature 

Stipulation and site-specific mitigations, the depths of the features, and water currents in the topographic 

feature area. 

4.1.4.2.1. Description of the Affected Environment 

Some areas of the continental shelf in the CPA and WPA are characterized by topographic features 

that are inhabited by hard-bottom benthic communities. The habitat created by the topographic features is 

important for the following reasons: 

(1) they support hard-bottom communities of high biomass, high diversity, and high 

numbers of plant and animal species; 

(2) they support, either as shelter or food, or both, large numbers of commercially and 

recreationally important fishes; 

(3) they are unique to the extent that they are small, isolated areas of such communities 

in vast areas of much lower diversity; 

(4) they provide a relatively pristine area suitable for scientific research; and 
Environmental and Socioeconomic Consequences 4-63 

(5) they have an aesthetically intrinsic value. 

Figure 4-2 depicts the location of 37 known topographic features in the Gulf of Mexico; 16 in the 

CPA and 21 in the WPA. No topographic features are located in the 181 South Area. 

The description of the biology of topographic features can be found in Chapter 3.2.2.1.2 of the 

Multisale EIS. Benthic organisms on these features are mainly limited by temperature, turbidity, and low 

light. Temperatures lower than 16 o

C reduce coral growth, while temperatures in excess of 32 oC will 

impede coral growth and induce coral bleaching (loss of symbiotic zooxanthellae). Light penetration in 

the Gulf is limited by several factors, including depth and events of prolonged turbidity. Hard substrates 

favorable to colonization by coral communities in the northern Gulf are found on outer shelf, high-relief 

features. 

In 1998, USGS, in cooperation with MMS and the Flower Garden Banks National Marine Sanctuary, 

surveyed the East and West Flower Garden Banks using high-resolution, multi-beam mapping techniques 

(Gardner et al., 1998). In 2002, they mapped 12 more topographic features, including Alderdice, Sonnier, 

Geyer, Bright, Rankin (1 and 2), Jakkula, McNeil, Bouma, McGrail, Rezak, and Sidner Banks (Gardner et 

al., 2002a). These surveys reveal complex bathymetry in some areas surrounding the banks outside the 

No Activity Zones. These small features surrounding the banks are considered important fish habitat and 

are protected by MMS from impacts of oil and gas activities. The depth of these banks reduces the effects 

of storms on the habitats. The most common influence of strong storms on these banks is an increase in 

turbidity, generally at the lower levels of the banks. Turbidity and sedimentation are normal in these 

lower levels because of the nepheloid layer and normal resuspension. 

Severe hurricanes can cause physical damage to reef structure and organisms. In September 2005, 

Hurricane Rita passed over the northwestern Gulf of Mexico, affecting at least 18 topographic features. 

The MMS has conducted studies of select topographic features since Hurricane Rita. Long-term 

monitoring has continued on a yearly basis at the East and West Flower Garden Banks through an equal 

partnership between MMS and NOAA’s National Marine Sanctuary program. Another MMS study, 

Post-Hurricane Assessment of Sensitive Habitats of the Flower Garden Banks Vicinity (Robbart et al., in 

preparation), is investigating hurricane effects at the East Flower Garden, Sonnier, McGrail, Geyer, and 

Bright Banks. Initial assessment of the East Flower Garden Bank reveals mechanical damage from 

Hurricane Rita and a significant bleaching event (up to 46% of corals). This was followed by an outbreak 

of coral disease affecting up to 8 percent of corals at the East Flower Garden Bank. These are the most 

severe recorded outbreaks of bleaching and disease at the Flower Garden Banks. Other preliminary 

results suggest little hurricane damage to McGrail, Geyer, and Bright Banks but severe damage at Sonnier 

Bank (Robbart et al., in preparation). Speculation is that Sonnier Bank was more affected because of its 

shallower depth and position on the east side of the storm track. It is also thought that repeated anchor 

damage has affected Sonnier Bank. Community recovery is expected to take at least 5 years if future 

anchor damage is prevented. Monitoring at the Flower Garden Banks in 2006 and 2007 shows good 

recovery of corals with no significant deterioration of community health (Precht et al., 2006; Precht et al., 

2008). 

A search was conducted for additional new information published since completion of the Multisale 

EIS. Various Internet sources 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. 

One ongoing study of Sonnier Bank reports some preliminary results that indicate small shifts in 

benthic cover, including an increase in algae and a decrease in sponges (Rooker et al., in preparation). 

They also report some shifts in fish community composition. These shifts are likely the result of impacts 

from Hurricane Rita in September 2005. 

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. 
4-64 Central and Western Gulf of Mexico Multisale Supplemental EIS

4.1.4.2.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on topographic feature communities (or banks) is presented in Chapters 4.2.2.1.4.1.2 and 

4.2.1.1.4.1.1 of the Multisale EIS, respectively. The following is a summary of the information presented 

in the Multisale EIS, which incorporates new information found since the publication of the Multisale 

EIS. 

The 181 South Area is 129 mi (207 km) from the nearest topographic feature. 

The routine activities associated with a CPA or WPA proposed action that would impact topographic 

feature communities include anchoring, infrastructure and pipeline emplacement, infrastructure removal, 

drilling discharges, and produced water discharges. 

The Topographic Features Stipulation is described in detail in Chapter 2.4.1.3.1 of the Multisale EIS. 

It is a mitigating measure for leases resulting from a proposed action. The stipulation is designed to 

prevent drilling activities and anchor emplacement from damaging the banks (the major potential 

impacting factors on these hard bottoms resulting from offshore oil and gas activities). 

Anchoring is potentially the most damaging impact, having the ability to destroy lush biological 

assemblages and damage the structure of the banks themselves. Anchors can destroy a swath of habitat 

by dragging over the seafloor or the anchor chain can sweep a wide area of the seafloor. 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 hard-bottom areas. The banks could be targets for anchoring 

since the water depth is shallower over the banks. However, this is more likely a factor for smaller 

vessels, such as fishing boats, rather than service vessels. 

Infrastructure and pipelines could be placed over topographic feature habitat, crushing the benthic 

community and damaging the structure of the habitat itself. While damage from a pipeline would likely 

affect a very limited area, the associated anchors and anchor chain/cables of a traditional pipelaying barge 

could devastate a wide swath of habitat along each side of the pipeline route. 

Both explosive and nonexplosive structure-removal operations will disturb the seafloor and 

potentially affect nearby bank communities. Structure removal using explosives suspends sediments that 

will settle on nearby biotic communities. However, the heaviest sedimentation would not travel far and 

would not likely reach the upper portions of topographic features. The reef community can withstand 

some episodic sedimentation, and the organisms that colonize the lower parts of banks are adapted to 

turbid environments. Explosive structure removals create shock waves, which harm biota in the 

immediate vicinity. Organisms with swim bladders, such as fish, are most affected by blasts; most 

stationary benthic animals are remarkably resistant to these effects (O’Keeffe and Young, 1984). 

Discharges of drilling cuttings and fluids can affect benthic organisms in the immediate vicinity of the 

activity. Cuttings can build layers up to 12 in (30 cm) thick near the well, smothering most sessile 

organisms. In addition, the cuttings may contain contaminants that are detrimental to the growth and 

development of organisms. The Topographic Features Stipulation requires shunting of drill cuttings and 

fluids to within 10 m (33 ft) of the bottom to protect the more sensitive organisms on the upper portions 

of the reef. 

Produced-water discharges contain high amounts of dissolved solids and total organic carbon, and 

low dissolved oxygen. Other common components include heavy metals, elemental sulfur and sulfide, 

organic acids, treating chemicals, and emulsified and particulate crude oil constituents. The salinity of 

produced water can vary from 0 to 300 ppt. These products, if discharged directly on topographic feature 

habitats, would have harmful effects on the community. The Topographic Features Stipulation keeps 

discharges far enough away to protect the habitat. 

CPA Proposed Action Analysis 

The routine activities associated with a proposed action that would impact topographic feature 

communities in the CPA include anchoring, infrastructure and pipeline emplacement, infrastructure 

removal, drilling discharges, and produced-water discharges. 
Environmental and Socioeconomic Consequences 4-65 

For a CPA proposed action, 395-564 new exploration/delineation and development wells and 28-40 

new production structures are projected. The area is expected to have 24-36 structures removed, with 

14-16 of them using explosives. About 130-2,075 km (80-1,289 mi) of new pipeline installation is 

projected. Approximately 119,000-241,000 service-vessel trips are expected to result from the CPA 

proposed action. Less than 2 percent of the CPA lease blocks contact topographic-feature protection 

zones. Therefore, only a small percentage of the projected new activity listed above is expected to be 

near topographic features. 

The 181 South Area is 129 mi (207 km) from the nearest topographic feature in the CPA. Transiting 

service vessels would be the only likely connection between the two areas. Since the closest topographic 

feature habitats are deep, >56 m (184 ft) to their tops, it is unlikely that the 181 South Area would result 

in any effect unless a transiting vessel has a catastrophic accident near a bank. 

Anchoring is potentially the most damaging impact to topographic features. The low percent of 

blocks having topographic features limits the likelihood that structures will be installed near a bank. 

Permit requests for activity in the vicinity of topographic features will receive close scrutiny to ensure 

protection based on the Topographic Features Stipulation. This greatly limits the likelihood of damage to 

the habitat. Most service vessels will travel to other locations, only occasionally transiting over a 

topographic feature. The Topographic Features Stipulation would prohibit activities from causing direct 

impacts to topographic feature communities by prohibiting activities on the habitat and limiting 

discharges in surrounding protection zones. 

Very little new infrastructure is expected near topographic features. If the proposed lease stipulation 

is applied and followed, the benthic community should suffer no damaging impacts. None have been 

reported in the past. No bottom-disturbing activity is allowed within the No Activity Zones. Drill 

cuttings and fluids within the 1,000-m (3,281-ft), 1-mi (1.6-km), 3-mi (4.8-km), and 4-mi (6.4-km) zones 

must be shunted to within 10 m (33 ft) of the bottom. NTL 2004-G05 recommends that bottomdisturbing activities must be located at least 152 m (500 ft) from the No Activity Zones. Trenching is not 

required for pipelines in depths of over 60 m (200 ft); no CPA topographic features are found in depths 

shallower than this. Pipeline routes would avoid topographic feature habitat. 

About 24-36 structure removals are projected for the CPA; 14-16 of these could be explosive 

removals. Any removals requested in a topographic feature area will be scrutinized very carefully. 

Options will be explored for using alternative methods during site clearance operations to minimize 

potential impact to hard-bottom communities. Techniques may require remote-sensing surveys to 

identify and recover debris. Topographic Features Stipulation requirements protecting the habitat would 

take precedence. 

Produced-water discharges would be separated from sensitive, hard-bottom habitat the same as drill 

cuttings and fluids. Discharges are at the sea surface and would disperse and dilute before reaching the 

bank habitats. The Topographic Features Stipulation keeps impacts far enough away to protect the habitat 

from direct impacts. 

WPA Proposed Action Analysis 

The routine activities associated with a proposed action that would impact topographic feature 

communities in the WPA include anchoring, infrastructure and pipeline emplacement, infrastructure 

removal, drilling discharges, and produced-water discharges. 

For a WPA proposed action, 197-287 new exploration/delineation and development wells and 28-41 

new production structures are projected. The area is expected to have 20-31 structures removed, with 

11-17 of them using explosives. About 130-760 km (80-472 mi) of new pipeline installation is projected. 

Approximately 94,000-155,000 service-vessel trips are expected to result from a WPA proposed action. 

Less than 4 percent of the WPA lease blocks contact topographic feature protection zones. Therefore, 

only a small percentage of the projected new activity listed above is expected to be near topographic 

features. 

Anchoring is potentially the most damaging impact to topographic features. The low percent of 

blocks having topographic features limits the likelihood that structures will be installed near a bank. 

Permit requests for activity in the vicinity of topographic features will receive close scrutiny to ensure 

protection based on the Topographic Features Stipulation. This greatly limits the likelihood of damage to 

the habitat. Most service vessels will travel to other locations, only sometimes transiting over a 
4-66 Central and Western Gulf of Mexico Multisale Supplemental EIS

topographic feature. The Topographic Features Stipulation would prohibit activities from causing direct 

impacts to topographic feature communities by prohibiting activities on the habitat and limiting 

discharges in surrounding protection zones. 

Very little new infrastructure is expected near topographic features. If the proposed lease stipulation 

is applied and followed, the benthic community should suffer no damaging impacts. None have been 

reported in the past. No bottom-disturbing activity is allowed within the No Activity Zones. Drill 

cuttings and fluids within the 1,000-m (3,281-ft), 1-mi (1.6-km), 3-mi (4.8-km), and 4-mi (6.4-km) zones 

must be shunted to within 10 m (33 ft) of the bottom. NTL 2004-G05 recommends that bottomdisturbing activities must be located at least 152 m (500 ft) from the No Activity Zones. Trenching is not 

required for pipelines in depths of over 60 m (200 ft); only two WPA topographic features are found in 

depths shallower than this, at about 50 m (164 ft). Pipeline routes would avoid topographic feature 

habitat. 

About 20-31 structure removals are projected for the WPA; 11-17 of these could be explosive 

removals. Any removals requested in a topographic feature area will be scrutinized very carefully. 

Options will be explored for using alternative methods during site clearance operations to minimize 

potential impact to hard-bottom communities. Techniques may require remote-sensing surveys to 

identify and recover debris. Topographic Features Stipulation requirements protecting the habitat would 

take precedence. 

Produced-water discharges would be separated from sensitive, hard-bottom habitat the same as drill 

cuttings and fluids. Discharges are at the sea surface and would disperse and dilute before reaching the 

bank habitats. The Topographic Features Stipulation keeps impacts far enough away to protect the habitat 

from direct impacts. 

Summary and Conclusion 

The routine activities associated with a CPA or WPA proposed action that would impact topographic 

feature communities include anchoring, infrastructure and pipeline emplacement, infrastructure removal, 

drilling discharges, and produced-water discharges. Since the 181 South Area is 129 mi (207 km) from 

the nearest topographic feature, transiting service vessels would be the only likely connection between the 

two areas. Since the closest topographic feature habitats are deep, >56 m (184 ft) to their tops, it is 

unlikely that the 181 South Area would result in any effect unless a transiting vessel has a catastrophic 

accident near a bank. Adherence to the Topographic Features Stipulation makes damage to the ecosystem 

unlikely. Pipeline routes would avoid topographic feature habitat. Anchor damage and infrastructure 

emplacement is prohibited on a topographic feature habitat. 

The MMS has reexamined the analysis for topographic features presented in the Multisale EIS, based 

on the additional information presented above. No significant new information was found that would 

alter the overall conclusion that impacts to topographic features from routine activities associated with a 

CPA or WPA proposed action would be minimal. 

4.1.4.2.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts upon topographic features (banks) can be found in 

Chapter 4.4.4.1.2 of the Multisale EIS. Refer to Chapters 2.2.1.3.1 and 2.3.1.3.1 for a complete 

description and discussion of the proposed Topographic Features Stipulations. The following is a 

summary of the information presented in the Multisale EIS, which incorporates new information found 

since publication of the Multisale EIS. 

Accidental disturbances resulting from a proposed action in the CPA or WPA, including oil spills, 

blowouts, chemical spills, and vessel collisions have the potential to disrupt and alter the environmental, 

commercial, recreational, and aesthetic values of topographic features of both the CPA and WPA. 

Oil spills potentially affecting topographic features and their biological communities could result 

from surface and seafloor spills. Both surface and subsurface spills could result in a steady discharge of 

oil over a long period of time. Surface oil spills may occur as a result of platform or tanker spills. The 

depth to which topographic features rise in the northern Gulf of Mexico (to within 15 m [49 ft] of the sea 
Environmental and Socioeconomic Consequences 4-67 

surface) should protect any of the reef plant and animal species they harbor from surface oil slicks. Oil 

from a surface spill can be driven into the water column; measurable amounts have been documented 

down to a 10-m (33-ft) depth, although modeling exercises have indicated such oil may reach a depth of 

20 m (66 ft). At this depth, the oil is found at concentrations several orders of magnitude lower than the 

amount shown to have an effect on corals (Lange, 1985; McAuliffe et al., 1975 and 1981; Knap et al., 

1985). Any dispersed oil that reaches the benthic dwellers would be expected to be at concentrations of 

less than 1 ppm. Such low oil concentrations would not be life threatening to larval or adult stages at that 

depth (Fucik et al., 1994). Because the crests of topographic features in the northern Gulf are found 

below 10 m (33 ft), no concentrated oil from a surface spill is expected to reach their sessile biota. 

Seafloor spills could be caused by a tanker accident, pipeline rupture, or well blowout. However, a 

subsurface spill should rise to the surface, and any oil remaining at depth would probably be swept clear 

of the banks by currents moving around the banks (Rezak et al., 1983). Evidence from a recent 

experiment in the North Sea indicates that oil released during a deepwater blowout would quickly rise to 

the surface and form a slick (Johansen et al., 2001). Impacts from a deepwater oil spill would occur in the 

water column and at the surface where the oil would be mixed into the water and dispersed by wind 

waves. If some oil were to contact topographic features, the impacts would be primarily sublethal, with 

the disruption or impairment of a few elements at the local scale, but no interference to the general system 

performance would occur. The sublethal effects 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). It 

is anticipated that the potential recovery for such an event would occur within a period of 2 years 

(USDOC, NOAA, Office of Response and Restoration, 2007; Shigenaka, 2001; Rice et al., 1983). In the 

highly unlikely event that oil from a subsurface spill reached an area containing coral cover (e.g., Flower 

Garden Banks and Stetson Bank) in lethal concentrations, the impacted area would be small, but its 

recovery could take in excess of 10 years. 

NTL 2004-G05 recommends that drilling would not occur within 152 m (500 ft) of a No Activity 

Zone, so blowouts would not occur in the immediate vicinity of the topographic features and associated 

biota. Therefore, hazardous concentrations of oil would be unlikely to reach the topographic features. 

Oil spills originating outside the No Activity Zones would rise to the surface and be dispersed to diluted 

concentrations in the water column prior to reaching topographic features (CSA, 1992b and 1994). 

Common OCS-related chemicals spilled are methanol, ethylene glycol, zinc bromide, and ammonium 

chloride. Two chemicals could potentially impact the marine environment—zinc bromide and 

ammonium chloride (Boehm et al., 2001). Most other chemicals are either nontoxic or used in small 

quantities. Precipitation of zinc in marine waters would minimize the potential for impact. Ammonium 

chloride disassociates to temporarily elevate the levels of ammonia in the spill vicinity. Chemical 

dispersants can be used in the remediation of oil spills to promote mixing with the water and faster 

degradation. These would probably not be approved for use during the time of coral spawning (AugustSeptember). 

Vessel collisions can result in spills of oils, fuels, and chemicals. Collision of a service vessel with a 

platform could result in spills from the vessel, the platform, or both. It could also cause a moored 

structure to drag anchors or break loose from anchors and subsequently impact a topographic feature. A 

collision could potentially result in the sinking of a vessel with direct physical impacts to a topographic 

feature. If a sunken vessel landed on or near a sensitive habitat, leaking fluids could contact the habitat 

directly. From 1996 to 2005, there were 129 OCS-related collisions, mostly with platforms or pipeline 

risers. Diesel fuel is the product most frequently spilled, while corrosion inhibitor, hydraulic fluid, lube 

oil, and methanol have also been released. Approximately 10 percent of vessel collisions with platforms 

in the OCS caused diesel spills. Minimal impacts result from a spill since diesel is light and will 

evaporate and biodegrade within a few days. 

A search was conducted for new information published since completion of the Multisale EIS. 

Various Internet sources were examined to determine any recent information regarding topographic 

features. Sources investigated include USGS, NOAA, USEPA, and coastal universities. Other sites were 

found through general Internet searches. 

Since Hurricanes Katrina and Rita in 2005, MMS has identified 154 spills of petroleum products of 

>1 bbl, totaling 17,077 bbl that were lost from platforms, rigs, and pipelines on the Federal OCS (USDOI, 

MMS, 2007e). There were no accounts of environmental consequences, including impacts to topographic 

features, resulting from OCS spills identified with Hurricanes Katrina and Rita. 
4-68 Central and Western Gulf of Mexico Multisale Supplemental EIS

CPA Proposed Action Analysis 

The CPA contains 15 named topographic features that are protected from impacts by oil and gas 

activity by the MMS, all in waters less than 200 m (656 ft) deep. 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. As explained in Chapter 3.2.1, the incremental increase in oil production from the 

addition of the 181 South Area is not expected to result in an overall increase in the numbers of oil spills 

≥1,000 bbl likely to occur as a result of a CPA proposed action. For a CPA proposed action including the 

181 South Area, the probability of an oil spill ≥1,000 bbl occurring and passing over Sonnier Bank 

remains 3-5 percent and it is 2-3 percent for the Flower Garden Banks. The shallowest water depth over a 

bank in the CPA is about 18 m (60 ft) at Sonnier Bank. Depths to other banks are in excess of 30 m 

(100 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). Based on OCS spill rates, the incremental increase in oil production from the 

addition of the 181 South Area is not expected to result in an overall increase in the numbers of oil spills 

≥500 bbl likely to occur as a result of a CPA proposed action. 

Approximately 2-3 blowouts are projected to occur in the CPA during activities resulting from the 

proposed actions. With the application of the proposed stipulations, none of these blowouts should occur 

within 152 m (500 ft) of the No Activity Zones on protected banks. Furthermore, blowouts outside the 

No Activity Zones are unlikely to impact the biota of topographic features because oil will rapidly float to 

the surface. 

Since collisions occur infrequently, the potential impacts to topographic features in the CPA are not 

expected to be significant. Chemical spills are also infrequent, of small quantity, and usually occur in 

surface waters. No significant impacts to topographic features in the CPA are expected. 

The proposed Topographic Features Stipulation will assist in preventing most of the potential impacts 

from oil and gas operations including accidental oil spills, blowouts, vessel collisions, and chemical spills 

on the biota of topographic features. 

WPA Proposed Action Analysis 

The WPA contains 22 named topographic features that are protected from impacts by oil and gas 

activity by the MMS, all in water depths <200 m (656 ft). They represent a small fraction of the 

continental shelf area in the WPA. 

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. For a WPA proposed action, the probability of an oil spill ≥1,000 bbl occurring and 

passing over Stetson Bank is 2-4 percent and it is 4-7 percent for the Flower Garden Banks. The East 

Flower Garden Bank rises to within 16 m (53 ft) of the sea surface, and the West Flower Garden Bank 

rises to within 18 m (59 ft). The next shallowest bank in the WPA is Stetson Bank at 20 m (65 ft). 

Depths to other banks are in excess of 30 m (100 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). 

Approximately 1-2 blowouts are projected to occur in the WPA during activities resulting from the 

proposed actions. With the application of the proposed stipulations, none of these blowouts should occur 

within 152 m (500 ft) of the No Activity Zones on protected banks. Furthermore, blowouts outside the 

No Activity Zones are unlikely to impact the biota of topographic features because oil will rapidly float to 

the surface. 

Since collisions occur infrequently, the potential impacts to topographic features in the WPA are not 

expected to be significant. Chemical spills are also infrequent, of small quantity, and usually occur in 

surface waters. No significant impacts to topographic features in the WPA are expected. 

The proposed Topographic Features Stipulation will assist in preventing most of the potential impacts 

from oil and gas operations including accidental oil spills, blowouts, vessel collisions, and chemical spills 

on the biota of topographic features. 
Environmental and Socioeconomic Consequences 4-69 

Summary and Conclusion 

Contact with accidentally spilled oil would cause lethal and sublethal effects in benthic organisms. 

The oiling of benthic organisms is not likely because of the small area of the banks, the scattered 

occurrence of spills, the depth of the features, and because the proposed Topographic Features Stipulation 

would keep subsurface sources of spills away from the immediate vicinity of topographic features. 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 adult sessile biota, including coral colonies in the case of the Flower 

Garden Banks, and there would be limited incidences of mortality. 

The MMS has reexamined the analysis for topographic features presented in the Multisale EIS, based 

on the additional information presented above. This new information supports the previous assessments. 

No significant new information was found that would alter the overall conclusion that impacts on 

topographic feature communities from accidental impacts associated with a CPA or WPA proposed action 

would be minimal. 

4.1.4.2.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts on topographic features can be found in Chapter 

4.5.4.1.2 of the Multisale EIS. The following is a summary of the information presented in the Multisale 

EIS, which incorporates new information found since publication of the Multisale EIS. 

There are 37 topographic features (banks) protected by the MMS in the Gulf of Mexico. This 

cumulative analysis considers the effects of impact-producing factors related to the proposed actions plus 

those related to prior and future OCS lease sales, and to tanker and other shipping operations that may 

occur and adversely affect topographic feature communities. Non-OCS-related impacts, including natural 

disturbances, fishing, anchoring, treasure salving, and oil spills have the potential to alter topographic 

features. Specific OCS-related impact-producing factors considered in the analysis are infrastructure 

emplacement and removal, anchoring, drilling discharges, produced waters, oil spills, blowouts, chemical 

spills, and vessel collisions. Because the 181 South Area is 129 mi (207 km) from the nearest 

topographic feature, the only cumulative effect produced by its addition to a CPA proposed action is a 

small increase in the incremental impacts of vessel traffic. 

It is assumed protective stipulations for the topographic features will be part of appropriate OCS 

leases and existing site/project-specific mitigations will be applied to OCS activities on these leases or 

supporting activities on these leases. 

Non-OCS activities have a greater potential to affect the hard-bottom communities of the region than 

MMS-regulated activities. Natural disturbances such as hurricanes and extreme fluctuations of 

environmental conditions (e.g., nutrient pulses, low dissolved oxygen levels, seawater temperature 

minima, and seasonal algal blooms) can affect topographic feature communities. Hurricanes can produce 

waves that reach the crest of the topographic features to destroy and remove organisms. The height of 

topographic features above the surrounding soft bottoms elevates most of the reef community above the 

common effects of bottom currents that resuspend soft sediments. Organisms on the lower part of the reef 

are adapted to high turbidity. 

Recreational boating and fishing may severely impact topographic feature communities. Anchor 

damage by fishing boats appears to be a serious problem at Sonnier Bank (Robbart et al., in preparation; 

Rooker et al., in preparation). Bottom longlining could potentially result in cumulative impacts to 

topographic feature communities. If contact did occur, impacts from bottom longlines would be minimal. 

Ships anchoring near major shipping fairways, on occasion, may impact sensitive areas located near these 

fairways. 

Treasure salvage operations have targeted one bank for over 20 years, causing extensive damage to 

the reef community. Bright Bank, on the shelf-edge about 160 km (100 mi) south of Cameron, Louisiana, 

has numerous excavation sites reaching 1-4 m (3-12 ft) into the reef and up to 4 m (12 ft) across. Large 

coral heads appear to have been tumbled down the slope into deeper water (Hickerson, personal 

communication, 2007). 
4-70 Central and Western Gulf of Mexico Multisale Supplemental EIS

Oil and chemical spills from non-OCS-related impacts could result from vessel collisions and other 

accidents. While an unlikely event (<1/yr), import tanker accidents could produce the largest offshore 

spills. These oil and chemical spills will have the same effect as described below for OCS-related 

impacts. 

Oil and gas activities produce cumulative effects on the offshore environment. The Topographic 

Features Stipulation prevents direct impacts to topographic feature communities. The placement of 

structures on the seafloor crushes organisms and can cause scouring of the surficial sediments (Caillouet 

et al., 1981). The effect of pipeline-laying activities on the biota of topographic feature communities 

would be restricted to the temporary resuspension of sediments resulting in sublethal effects over small 

areas. 

Explosive and nonexplosive structure-removal operations disturb the seafloor. Structure removal 

using explosives (the most common removal method) can suspend sediments, which settle much in the 

same manner as discussed below for muds and cuttings discharges. Shock waves in the seafloor are 

attenuated within 100 m (328 ft) from the structure (Baxter et al., 1982). Resuspended sediments would 

impact an area within a radius of approximately 1,000 m (3,281 ft). The explosive removal of structures 

is expected to have minimal effects on topographic feature communities. 

Anchor damage from support boats and ships, floating drilling units, and pipeline-laying vessels are 

considered the greatest potential OCS-related threat to topographic feature areas. Anchoring can destroy 

a wide swath of habitat when a vessel drags or swings at anchor, causing the chain to drag across the 

seafloor. The biological stipulations limit the proximity of new activities to topographic features. The 

misplacement of anchors could severely impact hard-bottom substrate, which has recovery rates (which 

are not well documented) estimated at 5-20 years depending on the severity. These impacts are unlikely 

due to the 500 ft (152 m) buffer area around topographic features. 

Routine discharges of drilling muds and cuttings by oil and gas operations could smother organisms 

or produce less obvious sublethal toxic effects. Lease stipulations and site-specific mitigations would 

prevent drilling discharges directly over topographic feature habitat. Most drilling discharges in the 

vicinity of topographic features are shunted to the seafloor. Drilling discharges should reach undetectable 

concentrations in the water column within 1,000 m (3,281 ft) of the discharge point, thus limiting 

potential toxic effects to benthic organisms. Effects would diminish rapidly with increasing distance from 

the discharge area. The levels of contaminants in the water column and sediments are expected to be well 

below the new USEPA discharge regulations and permits (Chapter 4.1.3.4 of the Multisale EIS). The 

deposition of drilling muds and cuttings in topographic feature areas is not expected to greatly impact the 

biota or the habitat. The impact from muds and cuttings discharged as a result of the cumulative scenario 

would be temporary, primarily sublethal in nature, and the effects would be limited to small areas. 

Produced waters would be discharged at the surface; the depth of the topographic features, currents, 

and lateral offset of discharges would render the wastes harmless to the habitat. Adverse impacts of 

cumulative activities would therefore be temporary, primarily sublethal in nature, and the effects would 

be limited to small areas. Predicted recovery to pre-impact conditions from these sublethal impacts would 

take place within 5 years. 

Surface spills of oil can be mixed into the water column by wave turbulence. Measurable amounts 

have been documented down to a 10-m (33-ft) depth, and models have indicated such oil may reach a 

depth of 20 m (66 ft). Concentrations at these depths would be several orders of magnitude lower than 

the amount required to effect marine organisms (Lange, 1985; McAuliffe et al., 1975 and 1981). Since 

topographic features reside below 20-m (66-ft) water depth, surface spills would not impact the biota. 

Subsurface pipeline oil spills are not expected to cause damage to topographic feature biota because 

the oil would rise rapidly to the sea surface (Johansen et al., 2001). There is little probability that a 

subsurface oil spill will impact topographic features since the lease stipulations prevent the installation of 

pipelines in their immediate vicinity. The adverse impacts from subsurface oil spills on topographic 

features would be minor in scope, primarily sublethal in nature, and the effects would be contained within 

a small area. Recovery to pre-impact conditions from these sublethal impacts would take place within 

5-10 years. 

Subsurface blowouts can resuspend sediments and release hydrocarbons into the water column near 

topographic feature communities. The continued implementation of lease stipulations and site-specific 

mitigations should prevent blowouts from occurring directly on topographic features. A severe 

subsurface blowout within 400 m (1,312 ft) of a topographic feature could result in the smothering of the 
Environmental and Socioeconomic Consequences 4-71 

biota due to sedimentation. Since the topographic feature biota at the deeper levels is adapted to turbid 

conditions, most impacts would probably be sublethal with recovery taking place within 5 years. 

Common OCS-related chemicals spilled are methanol, ethylene glycol, zinc bromide, and ammonium 

chloride. The last two could potentially impact the marine environment; most other chemicals are either 

nontoxic or used in small quantities (Boehm et al., 2001). The effects of ammonium chloride would be 

rapidly diluted, and zinc quickly precipitates out of solution. Chemical dispersants used on the sea 

surface would be thoroughly diluted before reaching the topographic feature community. 

Vessel collisions can result in spills of oils, fuels, and chemicals. If a sunken vessel landed on or near 

a sensitive habitat, leaking fluids could contact the habitat directly. Diesel fuel is the product most 

frequently spilled, while corrosion inhibitor, hydraulic fluid, lube oil, and methanol have also been 

released. Minimal impacts result from a spill since diesel is light and will evaporate and biodegrade 

within a few days. In the unlikely event a freighter, tanker, or other ocean-going vessel related to OCS 

Program activities sank and proceeded to collide with a topographic feature or associated habitat, 

releasing its cargo, recovery capabilities from such a catastrophic scenario are unknown at this time. 

Should the Topographic Features Stipulation not be implemented, OCS activities could have the 

potential to destroy part of the biological communities. 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. The OCS Program, with the benefit of protective lease stipulations and 

site-specific mitigations, would have little adverse impact on topographic feature communities and 

habitat. 

Summary and Conclusion 

Non-OCS activities in the vicinity of the hard-bottom communities include natural disturbances, 

fishing, anchoring, treasure salving, and oil spills. These activities could cause severe damage that could 

threaten the survival of topographic feature communities. Ships using fairways in the vicinity of 

topographic features may anchor in the general area of topographic features on occasion, and numerous 

fishermen take advantage of the relatively shallow and easily accessible resources of regional topographic 

features. These activities could lead to severe and permanent physical damage. During severe storms, 

such as hurricanes, large waves can reach the crest of some topographic features with enough force to 

damage the reef community. 

Impact-producing factors resulting from activities of OCS oil and gas operations include 

infrastructure emplacement and removal, anchoring, drilling discharges, produced waters, oil spills, 

blowouts, chemical spills, and vessel collisions. Long-term OCS activities are not expected to adversely 

impact the topographic feature environment if these impact-producing factors are restrained by the 

continued implementation of protective lease stipulations and site-specific mitigations. The inclusion of 

the Topographic Features Stipulation would preclude the occurrence of physical damage, the most 

potentially damaging of these activities. The impacts to the topographic features are judged to be 

infrequent because of the small number of operations in the vicinity of topographic features. The impact 

to the topographic feature resource as a whole is expected to be slight because of the projected lack of 

community-wide impacts. Activities associated with the 181 South Area would produce a small 

incremental increase in impacts due to navigational traffic. 

Potential impact from oil spills >1,000 bbl would be restricted because of the depth of the features 

(>20 m or 66 ft), because subsea pipeline spills are expected to rise rapidly, and because of the low 

prospect of pipelines being routed immediately adjacent to topographic features. The frequency of 

impacts to topographic features should be rare and the severity slight. Impacts from accidents involving 

the misplacement of anchors on topographic features could be severe in small areas (those actually 

crushed or subjected to abrasions). 

The incremental contribution of a CPA or WPA 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 Topographic Features Stipulation and site-specific mitigations, the 

depths of the features, and water currents in the topographic feature area. 

New information published since completion of the Multisale EIS is discussed above in the 

description of the affected environment and incorporated into the impact analyses. No new OCS or non-
4-72 Central and Western Gulf of Mexico Multisale Supplemental EIS

OCS activities were found. New information supports the previous assessments contained in the 

Multisale EIS, which is incorporated by reference, and does not necessitate a reanalysis of the impacts for 

the proposed actions. The 181 South Area is about 129 mi (207 km) from the nearest topographic feature 

and is expected to result in a small increase in the incremental impacts of vessel traffic. The analysis and 

potential impacts detailed in the Multisale EIS remains valid for this SEIS. 

4.1.5. Continental Slope and Deepwater Resources 

The MMS has reexamined the analysis for continental slope and deepwater resources presented in the 

Multisale EIS, based on the additional information presented below and the addition of the 181 South 

Area to the proposed CPA sale area. No significant new information was found that would alter the 

impact conclusion for continental slope and deepwater resources presented in the Multisale EIS. The 181 

South Area is not expected to have any chemosynthetic or hard-bottom, nonchemosynthetic communities 

(such as deepwater corals) that would be exposed to any kind of impacts from routine activities or 

accidental events associated with a proposed action. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Chemosynthetic and nonchemosynthetic communities are 

susceptible to physical impacts from structure placement, anchoring, and pipeline installation associated 

with a CPA or WPA proposed action; however, the guidance provided in NTL 2000-G20 greatly reduce 

the risk of these physical impacts by requiring avoidance of potential chemosynthetic communities and by 

consequence avoidance of other hard-bottom communities. Even in situations where 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 a CPA or WPA 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. 

The most serious, cumulative, impact-producing factor threatening chemosynthetic and 

nonchemosynthetic communities is physical disturbance of the seafloor by OCS activities, which could 

destroy the organisms of these communities. The incremental contribution of a proposed action to the 

cumulative impacts is expected to be slight, and adverse impacts will be limited but not completely 

eliminated by adherence to NTL 2000-G20. 

4.1.5.1. Description of the Affected Environment 

4.1.5.1.1. Chemosynthetic Communities 

A detailed description of the biology, life history, and distribution of chemosynthetic, deepwater 

benthic communities can be found in Chapter 3.2.2.2.1 of the Multisale EIS. The following is a summary 

of the information presented in the Multisale EIS, which incorporates new information found since the 

publication of the Multisale EIS. 

Chemosynthetic communities are remarkable in that they utilize a carbon source independent of 

photosynthesis and the sun-dependent photosynthetic food chain that supports most all other life on earth. 

Although the process of chemosynthesis is entirely microbial, chemosynthetic bacteria and their 

production can support thriving assemblages of higher organisms through symbiosis. The 

chemosynthetic communities of the Gulf of Mexico have been studied extensively over the past 21 years, 

and communities first discovered on the upper slope of the Gulf of Mexico are likely the best understood 

seep communities in the world. The discovery history of these remarkable animals has all occurred 

within only the last 30 years. 

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. While the hydrocarbon reservoirs are broad areas several kilometers (miles) beneath the 

Gulf, chemosynthetic communities occur in isolated areas with thin veneers of sediment only a few 
Environmental and Socioeconomic Consequences 4-73 

meters (feet) thick. What was initially thought to be relatively rare occurrences of chemosynthetic 

communities is now known to be far more common and regularly associated with primary geophysical 

signatures of the seabed, including faulting with conduits for hydrocarbons to the surface from deeper 

depths and precipitation of carbonate deposits on the seafloor. Anomalies of seismic survey acoustic 

amplitudes are one major feature related to most known chemosynthetic communities, and these kinds of 

features are now relatively well mapped throughout the entire northern Gulf of Mexico. The total number 

of features on the northern Gulf slope that have probable associated communities now number in the 

thousands. 

Additional research was conducted to investigate recently available information since completion of 

the Multisale 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. In addition, there is an ongoing MMS/National Oceanic 

and Atmospheric Administration Office of Ocean Exploration (NOAA-OE) co-sponsored research 

project, Investigations of Chemosynthetic Communities on the Lower Continental Slope of the Gulf of 

Mexico, specifically targeting chemosynthetic communities in the deep Gulf of Mexico. This study was 

referenced in the Multisale EIS (USDOI, MMS, 2007b). Some new chemosynthetic communities were 

discovered in 2006 and 2007; however, they were located using the same criteria used during the 

biological review process for oil and gas operation plans or pipeline applications to determine the 

proximity of areas with potential chemosynthetic communities. 

Chemosynthetic communities are not expected anywhere in the 181 South Area. There are no known 

surface amplitude anomalies and this deep area is not underlain by salt structures that create conditions 

conducive to faulting and hydrocarbon flows similar to other areas of the Gulf. 

4.1.5.1.2. Nonchemosynthetic Communities 

The description of the biology, life history, and distribution of nonchemosynthetic, deepwater benthic 

communities can be found in Chapter 3.2.2.2.2 of the Final Multisale EIS. The following is a summary of 

the information presented in the Multisale EIS, which incorporates new information found since the 

publication of the Multisale EIS. 

A proposed lease sale area encompasses a vast range of habitats and water depths. The shallowest 

lease area encompasses the entirety of the upper slope, regardless of the depth criteria used to define the 

continental slope. The deepest portions extend nearly into the deepest part of the Gulf of Mexico at 

approximately 3,500 m (11,485 ft) south of the Sigsbee Escarpment in the Central Gulf. The additional 

181 South Area is also very deep, ranging from 2,700 to 3,200 m (8,900 to 10,500 ft). 

Other types of communities in the deep Gulf include the full spectrum of living organisms also found 

on the continental shelf or other areas of the marine environment. Major groups include bacteria and 

other microbenthos, meiofauna (0.063-0.3 mm or 0.002-0.012 in), macrofauna (>0.3 mm or >0.012 in), 

and megafauna (larger organisms such as crabs, sea pens, crinoids, and demersal fish). All of these 

groups are represented throughout the entire Gulf of Mexico—from the continental shelf to the deepest 

abyss at about 3,850 m (12,630 ft). Recent study results in Rowe (2002) have indicated some unique 

areas near the Mississippi River delta with substantially higher community biomass and carbon flux. 

Deepwater coral habitats and other potential hard-bottom communities not associated with 

chemosynthetic communities appear to be relatively rare. These unique communities are distinctive and 

similar in nature to protected pinnacles and topographic features on the continental shelf. Interest in 

deepwater corals has increased rapidly in the last decade as more coral systems are discovered worldwide 

and their importance in providing habitat for diverse communities is realized. 

Additional research was conducted to investigate recently available information since completion of 

the Multisale 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 MMS recently published two studies on hardbottom communities with an emphasis on Lophelia coral. The following are summaries of the results of 

these two studies, which will be used to develop additional studies of hard-bottom habitats in the deep 

Gulf of Mexico and will also enhance the ability of MMS to protect sensitive, deepwater biological 

features. 
4-74 Central and Western Gulf of Mexico Multisale Supplemental EIS

The report, Characterization of Northern Gulf of Mexico Deepwater Hard-Bottom Communities with 

Emphasis on Lophelia Coral (CSA, 2007), presents the results of a study of 10 sites on the northern Gulf 

of Mexico continental slope consisting of hard-bottom areas that generally include dense assemblages of 

the coral Lophelia pertusa. Study elements include geological characterization; biological 

characterization, imaging, and sampling; water chemistry; and physical oceanography including shortterm and long-term current meter deployments. This was the first comprehensive study of the distribution 

of Lophelia pertusa and its biology and ecology in the Gulf of Mexico. Results suggest that L. pertusa

plays a significant role in the ecology of hard-bottom habitats on the upper slope. 

The report, Seafloor Characteristics and Distribution Patterns of Lophelia pertusa and Other Sessile 

Megafauna at Two Upper-Slope Sites in the Northeastern Gulf of Mexico (Schroeder 2007), presents 

results of a study funded to document the seafloor characteristics and the distribution patterns of the 

deepwater coral Lophelia pertusa and other sessile megafauna at two sites in the Gulf of Mexico. The 

two sites, Viosca Knoll 826 (VK 826) and Viosca Knoll 862-906 (VK 862-906) are located on the upper 

DeSoto Slope subprovince. One of the sites, VK 862-906, is in close proximity to the site reported from 

the 1950’s field sampling by Moore and Bullis (1960). The dominant taxa at both the VK862 and VK906 

sites, in terms of numbers and biomass, are anemones. The largest megafauna observed were the 

antipatharians at VK 862-906, with individual colonies estimated to be between 2.1 and 2.4 m (7 and 8 ft) 

tall. There appears to be at least four species of antipatharians and, collectively, they are the second most 

abundant megafauna taxa at both sites. The dominant megafauna taxon at the VK 862 site is L. pertusa, 

which has successfully developed extensive assemblage complexes, comprised of large colony 

aggregations/thickets, at numerous locations. The VK 826 site has the most extensive development of 

L. pertusa found in the Gulf of Mexico to date. 

The report also discusses evidence of manmade disturbances. Furrows apparently produced when 

wire anchor cables, deployed in conjunction with oil and gas drilling operations conducted in this region, 

struck the bottom one or more times. When megafauna were present, moderate to severe damage to 

individual colonies or colony aggregations often resulted. However, there was no indication that 

extensive areawide destruction has occurred, although these features are present throughout the main 

knoll survey area. 

In addition, there is an ongoing MMS/NOAA-OE co-sponsored research project, Investigations of 

Chemosynthetic Communities on the Lower Continental Slope of the Gulf of Mexico, specifically 

targeting deepwater coral communities in the deep Gulf of Mexico. This study was referenced in the 

Multisale EIS (USDOI, MMS, 2007b). Some new, deepwater coral communities were discovered in 

2006 and 2007; however, they were located using the same criteria used during the biological review 

process for oil and gas operation plans or pipeline applications to determine the proximity of areas with 

potential chemosynthetic communities that also incorporates hard bottom and potential deepwater coral 

habitats. 

The 181 South Area is not expected to have any unusual biological communities that differ from 

typical, mud-bottom fauna that would normally occur at those depths (2,700-3,200 m or 8,900-10,500 ft). 

No exposed hard-bottom areas that could support coral or other attached communities are known to occur 

in the area. Basic descriptions of typical, soft-bottom fauna (i.e., bacteria, meiofauna, macrofauna, and 

megafauna) are addressed in the Multisale EIS. A great number of publications have derived from the 

two major MMS-funded deep Gulf studies—Rowe (2002) and Gallaway et al. (1988)—from which the 

majority of this summary information is derived. These two studies are incorporated by reference for 

extensive background information on deepwater Gulf of Mexico habitat and biological communities. 

4.1.5.2. Impacts of Routine Events 

4.1.5.2.1. Chemosynthetic Communities 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on chemosynthetic communities is presented in Chapters 4.2.1.1.4.2.1 and 4.2.2.1.4.2.1 

of the Multisale EIS, respectively. 
Environmental and Socioeconomic Consequences 4-75 

Chemosynthetic communities are susceptible to physical impacts from drilling discharges, structure 

placement (including templates or subsea completions), anchoring, or pipeline installation. In deep water, 

discharges of drilling fluids and cuttings at the surface are spread across broader areas of the seafloor and 

are, in general, distributed in thinner accumulations than in shallower areas on the continental shelf. 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 deepwater areas could impact areas of chemosynthetic organisms if they 

were crossed by the pipeline (pipeline burial is not required at depths where chemosynthetic communities 

are found). 

The guidance provided in NTL 2000-G20 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. 

CPA Proposed Action Analysis 

Chemosynthetic communities could be found in the deeper water areas of the CPA (i.e., Subareas 

C400-800, C800-1600, C1600-2400, and C>2400 m). The levels of projected activity in deep water as a 

result of a proposed action in the CPA are shown in Table 3-2. A range of 103-161 oil and gas 

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 the 

deepwater portions of the CPA as a result of a proposed action. 

NTL 2000-G20 recommends the search for and avoidance of dense chemosynthetic communities 

(such as Bush Hill-type communities) or areas that have a high potential for supporting these community 

types, as interpreted from geophysical records. The NTL is exercised on all applicable leases and is not 

an optional protective measure. The requirements and discussion of the effectiveness of the NTL is 

presented in Chapter 4.2.2.1.4.2.1 of the Multisale EIS. 

The 181 South Area is part of the CPA proposed action, but it is not expected to have any 

chemosynthetic communities that would be exposed to any kind of routine impacts. If new geophysical 

survey information did indicate the potential presence of chemosynthetic communities, the same 

biological review process and use of NTL 2000-G20 would apply, resulting in a greatly reduced 

probability of any impacts occurring. 

WPA Proposed Action Analysis 

Chemosynthetic communities could be found in the deeper water areas of the WPA (i.e., Subareas 

W400-800, W800-1600, W1600-2400, and W>2400 m). The levels of projected activity in deep water as 

a result of a proposed action in the WPA are shown in Table 3-3. A range of 60-91 oil and gas 

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 the 

deepwater portions of the WPA as a result of a proposed action. 

NTL 2000-G20 recommends the search for and avoidance of dense chemosynthetic communities 

(such as Bush Hill-type communities) or areas that have a high potential for supporting these community 

types, as interpreted from geophysical records. The NTL is exercised on all applicable leases and is not 

an optional protective measure. The requirements and discussion of the effectiveness of the NTL is 

presented in Chapter 4.2.1.1.4.2.1 of the Multisale EIS. 

Summary and Conclusion 

Chemosynthetic communities are susceptible to physical impacts from structure placement (including 

templates or subsea completions), anchoring, and pipeline installation. The guidance provided in NTL 

2000-G20 greatly reduce the risk of these physical impacts by requiring the avoidance of potential 

chemosynthetic communities. 
4-76 Central and Western Gulf of Mexico Multisale Supplemental EIS

The MMS has reexamined the analysis for impacts to chemosynthetic communities presented in the 

Multisale EIS, based on the additional information presented above. No significant new information was 

found that would alter the overall conclusion that impacts on chemosynthetic communities from routine 

activities associated with a CPA or WPA proposed action would be minimal to none. The 181 South 

Area is not expected to have any chemosynthetic communities that would be exposed to any kind of 

routine impacts. 

4.1.5.2.2. Nonchemosynthetic Communities 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on nonchemosynthetic communities is presented in Chapters 4.2.1.1.4.2.2 and 

4.2.2.1.4.2.2 of the Multisale EIS, respectively. 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, or pipeline installation. In deep water, discharges of drilling 

fluids and cuttings at the surface are spread across broader areas of the seafloor and are, in general, 

distributed in thinner accumulations than in shallower areas on the continental shelf. Carbonate outcrops 

and deepwater coral communities not associated with chemosynthetic communities are considered to be 

most at risk from oil and gas operations. 

The physical disturbances by structures themselves are typically limited to anchors for holding 

floating drilling or production facilities over the well sites. Anchoring will 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 will 

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 large in relation to the 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 chemosynthetic communities are found). Impacts of pipeline contact on soft bottom would 

be minimal. 

CPA Proposed Action Analysis 

The routine activities associated with a CPA proposed action that would impact nonchemosynthetic 

benthic communities would come from activities associated with drilling discharges, structure placement 

(including templates or subsea completions), anchoring, or pipeline installation. For a CPA proposed 

action, 114-174 oil and gas 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 will 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 
Environmental and Socioeconomic Consequences 4-77 

infaunal communities occurred, recolonization from 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, 

carbonate outcrops are targeted as one possible indication (surface amplitude anomaly on 3D seismic 

survey data) that chemosynthetic seep communities could be nearby. 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 >400 m (1,312 ft) 

would automatically trigger the NTL 2000-G20 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. 

There is no evidence of any exposed hard substrate in the 181 South Area that could support 

significant nonchemosynthetic communities and be exposed to any kind of routine impacts. If new 

geophysical survey information did indicate the potential presence of hard-bottom areas (that could 

support deepwater corals or other significant communities), the same biological review process and use of 

NTL 2000-G20 would apply, resulting in a greatly reduced probability of any impacts occurring. 

WPA Proposed Action Analysis 

The routine activities associated with a WPA proposed action that would impact nonchemosynthetic 

benthic communities would come from activities associated with drilling discharges, structure placement 

(including templates or subsea completions), anchoring, or pipeline installation. For a WPA proposed 

action, 65-97 oil and gas 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 W200-400, W400-800, W800-1600, W1600-2400, and W>2400 m (Table 3-3). 

Drilling muds and cuttings discharged at the seafloor or from the surface will have some limited impact to 

soft-bottom 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 from 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, 

carbonate outcrops are targeted as one possible indication (surface amplitude anomaly on 3D seismic 

survey data) that chemosynthetic seep communities could be nearby. 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 depth >400 m (1,312 ft) 

would automatically trigger the NTL 2000-G20 evaluation described above. 

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. 

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. Even in situations 

where the substantial burial of typical benthic infaunal communities occurred, recolonization from 
4-78 Central and Western Gulf of Mexico Multisale Supplemental EIS

populations from widespread neighboring soft-bottom substrate would be expected over a relatively short 

period of time for all size ranges of organisms. 

Impacts to other hard-bottom communities are expected to be avoided as a consequence of the 

application of the existing NTL 2000-G20 for chemosynthetic communities. The same geophysical 

conditions associated with the potential presence of chemosynthetic communities also results in hard 

carbonate substrate that is generally avoided. 

The MMS has reexamined the analysis for impacts to chemosynthetic communities presented in the 

Multisale EIS, based on the additional information presented above. No significant new information was 

found that would alter the overall conclusion that impacts on chemosynthetic communities from routine 

activities associated with a CPA or WPA proposed action would be minimal to none. The 181 South 

Area is not expected to have any sensitive exposed hard bottom that would be exposed to any kind of 

routine impacts. 

4.1.5.3. Impacts of Accidental Events 

4.1.5.3.1. Chemosynthetic Communities 

Background/Introduction 

A detailed description of accidental impacts upon chemosynthetic, deepwater benthic communities 

can be found in Chapter 4.4.4.2.1 of the Multisale EIS. The following is a summary of the information 

presented in the Multisale EIS, which incorporates new information found since publication of the 

Multisale EIS. 

Accidental events that could impact chemosynthetic communities are limited primarily to blowouts. 

A blowout at the seafloor could create a crater and could resuspend and disburse large quantities of 

bottom sediments within a 300-m (984-ft) radius from the blowout site, burying organisms located within 

that distance to some degree. The application of avoidance criteria for chemosynthetic communities 

recommended by NTL 2000-G20 should preclude the impact of a blowout to a distance of at least 457 m 

(1,500 ft). 

Impacts to chemosynthetic communities from any oil released would be a remote possibility. The 

release of hydrocarbons associated with a blowout should not present a possibility for impact to 

chemosynthetic communities located a minimum of 457 m (1,500 ft) from well sites (as recommended by 

NTL 2000-G20). All known reserves in the Gulf of Mexico to date have specific gravity characteristics 

that would preclude oil from sinking immediately after release at a blowout site. The potential for 

weathered components from a surface slick reaching a chemosynthetic community in any measurable 

volume would be very small. 

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. 

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), 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 would permanently 

prevent reestablishment, particularly if hard substrate required for recolonization was buried. 

CPA Proposed Action Analysis 

For water depths >400 m (1,312 ft), 0-2 blowouts are estimated in the CPA. The application of 

avoidance criteria for chemosynthetic communities recommended by NTL 2000-G20 should preclude any 

impact from a blowout at a minimum distance of 457 m (1,500 ft), which is beyond the distance of 

expected benthic disturbance. Resuspended bottom sediments transported by near-bottom currents could 

reach chemosynthetic communities located beyond 457 m (1,499 ft) and potentially impact them by burial 

or smothering. 
Environmental and Socioeconomic Consequences 4-79 

The risk of various sizes of oil spills occurring in the CPA is presented in Tables 3-6 and 3-7. The 

probability of oil in any measurable concentration reaching depths of 400 m (1,312 ft) or greater is very 

small. 

The 181 South Area is part of the proposed CPA sale area but it is not expected to have any 

chemosynthetic communities that would be exposed to any kind of accidental impacts. If new 

geophysical survey information did indicate the potential presence of chemosynthetic communities, the 

same biological review process and use of NTL 2000-G20 would apply, resulting a in greatly reduced 

probability of any impacts occurring. 

WPA Proposed Action Analysis 

For water depths >400 m (1,312 ft), 0-1 blowouts are estimated in the WPA. The application of 

avoidance criteria for chemosynthetic communities recommended by NTL 2000-G20 should preclude any 

impact from a blowout at a minimum distance of 457 m (1,500 ft), which is beyond the distance of 

expected benthic disturbance. Resuspended bottom sediments transported by near-bottom currents could 

reach chemosynthetic communities located beyond 457 m (1,499 ft) and potentially impact them by burial 

or smothering. 

The risk of various sizes of oil spills occurring in the WPA is presented in Tables 3-6 and 3-7. The 

probability of oil in any measurable concentration reaching depths of 400 m (1,312 ft) or greater is very 

small. 

Summary and Conclusion 

Chemosynthetic communities could be susceptible to physical impacts from a blowout depending on 

bottom-current conditions. The guidance provided in NTL 2000-G20 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 emplacement. 

Studies indicate that periods as long as hundreds of years are required to reestablish a seep 

community once it has disappeared (depending on the community type). There is evidence that 

substantial impacts on these communities would permanently prevent reestablishment, particularly if hard 

substrate required for recolonization was buried by resuspended sediments from a blowout. 

Potential accidental impacts from a CPA or WPA proposed action 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 

located at more than 1,500 ft (457 m) away from a blowout could experience minor impacts from 

resuspended sediments. 

The MMS has reexamined the analysis for impacts to chemosynthetic communities presented in the 

Multisale EIS, based on the additional information presented above. No significant new information was 

found that would alter the overall conclusion that impacts on chemosynthetic communities from routine 

activities associated with a CPA or WPA proposed action would be minimal to none. The 181 South 

Area is not expected to have any chemosynthetic communities that would be exposed to any kind of 

accidental impacts. 

4.1.5.3.2. Nonchemosynthetic Communities 

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. The following is a summary of the 

information presented in the Multisale EIS, which incorporates new information found since publication 

of the Multisale EIS. 

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, thus destroying 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, 
4-80 Central and Western Gulf of Mexico Multisale Supplemental EIS

such as brittle stars, sea pens, or 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. 

Oil and chemical spills are not considered to be a potential source of measurable impacts to 

nonchemosynthetic, deepwater benthic communities because of the water depths at which these 

communities are located. Oil spills at the surface would tend not to sink. The risk for weathering 

components from a surface slick reaching the benthos in any measurable concentrations would be very 

small. 

Deepwater coral habitats and other potential hard-bottom communities not associated with 

chemosynthetic communities appear to be relatively rare. One discovery of a dense deepwater coral 

habitats was recently made as a part of the MMS study, Investigations of Chemosynthetic Communities on 

the Lower Continental Slope of the Gulf of Mexico (Brook et al., in preparation) at a depth of 1,400 m 

(4,593 ft); however, this was an exception for the study. 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, but adherence to the guidance 

provided in NTL 2000-G-20 should prevent all but minor impacts to hard-bottom communities beyond 

454 m (1,500 ft). Under the current review procedures for chemosynthetic communities, carbonate 

outcrops (high reflectivity surface anomalies on 3D seismic survey data) are targeted as one possible 

indication that chemosynthetic seep communities are present. Any unique nonchemosynthetic 

communities that may be associated with carbonate outcrops or other topographical features would be 

avoided via this review, along with the chemosynthetic communities. 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 >400 m (1,312 ft) would automatically trigger the NTL 2000-G20 

evaluation described above. 

CPA Proposed Action Analysis 

For water depths >400 m (1,312 ft), 0-2 blowouts are estimated in the CPA. Resuspended sediments 

caused from a blowout will have minimal impacts on the full spectrum of soft-bottom community 

animals, including the possible mortality of a few megafauna organisms such as a crab or shrimp. 

The risk of various sizes of oil spills occurring in the CPA is presented in Tables 3-6 and 3-7. The 

probability of oil in any measurable concentration reaching depths of 400 m (1,312 ft) or greater from a 

surface spill is very small. 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 nonchemosynthetic communities. 

The 181 South Area is part of the proposed CPA sale area, but there is no evidence of any exposed 

hard substrate that could support significant nonchemosynthetic communities that would be exposed to 

any kind of accidental impacts. If new geophysical survey information did indicate the potential presence 

of hard bottom areas (that could support deepwater corals or other significant communities), the same 

biological review process and use of NTL 2000-G20 would apply, resulting in a greatly reduced 

probability of any impacts occurring. 

WPA Proposed Action Analysis 

For water depths >400 m (1,312 ft), 0-1 blowouts are estimated in the WPA. Resuspended sediments 

caused from a blowout will have minimal impacts on the full spectrum of soft-bottom community 

animals, including the possible mortality of a few megafauna organisms such as a crab or shrimp. 

The risk of various sizes of oil spills occurring in the WPA is presented in Tables 3-6 and 3-7. The 

probability of oil in any measurable concentration reaching depths of 400 m (1,312 ft) or greater from a 

surface spill is very small. 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 nonchemosynthetic communities. 

Summary and Conclusion 

Accidental events resulting from a CPA or WPA proposed action are expected to cause little damage 

to the ecological function or biological productivity of the widespread, typical, deep-sea benthic 
Environmental and Socioeconomic Consequences 4-81 

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. Even in 

situations where the substantial burial of typical benthic communities occurred, recolonization from 

populations from neighboring substrate would be expected over a relatively short period of time for all 

size ranges of organisms, in a matter of hours to days for bacteria and probably less than 1 year for most 

all macrofauna species. 

Deepwater coral habitats and other potential hard-bottom communities not associated with 

chemosynthetic communities will likely be avoided as a consequence of the application of NTL 

2000-G20 and the similar geophysical signatures (hard bottom), indicating the potential presence of 

chemosynthetic communities. 

Accidental events from a CPA or WPA proposed action are expected to cause little damage to the 

ecological function or biological productivity of the widespread, typical, deep-sea benthic communities. 

The MMS has reexamined the analysis for impacts to nonchemosynthetic communities presented in 

the Multisale EIS, based on the additional information presented above. No significant new information 

was found that would alter the overall conclusion that impacts on chemosynthetic communities from 

routine activities associated with a CPA or WPA proposed action would be minimal to none. As part of 

the proposed CPA sale area, the 181 South Area is not expected to have any sensitive exposed hard 

bottom that would be exposed to any kind of accidental impacts. 

4.1.5.4. Cumulative Impacts 

Background/Introduction 

Both chemosynthetic communities and nonchemosynthetic deepwater resources will be combined in 

this chapter. A detailed description of cumulative impacts upon deepwater benthic communities can be 

found in Chapter 4.5.4.2 of the Multisale EIS. The following is a summary of the information presented 

in the Multisale EIS, which incorporates new information found since publication of the Multisale EIS. 

Cumulative factors considered to impact the deepwater benthic communities of the Gulf of Mexico 

include both oil- and gas-related and non-oil- and 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 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 and WPA are currently minimal, and 

impacts to deepwater benthic communities are negligible. 

Other regional non-oil- and 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. 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 or significant, 

nonchemosynthetic communities such as coral communities. 

One potential significant large-scale source of impact could be potential efforts of carbon 

sequestration in the deep sea as a technique to reduce atmospheric carbon dioxide. This concept is still 

being considered but has major ramifications. One side of the issue, even beyond the problems of sealevel increase and climate change, includes the serious risk to shallow-water benthic organisms through 

pH increases, particularly those with calcium carbonate shells and corals (Shirayama and Thornton, 2005; 

Kleypas et al., 1999; Barry et al., 2005). However, the impacts of even very small excursions of pH and 

CO2 in the deep sea could also have serious, even global, deep-sea ecosystem impacts. Kita and Ohsumi 

(2004) suggest sequestration of anthropogenic CO2 could help reduce atmospheric CO2, but they also 

summarize the potentially substantial biological impact on marine organisms. It is obvious that 

substantial additional research is needed before any large-scale actions would take place. 

The greatest potential for cumulative adverse impacts to occur to the deepwater benthic communities, 

both chemosynthetic and nonchemosynthetic, would come from those OCS-related, bottom-disturbing 
4-82 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 

will occur on discoveries throughout the entire depth range of the CPA and WPA; these activities will 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 

will 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 required under NTL 

2000-G20. Activity levels for the cumulative scenario in the CPA and WPA are shown in Tables 4-6 and 

4-5 of the Multisale EIS, respectively. For the CPA deepwater offshore Subareas C200-400, C400-800 

C800-1600, C1600-2400, and C>2400, an estimated 1,445-2,003 exploration and delineation wells and 

12,602-14,920 development wells are projected to be drilled, and 114-174 production structures are 

projected to be installed through the 40-year analysis period. In the same water depths, 84-102 blowout 

accidents are projected (Table 4-6 of the Multisale EIS). For the WPA deepwater offshore Subareas 

W200-400, W400-800 W800-1600, W1600-240,0 and W>2400, an estimated 65-97 exploration and 

delineation wells and 4,139-5,290 development wells are projected to be drilled, and 65-97 production 

structures are projected to be installed through the 40-year analysis period. For these same water depths, 

29-37 blowout accidents are projected (Table 4-5 of the Multisale EIS). 

Routine discharges of drilling muds and cuttings have been documented to reach the seafloor in water 

depths >400 m (1,312 ft) and the impacts have been analyzed in the Multisale EIS, including the results 

from a recent study by CSA (2006), 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 chemosynthetic 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 MMS 

study (Brooks et al., in preparation). These new communities were targeted using the same procedures 

integral to the biological review process and the use of NTL 2000-G20 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 deeper communities to cumulative impacts. 

In cases where high-density communities are subjected to greatly dispersed cumulative discharges or 

resuspended 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 with recovery occurring 

within 2 years; however, 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. 

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. The 

distance of separation provided by the adherence of NTL 2000-G20 would protect both chemosynthetic 

and nonchemosynthetic communities from the direct effects of deepwater blowouts. Subsea structure 

removals are not expected in water depths >800 m (2,625 ft), in accordance with 30 CFR 250. 

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 not to sink. Oil discharges at depth or on the bottom would tend to rise in the 

water column and similarly not impact the benthos. 
Environmental and Socioeconomic Consequences 4-83 

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 NTL 

2000-G20 and the shallow hazards NTL 2007-G01 due to the avoidance of areas represented as hard 

bottom on surface anomaly maps derived from 3D seismic records. 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 (Bush Hill-type) communities; the widely distributed 

low-density communities would not be at risk. The guidance provided in NTL 2000-G20 require surveys 

and avoidance prior to drilling or pipeline installation and will greatly reduce the 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., in preparation). Confidence is increasing regarding the use 

of geophysical signatures for the prediction of likely presence of chemosynthetic communities with the 

dramatic success of this project. 

Activities unrelated to the OCS Program include fishing and trawling. Because of the water depths in 

these areas 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 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 anticipated. 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 cumulative impacts on nonchemosynthetic benthic communities are expected to cause little 

damage to the ecological function or biological productivity of the expected typical communities existing 

on sand/silt/clay bottoms of the deep Gulf of Mexico. Large motile animals would tend to move, and 

recolonization from populations from neighboring substrates would be expected in any areas impacted by 

burial. Potential cumulative impacts on deepwater coral or other high-density, hard-bottom communities, 

similar to chemosynthetic communities, are expected to cause little damage to ecological function or 

biological productivity. If major physical disturbance (such as anchor damage) or extensive burial by 

muds and cuttings were to occur to coral or other high-density, nonchemosynthetic hard-bottom 

communities, impacts could be severe. 

The incremental contribution of a CPA or WPA 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 will 

be limited but not completely eliminated by adherence to NTL 2000-G20. 
4-84 Central and Western Gulf of Mexico Multisale Supplemental EIS

The 181 South Area, part of the proposed CPA sale area, is not expected to have any chemosynthetic 

communities or sensitive exposed hard bottom that would be exposed to any kind of impacts from routine 

activities or accidental events associated with a proposed action. 

4.1.6. Marine Mammals 

The MMS has reexamined the analysis of the 29 species of marine mammals occurring in the Gulf of 

Mexico presented in the Multisale EIS, based on the additional information presented below and the 

addition of the 181 South Area to the proposed CPA sale area. No significant new information was found 

that would alter the impact conclusion for marine mammals presented in the Multisale EIS. With the 

exception of manatees, any of the marine species that occur in the Gulf of Mexico may be found in the 

181 South Area. However, the 181 South Area is not unique in regards to marine mammal distribution. 

Impacts from routine activities and accidental events occurring in the 181 South Area are similar to the 

rest of the sale area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Routine events related to a CPA or WPA proposed action, 

particularly when mitigated as required by MMS, are not expected to have long-term adverse effects on 

the size and productivity of any marine mammal species or population endemic to the northern Gulf of 

Mexico. Characteristics of impacts from accidental events depend on chronic or acute exposure, resulting 

in harassment, harm, or mortality to marine mammals, while exposure to dispersed hydrocarbons is likely 

to result in sublethal impacts. The effects of the incremental contribution of a CPA or WPA proposed 

action, including the 181 South Area, combined with non-OCS activities may be deleterious to cetaceans 

occurring in the Gulf of Mexico. Biological significance of any mortality would depend, in part, on the 

size and reproductive rates of the affected stocks, as well as the number, age, and size of animals affected. 

4.1.6.1. Description of the Affected Environment 

A detailed description of marine mammals can be found in Chapter 3.2.3 of the Multisale EIS. The 

following is a summary of the information presented in the Multisale EIS, which incorporates new 

information found since the publication of the Multisale EIS. With the exception of manatees, any of the 

marine species that occur in the Gulf of Mexico may be found in the 181 South Area. However, the 181 

South Area is not unique in regards to marine mammal distribution. 

Twenty-nine species of marine mammals occur in the Gulf of Mexico (Davis et al., 2000). The Gulf 

of Mexico’s marine mammals are represented by members of the taxonomic order Cetacea, which is 

divided into the suborders Mysticeti (i.e., baleen whales) and Odontoceti (i.e., toothed whales), as well as 

the order Sirenia, which includes the manatee and dugong. Within the Gulf of Mexico, there are 28 

species of cetaceans (7 mysticete and 21 odontocete species) and 1 sirenian species, the manatee 

(Jefferson et al., 1992) (Table 4-4). 

Threatened or Endangered Species 

Five baleen cetaceans (the northern right, blue, fin, sei, and humpback whales), one toothed cetacean 

(the sperm whale), and one sirenian (the West Indian manatee) occur in the Gulf of Mexico and are listed 

as endangered under the Endangered Species Act of 1973 (ESA). The sperm whale is common in oceanic 

waters of the northern Gulf of Mexico and appears to be a resident species, while the baleen whales are 

considered rare or extralimital in the Gulf of Mexico (Würsig et al., 2000). The life history, population 

dynamics, status, distribution, behavior, and habitat use of baleen and toothed whales can be found in 

Chapters 3.2.3.1.1 and 3.2.3.1.2 of the Multisale EIS. 

The West Indian manatee (Trichechus manatus) typically inhabits only coastal marine, brackish, and 

freshwater areas. The distribution, feeding habits, habitat use, and population estimates of manatees can 

be found in Chapter 3.2.3.1.3 of the Multisale EIS. 

Additional research was conducted to investigate recently available information since completion of 

the Multisale EIS. A recent report was found. This report presents the results of a study that collected the 
Environmental and Socioeconomic Consequences 4-85 

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 (Palka and Johnson, 2007). The study started a baseline 

of line transect, photo-identification, oceanographic, and genetic data for the Atlantic sperm whale. 

Compared with the Delta region 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). 

Recent Consultation 

As mandated by the ESA, MMS consulted with NMFS and FWS on possible and potential impacts 

from a CPA or WPA proposed action on endangered/threatened species and designated critical habitat 

under their jurisdiction. A biological assessment (BA) was prepared for each consultation. The action 

area analyzed in the BA’s included the 181 South Area addressed in this SEIS. 

The formal ESA consultation with NMFS was concluded with receipt of the Biological Opinion (BO) 

on July 3, 2007 (USDOC, NMFS, 2007d). The BO concludes that the proposed lease sales and associated 

activities in the Gulf of Mexico in the 2007-2012 OCS Leasing Program, which includes the 181 South 

Area, 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 BO, but not in the Multisale EIS. Based on NOAA’s 

surveys, opportunistic sightings, whaling catches, 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: an area off 

the Dry Tortugas and offshore of the Mississippi River delta (Maze-Foley and Mullin, 2006); however, 

distribution also appears influenced by occurrence and movement of cyclonic/anticyclonic currents in the 

Gulf of Mexico. 

The informal ESA consultation with FWS was concluded with a letter dated September 14, 2007. 

The FWS concurred with the MMS determination that proposed actions of the 2007-2012 OCS Leasing 

Program were not likely to adversely affect the threatened/endangered species or designated critical 

habitat under FWS jurisdiction. 

Nonendangered Species 

Two baleen cetaceans (Bryde’s and minke whales) and 20 toothed cetaceans (including sperm 

whales, 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. 

4.1.6.1.1. 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/Atchafalaya Rivers), 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 
4-86 Central and Western Gulf of Mexico Multisale Supplemental EIS

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. In either case, this input of 

nutrient-rich water leads to a localized deepwater environment with enhanced productivity and may 

explain the persistent presence of aggregations of sperm whales within 31 mi (50 km) of the Mississippi 

River Delta in the vicinity of the Mississippi Canyon. 

Tropical Weather 

Tropical storms and hurricanes are a normal occurrence in the Gulf of Mexico and along the coast. 

Generally, the impacts are localized and infrequent. However, in recent years the Gulf of Mexico has 

been extremely hard hit by several very powerful hurricanes. Few areas of the coast did not suffer some 

damage in 2004 and 2005. In 2004, Hurricane Ivan took a large toll on oil and gas structures and 

operations in the Gulf of Mexico and caused widespread damage to the Alabama-Florida Panhandle coast. 

In 2005, Hurricanes Katrina, Rita, and Wilma reached Category 5 strength in the Gulf of Mexico. These 

storms caused damage in all five of the Gulf Coast States and caused massive damage to structures and 

operations both offshore and on land. The actual impacts of these storms on the marine mammals in the 

Gulf of Mexico have not yet been determined and, for the most part, may remain very difficult to 

quantify. Examples of impacts that may have affected species include oil, gas, and chemical spills from 

damaged and destroyed structures and vessels (although no large oil spills were reported, many lesser 

spills are known to have occurred), increased trash and debris in both offshore and inshore habitats, and 

increased runoff and silting from wind and rain. These impacts are expected to be temporary. Generally, 

the offshore species and the offshore habitat are not expected to have been severely affected in the long 

term. However, the seasonal occurrence of impacts from hurricanes is impossible to predict. 

4.1.6.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on marine mammals is presented in Chapters 4.2.2.1.5 and 4.2.1.1.5 of the Multisale EIS, 

respectively. These potential effects may be direct or indirect. The major impact-producing factors 

affecting marine mammals as a result of routine OCS activities include the degradation of water quality 

from operational discharges; noise generated by helicopters, vessels, operating platforms, and drillships; 

vessel traffic; seismic surveys; explosive structure removals; and marine debris from service vessels and 

OCS structures. 

Some industry-generated effluents are routinely discharged into offshore marine waters. Marine 

mammals may have some interaction with these discharges. Contaminants in waste discharges and 

drilling muds might indirectly affect marine mammals through food-chain biomagnification. Although 

the scope and magnitude of such effects are not known, direct or indirect effects are not expected to be 

lethal. 

There is no conclusive evidence whether anthropogenic noise has or has not caused long-term 

displacements of, or reductions in, marine mammal populations. Noise associated with OCS activity, 

including aircraft, drilling noise, and vessels, may affect marine mammals by eliciting a startle response 

or masking other sounds. However, many of the industry-related sounds are believed to be out of, or on 

the limits of, marine mammal hearing, and the sounds are also generally temporary. The continued 

presence of sperm whales in close proximity to some of the deepwater structures in the Gulf of Mexico 

tends to rule out concerns of permanent displacement from disturbance. 

The Federal Aviation Administration (FAA) Advisory Circular 91-36C encourages pilots to maintain 

higher than minimum altitudes (noted below) over noise-sensitive areas. Corporate helicopter policy 

states that helicopters should maintain a minimum altitude of 700 ft (213 ft) while in transit offshore and 

500 ft (152 ft) while working between platforms. In addition, guidelines and regulations issued by NMFS 

under the authority of the Marine Mammal Protection Act do include provisions specifying helicopter 

pilots to maintain an altitude of 1,000 ft (305 ft) within 100 yd (91 m) of marine mammals. 
Environmental and Socioeconomic Consequences 4-87 

The rapid increase in exploration and development of petroleum resources in deep oceanic waters of 

the northern Gulf of Mexico has increased the risk of OCS vessel collisions with sperm whales and other 

deep-diving cetaceans (e.g., Kogia and beaked whales). Deep-diving whales may be more vulnerable to 

vessel strikes because of the extended surface period required to recover from extended deep dives. The 

MMS has issued regulations and guidelines to minimize the chance of vessel strike to marine mammals 

with proposed Protected Species Lease Stipulation and NTL 2007-G04, “Vessel Strike Avoidance and 

Injured/Dead Protected Species Reporting.” 

Wells and platforms could produce sounds at intensities and frequencies that could be heard by 

marine mammals. Potential effects on Gulf of Mexico marine mammals include disturbance (i.e., subtle 

changes in behavior, interruption of previous activities, or short- or long-term displacement), masking of 

natural sounds (e.g., surf and predators) and calls from nonspecifics, stress (physiological), and hearing 

impairment (permanent or temporary) by explosions and strong nonexplosive sounds. 

Seismic operations have the potential to harm marine mammals in close proximity to firing airgun 

arrays. The proposed Protected Species Lease Stipulation and the several mitigations, including onboard 

observers and airgun shut-downs for whales in the exclusion zone, included in NTL 2007-G02 

(“Implementation of Seismic Survey Mitigation Measures and Protected Species Observer Program”) 

minimize the potential of harm from seismic operations to marine mammals. 

Structure removals would cause only minor behavioral changes and noninjurious physiological 

effects on marine mammals as a result of the implementation of MMS NTL guidelines and regulations, 

and the NMFS Observer Program for explosive removals. To date, there are no documented “takes” of 

marine mammals resulting from explosive removals of offshore structures. 

Many types of materials, including plastics, are used during drilling and production operations. 

Industry directives for reducing marine debris and MMS’s guidelines through its NTL for maintaining 

awareness of the problem and eliminating accidental loss continue to minimize industry-related trash in 

the marine environment. 

CPA Proposed Action Analysis 

Potential effects on marine mammal species may occur from routine activities associated with a CPA 

proposed action and may be direct or indirect. The major impact-producing factors affecting marine 

mammals as a result of routine OCS activities include the degradation of water quality from operational 

discharges; noise generated by helicopters, vessels, operating platforms, and drillships; vessel traffic; 

seismic surveys; explosive structure removals; and marine debris from service vessels and OCS 

structures. These impacts are similar in the 181 South Area as they are to the rest of the sale area. 

Some industry-generated effluents are routinely discharged into offshore marine waters. Indirect 

effects to marine mammals through prey exposure to discharges are expected to be sublethal. Because 

OCS discharges are diluted and dispersed in the offshore environment, direct impacts to marine mammals 

are expected to be negligible. 

Helicopter operations (take-offs and landings) projected for a CPA proposed action are 1,004,000-

2,241,000 operations over the life of a proposed action. It is unlikely that marine mammals would be 

affected by routine OCS helicopter traffic operating at the anticipated altitudes. It is expected that about 

10 percent of helicopter operations would occur at altitudes below the specified minimums listed above as 

a result of inclement weather. Routine overflights may elicit a startle response from and interrupt marine 

mammals nearby (depending on the activity of the animals) (Richardson et al., 1995). Occasional 

overflights probably have no long-term consequences on marine mammals; however, frequent overflights 

could have long-term consequences if they repeatedly disrupt vital functions, such as feeding and 

breeding. Temporary disturbance to marine mammals may occur as helicopters approach or depart OCS 

facilities if animals are near the facility. Such disturbance is believed negligible. 

Service-vessel round trips projected for a CPA proposed action 119,000-241,000 trips over the life of 

a proposed action. Noise from service-vessel traffic may elicit a startle and/or avoidance reaction from 

marine mammals 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. 

Long-term displacement of animals from an area is also a consideration. Increased ship traffic could 

increase the probability of collisions between ships and marine mammals, resulting in injury or death to 

some animals. 
4-88 Central and Western Gulf of Mexico Multisale Supplemental EIS

Noise from drilling activities would be relatively constant during the temporary duration of drilling. 

Toothed whales echolocate and communicate at higher frequencies than the dominant sounds generated 

by drilling platforms (Gales, 1982). Bottlenose dolphins, one of the few species in which low-frequency 

sound detection ability has been studied, have poor sensitivity at the level where most OCS-industry noise 

energy is concentrated. Baleen whales are apparently more dependent on low-frequency sounds than 

other marine mammals and may be species of concern regarding OCS-industry noise. However, all 

baleen whale species except the Bryde’s whale are considered extralimital or accidental in the Gulf of 

Mexico. Bryde’s whales are considered rare in the Gulf of Mexico, and observations of this species have 

been almost exclusively in the Eastern Gulf of Mexico (Davis et al., 2000). Thus, Bryde’s whales and 

other baleen whale species are not likely to be subjected to OCS drilling and production noise. 

An additional 2-3 seismic surveys are anticipated in the 181 South Area. Seismic operations have the 

potential to harm marine mammals in close proximity to firing airgun arrays; however, the proposed 

Protected Species Lease Stipulation and the several mitigations would minimize the potential of harm 

from seismic operations to marine mammals. 

Potential impacts to marine mammals from the detonation of explosives include lethal and injurious 

incidental take, as well as physical or acoustic harassment. Injury to the lungs and intestines and/or the 

auditory system could occur. Harassment of marine mammals as a result of a noninjurious physiological 

response to the explosion-generated shock wave as well as to the acoustic signature of the detonation is 

also possible. No explosive removals are projected to occur in >800 m (2,625 ft), which includes the 181 

South Area. 

Some material is accidentally lost overboard where marine mammals could consume it or become 

entangled in it. The result of ingesting some materials lost overboard could cause disease or death. 

Entanglement is a concern as some packaging materials may be of a size and/or shape that could be 

impossible for marine mammals to jettison. Many of the plastics used by industry could withstand years 

of saltwater exposure without disintegrating or dissolving. An entangled marine mammal may suffer 

from acute impaired mobility that compromises its health quickly, or it may decline slowly from 

diminishing feeding and reproductive capability. The increased energy required to overcome the 

handicap of entanglement may require more food than the entangled whale can capture. 

WPA Proposed Action Analysis 

Potential effects on marine mammal species may occur from routine activities associated with a WPA 

proposed action and may be direct or indirect. The major impact-producing factors affecting marine 

mammals as a result of routine OCS activities include the degradation of water quality from operational 

discharges; noise generated by helicopters, vessels, operating platforms, and drillships; vessel traffic; 

seismic surveys; explosive structure removals; and marine debris from service vessels and OCS 

structures. 

Some industry-generated effluents are routinely discharged into offshore marine waters. Indirect 

effects to marine mammals through prey exposure to discharges are expected to be sublethal. Because 

OCS discharges are diluted and dispersed in the offshore environment, direct impacts to marine mammals 

are expected to be negligible. 

Helicopter operations (take-off and landings) projected for a WPA proposed action are 400,000-

900,000 operations over the life of a proposed action. It is unlikely that marine mammals would be 

affected by routine OCS helicopter traffic operating at these altitudes. It is expected that about 10 percent 

of helicopter operations would occur at altitudes below the specified minimums listed above as a result of 

inclement weather. Routine overflights may elicit a startle response from and interrupt marine mammals 

nearby (depending on the activity of the animals) (Richardson et al., 1995). Occasional overflights 

probably have no long-term consequences on marine mammals; however, frequent overflights could have 

long-term consequences if they repeatedly disrupt vital functions such as feeding and breeding. 

Temporary disturbance to marine mammals may occur as helicopters approach or depart OCS facilities if 

animals are near the facility. Such disturbance is believed negligible. 

Service-vessel round trips projected for a WPA proposed action are 94,000-155,000 trips over the life 

of a proposed action. Noise from service-vessel traffic may elicit a startle and/or avoidance reaction from 

marine mammals 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. 
Environmental and Socioeconomic Consequences 4-89 

Long-term displacement of animals from an area is also a consideration. Increased ship traffic could 

increase the probability of collisions between ships and marine mammals, resulting in injury or death to 

some animals. 

Noise from drilling activities would be relatively constant during the temporary duration of drilling. 

Toothed whales echolocate and communicate at higher frequencies than the dominant sounds generated 

by drilling platforms (Gales, 1982). Bottlenose dolphins, one of the few species in which low-frequency 

sound detection ability has been studied, have poor sensitivity at the level where most OCS-industry noise 

energy is concentrated. Baleen whales are apparently more dependent on low-frequency sounds than 

other marine mammals and may be species of concern regarding OCS-industry noise. However, all 

baleen whale species, except for the Bryde’s whale, are considered extralimital or accidental in the Gulf 

of Mexico. Bryde’s whales are considered rare in the Gulf of Mexico and observations of this species 

have been almost exclusively in the Eastern Gulf of Mexico (Davis et al., 2000). Thus, Bryde’s whales 

and other baleen whale species are not likely to be subjected to OCS drilling and production noise. 

Seismic operations have the potential to harm marine mammals in close proximity to firing airgun 

arrays; however, the proposed Protected Species Lease Stipulation and the several mitigations would 

minimize the potential of harm from seismic operations to marine mammals. 

Potential impacts to marine mammals from the detonation of explosives include lethal and injurious 

incidental take, as well as physical or acoustic harassment. Injury to the lungs and intestines and/or 

auditory system could occur. Harassment of marine mammals as a result of a noninjurious physiological 

response to the explosion-generated shock wave as well as to the acoustic signature of the detonation is 

also possible. 

Some material is accidentally lost overboard where marine mammals could consume it or become 

entangled in it. The result of ingesting some materials lost overboard could cause disease or death. 

Entanglement is a concern, as some packaging materials may be of a size and/or shape that could be 

impossible for marine mammals to jettison. Many of the plastics used by industry could withstand years 

of saltwater exposure without disintegrating or dissolving. An entangled marine mammal may suffer 

from acute impaired mobility that compromises its health quickly, or it may decline slowly from 

diminishing feeding and reproductive capability. The increased energy required to overcome the 

handicap of entanglement may require more food than the entangled whale can capture. 

Summary and Conclusion 

Potential effects on marine mammal species may occur from routine activities associated with a CPA 

or WPA proposed action may be direct or indirect. The major impact-producing factors affecting marine 

mammals as a result of routine OCS activities include the degradation of water quality from operational 

discharges; noise generated by helicopters, vessels, operating platforms, and drillships; vessel traffic; 

explosive structure removals; seismic surveys; and marine debris from service vessels and OCS 

structures. These impacts are similar in the 181 South Area as they are to the rest of the sale area. 

Contaminants in waste discharges and drilling muds might indirectly affect marine mammals through 

food-chain biomagnification. Although the scope and magnitude of such effects are not known, direct or 

indirect effects are not expected to be lethal. 

There is no conclusive evidence whether anthropogenic noise has or has not caused long-term 

displacements of, or reductions in, marine mammal populations. Noise associated with a CPA or WPA 

proposed action, including drilling noise, aircraft, and vessels, may affect marine mammals by eliciting a 

startle response or masking other sounds. However, many of the industry-related sounds are believed to 

be out of, or on the limits of, marine mammal hearing, and the sounds are also generally temporary. The 

continued presence of sperm whales in close proximity to some of the deepwater structures in the Gulf of 

Mexico tends to rule out concerns of permanent displacement from disturbance. 

Small numbers of marine mammals could be killed or injured by a chance collision with a service 

vessel; however, current MMS requirements and guidelines for vessel operation in the vicinity of 

protected species should minimize this risk (i.e., the proposed Protected Species Lease Stipulation and 

NTL 2007-G04). 

Seismic operations have the potential to harm marine mammals in close proximity to firing airgun 

arrays. The proposed Protected Species Lease Stipulation and the several mitigations, including onboard 

observers and airgun shut-downs for whales in the exclusion zone, included in NTL 2007-G02 
4-90 Central and Western Gulf of Mexico Multisale Supplemental EIS

(“Implementation of Seismic Survey Mitigation Measures and Protected Species Observer Program”) 

minimize the potential of harm from seismic operations to marine mammals. 

Marine mammal death or injury is not expected from explosive structure-removal operations. 

Existing mitigations and those recently developed for structures placed in oceanic waters should continue 

to minimize adverse effects to marine mammals from these activities. 

Marine mammal ingestion of industry-generated debris is a concern. Sperm whales may be 

particularly at risk because of their suspected feeding behavior involving cruising along the bottom with 

their mouth open. Entanglement in debris could have serious consequences. A sperm whale could suffer 

diminished feeding and reproductive success, and potential injury, infection, and death from entanglement 

in discarded packing materials or debris. Industry has made good progress in debris management on 

vessels and offshore structures in the last several years. The debris awareness training, instruction, and 

placards required by the proposed Protected Species Lease Stipulation and NTL 2007-G03 should greatly 

minimize the amount of debris that is accidentally lost overboard by offshore personnel. 

Routine activities related to a CPA or WPA proposed action, particularly when mitigated as required 

by MMS, are not expected to have long-term adverse effects on the size and productivity of any marine 

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

4.1.6.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of the possible impacts from accidental events associated with a CPA or WPA 

proposed action on marine mammals is presented in Chapter 4.4.5 of the Multisale EIS. Accidental, 

unexpected industrial events associated with a CPA or WPA proposed action could impact marine 

mammals. Such impacts would primarily be the result of blowouts, oil spills, and/or effects associated 

with the response to an oil spill. 

During a blowout, the pressure waves and noise generated by the eruption of gases and fluids might 

be significant enough to harass or injure marine mammals, depending on the proximity of the animal to 

the blowout. The effects of explosions and noise on marine mammals are discussed at length in Chapters 

4.2.1.5 and 4.2.2.1.5 of the Multisale EIS. 

Marine mammals occur in the inshore, coastal and oceanic waters of the Gulf of Mexico and could be 

impacted by accidental spills resulting from operations associated with the proposed actions in the CPA 

and WPA. The potential causes, sizes, and probabilities of oil spills that could occur during drilling, 

production, and transportation operations associated with a proposed action are presented in Chapter 4.3.1 

of the Multisale EIS. Chapter 4.3.1.8 of the Multisale EIS summarizes MMS’s information on the risk to 

marine mammals analyzed in this SEIS from oil spills and oil slicks that could occur as a result of a 

proposed action. 

The greatest diversity and abundance of cetaceans inhabiting the Gulf of Mexico is found in its 

oceanic and OCS waters. Individual cetaceans are not necessarily randomly distributed in the offshore 

environment but are, instead, prone to forming groups of varying sizes. In some cases, several species 

may be found aggregating in the same area. Large spills, particularly those continuing to flow fresh 

hydrocarbons into oceanic and/or outer shelf waters for extended periods (i.e., days, weeks, or months), 

pose an increased likelihood of impacting cetacean populations inhabiting these waters. 

It is impossible to know precisely which cetacean species, population, or individuals will be 

impacted, to what magnitude, or in what numbers, since each species has unique distribution patterns in 

the Gulf of Mexico and because of difficulties attributed to predicting when and where oil spills will 

occur. Chapter 4.3.1.6.4 of the Multisale EIS details the persistence, spreading, and weathering process 

for offshore spills. 

Blowouts, oil spills, and spill-response activities have the potential to adversely affect marine 

mammals, causing physical injury and irritation, fouling of baleen plates, respiratory stress from 

inhalation of toxic fumes, food reduction or contamination, direct ingestion of oil and/or tar, and 

temporary displacement from preferred habitats or migration routes. If these accidental events occur 

within marine mammal habitat, impacts will likely follow as animals are exposed to pollutants. 
Environmental and Socioeconomic Consequences 4-91 

CPA Proposed Action Analysis 

Accidental, unexpected industrial events associated with a CPA proposed action could impact marine 

mammals. Such impacts would primarily be the result of blowouts, oil spills, and/or effects associated 

with the response to an oil spill. These impacts are similar in the 181 South Area as they are to the rest of 

the sale area. However, as explained in Chapter 3.2.1, the incremental increase in oil production from 

the addition of the 181 South Area is not expected to result in an overall increase in the numbers of oil 

spills ≥1,000 bbl likely to occur as a result of a CPA proposed action. 

During a blowout, the pressure waves and noise generated by the eruption of gases and fluids might 

be significant enough to harass or injure marine mammals, depending on the proximity of the animal to 

the blowout. There are 2-3 blowouts projected from a proposed lease sale in the CPA. 

Based on abundance estimates and a hypothetical spill surface area, spills occurring in these waters 

could impact more species and more individuals than coastal spills potentially impacting coastal marine 

mammals. The endangered sperm whales use oceanic waters as their principle habitat, and the current 

abundance estimate for the northern Gulf of Mexico is 1,349 animals (Waring et al., 2006). 

The probability of a single marine mammal encountering an oil slick from a single, small spill is 

extremely low. Also, considering marine mammal populations instead of individual animals increases the 

probability of impact in that there are numerous animals and an encounter with an oil slick by any one of 

them could be considered an impact to the population. However, such an impact is not expected to be 

significant to the population. 

Spills of any size degrade water quality, and residuals become available for bioaccumulation within 

the food chain. Slicks may spread at the sea surface or may migrate underwater from the seafloor through 

the water column and never broach the sea surface. Regardless, a slick is an expanding but aggregated 

mass of oil that, with time, will disperse into smaller units as it evaporates (if at the sea surface) and 

weathers. Although marine mammals may (or may not) avoid oil spills or slicks, it is highly unlikely that 

they are capable of avoiding spill residuals in their environment. Consequently, the probability that a 

marine mammal is exposed to hydrocarbons resulting from a spill extends well after the oil spill has 

dispersed from its initial aggregated mass. 

Oil spills have the potential to cause chronic (long-term lethal or sublethal oil-related injuries) and 

acute (spill-related deaths occurring during a spill) effects on mammals. The effects of cleanup activities 

are unknown, but increased human presence (e.g., vessels) could add to changes in marine mammal 

behavior and/or distribution, thereby additionally stressing animals, and perhaps making them more 

vulnerable to various physiologic and toxic effects. 

WPA Proposed Action Analysis 

Accidental, unexpected industrial events associated with a WPA proposed action could impact marine 

mammals. Such impacts would primarily be the result of blowouts, oil spills, and/or effects associated 

with the response to an oil spill. 

During a blowout, the pressure waves and noise generated by the eruption of gases and fluids might 

be significant enough to harass or injure marine mammals, depending on the proximity of the animal to 

the blowout. There are 1-2 blowouts projected to occur from a proposed lease sale in the WPA. 

Based on abundance estimates and a hypothetical spill surface area, spills occurring in these waters 

could impact more species and more individuals than coastal spills potentially impacting coastal marine 

mammals. The endangered sperm whales use oceanic waters as their principle habitat, and the current 

abundance estimate for the northern Gulf of Mexico is 1,349 animals (Waring et al., 2006). 

The probability of a single marine mammal encountering an oil slick from a single, small spill is 

extremely low. Also, considering marine mammal populations instead of individual animals increases the 

probability of impact in that there are numerous animals and an encounter with an oil slick by any one of 

them could be considered an impact to the population. However, such impact is not expected to be 

significant to the population. 

Spills of any size degrade water quality, and residuals become available for bioaccumulation within 

the food chain. Slicks may spread at the sea surface or may migrate underwater from the seafloor through 

the water column and never broach the sea surface. Regardless, a slick is an expanding but aggregated 

mass of oil that, with time, will disperse into smaller units as it evaporates (if at the sea surface) and 

weathers. Although marine mammals may (or may not) avoid oil spills or slicks, it is highly unlikely that 
4-92 Central and Western Gulf of Mexico Multisale Supplemental EIS

they are capable of avoiding spill residuals in their environment. Consequently, the probability that a 

marine mammal is exposed to hydrocarbons resulting from a spill extends well after the oil spill has 

dispersed from its initial aggregated mass. 

Oil spills have the potential to cause chronic (long-term lethal or sublethal oil-related injuries) and 

acute (spill-related deaths occurring during a spill) effects on mammals. The effects of cleanup activities 

are unknown, but increased human presence (e.g., vessels) could add to changes in marine mammal 

behavior and/or distribution, thereby additionally stressing animals, and perhaps making them more 

vulnerable to various physiologic and toxic effects. 

Recent Consultation 

The NMFS believes that a small number of listed species will experience adverse effects as the result 

of exposure to a large oil spill or ingestion of accidentally spilled oil over the lifetime of the action. 

However, NMFS is not including an incidental take statement for the incidental take of listed species due 

to oil exposure. Incidental take, as defined at 50 CFR 402.02, refers only to takings that result from an 

otherwise lawful activity. The Clean Water Act (33 U.S.C. 1251 et seq.), as amended by the Oil Pollution 

Act of 1990 (33 U.S.C. 2701 et seq.), prohibits discharges of harmful quantities of oil, as defined at 40 

CFR 110.3, into waters of the United States. Therefore, even though the BO considered the effects on 

listed species by oil spills that may result from a WPA 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. 

Summary and Conclusion 

Accidental, unexpected industrial events associated with a CPA or WPA proposed action could 

impact marine mammals. Such impacts would primarily be the result of blowouts, oil spills, and/or 

effects associated with the response to an oil spill. These impacts are similar in the 181 South Area as 

they are to the rest of the sale area. Accidental blowouts, oil spills, and spill-response activities resulting 

from a CPA or WPA proposed action have the potential to impact marine mammals in the Gulf of 

Mexico. Characteristics of impacts (i.e., acute vs. chronic impacts) depend on the magnitude, frequency, 

location, and date of accidents, characteristics of spilled oil, spill-response capabilities and timing, and 

various meteorological and hydrological factors. Chronic or acute exposure from accidental events may 

result in harassment, harm, or mortality to marine mammals occurring in the northern Gulf of Mexico. 

Exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick is likely to result in 

sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability 

to disease) to marine mammals. 

4.1.6.4. Cumulative Impacts 

Background/Introduction 

A detailed description of possible cumulative impacts associated with a CPA or WPA proposed 

action on marine mammals is presented in Chapter 4.5.5 of the Multisale EIS. The cumulative analysis 

considers past, ongoing, and foreseeable future human and natural activities that may occur and adversely 

affect marine mammals in the same general area that may be affected by a proposed action. These 

activities include effects of the OCS Program (proposed actions, and prior and future OCS sales), State oil 

and gas activity, commercial shipping, commercial fishing, recreational fishing and boating activity, 

military operations, scientific research, and natural phenomena. Specific types of impact-producing 

factors considered in this cumulative analysis include noise from numerous sources, pollution, ingestion 

and entanglement in marine debris, vessel strikes, habitat degradation, and natural catastrophes. 

The major impact-producing factors relative to the CPA and WPA proposed actions are described in 

Chapters 4.2.2.1.5 and 4.2.1.1.5 of the Multisale EIS, respectively. Sections providing supportive 

material for the marine mammals analysis include Chapters 3.2.3 (description of marine mammals), 

4.1.1.2 (exploration), 4.1.1.3 (development and production), 4.1.1.7 and 4.1.2.1.11 (offshore and coastal 

noise), 4.1.2.1 (coastal infrastructure), and 4.3.1 and 4.4.5 (spills) of the Multisale EIS. 
Environmental and Socioeconomic Consequences 4-93 

Noise in the ocean has become a worldwide topic of concern, particularly in the last decade. The 

Gulf of Mexico is a very noisy place, and noise in the Gulf of Mexico comes from a broad range of 

sources. Virtually all of the marine mammal species in the Gulf of Mexico have been exposed to OCSindustrial noise due to the rapid advance into Gulf of Mexico deep oceanic waters by the oil and gas 

industry in recent years; whereas, 20 years ago, the confinement of industry to shallower coastal and 

continental shelf waters generally only exposed two species of marine mammals (the bottlenose dolphin 

and the Atlantic spotted dolphin) to industry activities and the related sounds. As noted in Chapter 4.1.1.7 

of the Multisale EIS, it is believed that most of the industry-related noise is at lower frequencies than is 

detectable or in the sensitivity range of most of the Gulf of Mexico marine mammal species. However, 

most of the information on marine mammal hearing is inferred, and there are reports of species reacting to 

sounds that were not expected to be audible. 

Industry noise sources include seismic operations, fixed platforms and drilling rigs, drilling ships, 

low-flying aircraft, vessel traffic, and explosive operations, particularly for structure removal. Chapter 

4.1.1.7 of the Multisale EIS discusses and shows the expected sources of many of these impacts for the 

OCS Program, as well as the expected sources from past, present, and future OCS-industry operations. 

Marine mammal avoidance guidelines listed in the Vessel Strike NTL 2007-G04 (“Vessel Strike 

Avoidance and Injured/Dead Protected Species Reporting”) should minimize the chance of marine 

mammals being subject to the increased noise level of a service vessel in very close proximity. Aircraft 

overflights are another source of noise and can cause startle reactions in marine mammals, including rapid 

diving, change in travel direction, and dispersal of marine mammal groups. Flight level minimum 

guidelines from NOAA and corporate helicopter policy should help mitigate the industry-related flight 

noise, though lower altitudes nearshore and as the helicopter lands and departs from rigs could impact 

marine mammals in close proximity to the structures or shore bases. Occasional overflights are not 

expected to have long-term impacts on marine mammals. 

The OCS-industry drilling impacts were discussed in Chapter 4.1.1 of the Multisale EIS. Although 

much of the focus is on industry operations in deep water, there is still interest and activity in more 

shallow and even coastal waters for oil and gas production. Explosive structure removals put 

considerable sound into the ocean, and these can occur in Federal or State waters. The COE also engages 

in some explosive and pile-driving operations that create loud but temporary noise. Such COE activities 

are consulted with NMFS and mitigations are included, often similar to the mitigations employed by 

MMS in consultation with NMFS. In order to minimize the likelihood of injury to marine mammals from 

explosive structure removals, MMS has issued guidelines (NTL 2004-G06) to offshore operators. These 

guidelines will be fortified by programmatic rulemaking under the Marine Mammal Protection Act 

(MMPA). Observations to minimize the possibility of a marine mammal being near an explosive removal 

mitigate these loud but very brief noises. 

Seismic exploration is the source of the loudest, and perhaps most controversial, OCS-industry 

activity. Seismic exploration is an integral part of oil and gas discovery, development, and production in 

the Gulf of Mexico. With technical advances that now allow the extraction of petroleum from the ultradeep areas of the Gulf of Mexico, seismic surveys are routinely conducted in virtually all water depths of 

the western Gulf of Mexico. Noise and acoustic disturbance have been topics of great debate in the last 

several years, and there is general agreement that the use of sonar, particularly by the military, has in 

some cases been associated with very severe impacts to certain species of marine mammals in recent 

years. Current research by MMS and partners did not detect avoidance of seismic vessels or airguns by 

sperm whales. Although that finding (or lack of finding) could be interpreted several ways, it is likely 

that the whales, which appear to generally remain in the northern Gulf of Mexico year-round, are 

habituated to seismic operations. Over the long term, stress to a population could cause very significant 

adverse effects including disease, reproductive failure, and population decline. 

The pollution of marine waters is another potentially adverse impact to marine mammals in the Gulf 

of Mexico. Effluents are routinely discharged into offshore waters and are regulated by USEPA NPDES 

permits. Marine mammals may periodically be exposed to these discharges. Direct effects to marine 

mammals are expected to be sublethal. Indirect effects via food sources are not expected because of 

dilution and dispersion of offshore operational discharges. Another OCS-industry form of pollution is oil 

spills. Because of dilution and weathering, such contact is expected to be sublethal. Indirect effects from 

the exposure of prey species to oil are also expected to be sublethal. 
4-94 Central and Western Gulf of Mexico Multisale Supplemental EIS

Pollution in the ocean comes from many point and nonpoint sources, and the Gulf of Mexico is 

certainly no exception. The drainage of the Mississippi River results in massive amounts of chemicals 

and other pollutants being constantly poured into the Gulf of Mexico. Since most of the marine mammals 

in the Gulf of Mexico are oceanic deepwater dwellers, the impacts of coastal and run-off pollution are 

greatly minimized as a result of dilution and dispersal. Primarily, the bottlenose dolphin and the manatee 

are most at risk for nearshore pollution. Given the many sources of unchecked pollution in the Gulf of 

Mexico, the amount of additional contaminants contributed by the oil and gas industry is negligible. 

Marine debris has an impact in the ocean. Plastics in particular, and from many different sources, 

pose a threat to the environment and a serious threat to marine mammals. Ingestion of plastic can cause a 

digestive gut blockage and ultimately death for a marine mammal. A wide variety of debris is commonly 

observed in the Gulf of Mexico and it comes from both terrestrial and marine sources. Since that time, 

industry has implemented waste management programs and greatly improved waste handling. The debris 

awareness training required by the proposed Protected Species Lease Stipulation and recommended by 

NTL 2007-G03 targets the accidental loss of material from vessels and structures. With these practices in 

place and compliance with applicable regulations and guidelines, the amount of marine debris contributed 

by a CPA or WPA proposed action would be minimal. 

Vessel strikes are a serious threat to marine mammals in the Gulf of Mexico. A collision between a 

marine mammal and a ship will result in injury and likely death. The increased vessel traffic may alter 

behavior of marine mammals by avoidance, displacement, or attraction to the vessel. However, those 

effects are expected to be short term. The Vessel Strike NTL 2007-G04 (“Vessel Strike Avoidance and 

Injured/Dead Protected Species Reporting”) provides guidelines to avoid a vessel/mammal collision and 

to minimize harassment of mammals by vessels approaching too closely. It also provides for the 

reporting of injured or dead protected species. Although OCS vessel traffic would be a major component 

of the cumulative vessel impacts, professional piloting and regulatory guidelines would minimize the 

impact of the OCS segment of vessel traffic. 

Other activities may have adverse effects on marine mammals. Occasionally, numbers of marine 

mammals strand, either alive or already dead. Die-offs happen infrequently but can seriously deplete 

small, discreet stocks. The causes of die-offs are not always well known and vary by event. Some appear 

to be triggered by natural events (i.e., unusually cold weather) but others are suspected to at least be 

indirectly caused by pollution of various contaminates. Exposure to certain compounds may weaken the 

natural immunity of marine mammals and make them susceptible to viruses and disease that would 

normally not affect them. 

The Gulf of Mexico has very little fishery interaction with marine mammals, compared with other 

areas. However, marine mammals can be injured or killed by commercial fishing gear. Mammals can 

either get hung on longline hooks or can be scooped into a net by a shrimp boat or groundfish vessel. 

Gillnets, which have now been banned in many places around the Gulf of Mexico, have been reported to 

take marine mammals. 

Lastly, tropical storms and hurricanes are normal occurrences in the Gulf of Mexico and along the 

Gulf Coast. Generally, the impacts have been localized and infrequent. However, in the last 2 years the 

Gulf of Mexico has been extremely hard hit by very powerful hurricanes. Few areas of the coast have not 

suffered some damage in 2004 and 2005, and activities in the Gulf of Mexico have also been severely 

impacted. Hurricanes have caused damage to all five of the Gulf Coast States and damage to structures 

and operations both offshore and onshore. The actual impacts of these storms on the animals in the Gulf 

of Mexico, and the listed species and critical habitat in particular, have not yet been determined and, for 

the most part, may remain very difficult to quantify. Examples of other impacts that may have affected 

species include oil, gas, and chemical spills from damaged and destroyed structures and vessels (although 

no large oil spills were reported, several lesser spills are known to have occurred), increased trash and 

debris in both offshore and inshore habitats, and increased runoff and silting from wind and rain. Not 

only are the impacts themselves difficult to assess, but the seasonal occurrence of impacts from hurricanes 

is also impossible to predict. 

Recent Consultation 

The proposed lease sales will not appreciably reduce the likelihood of the survival and recovery of 

sperm whales. The NMFS concluded that the anticipated reduction in numbers by take of sperm whales 
Environmental and Socioeconomic Consequences 4-95 

by oil spills associated with a proposed action, when evaluated in the context of the species’ status, the 

environmental baseline, and the cumulative effects, will not jeopardize the continued existence of sperm 

whales. 

Summary and Conclusion 

Activities considered under the cumulative scenario could affect protected cetaceans and sirenians. 

These marine mammals could be impacted by the degradation of water quality resulting from operational 

discharges; noise generated by platforms, drillships, helicopters and vessels; seismic surveys; explosive 

structure removals; oil spills; oil-spill-response activities; loss of debris from service vessels and OCS 

structures; vessel traffic; commercial fishing; capture and removal; pathogens; and natural catastrophes. 

The cumulative impact on marine mammals is expected to result in a number of chronic and sporadic 

sublethal effects (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. Few deaths are expected from oil spills, chance 

collisions with OCS service vessels, ingestion of plastic material, commercial fishing, and pathogens. Oil 

spills of any size are estimated to be recurring events that would periodically contact marine mammals. 

Deaths as a result of structure removals are not expected to occur due to mitigation measures (e.g., 

NOAA’s Fisheries Observer Program). Disturbance (e.g., noise from vessel traffic and drilling 

operations, etc.) and/or exposure to sublethal levels of toxins and anthropogenic contaminants may stress 

animals, weaken their immune systems, and make them more vulnerable to parasites and diseases that 

normally would not be fatal. The net result of any disturbance would be dependent 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). 

Collisions between cetaceans and ships, although expected to be rare events, could cause serious injury or 

mortality. Natural phenomenon, such as tropical storms and hurricanes, are impossible to predict, but 

they will occur in the Gulf of Mexico. Generally, the offshore species and the offshore habitat are not 

expected to have been severely affected in the long term. However, species that occupy more nearshore 

habitats may have suffered more long-term impacts. 

Effects of the incremental contribution of a CPA or WPA proposed action, including the 181 South 

Area, combined with non-OCS activities may be deleterious to cetaceans occurring in the Gulf of Mexico. 

Biological significance of any mortality would depend, in part, on the size and reproductive rates of the 

affected stocks, as well as the number, age, and size of animals affected. 

4.1.7. Sea Turtles 

The MMS has reexamined the analysis for the five sea turtles species that inhabit the Gulf of Mexico 

presented in the Multisale EIS, based on the additional information presented below and the addition of 

the 181 South Area to the proposed CPA sale area. While information from the 5-year status reviews for 

federally listed sea turtles in the Gulf of Mexico was incorporated, there was no significant new 

information that would alter the impact conclusion for sea turtles presented in the Multisale EIS, and 

FWS and NMFS recommended that the current listing classifications remain unchanged. Because the 181 

South Area is nearly 130 mi (209 km) from the nearest coast, all five species of sea turtles may potentially 

exist within the 181 South Area, and it appears to be an important habitat for leatherbacks. Impacts from 

routine activities and accidental events occurring in the 181 South Area are similar to the rest of the sale 

area. In most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of 

an oil slick will result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and 

increased vulnerability to disease) to sea turtles. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. The routine activities of a proposed action are unlikely to have 

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

Mexico. Accidental events associated with a proposed action have the potential to impact small to large 
4-96 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 a 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 

will result in sublethal impacts. However, the incremental contribution of a CPA or WPA proposed 

action, including the 181 South Area, to the numerous, cumulative impacts to sea turtles are not expected 

to be significant, especially due to mitigations currently in place. 

4.1.7.1. Description of the Affected Environment 

A detailed description of sea turtles in the Gulf of Mexico can be found in Chapter 3.2.4 of the 

Multisale EIS. The following is a summary of that description, which incorporates new information 

found since the publication of the Multisale EIS. 

Of the seven or eight extant species of sea turtles, five are known to inhabit the waters of the Gulf of 

Mexico (Pritchard, 1997): the leatherback, green turtle, hawksbill, Kemp’s ridley, and loggerhead 

(Table 4-5). These five species are all highly migratory, and no individual members of any of the species 

are likely to be year-round residents of the analysis area. Individual animals will make migrations into 

nearshore waters as well as other areas of the North Atlantic Ocean, Gulf of Mexico, and the Caribbean 

Sea. Because the 181 South Area is nearly 130 mi (2009 km) from the nearest coast, sea turtles may 

potentially exist within the 181 South Area. 

All five species of sea turtles found in the Gulf of Mexico have been federally listed as endangered or 

threatened since the 1970’s. There is currently no critical habitat designated in the Gulf of Mexico. 

A search was conducted for new information published since completion of the Multisale EIS. In 

August 2007, FWS and NMFS published 5-year status reviews for federally listed sea turtles in the Gulf 

of Mexico. (USDOC, NMFS and USDOI, FWS, 2007a-e) A 5-year review is an ESA-mandated process 

that is conducted to ensure the listing classification of a species as either threatened or endangered is still 

accurate. Both agencies share jurisdiction for federally listed sea turtles and jointly conducted the 

reviews. After reviewing all of the best scientific and commercially available information and data, the 

agencies’ biologists recommended that the current listing classification for the five sea turtle species 

remain unchanged. New Gulf of Mexico information from the 5-year reviews is included in this section. 

Natural disturbances such as hurricanes can cause significant destruction of nests and topography of 

nesting beaches (Pritchard, 1980; Ross and Barwani, 1982; Witherington, 1986). Tropical storms and 

hurricanes are a normal occurrence in the Gulf of Mexico and along the coast. Generally, the impacts 

have been localized and infrequent. Few areas of the Gulf Coast have not suffered some damage in 2004 

and 2005, and activities in the Gulf of Mexico have also been severely impacted. Some impacts, such as 

loss of beach habitat, are known to have occurred and will impact sea turtles that would have used those 

areas for nesting beaches. Increases or decreases in beach armoring and other structures may impact all 

nesting sea turtles in the areas affected. Hurricanes and tropical activity may temporarily remove some of 

these barriers to suitable nesting habitat. However, rebuilding may replace and expand the structures, 

magnifying the impact of natural habitat loss with manmade habitat loss. 

Global climate change could result in numerous and severe impacts to sea turtles. Rising sea levels 

could further diminish available nesting beach habitat. Changing ocean temperatures may alter 

distribution patterns for sea turtle prey (i.e., jellyfish for leatherbacks). This could impact adult 

survivability as well as nesting success. Warming temperatures may change the sex ratios of hatchlings 

as sex is determined by nest temperature. These are just a few examples of potential effects of global 

climate change. Though extremely difficult to predict, this is a topic of growing concern. 

Leatherback Sea Turtle 

The leatherback is the most abundant sea turtle in waters over the northern Gulf of Mexico 

continental slope (Mullin and Hoggard, 2000). Leatherbacks appear to spatially use both continental shelf 

and slope habitats in the Gulf of Mexico (Fritts et al., 1983b; Collard, 1990; Davis and Fargion, 1996). 

Surveys suggest that the region from Mississippi Canyon to DeSoto Canyon, especially near the shelf 

edge, which is north of the 181 South Area, appears to be an important habitat for leatherbacks (Mullin 

and Hoggard, 2000). Leatherbacks have been frequently sighted in the Gulf of Mexico during both 

summer and winter (Mullin and Hoggard, 2000). 
Environmental and Socioeconomic Consequences 4-97 

In Florida, an increase in leatherback nesting numbers from 98 nests in 1988 to 800-900 nests per 

season in the early 2000’s has been recorded. There has been a substantial increase in leatherback nesting 

in Florida since 1989 (USDOC, NMFS and USDOI, FWS, 2007a). However, there have been no 

confirmed sightings of leatherbacks coming ashore to nest within the CPA or WPA since 1930 in Texas 

(USDOI, FWS, 2007a). Although nesting is very rare on Gulf of Mexico beaches, leatherbacks occur in 

Gulf of Mexico waters. Satellite telemetry and tag returns have shown that some of the leatherbacks 

present in the Gulf of Mexico were tagged at nesting beaches in Costa Rica and Panama (USDOC, NMFS 

and USDOI, FWS, 2007a). 

The leatherback sea turtle is listed as endangered. Ongoing threats to leatherbacks include ingestion 

of marine debris, poaching of eggs and animals, and entanglement in longline fishing gear. 

Green Sea Turtle 

All green sea turtle populations are listed as threatened except for the breeding populations of Florida 

and the Pacific Coast of Mexico, which are endangered. Green sea turtles are found throughout the Gulf 

of Mexico , and are known to nest on Gulf of Mexico beaches but in very small numbers. 

The east coast of Florida is one of the most important nesting areas for green turtles, and the Florida 

nesting population is listed as endangered. The green turtle nesting population of Florida appears to be 

increasing based on 18 years (1989-2006) of nesting data from throughout the State (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 food and other products. Significant threats on green turtle nesting 

beaches in the region include beach armoring, erosion control, artificial lighting, and disturbance. 

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 (IUCN) based on global population declines of over 80 percent during the last 

three generations (105 years) (Meylan and Donnelly, 1999). The Atlantic Coast of Florida is the only 

area in the U.S. where hawksbills nest on a regular basis. 

Hawksbills are threatened by all the factors that threaten other marine turtles, including exploitation 

for meat, eggs, and the curio trade, loss or degradation of nesting and foraging habitats, increased human 

presence, nest depredation, oil pollution, incidental capture in fishing gear, ingestion of and entanglement 

in marine debris, and boat collisions (Lutcavage et al., 1997; Meylan and Ehrenfeld, 2000). The primary 

cause of hawksbill decline has been attributed to centuries of exploitation for tortoiseshell, the beautifully 

patterned scales that cover the turtle’s shell (Parsons, 1972). Another manmade factor that affects 

hawksbills in foraging areas and on nesting beaches is global climate change (USDOC, NMFS and 

USDOI, FWS, 2007c). 

Kemp’s Ridley 

Ogren (1988) suggests that the Gulf Coast, from Port Aransas, Texas, through Cedar Key, Florida, 

represents the primary habitat for subadult ridleys in the northern Gulf of Mexico. Internationally, the 

Kemp’s ridley is considered the most endangered sea turtle. There is no designated critical habitat for the 

Kemp’s ridley sea turtle. 

The species occurs mainly in coastal areas of the Gulf of Mexico and the northwestern Atlantic 

Ocean. Kemp’s ridleys nest in daytime aggregations known as arribadas, primarily at Rancho Nuevo, a 

stretch of beach in Mexico, Tamaulipas State. A 2007 arribada at Rancho Nuevo included over 4,000 

turtles over a 3-day period (USDOC, NMFS and USDOI, FWS, 2007d). Kemp’s ridley nests on South 

Padre Island, Texas, numbered 125 in 2007, and the nesting season had not yet ended. Fifteen nests were 

counted in Galveston County, Texas. This is the highest count for both Texas areas since the recording of 

nests began in the 1980’s. 
4-98 Central and Western Gulf of Mexico Multisale Supplemental EIS

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. 

Loggerhead Sea Turtle 

Loggerhead nesting along the Gulf Coast occurs primarily along the Florida Panhandle, although 

some nesting has been reported from Texas through Alabama as well (USDOC, NMFS and USDOI, 

FWS, 1991b). Loggerhead turtles have been primarily sighted in waters over the continental shelf, 

although many surface sightings of this species have also been made over the outer slope beyond the 

1,000-m (3,281-ft) isobath. The loggerhead sea turtle is listed as threatened. 

Ongoing threats to the western Atlantic loggerhead populations include incidental takes from 

dredging, commercial trawling, longline fisheries, and gillnet fisheries; loss or degradation of nesting 

habitat from coastal development and beach armoring; disorientation of hatchlings by beachfront lighting; 

nest predation by native and nonnative predators; degradation of foraging habitat; marine pollution and 

debris; watercraft strikes; and disease. 

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. Along the 47-mi (76-km) stretch of Alabama coastline, 62 

loggerhead nests were reported in 2003, 53 in 2004, and 45 in 2006 (data from 2005 is not available). 

Texas reported two loggerhead nests in 2006 and, prior to the end of the 2007 nesting season, Texas had 

three loggerhead nests. Louisiana has had no recorded loggerhead nests in the last 5 years. The number 

of nests in 2007 on Mississippi beaches is expected to be low. 

Recent Consultation 

As mandated by the ESA, MMS consulted with NMFS and FWS on possible and potential impacts 

from a CPA or WPA proposed action on endangered/threatened species and designated critical habitat 

under their jurisdiction. A biological assessment (BA) was prepared for each consultation. The action 

area analyzed in the BA’s included the “181 South Area” addressed in this SEIS. 

The formal ESA consultation with NMFS was concluded with receipt of the BO on July 3, 2007 

(USDOC, NMFS, 2007d). The BO concludes that the proposed lease sales and associated activities in the 

Gulf of Mexico in the 2007-2012 OCS Leasing Program, which includes the proposed lease sales 

addressed in this SEIS, are not likely to jeopardize the continued existence of threatened and endangered 

species under NMFS jurisdiction or destroy or adversely modify designated critical habitat. Sea turtles 

are under NMFS jurisdiction except when on the nesting beaches. The NMFS issued an Incidental Take 

Statement on sea turtle species; the Statement contains reasonable and prudent measures (RPM’s) with 

implementing terms and conditions to help minimize take. 

The informal ESA consultation with FWS was concluded by letter dated September 14, 2007. The 

FWS concurred with the MMS determination that the proposed actions of the 2007-2012 OCS Leasing 

Program were not likely to adversely affect the threatened/endangered species or designated critical 

habitat under FWS jurisdiction. Sea turtles are under FWS jurisdiction when on a nesting beach. 

4.1.7.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on sea turtles is presented in Chapters 4.2.2.1.6 and 4.2.1.1.6 of the Multisale EIS, 

respectively. 

The major impact-producing factors resulting from the routine activities associated with a CPA or 

WPA proposed action that may affect loggerhead, Kemp’s ridley, hawksbill, green, and leatherback 

turtles include water-quality degradation from operational contaminant discharges; noise from seismic 

exploration, helicopter and vessel traffic, operating platforms, and drillships; vessel collisions; explosive 

platform removals; and OCS-related trash and debris. 
Environmental and Socioeconomic Consequences 4-99 

Effluents are routinely discharged into offshore marine waters and are regulated by the USEPA’s 

NPDES permits. Information on the contaminants that would be discharged offshore as a result of a 

proposed action is provided in Chapter 4.1.1.4 of the Multisale EIS. 

Structure installation, pipeline placement, dredging, blowouts, and water quality degradation can 

impact seagrass bed and live-bottom sea turtle habitats. These impacts are analyzed in detail in Chapters 

4.2.2.1.3.3 and 4.2.2.1.4.1.1 of the Multisale EIS. The seagrass and high-salinity marsh components of 

wetland loss would be indirectly important for sea turtles by reducing the availability of forage species 

that rely on these sensitive habitats. 

Noise from service-vessel traffic and helicopter overflights may elicit a startle reaction from sea 

turtles and there is the possibility of short-term disruption of activity patterns. In the wild, most sea 

turtles spend at least 3-6 percent of their time at the surface. Despite the brevity of their respiratory 

phases, sea turtles sometimes spend as much as 19-26 percent of their time at the surface, engaged in 

surface basking, feeding, orientation, and mating (Lutcavage et al., 1997). Sea turtles located in 

shallower waters have shorter surface intervals, whereas turtles occurring in deeper waters have longer 

surface intervals. 

Exploration wells and producing development wells are projected to be drilled as a result of a CPA or 

WPA proposed action. Potential effects on turtles include disturbance (e.g., subtle changes in behavior 

and interruption of activity), masking of other sounds (e.g., surf, predators, and vessels), and stress (i.e., 

physiological). 

A wide variety of trash and debris is commonly observed in the Gulf of Mexico. Marine trash and 

debris comes from a variety of land-based and ocean sources (Cottingham, 1988). Some material is 

accidentally lost during drilling and production operations. 

CPA Proposed Action Analysis 

The major impact-producing factors resulting from the routine activities associated with a CPA 

proposed action that may affect loggerhead, Kemp’s ridley, hawksbill, green, and leatherback turtles 

include water-quality degradation from operational contaminant discharges; noise from seismic 

exploration, helicopter and vessel traffic, operating platforms, and drillships; vessel collisions; explosive 

platform removals; and OCS-related trash and debris. These impacts are similar in the 181 South Area as 

they are to the rest of the sale area. 

Turtles may be affected by routinely discharged effluents. Very little information exists on the 

impact of drilling muds on Gulf of Mexico sea turtles (Tucker and Associates, Inc., 1990). 

Little or no damage is expected to the physical integrity, species diversity, or biological productivity 

of live-bottom marine turtle habitat as a result of a CPA proposed action because these sensitive resources 

are protected by several mitigation measures established by MMS. These mitigation measures include 

marine protected species NTL’s (Chapter 1.5). 

An estimated 2,975-6,025 service-vessel round trips are expected to occur annually as a result of a 

CPA proposed action. Transportation corridors would be through areas where sea turtles have been 

sighted. It is not known whether turtles exposed to recurring vessel disturbance will be stressed or 

otherwise affected in a negative but inconspicuous way. Increased vessel traffic will increase the 

probability of collisions between vessels and turtles, potentially resulting in injury or death to some 

animals. 

The exploration and producing development wells could generate sounds at intensities and 

frequencies that could be heard by turtles. There is some evidence suggesting that turtles may be 

receptive to low-frequency sounds, which is at the level where most industrial noise energy is 

concentrated. 

Sea turtles can become entangled in or ingest debris produced by exploration and production 

activities resulting from a CPA proposed action. Leatherback turtles that mistake plastics for jellyfish 

may be more vulnerable to gastrointestinal blockage than other sea turtle species. The probability of 

plastic ingestion/entanglement is unknown. 

WPA Proposed Action Analysis 

The major impact-producing factors resulting from the routine activities associated with a WPA 

proposed action that may affect loggerhead, Kemp’s ridley, hawksbill, green, and leatherback turtles 
4-100 Central and Western Gulf of Mexico Multisale Supplemental EIS

include water-quality degradation from operational contaminant discharges; noise from seismic 

exploration, helicopter and vessel traffic, operating platforms, and drillships; vessel collisions; explosive 

platform removals; and OCS-related trash and debris. 

Turtles may be affected by routinely discharged effluents. Very little information exists on the 

impact of drilling muds on Gulf of Mexico sea turtles (Tucker and Associates, Inc., 1990). 

Little or no damage is expected to the physical integrity, species diversity, or biological productivity 

of live-bottom marine turtle habitat as a result of a WPA proposed action because these sensitive 

resources are protected by several mitigation measures established by MMS. These mitigation measures 

include marine protected species NTL’s (Chapter 1.5). 

An estimated 2,350-3,875 service-vessel round trips are expected to occur annually as a result of a 

WPA proposed action. Transportation corridors would be through areas where sea turtles have been 

sighted. It is not known whether turtles exposed to recurring vessel disturbance will be stressed or 

otherwise affected in a negative but inconspicuous way. Increased vessel traffic will increase the 

probability of collisions between vessels and turtles, potentially resulting in injury or death to some 

animals. 

The exploration and producing development wells could generate sounds at intensities and 

frequencies that could be heard by turtles. There is some evidence suggesting that turtles may be 

receptive to low-frequency sounds, which is at the level where most industrial noise energy is 

concentrated. 

Sea turtles can become entangled in or ingest debris produced by exploration and production 

activities resulting from a WPA proposed action. Leatherback turtles that mistake plastics for jellyfish 

may be more vulnerable to gastrointestinal blockage than other sea turtle species. The probability of 

plastic ingestion/entanglement is unknown. 

Recent Consultation 

The NMFS has determined that the following RPM’s are necessary and appropriate to minimize 

impacts of the incidental take of sea turtles from vessel operation. 

(1) The MMS must reduce the potential for sea turtles to be struck and injured by vessels 

operating in support of oil and gas development activities in the Gulf of Mexico. 

(2) The MMS must require the monitoring and reporting of any sea turtles struck or 

observed to have sign of vessel interaction to assess the actual level of incidental take 

in comparison with the anticipated incidental take. 

In order to be exempt from liability for take prohibited by Section 9 of the ESA, MMS must comply 

with the following terms and conditions, which implement the RPM’s described above. These terms and 

conditions are nondiscretionary. 

The following term and condition implements RPM No. 1: 

(1) The MMS must implement NMFS measures to reduce the risk of accidental vessel 

strikes with sea turtles by use of its legal authorities to ensure implementation of, and 

compliance with, NTL 2007-G04. 

The following terms and conditions implement RPM No. 2: 

(1) The MMS must make information available to vessel operators concerning species 

information on sea turtles in the Gulf of Mexico and reporting of vessel-struck, or 

injured or dead animals. 

(2) The MMS must ensure that all vessel-struck, or injured or dead turtles with 

indications of vessel interactions are reported to the Sea Turtle Stranding Network 

Coordinator in the nearest coastal state. Any takes of listed species shall be reported 

to the NMFS Southeast Regional Office within no more than 24 hr of the incident to 

takereport.nmfsser@noaa.gov. If an MMS action is responsible for the injured or 

dead animals (e.g., because of a vessel strike), MMS shall require the responsible 
Environmental and Socioeconomic Consequences 4-101 

parties to assist the respective salvage and stranding network as appropriate. Report 

dead or injured protected species to your local stranding network contacts. 

(3) The MMS must submit an annual report to the NMFS Southeast Regional Office 

regarding the reports of vessel-struck sea turtles, and injured and dead sea turtles 

reported from oil and gas operators. Hardcopies of all annual reports will be 

submitted to the following address: 

Assistant Regional Administrator for Protected Resources 

National Marine Fisheries Service 

263 13th Avenue South 

St. Petersburg, FL 33701

The NMFS expects impacts to sea turtles in the proposed lease sale area as a result of OCS oil and 

gas leasing activities. Based on stranding records, incidental captures during recreational and commercial 

fishing operations, scientific surveys, and historical data, the five species of sea turtles are known to occur 

in Gulf of Mexico waters in and around the proposed lease sale areas. The vessel strike avoidance 

requirements (NTL 2003-G10) will appreciably reduce the numbers of sea turtles that may be incidentally 

taken from routine offshore vessel operations; however, the available information on the relationship 

between these species and OCS oil and gas activities indicates that sea turtles may be killed or injured by 

vessel strikes. Therefore, pursuant to Section 7(b)(4) of the ESA, NMFS anticipates incidental take as 

follows: 

• 119 lethal takes (2.9 individuals annually, on average) and 238 nonlethal takes (5.9 

individuals annually, on average) of loggerhead sea turtles over the 40-year lifetime; 

• 10 lethal takes (1 individual every 4 years, on average) and 21 nonlethal takes (1 

individual every 1.9 years, on average) of leatherback sea turtles over the 40-year 

lifetime; 

• 13 lethal takes (1 individual every 3 years, on average) and 26 nonlethal takes (1 

individual every 1.5 years, on average) of Kemp’s ridley sea turtles over the 40-year 

lifetime; 

• 38 lethal takes (1 individual every 1.1 years, on average) and 76 nonlethal takes (1.9 

individuals annually, on average) of green sea turtles over the 40-year lifetime; and 

• 1 lethal take and 1 nonlethal take of a hawksbill sea turtle over the 40-year lifetime. 

If the actual incidental take exceeds this level, MMS must immediately reinitiate formal consultation. 

Summary and Conclusion 

Routine activities resulting from a CPA or WPA proposed action have the potential to harm sea 

turtles. These animals could be impacted by the degradation of water quality resulting from operational 

discharges; noise generated by seismic exploration, helicopter and vessel traffic, platforms, and drillships; 

vessel collisions; and marine debris generated by service vessels and OCS facilities. These impacts are 

similar in the 181 South Area as they are to the rest of the sale area. Lethal effects are most likely to be 

from chance collisions with OCS service vessels and ingestion of plastic materials. Most OCS activities 

are expected to have sublethal effects. 

Contaminants in waste discharges and drilling muds might indirectly affect sea turtles through foodchain biomagnification, but there is uncertainty concerning the possible effects. Rapid dilution of the 

discharges should minimize impact. Chronic sublethal effects (e.g., stress) resulting in persistent 

physiological or behavioral changes and/or avoidance of impacted areas from noise disturbance could 

cause declines in survival or fecundity, and result in population declines; however, such declines are not 

expected. The required seismic operation mitigations, particularly clearance of the impact area of sea 

turtles and marine mammals prior to ramp-up, and the subsequent gradual ramping up of the airguns, 

should minimize the impact of rapid onset of, and close proximity to, very loud noise. Vessel traffic is a 
4-102 Central and Western Gulf of Mexico Multisale Supplemental EIS

serious threat to sea turtles. Diligence on the part of vessel operators as encouraged by the vessel strike 

mitigations should minimize vessel/sea turtle collisions. 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 and minimizing the devastating effects on sea turtles. The routine activities of a 

CPA or WPA proposed action are unlikely to have significant adverse effects on the size and recovery of 

any sea turtle species or population in the Gulf of Mexico. 

4.1.7.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of the possible impacts from accidental events associated with a CPA or WPA 

proposed action on sea turtles is presented in Chapter 4.4.6 of the Multisale EIS. Accidental, unexpected 

industrial events associated with a CPA or WPA proposed action could impact sea turtles. Such impacts 

would primarily be the result of blowouts, oil spills, and/or effects associated with the response to an oil 

spill. 

Blowouts can occur during any phase of development: exploratory drilling, development drilling, 

production, completion, or workover operations. In the event of a blowout, the eruption of gases and 

fluids may generate significant pressure waves and noise that may harass, injure, or kill sea turtles, 

depending on their proximity to the accident. 

Since sea turtle habitat in the Gulf of Mexico includes inshore, coastal, and oceanic waters, as well as 

numerous beaches in the region, sea turtles could be impacted by accidental spills resulting from 

operations associated with the CPA and WPA proposed actions. The potential causes, sizes, and 

probabilities of oil spills that could occur during drilling, production, and transportation operations 

associated with a proposed action are presented in Chapter 4.3.1 of the Multisale EIS. 

All neonate sea turtles undertake a passive voyage via oceanic waters following nest evacuation. 

Depending on the species and population, their voyage in oceanic waters may last 10 or more years. 

Beaches of the Caribbean Sea and Gulf of Mexico are used as nesting habitat, and hatchlings evacuating 

these nesting beaches emigrate to oceanic waters seaward of their nesting sites. 

Spills of any size degrade water quality and residuals become available for bioaccumulation within 

the food chain. Slicks may spread at the sea surface or may migrate underwater from the seafloor through 

the water column and never broach the sea surface. Regardless, a slick is an expanding, but aggregated 

mass of oil that, with time, will disperse into smaller units as it evaporates (if at the sea surface) and 

weathers. Chapter 4.3.1.6.4 of the Multisale EIS details the persistence, spreading, and weathering 

process for offshore spills. 

CPA Proposed Action Analysis 

Accidental, unexpected industrial events associated with the CPA proposed action could impact sea 

turtles. Such impacts would primarily be the result of blowouts, oil spills, and/or effects associated with 

the response to an oil spill. These impacts are similar in the 181 South Area as they are to the rest of the 

sale area. However, as explained in Chapter 3.2.1, the incremental increase in oil production from the 

addition of the 181 South Area is not expected to result in an overall increase in the numbers of oil spills 

≥1,000 bbl likely to occur as a result of a CPA proposed action. 

In the event of a blowout, the eruption of gases and fluids may generate significant pressure waves 

and noise that may harass, injure, or kill sea turtles, depending on their proximity to the accident. 

Fortunately, improvements in technology and equipment have greatly decreased the occurrence of 

blowouts. 

In general terms, coastal waters of the planning areas are expected to be impacted by many, frequent, 

small spills (≤1 bbl); few, infrequent, moderately-sized spills (>1 and <1,000 bbl); and a single, large 

(≥1,000 bbl) spill. Pipelines pose the greatest risk of a large spill occurring in coastal waters. Depending 

on the timing of the spill’s occurrence in coastal waters, its impact and resulting cleanup may interrupt sea 

turtle migration, feeding, mating, and/or nesting activity for extended periods (days, weeks, months). 
Environmental and Socioeconomic Consequences 4-103 

Aside from the acute effects noted if sea turtles encounter an oil slick, the displacement of sea turtles to 

less suitable habitats from habitual feeding areas impacted by oil spills may increase vulnerability to 

predators, disease, or anthropogenic mortality. The interruption of mating and nesting activities for 

extended periods may influence the recovery of sea turtle populations. 

Sea turtle journeys begin as pulsed events, with many hatchlings emerging and emigrating offshore at 

the same times. Consequently, intermediate to large spills occurring in these waters may impact multiple 

turtles, particularly neonate or young juvenile sea turtles associating with oceanic fronts or refuging in 

sargassum mats where oil slicks, decomposing residues, and tarballs are likely to accumulate. Large 

spills, particularly those flowing fresh hydrocarbons into oceanic and/or outer shelf waters for extended 

periods (days, weeks, months), pose an increased risk of impacting sea turtles inhabiting these waters. 

There is an extremely small probability that a single sea turtle will encounter an oil slick resulting 

from a single, small spill. It is impossible to estimate precisely what sea turtle species, populations, or 

individuals will be impacted, to what magnitude, or in what numbers, since each species has unique 

distribution patterns in the Gulf of Mexico and because of difficulties attributed to estimating when and 

where oil spills will occur. 

As residues of an oil spill disperse and commit to the physical environment (i.e., water, sediments, 

and particulates), sea turtles of any life history stage may be exposed via the waters that they drink and 

swim, as well as via the prey they consume. For example, tarballs may be consumed by sea turtles and by 

other marine organisms, and eventually bioaccumulate within sea turtles. Although sea turtles may (or 

may not) avoid oil spills or slicks, it is highly unlikely that they are capable of avoiding spill residuals in 

their environment. Consequently, the probability that a sea turtle is exposed to oil resulting from a spill 

extends well after the oil spill has dispersed from its initial aggregated mass. 

Contact with petroleum and consumption of oil and oil-contaminated prey may seriously impact 

turtles; there is direct evidence that turtles have been seriously harmed by petroleum spills. Oil spills and 

residues have the potential to cause chronic (longer-term lethal or sublethal oil-related injuries) and acute 

(spill-related deaths occurring during a spill) effects on turtles. 

Due to spill response and cleanup efforts, much of an oil spill may be recovered before it reaches the 

coast. However, cleanup efforts in offshore waters may result in additional harm or mortality of sea 

turtles, particularly to neonates and juveniles. Oil spills and spill-response activities at nesting beaches, 

such as beach sand removal and compaction, can negatively affect sea turtles. Although spill-response 

activities such as vehicular and vessel traffic during nesting season are assumed to affect sea turtle 

habitats, further harm may be limited because of efforts designed to prevent spilled oil from contacting 

these areas. Increased human presence could influence turtle behavior and/or distribution, thereby 

stressing animals and making them more vulnerable to predators, the toxicological effects of oil, or other 

anthropogenic sources of mortality. 

WPA Proposed Action Analysis 

Accidental, unexpected industrial events associated with a WPA proposed action could impact sea 

turtles. Such impacts would primarily be the result of blowouts, oil spills, and/or effects associated with 

the response to an oil spill. 

In the event of a blowout, the eruption of gases and fluids may generate significant pressure waves 

and noise that may harass, injure, or kill sea turtles, depending on their proximity to the accident. 

Fortunately, improvements in technology and equipment have greatly decreased the occurrence of 

blowouts. 

In general terms, coastal waters of the planning areas are expected to be impacted by many, frequent, 

small spills (≤1 bbl); few, infrequent, moderately-sized spills (>1 and <1,000 bbl); and a single, large 

(≥1,000 bbl) spill. Pipelines pose the greatest risk of a large spill occurring in coastal waters. Depending 

on the timing of the spill’s occurrence in coastal waters, its impact and resulting cleanup may interrupt sea 

turtle migration, feeding, mating, and/or nesting activity for extended periods (days, weeks, months). 

Aside from the acute effects noted if sea turtles encounter an oil slick, the displacement of sea turtles to 

less suitable habitats from habitual feeding areas impacted by oil spills may increase vulnerability to 

predators, disease, or anthropogenic mortality. The interruption of mating and nesting activities for 

extended periods may influence the recovery of sea turtle populations. 

Sea turtle journeys begin as pulsed events, with many hatchlings emerging and emigrating offshore at 
4-104 Central and Western Gulf of Mexico Multisale Supplemental EIS

the same times. Consequently, intermediate to large spills occurring in these waters may impact multiple 

turtles, particularly neonate or young juvenile sea turtles associating with oceanic fronts or refuging in 

sargassum mats where oil slicks, decomposing residues, and tarballs are likely to accumulate. Large 

spills, particularly those flowing fresh hydrocarbons into oceanic and/or outer shelf waters for extended 

periods (days, weeks, months), pose an increased risk of impacting sea turtles inhabiting these waters. 

There is an extremely small probability that a single sea turtle will encounter an oil slick resulting 

from a single, small spill. It is impossible to estimate precisely what sea turtle species, populations, or 

individuals will be impacted, to what magnitude, or in what numbers, since each species has unique 

distribution patterns in the Gulf of Mexico and because of difficulties attributed to estimating when and 

where oil spills will occur. 

As residues of an oil spill disperse and commit to the physical environment (i.e., water, sediments, 

and particulates), sea turtles of any life history stage may be exposed via the waters that they drink and 

swim, as well as via the prey they consume. For example, tarballs may be consumed by sea turtles and by 

other marine organisms, and eventually bioaccumulate within sea turtles. Although sea turtles may (or 

may not) avoid oil spills or slicks, it is highly unlikely that they are capable of avoiding spill residuals in 

their environment. Consequently, the probability that a sea turtle is exposed to oil resulting from a spill 

extends well after the oil spill has dispersed from its initial aggregated mass. 

Contact with petroleum and consumption of oil and oil-contaminated prey may seriously impact 

turtles; there is direct evidence that turtles have been seriously harmed by petroleum spills. Oil spills and 

residues have the potential to cause chronic (longer-term lethal or sublethal oil-related injuries) and acute 

(spill-related deaths occurring during a spill) effects on turtles. 

Due to spill response and cleanup efforts, much of an oil spill may be recovered before it reaches the 

coast. However, cleanup efforts in offshore waters may result in additional harm or mortality of sea 

turtles, particularly to neonates and juveniles. Oil spills and spill-response activities at nesting beaches, 

such as beach sand removal and compaction, can negatively affect sea turtles. Although spill-response 

activities such as vehicular and vessel traffic during nesting season are assumed to affect sea turtle 

habitats, further harm may be limited because of efforts designed to prevent spilled oil from contacting 

these areas. Increased human presence could influence turtle behavior and/or distribution, thereby 

stressing animals and making them more vulnerable to predators, the toxicological effects of oil, or other 

anthropogenic sources of mortality. 

Recent Consultation 

The NMFS believes that a small number of listed species will experience adverse effects as the result 

of exposure to a large oil spill or ingestion of accidentally spilled oil over the lifetime of a CPA or WPA 

proposed action. However, NMFS is not including an Incidental Take Statement for the incidental take of 

listed species due to oil exposure. Incidental take, as defined at 50 CFR 402.02, refers only to takings that 

result from an otherwise lawful activity. The Clean Water Act (33 U.S.C. 1251 et seq.), as amended by 

OPA (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 BO considered the effects on listed 

species by oil spills that may result from a proposed action, those takings that would result from an 

unlawful activity (i.e., oil spills) are not specified in the Incidental Take Statement and have no protective 

coverage under Section 7(o)(2) of the ESA. 

Summary and Conclusion 

Accidental blowouts, oil spills, and spill-response activities resulting from a CPA or WPA proposed 

action have the potential to impact small to large numbers of sea turtles in the Gulf of Mexico, 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. These impacts are similar in the 181 

South Area as they are to the rest of the sale area. Populations of sea turtles in the northern Gulf of 

Mexico would be exposed to residuals of oils spilled as a result of a proposed action during their 

lifetimes. Chronic or acute exposure from accidental events may result in the harassment, harm, or 

mortality to sea turtles occurring in the northern Gulf of Mexico. In most foreseeable cases, exposure to 

hydrocarbons persisting in the sea following the dispersal of an oil slick will result in sublethal impacts 

(e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) to sea 
Environmental and Socioeconomic Consequences 4-105 

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. 

4.1.7.4. Cumulative Impacts 

Background/Introduction 

A detailed description of possible cumulative impacts on sea turtles is presented in Chapter 4.5.6 of 

the Multisale EIS. This cumulative analysis considers the effects of impact-producing factors related to a 

CPA or WPA proposed action, along with impacts of other commercial, military, recreational, offshore, 

and coastal activities that may occur and adversely affect populations of sea turtles in the same general 

area of the proposed actions. The combination of potential impacts resulting from a proposed action in 

addition to prior and future OCS sales, dredging operations, beach nourishment, beach lighting, power 

plant entrainment, military operations, water quality degradation, noise from numerous sources, vessel 

traffic, marine debris, pollution, recreational and commercial fishing, human consumption, and natural 

catastrophes affect the loggerhead, Kemp’s ridley, hawksbill, green, and leatherback turtles found in the 

Gulf of Mexico. Major impact-producing factors related to the CPA and WPA proposed actions that may 

occur are reviewed in detail in Chapters 4.2.2.1.6 and 4.2.1.1.6 of the Multisale EIS, respectively. 

Sections providing supportive material for the sea turtle analysis include Chapters 3.1 (physical 

environment), 3.2.4 (description of sea turtles), 4.1.1 (offshore impact-producing factors), 4.1.2 (coastal 

impact-producing factors), 4.1.3 (other activities), and 4.4 (environmental impacts of accidental events) of 

the Multisale EIS. 

The Gulf Coast is a well-populated and growing area, and development of previously unusable land 

for residential and commercial purposes is common. Increased populations often result in increased 

runoff and dumping. Many areas around the Gulf of Mexico already suffer from very high contaminant 

counts due to river and coastal runoff and discharges. Contaminants may accumulate in species or in prey 

species. Effluents are routinely discharged into offshore waters and are regulated by USEPA NPDES 

permits. Most operational discharges are diluted and dispersed when released in offshore areas and, due 

to the USEPA permit regulations on discharges, are considered to have little effect (API, 1989; Kennicutt, 

1995). Any potential that might exist for impact from drilling fluids would more likely be indirect, either 

by impact on prey items or possibly through ingestion via the food chain (API, 1989). Contaminants in 

drilling mud discharge may biomagnify and bioaccumulate in the food web, which may kill or debilitate 

important prey species of sea turtles or species lower in the marine food web. This could ultimately 

reduce reproductive fitness or longevity in sea turtles. 

Dredge-and-fill activities occur in many of the coastal areas inhabited by sea turtles. Operations 

range in scope from propeller dredging (scarring) by recreational boats to large-scale navigation dredging 

and fill for land reclamation. Dredging operations affect turtles through accidental take and habitat 

degradation. The construction and maintenance of Federal navigation channels has been identified as a 

source of sea turtle mortality. In addition to direct take, channelization of the inshore and nearshore areas 

can degrade foraging and migratory habitats via spoil dumping, degraded water quality/clarity, and 

altered current flow. 

Structure installation and removal, pipeline placement, dredging, and water quality degradation may 

adversely affect sea turtle foraging habitat through destruction of seagrass beds and live-bottom 

communities used by sea turtles (Gibson and Smith, 1999). At the same time, it should be noted that 

structure installation creates habitat for subadult and adult sea turtles, which may enhance the recovery of 

some turtle populations. 

Noise from service-vessel and helicopter traffic may cause a startle reaction from sea turtles and 

produce temporary stress (NRC, 1990). Additional activities, including vessel operations and ordnance 

detonation, also affect sea turtles. Private and commercial air traffic also traverse these areas and have 

the potential to cause impacts to sea turtles. Other sound sources potentially impacting sea turtles include 

seismic surveys and drilling noise. The potential impacts of anthropogenic sounds on sea turtles include 

physical auditory effects (temporary threshold shift), behavioral disruption, long-term effects, masking, 

and adverse impacts on prey species. Noise-induced stress has not been studied in sea turtles. Seismic 

surveys use airguns to generate sound pulses, which are a more intense sound than other nonexplosive 

sound sources. Seismic activities are expected to be primarily annoyance to sea turtles and cause a short-
4-106 Central and Western Gulf of Mexico Multisale Supplemental EIS

term behavioral response. However, sea turtles are included in the mitigations required of all seismic 

vessels operating in the Gulf of Mexico, as stated in NTL 2007-G02, “Implementation of Seismic Survey 

Mitigation Measures and Protected Species Observer Program.” 

Explosive discharges such as those used for MMS and COE structure removals can cause injury to 

sea turtles (Duronslet et al., 1986). Although sea turtles far from the site may suffer only disorientation, 

those near detonation sites could sustain fatal injuries. Other potential impacts include physical or 

acoustic harassment. Resuspension of bottom sediments, increased water turbidity, and mobilization of 

bottom sediments due to explosive detonation are considered to be temporary effects. To minimize the 

likelihood of removals occurring when sea turtles may be nearby, MMS issued guidelines for explosive 

platform removal to offshore operators. With these existing protective measures (NMFS Observer 

Program and daylight-only demolition) in place, the “take” of sea turtles during structure removals has 

been limited. 

Increased surfacing places turtles at greater risk of vessel collision. Vessel traffic, particularly supply 

boats running from shore bases to offshore structures, is one of the industry activities included in these 

proposed actions. Collisions between service vessels or barges and sea turtles would likely cause fatal 

injuries. In response to terms and conditions of previous NMFS Biological Opinions, and in an effort to 

minimize the potential for industry-related vessel strikes to sea turtles, MMS issued NTL 2007-G04, 

“Vessel Strike Avoidance and Injured/Dead Protected Species Reporting.” The NMFS has recommended 

conservation measures for operations of agency, contract or private vessels to minimize impacts on listed 

species. However, these actions represent the potential for some level of interaction and, in some cases, 

conservation measures only apply to areas outside the proposed action areas. 

Sea turtles may be seriously impacted by marine debris. Floating plastics and other debris, such as 

petroleum residues drifting on the sea surface, accumulate in sargassum drift lines commonly inhabited 

by hatchling sea turtles. These materials could be toxic. The MMS prohibits the disposal of equipment, 

containers, and other materials into offshore waters by lessees (30 CFR 250.40). In addition, MARPOL, 

Annex V, Public Law 100-220 (101 Statute 1458), prohibits the disposal of plastics at sea or in coastal 

waters. 

Pollution of marine waters is another potentially adverse impact to sea turtles in the Gulf of Mexico. 

Since sea turtle habitat in the Gulf of Mexico includes both inshore and offshore areas, sea turtles are 

likely to encounter spills. The probability that a sea turtle is exposed to hydrocarbons resulting from a 

spill extends well after the oil spill has dispersed from its initial aggregated mass. Oil spills can adversely 

affect sea turtles by toxic ingestion or blockage of the digestive tract, inflammatory dermatitis, ventilatory 

disturbance, disruption or failure of salt gland function, red blood cell disturbances, immune responses, 

and displacement from important habitat areas (Witham, 1978; Vargo et al., 1986; Lutz and Lutcavage, 

1989; Lutcavage et al., 1995). Although disturbances may be temporary, turtles chronically ingesting oil 

may experience organ degeneration. Exposure to oil may be fatal, particularly to juvenile and hatchling 

sea turtles. 

Oil-spill-response activities, such as vehicular and vessel traffic in coastal areas of seagrass beds and 

live-bottom communities, can alter sea turtle habitat and displace sea turtles from these areas. The 

strategy for cleanup operations should vary, depending on season, recognizing that disturbance to nests 

may be more detrimental than oil (Fritts and McGehee, 1982). As mandated by the OPA (Chapter 1.3), 

these areas are expected to receive individual consideration during oil-spill cleanup. 

Human consumption of turtle eggs, meat, or by-products occurs worldwide and depletes turtle 

populations (Cato et al., 1978; Mack and Duplaix, 1979). Commercial harvests are no longer permitted 

within continental U.S. waters, and Mexico has banned such activity (Aridjis, 1990). Since sea turtles are 

highly migratory species, the taking of turtles in subsistence and commercial sea turtle fisheries is still a 

concern. 

Tropical storms and hurricanes are a normal occurrence in the Gulf of Mexico and along the coast. 

Generally, the impacts have been localized and infrequent. However, in the last two years the Gulf of 

Mexico has been extremely hard hit by very powerful hurricanes. Few areas of the coast have not 

suffered some damage in 2004-2005, and activities in the Gulf of Mexico have also been severely 

impacted. Hurricanes have caused damage to all five of the Gulf Coast States and to structures and 

operations both offshore and onshore. The actual impacts of these storms on the animals in the Gulf of 

Mexico, and the listed species and critical habitat in particular, 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, 
Environmental and Socioeconomic Consequences 4-107 

are known to have occurred and will impact sea turtles that would have used those areas for nesting 

beaches. Oil, gas, and chemical spills from damaged and destroyed structures and vessels may have 

impacted sea turtles (although no large oil spills were reported, several lesser spills are known to have 

occurred). Increased trash and debris in both offshore and inshore habitats affected sea turtles. Increased 

runoff and silting from wind and rain may have affected water quality. 

Recent Consultation 

The proposed lease sales will not appreciably reduce the likelihood of the survival and recovery in the 

wild of any of the five species of sea turtles considered in the Biological Opinion. The NMFS concluded 

that the anticipated reduction in numbers by take of sea turtles by vessel strikes and oil spills associated 

with the CPA and WPA proposed actions, when evaluated in the context of each species’ status, the 

environmental baseline, and the cumulative effects, are not expected to jeopardize the continued existence 

of loggerhead, leatherback, Kemp’s ridley, green, or hawksbill sea turtles. 

Summary and Conclusion 

Activities considered under the cumulative scenario may harm sea turtles and their habitats. Those 

activities include structure installation, dredge operations, beach lighting, power plant entrainment, water 

quality and habitat degradation, seismic surveys, explosive structure removals, vessel traffic and 

collisions, OCS-related marine debris, oil spills, oil-spill-response activities, pollution, commercial and 

recreational fishing, human consumption, and natural catastrophes. It is expected that deaths as a result of 

structure removals would rarely occur because of mitigation measures. The presence of, and noise 

produced by, service vessels and by the construction, operation, and removal of drill rigs may cause 

physiological stress and make animals more susceptible to disease or predation, as well as disrupt normal 

activities. Sea turtles could be killed or injured by chance collision with service vessels or by eating 

marine debris, particularly plastic items, lost from OCS structures and service vessels. Contaminants in 

waste discharges and drilling muds might indirectly affect sea turtles through food-chain 

biomagnification. Oil spills and oil-spill-response activities are potential threats that may be expected to 

cause turtle deaths. Contact with, and consumption of oil and oil-contaminated prey, may seriously 

impact turtles. The majority of OCS activities are estimated to be sublethal (behavioral effects and 

nonfatal exposure to intake of OCS-related contaminants or debris). Chronic sublethal effects (e.g., 

stress) resulting in persistent physiological or behavioral changes and/or avoidance of impacted areas 

could cause declines in survival or productivity, resulting in either acute or gradual population declines. 

However, mitigations currently in place have, and will continue to, minimize sea turtle impacts. Natural 

phenomenon, such as tropical storms and hurricanes, are impossible to predict, but they will occur in the 

Gulf of Mexico. Generally, the offshore species and the offshore habitat are not expected to be severely 

affected in the long-term. However, species that occupy more nearshore habitats and those that use 

nearshore habitats (sea turtle nesting) may suffer more long-term impacts. Effects of the incremental 

contribution are similar in the 181 South Area as they are to the rest of the sale area. These numerous, 

cumulative impacts to sea turtles are not expected to be significant, especially due to mitigations currently 

in place. 

4.1.8. Alabama, Choctawhatchee, St. Andrew, and Perdido Key Beach Mice 

The MMS has reexamined the analysis for beach mice presented in the Multisale EIS, based on the 

additional information presented below and the addition of the 181 South Area to the proposed CPA sale 

area. No significant 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, impacts associated with 

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 a 

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

presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. An impact from consumption of beach trash and debris associated 

with a CPA proposed action on the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice 
4-108 Central and Western Gulf of Mexico Multisale Supplemental EIS

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. 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 a CPA 

proposed action to the cumulative impacts is negligible. Because beach mice are located such a far 

distance from the proposed WPA sale area, the impacts of a WPA proposed action have not been 

analyzed. 

4.1.8.1. Description of the Affected Environment 

A detailed description of habitats, diet, reproduction, and tropical storm impacts on beach mice can be 

found in Chapter 3.2.5 of the Multisale EIS. The following is a summary of the information presented in 

the Multisale EIS, which incorporates new information found since the publication of the Multisale EIS. 

Because the 181 South Area is over 180 mi (290 km) from the nearest beach mouse habitat, the area is not 

applicable to this discussion. 

Of the Gulf Coast subspecies of field mice (Peromyscus polionotus), 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, and the 

Perdido Key, St. Andrew, and Choctawhatchee subspecies in Florida (USDOI, FWS, 1987). Populations 

have fallen to levels approaching extinction. The Alabama, Perdido Key, and Choctawhatchee beach 

mice were listed as endangered in the 1980’s. The St. Andrew beach mouse was not listed as endangered 

until 1998; it 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 52 km (32.3 mi) of coastal dune habitat are now occupied by the four listed subspecies (1/3 

of the 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 (e.g., coastal development and associated human activities, military activities, coastal 

erosion, and weather). The FWS (USDOI, FWS, 2006) cites habitat loss as the primary cause for declines 

in populations of beach mice. The development of beachfront real estate along coastal areas and the 

catastrophic alteration by hurricanes are the primary contributors to loss of habitat. The destruction of 

Gulf Coast sand dune ecosystems for commercial and residential development has destroyed about 

60 percent of original beach mouse habitat (Holliman, 1983). Studies indicate that this continues to be a 

problem (Douglass et al., 1999; South Alabama Regional Planning Commission, 2001). 

Habitat reduction and fragmentation have affected the ability of beach mice to quickly recover 

following tropical storms. The combinations of habitat loss to beachfront development, isolation of 

remaining habitat blocks and beach mouse populations, and destruction of remaining habitat by 

hurricanes has increased the threat of extinction for the Alabama, Choctawhatchee, St. Andrew, and 

Perdido Key beach mice within the last 20-30 years (USDOI, FWS, 2006). 

Beach mice are restricted to the coastal barrier sand dunes along the Gulf. The inland extent of beach 

mouse habitat may vary depending on the configuration of the sand dune system and the vegetation 

present. Optimal overall beach mouse habitat is currently thought to be comprised of a heterogeneous 

mix of interconnected habitats including primary dunes, secondary dunes, scrub dunes, and interdunal 

areas. 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). Management 

practices designed to promote recovery of dune habitat, increase food sources, and enhance habitat 

heterogeneity may aid in recovery of beach mouse populations. In wild populations, beach mice have an 

average life span of about 9 months. 

Hurricanes are a natural environmental phenomenon affecting the Gulf Coast, and beach mice have 

evolved and persisted in coastal dune habitats since the Pleistocene. 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. While Alabama beach mouse numbers and habitat quality in the frontal dunes ebb and flow in 
Environmental and Socioeconomic Consequences 4-109 

response to tropical storms, the higher elevation scrub habitat is important to mouse conservation as a 

more stable environment during and after storm events. 

A search was conducted for new information published since completion of the Multisale EIS. A 

search of Internet bibliographic databases (Google, 2007a and b; OCLC FirstSearch, 2007), as well as 

personal interviews with subject matter experts in other agencies was conducted to determine the 

availability of recent information. Leblanc (personal communication, 2007) revealed that a population 

genetics study on the Alabama beach mouse was published in 2007 (Tenaglia et al., 2007). Adult males 

were often trapped with adult females, probably their mates in this monogamous species. These pairs 

were more distantly related than expected, probably because kin recognition allowed selection of 

unrelated mates to avoid inbreeding depression, reduced fitness of a population as a result of breeding of 

related individuals. 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 

adult-subadult familial bonds before final adult dispersal, which itself is a short distance. Consequences 

for inbreeding impacts remain to be investigated. Sneckenberger (personal communication, 2007) 

reported no new articles on beach mice in Florida. 

4.1.8.2. Impacts of Routine Events 

A detailed description of routine impacts on beach mice associated with a CPA proposed action can 

be found in Chapter 4.2.2.1.7 in the Multisale EIS. 

This chapter discusses the possible effects of routine activities associated with a CPA proposed action 

on the Alabama, Choctawhatchee, St. Andrew, and Perdido Key beach mice, which are designated as 

protected species under the ESA (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. 

CPA Proposed Action Analysis 

The major routine impact-producing factors associated with a CPA 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 or may become entangled in 

debris. A proposed action is expected to contribute negligible marine debris or disruption to beach mice 

areas. Unless properly regulated, personnel removing marine debris may temporarily scare away beach 

mice, destroy their food resources such as sea oats, or trample the tops of their burrows. Due to the 

extended distance from shore, impacts associated with activities occurring in the 181 South Area are not 

expected to impact beach mice. 

Summary and Conclusion 

An impact from a CPA proposed action on the Alabama, Choctawhatchee, St. Andrew, and Perdido 

Key beach mice is possible but unlikely. An impact may result from the consumption of beach trash and 

debris. A proposed action would deposit only a small portion of the total debris that would reach the 

habitat. Unless adequately regulated, efforts undertaken for the removal of marine debris may 

temporarily scare away beach mice, destroy their food resources, or collapse the tops of their burrows. 

4.1.8.3. Impacts of Accidental Events 

A detailed description of accidental impacts upon beach mice can be found in Chapter 4.4.7 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

Direct contact with spilled oil can cause skin and eye irritation and subsequent infection for 

endangered beach mice. The fur will be matted and lose its insulation against heat and cold. Sweat 

glands, ear tissues, and throat tissues may be irritated or infected. The disruption of sight and hearing 

increases vulnerability to predators. Other direct toxic effects may include asphyxiation from inhalation 

of fumes. Direct contact may result from oil ingestion or food contamination. Indirect impacts from oil 

spills would include reduction of food supply, destruction of habitat, and fouling of nests. Recovery of 
4-110 Central and Western Gulf of Mexico Multisale Supplemental EIS

habitat from hurricanes involves a vital link between mouse food supply (involving seeds of dunestabilizing 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, and loss may result in extinction of the beach mouse after later 

serious storms or hurricanes or further beachfront development disrupt 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 without regulation. 

There is no definitive information on the persistence of oil in the event that a spill was to contact 

beach mouse habitat. In Prince William Sound, Alaska, after the Exxon Valdez spill in 1989, buried oil 

has been measured in the intertidal zone of beaches, but no effort has been made to search for residual 

buried oil above high tide. Similarly, NRC (2003) makes no mention of studies of oil left above high tide 

after a spill. Regardless of the potential for persistence of oil in beach mouse habitat, a slick cannot wash 

over the foredunes unless carried by a heavy storm swell. 

CPA Proposed Action Analysis 

The ranges of the four endangered subspecies of beach mice are shown in Figure 3-9 as revised by 

FWS for this SEIS. The oiling of beach mice could result in extinction if it occurs on a large scale (over 

the entire range of one of the subspecies), 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 major spill. 

The 181 South Area is over 180 mi (290 km) from the nearest beach mouse habitat. Of spills 

originating from the 181 South Area, only spills >1,000 bbl could persist long enough to possibly contact 

beach mouse habitat. As explained in Chapter 3.2.1, the incremental increase in oil production from the 

addition of the 181 South Area is not expected to result in an overall increase in the numbers of oil spills 

≥1,000 bbl likely to occur as a result of a CPA proposed action. For a CPA proposed action, including 

the 181 South Area, 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 a proposed action. Spills in coastal waters could occur 

at storage or processing facilities, and service bases supporting the proposed action; however, these 

facilities would not be located near beach mouse habitat. 

Summary and Conclusion 

The oiling of beach mice could result in extinction if it occurs on a large scale (over the entire range 

of one of the subspecies). Oil-spill-response 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 actions are not expected to contact beach mice or their habitats. The addition of the 181 

South Area would not increase the risk of impacts from accidental events on beach mouse habitat. 

The MMS has reexamined the analysis for impacts to beach mice presented in the Multisale EIS, 

based on the additional information presented above. No significant new information was found that 

would alter the overall conclusion that impacts on beach mice from accidental impacts associated with a 

CPA proposed action would be minimal 

4.1.8.4. Cumulative Impacts 

A detailed description of cumulative impacts upon beach mice can be found in Chapter 4.5.7 of the 

Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

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 proposed actionrelated 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 
Environmental and Socioeconomic Consequences 4-111 

beach mice populations to unsustainable levels. The expected incremental contribution of a CPA 

proposed action to the cumulative impacts is negligible. 

A search was conducted for new information published since completion of the Multisale EIS. A 

search of Internet bibliographic databases (Google, 2007a and b; OCLC FirstSearch, 2007) as well as 

personal interviews with subject matter experts in other agencies was conducted to determine availability 

of recent information. Sneckenberger (personal communication, 2007) reported no new articles on beach 

mice in Florida. 

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 to 

34.9 + 1.1 percent with the translocation of mice. Total loss of private land as suitable habitat raises the 

risk further to 46.8 + 1.1 percent, but only 40.8 + 1.1 percent with the translocation of mice. Hanski 

(1999) warns that simpler metapopulation models, such as that done for the Alabama beach mouse, are 

more reliable than PVHA models because predictions of PHVA and Population Viability Analysis (PVA) 

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 a 

proposed action in the Multisale EIS upon the Alabama, Choctawhatchee, St. Andrew, and Perdido Key 

beach mice. The analysis and potential impacts detailed in the Multisale EIS apply for the SEIS. Due to 

the extended distance from shore, the incremental impacts associated with activities occurring in the 181 

South Area are not expected to impact beach mice. 

Summary and Conclusion 

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. This conclusion is supported by a recent population model of the Alabama beach 

mouse. Impacts from a CPA proposed action could come from trash and debris and effort to remove 

them, as well as oil spills and cleanup operations. The expected incremental contribution of a CPA 

proposed action to the cumulative impacts is negligible. No additional incremental impacts on beach 

mice associated with activities occurring in the 181 South Area are expected. 

4.1.9. Coastal and Marine Birds 

The MMS has reexamined the analysis for coastal and marine birds presented in the Multisale EIS, 

based on the additional information presented below and the addition of the 181 South Area to the 

proposed CPA sale area. No significant new information was found that would alter the impact 

conclusion for coastal and marine birds presented in the Multisale EIS. Use of the 181 South Area by 

breeding or nonbreeding seabirds is unknown; however, the 181 South Area is located nearly 130 mi 

(209 km) from the nearest coast and is projected to result in a relatively minor amount of additional 

activity. Therefore, no additional impacts on coastal and marine birds are projected as a result of the 
4-112 Central and Western Gulf of Mexico Multisale Supplemental EIS

inclusion of the 181 South Area. Disturbance to seabirds in the 181 South Area would be similar to 

disturbance to the birds in the other offshore waters of the proposed lease sale areas. Endangered or 

threatened bird species (i.e., piping plover, whooping crane, and brown pelican) that inhabit or frequent 

the north-central and western Gulf of Mexico coastal areas are not expected to occur in the 181 South 

Area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. The majority of impacts resulting from routine activities 

associated with a CPA or WPA proposed action on endangered/threatened and nonendangered/

nonthreatened coastal and marine birds are expected to be sublethal. These impacts include behavioral 

effects, exposure to or intake of OCS-related contaminants or discarded debris, temporary disturbances, 

and displacement of localized groups from impacted habitats. Impacts from potential oil spills associated 

with a 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 a CPA or WPA 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. 

4.1.9.1. Description of the Affected Environment 

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, which incorporates new 

information found since the publication of the Multisale EIS. 

The Gulf of Mexico is populated by both resident and migratory species of coastal and marine birds. 

They are herein separated into six major groups: diving birds, gulls/terns, shorebirds, passerines, wading 

birds, and waterfowl. Many species are mostly pelagic and, therefore, are rarely sighted nearshore. 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 nesting 

colony sites and total number of nesting coastal and marine birds (Martin and Lester, 1991; Martin, 

1991). Fidelity to these nesting sites varies from year to year along the Gulf Coast. Site abandonment 

along the northern Gulf Coast has often been attributed to habitat alteration and excessive human 

disturbance (Martin and Lester, 1991). 

Diving birds are a diverse group. There are three main groups of diving birds: cormorants and 

anhingas (Pelecaniformes), loons (Gaviiformes), and grebes (Podicipediformes). Nesting diving birds in 

the Gulf include cormorants. Gulls, terns, noddies, jaegers, and black skimmers make up the gull/tern 

group. Of these, colonies of laughing gulls, eight species of terns, and black skimmers nest along the 

Gulf Coast (Martin and Lester, 1991; Pashley, 1991). Use of the 181 South Area by breeding or 

nonbreeding seabirds is unknown. 

The small size of terns is a factor in their vulnerability to OCS-related activities and their general 

ecology. Terns are usually smaller than gulls, and tern refugees from colonies destroyed by humans may 

not be able to recolonize next to large gull colonies that are restricted to the same marsh and other such 

coastal habitats. Predation on tern eggs and chicks by the gulls is then often massive (Anderson and 

Devlin, 1999). Terns are smaller than other fish-eating seabirds and, hence, may be excluded from 

optimum feeding grounds by interference competition including food stealing (kleptoparasitisim) 

(Ballance et al., 1997). However, for seabirds with similar wing feather patterns, smaller birds like terns 

have more flight power and can fly farther (e.g., maximum foraging radius for breeding sooty terns is 
Environmental and Socioeconomic Consequences 4-113 

about 460 mi or 740 km; Flint, 1991) to search successfully for schools of prey that are suboptimal 

because they take longer to locate (Ballance et al., 1997). 

Shorebirds are those members of the order Charadriiformes 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, snipes, and allies) (Hayman et al., 1986). 

All of the shorebirds are solitary nesters. 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 (Terres, 1991). Both spring and fall migrations 

take place in a series of “hops” to staging areas where birds spend time feeding heavily to store up fat for 

the sustained flight to the next staging area; many coastal habitats along the Gulf of Mexico are critical 

for such purposes. Along the central Gulf Coast, 44 species of shorebirds have been recorded; only 6 nest 

in the area, and the remaining are wintering residents and/or staging migrants (Pashley, 1991). 

Many of the overwintering shorebird species remain within specific areas throughout the season and 

exhibit between-year wintering site tenacity, at least when not disturbed by humans. Birds are 

aerodynamically constrained to use more energy to initiate movement (take off) than most other 

vertebrates (Attenborough and Salisbury, 1998). They may prefer to stay in one place. These species 

may be especially susceptible to localized impacts resulting in habitat loss or degradation unless they 

move to more favorable habitats when disturbed by man. The diversity of feeding methods may increase 

the ability of shorebirds to find new foraging habitat if human activities force them to leave their usual 

habitat. 

Passerine birds mostly migrate across the Gulf of Mexico each fall and spring and are protected, 

along with other migrants, under the Migratory Bird Treaty Act. A recent study of platforms as possible 

resting sites for birds crossing the Gulf was completed and is summarized in Chapter 3.2.6.1 of the 

Multisale EIS. The 181 South Area is farther offshore than the area covered by that platform study. 

Therefore, the potential effect of platforms in the 181 South Area on trans-Gulf migrants is unknown. 

Collectively, the following families of wading birds have representatives in the northern Gulf that are 

adapted to shallow water: Ardeidae (herons and egrets), Ciconiidae (storks), Threskiornithidae (ibises 

and spoonbills), and Gruidae (cranes). Common wading birds in the northern Gulf of Mexico, as well as 

their main features, are listed in Table 3-8 of the Multisale EIS. Seventeen species of wading birds in the 

Order Ciconiiformes are currently known to nest in the U.S., 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. Great egrets are the most widespread nesting species in the central Gulf 

Coast 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, gallinules, and coots) have compact bodies; 

therefore, they are labeled marsh birds and not wading birds. They are also 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; National Geographic Society, 1983; Ripley and Beehler, 1985). 

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.. Common waterfowl 

in the northern Gulf of Mexico, as well as their main features, are also listed in Table 3-8 of the Multisale 

EIS. Many species usually migrate from wintering grounds along the Gulf Coast to summer nesting 

grounds in the north. Waterfowl migration pathways have traditionally been divided into four parallel 

north-south paths, or “flyways,” across the North American continent. The Gulf Coast serves as the 

southern terminus of both Central (Texas) and Mississippi (Louisiana, Mississippi, and Alabama) 

flyways. Waterfowl are highly social and possess a diverse array of feeding adaptations related to their 

habitat (Johnsgard, 1975). 

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, which incorporates new information found since the publication of the Multisale EIS. 
4-114 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 threatened and 

endangered species (USDOI, FWS, 2007b). 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). 

The following coastal and marine bird species that inhabit or frequent the north-central and western 

Gulf of Mexico coastal areas are recognized by FWS as either endangered or threatened: piping plover, 

whooping crane, and brown pelican. None of them are expected to occur in the 181 South Area. 

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 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, and it begins arriving on the wintering grounds in July and 

keeps arriving through September. 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. Critical wintering habitat includes the land between mean lower low water 

and any densely vegetated habitat (not used by the piping plover). 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). In late February, piping plovers begin leaving the wintering 

grounds to migrate back to their breeding sites. Northward migration peaks in late March, and by late 

May most birds have left the wintering grounds. Vegetation imposes an extreme threat of predators on 

breeding adults. On the northern breeding grounds, river alteration and reservoir creation cause high 

water flow where birds once relied on exposed sand bars to breed. However, diversion of peak flows in 

northern nesting habitat is also harmful. The result is the encroachment of vegetation that is usually kept 

under control by scour during high river flows. The migration of the piping plover is poorly understood. 

This species remains in a precarious state given its low population numbers, sparse distribution, and 

continued threats to habitat throughout its range. About 2,299 birds were located on the U.S. wintering 

grounds during the 2001 census (Haig and Ferland, 2002). Although the results of the 2006 International 

Census have not yet been published, during that census, 226 piping plovers were counted at 26 sites along 

~125 mi (200 km) of shoreline in Louisiana (Smith, personal communication, 2007). The final rule on 

the critical habitat of 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 in Mississippi, 7 in Louisiana, and 37 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). 

Whooping Crane 

The whooping crane (Grus americana) is an omnivorous, wading bird. Whooping cranes currently 

exist in three wild populations and at five captive locations (USDOI, FWS, 1994). All of the populations 

are listed as endangered. The only self-sustaining wild population nests in the Northwest Territories and 

adjacent areas of Alberta, Canada, primarily within the boundaries of Wood Buffalo National Park. 

These birds winter in coastal marshes and estuarine habitats along the Gulf Coast in the Aransas National 

Wildlife Refuge in Texas, and they represent the majority of the world’s population of free-ranging 

whooping cranes. Another wild flock was created with the transfer of wild whooping crane eggs from 

nests in the Wood Buffalo National Park to be reared by wild sandhill cranes in an effort to establish a 

migratory Rocky Mountains Population (USDOI, FWS, 1994). This population summers in Idaho, 
Environmental and Socioeconomic Consequences 4-115 

western Wyoming, and southwestern Montana, and it winters in the middle Rio Grande Valley, New 

Mexico. The third wild population is the first step in an effort to establish a nonmigratory population in 

Florida (USDOI, FWS, 1994). The 2007 wild populations were estimated to total 355; the captive 

population contained 148 birds (Stehn, 2007).Brown Pelican 

The population of brown pelicans and their habitat in Alabama, Florida, Georgia, North and South 

Carolina, and points northward along the Atlantic Coast were removed from the endangered species list in 

1985; however, within the remainder of the range, which includes coastal areas of Texas, Louisiana, and 

Mississippi, where populations are not secure, the brown pelican remains listed as endangered (Federal 

Register, 1985). The brown pelican (Pelicanus occidentalis) is one of two pelican species in North 

America. It feeds entirely upon fishes captured in coastal waters. Organochlorine pesticide pollution 

apparently contributed to the endangerment of the brown pelican. Organochlorines like DDT accumulate 

up the food web and reach their highest concentrations in predators such as the brown pelican. The 

pesticides interfere with calcium metabolism, causing reduced calcification of egg shells, and potentially 

allowing the eggs to be crushed under the weight of an incubating parent. In recent years, there has been 

a marked increase in brown pelican populations within the former range of the species. In 2004, 16,501 

nesting pairs produced an all-time high of 39,021 fledglings. Production decreased 35.2 percent in 2005 

to 25,289 fledglings as a result of an oil spill at the West Breton Island colony caused by Tropical Storm 

Arlene and by the cumulative effects of Hurricanes Cindy, Dennis, Emily, Katrina, and Rita. Ninety-five 

percent of production occurred west of the Mississippi River. Young brown pelicans there had reached 

flight stage at the time of Hurricane Katrina with no direct mortality at colonies. Conversely, brown 

pelicans incubating eggs and caring for 5- to 6-week-old young east of the Mississippi River when 

Hurricane Katrina struck were impacted as eggs and young were washed away. Colonies there were 

repeatedly flooded by Tropical Storm Arlene and the hurricanes, causing fledgling mortality. In addition, 

Hurricane Ivan in 2004 and Hurricanes Katrina and Rita in 2005 caused catastrophic destruction of barrier 

islands and brown pelican nesting colonies. Hurricane Katrina reduced the size of the Chandeleur Islands 

by 90 percent and completely washed away West Breton Island, Mitchell Island, and Grassy Island 

(HuntnFish.com, 2007). Other major causes of the decline of the brown pelican are colony site erosion, 

disease, and human disturbance (Boggs, written communication, 2007). The Louisiana Dept. of Wildlife 

and Fisheries submitted a request in March 1994 to FWS to officially remove the eastern brown pelican 

from the endangered species list in Louisiana (Louisiana Dept. of Wildlife and Fisheries, 1994). 

Effects of Hurricanes Katrina and Rita 

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). A detailed 

summary of impacts of the hurricanes on birds is provided in Chapter 3.2.6 of the Multisale EIS. 

New Information 

A search was conducted for new information published since completion of the Multisale EIS. A 

search of Internet bibliographic databases, as well as personal interviews with authors of references used 

in the Multisale EIS, was conducted to determine the availability of recent information since publication 

of the Multisale EIS. The Internet databases examined included Google (2007a and b) and OCLC 

FirstSearch (2007). No new information on the description of bird resources was found from these 

information sources. 

4.1.9.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on coastal and marine birds can be found in Chapters 4.2.2.1.8 and Chapter 4.2.1.1.7 of 

the Multisale EIS, respectively. The following is a summary of the information presented in the Multisale 

EIS, which incorporates new information found since the publication of the Multisale EIS. 
4-116 Central and Western Gulf of Mexico Multisale Supplemental EIS

This section discusses the possible effects of routine activities on coastal and marine birds of the Gulf 

of Mexico and its contiguous waters and wetlands. Federally listed endangered or threatened bird species 

are included in this discussion with non-listed bird 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 noise, air emissions, degradation of water 

quality, habitat degradation, discarded trash and debris from service-vessels and OCS structures, and 

structure lighting and presence. Any effects on birds are especially grave for intensively managed 

populations. For example, endangered and threatened species may be harmed by any impact on viable 

reproductive population size or disturbance of a few key habitat factors. 

The degree of disturbance of air or vessel traffic to birds varies. Behavior may temporarily halt or 

birds may be permanently displaced. Breeding may be interrupted without mortality, but it is ecologically 

vital to birds even so. Breeding birds become habituated to noise and the presence of humans (Nisbet, 

2000). Aircraft may be forced to fly below legal minimum altitudes in inclement weather, possibly 

disturbing birds. 

Air pollution may cause physiological impairment and provoke other diseases. Effects 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 stresses and shifts in food supplies. Acid deposition affects the forest 

forging habitat of birds. Air emissions may cause changes in bird distribution and abundance, but the 

emissions must be diagnostically separated from other possible factors (e.g., weather and food supplies) 

that could have the same effect. 

The impacts of discharges into water vary from short term to long term and from sublethal to lethal. 

Impacts may be from ingestion or contact (direct) or from the destruction of food supplies (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 experience chronic, sublethal 

impacts. 

Habitat can be described as the physical environment and as the plant substrates used by a bird. Birds 

select their habitat at various times in their life histories according to their needs. The greatest negative 

impact to coastal and marine birds is the loss or degradation of preferred or critical habitat and, for a 

threatened or endangered species, this may result in global extinction. This discussion applies to both 

federally listed endangered/threatened bird species and non-listed species, since the effects are the same 

or very similar. The extent of bird displacement resulting from habitat loss is highly variable between 

different species, based upon specific habitat requirements, which for most species are not completely 

known. As displaced birds move to undisturbed areas of similar habitat, their presence may augment 

habitat utilization pressure on these selected areas as a result of intra- and interspecific competition for 

space or food. 

Pipeline landfalls and terminals, and other onshore OCS-related construction, can destroy wetland 

bird habitat and can displace birds. Seabird nesting colonies are especially 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 birds of all types, including migrants, wintering birds, 

and breeding birds. 

Seabirds ingest plastic particles 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 last a lifetime 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 survival rates and breeding success. As a result of stress from the consumption of 
Environmental and Socioeconomic Consequences 4-117 

debris, individuals may weaken, facilitating infection and disease; migratory species may then not have 

the strength to reach their destination. 

CPA 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 a 

CPA proposed action would occur over the life of a 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 the USCG for reduced vessel 

speeds within these inland areas. It is projected that 119,000-241,000 service-vessel round trips related to 

a CPA proposed action would occur over the life of a proposed action; this is a rate of 2,925-6,025 

service-vessels trips annually. 

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 non-listed species since the effects are the same or very 

similar. Disturbance to seabirds in the 181 South Area will be similar to the disturbance to birds in the 

other offshore waters of a proposed action. 

The FAA 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/or critical habitat for 

feeding, resting (or staging), and nesting birds. 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 occur. 

Routine presence and low speeds of service vessels within inland and coastal waterways would diminish 

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 sulfur dioxide, SO2) emissions from hydrocarbon combustion from OCS-related 

activities are of concern in relation to birds. 

The indirect effects of air emissions on wildlife include food web contamination and habitat 

degradation, as well as adverse synergistic effects of air emissions with natural and other manmade 

stresses. Air pollutants may cause a change in the distribution of certain bird species (e.g., Newman, 

1977; Llacuna et al., 1993). 

Chapter 4.1.1.2 provides an analysis of the routine effects of a CPA proposed action on air quality. 

Emissions of pollutants into the atmosphere from the activities associated with a 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 and Research, 1998). 

Chapter 4.1.2 provides an analysis of the effects of a CPA proposed action on water quality. This 

discussion applies to both federally listed endangered/threatened bird species and non-listed species since 

the effects are the same or very similar. Expected degradation of coastal and estuarine water quality 

resulting from 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. 

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. Disturbance to 

seabirds in the 181 South Area will be similar to disturbance to the birds in the other offshore areas of a 

proposed action. These impacts could also be both direct and indirect. Many seabirds feed and nest in 
4-118 Central and Western Gulf of Mexico Multisale Supplemental EIS

the Gulf; therefore, water quality may also affect breeding success (measured as the ratio of fledged birds 

per nest to hatched birds per nest). 

The analysis of the potential impacts to coastal environments (Chapter 4.1.3) concludes that a 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. Initial impacts are locally significant and largely limited to where 

OCS-related canals and channels pass through wetlands. For a CPA proposed action, 0-1 new pipeline 

landfalls (Chapter 4.1.2.1.7 of the Multisale EIS) and 0-1 new gas processing plants (Chapter 4.1.2.1.4.2 

of the Multisale EIS) are projected. 

Coastal and marine birds are susceptible to entanglement in floating, submerged, and beached marine 

debris; specifically in plastics discarded from both offshore sources and land-derived litter and waste 

disposal (Heneman and the Center for Environmental Education, 1988). This discussion applies to both 

federally listed endangered/threatened bird species and non-listed species since the effects are the same or 

very similar. It is expected that coastal and marine birds will seldom become entangled in or ingest OCSrelated trash and debris as a result of MMS prohibitions on the disposal of equipment, containers, and 

other materials into offshore waters by lessees (30 CFR 250.40). In addition, MARPOL, Annex V, Public 

Law 100-220 (101 Statute 1458), which prohibits the disposal of any plastics, garbage, and other solid 

wastes at sea or in coastal waters, went into effect January 1, 1989, and is enforced by the USCG. 

Every 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. This discussion applies to both federally listed 

endangered/threatened bird species and non-listed 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.” Circulations increase the risks for 

birds to collide with platform structures and with each other. 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 4.2.2.1.8 of the 

Multisale EIS. It is projected that 28-40 platforms are projected to be installed as a result of a CPA 

proposed action. Nocturnal circulation on these platforms is 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 observed on the platforms by 

Russell (2005). The advantage of stopovers is expected to make up for any losses to bird populations 

from the nocturnal circulations. 

WPA 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 3-3). It is projected that 400,000-900,000 helicopter operations related to a WPA 

proposed action would occur over the life of a proposed action; this is a rate of 10,000-22,500 annual 

helicopter operations. Service vessels would use selected nearshore and coastal (inland) navigation 

waterways, or corridors, and adhere to protocol set forth by the USCG for reduced vessel speeds within 

these inland areas. It is projected that 94,000-155,000 service-vessel round trips related to a WPA 

proposed action would occur in the life of a proposed action; this is a rate of 2,350-3,875 service-vessels 

trips annually. 

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 
Environmental and Socioeconomic Consequences 4-119 

listed endangered/threatened bird species and non-listed species since the effects are the same or very 

similar. 

The FAA 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/or critical habitat for 

feeding, resting (or staging), and nesting birds. 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 occur. 

Routine presence and low speeds of service vessels within inland and coastal waterways would diminish 

the effects of disturbance from service vessels on nearshore and inland populations of coastal and marine 

birds. 

Contamination of wildlife by air emissions can occur in three ways: inhalation, absorption, and 

ingestion. Inhalation is the most common mode of contamination for birds (Newman, 1980). Levels of 

sulfur oxide (mainly SO2) emissions from hydrocarbon combustion from OCS-related activities are of 

concern in relation to birds. 

The indirect effects of air emissions on wildlife include food web contamination and habitat 

degradation, as well as adverse synergistic effects of air emissions with natural and other manmade 

stresses. Air pollutants may cause a change in the distribution of certain bird species (e.g., Newman, 

1977; Llacuna et al., 1993). 

Chapter 4.1.1.2 provides an analysis of the routine effects of a WPA proposed action on air quality. 

Emissions of pollutants into the atmosphere from the activities associated with a 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 and Research, 1998). 

Chapter 4.1.2 provides an analysis of the effects of a WPA proposed action on water quality. This 

discussion applies to both federally listed endangered/threatened bird species and non-listed 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. 

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. Disturbance to 

seabirds in the 181 South Area will be similar to disturbance to the birds in the other offshore areas of the 

proposed action. 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). 

The analysis of the potential impacts to coastal environments (Chapter 4.1.3) concludes that a WPA 

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. Initial impacts are locally significant and largely limited to where 

OCS-related canals and channels pass through wetlands. For a WPA proposed action, 0-1 new pipeline 

landfalls (Chapter 4.1.2.1.7 of the Multisale EIS) and 0-1 new gas processing plants (Chapter 4.1.2.1.4.2 

of the Multisale EIS) are projected. 

Coastal and marine birds are susceptible to entanglement in floating, submerged, and beached marine 

debris; specifically in plastics discarded from both offshore sources and land-derived litter and waste 

disposal (Heneman and the Center for Environmental Education, 1988). This discussion applies to both 

federally listed endangered/threatened bird species and non-listed species since the effects are the same or 

very similar. It is expected that coastal and marine birds will seldom become entangled in or ingest OCSrelated trash and debris as a result of MMS prohibitions on the disposal of equipment, containers, and 

other materials into offshore waters by lessees (30 CFR 250.40). In addition, MARPOL, Annex V, Public 
4-120 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 the USCG. 

Every 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. This discussion applies to both federally listed 

endangered/threatened bird species and non-listed 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.” Circulations increase the risks for 

birds to collide with platform structures and with each other. 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 28-41 platforms are projected to be installed as a result of a WPA 

proposed action (Table 3-3). Nocturnal circulation on these platforms is 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 observed on the platforms by 

Russell (2005). The advantage of stopovers is expected to make up for any losses to bird populations 

from the nocturnal circulations. 

Summary and Conclusion 

The majority of effects resulting from a CPA or WPA proposed action on endangered/threatened and 

nonendangered/nonthreatened coastal and marine birds are expected to be sublethal. These effects 

include behavioral effects, exposure to or intake of OCS-related contaminants or discarded debris, 

temporary disturbances, and displacement of localized groups from impacted habitats. Chronic sublethal 

stress, however, is often undetectable in birds. As a result of stress, individuals may weaken, facilitating 

infection and disease; migratory species may then not have the strength to reach their destination. 

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. No significant habitat 

impacts are expected to occur directly from routine activities resulting from a CPA or WPA proposed 

action. Secondary impacts from pipeline and navigation canals to coastal habitats will occur over the 

long-term and may ultimately displace species. Disturbance to seabirds in the 181 South Area will be 

similar to disturbance to the birds in the other offshore waters of a proposed action. 

4.1.9.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts to coastal and marine birds can be found in Chapter 4.4.8 

of the Multisale EIS. The following is a summary of the information presented in the Multisale EIS, 

which incorporates new information found since publication of the Multisale EIS.

This chapter discusses impacts to coastal and marine birds resulting from a CPA or WPA proposed 

action. Impact-producing factors include oil spills and oil-spill cleanup. Impact discussions are 

combined for threatened/endangered birds and nonthreatened/nonendangered birds because impacts of oil 

spills are similar for both.

Oil spills are the greatest potential direct and indirect impact to coastal and marine birds. Birds that 

are heavily oiled are usually killed. 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. Small coastal spills, pipeline spills, and spills from accidents in navigated 
Environmental and Socioeconomic Consequences 4-121 

waterways can contact and affect the different groups of coastal and marine birds, most commonly marsh 

birds, waders, waterfowl, and certain shorebirds. Lightly oiled birds can sustain tissue and organ damage 

from oil ingested during feeding and grooming or from oil that is inhaled. Stress, trauma, and shock 

enhance the effects of exposure and poisoning. Low levels of oil could stress birds by interfering with 

food detection, feeding impulses, predator avoidance, territory definition, homing of migratory species, 

susceptibility to physiological disorders, disease resistance, growth rates, reproduction, and respiration. 

Reproductive success can be affected by the toxins in oil. Indirect effects occur by the fouling of nesting 

habitat and the displacement of individuals, breeding pairs, or populations to less favorable habitats. 

Competition may exclude refugee seabirds from habitats occupied by other seabirds. 

New research, experience, and testing will help the efficacy of the rehabilitation of oiled birds and 

probably improve scare methods that will keep birds sway from an oil slick. Rehabilitation can be 

significant to the survival of threatened and endangered bird species. 

Dispersants used in spill cleanup activity can have toxic effects similar to oil on the reproductive 

success of coastal and marine birds. The air, vehicle, and foot traffic that takes place during shoreline 

cleanup activity can disturb nesting populations and degrade or destroy habitat if not properly regulated. 

A search was conducted for new information published since completion of the Multisale EIS. A 

search of Internet bibliographic databases, as well as personal interviews with authors of references used 

in the Multisale EIS, was conducted to determine the availability of recent information since publication 

of the Multisale EIS. The Internet databases examined included Google Advanced Book Search (2007a), 

Google Advanced Scholar Search (2007b), and OCLC FirstSearch (2007). Authors were contacted and 

interviewed to investigate any recent published data that may be available. 

A literature search found Burger (1997), who reports that exposure to small amounts of oil, may 

weaken birds or decreases their body weight so they go for years without problems until they face a 

severe environmental stress. Then, they have a higher mortality than unexposed birds. Burger (1993) 

notes that spill volume has little or no correlation with bird mortality. However, Wilhelm et al. (2007) 

shows that this is no longer true when spill volume is scaled as the perimeter of the oil slick by putting a 

fractional exponent on spill volume. An estimated 10,000 seabirds were killed in a 1,000-bbl spill from 

the FPSO Terra Nova vessel off the Grand Banks of Newfoundland on November 21, 2002. No birds 

could be counted on the beach because winds blew out to sea, and no seabird data were available from 

before the spill. Even so, birds inside and outside the slick area were counted from a ship at sea while the 

slick was on the water. The density of seabirds in the affected area, wind conditions, wave action, and 

distance to the shore may have more effect than spill volume. Khan and Ryan (1991) note substantial 

mortality in seabirds after attempts at rehabilitation. Sublethal symptoms of contamination were 

numerous and substantial prior to the mortality. Similarly, numerous symptoms were found in dead birds 

on the shore and in birds dying after rehabilitation that were affected by the Prestige oil spill off the coast 

of Spain on November 19, 2002 (Balseiro et al., 2005). Final major impacts to European shags 

(Phalacrocorax aristotelis) from the Prestige spill probably came in 2003 from a decimated food supply 

of fish (Velando et al., 2005). As oil weathered, the exposure of seabirds to oil from the Exxon Valdez

spill shifted from direct oiling to ingestion with food (Hartung, 1995). 

Alonso-Alvarez et al. (2007a and b) used blood chemistry of yellow-legged gulls (Larus michahellis) 

to compare long-term sublethal toxicity of the Prestige oil spill with short-term experimental sublethal 

toxicity in captive birds fed small amounts of fuel oil. Long-term effects were measured about 19 months 

after the spill. Short-term effects were measured in captive birds fed a small amount of fuel oil for 7 days. 

Adults from oiled colonies and fuel-oil-fed experimental birds had higher total polycyclic aromatic 

hydrocarbons (TPAH) and lower levels of three natural metabolites. High levels of the enzymes aspartate 

transaminase (AST) and gamma-glutamate transaminase (GGT) indicate a possible liver problem. Adults 

from oiled colonies had higher levels of the enzyme (AST) than adults from unoiled colonies. The TPAH 

was positively correlated with AST and negatively correlated with body condition. Females from oiled 

colonies showed higher levels of GGT than females from unoiled colonies. In chicks captured 19 months 

after the spill, only hematocrit showed a possible impact (anemia) from the spill. The TPAH in chicks 

was positively correlated with hematocrit (ruling out an anemia problem from TPAH consumed in oiled 

colonies) and GGT (indicating a possible liver problem). Calcium was lower in oil-fed females than in 

control females but the same in oil-fed and control males. Calcium is important for sufficient egg shell 

thickness in breeding females. 
4-122 Central and Western Gulf of Mexico Multisale Supplemental EIS

Parsons (1994) provides the following unique before and after data for impacts of a spill on birds. 

Extensive shoreline and salt marsh were oiled by a January 1990 Exxon spill in the Arthur Kill and Kill 

van Kull estuaries of New York Harbor. Double-crested cormorants had reached their pre-spill 

population growth by 1991. Productivity of herring gulls remained unchanged by the spill. Most heron 

populations increased after the spill. Great black-backed gulls had a loss of abundance. Snowy egrets 

and glossy ibis used salt marsh and mud flat habitat, some of which was oiled. Black-crowned night 

heron and glossy ibis had delayed nesting after the spill and, along with snowy egret, showed lower 

reproductive success after the spill. Egg laying and hatching were generally more successful than chickrearing because of the shortage of food fed to the chicks. Waterfowl were not affected seriously, except 

for a short-term decline in mallards. 

New data does not conflict with data in the Multisale EIS and often is similar to or supports the data 

in the Multisale EIS. 

CPA Proposed Action Analysis 

The addition of the 181 South Area is not expected to change impacts to coastal and marine birds 

from the effects described in Chapter 4.4.8 of the Multisale EIS. As explained in Chapter 3.2.1, the 

incremental increase in oil production from the addition of the 181 South Area is not expected to result in 

an overall increase in the numbers of oil spills ≥1,000 bbl likely to occur as a result of a CPA proposed 

action. Activity that would result from the addition of the 181 South Area would cause a negligible 

increase in the risk of a large spill occurring and contacting coastal bird habitats. For a CPA proposed 

action including the 181 South Area over the life of the proposed action, the probabilities of oil spills 

occurring and contacting coastal bird habitat within 10 days are 17-27 percent for the threatened piping 

plover; <0.5 percent for the endangered whooping crane; 11-17 percent for the brown pelican; 3-4 percent 

for raptors; 20-30 percent for gulls, terns, and charadriid allies; 20-30 percent for shoreline charadriids; 

11-16 percent for diving birds; 15-24 percent for wading birds; and 24-35 percent for waterfowl. All of 

these groups, except for the whooping crane, are widely distributed across the Gulf (Figures 4-22 through 

4-31 in the Multisale EIS); therefore, an oil spill would only affect a small portion of a bird group. Given 

that, the combined probabilities are always less than 36 percent. Small coastal spills, pipeline spills, and 

spills from accidents in navigable waterways can contact and affect the different groups of coastal and 

marine birds, most commonly marsh birds, waders, waterfowl, and certain shorebirds. In the CPA, an 

estimated total of 46-102 coastal spills will occur over a 34-year production period. Impacts on seabirds 

at sea are not part of the analysis, and their seasonal distribution needs to be characterized. Many species 

breed outside the United States, sometimes outside the Northern Hemisphere. The whooping crane has a 

low probability of being impacted by an oil spill because of its limited range. Oil-spill cleanup is not 

expected to affect coastal birds if properly regulated. Impacts on all species are expected to be negligible. 

WPA Proposed Action Analysis 

The probabilities of oil spills occurring and contacting coastal bird habitat within 10 days as the result 

of a proposed action over its 40-year life are 7-11 percent for the threatened piping plover; 1 percent for 

the endangered whooping crane; 8-13 for the brown pelican; 8-13 percent for raptors; 8-14 percent for 

gulls, terns, and charadriid allies; 8-14 percent for shoreline charadriids; 8-13 percent for diving birds; 8-

14 percent for wading birds; and 9-14 percent for waterfowl. All of these groups, except for the 

whooping crane, are widely distributed across the Gulf (Figures 4-22 through 4-31 in the Multisale EIS); 

therefore, an oil spill would only affect a small portion of a bird group. Given that, the combined 

probabilities are always <15 percent. Small coastal spills, pipeline spills, and spills from accidents in 

navigable waterways can contact and affect the different groups of coastal and marine birds, most 

commonly marsh birds, waders, waterfowl, and certain shorebirds. In the WPA, an estimated total of 15-

34 coastal spills will occur over a 34-year production period. Impacts on seabirds at sea are not part of 

the analysis and their seasonal distribution needs to be characterized. Many species breed outside the 

United States, sometimes outside the Northern Hemisphere. Impacts of a WPA proposed action on all 

coastal birds are expected to be negligible. Oil-spill cleanup is not expected to affect coastal birds if 

properly regulated. 
Environmental and Socioeconomic Consequences 4-123 

Summary and Conclusion 

Oil spills have the greatest impact on coastal and marine birds. Small amounts of oil can affect birds, 

and mortality from oil spills is often related to numerous symptoms of toxicity. Data from actual spills 

strongly suggest that impacts on their food supply are delayed after initial impacts from direct oiling. 

Mechanisms of toxic oil effects other than direct oiling of plumage have seldom been confirmed. The 

addition of the 181 South Area is not expected to change accidental impacts to coastal and marine birds 

presented in Chapter 4.4.8 of the Multisale EIS. Oil-spill impacts on birds from a CPA or WPA proposed 

action are expected to be negligible. Impacts of oil-spill cleanup from such a proposed action are also 

expected to be negligible. 

4.1.9.4. Cumulative Impacts 

Introduction/Background 

A detailed description of cumulative impacts to coastal and marine birds can be found in Chapter 

4.5.8 of the Multisale EIS. The following is a summary of the information presented in the Multisale EIS, 

which incorporates new information found since publication of the Multisale EIS. 

This cumulative analysis considers the effects of impact-producing factors related to the proposed 

actions; prior and future OCS sales; State oil and gas activity; crude oil imports by tanker; and other 

commercial, military, and recreational offshore and coastal activities that may occur and adversely affect 

populations of nonendangered/nonthreatened and endangered/threatened (listed) birds. Both listed and 

non-listed birds are discussed together because the impacts are similar. 

The OCS-related, impact-producing factors include oil spills and any improperly regulated spillresponse activities; habitat loss and modification resulting from coastal facility construction and 

development; OCS pipeline landfalls; aircraft and vessel traffic and noise, including OCS helicopter and 

service-vessels; air emissions; degradation of water quality; and trash and debris. Non-OCS, impactproducing factors include pollution of coastal waters resulting from municipal, industrial, and agricultural 

runoff and discharge; bird-watching activities; maintenance and use of navigation waterways; collisions 

of coastal and marine birds with structures such as power line towers; disease; storms and floods; coastal 

development; and fisheries interactions (negative impacts of decreased food resources by fisheries catch, 

and positive impacts of increased food resources from discarded bycatch). 

Extent of Impacts 

Activities considered under the cumulative scenario will detrimentally affect coastal and marine birds. 

The net effect of habitat loss from oil spills; habitat loss and modification resulting from coastal facility 

construction and development, as well as OCS pipeline landfalls; and maintenance and use of navigation 

waterways will alter species composition and reduce the overall carrying capacity of disturbed area(s) in 

general. These would be the most serious cumulative impacts on birds. 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). 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. Behavioral 

impacts will 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 may be a part of natural avian population regulation. Storms and floods are natural disturbances 

to which exposed organisms are generally adapted. Fisheries catch may reduce population densities of 

avian aquatic predators limited by food availability by taking substantial food away. Substantially 

increased food resources from discarded fishery bycatch may have the opposite (positive) impact. Both 

processes are of special concern because fisheries are a recent unnatural intrusion into the function of 

coastal communities and organisms may not have had time to adapt. 

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, as exemplified in historic census data, 
4-124 Central and Western Gulf of Mexico Multisale Supplemental EIS

and to stem from a net decrease in preferred and/or critical habitat. However, the incremental 

contribution of a CPA or WAP proposed action to the cumulative impacts on coastal and marine birds 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, even though some 

displacement of local individuals or flocks may occur. It is expected that there will be little interaction 

between oil spills from a proposed action and coastal and marine birds. 

A search was conducted for new information published since completion of the Multisale EIS. A 

search of Internet bibliographic databases, as well as personal interviews with authors of references used 

in the Multisale EIS, was conducted to determine the availability of recent information since publication 

of the Multisale EIS. The Internet databases examined included Google Advanced Book Search (2007a) 

and OCLC FirstSearch (2007). No new information was found from these information sources. No 

recent information was found that would necessitate a reanalysis of the impacts of a CPA or WPA 

proposed action upon coastal and marine birds. The analysis and potential impacts detailed in the 

Multisale EIS applies for this SEIS. 

Summary and Conclusion 

The cumulative effect 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. Some of these changes are expected to be permanent, as exemplified in 

historic census data, and to stem from a net decrease in preferred habitat for all birds and critical habitat 

for endangered species. However, the increment increase of a CPA or WPA proposed action is expected 

to be negligible, even taking into account the relatively small addition of oil production from the 181 

South Area to production for proposed actions analyzed in the Multisale EIS. 

4.1.10. Endangered and Threatened Fish 

4.1.10.1. Gulf Sturgeon 

The MMS has reexamined the analysis for Gulf sturgeon presented in the Multisale EIS, based on the 

additional information presented below and the addition of the 181 South Area to the proposed CPA sale 

area. No significant new information was found that would alter the impact conclusion for Gulf sturgeon 

presented in the Multisale EIS. The 181 South Area is nearly 130 mi (209 km) from the nearest coast, 

and it is not located within the designated critical habitat for Gulf sturgeon. It is extremely unlikely that 

there will be any sturgeon in the 181 South Area due to water depths that far exceed the recorded depths 

preferred by this sturgeon species. In addition, substrate type and the potential forage base associated 

with bottom types at these depths are not conducive for sustaining a Gulf sturgeon food base. 

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

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

presented in the Multisale EIS. A summary of those analyses and their reexamination due to new 

information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. 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 will 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. The incremental contribution of a proposed action to the cumulative impacts to Gulf sturgeon is 

small, and it is expected to be negligible and indiscernible from impacts of inshore activities. 

The Gulf sturgeon has been infrequently noted in some of the extreme easternmost portions of the 

WPA, but there has been no critical habitat designated west of the Mississippi River. Because of the 

infrequency of occurrence of Gulf sturgeon in the WPA, the following discussion of impacts to Gulf 

sturgeon is limited to the CPA. 
Environmental and Socioeconomic Consequences 4-125 

4.1.10.1.1. Description of the Affected Environment 

A detailed description of Gulf sturgeon can be found in Chapter 3.2.7.1 of the Multisale EIS. The 

following is a summary of the information presented in the Multisale EIS, which incorporates new 

information found since the publication of the Multisale EIS. 

The NMFS and FWS listed the Gulf sturgeon (Acipenser oxyrinchus desotoi) as a threatened species 

on September 30, 1991. Critical habitat, designated on April 18, 2003, was defined as 14 geographic 

areas in the Gulf of Mexico’s rivers and tributaries (Figure 3-11): 

• 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 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 Gulf 

of Mexico; 

• Pensacola Bay system in Florida; 

• Santa Rosa Sound in Florida; 

• nearshore Gulf of Mexico in Florida; 

• Choctawhatchee Bay system in Florida; 

• Apalachicola Bay system in Florida; and 

• Suwannee Sound and adjacent State waters within the Gulf of Mexico in Florida. 

The NMFS indicates that no changes in critical habitat have occurred and they are working to develop 

an estimate of sturgeon habitat loss and a habitat suitability index (HSI) for the species (Bolden, personal 

communication, 2007). They also have no data indicating that sturgeons are using the deeper Gulf 

waters. In general, the mud substrates found in the Gulf waters do not support the appropriate benthic 

food source for Gulf sturgeon. 

The formal ESA consultation with NMFS was concluded with receipt of the BO on July 3, 2007 

(USDOC, NMFS, 2007d). The BO concludes that the proposed actions would not adversely impact the 

endangered Gulf sturgeon or its critical habitat and that additional mitigative actions other than those 

already identified and in place would not be necessary 

Additional research was conducted to investigate information that may be available since completion 

of the Multisale EIS. A search of Internet information sources, as well as personal interviews with 

personnel from State and Federal resource agencies, was conducted to determine the availability of recent 

information. Various Internet sources were examined to determine any recent information regarding Gulf 

sturgeon (Florida Fish and Wildlife Commission, 2007; USDOI, FWS, 2007b and c). No new 

information was found from these information sources. State and Federal resource agencies were 

contacted and interviews were conducted to investigate any recent published or unpublished data that may 

be available. Current information on the impacts of Hurricane Katrina indicates that there may have been 
4-126 Central and Western Gulf of Mexico Multisale Supplemental EIS

some displacement of sturgeon or possibly damage to their habitat in localized areas where the storm 

forces were strongest. The current sampling programs along the coastal Gulf South indicate (at least 

anecdotally) that sturgeon are returning to the areas they occupied prior to the storm, which may indicate 

somewhat of a recovery of those areas (Paruka, personal communication, 2007a). No changes in 

migratory patterns or blockages of migratory pathways have been noted. In general, the researchers noted 

that the sturgeon are normally found approximately 0.5 mi (0.8 km) from shore between the shoreline and 

the barrier islands, with the bulk of the fish located in the CPA between Petit Bois, Dauphin, and 

Chandeleur Islands and from Perdido to Panama City, Florida, and as far as Fort Walton Beach (Slack, 

personal communication, 2007; Paruka, personal communication, 2007a). A Gulf sturgeon population 

census was conducted in the lower Escambia River from October 10 through November 5, 2006. This 

fish collection coincided with the sturgeons’ fall migration from the freshwater to marine environment. 

This study collected 130 fish ranging in size from 1 to 145 pounds (lb) (0.5 to 66 kilograms (kg)). Large 

fish (>99 lb or 45 kg) accounted for 10 percent of the catch, which is less than in 2003 where the same 

class comprised 19 percent of the catch (Paruka, 2007b). The current Gulf sturgeon population estimate 

is 451 fish. The decrease from the estimated 554 fish in 2003 is probably due to hurricane-induced, 

degraded water quality. Hurricane Ivan caused massive fish kills in 2004. 

A total of 17 Gulf sturgeon were collected in coastal Alabama waters from 2001 to 2007. Six of the 

14 sturgeon were collected in Alabama coastal waters in 2006 (Metee and Rider, 2007). A 160-lb (73-kg) 

Gulf sturgeon was captured, tagged, and released in Mobile Bay near Fairhope Alabama in February 2006 

and was later relocated in early 2007 near the Choctawhatchee River in 2007. 

The Gulf sturgeon is anadromus, 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. Subadult and adult Gulf sturgeon 

spend cool months (October or November through March or April) in estuarine areas, bays, or in the Gulf 

of Mexico (Odenkirk, 1989; Clugston et al., 1995). Adult Gulf sturgeon likely overwinter in the Gulf of 

Mexico, but this is currently unknown for the majority of the population. 

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). Unvegetated estuary and bay habitats have 

a preponderance of sandy substrates that support burrowing crustaceans, which are known to be prey 

items. Studies along the Florida coast indicate that Gulf sturgeon use shoreline areas between 2 and 4 m 

(6.5 and 13.0 ft) deep characterized by low relief and sand substrate (Fox et al., 2002). These studies also 

noted the occasional use of depths deeper than 4 m (13 ft) but concluded that these deeper waters were 

used for movement between shoreline areas. Gulf sturgeon can move fairly long distances rapidly but the 

moves are generally localized and, in all cases, sturgeon return to the optimum preferred shallow depth. 

Foraging areas for the Gulf sturgeon in the open Gulf of Mexico is unknown. Using telemetry studies as 

a basis, it has been hypothesized that a small percentage of the Gulf sturgeon population monitored may 

use the open Gulf for foraging. This conclusion is based on the absence of tagged sturgeon (relocated to 

deeper offshore waters) not being present in the nearshore samples, therefore indicating that these fish did 

not return as others did to the nearshore waters (Paruka et al., 2001). Some adult Gulf sturgeon were 

noted to migrate >100 km (62 mi) into marine waters, although as previously noted the majority returned 

quickly to shallow water (Fox et al., 2002). 

The evaluation of tagging data has identified several nearshore Gulf of Mexico feeding migrations but 

no offshore Gulf of Mexico feeding migrations. Telemetry data documented Gulf sturgeon from the Pearl 

River and Pascagoula River subpopulations migrating from their natal bay systems to Mississippi Sound 

and moving along the barrier islands on both the island passes (Ross et al., 2001). Based on recent 

population estimates for Pearl River drainage (Kirk and Rogillio, personal communication, 2007), the 

annual populations of sturgeon varied from the 1996 to 2005 period of record from an annual low of 222 

fish to a high of 536 fish captured. The acceptable range for annual mortality required to sustain the 

population in the Pearl River System was estimated to be in the range of 16 to 24 percent mortality. 

There was insufficient captures post-Hurricane Katrina to obtain an actual population number; however, a 

mortality rate of 38 percent was estimated. Based on this estimate of mortality, there is insufficient 

recruitment to maintain the current Pearl River population. Estimated annual populations of Gulf 

sturgeon in the Pascagoula River system is approximately 234 with an annual fish count that ranged from 

142 to 394 fish per year over a period of record from 1999 to 2000 (Slack, personal communication, 
Environmental and Socioeconomic Consequences 4-127 

2001). Based on this conversation, the 2005 annual population estimate for the Pascagoula system is 210 

fish. 

Gulf sturgeons from the Choctawhatchee, Yellow, and Apalachicola Rivers have been documented 

migrating in the nearshore Gulf of Mexico waters between the Pensacola and Apalachicola Bay units 

(Fox et al., 2000). Telemetry data from the Gulf of Mexico mainly show sturgeon in depths of 6 m 

(19.8 ft) or less (Ross et al., 2001; Fox et al., 2000). 

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 Gulf of Mexico, south to Tampa Bay (Wooley and Crateau, 1985; USDOI, FWS, 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). 

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). Although fry and juveniles feed in the riverine environment, 

subadults and adults do not (Mason and Clugston, 1993; Sulak and Clugston, 1999).

The offshore winter distribution of Gulf sturgeon relative to the location of the activities under the 

proposed action is unknown. However, there have been no reported catches of this species in Federal 

waters (Sulak, personal communication, 1997). 

The decline of the Gulf sturgeon is believed to be due to overfishing and habitat destruction, primarily 

the damming of coastal rivers and the degradation of water quality (Barkuloo, 1988). In the late 19th 

century and early 20th century, the Gulf sturgeon supported an important commercial fishery, providing 

eggs for caviar, flesh for smoked fish, and swim bladders for isinglass, a gelatin used in food products and 

glues (Carr, 1983). Dams and sill construction mostly after 1950 restricted access to historic spawning 

areas (Wooley and Crateau, 1985), exacerbating habitat loss, and overfishing resulted in the decline of the 

Gulf sturgeon throughout most of the 20th century. In several rivers throughout its range, dams have 

severely restricted sturgeon access to historic migration routes and spawning areas. Dredging and other 

navigation maintenance, possibly including lowering of river elevations and elimination of deep holes and 

altered rock substrates, may have adversely affected Gulf sturgeon habitats (Wooley and Crateau, 1985). 

Contaminants, both agricultural and industrial, may also be a factor in their decline. Organochlorines 

have been documented to cause reproductive failure in the Gulf sturgeon, reduced survival of young, or 

physiological alterations in other fish (White et al., 1983). In addition, Gulf sturgeon appear to be natal 

spawners with little, if any, spawning from other riverine populations. 

Today, the greatest habitat threat to sturgeon is the damming of coastal rivers. Sturgeon cannot pass 

through the lock and dam systems to reach spawning areas. Dredging, desnagging, and spoil deposition 

associated with channel maintenance and improvement also present a threat to sturgeon spawning habitat. 

Poor water quality because of pesticide runoff, heavy metals, and industrial contamination may be 

affecting sturgeon populations. Habitat loss continues to pose major threats to the recovery of the species. 

Natural phenomenon 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 and 

2005 hurricane seasons brought major and repeated damage to the Gulf Coast area. The effects from 

Hurricane Katrina (2005) are still being assessed. The impacted area included a large portion of the 

designated critical habitat and known locations of Gulf sturgeon. The sturgeons are upstream in 

freshwater riverine habitats during the tropical storm season. This may give the estuarine and marine 

areas time to recover from hurricane impacts before the sturgeon move downstream. For instance, 

massive runoff due to flooding rains and swollen tributaries could cause a sharp increase in toxic 

contaminants in estuarine habitats. However, spreading and dilution should mitigate any threat to 

sturgeon very quickly. By the time the downstream migration occurs, conditions should have returned to 

near normal. The flooding and subsequent “unwatering” of New Orleans in the fall of 2005 created 

concern for any sturgeon that might have been in the areas of Lake Pontchartrain, 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 
4-128 Central and Western Gulf of Mexico Multisale Supplemental EIS

locations of Lake Pontchartrain. It was expected that any sturgeon displaced returned to the area once the 

unwatering activities ceased (USACE, 2005a). The COE also noted that the emergency procedures 

permitted in the Panama City, Florida, aftermath of Hurricane Ivan may have created temporary impacts 

to species, including the Gulf sturgeon, but the emergency procedures did not adversely impact the 

species (USACE, 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. The hurricane impacts have not yet been fully assessed for Gulf sturgeon but they 

are generally believed to be temporary (Baker, personal communication, 2006). 

An unpredictable event that is currently having an affect on some of the Gulf sturgeon habitat in some 

of the Gulf States is the drought conditions along the upper portions of rivers feeding the lower riverine 

habitat for the species located in these coastal rivers. Recently, potential threats to the Gulf sturgeon 

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 upper Georgia (Picard, 

2007). 

4.1.10.1.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA proposed 

action on Gulf sturgeon is presented in Chapter 4.2.2.1.9.1 of the Multisale EIS. 

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 (Chapter 3.2.7.1 of 

Multisale EIS). Critical habitat is defined as special geographic areas that are essential for the 

conservation of a threatened or endangered species and that may require special management and 

protection. Designated Gulf sturgeon critical habitat is confined to State waters. Most activities related to 

the CPA proposed action will occur in Federal waters (e.g., structure placement, drilling, removal, etc); 

however, critical habitat may be impacted directly or indirectly. 

The Gulf sturgeon has been infrequently noted in some of the extreme easternmost portions of the 

WPA, but there has been no critical habitat designated west of the Mississippi River. Because of the 

infrequency of occurrence of Gulf sturgeon in the WPA, a discussion of impacts to Gulf sturgeon will be 

limited to the CPA. 

The 181 South Area is nearly 130 mi (209 km) from the nearest coast, and it is not located within the 

designated critical habitat for Gulf sturgeon. It is also extremely unlikely that there will be any sturgeon 

in the 181 South Area due to water depths that far exceed the recorded depths shown as a preference by 

this sturgeon species. Substrate type and the potential forage base associated with bottom types at these 

depths are not conducive for sustaining a Gulf sturgeon food base. 

CPA Proposed Action Analysis 

The routine activities associated with a CPA proposed action that would impact Gulf sturgeon include 

installation of pipelines in coastal waters, maintenance dredging of navigational canals, potential for 

service vessel strikes, and nonpoint-source runoff from onshore facilities. 

One to three new pipelines are projected to be installed in State waters as a result of a CPA proposed 

action. These new installations could temporarily increase the local total suspended solids in the water. 

The COE and State permits would require avoidance, minimization of impacts, and mitigation. 

The Corps and State permits would also require using techniques that would minimize turbidity 

impacts and require the beneficial use of dredged material for wetlands restoration. 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. 

Minor degradation of estuarine water quality is expected in the immediate vicinity of shore bases and 

other OCS-related facilities as a result of routine effluent discharges and runoff. Rapid dilution is 
Environmental and Socioeconomic Consequences 4-129 

expected to negate any impact to critical habitat or Gulf sturgeon from these sources. Offshore discharges 

of drilling muds and produced waters are expected to dilute to background levels within 1,000 m (3,281 

ft) of the discharge point (CSA, 1997). In addition, sturgeons are not known to be attracted to petroleum 

structures or activity, which is where the discharges would be the most concentrated. 

Service-vessel traffic running in and out of shore bases may create the potential for impact to Gulf 

sturgeon. However, due to the benthic nature of the sturgeon and their lack of attraction to dredging 

activity (Paruka, 2007c), it is doubtful that they would encounter a vessel strike. Recent studies have 

noted that freshwater sturgeon species respond to certain noise levels by moving from the bottom to 

varying distances up into the water column but still not to the depth that the fish would be susceptible to 

vessel strike (Hoover and Beard, 2007). 

It is also highly unlikely that Gulf sturgeon would encounter any drilling muds or produced waters 

from the 181 South Area since this area is at least 100-130 mi (161-209 km) offshore from any critical 

habitat or known preferred coastal holding areas for Gulf sturgeon. The current critical habitat is in State 

waters, well inshore of the location of any oil or gas structure installed as a result of a CPA 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. Sturgeons generally remain in the estuarine regions near river mouths or in 

shallow Gulf waters. 

Summary and Conclusion 

Potential impacts on Gulf sturgeon and the designated critical habitat may occur from drilling and 

produced-water discharges, degradation of estuarine and marine water quality by nonpoint runoff from 

estuarine OCS-related facilities, vessel traffic, explosive removal of structures, and pipeline installation. 

The dilution and low toxicity of these discharges are expected to result in a negligible impact of a CPA 

proposed action on Gulf sturgeon. Vessel traffic will generally only pose a risk to Gulf sturgeon when 

leaving and returning to port. Major navigation channels are excluded from critical habitat. The Gulf 

sturgeon’s characteristics of bottom-feeding and general avoidance of disturbance make the probability of 

vessel strike extremely remote. Explosive removal of structures as a result of a CPA proposed action will 

occur well offshore of Gulf sturgeon critical habitat and the riverine, estuarine, and shallow Gulf habitats 

where sturgeon are generally located. Environmental permit requirements and recent techniques for 

installing pipelines will result in very minimal impact to Gulf sturgeon critical habitat if any pipeline is 

installed nearshore due to a proposed action. Impacts from routine activities resulting from a CPA 

proposed action are expected to have negligible effects on Gulf sturgeon and their designated critical 

habitat. 

4.1.10.1.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of accidental impacts upon Gulf sturgeon can be found in Chapter 4.4.9.1 of 

the Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

Accidental impacts associated with a CPA or WPA proposed action that could adversely affect Gulf 

sturgeon include oil spills associated with the transport and storage of oil (Chapter 4.3.1 of the Multisale 

EIS). 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 

areas 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 (Chapter 3.2.7.1 of the Multisale EIS) 

in the CPA. There is no critical habitat designated in the WPA and 181 South Area is totally within 

Federal waters approximately 130 mi (209 km) from the designated critical habitat. Designated Gulf 

sturgeon critical habitat is confined to State waters. Most activities related to a proposed action will occur 

in Federal waters; however, critical habitat may be impacted directly or indirectly. Gulf sturgeon are 
4-130 Central and Western Gulf of Mexico Multisale Supplemental EIS

primarily benthic feeders and inhabit mostly nearshore, coastal water environments of moderate depth, 

except during the riverine spawning period. Based on current studies (Paruka, 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. Based on information from NMFS (Bolden, personal communication, 

2007), the muddy substrates found in deeper waters are not conducive for the sturgeons preferred benthic 

food base. It was noted that, throughout the many years that the offshore platforms have been monitored 

by remotely-operated vehicles (ROV’s), divers and active sampling, there has been no observation of 

Gulf sturgeon (Randall, personal communication, 2007) in or around these offshore sites. In recent 

sturgeon studies on the Suwannee River in Florida, it was noted that the smaller fish generally remain 

more inland and in shallow water while the juveniles tend to come down river from the spawning grounds 

closer to the river mouth. Adults tend to use the river mouth and the surrounding bays, sometimes 

venturing out to the barrier islands (Sulak et al., 2007). The juveniles and subadults, at least seasonally in 

the nearshore coastal waters, 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. 

Due to the distance of the 181 South Area from the potential known locations and critical habitat, the 

oil from an offshore spill would be sufficiently weathered and its toxic components neutralized by the 

time it reached the areas used by sturgeon. There is a greater potential for sturgeon contact with 

nearshore spills as a result of a pipeline rupture or vessel collisions. Some significant effects on sturgeon 

from cleanup efforts could occur if dispersants are used in the nearshore environment. The use of oil 

dispersants increases the risk of impact with bottom-feeding and/or bottom-dwelling fauna. For this 

reason, dispersants are not expected to be used with coastal spills. The dispersant can consolidate and 

take the oil to the bottom. The higher spill potential would be along the Louisiana coast, but the winds, 

increased wave energy, and the outflow of the Mississippi River would assist in the dispersion of an 

offshore spill. The potential risk to sturgeon would result from either direct contact with oil spills (or the 

potential PAH’s introduced through the spill) or, in some cases, long-term exposure. 

CPA Proposed Action Analysis 

Gulf sturgeon critical habitat is restricted to State waters east of the Mississippi River and primarily 

nearshore along river mouths and associated bays. The greatest threat to Gulf sturgeon would be from 

inland 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 being contacted by spills from operations related 

to a CPA proposed action. 

Spills that could occur in coastal waters from support operations (supply vessels and transport) are 

estimated at 46-102 spills for a CPA proposed action over its 40-year life. Oil spills that occur offshore 

are much less likely to contact Gulf sturgeon or their critical habitat than are inshore spills. The 

probabilities of an offshore spill ≥1,000 bbl occurring and contacting environmental features are 

described in Chapter 4.3.1.8 of the Multisale EIS and Chapter 3.2.1 of this SEIS. Eight parishes in 

Louisiana have a >0.5 percent chance of spill contact. For these parishes, the chance of an OCS offshore 

spill ≥1,000 bbl ranges from 1 to 16 percent. In Louisiana, the Deltaic Plain area has the highest risk of a 

spill ≥1,000 bbl occurring and contacting the coast as a result of a CPA proposed action (Chapter 4.3.1 of 

the Multisale EIS). 

Figures 3-10 and 3-11 show the known locations of Gulf sturgeon and the location of Gulf sturgeon 

critical habitat. The probability of an offshore oil spill ≥1,000 bbl occurring and contacting the known 

locations of Gulf sturgeon is 6-10 percent as the result of a proposed action over its 40-year life. There is 

<0.5-1 percent probability of an offshore oil spill ≥1,000 bbl occurring and contacting the western portion 

of Gulf sturgeon critical habitat (Unit 8), with a <0.5 percent for the eastern critical habitat portion (Units 

9-14). The risk of exposure of Gulf sturgeon to such a spill would be dependent on the species abundance 

and density, as well as the size and persistence of the slick. 

As explained in Chapter 3.2.1, the incremental increase in oil production from the addition of the 

181 South Area is not expected to result in an overall increase in the numbers of oil spills ≥1,000 bbl 

likely to occur as a result of a CPA proposed action. Activity that would result from the addition of the 
Environmental and Socioeconomic Consequences 4-131 

181 South Area would cause a negligible increase in the risk of a large spill occurring and contacting 

known locations of Gulf sturgeon or critical habitat.

Due to the distance of the activity from shore and critical habitat, it is unlikely that offshore spills or 

effluents will impact sturgeon habitat. The dilution and low toxicity of this pollution is expected to result 

in a negligible impact of a CPA proposed action on Gulf sturgeon. 

Summary and Conclusion 

Due to the distance of the activity from shore and Gulf sturgeon critical habitat, there is a minimal 

risk of any oil coming in contact with Gulf sturgeon. The likelihood 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 very 

small. Contact with oil spills could cause the fish to temporarily migrate from the affected area and could 

cause nonfatal irritation of gill epithelium and an increase of liver function in a few adults, which are 

nonlethal. 

The NMFS Biological Opinion (USDOC, NMFS, 2007d) concurred with MMS that the proposed 

actions would not adversely impact the endangered Gulf sturgeon or its critical habitat. No additional 

mitigative actions, other than those already identified, would be necessary. 

4.1.10.1.4. Cumulative Impacts 

Background /Introduction 

A detailed description of cumulative impacts upon Gulf sturgeon and its critical habitat can be found 

in Chapter 4.5.9 of the Multisale EIS. The following is a summary of the information presented in the 

Multisale EIS, which incorporates new information found since publication of the Multisale EIS. This 

cumulative analysis summary considers activities that could occur and adversely affect Gulf sturgeon 

within its range and critical habitat in the northern Gulf of Mexico, east of the Mississippi River during 

the 40-year analysis period. These activities include effects of the OCS Program (a proposed action, and 

prior and future OCS lease sales), State oil and gas activity, coastal development, man-induced 

modifications to water quantity and air quality, crude oil imports by tanker, commercial and recreational 

fishing, and natural phenomena. Specific types of impact-producing factors considered in this cumulative 

analysis include coastal and marine environmental degradation by nonpoint runoff from estuarine OCSrelated facilities, produced-water discharges, pipeline emplacements, oil spills, dredge-and-fill operations 

and natural catastrophes that alter or destroy habitat, commercial fishing techniques that result in sturgeon 

bycatch, and man-induced salinity modifications. 

Vessel traffic will generally only pose a risk to Gulf sturgeon when leaving and returning to port. 

Major navigation channels are excluded from critical habitat. The Gulf sturgeon’s characteristics of 

bottom-feeding and general avoidance of disturbance make the probability of vessel strike extremely 

remote. The explosive removal of structures as a result of a CPA proposed action will occur well 

offshore of Gulf sturgeon critical habitat and the riverine, estuarine, and shallow Gulf habitats where 

sturgeon are generally located. Environmental permit requirements and recent techniques for locating 

pipelines will result in very minimal impact to Gulf sturgeon critical habitat if any pipeline is installed 

nearshore as a result of a CPA proposed action. 

Hurricanes and other Natural Catastrophes 

Natural catastrophes and non-OCS activities such as dredge-and-fill may destroy or temporarily 

impair Gulf sturgeon habitat. Natural catastrophes including storms, floods, droughts, and hurricanes can 

result in substantial habitat damage. 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. The impacted area included a large portion of the designated critical habitat and known 

locations of Gulf sturgeon. The sturgeon is located upstream in freshwater riverine habitats during 

hurricane season. This may give the estuarine and marine areas time to recover from hurricane impacts 
4-132 Central and Western Gulf of Mexico Multisale Supplemental EIS

before the sturgeon move downstream. For instance, massive runoff due to flooding rains and swollen 

tributaries could cause a sharp increase in toxic contaminants in estuarine habitats. However, spreading 

and dilution should mitigate any threat to sturgeon very quickly. By the time the downstream migration 

occurs, conditions should have returned to near normal. Paruka (personal communication, 2007a) noted 

that his sturgeon monitoring program located fish that were displaced from the Panama City, Florida, area 

in Mobile Bay in 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 (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 (USACE, 2005a). The COE also noted that the 

emergency procedures permitted in the Panama City, Florida, aftermath of Hurricane Ivan may have 

created temporary impacts to species including the Gulf sturgeon, but that the emergency procedures did 

not adversely impact the species (USACE, 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 or were flooded and were likely a source 

of contaminant discharge. The hurricane impacts have not yet been fully assessed for Gulf sturgeon but 

are generally believed to be temporary (Baker, personal communication, 2006). 

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 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 

(Picard, 2007). 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. 

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. In addition, increases in trawl 

density and successive trawling in one area may cause long-term impacts to the critical habitat. 

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. 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. 

Navigation channels are not included in the critical habitat. 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. A 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 
Environmental and Socioeconomic Consequences 4-133 

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, the MMS’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 an HSI for the species (Bolden, personal communication, 2007). 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. 

Oil Spills 

The Gulf sturgeon could be impacted by oil spills resulting from a 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 distance (nearly 

130 mi or 209 km offshore) of the 181 South Area to Gulf sturgeon critical habitat, migratory routes, or 

nursery and feeding areas, there is a very low probability of impact from spills from this area. 

Direct contact with spilled oil could have detrimental physiological effects. The juvenile and 

subadult Gulf sturgeon, at a minimum, seasonally use the nearshore coastal waters and could potentially 

be at risk from both coastal and offshore spills. However, several factors influence the probability of 

spilled oil contact with Gulf sturgeon or their critical habitat. The likelihood of spill occurrence and 

subsequent contact with, or impact to, Gulf sturgeon and/or designated critical habitat is extremely low. 

Based on current OSRA modeling, 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 from within the 

181 South Area. 

The numbers and sizes of coastal spills are presented in Table 4-13 of the Multisale EIS. About 95 

percent of these spills are projected to be from non-OCS-related activity. Of coastal spills <1,000 bbl, the 

assumed size is 5 bbl; therefore, the great majority of coastal spills would affect a very small area and 

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. A total of 4-5 large 

(≥1,000 bbl) offshore spills are projected to occur annually from all sources Gulfwide. Of these offshore 

spills, one is estimated to occur every 1 to 2 years from the Gulfwide OCS Program (Table 4-15 of the 

Multisale EIS). A total of 1,550-2,150 smaller offshore spills (<1,000 bbl) are projected annually 

Gulfwide. The majority of these spills (1,350-1,900) would originate from OCS Program sources. 

Chapter 4.3.1.2 of the Multisale EIS describes the projections of future spill events in more detail. 

For spills >1,000 bbl, concentrations of oil below the slick are within the ranges that cause sublethal 

effects on marine organisms. However, when exposure time beneath accidental spills, hydrocarbon 

composition, and the change in this composition during weathering are considered, exposure doses are 

assumed to be far less than doses reported to cause even sublethal effects (McAuliffe, 1987). Given the 

low probability that the low-population 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 sub adult 

Gulf sturgeon, the impacts of spilled oil on this endangered subspecies are expected to be very low. 

However, regardless of spill size, the effects of direct contact from spilled oil on Gulf sturgeon occur 

through the ingestion of oil or oiled prey and the uptake of dissolved petroleum through the gills by adults 

and juveniles. Contact with or ingestion/absorption of spilled oil by adult Gulf sturgeon can result in 

mortality or sublethal physiological impact, especially irritation of gill epithelium and disturbance of liver 

function. It is expected that the extent and severity of effects from oil spills will 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 
4-134 Central and Western Gulf of Mexico Multisale Supplemental EIS

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. 

Other Impact-Producing Factors 

The cumulative and possibly repetitive affects 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 (Picard, 2007). 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. 

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 greatly modify nearshore salinity in 

the nearshore estuaries and bays (Mississippi Press, 2007). 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. 

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 will be sublethal and last for less than 1 month. Contact with spilled oil could have detrimental 

physiological effects. The juvenile and subadult Gulf sturgeon, at a minimum, seasonally use the 

nearshore coastal waters and could potentially be at risk from both coastal and offshore spills. However, 

several factors influence the probability of spilled oil contact with Gulf sturgeon or their critical habitat. 

The likelihood of spill occurrence and subsequent contact with, or impact to, Gulf sturgeon and/or 

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 will experience a decline in 

population sizes and a displacement from their current distribution that will last more than one generation. 

Deaths of adult sturgeon are expected to occur from commercial fishing. The incremental contribution of 

a CPA proposed action to the cumulative impact is negligible because the effect of contact between salespecific oil spills and Gulf sturgeon is expected to be sublethal and last less than 1 month. 

Additional research was conducted to investigate recently available information since completion of 

the Multisale EIS. A search of Internet information sources, as well as personnel interviews with 

personnel from State and Federal resource agencies, was conducted to determine the availability of recent 

information. No significant new information was found that would alter the conclusion as described in 

the Multisale EIS that the incremental contribution of a CPA proposed action’s impacts on fish resources 

to the cumulative impact is minimal. Furthermore, activity projected to result from the addition of the 

181 South Area is negligible compared with total OCS activity, and it is not likely to result in a 

significant contribution to cumulative impacts. 

The NMFS and MMS completed consultation, as specified under Section 7 of the ESA, on the effects 

of the 5-Year OCS Program (2007-2012) in the CPA and WPA, inclusive of the 181 South Area. A 

Biological Opinion was received by MMS on July 3, 2007, agreeing with MMS that the CPA and WPA 

proposed actions would not adversely impact the endangered Gulf sturgeon or its critical habitat and that 

additional mitigative action other than those already identified and in place would not be necessary 

4.1.11. Fisheries and Essential Fish Habitat 

The MMS has reexamined the analysis for fisheries and essential fish habitat (EFH) presented in the 

Multisale EIS, based on the additional information presented below and the addition of the 181 South 

Area to the proposed CPA sale area. No significant new information was found that would alter the 

impact conclusion for fisheries and EFH presented in the Multisale EIS. Due to the extreme depths in this 

area, the only managed fish species (and their pelagic EFH) are some of the highly migratory species 

including sharks, billfish, and tuna. The 181 South Area is located in very deep water, and limited 
Environmental and Socioeconomic Consequences 4-135 

activities in that area would not have any measurable additional impacts to fish resources or EFH for 

highly migratory species (the only managed species group that far offshore). 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Fish resources and EFH could be impacted by coastal 

environmental degradation, marine environmental degradation, pipeline trenching, and offshore 

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

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

resources or in EFH. Impacts of routine discharges are localized in time and space, are regulated by 

USEPA permits, and will have minimal impact. Accidental events that could impact fish resources and 

EFH include blowouts and oil or chemical spills. A subsurface blowout would have a negligible effect on 

Gulf of Mexico fish resources. If spills due to a CPA or WPA proposed action were to occur in open 

waters of the OCS proximate to mobile adult finfish or shellfish, the effects would likely be nonfatal and 

the extent of damage would be reduced due to the capability of adult fish and shellfish to avoid a spill. 

Impact-producing factors of the cumulative scenario that are expected to substantially affect fish 

resources and EFH include coastal and marine environmental degradation, overfishing, and to a lesser 

degree, coastal petroleum spills and coastal pipeline trenching. At the estimated level of cumulative 

impact, the resultant influence on fish resources and EFH is expected to be substantial, but not easily 

distinguished from effects due to natural population variations. The incremental contribution of a CPA or 

WPA proposed action to the cumulative impacts on fisheries and EFH would be small. 

4.1.11.1. Description of the Affected Environment 

The description of the biology, life history, and distribution of fish resources and the description of 

EFH can be found in Chapters 3.2.8.1 and 3.2.8.2 of the Multisale EIS, respectively. The following 

information is a summary of the information presented in the Multisale EIS, which incorporates new 

information discussed since the publication of the Multisale EIS. 

The Gulf of Mexico supports a great diversity of fish resources that are related to variable ecological 

factors, including 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 Gulf also has some limited areas of hard substrate on the continental shelf, including topographic 

features or banks offshore Texas and Louisiana and smaller carbonate features often referred to as 

pinnacles offshore Mississippi and Alabama. There are thousands of these carbonate mounds or 

pinnacles dotting the OCS of Mississippi-Alabama that 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, 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 or feet of depth are better known than the 

deep pelagic species. Extensive trawl sampling of Gulf of Mexico continental slope demersal fish are 

also reported in a major MMS-funded, deep Gulf study (Gallaway et al., 1988). 

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 200,5 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 noted with a recent media 

statement saying, “The Louisiana Oyster Task Force said beds are being restored, and this year’s haul is 

expected to be equal to or better than the harvests before Hurricane Katrina” (New Orleans Hospitality 
4-136 Central and Western Gulf of Mexico Multisale Supplemental EIS

Briefs, 2007; WDSU.com, 2007). Some recent reports from NOAA have further documented impacts 

from the 2005 hurricanes on fish and fishery habitat. One recent example is NMFS’s Report to Congress 

on the Impact of Hurricanes Katrina, Rita, and Wilma on Commercial and Recreational Fishery Habitat 

of Alabama, Florida, Louisiana, Mississippi, and Texas that was published in July 2007 (USDOC, 

NMFS, 2007a). This report confirms the substantial impacts of the 2005 hurricanes to nearshore habitats, 

especially oyster reefs. Offshore fisheries habitat sustained some impact, but not substantial. Similar 

information was also presented in Chapter 3.2.8.1 of the Multisale EIS. A recent report to Congress 

concluded “With the exception of oysters, available information indicates Gulf Coast marine resources 

were not significantly impacted by the 2005 hurricanes” (USDOC, NMFS, 2007b). 

Additional research was conducted to investigate recently available information since completion of 

the Multisale 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. Significant informational Internet websites include the 

Gulf of Mexico Fisheries Management Council (http://www.gulfcouncil.org/) and NMFS’s Southeast 

Region (http://sero.nmfs.noaa.gov/). 

From April 1, 2007, through June 30, 2007, there were no major changes in the fish stock 

sustainability index (FSSI) reported by NMFS (USDOC, NMFS, 2007c). The following are the only 

changes in overfished status of FSSI stocks in the Southeast Region (April 1-June 30, 2007): 

• South Atlantic Gag is now approaching an overfished condition. 

• Dolphin is now above 80 percent of maximum sustainable yield. 

• Gulf of Mexico Red Grouper is now rebuilt. 

181 South Area 

The 181 South Area is a minimum of 177 mi (285 km) south of the panhandle of Florida. The nearest 

land is Louisiana over 130 mi (209 m) away. Water depths in the area range from 2,700 to 3,200 m 

(8,900 to 10,500 ft). 

The benthic fish populations of the 181 South Area are expected to be very low in density and 

restricted to the few species that live at water depths below 2,700 m (8,900 ft). Pelagic, highly migratory 

species including billfish and tuna are expected in the area as there has been some longline fishing in this 

area in the past. Longlining fishing in the area will also continue in the future because the 181 South 

Area lies outside the large longline closure areas in the Eastern Gulf of Mexico (CSA, 2002). 

Essential Fish Habitat 

In consideration of existing mitigation measures, lease stipulations, and a submitted EFH Assessment 

document, MMS 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. Most of this area is now designated part of the 

CPA. The NMFS considered an EFH Assessment describing OCS development activities, an analysis of 

the potential effects, MMS’s views on those effects, and proposed mitigation measures as acceptable and 

meeting with the requirements of EFH regulations at 50 CFR Subpart K, 600.920(g). 

Further programmatic consultation was initiated and completed for the 2007-2012 lease sales 

addressed in the Multisale EIS, which did not include the 181 South Area. The NMFS concurred by a 

letter dated December 12, 2006, that the information presented in the Draft Multisale EIS satisfied the 

EFH consultation procedures outlined in 50 CFR 600.920, and as specified in NMFS’s March 17, 2000, 

findings. Provided MMS proposed mitigations, NMFS’s previous EFH conservation recommendations, 

and the standard lease stipulations and regulations are followed as proposed, NMFS agrees that impacts to 

EFH and associated fishery resources resulting from activities conducted under the 2007-2012 lease sales 

would be minimal. 

To address the addition of the 181 South Area, this SEIS was submitted to NMFS for general EFH 

consultation agreement information. This SEIS includes all required components for a new EFH 

Assessment: (1) description of the proposed action; (2) description of the action agency’s approach to 
Environmental and Socioeconomic Consequences 4-137 

protection of EFH and proposed mitigation, if applicable; (3) description of EFH and managed and 

associated species in the vicinity of the proposed action; and (4) analysis of the effects of the proposed 

and cumulative actions on EFH, the managed species, and associated species. 

Chapters 1.5 and 2.2.2 of the Multisale EIS discuss MMS’s approach to the preservation of EFH with 

specific mitigations. Chapter 3.2.1 of the Multisale EIS details coastal areas that are considered EFH 

including wetlands and areas of submerged vegetation. Chapter 3.2.2 of the Multisale EIS describes livebottom formations and their biotic assemblages, which are considered EFH. Chapters 4.2.1.1.8 and 

4.2.2.10 of the Multisale EIS contain the impact analysis of the proposed actions 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 (FMP’s) 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 (HMS); however, due to water depth, 

the 181 South Area is only affected by FMP’s and EFH designation for highly migratory species 

including sharks, billfish, and tuna. 

The managed species with EFH in the 181 South Area can be easily determined by using EFH 

designation maps produced by NMFS (USDOC, NMFS, 1999a and b). Of all the 32 species of shark 

described by NMFS in the final FMP for Atlantic tunas, swordfish, and sharks (USDOC, NMFS,1999b), 

only the longfin mako shark has designated EFH in the 181 South Area for neonate and early juveniles, 

juvenile subadult, and adults. Also presented in same FMP are the EFH maps for tunas and swordfish. 

Bigeye and Atlantic albacore tuna do not have EFH for any life history stage in the 181 South Area. 

The bluefin tuna and skipjack tuna are depicted as having EFH in the 181 South Area for spawning, eggs, 

and larva but not for adults or juvenile/subadults. Yellowfin tuna are shown as having EFH in the area for 

spawning, eggs, larvae, and juvenile/subadults, but not for adults. Swordfish have EFH in the 181 South 

Area for all life stages except adults where the map depicts EFH just outside the 181 South Area. 

Billfish EFH maps are presented in Amendment 1 to the Atlantic billfish FMP (USDOC, NMFS, 

1999a). Sailfish and the longbill spearfish do not have EFH in the 181 South Area, but two marlin 

species do. The white marlin has only adult EFH in the area, and the blue marlin has only 

juvenile/subadult EFH in the 181 South Area. 

The abundance of the above-listed highly migratory species in the 181 South Area is not well known. 

The CSA (2002) presents data on longline sets in the area between 1994 and 1998. This region is not 

heavily fished, but there is some longline activity, primarily directed at yellowfin tuna. The designated 

habitat of concern would not be bottom related, but it would be the pelagic water column to a depth of up 

to 800 m (2,625 ft) for swordfish and perhaps as deep as 1,000 m (3,280 ft) if adult bluefin tuna were to 

occur in the area (Block et al., 2001).

4.1.11.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of the possible impacts from routine activities associated with a CPA or WPA 

proposed action on fish resources and EFH is presented in Chapters 4.2.2.1.10 and 4.2.1.1.8 of the 

Multisale EIS, respectively. The following is a summary of the information presented in the Multisale 

EIS, which incorporates new information found since the publication of the Multisale EIS. 

Effects on fish resources and EFH from routine activities associated with a 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 and WPA are estuary dependent, coastal 

environmental degradation resulting from a 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. 
4-138 Central and Western Gulf of Mexico Multisale Supplemental EIS

Since many of the fish species within the CPA and WPA are dependent on offshore water and a 

variety of specific bottom types including hard substrate, marine environmental degradation resulting 

from a proposed action, although indirect, has the potential to adversely affect EFH and fish resources. 

Offshore EFH includes both high- and low-relief live bottoms (pinnacles) and natural reefs (topographic 

features). 

CPA Proposed Action Analysis 

The routine impact effects of a CPA proposed action on coastal wetlands and coastal water quality, 

with the exception of accidental events, are analyzed in detail in the Multisale EIS in Chapters 4.2.2.1.3.2 

and 4.2.2.1.2.1, respectively. Collectively, the adverse impacts from these effects are called coastal 

environmental degradation. The effects of a proposed action on offshore live bottoms and marine water 

quality are analyzed in detail in Chapters 4.2.2.1.4.1.1 and 4.2.2.1.2.2 of the Multisale EIS, respectively. 

Collectively, the adverse impacts from these effects are called marine environmental degradation in this 

SEIS. 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 each proposed action. 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 0-1 new gas processing plants projected in support of a 

CPA proposed action. 

Wetlands that could be impacted for some period of time or converted to open water are discussed in 

Chapter 4.2.2.1.3.2 of the Multisale EIS. A small amount of the routine dredging done in coastal areas 

will be directly or indirectly due to a proposed action. It is expected that coastal environmental 

degradation from a proposed action would have little effect on fish resources or EFH. Recovery of fish 

resources or EFH can occur from more than 99 percent, but not all, of the potential coastal environmental 

degradation. Fish populations, if left undisturbed, will regenerate in one generation and most EFH can 

recuperate quickly, but the loss of wetlands as EFH could be permanent. At the expected level of effect, 

the resultant influence on fish resources or EFH from a CPA proposed action would be negligible and 

indistinguishable from natural population variations. 

Marine Environmental Degradation 

The Live Bottom (Pinnacle Trend) and Topographic Features Stipulations are discussed in Chapters 

2.3.1.3 and 2.4.1.3 the Multisale EIS. The application of the new category of Potentially Sensitive 

Biological Features in NTL 2004-G05 will also serve to prevent impacts to hard-bottom EFH habitat 

associated with topographic features that may lie outside previously defined No Activity Zones. For any 

activities associated with a proposed action, USEPA’s Region 6 (and Region 4 for some areas) will 

regulate discharge requirements for the CPA through their NPDES permits. 

The projected total number of platform installations resulting from a CPA proposed action is 28-41 

for all water depths (Table 3-2). Bottom disturbance from structure emplacement operations associated 

with a 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 in water depths <156 m (<512 ft) are removed by severing their pilings with 

explosives placed 5 m (16 m) below the seafloor. It is projected that approximately 14 structures in water 

depths <200 m (<656 ft) in the CPA will be removed using explosives as a result of a proposed action. It 

is expected that structure removals would have a negligible effect on fish resources because these 

activities kill only those fish proximate to the removal site. 

The projected length of pipeline installations for a CPA proposed action is 130-2,075 km (81-1,289 

mi) for all water depths. Trenching for pipeline burial has the potential to adversely affect fish resources. 

Any affected population is expected to recover to predisturbance condition in one generation. At the 
Environmental and Socioeconomic Consequences 4-139 

expected level of impact, the resultant influence on fish resources would be negligible and 

indistinguishable from other natural population variations. 

The major sources of routine discharges to marine waters associated with a CPA proposed action are 

the temporary discharge of drilling muds and cuttings and the long-term discharge of produced-water 

effluent. Offshore discharges of drilling muds are expected to dilute to background levels within 1,000 m 

(3,280 ft) of the discharge point. Produced-water discharges contain components and properties 

potentially detrimental to fish resources. 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, 1997). 

Because of the extreme depths of the 181 South Area, the only managed fish species (and their 

pelagic EFH) are some of the highly migratory species including sharks, billfish, and tuna. One 

additional structure is projected to be installed as a result of the addition of the 181 South Area. Routine 

activities in the 181 South Area would cause negligible impacts and would not deleteriously affect fish 

resources or EFH. 

It is expected that marine environmental degradation from a 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 occur from 100 percent 

of the potential marine environmental degradation. Fish populations, if left undisturbed, will regenerate 

in one generation. Offshore live bottoms including pinnacles and topographic features are not expected to 

be impacted. Offshore discharges and subsequent changes to marine water quality will be regulated by 

USEPA NPDES permits. At the expected level of effect, the resultant influence on fish resources or EFH 

would be negligible and indistinguishable from natural population variations. 

Other Factors 

Structure emplacements can act as fish attracting devices (FAD’s) 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 and to be caught around FAD’s. The attraction of pelagic 

highly migratory species to offshore structures will 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). 

WPA Proposed Action Analysis 

The routine impact effects of a WPA proposed action on coastal wetlands and coastal water quality, 

with the exception of accidental events, are analyzed in detail in Chapters 4.2.1.1.3.2 and 4.2.1.1.2.1 of 

the Multisale EIS, respectively. Collectively, the adverse impacts from these effects are called coastal 

environmental degradation. The effects of a WPA 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, 

respectively. Collectively, the adverse impacts from these effects are called marine environmental 

degradation in this SEIS. 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 each proposed action. 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 0-1 new gas processing plants projected in support of a 

WPA proposed action. 

Wetlands that could be impacted for some period of time or converted to open water are discussed in 

Chapter 4.2.1.1.3.2 of the Multisale EIS. A small amount of the routine dredging done in coastal areas 

will be directly or indirectly due to a proposed action. It is expected that coastal environmental 

degradation from a proposed action would have little effect on fish resources or EFH. Recovery of fish 

resources or EFH can occur from more than 99 percent, but not all, of the potential coastal environmental 
4-140 Central and Western Gulf of Mexico Multisale Supplemental EIS

degradation. Fish populations, if left undisturbed, will regenerate in one generation and most EFH can 

recuperate quickly, but the loss of wetlands as EFH could be permanent. At the expected level of effect, 

the resultant influence on fish resources or EFH from a WPA proposed action would be negligible and 

indistinguishable from natural population variations. 

Marine Environmental Degradation 

The Topographic Features Stipulation is discussed in Chapters 2.2.1.3.1 and 2.3.1.3.1 of the Multisale 

EIS. (The live bottom (Pinnacle Trend) features do not occur in the WPA). The application of the new 

category of Potentially Sensitive Biological Features in NTL 2004-G05 will also serve to prevent impacts 

to hard-bottom EFH habitat associated with topographic features that may lie outside previously defined 

No Activity Zones. For any activities associated with a proposed action, USEPA’s Region 6 will regulate 

discharge requirements for the WPA through their NPDES permits. 

The projected total number of platform installations resulting from a WPA proposed action is 28-41 

for all water depths (Table 3-3). Bottom disturbance from structure emplacement operations associated 

with a 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 in water depths <156 m (<512 ft) are removed by severing their pilings with 

explosives placed 5 m (16 ft) below the seafloor. It is projected that 10-16 structures in water depths 

<200 m (<656 ft) in the WPA will be removed using explosives as a result of a proposed action. It is 

expected that structure removals would have a negligible effect on fish resources because these activities 

kill only those fish proximate to the removal site. 

The projected length of pipeline installations for a WPA proposed action is 130-760 km (81-472 mi) 

for all water depths. Trenching for pipeline burial has the potential to adversely affect fish resources. 

Any affected population is expected to recover to predisturbance condition in one generation. At the 

expected level of impact, the resultant influence on fish resources would be negligible and 

indistinguishable from other natural population variations. 

The major sources of routine discharges to marine waters associated with a WPA proposed action are 

the temporary discharge of drilling muds and cuttings and the long-term discharge of produced-water 

effluent. Offshore discharges of drilling muds are expected to dilute to background levels within 1,000 m 

(3,280 ft) of the discharge point. Produced-water discharges contain components and properties 

potentially detrimental to fish resources. 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, 1997). 

It is expected that marine environmental degradation from a WPA 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 occur from 100 percent 

of the potential marine environmental degradation. Fish populations, if left undisturbed, will regenerate 

in one generation. Offshore live bottoms and topographic features are not expected to be impacted. 

Offshore discharges and subsequent changes to marine water quality will be regulated by USEPA NPDES 

permits. At the expected level of effect, the resultant influence on fish resources or EFH would be 

negligible and indistinguishable from natural population variations. 

Other Factors 

Structure emplacements can act as FAD’s 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 and to be caught around FAD’s. The attraction of pelagic highly migratory species 

to offshore structures will 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). 
Environmental and Socioeconomic Consequences 4-141 

Summary and Conclusion 

It is expected that coastal and marine environmental degradation from a CPA or WPA proposed 

action would have little effect on fish resources or EFH. The impact of coastal and marine environmental 

degradation is expected to cause an undetectable 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. At the expected 

level of impact, the resultant influence on fish resources would cause less than a 1 percent change in fish 

populations or EFH. As a result, there would be little disturbance to fish resources or EFH. 

The MMS has reexamined the analysis for impacts to fish resources and EFH presented in the 

Multisale EIS, based on the additional information presented above. No significant new information was 

found that would alter the overall conclusion that impacts to fish resources and EFH from routine 

activities associated with a CPA or WPA proposed action would be minimal to none. A proposed action 

is expected to result in less than a 1 percent decrease in fish resources and/or standing stocks or in EFH. 

It would require one generation for fish resources to recover from 99 percent of the impacts. Recovery 

from the loss of wetlands habitat would probably not occur. The 181 South Area is located in very deep 

water and limited activities in that area would not have any measurable additional impacts to fish 

resources or EFH for highly migratory species (the only managed species group that far offshore). 

Additional hard substrate habitat provided by structure installation in areas where natural hard bottom 

is rare will tend to increase fish populations. The removal of these structures will eliminate that habitat, 

except when decommissioning results in platforms being used as artificial reef material. This practice is 

expected to increase over time. 

4.1.11.3. Impacts of Accidental Events 

A detailed description of accidental impacts upon fish resources, EFH, and commercial fishing can be 

found in Chapter 4.4.10 of the Multisale EIS. The following is a summary of the information presented in 

the Multisale EIS, which incorporates new information found since publication of the Multisale EIS. 

Accidental events that could impact fish resources and EFH include blowouts and oil or chemical 

spills. Subsurface blowouts, though 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 within a 300-m (984-ft) radius from the blowout site, potentially affecting a limited number of 

fish in the immediate area. The majority of mobile deep-sea benthic or near-bottom fish taxa would be 

expected to leave (and not reenter) the area of a blowout before being impacted by the localized area of 

resuspended sediments. 

Resuspended sediments may clog fish gills and interfere with respiration. Settlement of resuspended 

sediments may directly smother deep-water invertebrates that serve as food resources. However, coarse 

sediment should be redeposited quickly within several hundred meters or feet of a blowout site. Finer 

sediments can be more widely dispersed and redeposited over a period of hours to days within a few 

thousand meters or feet depending on the particle size. 

Oil loss from a blowout is rare. 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, and are less of an environmental risk. Loss of gas well control does not 

release liquid hydrocarbons into the water. 

The risk of oil spills from a 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 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, through uptake of dissolved petroleum products through the gills and epithelium of 

adults and juveniles, and through the death of eggs and decreased survival of larvae (NRC, 1985 and 

2002). These mechanisms and historical examples of large oil spills are discussed at length in Chapter 

4.4.10 in the Multisale EIS. Impacts of oil spills on adult fish have generally been thought to be minimal. 

The NOAA, Office of Response and Restoration’s Internet site states, “Most often, fish either are 

unaffected by oil, or are affected only briefly” (USDOC, NOAA, 2006). Adult fish are likely to actively 
4-142 Central and Western Gulf of Mexico Multisale Supplemental EIS

avoid a spill, thereby limiting the effects and lessening the extent of damage (Baker et al., 1991; Malins et 

al., 1982; Maki et al., 1995). 

Oil produced from the 181 South Area is anticipated to be a heavier oil than is typically found in 

shallower areas of the Gulf and, thus, it is projected linger in the environment longer than oil containing 

more volatile fractions. The amount of additional production from this area, however, is not anticipated 

to increase the risk of an oil spill >500 bbl occurring. Oil spills originating in the 181 South Area will not 

impact inshore estuaries, because it is located about 130 mi (209 km) from the nearest shore. 

One remaining type of spill could result from the accidental release of large volumes of drilling muds. 

This has occurred on occasion in deep water where drilling risers have failed and synthetic drilling fluids 

contained in the riser escaped to the seafloor (Boland et al., 2004). In recent instances, 600-800 bbl of 

synthetic drilling fluids were released. The fates and effects of such large point-source releases have not 

been studied to date, but a new project is currently funded to do just that after the next event occurs, 

Synthetic-based Fluid Spill of Opportunity: Environmental Impact and Recovery (USDOI, MMS, in 

preparation (a)). Gallaway and Baubien (1997) did report an increased abundance of fish, 3-10 times that 

expected, around the Pompano platform at 565 m (1,854 ft). The increase is thought to be related to 

organic enrichment from synthetic drilling mud discharges that resulted in an increase in benthic animals 

the fish were likely feeding on. 

CPA Proposed Action Analysis 

The effect of accidental events from a 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, respectively, and in Chapter 

4.1.2.1.2 of this SEIS. 

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 a proposed action. Only 2-3 

blowouts are projected for the entire depth range of a CPA proposed action. A blowout with oil release is 

not expected to occur. The few blowouts that could occur in the CPA as part of a proposed action would 

cause limited impacts to localized areas. Given the exposure of the area to high levels of suspended 

sediments and the low probability that a large blowout would occur, blowouts are not expected to 

significantly affect future water quality (EFH). 

The potential causes, sizes, and probabilities of petroleum spills estimated to occur during activities 

associated with a CPA proposed action are discussed in Chapter 3.2.1 and are listed in Table 3-6 for 

offshore spills. Information on spill response and cleanup and persistence is contained in 

Chapter 3.2.1.5. 

The probabilities of various size offshore spills occurring over the life of a proposed action are listed 

in Table 3-6. For a CPA proposed action, 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 in Texas or Louisiana 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 4-14 and 4-16 of the Multisale 

EIS and in Figures 3-6 through 3-11 of this SEIS. The probability of an oil spill ≥1,000 bbl occurring 

and passing over Sonnier Bank is 3-5 percent as the result of a CPA proposed action over its 40-year life. 

As explained in Chapter 3.2.1, the incremental increase in oil production from the addition of the 181 

South Area is not expected to result in an overall increase in the numbers of oil spills ≥1,000 bbl likely to 

occur as a result of a CPA proposed action. Activity that would result from the addition of the 181 South 

Area would cause a negligible increase in the risk of a large spill occurring and contacting county and 

parish shorelines and specific sensitive biological features. 

There is a small risk of spills occurring during shore-based support activities. The great majority of 

these will be very small. 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 very 
Environmental and Socioeconomic Consequences 4-143 

small area and dissipate rapidly. A total of 46-102 coastal spills of all sizes as a result of a CPA proposed 

action over its 40-year life is estimated to occur. It is also assumed that a petroleum spill would 

occasionally contact and affect nearshore and coastal areas of migratory Gulf of Mexico fisheries. These 

species are highly migratory and would actively avoid the spill area.

The effect of petroleum spills on fish resources as a result of a proposed action is expected to cause 

less than a 1 percent decrease in fish resources or standing stocks of any population. At the expected 

level of impact, the resultant influence on fish populations within or in the general vicinity of the 

proposed lease sale area would be negligible and indistinguishable from natural population variations. 

Due to the extreme depth of the 181 South Area, the only managed fish species (and their pelagic 

EFH) are some of the highly migratory species including sharks, billfish, and tuna. Up to one additional 

structure is projected to be installed as a result of the addition of the 181 South Area. Any possible 

accidental events occurring from the very limited activity in the 181 South Area would cause negligible 

impacts and would not deleteriously affect fish resources or EFH. 

WPA Proposed Action Analysis 

The effect of accidental events from a WPA proposed action on coastal wetlands and coastal water 

quality is analyzed Chapters 4.4.3.2 and 4.4.2.1 of the Multisale EIS and in Chapter 4.1.2.1.2 of this 

SEIS. 

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 a proposed action. Only 1-2 

blowouts are projected for the entire depth range of a WPA proposed action. A blowout with oil release 

is not expected to occur. The few blowouts that could occur in the WPA as part of a proposed action 

would cause limited impacts to localized areas. Given the exposure of the area to high levels of 

suspended sediments and the low probability that a large blowout would occur, blowouts are not expected 

to significantly affect future water quality (EFH). 

The potential causes, sizes, and probabilities of petroleum spills estimated to occur during activities 

associated with a WPA proposed action are discussed in Chapter 3.2.1 and are listed in Table 3-6 for 

offshore spills. Information on spill response and cleanup and persistence is contained in 

Chapter 3.2.1.5. 

The probabilities of various size offshore spills occurring over the life of a WPA proposed action are 

listed in Table 3-6. For a WPA proposed action, there is a 31-46 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 in Texas or Louisiana 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 and passing over Stetson Bank is 2-4 

percent and the Flower Garden Banks is 4-7 percent as the result of a WPA proposed action over its 

40-year life. The biological resources of other hard/live bottoms in the Gulf of Mexico (EFH) would 

remain unharmed as spilled substances could, at the most, reach the seafloor in minute concentrations 

considering the great distances and time required for transportation from the deepwater areas of a WPA 

proposed action.

There is a small risk of spills occurring during shore-based support activities. The great majority of 

these will be very small. 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 very 

small area and dissipate rapidly. A total of 15-34 coastal spills of all sizes as a result of a WPA proposed 

action over its 40-year life is estimated to occur. It is also assumed that a petroleum spill would 

occasionally contact and affect nearshore and coastal areas of migratory Gulf of Mexico fisheries. These 

species are highly migratory and would actively avoid the spill area.
4-144 Central and Western Gulf of Mexico Multisale Supplemental EIS

The effect of petroleum spills on fish resources as a result of a proposed action is expected to cause 

less than a 1 percent decrease in fish resources or standing stocks of any population. At the expected 

level of impact, the resultant influence on fish populations within or in the general vicinity of the 

proposed lease sale area would be negligible and indistinguishable from natural population variations. 

Summary and Conclusion 

Accidental events resulting from oil and gas development in a CPA or WPA proposed action area 

have the potential to cause some detrimental effects on fisheries and EFH. A subsurface blowout would 

have a negligible effect on Gulf of Mexico fish resources. If spills due to a 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. The 

effect of proposed-action-related oil spills on fish resources is expected to cause less than a 1 percent 

decrease in standing stocks of any population. Historically, there have been no oil spills of any size that 

have had a long-term impact on fishery populations. 

The MMS has reexamined the analysis for impacts to fish resources and EFH presented in the 

Multisale EIS, based on the additional information presented above. No significant new information was 

found that would alter the overall conclusion that impacts to fish resources and EFH from routine 

activities associated with a CPA or WPA proposed action would be minimal to none. At the expected 

level of impact, the resultant influence on fish populations and EFH from a proposed action in the CPA or 

WPA would be negligible and indistinguishable from variations due to natural causes; however, wetland 

loss could occur due to a petroleum spill contacting inland areas. The proposed actions are expected to 

result in less than a 1 percent decrease in fish resources and/or standing stocks or in EFH. It would 

require one generation for fish resources to recover from 99 percent of the impacts. Recovery from the 

loss of wetlands habitat would probably not occur. Any possible accidental events occurring from the 

limited activity in the 181 South Area would not deleteriously affect fish resources or EFH. 

4.1.11.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts upon fish and EFH can be found in Chapter 4.5.10 of 

the Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

This cumulative analysis summary considers activities that could occur and adversely affect fish 

resources and EFH in the northern Gulf of Mexico during the 40-year analysis period. These activities 

include effects of the OCS Program (a proposed action, and prior 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 coastal environmental degradation; marine environmental degradation; commercial and 

recreational fishing techniques or practices; hypoxia; red or brown tides; hurricanes; removal of 

production structures; petroleum spills; subsurface blowouts; pipeline trenching; and offshore discharges 

of drilling muds and produced waters. All of these subjects are discussed at length in Chapter 4.5.10 of 

the Multisale EIS. 

The most serious impact to coastal EFH is the cumulative effects on wetlands that are occurring at an 

ever-increasing rate as the Gulf Coast States’ populations increase. The cumulative impacts of pipelines 

to wetlands are described in Chapter 4.5.3.2 of the Multisale EIS. Canal dredging primarily 

accommodates commercial, residential, and recreational development. Additional details of cumulative 

wetlands loss, including impacts from major storms, such as the hurricanes of 2005, are detailed in 

Chapter 4.5.3.2 of the Multisale EIS. The incremental contribution of a CPA or WPA proposed action 

would be a very small part of the cumulative impacts to wetlands. 

The coastal waters of Texas, Louisiana, Mississippi, Alabama, and the Florida Panhandle are 

expected to continue to experience nutrient overenrichment, periods of low-dissolved oxygen, and toxin 

and pesticide contamination, resulting in the loss of both commercial and recreational uses of the affected 
Environmental and Socioeconomic Consequences 4-145 

waters. Fish kills, shellfish-ground closures, and restricted swimming areas would likely increase in 

numbers over the next 30-40 years (although some areas have seen improvements and reopened for 

swimming, such as Lake Pontchartrain). The incremental contribution of a proposed action would be a 

very small part of the cumulative impacts to coastal water quality. Localized, minor degradation of 

coastal water quality is expected from a 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 very small amount of dredging would occur 

as a result of a CPA or WPA proposed action. 

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. The impacts of the 2005 hurricanes to the 

shallowest topographic features were investigated in 2006 and indicated some physical damage from 

wave energy to a large portion of the shallow habitat on one pinnacle at Sonnier Bank and to numerous 

coral heads at the Flower Garden Banks. 

The OCS-related cumulative activities could impact the biological resources and the structure of live 

bottoms by 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). The Live Bottom (Pinnacle Trend) Stipulation (in the CPA) and the Topographic Features 

Stipulation (in the CPA and WPA) would prevent most of the potential impacts on live-bottom 

communities and EFH from the OCS Program and from bottom-disturbing activities (anchoring, structure 

emplacement and removal, and pipeline trenching), operational offshore waste discharges (drilling muds 

and cuttings, and produced waters), and blowouts. 

Surface oil spills from OCS Program-related activities would have the greatest chance of impacting 

high-relief live bottoms (includes topographic features and pinnacles) located in depths <20 m (66 ft) 

(mostly sublethal impacts); however, all pinnacle features are located deeper than 20 m (66 ft); the 

shallowest described is below 60 m (200 ft). Only four named topographic features reach depths of 

<20 m (66 ft): East and West Flower Garden Banks, Sonnier Bank, and Stetson Bank. Subsurface spills 

(pipeline spills) could cause localized, sublethal (short-term, physiological changes) impacts on the live 

bottoms; however, such events would be highly unlikely since the protective lease stipulations would 

prevent oil pipelines from being installed in the immediate vicinity of high-relief live bottoms. The 

impact of OCS-related activities on the live bottoms of the cumulative activity area would probably be 

slight because community-wide impacts should not occur. 

A proposed action would add slightly to the overall offshore water quality degradation through the 

disposal of offshore operational wastes and sedimentation/sediment resuspension. Other activities of a 

proposed action potentially contributing to regional impacts would be the effects of petroleum spills and 

anchoring. The extent of these impacts would be limited by the implementation of the protective lease 

stipulations and the depths of all but three high-relief, live-bottom habitats (>20 m or 66 ft). The 

incremental contribution of a CPA or WPA proposed action to the cumulative impacts on fisheries and 

EFH would be small. 

Municipal, agricultural, and industrial coastal discharges and land runoff would impact the health of 

marine waters. Coastal sources are assumed to exceed all other sources, with the Mississippi River 

continuing to be the major source of contaminants to the north-central Gulf of Mexico area. Even with 

the increased understanding of the agricultural sources of nutrients moving down the Mississippi River 

and causing the hypoxic areas off Louisiana every year, there has been little accomplished leading to 

reductions in those sources. In the case of mercury, the amount of mercury entering the Gulf of Mexico 

from all offshore oil and gas facilities contributes only 0.3 percent of the mercury coming from the air and 

Mississippi River (Neff, 2002). 

Offshore vessel traffic and OCS operations would contribute in a small way to regional degradation 

of offshore waters through spills and waste discharges. All spill incidents (OCS and others) and activities 

increasing water-column turbidity are assumed to cause localized water quality changes for up to 3 

months for each incident. The incremental contribution of a CPA or WPA proposed action to degradation 

of marine water quality would be small. 
4-146 Central and Western Gulf of Mexico Multisale Supplemental EIS

It is expected that coastal and marine environmental degradation from the OCS Program and nonOCS activities would affect fish populations and EFH. The impact of coastal and marine degradation 

from both OCS Program and non-OCS activities is expected to cause no more than a 10 percent decrease 

in fish populations or EFH. The incremental contribution of a CPA or WPA proposed action to these 

cumulative impacts would be small and likely undetectable. 

Fishing 

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. 

Competition between large numbers of commercial and recreational fishermen for a given fishery 

resource, as well as natural phenomena such as weather, hypoxia, and red or brown tides, may reduce fish 

resource standing populations. The impact of overfishing on fish resources can cause a measurable 

decrease in populations. Fishing techniques such as trawling or purse seining, when practiced 

nonselectively, may reduce the standing stocks of the desired target species as well as significantly impact 

species other than the target. Management practices for many fisheries stocks have resulted in a number 

of successes in recent years. It is expected that overfishing of some targeted species and trawl fishery 

bycatch would adversely affect fish resources; however, fishery management councils are moving toward 

additional new regulations and restrictions to address overfishing of most managed species. At the 

estimated level of effect, if overfishing were to occur, the resultant influence on fish resources would be 

expected to be substantial and easily distinguished from effects due to natural population variations. 

Structure Removals 

Structure removals would result in artificial habitat loss. It is estimated that 1,072-1,148 structures 

would be removed as a result of the OCS Program in the WPA and 4,925-4,949 structures would be 

removed in the CPA throughout all water depths during the 40-year analysis period (Tables 4-5 and 4-6 of 

the Multisale EIS). These numbers also represent additional installations in the same 40-year period. It is 

expected that structure removals would have a major effect on fish resources near the removal sites when 

explosives are used. 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). 

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 were to occur in coastal bays, 

estuaries, or 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. For 

eggs and larvae contacted by spilled diesel, the effect is expected to be lethal. 

The numbers and sizes of coastal spills are presented in Table 4-13 of the Multisale EIS. About 95 

percent of these spills are projected to be from non-OCS-related activity. Of coastal spills <1,000 bbl, the 

assumed size is 5 bbl; therefore, the great majority of coastal spills would affect a very small area and 

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. 

One large (≥1,000 bbl) offshore spill is projected to occur annually from the Gulfwide OCS Program 

(Table 4-13 of the Multisale EIS). A total of 1,500-1,800 smaller offshore spills (<1,000 bbl) are 

projected annually Gulfwide. Of these, 450-500 would originate from OCS Program sources. Chapter 

4.3.1.2 in the Multisale EIS describes projections of future spill events in more detail. The OCS-related 

spills in the cumulative area are expected to cause a 1 percent or less decrease in fish resources. The 

impact of non-OCS-related spills in this area is expected to cause a 10 percent or less decrease in fish 

resources. 
Environmental and Socioeconomic Consequences 4-147 

Sediment Resuspension, Muds and Cuttings 

Subsurface 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 

(7 blowouts per 1,000 well starts; <10% would result in some spilled oil). Considering the entire OCS 

Program during the 40-year analysis period, it is projected that there would be 63-75 blowouts for all 

water depths in the WPA and 169-197 blowouts in the CPA. Sandy sediments would be quickly 

redeposited within 400 m (1,312 ft) of a blowout site, and finer sediments would be widely dispersed and 

redeposited within a few thousand meters or feet over a period of 30 days or longer. These events are 

expected to have a negligible impact on fish populations. It is expected that the infrequent subsurface 

blowout that may occur on the Gulf of Mexico OCS would have a negligible effect on offshore fish 

resources 

Sediment would be resuspended during the installation of pipelines. A total of 2,340-9,850 km 

(1,454-6,120 mi) of pipeline is projected to be installed in the WPA and 2,539-18,790 km (1,578-11,676 

mi) is projected in the CPA (only in the water depth category of <60 m or 200 ft) during the 40-year 

analysis period. The effect on fish resources from pipeline trenching is expected to be minimal and to 

cause a 1 percent or less decrease in standing stocks. 

Drilling-mud discharges contain chemicals toxic to marine fishes; however, this is only at 

concentrations four or five orders of magnitude higher than those found more than a few meters or feet 

from the discharge point. Offshore discharges of drilling muds would dilute to very near background 

levels within 1,000 m (3,280 ft) of the discharge point and would have a negligible effect on fisheries. 

Biomagnification of mercury in large fish high in the food chain is a problem in the Gulf of Mexico 

(sometimes associated with drilling discharges in the press), but the bioavailability and any association 

with trace concentrations of mercury in discharged drilling mud has not been demonstrated. Numerous 

studies have concluded that platforms do not contribute to higher mercury levels in marine organisms.

Produced Water 

Produced-water discharges contain components and properties detrimental to fishery resources. 

Limited petroleum and metal contamination of sediments and the upper water column would occur out to 

several hundred meters or feet downcurrent from the discharge point. Offshore discharges of produced 

water would disperse, dilute to very 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 would be regulated by a USEPA NPDES 

permits. 

Hurricanes 

The impacts of the 2005 hurricanes were discussed at length in Chapter 4.5.10 of the Multisale EIS. 

No significant storms have occurred in the Gulf of Mexico since that time. As a cumulative impacting 

factor, hurricanes certainly had a substantial impact on Gulf Coast fisheries in 2005 (primarily coastal 

resources such as oysters) and other storms of similar intensity are certainly a possibility in the future. 

Future impacts to actual offshore fish resources and EFH could be expected to be minimal as they were in 

the cases of Hurricanes Katrina and Rita. Impacts to general coastal infrastructure and commercial 

fishing facilities would also be expected to be substantial in the face of similar strength storms in the 

future. 

LNG Facilities 

One additional cumulative impacting factor has been recently introduced as a possible significant 

impact to fisheries and offshore habitats in the future. This is the possibility of multiple offshore facilities 

for the offloading and regasification of liquefied natural gas (LNG) and the potential use of Gulf seawater 

for the warming process to convert the cold LNG to gas (known as the “open loop” technique). 

Additional details of potential impacts are discussed in Chapter 4.5.10 of the Multisale EIS. Only one 

LNG port facility has been fully approved and is operational at the time of this writing (Gulf Gateway 
4-148 Central and Western Gulf of Mexico Multisale Supplemental EIS

Energy Bridge). This facility consists of a submerged turret and the first delivery was made in March 

2005. 

The true impacts of an open-loop system have yet to be determined, primarily due to the lack of 

information regarding the seasonal and vertical stratification of fish eggs and larva in the water column in 

relationship to open-loop water intakes. At this point in time, the cumulative impacts from future LNG 

facilities using an open-loop system will not be a consideration due to the likely continued permitting 

freeze of open-loop designs. 

Other 

Similar to the discussion of impacts to deepwater biological resources, an additional source of 

potentially huge impacts to fisheries and EFH should be mentioned—those associated with global climate 

change. This subject is too uncertain to discuss in detail at this time due to the wide-ranging scenarios 

from minor and fluctuating temperature changes with associated minimal sea-level rise of a few 

centimeters or inches over the next several decades to extremes of sea-level rise of 6 m (20 ft) and more. 

This higher level of impact is theoretically within the 40-year timeframe of the cumulative scenario 

analysis and would obviously have overwhelming impacts to shallower coastal fishery ecosystems. 

Water column depths overlying habitats on the shelf edge, such as the Flower Garden Banks, could 

increase by 35 percent, potentially impacts on corals. Proposed regionwide methods to sequester carbon 

(or other large-scale actions to reduce atmospheric CO2) are likely in the distant future. Many of the 

scenarios include severe impacts of their own, such as deep-sea pH changes. 

Summary and Conclusion 

Activities resulting from the OCS Program and non-OCS events in the northern Gulf of Mexico have 

the potential to cause cumulative detrimental effects on fish resources and EFH. Impact-producing 

factors of the cumulative scenario that are expected to substantially affect fish resources and EFH include 

coastal and marine environmental degradation, overfishing, and to a lesser degree, coastal petroleum 

spills and coastal pipeline trenching. 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 a proposed action’s impacts on fish resources and EFH to the 

cumulative impact is small (as analyzed in Multisale EIS Chapters 4.2.1.1.8 for the WPA, 4.2.2.1.10 for 

the CPA, and 4.4.10 for accidental impacts). The effects of impact-producing factors (i.e., coastal and 

marine environmental degradation, petroleum spills, subsurface blowouts, pipeline trenching, and 

offshore discharges of drilling muds and produced waters) related to a CPA or WPA proposed action are 

expected to be negligible (resulting in less than a 1% decrease in fish populations or EFH) and almost 

undetectable among the other cumulative impacts. Even with consideration of an extreme year of major 

hurricane impacts to coastal wetlands in 2005, the cumulative impact of a CPA or WPA proposed action 

is expected to be negligible and undetectable. 

The cumulative impact is expected to result in a less than 10 percent decrease in fish resource 

populations or EFH. It would require 2-3 generations for fishery resources to recover from 99 percent of 

the impacts. Recovery cannot take place from habitat loss (without unprecedented coastal reconstruction 

and wetlands restoration on an immense scale). 

No significant new information was found that would alter the conclusion as described in the 

Multisale EIS that the incremental contribution of a CPA or WPA proposed action’s impacts on fish 

resources and EFH to the cumulative impact is minimal. Furthermore, activity projected to result from 

the addition of the 181 South Area is negligible compared with total OCS activity, and it is not likely to 

result in a significant contribution to cumulative impacts. 

4.1.12. Commercial Fishing 

The MMS has reexamined the analysis for commercial fishing presented in the Multisale EIS, based 

on the additional information presented below and the addition of the 181 South Area to the proposed 

CPA sale area. New fishery statistics analyzed and the addition of the 181 South Area do not change the 
Environmental and Socioeconomic Consequences 4-149 

conclusion in the Multisale EIS that impacts on the commercial fisheries from the proposed action would 

be minimal. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Routine activities in the CPA and WPA such as seismic surveys 

and pipeline trenching would cause negligible impacts and will 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 either a CPA or a WPA proposed 

action are anticipated to be minimal. Commercial fishermen are anticipated to avoid the area of a well 

blowout or an oil spill. Any impact on catch or value of catch would be insignificant compared with 

natural variability. The incremental contribution of a 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. 

4.1.12.1. Description of the Affected Environment 

A detailed description of commercial fishing can be found in Chapter 3.3.1 of the Multisale EIS. The 

following is a summary of the information presented in the Multisale EIS, which incorporates new 

information found since the publication of the Multisale EIS. 

Commercial fishing regulations are very detailed and change on a regular basis depending on a 

variety of factors including stock assessment and catch statistics. Changes can occur on short notice, 

especially time closures based on allowable catch. Federal fishing regulations are not always the same as 

State fishing regulations. The Gulf of Mexico Fishery Management Council (GMFMC) provides the 

current information on commercial and recreational fishing rules for U.S. Federal waters of the Gulf of 

Mexico. The most recent rule updates were published in April 2007 (GMFMC, 2007). 

The 181 South Area is located nearly 130 mi (209 km) from the nearest coastline. There are no 

special regulations designated within this area that would indicate any difference in the commercial 

fisheries that what is found in adjacent areas of the Gulf as described in the Multisale EIS. 

Annual and monthly commercial fisheries landings statistics are available on the NMFS Internet site 

(USDOC, NMFS, 2007e). The following information is derived from various analyses of the available 

data queries at this site. The most recent, complete information on landings and value of fisheries for the 

U.S. was compiled by NMFS for 2006. Data from the 2004 data compilation is available in Chapter 3.3.1 

of the Multisale EIS, and although the numbers for 2006 are slightly different for the total catch and its 

value, the general trends are unchanged. During 2006, commercial landings of all fisheries in the Gulf of 

Mexico totaled nearly 1.3 billion pounds, valued at nearly $663 million (USDOC, NMFS, 2007e). The 

Gulf of Mexico provides over 32 percent of the commercial fish landings by weight and 25 percent of all 

catch by monetary value in the continental U.S. (excluding Alaska) on an annual basis. 

Menhaden, with landings of about 899 million pounds and valued at $41.2 million, was the most 

important Gulf of Mexico species in terms of quantity landed during 2006. Landings increased by 83 

million pounds in the Gulf Coast States compared with landings in 2005. Shrimp, with landings of nearly 

246 million pounds and valued at about $354 million, was the most important Gulf of Mexico species in 

terms of value landed during 2006. The 2006 Gulf of Mexico oyster fishery accounted for nearly 90 

percent of the national total, with landings of 19.5 million pounds of meats valued at about $62 million. 

The Gulf of Mexico blue crab fishery accounted for about 41 percent of the national total, with landings 

of 66 million pounds valued at about $42.5 million (USDOC, NMFS, 2007e). 

Texas’s total commercial landings in 2006 were about 117 million pounds valued at over $197 

million. Shrimp was the most valuable species group landed, with all shrimp species combined coming to 

a total weight of over 104 million pounds valued at over $167 million. In addition, during 2006, the 

Eastern oyster, red snapper, and black drum each accounted for landings valued at over $2 million. Blue 

crab landings were over $1.9 million (USDOC, NMFS, 2007e). 

Louisiana’s total commercial landings in 2006 were 911 million pounds valued at $269 million. 

Shrimp was the most important fishery landed, with about 135 million pounds valued at $145 million. In 
4-150 Central and Western Gulf of Mexico Multisale Supplemental EIS

addition, during 2006, the following marine species each accounted for landings valued at over $2 

million: Atlantic menhaden, blue crab, Eastern oyster, red snapper, and yellowfin tuna (USDOC, NMFS, 

2007e). 

Mississippi’s total commercial landings in 2006 were 221.8 million pounds valued at nearly $22 

million. Shrimp was the most important fishery landed, with 8.5 million pounds valued at $11.8 million. 

In addition, during 2006, the Atlantic menhaden catch was valued at $8.4 million (USDOC, NMFS, 

2007e). 

Alabama’s total commercial fishery landings for 2006 were 33.7 million pounds valued at $49 

million. Shrimp was the most important fishery, with about 23.9 million pounds landed valued at about 

$39.2 million. In addition, during 2006, the following species each accounted for landings valued at over 

$500 thousand: blue crab, Eastern oyster, sharks, red snapper, striped mullet, and Spanish mackerel 

(USDOC, NMFS, 2007e). 

Total commercial landings for the west coast of Florida in 2006 were 69.7 million pounds valued at 

$146.8 million. Shrimp was the most important fishery landed, with 17 million pounds valued at $ 37.4 

million. In addition, during 2006, the following species each accounted for landings valued at over $4 

million: stone crab, blue crab, Eastern oyster, red grouper, gag, and Caribbean spiny lobster (USDOC, 

NMFS, 2007e) 

Effects from the 2005 hurricanes have had substantial impacts on the oyster industry. It was initially 

believed that the 2005 hurricanes would have devastating effects on the health and numbers of offshore 

fish stocks in the Gulf of Mexico. Results of surveys conducted by NOAA indicate that shrimp and 

bottom fish catch per unit effort were within the range of past interannual variations (USDOC, NMFS, 

2007b). The commercial fisheries landings of the Central Gulf Coast were drastically impacted by 

Hurricanes Rita and Katrina because of the severe impact on coastal port facilities and fishing vessels. 

These data are discussed in the Chapter 3.3.1 of the Multisale EIS. 

In July 2007, NMFS published a preliminary report for 2006 on U.S. commercial and recreational 

fisheries (USDOC, NMFS, 2007e). Despite Louisiana’s drop in the number of landings following 

Hurricane Katrina, Louisiana still remains the leader in Gulf landings, followed by Mississippi, Texas, 

Florida (West Coast), and Alabama. Kirkham (2007) states “though the migration into other state waters 

is not new, the post-storm NOAA statistics suggest a new trend: Fishers are taking more seafood from 

Louisiana waters than what is brought in to Louisiana ports” and “whether the trends will continue is up 

for debate. As docks, ramps, and icehouses in Louisiana come back online -- about 85 percent are back, 

according to a recent Wildlife and Fisheries report -- fishers will be able to bring their catch back to prestorm ports and buyers” (Louisiana Dept. of Wildlife and Fisheries, 2007b). 

Surveys conducted by NMFS after Hurricanes Katrina, Rita, and Wilma in 2005 showed clearly that 

the stock of all commercially important fish and invertebrate species were within interannual variation. A 

history of the problems experienced by the shrimp (i.e., white, brown, red, and seabob), crab (i.e., blue 

and stone), spiny lobster, and finfish industry and stocks are presented in Chapter 3.3.1 of the Multisale 

EIS. 

Stock Status 

The NMFS reports each year to the Congress and Fishery Management Councils on the status of all 

fish stocks in the nation. Nationwide, 81 percent of the fish stocks and stock complexes with known 

status are not subject to overfishing and 72 percent of the stocks and stock complexes with known status 

are not overfished. (“Overfished” is defined as a stock size that is below a prescribed biomass threshold. 

“Overfishing” is harvesting at a rate above a prescribed fishing mortality threshold.) The NMFS has 

increased the number of assessed stocks over the last several years, and this trend will continue. In 2004, 

NMFS completed 84 stock assessments, of which 10 were for stocks not previously assessed. 

The number of commercial species designated to be overfished has been reduced from previous years. 

In 2006, only two major stock groups were overfished in the Gulf of Mexico: red snapper and greater 

amberjack. No other species were approaching overfished status (USDOC, NMFS, 2007b). A history of 

fish species considered overfished since 2001 is presented in Chapter 3.3.1 of the Multisale EIS. 
Environmental and Socioeconomic Consequences 4-151 

4.1.12.2. Impacts of Routine Events 

Background/Introduction 

The detailed description of possible impacts on commercial fishing from routine activities associated 

with a CPA or WPA proposed action is given in Chapters 4.2.2.1.11 and 4.2.1.1.9 of the Multisale EIS, 

respectively. Because the 181 South Area is nearly 130 mi (209 km) from the nearest shore, it is not 

expected to contribute significantly to the indirect inshore impacts on fisheries discussed below. 

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. 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, which is lethal to fish that have internal air chambers (swim bladders), are 

demersal, or are in close association with the structure. Intense sounds generated by seismic surveys 

affect the spatial distribution of fish during and for some period following exposure. 

The most commonly discharged offshore wastes are drill mud and produced water. Drill muds 

contain metals such as mercury and cadmium, which are toxic to fishery resources. Produced waters 

commonly contain brine, trace metals, hydrocarbons, organic acids, and radionuclides, all of which can be 

toxic to fisheries resources. 

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 Chapters 4.2.1.1.2.1 and 4.2.2.1.2.1 of the Multisale 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 muds. 

CPA Proposed Action Analysis 

The routine activities associated with a 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 a CPA proposed action range from 28 to 

40. 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 water depths of <200 m (656 ft), the area of 

concentrated bottom trawling, is 22-24, thus potentially excluding 4,246-4,632 ac (<0.01%) from the total 

area available to trawling. 

Commercial fisheries conflicts with platforms in water deeper than 200 m (656 ft), including those 

that may be installed in the 181 South Area, are limited to the longline fishery. Surface-drifting longlines 
4-152 Central and Western Gulf of Mexico Multisale Supplemental EIS

may contact a deepwater platform if not set an appropriate distance from the surface-piercing structure. 

The area of surface-piercing structure is very small in relation to the total area available to longliners. 

From 50 to 850 km (31 to 528 mi) of pipeline are anticipated to be laid in water depths <60 m 

(200 ft). In water depths beyond 60 m (200 ft), including the acreage in the 181 South Area, the projected 

length of pipeline is 90-1,355 km (56-842 mi). Gear loss from hang-on pipelines is mitigated by funds 

provided by the Fisherman’s Compensation Fund. Because of pipeline burial requirements, it is assumed 

that installed pipelines will seldom conflict with bottom trawling activities in water depths <60 m (200 ft) 

and will not conflict with deeper waters, including water depths encountered in the 181 South Area. 

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 18-20 removals will result in the CPA in water 

depths <200 m (656 ft) as a result of a proposed action, making approximately 3,474-3,860 ac available 

again for commercial fishing. It is expected that structure removals will have a negligible impact on 

commercial fishing because of the inconsequential number of removals and the consideration that 

removals kill primarily those fish associated with the platforms. 

Seismic surveys will occur in both shallow and deep waters of the CPA, including the 181 South 

Area. Seismic survey vessels are of temporary presence in any commercially fished area of the CPA. 

Temporal and spatial distributions of commercial species are not affected in adjacent areas. 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. 

Produced waters and drill muds are discharged in shallow and deep waters of the CPA, including the 

the 181 South Area. Studies of drill muds and produced waters from platforms show that the plume 

disperses rapidly in both cases and does not pose a threat to commercial fisheries. 

Indirect impacts detailed above from offshore operations have an impact on commercial fishery 

resources that cannot be discerned from direct impacts of inshore activities. Indirect impacts from the 

181 South Area are negligible because of its distance from the nearest shoreline (130 mi or 209 km). 

WPA Proposed Action Analysis 

The routine activities associated with a WPA 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 a WPA proposed action range from 28 to 

41. 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 of 

concentrated bottom trawling, is 23-33, thus potentially excluding 4,439-6,369 ac (<0.01%) 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 laid in the WPA in water depths <60 m (200 ft) 

is from 60 to 420 km (37 to 261 mi). In water depths beyond 60 m (200 ft), the projected length of 

pipeline is unavailable. Because of pipeline burial requirements, it is assumed that installed pipelines will 

seldom conflict with bottom trawling activities in water depths <60 m (200 ft), and it will 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 15-24 removals will result in the WPA in water 

depths <200 m (656 ft) as a result of a proposed action, making approximately 3,667-4,632 ac available 

again for commercial fishing. It is expected that structure removals will have a negligible impact on 

commercial fishing because of the inconsequential number of removals and the consideration that 

removals kill primarily those fish associated with the platforms. 

Seismic surveys will occur in both shallow and deep waters of the WPA. Seismic survey vessels are 

of temporary presence in any commercially fished area of the WPA. Temporal and spatial distributions 

of commercial species are not affected in areas adjacent to seismic surveys. The locations and schedules 
Environmental and Socioeconomic Consequences 4-153 

of seismic surveys are published in the USCG’s Local Notice to Mariners. Seismic surveys have a 

negligible impact on commercial fisheries. 

Produced waters and drill muds are discharged in shallow and deep waters of the WPA. Studies of 

drill muds and produced waters from platforms show that the plume disperses rapidly in both cases and 

does not pose a threat to commercial fisheries. 

Indirect impacts detailed above from offshore operations have an impact on commercial fishery 

resources that cannot be discerned from direct impacts of inshore activities. 

Summary and Conclusion 

Routine activities such as seismic surveys and pipeline trenching in the CPA and WPA would cause 

negligible impacts and will not deleteriously affect commercial fishing activities. Seismic surveys are not 

expected to cause long-term or permanent displacement of any listed species from critical 

habitat/preferred habitat or to result in the destruction or adverse modification of critical habitat or 

essential fish habitat. Operations such as production platform emplacement, underwater OCS 

impediments, and explosive platform removal would cause slightly greater impacts on commercial 

fishing, although their effects are localized and temporary. Commercial fisheries conflicts with platforms 

in water deeper than 200 m (656 ft), including those installed in the 181 South Area, are limited to the 

longline fishery. The area of surface-piercing structure in this area is, however, very small in relation to 

the area available to longliners. Indirect impacts to inshore habitats are negligible and indistinguishable 

from direct impacts of inshore activities on commercial fisheries. 

The MMS has reexamined the impacts of CPA and WPA activities on the commercial fisheries 

resources. A search was conducted for new information published since completion of the Multisale 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. 

Commercial catches by species and by State have been updated in Chapter 4.1.12.1, as have the 

impacts of the 2005 hurricanes on fish and fish habitat from recent reports (USDOC, NMFS, 2007e 

and f). Also included in the new information examined was the inclusion of the 181 South Area to the 

analysis. New information was not significantly different from that provided in the Multisale EIS and 

therefore no information was found that would alter the conclusion in the Multisale EIS that impacts on 

the commercial fisheries from routine activities associated with a CPA or WPA proposed action would be 

minimal. 

4.1.12.3. Impacts of Accidental Events 

Background/Introduction 

The description of possible impacts on commercial fisheries resulting from accidental events 

associated with a WPA or a CPA proposed action is presented in detail in Chapter 4.4.10 of the Multisale 

EIS. Accidental events that would impact commercial fisheries include subsurface offshore blowouts and 

oil spills, both inshore and offshore. 

A subsurface blowout event, although highly unlikely, has the potential to affect fish within a few 

hundred meters or feet of the blowout. A blowout at the seafloor can cause a crater that might interfere 

with longlining in the near vicinity or cause a limited 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, will fall out of the water column quickly, and finer sediments are redistributed by 

currents and settle out over a larger area. 

Oil spills are rare from a blowout. Most product loss from blowouts is natural gas, primarily 

methane, which rapidly dissolves in the water column or escapes into the air. 

The risk of oil-spill events as a result of a CPA or WPA 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 discussed 

at length in Chapter 4.4.10 of the Multisale EIS. 
4-154 Central and Western Gulf of Mexico Multisale Supplemental EIS

Oil has the potential to affect finfish through direct ingestion of hydrocarbons or ingestion of 

contaminated prey, through uptake of dissolved petroleum products through the gills and epithelium of 

adults and juveniles, and through the death of eggs and decreased survival of larvae (NRC, 1985 and 

2002). All of these mechanisms are discussed at length in Chapter 4.4.10 of the Multisale EIS. 

Oil spilled in the offshore areas is usually localized and has a very low probability of reaching coastal 

areas that serve as nursery ground for many commercial fish. Much of the oil volatilizes or is dispersed 

by currents in the offshore environment. 

Oil produced from the 181 South Area is anticipated to have a high concentration of heavy 

hydrocarbon compounds and, thus, it is projected to linger in the environment longer than oil from other 

areas composed of more volatiles. As explained in Chapter 3.2.1, the incremental increase in oil 

production from the addition of the 181 South Area is not expected to result in an overall increase in the 

numbers of oil spills ≥1,000 bbl likely to occur as a result of a CPA proposed action. Because it is 

located about 130 mi (209 km) from the nearest shore, oil spills from the 181 South Area would not 

impact inshore estuaries. 

CPA Proposed Action Analysis 

The accidental events that would impact commercial fisheries include well blowouts, primarily gas 

well blowouts and oil spills. 

Impacts of gas well blowouts on commercial fisheries are very localized and limited. Cratering and 

sediment redistribution would affect only the area within a few hundred yards or meters of the blowout. 

Commercial fishermen would avoid fishing any cratered area that would interfere with longlining. 

Commercial fishermen would also actively avoid the area of a spill. Fish flesh tainting (oily tasting 

fish), closure of an area due to tainting, or the perception of tainting commercial catches may prevent 

fishermen from working in an area, which could decrease commercial landings value or catch. At the 

expected level of impact, the impact on commercial fisheries from a CPA proposed action would not be 

perceptible against natural background variation. 

As explained in Chapter 3.2.1, the incremental increase in oil production from the addition of the 

181 South Area is not expected to result in an overall increase in the numbers of oil spills ≥1,000 bbl 

likely to occur as a result of a CPA proposed action. If a spill were to occur, however, the higher 

concentration of heavy hydrocarbons would potentially cause the oil to linger in the environment longer 

than lighter crude oil. This might result in a slightly larger area of affected environment. The effect on 

catch or value of commercial species, however, is not anticipated to be large enough to discern from 

natural population variability. 

WPA Proposed Action Analysis 

The accidental events that would impact commercial fisheries include well blowouts, primarily gas 

well blowout and oil spills. 

Impacts of gas well blowouts on commercial fisheries are very localized and limited. Cratering and 

sediment redistribution would affect only the area with a few hundred yards or meters of the blowout. 

Commercial fishermen would avoid fishing any cratered area that would interfere with longlining. 

Commercial fishermen would also actively avoid the area of a spill. Fish flesh tainting (oily tasting 

fish), closure of an area due to tainting, or the perception of tainting commercial catches may prevent 

fishermen from working in an area, which could decrease commercial landings value or catch. At the 

expected level of impact, the impact on commercial fisheries from a WPA proposed action would not be 

perceptible against natural background variation. 

Summary and Conclusion 

In summary, the potential impacts from accidental events, a well blowout or an oil spill, associated 

with either a CPA or WPA 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 the value of catch 

would be insignificant compared with natural variability. 

An increased risk of a large oil spill (>1,000 bbl) occurring is not anticipated; therefore, the inclusion 

of the 181 South Area is anticipated to have minimal effects on commercial fisheries (longliners). 
Environmental and Socioeconomic Consequences 4-155 

The new information on commercial catches and their value since 2005 were considered, as well as 

the inclusion of the 181 South Area. New information was not significantly different from that provided 

in the Multisale EIS and therefore no information was found that would alter the conclusions in the 

Multisale EIS that impacts on the commercial fisheries from accidental events associated with a CPA or 

WPA proposed action would be minimal. 

4.1.12.4. 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. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

Specific types of impact-producing factors considered in the cumulative analysis include commercial 

fishing techniques or practices, hurricanes, installation of production platforms, underwater OCS 

obstructions, production platform removals, seismic surveys, petroleum spills, subsurface blowouts, 

pipeline trenching, and offshore discharges of drilling muds and produced waters. 

Competition between large numbers of commercial fishermen, between commercial operations 

employing different fishing methods, and between commercial and recreational fishermen for a given 

fishery resource, as well as natural phenomena such as hurricanes, hypoxia, and red or brown tides, may 

impact commercial fishing activities. Fishing techniques such as trawling, gill netting, or purse seining, 

when practiced nonselectively, may reduce the standing stocks of the desired target species as well as 

significantly impact species other than the target. In addition, continued fishing of most commercial 

species at the present levels may result in rapid declines in commercial landings and the eventual failure 

of certain fisheries. Finally, hurricanes may impact commercial fishing by damaging gear and shore 

facilities and by dispersing resources over a wide geographic area. The availability and price of key 

supplies and services, such as fuel, can also affect commercial fishing. 

Seismic surveys will occur in both shallow and deepwater areas of the Gulf of Mexico. Usually, 

fishermen are precluded from a very small area for several days. This should not significantly impact the 

annual landings or the value of landings for commercial fisheries in the Gulf. Gulf of Mexico species can 

be found in many adjacent locations, and Gulf commercial fishermen do not fish in one locale. 

The potential causes, sizes, and probabilities of petroleum spills that could occur during activities 

associated with a CPA or WPA proposed action are discussed in detail in Chapter 4.3.1. One large 

(≥1,000 bbl) offshore spill is estimated to occur annually from all sources Gulfwide. The impact of OCSrelated spills in the cumulative area is not expected to cause a discernible decrease in commercial catch. 

The impact of non-OCS-related spills in this area is not expected to cause a decrease in commercial 

fishing local to the spill area. At the expected level of impact, the resultant influence on commercial 

fishing, landings, or the value of those landings is not expected to be distinguished from natural 

population variations. 

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 (6 blowouts per 1,000 well starts; <10% would result in some spilled oil). 

Blowouts can resuspend sediment locally, and natural gas well blowouts release methane into the water 

column. Methane is quickly dispersed from the water column. 

Pipeline trenching also has the potential to affect commercial fisheries as a result of sediment 

suspension. Sandy sediments from either source would be quickly redeposited within 400 m (1,312 ft) of 

the trench, and finer sediments would be widely dispersed and redeposited over a period of hours to days 

within a few thousand meters (yards) of the event. No significant impact to commercial fisheries is 

therefore 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 (Stone et al., 1996). 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. 

Drilling-mud discharges contain chemicals toxic to marine fishes including brine, hydrocarbons, 

radionuclides, and metals; however, this is only at concentrations many orders of magnitude higher than 
4-156 Central and Western Gulf of Mexico Multisale Supplemental EIS

those found more than a few meters or feet from the discharge point. Offshore discharges of drilling 

muds would dilute to very 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 would disperse, dilute to very near background levels 

within 1,000 m (3,281 ft) of the discharge point, and have a negligible cumulative effect on fisheries. 

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. This was clearly the most 

destructive impact to commercial fishing infrastructure in U.S. history, but there are also many 

indications that these levels of impacts could reoccur. Natural disaster impacts are easily distinguished 

from incremental impacts of the OCS activities. 

Commercial catches by species and by State have been updated in Chapter 4.1.12.1, as have the 

impacts of the 2005 hurricanes on fish and fish habitat from recent reports (USDOC, NMFS, 2007e 

and f). Also included in the new information examined was the inclusion of the 181 South Area to the 

analysis. New information was not significantly different from that provided in the Multisale EIS and 

therefore no information was found that would alter the conclusion in the Multisale EIS that cumulative 

impacts on the commercial fisheries would be minimal. 

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. Impact-producing 

factors of the cumulative scenario that are expected to substantially affect commercial fishing include 

commercial and fishing techniques or practices, hurricanes, installation of production platforms, 

underwater OCS obstructions, production platform removals, seismic surveys, petroleum spills, 

subsurface blowouts, pipeline trenching, and offshore discharges of drilling muds and produced waters. 

Recent substantial impacts were because of the 2005 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 (i.e., installation of production platforms, underwater OCS 

obstructions, production platform removals, seismic surveys, oil spills, subsurface blowouts, pipeline 

trenching, and offshore discharges of drilling muds and produced waters) related to a CPA or WPA 

proposed action are expected to be negligible and indiscernible from natural fishery population 

variability. 

New fishery statistics analyzed and the addition of the 181 South Area do not change the conclusion 

in the Multisale EIS that the incremental contribution of a CPA or WPA proposed action to cumulative 

impacts on the commercial fisheries would be negligible and indiscernible from natural fishery population 

variability. 

4.1.13. Recreational Fishing 

Recreational fishing continues to be a popular nearshore and near offshore recreational activity in the 

northeastern and central Gulf of Mexico. The MMS has reexamined the analysis for recreational fishing 

presented in the Multisale EIS, based on the additional information presented below and the addition of 

the 181 South Area to the proposed CPA sale area. New information was not significantly different from 

that provided in the Multisale EIS and therefore no information was found that would alter the 

conclusions in the Multisale EIS that impacts on the recreational fisheries from accidental events 

associated with a CPA or WPA proposed action would be minimal. The inclusion of 181 South Area will 

have no direct routine impacts on recreational fishing due to its distance (nearly 130 mi; 209 km) from the 

nearest shore. Indirect impacts resulting from an incremental increase of vessel trips from activities in the 

181 South Area is expected to be negligible. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 
Environmental and Socioeconomic Consequences 4-157 

summary of potential impacts follows. Routine activities in the CPA and WPA such as seismic surveys 

and pipeline trenching would cause negligible impacts and will not deleteriously affect recreational 

fishing activities. Indirect impacts to inshore habitats are negligible and indistinguishable from direct 

impacts of inshore activities on commercial recreational fisheries. Temporary localized impacts from oil 

spills are anticipated as a result of a CPA or WPA proposed action, which would include temporary 

inconvenience to recreational fishermen and possibly some loss of revenue to facilities supported by 

recreational fishermen such as boat launches and bait shops. The incremental contribution of a CPA or 

WPA proposed action to the cumulative impact on recreational fishing is positive, although minor, due to 

the relatively small number of structures projected. 

4.1.13.1. Description of the Affected Environment 

The primary source for marine recreational fisheries data in U.S. waters is the Marine Recreational 

Fisheries Statistics Survey (MRFSS) conducted by NMFS. This recreational fisheries data from the Gulf 

of Mexico through 2005 (USDOC, NMFS, 2006) is summarized below, and it presented in detail in 

Chapter 3.3.2 and Tables 3-12, 3-13, and 3-14 of the Multisale EIS. Since the publication of the 

Multisale EIS, NMFS has published the 2006 MRFSS (USDOC, NMFS, 2007g), which is presented in 

Tables 4-6 through 4-8. These 2005 and 2006 data are inclusive of the 181 South Area. 

In 2006, 3.6 million residents participated in marine recreational fishing. All participants, including 

visitors, took nearly 25 million trips and caught almost 193 million fish. About 65 percent of the trips 

were made in west Florida, followed by 18 percent in Louisiana, almost 9 percent in Alabama, over 4 

percent in Texas, and 4 percent in Mississippi. From 2005 to 2006, the number of recreational fishing 

trips from Mississippi decreased by 36 percent, while the number of trips from Alabama increased by 37 

percent. Florida, Louisiana, and Texas saw smaller increases in the number of trips. 

In 2006, over 6.1 million people, up from 5.6 million in 2005, engaged in some form of recreational 

fishing in Louisiana, Mississippi, Alabama, and western Florida. Of the four states, western Florida had 

the highest number of anglers and fishing trips in 2005 and 2006, followed (in descending order by 

number of trips) by Louisiana, Alabama, and Mississippi. The most common mode of fishing in three 

Gulf Coast States was private/rental boats, comprising over 60 percent in Louisiana and Mississippi, and 

26 percent in West Florida; the most popular form in Alabama was shore ocean (<3 mi or 4.8 km) at 39 

percent. In 2005, the most common mode of fishing in all Gulf Coast States was private/rental boats, 

comprising over 50 percent of the trips in each State. 

In 2005 and 2006, the percentage of effort expended in inland, State, and Federal waters varied by 

state. In Mississippi and Louisiana, approximately 90 percent of the trips were made in inland waters as 

opposed to State and Federal ocean waters in both 2005 and 2006. In West Florida and Alabama, the 

percentage of trips made in State ocean waters (46% and 51%, respectively) was much higher than the 

other two states. These percentages increased by 7 percent and 6 percent, respectively, from 2005. 

The top species commonly caught by recreational fishers in the MRFSS Gulf Coast States are 

illustrated in Table 4-6. By number, herring and spotted sea trout, both inland species, were the most 

common fish caught by recreational anglers in the Gulf of Mexico during 2005 and 2006. In 2006, the 

estimated catch for herrings was over 41 million fish, up from 24 million in 2005; while anglers caught 

over 30 million spotted sea trout, up from 23 million in 2005. Other important inland species include red 

drum, saltwater catfishes, and pinfishes. In offshore oceanic waters of the Gulf of Mexico, the most 

important species in terms of pounds caught were red drum, red snapper, and sheepshead. 

Hurricanes Katrina and Rita impacted recreational fishing from the Florida Panhandle to the Texas 

border, with additional impacts felt in southern Florida. The hurricanes had a major impact on the 

supporting infrastructure that anglers require to go fishing (e.g., bait shops, docks and marinas, lodging, 

fuel and ice facilities, etc.). In addition to damages to boats and facilities, revenue losses associated with 

lost markets of products or services are occurring. When considered on a regional basis, these lost market 

channels constitute a considerable reduction in the levels of economic activity, income generation, 

employment creation, and tax collections. 

Storm-related, recreational fisheries losses over the next year could total $421 million at the retail 

level (Louisiana Dept. of Wildlife and Fisheries, 2007). This figure includes losses incurred by licensed 

charter and guide vessels operating in the severely affected Louisiana parishes. 
4-158 Central and Western Gulf of Mexico Multisale Supplemental EIS

In addition, Hurricanes Katrina and Rita deposited extensive amounts of debris over various areas of 

the Gulf Coast (USDOC, NOAA, 2007). Submerged marine debris poses a hazard to vessel traffic. The 

NOAA is conducting underwater surveys off the coasts of Louisiana, Mississippi, and Alabama. This 

information is being used by State and Federal agencies tasked with removing marine debris left by 

Hurricane Katrina, and it will aid in planning for the aftermath of future storms. 

4.1.13.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine impacts on recreational fishing associated with a CPA or WPA 

proposed action can be found in Chapters 4.2.2.1.12 and 4.2.1.1.10 in the Multisale EIS, respectively. 

Routine events that might have direct effects on recreational fishing activity include structures 

installed on productive leases, platform removal, seismic surveys, drilling activities and pipeline 

trenching, drilling rig and platform discharges, and marine vessel traffic. 

Structures placed on productive leases provide hard substrate for invertebrate communities as food 

supply to attract provide shelter for fish. Each structure placed in the Gulf of Mexico to produce oil or 

gas would function as an artificial reef, attract sport fish, and improve fishing prospects in the immediate 

vicinity of platforms. This impact would last for the life of the structure, i.e., until the structures are 

removed from the location and the marine environment. 

Platform removal in <60 m (<200 ft) of water is usually accomplished by the use of explosives that 

are lethal to fish with internal air chambers, are demersal, or are in close contact with the platform 

structure. Seismic surveys generate intense sounds that affect the spatial distribution of fish during the 

surveys and for some period after exposure. Drilling activities and pipeline trenching provide temporary 

space-use conflicts with recreational fishermen. 

In additional, drilling rigs and permanent platforms discharge drilling mud and produced waters, 

respectively. Drill muds contain metals such as mercury and cadmium, and produced waters contain trace 

metals, brine, hydrocarbons, and radionuclides. Marine vessel traffic is increased for each productive 

platform established. 

Routine offshore activities also may impact inshore recreational fish stocks since most species are 

dependent on the inshore bays and wetlands for juvenile recruitment, growth, and/or survival. 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 inshore water quality including discharges, trash, and runoff that may be released 

from onshore facilities may indirectly impact recreational fisheries and impacts to coastal water quality. 

Coastal water quality in relation to commercial fisheries is discussed in Chapters 4.2.1.1.2.1 and 4.4.2.1 

of the Multisale EIS and in Chapter 4.1.2.1.2 of this SEIS. 

CPA Proposed Action Analysis 

Routine impacts to recreational fisheries that would occur as a result of a CPA proposed action 

include installation of platforms, platform removal, seismic surveys, drilling activities and pipeline 

trenching, drilling rig and platform discharges and marine vessel traffic. 

A CPA proposed action is anticipated to result in the installation of 22-24 new production platforms 

in water depths <200 m (656 ft) and would have beneficial effects on offshore and deep-sea recreational 

fishing within developed leases accessible to fishermen. These structures provide hard substrate that 

support food organisms, provide shelter, and attract fish. These positive effects would accrue and would 

last until the production structures are removed from the marine environment. 

Structural removals of platforms in water depths <200 m (656 ft) result in a loss of artificial habitat 

and result in fish mortality when explosives are used. It is projected that 18-20 removals will result in the 

CPA in water depths <200 m (656 ft). It is expected that structure removals will have a negligible impact 

on recreational fishing because of the inconsequential number of removals and the consideration that 

removals kill primarily those fish associated with the platforms 
Environmental and Socioeconomic Consequences 4-159 

Seismic surveys vessels are of temporary presence in any recreationally fished area of the CPA. 

Temporal and spatial distributions of species are not affected in adjacent areas. 

Space-use conflicts could occur during the time that any platform or pipeline is being installed. The 

length of pipeline anticipated as a result of a CPA proposed action is 50-850 km (31-528 mi) in water 

depths <60 m (200 ft). These impacts are short term and considered negligible on the recreational fishing 

community. 

Platform discharges are small in volume and quickly diluted, and they do not significantly impact 

recreational fisheries. Impacts on recreational fishing because of OCS-related vessel wakes would be 

minor because, on average, vessel use associated with a CPA proposed action would represent <1 percent 

of total vessel use. 

The inclusion of the 181 South Area will have no direct routine impacts on recreational fishing due to 

its distance (nearly 130 mi or 209 km) from the nearest shore. Indirect impacts resulting from an 

incremental increase of vessel trips from activities in the 181 South Area is expected to be negligible. 

WPA Proposed Action Analysis 

Routine impacts to recreational fisheries that would occur as a result of a WPA proposed action 

include installation of platforms, platform removal, seismic surveys, drilling activities and pipeline 

trenching, drilling rig and platform discharges and marine vessel traffic. 

A WPA proposed action is anticipated to result in the installation of 23-33 new production platforms 

in water depths <200 m (656 ft) and would have beneficial effects on offshore and deep-sea recreational 

fishing within developed leases accessible to fishermen. These structures provide hard substrate that 

supports food and shelter and attracts fish. These positive effects would accrue and would last until the 

production structures are removed from the marine environment. 

The structural removal of platforms in water depths <200 m (656 ft) results in a loss of artificial 

habitat and results in fish mortality when explosives are used. It is projected that 10-16 removals will 

result in the WPA in water depths <200 m. It is expected that structure removals will have a negligible 

impact on recreational fishing because of the inconsequential number of removals and the consideration 

that removals kill primarily those fish associated with the platforms. 

Seismic survey vessels are of temporary presence in any recreationally fished area of the WPA. 

Temporal and spatial distributions of species are not affected in adjacent areas. 

Space-use conflicts could occur during the time that any platform or pipeline is being installed. The 

length of pipeline anticipated as a result of a WPA proposed action is 60-420 km (37-261 mi) in water 

depths <60 m (200 ft). These impacts are short term and considered negligible on the recreational fishing 

community. 

Platform discharges are small in volume and quickly diluted, and they do not significantly impact 

recreational fisheries. Impacts on recreational fishing because of OCS-related vessel wakes would be 

minor because, on average, vessel use associated with a WPA proposed action would represent <1 percent 

of total vessel use. 

Summary and Conclusion 

Routine activities such as seismic surveys and pipeline trenching in the CPA and WPA would cause 

negligible impacts and will not deleteriously affect recreational fishing activities. Seismic surveys are not 

expected to cause long-term or permanent displacement of any recreationally fished species. Operations 

such as production platform emplacement, underwater OCS impediments, and explosive platform 

removal will not cause significant impacts to recreational fishing because their effects are localized and 

temporary. Recreational fisheries conflicts with platforms in the 181 South Area are not anticipated 

because its distance to the nearest shoreline is 130 mi (209 km). Indirect impacts to inshore habitats are 

negligible and indistinguishable from direct impacts of inshore activities on recreational fisheries. 

The MMS has reexamined the analysis for recreational fishing presented in the Multisale EIS based 

on the updated information presented. Specifically included in the reexamination was the addition of the 

181 South Area to the analysis. No significant new information was found that would alter the impact 

conclusion for recreational fishing presented in the Multisale EIS; therefore, a new analysis of the 

potential impacts of a CPA or WPA proposed action on recreational fishing is not required. The analysis 
4-160 Central and Western Gulf of Mexico Multisale Supplemental EIS

and potential impacts detailed in the Multisale EIS still apply for a CPA or WPA proposed action. 

Significant impacts to recreational fisheries will not result from either a CPA or a WPA proposed action. 

4.1.13.3. Impacts of Accidental Events 

Detailed information of the possible impacts on recreational fisheries from accidental events 

associated with a CPA or WPA proposed action are discussed in detail in Chapter 4.4.11 of the Multisale 

EIS. Accidental events that could possibly impact recreational fisheries are oil spills that occur within 

approximately 100 mi (161 km) of shore, which is where most recreational fishing takes place. Oil 

spilled in the offshore areas is usually localized and has a very low probability of reaching coastal areas 

that serve as nursery ground for many species of finfish. Much of the oil volatilizes or is dispersed by 

currents in the offshore environment. The 181 South Area is nearly 130 mi (209 km) from the nearest 

shore, and therefore has no discernible impact on recreational fishery resources. 

The probability of an offshore oil spill event is very low, as detailed in Chapter 4.3.1.5 of the 

Multisale EIS. Spills in coastal waters, as discussed in Chapter 4.3.1.7 of the Multisale EIS, 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 and rivers, and through 

coastal bays. 

Oil has the potential to affect finfish through direct ingestion of hydrocarbons or ingestion of 

contaminated prey, through uptake of dissolved petroleum products through the gills and epithelium of 

adults and juveniles, and through the death of eggs and decreased survival of larvae (NRC, 1985 and 

2002). All of these mechanisms are discussed in detail in Chapter 4.4.10 of the Multisale EIS. 

CPA Proposed Action Analysis 

The accidental events that could potentially cause impacts on the recreational fishery are nearshore oil 

spills. The impacts from the size of oil spills projected within the area used by recreational fishermen in 

the CPA would be temporary and localized. Recreational fishermen would routinely avoid the area of a 

spill or an inshore grounding of a spill because of the oil and cleanup operations. This could result in 

inconvenience to fishermen and temporary loss of revenue for inshore facilities dependent on recreational 

fishermen, such as boat launches or bait shops. 

No impact to recreational species catch is anticipated from the addition of the 181 South Area 

because of its distance to the nearest shore. 

WPA Proposed Action Analysis 

The accidental events that could potentially cause impacts on the recreational fishery are nearshore oil 

spills. The impacts from the size of oil spills projected within the area used by recreational fishermen in 

the WPA would be temporary and localized. Recreational fishermen would routinely avoid the area of a 

spill or an inshore grounding of a spill because of the oil and cleanup operations. This could result in 

inconvenience to fishermen and temporary loss of revenue for inshore facilities dependent on recreational 

fishermen, such as boat launches or bait shops. 

Summary and Conclusion 

In summary, only temporary localized impacts from oil spills are anticipated as a result of a CPA or 

WPA proposed action. These impacts include temporary inconvenience to recreational fishermen and 

possibly some loss of revenue to facilities supported by recreational fishermen, such as boat launches and 

bait shops. No impacts are anticipated from the addition of the 181 South Area because of its nearly 

130-mi (209-km) distance to the nearest shore. 

The new information presented regarding recreational fishing activity and the inclusion of the 181 

South Area were considered. New information was not significantly different from that provided in the 

Multisale EIS and therefore no information was found that would alter the conclusions in the Multisale 

EIS that impacts on the recreational fisheries from accidental events associated with a CPA or WPA 

proposed action would be minimal. 
Environmental and Socioeconomic Consequences 4-161 

4.1.13.4. Cumulative Impacts 

A detailed description of cumulative impacts on recreational fishing can be found in Chapter 4.5.12 of 

the Multisale EIS. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

This cumulative impact analysis considers existing recreational fishing activity, artificial reef 

developments, fishery management regimes, and past and future oil and gas developments. Sport fishing 

is a very popular recreational activity throughout the Gulf of Mexico and is one of the major attractions 

that generate significant tourism economies along the Louisiana, Alabama, and Florida coastal areas. The 

latest information indicates participation in marine recreational fishing in the Gulf of Mexico has shown a 

generally increasing trend from 2000 through 2006 (USDOC, NMFS, 2007g). The 181 South Area is not 

an area of significant recreational fishing due to its distance of nearly 130 mi (209 km) from the nearest 

shore. 

National concern for the health and sustainability of marine fisheries led to Federal legislation that 

resulted in the development of fishery management plans affecting recreational fish species in the Gulf of 

Mexico. Fisheries management plans focused on targeted species, such as red snapper, have led to size 

and creel limits as well as seasonal closures and gear restrictions or modifications in both commercial and 

recreational fishing. 

The Gulf Coast States have aggressively supported artificial reef development programs to help 

encourage and increase interest and enjoyment in offshore recreational fishing. With the exception of 

structures located deep water, most structures associated with a proposed action would act as artificial 

reefs and would attract recreational fishermen. 

Other cumulative impacts to recreational fisheries from routine OCS operations include space-use 

conflicts and noise from rig and platform installation and removal in the OCS. Space-use conflicts are 

usually minimal, but there is recreational shrimp trawling for wild shrimp, and trawls can become 

entangled with OCS structures in the water. Recreational rod and reel anglers often target oil and gas 

platforms because these structures act as Fish Attraction Devices (FAD’s). Noise from rig and platform 

installation may scatter some groundfish away from their homing area, possibly resulting in a temporary 

decrease in recreational catch, but most fish will return once the noise quits. Platform removal using 

explosives may impact recreational fisheries by driving some fish away or killing them. A structure that 

may be targeted as a fishing location by recreational anglers could be eliminated. 

Non-OCS activities also have the potential to adversely affect recreational fisheries, with most 

impacts occurring in nearshore coastal waters. Recreational fisheries may be affected by coastal 

development, commercial fishing, and dredge-and-fill activities. 

Oil spills can affect recreational fishers in ways similar to those stated for commercial fishers—

fouling gear with oil, tainting the catch, and degrading water quality and fishing grounds—all of which 

could occur as a result of either OCS or non-OCS cumulative activities. Spills are unlikely to decrease 

recreational fishing activity but may divert the location or timing of a few planned fishing trips and result 

in the loss of income to local businesses that are dependent on recreational fishermen, such as bait shops 

and boat launches. 

The OCS oil spills most likely to affect recreational anglers would be the shallow water spills since 

the recreational anglers are less likely to venture far offshore. Most recreational fishing is conducted 

within 100 mi (161 km) of shore. It is unlikely that all of these assumed spills will occur inshore. 

New information available (USDOC, NMFS, 2007g) was used to update the recreational fishing 

statistics from those presented in the Multisale EIS. These data and the addition of the 181 South Area 

were considered. The new data do not alter the conclusion of that presented in the Multisale EIS that 

cumulative impacts resulting from a CPA or WPA proposed action are minor. 

Summary and Conclusion 

Recreational fishing continues to be a popular nearshore and near offshore recreational activity in the 

northeastern and central Gulf of Mexico. The incremental contribution of a CPA or WPA proposed 

action to the cumulative impact on recreational fishing is positive, although minor, due to the relatively 

small number of structures projected. 

The cumulative impacts to recreational fisheries include space-use conflicts, noise from rig and 

platform installation, and oil spills in the OCS. Non OCS activities with the potential for cumulative 
4-162 Central and Western Gulf of Mexico Multisale Supplemental EIS

impacts on recreational fisheries include coastal development, commercial fishing, dredge-and-fill 

activities, and inshore oil spills. 

New information used to update the recreational fishing statistics from those presented in the 

Multisale EIS were considered, as well as the addition of the 181 South Area. These new data do not alter 

the conclusion of that presented in the Multisale EIS that cumulative impacts resulting from a CPA or 

WPA proposed action are minor. 

4.1.14. Recreational Resources 

The MMS has reexamined the analysis for recreational resources presented in the Multisale EIS, 

based on the additional information presented below and the addition of the 181 South Area to the 

proposed CPA sale area. No significant new information was found that would alter the impact 

conclusion for recreational resources presented in the Multisale EIS. The 181 South Area is located 

nearly 130 mi (209 km) from the nearest coast, far distant from recreational beaches, out of sight from 

land, and out of range for most recreational fishing. The inclusion of the 181 South Area is projected to 

result in a relatively minor amount of additional activity, limiting potential impacts from traffic and from 

trash and debris. The locations of the 181 South Area and the limited activities that are expected to result 

also limit potential impacts from oil spills. Therefore, no additional impacts on recreational resources are 

projected as a result of the addition of the 181 South Area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. While marine debris and nearshore operations, either individually 

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

reduce the number of recreational visits to Gulf Coast beaches. It is unlikely that a spill would be a major 

threat to recreational beaches because any impacts would be short term and localized, and should have no 

long-term effect on tourism. The incremental contribution of the CPA and WPA proposed actions to 

cumulative impacts to recreational resources would be minor. 

4.1.14.1. Description of the Affected Environment 

A detailed description of recreational resources can be found in Chapter 3.3.3 of the Multisale EIS. 

The following is a summary of the information presented in the Multisale EIS, which incorporates new 

information found since the publication of the Multisale EIS and the addition of the 181 South Area to the 

proposed CPA sale area. Because the 181 South Area is on the eastern edge of the CPA sale area nearly 

130 mi (209 km) from the nearest coast and because it is expected to result in very limited additional 

activity, the 181 South Area would add little to the impacting factors relevant to recreational resources 

(e.g., traffic and oil spills). 

The northern Gulf of Mexico coastal zone is one of the major recreational regions of the U.S., 

particularly in connection with marine fishing and beach-related activities. The shorefronts along the 

Gulf Coasts of Florida, Alabama, Mississippi, Louisiana, and Texas offer a diversity of natural and 

developed landscapes and seascapes. The MMS defines major recreational beaches as those frequently 

visited sandy areas along the shoreline that are exposed to the Gulf of Mexico and that support a 

multiplicity of recreational activities. Included are Gulf Islands National Seashore, State parks and 

recreational areas, county and local parks, urban beaches, private resort areas, and State and private 

environmental preservation and conservation areas. 

Recreation and tourism are major sources of employment along the Gulf Coast. Table 4-9 presents 

employment in tourism-related industries in 2005. The data in Table 4-9 are a compilation of data from 

travel- and tourism-related industries in the County Business Patterns (USDOC, Bureau of the Census, 

2007). 

Employment data are assumed to be in various travel-related industries, including food and beverage 

stores, gas stations, general merchandise stores, passenger air transportation, transit and ground passenger 

transportation, scenic and sightseeing transportation, passenger car rental, travel arrangement and 

reservation services, arts/entertainment/recreation, and accommodation and food services. The data 

presented are only for coastal counties and parishes because these are where the recreation and tourism 
Environmental and Socioeconomic Consequences 4-163 

industry might potentially be affected by routine events, such as OCS-related trash and debris, visual 

effects of structures, air and vessel traffic, and accidental events, such as oil spills. (This data differs from 

the data used to describe Labor Market Areas (LMA’s) and Economic Impact Areas (EIA’s) in Tables 

3-15 and 3-16 in the Multisale EIS, which includes all counties and parishes. The LMA’s and EIA’s

extend inland geographically into areas where tourism and recreation is not linked to coastal 

environments. The data in Table 4-9 more correctly describes the level of tourism-related employment 

and establishments potentially affected by OCS activities.) 

Marine recreation is defined as coastal and ocean participation in at least 1 of 19 activities/settings. 

In 2000, over 34 million people participated in some form of marine recreation in the five Gulf Coast 

States. Beaches are a major recreational resource that attracts tourists and residents to the Gulf Coast for 

fishing, swimming, shelling, beachcombing, camping, picnicking, bird watching, and other activities. 

The five Gulf Coast States have 1,734 mi (2,791 km) of beach and 706 beaches (USEPA, 2004b), and 

visiting beaches was the number one activity/setting for marine recreation. Nearly 22 million people 

participated in beach activities in 2000. Updates of these data from the 1999-2000 National Survey on 

Recreation and the Environment are currently underway. The scenic and aesthetic value of Gulf Coast 

beaches plays an important role in attracting visitors to the coastal zone (USDOC, NOAA, 2005b). 

The value of recreation and tourism in the Gulf of Mexico coastal zone from Texas through Florida 

has been estimated in the tens of billions of dollars annually (USDOI, MMS, 2001a; pages III-101 and 

III-102). Tourists visiting Florida’s beaches in 2000 spent approximately $21.9 billion, resulting in an 

indirect economic effect of $19.7 billion and a total economic impact of $41.6 billion (Florida Sea Grant, 

2005). In 2003, Baldwin County had a travel-related economic impact on Alabama totaling more than 

$1.8 billion (Economic Development Partnership of Alabama, 2005). From Alabama through Texas, 

substantial recreational activity takes place in sight of Gulf of Mexico oil and gas structures such as 

pipeline landfalls and offshore platforms. Offshore platforms also function as artificial reefs and, as such, 

have considerable positive economic impact by attracting fish and fishermen alike (Hiett and Milon, 

2002). 

In 2001, 2.5 million residents and nonresidents 16 years old and older hunted in the Gulf Coast States 

and spent approximately $3.4 billion on hunting. Nine million U.S. residents 16 years old or older fed, 

observed, or photographed wildlife in the Gulf Coast States in 2001 and spent roughly $3.9 billion 

(USDOI, FWS and USDOC, Bureau of the Census, 2001). These figures are for the whole of each Gulf 

Coast State, and the coastal hunting and wildlife observation activities presumably would constitute a 

small fraction of the total. 

The previous discussions describe the tourism and recreation baseline for the Gulf of Mexico prior to 

the impacts of Hurricanes Katrina and Rita in 2005. Both of these hurricanes caused extensive adverse 

impact to tourism and recreation throughout the Gulf by disrupting recreational services and destroying 

beaches, public piers, hotels, marinas, recreational pleasure craft and charter boats, and numerous forms 

of other recreational infrastructure. The extent of the 2005 hurricane impacts to tourism and recreation 

has yet to be fully quantified, but it will likely take years for tourism and recreation to return to prehurricane levels in some areas. One source does provide information related to the effects of the 

hurricanes on coastal areas. Hurricanes Katrina and Rita deposited extensive amounts of debris over 

various areas of the Gulf Coast. Because submerged marine debris poses a hazard to vessel traffic, 

NOAA is conducting underwater surveys off the coasts of Louisiana, Mississippi, and Alabama. This 

information is being used by State and Federal agencies tasked with removing marine debris left by 

Hurricane Katrina and will aid in planning for the aftermath of future storms (USDOC, NOAA, 2007). 

The Ocean Conservancy sponsors national and international beach cleanups, including annual events 

in Louisiana, Mississippi, and Alabama. The Louisiana event is coordinated by the LADEQ Litter 

Reduction and Public Action Program. Statistics have not been published for the last Louisiana event, 

held in September 2007 (LADEQ, 2007c). The Mississippi Marine Debris Task Force sponsors the 

annual Mississippi Coastal Cleanup. During the 19th Annual Mississippi Coastal Cleanup on 

September 15, 2007, volunteers collected over 53,800 pounds of trash along 159 mi (256 km) of 

Mississippi Gulf Coast and barrier islands (Mississippi Alabama Sea Grant Consortium, 2007). The 

Alabama Coastal Cleanup is coordinated through the Alabama Dept. of Conservation and Natural 

Resources, State Lands Division, Coastal Section and the Alabama People Against a Littered State. Since 

joining the effort in 1987, 48,446 participants in Alabama have removed a total of 902,242 lb of debris 

and have cleaned 2,847 mi (4,582 km) of coastline (Alabama Coastal Cleanup, 2007). 
4-164 Central and Western Gulf of Mexico Multisale Supplemental EIS

4.1.14.2. Impacts of Routine Events 

Background and Introduction 

The primary impact-producing factors associated with offshore oil and gas exploration and 

development, and most widely recognized as threats to the enjoyment and use of recreational beaches, are 

oil spills and offshore trash, debris, and tar. Additional factors such as the physical presence of platforms 

and drilling rigs can affect the aesthetics of beach appreciation and are other areas of concern. Oil spills 

and tar result from accidental events and are analyzed below in Chapter 4.1.14.3. This section discusses 

the possible effects of routine activities associated with a CPA proposed action, the addition of the 181 

South Area, and the WPA on recreational resources. 

A detailed description of routine impacts on recreational resources associated with a CPA or WPA 

proposed action can be found in Chapters 4.2.2.1.13 and 4.2.1.1.11 of the Multisale EIS, respectively. 

The following is a summary of the information presented in the Multisale EIS, which incorporates new 

information found since publication of the Multisale EIS and the addition of the 181 South Area to the 

proposed CPA sale area. 

Trash and debris is the primary impact-producing factor from routine OCS activities that could affect 

the use and enjoyment of recreational beaches. Litter on recreational beaches from OCS operations could 

adversely affect the ambience of the beach environment, detract from the enjoyment of beach activities, 

and increase administrative costs to maintain beaches. Trash items such as glass, pieces of steel, and 

drums with chemical residues could also constitute a health threat to recreational beach users. The 

physical presence of platforms and drilling rigs visible from shore and the noise associated with vessels 

and aircraft traveling between coastal shore bases and offshore operation sites are also impact-producing 

factors that could adversely affect the natural ambience of recreational beaches, particularly on primitive 

coastal beaches. Depending on weather conditions, drilling rigs and platforms placed 3-10 mi (5-16 km) 

from land are within sight range of shoreline. Currently, nearshore oil and gas operations are present in 

State and Federal waters off Louisiana, Mississippi, and Alabama. 

CPA Proposed Action Analysis 

A CPA proposed action is projected to result in the drilling of 77-88 exploration and production wells 

and the installation of 20-21 platforms in water depths <60 m (200 ft). In water depths of 60-200 m (200-

656 ft), a proposed action is projected to result in 31-38 wells and 2-3 platforms. The addition of the 181 

South Area to the proposed CPA sale area is projected to result in an additional 9-12 wells and the 

installation of up to 1 platform. Marine debris would be lost from time to time from OCS operations 

associated with drilling activities and production facilities projected to result from a proposed action in 

the CPA. 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 potential for accidental loss of solid wastes from OCS oil and gas 

operations. Recreational beaches in Louisiana and Texas are most likely to be impacted by any 

waterborne trash. Beached litter and debris from a proposed action is unlikely to be perceptible to beach 

users or administrators because a proposed action would constitute only a small percentage of the total 

OCS Program activity in the CPA. 

A CPA proposed action is expected to result in 119,000-241,000 service-vessel trips over the life of 

the leases, or about 2,975-6,025 trips annually. A proposed action is also expected to result in 1,004,000-

2,241,000 helicopter operations (take off and landing), which is about 25,100-56,025 operations annually. 

Due to the amount of additional production projected from the addition of the 181 South Area, operations 

in this area are not expected to generate additional traffic and noise sufficient to change the analysis 

presented in the Multisale EIS. Service vessels are assumed to use established nearshore traffic lanes, and 

helicopters are assumed to comply with areal clearance restrictions at least 90 percent of the time. These 

actions tend to distance traffic from recreational beach users and, thereby minimize its effects. This 

additional helicopter and vessel traffic would add very little noise pollution likely to affect beach users. 

Because the 181 South Area is on the eastern edge of the CPA sale area nearly 130 mi (209 km) from 

the nearest coast and because it is expected to result in very limited additional activity, the 181 South 

Area would add little to the impacting factors relevant to recreational resources (e.g., traffic and oil 
Environmental and Socioeconomic Consequences 4-165 

spills). Therefore, its inclusion does not change the analysis or conclusions regarding recreation that are 

found in Chapters 4.2.1.1.11 and 4.2.2.1.13 of the Multisale EIS. 

WPA Proposed Action Analysis 

A WPA proposed action is projected to result in the drilling of 87-125 exploration and production 

wells and the installation of 21-31 platforms in water depths <60 m (200 ft). In water depths of 60-200 m 

(200-656 ft), a proposed action is projected to result in 18-22 wells and 2 platforms. Marine debris would 

be lost from time to time from OCS operations associated with drilling activities and production facilities 

projected to result from a WPA 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 potential for accidental loss of 

solid wastes from OCS oil and gas operations. Recreational beaches in Louisiana and Texas are most 

likely to be impacted by any waterborne trash. Beached litter and debris from a proposed action is 

unlikely to be perceptible to beach users or administrators because a proposed action would constitute 

only a small percentage of the total OCS Program activity in the WPA. 

A WPA proposed action is expected to result in 94,000-155,000 service-vessel trips over the life of 

the leases or about 2,350-3,875 trips annually. A proposed action is also expected to result in 400,000-

900,000 helicopter operations (take off and landing), which is about 10,000-22,500 operations annually. 

Service vessels are assumed to use established nearshore traffic lanes, and helicopters are assumed to 

comply with areal clearance restrictions at least 90 percent of the time. These actions tend to distance 

traffic from recreational beach users and, thereby minimize its effects. This additional helicopter and 

vessel traffic would add very little noise pollution likely to affect beach users. 

Summary and Conclusion 

The proposed actions in the CPA, including the 181 South Area, and WPA would result in marine 

debris lost from time to time from operations. However, the impact on Gulf Coast recreational beaches 

and beach use is expected to be minimal. The incremental increase from the CPA, the 181 South Area 

addition, and WPA in helicopter and vessel traffic is projected to add very little additional noise that may 

affect beach users. The proposed actions are projected to result in nearshore operations that may 

adversely affect the enjoyment of some Gulf Coast beach uses; however, these would have little effect on 

the number of beach users. While these factors, either individually or collectively, may adversely affect 

the quality of some recreational experiences, they are unlikely to reduce the number of recreational visits 

to Gulf Coast beaches. 

4.1.14.3. Impacts of Accidental Events 

Background and Introduction 

A detailed description of accidental impacts on recreational resources can be found in Chapter 4.4.12 

of the Multisale EIS. The following is a summary of the information presented in the Multisale EIS, 

which incorporates new information found since publication of the Multisale EIS and the addition of the 

181 South Area to the proposed CPA sale area. 

While respondents in the MMS study, Socioeconomic and Environmental Issues Analysis of Oil and 

Gas Activity on the Outer Continental Shelf of the Western Gulf of Mexico, recognized the threats to 

recreation and tourism posed by such factors as offshore trash and debris, the visual impacts of offshore 

structures, and the noise of vessel and helicopter traffic, most believed that a large oil spill would have 

devastating effects on the tourist industry. While “small” spills were deemed to occur with some 

frequency, it is “the big one” that people fear most (Kelley, 2002). Offshore trash and tar is often noted 

as the second biggest threat to the condition of Gulf Coast beaches. Large oil spills contacting 

recreational beaches can cause short-term displacement of recreational activity from the areas directly 

affected, including the closure of beaches for periods of 2-6 weeks or until the cleanup operations are 

complete. A large oil spill can acutely threaten recreational beaches for up to 30 days. 

Factors such as season, weather and tidal action, beach type and location, amount, condition and type 

of oil washing ashore, cleanup methods, and publicity can influence the severity of effects on a 
4-166 Central and Western Gulf of Mexico Multisale Supplemental EIS

recreational beach and its use. Sorensen (1990) reviews the economic effects of several historic large oil 

spills on beaches and concludes that such spills near a coastal recreational area would reduce visitation by 

5-15 percent over one season but would have no long-term effect on tourism. 

Tarballs (the floating residue remaining after oil slicks dissipate) are likely results from large spills. 

Tarballs are known to persist as long as 1-2 years in the marine environment. A MMS-funded study 

investigated the abundance and sources of tarballs on the recreational beaches of the CPA (Henry et al., 

1993). The study concludes that the presence of tarballs along the Louisiana coastline is primarily related 

to marine transportation activities and that their effect on recreational use is below the level of social and 

economic concern. 

CPA Proposed Action Analysis 

The risk of a spill occurring from a CPA proposed action and contacting recreational beaches is 

described in Chapter 4.3.1.8 of the Multisale EIS. Figure 3-8 displays the probabilities of oil spills 

>1,000 bbl occurring and contacting within 10 days shoreline as a result of a CPA proposed action. In a 

CPA proposed action, the probabilities are >0.5 percent in the following parishes and counties: Cameron, 

Vermilion, Iberia, Terrebonne, Lafourche, Jefferson, St. Bernard, and Plaquemines Parishes in Louisiana; 

and Jefferson and Galveston Counties in Texas. Figure 3-8 provides the probabilities of oil spills ≥1,000 

bbl occurring and contacting within 10 days State offshore waters or recreational beaches as a result of a 

CPA or WPA proposed action and reaching major recreational beach areas. As explained in Chapter 

3.2.1, the incremental increase in oil production from the addition of the 181 South Area is not expected 

to result in an overall increase in the numbers of oil spills ≥1,000 bbl likely to occur as a result of a CPA 

proposed action. Activity that would result from the addition of the 181 South Area would cause a 

negligible increase in the risk of a large spill occurring and contacting coastal counties and parishes, and 

major recreational beach areas. 

Should a spill occur, such factors as season, weather and tidal action, beach type and location, 

amount, condition and type of oil washing ashore, and cleanup methods would have a bearing on the 

severity of effects the spill would have on a recreational beach and its use. A spill near a coastal 

recreational area would reduce visitation in the area by 5-15 percent over one season but would have no 

long-term effect on tourism (Sorensen, 1990). 

Large oil and petroleum product spills could occur over the next 40 years and cause the temporary 

closure (up to 6 weeks) of park and recreation areas along the Gulf Coast and could affect tourism at the 

local level. The most likely source of OCS-related offshore oil spills is pipelines, and, because the 

existing pipeline system is concentrated off the coasts of western Louisiana and eastern Texas, these 

coasts are also the most likely location for a spill to occur and contact a recreational resource. Spills from 

OCS operations or import tankers occurring in proximity to recreational beaches and coastal parks could 

result in shoreline oiling, leading to the closure of these parks and beaches during cleanup operations, 

which can last from 2 to 6 weeks. 

WPA Proposed Action Analysis 

The risk of a spill occurring from a WPA proposed action and contacting recreational beaches is 

described under Chapter 4.3.1.8 of the Multisale EIS. Figure 3-8 displays the probabilities of oil spills 

>1,000 bbl occurring and contacting within 10 days shoreline as a result of a WPA proposed action. In a 

WPA proposed action, the probabilities are >0.5 percent in the following parishes and counties: Cameron 

Parish in Louisiana; and Aransas, Calhoun Matagorda, Brazoria, Galveston, and Jefferson Counties in 

Texas. Figure 3-8 provides the probabilities of oil spills ≥1,000 bbl occurring and contacting within 10 

days State offshore waters or recreational beaches as a result of a CPA or WPA proposed action and 

reaching major recreational beach areas. Should a spill occur, such factors as season, weather and tidal 

action, beach type and location, amount, condition and type of oil washing ashore, and cleanup methods 

would have a bearing on the severity of effects the spill would have on a recreational beach and its use. A 

spill near a coastal recreational area would reduce visitation in the area by 5-15 percent over one season 

but would have no long-term effect on tourism (Sorensen, 1990). 

Large oil and petroleum product spills could occur over the next 40 years and cause temporary 

closure (up to 6 weeks) of park and recreation areas along the Gulf Coast and could affect tourism at the 
Environmental and Socioeconomic Consequences 4-167 

local level. The most likely source of OCS-related offshore oil spills is pipelines, and, because the 

existing pipeline system is concentrated off the coasts of western Louisiana and eastern Texas, these 

coasts are also the most likely location for a spill to occur and contact a recreational resource. Spills from 

OCS operations or import tankers occurring in proximity to recreational beaches and coastal parks could 

result in shoreline oiling, leading to the closure of these parks and beaches during cleanup operations, 

which can last from 2 to 6 weeks. 

Summary and Conclusion 

It is unlikely that a spill would be a major threat to recreational beaches because any impacts would 

be short term and localized. Should a spill contact a recreational beach, short-term displacement of 

recreational activity from the areas directly affected would occur. Beaches directly impacted would be 

expected to close for periods of 2-6 weeks or until the cleanup operations were complete. Should a spill 

result in a large volume of oil contacting a beach or a large recreational area being contacted by an oil 

slick, visitation to the area could be reduced by as much as 5-15 percent for as long as one season, but 

such an event should have no long-term effect on tourism. Tarballs can lessen the enjoyment of the 

recreational beaches but they should have no long-term effect on the overall use of the beaches. Activity 

that would result from the addition of the 181 South Area would cause a negligible increase in the risk of 

a large offshore oil spill occurring and contacting coastal counties and parishes. 

4.1.14.4. Cumulative Impacts 

Background and Introduction 

This cumulative analysis of possible effects to recreational resources considers the effects of impactproducing factors related to the CPA and WPA proposed actions (Chapters 4.2.1.1.11 and 4.2.2.1.13 of 

the Multisale EIS) including the addition of the 181 South Area to the CPA, plus those impact-producing 

factors related to prior and future OCS sales, State offshore and coastal oil and gas activities throughout 

the Gulf of Mexico, tankering of crude oil imports, merchant shipping, commercial and recreational 

fishing, military operations, recreational use of beaches, and other offshore and coastal activities that 

result in debris, litter, trash, and spills, which may adversely affect major recreational beaches. Specific 

OCS-related, impact-producing factors analyzed include trash and debris, the physical presence of 

platforms and drilling rigs, support vessel and helicopter operations, oil spills, and spill cleanup activities. 

It does not consider factors that cannot be predicted over the 40-year analysis period such as land 

development, civil works projects, natural phenomena such as hurricanes, or fluctuations in the health of 

the U.S. economy and the price of gasoline. All of these local- and national-level factors have affected, 

and would continue to have greater effects on, the travel and tourism industry in general and on beach use 

along the U.S. Gulf Coast than do the factors that can be considered in the OCS Program. 

Trash and debris are a recognized problem affecting the enjoyment and maintenance of Gulf Coast 

recreational beaches. Extensive aerial surveys conducted by NMFS over large areas of the Gulf of 

Mexico characterized floating offshore trash and debris as an ubiquitous, Gulfwide problem (LeckeMitchell and Mullin, 1997). Coastal and offshore oil and gas operations contribute to trash and debris 

washing up on Texas and Louisiana beaches (Miller and Echols, 1996; Lindstedt and Holmes, 1988). 

Regulatory, administrative, educational, and volunteer programs involving government, industry, 

environmental, school, and civic groups; specific marine user groups; and private citizens are committed 

to monitoring and reducing the beach litter problem Gulfwide. 

CPA and WPA Proposed Actions Analysis 

Trash and debris detract from the aesthetic quality of beaches, can be hazardous to beach users, and 

can increase the cost of maintenance programs. The continued and expanded oil and gas operations 

throughout the Gulf of Mexico have contributed to the trash and debris on coastal beaches. The OCS 

activities are one of the many offshore activities (such as merchant shipping, Naval operations, offshore 

and coastal commercial and recreational fishing, and State offshore oil and gas activities), coastal 

activities (such as recreation, State onshore oil and gas activities, and condominiums and hotels), and 
4-168 Central and Western Gulf of Mexico Multisale Supplemental EIS

natural phenomena (such as storms, hurricanes, and river outflows) that contribute to the debris and 

pollution found on Gulf of Mexico recreational beaches. 

The OCS oil and gas industry is mitigating its contribution to this problem through (1) improved 

offshore waste management practices, (2) a strong commitment to participation in the annual removal of 

trash and litter from recreational beaches affected by their offshore operations, and (3) its support of 

MARPOL Annex V. The special efforts to generate cooperation and support from all Gulf user groups 

through the Gulf of Mexico program should lead to a decline in the overall level of human-generated 

trash adversely affecting recreational beaches throughout the Gulf. The MMS also mitigates this problem 

with rules governing the handling and disposal of trash generated on OCS structures. Because of the 

relative size of the OCS contribution to the trash and debris problem and because of ongoing industry and 

governmental efforts to mitigate this problem, the analysis in Chapters 4.2.1.1.11 and 4.2.2.1.13 of the 

Multisale EIS concluded that the incremental contribution of the CPA and WPA proposed actions to trash 

and debris would be minor. Due to the limited amount of additional production projected from the 

addition of the 181 South Area, this addition would not change this cumulative assessment. 

At present, there are approximately 4,000 OCS platforms on the Gulf of Mexico OCS. The CPA is 

located 3 nmi from the Louisiana, Mississippi, and Alabama shores. In the CPA, there are nearly 1,000 

platforms (34% of the structures, in water depths <60 m (200 ft)) within 10 mi (16 km) of the shore. Of 

those, most (84%) are located in the CPA west of the Mississippi River. In the CPA east of the 

Mississippi River, 14 percent of OCS platforms are within 10 mi (16 km) of the Louisiana, Mississippi, or 

Alabama coast. The WPA is 10 mi (16 km) from the Texas shore; therefore, no structures located in the 

WPA would be visible from shore. Based on these numbers and peak-year projections, a maximum of 

about 1,000 OCS production structures would be visible from shore at one time, and this number would 

drastically decrease during the 40-year analysis period as operations move into deeper water. Oil and gas 

operations in State waters off Texas, Louisiana, and Alabama are also visible from shore. Aesthetic 

impacts of the visible presence of offshore drilling rigs and platforms are unlikely to affect the level of 

beach recreation, but they may affect the experience of some beach users, especially at beach areas such 

as the Padre Islands National Seashore in Texas and the Gulf Islands National Seashore on Mississippi’s 

outer barrier islands. Because of its location to shore (nearly 130 mi or 209 km), the addition of the 181 

South Area would make no contribution to the aesthetic impacts of a CPA proposed action. 

Vessels and helicopter traffic servicing OCS operations would be seen and heard by beach users from 

time to time. Existing and future oil and gas developments in the State waters contribute to these impacts. 

Commercial and recreational maritime traffic add to the visual and noise impacts. See Chapter 4.1.1.2.2 

of the Multisale EIS for a summary of the report on potential OCS impacts on recreational beach activity 

(Kelley, 2002). Because of the limited amount of additional production projected from the addition of the 

181 South Area and because of its location, this addition does not change the analysis of the cumulative 

effects analysis of OCS-related traffic on beach users in the Multisale EIS.

Chapter 4.3.1 of the Multisale EIS discusses the risk of spill occurrence, the number of spills 

estimated for the OCS Program, and the likelihood of an OCS spill contacting the Gulf Coast. The 

scenarios analyzed hypothetical oil spills of ≥1,000 bbl occurring from future OCS oil and gas operations 

in the Gulf of Mexico. Should such a spill contact a recreational beach, it would result in a short-term 

displacement of recreational activity from the areas directly affected. Beaches directly impacted would 

be expected to close for periods of 2-6 weeks or until the cleanup operations were complete. Should a 

spill occur, factors such as season, extent of pollution, beach type and location, condition and type of oil 

washing ashore, tidal action, and cleanup methods would have a bearing on the severity of effects the spill 

would have on a recreational beach and its use. Sorenson (1990) reviewed the economic effects of 

several historic, large oil spills on beaches and concluded that a spill near a coastal recreation area would 

reduce visitation in the area by 5-15 percent over one season but would have no long-term effect on 

tourism. 

The estimated annual oil-spill occurrences expected in the future in the CPA or WPA, based on 

historical data maintained by MMS and USCG, are presented in Table 4-13 of the Multisale EIS. The 

great majority of coastal spills that do occur from OCS-related activities are likely to originate near 

terminal locations in the coastal zone around marinas, refineries, commercial ports, pipeline routes, and 

marine terminal areas, usually during the transfer of fuel. The average fuel-oil spill is 18 bbl. It is 

expected that these frequent, but small, spills would not affect coastal beach use. Due to the limited 

amount of additional production projected from the addition of the 181 South Area and its location far 
Environmental and Socioeconomic Consequences 4-169 

from shore, this addition does not change the analysis of the cumulative effects of large and small oil 

spills in the Multisale EIS. 

Although hundreds of small spills are documented annually from all sources within the marine and 

coastal environment of the Gulf Coast, it is primarily large spills (≥1,000 bbl) that are a major threat to 

coastal beaches. Should a large spill impact major recreational beaches, no matter the source, it would 

result in unit and park closures until cleanup is complete. Oil-pollution events impacting recreational 

beaches would generate immediate cleanup response from responsible oil and gas industry sources. 

Recreational use would be displaced from impacted beaches and closed parks (generally 2-6 weeks). 

Recreational use and tourism impacts would be more significant if spills affect beaches during peak-use 

seasons and if publicity is intensive and far-reaching. 

Summary and Conclusion 

Debris and litter derived from both offshore and onshore sources are likely to diminish the tourist 

potential of beaches and to degrade the ambience of shoreline recreational activities, thereby affecting the 

enjoyment of recreational beaches throughout the area. The incremental beach trash resulting from the 

CPA and WPA proposed actions is expected to be minimal. 

Platforms and drilling rigs operating nearshore may affect the ambience of recreational beaches, 

especially beach wilderness areas. The sound, sight, and wakes of OCS-related and non-OCS-related 

vessels, as well as OCS helicopter and other light aircraft traffic, are occasional distractions that are 

noticed by some beach users. 

Oil that contacts the coast may preclude short-term recreational use of one or more Gulf Coast 

beaches. The displacement of recreational use from impacted areas would occur, and a short-term decline 

in tourism may result. Beach use at the regional level is unlikely to change from normal patterns; 

however, the closure of specific beaches or parks directly impacted by a large oil spill is likely during 

cleanup operations. The incremental contribution of a CPA or WPA proposed action to the cumulative 

impact on recreational resources is minor due to the limited effect of increased helicopter, vessel traffic, 

and marine debris on the number of beach users. Because only a limited amount of additional production 

is projected from the addition of the 181 South Area and because its location is nearly 130 mi (209 km) 

offshore, this addition would not change the analysis of cumulative impacts to recreation and tourism 

presented in the Multisale EIS. 

4.1.15. Archaeological Resources 

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). The archaeological resources regulation 

(30 CFR 250.194) provides specific authority to each MMS Regional Director to require archaeological 

resource surveys, analyses, and reports. Surveys are required prior to any exploration or development 

activities on leases within areas determined to have a high potential for archaeological resources (NTL 

2005-G07 and NTL 2006-G07). 

The MMS has reexamined the analysis for prehistoric and historic archaeological resources presented 

in the Multisale EIS, based on the additional information presented below and the addition of the 181 

South Area to the proposed CPA sale area. No significant new information was found that would alter 

the impact conclusion for archaeological resources presented in the Multisale EIS. Given the extreme 

water depths in the 181 South Area (nearly 130 mi or 209 km), no prehistoric archaeological resources 

would likely be encountered in this area. Areas considered by MMS to have a high potential for historic 

shipwrecks are located throughout the Gulf of Mexico, including the 181 South Area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. The greatest potential impact to an archaeological resource as a 

result of routine activities associated with a CPA or WPA 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 or historic 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 
4-170 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 will 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 a 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. 

The effects of the various impact-producing factors of cumulative activities have likely resulted in the 

loss of significant or unique historic archaeological information. The incremental contribution of a CPA 

or WPA proposed action to the cumulative impacts on offshore historic archeological resources is 

expected to be very small due to the efficacy of the required remote-sensing survey and archaeological 

report. The incremental contribution of a proposed action to the cumulative impacts on coastal 

archeological resources is also expected to be very small due to the review and approval processes of the 

various Federal, State, and local agencies involved in permitting onshore activities. 

4.1.15.1. Description of the Affected Environment 

The description of archaeological resources (prehistoric and historic) can be found in Chapter 3.3.4 of 

the Multisale EIS. A summary of these resources is included below. 

Prehistoric Archaeological Resources 

Available geologic evidence indicates that sea level in the northern Gulf of Mexico was at least 90 m 

(295 ft), and possibly as much as 130 m (427 ft), lower than present sea level, and that the low sea-stand 

occurred during the period 20,000-17,000 years before present (B.P.) (Nelson and Bray, 1970). Sea level 

in the northern Gulf reached its present stand around 3,500 years B.P. (CEI, 1986). 

During periods that the continental shelf was above sea level and exposed, the area was open to 

habitation by prehistoric peoples. The advent of early man into the Gulf of Mexico region is currently 

accepted to be around 12,000 years B.P. (Aten, 1983). According to the sea-level curve for the northern 

Gulf of Mexico proposed by Coastal Environments, Inc. (CEI), sea level at 12,000 years B.P. would have 

been approximately 45 m (148 ft) below the present 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 a potential for 

prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the extent of 

emergent continental shelf depth and the entry date of prehistoric man into North America, MMS adopted 

the 12,000 years B.P. and the 60-m (197-ft) water depth as the seaward extent of the prehistoric 

archaeological high-potential area. Areas with a potential for containing prehistoric archaeological 

resources are located within the CPA and WPA lease areas; however, given the extreme water depths in 

the 181 South Area (nearly 130 mi or 209 km), no prehistoric archaeological resources could be 

encountered in this area. 

Historic Archaeological Resources 

There are areas of the northern Gulf of Mexico that are considered by MMS to have a high potential 

for historic period shipwrecks (Garrison et al., 1989; Pearson et al., 2003). These areas are located 

throughout the Gulf of Mexico, including the 181 South Area. Statistical analysis of the shipwreck 

location data identified two specific types of high-potential areas: (1) within 10 km (6 mi) of the 

shoreline and (2) proximal to historic ports, barrier islands, and other loss traps. Additionally, MMS has 

created high-potential search polygons associated with individual shipwrecks to afford protection to 

wrecks located outside the two high-potential areas. Recent research on historic shipping routes, 

however, 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 an 

historic shipwreck could be located in this area (Lugo-Fernandez et al., 2007). This route runs through 

the proposed sale areas including the 181 South Area, and much of this area is not currently identified as 
Environmental and Socioeconomic Consequences 4-171 

requiring an archaeological assessment. A study to conduct archival research on these historic shipping 

routes has been included on the Fiscal Year 2008 Studies Development Plan. 

The MMS shipwreck database lists numerous shipwrecks that fall within the proposed sale areas, 

including the 181 South Area. 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. The MMS 

Shipwreck Database currently lists 954 wrecks in the CPA (including the 181 South Area) and 516 

wrecks in the WPA. These wrecks are listed by planning area in Table 4-10. This list should not be 

considered exhaustive. 

The specific locations of archaeological sites cannot be known without first conducting a highresolution, remote-sensing survey of the seabed and near-surface sediments. Regular reporting of 

shipwrecks did not occur until late in the 19th century, and losses of several classes of vessel, such as 

small fishing boats, were largely unreported in official records. Aside from acts of war, hurricanes cause 

the greatest number of wrecks in the Gulf. Wrecks occurring in deeper water on the Federal OCS would 

have a moderate to high preservation potential because they lie beyond the influence of storm currents 

and waves. However, factors affecting the preservation of wood and iron at great depth in the Gulf of 

Mexico are, as of yet, poorly understood. Shipwrecks occurring in shallow water nearer to shore are more 

likely to have been reworked and disturbed by storms. Historic research indicates that shipwrecks occur 

less frequently in Federal waters, where they 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. 

The MMS approved the latest revision of NTL 2005-G07, “Archaeological Resource Surveys and 

Reports,” on July 1, 2005. This revised NTL (1) continues to require a 50-m (164-ft) line-spacing for 

historic shipwreck remote-sensing surveys in water depths <200 m (656 ft) and a 300-m (984-ft) linespacing for historic shipwreck remote-sensing surveys in water depths >200 m (656 ft), (2) increases the 

number of historic shipwreck blocks along the deepwater approach to the Mississippi River, (3) issues a 

reminder to operators of their requirement to notify MMS within 48 hr of the discovery of any potential 

archaeological site, and (4) updates some of the reporting requirements for archaeological assessments. 

Recent hurricane activity in the Gulf of Mexico is certain to have impacted archaeological resources 

in shallow water. A search was conducted for new information published since completion of the 

Multisale EIS; however, little new information was identified. Yet, 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, the National Park Service (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, the MMS awarded a study to investigate the 

impacts that recent storm activity may have had on historic shipwrecks in the Gulf of Mexico. Remotesensing surveys for this study were completed in May 2007 and dive operations were completed in 

October 2007. A final report of findings is expected early in 2009. Preliminary analysis of the remotesensing surveys and diver investigations indicates that at least 3 of the 10 shipwrecks examined were 

affected by recent storm activity (PBS&J, in preparation). 

A recently published report, Archaeological and Biological Analysis of World War II Shipwrecks in 

the Gulf of Mexico: Artificial Reef Effect in Deep Water (Church et al., 2007), documents the results of a 

multidisciplinary study that focused on the biological and archaeological aspects of seven World War II 

era shipwrecks in the north-central portion of the Gulf of Mexico. The study was funded by MMS and 

NOAA’s Office of Ocean Exploration. 

Seven shipwrecks, including a German submarine (U-boat) and some of its targets, were investigated. 

The ships lie in water ranging from 122 to 1,981 m (400 to 6,500 ft) deep. The study found deep-sea 

wrecks act as artificial reefs, attracting far more species of plants and animals than expected. The finding 

indicates that oil and gas production platforms in deep water are likely to serve as hard surface, 

supporting hundreds of life forms. 

The marine archaeology part of the study positively confirmed the identity of three wrecks and found 

a relationship among water depth, ship size, and the size of the debris field. The condition, state of 
4-172 Central and Western Gulf of Mexico Multisale Supplemental EIS

preservation, and deterioration rate for each shipwreck, as well as potential environmental impact, was 

assessed. In general there was a correlation between the wreck’s state of preservation and depth in this 

area of the Gulf of Mexico. Sediment core samples taken at various locations at each wreck site indicated 

the wreck sites are not contaminating or adversely impacting the surrounding seafloor at this time. 

4.1.15.2. Impacts of Routine Events 

A detailed description of the possible effects of routine activities associated with a CPA or WPA 

proposed action on archaeological resources can be found in Chapters 4.2.2.1.14 and 4.2.1.1.12 of the 

Multisale EIS, respectively. 

Blocks having a high potential for the occurrence of prehistoric, prehistoric and historic, or historic 

archaeological resources are found in the CPA and WPA. An Archaeological Resources Stipulation was 

included in all Gulf of Mexico lease sales from 1973 through 1994. The stipulation has been incorporated 

into operational regulations, which can be found at 30 CFR 250.194, 250.203(b)(15), 250.203(o), 

250.204(b)(8)(v)(A), 250.204(s), and 250.1007(a)(5). All protective measures offered in the stipulation 

have been adopted in this regulation. 

The likely locations of archaeological sites cannot be delineated without first conducting a remotesensing survey of the seabed and near-surface sediments. The MMS regulations that require OCS lessees 

and operators and applicants for pipeline rights-of-way to conduct an archaeological survey prior to 

proposed activities within areas determined to have a high potential for historic and/or prehistoric 

archaeological resources are described in Chapter 1.5 of the Multisale EIS. 

Prehistoric Archaeological Resources 

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 sealevel stands and the entry date of prehistoric man into North America, MMS 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 a CPA or WPA 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. The area of seafloor disturbance from each of these structures is 

defined in Chapter 4.1.1.3.2.1 of the Multisale EIS. Pile driving associated with platform emplacement 

may also cause sediment liquefaction an unknown distance from the piling, disrupting stratigraphy in the 

area of liquefaction. 

Pipeline placement has the potential to cause a physical impact to prehistoric archaeological 

resources. Pipelines placed in water depths of <60 m (200 ft) must be buried. Burial depths of 1 m 

(3.28 ft) are required, with the exception of shipping fairways and anchorage areas, where the 

requirements are 3.0 m (9.84 ft) and 4.6 m (15 ft), 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 
Environmental and Socioeconomic Consequences 4-173 

unidentified coastal prehistoric sites that could be impacted by onshore development, some may contain 

unique information. 

Onshore development as a result of a proposed action could result in direct physical contact between 

construction of new onshore facilities or a pipeline landfall and a previously unidentified prehistoric site. 

Direct physical contact with a prehistoric site could destroy fragile artifacts or site features and could 

disturb the site context. The result would be the loss of information on the prehistory of North America 

and the Gulf Coast region. 

Since all platform locations within the high-potential areas for the occurrence of offshore prehistoric 

archaeological resources are given archaeological clearance prior to setting the structure, removal of the 

structure should not result in any adverse impact to archaeological resources. This is consistent with the 

findings of the Programmatic Environmental Assessment: Structure Removal Activities, Central and 

Western GOM Planning Areas (USDOI, MMS, 1987). 

Except for the projected 0-1 new gas processing plant and 0-1 new pipeline landfall, a proposed 

action would require no new oil and gas coastal infrastructure. Any facility constructed must receive 

approval from the pertinent Federal, State, county/parish, and/or 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 a proposed action. 

In order to reduce the risk of impacting a prehistoric archaeological resource during an MMSpermitted activity, the MMS 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 Lessee (LTL’s), and updates requirements to reflect current technology. The list of lease blocks 

requiring an archaeological survey and assessment are identified in NTL 2006-G07. 

Historic Archaeological Resources 

The areas of the northern Gulf of Mexico that are considered to have high potential for historic period 

shipwrecks were redefined as a result of an MMS-funded study (Pearson et al., 2003; NTL 2006-G07). 

The 2003 study refined the shipwreck database in the Gulf of Mexico, initially developed by a previous 

MMS-funded study (Garrison et al., 1989), and identified new areas along the approach to the Mississippi 

River that have a high potential for containing historic shipwrecks. The Garrison et al. (1989) study used 

statistical analysis of shipwreck location data to identify two specific types of high-potential areas—the 

first within 10 km (6 mi) of the shoreline and the second proximal to historic ports, barrier islands, and 

other loss traps. High-potential search polygons associated with individual shipwrecks were also created 

to afford protection to wrecks located outside the two aforementioned high-potential areas. The Pearson 

et al. (2003) study incorporated this model into their recommendations, and the historic archaeological 

high-potential areas are under MMS review at the time of this writing. Additionally, recent research on 

historic shipping routes in the Gulf of Mexico suggests that the colonial trade route from Veracruz, 

Mexico, to Havana, Cuba, ran along the deepwater portion of the CPA and WPA between 25° and 27.5° 

N. latitude, which therefore increases the probability that an historic shipwreck could be located in this 

area (Lugo-Fernandez et al., 2007). 

Offshore development could result in a drilling rig, platform, pipeline, dredging activity, or anchors 

having an impact on an 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. 

The placement of drilling rigs and production systems has the potential to cause physical impact to 

historic archaeological resources. The area of seafloor disturbance from each of these structures is 

defined in Chapter 4.1.1.3.2.1 of the Multisale EIS. Pile driving associated with platform emplacement 

may also cause sediment liquefaction an unknown distance from the piling, disrupting stratigraphy in the 

area of liquefaction. 

Pipeline placement has the potential to cause a physical impact to historic archaeological resources. 

Pipelines placed in water depths of <61 m (200 ft) must be buried. Burial depths of 1 m (3.28 ft) are 
4-174 Central and Western Gulf of Mexico Multisale Supplemental EIS

required, with the exception of shipping fairways and anchorage areas, where the requirements are 3.0 m 

(9.84 ft) and 4.6 m (15 ft), respectively. 

The dredging of new channels, as well as maintenance dredging of existing channels, has the potential 

to cause a physical impact to historic shipwrecks (Espey, Huston, & Associates, 1990a). There are many 

navigation channels that provide OCS access to onshore facilities. Most of these channels are located in 

the CPA. 

Anchoring associated with platform and pipeline emplacement, as well as with service-vessel and 

shuttle-tanker activities, may also physically impact 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 a proposed action would generate ferromagnetic structures and debris, which 

would tend to mask magnetic signatures of significant historic archaeological resources. The task of 

locating historic resources through an archaeological survey is, therefore, made more difficult as a result 

of leasing activity. 

The loss of ferromagnetic debris during exploration and production activities has the potential to 

mask the magnetic signatures of historic shipwrecks. Under a proposed action, it is expected that 

hundreds of tons of ferromagnetic debris would be lost overboard. It is expected that most ferromagnetic 

debris associated with OCS structures would be removed from the seafloor during site-clearance 

activities. Site clearance, however, takes place after the useful life of the structure is complete. It has 

been noted that such debris has the potential to be moved from the area of initial deposition as a result of 

trawling activities (Garrison et al., 1989). Also, no site-clearance activities are required for pipeline 

emplacement operations. Therefore, there remains the potential for masking the signatures of historic 

shipwrecks as a result of ferromagnetic debris from OCS oil and gas activities. 

Since all platform locations within the high-potential areas for the occurrence of offshore historic 

archaeological resources are given archaeological clearance prior to setting the structure, removal of the 

structure should not result in any adverse impact to archaeological resources. This is consistent with the 

findings of the Programmatic Environmental Assessment: Structure Removal Activities, Central and 

Western GOM Planning Areas (USDOI, MMS, 1987). 

Onshore historic properties include sites, structures, and objects such as historic buildings, forts, 

lighthouses, homesteads, cemeteries, and battlefields. Sites already listed on the National Register of 

Historic Places and those considered eligible for the Register have already been evaluated as being able to 

make a unique or significant contribution to science. Historic sites that have yet to be identified may 

contain unique historic information and would have to be assessed after discovery to determine the 

importance of the data. 

Onshore development could result in the direct physical contact between the construction of new 

onshore facilities or pipeline canals and previously unidentified historic sites. This direct physical contact 

with a historic site could cause physical damage to, or complete destruction of, information on the history 

of the region and the Nation. Except for the projected 0-1 new gas processing plant and 0-1 new pipeline 

landfall, a proposed action would require no new oil and gas coastal infrastructure. Any facilities to be 

constructed must receive approval from the pertinent Federal, State, county/parish, and/or communities 

involved. Protection of archaeological resources in these cases is expected to be achieved through the 

various approval processes involved. There is, therefore, no expected impact to onshore historic sites in 

the CPA or WPA from onshore development. 

Maintenance dredging in support of activities resulting from a proposed action has the potential to 

impact a historic shipwreck. For instance, maintenance dredging in the Port Mansfield Entrance Channel 

is believed to have impacted the Santa Maria de Yciar, which sank on April 29, 1554 (Espey, Huston & 

Associates, 1990a). Impacts from maintenance dredging can be attributed proportionally to the users of 

the navigation channels. The MMS assessment indicates that, under a proposed action, <1 percent of the 

ship traffic through the Port Mansfield Cut is related to OCS use. Therefore, the impact to the Santa 

Maria de Yciar directly attributable to traffic and maintenance dredging as a result of the OCS Program is 

negligible. As these shipwrecks are unique historic archaeological resources, maintenance dredging, in 

general, is responsible for impacts to historic shipwrecks. Proposed-action activities represent <1 percent 

of the usage of the major navigation channels along the Gulf Coast. 

In order to reduce the risk of impacting a historic shipwreck during an MMS-permitted activity, the 

MMS requires a 50-m (164-ft) remote-sensing survey linespacing for historic shipwreck surveys in water 
Environmental and Socioeconomic Consequences 4-175 

depths <200 m (656 ft) and a 300-m (984-ft) remote-sensing survey linespacing for historic shipwreck 

surveys in water depths >200 m (656 ft). The current NTL—NTL 2005-G07, effective July 1, 2005—

supersedes all other archaeological NTL’s and LTL’s, and updates requirements to reflect current 

technology. The list of lease blocks requiring an archaeological survey and assessment are identified in 

NTL 2006-G07. 

CPA Proposed Action Analysis 

According to projections presented in Table 3-2, under a proposed action, 404-576 exploration, 

delineation, and development wells would be drilled, and 28-40 production platforms would be installed 

as a result of a CPA proposed action, including the 181 South Area. Relative-sea-level data for the Gulf 

of Mexico indicates that there is very low potential for the occurrence of prehistoric archaeological sites 

in water depths >60 m (197 ft). If only the area likely to contain prehistoric sites (shallower than 60 m or 

197 ft) is considered, 77-88 exploration, delineation, and development wells and 20-21 production 

platforms are projected to be installed (Table 3-3). The limited amount of impact to the seafloor 

throughout the CPA, the required archaeological survey, and the archaeological clearance are sufficient to 

assume a low potential for impacting a prehistoric archaeological site. Should such an impact occur, 

damage to or loss of significant or unique prehistoric archaeological information could occur. 

Of the total estimated number of exploration, delineation, and development wells identified in Table 

3-2, 108-126 wells would be drilled and 22-24 platforms would be installed in water depths of 200 m 

(656 ft) or less, where the majority of blocks having a high 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. 

Generally, in the eastern part of the CPA, where unconsolidated sediments are thick, it is likely that 

side-scan sonar would not detect shipwrecks buried beneath the mud. In this area, which begins 

nearshore around the Vermilion Area (USDOI, MMS, 1984) and extends eastward, the effectiveness of 

the survey for detecting historic shipwrecks of composite and wooden construction would depend on the 

capability of a magnetometer to detect ferromagnetic masses of the size characteristically associated with 

shipwrecks. It is assumed that the required 50-m (164-ft) linespacing (as specified in NTL 2005-G07) is a 

highly effective survey methodology, allowing detection and avoidance of historic shipwrecks within the 

survey area. The survey would therefore minimize the potential impacts to historic shipwrecks. 

Because there is only a thin Holocene sediment veneer overlying an overconsolidated Pleistocene 

surface in the western part of the CPA, shipwrecks are more likely to be detected by side-scan sonar; 

therefore, the 50-m (164-ft) survey linespacing is expected to be even more effective for reducing the 

potential for a direct physical contact between an impact-producing factor and a shipwreck in the western 

part of the CPA. There is a very small possibility that a historic shipwreck could be impacted by OCS 

activities. Should such an impact occur, however, significant or unique archaeological information could 

be lost. 

Considering that the expanded MMS shipwreck database contains 954 reported shipwrecks in the 

entire CPA (Table 4-10) and that an archaeological survey and assessment is required in all lease blocks 

identified as having a high potential for containing historic shipwrecks, the probability of an OCS activity 

contacting and damaging a shipwreck is very low. If an oil and gas structure contacted a historic 

resource, however, there could be a loss of significant or unique archaeological information. 

WPA Proposed Action Analysis 

According to projections presented in Table 3-3, under a proposed action, 197-287 exploration, 

delineation, and development wells would be drilled, and 28-41 production platforms would be installed 

as a result of a WPA proposed action. Relative sea-level data for the Gulf of Mexico indicates that there 

is very low potential for the occurrence of prehistoric archaeological sites in water depths >60 m (>197 

ft). If only the area likely to contain prehistoric sites (shallower than 60 m or 197 ft) is considered, 87-

125 exploration, delineation, and development wells and 21-31 production platforms are projected to be 

installed (Table 3-3). The limited amount of impact to the seafloor throughout the WPA, the required 

archaeological survey, and the archaeological clearance are sufficient to assume a low potential for 

impacting a prehistoric archaeological site. Should such an impact occur, damage to or loss of significant 

or unique prehistoric archaeological information could occur. 
4-176 Central and Western Gulf of Mexico Multisale Supplemental EIS

Of the total estimated number of exploration, delineation, and development wells and production 

platforms identified in Table 3-3, 105-147 exploration, delineation, and development wells would be 

drilled and 23-33 platforms would be installed in water depths of 200 m (656 ft) or less, where the 

majority of blocks having a high 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. Because there is only a thin Holocene sediment veneer overlying an 

indurated Pleistocene surface in the eastern part of the WPA, shipwrecks are more likely to be detected by 

side-scan sonar; therefore, the 50-m (164-ft) survey linespacing is expected to be even more effective for 

reducing the potential for a direct physical contact between an impact-producing factor and a shipwreck 

in the eastern WPA. Considering that the expanded MMS shipwreck database contains 516 reported 

shipwrecks in the entire WPA (Table 4-10) and that an archaeological survey and assessment is required 

in all lease blocks identified as having a high potential for containing historic shipwrecks, the potential of 

an OCS activity contacting and damaging a shipwreck is very low. If an oil and gas structure contacted a 

historic resource, however, there could be a loss of significant or unique archaeological information. 

Summary and Conclusion 

The greatest potential impact to an archaeological resource as a result of a CPA or WPA 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 or historic site. Given the extreme water 

depths in the 181 South Area, no prehistoric archaeological resources could be encountered in this area. 

However, there is a potential of contact with historic archaeological resources. 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 archaeological sites. Since the survey and 

clearance provide a significant reduction in the potential for a damaging interaction between an impactproducing factor and an archaeological site, there is a very small possibility of an OCS activity contacting 

an archaeological site in those lease blocks that require a high-resolution survey. Should such contact 

occur, there would be damage to or loss of significant and/or unique archaeological information. 

An MMS-funded study (Pearson et al., 2003) resulted in refinement of the areas assessed as having a 

high potential for the location of historic period shipwrecks. An MMS review of the historic highpotential areas for historic shipwrecks is occurring at the time of this writing. The NTL for 

archaeological resource surveys in the Gulf of Mexico Region, NTL 2005-G07, mandates a 300-m 

(984-ft) linespacing for remote-sensing surveys of leases within areas having a high potential for 

prehistoric sites; a 50-m (164-ft) linespacing of leases within the areas having a high potential for historic 

shipwrecks in water depths 200 m (656 ft) or less, and a 300-m (984-ft) linespacing in water depths >200 

m (656 ft). NTL 2006-G07 identifies those lease blocks that have been designated as having a high 

potential for containing archaeological resources. 

Except for the projected 0-1 new gas processing plants and 0-1 new pipeline landfall, a CPA or WPA 

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. 

Offshore oil and gas activities resulting from a proposed action could contact an archaeological 

resource because of incomplete knowledge on the location of these sites in the Gulf. Although this 

occurrence is not probable, such an event would result in the disturbance or destruction of important 

archaeological information. Under 30 CFR 250.194(c) and 30 CFR 250.1010(c), lessees are required to 

notify the MMS within 48 hr of the discovery of any potential archaeological resources. 

4.1.15.3. Impacts of Accidental Events 

Spills, collisions, and blowouts are accidental events that can happen in association with a CPA or 

WPA proposed action. If an accidental event occurs as a result of one of these events, there could be an 

impact to archaeological resources. Oil spills in the CPA or WPA have the potential to affect both 

prehistoric and historic archaeological resources. Impacts to historic resources would be limited to visual 

impacts and, possibly, physical impacts associated with spill cleanup operations. Impacts to prehistoric 

archaeological sites would be the result of hydrocarbon contamination of organic materials, which have 

the potential to date site occupation through radiocarbon dating techniques, as well as possible physical 
Environmental and Socioeconomic Consequences 4-177 

disturbance associated with spill cleanup operations. A detailed description of the possible effects of 

accidental events associated with a CPA and WPA proposed action on archaeological resources can be 

found in Chapter 4.4.13 of the Multisale EIS. 

Prehistoric Archaeological Resources 

Prehistoric archaeological sites on barrier islands and along beaches may be damaged by oil spilled as 

the result of an accidental event. The risk of oil spills occurring and contacting coastal areas is described 

in Chapter 4.3.1 of the Multisale EIS and in Chapter 3.2.1 of this SEIS. Direct physical contact of 

spilled oil with a prehistoric site could coat fragile artifacts or site features with oil. The potential for 

radiocarbon-dating organic materials in the site also could be adversely affected. Ceramic or lithic 

seriation or other relative dating techniques might ameliorate this loss of information. It is also possible 

to decontaminate an oiled sample for radiocarbon dating. Investigations into archaeological damage 

associated with the Exxon Valdez oil spill in the Gulf of Alaska revealed that oil did not penetrate the 

subsoil or into wooden artifacts in the intertidal zone, apparently because of hydrostatic pressure (Federal 

Archaeology, 1994); however, it is not certain that this finding would hold true in the Gulf of Mexico 

coastal region. 

Coastal prehistoric sites could experience an impact from oil-spill cleanup operations, including 

possible site looting from oil-spill cleanup crews. Cleanup equipment could destroy fragile artifacts and 

disturb the provenience of artifacts and site features. Some of the coastal prehistoric sites that might be 

impacted by beach cleanup operations may contain unique and significant scientific information. Should 

an oil spill contact a coastal prehistoric site, there could be a loss of significant archaeological information 

on the prehistory of North America and the Gulf Coast region. 

Historic Archaeological Resources 

The risk of contact to archaeological resources from oil spills associated with proposed-action 

operations is described in Chapter 4.3.1.8 of the Multisale EIS. Should an oil spill contact a coastal 

historic site, such as a fort or a lighthouse, the major impact would be a visual impact from oil contact and 

contamination of the site and its environment. Impacts to coastal historic sites are expected to be 

temporary and reversible. Should such an oil spill contact an onshore historic site, the effects would be 

temporary and reversible. 

Oil released subsea as a result of a blowout or pipeline incident would not be expected to contact an 

offshore sunken historic resource such as a shipwreck. 

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 or WPA proposed action. The proposed actions, therefore, are not 

expected to result in impacts to prehistoric archaeological sites; however, should such an impact occur, 

unique or significant archaeological information could be lost and this impact would be irreversible. 

Impacts to a historic archaeological resource could also occur as a result of an accidental spill. As 

indicated in Chapter 4.3.1.8 of the Multisale EIS, it is not very likely that an oil spill would occur and 

contact coastal historic archaeological sites from accidental events associated with a CPA or WPA 

proposed action. The major effect from an oil-spill impact would be visual contamination of a historic 

coastal site, such as a historic fort or lighthouse. As historic archaeological sites are protected under law, 

it is expected that any spill cleanup operations would be conducted in such a way as to cause little or no 

impacts to historic archaeological resources. These impacts would be temporary and reversible. 
4-178 Central and Western Gulf of Mexico Multisale Supplemental EIS

4.1.15.4. Cumulative Impacts 

A detailed description of cumulative impacts on archaeological resources can be found in Chapter 

4.5.14 of the Multisale EIS. The following is a summary of the information presented in the Multisale 

EIS, which incorporates new information found since publication of this SEIS. The analysis of these 

impacts applies to the CPA, including the 181 South Area, and the WPA. 

Prehistoric Archaeological Resources 

As a result of future OCS exploration and development activities in the Gulf of Mexico during the 40-

year analysis period projects drilling 12,966-14,187 exploration, delineation, and development wells in 

water depths <60 m (197 ft) (Table 4-4 of the Multisale EIS). Relative sea-level curves for the Gulf of 

Mexico indicate there is very low potential for the occurrence of prehistoric archaeological sites in water 

depths >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 2,530-18,790 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 over the 40-year analysis period as a result OCS 

Program activities in the CPA (including the 181 South Area) 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 the archaeological survey minimizes 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 pipelaying 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 during past OCS activities. 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 4.3.1 of the Multisale EIS. 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. Contamination of organic site materials by hydrocarbons can make radiocarbon dating of prehistoric 

sites 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. 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/or 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. 
Environmental and Socioeconomic Consequences 4-179 

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 MMS does not have jurisdiction over pipelines in State waters, the archaeological resource 

protection requirements of the National Historic Preservation Act (NHPA) are not within MMS’s 

jurisdiction. However, other Federal agencies, such as COE, which lets permits associated with pipelines 

in State waters, are responsible for the protection of archaeological resources under the NHPA. 

Therefore, the impacts that might occur to archaeological resources by pipeline construction within State 

waters should be mitigated under the requirements of the NHPA. 

About half of the coast along the northern Gulf was hit with 16-20 tropical cyclones between the 

years 1901 and 1955 (DeWald, 1982). Prehistoric sites in shallow waters and on coastal beaches are 

exposed to the destructive effects of wave action and scouring currents. Under such conditions, it is 

highly likely that artifacts would be dispersed and the site context disturbed. Some of the original 

information contained in the site would be lost in this process. Overall, a significant loss of data from 

prehistoric sites has probably occurred, and would continue to occur, in the northeastern Gulf from the 

effects of tropical storms and hurricanes. 

Historic Archaeological Resources 

Archaeological surveys are assumed to be highly effective in reducing the potential for an interaction 

between an impact-producing activity and a historic resource. The surveys are expected to be most 

effective in areas where there is only a thin veneer of unconsolidated Holocene sediments. In these areas, 

shipwreck remains are more likely to be exposed at the seafloor where they can be detected by the sidescan sonar as well as the magnetometer. In areas of thicker unconsolidated sediments, shipwreck remains 

are more likely to be completely buried with detection relying solely on the 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 during the 40-year analysis period 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 17,785 lease blocks in the OCS Program area, less than half of these blocks are leased. There 

are 3,726 blocks that fall within the Gulf of Mexico Region’s high-potential areas for historic resources. 

Of these blocks, 2,095 blocks are in water depths of 200 m (656 ft) or less and would require a survey at 

the 50-m (164-ft) linespacing. The potential of an interaction between rig or platform emplacement and a 

historic shipwreck is greatly diminished by requisite site surveys, but it still exists. Such an interaction 

could result in the loss of or damage to significant or unique historic resources. 

Table 4-4 of the Multisale EIS indicates 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 4.3.1 of the Multisale EIS. 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 4-14 of the 
4-180 Central and Western Gulf of Mexico Multisale Supplemental EIS

Multisale EIS 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 would be contained in the vicinity of the spill. 

Should such oil spills contact a historic site, the effects would be temporary and reversible. 

Most channel dredging occurs at the entrances to bays, harbors, and ports. These areas have a high 

potential for historic shipwrecks; the greatest concentrations of historic wrecks are likely associated with 

these features (Pearson et al., 2003). It is reasonable to assume that significant or unique historic 

archaeological information has been lost as a result of past channel dredging activity. In many areas, 

COE requires remote-sensing surveys prior to dredging activities to minimize such impacts. 

Past, present, and future OCS oil and gas exploration and development and commercial trawling 

would result in the deposition of tons of ferromagnetic debris on the seafloor. Modern marine debris 

associated with these activities would tend to mask the magnetic signatures of historic shipwrecks, 

particularly in areas that were developed prior to requiring archaeological surveys. Such masking of the 

signatures characteristic of historic shipwrecks may have resulted or may yet result in OCS activities in 

the cumulative activity area impacting a shipwreck containing significant or unique historic information. 

Trawling activity would specifically only affect the uppermost portions of the sediment column 

(Garrison et al., 1989). On many wrecks, the uppermost portions would already be disturbed by natural 

factors and would contain only artifacts that have lost all original context. 

Because MMS does not have jurisdiction over pipelines in State waters, the archaeological resource 

protection requirements of the NHPA are not under the jurisdiction of MMS in those areas. However, 

other Federal agencies, such as COE, which issues permits associated with pipelines in State waters, are 

responsible for the protection of archaeological resources under the NHPA. Therefore, the impacts that 

might occur to archaeological resources by OCS-related pipeline construction within State waters should 

be mitigated under the requirements of the NHPA. 

Sport diving 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 Texas Historical Commission and the Southwest Underwater Archaeological Society 

(Arnold, personal communication, 1997), will 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. Since the extent of these activities is unknown, the impact cannot be quantified. 

A Spanish war vessel, El Cazador, was discovered in the Central Gulf of Mexico. The vessel contained a 

large amount of silver coins and has been impacted by treasure-hunting salvage operations (The Times 

Picayune, 1993). The historic data available from this wreck and from other wrecks that have been 

impacted by treasure hunters and sport divers represent a significant or unique loss. 

Tropical storms and hurricanes are normal occurrences in the Gulf of Mexico 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 and 

hurricanes (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 and hurricanes. Some of the data lost have most likely been significant or 

unique. The MMS is currently funding a study to identify potential impacts from recent hurricane activity 

on historic shipwrecks in the Gulf of Mexico. A final report of findings is expected from this study in 

January 2009. 

Summary and Conclusion 

Several impact-producing factors may threaten archaeological resources. An impact could result 

from a contact between an OCS activity (i.e., pipeline and platform installations, drilling rig emplacement 

and operation, dredging, and anchoring activities) and a prehistoric site or historic shipwreck located on 

the continental shelf. The archaeological surveys and resulting archaeological analysis and clearance that 

are required prior to an operator beginning oil and gas activities in a lease area are expected to be highly 

effective at identifying and avoiding possible archaeological resources. The OCS development prior to 

requiring archaeological surveys has possibly impacted sites containing significant or unique 

archaeological information. 
Environmental and Socioeconomic Consequences 4-181 

Oil spills have the potential to impact coastal prehistoric sites directly or indirectly by physical 

impacts caused by oil-spill cleanup operations. Should an oil spill occur and contact a coastal prehistoric 

site, loss of significant or unique information could result. The loss or discard of ferromagnetic debris 

associated with oil and gas exploration and development and trawling activities could result in the 

masking of historic shipwrecks. 

The loss of significant or unique archaeological information from commercial fisheries (trawling) is 

not expected. It is expected that dredging, sport diving, commercial treasure hunting, and tropical storms 

and hurricanes have impacted and will continue to impact archaeological resources. However, the 

shallow depth of sediment disturbance caused by commercial fisheries activities (trawling) is not 

expected to exceed that portion of the sediments that have already been disturbed by wave-generated 

factors, and is therefore not expected to impact prehistoric resources. It is possible that explosive seismic 

surveys on the OCS and within State waters, prior to 1989, could have impacted archaeological resources. 

Explosive seismic charges set near historic shipwrecks could have displaced the vessel’s surrounding 

sediments, acting like a small underwater fault and moving fragile wooden, ceramic, and metal remains 

out of their initial cultural context. Such an impact would have resulted in the loss of significant or 

unique archaeological information. 

Onshore development as a result of a CPA or WPA 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 will serve to mitigate these potential impacts. The expected effects of oil spills on 

historic coastal resources are temporary and reversible. 

The effects of the various impact-producing factors discussed in this analysis have likely resulted in 

the loss of significant or unique historic archaeological information. In the case of factors related to OCS 

Program activities in 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 clearance requirements). The 

incremental contribution of a CPA or WPA proposed action is expected to be very small due to the 

efficacy of the required remote-sensing survey and archaeological report. However, there is a possibility 

of an interaction between bottom-disturbing activity (rig emplacement, pipeline trenching, and anchoring) 

and an archaeological site. 

4.1.16. Human Resources and Land Use 

4.1.16.1. Land Use and Coastal Infrastructure 

The MMS has reexamined the analysis for land use and coastal infrastructure presented in the 

Multisale EIS, based on the additional (mainly supplemental) information presented below and the 

addition of the 181 South Area to the proposed CPA sale area. Although the addition of the 181 South 

Area resulted in some increases in the activity scenario for a typical CPA proposed action, these minor 

increases in activity were not significant enough to affect the long-term (i.e., 40-year) forecasts of coastal 

infrastructure needs to support either a typical CPA sale or the OCS Program. To date, no new 

information has been found that necessitates a change to the coastal infrastructure scenario presented in 

the Multisale EIS. The MMS recently analyzed historical data and validated past scenario projections of 

new pipeline landfalls and new onshore waste disposal sites. Based on the lack of significant new 

information and MMS’s recent analysis, the coastal infrastructure projections have not changed for a 

proposed lease sale or for the OCS Program. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. A CPA (i.e., including the 181 South Area) or WPA proposed 

action would not require additional coastal infrastructure, with the exception of possibly one new gas 

processing facility and one new pipeline landfall, and 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 a 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 
4-182 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 the 

cleanup of any oil or chemicals spilled. The incremental contribution of a proposed action to the 

cumulative impacts on land use and coastal infrastructure are expected to be minor. 

4.1.16.1.1. Description of the Affected Environment 

The primary region of geographic influence of the proposed actions is coastal Texas and Louisiana, 

with a lesser influence on coastal Mississippi and Alabama and limited sale-related activities occurring in 

the Florida area. Land use in this area has not significantly changed since the Multisale EIS (Chapter 

3.3.5.1.2) and that description is summarized here. According to the U.S. Dept. of Agriculture’s 

Economic Research Service (ERS) classifications, 5 of 132 counties/parishes in the analysis area are 

classified as farming dependent, 9 as mining dependent (suggesting the importance of oil and gas 

development), 27 as manufacturing dependent, 30 as government employment centers, and 21 as tied to 

service employment (U.S. Dept. of Agriculture, ERS, 2004). The ERS also classifies 39 of the 

counties/parishes as major retirement destinations and 7 of the rural ones as recreation dependent. 

Important cities include Baton Rouge, Beaumont, Corpus Christi, Galveston, Houston, Lafayette, Lake 

Charles, Mobile, New Orleans, Pascagoula, and Port Arthur. 

The Texas Gulf coastal plain constitutes over one-third of the State and includes forest, cattle and 

farmlands, major cities of commerce and education, tourist locales, Federal installations, and major ports. 

The oil and gas industry has been part of its economy since the early 1900’s. The majority of oil and gas 

corporations have headquarters in Houston. The military also has a significant presence. 

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 it is devoted to 

State-chartered, beachfront gambling enterprises and heavy tourism. One-third is industrial—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. The military has had a long presence in the area. 

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 Chapter 

3.3.3 and Figures 3-13 through 3-15 of the Multisale EIS for a description of OCS infrastructure. 

4.1.16.1.2. Impacts of Routine Events 

Background/Introduction 

Chapter 4.1.2.1 of the Multisale EIS describes the potential need for the construction of new facilities 

and/or the expansion at existing facilities that could result from a proposed action and the OCS Program. 

Up to one new pipeline landfall and up to one new gas processing plant was projected as a result of an 

individual proposed lease sale. At present, there is considerable excess gas capacity in the Gulf of 

Mexico. However, near the end of the 40-year life of a proposed action, 0-1 new facilities are expected to 

be constructed as a result of a CPA or WPA proposed action. The MMS projected no other new coastal 

infrastructure as a result of an individual proposed lease sale. A proposed action may contribute to the 

use of existing and projected facilities. The MMS stated that no new navigation channels are expected to 

be dredged as a result of a proposed action; however, a proposed action would contribute to maintenance 

dredging of existing navigational canals. It should be noted that MMS is not a permitting agency of 

onshore infrastructure. The permitting agencies would be COE and the State in which the activity has or 

would occur. 

The MMS projected the number of Federal OCS landfalls that may result from proposed lease sales in 

order to analyze the potential impacts to wetlands and other coastal habitats. In the Multisale EIS and 
Environmental and Socioeconomic Consequences 4-183 

other previous EIS’s and EA’s, MMS 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, MMS projected up to one pipeline landfall per lease sale; however, recent 

MMS analysis showed that even one landfall as a result of an individual lease sale may be unlikely 

(USDOI, MMS, 2007g). This analysis confirms MMS’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. Although there will be some instances where new pipelines may 

need to be constructed, there is nothing to suggest any dramatic shifts in the trends in new Federal OCS 

landfalls given the current outlook for Gulf of Mexico development, particularly in coastal Louisiana 

(Dismukes, personal communication, 2007). While there are some opportunities for new pipeline 

landfalls from increased production activity, many of those will be limited due to a number of factors 

associated with basic pipeline economics. 

The analyses of coastal infrastructure presented in the Multisale EIS and other previous EIS’s and 

EA’s concluded that no new solid-waste facilities would be built as a result of a single lease sale or as a 

result of the OCS Program. Recent research further supports these past conclusions that existing solidwaste disposal infrastructure is adequate to support both existing and projected offshore oil and gas 

drilling and production needs (Dismukes et al., 2007). 

To date, no new information has been found that necessitates a change to the coastal infrastructure 

scenario presented in the Multisale EIS. Although the addition of the 181 South Area slightly increased 

some of the activity scenario parameters (e.g., production) for a typical CPA proposed action, the 

relatively small increase was not enough to change the long-term (i.e., 40-year) forecasts of coastal 

infrastructure needs to support OCS activity. The MMS also recently analyzed historical data and 

validated past scenario projections of new pipeline landfalls and new onshore waste disposal sites. Based 

on the lack of significant new information and MMS’s recent analyses supporting the estimates, the 

coastal infrastructure projections used in the Multisale EIS are still considered to be the best available. 

CPA Proposed Action Analysis 

A detailed impact analysis of the routine impacts of a CPA proposed action on land use and coastal 

infrastructure can be found in Chapter 4.2.2.1.15.1 of the Multisale EIS. The following is a summary of 

the information presented in the Multisale EIS, which incorporates new information found since the 

publication of the Multisale EIS, as well as new information relevant to the addition of the 181 South 

Area to the proposed CPA sale area. 

The MMS reviewed existing exploration and development plans near the 181 South Area. All plans 

reviewed identified Port Fourchon as the primary service base; however, for some plans other bases were 

identified instead of Port Fourchon for either crew or helicopter (i.e., Galliano and Venice, Louisiana), or 

as a backup to Port Fourchon (i.e., Venice, Louisiana). 

For the near term, Port Fourchon would most likely be the primary service base to support oil and gas 

activity in the 181 South Area. Because of the limited amount of land available at Port Fourchon, the port 

may face capacity constraints in the long term. Operators are also looking to diversity risk from 

shutdowns like those experienced after Hurricanes Katrina and Rita, and are therefore likely to look to 

other ports. Thus, in the longer term, other deepwater access ports such as Theodore and Mobile, 

Alabama, and Pascagoula, Mississippi, could also support the 181 South Area. 

For the 181 South Area scenario analysis, MMS estimates that there would be approximately 4 trips 

per week by supply vessels to a facility during drilling and production, approximately 8 trips per week by 

crew boats during drilling operations, and approximately 14 helicopter round trips per week to a 

production facility.

A 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 would not alter the current 

land use of the analysis area. 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. 

No recent information was found that would necessitate a reanalysis of the impacts of a CPA 

proposed action upon land use and coastal infrastructure. Although the addition of the 181 South Area 

slightly increased some of the activity scenario parameters (e.g., production) for a typical CPA proposed 
4-184 Central and Western Gulf of Mexico Multisale Supplemental EIS

action, the relatively small increase was not enough to change the long-term (i.e., 40-year) forecasts of 

coastal infrastructure needs to support OCS activity. The analysis and potential impacts detailed in the 

Multisale EIS apply for the new CPA area that includes the 181 South Area. 

The existing oil and gas infrastructure is expected to be sufficient to handle development associated 

with a proposed action. A proposed CPA lease sale would not alter the current land use of the area. 

WPA Proposed Action Analysis 

A detailed impact analysis of the routine impacts of a WPA proposed action on land use and coastal 

infrastructure can be found in Chapter 4.2.1.1.13.1 of the Multisale EIS. The following is a summary of 

the information presented in the Multisale EIS, which incorporates new information found since the 

publication of the Multisale EIS. 

A WPA proposed action would not require additional coastal infrastructure, with the exception of 

possibly one new gas processing facility and one new pipeline landfall, and would not alter the current 

land use of the analysis area. 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. 

No recent information was found that would necessitate a reanalysis of the impacts of a WPA 

proposed action upon land use and coastal infrastructure. As discussed above, MMS recently analyzed 

historical data and validated past scenario projections of new pipeline landfalls and new onshore waste 

disposal sites. Based on the lack of significant new information and MMS’s recent analyses supporting 

the estimates, the coastal infrastructure projections used in the Multisale EIS are still considered to be the 

best available. 

The existing oil and gas infrastructure is expected to be sufficient to handle development associated 

with a proposed action. A proposed WPA lease sale would not alter the current land use of the area. 

Summary and Conclusion 

Routine activities as the result of a CPA or WPA proposed action would not require additional coastal 

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

landfall, and 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 a 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. 

No recent information was found that would necessitate a reanalysis of the impacts of a CPA or WPA 

proposed action upon land use and coastal infrastructure. Although the addition of the 181 South Area 

slightly increased some of the activity scenario parameters (e.g., production) for a typical CPA proposed 

action, the relatively small increase was not enough to change the long-term (i.e., 40-year) forecasts of 

coastal infrastructure needs to support OCS activity. The analysis and potential impacts detailed in the 

Multisale EIS apply for the new CPA area that includes the 181 South Area. 

4.1.16.1.3. Impacts of Accidental Events 

Background/Introduction 

The accidental events associated with a CPA or WPA proposed action that would most likely impact 

coastal infrastructure and land use include oil spills, chemical spills, and vessel collisions. Impacts from 

well blowouts in the OCS are expected to be short-term and localized, and thus not likely to affect either 

coastal infrastructure or land use in the Gulf of Mexico. 

Spills can be associated with the exploration, production, or transportation phases of a CPA or WPA 

proposed action. The risk of oil-spill events as a result of a proposed action are discussed in depth in 

Chapter 4.3.1 of the Multisale EIS, while vessel collisions and chemical and drilling-fluid spills are 

discussed in Chapters 4.3.3 and 4.3.4, respectively. 

Oil spilled in the offshore areas is usually localized and has a low probability of contacting coastal 

areas; much of the oil volatilizes or is dispersed by currents. Oil produced from the 181 South Area is 
Environmental and Socioeconomic Consequences 4-185 

anticipated to have a high concentration of hydrocarbon compounds and, thus, it is projected to linger in 

the environment longer than oil from other areas that are composed of more volatiles. However, the Sale 

181 Area is approximately 130 mi (209 km) from the nearest shore. Moreover, the additional production 

from this area does not increase the overall risk of a large spill occurring in the Gulf of Mexico. 

CPA Proposed Action Analysis 

The accidental events associated with a CPA proposed action that would most likely impact coastal 

infrastructure and land use include oil spills, chemical spills, and vessel collisions. Spills can be 

associated with the exploration, production, or transportation phases of a proposed action. 

Both coastal or nearshore spills and vessel collisions could have short-term adverse effects on the 

operations of coastal infrastructure facilities. For example, on June 21, 2006, an oil spill occurred in the 

Calcasieu Parish Ship Channel in Lake Charles, Louisiana. The spill caused the Channel to be closed to 

all maritime traffic between lights 112 and 100 (World Marine News, 2006). The 11-mi (18-km) stretch 

of closed waterway caused a backup of vessels, six of which were carrying crude. In response to the loss 

of imports, Conoco Phillips and Citgo asked for oil to be lent to their refineries from the Strategic 

Petroleum Reserve. It also caused Calcasieu Refinery to cut runs to 20 percent at its refinery. Inbound 

traffic on the waterway was reopened July 1, 2006 (LaFavors, 2006). North America’s largest operating 

liquefied natural gas (LNG) importation terminal, owned by BG LNG Services LLC, was also forced to 

close for a few days during cleanup. 

In general, impacts from accidental events are not likely to last long enough to have any impacts on 

overall land use in the Gulf of Mexico analysis area. 

Additional impacts from the 181 South Area are not anticipated because of the distance of the area 

from the coast (130 mi or 209 km), and oil production in the area will not be large enough to increase the 

overall risk of a large spill occurring in the Gulf of Mexico. However, if a spill were to occur, the higher 

concentration of heavy hydrocarbons could potentially cause the oil to linger in the environment longer, 

which may result in a slightly larger area being affected and potentially longer cleanup time. 

WPA Proposed Action Analysis 

The accidental events associated with a WPA proposed action that would most likely impact coastal 

infrastructure and land use include oil spills, chemical spills, and vessel collisions. Spills can be 

associated with the exploration, production, or transportation phases of a proposed action. 

Both coastal or nearshore spills and vessel collisions could have short-term adverse effects on the 

operations of coastal infrastructure facilities. For example, on June 21, 2006, an oil spill occurred in the 

Calcasieu Parish Ship Channel in Lake Charles, Louisiana. The spill caused the Channel to be closed to 

all maritime traffic between lights 112 and 100 (World Marine News, 2006). The 11-mi (18-km) stretch 

of closed waterway caused a backup of vessels, six of which were carrying crude. In response to the loss 

of imports, Conoco Phillips and Citgo asked for oil to be lent to their refineries from the Strategic 

Petroleum Reserve. It also caused Calcasieu Refinery to cut runs to 20 percent at its refinery. Inbound 

traffic on the waterway was reopened July 1, 2006 (LaFavors, 2006). North America’s largest operating 

LNG importation terminal, owned by BG LNG Services LLC, was also forced to close for a few days 

during cleanup. 

In general, impacts from accidental events are not likely to last long enough to have any impacts on 

overall land use in the Gulf of Mexico analysis area. 

Summary and Conclusion 

Accidental events associated with a CPA or WPA proposed action (including the 181 South Area) 

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 clean up of any oil or chemicals spilled. 
4-186 Central and Western Gulf of Mexico Multisale Supplemental EIS

4.1.16.1.4. Cumulative Impacts 

Background/Introduction 

A detailed description of cumulative impacts upon land use and coastal infrastructure can be found in 

Chapter 4.5.15.1 of the Multisale EIS. The following is a summary of the information presented, 

incorporating any new information that has become available since publication of the Multisale EIS, 

including information relevant to the addition of the 181 South Area. 

The cumulative analysis considers the effects of impact-producing factors from OCS and State oil and 

gas activities. The OCS-related factors consist of prior, current, and future OCS lease sales. Chapters 

3.3.5.1.2 and 3.3.5.8 in 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 onshore. 

No recent information was found that would necessitate a reanalysis of the cumulative impacts of a 

proposed action upon land use and coastal infrastructure. As discussed above, MMS recently analyzed 

historical data and validated past scenario projections of new pipeline landfalls and new onshore waste 

disposal sites. Although the addition of the 181 South Area slightly increased some of the activity 

scenario parameters (e.g., production) for a typical CPA proposed action, the relatively small increase was 

not enough to change the long-term (i.e., 40-year) forecasts of coastal infrastructure needs to support OCS 

activity. The cumulative analysis and potential impacts detailed in the Multisale EIS apply for the new 

CPA area that includes the 181 South Area as well as the OCS Program. Based on the lack of significant 

new information and MMS’s recent analyses supporting the estimates, the coastal infrastructure 

projections used in the Multisale EIS are still considered to be the best available. 

Land use in the analysis area will evolve over time. The majority of this change is likely to occur 

from general regional growth rather than from activities associated with the OCS Program and/or State 

production. Projected new coastal infrastructure as a result of the OCS Program is shown by State in 

Table 4-9 of the Multisale EIS. For the OCS Program, MMS projects that up to 14 new gas processing 

plants with a facility size of 1.75 Bcf/d could be needed, assuming average retirement and no expansions 

and/or the addition of new capacity to replace what is physically depreciating over the next 40 years at all 

existing facilities. Of these, two are in Texas, three are in Louisiana, and nine are in the MississippiAlabama area. In reality, it is likely that few (if any) new, greenfield gas processing facilities would be 

developed along the CPA or WPA. It is much more likely that a large share of the natural gas processing 

capacity that is needed in the industry will be located at existing facilities, using future investments for 

expansions and/or to replace depreciated capital equipment for a variety of reasons. These reasons 

include lower development costs because of existing structures and utility services; existing 

interconnections to pipelines, natural gas liquid lines, and fractionators; incremental labor requirements 

are low relative to new facility staffing; the advantages of existing support, logistical and supply 

relationships such a vendors and maintenance support; and general economies of scale (Dismukes, 

personal communication, 2007). An example of this likely gas-processing development scenario can be 

seen with the Venice Gas Processing facility in Plaquemines Parish, which has expanded several times to 

a current maximum capacity of 1.3 Bcf/d since it was developed in 1996 as an 810 MMcf/d facility 

(Dismukes, personal communication, 2007). 

Except for the projected new gas processing plants needed near the end of the 40-year analysis (up to 

14 with a capacity of 1.75 Bcf/d, assuming average retirement and no expansions and/or the addition of 

new capacity to replace what is physically depreciating at all existing facilities) and the 4-6 pipeline shore 

facilities, the OCS Program will require no new oil and gas coastal infrastructure. There may be some 

expansion at current facilities, but the land in the analysis area is sufficient to handle development. The 

MMS expects that there is sufficient land to construct the few new gas processing plants that may be 

needed and the pipeline shore facilities in the analysis area. Any new facilities or expansions would also 

support State oil and gas production. Thus, the results of OCS and State oil and gas activities are 

expected to minimally alter the current land use of the area. 

Shore-based OCS and State servicing should increase in the ports of Galveston, Texas; Port 

Fourchon, Louisiana; and Mobile, Alabama. There is sufficient land designated in commercial and 

industrial parks and adjacent to the Galveston and Mobile area ports to minimize disruption to current 

residential and business use patterns. Port Fourchon, though, has limited land available; operators have 

had to create land on adjacent wetland areas. In the absence of the planned expansions, Louisiana 
Environmental and Socioeconomic Consequences 4-187 

Highway 1 (LA Hwy 1) would not be able to handle future OCS and State activities. On January 6, 2006, 

the Louisiana Dept. of Transportation and Development announced that it accepted a bid for the first of 

three phases on a new LA Hwy 1 toll road and bridge in lower Lafourche and Jefferson Parishes. Phase 

1A, construction of the two-lane elevated highway from the new Leeville Overpass to Port Fourchon, is 

underway and is expected to be completed in 2011. Phases 1B and 1C, the overpass at Bayou Lafourche 

in Leeville and its on- and off-ramps, is underway and is expected to be completed in early 2009. Phase 

1D, the Customer Service Center and Tolling System, is scheduled to go out to bid in 2008 and to open in 

2009, along with the Leeville Overpass. The toll will be $2.50 for cars and light trucks, and $1.25 per 

additional axle. A large portion of the tolls paid to finance the construction of this project will be paid by 

transportation activities associated with OCS oil- and gas-related activities. Traffic counts on LA Hwy 1 

have continued to increase with over 7,000 cars, trucks, and industrial vehicles having traveled along LA 

Hwy 1 during October 2007. In addition, any changes that increase OCS and State demand of water will 

further strain Lafourche Parish’s water system. Additional OCS activity will further strain Lafourche 

Parish’s social infrastructure as well, such as local hospitals and schools. Other ports in the analysis area 

that have sufficient available land plan to make infrastructure changes. Since the State of Florida and 

many of its residents reject any mineral extraction activities off their coastline, oil and gas businesses are 

not expected to be located there. 

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. Most subareas have strong industrial bases and designated 

industrial parks to accommodate future growth in oil and gas businesses. No recent information was 

found that would necessitate a reanalysis of the cumulative impacts of a CPA or WPA proposed action 

upon land use and coastal infrastructure. As discussed above, MMS recently analyzed historical data and 

validated past scenario projections of new pipeline landfalls and new onshore waste disposal sites. 

Although the addition of the 181 South Area slightly increased some of the activity scenario parameters 

(e.g., production) for a typical CPA proposed action, the relatively small increase was not enough to 

change the long-term (i.e., 40-year) forecasts of coastal infrastructure needs to support OCS activity. The 

analysis and potential impacts detailed in the Multisale EIS apply for the new CPA area that includes the 

181 South Area as well as the OCS Program. Based on the lack of significant new information and 

MMS’s recent analyses supporting the estimates, the coastal infrastructure projections used in the 

Multisale EIS are still considered to be the best available. 

Any changes (most likely expansions at existing facilities, except for the 4-6 new pipeline shore 

facilities and any new, greenfield gas processing plants) are expected to be contained on available land. 

Port Fourchon is expected to experience significant impacts to its land use from OCS-related expansion. 

Increased OCS-related usage from port clients is expected to significantly impact LA Hwy 1 in Lafourche 

Parish. Also, increased demand of water by the OCS will further strain Lafourche Parish’s water system. 

The incremental contribution of a CPA or WPA proposed action to the cumulative impacts on land 

use and coastal infrastructure are expected to be minor. Of the new coastal infrastructure projected as a 

result of the OCS Program, only 0-1 new gas processing plants and up to one new pipeline landfall are 

expected to be constructed as a result of a CPA or WPA proposed action, including the 181 South Area. 

The proposed actions would contribute to a small percentage of the projected OCS-related activity at Port 

Fourchon. 

4.1.16.2. Demographics 

The MMS has reexamined the analysis for demographics presented in the Multisale EIS, based on the 

additional information presented below and the addition of the 181 South Area to the proposed CPA sale 

area. No significant new information was found that would alter the impact conclusion for demographics 

presented in the Multisale EIS. The 181 South Area is located nearly 130 mi (209 km) from the nearest 

coast and is projected to result in a relatively minor amount of additional activity, therefore no additional 

impacts on employment, or the resulting population and demographics, are projected as a result of the 

inclusion of the 181 South Area. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 
4-188 Central and Western Gulf of Mexico Multisale Supplemental EIS

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. A CPA or WPA proposed action is projected to minimally affect 

the demography of the analysis area. Population impacts from a proposed action are projected to be 

minimal (<1% of the total population) for any economic impact area (EIA) 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 a 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) projected to move into focal areas, 

such as Port Fourchon. Accidental events associated with a 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. Baseline 

patterns and distributions of these factors, as described in Chapter 3.3.5.4.1 of the Multisale EIS, are not 

expected to change for the analysis area as a whole. Lafourche Parish (EIA LA-3), including Port 

Fourchon in particular, and Lafayette (EIA LA-2) in Louisiana are projected to experience some impacts 

to population as of a result of increase demand of OCS labor. A CPA or WPA proposed action is 

projected to have an incremental contribution of <1 percent to the population level in any of the EIA’s. 

4.1.16.2.1. Description of the Affected Environment 

A detailed description of the demographics of the Gulf Coast can be found in Chapter 3.3.5.4 of the 

Multisale EIS, including the impacts of the 2005 hurricane season. The following is a summary of the 

information presented in the Multisale EIS, which incorporates new information found since the 

publication of the Multisale EIS. The 181 South Area is located at the southeastern edge of the proposed 

CPA sale area nearly 130 mi (209 km) from the nearest coast. Although the addition of the 181 South 

Area to the CPA is projected to result in some additional sale-related activity, it is not enough to impact 

the employment or population projections for a proposed action presented in the Multisale EIS. 

Offshore waters of the WPA, CPA, and EPA lie adjacent to coastal Texas, Louisiana, Mississippi, 

Alabama, and Florida. The MMS grouped sets of counties and, in Louisiana, parishes into Labor Market 

Areas (LMA’s) on the basis of intercounty commuting patterns. Twenty-three of these LMA’s span the 

Gulf Coast and comprise the 13 MMS-defined EIA’s. Table 3-17 of the Multisale EIS lists the counties 

and parishes that comprise the LMA’s and EIA’s, and Figure 2-3 of the this SEIS illustrates the counties 

and parishes that comprise the EIA’s. See Chapter 3.3.5.4.1 of the Multisale EIS for further detail.

Tables 3-18 through 3-30 in the Multisale EIS provide detailed demographic data. The following is a 

summary of that data. The area’s population increased by 19 percent between 2000 and 2006. The 

region’s 2006 total population is 23.3 million. In the U.S., population age structures typically reflect the 

presence of the baby-boom generation. The African-American population increased 8.2 percent between 

2000 and 2006. The Hispanic population increased 24.4 percent between 2000 and 2006. This group is 

the second largest race/ethnic group in the region, making up 25.8 percent of the Gulf Coast population in 

2006. Although Asians and Pacific Islanders constitute a relatively small proportion of the Gulf Coast 

population; this group has experienced a growth rate of 28.8 percent between 2000 and 2006. The 

proportion of white population has steadily declined and in 2006 constitutes 53.6 percent of the region’s 

population. These overall trends vary from one Gulf Coast State to another and from one LMA to 

another. 

Tables 3-18 through 3-30 in the Multisale EIS also contain the analysis area’s baseline projections for 

population, employment, business patterns, and income and wealth through 2030 using Woods & Poole’s 

Complete Economic and Demographic Data Source (Woods & Poole Economics, Inc., 2006). These 

tables present projections by MMS-defined EIA. These baseline projections assume the continuation of 

existing social, economic, and technological trends at the time of the forecast. Therefore, the projections 

include population and 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 projections 

include Woods & Poole’s 2006 assumptions regarding Hurricane Katrina’s impact on the Southeast. 

Over the forecast period, Woods & Poole’s 2006 forecast of Hurricane Katrina’s impact assumes that all 

of the population, employment, and income gains and losses from Hurricane Katrina will mitigate and 
Environmental and Socioeconomic Consequences 4-189 

that New Orleans, Louisiana, will fully recover (Woods & Poole Economics, Inc., 2006). These baseline 

projections have changed only slightly from 2006 to 2007 (Woods & Poole Economics, Inc., 2007). 

Comparing the Woods & Poole projections in the 2006 data with the 2007 data for the hurricaneimpacted parishes and counties (with the 2006 data in parentheses) shows that population losses from the 

hurricanes between 2005 and 2006 in the new data were less than those that were assumed in 2006 data 

and presented in the Multisale EIS: (86%) 76 percent in St. Bernard Parish, Louisiana; (66%) 51 percent 

in Orleans Parish, Louisiana; (51%) 22 percent in Plaquemines Parish, Louisiana; and (16%) 13 percent 

in Hancock, Mississippi. The 2007 data also have revised assumptions regarding counties and parishes 

that experienced population and employment gains because of Hurricane Katrina displacement: (21%) 5 

percent in St. John the Baptist Parish, Louisiana; (10%) 5 percent in East Baton Rouge Parish, Louisiana; 

(18%) 4 percent in St. Charles Parish, Louisiana; and (18%) 7 percent in Tangipahoa Parish, Louisiana. 

In each case, these gains were less than those that were assumed in the 2006 data. Table 4-11 presents 

the new baseline population estimates based on the 2007 Wood & Poole data that are used to analyze 

population impacts in this SEIS (an update of Table 3-35 in the Multisale EIS). In general, Woods & 

Poole expects the Mississippi Gulf Coast to recover its population more quickly than the heavily impacted 

Louisiana parishes. Although they project the Louisiana parishes to have a much slower population 

growth rate, they project nearly all of the communities (except for Orleans Parish) to recover completely 

by 2030. 

The following is a summary of new information since the Multisale EIS from Rowley (2007). There 

is still disagreement surrounding the population estimates for the areas most affected by storms. For the 

City of New Orleans, the Louisiana Public Health Institute (LPHI) estimates the city’s population at 

191,139 as of January 2007; the U.S. Census Bureau estimates the population at 223,388 as of July 2006; 

and the City itself estimates it closer to 230,000. For St. Bernard Parish, the Census Bureau estimates the 

population at 66,441 in 2000 and 15,514 in July 2006; and the LPHI estimates it at 25,296 in January 

2007. Prior to Hurricane Katrina, the population of Hancock County, Mississippi, was 46,546; as of July 

2006, the Census estimated it at 40,421, indicating a substantial return of population. The Jefferson 

Parish population estimates are 451,049 in 2000, 431,361 in July 2006, and 434,666 in January 2007. 

The high population in Jefferson Parish indicates an in-migration of former residents of Orleans, St. 

Bernard, and Plaquemines Parishes and seasonal construction workers. See Chapter 3.3.5.5.1 of the 

Multisale EIS for a discussion of the relationship of population to housing availability and employment. 

Recovery remains uneven throughout the affected areas. Areas where the most severe problems 

remain are New Orleans and St. Bernard Parish, Louisiana; and Hancock County, Mississippi. Recovery 

is well underway in Jefferson Parish, Lake Charles, and Cameron Parish, Louisiana; Biloxi, Gulfport, and 

Pascagoula, Mississippi; and Bayou La Batre, Alabama. Recovery is driving expansion in East Baton 

Rouge and St. Tammany Parishes, Louisiana; Jackson, Hattiesburg, and Laurel, Mississippi; and Gulf 

Shores and Mobile, Alabama. The measures of recovery are the functions of local government, 

population, crime, economic and fiscal effects, local government budgets, housing, and labor.

Age 

Tables 3-18 through 3-30 of the Multisale EIS provide an overview of the Gulf Coast population, 

including trends and projections from 1990 to 2030. Woods & Poole projects the area to increase in 

population throughout this period, with a considerable shift in age structure. Until 2015, when the baby 

boomers start to retire in increasing numbers, the fastest growing age group will continue to be the 50- to 

64-year olds. After 2015, the proportion in the 50- to 64-year age group, as well as the younger age 

groups, begin to decline. Meanwhile, the age structure of the region will shift toward the more elderly. 

For example, the 65 and older age group increases from 13.3 percent of the total population in 2006 to 

over 19 percent in 2030.

Tables 3-18 through 3-30 of the Multisale EIS indicate that differences in net migration and age 

structure among the coastal EIA’s could create variations in population growth. Woods & Poole expects 

the highest rates of growth between 2006 and 2030 adjacent to the WPA and the lowest adjacent to the 

CPA. Woods & Poole projects the southern Florida and western southeastern Texas areas to have the 

highest growth rates, generally exceeding those expected for Louisiana, Mississippi, and Alabama, and 

they expect the lowest population growth rates in the Louisiana EIA’s. An exception is EIA LA-4, which 

they expect to have the highest population growth rate (55% over this period) due to the large population 
4-190 Central and Western Gulf of Mexico Multisale Supplemental EIS

loss in the New Orleans metropolitan area following Hurricane Katrina. They also expect EIA MS-1, 

which includes the Biloxi-Gulfport metropolitan area, to increase its population by approximately 30 

percent between 2006 and 2030. This high growth rate is also largely due to the substantial population 

loss that occurred after Hurricane Katrina (Woods & Poole Economics, Inc., 2006). As discussed above, 

Woods & Poole 2007 data projections have changed only slightly (Woods & Poole Economics, Inc., 

2007). 

Race and Ethnic Composition 

The following is a summary of the racial and ethnic composition of the analysis area presented in the 

Multisale EIS. The racial and ethnic composition of this area reflects both historical settlement patterns 

and current economic activities. In Texas from Brownsville to Corpus Christi, Hispanics form the 

dominant group. From Aransas to Houston, the size of the African-American population increases. In 

Jefferson County, Texas, adjacent to Louisiana, African-Americans outnumber Hispanics, reflecting the 

dominant minority status of African-Americans throughout the rest of the analysis area to the east. 

Despite the larger number of white, non-Hispanic people in coastal Texas, Louisiana, Mississippi, and 

Alabama, African-Americans and Hispanics together outnumber whites (Donato and Hakimzadeh, 2006). 

Approximately 45 percent of construction workers involved in the rebuilding effort and living in New 

Orleans, Louisiana, are estimated to be Latino (Fletcher et al., 2006). Southwestern Louisiana is Acadian 

country. Historically, settlers included Houma Indians, French, Spanish, English, and African. (See 

Chapter 4.1.16.4, Environmental Justice, for a further discussion of minority and low-income 

populations.) 

4.1.16.2.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine impacts on demographics associated with a CPA or WPA proposed 

action can be found in Chapters 4.2.2.1.15.2 and 4.2.1.1.13.2 of the Multisale EIS. The following is a 

summary of the information presented in the Multisale EIS, which incorporates new information found 

since publication of the Multisale EIS. 

The addition of any new human activity, such as oil and gas development resulting from the proposed 

actions, 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 and WPA proposed 

actions. The addition of the 181 South Area to a CPA sale area presents no unique issues. 

CPA Proposed Action Analysis 

Population 

No new data or information was found that indicated that the MAG-PLAN data used in the Multisale 

EIS was not still valid for projecting likely future activity. Although the addition of the 181 South Area 

increases some activity scenario parameters (e.g., production), the net annual increases to activity are not 

substantial enough to affect overall employment and resulting population projections. Projected 

population changes reflect the number of people dependent on income from the OCS-related employment 

for their likelihood (e.g., family members of oil and gas workers), which is based on the ratio of 

population to employment in the analysis area over the life of a proposed lease sale. Thus, the population 

projections from the Multisale EIS are still considered to be the best available and are summarized below. 

A CPA proposed action is projected to generate between 13,600 and 32,280 persons in the analysis 

area during the peak year of impact (year 5) for the low- and the high-case scenarios, respectively (Table 

4-28 in the Multisale EIS). Using the new 2007 Woods & Poole data discussed above as the baseline, 

MMS recalculated the population impacts on a percentage basis. These revised numbers do not differ 

significantly from those presented in Table 4-29 of the Multisale EIS and mirror those for employment 

impacts discussed in Chapter 4.1.16.3.2. Population impacts from a CPA proposed action are projected 
Environmental and Socioeconomic Consequences 4-191 

to be minimal (<1% of the total population) for any EIA in the Gulf of Mexico region. The mix of males 

to females is expected to remain unchanged. 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) projected to move into such focal areas as Port Fourchon. 

Age 

Given the low levels of industrial expansion and population growth projected for a CPA proposed 

action, the age distribution of the analysis area is projected to remain virtually unchanged through the life 

of a proposed action from the pattern previously discussed in Chapter 3.3.5.4.2 of the Multisale EIS. 

Also, a CPA proposed action 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 if a CPA 

proposed action takes place. Given the low levels of employment and population growth and the 

industrial expansion projected as a result of a CPA proposed action, the racial distribution pattern 

described in Chapter 3.3.5.4.3 of the Multisale EIS is expected to continue through the life of a proposed 

action (See Chapters 3.3.5.4.1 and 3.3.5.4.3 of the Multisale EIS for a discussion of race and ethnic 

composition changes as a result of Hurricanes Katrina and Rita). 

WPA Proposed Action Analysis 

Population 

No new data or information was found that indicated that the exploration and development scenarios 

or internal MAG-PLAN data used in the Multisale EIS was not still valid projections of likely future 

activity. Projected population changes reflect the number of people dependent on income from the OCSrelated employment for their likelihood (e.g., family members of oil and gas workers), which is based on 

the ratio of population to employment in the analysis area over the life of a proposed lease sale. Thus, the 

employment and resulting population projections from the Multisale EIS are still considered to be the best 

available and are summarized below. 

A WPA proposed action is expected to generate between 13,600 and 32,280 persons in the analysis 

area during the peak year of impact (year 2) for the low- and the high-case scenarios, respectively (Table 

4-20 in the Multisale EIS). Using the new 2007 Woods & Poole data discussed above as the baseline, 

MMS recalculated the population impacts on a percentage basis. These revised numbers do not differ 

significantly from those presented in Table 4-21 of the Multisale EIS and mirror those for employment 

impacts discussed in Chapter 4.1.16.3.2. Population impacts from a WPA proposed action are projected 

to be minimal (<1% of the total population) for any EIA in the Gulf of Mexico region. The mix of males 

to females is expected to remain unchanged. 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) projected to move into focal areas, such as Port Fourchon. 

Age 

The age distribution of the analysis area as a result of a WPA proposed action is projected to remain 

virtually unchanged. Given both the low levels of population growth and industrial expansion associated 

with a WPA proposed action, the age distribution pattern discussed in Chapter 3.3.5.4.2 of the Multisale 

EIS is projected to continue through the life of a proposed action. A WPA proposed action is not 

projected 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 if a WPA 

proposed action takes place. Given the low levels of employment and population growth and the 

industrial expansion projected as the result of a WPA proposed action, the racial distribution pattern 
4-192 Central and Western Gulf of Mexico Multisale Supplemental EIS

described in Chapter 3.3.5.4.3 of the Multisale EIS is expected to continue through the life of a WPA 

proposed action (See Chapters 3.3.5.4.1 and 3.3.5.4.3 of the Multisale EIS for a discussion of race and 

ethnic composition changes as a result of Hurricanes Katrina and Rita). 

Summary and Conclusion 

A CPA or WPA proposed action is projected to minimally affect the demography of the analysis area. 

Population impacts from a 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 3.3.5.4 of the Multisale EIS, are expected to remain unchanged as the result of a 

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) projected to move into focal areas, such as Port Fourchon. 

4.1.16.2.3. Impacts of Accidental Events 

Accidental events associated with a CPA or WPA proposed action such as oil or chemical spills, 

blowouts, and vessel collisions would have no effects on the demographic characteristics of the Gulf 

coastal communities. 

4.1.16.2.4. 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. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since the publication of the Multisale EIS. 

The cumulative analysis considers the effects of OCS-related, impact-producing as well as non-OCSrelated 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, but these events cannot be predicted with reasonable accuracy. Examples of unexpected 

events include major future natural disasters (including but not limited to hurricanes), oil embargos, and 

acts of war or terrorism. 

This analysis uses the economic and demographic projections from Woods & Poole (Woods & Poole 

Economics, Inc. 2007) to define the contributions of other likely projects, actions, and trends to the 

cumulative activities (see Chapter 4.1.16.3.4 for further discussion). The analysis is for all 132 of the 

coastal counties and parishes in the analysis area (from Texas to Florida) over a 40-year period. 

Woods & Poole makes projections on local, regional, and national trend data and the assumption of a 

continuation of current patterns in OCS leasing activity and other industries important to the region. 

These projections also include Woods & Poole’s assumptions regarding the impacts of, and recovery 

from, Hurricanes Katrina and Rita on the southeastern U.S. (Chapter 3.3.5.5 of the Multisale EIS). The 

same methodology used to project changes to population from routine activities associated with a CPA or 

WPA proposed action is used for the cumulative analysis. 

Population 

Population impacts from the OCS Program (Table 4-43 in the Multisale EIS) mirror those associated 

with employment described in Chapter 4.1.16.3.4. Projected population changes reflect the number of 

people dependent on income from oil- and gas-related employment for their livelihood (e.g., family 

members of oil and gas workers), a figure based on the ratio of population to employment in the analysis 

area. Activities associated with the OCS Program are projected to have minimal effects on population in 

most of the EIA’s. Lafourche (EIA LA-3) and Lafayette (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. 
Environmental and Socioeconomic Consequences 4-193 

Using the new 2007 Woods & Poole data discussed above as the baseline, MMS recalculated the 

employment impacts of the OCS Program on a percentage basis. These revised numbers do not differ 

significantly from those presented in Table 4-44 of the Multisale EIS and mirror those discussed for OCS 

Program employment in Chapter 4.1.16.3.4. 

Age 

Cumulative activities are projected to leave the age distribution of the analysis area virtually 

unchanged. Given both the low levels of population growth and industrial expansion associated with the 

cumulative activities, it is projected that the age distribution pattern discussed in Chapter 3.3.3.4.2 in the 

Multisale EIS will likely continue throughout the 40-year 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 described in Chapter 3.3.5.4.3 of the 

Multisale EIS is projected to continue throughout the 40-year analysis period. See Chapters 3.3.5.4.1 and 

3.3.5.4.3 of the Multisale EIS for a discussion of race and ethnic composition changes in the New Orleans 

metropolitan area as a result of Hurricane Katrina. 

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 3.3.5.4.1 of the Multisale EIS, are not 

expected to change for the analysis area as a whole. Lafourche Parish (EIA LA-3), including Port 

Fourchon, in particular, and Lafayette (EIA LA-2) in Louisiana are projected to experience some impacts 

to population as of a result of increase demand of OCS labor. A CPA or WPA proposed action is 

projected to have an incremental contribution of <1 percent to the population level in any of the EIA’s. 

Given both the low levels of population growth and industrial expansion associated with the proposed 

actions, it is expected the baseline age and racial distribution pattern to continue through the analysis 

period. 

4.1.16.3. Economic Factors 

The MMS has reexamined the analysis for economic factors presented in the Multisale EIS, based on 

the additional information presented below and the addition of the 181 South Area to the proposed CPA 

sale area. New economic and demographic data (Woods & Poole Economics, Inc., 2007) analyzed and 

the addition of the 181 South Area does not change the conclusions in the Multisale EIS, which stated that 

there would be only minor economic changes in the Texas, Louisiana, Mississippi, Alabama, and Florida 

EIA’s should a proposed CPA or WPA lease sale occur. 

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

CPA or WPA proposed action, and a proposed action’s incremental contribution to the cumulative 

impacts are presented in the Multisale EIS. A summary of those analyses and their reexamination due to 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. A 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 a proposed action is expected to occur 

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

force. 

4.1.16.3.1. Decscription of the Affected Environment 

Chapter 3.3.5.5 in the Multisale EIS describes the economic factors relevant to the socioeconomic 

analysis area, including current measures of employment (Chapter 3.3.5.5.1), income and wealth (Chapter 

3.3.5.5.2), and business patterns by industrial sector (Chapter 3.3.5.5.3). This information is summarized 

below and incorporated by reference into this document. Additional supplemental information is 
4-194 Central and Western Gulf of Mexico Multisale Supplemental EIS

available regarding current economic conditions in the Gulf of Mexico region, particularly as it relates the 

recovery to date from the 2005 hurricanes. However, this new information (summarized below) does not 

in any way change the baseline population and employment projections used to analyze impacts of a 

typical sale and the OCS Program, the methodologies used, or the conclusions presented in the Multisale 

EIS. The addition of the 181 South Area to the CPA sale area does not change the onshore 

socioeconomic analysis area used in the Multisale EIS (132 coastal counties and parishes from Texas to 

Florida; Table 3-17 and Figure 3-12 in the Multisale EIS). 

The industrial composition for the EIA’s adjacent to the CPA and those adjacent to the WPA are 

similar. In 2005, the top three ranking sectors in terms of employment in all EIA’s in the analysis area, 

except FL-4, were the services, retail trade, and State and local government sectors—with the service 

industry ranking number one in all EIA’s and retail trade ranking second in all EIA’s, except FL-2, where 

State and local government is second. In FL-4, the top three rankings sectors were services; retail trade; 

and finance, insurances and real estate, in that order, with State and local government a close fourth. In 

EIA’s TX-1, LA-1, LA-3, and FL-2, construction ranks fourth; in EIA’s AL-1, MS-1, and TX-2, 

manufacturing ranks fourth; in EIA’s LA-4, TX-3, and FL-3, finance, insurance, and real estate ranks 

fourth; and in EIA LA-2, mining ranks fourth. 

Average annual employment growth projected from 2005 through 2030 ranges from a low of 1.22 

percent for EIA LA-4 to a high of 2.50 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 1.57 percent per year, while 

the Gulf of Mexico economic impact analysis area is expected to grow at about 1.73 percent per year. 

This represents growth in general employment for the EIA’s. 

In the Multisale EIS, MMS used data from Woods & Poole’s Complete Economic and Demographic 

Data Source (Woods & Poole Economics, Inc., 2006) for baseline population and employment estimates 

over the 40-year life of a typical proposed lease sale. Table 3-41 in the Multisale EIS contains the 

analysis area’s baseline employment projections by MMS-defined EIA. These projections are based on 

the Woods & Poole’s Complete Economic and Demographic Data Source (Woods & Poole Economics, 

Inc., 2006) and assume the continuation of existing social, economic, and technological trends at the time 

of the forecast. 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 projections also include Woods & Poole’s assumptions regarding Hurricanes Katrina and 

Rita’s impact on the Southeast. 

The 2007 Woods & Poole data became available in late August 2007 and contain their revised 

estimates regarding the economic and demographic impacts of the 2005 hurricanes on the Gulf region 

(Woods & Poole Economics, Inc., 2007). In the new data, population, income, and employment were 

assumed to decline from 2005 to 2006 by 76 percent in St. Bernard Parish, Louisiana; 51 percent in 

Orleans Parish, Louisiana; 22 percent in Plaquemines Parish, Louisiana; 19 percent in Cameron Parish; 

Louisiana; 13 percent in Hancock County, Mississippi; and 11 percent in Harrison County, Mississippi. 

In each case, these losses were less than those that were assumed in the 2006 Woods & Poole data. The 

2007 data also have revised assumptions regarding counties and parishes that experienced population and 

employment gains because of Hurricane Katrina displacement: 9 percent in Pearl River County, 

Mississippi; 7 percent in Tangipahoa Parish, Louisiana; 5 percent in St. John the Baptist Parish, 

Louisiana; 5 percent in East Baton Rouge Parish, Louisiana; and 4 percent in St. Charles Parish, 

Louisiana from 2005 to 2006. In each case, these gains were less than those that were assumed in the 

2006 data. Table 4-12 presents the new baseline employment estimates based on the 2007 Wood & 

Poole data that are used to analyze employment impacts in this document. 

Two years after Hurricanes Katrina and Rita, the recovery remains uneven throughout the areas 

originally affected. Areas where the most severe problems remain are Orleans and St. Bernard Parishes, 

Louisiana, and Hancock County, Mississippi. Affordable housing continues to be a problem in these 

areas, particularly in New Orleans. Adding to the problem is the high cost of insurance and building 

materials, causing many prospective developers to postpone projects until these issues are better resolved. 

Recovery is well underway in Jefferson and Calcasieu Parishes, Louisiana, as well as in Biloxi, Gulfport, 

and Pascagoula, Mississippi; and Bayou La Batre, Alabama. Recovery is driving expansion in East Baton 

Rouge and St. Tammany Parishes in Louisiana; Jackson, Hattiesburg, and Laurel, Mississippi; and in 

Gulf Shores and Mobile, Alabama. The measures of recovery are the functions of local government, 
Environmental and Socioeconomic Consequences 4-195 

population, crime, economic and fiscal effects, local government budgets, housing, and labor (Rowley, 

2007). 

Researchers continue to study the employment impacts of the 2005 hurricane season. The Bureau of 

Labor Statistics did a special review of the employment impacts of Hurricane Katrina and found that St. 

Bernard, Orleans, and Jefferson Parishes had the largest percent declines in employment between 

September 2004 and September 2006 (38%, 27%, and 24.5%, respectively). In the two months following 

Hurricane Katrina, nonfarm payroll employment in Louisiana fell by 241,000, a decline of 12 percent; in 

the New Orleans metro area, employment declined by 215,000, or 35 percent. In the New Orleans metro 

area in June 2006, it was 30 percent below the level a year earlier. Total nonfarm employment in 

Louisiana decreased by 184,600 jobs or 9.6 percent from September 2004 to September 2005; in May 

2006, the year-to-year loss was 177,700 jobs or 9.1 percent (U.S. Dept. of Labor, Bureau of Labor 

Statistics, 2006; pages 2, 4, 6, 8, 27, and 28). However, more recent data show nonfarm payroll 

employment in Louisiana increasing 3.8 percent between April 2006 and April 2007 (one of the largest 

over-the-year percentage gains in employment for a State), or an increase of 69,500 from 1,835,700 to 

1,905,200 (U.S. Dept. of Labor, Bureau of Labor Statistics, 2007). 

Estimating employment data has proven more difficult post-Hurricane Katrina, and some previous 

estimates are being revised as data-gathering limitations are addressed. For example, the Atlanta Federal 

Reserve Bank announced a revision to their employment estimates for Louisiana from 1,766,400 to 

1,844,300 (an increase of 77,900 or 4.4%) between March 2005 and March 2006. Much of the revision 

was to account for job growth in the State’s construction industry that had been underestimated due to 

survey sampling issues (such as identifying and sampling new construction businesses). Professional and 

business services is another industry where employment in Louisiana appears to have been originally 

underestimated (Federal Reserve Bank of Atlanta, 2006). 

Researchers also continue to examine the impacts of the 2005 hurricane season on businesses in the 

region. For example, a Louisiana State University report on the hurricanes’ effect on businesses 

comparing the second quarter of 2005 with the second quarter of 2006 concludes that, after a decline of 

over 5,000 in the number of employers (5.3%), the entire State of Louisiana had 2,270 fewer employers 

(2.3%) 1 year after the hurricanes (Terrell and Bilbo, 2007). The business failure rate in the year after the 

storms was 11.7 percent for the State as a whole compared with 26.5 percent for the five-parish Southeast 

region. 

4.1.16.3.2. Impacts of Routine Events 

Background/Introduction 

The detailed description of possible impacts on economic factors, primarily employment, from 

routine activities associated with a CPA or WPA proposed action is given in Chapters 4.2.2.1.15.3 and 

4.2.1.1.13.3 of the Multisale EIS. 

The economic analysis for a proposed lease sale in the CPA or WPA 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. The MMS 

uses a two-stage economic impact model, called MAG-PLAN, where the first stage estimates the 

expenditures required to support the activity levels in a specific exploration and development scenario, 

and allocates these expenditures to the various industrial sectors in the onshore economic impact areas. 

The activities are meant to be comprehensive, including exploration drilling, platform fabrication and 

installation, pipeline construction and installation, and various other construction and maintenance 

functions required to support the phases of developments (including platform removals). High- and lowrange estimates of activity drawn from this scenario form the basis for a range of estimates of 

employment. 

The second stage of the model estimates how the initial dollars spent in a geographic area reverberate 

through the economy, using multipliers taken from the widely used IMPLAN model. Thus, the 

employment projections presented in this document represent total employment impacts (i.e., direct, 

indirect, and induced). Total employment projections for activities resulting from a CPA or WPA 

proposed action are expressed as absolute numbers and as a percentage of the baseline employment 

projections described above in Chapter 4.1.16.3.1 and as shown on Table 4-12. 
4-196 Central and Western Gulf of Mexico Multisale Supplemental EIS

CPA Proposed Action Analysis 

No new data or information was found that indicated that the MAG-PLAN data used in the Multisale 

EIS was not still valid for projecting likely future activity. Although the addition of the 181 South area 

increases some activity scenario parameters (e.g., production), the net annual increases to activity are not 

substantial enough to affect overall employment projections. Thus, the employment projections from the 

Multisale EIS are still considered to be the best available and are summarized below. 

Based on MAG-PLAN model results, direct employment associated with a proposed CPA lease sale 

is estimated at about 3,700-9,150 jobs during the peak impact year for the low- and high-case scenarios, 

respectively (Tables 4-30 and 4-31 in the Multisale EIS). Indirect employment is projected at about 

1,600-3,650 jobs, while induced employment is calculated to be about 2,500-5,750. Thus, total 

employment resulting from a proposed CPA lease sale is not expected to exceed 7,800-18,550 jobs in any 

given year over a proposed action’s 40-year lifetime. Most of the employment related to a 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 7,800-18,550 jobs would be staffed with existing company labor force and would simply maintain 

the status quo. Thus, these employment projections are likely to overestimate the actual magnitude of 

new employment effect from a 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, 

MMS anticipates that very few OCS-related activities will be staged from Florida. 

Using the new 2007 Woods & Poole data discussed above as the baseline, MMS recalculated the 

employment impacts on a percentage basis. These revised numbers do not differ significantly from those 

presented in the Multisale EIS. Employment is not expected to exceed 1 percent of the total employment 

in any given EIA of Texas, Louisiana, Mississippi, Alabama, or Florida. On a percentage basis, EIA’s 

LA-2 and LA-3 are still projected to have the greatest employment impacts at 0.5 percent. EIA LA-4 is 

still projected to have the next greatest impact at 0.3 percent (compared with 0.4 percent in the Multisale 

EIS), followed by EIA TX-3, which is still at 0.2 percent. EIA LA-1 dropped to 0.1 percent compared 

with 0.2 percent in the Multisale EIS. 

WPA Proposed Action Analysis 

No new data or information was found that indicated that the exploration and development scenarios 

or internal MAG-PLAN data used in the Multisale EIS was not still valid projections of likely future 

activity. Thus, the employment projections from the Multisale EIS are still considered to be the best 

available and are summarized below. 

Based on MAG-PLAN model results, direct employment associated with a proposed WPA lease sale 

is estimated at about 1,300-2,350 jobs during the peak impact year for the low- and high-case scenarios, 

respectively (Tables 4-22 and 4-23 in the Multisale EIS). Indirect employment is projected at about 550-

950 jobs, while induced employment is calculated to be about 850-1,500. Thus, total employment 

resulting from a WPA lease sale is not expected to exceed 2,700-4,800 jobs in any given year over a 

proposed action’s 40-year lifetime. Most of the employment related to a WPA proposed action is 

expected to occur in Texas (EIA TX-3) and Louisiana (EIA’s LA-2 and LA-3). 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 2,700-4,800 

jobs would be staffed with existing company labor force and would simply maintain the status quo. Thus, 

these employment projections are likely to overestimate the actual magnitude of new employment effect 

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, MMS anticipates 

that very few OCS-related activities will be staged from Florida. 

Using the new 2007 Woods & Poole data discussed above as the baseline, MMS recalculated the 

employment impacts on a percentage basis. These revised numbers do not differ significantly from those 

presented in the Multisale EIS. Employment is not expected to exceed 1 percent of the total employment 

in any given EIA of Texas, Louisiana, Mississippi, Alabama, or Florida. On a percentage basis, EIA 
Environmental and Socioeconomic Consequences 4-197 

LA-2 is still projected to have the greatest employment impact at 0.2 percent, followed by LA-3 and 

TX-3, both at 0.1 percent. 

Summary and Conclusion 

Should a proposed CPA or WPA lease sale occur, there would be only minor economic changes in 

the Texas, Louisiana, Mississippi, Alabama, and Florida EIA’s. A CPA or WPA 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 a proposed action is expected to occur in Texas (EIA TX-3) and Louisiana (EIA’s 

LA-2, LA-3, and LA-4). The demand would be met primarily with the existing population and labor 

force for reasons discussed above. 

4.1.16.3.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of the possible impacts from accidental events associated with a CPA or WPA 

proposed action on economic factors, primarily employment, is presented in Chapter 4.4.14.3 of the 

Multisale EIS. Accidental events associated with a CPA or WPA proposed action, such as oil or chemical 

spills, blowouts, and vessel collisions, will likely have minimal, if any, net effects on employment. 

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 non-market 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 (Pulsipher et al., 1999). Chapters 4.4.12, 4.4.13, and 4.4.14 include 

additional discussions of the potential consequences of an oil spill on commercial and recreational 

fishing, and recreational beaches. 

The employment impacts from a vessel collision or blowout are likely to be shorter term and less than 

those from a spill. Most blowouts last for a short duration, with half lasting less than a day. 

CPA Proposed Action Analysis 

Chapters 4.3.1.5, 4.3.1.6, and 4.3.4 in the Multisale EIS depict the risks and number of spills 

estimated to occur for a proposed action. The probabilities of an offshore oil 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. Figures 3-6 and 3-7 show the Gulf of Mexico coastal 

counties and parishes having a risk >0.5 percent of being contacted within 10 days by an offshore oil spill 

≥1,000 bbl as a result of a 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 1-15 percent chance of an 

OCS offshore oil spill ≥1,000 bbl occurring and reaching their shoreline within 10 days as the result of a 

proposed action over its 40-year life. In Louisiana, Plaquemines Parish has the greatest risk (10-15%) of 

an oil spill occurring and contacting its shoreline within 10 days as a result of a CPA proposed action. 

The MMS 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 an individual 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 a 

proposed action or the OCS Program is very unlikely. 

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 a CPA proposed action. 

The employment impacts from a vessel collision or blowout are likely to be shorter term and less than 

those from a spill. There are 2-3 blowouts estimated as a result of a CPA proposed action. 
4-198 Central and Western Gulf of Mexico Multisale Supplemental EIS

WPA Proposed Action Analysis 

Chapters 4.3.1.5, 4.3.1.6, and 4.3.4 in the Multisale EIS depict the risks and number of spills 

estimated to occur for a proposed action. The probabilities of an offshore oil 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. Figures 3-6 and 3-7 show the Gulf of Mexico coastal 

counties and parishes having a risk >0.5 percent of being contacted within 10 days by an offshore oil spill 

≥1,000 bbl as a result of a WPA 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; six counties in Texas and one parish in Louisiana have a 1-5 percent chance of an OCS 

offshore oil spill ≥1,000 bbl occurring and reaching their shoreline within 10 days as the result of a 

proposed action over its 40-year life. In Texas, Matagorda County has the greatest risk (3-5%) of being 

contacted within 10 days by an oil spill occurring offshore as a result of a WPA proposed action. The 

MMS 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 a 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 a proposed action or OCS 

Program is very unlikely 

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 a WPA proposed action. 

The employment impacts from a vessel collision or blowout are likely to be shorter term and less than 

those from a spill. There are 1-2 blowouts estimated as a result of a WPA 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 opportunity cost of employment and expenditures that could have been gone to 

production or consumption rather than spill cleanup efforts. Non-market 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, shortterm 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. 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 a CPA or WPA proposed action. The employment impacts from a vessel 

collision or blowout are likely to be shorter-term and less than those from a spill. 

4.1.16.3.4. 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. The following is a summary of the information presented 

in the Multisale EIS, which incorporates new information found since the publication of the Multisale 

EIS. 

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 (from Texas to Florida) over a 40-year period. Instead of an arbitrary 

assemblage of future possible projects and actions, the analysis employs the economic and demographic 
Environmental and Socioeconomic Consequences 4-199 

projections from Woods & Poole Economics, Inc. (2007) to define the contributions of other likely 

projects, actions, and trends to the cumulative case. These projections are based on local, regional, and 

national trend data as well as likely changes to local, regional, and national economic and demographic 

conditions. Therefore, the projections include employment associated with the continuation of current 

patterns in OCS leasing activity as well as the continuation of trends in other industries important to the 

region. These Woods & Poole projections represent a more comprehensive and accurate appraisal of 

cumulative conditions than could be generated using the traditional list of possible projects actions. 

These projections also include Woods & Poole’s assumptions regarding Hurricanes Katrina and Rita’s 

impact on the Southeast (Chapter 4.1.16.3.1). Hence, the regional economic impact assessment 

methodology used to estimate changes to employment for a proposed lease sale was used for the 

cumulative analysis. 

Tables 4-45 and 4-46 in the Multisale EIS present projected employment associated with the OCS 

Program. Based on these model results, direct employment in the MMS-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 peak period. Therefore, total employment resulting from OCS Program activities in the 

MMS-defined EIA is not expected to exceed 257,000-328,000 jobs in any given year over the 40-year 

impact period. 

Using the new 2007 Woods & Poole data discussed above as the baseline, MMS 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. 

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 2.9 percent (compared with 3.1% in the Multisale EIS) of the 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 greater in LA-2, reaching a maximum of nearly 

20.3 percent (compared with 21% in the Multisale EIS) versus about 8 percent in LA-3. While these 

numbers are high, it is important to remember that they are overestimates because the baseline projections 

already include employment resulting from the continuation of current patterns in OCS Program 

activities. Hence, forecasting total employment from the OCS Program and then dividing by a number 

that already includes all of the employment from previous OCS Program actions significantly 

overestimates the impacts of the OCS Program on a percentage basis. Also, the percentage analysis is 

highly dependent on the baseline employment projections, which are somewhat 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 follows 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 (Dismukes, personal 

communication, 2006). The next greatest impacts in percentage terms are in LA-4, LA-1, and TX-2, 

respectively, with none exceeding 5 percent in any given year. The OCS-related employment for TX-1 

and all of Alabama, Mississippi, and Florida’s EIA’s is not expected to exceed 1.8 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 MMS does expect some employment will be met 

through in-migration; however, this level is projected to be small and localized and, thus, MMS 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 

Louisiana. 

On a regional level, the cumulative impact on the population, labor, and employment of the counties 

and parishes of the impact area is considerable for some focal points. Port Fourchon is experiencing full 

employment, housing shortages, and stresses on local infrastructure—roads (LA Hwy 1), water supply, 
4-200 Central and Western Gulf of Mexico Multisale Supplemental EIS

schools, hospitals, etc. Port Fourchon is a focal point for OCS development, especially deepwater OCS 

operations. As discussed in Chapter 4.1.16.1.2 above, Port Fourchon would most likely be the primary 

service base to support oil and gas activity in the 181 South Area in the near term. The proposed actions 

would contribute to a small percentage of the projected OCS-related activity at Port Fourchon. Any 

additional employment, particularly new residential employment, and the resultant strain on 

infrastructure, due to the OCS Program, are expected to have a significant impact on the area. 

The resource costs of cleaning up an oil spill, either onshore or offshore, were not included in the 

above cumulative analysis. Chapter 4.3.1 in the Multisale EIS discusses the risk of spill occurrence, the 

number of spills estimated for the OCS Program, and the likelihood of an OCS-spill contacting the Gulf 

Coast. A discussion of how a spill would affect the cumulative impacts to economic factors, primarily 

employment, can be found in Chapter 4.5.15.3 of the Multisale EIS. Chapters 4.4.10 and 4.4.12 in the 

Multisale EIS contain more discussions of the consequences of a spill on fisheries and recreational 

beaches. 

Summary and Conclusion 

The OCS Program will produce only minor economic changes in the Texas, Mississippi, Alabama, 

and Florida EIA’s. With the exception of EIA TX-3, the OCS Program is expected to represent 

<2 percent of employment projected in any of the EIA’s in these states. Employment associated with the 

OCS Program reaches 2.9 percent (compared with 3.1% in the Multisale EIS) of total projected 

employment for EIA TX-3. 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 8.0 percent of total 

employment, respectively. On a regional level, activities relating to the OCS Program are expected to 

significantly impact employment in Lafourche Parish, Louisiana, in EIA LA-3. Therefore, the 

population, housing, roads (LA Hwy 1), water supply, schools, and hospitals in the parish will be affected 

and strained. The proposed actions would contribute to a small percentage of the projected OCS-related 

activity at Port Fourchon. 

The short-term social and economic consequences for the Gulf coastal region should a spill ≥1,000 

bbl occur includes opportunity cost of employment and expenditures that could have gone to production 

or consumption rather than spill-cleanup efforts. Non-market 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 an oil 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. Overall 

employment projected for all oil and gas activities related to the OCS Program, including employment 

impacts from oil spills, is projected to be substantial (particularly in EIA’s TX-3, LA-2, and LA-3). 

As discussed in Chapter 4.1.16.3.2, a CPA or WPA proposed action is expected have an incremental 

contribution of <1 percent to the employment level in any of EIA’s. 

4.1.16.4. Environmental Justice 

The MMS has reexamined the analysis for environmental justice presented in the Multisale EIS, 

based on the additional information presented below and the addition of the 181 South Area to the 

proposed CPA sale area. No significant new information was found that would alter the impact 

conclusion for environmental justice as presented in the Multisale EIS. The 181 South Area is located at 

the eastern edge of the CPA sale area nearly 130 mi (209 km) from the nearest coast. Also, the 181 South 

Area is projected to result in a relatively minor amount of additional sale-related activity. This limited 

activity will have few impacts; the location of the 181 South Area means that any impacts that may result 

are unlikely to be concentrated in an area that could disproportionately impact minority or low income 

people. Therefore, no additional impacts on minority or low-income people are projected as a result of 

the inclusion of the 181 South Area. 

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

CPA or WPA proposed action, and a 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 
Environmental and Socioeconomic Consequences 4-201 

new information and the addition of the 181 South Area is presented in the following sections. A brief 

summary of potential impacts follows. Because the proposed CPA sale area lies 3 or more mi (5 or more 

km) offshore, no activities that occur on the resulting leases (and that are regulated by MMS) will impact 

directly 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 actions are not expected to have disproportionately high or adverse environmental or health 

effects on minority or low-income people. The CPA and WPA proposed actions would help to maintain 

ongoing levels of activity rather than expand them. The cumulative environmental justice impacts from 

non-OCS activities have made, and will make, substantially larger contributions to the environmental 

justice effects than will the OCS Program. The incremental contribution of the CPA and WPA proposed 

actions to cumulative impacts would be minor. 

4.1.16.4.1. Description of the Affected Environment 

A detailed description of environmental justice is found in Chapter 3.3.5.10 of the Multisale EIS. The 

following is a summary of the information presented in the Multisale EIS. It incorporates new 

information found since the publication of the Multisale EIS and considers the additional sale-related 

activity expected to be associated with 181 South Area. The 181 South Area is located at the eastern edge 

of the CPA sale area nearly 130 mi (209 km) from the nearest coast. Also, the 181 South Area is 

projected to result in a relatively minor amount of additional sale-related activity. This limited activity 

will have few impacts; the location of the 181 South Area means that any impacts that may result are 

unlikely to be concentrated in an area that could disproportionately impact minority or low-income 

people. Therefore, no additional impacts on minority or low-income people are projected as a result of 

the inclusion of the 181 South Area. 

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 with low incomes. Those environmental effects encompass human health, 

social, and economic consequences. The Federal agency in charge of the proposed action must provide 

opportunities for community input during the NEPA process (see Chapter 5 for a discussion of scoping 

and community consultation and coordination). 

The MMS manages the Nation’s energy resources on the OCS. Because this area is 3 or more mi (5 

or more km) offshore, well distant from human habitation, the routine activities that occur on OCS leases 

and that are managed by MMS do not have environmental justice impacts. For this SEIS, environmental 

justice concerns result indirectly from a proposed action, from nearshore and onshore activities conducted 

in support of offshore exploration, development and production, and these concerns result from the 

accidental release of petroleum (oil spills). 

The nearshore and onshore activities that raise environmental justice concerns are associated with the 

operations of OCS-related infrastructure. During the past 60 years, State and Federal governmental 

agencies have leased substantial areas for petroleum development off Texas, Louisiana, Mississippi, and 

Alabama, and the industry has built an extensive support infrastructure system. A 2004 MMS study 

describes the major categories of existing OCS-related infrastructure (Louis Berger Group, Inc., 2004). 

Figures 3-13 through 3-15 of the Multisale EIS illustrate the distribution of the facilities identified 

throughout the Gulf Coast. This support-system infrastructure is described in detail in Chapter 3.3.5.8 of 

the Multisale EIS. This system includes “upstream” infrastructure supporting the development and 

production of offshore oil (e.g., shipbuilding and fabrication yards, supply ports, and pipeyards) and 

“downstream” infrastructure that gets the product to market (e.g., pipelines, refineries, and petrochemical 

plants). This environmental justice analysis emphasizes upstream infrastructure and pipelines because 

these operations are influenced by offshore activities (e.g., new demand for platforms); therefore, they can 

be affected by the OCS Program, while downstream operations such as refining are driven by consumer 

demand and, hence, are not affected by the OCS Program. 

The OCS-related infrastructure is unevenly distributed across the Gulf of Mexico region. Table 3-40 

of the Multisale EIS identifies the counties and parishes with concentrated levels of oil- and gas-related 
4-202 Central and Western Gulf of Mexico Multisale Supplemental EIS

infrastructure. Much upstream infrastructure is located in coastal Louisiana and less in coastal Texas, 

Mississippi, and Alabama. Downstream processing is concentrated more in industrial corridors farther 

inland located in Texas and Louisiana and less in Mississippi and Alabama. Environmental justice maps 

(Figures 3-21 through 3-26 of the Multisale EIS) illustrate that the location of oil-related infrastructure 

does not coincide geographically with higher proportions of low-income and minority residents across 

Gulf of Mexico counties and parishes. 

The OCS infrastructure is widespread in coastal Louisiana, but concentrated in Lafourche Parish. 

The majority of OCS-related infrastructure in Lafourche Parish is in the southern portion where the 

Houma Indian population resides. South Lafourche Parish still provides valuable habitat land for 

traditional subsistence activities such as hunting, fishing, and trapping practiced by the Houma and other 

groups in the area (Hemmerling and Colten, 2003). 

Figures 3-21 through 3-23 of the Multisale EIS indicate the substantial proportions of AfricanAmerican and Hispanic persons along the coast. Also, some counties and parishes have populations of 

Native Americans. While most of the percentages are quite small—three-quarters are 0.5 percent or 

less—two counties and two parishes have 2- 5 percent Native American population. The Mowa Choctaw 

tribe of Washington County, Alabama, constitutes 5 percent of the county’s population. The United 

Houma Nation represents 4 percent of the population of Terrebonne Parish, Louisiana, and just over 

2 percent of Lafourche Parish, Louisiana. The Alabama-Coushatta tribe is 2 percent of the population of 

Polk County, Texas. 

Offshore workers in the production sector are almost entirely male and white (Rosenberg, personal 

communication, 2001). 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 b; Donato et al., 1998). 

Hurricane Katrina in 2005 had disproportionate impacts on the Gulf Coast population. In addition, 

the three states where Hurricane Katrina flooded and damaged communities rank among the poorest in 

the country. Approximately one-fifth (21%) of the population most directly affected by the storm was 

poor. Also see Chapter 3.3.5.4.1 of the Multisale EIS for further discussion of the effects of Hurricanes 

Katrina and Rita on minority populations. 

An analysis of Federal Emergency Management Agency (FEMA) storm-damage data shows that 

Hurricane Katrina’s impact was disproportionately borne by the region’s African-American community, 

by people who rented their homes, and by the poor and unemployed. According to FEMA, more than 

one-third of the region’s 1.7 million residents lived in areas that suffered flooding or moderate to 

catastrophic storm damage. . The majority of people living in damaged areas were in the City of New 

Orleans (over 350,000), with additional concentrations in suburban Jefferson Parish (175,000) and St. 

Bernard Parish (53,000) and along the Mississippi Coast (54,000). In the region as a whole, the 

disparities in storm damage are shown in the following comparisons (arranged in order of the degree of 

disparity): by race–damaged areas were 46 percent black, compared with 26 percent in undamaged areas; 

by housing tenure–46 percent of homes in damaged areas were occupied by renters, compared with 31 

percent in undamaged communities; and by poverty and employment status–21 percent of households had 

incomes below the poverty line in damaged areas, compared with 15 percent in undamaged areas, and 7.6 

percent of persons in the labor force were unemployed in damaged areas (before the storm), compared 

with 6.0 percent in undamaged areas. These comparisons are heavily influenced by the experience of the 

City of New Orleans. Outside the city, there were actually smaller shares of African-American, poor, and 

unemployed residents in the damaged areas. A closer inspection of neighborhoods within New Orleans 

shows that some affluent white neighborhoods were hard hit, while some poor minority neighborhoods 

were spared. Yet, if the post-Hurricane Katrina city was limited to the population previously living in 

areas that were undamaged by the storm―that is, if nobody were able to return to damaged 

neighborhoods―New Orleans is at risk of losing more than 80 percent of its black population (Logan, 

2007). 

Hurricane Katrina lifted and dislodged a 250,000-bbl storage tank at the Murphy Oil Refinery in St. 

Bernard Parish, Louisiana. The USEPA is monitoring Murphy Oil’s cleanup (USEPA, 2006b). 

Communities such as St. Bernard Parish, Louisiana, are potentially vulnerable to such accidents because 

of their close proximity to OCS-related infrastructure. 

The Multisale EIS states the following: “Evidence also suggests that a healthy offshore petroleum 

industry also indirectly benefits low-income and minority populations.” One MMS study in Louisiana 
Environmental and Socioeconomic Consequences 4-203 

found income inequality decreased during the oil boom and increased with the decline (Tolbert, 1995). 

The following updated information relates to this point. 

A follow-up study to Tolbert (1995) about Abbeville, Louisiana, resulted in the following findings. A 

study component of a plant closure in Abbeville found that more employment opportunities exist within 

the community and surrounding area because, indirectly, growth of the oil and gas industry has served as 

an impetus in creating other labor-market opportunities. A study component of industrial composition 

finds that a key source of sustainability from economic fluctuations at one time may be problematic at 

another time. Conversely, a problematic sector of the local economy at one time period may be proven to 

be a stabilizing sector at another time. These sectors include the oil and gas industry, manufacturing, and 

others. The particular lesson in the Abbeville context is that shifting sectors can be sustained by strong 

business services and professional sectors. The conclusions of Tolbert (2006) appear to qualify the 

conclusions of Tolbert (1995). 

4.1.16.4.2. Impacts of Routine Events 

Background/Introduction 

A detailed description of routine impacts on environmental justice issues associated with a CPA or 

WPA proposed action can be found in Chapters 4.2.2.1.15.4 and 4.2.1.1.13.4 of the Multisale EIS, 

respectively. The following is a summary of the information presented in the Multisale EIS, which 

incorporates new information found since publication of the Multisale EIS. 

Routine impact-producing factors that raise environmental justice concerns center on increases in 

onshore activity and additions to the infrastructure supporting this activity. Increases in onshore activity 

include dimensions such as employment, migration, commuter traffic, and truck traffic. Additions to the 

infrastructure include possible additions to fabrication yards, supply ports, and onshore disposal sites for 

offshore waste. Chapter 3.3.5 of the Multisale EIS describes the widespread presence of an extensive 

OCS infrastructure support system and associated labor force, as well as economic factors related to OCS 

activities. 

CPA Proposed Action Analysis 

Environmental justice issues involve questions of disproportionate and negative effects on minority 

and low-income populations. Chapter 3.3.5.10 of the Multisale EIS provides a description of existing 

conditions. No predictions are made regarding employment of minority or low-income people or the 

location of new infrastructure. A CPA proposed action is expected to generate slight increases in 

employment opportunities in a wide range of businesses along the Gulf Coast. 

Various economic and socioeconomic variables can affect how to assess environmental justice 

impacts (Singelmann, personal communication, 2006). In general, the oil and gas industry has had a 

slight, indirect, but positive effect on the employment of minority and low-income populations by 

providing local economic opportunities. It may also be, at times, a key sector of sustainability from 

economic fluctuations (although problematic at other time). Shifting sectors can sustain strong business 

services and professional sectors (Tolbert, 1995 and 2006; Tobin, 2001).

One dimension of environmental justice impact analysis is that siting of infrastructure in certain 

places will have disproportionate and negative effects on minority and low-income populations. A CPA 

proposed action will contribute to maintaining ongoing levels of activity rather than expanding them and 

is not expected to generate new infrastructure demand sufficient to raise siting issues. 

Because of Louisiana’s extensive oil-related, infrastructure support system (Chapter 3.3.5.8 of the 

Multisale EIS), Louisiana is likely to experience more employment effects related to a CPA proposed 

action than are the other coastal states. Lafourche Parish, Louisiana, is likely to experience the greatest 

concentration and is the only parish where the additional OCS-related activities and employment are 

sufficiently concentrated to increase stress to its infrastructure. Even so, the effects of a proposed action 

in Lafourche Parish are not anticipated to be significant in the long term or to have disproportionate 

effects on minority and low-income populations for two reasons. First, the parish is not predominately 

minority or low income (Figures 3-22 and 3-25 of the Multisale EIS). Second, while the majority of 

OCS-related infrastructure is located in south Lafourche Parish where the Houma Indian population is 
4-204 Central and Western Gulf of Mexico Multisale Supplemental EIS

concentrated (a State of Louisiana recognized Native American tribe that is a possible environmental 

justice concern), the Houma Indians are not residentially segregated. A CPA proposed action would not 

significantly alter this preexisting situation of substantial onshore infrastructure and employment located 

proximate to each other. Therefore, minority and low-income populations, including the Houma Indians, 

are not expected to sustain disproportionate adverse effects from a CPA proposed action. 

Two local infrastructure issues described in Chapter 3.3.5.2 of the Multisale EIS raise environmental 

justice concerns in this area—traffic on LA Hwy 1 and the Port Fourchon expansion. The most serious 

concern raised is the high-level of traffic on LA Hwy 1. Increased truck traffic destined for Port 

Fourchon physically stresses the highway, inconveniences and sometimes disrupts local communities, and 

may pose health risks in the form of increased accident rates and possible interference to hurricane 

evacuations (Keithly, 2001; Hughes et al., 2001). As described in Chapter 3.3.5.2 of the Multisale EIS, 

the area’s “string settlement pattern” means that all income groups alike live on a narrow band of high 

ground along LA Hwy 1 and will be equally affected by any increased traffic. Port Fourchon is relatively 

new and is surrounded by mostly uninhabited land. Existing residential areas close to the port are also 

new and not considered low-income or minority areas. Expansion of infrastructure at Port Fourchon is 

not expected to affect minority or low-income populations disproportionately. Lafourche Parish is an 

area of relatively low unemployment because of the concentration of petroleum-related industry in the 

area (Hughes et al., 2001). Because of these factors, minority and low-income populations of Lafourche 

Parish will not experience any disproportionate impacts compared with the rest of the parish population 

resulting from a CPA proposed action. 

The MMS has reevaluated baseline conditions pertaining to environmental justice in light of the 

impacts of hurricane activity in the Gulf of Mexico in 2005. While this hurricane activity affected all the 

residents of impacted coastal communities, in some areas it may have disproportionately impacted the 

size and distribution of minority and low-income populations. However, the 2005 hurricanes did not 

cause major shifting in the location of onshore support infrastructure nor increases in the size or 

concentration of minority and low-income populations associated with this infrastructure. Therefore, 

differences in post-2005 conditions do not change the CPA environmental justice conclusions. 

WPA Proposed Action Analysis 

Environmental justice issues involve questions of disproportionate and negative effects on minority 

and low-income populations. No predictions are made regarding employment of minority or low-income 

people or the location of new infrastructure. A WPA proposed action is expected to generate slight 

increases in employment opportunities in a wide range of businesses along the Gulf Coast. 

Various economic and socioeconomic variables can affect how to assess environmental justice 

impacts (Singelmann, personal communication, 2006; Tolbert, 1995; and Tobin, 2001). More 

employment opportunities exist with a community because growth of the oil and gas industry has served 

as an impetus. A key sector of sustainability from economic fluctuations at one time may be problematic 

at another time. Shifting sectors can sustain strong business services and professional sectors (Tolbert, 

2006). 

One dimension of environmental justice impact analysis is that siting of infrastructure in certain 

places can have disproportionate and negative effects on minority and low-income populations. A WPA 

proposed action will contribute to maintaining ongoing levels of activity rather than expanding them and 

is not expected to generate new infrastructure demand sufficient to raise siting issues. 

Because of Louisiana’s extensive oil-related infrastructure support system (Chapter 3.3.5.8 of the 

Multisale EIS), Louisiana is likely to experience more employment effects related to a WPA proposed 

action than are the other coastal states. Lafourche Parish, Louisiana, is likely to experience the greatest 

concentration and is the only parish where the additional OCS-related activities and employment are 

sufficiently concentrated to increase stress to its infrastructure. Even so, the effects of a proposed action 

in Lafourche Parish are not expected to be significant in the long term or to have disproportionate effects 

on minority and low-income populations for two reasons. First, the parish is not predominately minority 

or low income (Figures 3-22 and 3-25 of the Multisale EIS). Second, while the majority of OCS-related 

infrastructure is located in south Lafourche where the Houma Indian population (a tribe with State of 

Louisiana recognition) is concentrated, the Houma Indians are not residentially segregated. Since the 

cumulative would not significantly alter this preexisting situation where substantial onshore infrastructure 
Environmental and Socioeconomic Consequences 4-205 

and employment already exist, minority and low-income populations including the Houma Indians would 

not sustain disproportionate adverse effects from a WPA proposed action. 

Two local infrastructure issues described in Chapter 3.3.5.2 of the Multisale EIS raise environmental 

justice concerns—traffic on LA Hwy 1 and the Port Fourchon expansion. Increased truck traffic destined 

for Port Fourchon physically stresses the highway, inconveniences and sometimes disrupts local 

communities, and may pose health risks in the form of increased accident rates and possible interference 

to hurricane evacuations (Keithly, 2001; Hughes et al., 2001). As described in Chapter 3.3.5.2 of the 

Multisale EIS, the area’s “string settlement pattern” means that all income groups alike live on a narrow 

band of high ground along LA Hwy 1 and will be equally affected by any increased traffic. Port 

Fourchon is relatively new and is surrounded by mostly uninhabited land. Existing residential areas close 

to the port are also new and not considered low-income or minority areas. Therefore, any expansion of 

infrastructure at Port Fourchon will not disproportionately affect minority or low-income populations. 

Lafourche Parish is an area of relatively low unemployment because of the concentration of petroleumrelated industry in the area (Hughes et al., 2001). Minority and low-income populations of Lafourche 

Parish are not expected to experience any disproportionate impacts compared with the rest of the parish 

population resulting from a WPA proposed action. 

The baseline conditions pertaining to environmental justice were reevaluated in the light of the 2005 

hurricane activity in the Gulf of Mexico. This hurricane activity had severe impacts on many coastal 

communities and many of these impacts fell disproportionately on minority and low-income populations. 

However, these changes did not cause a major shift in the distribution of the onshore infrastructure nor 

did they increase the number or percentage of minority and low-income populations residing near this 

infrastructure. Therefore, the environmental justice conclusions do not change 

Summary and Conclusion 

Because of the existing extensive and widespread infrastructure support system for OCS-related 

industry and associated labor force, the effects of a CPA or WPA proposed action are expected to be 

widely distributed and minimal. A proposed action is expected to generate employment that will have a 

limited but positive effect on low-income and minority populations. Given that existing industry 

infrastructure does not geographically coincide with higher proportions of minority and low-income 

peoples, a proposed action is not expected to have a disproportionate effect on these populations. 

Lafourche Parish will experience the most concentrated effects of a proposed action. Low-income or 

minority groups, including the Houma Indians, are not expected to experience effects disproportionately 

for two reasons. First, the parish is not predominately low-income or minority. Second, while the 

majority of OCS-related infrastructure is located in south Lafourche where the Houma Indian population 

(a tribe with State of Louisiana recognition) is concentrated, the Houma Indians are not residentially 

segregated. Since a proposed action would not significantly alter this preexisting situation where 

substantial onshore infrastructure and employment already exist, minority and low-income populations 

including the Houma Indians would not sustain disproportionate adverse effects. 

A CPA or WPA proposed action would help to maintain ongoing levels of activity rather than expand 

them. A proposed action is not expected to have disproportionately high or adverse environmental or 

health effects on minority or low-income people. 

4.1.16.4.3. Impacts of Accidental Events 

Background/Introduction 

A detailed description of analysis of accidental impacts on environmental justice can be found in 

Chapter 4.4.14.4 of the Multisale EIS. The following is a summary of the information presented in the 

Multisale EIS, which incorporates new information found since publication of the Multisale EIS. 

An environmental justice concern is the potential oil spills associated with a CPA or WPA proposed 

action that would enter or occur in coastal waters. Oil spills potentially could affect the many people who 

use those waters for fishing, diving, boating, and swimming, and they could have negative economic and 

health impacts. 
4-206 Central and Western Gulf of Mexico Multisale Supplemental EIS

Should an oil spill occur and contact coastal areas, any adverse effects are not likely to 

disproportionately impact minority or low-income populations. First, the populations immediately 

adjacent to the coast that might be affected are not physically, culturally, or economically homogenous. 

Second, these populations are not predominately minority or low income. The homes and summer homes 

of the relatively affluent line much of the Gulf Coast, and this process of gentrification is ongoing. As 

shown by Figures 3-21 through 3-26 and as discussed in Chapter 3.3.5.10 of the Multisale EIS, coastal 

concentrations of minority and low-income populations are few and mostly urban. The higher 

probabilities of oil contacting land in Louisiana are centered on South Pass and Southwest Pass at the 

confluence of the deltaic plain and the Gulf of Mexico (Chapter 4.3.1 of the Multisale EIS). In Louisiana, 

Grand Isle is the only inhabited barrier island, and this community is not predominantly minority or low 

income. Most of the Louisiana coast, including South Pass, Southwest Pass, and the shorelines 

surrounding Morgan City and the lower Mississippi Delta, is virtually uninhabited and uninhabitable. 

The users of the coast and coastal waters are also not physically, culturally, or economically 

homogenous. Since recreational users of coastal waters tend to be relatively affluent, the impacts of an 

oil spill are unlikely to affect minority or low-income people disproportionately. Oil spills can have 

indirect effects, such as through serious, short-term impacts on tourism. However, these too are unlikely 

to affect minority or low-income people disproportionately. Chapter 4.4.14.4 of the Multisale EIS and 

Chapter 4.1.14.3 of this SEIS discuss in further detail impacts to recreational resources from oil spills. 

Approximately 61-136 coastal spills are estimated to occur within Gulf coastal waters from activities 

supporting CPA and WPA proposed actions, over their 40-year life, combined; most (about 90%) of these 

spills would be ≤1 bbl. The most likely locations of the estimated 6-15 coastal spills >1 bbl would be 

proximate to the major oil pipeline shore facilities. Except for two accidental 3,000-bbl spills estimated 

to occur in Louisiana and Texas coastal waters under the high resource-estimate scenario over the 40-year 

life of a proposed action, MMS estimates that coastal spills ≥1,000 bbl resulting from a proposed action 

have a low probability of occurrence. 

Figures 3-6 and 3-7 show the Gulf of Mexico coastal counties and parishes having a risk >0.5 

percent of being contacted within 10 days by an offshore spill ≥1,000 bbl occurring as a result of a 

proposed action. Most counties and parishes have a <0.5 percent probability of a spill ≥1,000 bbl 

occurring and contacting (combined probability) their shorelines within 10 days; six counties in Texas 

and eight parishes in Louisiana have a 1-16 percent chance of an OCS offshore spill ≥1,000 bbl occurring 

and reaching their shoreline within 10 days as the result of a proposed action over its 40-year life. In 

Louisiana, Plaquemines Parish has the greatest risk (10-16%) of a spill occurring and contacting its 

shoreline within 10 days as a result of a CPA proposed action. In Texas, Matagorda County has the 

greatest risk (3-5%) of being contacted within 10 days by a spill occurring offshore as a result of a WPA 

proposed action. 

As explained in Chapter 3.2.1, the incremental increase in oil production from the addition of the 

181 South Area is not expected to result in an overall increase in the numbers of oil spills ≥1,000 bbl 

likely to occur as a result of a CPA proposed action. Activity that would result from the addition of the 

181 South Area would not cause an increase in the risk of a large spill occurring and contacting coastal 

counties and parishes, except for Plaquemines Parish for which the addition of the 181 South Area would 

result in a 1 percent increase in risk. 

Summary and Conclusion 

Because of the heterogeneous population distribution along the Gulf of Mexico region, accidental 

spill events associated with CPA and WPA proposed actions are not expected to have disproportionate 

adverse environmental or health effects on minority or low-income populations. 

4.1.16.4.4. Cumulative Impacts 

A detailed description of cumulative impacts upon environmental justice can be found in Chapter 

4.5.15.4 of the Multisale EIS. The following is a summary of the information presented in the Multisale 

EIS unless otherwise noted.

This chapter analyzes the cumulative effects to environmental justice of the OCS Program, the CPA 

and WPA proposed actions, and non-OCS factors. The analysis centers on increases in onshore activity 
Environmental and Socioeconomic Consequences 4-207 

and additions to infrastructure related to this activity. Onshore activity includes activity such as 

employment, migration, commuter traffic, and truck traffic. Infrastructure includes such types as 

fabrication yards, supply ports, and onshore disposal sites for offshore waste. 

Chapter 3.3.5 of the Multisale EIS describes the widespread and extensive physical infrastructure and 

associated labor force and the economic factors related to OCS activities. The widespread distribution of 

OCS-related infrastructure serves to limit the magnitude of effects that the OCS Program may have on 

any particular community. Additional OCS activities will serve mostly to maintain current activity levels. 

Generally, effects will be widely yet thinly distributed across the Gulf Coast and will consist of slightly 

increased employment and even more slightly increased population. For most of the Gulf Coast, 

cumulative activities will generate only minor changes to employment. Some places could experience 

elevated employment, population, infrastructure, and/or traffic effects because of local concentrations of 

fabrication and supply operations. Lafourche Parish, Louisiana, is one community where concentrations 

of industry activity and related employment are likely to continue to strain the local infrastructure. 

No predictions are made regarding employment of minority or low-income people or the location of 

that employment. Figures 3-21 through 3-26 of the Multisale EIS provide distributions of counties and 

parishes of high concentrations of minority groups and low-income households. Because the distribution 

of low-income and minority populations does not geographically coincide with OCS-related industry 

infrastructure by counties and parishes, the effects of the OCS Program are not likely to be 

disproportionate for minority and low-income populations. 

Various economic and socioeconomic variables can affect how to assess environmental impacts 

(Singelmann, personal communication, 2006). In general, the oil and gas industry has had a slight, 

indirect, but positive effect on the employment of minority and low-income populations by providing 

local economic opportunities. It may also be, at times, a key sector of sustainability from economic 

fluctuations (although problematic at other time). Shifting sectors can sustain strong business services 

and professional sectors (Tolbert, 1995 and 2006; Tobin, 2001). 

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, rather 

than expand, current levels of activity, no single sale will generate significant new infrastructure demand. 

Over the next 40 years, it is likely to result in new pipeline landfalls, pipeline shore facilities, and gas 

processing plants but, because of adequate existing capacity, it is unlikely to result in new waste-disposal 

sites (Louis Berger Group, Inc., 2004). 

At present, there are 126 OCS-related pipeline landfalls and 50 OCS-related pipeline shore facilities 

in the Gulf of Mexico region (Table 3-38 of the Multisale EIS). Pipeline shore facilities are small 

structures, such as oil metering stations, associated with pipeline landfalls. For the 40-year analysis 

period, MMS predicts between 32 and 47 new pipeline landfalls and between 4 and 6 pipeline shore 

facilities (Table 4-9 of the Multisale EIS). 

The MMS projects 14 new gas-processing plants in support of the OCS Program over the next 40 

years, although their location among the states is not predicted. As described in Chapter 3.3.5.8 of the 

Multisale EIS, the Gulf’s extensive OCS-related infrastructure is widely distributed. This distribution is 

based on economic and infrastructure considerations unrelated to the geographic distribution of counties 

and parishes with higher proportions of minority or low-income populations. Therefore, it is not likely 

that new coastal infrastructure resulting from the OCS Program will disproportionately affect low-income 

or minority groups. 

Chapter 3.3.5.8 of the Multisale EIS describes Louisiana’s extensive oil- and gas-related 

infrastructure support system. As a result of the concentration of OCS-support infrastructure, Louisiana 

has experienced more employment effects than the other Gulf Coast States. While the planned addition 

of a C-Port in Galveston, Texas, would increase Texas’s share of future effects, Louisiana is likely to 

continue to experience more effects than do other Gulf Coast States. 

Because of Louisiana’s extensive oil-related infrastructure support system (Chapter 3.3.5.8 of the 

Multisale EIS), Louisiana is likely to experience more employment effects from cumulative activities than 

do other coastal states. Lafourche Parish, Louisiana, is likely to experience the greatest concentration and 

is the only parish where the additional OCS-related activities and employment are sufficiently 

concentrated to increase the existing stress to its infrastructure. Even so, these cumulative effects are 

unlikely to be significant in the long term or to disproportionately affect minority and low-income 

populations for two reasons. First, the parish is not predominately minority or low income (Figures 3-22 
4-208 Central and Western Gulf of Mexico Multisale Supplemental EIS

and 3-25 of the Multisale EIS). Second, while the majority of OCS-related infrastructure is located in 

south Lafourche where the Houma Indian population (a tribe with State of Louisiana recognition) is 

concentrated, the Houma Indians are not residentially segregated. Since the cumulative would not 

significantly alter this preexisting situation where substantial onshore infrastructure and employment 

already exist, minority and low-income populations, including the Houma Indians, would not sustain 

disproportionate adverse effects. 

Two local infrastructure issues described in Chapter 3.3.5.2 of the Multisale EIS raise environmental 

justice concerns: traffic on LA Hwy 1 and the Port Fourchon expansion. The most serious concern raised 

during scoping for the Multisale EIS is the high level of traffic on LA Hwy 1. Increased truck traffic 

destined for Port Fourchon physically stresses the highway, inconveniences and sometimes disrupts local 

communities, and may pose health risks from increased accident rates and possible interference to 

hurricane evacuations (Keithly, 2001; Hughes et al., 2001). However, as described in Chapter 3.3.5.2 of 

the Multisale EIS, the area’s “string settlement pattern” means that all income groups alike live on a 

narrow band of high ground along LA Hwy 1 and will be equally affected by any increased traffic. 

Port Fourchon is relatively new and is mostly surrounded by uninhabited land. Existing residential 

areas close to the port are new and are not low income. While the minority and low-income populations 

of Lafourche Parish will share with the rest of the population the negative impacts of cumulative 

activities, most effects are expected to be economic and positive. While the link between a healthy oil 

industry and indirect economic benefits to all sectors of society may be weak in some communities, in 

Lafourche Parish it is strong. The Parish is part of an area of relatively low unemployment due to the 

concentration of petroleum industry activity (Hughes et al., 2001). 

Chapter 4.5.15.2 discusses the potential strains on community infrastructure and services in the 

following parishes and counties: St. Tammany, St. John the Baptist, St. James, Ascension, St. Charles, 

East Baton Rouge, and Tangipahoa Parishes in Louisiana; and Stone County in Mississippi. Potential 

strains are found to be low; also, the distribution of low-income and minority populations does not 

parallel the distribution of OCS-related industry activity and infrastructure. Therefore, the infrastructure 

and service strains resulting from cumulative activities will not cause disproportionate and negative 

effects or minority and low-income groups. 

As discussed in the environmental justice analysis for oil spills (Chapter 4.4.14.4 of the Multisale 

EIS), existing coastal populations are not generally minority or low income. Several Louisiana parishes 

in the lower Mississippi River Delta area have a higher percentage of minorities than the State average 

(e.g., Iberville, St. James, St. John the Baptist, and Orleans Parishes; Figure 3-22 of the Multisale EIS), 

but these are not coastal, and the majority of Louisiana’s coastline is virtually uninhabited. Since none of 

the coastal Louisiana parishes with a high level of OCS-related infrastructure have a higher percentage of 

poverty than the State average (Figure 3-25 of the Multisale EIS), in the cumulative case, pipeline 

landfalls and their associated facilities will not disproportionately affect minority or low-income 

populations. 

The baseline conditions pertaining to environmental justice were reevaluated in light of the 2005 

hurricane activity in the Gulf of Mexico. This hurricane activity had severe impacts on many coastal 

communities and many of these impacts fell disproportionately on minority and low-income populations. 

However, these changes did not cause a major shift in the distribution of the onshore infrastructure nor 

did they increase the number or percentage of minority and low-income populations residing near this 

infrastructure. Therefore, the environmental justice conclusions of the Multisale EIS do not change. 

Many studies of social change in the Gulf of Mexico coastal region suggest that the offshore 

petroleum industry, and even the offshore and onshore petroleum industry, has not been a critical factor 

except in limited in small areas for limited periods of time. This was a key conclusion of an MMSfunded study of the historical role of the industry in the Gulf, a study that addressed social issues related 

to environmental justice (Wallace et al., 2001). The MMS’s 5-Year Programmatic EIS (USDOI, MMS, 

2007a) analyzed the contribution of the OCS Program in the Gulf of Mexico to the cumulative effects. It 

concludes that the cumulative environmental justice impacts from non-OCS activities have made, and will 

make, substantially larger contributions to the environmental justice effects than will the OCS Program. 
Environmental and Socioeconomic Consequences 4-209 

Summary and Conclusion 

Because of the presence of an existing extensive and widespread infrastructure support system for 

OCS and associated labor force, the effects of the OCS Program are widely distributed and, except in 

Louisiana, likely to be minimal. In general, the OCS Program will generate employment and have a 

limited but positive effect on low-income and minority populations. In Louisiana, positive employment 

effects are expected to be greater. 

While Lafourche Parish will experience the most concentrated effects of cumulative impacts, these 

will not disproportionately affect low-income or minority populations, including the Houma Indians. 

This is because the parish is not predominately low income or minority and because the effects of road 

traffic and port expansion will not occur in areas of low-income or minority concentration. 

The OCS Program is not expected to have disproportionately high or adverse environmental or health 

effects on minority or low-income people. In the Gulf of Mexico coastal area, the contribution of the 

cumulative effects of all activities and trends affecting environmental justice issues over the next 40 years 

is likely to be negligible to minor. Cumulative effects will be concentrated in coastal areas and in 

Louisiana. The contribution of the OCS Program to cumulative impacts is expected to be minor (USDOI, 

MMS, 2007a). Therefore, the incremental contribution of the CPA and WPA proposed actions would 

also be minor. 

4.2. ALTERNATIVES TO THE PROPOSED ACTIONS

4.2.1. Alternatives for Proposed Central Planning Area Sales 208, 213, 216, and 

222 

The following three alternatives were included for analysis in the Multisale EIS. As explained in 

Chapter 2.1.3.2, the Use of a Nomination and Tract Selection Leasing System Alternative was not 

included for analysis in this SEIS due to an ongoing MMS study on alternative approaches to leasing. No 

new alternatives were proposed due to the addition of the 181 South Area to the proposed CPA lease 

sales. 

4.2.1.1. Alternative B—The Proposed Actions Excluding the Unleased Blocks 

Near Biologically Sensitive Topographic Features 

Description of the Alternative 

Alternative B differs from Alternative A (proposed action) by not offering blocks that are possibly 

affected by the proposed Topographic Features Stipulation (Chapter 2.2.1.3.1). All of the assumptions 

(including the 6 other potential mitigating measures) and estimates are the same as for a proposed action 

(Alternative A). A description of Alternative A is presented in Chapter 2.2.1.1. 

No topographic features are located in the 181 South Area; therefore, no blocks located in the 181 

South Area would be excluded under Alternative B. 

Effects of the Alternatives 

The following analyses are based on the scenario for a proposed action in the CPA (Alternative A). 

The scenario provides assumptions and estimates on the amounts, locations, and timing for OCS 

exploration, development, and production operations and facilities, both offshore and onshore. These are 

estimates only and not predictions of what will happen as a result of holding a proposed 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 those under a typical 

proposed action in the CPA (Chapter 4.1) for the following resources: 
4-210 Central and Western Gulf of Mexico Multisale Supplemental EIS

—Air Quality 

—Water Quality 

—Sensitive Coastal Environments 

—Live Bottoms (Pinnacle Trend) 

—Continental Slope and Deepwater 

Benthic Communities 

—Marine Mammals 

—Sea Turtles 

—Alabama, Choctawhatchee, 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 

The impacts to some Gulf of Mexico resources under Alternative B would be different from the 

impacts expected under a proposed action. These impacts are described below. 

Impacts on Sensitive Offshore Resources 

Topographic Features 

The sources and severity of impacts associated with this alternative are those sale-related activities 

discussed for a proposed action. The potential impact-producing factors to the topographic features of the 

Central Gulf 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 4.1.4.1.2.2. 

Impacts of Routine Activities and Accidental Events 

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 will be eliminated by the adoption of 

this alternative. Effluent discharge and blowouts will 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 will 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 4.1.4.1.2.3. 

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 will 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 Central Gulf, 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, especially the Flower Garden Banks, in more detail. The currents that move around the banks 

will 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 (in the case of the Flower Garden Banks National Marine Sanctuary) 

(CSA, 1992b and 1994). It is anticipated that recovery from a mostly sublethal exposure would occur 

within a period of 2 years. In the unlikely event that oil from a subsurface spill contacted a coral-covered 

area (in the case of the Flower Garden Banks), 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, diseases) and may hamper their ability to 

reproduce. A complete recovery of such an affected area could take in excess of 10 years. 
Environmental and Socioeconomic Consequences 4-211 

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 a 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 

Feature 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 (in the case of the Flower Garden Banks National Marine Sanctuary); 

recovery from such an event is anticipated to occur within a period of 2 years. 

4.2.1.2. Alternative C—The Proposed Actions Excluding Unleased Blocks within 

15 Miles of the Baldwin County, Alabama, Coast 

Description of the Alternative 

Alternative C differs from Alternative A (a 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 those under Alternative A (Chapters 2.2.1.3 and 3.1.1). 

A description of Alternative A is presented in Chapter 2.2.1.1. 

The 181 South Area is located more than 90 mi (145 km) south of the Baldwin County, Alabama, 

coast; therefore, no blocks located in the 181 South Area would be excluded under Alternative C. 

Effects of the Alternatives 

The following analyses are based on the scenario for a proposed action in the CPA (Alternative A). A 

detailed discussion of the scenario and related impact-producing factors is present in Chapter 3.1. 

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 a typical proposed action in the 

CPA (Chapter 4.1) for the following resources: 

—Air Quality 

—Sensitive Coastal Environments 

—Live Bottoms (Pinnacle Trend) 

—Topographic Features 

—Continental Slope and Deepwater Benthic 

Communities 

—Marine Mammals 

—Sea Turtles 

—Alabama, Choctawhatchee, 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 

Impacts to some Gulf of Mexico resources would be different from the impacts of a proposed action. 

These impacts are described below. 
4-212 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 (Chapter 3.1). Alternative C 

would eliminate impacts associated with platform emplacement in the areas within 15 mi off the coast of 

Baldwin County, Alabama. 

The oil-spill events related to a 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 short-duration 

(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. 

Conclusion 

Bottom disturbances from platform emplacements and removals, drilling activities, and blowouts 

would not occur within the excluded area under Alternative C. 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, if Alternative C is adopted. Additionally, the risk of oil-spill impacts would be 

slightly reduced as exploration and development operations would not occur in the excluded area. 

Impacts on Archaeological Resources 

As a result of a typical proposed action in the CPA, 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 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 of the Baldwin County shoreline. 

Conclusion 

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. 

Impacts on Recreational Resources 

The major impact-producing factors that could potentially affect recreational beaches include the 

presence of offshore structures, pipelaying activities, support helicopter and vessel traffic, trash and 

debris, and oil spills. Exploratory rig activity and platforms associated with OCS development activity 

could be viewed from coastal communities along the Gulf of Mexico when they are closer than 

approximately 10 mi (16 km) from shore; beyond that, structures appear very small and barely 

discernable to the naked eye, eventually disappearing from view. Alternative C would exclude those 

blocks within 15 mi (24 km) of the shoreline from leasing. No OCS structures would be constructed 

within the excluded area. Any visual impact due to OCS structures in the area off Baldwin County, 

Alabama, would be eliminated. Pipelaying activities, support helicopter and vessel traffic, trash and 

debris, and oil spills from the remaining areas offered from lease would continue to present potential 

impacts to recreational beaches. 
Environmental and Socioeconomic Consequences 4-213 

Conclusion 

Alternative C would exclude blocks within 15 mi (24 km) of the Baldwin County, Alabama, coast 

from leasing. No OCS structures would be constructed within the excluded area. Therefore, any visual 

impact due to OCS structures in the area off Baldwin County would be eliminated. 

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. 

4.2.1.3. 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 Draft 

Proposed Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012. By canceling a proposed 

lease sale including leases that would be offered in the 181 South Area, the opportunity is postponed for 

development of the estimated 0.807-1.336 BBO and 3.365-5.405 Tcf of gas, some of which may be 

foregone. Any potential environmental and socioeconomic impacts resulting from a proposed sale 

(Chapter 4.1, Alternative A—The Proposed Actions) would be postponed or not occur. 

Effects of the Alternative 

Under Alternative D, USDOI cancels a planned 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 (proposed action) also would be delayed 

or not occur. 

The MMS recently published a report that examined previous exploration and development activity 

scenarios (USDOI, MMS, 2007g). The MMS compared forecasted activity with the actual activity from 

14 WPA and 14 CPA lease sales. 

The report shows that many lease sales contribute to the present level of OCS activity, and any single 

lease sale accounts for only a small percentage of the total OCS activities. In 2006, leases from 92 

different sales contributed to Gulf of Mexico production, while an average CPA lease sale contributed to 

2 percent of oil production and 2 percent of gas production in the CPA. In 2006, leases from 15 different 

sales contributed to the installation of production structures in the Gulf of Mexico, while an average CPA 

lease sale contributed to 6 percent of the installation of production structures in the CPA. In 2006, leases 

from 70 different sales contributed to wells drilled in the Gulf of Mexico, while an average CPA lease 

sale contributed to 4 percent of wells drilled in the CPA. 

Like past lease sales, a 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 a 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 a 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. 
4-214 Central and Western Gulf of Mexico Multisale Supplemental EIS

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, 2007g). Since 1983, 

MMS has scheduled and held annual areawide lease sales in the Gulf of Mexico, cancelling only one 

lease sale. In October 2006, MMS 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, MMS canceled CPA Lease Sale 

201, scheduled for March 2007. However, the acreage was offered 7 months later in CPA Lease Sale 205 

(October 2007). 

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 a 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 a 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 a 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 MMS publications: 

Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012 (USDOI, MMS, 2007a); Outer 

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

(USDOI, MMS, 2007b); and Energy Alternatives and the Environment (USDOI, MMS, in preparation 

(b)). 

Summary and Conclusion 

Canceling a lease sale would eliminate the effects described for Alternative A (Chapter 4.1). The 

incremental contribution of the proposed lease sales to cumulative effects would also be foregone, but 

effects from other activities, including other OCS lease sales, would remain. 

If a lease sale would be cancelled, 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. However, the cancellation of a 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. 
Environmental and Socioeconomic Consequences 4-215 

4.2.2. Alternatives for Proposed Western Planning Area Sales 210, 215, and 218 

The following two alternatives were included for analysis in the Multisale EIS. As explained in 

Chapter 2.1.3.2 of this SEIS, the Use of a Nomination and Tract Selection Leasing System Alternative 

was not included for analysis in this SEIS due to an ongoing MMS study on alternative approaches to 

leasing. 

4.2.2.1. Alternative B—The Proposed Actions Excluding the Unleased Blocks 

Near Biologically Sensitive Topographic Features 

Description of the Alternative 

Alternative B differs from Alternative A (proposed action) by not offering blocks that are possibly 

affected by the proposed Topographic Features Stipulation (Chapter 2.3.1.3.1). All of the assumptions 

(including the six other potential mitigating measures) and estimates are the same as for a proposed action 

(Alternative A). A description of Alternative A is presented in Chapter 2.3.1.1. 

Effects of the Alternatives 

The following analyses are based on the scenario for a proposed action in the WPA (Alternative A). 

The scenario provides assumptions and estimates on the amounts, locations, and timing for OCS 

exploration, development, and production operations and facilities, both offshore and onshore. These are 

estimates only and not predictions of what will happen as a result of holding a proposed 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 those under a typical 

proposed action in the WPA (Chapter 4.1) for the following resources: 

—Air Quality 

—Water Quality 

—Sensitive Coastal Environments 

—Live Bottoms (Pinnacle Trend) 

—Continental Slope and Deepwater Benthic 

Communities 

—Marine Mammals 

—Sea Turtles 

—Coastal and Marine Birds 

—Fish Resources and Essential Fish Habitat 

—Commercial Fishing 

—Recreational Fishing 

—Recreational Resources 

—Archaeological Resources 

—Human Resources and Land Use 

The impacts to some Gulf of Mexico resources under Alternative B would be different from the 

impacts expected under a proposed action. These impacts are described below. 

Impacts on Sensitive Offshore Resources 

Topographic Features 

The sources and severity of impacts associated with this alternative are those sale-related activities 

discussed for a proposed action. The potential impact-producing factors to the topographic features of the 

Western Gulf 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 4.1.4.1.2.2. 

Impacts of Routine Activities and Accidental Events 

All 21 topographic features of the WPA are located within water depths less than 200 m (656 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 will be 
4-216 Central and Western Gulf of Mexico Multisale Supplemental EIS

eliminated by the adoption of this alternative. Effluent discharge and blowouts will 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 will have been excluded from leasing under this alternative. Thus, the only impactproducing 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 4.1.4.1.2.3. 

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 will 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 Western Gulf, 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, especially the Flower Garden Banks, in more detail. The currents that move around 

the banks will 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 (in the case of the Flower Garden Banks 

National Marine Sanctuary) (CSA, 1992b and 1994). It is anticipated that recovery from a mostly 

sublethal exposure would occur within a period of 2 years. In the unlikely event that oil from a 

subsurface spill contacted a coral-covered area (in the case of the Flower Garden Banks), 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, 

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 a 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 

Feature 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 (in the case of the Flower Garden Banks National Marine Sanctuary); 

recovery from such an event is anticipated to occur within a period of 2 years. 

4.2.2.2. Alternative C—No Action 

Description of the Alternative 

Alternative C is equivalent to cancellation of a lease sale scheduled for a specific period in the Draft 

Proposed Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012. By canceling a proposed 

lease sale, the opportunity is postponed for development of the estimated 0.242-0.423 BBO and 1.644-

2.647 Tcf of gas, some of which may be foregone. Any potential environmental and socioeconomic 

impacts resulting from a proposed sale (Chapter 4.2.1, Alternative A—The Proposed Actions) would be 

postponed or not occur. 
Environmental and Socioeconomic Consequences 4-217 

Effects of the Alternative 

Under Alternative C, the USDOI cancels a planned WPA 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 (proposed action) also would be delayed 

or not occur. 

The MMS recently published a report that examined previous exploration and development activity 

scenarios (USDOI, MMS, 2007g). The MMS 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 WPA lease sale contributed to 

3 percent of oil production and 3 percent of gas production in the WPA. In 2006, leases from 15 different 

sales contributed to the installation of production structures in the Gulf of Mexico, while an average WPA 

lease sale contributed to 6 percent of the installation of production structures in the WPA. In 2006, leases 

from 70 different sales contributed to wells drilled in the Gulf of Mexico, while an average WPA lease 

sale contributed to 6 percent of wells drilled in the WPA. 

Like other lease sales, a proposed 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 a proposed lease sale would replace activity 

resulting from existing leases that have reached or are near the end of their economic life. 

Like past lease sales, a proposed WPA 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 a 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 a 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 WPA 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, 2007g). Since 1983, 

MMS has scheduled and held annual areawide lease sales in the Gulf of Mexico, cancelling only one 

lease sale. In October 2006, MMS 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, MMS canceled CPA Lease Sale 

201, scheduled for March 2007. However, the acreage was offered 7 months later in CPA Lease Sale 205 

(October 2007). 

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 a 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 a 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 a lease sale would delay the receipt of interest on billions of dollars of bonus bids, rental 

income, and royalty income by the Federal treasury. 
4-218 Central and Western Gulf of Mexico Multisale Supplemental EIS

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 MMS publications: 

Outer Continental Shelf Oil and Gas Leasing Program: 2007-2012 (USDOI, MMS, 2007a); Outer 

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

(USDOI, MMS, 2007b); and Energy Alternatives and the Environment (USDOI, MMS, in 

preparation(b)). 

Summary and Conclusion 

Canceling a lease sale would eliminate the effects described for Alternative A (Chapter 4.1). The 

incremental contribution of the proposed lease sales to cumulative effects would also be foregone, but 

effects from other activities, including other OCS lease sales, would remain. 

If a lease sale would be cancelled, 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 WPA 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. However, the cancellation of a 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. 

4.3. UNAVOIDABLE ADVERSE IMPACTS OF THE PROPOSED ACTIONS

Unavoidable adverse impacts associated with a proposed action are expected to be primarily shortterm and localized in nature and are summarized below. 

Sensitive Coastal Habitats: If an oil spill were to contact a barrier beach, the removal of beach sand 

during cleanup activities could result in adverse impacts if the sand is not replaced. If an oil spill contacts 

coastal wetlands, adverse impacts could be high in localized areas. In some areas, wetland vegetation 

would experience suppressed productivity for several years. Much of the wetland vegetation would 

recover over time, but some wetland areas would 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 

maintenance dredging, wake erosion, and other secondary impacts related to channels would occur as a 

result of the proposed actions. 

Sensitive Offshore Habitats: If an oil spill occurred and contacted sensitive offshore habitats, there 

could be some adverse impacts on organisms contacted by oil. 

Water Quality: Routine offshore operations would cause some unavoidable effects to varying degrees 

on the quality of the surrounding water. Drilling, construction, and pipelaying activities would cause an 

increase in the turbidity of the affected waters for the duration of the activity periods. A turbidity plume 

would also be created by the discharge of drill cuttings and drilling fluids. This, however, would only 

affect water in the immediate vicinity of the rigs and platforms. The discharge of treated sewage from the 

rigs and platforms would increase the levels of suspended solids, nutrients, chlorine, and BOD 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. 

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 impacted bodies of water 
Environmental and Socioeconomic Consequences 4-219 

through inputs of chronic 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 to air quality could occur near catastrophic events (e.g., 

oil spills and blowouts) due to evaporation and combustion. Mitigation of long-term effects would be 

accomplished through existing regulations and development of new control emission technology. 

However, short-term effects from nonroutine catastrophic events (accidents) are uncontrollable. 

Endangered and Threatened Species: Unavoidable adverse impacts to endangered and threatened 

marine mammals, birds, sea turtles, mice, and the Gulf sturgeon due to activities associated with a 

proposed action (e.g., seismic surveys, water quality and habitat degradation, helicopter and vessel traffic, 

oil spills and spill response, and discarded trash and debris) would be primarily sublethal. Lethal impacts 

to endangered species are expected to be rare. 

Nonendangered and Nonthreatened Marine Mammals: Unavoidable adverse impacts to 

nonendangered and nonthreatened marine mammals due to activities associated with a proposed action 

(e.g., seismic surveys, water quality degradation, helicopter and vessel traffic, oil spills and spill response, 

and discarded trash and debris) would be primarily sublethal. Lethal impacts to nonendangered and 

nonthreatened marine mammals are expected to be rare. 

Coastal and Marine Birds: Some injury or mortality to coastal birds could result in localized areas 

from OCS-related oil spills, helicopter and OCS service-vessel traffic, and discarded trash and debris. 

Marine birds could be affected by noise, disturbances, and trash and debris associated with offshore 

activities. If an oil spill occurs and contacts marine or coastal bird habitats, some birds could experience 

sublethal impacts and birds feeding or resting in the water could be coated with oil and die. Oil spills and 

oil-spill cleanup activities could also affect local bird prey species. 

Fish Resources and Commercial Fisheries: Losses to fishing resources and fishing gear could occur 

from production platform placement, oil spills, and produced-water discharges. Localized populations of 

fish species are expected to experience sublethal effects. This could result in a temporary decrease in a 

local population on a local scale. It is unlikely that fishermen would harvest fish in the area of an oil spill, 

as spilled oil could coat or contaminate commercial fish species rendering them unmarketable. Other 

unavoidable adverse impacts include loss of fishing space caused by the installation of pipelines, rigs, 

platforms, or by other OCS-related structures. 

Recreational Beaches: Even though existing regulations prohibit littering of the marine environment 

with trash, offshore oil and gas operations may result in the accidental loss of some floatable debris in the 

ocean environment; this debris may eventually come ashore on major recreational beaches. Accidental 

events can lead to oil spills, which are difficult to contain in the ocean; therefore, it may be unavoidable 

that some recreational beaches become temporarily soiled by weathered crude oil. 

Archaeological Resources: As a result of the proposed actions, unique or significant archaeological 

information may be lost. 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. In some cases (e.g., in areas of high sedimentation rates), survey 

techniques may not be effective at identifying a potential resource. 

4.4. IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES

Irreversible or irretrievable commitments of resources refer 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 due to impacts from dredging, construction activities, or oil spills. 

Dredging activities can result in direct and indirect loss of wetlands, and oil spills can damage or destroy 

wetland vegetation, which leads to increased erosion and conversion of wetlands to open water. 

Construction and emplacement of onshore pipelines in coastal wetlands could result in the loss of coastal 

wetlands because of mechanical destruction and because of landloss facilitated by erosion of the marsh 

soils. 
4-220 Central and Western Gulf of Mexico Multisale Supplemental EIS

Sensitive Offshore Resources: 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. 

Fish Resources and Commercial Fisheries: Structure removal by explosives causes mortality to fish 

resources, including commercial and recreational species. Fish kills, including such valuable species as 

red snapper, are known to occur when explosives are used to remove structures in the Gulf of Mexico. If 

structure removal by explosives is continued, it will adversely impact the commercial fishing industry 

proximate to the removal site. However, in view of the positive impact of offshore platforms to fish 

resources and commercial fishing as a result of the platforms serving as artificial reefs and fish attracting 

devices, 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: Beached litter, debris, oil slicks, and tarballs may result in decreased 

enjoyment or lost opportunities for enjoyment of coastal recreational resources. 

Archaeological Resources: Although the impact to archaeological resources as a result of a proposed 

action is expected to be low, any interaction between an impact-producing factor (drilling of wells, 

emplacement of platforms, subsea completions, and pipeline installation) and a significant historic 

shipwreck or prehistoric site could destroy information contained in the site components and in their 

spatial distribution. This would be an irretrievable loss of potentially unique archaeological data. 

Oil and Gas Development: Leasing and subsequent development and extraction of hydrocarbons as a 

result of the proposed actions could represent an irreversible and irretrievable commitment of 

nonrenewable oil and gas resources once they are consumed. The estimated amount of resources to be 

recovered as a result of the proposed actions 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 safety and environmental protection. Nonetheless, some loss of human and 

animal life is inevitable from unpredictable and unexpected acts of man and nature (unavoidable 

accidents, human error and noncompliance, and adverse weather conditions). Some normal and required 

operations, such as structure removal, can result in the destruction of marine life. Although the possibility 

exists that individual marine mammals, marine turtles, birds, and fish can be injured or killed, there is 

unlikely to be a lasting effect on baseline populations. 

4.5. RELATIONSHIP BETWEEN THE SHORT-TERM USE OF MAN’S ENVIRONMENT 

AND THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY

In this section, the short-term effects and uses of various components of the environment in the 

vicinity of proposed actions are related to long-term effects and the maintenance and enhancement of 

long-term productivity. 

Short-term refers to the total duration of oil and gas exploration and production activities, whereas 

long-term refers to an indefinite period beyond the termination of oil and gas production. The specific 

impacts of a proposed action vary in kind, intensity, and duration according to the activities occurring at 

any given time. 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 a 

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. Platform removal is also a short-term 

activity with localized impacts; the impacts of site clearance may be longer lasting. Over the long-term, 

several decades to several hundreds of years, natural environmental balances are expected to be restored. 

Many of the effects discussed in Chapter 4.1 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 principle short-term use of the leased areas in the Gulf of Mexico would be for the production of 

0.242-0.423 BBO and 1.644-2.647 Tcf of gas from a typical WPA proposed action and 0.807-1.336 BBO 

and 3.365-5.405 Tcf of gas from a typical CPA proposed action. The short-term recovery of 
Environmental and Socioeconomic Consequences 4-221 

hydrocarbons may have long-term impacts on biologically sensitive offshore areas or archaeological 

resources. 

The OCS activities could temporarily interfere with recreation and tourism in the region, in the event 

of an oil spill contacting popular tourist beaches. 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 4.1.16, Impacts on Human Resources and Land Use). A return to equilibrium 

could be quickly expected as population changes and industrial development are absorbed in expanded 

communities. After the completion of oil and gas production, the marine environment is generally 

expected to remain at or return to its normal long-term productivity levels. To date, there has been no 

discernible decrease in long-term marine productivity in OCS areas where oil and gas have been produced 

for many years. 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 actions could increase these incidental benefits of offshore development. Offshore fishing and 

diving has gradually increased in the past three decades; platforms have been 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. To maintain the long-term productivity of site-specific, artificial reefs 

attractive to fishermen and divers, removed platforms may need to eventually be replaced. 

Archaeological and historic finds discovered during development would enhance long-term 

knowledge. Overall, finds may help to locate other sites; but destruction of artifacts would represent 

long-term losses. 

Extraction and consumption of offshore oil and natural gas would be a long-term depletion of 

nonrenewable resources. Economic, political, and social benefits would accrue from the availability of 

these natural resources. Most benefits would be short term and would delay the increase in the Nation's 

dependency on oil imports. The production of offshore oil and natural gas from the proposed action 

would provide short-term energy and perhaps additional time for the development of long-term 

alternative energy sources or substitutes for these nonrenewable resources. 
CHAPTER 5 

CONSULTATION AND COORDINATION
Consultation and Coordination 5-3 

5. CONSULTATION AND COORDINATION 

5.1. MULTISALE EIS 

This SEIS supplements 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). The Multisale 

EIS addressed 11 proposed CPA and WPA lease sales, as scheduled in the proposed Outer Continental 

Shelf Oil and Gas Leasing Program: 2007-2012. Chapter 5 of the Multisale EIS describes the 

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

that occurred during the development of the Multisale EIS. 

5.2. DEVELOPMENT OF THE PROPOSED ACTIONS

As mandated in the Gulf of Mexico Energy Security Act of 2006 (P.L. 109-432, December 20, 2006), 

MMS shall offer for oil and gas leasing approximately 4.3 million ac located in the southeastern part of 

the CPA (181 South Area), which would be included in proposed CPA Sales 208 (2009), 213 (2010), 216 

(2011), and 222 (2012). This SEIS analyzes the potential environmental effects of oil and natural gas 

leasing, exploration, development, and production in the 181 South Area, and any new information 

available for the remainder of the proposed sales since the publication of the Multisale EIS. 

5.3. NOTICE OF INTENT TO PREPARE AN SEIS AND CALL FOR INFORMATION AND 

NOMINATIONS

On September 10, 2007, the Call for Information and Nominations (Call) and Notice of Intent to 

Prepare an EIS (NOI) were published in the Federal Register. The general area of the Call only covers 

the 181 South Area. The NOI sought input on the scope of the SEIS, which covers the proposed CPA 

lease sales and WPA Sales 210 (2009), 215 (2010), and 218 (2011). Additional public notices were 

distributed via local newspapers, the U.S. Postal Service, and the Internet. A 30-day comment period was 

provided for the Call; it closed on October 10, 2007. A 45-day comment period was provided for the 

NOI; it closed on October 25, 2007. Federal, State, and local governments, along with other interested 

parties, were invited to send written comments to the Gulf of Mexico Region on the scope of the EIS. 

The MMS received several comment letters in response to the Call and/or the NOI, which are 

summarized below in Chapter 5.4. 

5.4. DEVELOPMENT OF THE DRAFT SEIS 

Scoping for this Draft SEIS was conducted in accordance with CEQ regulations implementing NEPA. 

Scoping provides those with an interest in the OCS Program an opportunity to provide comments on the 

proposed actions. In addition, scoping provides MMS an opportunity to update the Gulf of Mexico 

Region’s environmental and socioeconomic information base. The scoping process officially commenced 

on September 10, 2007, with the publication of the NOI in the Federal Register. Formal scoping 

meetings were held in Texas, Louisiana, and Alabama. The dates, times, locations, and public attendance 

of the scoping meetings for the SEIS were as follows: 

Tuesday, October 9, 2007 

7:00 p.m. 

Larose Civic Center, Larose Regional Park 

Larose, Louisiana 

13 registered attendees 

11 speakers 

Wednesday, October 10, 2007 

1:00 p.m. 

The Woods Auditorium in the Energy, Coast & 

Environment Building at the LSU Campus 

Baton Rouge, Louisiana 

3 registered attendees 

2 speakers 
5-4 Central and Western Gulf of Mexico Multisale Supplemental EIS

Thursday, October 11, 2007 

7:00 p.m. 

Riverview Plaza Hotel, 64 South Water Street 

Mobile, Alabama 

No registered attendees or speakers 

Thursday, October 11, 2007 

1:00 p.m. 

Houston Airport Marriott 

18700 J.F. Kennedy Blvd 

Houston, Texas 

2 registered attendees 

1 speaker 

Comments (both verbal and written) were received from the Call/NOI and four scoping meetings 

from State and local governmental agencies; interest groups; industry; and the general public on the scope 

of the SEIS, significant issues that should be addressed, alternatives that should be considered, and 

mitigation measures. All scoping comments received, which were appropriate for a lease sale NEPA 

document, were considered in the preparation of this Draft SEIS. While most of the commenters were 

supportive of the proposed lease sales and recognized the economic benefits of the OCS Program, they 

requested mitigation of impacts of the OCS Program or the proposed lease sales, in particular funding of 

improvements to LA Hwy 1 and coastal restoration. Two letters were received opposing the proposed 

lease sales. Several comments were received on impact-producing factors and environmental and 

socioeconomic resources and issues, which were addressed in MMS’s previous lease sale NEPA 

documents and in this Draft SEIS. Issues unique to the 181 South Area included transportation of oil 

production (i.e., pipelines and tankering), likely modifications of onshore facilities and onshore and 

nearshore pipeline networks, increased wake damage from larger vessels, increased susceptibility to 

hurricane impacts, longer hurricane evacuation times, and the possibility of different geological 

characteristics. 

5.5. DISTRIBUTION OF THE DRAFT SEIS FOR REVIEW AND COMMENT

The MMS sent copies of this Draft SEIS to the following public and private agencies and groups. 

Local libraries along the Gulf Coast were also provided copies of this document. The list of libraries and 

their locations is available on the MMS Internet website at http://www.gomr.mms.gov. To initiate the 

public review and comment period on this Draft EIS, MMS published a Notice of Availability (NOA) in 

the Federal Register. Additionally, public notices were mailed with this Draft SEIS and placed on the 

MMS Internet website. All comments received on this Draft SEIS will be considered in the preparation 

of the Final SEIS. 

Federal Agencies 

Congress 

Congressional Budget Office 

House Resources Subcommittee on Energy 

and Mineral Resources 

Senate Committee on Energy and Natural 

Resources 

Department of Commerce 

National Marine Fisheries Service 

National Oceanic and Atmospheric 

Administration 

Department of Defense 

Department of the Air Force 

Department of the Army 

Corps of Engineers 

Department of the Navy 

Department of Energy 

Strategic Petroleum Reserve PMD 

Department of the Interior 

Fish and Wildlife Service 

Geological Survey 

Minerals Management Service 

National Park Service 

Office of Environmental Policy and 

Compliance 

Office of the Solicitor 

Department of State 

Office of Environmental Protection 

Department of Transportation 

Coast Guard 

Office of Pipeline Safety 

Environmental Protection Agency 

 Region 4 

 Region 6 

Marine Mammal Commission 

State and Local Agencies 

Alabama 

Governor’s Office 

Alabama Highway Department 

Alabama Historical Commission and State 

Historic Preservation Officer 
Consultation and Coordination 5-5 

Alabama Public Service Commission 

Department of Environmental Management 

Department of Conservation and Natural 

Resources 

South Alabama Regional Planning 

Commission 

State Docks Department 

State Legislature Natural Resources 

Committee 

State Legislature Oil and Gas Committee 

Florida 

Governor’s Office 

Bureau of Archaeological Research 

Department of Community Affairs 

Department of Environmental Protection 

Department of State Archives, History and 

Records Management 

Escambia County 

Florida Coastal Zone Management Office 

State Legislature Natural Resources and 

Conservation Committee 

State Legislature Natural Resources 

Committee 

West Florida Regional Planning Council 

Louisiana 

Governor’s Office 

Calcasieu Regulatory Planning Commission 

Department of Culture, Recreation, and 

Tourism 

Department of Environmental Quality 

Department of Natural Resources 

Department of Transportation and 

Development 

Department of Wildlife and Fisheries 

Louisiana Geological Survey 

State Legislature Natural Resources 

Committee 

State House of Representatives Natural 

Resources Committee 

Mississippi 

Governor’s Office 

Department of Archives and History 

Department of Natural Resources 

Department of Wildlife Conservation 

State Legislature Oil, Gas, and Other Minerals 

Committee 

Texas 

Governor’s Office 

Attorney General of Texas 

General Land Office 

Southeast Texas Regional Planning 

Commission 

State Legislature Natural Resources 

Committee 

State Senate Natural Resources Committee 

Texas Historical Commission 

Texas Legislation Council 

Texas Parks and Wildlife Department 

Texas Water Development Board 

Libraries 

Alabama 

Auburn University Library, Montgomery 

Dauphin Island Sea Lab, Marine 

Environmental Science Consortium Library, 

Dauphin Island 

Gulf Shores Public Library, Gulf Shores 

Mobile Public Library, Mobile 

Montgomery Public Library, Montgomery 

Thomas B. Norton Public Library, Gulf 

Shores 

University of South Alabama, Mobile 

Florida 

Charlotte-Glades Regional Library System, 

Port Charlotte 

Collier County Public Library, Naples Florida 

A&M, Coleman Memorial Library, 

Tallahassee 

Northwest Regional Library System, Panama 

City 

Florida State University, Strozier Library, 

Tallahassee 

Fort Walton Beach Public Library, Fort 

Walton Beach 

Leon County Public Library, Tallahassee 

Marathon Public Library, Marathon 

Monroe County Public Library, Key West 

Selby Public Library, Sarasota 

St. Petersburg Public Library, St. Petersburg 

Tampa-Hillsborough Public Library, Tampa 

University of Florida, Holland Law Library, 

Gainesville 

University of Miami Library, Miami 

University of West Florida, Pensacola 

Louisiana 

Calcasieu Parish Library, Lake Charles 

Cameron Parish Library, Cameron 

Grand Isle Branch Library, Grand Isle 

Iberville Parish Library, Plaquemines 

Jefferson Parish Regional Branch Library, 

Metairie 
5-6 Central and Western Gulf of Mexico Multisale Supplemental EIS

Jefferson Parish West Bank Outreach Branch 

Library, Harvey 

Lafayette Public Library, Lafayette 

Lafitte Branch Library, Lafitte 

Lafourche Parish Library, Thibodaux 

Louisiana State University Library, Baton 

Rouge 

Louisiana Tech University Library, Ruston 

Loyola University, Government Documents 

Library, New Orleans 

LUMCON Library, Chauvin 

McNeese State University, Luther E. Frazar 

Memorial Library, Lake Charles 

New Orleans Public Library, New Orleans 

Nicholls State University, Nicholls State 

Library, Thibodaux 

Plaquemines Parish Library, Buras 

St. Bernard Parish Library, Chalmette 

St. Charles Parish Library, Luling 

St. John the Baptist Parish Library, LaPlace 

St. Mary Parish Library, Franklin 

St. Tammany Parish Library, Covington 

St. Tammany Parish Library, Slidell 

Terrebonne Parish Library, Houma 

Tulane University, Howard Tilton Memorial 

Library, New Orleans 

University of New Orleans Library, New 

Orleans 

University of Southwestern Louisiana, Dupre 

Library, Lafayette 

Vermilion Parish Library, Abbeville 

West Bank Regional Library, Harvey 

Mississippi 

Gulf Coast Research Laboratory, Gunter 

Library, Ocean Springs

Hancock County Library System, Bay St. 

Louis 

Harrison County Library, Gulfport 

Jackson State University, Eudora Welty 

Library, Jackson 

Oklahoma 

University of Tulsa, McFarlin Library, Tulsa 

Texas 

Abilene Christian University, Abilene 

Alma M. Carpenter Public Library, Sourlake 

Aransas Pass Public Library, Aransas Pass 

Austin Public Library, Austin 

Baylor University, Waco 

Bay City Public Library, Bay City 

Brazoria County Library, Freeport 

Calhoun County Library, Port Lavaca 

Chambers County Library System, Anahuac 

Corpus Christi Central Library, Corpus Christi 

Dallas Public Library, Dallas 

East Texas State University Library, 

 Commerce 

Houston Public Library, Houston 

Jackson County Library, Edna 

Lamar University, Mary and John Gray 

 Library, Lamar Station 

Liberty Municipal Library, Liberty 

Orange Public Library, Orange 

Port Arthur Public Library, Port Arthur 

Port Isabel Public Library, Port Isabel 

R. J. Kleberg Public Library, Kingsville 

Reber Memorial Library, Raymondville 

Refugio County Public Library, Refugio 

Rice University, Fondren Library, Houston 

Rockwall County Library, Rockwall 

Rosenberg Library, Galveston 

Sam Houston Regional Library & Research 

 Center, Liberty 

Stephen F. Austin State University, Steen 

 Library, Nacogdoches 

Texas A&M University Library, Corpus 

 Christi 

Texas A&M University, Evans Library, 

 College Station 

Texas Southmost College Library, 

 Brownsville 

Texas State Library, Austin 

Texas Tech University Library, Lubbock 

University of Houston Library, Houston 

University of Texas Library, Arlington 

University of Texas Library, Austin 

University of Texas Library, Brownsville 

University of Texas Library, El Paso 

University of Texas Library, San Antonio 

University of Texas at Dallas, McDermott 

 Library, Richardson 

University of Texas, LBJ School of Public 

 Affairs Library, Austin 

University of Texas, Tarlton Law Library, 

 Austin 

Victoria Public Library, Victoria 

Industry 

American Petroleum Institute 

Alabama Petroleum Council 

Amerada Hess Corporation 

Area Energy LLC 

Baker Atlas 

Bellwether Group 

B-J Services Co 

BP Amoco 

C.H. Fenstermaker & Associates 
Consultation and Coordination 5-7 

Chevron U.S.A. Inc. 

Clayton Williams Energy, Inc 

Coastal Conservation Association 

Coastal Environments, Inc. 

Continental Shelf Associates, Inc. 

Coscol Marine Corporation 

Devon Energy Corp. 

Dominion Exploration & Production, Inc. 

Ecological Associates, Inc. 

Ecology and Environment 

Energy Partners, Ltd. 

EOG Resources, Inc. 

Escambia County Marine Resources 

Exxon Mobil Production Company 

Florida Petroleum Council 

FNGA, FPGA and AGDF 

Forest Oil Corporation 

Freeport-McMoRan, Inc. 

Fugro Geo Services, Inc. 

General Dynamics - AIS 

Geo Marine Inc. 

Global Industries, Ltd. 

Gulf Environmental Associates 

Gulf of Mexico Newsletter 

Halliburton 

Horizon Marine, Inc. 

Industrial Vehicles International, Inc. 

International Association of Geophysical 

Contractors 

International Paper Company 

J. Connor Consultants 

JK Enterprises 

John Chance Land Surveys, Inc. 

Kelly Energy Consultants 

Kerr-McGee Corporation 

Midstream Fuel Service 

Mote Marine Laboratory 

Newfield Exploration Company 

NWF Daily News 

Offshore Energy Center 

Offshore Operators Committee 

Petrobras America, Inc. 

PPG Industries, Inc. 

Propane Market Strategy Newsletter 

Coffers Ocean Fishing Forecast Service 

Science Applications International 

Corporation 

Seneca Resources Corporation 

Shell Exploration & Production Company 

Stone Energy Corporation 

Strategic Management Services-USA 

T. Baker Smith, Inc. 

Texas Geophysical Company, Inc. 

The Houston Exploration Company 

Triton Engineering Services Co. 

W & T Offshore, Inc. 

Walker Landscaping 

Washington Post 

WEAR-TV 

Special Interest Groups 

1000 Friends of Florida 

American Cetacean Society 

American Littoral Society 

Apalachicola Riverkeeper 

Audubon Louisiana Nature Center 

Audubon of Florida 

Audubon Society 

Bay County Audubon Society 

Citizens Assoc. of Bonita Beach 

Clean Gulf Associates 

Coalition to Restore Coastal Louisiana 

Coastal Conservation Association 

Conservancy of SW Florida 

Defenders of Wildlife 

Earthjustice 

Florida Public Interest Research Group 

Florida Sea Grant College 

Gulf Coast Environmental Defense 

Gulf Restoration Network 

Hubbs-Sea World Research Institute 

Izaak Walton League of America, Inc 

Louisiana State University 

Mobile Bay National Estuary Program 

Natural Resources Defense Council 

Nature Conservancy 

Pacific Marine Technology 

Perdido Key Association 

Population Connection 

Sierra Club 

South Mobile Communities Association 

Southeastern Fisheries Association 

The Conservancy 

The Conservation Fund 

The Nature Conservancy 

Walton County Growth Management 

Ports/Docks 

Alabama 

Alabama State Port Authority 

Port of Mobile 

Florida 

Port Manatee 

Panama City Port Authority 

Port of Pensacola 

Tampa Port Authority 
5-8 Central and Western Gulf of Mexico Multisale Supplemental EIS

Louisiana 

Greater Baton Rouge Port Commission 

Greater Lafourche Port Commission 

Lake Charles Harbor and Terminal District 

Louisiana Offshore Oil Port, LLC 

Plaquemines Port, Harbor and Terminal 

District 

Port of Iberia District 

Port of New Orleans 

Port of Baton Rouge 

Port of Krotz Springs 

Port of Shreveport-Bossier 

Port of South Louisiana 

St. Bernard Port, Harbor and Terminal District 

Mississippi 

Port Bienville 

Port of Biloxi 

Port of Gulfport 

Port of Natchez 

Port of Pascagoula 

Port of Vicksburg 

Texas 

Brownsville Navigation District—Port of 

Brownsville 

Port Freeport, Texas—Brazos River Harbor 

Navigation District 

Port Aransas 

Port of Beaumont 

Port of Corpus Christi Authority 

Port Freeport 

Port of Galveston 

Port of Houston Authority 

Port of Isabel—San Benito Navigation District 

Port Mansfield/Willacy County Navigation 

District 

Port of Orange 

Port of Port Arthur Navigation District 

Port of Port Lavaca/Point Comfort 

Port of Sabine Pass 

Port of Texas City

5.6. PUBLIC HEARINGS

In accordance with 30 CFR 256.26, MMS will hold public hearings soliciting comments on this Draft 

SEIS. The hearings also provide the Secretary of the Interior with information from interested parties to 

help in the evaluation of potential effects of the proposed lease sales. Announcement of the dates, times, 

and locations of the public hearings will be included in the NOA for this Draft SEIS. Notices of the 

public hearings were included with copies of this Draft SEIS mailed to the parties indicated above, posted 

on the MMS Internet website (http://www.gomr.mms.gov), and published in local newspapers. 

5.7. COASTAL ZONE MANAGEMENT ACT

A consistency review will be performed and a CD will be prepared for each affected State prior to 

each proposed lease sale. To prepare the CD’s, MMS reviews each State’s CZMP and analyzes the 

potential impacts as outlined in this SEIS, new information, and applicable studies as they pertain to the 

enforceable policies of each CZMP. Based on the analyses, the MMS Director makes an assessment of 

consistency, which is then sent to each State with the PNOS. If a State disagrees with MMS’s CD, the 

State is required to do the following under the CZMA: (1) indicate how the MMS presale proposal is 

inconsistent with their CZMP and suggest alternative measures to bring the MMS proposal into 

consistency with their CZMP or (2) describe the need for additional information that would allow a 

determination of consistency. Unlike the consistency process for specific OCS plans and permits, there is 

no procedure for administrative appeal to the Secretary of Commerce for a Federal CD for presale 

activities. Either MMS or the State may request mediation. Mediation is voluntary, and the DOC would 

serve as the mediator. Whether there is mediation or not, the final CD is made by DOI and it is the final 

administrative action for the presale consistency process. Each Gulf State’s CZMP is described in 

Appendix B of the Multisale EIS (USDOI, MMS, 2007b). 

5.8. ENDANGERED SPECIES ACT

The Endangered Species Act of 1973 (ESA) (16 U.S.C. 1631 et seq.) of 1973, as amended (43 U.S.C. 

1331 et seq.), establishes a national policy designed to protect and conserve threatened and endangered 

species and the ecosystems upon which they depend. In accordance with Section 7 of the ESA, MMS 

consults with NMFS and FWS on possible and potential impacts from sale proposals on 

endangered/threatened species and designated critical habitat under their jurisdiction. The MMS has 
Consultation and Coordination 5-9 

consulted NMFS and FWS on the proposed lease sales and associated activities in the Gulf of Mexico in 

the 2007-2012 5-Year Program. 

The NMFS Biological Opinion was signed on June 29, 2007, and was received by MMS on July 3, 

2007. The Biological Opinion concludes that the proposed lease sales and associated activities in the 

Gulf of Mexico in the 2007-2012 OCS Leasing Program, including the lease sales addressed in this SEIS, 

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 NMFS issued an Incidental 

Take Statement on sea turtle species, which contains reasonable and prudent measures with implementing 

terms and conditions to help minimize take. 

The FWS and MMS have consulted informally per FWS guidance. A draft copy of the Biological 

Assessment, prepared by MMS, was submitted as requested by FWS (USDOI, MMS, 2007h). On 

June 28, 2007, MMS received oral confirmation from FWS that the consultation will remain informal; 

therefore, there will be no new mitigations or Terms and Conditions from FWS. The final Biological 

Assessment and a request for a Letter of Concurrence were submitted to FWS on August 3, 2007. The 

FWS submitted a Letter of Concurrence dated September 14, 2007 (USDOI, FWS, 2007a). The FWS 

concurred with the MMS determination that proposed actions of the 2007-2012 OCS Leasing Program 

were not likely to adversely affect the threatened/endangered species or designated critical habitat under 

FWS jurisdiction. Sea turtles are under FWS jurisdiction when on a nesting beach. 

The biological assessments prepared by MMS analyzed a typical year of OCS activity rather than a 

typical lease sale and did not exclude the 181 South Area. Therefore, concurrence letters will be 

requested annually from NMFS and FWS to determine whether or not the information and analyses in the 

biological assessments and the associated consultations under the ESA are still valid.

5.9. MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT ACT

Pursuant to Section 305(b) of the Magnuson-Stevens Fishery Conservation and Management Act, 

Federal agencies are required to consult with NMFS on any action that may result in adverse effects to 

essential fish habitat (EFH). The NMFS published the final rule implementing the EFH provisions of the 

Magnuson-Stevens Fisheries Conservation and Management Act (50 CFR 600) on January 17, 2002. 

Certain OCS activities authorized by MMS may result in adverse effects to EFH, and therefore, require 

EFH consultation. 

In March 2000, the MMS’s Gulf of Mexico Region consulted with NMFS’s Southeast Regional 

Office in preparing a NMFS regional finding for the Gulf of Mexico Region that allows MMS to 

incorporate the EFH assessments into NEPA documents. The MMS consulted on a programmatic level, 

by letters of July 1999 and August 1999, to address EFH issues for certain MMS OCS activities (plans of 

exploration and production, pipeline rights-of-way, and platform removals). 

An EFH consultation for the CPA and WPA lease sales included in the 2002-2007 OCS Leasing 

Program, using the Draft Multisale EIS as the NEPA document, was initiated in March 2002 by MMS 

with NMFS’s Southeast Regional Office. The NMFS responded in April 2002, endorsing the 

implementation of resource protection measures previously developed cooperatively by MMS and NMFS 

in 1999 to minimize and avoid EFH impacts related to exploration and development activities in the CPA 

and WPA. In addition to routine measures, additional conservation recommendations were made. In 

May 2002, MMS responded to NMFS acknowledging receipt and agreement to follow the additional 

conservation recommendations. The EFH conservation measures recommended by NMFS serve the 

purpose of protecting EFH. Continuing agreements, including avoidance distances from topographicfeature’s No Activity Zones and live-bottom pinnacle features, and circumstances that require projectspecific consultation, appear in NTL 2004-G05. 

Effective January 23, 2006, NMFS approved a revision to the EFH rules acknowledging amendments 

made by the Gulf of Mexico Fishery Management Council resulting in the identification of habitat areas 

of particular concern. One of the most important changes noted in the amendment is the elimination of 

the EFH description and identification from waters between 100 fathoms and the seaward limit of the 

EEZ. 

Further programmatic consultation was initiated and completed for the 2007-2012 lease sales 

addressed in the Multisale EIS, which did not include the 181 South Area. The NMFS concurred by letter 

dated December 12, 2006, that the information presented in the Draft Multisale EIS satisfies the EFH 
5-10 Central and Western Gulf of Mexico Supplemental Multisale EIS

consultation procedures outlined in 50 CFR 600.920 and as specified in our March 17, 2000, findings. 

Provided MMS proposed mitigations, our previous EFH conservation recommendations, and the standard 

lease stipulations and regulations are followed as proposed, NMFS agrees that impacts to EFH and 

associated fishery resources resulting from activities conducted under the 2007-2012 lease sales would be 

minimal. Due to the addition of the 181 South Area, a new request for Programmatic Consultation was 

initiated with the completion of this Draft SEIS. 
CHAPTER 6 

REFERENCES
References 6-3 

6. REFERENCES 

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CHAPTER 7 

PREPARERS
Preparers 7-3 

7. PREPARERS 

Dennis L. Chew, Chief, Environmental Assessment Section 

Gary D. Goeke, NEPA/CZM Unit Supervisor, Supervisory Environmental Protection Specialist 

Michelle V. Morin, Coordinator, Senior Environmental Scientist 

Casey Rowe, Coordinator, Biologist 

Mary C. Boatman, Headquarters’ Coordinator, Environmental Specialist 

Dave Ball, Marine Archaeologist 

Gregory S. Boland, Fisheries Biologist/Biological Oceanographer 

Darice K. Breeding, Environmental Protection Specialist 

Carole L. Current, Physical Oceanographer 

Richard Desselles, Petroleum Engineer 

Donald (Tre) W. Glenn III, Protected Species Biologist 

Mike Gravois, Geographer 

Larry M. Hartzog, Environmental Scientist 

Bonnie La Borde Johnson, Environmental Scientist 

Nancy M. Kornrumpf, Program Analyst 

Gregory Kozlowski, Environmental Scientist 

Jill Leale, Geographer 

Daniel (Herb) Leedy, Supervisor, Biological Sciences Unit 

Harry Luton, Social Scientist 

Margaret Metcalf, Physical Scientist 

Deborah H. Miller, Technical Publications Editor 

Tara Montgomery, Supervisor, Mapping and Automation Unit 

David P. Moran, Environmental Scientist 

Maureen M. Mulino, Marine Biologist 

Carol Roden, Protected Species Biologist 

John L. Rodi, Leasing Program Manager 

Catherine A. Rosa, Environmental Assessment Program Specialist 

James Sinclair, Marine Biologist 

Kristen L. Strellec, Economist 

Wilfred W. Times, Visual Information Specialist 
APPENDICES
APPENDIX A 

FIGURES
Figure 1-1. Gulf of Mexico Outer Continental Shelf Planning Areas, Proposed Lease Sale Areas, the 181 South Area, and Locations o
Figure 2-1. Location of Proposed Stipulations and Deferrals. 
Figure 2-2. Military Warning Areas in the Gulf of Mexico. 
Figure 2-3. Economic Impact Areas in the Gulf of Mexico. 
Figure 3-1. Offshore Subareas in the Gulf of Mexico. 
A-8 

Figure 3-2. Leasing Activity and Infrastructure Near the 181 South Area. 

Central and Western Gulf of Mexico Multisale Supplemental EIS
Figure 3-3. OCS-Related Service Bases in the Gulf of Mexico. 
A-10 Central and Western Gulf of Mexico Multisale Supplemental EIS

0

25

50

75

100

Percent Probability of Occurrence 

Low Resource Estimate

High Resource Estimate

000 111 22 2 333 4 4 5 5 6 6 6

Number of Facility Spills Number of Pipeline Spills Total Number of Spills

4 5

Figure 3-4. Probability (percent chance) of a Particular Number of Offshore Spills >1,000 bbl Occurring as a 

Result of Either Facility or Pipeline Operations Related to a CPA Proposed Action. 

0

25

50

75

100

Percent Probability of Occurrence 

Low Resource Estimate

High Resource Estimate

000 1 11 222 333 444 5 5

Number of Facility Spills Number of Pipeline Spills Total Number of Spills

5

Figure 3-5. Probability (percent chance) of a Particular Number of Offshore Spills >1,000 bbl Occurring as 

a Result of Either Facility or Pipeline Operations Related to a WPA Proposed Action. 
Figures A-11

Figure 3-7. Probabilities of Oil Spills (>

Figure 3-6. Probabilities of Oil Spills (>1,000 bbl) Occurring and Contacting within 10 Days the Shoreline 

(counties and parishes) as a Result of a Proposed Action in the Western Planning Area (only 

counties and parishes with greater than a 0.5% risk of contact within 10 days are shown). 

1,000 bbl) Occurring and Contacting within 10 Days the Shoreline 

(counties and parishes) as a Result of a Proposed Action in the Central Planning Area (only counties 

and parishes with greater than a 0.5% risk of contact within 10 days are shown). 
Figure 3-8. Probabilities of Oil Spills (>1,000 bbl) Occurring and Contacting within 10 Days State Offshore Waters or Recreationa

CPA or WPA Proposed Action. 
Figure 3-9. Probabilities of Oil Spills (>1,000 bbl) Occurring and Contacting within 10 Days Endangered Beach Mice Hab

CPA or WPA Proposed Action.
A-14 Central and Western Gulf of Mexico Multisale Supplemental EIS

Figure 3-10. Probabilities of Oil Spills (>1,000 bbl) Occurring and Contacting within 10 Days Known Locations of 

Gulf Sturgeon as a Result of CPA Proposed Action. 

Figure 3-11. Probabilities of Oil Spills (≥1,000 bbl) Occurring and Contacting within 10 Days Gulf Sturgeon 

Critical Habitat as a Result of a CPA Proposed Action. 
Figure 3-12. Major Oil Pipeline Landfall Areas Developed for OSRA. 
A-16 Central and Western Gulf of Mexico Multisale Supplemental EIS

Figure 3-13. Spatial Frequency (%) of the Water Mass Associated with the Loop Current in the Eastern 

Gulf of Mexico Based on Data for the Period 1976-2003.
Figure 4-1. Coastal and Marine Waters of the Gulf of Mexico. 
Figure 4-2. Location of Topographic Features in the Gulf of Mexico. 
APPENDIX B 

TABLES
Tables B-3 

Table 3-1 

 

Projected Oil and Gas Production in the Gulf of Mexico OCS 

 Proposed 

Action 

OCS Program 

(2007-2046) 

Central Gulf of Mexico 

Reserve/Resource Production 

Oil (BBO) 0.807-1.3361 21.933-24.5101

Gas (Tcf) 3.365-5.4051 90.155-102.7611

 

Western Gulf of Mexico 

Reserve/Resource Production 

Oil (BBO) 0.242-0.423 6.629-8.060 

Gas (Tcf) 1.644-2,647 52.211-59.961 

1

 Includes the projected activity associated with the addition of the 181 South Area. 

BBO = billion barrels of oil. 

Tcf = trillion cubic feet. 
Table 3-2 Offshore Scenario Information Related to the Proposed Action in the Central Planning Area Offshore Subareas1 C0-60 (western) C0-60 (eastern) C60-200 C200-400 C400-800 C800-1600 C1600-2400 

Wells Drilled Exploration and Delineation Wells 14-16 3 9-12 7-11 9-14 10-18 7-12 

Development Wells 51-59 9-10 22-26 75-107 61-83 56-91 37-59 

Oil Wells 13-15 2-2 7-8 43-61 36-49 33-54 22-36 Gas Wells 38-44 7-8 15-18 32-46 25-33 23-37 15-23 

Workovers and Other Well Activities 309-357 55-63 133-161 455-651 371-504 343-553 224-357 Production Structures Installed 17-18 3 2-3 1-3 1-3 1-4 1-3 

Removed Using Explosives 10 2 2 0-1 0-1 0 0 Total Removed 14 2-3 2-3 1-3 1-3 1-4 1-3 

Method of Oil Transportation4 Percent Piped 99% 99% 100% 100% 100% 0%-50% 0%-100% 0

Percent Barged 1% 1% 0% 0% 0% 0% 0% Percent Tankered 0% 0% 0% 0% 0% 0%-50% 0%-100% 

Length of Installed Pipelines (km)5 40-720 10-130 NA NA NA NA NA Blowouts 0 0 0 0 0-1 0-1 0 Service-Vessel Trips (1,000 round trips) 18-19 3 3-4 4-7 19-52 19-68 18-51 Helicopter Operations (1,000 operations) 607-1,016 107-169 71-169 36-169 36-169 36-226 36-169 1 See Figure 3-1. 2 Includes the projected activity associated with the addition of the 181 South Area. 3 Subarea totals may not add up to the planning area total because of rounding. 4 100% of gas is assumed to be piped. 5 Projected length of OCS pipelines does not include length in State waters. NA means that information is not available. 
Table 3-3 Offshore Scenario Information Related to the Proposed Action in the Western Planning Area Offshore Subareas1 W0-60 W60-200 W200-400 W400-800 W800-1600 W1600-2400 

Wells Drilled Exploration and Delineation Wells 23-36 5-7 1 3-4 5-10 2-3 

Development Wells 64-89 13-15 6-7 9-13 48-75 9-15 

Oil Wells 3-5 2-2 1-2 6-8 29-45 6-9 Gas Wells 61-84 10-13 5-5 3-5 20-30 3-6 

Workovers and Other Well Activities 392-539 77-91 35-42 56-77 294-455 56-91 Production Structures Installed 21-31 2 1 1 1-3 1-2 

Removed Using Explosives 9-15 1 0 0 0 0 Total Removed 13-22 2 1 1 1-3 1 

Method of Oil Transportation3 Percent Piped 99% 100% 100% 100% 0%-50% 0%-100% 

Percent Barged 1% 0% 0% 0% 0% 0% Percent Tankered 0% 0% 0% 0% 0%-50% 0%-100% 0

Length of Installed Pipelines (km)4 60-420 NA NA NA NA NA Blowouts 1 0 0 0 0-1 0 Service-Vessel Trips (1,000 round trips) 23-33 3 1 16-17 18-51 16-33 Helicopter Operations (1,000 operations) 300-680 30-44 14-22 14-22 14-66 14-44 

1 See Figure 3-1. 2 Subarea totals may not add up to the planning area total because of rounding. 3 100% of gas is assumed to be piped. 4 Projected length of OCS pipelines does not include length in State waters. NA means that information is not available.
B-6 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Table 3-4 

Aggregate Average Lag in Months from Sales to First Spud for Leases Issued from 1983 to 1999 

Water Depth 1983-1987 1985-1989 1990-1994 1995-1999 

<60 m 29.3 27.8 25.8 22.9 

60m-200 m 30.5 31.0 36.0 27.2 

200m-900 m 40.4 46.4 42.9 30.0 

>900 m 84.9 93.3 84.2 53.6 

 Source: Iledare and Kaiser, 2007. 

Table 3-5 

Aggregate Average Lag in Months from Sales to First Production for Leases Issued from 1983 to 1999 

Water Depth 1983-87 1985-1989 1990-1994 1995-1999 

<60 m 59.0 53.2 49.5 41.1 

60m-200 m 74.7 65.7 60.3 47.5 

200m-900 m 128.1 123.0 70.2 54.1 

>900 m 180.6 176.9 105.9 99.6 

 Source: Iledare and Kaiser, 2007. 
Tables B-7 

Table 3-6 

 

Mean Number and Sizes of Spills Estimated to Occur in 

OCS Offshore Waters from an Accident Related 

to Activities Supporting a Proposed Action Over a 40-Year Time Period 

Spill Size Group Spill Rate 

(Spills/BBO)1

Number of Spills 

Estimated for a 

CPA Proposed 

Action2

Number of Spills 

Estimated for a 

WPA Proposed 

Action2

Estimated 

Spill Size1

0-1.0 bbl 3,357.31 2,709-4,485 812-1,420 0.073

1.1-9.9 bbl 74.7 60-100 18-32 34

10.0-49.9 bbl 16.18 13-22 4-7 204

50.0-499.9 bbl 6.37 5-9 2-3 904

500.0-999.9 bbl 0.52 <1-1 <1 6404

>1,000 bbl 1.51 1-2 <1-1 4,6004

>10,000 bbl 0.39 <1-1 <1 15,0004

Notes: The number of spills estimated is derived by application of the historical rate of spills per 

volume crude oil handled (1985-1999) (Anderson and LaBelle, 2000) to the projected 

production for a proposed action in the WPA or CPA (Table 3-1). Projected production is 

an estimate of recoverable resource and is influenced by supporting infrastructure, as well 

as economic and technological factors. The actual number of spills that may occur in the 

future could vary from the estimated number. 

1 Source: Anderson and LaBelle, 2000. 

2 Source: Table 3-1. 

3 Average spill size. 

4 Median spill size. 
B-8 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Table 3-7 

 

Estimated Number of Spills that Could Happen in Gulf Coastal Waters 

from an Accident Related to Activities Supporting a Proposed Action 

Size Category Assumed Size 

CPA 

Proposed Action 

WPA 

Proposed Action 

Total 46-102 15-34 

<1 bbl 1 bbl 42-92 13-29 

>1 bbl and <50 bbl 3 bbl 2-4 1-2 

>50 bbl and <1,000 bbl 150 bbl 2-5 1-2 

>1,000 bbl 3,000 bbl <1-1 <1-1 

Note: The estimated number of spills is obtained from the count of coastal spills 

for 2001 proportioned to reflect that OCS oil comprised 19 percent of the oil 

crossing into GOM coastal waters in 2001. Intrastate oil and refined 

product transport were not included. The low estimate in the range was 

obtained from Dickey (2006) and the high estimate was obtained from 

aggregated national data available on the Internet (USCG, 2001). 

Sources: Dickey, personal communication, 2006; USCG, 2001; National Ocean 

Economics Program, 2006; USDOE, EIAb, 2006. 
Tables B-9 

Table 3-8 

 

Number and Volume of Chemical and Synthetic-Based Fluid Spills 

in the Gulf of Mexico during the Years 2001-2005 

Spill Size 2001 2002 2003 2004 2005 

(bbl) Chemical SBF Chemical SBF Chemical SBF Chemical SBF Chemical SBF 

1-<50 9 4 6 11 2 11 16 5 42 7 

50-<100 0 0 0 2 0 2 1 1 3 0 

100-<500 2 3 2 1 1 3 2 2 2 6 

500-<1,000 0 1 0 2 0 1 0 1 1 0 

>1,000 0 0 0 1 0 1 1 1 0 0 

Total 11 8 8 17 3 18 20 10 48 13 

Note: For the years 2001-2003, the total volume of drilling fluid was recorded. For 2004, the syntheticbased fluid fraction of the whole drilling fluid was recorded. 

Source: Anderson, personal communication, 2007. 

Table 3-9 

 

Record of Past Spills Where >1,000 bbl of Synthetic-Based Fluid (SBF) was Released 

Date Location Water Depth 

(ft) 

SBF Volume Released* 

(bbl) 

Cause 

03/01/02 WR 206 8,180 1,800 Emergency riser disconnect 

05/21/03 MC 822 6,040 1,421 Riser failure 

04/11/04 GC 653 4,238 1,034 Emergency riser disconnect 

10/21/07 GC 726 4,686 1,061 Hole in the riser 

* Volume reflects the amount of synthetic fluid, not the total drilling mud released. 

GC = Green Canyon. 

MC = Mississippi Canyon. 

WR = Walker Ridge. 

Source: USDOI, MMS, 2007i. 
B-10 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Table 4-1 

 

National Ambient Air Quality Standards (NAAQS) 

Pollutant Averaging Primary Secondary 

 Period Standardsa Standardsb

Ozone 8-hour d 0.08 ppm (157 μg/m3) (same as primary) 

Sulphur Dioxide Annual 0.03 ppm (80 μg/m3) NA

 24-hour 0.14 ppm (365 μg/m3) NA

 3-hour c NA 0.5 ppm (1,300 μg/m3) 

Carbon Monoxide 8-hour c 9.0 ppm (10 mg/m3) NA 

1-hour c 35 ppm (40 mg/m3) NA 

Nitrogen Dioxide Annual 0.053 ppm (100 μg/m3) (same as primary) 

Suspended Particulate 

 Matter (PM10) Annual Revoked Revoked 

 24-hour 150 μg/m3 e (same as primary) 

(PM2.5) Annual 15 μg/m3 f (same as primary) 

 24-hour 35 μg/m3 g (same as primary) 

Lead Calendar Quarter 1.5 μg/m3 (same as primary) 

a

 The levels of air quality necessary, with an adequate margin of safety, to protect the public 

health. 

b

 The levels of air quality necessary to protect the public welfare from any known or anticipated 

adverse effects of a pollutant. 

c

 Not to be exceeded more than once a year. 

d

 Three-year average of the annual fourth-highest daily maximum 8-hour average for each 

monitor. 

e

 Based on the 99th percentile of 24-hour PM10 concentration at each monitor. 

f

 Based on 3-year average of annual arithmetic mean concentrations. 

g

 Based on 3-year average of 98th percentile of 24-hour concentrations. 

Note: mg/m3

 = milligrams per cubic meter = 1,000 μg/m-3.

 μg/m3 = micrograms per cubic meter. 

Source: 40 CFR 50, 2005. 
Tables B-11 

Table 4-2 

Comparison of Hurricane-Induced Land to Water Changes by Hydrologic Basin 

in Coastal Louisiana during the 2005 Hurricane Season 

Hurricane Basin New Water Area 

(mi2

) 

Katrina Mississippi River Delta 

Breton Sound 

Pontchartrain 

Pearl River 

Total 

-18 

-41 

-19 

-4 

-82 

Rita Calcasieu/ Sabine 

Mermentau 

Teche/ Vermillion 

Atchafalaya 

Terrebonne 

Total 

-22 

-62 

-5 

-9 

-19 

-117 

Both Hurricanes Barataria -18 

Total -217 

Table 4-3 

Comparison of Habitats Affected by Storm-Induced Land/Water Change 

Habitat Type 

Comparison of Pre- and Post-Katrina Satellite 

Imagery Land Water Habitat Changes 

(mi2

) 

 Pre-Katina (2004) Post-Katrina (2005) 

Net Change 

(mi2

) 

Forested wetlands 1,329 1,328 -1 

Other land* 397 371 -26 

Fresh marsh 1,542 1,420 -122 

Intermediate marsh 1,087 997 -90 

Brackish marsh 878 845 -33 

Saline marsh 690 662 -28 

Water** 6,995 7,295 300 

Total land/water change 

(300-83 mi2

=217 mi2)*** 

 217 

* This category includes developed land, agricultural lands, and natural ridges without wetland 

vegetation. 

** This category includes 40 ac of flooded agricultural land and 43 ac of burned flooded marsh 

(83 mi2

). 

*** This number represents the total square miles of habitat loss and water change based on 

adjustments noted for burned marsh and agricultural land (i.e., 300 mi2

-83 mi2=217 mi2 of land to 

water). 
B-12 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Table 4-4 

 

Estimated Abundance of Cetaceans 

in the Northern Gulf of Mexico Oceanic Waters 

Species Common Name Estimated Number of 

Individuals 

Balaenoptera edeni Bryde’s whale 40 

Physeter macrocephalus Sperm whale* 1,349 

Kogia spp. Dwarf or pygmy sperm whale 742 

Ziphius cavirostris Cuvier’s beaked whale 95 

Unidentified ziphiid Unidentified beaked whales 146 

Feresa attenuata Pygmy killer whale 408 

Pseudorca crassidens False killer whale 1,038 

Orcinus orca Killer whale 133 

Globicephala sp. Pilot whale 2,388 

Peponocephala electra Melonheaded whale 3,451 

Grampus griseus Risso’s dolphin 2,169 

Tursiops truncatus Bottlenose dolphin 27,559 

Steno bredanensis Rough-toothed dolphin 2,223 

Lagenodelphis hosei Fraser’s dolphin 726 

Stenella frontalis Atlantic spotted dolphin 30,947 

Stenella longirostris Spinner dolphin 11,971 

Stenella attenuate Pantropical spotted dolphin 91,321 

Stenella clymene Clymene dolphin 17,355 

Stenella coeruleoalba Striped dolphin 6,505 

*Endangered. 

Source: Waring et al., 2004. 
Tables B-13 

Table 4-5 

 

Sea Turtle Taxa of the Northern Gulf of Mexico 

Order Testudines (turtles) Relative Occurrence* ESA Status** 

Family Cheloniidae (hardshell sea turtles) 

Loggerhead sea turtle (Caretta caretta) Common Threatened/Endangered 

Green sea turtle (Chelonia mydas) Common Endangered 

Hawksbill sea turtle (Eretmochelys imbricata) Rare Endangered 

Kemp’s Ridley sea turtle (Lepidochelys kempi) Common Endangered 

Family Dermochelyidae (leatherback sea turtle) 

Leatherback sea turtle (Dermochelys coriacia) Uncommon Endangered 

*Population status in the northern GOM is summarized according to the following categories: 

Common: A common species is one that is abundant wherever it occurs in the region (i.e., the northern 

GOM). Most common species are widely distributed over the area. 

Uncommon: An uncommon species may or may not be widely distributed but does not occur in large numbers. 

Uncommon species are not necessarily rare or endangered. 

Rare: A rare species is one that is present in such small numbers throughout the region that it is seldom seen. 

Although not threatened with extinction, a rare species may become endangered if conditions in its 

environment change. 

**Endangered Species Act (ESA) status is summarized according to listing status under the following categories: 

Endangered: Species determined to be in imminent danger of extinction throughout all of a significant portion 

of their range. 

Threatened: Species determined likely to become endangered in the foreseeable future. 

 
B-14 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Table 4-6 

2006 Top Species Commonly Caught by Recreational Fishers 

in the Marine Recreational Fisheries Statistics Gulf Coast States (except Texas) 

Species Total All Fish 

(#) 

Total All Fish 

(lb) 

Inland 

(#) 

Inland 

(lb) 

Ocean 

(#) 

Ocean 

(lb) 

Black drum 1,267,386 2,480,078 1,219,109 2,351,043 48,277 129,035

Dolphins 81,400 188,130 870 80,530 188,130

Gray snapper 2,594,974 1,381,957 2,043,579 483,753 551,395 898,204

Greater amberjack 66,394 683,364 1,850 64,544 683,364

Herrings 41,716,268 152,455 41,255,403 152,455 460,865 0

King mackerel 498,355 1,349,952 362,809 590,059 135,546 759,893

Mycteroperca 

groupers 

644,735 231,395 603,463 110,062 41,272 121,333

Pinfishes 6,736,540 369,738 5,710,573 346,356 1,025,967 23,382

Red drum 8,596,876 13,576,884 8,116,594 12,063,913 480,282 1,512,971

Red snapper 1,586,841 1,485,529 62,979 33,287 1,523,862 1,452,242

Saltwater 

catfishes 

8,773,173 862,261 7,673,254 742,800 1,099,919 119,461

Sand seatrout 3,457,656 1,237,721 3,337,144 1,180,793 120,512 56,928

Sheepshead 2,403,692 3,236,779 2,133,947 2,429,966 269,745 806,813

Spotted seatrout 30,439,521 15,500,347 29,925,279 15,196,037 514,242 304,310

Source: USDOC, NMFS, 2007f. 

Table 4-7 

2006 Recreational Fishing Participation 

in the Marine Recreational Fisheries Statistics Gulf Coast States 

State Participation Estimate 

(number of people) 

 Coastal Non-Coastal Out-of-State Total 

West Florida 2,083,835 1,988,445 4,072,281 

Alabama 232,799 183,511 319,720 736,030 

Mississippi 143,417 23,382 26,532 193,331 

Louisiana 867,742 108,491 197,841 1,174,074 

Gulf Total 3,327,793 315,384 2,532,538 6,175,716 

Source: USDOC, NMFS, 2007f. 
Tables B-15 

Table 4-8 

2006 Mode of Fishing in the Marine Recreational Fisheries Statistics 

for the Gulf Coast States (except Texas)

State Area Number of Trips % of State Total 

Alabama Shore Ocean (<3 mi) 836,479 39 

 Shore Inland 372,368 17 

 Charter Ocean (<3 mi) 6,238 0 

 Charter Ocean (>3 mi) 61,894 3 

 Charter Inland 9,294 0 

 Private/Rental Ocean (<3 mi) 253,917 12 

 Private/Rental Ocean (>3 mi) 184,991 9 

 Private/Rental Inland 418,244 20 

 Total 2,143,425 

West Florida Shore Ocean (<3 mi) 3,542,065 22 

 Shore Inland 3,195,967 19 

 Charter Ocean (<3 mi) 172,528 1 

 Charter Ocean (>3 mi) 268,956 2 

 Charter Inland 118,440 1 

 Private/Rental Ocean (<3 mi) 3,654,698 23 

 Private/Rental Ocean (>3 mi) 1,015,560 6 

 Private/Rental Inland 4,262,060 26 

 Total 16,230,274 

Louisiana Shore Ocean (<3 mi) 96,247 2 

 Shore Inland 837,514 19 

 Charter Ocean (<3 mi) 11,845 0 

 Charter Ocean (>3 mi) 56,052 1 

 Charter Inland 108,181 2 

 Private/Rental Ocean (<3 mi) 166,798 4 

 Private/Rental Ocean (>3 mi) 120,391 3 

 Private/Rental Inland 3,094,252 69 

 Total 4,491,280 

Mississippi Shore Ocean (<3 mi) 727 0 

 Shore Inland 324,295 32 

 Charter Ocean (<3 mi) 3,928 0 

 Charter Ocean (>3 mi) 68 0 

 Charter Inland 3,058 0 

 Private/Rental Ocean (<3 mi) 25,895 3 

 Private/Rental Ocean (>3 mi) 29,518 3 

 Private/Rental Inland 610,422 61 

 Total 997,911 

Gulf Total Shore Ocean (<3 mi) 4,475,518 19 

 Shore Inland 4,730,144 20 

 Charter Ocean (<3 mi) 194,539 1 

 Charter Ocean (>3 mi) 386,970 2 

 Charter Inland 238,973 1 

 Private/Rental Ocean (<3 mi) 4,101,308 17 

 Private/Rental Ocean (>3 mi) 1,350,460 6 

 Private/Rental Inland 8,384,978 35 

Total 23,862,890 

Source: USDOC, NMFS, 2007f.
B-16 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Table 4-9 

Employment and Establishments in Tourism-Related Industries in 2005 by Coastal County and Parish 

Area Employment Establishments Area Employment Establishments 

Texas 

Cameron 

Willacy 

Aransas 

Kenedy 

Kleberg 

Nueces 

Refugio 

San Patricio 

Brazoria 

Matagorda 

Calhoun 

Jackson 

Jefferson 

Chambers 

Galveston 

Harris 

Texas Total 

Louisiana 

Cameron 

Iberia 

Vermillion 

Lafourche 

St. Mary 

Terrebonne 

Orleans 

Plaquemines 

St. Bernard 

St. Tammany 

Louisiana Total 

Mississippi 

Hancock 

Harrison 

Jackson 

Mississippi Total 

20,192 

543 

843 

10 

1,932 

24,000 

414 

3,876 

12,962 

1,750 

1,148 

682 

15,689 

1,205 

20,085 

253,614 

358,945 

326 

5,330 

1,996 

5,391 

4,622 

8,177 

56,900 

1,317 

3,409 

15,115 

102,583 

3,623 

26,209 

6,880 

36,712 

1,046 

56 

118 

1 

114 

1,281 

22 

224 

686 

159 

94 

48 

830 

896 

1,010 

11,700 

18,285 

29 

213 

158 

299 

201 

412 

1,972 

110 

210 

755 

4,359 

160 

764 

612 

1,536 

Alabama 

Baldwin 

Mobile 

Alabama Total 

Florida 

Bay 

Franklin 

Gulf 

Escambia 

Okaloosa 

Santa Rosa 

Walton 

Jefferson 

Wakulla 

Taylor 

Citrus 

Dixie 

Levy 

Hernando 

Hillsborough 

Pasco 

Pinellas 

Collier 

Lee 

Miami-Dade 

Monroe 

Charlotte 

Manatee 

Sarasota 

Florida Total 

Gulf States Total 

13,084 

26,101 

39,185 

14,651 

963 

561 

20,783 

17,768 

6,569 

4,061 

527 

849 

1,118 

5,937 

378 

2,297 

8,283 

92,467 

19,798 

68,259 

30,501 

43,592 

166,316 

15,065 

9,126 

17,546 

28,374 

575,789 

1,113,214 

690 

1,322 

2,012 

846 

82 

51 

965 

824 

321 

206 

49 

68 

80 

359 

46 

151 

388 

3,678 

1,016 

3,568 

1,191 

1,860 

8,388 

899 

414 

907 

1,371 

27,728 

53,920 

Source: USDOC, Bureau of the Census, 2007. 
Tables B-17 

Table 4-10 

Number of Shipwrecks by Planning Area and Lease Area 

Western Planning Area Central Planning Area 

Lease Area Number of Wrecks Lease Area Number of Wrecks 

Alaminos Canyon 

Brazos 

Corpus Christi 

East Breaks 

Galveston 

Garden Banks 

High Island 

Keathley Canyon 

Matagorda Island 

Mustang Island 

North Padre Island 

Port Isabel 

South Padre Island 

Sabine Pass (Texas) 

Total 

1 

62 

3 

7 

117 

2 

110 

1 

45 

72 

39 

2 

53 

2 

516 

Atwater Valley 

Bay Marchand 

Breton Sound 

Chandeleur 

Desoto Canyon 

East Cameron 

Eugene Island 

Ewing Bank 

Green Canyon 

Grand Isle 

Henderson* 

Lloyd Ridge* 

Lund 

Mississippi Canyon 

Mobile 

Main Pass 

South Pelto 

Sabine Pass (Louisiana) 

South Marsh Island 

South Pass 

Ship Shoal 

South Timbalier 

Viosca Knoll 

Vermilion 

West Cameron 

West Delta 

Walker Ridge 

Total 

4 

3 

13 

8 

3 

48 

94 

3 

14 

31 

4 

4 

11 

44 

55 

64 

16 

16 

31 

35 

93 

90 

23 

62 

119 

63 

3 

954 

* Located within the 181 South Area.
B-18 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Table 4-11 

 

Baseline Population Projections (in thousands) by Economic Impact Area 

Calendar 

Year AL-1 MS-1 LA-1 LA-2 LA-3 LA-4 TX-1 TX-2 TX-3 FL-1 FL-2 FL-3 FL-4 

2005 695.00 476.96 333.81 560.68 1,042.49 1,379.10 1,651.49 586.93 5,606.22 855.15 607.41 3,419.80 5,948.71 

2006 705.72 450.51 331.06 573.86 1,088.03 1,091.15 1,686.24 597.58 5,780.54 860.36 616.80 3,493.31 6,023.16 

2007 713.67 457.22 333.40 577.41 1,098.80 1,111.86 1,724.29 604.87 5,867.44 882.93 627.03 3,548.82 6,164.61 

2008 719.85 462.80 334.91 579.55 1,106.87 1,129.79 1,758.03 610.66 5,939.77 903.28 635.70 3,595.51 6,290.56 

2009 725.96 468.32 336.40 581.64 1,114.83 1,147.56 1,791.49 616.39 6,011.40 923.48 644.29 3,641.76 6,415.45 

2010 732.10 473.85 337.91 583.77 1,122.84 1,165.31 1,824.91 622.13 6,083.09 943.63 652.89 3,688.03 6,540.11 

2011 738.38 479.47 339.50 586.03 1,131.09 1,183.28 1,858.62 628.00 6,155.95 963.92 661.61 3,735.00 6,665.77 

2012 744.83 485.19 341.17 588.44 1,139.60 1,201.45 1,892.65 634.01 6,230.07 984.37 670.47 3,782.72 6,792.53 

2013 751.46 491.03 342.93 591.00 1,148.39 1,219.90 1,927.09 640.17 6,305.66 1,005.02 679.48 3,831.32 6,920.68 

2014 757.94 496.75 344.62 593.44 1,156.95 1,238.05 1,961.05 646.20 6,379.83 1,025.40 688.34 3,879.05 7,047.07 

2015 764.70 502.66 346.45 596.12 1,165.96 1,256.65 1,995.70 652.47 6,456.39 1,046.14 697.45 3,928.22 7,175.91 

2016 771.53 508.60 348.31 598.88 1,175.07 1,275.28 2,030.36 658.79 6,533.27 1,066.86 706.60 3,977.56 7,304.66 

2017 778.41 514.61 350.19 601.64 1,184.26 1,294.17 2,065.62 665.17 6,611.06 1,087.99 715.87 4,027.53 7,435.71 

2018 785.36 520.69 352.08 604.42 1,193.51 1,313.35 2,101.49 671.62 6,689.79 1,109.54 725.26 4,078.12 7,569.12 

2019 792.37 526.84 353.98 607.21 1,202.84 1,332.82 2,137.99 678.12 6,769.45 1,131.52 734.78 4,129.35 7,704.92 

2020 798.83 532.35 355.78 609.88 1,211.52 1,349.77 2,168.99 684.07 6,840.79 1,149.74 743.20 4,174.95 7,819.64 

2021 806.03 538.52 357.83 612.95 1,221.22 1,368.94 2,204.48 690.71 6,920.68 1,170.88 752.68 4,226.10 7,951.26 

2022 813.29 544.77 359.90 616.03 1,231.00 1,388.38 2,240.56 697.41 7,001.50 1,192.40 762.27 4,277.88 8,085.09 

2023 820.62 551.09 361.97 619.12 1,240.86 1,408.09 2,277.22 704.18 7,083.27 1,214.32 771.99 4,330.30 8,221.17 

2024 828.02 557.48 364.06 622.24 1,250.79 1,428.09 2,314.49 711.01 7,165.99 1,236.65 781.83 4,383.35 8,359.55 

2025 834.83 563.22 366.04 625.21 1,260.03 1,445.61 2,346.46 717.26 7,240.24 1,255.42 790.58 4,430.72 8,477.73 

2026 842.62 569.79 368.36 628.73 1,270.63 1,465.76 2,383.54 724.41 7,325.18 1,277.40 800.61 4,484.96 8,615.01 

2027 850.49 576.43 370.69 632.27 1,281.32 1,486.20 2,421.22 731.63 7,411.13 1,299.76 810.77 4,539.86 8,754.51 

2028 858.43 583.16 373.04 635.83 1,292.11 1,506.92 2,459.49 738.92 7,498.08 1,322.52 821.06 4,595.44 8,896.28 

2029 866.44 589.96 375.40 639.41 1,302.98 1,527.93 2,498.36 746.28 7,586.06 1,345.67 831.48 4,651.69 9,040.34 

2030 873.80 596.07 377.63 642.82 1,313.05 1,546.38 2,531.89 752.99 7,664.98 1,365.32 840.74 4,701.92 9,164.13 

2031 881.95 603.02 380.02 646.43 1,324.10 1,567.94 2,571.91 760.50 7,754.91 1,389.22 851.41 4,759.47 9,312.53 

2032 890.19 610.05 382.43 650.08 1,335.24 1,589.80 2,612.56 768.07 7,845.90 1,413.54 862.21 4,817.74 9,463.33 

2033 898.50 617.17 384.85 653.74 1,346.48 1,611.96 2,653.86 775.73 7,937.95 1,438.29 873.15 4,876.72 9,616.57 

2034 906.89 624.36 387.28 657.42 1,357.81 1,634.43 2,695.80 783.45 8,031.08 1,463.47 884.23 4,936.42 9,772.29 

2035 915.35 631.65 389.74 661.12 1,369.23 1,657.22 2,738.41 791.26 8,125.31 1,489.09 895.45 4,996.85 9,930.54 

2036 923.90 639.01 392.21 664.84 1,380.76 1,680.33 2,781.69 799.14 8,220.65 1,515.16 906.81 5,058.02 10,091.35

2037 932.52 646.47 394.69 668.59 1,392.38 1,703.75 2,825.66 807.11 8,317.10 1,541.68 918.32 5,119.93 10,254.76

2038 941.23 654.01 397.19 672.35 1,404.10 1,727.51 2,870.32 815.15 8,414.68 1,568.67 929.97 5,182.61 10,420.81

2039 950.02 661.63 399.70 676.14 1,415.91 1,751.59 2,915.69 823.27 8,513.41 1,596.14 941.77 5,246.06 10,589.56

2040 958.88 669.35 402.24 679.95 1,427.83 1,776.01 2,961.77 831.47 8,613.29 1,624.08 953.72 5,310.28 10,761.04

2041 967.84 677.16 404.78 683.77 1,439.84 1,800.77 3,008.59 839.75 8,714.35 1,652.51 965.82 5,375.28 10,935.29

2042 976.87 685.06 407.35 687.63 1,451.96 1,825.88 3,056.14 848.12 8,816.60 1,681.44 978.08 5,441.09 11,112.37

2043 985.99 693.05 409.93 691.50 1,464.18 1,851.33 3,104.44 856.57 8,920.04 1,710.88 990.49 5,507.69 11,292.32

2044 995.20 701.13 412.52 695.39 1,476.50 1,877.14 3,153.51 865.11 9,024.70 1,740.83 1,003.06 5,575.12 11,475.18

2045 1,004.49 709.31 415.13 699.31 1,488.93 1,903.31 3,203.36 873.72 9,130.58 1,771.31 1,015.78 5,643.37 11,660.99

2046 1,013.87 717.58 417.76 703.25 1,501.46 1,929.85 3,253.99 882.43 9,237.71 1,802.32 1,028.67 5,712.45 11,849.82

2047 1,023.33 725.95 420.41 707.21 1,514.09 1,956.75 3,305.42 891.22 9,346.09 1,833.88 1,041.73 5,782.38 12,041.71

2048 1,032.89 734.41 423.07 711.19 1,526.84 1,984.03 3,357.66 900.10 9,455.75 1,865.98 1,054.94 5,853.17 12,236.70

Notes: Actual Woods & Poole projections for 2005 through 2010, 2015, 2020, 2025, and 2030. 

 Missing estimates through 2030 calculated using average annual growth rate for the 5-year period; projections after 2030 calculated using the 

average annual growth rate from 2025 to 2030. 

Source: Woods & Poole Economics, Inc., 2007. 
Tables B-19 

Table 4-12 

 

Baseline Employment Projections (in thousands) by Economic Impact Area 

Calendar 

Year AL-1 MS-1 LA-1 LA-2 LA-3 LA-4 TX-1 TX-2 TX-3 FL-1 FL-2 FL-3 FL-4 

2005 364.12 240.86 175.21 301.34 612.65 763.61 732.70 292.73 3,235.85 487.32 320.79 1,959.96 3,389.60

2006 369.61 226.97 176.80 308.37 635.01 594.14 747.93 297.69 3,298.53 499.95 327.04 2,001.44 3,460.73

2007 375.11 231.56 179.34 312.41 643.81 612.02 763.14 302.61 3,366.19 512.60 333.30 2,042.96 3,531.89

2008 380.61 236.15 181.89 316.47 652.58 629.89 778.37 307.56 3,433.87 525.26 339.60 2,084.48 3,603.08

2009 386.10 240.75 184.45 320.52 661.36 647.77 793.60 312.48 3,501.57 537.91 345.89 2,126.02 3,674.27

2010 391.60 245.35 187.02 324.57 670.14 665.64 808.82 317.40 3,569.28 550.57 352.18 2,167.58 3,745.49

2011 397.10 249.95 189.60 328.62 678.91 683.52 824.05 322.30 3,637.02 563.23 358.48 2,209.13 3,816.71

2012 402.59 254.56 192.18 332.67 687.68 701.38 839.27 327.21 3,704.77 575.88 364.78 2,250.69 3,887.95

2013 408.09 259.17 194.78 336.72 696.45 719.26 854.48 332.10 3,772.56 588.55 371.08 2,292.26 3,959.19

2014 413.59 263.78 197.38 340.77 705.22 737.14 869.71 336.99 3,840.35 601.21 377.37 2,333.82 4,030.46

2015 419.08 268.39 200.00 344.81 713.98 755.00 884.93 341.86 3,908.16 613.87 383.68 2,375.38 4,101.72

2016 424.58 273.01 202.65 348.87 722.74 772.87 900.15 346.72 3,976.04 626.53 389.98 2,416.96 4,173.01

2017 430.15 277.71 205.33 352.97 731.61 791.17 915.63 351.64 4,045.09 639.46 396.38 2,459.27 4,245.55

2018 435.79 282.49 208.05 357.12 740.58 809.90 931.38 356.64 4,115.35 652.65 402.89 2,502.32 4,319.34

2019 441.50 287.36 210.81 361.31 749.67 829.07 947.40 361.71 4,186.82 666.11 409.51 2,546.12 4,394.42

2020 446.56 291.50 213.24 365.08 757.78 844.36 961.03 366.14 4,247.54 677.19 415.19 2,583.28 4,458.19

2021 452.06 296.13 215.94 369.13 766.54 862.23 976.26 370.96 4,315.54 689.85 421.48 2,624.87 4,529.54

2022 457.62 300.84 218.68 373.23 775.39 880.48 991.72 375.83 4,384.62 702.75 427.88 2,667.12 4,602.02

2023 463.26 305.62 221.45 377.37 784.35 899.11 1,007.44 380.77 4,454.81 715.89 434.37 2,710.06 4,675.67

2024 468.96 310.48 224.26 381.56 793.41 918.14 1,023.40 385.78 4,526.13 729.28 440.96 2,753.69 4,750.49

2025 474.05 314.66 226.75 385.34 801.55 933.71 1,037.16 390.21 4,587.53 740.51 446.68 2,791.22 4,814.91

2026 479.54 319.31 229.50 389.39 810.30 951.57 1,052.38 394.98 4,655.65 753.17 452.97 2,832.80 4,886.29

2027 485.10 324.03 232.29 393.49 819.14 969.78 1,067.83 399.80 4,724.79 766.05 459.35 2,875.01 4,958.73

2028 490.73 328.82 235.11 397.63 828.07 988.33 1,083.50 404.69 4,794.96 779.14 465.82 2,917.84 5,032.25

2029 496.42 333.68 237.97 401.82 837.10 1,007.24 1,099.40 409.63 4,866.17 792.47 472.38 2,961.31 5,106.86

2030 501.53 337.91 240.52 405.61 845.27 1,023.03 1,113.27 414.05 4,928.16 803.82 478.14 2,999.14 5,171.83

2031 507.35 342.90 243.44 409.88 854.49 1,042.60 1,129.61 419.11 5,001.35 817.56 484.87 3,043.82 5,248.50

2032 513.23 347.97 246.40 414.19 863.81 1,062.55 1,146.19 424.23 5,075.62 831.54 491.70 3,089.17 5,326.32

2033 519.18 353.11 249.39 418.55 873.24 1,082.88 1,163.01 429.42 5,151.00 845.76 498.63 3,135.20 5,405.28

2034 525.20 358.32 252.42 422.95 882.76 1,103.60 1,180.08 434.67 5,227.49 860.22 505.65 3,181.91 5,485.42

2035 531.29 363.62 255.49 427.40 892.39 1,124.71 1,197.40 439.98 5,305.12 874.93 512.77 3,229.31 5,566.75

2036 537.46 368.99 258.59 431.90 902.12 1,146.23 1,214.97 445.36 5,383.91 889.89 520.00 3,277.42 5,649.28

2037 543.69 374.44 261.73 436.45 911.97 1,168.16 1,232.80 450.80 5,463.86 905.11 527.32 3,326.25 5,733.03

2038 549.99 379.97 264.91 441.04 921.91 1,190.51 1,250.90 456.31 5,545.00 920.58 534.75 3,375.81 5,818.03

2039 556.37 385.59 268.13 445.68 931.97 1,213.29 1,269.26 461.88 5,627.35 936.32 542.28 3,426.10 5,904.28

2040 562.82 391.29 271.38 450.37 942.14 1,236.50 1,287.89 467.53 5,710.92 952.33 549.92 3,477.14 5,991.82

2041 569.35 397.07 274.68 455.11 952.41 1,260.16 1,306.79 473.24 5,795.73 968.62 557.66 3,528.95 6,080.65

2042 575.95 402.93 278.01 459.89 962.80 1,284.27 1,325.97 479.03 5,881.80 985.18 565.52 3,581.52 6,170.80

2043 582.63 408.89 281.39 464.73 973.31 1,308.84 1,345.43 484.88 5,969.15 1,002.03 573.48 3,634.88 6,262.29

2044 589.39 414.93 284.81 469.62 983.92 1,333.88 1,365.18 490.81 6,057.79 1,019.16 581.56 3,689.04 6,355.13

2045 596.22 421.06 288.27 474.56 994.66 1,359.40 1,385.21 496.80 6,147.75 1,036.59 589.75 3,744.00 6,449.35

2046 603.14 427.28 291.77 479.56 1,005.51 1,385.41 1,405.54 502.88 6,239.05 1,054.31 598.06 3,799.78 6,544.96

2047 610.13 433.59 295.31 484.60 1,016.47 1,411.92 1,426.17 509.02 6,331.71 1,072.34 606.48 3,856.39 6,642.00

2048 617.20 440.00 298.90 489.70 1,027.56 1,438.93 1,447.10 515.24 6,425.74 1,090.67 615.03 3,913.84 6,740.47

Notes: Actual Woods & Poole projections for 2005 through 2010, 2015, 2020, 2025, and 2030. 

 Missing estimates through 2030 calculated using average annual growth rate for the 5-year period; projections after 2030 calculated using the 

average annual growth rate from 2025 to 2030. 

Source: Woods & Poole Economics, Inc., 2007. 
KEYWORD INDEX
Keyword Index Keyword-3 

KEYWORD INDEX 

Air Quality, x, xi, 1-7, 2-5, 2-8, 2-20, 4-3, 4-4, 4-5, 4-6, 4-7, 4-8, 4-9, 4-117, 4-119, 4-131, 4-210, 4-211, 

4-215, 4-219 

Alternative Energy, 3-40, 3-41, 4-214, 4-218, 4-221 

Archaeological Resources, x, xv, 2-5, 2-14, 2-24, 3-19, 4-169, 4-170, 4-171, 4-172, 4-173, 4-174, 4-176, 

4-177, 4-178, 4-179, 4-180, 4-181, 4-210, 4-212, 4-213, 4-215, 4-219, 4-220, 4-221 

Artificial Reefs, 1-7, 2-5, 3-37, 4-139, 4-140, 4-141, 4-151, 4-158, 4-161, 4-163, 4-171, 4-220, 4-221 

Beach Mice, x, xiii, 2-12, 4-107, 4-108, 4-109, 4-110, 4-111, 4-210, 4-211 

Blowouts, viii, xi, xii, xiv, xv, xvi, 2-8, 2-9, 2-11, 2-13, 2-14, 2-15, 2-20, 2-22, 2-23, 2-25, 3-8, 3-24, 3-

26, 3-33, 4-3, 4-6, 4-7, 4-8, 4-10, 4-19, 4-20, 4-21, 4-26, 4-55, 4-56, 4-57, 4-59, 4-61, 4-62, 4-64, 4-65, 

4-66, 4-67, 4-68, 4-69, 4-70, 4-71, 4-78, 4-79, 4-80, 4-81, 4-82, 4-83, 4-90, 4-91, 4-92, 4-99, 4-102, 4-

103, 4-104, 4-135, 4-141, 4-142, 4-143, 4-144, 4-145, 4-147, 4-148, 4-149, 4-153, 4-154, 4-155, 4-156, 

4-176, 4-177, 4-182, 4-184, 4-185, 4-188, 4-192, 4-197, 4-198, 4-210, 4-212, 4-215, 4-216, 4-219 

Chemosynthetic Communities, xiii, 1-7, 1-8, 2-5, 2-11, 2-22, 3-7, 4-72, 4-73, 4-74, 4-75, 4-76, 4-77, 4-

78, 4-79, 4-80, 4-81, 4-82, 4-83, 4-84 

Coastal And Marine Birds, x, xiii, 2-12, 2-23, 4-111, 4-112, 4-115, 4-116, 4-117, 4-118, 4-119, 4-120, 4-

121, 4-122, 4-123, 4-124, 4-210, 4-211, 4-215, 4-219 

Coastal Zone Management, x, 1-5, 1-6, 4-9, 4-37, 4-38, 4-44, 5-5, 5-8 

Collisions, viii, xv, xvi, 2-15, 2-25, 3-24, 3-33, 3-40, 4-13, 4-19, 4-20, 4-26, 4-28, 4-40, 4-44, 4-49, 4-50, 

4-57, 4-58, 4-59, 4-60, 4-61, 4-66, 4-67, 4-68, 4-69, 4-70, 4-71, 4-81, 4-87, 4-89, 4-94, 4-95, 4-97, 4-

98, 4-99, 4-100, 4-101, 4-102, 4-106, 4-107, 4-120, 4-123, 4-130, 4-133, 4-176, 4-182, 4-184, 4-185, 4-

188, 4-192, 4-197, 4-198 

Commercial Fishing, x, xiv, 1-7, 2-5, 2-13, 2-23, 3-20, 3-34, 4-14, 4-92, 4-94, 4-95, 4-101, 4-105, 4-131, 

4-132, 4-134, 4-141, 4-147, 4-148, 4-149, 4-151, 4-152, 4-153, 4-155, 4-156, 4-161, 4-162, 4-182, 4-

210, 4-211, 4-215, 4-220, 4-221 

Consultation and Coordination, viii, 1-5, 1-7, 4-201, 5-3 

Cumulative Activities, viii, 3-34, 4-3, 4-14, 4-21, 4-45, 4-53, 4-60, 4-62, 4-70, 4-108, 4-110, 4-111, 4-

112, 4-145, 4-161, 4-170, 4-188, 4-192, 4-193, 4-207, 4-208 

Cumulative Impacts, viii, xi, 2-11, 2-21, 2-22, 4-3, 4-8, 4-9, 4-14, 4-20, 4-21, 4-28, 4-32, 4-33, 4-41, 4-

45, 4-51, 4-53, 4-59, 4-60, 4-62, 4-63, 4-69, 4-72, 4-81, 4-82, 4-83, 4-84, 4-92, 4-95, 4-105, 4-107, 4-

108, 4-110, 4-111, 4-112, 4-123, 4-124, 4-131, 4-133, 4-134, 4-135, 4-144, 4-145, 4-146, 4-148, 4-149, 

4-155, 4-156, 4-161, 4-162, 4-167, 4-169, 4-170, 4-178, 4-181, 4-186, 4-187, 4-188, 4-192, 4-193, 4-

198, 4-200, 4-206, 4-209, 4-211, 4-213, 4-216 

Deepwater, xii, 2-11, 2-22, 3-4, 3-6, 3-7, 3-8, 3-9, 3-14, 3-15, 3-16, 3-22, 3-30, 3-33, 3-35, 3-41, 4-16, 4-

20, 4-57, 4-67, 4-72, 4-73, 4-74, 4-75, 4-76, 4-77, 4-78, 4-79, 4-80, 4-81, 4-82, 4-83, 4-86, 4-89, 4-94, 

4-132, 4-135, 4-143, 4-148, 4-152, 4-155, 4-170, 4-171, 4-173, 4-183, 4-200, 4-210, 4-211, 4-215, 4-

216 

Demographics, xv, 2-15, 2-25, 4-187, 4-188, 4-190, 4-192 

Discharges, x, xi, xii, xiv, 2-9, 2-11, 2-13, 2-16, 2-20, 2-22, 2-23, 2-26, 3-10, 3-11, 3-19, 3-25, 3-26, 3-34, 

3-39, 4-9, 4-10, 4-11, 4-12, 4-14, 4-15, 4-17, 4-18, 4-19, 4-20, 4-21, 4-55, 4-56, 4-57, 4-59, 4-60, 4-61, 

4-62, 4-64, 4-65, 4-66, 4-69, 4-70, 4-71, 4-75, 4-76, 4-77, 4-80, 4-82, 4-83, 4-86, 4-87, 4-88, 4-89, 4-

92, 4-93, 4-95, 4-98, 4-99, 4-100, 4-101, 4-104, 4-105, 4-106, 4-107, 4-116, 4-117, 4-119, 4-124, 4-

128, 4-129, 4-131, 4-132, 4-135, 4-137, 4-138, 4-139, 4-140, 4-142, 4-144, 4-145, 4-147, 4-148, 4-151, 

4-155, 4-156, 4-158, 4-159, 4-218, 4-219 

Dispersants, 3-25, 3-29, 3-30, 3-31, 4-30, 4-39, 4-40, 4-58, 4-61, 4-67, 4-71, 4-121, 4-130 
Keyword-4 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Economic Factors, xvi, 2-16, 2-25, 4-193, 4-195, 4-197, 4-198, 4-200, 4-203, 4-207 

EFH, xiv, 2-13, 2-23, 4-134, 4-135, 4-136, 4-137, 4-138, 4-139, 4-140, 4-141, 4-142, 4-143, 4-144, 4-

145, 4-146, 4-147, 4-148, 5-9 

Employment, xv, xvi, 2-15, 2-16, 2-25, 4-157, 4-162, 4-182, 4-187, 4-188, 4-189, 4-190, 4-191, 4-192, 4-

193, 4-194, 4-195, 4-196, 4-197, 4-198, 4-199, 4-200, 4-202, 4-203, 4-204, 4-205, 4-207, 4-209 

Environmental Justice, x, xvi, 1-5, 2-16, 2-25, 4-190, 4-200, 4-201, 4-202, 4-203, 4-204, 4-205, 4-206, 4-

207, 4-208, 4-209 

Essential Fish Habitats, xiv, 1-5, 2-13, 2-23, 4-134, 4-136, 4-153, 4-210, 4-211, 4-215, 5-9 

Explosive Removals, 2-5, 3-20, 4-56, 4-60, 4-65, 4-66, 4-70, 4-87, 4-88, 4-93, 4-102, 4-129, 4-131, 4-145 

Fish Resources, xiv, 2-13, 2-23, 4-43, 4-134, 4-135, 4-137, 4-138, 4-139, 4-140, 4-141, 4-142, 4-143, 4-

144, 4-146, 4-147, 4-148, 4-151, 4-210, 4-211, 4-215, 4-219, 4-220 

Fisheries, x, xiv, 1-8, 2-5, 2-13, 2-14, 2-23, 2-24, 3-9, 4-53, 4-59, 4-61, 4-62, 4-69, 4-71, 4-81, 4-95, 4-98, 

4-101, 4-106, 4-115, 4-123, 4-134, 4-135, 4-136, 4-141, 4-143, 4-144, 4-145, 4-146, 4-147, 4-148, 4-

149, 4-150, 4-151, 4-152, 4-153, 4-154, 4-155, 4-156, 4-157, 4-158, 4-159, 4-160, 4-161, 4-181, 4-200, 

4-219, 4-220, 5-4, 5-5, 5-7, 5-9 

Flaring, 3-16, 3-17, 4-4, 4-5, 4-6 

Flower Garden Banks, ix, 1-5, 2-4, 2-5, 2-19, 4-62, 4-63, 4-67, 4-68, 4-69, 4-143, 4-145, 4-148, 4-210, 4-

211, 4-216 

Gulf sturgeon, 4-210, 4-211 

Gulf Sturgeon, xiv, 2-13, 4-124, 4-125, 4-126, 4-127, 4-128, 4-129, 4-130, 4-131, 4-132, 4-133, 4-134, 4-

210, 4-211, 4-219 

Hurricanes, x, 2-11, 2-21, 3-11, 3-12, 3-17, 3-18, 3-19, 3-20, 3-22, 3-25, 3-33, 3-34, 3-35, 3-36, 3-37, 3-

40, 3-42, 4-4, 4-11, 4-14, 4-21, 4-22, 4-23, 4-24, 4-27, 4-29, 4-30, 4-33, 4-34, 4-35, 4-36, 4-39, 4-40, 4-

43, 4-44, 4-45, 4-46, 4-51, 4-52, 4-58, 4-59, 4-61, 4-62, 4-63, 4-67, 4-69, 4-71, 4-86, 4-94, 4-95, 4-96, 

4-106, 4-107, 4-108, 4-110, 4-111, 4-115, 4-125, 4-126, 4-127, 4-131, 4-132, 4-135, 4-144, 4-145, 4-

147, 4-148, 4-150, 4-153, 4-155, 4-156, 4-157, 4-158, 4-163, 4-167, 4-168, 4-171, 4-179, 4-180, 4-181, 

4-183, 4-188, 4-189, 4-190, 4-191, 4-192, 4-193, 4-194, 4-195, 4-199, 4-202, 4-204, 4-205, 4-208, 5-4 

Income, xvi, 2-16, 2-25, 4-157, 4-161, 4-188, 4-190, 4-191, 4-192, 4-193, 4-194, 4-200, 4-201, 4-202, 4-

203, 4-204, 4-205, 4-206, 4-207, 4-208, 4-209, 4-214, 4-217 

Infrastructure, vii, x, xi, xii, xv, xvi, 2-10, 2-11, 2-15, 2-16, 2-21, 2-22, 2-24, 2-25, 3-3, 3-4, 3-8, 3-13, 3-

14, 3-15, 3-16, 3-17, 3-18, 3-21, 3-22, 3-24, 3-26, 3-34, 3-35, 3-36, 3-39, 4-11, 4-12, 4-14, 4-24, 4-25, 

4-30, 4-33, 4-34, 4-36, 4-55, 4-56, 4-57, 4-59, 4-61, 4-62, 4-64, 4-65, 4-66, 4-69, 4-71, 4-92, 4-117, 4-

118, 4-147, 4-156, 4-157, 4-163, 4-173, 4-174, 4-176, 4-179, 4-181, 4-182, 4-183, 4-184, 4-185, 4-186, 

4-187, 4-199, 4-201, 4-202, 4-203, 4-204, 4-205, 4-207, 4-208, 4-209, 4-218, 4-221 

Land Use, x, xv, 2-15, 2-24, 4-181, 4-182, 4-183, 4-184, 4-185, 4-186, 4-187, 4-190, 4-210, 4-211, 4-215, 

4-221 

Lease Sale 200, x, 4-214, 4-217 

Live Bottoms, ix, xii, 1-8, 2-4, 2-10, 2-16, 2-17, 3-7, 4-49, 4-53, 4-54, 4-55, 4-56, 4-57, 4-58, 4-59, 4-60, 

4-61, 4-62, 4-64, 4-69, 4-70, 4-71, 4-99, 4-100, 4-105, 4-106, 4-137, 4-138, 4-139, 4-140, 4-143, 4-145, 

4-146, 4-147, 4-210, 4-211, 4-215, 4-216, 5-9 

Louisiana Highway 1, 2-7, 4-187, 4-199, 4-200, 4-204, 4-205, 4-208, 5-4 

Marine Mammals, x, xiii, 1-5, 1-8, 2-5, 2-11, 2-22, 3-12, 3-16, 3-19, 4-84, 4-86, 4-87, 4-88, 4-89, 4-90, 4-

91, 4-92, 4-93, 4-94, 4-95, 4-101, 4-210, 4-211, 4-215, 4-219, 4-220, 5-4 

Mercury, 4-145, 4-147, 4-151, 4-158 

Meteorological Conditions, 4-13, 4-19 
Keyword Index Keyword-5 

Mitigating Measures, vii, ix, 1-6, 1-7, 2-3, 2-4, 2-5, 2-16, 2-18, 2-25, 2-26, 4-55, 4-64, 4-209, 4-211, 4-

215 

NEPA, vii, 1-3, 1-6, 1-7, 2-5, 2-6, 4-37, 4-38, 4-201, 5-3, 5-4, 5-9 

Noise, 3-9, 3-16, 4-86, 4-87, 4-88, 4-89, 4-90, 4-91, 4-92, 4-93, 4-95, 4-98, 4-99, 4-100, 4-101, 4-102, 4-

103, 4-105, 4-107, 4-116, 4-117, 4-118, 4-119, 4-123, 4-124, 4-129, 4-161, 4-164, 4-165, 4-168, 4-219 

Oil Spills, viii, x, xii, xiv, xv, 2-9, 2-10, 2-11, 2-13, 2-14, 2-15, 2-21, 2-22, 2-23, 2-24, 3-9, 3-11, 3-15, 3-

24, 3-25, 3-26, 3-27, 3-28, 3-29, 3-30, 3-31, 3-32, 3-33, 4-6, 4-7, 4-8, 4-13, 4-19, 4-21, 4-22, 4-26, 4-

27, 4-28, 4-29, 4-30, 4-32, 4-33, 4-39, 4-40, 4-43, 4-44, 4-45, 4-46, 4-48, 4-50, 4-51, 4-52, 4-53, 4-55, 

4-56, 4-57, 4-58, 4-59, 4-60, 4-61, 4-62, 4-64, 4-65, 4-66, 4-67, 4-68, 4-69, 4-70, 4-71, 4-79, 4-80, 4-

82, 4-86, 4-90, 4-91, 4-92, 4-93, 4-94, 4-95, 4-102, 4-103, 4-104, 4-106, 4-107, 4-109, 4-110, 4-111, 4-

112, 4-115, 4-120, 4-121, 4-122, 4-123, 4-124, 4-129, 4-130, 4-131, 4-133, 4-134, 4-141, 4-142, 4-143, 

4-144, 4-145, 4-149, 4-153, 4-154, 4-156, 4-157, 4-160, 4-161, 4-162, 4-163, 4-164, 4-165, 4-166, 4-

167, 4-168, 4-169, 4-170, 4-176, 4-177, 4-178, 4-179, 4-181, 4-184, 4-185, 4-197, 4-198, 4-200, 4-201, 

4-205, 4-206, 4-208, 4-210, 4-212, 4-215, 4-216, 4-218, 4-219, 4-220, 4-221 

OSRA, 3-26, 3-27, 4-133 

Physical Oceanography, 3-41, 3-42, 4-74 

Pinnacle Trend, xii, 2-10, 2-17, 4-53, 4-54, 4-55, 4-56, 4-57, 4-58, 4-59, 4-60, 4-61, 4-62, 4-138, 4-140, 

4-145, 4-210, 4-211, 4-215 

Pipelines, x, xiv, 2-6, 2-13, 2-17, 3-7, 3-8, 3-11, 3-13, 3-14, 3-17, 3-18, 3-21, 3-23, 3-24, 3-28, 3-34, 3-35, 

3-39, 4-11, 4-12, 4-14, 4-18, 4-19, 4-21, 4-26, 4-28, 4-32, 4-34, 4-37, 4-38, 4-39, 4-40, 4-41, 4-42, 4-

44, 4-46, 4-47, 4-48, 4-49, 4-50, 4-51, 4-52, 4-55, 4-56, 4-58, 4-60, 4-61, 4-64, 4-65, 4-66, 4-67, 4-70, 

4-71, 4-77, 4-102, 4-103, 4-116, 4-124, 4-128, 4-129, 4-131, 4-144, 4-145, 4-147, 4-151, 4-152, 4-166, 

4-167, 4-172, 4-173, 4-178, 4-179, 4-180, 4-183, 4-186, 4-201, 4-212, 4-219, 5-4 

Port Fourchon, xv, 2-7, 2-15, 2-25, 3-22, 3-40, 4-25, 4-37, 4-38, 4-44, 4-47, 4-183, 4-186, 4-187, 4-188, 

4-191, 4-192, 4-193, 4-199, 4-200, 4-204, 4-205, 4-208 

Produced Waters, xiv, 2-13, 2-23, 3-10, 4-21, 4-43, 4-44, 4-59, 4-60, 4-61, 4-69, 4-70, 4-71, 4-82, 4-129, 

4-135, 4-137, 4-144, 4-145, 4-148, 4-151, 4-152, 4-153, 4-155, 4-156, 4-158, 4-218 

Public Services, x, 4-197, 4-198, 4-200 

Recreational Resources, x, xv, 2-14, 2-24, 4-162, 4-164, 4-165, 4-167, 4-169, 4-206, 4-210, 4-212, 4-213, 

4-215, 4-220 

Resource Estimates, 1-7, 3-3, 3-4, 3-25 

Sea Turtles, x, xiii, 1-8, 2-5, 2-12, 2-22, 3-19, 4-95, 4-96, 4-97, 4-98, 4-99, 4-100, 4-101, 4-102, 4-103, 4-

104, 4-105, 4-106, 4-107, 4-210, 4-211, 4-215, 4-219, 5-9 

Seagrass Communities, x, xii, 2-10, 2-21, 4-45, 4-46, 4-47, 4-48, 4-49, 4-50, 4-51, 4-52 

Service base, 3-15, 3-16, 3-21, 3-22, 3-23, 4-5, 4-12, 4-38, 4-44, 4-110, 4-145, 4-183, 4-196, 4-200 

Site Clearance, 2-5, 3-20, 4-56, 4-65, 4-66, 4-174, 4-220 

Submerged Vegetation, 4-45, 4-47, 4-49, 4-51, 4-52, 4-137 

Synthetic-Based Drilling Fluids, xi, 2-9, 2-20, 3-33, 3-34, 4-10, 4-17, 4-18, 4-20 

Topographic Features, ix, x, xii, 2-3, 2-4, 2-5, 2-10, 2-11, 2-16, 2-18, 2-21, 2-22, 2-26, 3-7, 4-57, 4-59, 4-

62, 4-63, 4-64, 4-65, 4-66, 4-67, 4-68, 4-69, 4-70, 4-71, 4-72, 4-73, 4-85, 4-135, 4-138, 4-139, 4-140, 

4-145, 4-209, 4-210, 4-211, 4-215, 4-216 

Tourism, x, xv, 2-14, 2-24, 4-29, 4-31, 4-98, 4-161, 4-162, 4-163, 4-165, 4-166, 4-167, 4-168, 4-169, 4-

182, 4-197, 4-198, 4-200, 4-206, 4-221, 5-5 

Trash, x, xiii, xv, 2-12, 2-14, 3-9, 4-86, 4-87, 4-94, 4-98, 4-99, 4-100, 4-102, 4-107, 4-109, 4-110, 4-111, 

4-116, 4-118, 4-119, 4-123, 4-151, 4-158, 4-162, 4-163, 4-164, 4-165, 4-167, 4-168, 4-169, 4-212, 4-

219 
Keyword-6 Central and Western Gulf of Mexico Multisale Supplemental EIS 

Waste Disposal, 2-15, 2-24, 3-21, 3-24, 4-118, 4-119, 4-181, 4-183, 4-184, 4-186, 4-187, 4-207 

Wastes, xii, 2-10, 2-21, 3-14, 4-14, 4-18, 4-33, 4-36, 4-44, 4-60, 4-61, 4-70, 4-71, 4-82, 4-118, 4-120, 4-

145, 4-151, 4-158, 4-164, 4-165 

Water Quality, x, xi, 2-8, 2-9, 2-20, 3-19, 4-9, 4-10, 4-11, 4-12, 4-13, 4-14, 4-15, 4-16, 4-17, 4-18, 4-19, 

4-20, 4-21, 4-46, 4-47, 4-86, 4-87, 4-88, 4-89, 4-91, 4-95, 4-99, 4-101, 4-102, 4-105, 4-107, 4-116, 4-

117, 4-119, 4-123, 4-126, 4-127, 4-128, 4-129, 4-137, 4-138, 4-139, 4-140, 4-142, 4-143, 4-145, 4-147, 

4-151, 4-158, 4-161, 4-210, 4-212, 4-213, 4-215, 4-218, 4-219 

Wetlands, x, xii, 1-5, 2-9, 2-10, 2-21, 3-9, 3-24, 3-36, 3-38, 3-40, 4-13, 4-23, 4-27, 4-28, 4-30, 4-32, 4-33, 

4-34, 4-35, 4-36, 4-37, 4-38, 4-39, 4-40, 4-41, 4-42, 4-43, 4-44, 4-46, 4-51, 4-115, 4-116, 4-118, 4-119, 

4-128, 4-132, 4-137, 4-138, 4-139, 4-141, 4-142, 4-143, 4-144, 4-148, 4-151, 4-158, 4-182, 4-218, 4-

219 
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 

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 territories under U.S. administration. 

The Minerals Management Service Mission 

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) 

primary responsibilities are to manage the mineral resources located on the Nation's Outer 

Continental Shelf (OCS), collect revenue from the Federal OCS and onshore Federal and Indian 

lands, and distribute those revenues. 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program 

administers the OCS competitive leasing program and oversees the safe and environmentally 

sound exploration and production of our Nation's offshore natural gas, oil and other mineral 

resources. The MMS Minerals Revenue Management meets its responsibilities by ensuring the 

efficient, timely and accurate collection and disbursement of revenue from mineral leasing and 

production due to Indian tribes and allottees, States and the U.S. Treasury. 

The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially 

affected parties and (2) carrying out its programs with an emphasis on working to enhance the 

quality of life for all Americans by lending MMS assistance and expertise to economic 

development and environmental protection.