U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

OCS EIS/EA 

BOEM 2015-032 

Gulf of Mexico OCS 

Oil and Gas Lease Sale: 2016

Western Planning Area Lease Sale 248

Draft Supplemental Environmental Impact Statement 

U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

OCS EIS/EA 

BOEM 2015-032 

Gulf of Mexico OCS 

Oil and Gas Lease Sale: 2016

Western Planning Area Lease Sale 248

Draft Supplemental Environmental Impact Statement 

Author 

Bureau of Ocean Energy Management 

Gulf of Mexico OCS Region 

Published by 

New Orleans

September 2015

iii

REGIONAL DIRECTOR’S NOTE

This Supplemental Environmental Impact Statement (EIS) addresses one proposed Federal action: 

proposed Outer Continental Shelf (OCS) oil and gas Lease Sale 248 in the Western Planning Area (WPA) 

of the Gulf of Mexico, as scheduled in the Proposed Final Outer Continental Shelf Oil & Gas Leasing 

Program: 2012-2017 (Five-Year Program) (USDOI, BOEM, 2012a). This Supplemental EIS 

incorporates by reference all of the relevant material in the “prior 2012-2017 Gulf of Mexico EISs” from 

which it tiers: Gulf of Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western Planning Area Lease 

Sales 229, 233, 238, 246, and 248; Central Planning Area Lease Sales 227, 231, 235, 241, and 247, Final 

Environmental Impact Statement (2012-2017 WPA/CPA Multisale EIS) (USDOI, BOEM, 2012b); Gulf 

of Mexico OCS Oil and Gas Lease Sales: 2013-2014; Western Planning Area Lease Sale 233; Central 

Planning Area Lease Sale 231, Final Supplemental Environmental Impact Statement (WPA 233/CPA 231 

Supplemental EIS) (USDOI, BOEM, 2013a); Gulf of Mexico OCS Oil and Gas Lease Sales: 2014-2016; 

Western Planning Area Lease Sales 238, 246, and 248, Final Supplemental Environmental Impact 

Statement (WPA 238/246/248 Supplemental EIS) (USDOI, BOEM, 2014); and Gulf of Mexico OCS Oil 

and Gas Lease Sales: 2015 and 2016; Western Planning Area Lease Sales 246 and 248, Final 

Supplemental Environmental Impact Statement (WPA 246/248 Supplemental EIS) (USDOI, BOEM, 

2015). 

The prior 2012-2017 Gulf of Mexico EISs analyzed the potential impacts of a WPA proposed action 

on the marine, coastal, and human environments. It is important to note that the prior 2012-2017 Gulf of 

Mexico EISs were prepared using the best information that was publicly available at the time the 

documents were prepared. This Supplemental EIS is deemed appropriate to supplement the documents 

cited above for proposed WPA Lease Sale 248 in order to consider new circumstances and information 

arising from, among other things, the Deepwater Horizon explosion, oil spill, and response. This

Supplemental EIS’s analysis focuses on updating the baseline conditions and potential environmental 

effects of oil and natural gas leasing, exploration, development, and production in the WPA since 

publication of the prior 2012-2017 Gulf of Mexico EISs. This Supplemental EIS will also assist 

decisionmakers in making informed, future decisions regarding the approval of operations, as well as 

leasing. This Supplemental EIS is the final National Environmental Policy Act (NEPA) review 

conducted for proposed WPA Lease Sale 248. 

BOEM’s Gulf of Mexico OCS Region and its predecessors have been conducting environmental 

analyses of the effects of OCS oil and gas development since the inception of NEPA. We have prepared 

and published more than 50 draft and 50 final EISs. Our goal has always been to provide factual, reliable, 

and clear analytical statements in order to inform decisionmakers and the public about the environmental 

effects of proposed OCS oil- and gas-related activities and their alternatives. We view the EIS process as 

providing a balanced forum for early identification, avoidance, and resolution of potential conflicts. It is 

in this spirit that we welcome comments on this document from all concerned parties.

Michael A. Celata

Acting Regional Director

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

v 

COVER SHEET

Supplemental Environmental Impact Statement 

for 

Proposed OCS Oil and Gas Lease Sale 248 

in the Western Planning Area of the Gulf of Mexico

Draft (x) Final ( ) 

Type of Action: Administrative (x) Legislative ( ) 

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

and Louisiana 

Agency Headquarters Contact Region Contacts 

U.S. Department of the Interior 

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region 

(GM 623E) 

1201 Elmwood Park Boulevard 

New Orleans, LA 70123-2394 

Tim Holder (HM 4010) 

U.S. Department of the Interior 

Bureau of Ocean Energy Management

45600 Woodland Road

Sterling, VA 20166 

703-787-1744 

Michelle K. Nannen

504-731-6682 

Gary D. Goeke 

504-736-3233 

ABSTRACT

This Supplemental Environmental Impact Statement (EIS) addresses one proposed Federal action: 

proposed Outer Continental Shelf (OCS) oil and gas Lease Sale 248 in the Western Planning Area (WPA) 

of the Gulf of Mexico, as scheduled in the Proposed Final Outer Continental Shelf Oil & Gas Leasing 

Program: 2012-2017 (Five-Year Program) (USDOI, BOEM, 2012a). 

This Supplemental EIS updates the baseline conditions and potential environmental effects of oil and 

natural gas leasing, exploration, development, and production in the WPA since publication of the “prior 

2012-2017 Gulf of Mexico EISs”: Gulf of Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western 

Planning Area Lease Sales 229, 233, 238, 246, and 248; Central Planning Area Lease Sales 227, 231, 

235, 241, and 247, Final Environmental Impact Statement (2012-2017 WPA/CPA Multisale EIS) 

(USDOI, BOEM, 2012b); Gulf of Mexico OCS Oil and Gas Lease Sales: 2013-2014; Western Planning 

Area Lease Sale 233; Central Planning Area Lease Sale 231, Final Supplemental Environmental Impact 

Statement (WPA 233/CPA 231 Supplemental EIS) (USDOI, BOEM, 2013a); Gulf of Mexico OCS Oil 

and Gas Lease Sales: 2014-2016; Western Planning Area Lease Sales 238, 246, and 248, Final 

Supplemental Environmental Impact Statement (WPA 238/246/248 Supplemental EIS) (USDOI, BOEM, 

2014); and Gulf of Mexico OCS Oil and Gas Lease Sales: 2015 and 2016; Western Planning Area Lease 

Sales 246 and 248, Final Supplemental Environmental Impact Statement (WPA 246/248 Supplemental 

EIS) (USDOI, BOEM, 2015). This Supplemental EIS analyzes the potential impacts of a WPA proposed 

action on sensitive coastal environments, offshore marine resources, and socioeconomic resources both 

onshore and offshore. It is important to note that this Supplemental EIS was prepared using the best 

information that was publicly available at the time the document was prepared. Where relevant 

information on reasonably foreseeable significant adverse impacts is incomplete or unavailable, the need 

for the information was evaluated to determine if it was essential to a reasoned choice among the 

alternatives and if so, it was either acquired or in the event it was impossible or exorbitant to acquire the 

information, accepted scientific methodologies were applied in its place.
vi

The proposed action is considered to be a major Federal action requiring an EIS. This document 

provides the following information in accordance with the National Environmental Policy Act (NEPA)

and its implementing regulations, and it will be used in making decisions on the proposal. This 

Supplemental EIS is the final NEPA review conducted for proposed WPA Lease Sale 248. This 

document includes the purpose of and need for the WPA proposed action, identification of the 

alternatives, description of the affected environment, and an analysis of the potential environmental 

impacts of the WPA proposed action, alternatives, and associated activities, including proposed 

mitigating measures and their potential effects. Potential contributions to cumulative impacts resulting 

from activities associated with the WPA proposed action 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 the WPA proposed action is adopted. Activities and 

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

resources are considered in the analyses.

Additional copies of this Supplemental EIS, the prior 2012-2017 Gulf of Mexico EISs, and the other 

referenced publications may be obtained from the Bureau of Ocean Energy Management, Gulf of Mexico 

OCS Region, Public Information Office (GM 250C), 1201 Elmwood Park Boulevard, Room 250, New 

Orleans, Louisiana 70123-2394, by telephone at 504-736-2519 or 1-800-200-GULF, or on BOEM’s

website at http://www.boem.gov/nepaprocess/. 
Summary vii

SUMMARY

This Supplemental Environmental Impact Statement (EIS) addresses one proposed Federal action that 

offers for lease an area on the Gulf of Mexico Outer Continental Shelf (OCS) that may contain 

economically recoverable oil and gas resources. Under the Proposed Final Outer Continental Shelf Oil & 

Gas Leasing Program: 2012-2017 (Five-Year Program) (USDOI, BOEM, 2012a), five proposed lease 

sales are scheduled for the Western Planning Area (WPA). The remaining proposed lease sale within the 

WPA is proposed WPA Lease Sale 248, which is tentatively scheduled to be held in August 2016. At the 

completion of this Supplemental EIS process, a decision will be made on whether or how to proceed with 

proposed WPA Lease Sale 248. 

This Supplemental EIS updates the baseline conditions and potential environmental effects of oil and 

natural gas leasing, exploration, development, and production in the WPA since publication of the “prior 

2012-2017 Gulf of Mexico EISs”: Gulf of Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western 

Planning Area Lease Sales 229, 233, 238, 246, and 248; Central Planning Area Lease Sales 227, 231,

235, 241, and 247, Final Environmental Impact Statement (2012-2017 WPA/CPA Multisale EIS) 

(USDOI, BOEM, 2012b); Gulf of Mexico OCS Oil and Gas Lease Sales: 2013-2014; Western Planning 

Area Lease Sale 233; Central Planning Area Lease Sale 231, Final Supplemental Environmental Impact 

Statement (WPA 233/CPA 231 Supplemental EIS) (USDOI, BOEM, 2013a); Western Planning Area 

Lease Sales 238, 246, and 248, Final Supplemental Environmental Impact Statement (WPA 238/246/248 

Supplemental EIS) (USDOI, BOEM, 2014a); and Western Planning Area Lease Sales 246 and 248, Final 

Supplemental Environmental Impact Statement (WPA 246/248 Supplemental EIS) (USDOI, BOEM, 

2015). 

This Supplemental EIS analyzes the potential impacts of the WPA proposed action on sensitive

coastal environments, offshore marine resources, and socioeconomic resources both onshore and offshore. 

It is important to note that this Supplemental EIS was prepared using the best information that was 

publicly available at the time this document was prepared. Where relevant information on reasonably 

foreseeable significant adverse impacts is incomplete or unavailable, the need for the information was 

evaluated to determine if it was essential to a reasoned choice among the alternatives and if so, it was 

either acquired or, in the event it was impossible or exorbitant to acquire the information, accepted 

scientific methodologies were applied in its place.

This summary section provides only a brief overview of the proposed WPA lease sale, alternatives, 

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

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

environmental and socioeconomic impacts discussed, it is necessary to read the entire Supplemental EIS. 

Relevant discussion of specific topics can be found in the chapters and appendices of this Supplemental 

EIS as described below.

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

lease sale, the prelease process, postlease activities, and other OCS oil- and gasrelated activities.

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

and socioeconomic effects of the proposed WPA lease sale and alternatives. It also 

discusses potential mitigating measures to avoid or minimize impacts. 

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

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

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

the Gulf of Mexico. 

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

describes offshore infrastructure and routine activities (impact-producing 

factors) associated with the proposed lease sale that could potentially affect 

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

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

discusses potential accidental events (i.e., oil spills, losses of well control, 
viii Western Planning Area Lease Sale 248 Supplemental EIS

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

a result of activities associated with the proposed lease sale.

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

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

gas-related activities, as well as all OCS oil- and gas-related activities, that 

may affect the biological, physical, and socioeconomic resources of the Gulf 

of Mexico. 

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

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

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

socioeconomic resources of the Gulf of Mexico. 

Chapter 4.1, Proposed Western Planning Area Lease Sale 248, describes the 

impacts of the WPA proposed action and two alternatives to the WPA 

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

the Gulf of Mexico. 

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

Proposed Action; Chapter 4.3, Irreversible and Irretrievable Commitment of 

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

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

Productivity. 

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

coordination activities with Federal, State, and local agencies, federally recognized 

Indian Tribes, and other interested parties that occurred during the development of 

this Supplemental EIS. 

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

EIS.

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

for preparing and reviewing this Supplemental EIS.

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

Supplemental EIS. 

• Appendix A, Catastrophic Spill Event Analysis, is a technical analysis of a potential 

low-probability catastrophic event to assist BOEM in meeting the Council on 

Environmental Quality’s (CEQ) requirements for evaluating low-probability 

catastrophic events under NEPA and to provide the public and decisionmaker with an 

understanding of the potential impacts that could result should such an event occur. 

A catastrophic spill event is a low-probability event that is not reasonably expected to 

occur and not part of the WPA proposed action or reasonably foreseeable accidental 

events. 

• Keyword Index is a list of descriptive terms and the pages on which they can be 

found in this Supplemental EIS.

Proposed Action and Alternatives

The following alternatives were included for analysis in this Supplemental EIS.

Alternatives for Proposed Western Planning Area Lease Sale 248 

Alternative A—The Proposed Action (Preferred Alternative): This alternative would offer for lease 

all unleased blocks within the proposed WPA lease sale area for oil and gas operations (Figure 2-1), with 

the following exception:
Summary ix

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

Marine Sanctuary (i.e., the boundary as of the publication of this Supplemental EIS). 

The U.S. Department of the Interior (DOI) is conservative throughout the NEPA process and includes 

the total area within the WPA for environmental review even though the leasing of portions of the WPA 

(subareas or blocks) can be deferred during a Five-Year Program.

The proposed WPA lease sale area encompasses about 28.58 million acres (ac). As of July 2015, 

approximately 22 million ac of the proposed WPA lease sale area are currently unleased. This 

information is updated monthly and can be found on BOEM’s website at http://www.boem.gov/Gulf-ofMexico-Region-Lease-Map/. The estimated amount of natural resources projected to be developed as a 

result of the proposed WPA lease sale is 0.116-0.200 billion barrels of oil (BBO) and 0.538-0.938 trillion 

cubic feet (Tcf) of gas (Table 3-1; refer to Chapter 2.3.1 for further details).

Alternative B—Exclude the Unleased Blocks Subject to the Topographic Features Stipulation: This 

alternative would offer for lease the same unleased blocks within the proposed WPA lease sale area as 

described for the proposed action (Alternative A), but it would exclude from leasing any unleased blocks 

subject to the Topographic Features Stipulation (which would be offered under Alternative A). The 

number of unleased blocks that would not be offered under Alternative B represents only a small 

percentage of the total number of blocks to be offered under Alternative A and, therefore, the estimated 

amount of resources projected to be developed is within the same scenario range as for Alternative A 

(0.116-0.200 BBO and 0.538-0.938 Tcf of gas). The exclusion of this small subset of available blocks 

would likely reduce exploration, development, and production flexibility and, therefore, would likely 

result in adverse economic effects. Refer to Chapters 2.3.2 and 4.1.2 for further details.

Alternative C—No Action: This alternative is the cancellation of the proposed WPA lease sale. If this 

alternative is chosen, the opportunity for development of the estimated 0.116-0.200 BBO and 

0.538-0.938 Tcf of gas that could have resulted from the proposed WPA lease sale would be precluded 

during the current Five-Year Program, but it could again be contemplated as part of a future Five-Year 

Program. Any potential environmental impacts arising out of the proposed WPA lease sale would not 

occur, but activities associated with existing leases in the WPA would continue. Refer to Chapters 2.3.3 

and 4.1.3 for further details.

Mitigating Measures

Proposed lease stipulations and other mitigating measures designed to reduce or eliminate 

environmental risks and/or potential multiple-use conflicts between OCS operations and U.S. Department 

of Defense activities may be applied to the chosen alternative. Five lease stipulations are proposed for the 

WPA proposed lease sale—the Topographic Features Stipulation, Military Areas Stipulation, Protected 

Species Stipulation, United Nations Convention on the Law of the Sea Royalty Payment, and the 

Stipulation on the Agreement between the United States of America and the United Mexican States 

Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico. The United Nations 

Convention on the Law of the Sea Royalty Payment is applicable to the proposed WPA lease sales even 

though it is not an environmental or military stipulation. 

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

and Minerals (ASLM). The inclusion of the stipulations as part of the analysis of the WPA proposed 

action does not ensure that the ASLM will make a decision to apply the stipulations to leases that may 

result from a 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 

lease stipulations or mitigating measures to be included in a lease sale will be described in the Final 

Notice of Sale. Mitigating measures in the form of lease stipulations are added to the lease terms and are 

therefore enforceable as part of the lease. In addition, mitigations may be added to plans and/or permits 

for OCS oil- and gas-related activities. For more information on mitigating measures that are added at the 

postlease stage, refer to Appendix A (“Commonly Applied Mitigating Measures”) of the WPA 246/248 

Supplemental EIS, which is hereby incorporated by reference. 
x Western Planning Area Lease Sale 248 Supplemental EIS

Scenarios Analyzed

Offshore activities are described in the context of scenarios for the WPA proposed action 

(Chapter 3.1) and for the OCS Program (Chapter 3.3). BOEM’s Gulf of Mexico OCS Region 

developed these scenarios to provide a framework for detailed analyses of potential impacts of the 

proposed WPA lease sale. The scenarios are presented as ranges of the amounts of undiscovered, 

unleased hydrocarbon resources estimated to be leased and discovered as a result of the WPA proposed 

action. The analyses are based on a traditionally employed 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 WPA proposed action when added to all past, present, and 

reasonably foreseeable future activities, including non-OCS oil- and gas-related activities such as import 

tankering and commercial fishing, as well as all OCS oil- and gas-related 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 (2012-2051). This includes projected activity from lease 

sales that have been held, but for which exploration or development has not yet begun or is continuing. In 

addition to human activities, impacts from natural occurrences, such as hurricanes, are analyzed.

Significant Issues 

The major issues that frame the environmental analyses in this Supplemental EIS and prior 

2012-2017 Gulf of Mexico EISs are the result of concerns raised during years of scoping for the Gulf of 

Mexico OCS Program. Issues related to OCS oil and gas exploration, development, production, and 

transportation activities include the potential for 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, impacts to tourism, aesthetic interference, cultural impacts, 

environmental justice, and conflicts with State coastal zone management programs. Environmental 

resources and activities identified during the scoping process that warrant environmental analyses include 

air quality, water quality, coastal barrier beaches and associated dunes, wetlands, seagrass communities, 

topographic features, Sargassum communities, deepwater benthic communities, soft bottom benthic 

communities, marine mammals, sea turtles, diamondback terrapins, coastal and marine birds, fish 

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

archaeological resources, and socioeconomic conditions. 

Other relevant issues include impacts from the Deepwater Horizon explosion, oil spill, and response; 

impacts from past and future hurricanes on environmental and socioeconomic resources; and impacts on 

coastal and offshore infrastructure. During the past few years, both the Gulf Coast States’ and Gulf of 

Mexico oil and gas activities have been impacted by major hurricanes. The description of the affected 

environment (Chapter 4.1) includes impacts from these relevant issues on the physical environment, 

biological environment, and socioeconomic activities, and on OCS oil- and gas-related infrastructure. 

This Supplemental EIS also considers baseline data in the assessment of impacts from the WPA proposed 

action on the resources and the environment (Chapter 4.1). 

Impact Conclusions

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

the WPA proposed action and the WPA proposed action’s incremental contribution to the cumulative 

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

action on each environmental and socioeconomic resource and the conclusions of the analyses can be 

found below.

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

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

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

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

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

H2S-related deaths have occurred on the OCS, accidents involving high concentrations of H2S could result 
Summary xi

in deaths as well as environmental damage. These emissions from routine activities and accidental events 

associated with the WPA proposed action are not expected to occur at concentrations that would change 

onshore air quality classifications. 

Water Quality (Coastal and Offshore Waters): Impacts from routine activities associated with the 

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. Offshore water impacts associated with routine activities result from the 

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

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

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

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

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

removal and pipeline placement disturb the sediments and cause increased turbidity. In addition, offshore 

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

associated with the WPA proposed action that could impact coastal and offshore water quality include 

spills of oil and refined hydrocarbons, releases of natural gas and condensate, spills of chemicals or 

drilling fluids, loss of well control, pipeline failures, collisions, or other malfunctions that would result in 

such spills. Although response efforts may decrease the amount of oil in the environment, the response 

efforts may also impact the environment through, for example, increased vessel traffic, 

hydromodification, and the application of dispersants. Natural degradation processes will also decrease 

the amount of spilled oil over time. 

Coastal Barrier Beaches and Associated Dunes: Routine activities associated with the WPA 

proposed action, such as increased vessel traffic, maintenance dredging of navigation canals, and pipeline

installation, would cause negligible impacts. Such impacts would be expected to be restricted to 

temporary and localized disturbances and not deleteriously affect barrier beaches and associated dunes. 

Indirect impacts from routine activities are negligible and indistinguishable from direct impacts of 

onshore activities. The potential impacts from accidental events (primarily oil spills) associated with the 

WPA proposed action are anticipated to be minimal. Should a spill (other than a low-probability 

catastrophic spill, which is not part of the WPA proposed action and not likely expected) contact a barrier 

beach, oiling is expected to be light and sand removal during cleanup activities minimal. No significant 

long-term impacts to the physical shape and structure of barrier beaches and associated dunes are 

expected to occur as a result of the WPA proposed action.

Wetlands: Impacts on wetlands from routine activities associated with the WPA proposed action are 

expected to be minimal because most of the activities affecting wetlands will be minor, localized, and 

temporary. Such activities may include the projected placement of short lengths of onshore pipeline

across wetlands, the placement of dredge spoil from maintenance dredging activities into minimal areas 

of wetlands, and the disposal of OCS wastes. Mitigating measures would be used to further reduce these 

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, other than a low-probability catastrophic spill, which is not part of 

the WPA proposed action and not likely expected) are anticipated to be minimal. Overall, impacts to 

wetland habitats from an oil spill associated with activities related to the WPA proposed action would be 

expected to be small and temporary because of the nature of the system, regulations, and specific cleanup 

techniques.

Seagrass Communities: Turbidity impacts from pipeline installation and maintenance dredging 

associated with the WPA proposed action would be temporary and localized due to regulations and 

mitigating measures. The increment of impacts from service-vessel transit associated with the 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.

Topographic Features: The routine activities associated with the 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 
xii Western Planning Area Lease Sale 248 Supplemental EIS

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

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

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

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

Sargassum Communities: The WPA proposed action is expected to cause only minor impacts to 

Sargassum because the effects from OCS oil- and gas-related activities would occur within a small 

portion of the Sargassum community as a whole. Limited portions of the Sargassum community could 

suffer mortality if it contacted spilled oil or occurred in an area where cleanup activities were being 

conducted. The Sargassum community lives in pelagic waters with generally high water quality and 

would be resilient to the minor accidental effects predicted. It has a yearly cycle that promotes quick 

recovery from impacts.

Chemosynthetic and Nonchemosynthetic Deepwater Benthic Communities: Chemosynthetic and 

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

and pipeline installation associated with the WPA proposed action. However, the policy requirements 

described in Notice to Lessees and Operators (NTL) 2009-G40 greatly reduce the risk of these physical 

impacts by clarifying the measures that must be taken to ensure avoidance of potential sensitive 

deepwater benthic communities and, by consequence, avoidance of other hard bottom communities. 

Potential accidental events associated with the 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.

Soft Bottom Benthic Communities: The routine activities associated with the WPA proposed action 

that would impact soft bottom benthic communities (i.e., bottom disturbance from anchoring and 

infrastructure emplacement, and accumulation of drill cuttings on the seafloor) generally occur within a 

few hundred meters of platforms, and the greatest impacts are seen in communities closest to the 

platform. Although localized impacts to comparatively small areas of soft bottom benthic communities 

would occur, impacts would be relatively minor since soft bottom benthic communities are ubiquitous 

throughout the seafloor of the WPA, an area spanning 115,645 square kilometers (44,651 square miles). 

Even in situations where substantial burial of typical benthic infaunal communities occurred, 

recolonization by populations from widespread, neighboring soft bottom substrate would be expected 

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

Marine Mammals: Routine events related to the WPA proposed action are not expected to have 

adverse effects on the size and productivity of any marine mammal species or population in the northern 

Gulf of Mexico. Characteristics of impacts from accidental events depend on whether the exposure is 

chronic or acute, and exposure may result in harassment, harm, or mortality to marine mammals, but 

population-level effects are not expected due to their wide-ranging distributions. Exposure to dispersed 

hydrocarbons is likely to result in sublethal impacts.

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

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

present in the Gulf of Mexico and due to mitigating measures that are in place. Accidental events 

associated with the WPA proposed action have the potential to impact small to large numbers of sea 

turtles. Sea turtles in the northern Gulf of Mexico may be exposed to residuals of oils spilled as a result 

of the WPA 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 the most likely scenarios, 

exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick are expected to most 

often result in sublethal impacts (e.g., decreased health and/or reproductive fitness and increased 

vulnerability to disease) to sea turtle individuals. The incremental contribution of the WPA proposed 

action would not be likely to result in a significant incremental impact on sea turtle populations within the 

WPA; in comparison, impacts from non-OCS energy-related activities, including overexploitation, 

commercial fishing, and pollution, have historically proven to be a greater threat to sea turtle species.

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

significant adverse effects on the size and recovery of terrapin species or populations in the Gulf of 

Mexico. Impacts on diamondback terrapins from smaller accidental events are likely to affect individual 

diamondback terrapins in the spill area, but they are unlikely to rise to the level of population effects (or 

significance) given the probable size and scope of such spills. Due to the distance of most terrapin habitat 

from offshore OCS energy-related activities, impacts associated with activities occurring as a result of the 

WPA proposed action are not expected to impact terrapins or their habitat. The incremental effect of the 
Summary xiii

WPA proposed action on diamondback terrapin populations is not expected to be significant when 

compared with historic and current non-OCS energy-related activities, such as habitat loss, 

overharvesting, crabbing, and fishing. 

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

the WPA proposed action on threatened and endangered and nonthreatened and nonendangered avian 

species are expected to be adverse, but not significant. These impacts include behavioral effects, 

exposure to or intake of OCS oil- and gas-related contaminants and discarded debris, disturbance-related 

impacts, and displacement of birds from habitats that are destroyed, altered, or fragmented, making these

areas otherwise unavailable. Impacts from potential oil spills associated with the WPA proposed action 

and the effects related to oil-spill cleanup are expected to be adverse, but not significant. Oil spills, 

irrespective of size, can result in some mortality as well as sublethal, chronic short- and long-term effects, 

in addition to potential impacts to food resources. Cumulative activities on coastal and marine birds are 

expected to result in discernible changes to avian species composition, distribution, and abundance; 

however, the incremental contribution of the WPA proposed action to the cumulative impact is 

considered adverse but not significant because the effects of the most probable impacts, such as lease 

sale-related operational discharges and helicopters and service-vessel noise and traffic, are expected to be 

sublethal. Some displacement of local individuals or flocks to other habitat may occur if habitat is 

available.

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

impacted by coastal environmental degradation potentially caused by canal dredging, increases in 

infrastructure, and inshore spills, and by marine environmental degradation possibly caused by pipeline

trenching, offshore discharges, and offshore spills. Impacts of routine dredging and discharges are 

localized in time and space and are regulated by Federal and State agencies through permitting processes; 

therefore, there would be minimal impact to fish resources and essential fish habitat from these routine 

activities associated with the WPA proposed action. Accidental events that could impact fish resources 

and essential fish habitat include oil or chemical spills. If a spill were to occur as a result of the WPA 

proposed action and if it was proximate to mobile fishes, the impacts of the spill would depend on 

multiple factors, including the amount spilled, the areal extent of the spill, the distance of the spill from 

particular essential fish habitats (e.g., nursery habitats), and the type and toxicity of oil spilled. Impacts 

from oil spills on sensitive essential fish habitat would be low because most sensitive essential fish 

habitats are located at depths greater than 20 m (65 ft) and the spilled substances would, at the most, reach 

the seafloor in minute concentrations. In addition, sensitive essential fish habitats would likely be 

distanced from OCS oil- and gas-related activities due to regulations, stipulations, and NTLs. An oil spill 

is expected to cause a minimal decrease in Gulf of Mexico standing fish stocks of any population because 

most spill events would be localized, therefore affecting a small portion of fish populations. 

Commercial Fisheries: Routine OCS oil- and gas-related activities in the WPA, such as seismic 

surveys and pipeline trenching, would cause negligible impacts and would not deleteriously affect 

commercial fishing activities. Indirect impacts from routine OCS oil- and gas-related activities to inshore 

habitats are negligible and indistinguishable from direct impacts of inshore non-OCS oil- and gas-related 

activities on commercial fisheries. The potential impacts from accidental events, such as an oil spill, 

associated with the WPA proposed action are anticipated to be minimal. Commercial fishermen are 

anticipated to avoid the area of an oil spill. Large spills may impact commercial fisheries by forcing area 

closures. The overall impact depends on the areal extent and length of the closure. The impact of spills 

on catch or value of catch would depend on the volume and location (i.e., distance from shore) of the 

spill, as well as the physical properties of the oil spilled.

Recreational Fishing: There could be minor and short-term, space-use conflicts with recreational 

fishermen during the initial phases of the WPA proposed action. The WPA proposed action could also 

lead to low-level environmental degradation of fish habitat, which would also negatively impact 

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

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

recreational fishing closures in the vicinity of the oil spill. Except for a low-probability catastrophic spill, 

which is not part of the WPA proposed action and not likely expected (e.g., the Deepwater Horizon oil 

spill), oil spills should not affect recreational fishing to a large degree due to the likely availability of 

substitute fishing sites in neighboring regions. 

Recreational Resources: Routine OCS oil- and gas-related activities can cause minor disturbances to 

recreational resources, particularly beaches, through increased levels of noise, debris, and rig visibility. 
xiv Western Planning Area Lease Sale 248 Supplemental EIS

Any oil spills that might result from the WPA proposed action would be small in area affected, of short 

duration, distantly located, and not likely to impact Gulf Coast recreational resources. Should an oil spill 

occur and contact a beach area or other recreational resource, it could cause some disruption during the 

physical oiling impact and cleanup phases of the spill. However, except for a low-probability 

catastrophic spill, which is not part of the WPA proposed action and not likely expected (e.g., the 

Deepwater Horizon oil spill), these effects are likely to be small in scale and of short duration.

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

archaeological resource as a result of routine OCS oil- and gas-related activities associated with the WPA 

proposed action would result from direct contact between an offshore activity (e.g., platform installation, 

drilling rig emplacement, structure removal or site clearance operation, and dredging or pipeline project) 

and a historic or prehistoric site. The archaeological survey and archaeological clearance of sites, where 

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 contact occur with archaeological 

resources, there would be localized damage to or loss of significant and/or unique archaeological 

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

and approval processes of the various Federal, State, and local agencies involved in permitting onshore 

activities. It is not very likely that accidental events associated with the WPA proposed action, including 

a large oil spill, would impact coastal prehistoric or historic archaeological sites. If a spill were to occur 

and make contact with 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, while reversible, could result in 

additional impacts to fragile cultural materials from the cleaning process.

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

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

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

infrastructure is expected to be sufficient to handle development associated with the WPA 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, 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 WPA proposed action is projected to minimally affect the demography of the 

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

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

patterns and distributions are expected to remain unchanged as a result of the WPA 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 (from elsewhere within or outside the U.S.), which is 

projected to move into focal areas such as Port Fourchon. Accidental events associated with the WPA 

proposed action, such as oil or chemical spills and vessel collisions, would likely have no effects on the 

demographic characteristics of the Gulf coastal communities.

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

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

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

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

Environmental Justice: Environmental justice implications arise indirectly from onshore activities 

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

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

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

population, the WPA proposed action is not expected to have disproportionately high or adverse 

environmental or health effects on minority or low-income populations. The WPA proposed action 

would help to maintain ongoing levels of activity, which may or may not result in the expansion of 

existing infrastructure. For a detailed discussion of scenario projections and the potential for expansion at 

existing facilities and/or construction of new facilities, refer to Chapter 3.1.2. 
Table of Contents xv 

TABLE OF CONTENTS

Page

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

LIST OF FIGURES ................................................................................................................................... xix

LIST OF TABLES ..................................................................................................................................... xxi

ABBREVIATIONS AND ACRONYMS ................................................................................................ xxiii

CONVERSION CHART ........................................................................................................................ xxvii

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

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

1.2. Description of the Proposed Action ......................................................................................... 1-5

1.3. Regulatory Framework ............................................................................................................ 1-6

1.3.1. Recent BOEM/BSEE Rule Changes ......................................................................... 1-7

1.3.1.1. Recent and Ongoing Regulatory Reform and GovernmentSponsored Research ................................................................................. 1-7

1.3.1.2. Recent and Ongoing Industry Reform and Research ............................. 1-10

1.4. Prelease Process ..................................................................................................................... 1-10

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

1.6. Other OCS Oil- and Gas-Related Activities .......................................................................... 1-14

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

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

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

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

2.2.1.1. Alternatives for Proposed Western Planning Area Lease Sale 

248 ............................................................................................................ 2-3

2.2.2. Mitigating Measures .................................................................................................. 2-4

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

2.2.2.2. Existing Mitigating Measures .................................................................. 2-5

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

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

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

2.3. Proposed Western Planning Area Lease Sale 248 ................................................................... 2-7

2.3.1. Alternative A—The Proposed Action ....................................................................... 2-7

2.3.1.1. Description ............................................................................................... 2-7

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

2.3.1.3. Mitigating Measures................................................................................. 2-9

2.3.1.3.1. Topographic Features Stipulation ......................................... 2-9

2.3.1.3.2. Military Areas Stipulation ................................................... 2-10

2.3.1.3.3. Protected Species Stipulation .............................................. 2-10

2.3.1.3.4. United Nations Convention on the Law of the Sea 

Royalty Payment Stipulation ............................................... 2-10
xvi Western Planning Area Lease Sale 248 Supplemental EIS

2.3.1.3.5. Stipulation on the Agreement between the United 

States of America and the United Mexican States 

Concerning Transboundary Hydrocarbon Reservoirs 

in the Gulf of Mexico .......................................................... 2-10

2.3.2. Alternative B—Exclude the Unleased Blocks Subject to the Topographic 

Features Stipulation ................................................................................................. 2-11

2.3.2.1. Description ............................................................................................. 2-11

2.3.2.2. Summary of Impacts .............................................................................. 2-11

2.3.3. Alternative C—No Action....................................................................................... 2-11

2.3.3.1. Description ............................................................................................. 2-11

2.3.3.2. Summary of Impacts .............................................................................. 2-12

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. Resource Estimates and Timetables ......................................................... 3-4

3.1.1.1.1. Proposed Action .................................................................... 3-4

3.1.1.1.2. OCS Program ........................................................................ 3-5

3.1.1.2. Exploration and Delineation .................................................................... 3-5

3.1.1.2.1. Seismic Surveying Operations .............................................. 3-5

3.1.1.2.2. Exploration and Delineation Plans and Drilling .................... 3-6

3.1.1.3. Development and Production ................................................................... 3-8

3.1.1.4. Operational Waste Discharged Offshore................................................ 3-12

3.1.1.5. Air Emissions ......................................................................................... 3-13

3.1.1.6. Noise ...................................................................................................... 3-13

3.1.1.7. Major Sources of Oil Inputs in the Gulf of Mexico ............................... 3-14

3.1.1.8. Offshore Transport ................................................................................. 3-14

3.1.1.9. Safety Issues ........................................................................................... 3-14

3.1.1.10. Decommissioning and Removal Operations .......................................... 3-14

3.1.2. Coastal Impact-Producing Factors and Scenario ..................................................... 3-15

3.1.2.1. Coastal Infrastructure ............................................................................. 3-15

3.1.2.2. Discharges and Wastes ........................................................................... 3-17

3.2. Impact-Producing Factors and Scenario—Accidental Events ............................................... 3-17

3.2.1. Oil Spills .................................................................................................................. 3-17

3.2.1.1. Spill Prevention ...................................................................................... 3-18

3.2.1.2. Past OCS Spills ...................................................................................... 3-18

3.2.1.3. Characteristics of OCS Oil ..................................................................... 3-19

3.2.1.4. Overview of Spill Risk Analysis ............................................................ 3-19

3.2.1.5. Risk Analysis for Offshore Spills ≥1,000 bbl ........................................ 3-20

3.2.1.6. Risk Analysis for Offshore Spills <1,000 bbl ........................................ 3-21

3.2.1.7. Risk Analysis for Coastal Spills ............................................................. 3-21

3.2.1.8. Risk Analysis by Resource..................................................................... 3-22

3.2.1.9. Spill Response ........................................................................................ 3-22

3.2.2. Losses of Well Control ............................................................................................ 3-24

3.2.3. Pipeline Failures ...................................................................................................... 3-25

3.2.4. Vessel Collisions ..................................................................................................... 3-26

3.2.5. Chemical and Drilling-Fluid Spills ......................................................................... 3-26

3.3. Cumulative Activities Scenario ............................................................................................. 3-26

3.3.1. OCS Program .......................................................................................................... 3-27

3.3.2. State Oil and Gas Activity ....................................................................................... 3-27
Table of Contents xvii

3.3.3. Other Major Factors Influencing Offshore Environments ...................................... 3-28

3.3.3.1. Dredged Material Disposal .................................................................... 3-28

3.3.3.2. OCS Sand Borrowing ............................................................................. 3-29

3.3.3.3. Marine Transportation ............................................................................ 3-29

3.3.3.4. Military Activities .................................................................................. 3-30

3.3.3.5. Artificial Reefs and Rigs-to-Reefs Development ................................... 3-30

3.3.3.6. Offshore Liquefied Natural Gas Projects and Deepwater Ports ............. 3-31

3.3.3.7. Development of Gas Hydrates ............................................................... 3-31

3.3.3.8. Renewable Energy and Alternative Use................................................. 3-31

3.3.4. Other Major Factors Influencing Coastal Environments ......................................... 3-31

3.3.4.1. Sea-Level Rise and Subsidence ............................................................. 3-32

3.3.4.2. Mississippi River Hydromodification .................................................... 3-32

3.3.4.3. Maintenance Dredging and Federal Channels ....................................... 3-32

3.3.4.4. Coastal Restoration Programs ................................................................ 3-32

3.3.5. Natural Events and Processes .................................................................................. 3-33

3.3.6. Non-OCS Oil- and Gas-Related Oil Spills .............................................................. 3-33

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

4.1. Proposed Western Planning Area Lease Sale 248 ................................................................... 4-3

4.1.1. Alternative A—The Proposed Action ....................................................................... 4-9

4.1.1.1. Air Quality ............................................................................................... 4-9

4.1.1.2. Water Quality ......................................................................................... 4-12

4.1.1.2.1. Coastal Waters ..................................................................... 4-12

4.1.1.2.2. Offshore Waters .................................................................. 4-14

4.1.1.3. Coastal Barrier Beaches and Associated Dunes ..................................... 4-18

4.1.1.4. Wetlands ................................................................................................. 4-22

4.1.1.5. Seagrass Communities ........................................................................... 4-26

4.1.1.6. Topographic Features ............................................................................. 4-28

4.1.1.7. Sargassum Communities ........................................................................ 4-31

4.1.1.8. Chemosynthetic Deepwater Benthic Communities ................................ 4-33

4.1.1.9. Nonchemosynthetic Deepwater Benthic Communities .......................... 4-37

4.1.1.10. Soft Bottom Benthic Communities ........................................................ 4-41

4.1.1.11. Marine Mammals ................................................................................... 4-43

4.1.1.12. Sea Turtles .............................................................................................. 4-48

4.1.1.13. Diamondback Terrapins ......................................................................... 4-52

4.1.1.14. Coastal and Marine Birds ....................................................................... 4-55

4.1.1.15. Fish Resources and Essential Fish Habitat ............................................. 4-60

4.1.1.16. Commercial Fisheries............................................................................. 4-63

4.1.1.17. Recreational Fishing............................................................................... 4-66

4.1.1.18. Recreational Resources .......................................................................... 4-69

4.1.1.19. Archaeological Resources ...................................................................... 4-71

4.1.1.19.1. Historic Archaeological Resources ..................................... 4-71

4.1.1.19.2. Prehistoric Archaeological Resources ................................. 4-74

4.1.1.20. Human Resources and Land Use ........................................................... 4-77

4.1.1.20.1. Land Use and Coastal Infrastructure ................................... 4-77

4.1.1.20.2. Demographics...................................................................... 4-81

4.1.1.20.3. Economic Factors ................................................................ 4-83

4.1.1.20.4. Environmental Justice ......................................................... 4-86

4.1.1.21. Species Considered due to U.S. Fish and Wildlife Concerns ................ 4-90
xviii Western Planning Area Lease Sale 248 Supplemental EIS

4.1.2. Alternative B—Exclude the Unleased Blocks Subject to the Topographic 

Features Stipulation ................................................................................................. 4-92

4.1.3. Alternative C—No Action....................................................................................... 4-95

4.2. Unavoidable Adverse Impacts of the Proposed Action ......................................................... 4-97

4.3. Irreversible and Irretrievable Commitment of Resources ...................................................... 4-99

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

Maintenance and Enhancement of Long-term Productivity ................................................ 4-100

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

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

5.2. Call for Information and Notice of Intent to Prepare a Supplemental EIS .............................. 5-3

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

5.3.1. Summary of Comments Received in Response to the Call for Information ............. 5-3

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

5.3.3. Additional Scoping Opportunities ............................................................................. 5-5

5.3.4. Cooperating Agency .................................................................................................. 5-5

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

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

5.6. Endangered Species Act........................................................................................................... 5-8

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

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

5.9. Government-to-Government .................................................................................................. 5-10

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

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

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

FIGURES ......................................................................................................................................... Figures-3 

TABLES ........................................................................................................................................... Tables-3 

APPENDIX A. CATASTROPHIC SPILL EVENT ANALYSIS: HIGH-VOLUME, 

EXTENDED-DURATION OIL SPILL RESULTING FROM LOSS OF 

WELL CONTROL ON THE GULF OF MEXICO OUTER CONTINENTAL 

SHELF ......................................................................................................................... A-iii

KEYWORD INDEX ................................................................................................................... Keywords-3 
List of Figures xix

LIST OF FIGURES

Page

Figure 1-1. Gulf of Mexico Planning Areas, Proposed WPA Lease Sale Area, and Locations of 

Major Cities. .............................................................................................................. Figures-3

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

Figure 2-2. Military Warning Areas and Eglin Water Test Areas in the Gulf of Mexico. ........... Figures-5

Figure 3-1. Offshore Subareas in the Gulf of Mexico. ................................................................. Figures-6

List of Tables xxi

LIST OF TABLES

Page

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

Table 3-2 Offshore Scenario Information Related to a Typical Lease Sale in the Western 

Planning Area ................................................................................................................ Tables-4

Table 3-3 Offshore Scenario Information Related to OCS Program Activities in the Gulf of 

Mexico (WPA, CPA, and EPA) for 2012-2051 ............................................................ Tables-5

Table 3-4 Offshore Scenario Information Related to OCS Program Activities in the Western 

Planning Area for 2012-2051 ........................................................................................ Tables-6

Table 3-5 Annual Volume of Produced Water Discharged by Depth (millions of bbl) ................ Tables-7

Table 4-1 Unusual Mortality Event Cetacean Data for the Northern Gulf of Mexico .................. Tables-7

Table 4-2 Number of Angler Trips in 2009-2014 .......................................................................... Tables-8

Table 4-3 Top Species Landed by Recreational Fishermen .......................................................... Tables-9

Table 4-5 Demographic and Employment Baseline Conditions in 2050 in all Economic 

Impact Areas................................................................................................................ Tables-13

Table 4-6 Sales Volumes, Sales Values, and Revenues .............................................................. Tables-16

Abbreviations and Acronyms xxiii

ABBREVIATIONS AND ACRONYMS

°C degree Celsius

°F degree Fahrenheit

2012-2017 WPA/CPA Gulf of Mexico OCS Oil and Gas Lease Sales: 2012-2017; 

Multisale EIS Western Planning Area Lease Sales 229, 233, 238, 246, and 248; 

Central Planning Area Lease Sales 227, 231, 235, 241, and 247; 

Final Environmental Impact Statement; Volumes I-III

2D two dimensional 

3D three dimensional 

ac acre

Agreement Agreement between the United States of America and the United

Mexican States Concerning Transboundary Hydrocarbon Reservoirs 

in the Gulf of Mexico 

AL Alabama

API American Petroleum Institute

ASLM Assistant Secretary of the Interior for Land and Minerals

bbl barrel

BBO billion barrels of oil

BOEM Bureau of Ocean Energy Management

BOEMRE Bureau of Ocean Energy Management, Regulation and Enforcement

BOP blowout preventer 

BSEE Bureau of Safety and Environmental Enforcement 

Call Call for Information

CD Consistency Determination

CEQ Council on Environmental Quality 

CEWAF chemically enhanced (dispersed) water-accommodated fractions

CFR Code of Federal Regulations 

CG Coast Guard (also: USCG)

CH4 methane 

CMP Coastal Management Program

CO carbon monoxide 

CO2 carbon dioxide 

COE Corps of Engineers (U.S. Army) 

CPA Central Planning Area

CPA 235/241/247 Gulf of Mexico OCS Oil and Gas Lease Sales: 2015-2017; 

Supplemental EIS Central Planning Area Lease Sales 235, 241, and 247; 

Final Supplemental Environmental Impact Statement

CSA Continental Shelf Associates

CYP1A cytochrome P-4501A 

CZMA Coastal Zone Management Act

dB decibel

DOI Department of the Interior (U.S.) (also: USDOI) 

EFH essential fish habitat

e.g. for example 

EIA Economic Impact Area

EIS environmental impact statement

EPA Eastern Planning Area 

EPA 225/226 EIS Gulf of Mexico OCS Oil and Gas Lease Sales: 2014 and 2016; 

 Eastern Planning Area Lease Sales 225 and 226; 

 Final Environmental Impact Statement 

EPAct Energy Policy Act of 2005 

ERMA Environmental Response Management Application 

ESA Endangered Species Act of 1973 

et al. and others 
xxiv Western Planning Area Lease Sale 248 Supplemental EIS

et seq. and the following 

Five-Year Program Proposed Final Outer Continental Shelf Oil & Gas Leasing Program: 

 2012-2017 

Five-Year Program EIS Outer Continental Shelf Oil and Gas Leasing Program: 2012-2017, 

 Final Environmental Impact Statement

FL Florida 

FR Federal Register

ft feet

FWS Fish and Wildlife Service 

G&G geological and geophysical

g gram

GAP General Activities Plan

GIS Geographic Information System 

GMFMC Gulf of Mexico Fishery Management Council 

GOM Gulf of Mexico 

H2S hydrogen sulfide 

i.e. that is

km kilometer

LA Louisiana 

LNG liquefied natural gas

m meter

MAG-PLAN MMS Alaska-GOM Model Using IMPLAN

MARAD Maritime Administration (U.S. Department of Transportation) 

Mcf thousand cubic feet

mi mile

MMbbl million barrels

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MODU mobile offshore drilling unit 

MS Mississippi

N2O nitrous oxide

NAAQS National Ambient Air Quality Standards

NASA National Aeronautics and Space Administration

NCP National Oil and Hazardous Substances Pollution Contingency Plan 

NEPA National Environmental Policy Act

NGL natural gas liquids 

NMFS National Marine Fisheries Service

nmi nautical-mile

NO2 nitrogen dioxide 

NOx nitrogen oxides 

NOA Notice of Availability

NOAA National Oceanic and Atmospheric Administration

NOI Notice of Intent to Prepare an EIS

NOS National Ocean Service

NPDES National Pollutant and Discharge Elimination System

NRC National Research Council

NRDA Natural Resource Damage Assessment

NTL Notice to Lessees and Operators

OCS Outer Continental Shelf

OCSLA Outer Continental Shelf Lands Act 

ODMDS ocean dredged-material disposal site

OSAT Operational Science Advisory Team

OSHA Occupational Safety and Health Administration 

OSRA Oil Spill Risk Analysis

OSRP oil-spill response plan

OSV offshore supply vessel
Abbreviations and Acronyms xxv 

P.L. Public Law

PAH polycyclic aromatic hydrocarbons 

PM particulate matter

PM2.5 particulate matter less than or equal to 2.5 μm 

PM10 particulate matter less than or equal to 10 μm 

PSD Prevention of Significant Deterioration

ROD Record of Decision

SAP Site Assessment Plan

SBF synthetic-based fluid

Secretary Secretary of the Interior

SMART Special Monitoring of Applied Response Technologies 

SO2 sulphur dioxide 

SOx sulphur oxides 

Stat. Statute

Tcf trillion cubic feet

Trustee Council Natural Resource Damage Assessment Trustee Council

TX Texas

U.S. United States

U.S.C. United States Code

UME unusual mortality event 

USCG U.S. Coast Guard (also: CG)

USDHS U.S. Department of Homeland Security

USDOC U.S. Department of Commerce 

USDOE U.S. Department of Energy 

USDOI U.S. Department of the Interior (also: DOI) 

USDOT U.S. Department of Transportation 

USEPA U.S. Environmental Protection Agency 

USGS U.S. Geological Survey

VGP Vessel General Permit

VOC volatile organic compound

VSP vertical seismic profiling

W. west

WAF water-accommodated fraction

WPA Western Planning Area

WPA 233/CPA 231 Gulf of Mexico OCS Oil and Gas Lease Sales: 2013-2014; 

Supplemental EIS Western Planning Area Lease Sale 233;

Central Planning Area Lease Sale 231; 

Final Supplemental Environmental Impact Statement 

WPA 238/246/248 Gulf of Mexico OCS Oil and Gas Lease Sales: 2014-2016; 

Supplemental EIS Western Planning Area Lease Sales 238, 246, and 248; 

Final Supplemental Environmental Impact Statement

WPA 246/248 Gulf of Mexico OCS Oil and Gas Lease Sales: 2015 and 2016; 

Supplemental EIS Western Planning Area Lease Sales 246 and 248; 

Final Supplemental Environmental Impact Statement 

Conversion Chart xxvii

CONVERSION CHART

To convert from To Multiply by

centimeter (cm) inch (in) 0.3937

millimeter (mm) inch (in) 0.03937

meter (m) foot (ft) 3.281

meter2 (m2) foot2 (ft2) 10.76

meter2 (m2) yard2 (yd2) 1.196

meter2 (m2) acre (ac) 0.0002471

meter3 (m3) foot3 (ft3) 35.31

meter3 (m3) yard3 (yd3) 1.308

kilometer (km) mile (mi) 0.6214

kilometer2 (km2) mile2 (mi2) 0.3861

hectare (ha) acre (ac) 2.47

liter (L) gallons (gal) 0.2642

degree Celsius (°C) degree Fahrenheit (°F) °F = (1.8 x °C) + 32

1 barrel (bbl) = 42 gal = 158.9 L = approximately 0.1428 metric tons

1 nautical mile (nmi) = 1.15 mi (1.85 km) or 6,076 ft (1,852 m) 

tonnes = 1 long ton or 2,240 pounds

CHAPTER 1 

THE PROPOSED ACTION

The Proposed Action 1-3 

1. THE PROPOSED ACTION

1.1. PURPOSE OF AND NEED FOR THE PROPOSED ACTION

The proposed Federal action addressed in this Supplemental Environmental Impact Statement (EIS) is 

to offer for lease certain Outer Continental Shelf (OCS) blocks located in the Western Planning Area 

(WPA) of the Gulf of Mexico (GOM) (Figure 1-1). Under the Proposed Final Outer Continental Shelf 

Oil & Gas Leasing Program: 2012-2017 (Five-Year Program) (USDOI, BOEM, 2012a), proposed WPA 

Lease Sale 248 is tentatively scheduled to be held in August 2016. The proposed Federal action is to 

offer for lease those areas that may contain economically recoverable oil and gas resources in accordance 

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

1331 et seq.). 

The purpose of the proposed action is to further the orderly development of OCS oil and gas 

resources. The proposed WPA lease sale 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. 

Under the OCLSA, for each proposed lease sale in the Five-Year Program, the Bureau of Ocean Energy 

Management (BOEM) makes individual decisions on whether and how to proceed with a proposed lease 

sale. This Supplemental EIS will be used by BOEM to make an informed decision on proposed WPA 

Lease Sale 248. 

The United States (U.S.) still has a great demand for oil and gas resources and, therefore, there is a 

need for continued oil and gas resource development. The WPA, together with the Central Planning Area 

(CPA) of the GOM, constitutes one of the world’s major oil- and gas-producing areas and has proved a 

steady and reliable source of crude oil and natural gas for more than 50 years. Oil serves as the feedstock 

for liquid hydrocarbon products, including gasoline, aviation and diesel fuel, and various petrochemicals. 

Oil from the WPA would help reduce the Nation’s dependence on foreign oil imports. The U.S. 

consumed 19.03 million barrels (MMbbl) of oil per day (USDOE, Energy Information Administration, 

2015a) and 25.26 trillion cubic feet (Tcf) of natural gas per day (USDOE, Energy Information 

Administration, 2015b) in 2014. The Energy Information Administration projects the total U.S. 

consumption of liquid fuels, including fossil fuels and biofuels, to fall slightly from 19.06 MMbbl per day 

in 2014 to 18.73 MMbbl by 2040 (USDOE, Energy Information Administration, 2015c). The Energy 

Information Administration also projects the total U.S. consumption of natural gas to rise from 25.26 Tcf 

in 2014 to 31.48 Tcf by 2040 (USDOE, Energy Information Administration, 2015b). The U.S. net 

imports of natural gas accounted for 1.36 Tcf in 2014 and are projected to decrease to 0.04 Tcf by 2017 

(USDOE, Energy Information Administration, 2015b). Altogether, net imports of crude oil and 

petroleum products accounted for 28.7 percent of our total petroleum consumption in 2014 and are 

projected to increase to 32.2 percent by 2040 (USDOE, Energy Information Administration, 2015d). The 

U.S. crude oil and petroleum products imports stood at 9.2 MMbbl per day in 2014 (USDOE, Energy 

Information Administration, 2015e). Exports totaled 2.9 MMbbl per day in 2014, mainly in the form of 

distillate fuel oil, petroleum coke, and residual fuel oil (USDOE, Energy Information Administration, 

2015f). The U.S. had net imports of 6.3MMbbl per day. The net exports of natural gas are projected to 

be 0.66 Tcf in 2018 and rise to 5.78 Tcf in 2040 (USDOE, Energy Information Administration, 2015b). 

In 2014, the Nation’s biggest supplier of crude oil and petroleum-product imports was Canada (37%), 

with countries in the Persian Gulf being the second largest source (20%) (USDOE, Energy Information 

Administration, 2015e). In 2014, the Nation’s biggest supplier of natural gas was Canada (98%), with 

Trinidad being the second largest source (1.6%) (USDOE, Energy Information Administration, 2014g). 

Oil produced from the WPA would reduce the environmental risks associated with transoceanic oil 

tankering from sources overseas. In addition, natural gas is not easily transported, making domestic 

production especially desirable. The need for domestic natural gas reserves is also based upon the use of 

gas as an environmentally preferable alternative to oil or coal for generating electricity.

The Secretary of the Interior (Secretary) has designated BOEM as the administrative agency 

responsible for the mineral leasing of submerged OCS lands and for the supervision of most offshore 

operations after lease issuance. BOEM is responsible for managing development of the Nation’s offshore 

resources in an environmentally and economically responsible way. The functions of BOEM on the OCS 

include leasing; the regulation of exploration, development, and production activities; plan 

administration; environmental studies; NEPA analysis; hydrocarbon resource evaluation; economic 
1-4 Western Planning Area Lease Sale 248 Supplemental EIS

analysis; and the renewable energy program. In addition, the Secretary has designated the Bureau of 

Safety and Environmental Enforcement (BSEE) as being responsible for enforcing safety and 

environmental regulations. The functions of BSEE include all field operations, including permitting and 

research, inspections, offshore regulatory programs, oil-spill response, and training and environmental 

compliance functions. 

Other Pertinent Environmental Reviews or Documentation

This Supplemental EIS supplements, tiers from, and incorporates by reference all of the relevant 

analyses from the Multisale and Supplemental EISs listed below, i.e., the “prior 2012-2017 Gulf of 

Mexico EISs.” 

• July 2012 – Gulf of Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western 

Planning Area Lease Sales 229, 233, 238, 246, and 248; Central Planning Area 

Lease Sales 227, 231, 235, 241, and 247, Final Environmental Impact Statement

(2012-2017 WPA/CPA Multisale EIS) (USDOI, BOEM, 2012b) 

• April 2013 – Gulf of Mexico OCS Oil and Gas Lease Sales: 2013-2014; Western 

Planning Area Lease Sale 233; Central Planning Area Lease Sale 231, Final 

Supplemental Environmental Impact Statement (WPA 233/CPA 231 Supplemental 

EIS) (USDOI, BOEM, 2013a) 

• March 2014 – Gulf of Mexico OCS Oil and Gas Lease Sales: 2014-2016; Western 

Planning Area Lease Sales 238, 246, and 248, Final Supplemental Environmental 

Impact Statement (WPA 238/246/248 Supplemental EIS) (USDOI, BOEM, 2014a) 

• March 2015 – Gulf of Mexico OCS Oil and Gas Lease Sales: 2015 and 2016; 

Western Planning Area Lease Sales 246 and 248, Final Supplemental Environmental 

Impact Statement (WPA 246/248 Supplemental EIS) (USDOI, BOEM, 2015) 

The NEPA documents listed above are part of the Five-Year Program, and their relationship (tiering 

and supplementing) and timing with their respective proposed actions (lease sales) are illustrated in the 

figure below.
The Proposed Action 1-5 

Each subsequent Supplemental EIS, regardless of the planning area, updates the potential 

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

GOM in Chapter 4.1.1 and updates the cumulative impacts from the most recent Supplemental EIS. 

Within each specific planning area, the baseline conditions for that planning area are updated to reflect 

the most recent technical and scientific information available.

This Supplemental EIS focuses on updating the baseline conditions and potential environmental 

effects of oil and natural gas leasing, exploration, development, and production in the WPA since 

publication of the prior 2012-2017 Gulf of Mexico EISs. This Supplemental EIS analyzes the potential 

impacts of the WPA proposed action on the marine, coastal, and human environments. This 

Supplemental EIS will also assist decisionmakers in making informed, future decisions regarding the 

approval of operations, as well as leasing. At the completion of the NEPA process, a decision will be 

made for proposed WPA Lease Sale 248. The analysis in this Supplemental EIS also focuses on the 

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

the areas identified through the Area Identification (Area ID) procedure as the proposed lease sale area. 

In addition to the No Action alternative (i.e., cancel the proposed lease sale), other alternatives may be 

considered for the proposed WPA lease sale, such as deferring certain areas from the proposed lease sale.

1.2. DESCRIPTION OF THE PROPOSED ACTION

The proposed action is the next oil and gas lease sale in the WPA as scheduled in the Five-Year 

Program. Proposed WPA Lease Sale 248 is tentatively scheduled to be held in August 2016. The 

analyses contained in this Supplemental EIS examine impacts from a single, typical WPA lease sale.

The proposed WPA lease sale area encompasses virtually all of the WPA’s approximately 

28.58 million acres (ac). This area begins 3 marine leagues (9 nautical miles [nmi]; 10.36 miles [mi]; 

16.67 kilometers [km]) offshore Texas and extends seaward to the limits of the United States’ jurisdiction 

over the continental shelf (often the Exclusive Economic Zone) in water depths up to approximately 

3,346 meters (m) (10,978 feet [ft]) (Figure 1-1). As of July 2015, approximately 22 million ac of the 
1-6 Western Planning Area Lease Sale 248 Supplemental EIS

proposed WPA lease sale area are currently unleased. This information is updated monthly and can be 

found on BOEM’s website at http://www.boem.gov/Gulf-of-Mexico-Region-Lease-Map/. 

The estimated amount of resources projected to be developed as a result of a single, typical lease sale 

(e.g., proposed WPA Lease Sale 248) is 0.116-0.200 billion barrels of oil (BBO) and 0.538-0.938 trillion 

cubic feet (Tcf) of gas. The proposed WPA lease sale includes proposed lease stipulations designed to 

reduce environmental risks; these stipulations are discussed in Chapter 2.3.1.3 of this Supplemental EIS

and in Chapter 2.3.1.3 of the prior 2012-2017 Gulf of Mexico EISs. 

1.3. REGULATORY FRAMEWORK

Federal laws mandate the OCS leasing program (i.e., the OCSLA) and the environmental review 

process (i.e., NEPA). Several Federal regulations establish specific consultation and coordination

processes with Federal, State, and local agencies (e.g., Coastal Zone Management Act, Endangered 

Species Act, the Magnuson-Stevens 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 applicable Federal, State, and local laws and regulations. The major applicable Federal 

laws, regulations, and Executive Orders are listed below.

Regulation, Law, and Executive Order Citation

Outer Continental Shelf Lands Act 43 U.S.C. §§ 1331 et seq.

National Environmental Policy Act of 1969 42 U.S.C. §§ 4321-4347

40 CFR §§ 1500-1508

Coastal Zone Management Act of 1972 16 U.S.C. §§ 1451 et seq.

15 CFR part 930

Endangered Species Act of 1973 16 U.S.C. §§ 1531 et seq.

Magnuson-Stevens Fishery Conservation and Management Act 16 U.S.C. §§ 1251 et seq.

Essential Fish Habitat Consultation (in 1996 reauthorization of the 

Magnuson-Stevens Fishery Conservation and Management Act)

P.L. 94-265

16 U.S.C. §§ 1801-1891

50 CFR part 600 subpart K

Marine Mammal Protection Act 16 U.S.C. §§ 1361 et seq.

Clean Air Act 42 U.S.C. §§ 7401 et seq.

40 CFR part 55

Clean Water Act 33 U.S.C. §§ 1251 et seq.

Harmful Algal Bloom and Hypoxia Research and Control Act P.L. 105-383

Oil Pollution Act of 1990 33 U.S.C. §§ 2701 et seq.

Executive Order 12777

Comprehensive Environmental Response, Compensation, and Liability 

Act of 1980 42 U.S.C. §§ 9601 et seq. 

Resource Conservation and Recovery Act 42 U.S.C. §§ 6901 et seq.

Marine Plastic Pollution Research and Control Act 33 U.S.C. §§ 1901 et seq.

National Fishing Enhancement Act of 1984 33 U.S.C. §§ 2601 et seq.

Fishermen’s Contingency Fund 43 U.S.C. §§ 1841-1846

Ports and Waterways Safety Act of 1972 33 U.S.C. §§ 1223 et seq.

Marine and Estuarine Protection Acts 33 U.S.C. §§ 1401 et seq.

Marine Protection, Research, and Sanctuaries Act of 1972 P.L. 92-532

National Estuarine Research Reserves 16 U.S.C. § 1461, Section 315

National Estuary Program P.L. 100-4

Coastal Barrier Resources Act 16 U.S.C. §§ 3501 et seq.

National Historic Preservation Act 54 U.S.C. §§ 300101 et seq.

Rivers and Harbors Act of 1899 33 U.S.C. §§ 401 et seq.

Occupational Safety and Health Act of 1970 29 U.S.C. §§ 651 et seq.
The Proposed Action 1-7 

Regulation, Law, and Executive Order Citation

Energy Policy Act of 2005 P.L. 109-58

Gulf of Mexico Energy Security Act of 2006 P.L. 109-432

Marine Debris Research, Prevention, and Reduction Act P.L. 109-449

American Indian Religious Freedom Act of 1978 P.L. 95-341

42 U.S.C. §§ 1996 and 1996a

Migratory Bird Treaty Act of 1918 16 U.S.C. §§ 703 et seq.

Submerged Lands Act of 1953 43 U.S.C. §§ 1301 et seq.

49 U.S.C. 44718: Structures Interfering with Air Commerce 49 U.S.C. § 44718

Marking of Obstructions 14 U.S.C. § 86

Wilderness Act of 1964

P.L. 88-577

16 U.S.C. §§ 1131-1136

78 Stat. 890

Toxic Substances Control Act

P.L. 94-469

15 U.S.C. §§ 2601-2697

Stat. 2003

Bald Eagle Protection Act of 1940 P.L. 86-70

16 U.S.C. §§ 668-668d

Executive Order 11988: Floodplain Management 42 FR 26951 (1977); amended by 

Executive Order 12148 (7/20/79)

Executive Order 11990: Protection of Wetlands 42 FR 26961 (1977); amended by 

Executive Order 12608 (9/9/87)

Executive Order 12114: Environmental Effects Abroad 44 FR 1957 (1979)

Executive Order 12898: Environmental Justice 59 FR 5517 (1994)

Executive Order 13007: Indian Sacred Sites 61 FR 26771-26772 (1996)

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

Executive Order 13175: Consultation and Coordination with Indian 

Tribal Governments 65 FR 67249-67252 (2000)

Executive Order 13186: Responsibilities of Federal Agencies to 

Protect Migratory Birds 66 FR 3853 (2001)

1.3.1. Recent BOEM/BSEE Rule Changes

In light of the Deepwater Horizon explosion, oil spill, and response, the Federal Government, along 

with industry, increased their rules and safety measures related to oil-spill prevention, containment, and 

response. Additionally, the Federal Government and industry have increased their research and reform in 

response to the Deepwater Horizon explosion, oil spill, and response through government-funded 

research, industry-funded research, and joint partnerships. These joint partnerships are often between 

government agencies, industry, and nongovernmental organizations. For more information about the 

BOEM/BSEE rule changes prior to this Supplemental EIS, refer to Chapters 1.3 and 1.5 of the prior 

2012-2017 Gulf of Mexico EISs. 

1.3.1.1. Recent and Ongoing Regulatory Reform and Government-Sponsored 

Research

BOEM and BSEE have already instituted regulatory reforms responsive to many of the 

recommendations expressed in the various reports prepared following the Deepwater Horizon explosion, 

oil spill, and response. To date, regulatory reform has occurred through both prescriptive and 

performance-based regulation and guidance, as well as OCS safety and environmental protection 

requirements, as described in the 2012-2017 WPA/CPA Multisale EIS. The reforms strengthen the 

requirements for all aspects of OCS operations. Ongoing reform and research endeavors to improve 

workplace safety and to strengthen oil-spill prevention planning, containment, and response are described 
1-8 Western Planning Area Lease Sale 248 Supplemental EIS

in detail in Chapter 1.3.1.2 of the 2012-2017 WPA/CPA Multisale EIS, with updated information in 

Chapter 1.3.2.2 of the WPA 233/CPA 231 Supplemental EIS and Chapter 1.3.1.1 of the WPA 

238/246/248 Supplemental EIS and WPA 246/248 Supplemental EIS. Since publication of the WPA 

246/248 Supplemental EIS, no substantive rule changes have been implemented that would affect 

potential environmental impacts from OCS oil- and gas-related activities in the Gulf of Mexico. 

However, new and modified Notices to Lessees and Operators (NTLs) and other policies applicable to 

OCS oil and gas operations in the Gulf of Mexico are summarized below. A detailed listing of the current 

Gulf of Mexico OCS Region NTLs is available through BOEM’s Gulf of Mexico OCS Region’s website 

at http://boem.gov/Regulations/Notices-Letters-and-Information-to-Lessees-and-Operators.aspx or 

through the Region’s Public Information Office at 504-736-2519 or 1-800-200-GULF.

NTL 2015-BOEM-N01, “Information Requirements for Exploration Plans, Development 

and Production Plans, and Development Operations Coordination Documents on the OCS 

for Worst Case Discharge and Blowout Scenarios” 

This NTL supersedes NTL 2010-N06 (effective date June 18, 2010) and updates the information 

requirements for exploration plans (EPs) and also for development operations coordination documents 

(DOCDs) or development and production plans (DPPs) if the plans include any drilling activities. This 

NTL is accompanied by a Frequently Asked Questions Information Sheet that can also be found on 

BOEM’s website.

Frequently Asked Questions for NTL 2015-BOEM-N01, “Information Requirements for 

Exploration Plans, Development and Production Plans, and Development Operations 

Coordination Documents on the OCS for Worst Case Discharge and Blowout Scenarios”

This Frequently Asked Questions Information Sheet accompanies NTL 2015-BOEM-N01 and 

provides responses to 38 frequently asked questions about requirements for EPs, DOCDs, and DPPs for 

worst-case discharge and blowout scenarios. It also supersedes the Frequently Asked Questions 

Information Sheet for NTL 2010-N06, “Information Requirements for Exploration Plans, Development 

and Production Plans, and Development Operations Coordination Documents on the OCS for Worst Case

Discharge and Blowout Scenarios.”

NTL 2015-BOEM-N02, “Elimination of Expiration Dates on Certain Notices to Lessees and 

Operators Pending Review and Reissuance”

This national NTL eliminates the expiration dates on certain existing NTLs published on BOEM’s

website. This NTL also clarifies that, until BOEM revises, reissues, or withdraws the published NTLs, 

they will continue to apply regardless of any stated expiration dates. 

NTL 2014-BOEM-G04, “Military Warning and Water Test Areas” 

This NTL is issued pursuant to 30 CFR § 550.103 and provides links to the addresses and telephone 

numbers of the individual command headquarters for the military warning and water test areas in the Gulf 

of Mexico. This NTL updates BOEM’s contact information and replaces NTL 2009-G06. 

NTL 2014-BSEE-N03, “eWell Permitting and Reporting System” 

This NTL supersedes NTL 2007-G15. This NTL updates the information and guidance about 

obtaining access to the eWell Permitting and Reporting System (eWell) and attaches an updated eWell 

Permitting and Reporting System Application Manual. This NTL also announces the availability of the 

electronic reporting features in eWell to the Alaska and Pacific OCS Regions.

NTL 2014-BSEE-G03, “Release of Well Data and Information” 

This NTL supersedes NTL 2008-G22 and provides schedules for the release of well data and 

information that are submitted to BSEE as described in NTL 2010-BSEE-G02. 
The Proposed Action 1-9 

NTL 2014-BSEE-G04, “New Address and Phone Numbers for the Lake Jackson District 

Office”

This NTL provides the new address and contact information for the Lake Jackson District Office.

NTL 2014-BSEE-G05, “Contact with District Offices, Pipeline Section, and Resource 

Conservation Section Outside Regular Work Hours” 

This NTL is issued pursuant to 30 CFR § 250.103 and supersedes NTL 2007-G12. This NTL updates 

the New Orleans, Houma, Lake Charles, and Lake Jackson District Offices’ addresses and also the 

Pipeline Section address for BSEE’s Gulf of Mexico OCS Region. This NTL also restates the after-hours 

flaring/venting contact information for the Resource Conservation Section contained in NTL 2012-BSEEN04, “Flaring and Venting Requests,” in order to consolidate BSEE’s Gulf of Mexico OCS Region’s

after-hours contacts into a single NTL. 

NTL 2014-BSEE-G06, “Lessee and Operator Refueling Requirements for BSEEContracted Helicopters”

This NTL provides guidance on BSEE’s interpretation of 30 CFR § 250.132(a)(2), which requires 

lessees and operators to provide helicopter landing sites and refueling facilities to helicopters that BSEE 

uses to regulate offshore operations.

NTL 2015-BSEE-N01, “Performance Measures for OCS Operators and Form BSEE-0131”

This NTL supersedes NTL 2014-BSEE-N02 and provides lessees information about when and how to 

file their performance measures data with the Bureau.

Gulf of Mexico Environmental Studies Program

The Division of Environmental Sciences manages the Environmental Studies Program for BOEM. 

The Environmental Studies Program develops, conducts, and oversees world-class scientific research 

specifically to inform policy decisions regarding the development of OCS energy and mineral resources. 

Research covers physical oceanography, atmospheric sciences, biology, protected species, social sciences 

and economics, submerged cultural resources, and environmental fates and effects. BOEM is a leading 

contributor to the growing body of scientific knowledge about the Nation’s marine and coastal 

environment. Studies published by the Environmental Studies Program, Gulf of Mexico OCS Region, 

since publication of the WPA 246/248 Supplemental EIS are shown in the table below. For a list of 

studies published by the Environmental Studies Program, Gulf of Mexico OCS Region, prior to those 

listed below (i.e., 2006-2013), refer to Appendix E of the WPA 238/246/248 Supplemental EIS and 

Chapter 1 of the WPA 246/248 Supplemental EIS. 

Publications of the Environmental Studies Program, Gulf of Mexico OCS Region, 

Since Publication of the WPA 246/248 Supplemental EIS

Study Number Title

BOEM 2014-609

BOEM 2014-610

BOEM 2014-611

BOEM 2014-612

Gulf Coast Communities and the Fabrication and Shipbuilding Industry: 

A Comparative Community Study

Volume I: Historical Overview and Statistical Model

Volume II: Community Profiles

Volume III: Technical Papers

Volume IV: Appendices

BOEM 2014-660 Measuring County-Level Tourism and Recreation in the Gulf of Mexico Region: Data, 

Methods, and Estimates
1-10 Western Planning Area Lease Sale 248 Supplemental EIS

BOEM 2014-661 Assessing the Impacts of the Deepwater Horizon Oil Spill on Tourism in the Gulf of 

Mexico Region

BOEM 2014-666 Year 2011 Gulfwide Emission Inventory Study

BOEM 2014-669 Measurements in the Yucatan-Campeche Area in Support of the Loop Current

Dynamics Study

BOEM 2014-771 Current-Topography Interaction and Its Influence on Water Quality and Contaminant 

Transport over Shelf-Edge Banks

BOEM 2014-1003 Intra-Americas Sea Nowcast/Forecast System Ocean Reanalysis to Support 

Improvement of Oil-Spill Risk Analysis in the Gulf of Mexico by Multi-Model Approach

BOEM 2015-003 Assessing Impacts of OCS Activities on Public Infrastructure, Services, and Population 

in Coastal Communities Following Hurricanes Katrina and Rita

BOEM 2015-004 Digital Conversion of Dive Video from Fifteen Dive Seasons

BOEM 2015-005 New Invasive Species Colonizing Energy Platforms in the Northern Gulf of Mexico: 

Verification and Examination of Spread

BOEM 2015-012

Understanding the Habitat Value and Function of Shoal/Ridge/Trough Complexes to 

Fish and Fisheries on the Atlantic and Gulf of Mexico Outer Continental Shelf: Final 

Literature Synthesis and Gap Analysis

1.3.1.2. Recent and Ongoing Industry Reform and Research

Since the preparation of the WPA 246/248 Supplemental EIS, the oil and gas industry and 

engineering trade groups have continued to prepare new standards and develop best practices for the safe 

and environmentally responsible development of OCS oil and gas. As an example, the American 

Petroleum Institute (API) has produced several Recommended Practices and Standards that have become 

part of State and Federal regulations. In July 2014, API completed Recommended Practice 17W, 

“Recommended Practice for Subsea Capping Stacks” (API, 2014a). This recommended practice covers 

the design, fabrication, and operation of new subsea capping stacks, and it can be used to improve 

existing equipment. The API’s standards are designed to assist industry professionals to improve the 

efficiency and cost effectiveness of their operations, comply with legislative and regulatory requirements, 

safeguard health, and protect the environment. The API’s Recommended Practices and technical 

information can be found on API’s website (API, 2014b).

1.4. PRELEASE PROCESS

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

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

interest in the OCS Program an opportunity to provide input on the significant issues and potential impact 

of the proposed action, alternatives, and mitigating measures to reduce or eliminate impacts. In addition, 

scoping provides BOEM an opportunity to update the Gulf of Mexico OCS Region’s environmental and 

socioeconomic information base. BOEM conducted early coordination with appropriate Federal, State, 

and local government agencies; federally recognized Indian Tribes; nongovernmental organizations; and 

other concerned parties to discuss and coordinate the prelease process for proposed WPA Lease Sale 248 

and for this Supplemental EIS. While scoping is an ongoing process, it officially commenced on 

March 30, 2015, with the publication of the Notice of Intent to Prepare a Supplemental EIS (NOI) in the

Federal Register (2015a). Additional public notices were distributed via local newspapers, the U.S. 

Postal Service, and the Internet. A 30-day comment period was provided; it closed on April 28, 2015. 

Federal, State, and local governments, and federally recognized Indian Tribes, as well as other interested 

parties were invited to send written comments to the Gulf of Mexico OCS Region on the scope of this 

Supplemental EIS. Comments were received in response to the NOI from State government agencies, 

federally recognized Indian Tribes, industry, and the general public on the scope of this Supplemental 

EIS, significant issues that should be addressed, alternatives that should be considered, and mitigating 
The Proposed Action 1-11

measures. All scoping comments received were considered in the preparation of the Draft Supplemental 

EIS. The comments are summarized in Chapter 5.3, “Development of the Draft Supplemental EIS.”

In addition to BOEM’s consideration of scoping comments received for this Supplemental EIS, this 

document tiers from and incorporates by reference all of the relevant scoping comments and responses to 

the comments from the prior 2012-2017 Gulf of Mexico EISs. A summary of scoping comments 

incorporated by reference can be found in Chapter 5.3, “Development of the Draft Supplemental EIS,” of 

the prior 2012-2017 Gulf of Mexico EISs. 

At the beginning of each Five-Year Program, the Gulf of Mexico OCS Region releases an Area 

Identification (Area ID) for each planning area, defining the lease sale areas. On October 4, 2012, BOEM 

released its Area ID decision. The Area ID is an administrative prelease step that describes the 

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

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

NEPA, this Supplemental EIS analyzes the potential impacts of the WPA proposed action on the marine, 

coastal, and human environments. 

BOEM will mail copies of the Draft Supplemental EIS for review and comment to Federal, State, and 

local government agencies; federally recognized Indian Tribes; interest groups; industry; 

nongovernmental organizations; the general public; and local libraries. To initiate the public review and 

comment period on the Draft Supplemental EIS, BOEM will publish a Notice of Availability (NOA) in 

the Federal Register. In addition, public notices will be mailed with the Draft Supplemental EIS and will 

be placed on BOEM’s website (http://www.boem.gov/nepaprocess).

A consistency review will be performed in accordance with the Coastal Zone Management Act 

(CZMA), and a Consistency Determination (CD) will be prepared for each CZMA State prior to the 

proposed WPA lease sale. To prepare the CDs, BOEM reviews each CZMA State’s Coastal Management 

Program (CMP) and analyzes the potential impacts as outlined in this Supplemental EIS, new 

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

analyses, BOEM’s Gulf of Mexico OCS Region’s Regional Director makes an assessment of consistency, 

which is then sent to the CZMA States of Texas and Louisiana for the WPA lease sale. If a CZMA State 

disagrees with the Bureau of Ocean Energy Management’s CD, the CZMA State is required to do the 

following under the CZMA: (1) indicate how BOEM’s presale proposal is inconsistent with the CZMA 

State’s CMP; (2) describe the specific enforceable policies (including citations) that are inconsistent; 

(3) suggest alternative measures to bring BOEM’s proposal into consistency with the CZMA State’s CMP 

and/or 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 not a procedure for 

administrative appeal to the Secretary of Commerce for a Federal CD for presale activities. In the event 

of a disagreement between a Federal agency and the CZMA State’s CMP regarding consistency of the 

proposed lease sale, either BOEM or the CZMA State may request mediation. The regulations provide 

for an opportunity to resolve any differences with the CZMA State, but the CZMA allows BOEM to 

proceed with a proposed lease sale despite any unresolved disagreements if the Federal agency clearly 

describes, in writing, how the activity is consistent to the maximum extent practicable with the CZMA 

State’s CMP.

Proposed WPA Lease Sale 248 is tentatively scheduled for August 2016. BOEM must publish a 

Final Supplemental EIS at least 30 days prior to a decision on whether and/or how to proceed with 

proposed WPA Lease Sale 248. BOEM will publish an NOA for the Final Supplemental EIS in the 

Federal Register and will send copies of the Final Supplemental EIS for review to: Federal, State, and 

local agencies; federally recognized Indian Tribes; interest groups; industry; nongovernmental 

organizations; the general public; and local libraries. In addition, public notices will be mailed with the 

Final Supplemental EIS and will be placed on BOEM’s website (http://www.boem.gov/nepaprocess/). At 

the completion of this Supplemental EIS process, a decision will be made for proposed WPA Lease Sale 

248. 

The Final Supplemental EIS is not a decision document. The Assistant Secretary of the Interior for 

Land and Minerals Management (ASLM) will make a decision on whether to hold the proposed lease sale 

and, if the decision is made to hold the lease sale, then any particulars relevant to the lease sale including, 

but not limited to, the lease sale area and any mitigations will be announced in a Final Notice of Sale 

(NOS). A NEPA Record of Decision (ROD) will memorialize the decision and will identify BOEM’s 

preferred alternative for each lease sale, as well as the environmentally preferable alternative, if different. 

The ROD will summarize the proposed action and the alternatives evaluated in this Supplemental EIS, the 
1-12 Western Planning Area Lease Sale 248 Supplemental EIS

information considered in reaching the decision, and the adopted mitigations. An NOA for the ROD will 

be published in the Federal Register and will be made available on BOEM’s website at 

http://www.boem.gov/nepaprocess. 

A Proposed Notice of Sale (NOS) will become available to the public 4-5 months prior to the 

proposed lease sale. A notice announcing the availability of the Proposed NOS will appear in the Federal 

Register, initiating a 60-day comment period. Comments received will be analyzed during preparation of 

the decision documents that are the basis for the Final NOS, including lease sale configuration and terms 

and conditions. 

If the ASLM decides to hold the proposed lease sale, a Final NOS will be published in the Federal 

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

Measures to Enhance Transparency and Effectiveness in the Leasing and Tiering Process

The following discussion is from the Outer Continental Shelf Oil and Gas Leasing Program: 

2012-2017, Final Environmental Impact Statement (Five-Year Program EIS) (USDOI, BOEM, 2012c) 

and has been incorporated into this Supplemental EIS for information purposes. 

BOEM realizes that each region is different in terms of mineral resources and dependent economies, 

the relative state of infrastructure and support industries, and the sensitivity of ecosystems, environmental 

resources, and communities; and that a leasing strategy needs to be sensitive to those differences, but also 

that it must be consistent with OCSLA principles. BOEM envisions a phased OCSLA process that 

minimizes multiple-use and environmental conflicts to the extent possible during the Five-Year Program 

implementation, that makes lease sale decisions in the context of the best available information, and that 

discloses clear reasons for those decisions, even in the face of uncertainty. This vision is consistent with 

the National Ocean Policy Implementation Plan and related Marine Planning initiatives, all of which 

provide a complementary framework for space-use conflict considerations.

BOEM is committing to several process enhancements to ensure transparency during the phased 

OCSLA and tiered NEPA processes of this Five-Year Program. Although specific approaches to 

implementation may be tailored to the different needs of the Regions and their stakeholders, BOEM is 

determined to improve the effectiveness of the tiering process through the following:

• Alternative and Mitigation Tracking Table. BOEM has established an alternative 

and mitigation tracking table to provide increased visibility into the consideration of 

recommendations for deferrals, mitigations, and alternatives at different stages of the 

leasing process. Beginning with the Five-Year Program EIS, the table tracks the 

lineage and treatment of suggestions for spatial exclusions, temporal deferrals, and/or 

mitigation from the Five-Year Program to the lease sale phase and on to the plan 

phase. This table allows commenters to see how and at what stage of the process 

their concerns are being considered. BOEM will maintain a table that will be 

updated as deferral requests are considered at the lease sale and plan stages, and as 

new requests are made. The alternative and mitigation tracking table has been placed 

on BOEM’s website at http://www.boem.gov/5-year/2012-2017/Tracking-Table/. A 

link to the table will be provided in the lease sale documents and in the annual report, 

which is discussed below.

• Strengthening the Prelease Sale Process. BOEM is taking a number of steps to 

enhance opportunities for members of the public to comment and provide new 

information in the prelease sale planning process. Historically, the Call for 

Information (Call), which is the first step in the Prelease Sale Process, has generally 

asked for industry to nominate specific blocks or descriptions of areas within the 

Five-Year Program area for which they have the most interest, while the NOI 

requests comments on issues that should be addressed and alternatives that should be 

considered in the NEPA documents that will be prepared for the action.

• Annual Progress Report. BOEM will publish an annual progress report on the 

approved Five-Year Program that includes an opportunity for stakeholders and the 

public to comment on the Five-Year Program’s implementation. Under Section 18(e) 

of the OCSLA, the Secretary must review annually the approved Five-Year Program. 
The Proposed Action 1-13

Historically, this has been an internal review process that reported to the Secretary 

any information or events that might result in a revision to the Five-Year Program. If 

the revision is considered significant under the OCSLA, the Five-Year Program can 

only be revised and reapproved by following the same Section 18 steps used to 

originally develop the Program. However, once the Section 18 process has been 

initiated for the next Five-Year Program, the annual review is subsumed in that 

process, as the same substantive and procedural requirements are being addressed.

The findings of the annual progress report may lead the Secretary to revise the FiveYear Program by reducing the size of, delaying, or cancelling scheduled lease sales. 

If the desired revisions are considered significant, such as including new areas for 

consideration or more lease sales in areas already included, the entire Section 18 

process must be followed, in essence resulting in the preparation of a new Program. 

BOEM’s 2014 Annual Progress Report (issued in January 2015) provided an 

overview of the activities that occurred during the previous year. Oil and gas 

exploration, development, and production were successful in the Gulf of Mexico, and 

there was no indication of proposed revisions to the current 2012-2017 Five-Year 

Program for the remainder of the Program. Therefore, with proposed WPA Lease 

Sale 248 as the last proposed WPA lease sale of the Five-Year Program and no 

revisions currently proposed, changes to the current Five-Year Program are not 

expected. Nonetheless, BOEM is currently engaged in the development of the 2017-

2022 Five-Year Program and should there be any proposed revisions, they would be 

subsumed into the ongoing 2017-2022 Section 18 process.

• Systematic Planning. BOEM is committed to engaging in systematic planning 

opportunities that foster improved governmental coordination, communication, and 

information exchange. As the only agency authorized to grant renewable energy, 

marine mineral, and oil and gas leases on the OCS, the Bureau of Ocean Energy 

Management has been assigned as the Federal co-lead, along with the U.S. Coast 

Guard, for systematic regional planning efforts in the Mid-Atlantic. Additionally, 

BOEM will participate on Regional Planning Bodies in the Northeast, Mid-Atlantic, 

and West Coast as the Department of the Interior (DOI) lead. In the Gulf of Mexico 

OCS Region, BOEM representatives will assist the U.S. Fish and Wildlife Service 

(FWS), the DOI regional lead, with various working group activities. This will 

facilitate data and information availability, provide research of new technologies, and 

identify conflict resolution and avoidance strategies. BOEM anticipates that its 

Marine Planning engagement will enhance regulatory efficiency through improved 

coordination and collaboration, and, in the long term, enhance the stewardship of 

ocean and coastal resources.

These strategies will allow BOEM to not only address the activities that take place under the 

2012-2017 Five-Year Program but also to lay the groundwork for decisions that will be faced in 

subsequent Five-Year Programs. BOEM will improve efforts to gather information while enhancing 

opportunities for stakeholders and other interested parties to participate in and be engaged in the 

decisionmaking process. The initiation of studies and long-term planning will facilitate future decisions 

by ensuring that the best information is available when making leasing decisions on the approved 

program and before the development of future OCS Programs.

1.5. POSTLEASE ACTIVITIES

BOEM and BSEE are responsible for managing, regulating, and monitoring oil and natural gas 

exploration, development, and production operations on the Federal OCS to promote the 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 parts 550, 551 (except those aspects that pertain to drilling), 

and 554. 
1-14 Western Planning Area Lease Sale 248 Supplemental EIS

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

implemented through lease stipulations, operating regulations, NTLs, and project-specific requirements or 

approval conditions. The NTLs provide clarifications and additional information on some of these 

measures. Mitigating measures address concerns such as endangered and threatened species, geologic 

and manmade hazards, military warning and ordnance disposal areas, archaeological sites, air quality, 

oil-spill response planning, chemosynthetic communities, artificial reefs, operations in hydrogen sulfide 

(H2S)-prone areas, and shunting of drill effluents in the vicinity of biologically sensitive features. Refer 

to Appendix A (“Commonly Applied Mitigating Measures”) of the WPA 246/248 Supplemental EIS, 

which is hereby incorporated by reference, for more information on the mitigations that BOEM and BSEE 

apply to plans and/or permits as applicable. 

BOEM issues NTLs to provide clarification, description, or interpretation of a regulation; to provide 

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

administrative information. A detailed listing of the current Gulf of Mexico OCS Region NTLs is 

available through BOEM’s Gulf of Mexico OCS Region’s website at http://boem.gov/Regulations/

Notices-Letters-and-Information-to-Lessees-and-Operators.aspx or through the Region’s Public 

Information Office at 504-736-2519 or 1-800-200-GULF.

Formal plans must be submitted to BOEM for review and approval before any project-specific 

activities, except for ancillary activities (such as geological and geophysical [G&G] activities or studies 

that model potential oil and hazardous substance spills), can begin on a lease. Conditions of approval are 

mechanisms to control or mitigate potential safety or environmental problems associated with proposed 

operations. Conditions of approval are based on BOEM’s 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 and easement, 

or pipeline right-of-way grant.

Some BOEM-identified mitigating measures are implemented through cooperative agreements or 

coordination with the oil and gas industry and Federal and State agencies. These measures include the 

National Marine Fisheries Service’s (NMFS’s) 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.

Refer to Chapter 1.5 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 

Supplemental EIS for descriptions of postlease activities, including the following: G&G surveys; 

exploration and development plans; permits and applications; inspection and enforcement; pollution 

prevention, oil spill response plans, and financial responsibility; air emissions; flaring and venting; 

hydrogen sulfide contingency plans; archaeological resources regulation; coastal zone management

consistency review and appeals for plans; best available and safest technologies, including at production 

facilities; personnel training and education; structure removal and site clearance; marine protected species 

NTLs; and the Rigs-to-Reefs program.

1.6. OTHER OCS OIL- AND GAS-RELATED ACTIVITIES

BOEM and BSEE have programs and activities that are OCS related but not specific to the oil and gas 

leasing process or to the management of exploration, development, and production activities. These 

programs include both environmental and technical studies, and cooperative agreements with other 

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

activities, and regulatory enforcement. BOEM also participates in industry research efforts and forums. 

Chapter 1.6 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS

contains descriptions of the other OCS oil- and gas-related activities, including the Environmental Studies 

Program, Technology Assessment Program (formerly known as Technology Assessment & Research 

(TA&R) Program), and interagency agreements. Refer to Chapter 1.3.1.1 for the list of recent Gulf of 

Mexico Environmental Studies Program publications. 
CHAPTER 2 

ALTERNATIVES INCLUDING THE PROPOSED ACTION

Alternatives Including the Proposed Action 2-3 

2. ALTERNATIVES INCLUDING THE PROPOSED ACTION 

This Supplemental EIS addresses one proposed Federal action: proposed OCS oil and gas Lease Sale 

248 in the WPA of the GOM (Figure 1-1), as scheduled in the Five-Year Program (USDOI, BOEM, 

2012a). The proposed action (proposed lease sale) assumes compliance with applicable regulations and 

lease stipulations in place at the time a ROD is signed. 

2.1. SUPPLEMENTAL EIS NEPA ANALYSIS

Proposed WPA Lease Sale 248 was analyzed in the 2012-2017 WPA/CPA Multisale EIS. This 

Supplemental EIS tiers from the prior 2012-2017 Gulf of Mexico EISs (i.e., the 2012-2017 WPA/CPA 

Multisale EIS, WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS), and it summarizes and hereby incorporates those documents by reference. 

The proposed lease sale is expected to be within the scenario ranges summarized in Chapter 3 of this 

Supplemental EIS and as discussed in Chapter 3 of the prior 2012-2017 Gulf of Mexico EISs from which 

it tiers.

At the completion of the NEPA process for this Supplemental EIS, a decision will be made on 

whether or how to proceed with proposed WPA Lease Sale 248. Informal and formal consultation with 

other Federal agencies, the affected States, federally recognized Indian Tribes, nongovernmental 

organizations, and the public will be carried out to assist in the determination of whether or not the 

information and analysis contained in this Supplemental EIS is still valid. Specifically, information 

requests will be issued soliciting input on proposed WPA Lease Sale 248. 

2.2. ALTERNATIVES, MITIGATING MEASURES, AND ISSUES

2.2.1. Alternatives

The alternatives to be considered for proposed WPA Lease Sale 248 are detailed in Chapter 2.3

below. These suggested alternatives have been derived from both the historical comments submitted to 

BOEM and the scoping performed for the analyses in this Supplemental EIS. 

Through our scoping efforts for this Supplemental EIS and previous EISs, numerous issues and topics 

were identified for consideration. During the scoping period for the prior 2012-2017 Gulf of Mexico 

EISs, a number of alternatives or deferral options were suggested and examined for inclusion in those

EISs (Chapter 2.2.1.1 of the prior 2012-2017 Gulf of Mexico EISs). Those alternative and deferral 

options were also reexamined during the preparation of this Supplemental EIS. These suggestions 

included additional deferrals, policy changes, and suggestions beyond the scope of this Supplemental EIS. 

BOEM has not identified any new significant information that changes its conclusions in the prior 

2012-2017 Gulf of Mexico EISs or that indicates that the proposed alternatives or deferral options are 

appropriate for further in-depth analysis. The justifications for not carrying those suggestions through 

detailed analyses in this Supplemental EIS are the same as those used in the prior 2012-2017 Gulf of 

Mexico EISs. 

The analyses of environmental impacts from the proposed alternatives summarized in 

Chapter 2.3.1.2 below and described in detail in Chapter 4.1.1 are based on the development scenario, 

which is a set of assumptions and estimates on the amounts, locations, and timing for OCS oil and gas 

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. 

2.2.1.1. Alternatives for Proposed Western Planning Area Lease Sale 248

Alternative A—The Proposed Action (Preferred Alternative): This alternative would offer for lease 

all unleased blocks within the proposed WPA lease sale area for oil and gas operations (Figure 2-1), with 

the following exception: 
2-4 Western Planning Area Lease Sale 248 Supplemental EIS

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

Marine Sanctuary (i.e., the boundary as of the publication of this Supplemental EIS).

The DOI is conservative throughout the NEPA process and includes the total area within the WPA for 

environmental review even though the leasing of portions of the WPA (subareas or blocks) can be 

deferred during a Five-Year Program. 

The proposed WPA lease sale area encompasses about 28.58 million ac. As of July 2015, 

approximately 22 million ac of the proposed WPA lease sale area are currently unleased. This 

information is updated monthly and can be found on BOEM’s website at http://www.boem.gov/Gulf-ofMexico-Region-Lease-Map/. The estimated amount of resources projected to be developed as a result of 

the proposed WPA lease sale is 0.116-0.200 BBO and 0.538-0.938 Tcf of gas (Table 3-1).

Alternative B—Exclude the Unleased Blocks Subject to the Topographic Features Stipulation: This 

alternative would offer for lease the same unleased blocks within the proposed WPA lease sale area as 

described for the proposed action (Alternative A), but it would exclude from leasing any unleased blocks 

subject to the Topographic Features Stipulation (which would be offered under Alternative A) discussed 

in Chapter 2.3.1.3.1 below. The estimated amount of resources projected to be developed is

0.116-0.200 BBO and 0.538-0.938 Tcf of gas. The number of blocks that would not be offered under 

Alternative B represents only a small percentage of the total number of blocks to be offered under 

Alternative A; therefore, it is assumed that the levels of activity for Alternative B would be essentially the 

same as those projected for the WPA proposed action. The exclusion of this small subset of available 

blocks would likely reduce exploration, development, and production flexibility and, therefore, would 

likely result in adverse economic effects. Refer to Chapters 2.3.2 and 4.1.2 for further details. 

Alternative C—No Action: This alternative is the cancellation of the proposed WPA lease sale. If this 

alternative is chosen, the opportunity for development of the estimated 0.116-0.200 BBO and 

0.538-0.938 Tcf of gas that could have resulted from the proposed WPA lease sale would be precluded 

during the current 2012-2017 Five-Year Program, but it could again be contemplated as part of a future 

Five-Year Program. Any potential environmental impacts arising out of the proposed WPA lease sale 

would not occur, but activities associated with existing leases in the WPA would continue. Refer to 

Chapters 2.3.3 and 4.1.3 for further details.

Alternatives and Deferrals Considered but Not Analyzed in Detail

Chapter 2.2.1.1 of the 2012-2017 WPA/CPA Multisale EIS includes a detailed description of 

alternatives previously considered but not analyzed in detail in this Supplemental EIS, including the 

following: exclude deep water and limit leasing to shallow waters; delay leasing until drilling safety is 

improved; do not allow drilling in areas with strong ocean currents such as the Loop Current; delay 

leasing until the state of the GOM environmental baseline is known; and identify and protect sensitive 

ecosystems. The justifications for not engaging in detailed analysis of these alternatives and deferrals in 

this Supplemental EIS are the same as those used in the 2012-2017 WPA/CPA Multisale EIS, and BOEM 

has identified no new information that changes these conclusions. No new alternatives were proposed 

during the scoping period for this Supplemental EIS (refer to Chapter 5.3.2 for a summary of the scoping 

comments).

2.2.2. Mitigating Measures

The NEPA process is intended to help public officials make decisions that are based on an 

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

environment. Agencies are required to identify and include in an EIS those appropriate mitigating 

measures not already included in the proposed action or alternatives. The CEQ regulations (40 CFR § 

1508.20) define mitigation as follows:

• Avoidance—Avoiding an impact altogether by not taking a certain action or part of 

an action. 

• Minimization—Minimizing impacts by limiting the intensity or magnitude of the 

action and its implementation. 
Alternatives Including the Proposed Action 2-5 

• Restoration—Rectifying the impact by repairing, rehabilitating, or restoring the 

affected environment. 

• Maintenance—Reducing or eliminating the impact over time by preservation and 

maintenance operations during the life of the action. 

• Compensation—Compensating for the impact by replacing or providing substitute 

resources or environments.

2.2.2.1. Proposed Mitigating Measures Analyzed

The potential lease stipulations and mitigating measures included for analysis in this Supplemental 

EIS were developed as a result of numerous scoping efforts for the continuing OCS Program in the GOM. 

Five lease stipulations (described in Chapter 2.3.1.3 of the prior 2012-2017 Gulf of Mexico EISs) are 

proposed for WPA Lease Sale 248—the Topographic Features Stipulation, Military Areas Stipulation, 

Protected Species Stipulation, United Nations Convention on the Law of the Sea Royalty Payment 

Stipulation, and the Stipulation on the Agreement between the United States of America and the United 

Mexican States Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico. 

The United Nations Convention on the Law of the Sea Royalty Payment Stipulation is applicable to 

the proposed WPA lease sale even though it is not an environmental or military stipulation. 

These measures will be considered for adoption by the ASLM, under authority delegated by the 

Secretary. The analysis of any stipulations for Alternative A does not ensure that the ASLM will make a 

decision to apply the stipulations to leases that may result from the proposed WPA 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 lease stipulations or mitigating measures to be included in a lease sale will be described in the 

ROD for that lease sale. Mitigating measures in the form of lease stipulations are added to the lease terms 

and are therefore enforceable as part of the lease. In addition, each exploration and development plan, as 

well as any pipeline applications that result from a lease sale, will undergo a NEPA review, and additional 

project-specific mitigations will be applied as conditions of plan approval. Refer to Appendix A 

(“Commonly Applied Mitigating Measures”) of the WPA 246/248 Supplemental EIS, which is 

incorporated by reference, for more information on the mitigations that BOEM and BSEE apply to plans 

and/or permits as applicable. The BSEE has the authority to monitor and enforce these conditions, and 

under 30 CFR part 250 subpart N, may seek remedies and penalties from any operator that fails to comply 

with those conditions, stipulations, and mitigating measures.

2.2.2.2. Existing Mitigating Measures

Mitigating measures have been proposed, identified, evaluated, or developed through previous 

BOEM lease sale NEPA review and analysis. Many of these mitigating measures have been adopted and 

incorporated into regulations and/or guidelines governing OCS oil and gas exploration, development, and 

production activities. All plans for OCS oil- and gas-related activities (e.g., exploration and development 

plans, pipeline applications, and structure-removal applications) go through rigorous BOEM review and 

approval to ensure compliance with established laws and regulations. Existing mitigating measures must 

be incorporated and documented in plans submitted to BOEM. Operational compliance of the mitigating 

measures is enforced through BSEE’s onsite inspection program.

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

in an environmentally sound manner (with an emphasis on minimizing any adverse impact of routine 

operations on the environment). For example, certain measures ensure site clearance, and survey 

procedures are carried out to determine potential snags to commercial fishing gear and to avoid 

archaeological sites and biologically sensitive areas such as topographic features and deepwater benthic 

(chemosynthetic and nonchemosynthetic) communities. In addition, all BOEM-regulated activities and 

operations must comply with the requirements of other agencies having jurisdiction. Refer to Chapter 5

for more information on applicable consultation and coordination requirements.

Some BOEM-identified mitigating measures are incorporated into OCS operations through 

cooperative agreements or efforts with industry and State and Federal agencies. These mitigating 

measures include mandating compliance with the National Marine Fisheries Service’s (NMFS’s) 
2-6 Western Planning Area Lease Sale 248 Supplemental EIS

Observer Program to protect marine mammals and sea turtles during the use of explosives for structure 

removal, labeling operational supplies to track possible sources of debris or equipment loss, developing 

methods of pipeline landfall to eliminate impacts to beaches or wetlands, and requiring beach cleanup 

events.

Site-specific mitigating measures are also applied by BOEM during plan and permit reviews. BOEM 

realized that many of these site-specific mitigations were recurring and developed a list of “standard” 

mitigations. There are currently over 120 standard mitigations. The wording of a standard mitigation is 

developed by BOEM in advance and may be applied whenever conditions warrant. Standard mitigation 

text is revised as often as is necessary (e.g., to reflect changes in regulatory citations, agency/personnel 

contact numbers, and internal policy). Site-specific mitigation “categories” include air quality, 

archaeological resources, artificial reef material, chemosynthetic communities, Flower Garden Banks, 

topographic features, hard bottoms, military warning areas and Eglin Water Test Areas, hydrogen sulfide, 

drilling hazards, remotely operated vehicle surveys, geophysical survey reviews, and general safety

concerns. Site-specific mitigation “types” include advisories, conditions of approval, hazard survey 

reviews, inspection requirements, notifications, post-approval submittals, and safety precautions. In 

addition to standard mitigations, BOEM may also apply nonrecurring mitigating measures that are 

developed on a case-by-case basis. Refer to Appendix A (“Commonly Applied Mitigating Measures”) of 

the WPA 246/248 Supplemental EIS, which is hereby incorporated by reference, for more information on 

the mitigations that BOEM and BSEE apply to plans and/or permits as applicable. 

BOEM is continually revising applicable mitigations to allow the Gulf of Mexico OCS Region to 

more easily and routinely track mitigation compliance and effectiveness. A primary focus of this effort is 

requiring post-approval submittal of information within a specified timeframe or after a triggering event

(e.g., end of operations reports for plans, construction reports for pipelines, and removal reports for 

structure removals). 

2.2.3. Issues

Issues are defined in CEQ Guidance as the principal “effects” that an EIS should evaluate in-depth. 

Selection of environmental and socioeconomic issues to be analyzed was based on the following criteria:

• the issue is identified in CEQ regulations as subject to evaluation;

• the relevant resource/activity was identified through agency expertise, through the 

scoping process, or from comments on past EISs; 

• the resource/activity may be vulnerable to one or more of the impact-producing 

factors associated with the OCS Program;

• a reasonable probability of an interaction between the resource/activity and impactproducing factor should exist; or

• the information that indicates a need to evaluate the potential impacts to a 

resource/activity has become available.

2.2.3.1. Issues to be Analyzed

Chapter 2.2.3.1 of the 2012-2017 WPA/CPA Multisale EIS addresses the issues related to potential 

impact-producing factors and the environmental and socioeconomic resources and activities that could be 

affected by OCS oil and gas exploration, development, production, and transportation activities (i.e., 

accidental events; drilling fluids and cuttings; visual and aesthetic interference; air emissions; water 

quality degradation and other wastes; structure and pipeline emplacement; platform removals; OCS oiland gas-related support services, activities, and infrastructure; and regional cultures and socioeconomics). 

Chapter 4.1.1 of this Supplemental EIS and Chapter 4.1.1 of the prior 2012-2017 Gulf of Mexico EISs

describe the resources and activities that could be affected by the impact-producing factors listed above 

and include the following resource topics:
Alternatives Including the Proposed Action 2-7 

— Air Quality

— Archaeological Resources (Historic and 

Prehistoric)

— Coastal Barrier Beaches and Associated 

Dunes 

— Coastal and Marine Birds 

— Commercial Fisheries

— Deepwater Benthic Communities 

(Chemosynthetic and Nonchemosynthetic)

— Diamondback Terrapins 

— Fish Resources and Essential Fish Habitat

— Human Resources and Land Use 

(Land Use and Coastal Infrastructure, 

Demographics, Economic Factors, and 

Environmental Justice)

— Marine Mammals

— Recreational Fishing

— Recreational Resources

— Sargassum Communities 

— Sea Turtles

— Seagrass Communities 

— Soft Bottom Benthic Communities 

— Species Considered due to U.S. Fish and 

Wildlife Concerns 

— Topographic Features

— Water Quality (Coastal and Offshore)

— Wetlands

2.2.3.2. Issues Considered but Not Analyzed

As previously noted, the CEQ regulations for implementing NEPA instruct agencies to adopt an early 

process (termed “scoping”) for determining the scope of issues to be addressed and for identifying 

significant issues related to a proposed action. As part of this scoping process, agencies shall identify and 

eliminate from detailed study the issues that are not significant to the WPA proposed action or have been 

covered by prior environmental review. 

Additional issues identified during scoping are addressed in this Supplemental EIS. Comments 

received during scoping are summarized in Chapter 5.3.2. Two comments listed in Chapter 5.3.2 are 

issues that are considered in this Supplemental EIS. One other comment, which is from the Choctaw 

Nation of Oklahoma, indicates that their Tribe does not have archaeological deposits offshore in the WPA 

and they defer comment under the National Historic Preservation Act to other Tribes that have been 

contacted. For ongoing discussions with federally recognized Indian Tribes, refer to Chapter 5.9. The 

fourth comment is a suggested alternative that is addressed in Chapter 2.2.1.1 of this Supplemental EIS 

and Chapter 2.2.1.1 of the 2012-2017 WPA/CPA Multisale EIS, which is incorporated by reference.

2.3. PROPOSED WESTERN PLANNING AREA LEASE SALE 248

2.3.1. Alternative A—The Proposed Action

2.3.1.1. Description

Alternative A would offer for lease all unleased blocks within the proposed WPA lease sale area for 

oil and gas operations (Figure 2-1), with the following exception: 

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

Marine Sanctuary (i.e., the boundary as of the publication of this Supplemental EIS). 

The DOI is conservative throughout the NEPA process and includes the total area within the WPA for 

environmental review even though the leasing of portions of the WPA (subareas or blocks) can be 

deferred during a Five-Year Program. 

The proposed WPA lease sale area encompasses about 28.58 million ac. As of July 2015, 

approximately 22 million ac of the proposed WPA lease sale area are currently unleased. This 

information is updated monthly and can be found on BOEM’s website at http://www.boem.gov/Gulf-ofMexico-Region-Lease-Map/. The estimated amount of resources projected to be developed as a result of 

the proposed WPA lease sale is 0.116-0.200 BBO and 0.538-0.938 Tcf of gas (Table 3-1). 

The analyses of impacts summarized below and described in detail in Chapter 4.1.1 are based on the 

development scenario, which is a set of assumptions and estimates on the amounts, locations, and timing 

for OCS oil and gas exploration, development, and production operations and facilities, both offshore and 
2-8 Western Planning Area Lease Sale 248 Supplemental EIS

onshore. A detailed discussion of the development scenario and major related impact-producing factors is 

included in Chapter 3. 

Alternative A has been identified as BOEM’s preferred alternative; however, this does not mean that 

another alternative may not be selected in the ROD. 

2.3.1.2. Summary of Impacts

A search by BOEM’s subject-matter experts was conducted for each resource to consider new 

information made available since publication of the prior 2012-2017 Gulf of Mexico EISs and to consider 

new information on the Deepwater Horizon explosion, oil spill, and response. It must also be emphasized 

that, in arriving at the overall conclusions for certain environmental resources (e.g., coastal and marine 

birds, fisheries, and wetlands), the conclusions are not based on impacts to individuals, small groups of 

animals, or small areas of habitat, but on impacts to the resources/populations as a whole. Any new 

information discovered was analyzed by BOEM’s subject-matter experts to determine if the impact 

conclusions presented in the prior 2012-2017 Gulf of Mexico EISs were altered as a result of the new 

information. 

For the following resources, BOEM’s subject-matter experts determined through literature searches 

and communications with other agencies and academia that there was no new information made available

since publication of the prior 2012-2017 Gulf of Mexico EISs that is relevant to the WPA proposed 

action. Therefore, the impact conclusions for these resources remain the same as those that were 

presented in the prior 2012-2017 Gulf of Mexico EISs. These impact conclusions are presented in 

Chapter 4.1.1. For ease of review, the individual chapter numbers for each resource are provided in the 

following list.

• Seagrass Communities (Chapter 4.1.1.5) 

• Sargassum Communities (Chapter 4.1.1.7) 

• Soft Bottom Benthic Communities (Chapter 4.1.1.10) 

• Diamondback Terrapins (Chapter 4.1.1.13) 

• Archaeological Resources (Historic and Prehistoric) (Chapters 4.1.1.19.1 and

4.1.1.19.2, respectively) 

• Species Considered due to U.S. Fish and Wildlife Service Concerns (Chapter 

4.1.1.21) 

For the following resources, BOEM’s subject-matter experts determined through literature searches 

and communications with other agencies and academia that there was new information made available 

since publication of the prior 2012-2017 Gulf of Mexico EISs that is relevant to the WPA proposed 

action. BOEM’s subject-matter experts have reexamined the analyses for these resources based on new 

information made available; however, none of the new information was deemed significant enough to 

alter any of the impact conclusions presented in the prior 2012-2017 Gulf of Mexico EISs. These impact 

conclusions are presented in Chapter 4.1.1. For ease of review, the individual chapter numbers for each 

resource are provided in the following list. 

• Air Quality (Chapter 4.1.1.1) 

• Water Quality (Coastal and Offshore Waters) (Chapters 4.1.1.2.1 and 4.1.1.2.2, 

respectively) 

• Coastal Barrier Beaches and Associated Dunes (Chapter 4.1.1.3) 

• Wetlands (Chapter 4.1.1.4) 

• Topographic Features (Chapter 4.1.1.6) 

• Chemosynthetic Deepwater Benthic Communities (Chapter 4.1.1.8) 
Alternatives Including the Proposed Action 2-9 

• Nonchemosynthetic Deepwater Benthic Communities (Chapter 4.1.1.9) 

• Marine Mammals (Chapter 4.1.1.11) 

• Sea Turtles (Chapter 4.1.1.12) 

• Coastal and Marine Birds (Chapter 4.1.1.14) 

• Fish Resources and Essential Fish Habitat (Chapter 4.1.1.15) 

• Commercial Fisheries (Chapter 4.1.1.16) 

• Recreational Fishing (Chapter 4.1.1.17) 

• Recreational Resources (Chapter 4.1.1.18) 

• Human Resources and Land Use (Land Use and Coastal Infrastructure, 

Demographics, Economic Factors, and Environmental Justice) (Chapters 4.1.1.20.1, 

4.1.1.20.2, 4.1.1.20.3, and 4.1.1.20.4, respectively) 

Ultimately, no new significant information was discovered that would alter the impact conclusions for 

any of the resources analyzed in the prior 2012-2017 Gulf of Mexico EISs. The analyses and potential 

impacts detailed in the prior 2012-2017 Gulf of Mexico EISs remain valid and, as such, apply for 

proposed WPA Lease Sale 248. 

In accordance with CEQ regulations to provide decision-makers with a robust environmental analysis, 

Appendix A (“Catastrophic Spill Event Analysis”) provides an analysis of the potential impacts of a lowprobability catastrophic oil spill, which is not a part of the WPA proposed action and not likely expected, 

to the environmental and cultural resources and the socioeconomic conditions analyzed in Chapter 4.1.1. 

2.3.1.3. Mitigating Measures

The following lease stipulations may be applied to the WPA proposed action as mitigating measures. 

If the decision is to hold a lease sale, the lease stipulations applicable to the lease sale will be announced 

in the Final Notice of Sale and Record of Decision.

2.3.1.3.1. Topographic Features Stipulation

The topographic features located in the WPA provide habitat for hard bottom communities of high 

biomass and diversity (Chapter 4.1.1.6). Without the Topographic Features Stipulation and mitigating 

measures, these communities could be severely and adversely impacted by oil and gas activities resulting 

from the WPA proposed action if such activities took place on blocks that are subject to the Topographic 

Features Stipulation (i.e., those blocks with a topographic feature, a No Activity Zone surrounding a 

topographic feature, or a shunting zone [1,000-Meter, 1-Mile, 3-Mile, and/or 4-Mile] surrounding a 

topographic feature). The DOI has recognized this problem for some years and, since 1973, has made 

lease stipulations a part of leases on blocks near these biotic communities so that impacts from nearby oil 

and gas activities were mitigated. This stipulation would not prevent the recovery of oil and gas resources

within a Topographic Features Stipulation block, but it would serve to protect valuable and sensitive 

biological resources from routine OCS oil- and gas-related activity by distancing bottom-disturbing 

activity (e.g., anchors, chains, cables, and wire ropes) 152 m (500 ft) from the No Activity Zone that 

surrounds topographic features and by requiring that drill muds and cuttings be shunted to the seafloor if a 

well is within a shunting zone (1,000-Meter, 1-Mile, 3-Mile, and/or 4-Mile) surrounding a topographic 

feature. 

The Topographic Features Stipulation was formulated based on consultation with various Federal 

agencies and comments solicited from the States, industry, environmental organizations, and academic 

representatives. The Topographic Features Stipulation has been updated over time, using years of 

scientific information collected since the stipulation was first proposed. This information includes 

numerous Agency-funded studies of topographic features in the GOM; numerous stipulation-imposed, 

industry-funded monitoring reports; and numerous studies of drilling discharges offshore (Neff, 2005; 

Boehm et al., 2001; Neff et al., 2000; and NRC, 1983). BOEM and the National Oceanic and 
2-10 Western Planning Area Lease Sale 248 Supplemental EIS

Atmospheric Administration (NOAA) also co-sponsor an ongoing long-term monitoring program at the 

Flower Garden Banks in order to determine if continued offshore oil and gas activity in the GOM has 

impacted the reef habitat of these features. The Topographic Features Stipulation protects these biotic 

communities from routine OCS oil and gas activities resulting from the WPA proposed action, while 

allowing the development of nearby oil and gas resources. This stipulation would not prevent adverse

effects of an accident such as a large oil spill from a nearby oil or gas operation from impacting these 

biotic communities; however, it would distance the activity at least 152 m (500 ft) from the No Activity 

Zone surrounding topographic features, thereby reducing the possibility of physical oiling. The location 

of the blocks affected by the Topographic Features Stipulation is shown on Figure 2-1. A more detailed 

discussion and definition of this stipulation and its effectiveness are found in Chapter 2.3.1.3.1 of the 

2012-2017 WPA/CPA Multisale EIS.

2.3.1.3.2. Military Areas Stipulation

The Military Areas Stipulation has been applied to all blocks leased in military areas since 1977 and 

reduces potential impacts, particularly in regards to safety. However, this stipulation 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 GOM. A more 

detailed discussion and definition of this stipulation and its effectiveness are found in Chapter 2.3.1.3.2 of 

the 2012-2017 WPA/CPA Multisale EIS. 

2.3.1.3.3. Protected Species Stipulation

The Protected Species Stipulation has been applied to all blocks leased in the GOM since December 

2001. This stipulation was developed in consultation with the U.S. Department of Commerce, National 

Oceanic and Atmospheric Administration, NMFS, and the U.S. Department of the Interior, FWS, in 

accordance with Section 7 of the Endangered Species Act, and it is designed to minimize or avoid 

potential adverse impacts to federally protected species. A more detailed discussion and definition of this 

stipulation and its effectiveness are found in Chapter 2.3.1.3.3 of the 2012-2017 WPA/CPA Multisale 

EIS.

2.3.1.3.4. United Nations Convention on the Law of the Sea Royalty Payment

Stipulation

The United Nations Convention on the Law of the Sea Royalty Payment Stipulation has been applied 

to blocks or portions of blocks beyond the U.S. Exclusive Economic Zone (generally greater than 200 nmi 

[230 mi; 370 km] from the U.S. coastline). Leases on these blocks may be subject to special royalty 

payments under the provisions of the 1982 United Nations Convention on the Law of the Sea Royalty 

Payment Stipulation (consistent with Article 82) if the U.S. becomes a party to the Convention prior to or 

during the life of the lease. A more detailed discussion and definition of this stipulation and its 

effectiveness are found in Chapter 2.3.1.3.4 of the 2012-2017 WPA/CPA Multisale EIS. 

2.3.1.3.5. Stipulation on the Agreement between the United States of America and the 

United Mexican States Concerning Transboundary Hydrocarbon Reservoirs 

in the Gulf of Mexico

The “Agreement Between the United States of America and the United Mexican States Concerning 

Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico” has now entered into force, making it 

possible for U.S. lessees to enter into voluntary agreements with a licensee of the United Mexican States 

to develop transboundary reservoirs. The stipulation has been applied to blocks or portions of blocks 

located wholly or partially within the 3 statute miles (4.8 km) of the maritime or continental shelf 

boundary with Mexico. The stipulation incorporates by reference the Agreement and notifies lessees that, 

among other things, activities in this boundary area will be subject to the Agreement and that approval of 

plans, permits, and unitization agreements will be conditioned upon compliance with the terms of the 
Alternatives Including the Proposed Action 2-11

Agreement. For more information, refer to the Agreement itself, which is available on BOEM’s website 

at http://www.boem.gov/BOEM-Newsroom/Library/Publications/Agreement-between-the-United-Statesand-Mexico-Concerning-Transboundary-Hydrocarbon-Reservoirs-in-the-Gulf-of-Mexico.aspx. 

2.3.2. Alternative B—Exclude the Unleased Blocks Subject to the Topographic 

Features Stipulation

2.3.2.1. Description

Alternative B differs from Alternative A by not offering the unleased blocks that are subject to the 

proposed Topographic Features Stipulation but that would be offered under Alternative A (except blocks 

within the Flower Garden Banks National Marine Sanctuary, which are not offered under either 

alternative) (Chapter 2.3.1.3.1 of this Supplemental EIS and Chapter 2.3.1.3.1 of the 2012-2017 

WPA/CPA Multisale EIS). Blocks subject to the Topographic Features Stipulation include any unleased 

block in which a No Activity Zone or Shunting Zone surrounding a topographic feature is located. These 

unleased blocks will not be available for lease under Alternative B. The number of unleased blocks that 

would not be offered under Alternative B represents only a small percentage of the total number of blocks 

to be offered under Alternative A; therefore, it is assumed that the levels of activity for Alternative B 

would be essentially the same as those projected for the WPA proposed action (refer to Chapter 4.1.2 for 

further details). The estimated amount of resources projected to be developed under Alternative B is 

within the same scenario range as for Alternative A, i.e., 0.116-0.200 BBO and 0.538-0.938 Tcf of gas. 

All of the assumptions, including the four other potential mitigating measures (i.e., the Military Areas 

Stipulation, Protected Species Stipulation, United Nations Convention on the Law of the Sea Royalty 

Payment Stipulation, and the Stipulation on the Agreement between the United States of America and the 

United Mexican States Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico, as 

described in Chapter 2.2.1.3), are the same as for Alternative A. A description of Alternative A is 

presented in Chapter 2.3.1.1. The Topographic Features Stipulation would not be applicable with

Alternative B because the blocks that could be subject to the Topographic Features Stipulation would not 

be offered for lease.

2.3.2.2. Summary of Impacts

The analyses of impacts summarized in Chapter 2.3.1.2 and described in detail in Chapter 4.1.1 are 

based on the development scenario, which is a set of assumptions and estimates on the amounts, 

locations, and timing for OCS oil and gas 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. 

The difference between the potential impacts described for Alternative A and those under 

Alternative B is that under Alternative B no oil- and gas-related activity would take place in the blocks 

subject to the Topographic Features Stipulation under Alternative A (Figure 2-1). The number of blocks 

that would not be offered under Alternative B represents only a small percentage of the total number of 

blocks to be offered under Alternative A; therefore, it is assumed that the levels of activity for 

Alternative B would be essentially the same as those projected for the WPA proposed action. As a result, 

the impacts expected to result from Alternative B would be very similar to those described under the 

WPA proposed action (Chapter 4.1.1). Therefore, the regional impact levels for all resources, except for 

the topographic features, would be similar to those described under the WPA proposed action. This 

alternative, if adopted, would prevent any oil- and gas-related activity whatsoever in the affected blocks; 

thus, it would eliminate any potential direct impacts to the biota of those blocks from routine oil- and gasrelated 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 the proposed WPA lease sale. If this alternative is chosen, the 

opportunity for development of the estimated 0.116-0.200 BBO and 0.538-0.938 Tcf of gas that could 

have resulted from the proposed WPA lease sale would be precluded or postponed to a future WPA lease 
2-12 Western Planning Area Lease Sale 248 Supplemental EIS

sale. Any potential environmental impacts arising out of the proposed WPA lease sale would not occur, 

but activities associated with existing leases in the WPA would continue. The No Action alternative, 

therefore, encompasses the same potential impacts as a decision to delay the leasing of unleased blocks in 

the WPA to a later scheduled lease sale under the Five-Year Program, when another decision on whether 

to hold that future lease sale would be made. Because delay of the proposed WPA lease sale would yield 

essentially the same results as the No Action alternative (i.e., most impacts related to Alternative A would 

not occur), delay of the proposed WPA lease sale was not considered as a separate alternative under this 

Supplemental EIS. 

2.3.3.2. Summary of Impacts

Cancelling the proposed WPA lease sale would eliminate the effects described for Alternative A 

(Chapter 4.1.3). The incremental contribution of the WPA proposed lease sale to the cumulative effects 

would also be forgone, but the effects from other activities, including other OCS lease sales, would 

remain. Moreover, if the proposed WPA lease sale was cancelled, the resulting development of oil and 

gas could be reevaluated under a future lease sale. Therefore, the overall level of OCS oil- and gasrelated activity in the WPA would only be reduced by a small percentage, if any, and the cancellation of 

the proposed WPA lease sale would not significantly change the environmental impacts of overall OCS 

oil- and gas-related activity. However, the cancellation of the proposed WPA lease sale could result in 

direct economic impacts to industry. Revenues collected by the Federal Government (and thus revenue 

disbursements to the States) also would be adversely affected.

If the proposed WPA lease sale was cancelled, other sources of energy could potentially be 

substituted for the lost production. Principal substitutes would be additional imports, conservation, 

additional domestic production of oil and gas in other areas, and other fuels. These alternatives, except 

conservation, have significant negative environmental impacts of their own. For example, the tankering 

of fuels from alternate sources over longer distances would also have significant potential negative 

impacts, including through the increased risk of spills in the GOM.
CHAPTER 3 

IMPACT-PRODUCING FACTORS AND SCENARIO

Impact-Producing Factors and Scenario 3-3 

3. IMPACT-PRODUCING FACTORS AND SCENARIO

3.1. IMPACT-PRODUCING FACTORS AND SCENARIO—ROUTINE OPERATIONS

3.1.1. Offshore Impact-Producing Factors and Scenario

Chapter 3.1.1 in the prior 2012-2017 Gulf of Mexico EISs (i.e., the 2012-2017 WPA/CPA Multisale 

EIS, WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 246/248 

Supplemental EIS) describe in detail the offshore infrastructure and activities (impact-producing factors) 

associated with a WPA proposed action (i.e., a typical lease sale that would result from a proposed action) 

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

Gulf of Mexico. In addition, Chapter 3.1.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 3.1.1 

of the Gulf of Mexico OCS Oil and Gas Lease Sales: 2014 and 2016; Eastern Planning Area Lease Sales 

225 and 226; Final Environmental Impact Statement (EPA 225/226 EIS) (USDOI, BOEM, 2013b) also 

describe the OCS Program’s cumulative activity scenario resulting from past and future lease sales in the 

WPA, CPA, and EPA that could potentially affect the biological, physical, and socioeconomic resources 

of the GOM within the WPA. Note that offshore and onshore impact-producing factors and scenarios 

associated with a CPA or an EPA proposed action (i.e., a typical lease sale that would result from a 

proposed action within the CPA or EPA) as well as OCS Program activity resulting from past and future 

lease sales in the CPA or EPA are disclosed in the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 

231 Supplemental EIS, CPA 235/241/247 Supplemental EIS (Gulf of Mexico OCS Oil and Gas Lease 

Sales: 2015-2017; Central Planning Area Lease Sales 235, 241, and 247; Final Supplemental 

Environmental Impact Statement; USDOI, BOEM, 2014b), and EPA 225/226 EIS. 

Offshore is defined, for the purposes of this Supplemental EIS, as the OCS portion of the GOM that 

begins 3 marine leagues (9 nmi; 10.36 mi; 16.67 km) offshore Texas and Florida and 3 nmi (3.45 mi; 

5.56 km) offshore Louisiana, Mississippi, and Alabama. The OCS extends seaward to the limits of the 

United States’ jurisdiction over the continental shelf in water depths up to approximately 3,346 m 

(10,978 ft), which comprises the Exclusive Economic Zone (Figure 1-1). Coastal infrastructure and 

activities associated with a WPA proposed action are described in Chapter 3.1.2. 

BOEM projects that the overwhelming majority of the oil and natural gas fields discovered as a result 

of a WPA proposed action will reach the end of their economic lives within a time span of 40 years 

following a lease sale. Therefore, activity levels are projected to 40 years for this Supplemental EIS. 

Although unusual cases exist where activity on a lease may continue beyond 40 years, BOEM’s forecasts 

indicate that most significant activities associated with exploration, development, production, and 

abandonment of leases in the GOM occur well within the 40-year analysis period. For the cumulative 

case analysis, total OCS Program exploration and development activities are also forecast over a 40-year 

period. For modeling purposes and quantitative OCS Program activity analyses, a 40-year analysis period 

is also used. Exploration and development activity forecasts become increasingly more uncertain as the 

length of time of the forecast increases and the number of influencing factors increases.

BOEM uses a series of spreadsheet-based data analysis tools to develop the forecasts of oil and gas 

exploration, discovery, development, and production activity for a proposed action and OCS Program 

scenarios presented in this Supplemental EIS. BOEM’s analyses incorporate all relevant historical 

activity and infrastructure data, and BOEM’s resulting forecasts are analyzed and compared with actual 

historical data to ensure that historical precedent and recent trends are reflected in each activity forecast.

BOEM is confident that its analysis methodology, with adjustments and refinements based on recent 

activity levels, adequately projects Gulf of Mexico OCS oil- and gas-related activities in both the short 

term and the long term for the EIS analyses.

The WPA proposed actions and the Gulfwide OCS Program scenarios are based on the following 

factors:

• resource estimates developed by BOEM; 

• recent trends in the amount and location of leasing, exploration, and development 

activity;
3-4 Western Planning Area Lease Sale 248 Supplemental EIS

• estimates of undiscovered, unleased, economically recoverable oil and gas resources 

in each water-depth category and each planning area;

• existing offshore and onshore oil and/or gas infrastructure; 

• published data and information; 

• industry information; and

• oil and gas technologies, and the economic considerations and environmental 

constraints of these technologies.

Proposed WPA Lease Sale 248 represents 4-5 percent of the OCS Program activities expected in the 

WPA from 2012 through 2051 based on barrels of oil equivalent (BOE) resource estimates and 1 percent 

of the total OCS Program (WPA, CPA, and EPA) from 2012 through 2051. 

Specific projections for activities associated with the WPA proposed action are discussed in the 

following scenario sections. The potential impacts of the activities associated with a proposed “typical” 

WPA lease sale are considered in the environmental analysis sections (Chapter 4.1.1).

The OCS Program scenario includes all activities that are projected to occur from past, proposed, and 

future lease sales during the analysis period. This includes projected activity from lease sales that have 

been held but for which exploration or development has either not yet begun or is continuing. Activities 

that take place beyond the analysis timeframe as a result of future lease sales are not included in this 

analysis. The impacts of activities associated with the OCS Program on biological, physical, and 

socioeconomic resources are analyzed in the cumulative environmental analysis sections (Chapter 4.1.1).

3.1.1.1. Resource Estimates and Timetables

The WPA proposed action and the cumulative oil and gas program have not changed since analyzed 

for the WPA 246/248 Supplemental EIS. BOEM has not identified any new information or change in 

circumstances since publication of the prior 2012-2017 Gulf of Mexico EISs that would change the 

estimates and timetables.

3.1.1.1.1. Proposed Action

The proposed action scenario is used to assess the potential impacts of a proposed “typical” lease sale. 

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 area; 

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. 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. 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. Historical databases and information derived from oil 

and gas exploration and development activities are available to BOEM and were used extensively. The 

undiscovered, unleased, conventionally recoverable resource estimates for a proposed action are 

expressed as ranges, from low to high. This range provides a reasonable expectation of oil and gas 

production anticipated from a “typical” lease sale held as a result of a proposed action based on an actual 

range of historic observations.

Table 3-1 presents the projected oil and gas production for a WPA proposed action and for the OCS 

Program. Table 3-2 provides a summary of the major scenario elements of a WPA proposed action, a 

“typical” lease sale, and related impact-producing factors. To analyze impact-producing factors for a 

WPA proposed action and the OCS Program, the proposed WPA lease sale area was divided into offshore 

subareas based upon ranges in water depth. Figure 3-1 depicts the location of the offshore subareas. The 

water-depth ranges reflect the technological requirements and related physical and economic impacts as a 

consequence of the oil and gas potential, exploration and development activities, and lease terms unique 

to each water-depth range. Estimates of resources and facilities are distributed into each of the subareas.
Impact-Producing Factors and Scenario 3-5 

Proposed Action Scenario (WPA Typical Lease Sale): The estimated amounts of resources projected 

to be leased, discovered, developed, and produced as a result of a typical proposed WPA lease sale are 

0.116-0.200 BBO and 0.538-0.938 Tcf of gas. 

The number of exploration and delineation wells, production platforms, and development wells 

projected to develop and produce the estimated resources for a WPA proposed action is given in 

Table 3-2. The table shows the distribution of these factors by offshore subareas in the proposed lease 

sale area. Table 3-2 includes estimates of the major impact-producing factors related to the projected 

levels of exploration, development, and production activity. 

Exploratory drilling activity generally takes place over an 8-year period, beginning within 1 year after 

a lease sale. Development activity generally 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 a lease sale and continues to the 40th year; 

however, in rare cases, production could continue beyond the 40th year.

3.1.1.1.2. OCS Program

OCS Program Cumulative Scenario (WPA, CPA, and EPA): Projected reserve/resource production 

for the OCS Program is 18.335-25.64 BBO and 75.886-111.627 Tcf of gas and represents anticipated 

production from lands currently under lease plus anticipated production from future lease sales over the 

40-year analysis period. The OCS Program cumulative scenario includes WPA, CPA, and EPA 

production estimates. Table 3-3 presents all anticipated production from lands currently under lease in 

the WPA, CPA, and EPA plus all anticipated production from future total OCS Program (WPA, CPA, 

and EPA) lease sales over the 40-year analysis period.

WPA Cumulative Scenario: Projected reserve/resource production for the OCS Program in the WPA 

(2.510-3.696 BBO and 12.539-18.434 Tcf of gas) represents anticipated production from lands currently 

under lease in the WPA plus anticipated production from future WPA lease sales over the 40-year 

analysis period. Projected production under the cumulative scenario represents approximately 14 percent 

of the oil and 17 percent of the gas of the total Gulfwide OCS Program. Table 3-4 presents all 

anticipated production from lands currently under lease in the WPA plus all anticipated production from 

future WPA lease sales over the 40-year analysis period. The impact-producing factors, affected 

environment, and environmental consequences related to a WPA proposed lease sale are disclosed in this 

Supplemental EIS and in the prior 2012-2017 Gulf of Mexico EISs. 

CPA Cumulative Scenario: Projected reserve/resource production for the OCS Program in the CPA 

(15.825-21.733 BBO and 63.347-92.691 Tcf of gas) represents anticipated production from lands 

currently under lease in the CPA plus anticipated production from future CPA lease sales over the 40-year 

analysis period. Projected production under the cumulative scenario represents approximately 

85-86 percent of the oil and 83 percent of the gas of the total Gulfwide OCS Program. Table 3-6 of the 

2012-2017 WPA/CPA Multisale EIS presents all anticipated production from lands currently under lease 

in the CPA plus all anticipated production from future CPA lease sales over the 40-year analysis period. 

The impact-producing factors, affected environment, and environmental consequences related to CPA 

proposed lease sales are disclosed in the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 

Supplemental EIS, and CPA 235/241/247 Supplemental EIS.

EPA Cumulative Scenario: Projected reserve/resource production for the OCS Program in the EPA 

(0-0.211 BBO and 0-0.502 Tcf of gas) represents all anticipated production from lands currently under 

lease in the EPA plus all anticipated production from future EPA lease sales over the 40-year analysis 

period. Projected production represents approximately 1 percent of the oil and less than 1 percent of the 

gas of the total Gulfwide OCS Program. Table 3-3 of the EPA 225/226 EIS presents all anticipated 

production from lands currently under lease in the EPA plus all anticipated production from future EPA 

lease sales over the 40-year analysis period. The impact-producing factors, affected environment, and 

environmental consequences related to EPA proposed lease sales are disclosed in the EPA 225/226 EIS.

3.1.1.2. Exploration and Delineation

3.1.1.2.1. Seismic Surveying Operations

Prelease exploration surveys are comprised of geological and geophysical (G&G) surveys performed 

on or off leased areas. The most prevalent surveys used are seismic surveys with airguns/airgun arrays as 
3-6 Western Planning Area Lease Sale 248 Supplemental EIS

acoustic sources, which are focused most commonly (but not always) on deeper targets and are 

collectively authorized under BOEM’s geological and geophysical permitting process. Postlease 

(ancillary) G&G surveys collect data on hazards, drilling, reservoir monitoring, and archaeological 

resources. There are also surficial or near-surface surveys conducted to identify potential shallow 

geologic hazards for geotechnical engineering and site planning for bottom-founded structures. Noise

associated with OCS oil and gas development results from various G&G surveys, the operation of fixed 

structures such as offshore platforms and drilling rigs, and helicopter and service-vessel traffic. These 

noise sources are discussed in Chapter 3.1.1.6 of this Supplemental EIS and in Chapter 3.1.1.6 of the 

prior 2012-2017 Gulf of Mexico EISs. 

WPA Proposed Action Scenario (Typical Lease Sale): Because of the cyclic nature in the acquisition 

of G&G surveys, a prelease airgun survey would be attributable to lease sales held up to 7-9 years after 

the survey was completed. Based on an amalgam of historical trends in G&G permitting and industry 

input, BOEM projects that proposed lease sales within the WPA, CPA, and EPA would result in 

29,197 OCS blocks surveyed by 2D and 3D airgun surveys for the years 2012-2017. This breaks down 

per planning area as follows: WPA ~7,300 blocks; CPA ~21,314 blocks; and EPA ~583 blocks. (Note 

that the number of blocks could include multiple surveys on a single block that would then be counted as 

a unique block survey each time.) For postlease ancillary G&G surveys, information obtained from highresolution seismic contractors operating in the GOM project a proposed action would result in about 

50 vertical seismic profiling (VSP) airgun sourced surveys and 629 non-airgun high-resolution surveys 

covering approximately 226,400 line miles (364,420 km) of near-surface and shallow penetration seismic 

during the life of a proposed action. The impact-producing factors, affected environment, and 

environmental consequences related to WPA proposed lease sales are disclosed and addressed in the prior 

2012-2017 Gulf of Mexico EISs. Chapter 3.1.1.2.1 of the 2012-2017 WPA/CPA Multisale EIS describes 

in detail ocean-bottom surveys. 

OCS Program Cumulative Scenario: The G&G survey activity levels are projected to follow the 

same trend as exploration activities, which peaked in 2008-2010, and are projected to steadily decline 

until 2027 and will remain relatively steady throughout the second half of the 40-year analysis period. It 

is important to note that the cycling of G&G data acquisition is not driven by the 40-year life cycle of 

productive leasing, but instead will tend to respond to new production or potential new production driven 

by new technology. Consequently, some areas will be resurveyed in 2-year cycles, while other areas, 

considered nonproductive, may not be surveyed for 20 years or more. 

Assuming that seismic acquisition will remain the dominant exploration tool used by industry in the 

future and that a number of surveyed blocks will be resurveyed several more times, BOEM makes the 

following projections. During the first 5 years (2012-2017) of the 40-year analysis period (2012-2051), 

BOEM projects the following annual activities: 50 VSP airgun surveys; 226,400 lines miles 

(364,420 km) of non-airgun, high-resolution surveys; and 29,197 3D blocks surveyed by deep-penetration 

airgun arrays, including areas that will be resurveyed. Expanding this analysis to the first 20 years 

(2012-2032), the annual projections would be 60 VSP airgun surveys; 400,000 mi (740,800 km) surveyed 

of non-airgun, high-resolution surveys; and 33,000 blocks of 2D/3D deep-penetration airgun surveys 

(60% in the CPA, 10% in the EPA, and 30% in the WPA). During the second half of the 40-year analysis 

period, the annual projection would be approximately 40 VSP airgun surveys; 240,000 mi (444,480 km) 

surveyed by non-airgun, high-resolution surveys; and 15,000-20,000 blocks surveyed by deep-penetration 

airgun surveys annually (50% in the CPA, 20% in the EPA, and 30% in the WPA). 

3.1.1.2.2. Exploration and Delineation Plans and Drilling

Chapter 3.1.1.2.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail exploration and 

delineation plans and drilling. 

Oil and gas operators use drilling terms that represent stages in the discovery and exploitation of 

hydrocarbon resources. An exploration well generally refers to the first well drilled on a prospective 

geologic structure to confirm that a resource exists. If a resource is discovered in quantities appearing to 

be economically viable and in circumstances when reservoirs are large, one or more follow-up delineation 

wells help define the amount of resource or the extent of the reservoir. Following a discovery, an 

operator will often temporarily plug and abandon a discovery to allow time to generate a development 

scenario and to build or procure equipment. 
Impact-Producing Factors and Scenario 3-7 

In the GOM, exploration and delineation wells are typically drilled with mobile offshore drilling units 

(MODUs), e.g., jack-up rigs, semisubmersible rigs, submersible rigs, platform rigs, or drill ships. 

Non-MODUs, such as inland barges, are also used as drilling rigs. 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 rig availability and daily operation rates play a large role when 

an operator decides upon the type of rig to contract. The depth ranges for exploration rigs used in this 

analysis for the Gulf of Mexico are indicated below.

MODU or Drilling Rig Type Water-Depth Range

Jack-up, submersible, and inland barges ≤100 m (328 ft)

Semisubmersible and platform rig 100-3,000 m (328-9,843 ft)

Drillship ≥600 m (1,969 ft)

Historically, drilling rig availability has been a limiting factor for activity in the GOM and is assumed 

to be a limiting factor for activity projected as a result of a proposed lease sale. Drilling activities may 

also be constrained by the availability of rig crews, shore-based facilities, risers, and other equipment. 

The scenario for a WPA proposed action assumes that an average exploration well will require 

30-120 (mean of 60) 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. This scenario assumes that the 

average exploration or delineation well depth will be approximately 4,572-7,010 m (15,000-23,000 ft) 

below the mudline (i.e., surface of the seafloor).

Some delineation wells may be drilled using a sidetrack technique. In sidetracking a well, a portion 

of the existing wellbore is plugged back to a specific depth, directional drilling equipment is installed, and 

a new wellbore is drilled to a different geologic location. The lessee may use this technology to better 

understand the prospect and to plan future wells. Use of this technology may also reduce the time and 

exploration expenditures needed to help evaluate the prospective horizons on a new prospect. 

The cost of an average exploration well can be $40-$150 million, or more, without certainty that 

objectives can be reached (i.e., an actual discovery and/or confirmation of hydrocarbons). Some recent 

ultra-deepwater exploration wells (>6,000 ft [1,829 m] water depth) in the GOM have been reported to 

cost upwards of $200 million. The actual cost 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.

Subpart D of BSEE’s regulations (30 CFR part 250) specifies requirements for drilling activities. 

Refer to Chapter 1.3.1 of this Supplemental EIS, Chapter 1.3.1 and Table 1-2 of the 2012-2017 

WPA/CPA Multisale EIS, Chapter 1.3.2 of the WPA 233/CPA 231 Supplemental EIS, and Chapter 1.3.1 

of the WPA 238/246/248 Supplemental EIS and WPA 246/248 Supplemental EIS, which provide a 

summary of new and updated safety requirements. 

Tables 3-2 through 3-4 show the estimated range of exploration and delineation wells by waterdepth range for the WPA typical lease sale cases; for the WPA, CPA, and EPA total OCS Program case; 

and for the WPA cumulative cases, respectively.

WPA Proposed Action Scenario (Typical Lease Sale): BOEM estimates that 53-89 exploration and 

delineation wells would be drilled as a result of a WPA proposed action. Table 3-2 shows the estimated 

range of exploration and delineation wells by water-depth range. Approximately 55 percent of the 

projected wells are expected to be on the continental shelf (0-200 m [0-656 ft] water depth), and a little 

less than 45 percent are expected in the intermediate water-depth ranges and deeper (>200 m; 656 ft).

OCS Program Cumulative Scenario (WPA, CPA, and EPA): BOEM estimates that 

6,910-9,827 exploration and delineation wells would be drilled in the WPA, CPA, and EPA as a result of 

all past OCS lease sales and projected activity for future lease sales associated with this Five-Year 

Program. Tables 3-3 and 3-4 of this Supplemental EIS and Table 3-6 of the 2012-2017 WPA/CPA 

Multisale EIS show the estimated range of exploration and delineation wells by water-depth range. Of 

these wells, approximately 55 percent are expected to be on the continental shelf (0-200 m [0-656 ft] 

water depth) and approximately 45 percent are expected in intermediate water-depth ranges and deeper 

(>200 m; 656 ft). Note that offshore and onshore impact-producing factors and scenarios associated with 

a CPA or an EPA proposed action (i.e., a typical lease sale that would result from a proposed action 
3-8 Western Planning Area Lease Sale 248 Supplemental EIS

within the CPA or EPA) as well as OCS Program activity resulting from past and future lease sales in the 

CPA or EPA are disclosed in the 2012-2017 Multisale EIS, WPA 233/CPA 231 Supplemental EIS, CPA 

235/241/247 Supplemental EIS, and EPA 225/226 EIS. 

3.1.1.3. Development and Production

Development and Production Drilling

Following a successful exploration program (i.e., one that results in the discovery of an economically 

viable oil and/or gas field), operators of OCS leases must engage in a series of field development and 

production drilling activities in order to extract the discovered oil and/or gas reserves from the subsurface. 

If, however, the exploration program results in failure, future activity on the lease is minimal and limited 

to short duration activities carried out to plug and permanently abandon the exploration wells drilled on 

the lease.

The initial activity associated with a field development and production drilling program typically is 

the drilling of delineation wells. Delineation wells are drilled to specific subsurface targets in order to 

obtain information about the reservoir that can be used by the operator to identify the lateral and vertical 

extent of a hydrocarbon accumulation. Depending on the information obtained from delineation well 

drilling, these wells can be completed and prepared to serve as production wells. Production wells are 

wells that are drilled following the delineation stage of the development program. The production well is 

drilled specifically for the purpose of extracting hydrocarbons from the subsurface and therefore must be 

positioned within the reservoir in locations where the greatest volume of production can be realized. 

Wells initially drilled as delineation wells that are later converted to production wells and wells drilled as 

production wells are sometimes collectively referred to as development wells.

Following the drilling of development wells, the operator of a field may decide to remain on location 

and immediately begin the next stage of the field development program, i.e., preparing the development 

wells for production. However, there are a number of reasons, for example, when additional well tests are 

required or if the drilling rig is committed to another location, that the operator may decide to move off 

location and delay the work required to prepare the wells for production. When a decision to delay the 

work is chosen, each development well must be temporarily abandoned before the drilling rig can be 

moved to another location. It is also not uncommon for an operator to drill the required number of 

development wells in stages, leaving some time period in between the well drill stages to evaluate the 

information obtained from the wells and, if necessary, use this information to modify the development 

program. 

The process that includes the suite of activities that are carried out to prepare a development well for 

production is the completion process.1

 When the decision is made to perform a well completion, a new 

stage of activity begins. BOEM estimates that approximately 80-90 percent of wells drilled as 

development wells will become producing wells. There is a wide variety of well completion techniques 

performed in the Gulf of Mexico, and the type of well completion used to prepare a drill well for 

production is based on the rock properties of the reservoir as well as the properties of the reservoir fluid. 

However, for the vast majority of well completions, the typical process includes installing or “running” 

the production casing, cementing the casing, perforating the casing and surrounding cement, injecting 

water, brine, or gelled brine as carrier fluid for frac pack/sand proppant pack and gravel pack; 

treating/acidizing the reservoir formation near the wellbore; installing production screens; running 

production tubing; and installing a production tree. Casing is run in the well to prevent the well from 

collapsing. Cement is pumped into the well both to displace drilling fluids that remain in the well and 

also to fill in the space that exists between the casing and the face of the rock formations in the wellbore. 

The casing and cement are perforated adjacent to the reservoir to allow the reservoir fluids to enter the 

wellbore. A gravel pack is a filtration system that is used to prevent sand from entering the wellbore. 

 

1

As described below, there is a wide range of variability in the particular activities that might be used in the 

completion process depending on the specific characteristics of the well. Many of the terms used to describe these 

activities (e.g., fracking and acidization) do not have precise, fixed definitions in all contexts. Accordingly, two 

very different processes with different potential environmental impacts may both be called by the same name. For 

these reasons, the description of these activities in this chapter is meant to be a general description of the range of 

activities that may be involved in well completion.
Impact-Producing Factors and Scenario 3-9 

Well treatment, such as acidizing, is used to improve the flow of reservoir fluids into the wellbore by 

cleaning out and/or dissolving debris that accumulates in the wellbore and near-wellbore reservoir 

formation as a result of the drilling process. For moderate to high permeability reservoirs, today’s most 

technologically advanced well treatment and stimulation processes are designed not only to mitigate nearwellbore formation damage issues but also to serve as another mechanism to help control the flow of sand 

into the wellbore and to enhance the flow rate of the well. Production tubing is run inside the casing. 

Production tubing protects the casing from wear and corrosion, and it provides a continuous conduit for 

the reservoir fluid to flow from the reservoir to the wellhead. The production tree is a wellhead device 

that is used to control, measure, and monitor the conditions of the reservoir and the well from the surface. 

A commonly used development well completion and stimulation technique that has been used in the 

Gulf of Mexico for more than 25 years is the “frac pack” completion process. This completion technique, 

which is typically used for moderate to high permeability reservoirs, is used to reduce the movement of 

sand and other fine particulate matter within the reservoir, reduce the concentration of sand and silt in the 

produced fluids, improve the flow of reservoir fluids into the wellbore, increase production rates, and 

maximize production efficiency. The frac pack completion process uses pressurized fluids, typically 

seawater, brine, or gelled brine, to create small fractures in the reservoir rock within a zone near the 

wellbore where the reservoir’s permeability was damaged by the drilling process. The pressurized highdensity, gelatin-like fluid also serves as the carrier agent for the mechanical agent or proppant that is 

mixed with the completion fluids. The mechanical agents, typically sand, manmade ceramics, or small 

microspheres (tiny glass beads), are injected into the small fractures and remain lodged in the fractures 

when the process is completed. The proppant serves to hold the fractures open allowing them to perform 

as conduits to assist the flow of hydrocarbons from the reservoir formation to the wellbore. Well 

treatment chemicals are also commonly used to improve well productivity. For example, acidizing a 

reservoir to dissolve cementing agents and improve fluid flow is a common well treatment procedure in 

the GOM.

In contrast to the large-scale, induced hydraulic fracturing procedures, commonly referred to as 

“fracking,” used in onshore oil and gas operations for low-permeability “tight gas,” “tight oil,” and “shale 

gas,” reservoirs, the vast majority of hydraulic fracturing treatments carried out on the OCS in the GOM 

are “frac packs,” which are small-scale by comparison and most commonly used for high-permeability 

formations to reduce the concentration of sand and silt in the produced fluids and to maintain high flow 

rates. Since damage to the formation caused by drilling operations does not extend for large distances 

away from the reservoir-borehole interface, the fracturing induced by the procedure is also designed to 

remain in close proximity to the borehole, extending distances of typically 15-30 m (49-98 ft) from the 

borehole (Sanchez and Tibbles, 2007).

Additives used in fracture-pack operations are often similar, if not identical, to those used for shale or 

tight sand development onshore and they are used for similar purposes. The concentrations of some of 

these additives are typically different due to the GOM’s very different geologic characteristics of the 

producing formation. The most significant difference is that the GOM typically has much higher 

formation permeabilities and the lower amounts of clay/shale in typical formations (API, 2015). Another 

factor that can significantly influence additive selection and use in offshore operations is the ability to 

discharge treated wastewaters that meet applicable regulatory requirements (API, 2015). 

Boehm et al. (2001) notes 24 functional categories of additives and 2 categories of proppants used 

offshore in the GOM for fracturing activities:
3-10 Western Planning Area Lease Sale 248 Supplemental EIS

— water-based polymers

— defoamers

— friction reducers

— oil gelling additives

— fluid loss additives (FLAs)

— biocides 

— breakers 

— acid-based gel systems

— emulsifiers 

— water-based systems

— clay stabilizers 

— crosslinked gel systems

— surfactants

— alcohol/water systems

— non-emulsifiers 

— oil-based systems

— pH control additives 

— polymer plugs 

— crosslinkers 

— continuous mix gel concentrates

— foamers 

— resin-coated proppants 

— gel stabilizers 

— intermediate-to-high strength ceramic 

proppants 

Each of these is described in greater detail in the Boehm et al. (2001) study, along with other 

treatment and completion chemicals. The appendix to the study even offers a chemical inventory with 

example products and Material Safety Data Sheets for those products. In general, discharges of any 

fluids, including those associated with well completion, are subject to the terms of National Pollution 

Discharge Elimination System (NPDES) permits issued by the USEPA under the Clean Water Act. 

These permits place limitations on the toxicity of all effluents, as well as other requirements for 

monitoring and reporting. Wastes and discharges generated from OCS oil- and gas-related activities, 

including produced water and well completion fluids, are addressed programmatically by BOEM in 

Chapters 3.1.1.4 and 3.1.2.2.3 of the 2012-2017 WPA/CPA Multisale EIS, from which this Supplemental 

EIS is tiered.

During a frac pack, the pumping equipment, sand (proppant) and additives are carried, mixed, and 

pumped from a specialized stimulation and treatment vessel. The base fluid that is used for the frac-pack 

operation will typically be treated seawater, although other brines may be used if conditions dictate (API, 

2015). BOEM considers these large special purpose vessels (supporting fracturing operations) as offshore 

supply/service vessels (OSVs). In Table 3-2, the number of OSV trips is estimated by subareas (range of 

water depths) in the GOM. Potential impacts associated with OSVs are described in various sections 

throughout the documents including operational wastes, noise, and air emissions related to vessel 

movement throughout the GOM. 

What is explained above is a general procedure for frac-pack operation, but every fracturing job is 

case specific. In general, the fracturing process remains the same but chemical formulations, fluid and 

proppant volumes, pump time, and pressure will vary based on the depth and engineering/geologic 

parameters for a particular well completion. After a production test determines the desired production 

rate to avoid damaging the reservoir, the well is ready to go online and produce. 

The development operations and coordination document (DOCD) is the chief planning document that 

lays out an operator’s specific intentions for development. Chapter 3.1.1.3.1 of the 2012-2017 WPA/CPA 

Multisale EIS describes in detail DOCDs related to a WPA proposed action. The range of postlease 

development plans is discussed in Chapter 1.5 of the 2012-2017 WPA/CPA Multisale EIS and WPA 

233/CPA 231 Supplemental EIS. Table 3-2 shows the estimated range of development wells and 

production structures by water-depth subarea for a WPA proposed action. 

WPA Proposed Action Scenario (Typical Lease Sale): BOEM estimates that 77-121 development and 

production wells would be drilled as a result of a WPA proposed action. Table 3-2 shows the estimated 

range of development and production wells by water-depth subarea. Approximately 55 percent of the 

projected wells (oil and gas combined) are expected to be on the continental shelf (0-200 m [656 ft] water 

depth) and 45-47 percent are expected in intermediate water-depth ranges and deeper (>200 m; 656 ft). 

Trends between the oil and gas development wells are markedly different. For the 27-40 oil wells 

projected as a result of a WPA proposed action, 55-60 percent of those wells fall within the intermediate 

water-depth ranges and deeper (200-1,600 m; 656-5,249 ft). The percent of oil wells in the other waterdepth categories each range from around 7 to 15 percent. For 36-62 gas wells projected as a result of a 

WPA proposed action, nearly 80 percent of gas wells are projected to be located on the continental shelf 

(0-200 m [0-656 ft] water depth). The percent of gas wells in the other water-depth categories is much 

less, and each range from 3 to 6 percent.
Impact-Producing Factors and Scenario 3-11

OCS Program Cumulative Scenario (WPA, CPA, and EPA): It is estimated that 8,530-12,180 

development and production wells will be drilled in the WPA, CPA, and EPA as a result of the proposed 

lease sales and all OCS oil- and gas-related activity associated with previous lease sales. Table 3-3

shows the estimated range of development wells by water depth.

The 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, CPA 235/241/247 

Supplemental EIS, and EPA 225/226 EIS detail the offshore and onshore impact-producing factors and 

scenarios associated with a CPA or an EPA proposed action, i.e., a typical lease sale that would result 

from a proposed action within the CPA or EPA, as well as OCS Program activity resulting from past and 

future lease sales in the CPA or EPA.

Infrastructure Emplacement/Structure Installation and Commissioning Activities

Chapter 3.1.1.3.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail infrastructure

emplacement/structure installation and commissioning activities.

Bottom-founded or floating structures may be placed over development wells to facilitate production 

from a prospect. These structures provide the means to access and control the wells. They serve as a 

staging area to process and treat produced hydrocarbons from the wells, initiate export of the produced 

hydrocarbons, conduct additional drilling or reservoir stimulation, conduct workover activities, and carry 

out eventual abandonment procedures. There is a range of offshore infrastructure installed for 

hydrocarbon production. Among these are pipelines, fixed and floating platforms, caissons, well 

protectors, casing, wellheads, and conductors. 

WPA Proposed Action Scenario (Typical Lease Sale): It is estimated that 15-23 production structures 

will be installed as a result of a WPA proposed action. Table 3-2 shows the projected number of 

structure installations for a WPA proposed action by water-depth range. About 67-74 percent of the 

production structures installed for a WPA proposed action are projected to be on the continental shelf 

(0-60 m; 0-197 ft). 

OCS Program Cumulative Scenario (WPA, CPA, and EPA): It is estimated that 1,435-2,026 

production structures would be installed in the WPA, CPA, and EPA as a result of the proposed lease 

sales and all OCS oil- and gas-related activity associated with previous lease sales. Tables 3-2 and 3-3 of 

this Supplemental EIS and Table 3-6 of the 2012-2017 WPA/CPA Multisale EIS show the projected 

number of structure installations by water-depth range for the OCS Program. 

The 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, CPA 235/241/247 

Supplemental EIS, and EPA 225/226 EIS detail the offshore and onshore impact-producing factors and 

scenarios associated with a CPA or an EPA proposed action, i.e., a typical lease sale that would result 

from a proposed action within the CPA or EPA, as well as OCS Program activity resulting from past and 

future lease sales in the CPA or EPA.

Bottom Area Disturbance

Chapter 3.1.1.3.2.1 of the 2012-2017 WPA/CPA Multisale EIS describes in detail bottom area

disturbances. Structures emplaced or anchored on the OCS to facilitate oil and gas exploration and 

production include drilling rigs or MODUs (jack-ups, semisubmersibles, and drillships), pipelines, and 

fixed surface, floating, and subsea production systems, and are described in Chapter 3.1.1.3 of this 

Supplemental EIS and in Chapters 3.1.1.3.1 and 3.1.1.3.2 of the 2012-2017 WPA/CPA Multisale EIS. 

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 the facilities’ 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.
3-12 Western Planning Area Lease Sale 248 Supplemental EIS

Sediment Displacement

Chapter 3.1.1.3.2.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail sediment 

displacement. Displaced sediments are those that have been physically moved “in bulk.” Displaced 

sediments will cover or bury an area of the seafloor, while resuspended sediments will cause an increase 

in turbidity of the adjacent water column. Resuspended sediments eventually settle, covering the 

surrounding seafloor. Resuspended sediments may include entrained heavy metals or hydrocarbons. 

Infrastructure Presence

Chapter 3.1.1.3.3 of the 2012-2017 WPA/CPA Multisale EIS describes in detail impact-producing 

factors due to infrastructure presence. The installation and maintenance of infrastructure may include, but 

is not limited to, the following:

• anchoring; 

• offshore production systems; 

• space-use requirements (deployment of survey equipment or bottom-founded 

production equipment); 

• aesthetic quality (presence and visibility of equipment, vessels, and air traffic); and

• workovers and abandonments. 

3.1.1.4. Operational Waste Discharged Offshore

Chapter 3.1.1.4 of the 2012-2017 WPA/CPA Multisale EIS describes in detail the impacting factors 

related to operational wastes discharged offshore, and Chapter 3.1.1.4 of the WPA 233/ CPA 231 

Supplemental EIS provides a summary as well as detailed updated information on more recent, stricter 

regulations regarding vessel discharges. Operational wastes discharged offshore include the following:

• drilling muds and cuttings; 

• produced waters; 

• well treatment, workover, and completion fluids; 

• production solids and equipment; 

• bilge, ballast, and fire water; 

• cooling water; 

• deck drainage;

• treated domestic and sanitary wastes; 

• minor discharges; 

• vessel operational discharges; and

• distillation and reverse osmosis brine.

BOEM maintains records of the volume of produced water from each block on the OCS and its 

disposition―injected on lease, injected off lease, transferred off lease, or discharged overboard. The 

amount discharged overboard for the years 2000-2014 is summarized by water depth in Table 3-5 with 

new data provided for the year 2014, as well as any updates available for past years. The total volume of 

produced water for all water depths during this 14-year period ranged from 485.6 to 648.2 MMbbl, with 

the largest contribution (68-88%) coming from operations on the shelf. The total volume of produced 

water generally decreased after 2004, reflecting an overall decrease in contributions from operations on 
Impact-Producing Factors and Scenario 3-13

the shelf. The contribution of produced water from operations in deep water (>400-m [1,312-ft] water 

depth) and ultra-deepwater (>1,600-m [5,249-ft] water depth) production has been increasing. From 2000 

to 2014, the contribution from these operations (deep and ultra-deepwater together) increased from 

6 percent (37.8 MMbbl) to 31 percent (150.0 MMbbl) of the total produced-water volume (calculated 

from data in Table 3-5). The updated annual amounts and depth distributions of produced water 

discharged by depth are within the range of or similar to data presented in the 2012-2017 WPA/CPA 

Multisale EIS and WPA 233/CPA 231 Supplemental EIS. Thus, this new information did not change the 

validity of the operational wastes discussion previously presented. 

3.1.1.5. Air Emissions

In 1990, pursuant to Section 328 of the Clean Air Act Amendments and following consultation with 

the Commandant of the U.S. Coast Guard (USCG) and the Secretary of the Interior, the U.S. 

Environmental Protection Agency (USEPA) assumed air quality responsibility for the OCS waters east of 

87.5o W., this Agency retained National Ambient Air Quality Standards (NAAQS) air quality jurisdiction 

for OCS operations west of the same longitude in the GOM. However, in 2014, BOEM’s air quality 

regulations underwent a comprehensive review to replace obsolete provisions and to ensure that updates 

in regulations are following improvements in scientific and technological information. BOEM’s air 

quality regulations update is expected to be published within the next 2 years as of the publication date of 

this Supplemental EIS.

There are many air emissions sources related to OCS oil and gas exploration, development, and 

production in the GOM. During the exploration stage, most of the OCS non-platform emissions are from 

combustion from the equipment used on a drilling rig or from fuel usage of a support vessel. During the 

production stage, platform emission sources include boilers, diesel engines, combustion flares, fugitives, 

glycol dehydrators, natural gas engines, turbines, pneumatic pumps, pressure/level controllers, storage 

tanks, cold vents, and others. During the development stage, most of the OCS non-platform emissions are 

from fuel usage of support or survey vessels to lay pipelines, install facilities, or map geologic formations 

and seismic properties.

Pollutants released by OCS sources include the NAAQS pollutants carbon monoxide (CO), nitrogen 

oxides (NOx), particulate matter (PM), and sulfur dioxide (SO2). Certain pollutants also released by OCS 

sources (NOx and volatile organic compounds [VOC]) are also precursors to ozone, which is formed by 

photochemical reactions in the atmosphere and is another NAAQS pollutant. Lastly, OCS sources release 

greenhouse gas emissions, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).

The Year 2011 Gulfwide Emissions Inventory Study (Wilson and Boyer, 2014) indicates that OCS oil 

and gas production platform and non-platform sources emit the majority of criteria pollutants and 

greenhouse gases in the GOM on the OCS, with the exception of SO2 (primarily emitted from commercial 

marine vessels), and N2O (from biological sources). The OCS oil and gas production platform and 

non-platform sources account for 90 percent of the total CO emissions, 73 percent of NOx emissions, 

68 percent of PM10 emissions, 42 percent of SO2 emissions, 63 percent of VOC emissions, and 85 percent

of the greenhouse gas emissions. Similar to the 2008 Inventory (Wilson et al., 2010), natural gas engines 

on platforms represented the largest CO emission source, accounting for 47 percent of the total estimated 

CO emissions; and support vessels were the highest emitters of both NOx and PM10, accounting for 

37 percent and 42 percent of the total estimated emissions. Oil and natural gas production platform vents 

account for the highest percentage (29%) of the VOC emissions. Support vessels (32% of total 

emissions); production platform natural gas, diesel, and dual-fuel turbines (18% of total emissions); and 

commercial marine vessels (11% of total emissions) emit the majority of the greenhouse gas emissions.

3.1.1.6. Noise

Noise associated with OCS oil and gas development results from seismic surveys, the operation of 

fixed structures such as offshore platforms and drilling rigs, and helicopter and service-vessel traffic. 

Noise generated from these activities can be transmitted through both air and water, and may be 

long-lived or temporary. Offshore drilling and production involve various activities that produce a 

composite underwater noise field. The intensity level and frequency of the noise emissions are highly 

variable, both between and among the various industry sources. Noise from proposed OCS oil- and 

gas-related activities may affect resources near the activities. Whether a sound is or is not detected by 
3-14 Western Planning Area Lease Sale 248 Supplemental EIS

marine organisms depends both on the acoustic properties of the source (spectral characteristics, intensity, 

and transmission patterns) and the sensitivity of the hearing system in the marine organism. Noise can 

cause varying degrees of harassment to an exposed animal and may cause “take” of endangered and 

threatened species as defined in the Endangered Species Act of 1973 (ESA). Source levels within hearing 

thresholds may alter hearing or induce behavioral changes (Richardson et al., 1995). Chapter 3.1.1.6 of 

the 2012-2017 WPA/CPA Multisale EIS describes in detail noise impact-producing factors associated 

with OCS oil and gas development. 

3.1.1.7. Major Sources of Oil Inputs in the Gulf of Mexico

Petroleum hydrocarbons can enter the GOM from a wide variety of sources. The major sources of oil 

inputs in the GOM are natural seepage, permitted produced-water discharges, land-based discharges, and 

accidental spills. Numerical estimates of the contributions for these sources to the GOM coastal and 

offshore waters are shown in Tables 3-8 and 3-9 of the 2012-2017 WPA/CPA Multisale EIS. Chapter 

3.1.1.7 of the 2012-2017 WPA/CPA Multisale EIS describes in detail major sources of oil inputs in the 

Gulf of Mexico, including natural seepage, produced water, land-based discharges, and spills.

Chapter 3.1.1.7.4 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 3.1.1.7 of the WPA 

238/246/248 Supplemental EIS also provide the following information related to oil spills: 

• trends in reported spill volumes and numbers; 

• projections of future spill events;

• OCS oil- and gas-related offshore oil spills; 

• non-OCS oil- and gas-related offshore spills; 

• OCS oil- and gas-related coastal spills; 

• non-OCS oil- and gas-related coastal spills; and

• other sources of oil.

3.1.1.8. Offshore Transport

Offshore transport includes both movements of oil and gas products, as well as the transportation of 

equipment and personnel. Chapter 3.1.1.8 of the 2012-2017 WPA/CPA Multisale EIS describes in detail 

sources of offshore transport and proposed action scenarios, including pipelines (installation and 

maintenance; landfalls), barges, oil tankers, and projections related to floating production, storage, and 

offloading systems, service vessels, and helicopter trips. Updated information on total traffic (OCS- and 

non-OCS Program-related) on navigation channels for 2011 can be found in Table 3-7 of the WPA 

238/246/248 Supplemental EIS. This information did not alter the projections or conclusions made in the 

prior 2012-2017 Gulf of Mexico EISs. 

3.1.1.9. Safety Issues

Safety issues related to OCS oil and gas development include the presence of hydrogen sulfide and 

sulfurous petroleum and shallow hazards. These safety issues are described in detail in Chapters 3.1.1.9.1 

and 3.1.1.9.2 of the 2012-2017 WPA/CPA Multisale EIS. Technologies continue to evolve to meet the 

technical, environmental, and economic challenges of deepwater development. These new and unusual 

technologies are described in Chapter 3.1.1.9.3 of the 2012-2017 WPA/CPA Multisale EIS.

3.1.1.10. Decommissioning and Removal Operations

During exploration, development, and production operations, the seafloor around activity sites within 

a proposed lease sale area becomes the repository of temporary and permanent equipment and structures. 

In compliance with Section 22 of BOEM’s Oil and Gas Lease Form (BOEM-2005) and BSEE regulations 

(30 CFR §§ 250.1710 et seq.—Permanently Plugging Wells and 30 CFR §§ 250.1725 et seq.—Removing 

Platforms and Other Facilities), lessees are required to remove all seafloor obstructions from their leases 
Impact-Producing Factors and Scenario 3-15

within 1 year of lease termination or relinquishment. These regulations require lessees to sever bottomfounded 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. The 

structures are generally grouped into two main categories depending upon their relationship either to the 

platform/facility (piles, jackets, caissons, templates, mooring devises, etc.) or to the well (wellheads, 

casings, casing stubs, etc.). Decommissioning and removal operations, including a WPA proposed action 

and OCS Program scenarios, are described in detail in Chapter 3.1.1.10 of the 2012-2017 WPA/CPA 

Multisale EIS.

3.1.2. Coastal Impact-Producing Factors and Scenario

3.1.2.1. Coastal Infrastructure

A full description of coastal impact-producing factors and scenario is presented in the 2012-2017 

WPA/CPA Multisale EIS. No new significant information was discovered that would alter impact 

conclusions based upon these operations. The following is a summary. For more details, refer to Chapter 

3.1.2 of the prior 2012-2017 Gulf of Mexico EISs, which describes coastal impact-producing factors. 

These coastal impact-producing factors could potentially affect the biological, physical, and 

socioeconomic resources of the GOM. Chapter 3.1.2.1 of the prior 2012-2017 Gulf of Mexico EISs

provides a summary as well as detailed updated information on OCS oil- and gas-related coastal 

infrastructure types, which include the following, but are not limited to: 

• service bases; 

• coastal pipelines

• terminals;

• processing facilities;

• helicopter hubs; 

• processing facilities;

• coastal barging; and 

• navigation channels (refer to the updated information on navigation channels in 

Table 3-7 of the WPA 238/246/248 Supplemental EIS). 

This OCS oil- and gas-related infrastructure has been developed over many decades, and it is an 

extensive and mature system that provides support for offshore activities. The expansive presence of this 

coastal infrastructure is the result of long-term industry offshore and onshore trends and is not subject to 

rapid fluctuations. The routine activities of built infrastructure associated with a WPA proposed action are 

regulated by Federal and State agencies through permitting processes, routine inspections, and a 

structured enforcement regime. Permit requirements largely mitigate any air and water quality impacts 

that can result from these activities. Because these impacts occur whether a WPA proposed action is 

implemented or not, a WPA proposed action would account for only a small percentage of these impacts. 

A detailed description of the baseline affected environment for land use and coastal infrastructure in the 

WPA can be found in Chapter 4.1.1.20.1 of this Supplemental EIS, Chapter 4.1.1.20.1.1 of the 

2012-2017 WPA/CPA Multisale EIS, and Chapter 4.1.1.20.1 of the WPA 233/CPA 231 Supplemental 

EIS WPA 238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. 

BOEM projects no new coastal infrastructure with the exception of up to one new pipeline landfall 

and up to one new gas processing facility as a result of an individual proposed action. While offshore 

projects may add additional miles of pipeline to transport product, it is not likely that these projects would 

transport natural gas or crude oil directly onshore, but rather interconnect with existing systems. 

Generally, it is more cost effective for companies to tie into the existing offshore pipeline network. 

Pipeline safety regulations govern the entire life of pipeline operations, including design, construction, 

inspection, recordkeeping, worker qualification, and emergency preparedness; and any new pipeline 

landfalls would be subject to regulatory requirements. Because of the long timelines associated with the 
3-16 Western Planning Area Lease Sale 248 Supplemental EIS

Gulf of Mexico projects, the late 2014/early 2015 downturn in oil prices is expected to a have minimal 

direct impact on GOM crude oil production through 2016. The U.S. Energy Information Administration 

projects GOM production to reach 1.52 MMbbl per day in 2015 and 1.61 MMbbl per day in 2016, or 

about 16 percent and 17 percent of total U.S. crude oil production in those 2 years. The current low oil 

prices add uncertainty to the timelines of deepwater GOM projects, with projects in early development 

stages exposed to the greatest risk of delay (USDOE, Energy Information Administration, 2015h).

Chapter 3.1.2.1 of the prior 2012-2017 Gulf of Mexico EISs describes the activities and coastal 

impact factors of the following infrastructure types in the GOM. The GOM ports vary considerably by 

size, specialty, and defining characteristics. In general, however, there are two major types of port 

facilities: deep-draft seaports and inland river and intra-coastal waterways port facilities. A service base

is a community of businesses that load, store, and supply equipment, supplies, and personnel that are 

needed at offshore work sites. Service bases can range from large yards offering a range of services that 

include full logistics management to smaller shops that supply one or many of the items needed on an 

offshore platform or marine vessel (Dismukes, 2011). While no proposed action is projected to 

significantly change existing OCS oil- and gas-related service bases or ports, or require any additional 

ports or service bases, the WPA proposed action would contribute to the use of these coastal 

infrastructure types. Round-trip service vessel trips as a result of the WPA proposed action are projected 

between 64,000 and 75,000 trips over the 40-year planning period (Table 3-2). For a more in-depth 

discussion of service vessels, refer to Chapter 3.1.1.8. Much of the record U.S. growth in oil and gas 

output is transiting through Houston, the country’s largest export gateway and home to the greatest 

concentration of refineries and petrochemical plants in the United States. Coast Guard data show that an 

average day on the Houston Ship Channel in 2013 saw 38 tankers, 22 freighters, 1 cruise ship, 

345 towboats, 6 public vessels, 297 ferries, 25 other transits, and 75 ships in port (Arnsdorf, 2014). Oil 

production companies have scaled back onshore drilling in response to late 2014/early 2015 falling oil 

prices, and some construction has been temporarily delayed for “downstream” petrochemical 

manufacturing plants. But these plants, some of which represent multibillion-dollar capital investments, 

are long-term projects that are largely immune to short-term fluctuations in energy prices. In recent years, 

companies have announced some $35 billion in new or expanded petrochemical investments along the 

Houston Ship Channel. Several of those projects are set to open in 2016 and 2017. They are being built 

primarily to supply export markets (Bonney, 2015). Depressed oil prices have also encouraged company 

consolidation and reorganization, allowing companies to pursue new efficiencies. For instance, Valero 

Energy Partners LP announced the acquisition of refined petroleum terminals in Houston and Louisiana. 

Valero Partners Houston LLC operates a crude oil, intermediates, and refined petroleum products 

terminal located on the Houston Ship Channel; this terminal supports Valero Energy Partners’ Houston 

refinery and consists of storage tanks with 3.6 MMbbl of storage capacity. Valero Partners Louisiana 

LLC operates a crude oil, intermediates, and refined petroleum products terminal located on the 

Mississippi River in Norco, Louisiana; this terminal supports the partnership’s St. Charles, Louisiana,

refinery and consists of storage tanks with 10 MMbbl of storage capacity (Zack’s Equity Research, 2015).

If activity levels increase, it is reasonable to assume that these facilities will expand to meet demand. 

Helicopter hubs or “heliports” are facilities where helicopters can land, load, and offload passengers and 

supplies, refuel, and be serviced. These hubs are used primarily as flight support bases to service the 

offshore oil and gas industry. Most of the helicopter operations originate at helicopter hubs in coastal 

Texas and Louisiana. There are 233 identified heliports within the analysis area that support OCS 

oil- and gas-related activities; that is, 118 in Texas and 115 in Louisiana (Dismukes, 2011). Helicopter 

operations for a WPA proposed action are projected between 290,000 and 605,000 round-trip operations 

over the 40-year planning period (Table 3-2). No new heliports are projected as a result of the OCS 

Program; however, if activity levels increase, current locations may expand. 

The U.S. Energy Information Administration updates national energy projections annually, including 

refinery capacity. A crude oil refinery is a group of industrial facilities that turns crude oil and other 

inputs into finished petroleum products. A refinery’s capacity refers to the maximum amount of crude oil 

designed to flow into the distillation unit of a refinery, also known as the crude unit. Most of the GOM 

region’s refineries are located in Texas and Louisiana (Table 3-13 of the 2012-2017 WPA/CPA Multisale 

EIS). Texas has 27 operable refineries, with an operating capacity of over 5.1 MMbbl/day, which is over 

28 percent of the total U.S. capacity. Louisiana follows closely behind Texas, with 19 operable refineries, 

with an operational capacity of over 3.27 MMbbl/day, which is 18 percent of the total U.S. capacity 

(USDOE, Energy Information Administration, 2014). The estimated amounts of crude oil projected to be 
Impact-Producing Factors and Scenario 3-17

leased, discovered, developed, and produced as a result of a typical proposed WPA lease sale are between 

0.116 and 0.200 BBO (Table 3-1 of the 2012-2017 WPA/CPA Multisale EIS ), which would require only 

0.09-0.16 percent of the current combined Texas and Louisiana refinery capacity over the 40-year 

planning period. 

3.1.2.2. Discharges and Wastes

Chapter 3.1.2.2 of the 2012-2017 WPA/CPA Multisale EIS describes in detail coastal discharges and 

wastes and Chapter 3.1.2.2 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS provide a summary and updates to coastal 

discharges and wastes, which include the following: 

• disposal and storage for offshore operational wastes; 

• onshore facility discharges; 

• coastal service-vessel discharges; 

• offshore wastes disposed onshore; and

• beach trash and debris. 

The USEPA, through general permits issued by the USEPA Region with jurisdictional oversight, 

regulates all waste streams generated from offshore oil and gas activities. The USEPA Region 6 has 

jurisdiction over the CPA off the Louisiana coast and all of the WPA. The USEPA Region 4 has 

jurisdiction over the eastern portion of the GOM, including all of the EPA and part of the CPA off the 

coasts of Alabama and Mississippi. Each region has promulgated general permits for discharges that 

incorporate the 1993 effluent guidelines as a minimum. In some instances, a site-specific permit is 

required. The USEPA also regulates vessel discharges with the Vessel General Permit (VGP), which is a 

Clean Water Act National Pollutant Discharge Elimination System (NPDES) permit that authorizes, on a 

nationwide basis, discharges incidental to the normal operation of nonmilitary and nonrecreational vessels 

greater than or equal to 79 ft (24 m) in length. On March 28, 2013, USEPA reissued the 2008 VGP for 

another 5 years; the reissued permit, the 2013 VGP, now contains numeric ballast water discharge limits 

for most vessels. The VGP also contains more stringent effluent limits for oil-to-sea interfaces and 

exhaust gas scrubber washwater (USEPA, 2013a). The VGP, geographically, covers inland waters out to 

3 mi (5 km) and applies to vessels acting as a means of transportation. If the vessel is moored to a rig 

generating an amount of water that is greater than what it takes for the normal operation of a vessel, the 

VGP would not apply to brine production. As of early March 2015, a bipartisan effort to establish a 

uniform national framework for the regulation of vessel discharges took another step forward as the 

Senate Committee on Commerce, Science, and Transportation approved Senate Bill 373, the Vessel 

Incidental Discharge Act. This measure would replace a patchwork of overlapping and conflicting 

Federal and State regulations with a uniform Federal framework for vessel discharge regulation 

(MarineLog, 2015). 

The BSEE policy regarding marine debris prevention is outlined in NTL 2012-JOINT-G01, “Marine 

Trash and Debris Awareness and Elimination.” The NTL instructs OCS operators to post informational 

placards that outline the legal consequences and potential ecological harms of discharging marine debris. 

The NTL also states that OCS workers should complete annual marine debris prevention training and 

instructs operators to develop a certification process for the completion of this training by their workers. 

These various laws, regulations, and NTL will likely minimize the discharge of marine debris from OCS 

operations. 

3.2. IMPACT-PRODUCING FACTORS AND SCENARIO—ACCIDENTAL EVENTS

3.2.1. Oil Spills

Oil spill occurrence cannot be predicted, but an estimate of its likelihood can be quantified using spill 

rates derived from historical data and projected volumes of oil produced and transported. The following 

sections discuss spill prevention and spill response, and analyze the risk of spills that could occur as a 
3-18 Western Planning Area Lease Sale 248 Supplemental EIS

result of activities associated with a WPA proposed action. Public input through public scoping meetings, 

Federal and State agencies’ input through consultation and coordination, and industry and 

nongovernmental organizations’ input indicate that oil spills are perceived to be a major concern. The 

following discussion analyzes the risk of spills that could occur as a result of a typical WPA proposed 

action, as well as information on the number and sizes of spills from non-OCS oil- and gas-related 

sources. Although not reasonably expected as a result of a WPA proposed action, the potential 

occurrence of a catastrophic spill is exceedingly low (Ji et al., 2014), but it cannot be ruled out entirely; 

refer to Appendix B of the WPA 246/248 Supplemental EIS for the “Catastrophic Spill Event Analysis.”

3.2.1.1. Spill Prevention

Over the years, comprehensive pollution-prevention requirements that include redundant safety 

systems, as well as inspection and testing requirements to confirm that these devices are working properly 

(Chapter 1.5). Until the Deepwater Horizon oil spill, an overall reduction in spill volume had occurred 

during the previous 40 years, while oil production had generally increased. A characterization of spill 

rates, average and median volumes from 1995 to 2009 compared with 1996 to 2010, which includes the 

Deepwater Horizon oil spill, is provided in Update of Occurrence Rates for Offshore Oil Spills (Anderson 

et al., 2012). BOEM attributes this improvement to its operational requirements, ongoing efforts by the 

oil and gas industry to enhance safety and pollution prevention, and the evolution and improvement of 

offshore technology. 

3.2.1.2. Past OCS Spills

The BSEE spill-event database includes records of past spills from activities that are regulated by 

BSEE. These data include oil spills >1 bbl that occurred in Federal waters from OCS facilities and

pipeline operations. Spills from facilities include spills from drilling rigs, drillships, and storage, 

processing, or production platforms that occurred during OCS drilling, development, and production 

operations. Spills from pipeline operations are those that have occurred on the OCS and are directly 

attributable to the transportation of OCS oil. Anderson et al. (2012) was utilized in the 2012-2017 

WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, and WPA 238/246/248 Supplemental 

EIS to characterize spill rates and to provide analysis for average and median volumes. The analysis by 

Anderson et al. (2012) examined spill data for the period 1964 to 2010, including the Deepwater Horizon

oil spill.

A search of BSEE’s oil-spill database (USDOI, BSEE, 2013) was performed to assess new spill 

information and to provide an update to the Anderson et al. (2012) analysis. The most recent data 

available provide additional information for the period 2011 to 2013, during which 46 spills from OCS 

oil- and gas-related activities of <1,000 bbl in size were reported. The breakdown of the 46 spills 

<1,000 bbl that occurred from 2011 to 2013 from OCS oil- and gas-related activities is as follows: 

28 spills of 1-4 bbl; 6 spills of 5-9 bbl; 10 spills of 10-49 bbl; 1 spill of 50-99 bbl; 1 spill of 100-999 bbl; 

and 0 spills of ≥1,000 bbl. The combined total of oil spilled in these 46 events was 857 bbl. This is an 

outcome that is within the range of spills estimated to occur in Table 3-12 of the 2012-2017 WPA/CPA 

Multisale EIS, which serves as an estimate of the number and size of spills likely to occur as a result of a 

WPA proposed action over a 40-year time period. Thus, the additional information provided by the 

review of BSEE’s oil-spill database (USDOI, BSEE 2013) did not change the validity of the scenario 

previously presented. 

The majority of the 2011-2013 spills are attributed to OCS platforms/rigs, followed by vessels, and 

lastly by OCS pipelines. These data were compared with the estimated number and sizes of spills 

presented in Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS (derived in part from Anderson et al., 

2012), and it was found that the new spill data were within the spill numbers estimated in the 2012-2017 

WPA/CPA Multisale EIS. The new data also concurred with the previous finding that the most likely 

source of a spill <1,000 bbl would be from platforms, rigs, or vessels. Thus, a review of recent 

information does not change the risk analyses for spills <1,000 bbl previously provided in the prior 

2012-2017 Gulf of Mexico EISs. As estimated in Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS, 

no spills have occurred in the ≥1,000-bbl size class.
Impact-Producing Factors and Scenario 3-19

3.2.1.3. Characteristics of OCS Oil

The physical and chemical properties of oil greatly affect its transport and ultimate fate in the 

environment and determine the following: how oil will behave on the water surface (surface spills) or in 

the water column and sediments (subsea spills); the persistence of the slick on the water; the type and 

speed of weathering processes; the degree and mechanisms of toxicity; the effectiveness of containment 

and recovery equipment; and the ultimate fate of the spill residues. Crude oils are a natural mixture of 

hundreds of different compounds, with liquid hydrocarbons accounting for up to 98 percent of the total 

composition. The chemical composition of crude oil can vary significantly from different producing 

areas; thus, the exact composition of oil being produced in OCS waters varies throughout the Gulf. The 

American Petroleum Institute gravity (API gravity) is a measure of the relative density of oil compared 

with water and is expressed in degrees (°). Oils with an API gravity <10 are heavier and typically sink, 

whereas oils with an API gravity >10 are lighter and typically float. Following an oil spill, the 

composition of the released oil can change substantially due to weathering processes such as evaporation, 

emulsification, dissolution, and oxidation. More details on the properties and persistence of different 

types of oils are provided in Table 3-7 of the WPA 233/CPA 231 Supplemental EIS. 

Extensive laboratory testing has been performed on various oils from the GOM to determine their 

physical and chemical characteristics. For example, numerous oils collected from the GOM (U.S. waters) 

are included in Environment Canada’s (2013) oil properties database. The database provides details of an 

oils chemical composition including hydrocarbon groups (i.e., saturates, aromatics, resins, asphaltenes), 

VOCs (such as benzene, toluene, ethylbenzene, and xylene), sulfur content, biomarkers, and metals. The 

database also includes API gravities, of which GOM oils are in the range of 15° to 60°. Additional data 

have been collected from approximately 450 deepwater exploration plans and development operations 

and coordination documents that were submitted to BOEM/BSEE. These data are available through 

BOEM’s Exploration and Development Plans Online Query (refer to USDOI, BOEM, 2013c). Statistics 

on these API gravities result in a similar range (16° to 58°) as previously reported, with a mean value of 

36°. These new data corroborate the information previously presented in the prior 2012-2017 Gulf of 

Mexico EISs. 

3.2.1.4. Overview of Spill Risk Analysis

There are many factors that BOEM evaluates to determine the risk of impact occurring from an oil 

spill, including likely spill sources, likely spill locations, likely spill sizes, the likelihood and frequency of 

occurrence for different size spills, timeframes for the persistence of spilled oil, volumes of oil removed 

due to weathering and cleanup, and the likelihood of transport by wind and waves resulting in contact to 

specified environmental features. Sensitivity of the environmental resources and potential effects are 

addressed in the analyses for the specific resources of concern (Chapter 4.1.1). BOEM uses data on past 

OCS production and spills, along with estimates of future production, to evaluate the risk of future spills. 

Additionally, BOEM uses a numerical model to calculate the likely trajectory of spills (i.e., transport 

pathways) and analyzes historical data of occurrence rates for oil spills (refer to Anderson et al., 2012) to 

make projections of future oil-spill frequency and size. A more detailed description of the spill risk 

analysis and the trajectory model, called OSRA (oil-spill risk analysis) model, were provided in Chapter 3 

of the prior 2012-2017 Gulf of Mexico EISs , as well as in the Ji et al. (2012) OSRA report. Appendix C 

of the WPA 238/246/248 Supplemental EIS also contains the OSRA model’s catastrophic spill event 

results to estimate the risks associated with a possible future catastrophic or high-volume, long-duration 

oil spill.

The OSRA model results and estimated spill size/frequency tables as presented and discussed in the 

2012-2017 WPA/CPA Multisale EIS remain applicable because the basic assumptions inherent in the 

model and calculations are still valid. The latest analysis available for the characterization of spill rates 

and for average and median volumes (Anderson et al., 2012) inputted into the model is still valid because 

the more recent small OCS spills (2011-2013) were within spill scenario estimates developed using the

past data. In addition, the physical forcing (e.g., ocean currents and wind fields) and environmental 

resources input (e.g., locations and seasonality of various biological resources) to the OSRA model are 

still representative of our current state of knowledge regarding both ocean modeling and potential 

environmental resources at risk. Numerous efforts are underway since the Deepwater Horizon oil spill to 

further improve trajectory modeling in the Gulf of Mexico, including several BOEM environmental 
3-20 Western Planning Area Lease Sale 248 Supplemental EIS

studies (e.g., refer to Section 4.2 in Ji et al., 2013). The results of these new research activities are not yet 

available or fully tested for incorporation into BOEM’s oil-spill risk analysis for this Supplemental EIS. 

However, the OSRA analysts have chosen to take a more environmentally conservative approach by 

presuming persistence of oil over the selected time duration of the trajectories. As such, the trajectories 

simulated by the OSRA model do not involve any direct consideration of cleanup, dispersion, or 

weathering processes that could alter the quantity or properties of oil that might eventually contact the 

environmental resource locations. So in lieu of missing information and with the understanding that the 

OSRA model is conservative, BOEM can conclude that the unavailable information is not essential to an 

analysis of, or reasoned choice among, alternatives. Thus, new information did not change the results of 

previous spill risk analyses provided in the prior 2012-2017 Gulf of Mexico EISs. 

The following discussions provide separate risk information for offshore and coastal spills that may 

result from a WPA proposed action. This analysis is divided into discussions of offshore spills

≥1,000 bbl, offshore spills <1,000 bbl, and coastal spills of any spill volume. Only spills ≥1,000 bbl are 

addressed using OSRA because smaller spills typically do not persist long enough to be simulated by 

trajectory modeling.

3.2.1.5. Risk Analysis for Offshore Spills ≥1,000 bbl

Chapter 3.2.1.5 of the 2012-2017 WPA/CPA Multisale EIS addressed the risk of spills ≥1,000 bbl 

that could occur from accidents associated with activities resulting from a WPA proposed action. The 

risk analyses included the following:

• estimated number of offshore spills ≥1,000 bbl and probability of occurrence; 

• most likely source of offshore spills ≥1,000 bbl; 

• most likely size of an offshore spill ≥1,000 bbl; 

• fate of offshore spills ≥1,000 bbl; 

• transport of spills ≥1,000 bbl by winds and currents; 

• length of coastline affected by offshore spills ≥1,000 bbl; and

• likelihood of an offshore spill ≥1,000 bbl occurring and contacting modeled locations 

of environmental resources.

Specifically, the 2012-2017 WPA/CPA Multisale EIS estimated for a WPA proposed action that the 

mean number of spills was estimated at <1 spill (mean equal to 0.1-0.2) total from both OCS oil- and gasrelated platforms and pipelines. Based on historical data, the most likely source of an offshore spill was 

determined to be a potential pipeline break at the seafloor. 

The analysis presented in Anderson et al. (2012) remains applicable and up to date for characterizing 

spill rates and average and median spill volumes in this Supplemental EIS considering that no spills

≥1,000 bbl in size have occurred during 2011-2013. In terms of weathering, fate, and transport of oil 

spills in the Gulf of Mexico, a variety of ongoing studies are providing more insights in the aftermath of 

the Deepwater Horizon oil spill. For example, recent studies have provided further evidence that the 

diverse microbial communities in both the water column (e.g., Mason et al., 2012) and sediments (Kimes 

et al., 2013) of the GOM can play an active role in metabolizing and bioremediating crude oil from 

offshore spills. Further research is also being conducted regarding what impact chemical dispersant

application may have on this biodegradation process. Other research on oil fates also suggests that

marine snow formation in the aftermath of a large oil-spill event (such as the Deepwater Horizon oil spill) 

may play a key role in the fate of surface oil (e.g., Passow et al., 2012). Many of the recent findings 

related to the quantitative modeling of fate and transport of large oil spills in the Gulf of Mexico are part 

of the ongoing Natural Resource Damage Assessment (NRDA) process and have not yet been publicly 

released. However, the OSRA analysts have chosen to take a more environmentally conservative 

approach by presuming persistence of oil over the selected time duration of the trajectories. As such, the 

trajectories simulated by the OSRA model do not involve any direct consideration of cleanup, dispersion, 

or weathering processes that could alter the quantity or properties of oil that might eventually contact the 
Impact-Producing Factors and Scenario 3-21

environmental resource locations. So in lieu of missing information and with the understanding that the 

OSRA model is overly conservative, BOEM can conclude that the unavailable information is not essential 

to an analysis of, or reasoned choice among, alternatives. Thus, a review of recent information does not 

change the quantitative risk analyses for spills ≥1,000 bbl previously provided in the prior 2012-2017 

Gulf of Mexico EISs. 

3.2.1.6. Risk Analysis for Offshore Spills <1,000 bbl

Chapter 3.2.1.6 of the 2012-2017 WPA/CPA Multisale EIS addressed the risk of spills <1,000 bbl 

resulting from a WPA proposed action. Analysis of historical data shows that most offshore OCS oil 

spills fall within this category, with the majority of spills falling within the significantly smaller range of

≤1 bbl (Anderson et al., 2012). Although spills of ≤1 bbl amount to 96 percent of all OCS oil- and gasrelated spill occurrences, they have contributed very little to the total volume of oil spilled. The risk 

analyses addressed in Chapter 3.2.1.6 of the 2012-2017 WPA/CPA Multisale EIS included the following: 

• estimated number of offshore spills <1,000 bbl and total volume of oil spilled;

• most likely source and type of offshore spills <1,000 bbl; 

• most likely size of offshore spills <1,000 bbl; 

• persistence, spreading, and weathering of offshore oil spills <1,000 bbl; 

• transport of spills <1,000 bbl by winds and currents; and 

• likelihood of an offshore spill <1,000 bbl occurring and contacting modeled locations 

of environmental resources.

A search of BSEE’s oil-spill database (USDOI, BSEE, 2013) was performed to assess new spill 

information during 2011-2013, a period that was not analyzed in Anderson et al. (2012). During 

2011-2013, there were 46 spills from OCS oil- and gas-related activities of <1,000 bbl in size, totaling 

857 bbl overall. The breakdown of these spills into size classes is provided in Chapter 3.2.1.2. As noted 

above, the 2011-2013 spill data were compared with the estimated number and sizes of spills presented in 

Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS and were found to be well within the spill 

numbers estimated in the 2012-2017 WPA/CPA Multisale EIS. The new data also supported previous 

findings that the most likely source of a spill of <1,000 bbl would be from platforms, rigs, or vessels. 

Thus, a review of recent information does not change the risk analyses for spills <1,000 bbl previously 

provided in Chapter 3.2.1.6 of the prior 2012-2017 Gulf of Mexico EISs. 

3.2.1.7. Risk Analysis for Coastal 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. BOEM projects that almost all (>99%) oil 

produced as a result of a WPA proposed action will be brought ashore via pipelines to oil pipeline shore 

bases, stored at these facilities, and eventually transferred via pipeline or barge to Gulf coastal refineries. 

Because 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. Chapter 3.2.1.7 of the 2012-2017 WPA/CPA Multisale EIS describes in 

detail the estimated number and most likely sizes of coastal spills and the likelihood of coastal spill 

contact. 

The number and most likely spill sizes to occur in coastal waters in the future are expected to 

resemble the patterns that have occurred in the past, as long as the level of hydrocarbon use by 

commercial and recreational activities remains generally the same. As discussed in Chapter 3.2.1.7 of the 

WPA 238/246/248 Supplemental EIS, estimates of future coastal spills are based on the number and 

location of historical coastal spills reported to USCG. Based on the USCG’s historical data for the GOM 
3-22 Western Planning Area Lease Sale 248 Supplemental EIS

region, Louisiana and Texas are attributed the highest probability of having a spill ≥1,000 bbl occur in 

coastal waters.

3.2.1.8. Risk Analysis by Resource

BOEM previously analyzed the risk to resources from oil spills and oil slicks that could occur as a 

result of a WPA proposed action in the 2012-2017 WPA/CPA Multisale EIS. The risk results were based 

on BOEM’s estimates of likely spill locations, sources, sizes, frequency of occurrence, physical fates of 

different types of oil slicks, and probable transport that were described in more detail in specific spill 

scenarios. For offshore spills ≥1,000 bbl, combined probabilities were calculated using the OSRA model, 

which includes both the likelihood of a spill from a WPA proposed action occurring and the likelihood of 

the oil slick reaching areas where known environmental resources exist. 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 under each resource category in Chapter 4.1.1 of this Supplemental EIS and was provided in 

Chapter 4.1.1 of the prior 2012-2017 Gulf of Mexico EISs and Chapter 3.2.1.8 and Figures 3-8 through 

3-28 of the 2012-2017 WPA/CPA Multisale EIS. 

3.2.1.9. Spill Response

For a WPA proposed action, Chapter 3.2.1.9 of the 2012-2017 WPA/CPA Multisale EIS describes in 

detail issues related to offshore spill-response requirements and initiatives; offshore response, 

containment, and cleanup technology; and onshore response and cleanup. Additional information and 

updates to the 2012-2017 WPA/CPA Multisale EIS have been included within respective sections of the 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 246/248 

Supplemental EIS. 

As a result of the Oil Pollution Act of 1990 and the reorganization of the Bureau of Ocean Energy 

Management, Regulation and Enforcement into BOEM and BSEE in 2010, BSEE was tasked with a 

number of oil-spill response duties and planning requirements. The BSEE implements the following 

requirements according to BSEE’s regulations at 30 CFR parts 250 and 254: 

• requires immediate notification for spills ≥1 bbl—all spills require notification to 

USCG, and BSEE also 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 (OSRPs) for 

offshore facilities;

• conducts unannounced drills to ensure compliance with OSRPs; 

• 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. 

BOEM also has regulatory requirements addressing site-specific OSRPs and spill response

information. In accordance with BOEM’s regulations at 30 CFR §§ 550.219 and 550.250, operators must 

have an approved OSRP prior to BOEM’s approval of an operator-submitted exploration, development, 

or production plan. Operators are, therefore, required to provide BOEM an OSRP that is prepared in 

accordance with 30 CFR part 254 subpart B with their proposed exploration, development, or production 
Impact-Producing Factors and Scenario 3-23

plan for the facilities that they will use to conduct their activities; or to alternatively reference their 

approved regional OSRP by providing the following information: 

• a discussion of the approved OSRP;

• the location of the primary oil-spill equipment base and staging area;

• the name of the oil-spill equipment removal organization(s) for both equipment and 

personnel; 

• the calculated volume of the worst-case discharge scenario in accordance with 

30 CFR § 254.26(a) and a comparison of the worst-case discharge scenario in the 

approved regional OSRP with the worst-case discharge calculated for these proposed 

activities; and

• a description of the worst-case discharge to include the trajectory information, 

potentially impacted resources, and a detailed discussion of the spill response

proposed to the worst-case discharge in accordance with 30 CFR §§ 254(b)-(d).

All OSRPs are reviewed and approved by BSEE, whether submitted with a BOEM-associated plan or 

directly to BSEE in accordance with 30 CFR part 254. Hence, BOEM relies heavily upon BSEE’s 

expertise to ensure that the OSRP complies with all pertinent laws and regulations, and demonstrates the 

ability of an operator to respond to a worst-case discharge. The NTLs and guidance documents issued by 

BOEM and BSEE prior to 2012 that clarify additional oil-spill requirements since the Deepwater Horizon

explosion, oil spill, and response occurred are described in detail in Chapter 3.2.1.9 of the prior 

2012-2017 Gulf of Mexico EISs. 

The NTL 2012-BSEE-N06, “Guidance to Owners and Offshore Facilities Seaward of the Coast Line 

Concerning Regional Oil Spill Response Plans,” which was effective on August 10, 2012, provides 

clarification, guidance, and information concerning the preparation and submittal of a regional OSRP for 

owners and operators of oil handling, storage, or transportation facilities, including pipelines located 

seaward of the coastline. Some of the clarifications and encouraged practices that are identified in NTL 

2012-BSEE-N06 and that are based upon lessons learned from the Deepwater Horizon oil-spill response

are described in detail in the WPA 238/246/248 Supplemental EIS and WPA 246/248 Supplemental EIS. 

The BSEE has also issued NTL 2013-BSEE-N02, “Significant Change to Oil Spill Response Plan 

Worst Case Discharge Scenario,” to clarify what BSEE considers a significant change in a worst-case 

discharge scenario, which requires that a revision to an OSRP be submitted. Details of the guidance 

issued by this NTL are discussed in the WPA 238/246/248 Supplemental EIS and WPA 246/248 

Supplemental EIS. 

The BSEE also issued NTL 2012-BSEE-N07, “Oil Discharge Written Follow-up Reports,” to address 

the oil discharge reports (30 CFR § 254.46(b)(2)) that are required to be submitted by a responsible party 

to BSEE for spills ≥1 bbl within 15 days after a spill has been stopped or ceased. The responsible party is 

encouraged to report cause, location, volume, remedial action taken, sea state, meteorological conditions, 

and the size and appearance of the slick.

Mechanical Cleanup

As previously indicated, BSEE oversees a research program to improve the capabilities for detecting 

and responding to an oil spill in the marine environment. One of BSEE’s recently completed research 

projects suggested an alternative to improve the present regulatory requirements at 30 CFR § 254.44 for 

determining the effective daily recovery capacity of spill-response skimming equipment. This suggested 

alternative would consider the encounter rate of a skimming system with spilled oil instead of the 

presently used de-rated pump capacity of a skimmer. This project was undertaken because the Deepwater 

Horizon oil-spill response highlighted that the existing regulation may not be an effective or accurate 

planning standard and predictor of oil-spill response equipment recovery capacity. The project was 

completed in 2012 and the National Academy of Sciences completed a peer review in 2013. The BSEE’s

Gulf of Mexico OCS Region is presently utilizing the results of this study in its OSRP reviews. There 

have been some changes to the spill-response equipment staging locations previously reported in the prior 

2012-2017 Gulf of Mexico EISs. Due to these changes, it is expected that the oil-spill response 
3-24 Western Planning Area Lease Sale 248 Supplemental EIS

equipment needed to respond to an offshore spill in a proposed lease sale area could be called out from 

one or more of the following oil-spill equipment base locations: New Iberia, Belle Chasse, Baton Rouge, 

Sulphur, Morgan City, Port Fourchon, Harvey, Houma, Galliano, Leeville, Fort Jackson, Venice, Grand 

Isle, or Lake Charles, Louisiana; Corpus Christi, Port Arthur, Aransas Pass, Ingleside, Galveston, or 

Houston, Texas; Pascagoula or Kiln, Mississippi; Mobile or Bayou La Batre, Alabama; and/or Panama 

City, Pensacola, Tampa, and/or Miami, Florida (Clean Gulf Associates, 2015; Marine Spill Response 

Corporation, 2015; National Response Corporation, 2015).

Dispersants

The USEPA recently issued a proposed rule to amend the requirements in Subpart J of the National 

Oil and Hazardous Substances Pollution Contingency Plan (NCP) that governs the use of dispersants, 

other chemical and biological agents, and other spill mitigating substances when responding to oil 

discharges into waters of the United States. The proposal addresses the efficacy, toxicity, environmental 

monitoring of dispersants, and other chemical and biological agents, as well as public, local, State, and 

Federal officials’ concerns regarding their use (Federal Register, 2015b). The USEPA also updated the 

NCP product schedule in 2014. The 2014 NCP Product Schedule lists the types of products that are 

authorized for use on oil discharges, including dispersants, surface washing agents, surface collecting 

agents, bioremediation agents, and miscellaneous oil-spill control agents.

In February 2014, the USEPA published an NCP Product Schedule Notebook that presents 

manufacturers’ summary information that describes (1) the conditions under which each of the products is 

recommended for use, (2) handling and worker precautions, (3) storage information, (4) recommended 

application procedures, (5) physical properties, (6) toxicity information, and (7) effectiveness information 

(USEPA, 2014). 

Due to the unprecedented volume of dispersants applied for an extended period of time in situations 

not previously envisioned or incorporated in existing dispersant use plans during the Deepwater Horizon

oil-spill response, the National Response Team has developed guidance for monitoring atypical dispersant 

operations. The guidance document, which was approved on May 30, 2013, is titled Environmental 

Monitoring for Atypical Dispersant Operations: Including Guidance for Subsea Application and 

Prolonged Surface Application. The subsea guidance generally applies to the subsurface ocean 

environment and focuses on operations in waters below 300 m (984 ft) and below the pycnocline. The 

surface application guidance supplements and complements the existing protocols as outlined within the 

existing Special Monitoring of Applied Response Technologies (SMART) monitoring program where the 

duration of the application of dispersants on discharged oil extends beyond 96 hours from the time of the 

first application (U.S. National Response Team, 2013). This guidance is provided to the Regional 

Response Teams by the National Response Team to enhance existing SMART protocols and to ensure 

that their planning and response activities will be consistent with national policy.

Shoreline Cleanup Countermeasures

In addition, the USCG improved coastal oil-spill response since the Deepwater Horizon oil spill by 

replacing the One Gulf Plan with separate Area Contingency Plans (ACPs) for each coastal USCG sector. 

The ACPs cover subregional geographic areas and represent the third tier of the National Response 

Planning System mandated by the Oil Pollution Act of 1990. The ACPs are a focal point of response 

planning. The Gulf of Mexico OCS Region’s ACPs also include separate Geographic Response Plans, 

which are developed jointly with local, State, and other Federal entities to better focus spill-response 

tactics and priorities. These Geographic Response Plans, which will be periodically revisited, contain the 

resources initially identified for protection during a spill, response priorities, procedures, and appropriate 

spill-response countermeasures.

3.2.2. Losses of Well Control

All losses of well control must be reported to BSEE. The BSEE clarified its procedure for loss of 

well control incident reporting in NTL 2010-N05, “Increased Safety Measures for Energy Development 

on the OCS,” which became effective on June 8, 2010. The BSEE Drilling Safety Rule (Federal 

Register, 2012a) became effective on October 22, 2012. This rule implements certain additional safety 

measures recommended in NTL 2010-N05 by incorporating the recommendations contained in the DOI 
Impact-Producing Factors and Scenario 3-25

report Increased Safety Measures for Energy Development on the Outer Continental Shelf (Safety 

Measures Report; USDOI, 2010), and the Deepwater Horizon Joint Investigation Team report (USDOI, 

BOEMRE and USDHS, CG, Joint Investigation Team, 2013). The BSEE amended the drilling, wellcompletion, well-workover, and decommissioning regulations related to well control, including subsea 

and surface blowout preventers, well casing and cementing, secondary intervention, unplanned 

disconnects, recordkeeping, and well plugging. The Drilling Safety Rule also enhanced the description 

and classification of well-control barriers, defined testing requirements for cement, clarified requirements 

for the installation of dual mechanical barriers, and extended for blowout preventers (BOPs) and wellcontrol fluids to well-completions, workovers, and decommissioning operations. Operators are required 

to document any loss of well-control event, even if temporary, and the cause of the event, and they are 

required to furnish that information by mail or email to the addressee indicated in the NTL. The operator 

does not have to provide information on kicks that were controlled, but the operator should include the 

release of fluids through a flow diverter (a conduit used to direct fluid flowing from a well away from the 

drilling rig).

The current definition for loss of well control is as follows:

• uncontrolled flow of formation or other fluids (the flow may be to an exposed 

formation [an underground blowout] or at the surface [a surface blowout]);

• uncontrolled flow through a diverter; and/or

• uncontrolled flow resulting from a failure of surface equipment or procedures. 

A loss of well control can occur during any phase of development, i.e., exploratory drilling, 

development drilling, well completion, production, or workover operations. A loss of well control can 

occur when improperly balanced well pressure results in sudden, uncontrolled releases of fluids from a 

wellhead or wellbore (PCCI Marine and Environmental Engineering, 1999; Neal Adams Firefighters, 

Inc., 1991). From 2007 to 2014, of the 47 loss of well-control events reported in the GOM, 25 (53%) 

resulted in loss of fluids at the surface or underground (USDOI, BSEE, 2015). In addition to spills, the 

loss of well control can resuspend and disperse bottom sediments. Historically, since 1971, most OCS 

blowouts have resulted in the release of gas, while blowouts resulting in the release of oil have been rare.

A BOP is a device with a complex of choke lines and hydraulic rams mounted atop a wellhead 

designed to close the wellbore with a sharp horizontal motion that may cut through or pinch shut casing 

and sever tool strings. The BOPs were invented in the early 1920s and have been instrumental in ending 

dangerous, costly, and environmentally damaging oil blowouts on land and in water. The BOPs have 

been required for OCS oil and gas operations from the time offshore drilling began in the late 1940s. 

The BOPs are actuated as a last resort upon imminent threat to the integrity of the well or the surface 

rig. For a cased well, which is the typical well configuration, the hydraulic ram of a BOP may be closed 

if oil or gas from an underground zone enters the wellbore to destabilize the well. By closing a BOP, 

usually by redundant surface-operated and hydraulic actuators, the drilling crew can prevent explosive 

pressure release and allow control of the well to be regained by balancing the pressure exerted by a 

column of drilling mud with formation fluids or gases from below. Chapter 3.2.1.9.2 of the 2012-2017 

WPA/CPA Multisale EIS provides information on the subsea well containment capability staged in the 

GOM area that could be utilized by an offshore operator if a loss of well control occurred and resulted in 

a loss of fluids.

3.2.3. Pipeline Failures

The potential mechanisms for damage to OCS pipeline infrastructure include mass sediment 

movements and mudslides that can exhume or push the pipelines into another location, impacts from 

anchor drops or boat collisions, and accidental excavation or breaching because the exact whereabouts of 

a pipeline are uncertain. Pipeline failures could also be caused by rig/platform and pipeline activities 

supporting a WPA proposed action. Chapter 3.2.3 of the 2012-2017 WPA/CPA Multisale EIS describes 

previous incidents of OCS oil- and gas-related pipeline failures.

Any one of the mechanisms listed above could cause an OCS oil- and gas-related oil spill ≥1,000 bbl. 

Any resulting spill size would be limited by the size of the pipeline and the ability of an operator to 

quickly shut off flow from the source. The median spill size estimated from a pipeline failure is 2,200 bbl 
3-26 Western Planning Area Lease Sale 248 Supplemental EIS

(Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS). For a WPA proposed action, up to one spill of 

this size is estimated to occur during the 40-year analysis period. 

3.2.4. Vessel Collisions

The BSEE revised operator vessel collision incident reporting requirements in a final rule effective 

July 17, 2006 (Federal Register, 2006). The incident reporting rule more clearly defines what incidents 

must be reported, broadens the scope to include incidents that have the potential to be serious, and 

requires the reporting of standard information for both oral and written reports. As part of the incident 

reporting rule, BSEE’s regulations at 30 CFR § 250.188(a)(6) require an operator to report all collisions 

that result in property or equipment damage greater than $25,000. “Collision” is defined as the act of a 

moving vessel (including an aircraft) striking another vessel or striking a stationary vessel or object (e.g., 

a boat striking a drilling rig or platform). Chapter 3.2.4 of the 2012-2017 WPA/CPA Multisale EIS 

provides data related to vessel collisions and discusses methods of prevention and avoidance of vessel 

collisions. 

3.2.5. Chemical and Drilling-Fluid Spills

Chapter 3.2.5 of the 2012-2017 WPA/CPA Multisale EIS describes OCS oil- and gas-related 

chemical and synthetic-based fluid spills. Below is a brief summary of that information. 

Chemicals are stored and used to condition drill muds during production and in well completions, 

stimulation, and workover procedures. The most common chemicals spilled are methanol, ethylene 

glycol, and zinc bromide. Methanol and ethylene glycol may be used as a treatment to prevent the 

formation of gas hydrates while zinc bromide may be used in completion fluids. The chemicals that are 

used the most are also the chemicals that are spilled in the greatest volume. Completion fluids are used in 

the largest quantity and constitute the largest volume of accidental releases. Completion fluids consist of 

brines made from seawater mixed with calcium chloride, calcium bromide, and/or zinc bromide. A study 

of chemical spills from OCS oil- and gas-related activities determined that only two chemicals could 

potentially impact the marine environment—zinc bromide and ammonium chloride (Boehm et al., 2001). 

Both of these chemicals are used for well treatment or completion and, therefore, are not in continuous 

use. Most other chemicals are either nontoxic or used in small quantities. There are some differences in 

the operational needs for chemicals in deepwater versus shallow-water operations. Higher volumes of 

treatment chemicals (e.g., defoamers and hydrate inhibitors) are used in deepwater environments due to 

the conditions encountered there (Boehm et al., 2001). 

Synthetic-based fluids (SBFs) or synthetic-based muds have been used since the mid-1990’s. In 

deepwater drilling, SBFs are preferred over water-based muds because of the SBFs’ superior performance 

properties. The synthetic oils used in SBFs are relatively nontoxic to the marine environment and have 

the potential to biodegrade. However, it should be noted that SBFs are not permitted to be discharged 

into the marine environment; only cuttings wetted with SBF may be discharged after the majority of 

synthetic fluid has been removed. Additionally, accidental riser disconnects could result in the release of 

large quantities of drilling fluids and are of particular concern when SBFs are in use. For further 

discussion on this topic, refer to Chapter 3.1.1.4.1 of the 2012-2017 WPA/CPA Multisale EIS. Refer to 

Chapter 3.2.5 of the WPA 238/246/248 Supplemental EIS for the most recent information on BSEE’s 

counts and summaries for spills ≥50 bbl. 

3.3. CUMULATIVE ACTIVITIES SCENARIO

The preceding sections of Chapter 3 discuss the impact-producing factors and scenario for routine 

activities and accidental events associated with a WPA proposed action that could potentially impact the 

physical, environmental, and socioeconomic resources that are analyzed in this Supplemental EIS. This

chapter also presents a summary of other factors that may cumulatively impact those resources. For a 

more complete and detailed discussion of topics related to cumulative activities related to a WPA 

proposed action, refer to the prior 2012-2017 Gulf of Mexico EISs. 
Impact-Producing Factors and Scenario 3-27

3.3.1. 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. Projected reserve/resource production for the OCS 

Program (Table 3-1; WPA, CPA, and EPA) is 18.34-25.64 BBO and 75.886-111.627 Tcf of gas. 

Table 3-3 presents projections of the major activities and impact-producing factors related to future Gulf 

of Mexico OCS Program activities.

The level of OCS oil- and gas-related 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 

cumulative impacts of activities associated with the OCS Program on biological, physical, and 

socioeconomic resources are analyzed in Chapter 4.1.1 of this Supplemental EIS, Chapters 4.1.1 and 

4.2.1 of the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 233 Supplemental EIS, and WPA 

246/248 Supplemental EIS, and Appendix D of the WPA 238/246/248 Supplemental EIS. 

Note that offshore and onshore impact-producing factors and scenarios associated with a CPA or an 

EPA proposed action (i.e., a typical lease sale that would result from a proposed action within the CPA or 

EPA) as well as OCS Program activity resulting from past and future lease sales in the CPA or EPA, are 

disclosed in the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, CPA 

235/241/247 Supplemental EIS, and EPA 225/226 EIS. 

3.3.2. State Oil and Gas Activity

All five Gulf Coast States have had some historical oil and gas exploration activity and, with the 

exception of Florida and Mississippi, currently produce oil and gas in State waters. The coastal 

infrastructure that supports the OCS Program also supports State oil and gas activities.

State oil and gas infrastructure consists of the wells that extract hydrocarbon resources, facilities that 

produce and treat the raw product, pipelines that transport the product to refineries and gas facilities for 

further processing, and additional pipelines that transport finished product to points of storage and final 

consumption. The type and size of infrastructure that supports production depends upon the size, type, 

and location of the producing field, the time of development, and the life cycle stage of operations. 

Chapter 3.3.2 of the 2012-2017 WPA/CPA Multisale EIS provides a reference for relevant historical 

information on State leasing programs. The most recent lease sale information for Texas and Louisiana 

has been updated below. 

Texas 

The most recent State oil and gas lease sale occurred on January 20, 2015. Fifty-one parcels 

containing more than 24,850 ac (10,056 ha) of State lands were offered for oil and gas leasing in the 

offshore area by Texas State University Lands (State of Texas, General Land Office, 2015). BOEM 

expects that Texas will conduct regular oil and gas lease sales during the 40-year cumulative activities

scenario for OCS oil- and gas-related activity, although the lease sale’s regularity could differ from 

current practices.

Louisiana

During the 2014-2015 Fiscal Year, the State of Louisiana offered 37 tracts for lease offshore, 17 of 

which were awarded. BOEM expects that Louisiana will conduct regular oil and gas lease sales during 

the 40-year cumulative activities scenario for OCS oil- and gas-related activity, although the lease sale’s 

regularity could differ from current practices (State of Louisiana, Dept. of Natural Resources, 2015).

Mississippi

BOEM expects Mississippi to institute a State lease sale program in the near future and to begin 

leasing in State waters during the 40-year cumulative activities scenario for OCS oil- and gas-related 

activity analyzed in this Supplemental EIS. Recent efforts to open Mississippi State waters for G&G and 

leasing activities have been challenged in court (Davis, 2014). 
3-28 Western Planning Area Lease Sale 248 Supplemental EIS

Alabama 

Alabama has no established schedule of State lease sales. The limited number of blocks in State 

waters has resulted in the State not holding regularly scheduled lease sales. The last lease sale was held in 

1997. BOEM does not expect Alabama to institute a lease sale program in the near future, although there 

is at least a possibility of a lease sale in State waters during the 40-year cumulative activities scenario for 

OCS oil- and gas-related activity following a CPA proposed action (Mobile Area Chamber of Commerce, 

2011). 

Florida

BOEM does not expect Florida to institute a State lease sale program in the near future, although it is 

possible that a change in policy could lead to leasing on the OCS or in State waters during the 40-year 

cumulative activities scenario for OCS oil- and gas-related activity analyzed in this Supplemental EIS. 

For more information, refer to Chapter 3.3.2 of the 2012-2017 WPA/CPA Multisale EIS.

Pipeline Infrastructure

A mature pipeline network exists in the GOM to transport oil and gas produced on the OCS to shore 

(Chapter 4.1.1.20.1). The network carries oil and gas onshore and inland to refineries and terminals, and 

a network of pipelines distributes finished products such as diesel fuel or gasoline to and between 

refineries and processing facilities onshore (Peele et al., 2002, Figure 4.1). Expansion of this network is 

projected to be primarily small-diameter pipelines to increase the interconnectivity of the existing 

network and a few major interstate pipeline expansions. Any new larger-diameter pipelines would likely 

be constructed to support onshore and offshore LNG terminals. Refer to Chapter 3.3.2 of the 2012-2017 

WPA/CPA Multisale EIS for information on pipeline infrastructure activities within the State waters of 

Texas, Louisiana, Mississippi, and Alabama.

3.3.3. Other Major Factors Influencing Offshore Environments

Other influencing factors occur concurrently with OCS oil- and gas-related activity in the offshore 

areas of the Gulf Coast States. These factors include (1) dredged material disposal, (2) OCS sand 

borrowing, (3) marine transportation, (4) military activities, (5) artificial reefs and rigs-to-reefs 

development, (6) offshore LNG projects, (7) development of gas hydrates, and (8) renewable energy and 

alternative use.

Cumulative impacts to biological, physical, and socioeconomic resources from these types of 

non-OCS oil- and gas-related activities are analyzed in Chapter 4.1.1 of this Supplemental EIS, Chapters 

4.1.1 and 4.2.1 of the 2012-2017 WPA/CPA Multisale EIS, WPA 233/CPA 231 Supplemental EIS, and 

WPA 246/248 Supplemental EIS and Appendix D of the WPA 238/246/248 Supplemental EIS. 

3.3.3.1. Dredged Material Disposal

BOEM anticipates that, over the next 40 years, the amount of dredged material disposed at ocean 

dredged-material disposal sites (ODMDSs) will fluctuate but that it will generally follow historical trends 

of the practice utilized to date by the Galveston and New Orleans Districts. Between 2003 and 2013, the 

Galveston District has averaged about 7.0 million yd3

 (5.3 million m3) of material dredged per year 

disposed at ODMDSs, while the New Orleans District has averaged about 15.4 million yd3

(11.8 million m3

) of material dredged per year disposed at ODMDSs. Quantities may decrease slightly as 

various entities identify additional onshore sites for the beneficial uses of dredged material. The 1972 

Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (the London 

Convention), to which the U.S. is a signatory, requires annual reporting of the amount of materials 

disposed at sea. The U.S. Army Corps of Engineers (COE) prepares the dredged material disposed 

portion of the report to the International Maritime Organization; these yearly reports are available on the 

COE’s Ocean Disposal Database (U.S. Dept. of the Army, COE, 2010). For a more complete and 

detailed discussion of maintenance dredging and Federal channels, refer to Chapter 4.1.1.3 of this 

Supplemental EIS, Chapters 3.3.3.1 and 3.3.4.3 of the 2012-2017 WPA/CPA Multisale EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS and Chapter 3.3.4.4 of the 
Impact-Producing Factors and Scenario 3-29

2012-2017 WPA/CPA Multisale EIS, WPA 238/246/248 Supplemental EIS, and WPA 246/248 

Supplemental EIS. 

3.3.3.2. OCS Sand Borrowing

If OCS sand is requested for coastal restoration or beach nourishment, BOEM uses the following two 

types of lease instruments: a noncompetitive negotiated agreement that can only be used for obtaining 

sand and gravel for public works projects funded in part or whole by a Federal, State, or local government 

agency, and a competitive lease in which any qualified person may submit a bid through a lease sale. 

BOEM has issued 47 noncompetitive negotiated agreements, but it has never held a competitive lease sale 

for OCS sand and gravel resources. BOEM’s Marine Minerals Program continues to focus on identifying 

sand resources for coastal restoration, investigating the environmental implications of using those 

resources, and processing noncompetitive use requests.

In May 2015, BOEM issued one new agreement in Louisiana for the Deepwater Horizon NRDA 

Whiskey Island Restoration Project in Terrebonne Parish using sand from Ship Shoal Block 88. In March 

2014, BOEM issued a noncompetitive agreement for Phase Two of the Caminada Headland Restoration 

Project in Lafourche and Jefferson Parishes using sand from South Pelto Blocks 13 and 14. Construction 

for Phase Two began in May 2015, with completion anticipated in May 2017.

BOEM has outlined its responsibility as steward of significant sand resources on the OCS in NTL 

2009-G04 (“Significant OCS Sediment Resources in the Gulf of Mexico”), which states the following: 

“If it is determined that significant OCS sediment resources may be impacted by a proposed activity, the 

MMS GOMR may require you to undertake measures deemed economically, environmentally, and 

technically feasible to protect the resources to the maximum extent practicable. Measures may include 

modification of operations and monitoring of pipeline locations after installation.” This NTL also 

provides guidance for the avoidance and protection of significant OCS sediment resources essential to 

coastal restoration initiatives in BOEM’s Gulf of Mexico OCS Region. Over the next 40 years, increased 

use of OCS sand for Louisiana restoration projects is likely. Currently, no Texas restoration projects have 

been specifically identified. For more information on OCS Sand Borrowing, refer to Chapter 3.3.3.2 of 

the 2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental EIS. 

3.3.3.3. Marine Transportation

Under current conditions, freight and cruise ship passenger marine transportation within the analyzed 

area should continue to grow at a modest rate or remain relatively unchanged based on historical freight 

and cruise traffic statistics. In 2013, the Sabine-Neches Waterway had the highest vessel capacity, 

followed by the Port of New Orleans in terms of tonnage handled. The Port of Houston was the third 

largest port in the United States (USDOT, MARAD, 2015). Tankers carrying mostly petrochemicals 

account for about 60 percent of the vessel calls in the Gulf of Mexico. Dry-bulk vessels, including bulk 

vessels, bulk containerships, cement carriers, ore carriers, and wood-chip carriers, account for another 

17 percent of the vessel calls. The GOM also supports a popular cruise industry. In 2011, there were 

149 cruise ship departures from Galveston, 139 cruise ship departures from New Orleans, and 199 cruise 

ship departures from Tampa (USDOT, MARAD, 2012). 

Total port calls, or vessel stops at a port, in the U.S. are increasing as a whole, and total port calls 

within the GOM are also increasing. Over the last 10 years, the Gulf of Mexico port calls have 

represented approximately 32 percent of total U.S. port calls. Trends for GOM port calls relative to total 

U.S. port calls show an approximate 3 percent average increase of GOM port calls over the last decade, 

from 17,673 to 22,989 (USDOT, MARAD, 2013) (Table 3-10 in the WPA 238/246/248 Supplemental 

EIS).

Table 3-2 presents the estimated number of vessel trips that would occur as a result of a WPA 

proposed action. Annual OCS oil- and gas-related vessel traffic due to a WPA proposed action represents 

a small proportion (<1%) of the total vessel traffic in the GOM (Chapter 3.1.1.8 of this Supplemental 

EIS, Chapter 3.1.1.8.4 of the 2012-2017 WPA/CPA Multisale EIS, and Chapter 3.1.1.8 of the WPA 

238/246/248 Supplemental EIS). Annual OCS oil- and gas-related vessel traffic due to cumulative OCS 

oil- and gas-related activity represents between 9 and 12 percent of the total traffic in the GOM.

Cumulative Activities Scenario: It is expected that the usage of GOM ports will continue to increase 

by approximately 3 percent annually over the next 40 years. As such, it is anticipated that port calls by all 
3-30 Western Planning Area Lease Sale 248 Supplemental EIS

ship types will be bounded annually by a lower limit of current use and an upper limit of approximately 

85,000 vessel port calls. 

3.3.3.4. Military Activities

Twelve military warning areas and six Eglin Water Test Areas are located within the GOM 

(Figure 2-2). The air space over the WPA is used by the U.S. Department of Defense for conducting 

various air-to-air and air-to-surface operations. The WPA includes all or parts of the following military 

warning areas: W-147, W-228, and W-602. These warning and water test areas are multiple-use areas 

where military operations and oil and gas development have coexisted without conflict for many years. 

Several military stipulations are planned for leases issued within identified military areas.

Naval Mine Warfare Command Operational Area D contains 17 blocks in the WPA and is used by the 

Navy for mine warfare testing and training. In addition to Naval Mine Warfare Command Operational 

Area D, the WPA has four warning areas that are used for military operations. The areas total 

approximately 21.3 million ac or 75 percent of the total acreage of the WPA.

Chapter 3.3.3.4 of the 2012-2017 WPA/CPA Multisale EIS describes military activities within the 

OCS.

Cumulative Activities Scenario: BOEM anticipates that, over the next 40 years, the military use areas 

currently designated in the WPA will remain the same and that none of them will be released for 

nonmilitary use. Over the cumulative activities scenario, BOEM expects to continue to require military 

coordination stipulations in these areas. The intensity of the military’s use of these areas, or the type of 

activities conducted in them, is anticipated to fluctuate according to the operational needs of the military.

3.3.3.5. Artificial Reefs and Rigs-to-Reefs Development

A description of artificial reefs and BSEE’s Rigs-to-Reefs Policy is presented in the 2012-2017 

WPA/CPA Multisale EIS. Policy revisions have been published in BSEE’s Interim Policy Document 

2013-07. No new significant information was discovered that would alter impact conclusions based upon 

these operations. The following is a summary of this information. For more details, refer to Chapter 

3.1.1.10 of this Supplemental EIS and Chapter 3.1.1.10 of the 2012-2017 WPA/CPA Multisale EIS. 

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. Current research indicates 

that these structures act as both fish-attracting and production-enhancing devices depending upon the 

species (Carr and Hixon, 1997; Gallaway et al., 2009; Shipp and Bortone, 2009; Dance et al., 2011). All 

of the Gulf Coast States—Texas, Louisiana, Mississippi, Alabama, and Florida—have artificial reef 

programs and plans. These programs are guided by the National Artificial Reef Plan. Originally 

published in 1985 and revised in 2007, this national plan is a requirement of the National Fishing 

Enhancement Act of 1984. The lead agencies responsible for guiding and regulating artificial reef 

development are NOAA and the COE. 

Offshore oil and gas platforms have been contributing hard substrate to the GOM since the first 

platform was installed in 1942. However, the OCSLA and implementing regulations establish 

decommissioning obligations, including the removal of platforms. The Rigs-to-Reefs Policy provides a 

means by which lessees may request a waiver to the removal requirement. Although BSEE supports and 

encourages the reuse of obsolete oil and gas structures as artificial reefs, specific requirements must be

met for a departure to be granted. In recent years, approximately 12 percent of the platforms 

decommissioned from the Gulf OCS have been used in authorized artificial reef programs. Scientific and 

public interest in the ecology of offshore structures and the potential benefits of contributing substantial 

quantities of hard substrate to a predominantly soft bottom environment may lead to increased emphasis 

on the creation of artificial reefs through the Rigs-to-Reefs Policy. At present, Texas, Louisiana, 

Alabama, and Mississippi participate in Rigs-to-Reefs.

WPA, CPA, and EPA Proposed Actions Scenario (Typical Lease Sale): The number of platform 

removals projected for a WPA, CPA, or EPA proposed action is 14-22, 32-61, and 0-1, respectively 

(Table 3-2 of this Supplemental EIS for a WPA proposed action, Table 3-3 of the 2012-2017 WPA/CPA 

Multisale EIS for a CPA proposed action, and Table 3-2 of the EPA 225/226 EIS). The number of 

platforms anticipated to be part of the Rigs-to-Reefs Program as a result of a WPA, CPA, or EPA 
Impact-Producing Factors and Scenario 3-31

proposed action is approximately 10 percent of the projected removals, or 1-2 in the WPA, 3-7 in the 

CPA, and up to 1 in the EPA.

OCS Program Scenario: Over the course of the 40-year cumulative activities scenario for the OCS 

Program (2012-2051), BOEM projects that a total of 1,279-1,837 platforms will be removed (Table 3-3). 

If approximately 10 percent of these structures are accepted into the Rigs-to-Reefs Program, there may be 

as many as 128-184 additional artificial reefs installed in the WPA, CPA, and EPA. 

3.3.3.6. Offshore Liquefied Natural Gas Projects and Deepwater Ports

There are currently no LNG terminals operating on the OCS in the GOM. The following provides 

updates to the status of LNG projects and deepwater ports in the GOM as provided in Chapter 3.3.3.6 of 

the 2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental EIS. 

Florida

Port Dolphin. On March 29, 2007, Port Dolphin Energy LLC filed an application with the Maritime 

Administration to construct a deepwater port located in Federal waters approximately 28 mi (45 km) 

offshore of Tampa, Florida. The applicant is a wholly owned subsidiary of Höegh LNG. The proposed 

port will consist of two submerged turret loading (STL) buoys similar to those used in the Northeast 

Gateway and Neptune projects. On October 26, 2009, the Maritime Administration issued a Record of 

Decision approving, with conditions, the Port Dolphin Energy Deepwater Port License application, and 

on April 19, 2010, the official license was issued. Port Dolphin is currently working with the relevant 

Federal and State of Florida agencies to obtain the required authorizations and permits for construction 

and operation of the facility. Due to market considerations and commercial potential of the project, Port 

Dolphin requested on October 17, 2014, that the Commission extend the deadline until December 31, 

2018, for constructing and placing into operation the facilities authorized by the December 3, 2009, 

Federal Energy Regulatory Commission Certificate (Port Dolphin Energy, 2014). 

3.3.3.7. Development of Gas Hydrates

Chapter 3.3.3.7 of the 2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental EIS 

describes the development of gas hydrates in detail. BOEM still anticipates that, within 40 years, it is 

likely that the first U.S. domestic production from hydrates may occur in Alaska. Gas obtained from 

onshore hydrates in Alaska will either support local oil and gas field operations or be available for 

commercial sale if and when a gas pipeline is constructed to the lower 48 states. However, Moridis et al. 

(2008) stated that one should not discount the possibility that the first U.S. domestic production of gas 

hydrates could occur in the GOM. Despite the substantially increased complexity and cost of offshore 

operations, there is a mature network of available pipeline capacity and easier access to markets in the 

Gulf of Mexico. 

3.3.3.8. Renewable Energy and Alternative Use

The two primary categories of renewable energy that have the potential for development in the coastal 

and OCS waters of the U.S. are wind turbines and marine hydrokinetic systems. Chapter 3.3.3.8 of the 

2012-2017 WPA/CPA Multisale EIS and WPA 246/248 Supplemental EIS describe renewable energy 

and alternative use programs and potential action within the OCS. 

Cumulative Activities Scenario: BOEM expects that, over the next 40 years, a limited number of 

alternative use projects will be proposed in the WPA. It is also likely that these alternative use projects 

will consist of wind energy projects based on the current development of that technology. BOEM’s 

expectation is based on the fact that known projects are being proposed in Texas State waters. Likewise, 

the potential alternative use projects could consist of a combination of integrated existing GOM 

infrastructure with new-built facilities.

3.3.4. Other Major Factors Influencing Coastal Environments

The GOM is a dynamic, constantly changing system where natural and human-caused factors 

simultaneously impact both the coastal areas of the Gulf Coast States and OCS oil- and gas-related 
3-32 Western Planning Area Lease Sale 248 Supplemental EIS

activities. These factors include (1) sea-level rise and subsidence, (2) Mississippi Delta 

hydromodification, (3) maintenance dredging and Federal channels, and (4) coastal restoration programs. 

Cumulative impacts to biological, physical, and socioeconomic resources from these types of nonOCS oil- and gas-related activities are analyzed in Chapter 4.1.1 of this Supplemental EIS, Chapters 

4.1.1 and 4.2.1 of the 2012-2017 WPA/CPA Multisale EIS and WPA 233/CPA 231 Supplemental EIS, 

and Appendix D of WPA 238/246/248 Supplemental EIS. 

3.3.4.1. Sea-Level Rise and Subsidence

Given the results from the National Assessment of Coastal Vulnerability to Sea-Level Rise, BOEM 

anticipates that, over the next 40 years, the northern GOM will likely experience a minimum relative sealevel rise of 55.2 millimeters (2.17 inches) and a maximum relative sea-level rise of 384 millimeters 

(15.1 inches) (Pendleton et al., 2010). Sea-level rise and subsidence together have the potential to affect 

many important areas, including the OCS oil and gas industry, oil and gas infrastructure, waterborne 

commerce, commercial fishery landings, and important habitat for biological resources (State of 

Louisiana, Coastal Protection and Restoration Authority, 2012). Chapter 3.3.4.1 of the 2012-2017 

WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental EIS describes sea-level rise and 

subsidence in detail. Programmatic aspects of climate change relative to the environmental baseline for 

the Gulf of Mexico OCS Program are discussed in Chapter 3.3 of the Five-Year Program EIS. 

3.3.4.2. Mississippi River Hydromodification

BOEM anticipates that, over the next 40 years, there might be minor sediment additions resulting 

from new and continuing freshwater diversion projects managed by the COE. Chapter 3.3.4.2 of the 

2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental EIS describes Mississippi 

River hydromodification in detail. 

3.3.4.3. Maintenance Dredging and Federal Channels

Along the Texas Gulf Coast there are eight federally maintained navigation channels in addition to 

the Gulf Intracoastal Waterway. Most of the dredged materials from the Texas channels have high 

concentrations of silt and clay. Beneficial uses of dredged material include beach nourishment for the 

more sandy materials and storm reduction projects or ocean disposal for much of the finer-grained 

material. Ocean disposal locations along the Texas coast are situated so that materials are placed on the 

downdrift side of the channel (U.S. Dept. of the Army, COE, 1992). The construction of Federal 

channels is not a growth industry that would lead to future direct taking of wetlands, and at least one 

Louisiana channel (Mississippi River Gulf Outlet) has been decommissioned and sealed with a rock 

barrier as of July 2009 (Shaffer et al., 2009). For a more complete and detailed discussion of maintenance 

dredging and Federal channels, refer to Chapters 4.1.1.3 and 3.3.4.4 of this Supplemental EIS, Chapter 

4.1.1.3 and 3.3.4.4 of the 2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental EIS, 

and Chapter 3.3.4.3 of the 2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental 

EIS. For more information on coastal restoration programs, refer to Chapter 3.3.4.4 of this Supplemental 

EIS and Chapter 3.3.4.4 of the 2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental 

EIS. 

3.3.4.4. Coastal Restoration Programs

Coastal restoration programs are taking place on both the State and Federal level. Current Federal 

efforts include the Coastal Wetlands Planning Protection and Restoration Act program; the Coastal 

Impact Assistance Program, which was formed in response to the Energy Policy Act of 2005; and the 

Gulf Coast Ecosystem Restoration Council, which was formed in response to the Resources and 

Ecosystems Sustainability, Tourist Opportunities and Revived Economies of the Gulf Coast States Act 

(RESTORE Act). For more information on coastal restoration programs, refer to Chapter 3.3.4.4 of the 

2012-2017 WPA/CPA Multisale EIS and WPA 238/246/248 Supplemental EIS. 
Impact-Producing Factors and Scenario 3-33

3.3.5. Natural Events and Processes

Chapter 3.3.5 of the 2012-2017 WPA/CPA Multisale EIS describes in detail natural events and 

processes in the Gulf of Mexico, including physical oceanography and hurricanes. 

Since 2009, most of the extreme atmospheric events in GOM have been categorized as tropical 

storms with strong winds, heavy rain, and storm surges causing coastal flooding. However, on 

August 28, 2012, Hurricane Isaac made landfall in southeastern Louisiana as a Category 1 hurricane. 

While there were no reports of moderate or extensive damage to offshore oil or gas infrastructure in the 

GOM, Hurricane Isaac did result in the suspension of small amounts of tarballs and some oil from 

sediments (Mulabagal et al., 2013). This conforms with the predictions in the 2012-2017 WPA/CPA 

Multisale EIS analysis and is discussed more fully in Chapter 4.1.1.2.1 of this Supplemental EIS. 

3.3.6. Non-OCS Oil- and Gas-Related Oil Spills

Oil spills related to non-OCS oil- and gas-related activities such as State oil and gas activity or vessel 

collisions (including tankering, barging, or State oil and gas vessels) can result in the contamination of 

offshore or coastal environments. The Oil Pollution Act of 1990 strengthens planning and prevention 

activities in waters by (1) providing for the establishment of spill contingency plans for all areas of the 

U.S., (2) mandating the development of response plans for individual tank vessels and certain facilities for 

responding to a worst-case discharge or a substantial threat of such a discharge, and (3) providing 

requirements for spill-removal equipment and periodic inspections. Oil spills associated with a WPA 

proposed action are discussed in Chapter 3.2.1 of this Supplemental EIS and Chapter 3.2.1 of the prior 

2012-2017 Gulf of Mexico EISs. Refer to Chapter 3.2.1.9 of this Supplemental EIS and Chapter 3.2.1.9 

of the 2012-2017 WPA/CPA Multisale EIS for more information on the Oil Spill Pollution Act and other 

response requirements and initiatives regarding oil spills. Spills from tankers involve the spillage of 

crude oil, whereas barge spills involve spills of both crude oil and other petroleum products. Anderson 

et al. (2012) noted that tanker spill rates have continued to have a substantial decline since 2000. Most 

likely, tanker spills have declined due to major regulatory changes in the early 1990’s that substantially 

eliminated the use of single-hull tankers by requiring double hulls or their equivalent (Anderson et al., 

2012). A majority of spills from tankers occurred in coastal areas (37 spills) versus offshore (16 spills) 

between 1974 and 2008. Barge spill rates for the last 15 years (1994 through 2008) declined dramatically 

as compared with the entire time period of available data (1974 through 2008), especially for crude oil 

barges and for both spill sizes ≥1,000 bbl and >10,000 bbl (Anderson et al., 2012). From 1974 through 

2008, 197 petroleum spills ≥1,000 bbl (28 of which were crude oil spills) occurred from barges in U.S. 

coastal, offshore, and inland waters (including U.S. territorial waters). Because the data available on 

barge transport in U.S. waters do not differentiate between inland and coastal/offshore transport, inland 

transport was included.

CHAPTER 4 

DESCRIPTION OF THE ENVIRONMENT

AND IMPACT ANALYSIS

Description of the Environment and Impact Analysis 4-3 

4. DESCRIPTION OF THE ENVIRONMENT AND IMPACT ANALYSIS

The impacts of proposed WPA and CPA lease sales were analyzed in the “prior 2012-2017 Gulf of 

Mexico EISs”: Gulf of Mexico OCS Oil and Gas Lease Sales: 2012-2017; Western Planning Area Lease 

Sales 229, 233, 238, 246, and 248; Central Planning Area Lease Sales 227, 231, 235, 241, and 247, Final 

Environmental Impact Statement (2012-2017 WPA/CPA Multisale EIS) (USDOI, BOEM, 2012b); the 

impacts of a WPA and CPA lease sale were analyzed in the Gulf of Mexico OCS Oil and Gas Lease 

Sales: 2013-2014; Western Planning Area Lease Sale 233; Central Planning Area Lease Sale 231, Final 

Supplemental Environmental Impact Statement (WPA 233/CPA 231 Supplemental EIS) (USDOI, BOEM, 

2013a); the impacts of a WPA lease sale were analyzed in the Gulf of Mexico OCS Oil and Gas Lease 

Sales: 2014-2016; Western Planning Area Lease Sales 238, 246, and 248, Final Supplemental 

Environmental Impact Statement (WPA 238/246/248 Supplemental EIS) (USDOI, BOEM, 2014a); and 

the impacts of a WPA lease sale were analyzed in the Gulf of Mexico OCS Oil and Gas Lease Sales: 

2015 and 2016; Western Planning Area Lease Sales 246 and 248, Final Supplemental Environmental 

Impact Statement (WPA 246/248 Supplemental EIS) (USDOI, BOEM, 2015a). An analysis of the routine 

activities, accidental events, and cumulative impacts of a WPA proposed action on the environmental, 

socioeconomic, and cultural resources of the Gulf of Mexico can be found in Chapter 4.1.1 of the prior 

2012-2017 Gulf of Mexico EISs; these EISs are hereby incorporated by reference.

The purpose of this Supplemental EIS is to determine if there are significant new circumstances or 

information bearing on the WPA proposed action or its impacts, as previously discussed in the prior 

2012-2017 Gulf of Mexico EISs, and if so, to disclose those changes and conclusions. This includes all 

relevant new information available since publication of the prior 2012-2017 Gulf of Mexico EISs. As 

will be demonstrated within each environmental, socioeconomic, and cultural resources chapter in this

Supplemental EIS, the new circumstances and new information identified and discussed herein do not 

alter the conclusions reached in the prior 2012-2017 Gulf of Mexico EISs. 

4.1. PROPOSED WESTERN PLANNING AREA LEASE SALE 248

Proposed WPA Lease Sale 248 is tentatively scheduled to be held in August 2016. The proposed 

WPA lease sale area encompasses about 28.58 million ac. This area begins 3 marine leagues (9 nmi; 

10.35 mi; 16.67 km) offshore Texas and extends seaward to the limits of the United States’ jurisdiction 

over the continental shelf (often the Exclusive Economic Zone) in water depths up to approximately 

3,346 m (10,978 ft) (Figure 1-1). As of July 2015, approximately 22 million ac of the proposed WPA 

lease sale area are currently unleased. This information is updated monthly and can be found on BOEM’s 

website at http://www.boem.gov/Gulf-of-Mexico-Region-Lease-Map/. The WPA proposed action would 

offer for lease all unleased blocks within the proposed WPA lease sale area for oil and gas operations 

(Figure 2-1), with the following exception: 

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

Marine Sanctuary (i.e., the boundary as of the publication of this Supplemental EIS).

The DOI is conservative throughout the NEPA process and includes the total area within the WPA for 

environmental review even though the leasing of portions of the WPA (subareas or blocks) can be 

deferred during a Five-Year Program. 

Chapter 4.1.1 presents a brief summary of the baseline data for the physical, biological, and 

socioeconomic resources that would potentially be affected by the WPA proposed action or the 

alternatives. For additional information on the baseline data for the physical, biological, and 

socioeconomic resources that would potentially be affected by the WPA proposed action or the 

alternatives, refer to Chapter 4.1.1 of the prior 2012-2017 Gulf of Mexico EISs. 

Chapter 4.1.1 also presents analyses of the potential impacts of routine events, accidental events, and 

cumulative activities associated with the WPA proposed action or the alternatives on these resources. 

Baseline data are considered in the assessment of impacts from proposed WPA Lease Sale 248 on these 

resources. In addition, Appendix A (“Catastrophic Spill Event Analysis”) serves as a complement to this 

chapter and provides additional analysis of the potential impacts of a low-probability catastrophic oil 

spill, which is not part of the WPA proposed action and not reasonably expected to occur, to the 
4-4 Western Planning Area Lease Sale 248 Supplemental EIS

environmental and cultural resources and the socioeconomic conditions analyzed below. For additional 

information on environmental impacts of the cumulative case for the Gulf of Mexico resources, refer to 

Chapter 4.1.1 of the prior 2012-2017 Gulf of Mexico EISs, as well as Appendix D of the WPA 

238/246/248 Supplemental EIS, which is hereby incorporated by reference. 

The Deepwater Horizon explosion resulted in the largest oil spill in U.S. history. An event such as 

this has the potential to adversely affect multiple resources over a large area. The level of adverse effect 

depends on many factors, including the sensitivity of the resource as well as the sensitivity of the 

environment in which the resource is located. All effects may not initially be seen and some could take 

years to fully develop. The following analyses of impacts from the Deepwater Horizon explosion, oil 

spill, and response on the physical, biological, and socioeconomic resources are based on post-Deepwater 

Horizon credible scientific information that was publicly available at the time this Supplemental EIS was 

prepared. This credible scientific information was applied using accepted methodologies, including

numerical modeling of data and scientific writing methods to convey the information of BOEM’s subjectmatter experts’ technical knowledge and experience. However, the Trustee Council of the NRDA for the 

Deepwater Horizon oil spill continues to study, measure, and interpret impacts arising out of that spill. 

Because much of the NRDA information has not yet been made available to BOEM or the general public, 

there are thus instances in which BOEM is faced with incomplete or unavailable information that may be

relevant to evaluating reasonably foreseeable significant adverse impacts on the human environment. 

While incomplete or unavailable information could conceivably result in potential future shifts in baseline 

conditions of habitats that could affect BOEM’s decisionmaking, BOEM has determined that there is 

sufficient basis to proceed with this Supplemental EIS while operating on the basis of the most current 

available data and expertise of BOEM’s subject-matter experts. Chapter 4.1.1 and Appendix A provide 

a summary of existing credible scientific evidence related to this issue and BOEM’s evaluation of 

potential impacts based upon theoretical approaches or research methods generally accepted in the 

scientific community. Despite the unavailability of complete information from the NRDA process, 

BOEM has determined that it can make an informed decision even without this incomplete or unavailable 

information because BOEM utilizes the best available scientifically credible information in its 

decisionmaking process and because BOEM cannot speculate as to the results of ongoing NRDA studies. 

Moreover, BOEM will continue to monitor these resources for effects caused by the Deepwater Horizon

explosion, oil spill, and response, and will ensure that future BOEM environmental reviews take into 

account any new information that may emerge. 

Chapter 3.2.1 of this Supplemental EIS provides a brief summary of the information on accidental 

spills that could result from all operations conducted under the OCS Program, as well as information on 

the number and sizes of spills from non-OCS sources. Table 3-12 of the 2012-2017 WPA/CPA Multisale 

EIS provides the number of spills ≥1,000 bbl and <1,000 bbl estimated to occur as a result of the WPA 

proposed action. BOEM estimates that the mean number of spills ≥1,000 bbl for the WPA proposed 

action is up to one spill. Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS provides spill rates for 

several spill-size categories. Chapter 3.2.1.8 and Figures 3-8 through 3-28 of the 2012-2017 WPA/CPA 

Multisale EIS describe the probabilities of a spill ≥1,000 bbl occurring and contacting modeled 

environmental resources. For additional information on accidental spills that could result from all 

operations conducted under the OCS Program, as well as information on the number and sizes of spills 

from non-OCS oil- and gas-related sources, refer to Chapter 3.2.1 of this Supplemental EIS and to 

Chapter 3.2.1 of the 2012-2017 WPA/CPA Multisale EIS. 

Analytical Approach 

The analyses of potential effects to the wide variety of physical, environmental, and socioeconomic 

resources in the vast area of the GOM and adjacent coastal areas are complex. Specialized education, 

experience, and technical knowledge are required, as well as familiarity with the numerous impactproducing factors associated with oil and gas activities and other activities that can cause cumulative 

impacts in the area. Knowledge and practical working experience of major environmental laws and 

regulations such as NEPA, the Clean Water Act, Clean Air Act, Coastal Zone Management Act (CZMA), 

Endangered Species Act (ESA), Marine Mammal Protection Act (MMPA), Magnuson-Stevens Fishery 

Conservation and Management Act, and others are also required. 

In order to accomplish this task, BOEM has assembled a multidisciplinary staff with hundreds of 

years of collective experience. The vast majority of this staff have advanced degrees with a high level of 
Description of the Environment and Impact Analysis 4-5 

knowledge related to the particular resources discussed in this chapter. This staff prepares the input to 

BOEM’s lease sale EISs and a variety of subsequent postlease NEPA reviews and is also involved with 

ESA, essential fish habitat, CZMA, National Historic Preservation Act, and Government-to-Government 

consultations. In addition, this same staff is also directly involved with the development of studies 

conducted by BOEM’s Environmental Studies Program. The results of these studies feed directly into the 

Bureau of Ocean Energy Management’s NEPA analyses.

For this Supplemental EIS, BOEM developed a set of assumptions with an accompanying scenario 

and described impact-producing factors that could occur from both routine oil and gas activities and from 

accidental events. These assumptions, scenario, and factors are summarized in Chapter 3 of this 

Supplemental EIS and are discussed in detail in Chapter 3 of the 2012-2017 WPA/CPA Multisale EIS. 

On the basis of these assumptions, scenario, and factors, BOEM’s multidisciplinary staff applies its 

knowledge and experience to analyze the potential effects that could arise out of proposed WPA Lease 

Sale 248. 

For most resources, the conclusions developed by BOEM’s subject-matter experts regarding the 

potential effects of proposed WPA Lease Sale 248 are necessarily qualitative in nature; however, these 

conclusions are based on the expert opinion and judgment of highly trained subject-matter experts. 

BOEM’s staff approaches this effort in good faith utilizing credible scientific information including, but 

not limited to, information available since the Deepwater Horizon explosion, oil spill, and response, and 

applying this information using accepted methodologies, including numerical modeling of data and

scientific writing methods to convey the information of the subject-matter experts’ technical knowledge 

and experience. It must also be emphasized that, in arriving at the overall conclusions for certain 

environmental resources (e.g., coastal and marine birds, fisheries, and wetlands), the conclusions are not 

based on impacts to individuals, small groups of animals, or small areas of habitat, but on impacts to the 

resources/populations as a whole. Where relevant information on reasonably foreseeable significant 

adverse impacts is incomplete or unavailable, the need for the information was evaluated to determine if it 

was essential to a reasoned choice among the alternatives. If BOEM’s subject-matter experts determined 

that the incomplete or unavailable information was essential, BOEM made good faith efforts to acquire 

the information. In the event that BOEM was unable to obtain essential information (e.g., due to 

exorbitant cost or the impossibility of obtaining the information within a known time period), BOEM 

applied accepted scientific methodologies in place of that information. This approach is described in the 

next subsection on “Incomplete or Unavailable Information.” 

Over the years, BOEM has developed a suite of lease stipulations and mitigating measures to 

eliminate or ameliorate potential environmental effects. In many instances, these lease stipulations and 

mitigating measures were developed in coordination with other natural resource agencies such as NMFS 

and FWS.

Throughout its effort to prepare this Supplemental EIS, BOEM has made painstaking efforts to 

comply with the spirit and intent of NEPA, to avoid being arbitrary and capricious in its analyses of 

potential environmental effects, and to use adaptive management to respond to new developments related 

to the OCS Program.

Incomplete or Unavailable Information 

In the following analyses of physical, environmental, and socioeconomic resources, BOEM identifies 

situations in which its analysis contains incomplete or unavailable information. The major area where 

BOEM is faced with incomplete or unavailable information is in relation to the Deepwater Horizon

explosion, oil spill, and response. Information related to the explosion, oil spill, and response is still 

being collected, interpreted, and analyzed by a myriad of Federal and State agencies. With respect to 

some of this information, including much of the data related to the NRDA process, those in charge of 

analyzing impacts from the spill have not yet shared their data and findings with BOEM or made this 

information publicly available. Therefore, in situations in which BOEM’s subject-matter experts were 

faced with incomplete or unavailable information, the subject-matter experts for each resource utilized the 

most recent publicly available, scientifically credible information from other sources to support the 

conclusions contained in this Supplemental EIS. This information is identified and summarized in 

Chapter 4.1.1 of this Supplemental EIS and is discussed in detail for each resource in Chapter 4.1.1 of 

the prior 2012-2017 Gulf of Mexico EISs. In certain circumstances, identified and described in more 

detail in Chapter 4.1.1 of this Supplemental EIS, BOEM’s subject-matter experts were required to utilize 
4-6 Western Planning Area Lease Sale 248 Supplemental EIS

accepted methodologies to extrapolate conclusions from existing or new information and to make 

reasoned estimates and develop conclusions regarding the current WPA baseline for resource categories 

and expected impacts from the WPA proposed action given any baseline changes. For reasons described 

below, there are no changes to the conclusions as presented in the prior 2012-2017 Gulf of Mexico EISs. 

It is important to note that, barring another catastrophic oil spill, which is a low-probability event that 

is not considered part of the WPA proposed action and not reasonably expected to occur, the adverse

impacts associated with the proposed WPA lease sale are small, even in light of the Deepwater Horizon

explosion, oil spill, and response. This is because of lease sale stipulations that are typically applied and 

because of BOEM’s and other Federal and State entities’ mitigating measures. BOEM also imposes sitespecific mitigations that become conditions of plan or permit approval at the postlease stage. 

Collectively, these measures further reduce the likelihood and/or severity of adverse impacts.

For the following resources, as with the prior 2012-2017 Gulf of Mexico EISs, the subject-matter 

experts determined that there is incomplete or unavailable information that is relevant to reasonably 

foreseeable significant adverse impacts; however, it is not essential to a reasoned choice among 

alternatives.

• Physical Resources in the WPA: Physical resources (i.e., water quality and air 

quality) within the WPA were likely not affected to any discernible degree by the 

Deepwater Horizon explosion, oil spill, and response, based on the best available 

information and the WPA’s distance from the Macondo well (485.2 km; 301.5 mi). 

BOEM has thus determined that the incomplete or unavailable information is not 

essential to a reasoned choice among alternatives because of this absence of 

discernible effect in the WPA and because BOEM utilizes the best available 

scientifically credible information in its decisionmaking process and cannot speculate 

as to the results of ongoing NRDA studies. In any event, much of the information 

related to the Deepwater Horizon explosion, oil spill, and response may not be 

available for some time, regardless of the costs necessary to obtain this information, 

as there are numerous task forces and interagency groups involved in the production 

of the information. It is not expected that these data would become publicly available 

in the near term, and certainly not within the timeline contemplated in the NEPA

analysis of this Supplemental EIS.

• Nonmobile Biological Resources within the WPA: Coastal and offshore biological 

and benthic habitats (i.e., barrier beaches, wetlands, seagrasses, soft bottom benthic 

communities, topographic features, and chemosynthetic and nonchemosynthetic 

communities) and nonmobile benthic species that would be expected to spend their 

entire life cycle in the WPA were likely not affected to any discernible degree by the 

Deepwater Horizon explosion, oil spill, and response, based on the WPA’s distance 

from the Macondo well (485.2 km; 301.5 mi) and currently available data indicating 

that the spill did not reach WPA waters or sediments. Similarly to the analysis of 

physical resources in the WPA described in the preceding paragraph, BOEM has 

determined that the incomplete or unavailable information regarding nonmobile 

biological resources is not essential to a reasoned choice among alternatives because 

of the absence of discernible effects in the WPA and because BOEM utilizes the best 

available scientifically credible information in its decisionmaking process and cannot 

speculate as to the results of ongoing NRDA studies.

• Mobile Biological Resources within or Migrating through the WPA: Certain mobile 

biological resources (i.e., birds, fish, marine mammals, and sea turtles) having ranges 

and/or habitats that may include different areas in the GOM may have individually 

been affected by exposure to oil and/or spill-response activities, provided they were 

in the vicinity of the Deepwater Horizon explosion, oil spill, and response during 

spill conditions. Precise information on the impacts on mobile biological resources 

within or migrating through the WPA is therefore not known, and it is not expected 

that these data would become publicly available within the timeline contemplated in 

the NEPA analysis of this Supplemental EIS. BOEM has concluded that this 

incomplete or unavailable information is not essential to a reasoned choice among the 
Description of the Environment and Impact Analysis 4-7 

alternatives because the adverse impacts from routine activities associated with the 

WPA proposed action are expected to be small, even in light of how baseline 

conditions may have been changed by the Deepwater Horizon explosion, oil spill, 

and response. Moreover, based on the scientifically credible information that was 

available and applied in Chapter 4.1.1, such as peer-reviewed journals and 

government reports, this incomplete or unavailable information is not essential to a 

reasoned choice among the alternatives because the subject-matter experts for this 

Supplemental EIS have already evaluated the probability and severity of these 

potential impacts and because this incomplete or unavailable information is not 

essential to understand every particular mechanism by which these significant 

impacts could occur. With regard to future potentially low-probability catastrophic 

spills, any incomplete or unavailable information regarding the nature of a very large 

spill would not be essential to a reasoned choice among the alternatives. This is 

because a low-probability catastrophic oil spill and its impacts are not “expected” as 

a result of the WPA proposed action since such a spill remains a low-probability 

event, particularly in light of improved safety and oil-spill response requirements that 

have been put in place since the spill.

• Endangered and Threatened Species: BOEM and BSEE reinitiated consultation with 

NMFS and FWS in light of new information that may become available on these 

species and in light of effects from the Deepwater Horizon explosion, oil spill, and 

response. Pending the completion of the reinitiated ESA Section 7 Consultation, 

BOEM has prepared an ESA Section 7(d) determination (50 CFR § 402.09). 

Section 7(d) of the ESA requires that, after initiation or reinitiation of consultation 

under Section 7(a)(2), the Federal agency “shall not make any irreversible or 

irretrievable commitment of resources with respect to the agency action which has 

the effect of foreclosing the formulation or implementation of any reasonable and 

prudent alternative measures which would not violate” Section 7(a)(2). BOEM has 

determined that the proposed action during the reinitiated Section 7 consultation 

period is consistent with the requirements of ESA Section 7(d) because (1) approving 

and/or conducting the proposed WPA lease sale will not foreclose the formulation or 

implementation of any Reasonable and Prudent Alternative measures that may be 

necessary to avoid jeopardy (or the likely destruction or adverse modification of 

critical habitat) and (2) the Secretary of the Interior retains the discretion under 

OCSLA to deny, suspend, or rescind plans and permits authorized under OCSLA at 

any time, as necessary to avoid jeopardy. Lease sales alone do not constitute an 

irreversible and irretrievable commitment of resources. In addition, the results of 

consultation and any additional relevant information on endangered and threatened 

species can be employed during postlease activities to ensure that Reasonable and 

Prudent Alternative measures are not foreclosed. BOEM and BSEE have developed 

an interim coordination program with NMFS and FWS for individual consultations 

on postlease activities requiring permits or plan approvals while formal consultation 

and development of new Biological Opinions are ongoing. 

• Natural Resource Damage Assessment (NRDA) Data: In response to the Deepwater

Horizon explosion, oil spill, and response, a major NRDA is underway to assess 

impacts to all natural resources in the GOM that may have been impacted by the 

resulting spill from the Macondo well, as well as impacts from the spill-response 

operations. The NRDA is mandated by the Oil Pollution Act of 1990. The 

U.S. Department of the Interior is a co-Trustee in the NRDA process, and BOEM is a 

cooperating agency on a Programmatic EIS being prepared as part of the NEPA

analysis for the Deepwater Horizon NRDA. However, the Deepwater Horizon 

NRDA process is being led by the NRDA Trustees, which include NOAA and DOI 

(FWS and National Park Service), but not BOEM. BOEM is listed as an affected 

party for NRDA purposes. At this time, limited data compiled in the Deepwater 

Horizon NRDA process have been made publicly available. Because limited data 

have been made publicly available, most Deepwater Horizon NRDA datasets are not 
4-8 Western Planning Area Lease Sale 248 Supplemental EIS

available for BOEM to use in its NEPA analyses. BOEM acknowledges that the 

ability to obtain and use the NRDA data in its NEPA analyses could be relevant to 

reasonably foreseeable significant adverse impacts; however, the Deepwater Horizon 

NRDA data are not essential to a reasoned choice among the alternatives because 

impacts identified through the Deepwater Horizon NRDA process would likely be 

the same under any alternative and obtaining the data would not help inform the 

decisionmaker. In addition and as discussed above, the baseline by which to gauge 

potential adverse impacts may have been changed by the Deepwater Horizon

explosion, oil spill, and response. The impacts are expected to be small because of 

BOEM’s lease sale stipulations and mitigating measures, site-specific mitigations

that become conditions of plan or permit approval at the postlease stage, and 

mitigations required by other State and Federal agencies. Even if the NRDA data 

were essential to a reasoned choice among the alternatives, the data are not publicly 

available and much of the data may not become available for many years. The 

NEPA allows for decisions to be made based on available scientifically credible 

information (e.g., peer-reviewed journals and studies, and government reports) 

applied using accepted methodologies where the incomplete information cannot be 

obtained or the cost of obtaining it is exorbitant. The NRDA process is ongoing and 

there is no timeline on when this information will be released. It is not within 

BOEM’s authority to obtain this information. Cost is not an issue in obtaining the 

information, regardless of whether the cost would be exorbitant or not. Instead, the 

limitations on the NRDA process, including statutory requirements under the Oil 

Pollution Act of 1990, are the determining factors on the availability of this 

information. In light of the fact that the NRDA data may not be available for years, 

BOEM has used accepted scientific methodologies to evaluate each resource, as 

described in this chapter. These include numerical modeling of data and scientific 

writing methods to convey the information of BOEM’s subject-matter experts’ 

technical knowledge and experience. Since the spill, BOEM’s Gulf of Mexico OCS 

Region’s Environmental Studies Program has continually modified its Studies Plan to 

reflect the Agency’s current information needs for studies that address impacts and 

recovery from the oil spill. The scientific studies conducted by the Environmental 

Studies Program provide some of the data that BOEM relies on in making decisions 

in this Supplemental EIS. BOEM’s proposed studies attempt to avoid duplication of 

study efforts while striving to fill information gaps where Deepwater Horizon NRDA 

studies may not address particular resources and their impacts from the oil spill.

• Socioeconomic and Cultural Resources: Incomplete or unavailable information 

related to socioeconomic and cultural impacts (i.e., commercial and recreational 

fishing, recreational resources, archaeological resources, land use and coastal 

infrastructure, demographics, economic factors, and environmental justice) may be 

relevant to reasonably foreseeable adverse impacts on these resources. With regard 

to the Deepwater Horizon explosion, oil spill, and response, BOEM has determined 

that the incomplete or unavailable information would not be essential to a reasoned 

choice among alternatives because BOEM utilizes the best available scientifically 

credible information in its decisionmaking process and cannot speculate as to the 

results of ongoing Deepwater Horizon NRDA studies.

This chapter has thoroughly examined the existing credible scientific evidence that is relevant to 

evaluating the reasonably foreseeable significant adverse impacts of the proposed WPA lease sale on the 

human environment. The subject-matter experts that prepared this Supplemental EIS conducted a diligent 

search for pertinent information, and BOEM’s evaluation of such impacts is based upon theoretical 

approaches or research methods generally accepted in the scientific community. All reasonably 

foreseeable impacts were considered, including oil-spill impacts that could have catastrophic

consequences, even if their probability of occurrence is low (Appendix A). Throughout this chapter, 

where information was incomplete or unavailable, BOEM complied with its obligations under NEPA to 

determine if the information was relevant to reasonably foreseeable significant adverse impacts; if so, 
Description of the Environment and Impact Analysis 4-9 

whether it was essential to a reasoned choice among alternatives; and, if it was essential, whether it could 

be obtained and whether the cost of obtaining the information was exorbitant, as well as whether 

generally accepted scientific methodologies could be applied in its place (40 CFR § 1502.22). 

4.1.1. Alternative A—The Proposed Action

4.1.1.1. Air Quality

BOEM has reexamined the analysis for air quality presented in the prior 2012-2017 Gulf of Mexico 

EISs based on the additional information presented below. No new information was discovered that 

would alter the impact conclusion for air quality presented in the prior 2012-2017 Gulf of Mexico EISs. 

Further, the analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248.

A detailed description of air quality, along with the full analyses of the potential impacts of routine 

activities, accidental events, and cumulative impacts associated with the WPA proposed action, are 

presented in Chapter 4.1.1.1 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.1 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

Details of air quality modeling are discussed in Appendix A of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below. 

The following routine activities associated with the WPA proposed action would potentially affect air 

quality: platform construction and emplacement; platform operations; drilling activities; flaring; seismicsurvey and support-vessel operations; pipeline laying and burial operations; evaporation of volatile 

petroleum hydrocarbons during transfers; and fugitive emissions. These activities could result in 

emissions that are released to the atmosphere and then influenced by meteorology. This impact analysis 

is based on four parameters—emission rates, surface winds, atmospheric stability, and the mixing height. 

Refer to Chapter 4.1.1.1 of the prior 2012-2017 Gulf of Mexico EISs and Appendix A of the WPA 

238/246/248 Supplemental EIS for details on air quality modeling. Emissions of pollutants into the 

atmosphere from the activities associated with the WPA proposed action are projected to have minimal 

effects on onshore air quality because of the distance from shore where the emissions are released and 

dilution before they reach shore, as well as the prevailing atmospheric conditions; emission rates and 

mixing heights. 

Accidental events that may cause impacts to air quality include the release of oil, condensate, natural 

gas, chemicals used offshore, or pollutants from the burning of these products, as well as fires. The 

accidental release of hydrocarbons related to the WPA proposed action may result in the emission of air 

pollutants. If a fire was associated with the accidental event, it could produce a broad array of pollutants, 

including NAAQS-regulated pollutants, NO2, CO, SO2, particle pollution (PM10, and PM2.5), volatile and 

semivolatile organic compounds, H2S, and CH4. Response activities to an accidental event that could 

impact air quality include in-situ burning, the use of flares to burn gas and oil, and the use of dispersants

applied from aircraft. These response activities are temporary in nature. Measurements taken during an 

in-situ burning show that a major portion of compounds was consumed in the burn (Fingas et al., 1995). 

Accidents involving high concentrations of H2S could result in human deaths as well as environmental 

damage. Regulations and NTLs mandate safeguards and protective measures, which are in place to 

protect workers from H2S releases. Overall, since fires are rare events and are of short duration, potential 

impacts to air quality are not expected to be significant.

The cumulative analysis considers OCS oil- and gas-related and non-OCS oil- and gas-related 

activities that could occur and adversely affect onshore air quality from OCS sources during the 40-year 

analysis period. The OCS oil- and gas-related activities that could impact air quality include the 

following: 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; fugitive emissions; the release of oil, condensate, 

natural gas, and chemicals used offshore, or pollutants from the burning of these products; blowouts; a 

low-probability catastrophic spill, which is not reasonably foreseeable and not part of the WPA proposed 
4-10 Western Planning Area Lease Sale 248 Supplemental EIS

action (refer to Appendix A for more details); and fires. Emissions of pollutants into the atmosphere 

from 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, which result in dilution of the emissions offshore before they reach the 

shoreline. In the WPA, the impacts of the OCS emissions on the onshore air quality are below the U.S. 

Environmental Protection Agency’s Significant Impact Levels (SILs) and BOEM’s Significance Levels, 

and they are well below the NAAQS. The only potential exception is for ozone, where there may be 

some minimal contribution to ozone at the shoreline. However, onshore impacts on air quality from 

emissions from OCS oil- and gas-related activities are estimated to be within the Prevention of Significant 

Deterioration (PSD) Class II allowable increments.

Non-OCS oil- and gas-related activity includes both marine and onshore industries and activities that 

are unrelated to oil and gas exploration and production. The non-OCS oil- and gas-related activities in the 

cumulative scenario that could potentially impact onshore air quality include State oil and gas programs, 

other major offshore but non-OCS oil- and gas-related factors influencing offshore environments (such as 

sand borrowing and transportation), onshore non-OCS oil- and gas-related activities such as emissions 

from industry (including major stationary sources, e.g., power plants, petroleum refineries and chemical 

plants) and mobile sources (cars/trucks) related to human activities, onshore non-OCS oil- and gas-related 

sources unrelated to human activities such as forest fires, accidental releases from an oil spill, accidental 

releases of hydrogen sulfide, and natural events (e.g., hurricanes). Non-OCS oil- and gas-related activity 

on the water that would most likely contribute to cumulative impacts to air quality would be the marine 

shipping or transportation industry. Industrial activity in Texas and Louisiana and vehicle emissions in 

highly populated areas are the onshore sources that would contribute to the cumulative impact to air 

quality. These offshore and onshore emissions sources generate greater amounts of pollutants than OCS

oil- and gas-related activity. Human populations residing near these same industries may encounter air 

contaminants as a result of non-OCS oil- and gas-related activities. These non-OCS oil- and gas-related 

sources would represent the majority of the cumulative emissions that are present at onshore locations.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of State and Federal databases, including updates to regulations, was conducted to determine 

the availability of recent information. The search revealed new information on hurricane impacts on air 

quality and intercontinental sources of fine particles in the atmosphere since publication of the prior 2012-

2017 Gulf of Mexico EISs. This information is pertinent to this Supplemental EIS because it details new 

information on non-OCS oil- and gas-related impacts to the environment, as well as impacts to air quality 

following the Deepwater Horizon explosion, oil spill, and response and Hurricane Isaac.

New information indicates that intercontinental dust from Central America and North Africa has been 

found in the Texas atmosphere. The dust-causing events will contribute to low visibility in Texas. Fine 

particulates (PM2.5), such as ammonium sulfate, can be suspended in the atmosphere and can impair 

visibility and adversely affect human health. Once in the atmosphere, these fine particulates can be 

transported for long distances. It has been observed that a substantial amount of the fine particulates 

observed in Texas comes from Mexico and Central America, and enters into the United States across 

Texas’ southern border. As a result, it reduces the visibility at Big Bend and Guadalupe Mountains 

National Parks, both Class I (pristine with respect to visibility) areas. The results of air dispersion 

modeling indicate that as much as half of the visibility impairment (occurring on 20% of the most 

visibility impaired days) at Big Bend comes from international transport (Texas Commission on 

Environmental Quality, 2014a). Recently, Bozlaker et al (2013) reported that the trans-Atlantic transport 

of North African dust by summertime trade winds occasionally increases ambient particulate matter (PM) 

concentrations in Texas above air quality standards. Exemptions from such exceedances can be sought 

for episodic events that are beyond regulatory control by providing qualitative supportive information. 

The identification of the intercontinental dust is based on the methods of using satellite images, air mass 

back-trajectories, and chemical aerosol measurements. These results indicate that an increase in visibility 

impairment in Texas is likely due to international transport of dust rather than OCS emission sources.

New information has been released with respect to air quality near beaches oiled during the 

Deepwater Horizon explosion, oil spill, and response following Hurricane Isaac. Hurricane Isaac did 
Description of the Environment and Impact Analysis 4-11

result in the suspension of small amounts of tarballs, tar mat fragments, and some oil from sediments 

(Auburn University, Samuel Ginn College of Engineering, 2012; Mulagabal et al., 2013); however, 

the impact of the air emissions from this hurricane event on the onshore air quality was very small. The 

Offshore and Coastal Dispersion modeling results, which are discussed in Appendix A of the WPA 

238/246/248 Supplemental EIS and which are incorporated by reference here, indicate that typical 

operations on the OCS do not generate pollutants in an amount that would significantly impact or 

significantly contribute to air quality degradation in Texas and that the same applies to emissions that are 

generated from isolated events (e.g., accidents, which are temporary sources).

During June 8 and 10, 2010, an aircraft performed flights to characterize pollutants emitted from the 

Deepwater Horizon explosion, oil spill and response. These flights measured organic aerosol particles 

and VOCs (Bahreini et al., 2012). According to Perring et al. (2011), approximately 4 percent of the 

combusted material from the Deepwater Horizon oil spill was released into the atmosphere as black 

carbon particulates. In the presence of evaporating hydrocarbons from the oil spill, NOx emissions from 

the recovery and cleanup activities produced ozone (Middlebrook et al., 2012). 

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined the new information does not 

change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs. However, as discussed in 

this Supplemental EIS, as well as in Chapter 4.1.1.1 of the prior 2012-2017 Gulf of Mexico EISs, BOEM 

has identified incomplete or unavailable information regarding air impacts from the Deepwater Horizon

explosion, oil spill, and response in the WPA, as well as inherent limitations resulting from conservative 

air quality modeling. 

Although final summary information and reports on air quality impacts in the WPA from the 

Deepwater Horizon explosion, oil spill, and response may be forthcoming, the final and conclusive 

information is not available at this time and will not be available within the timeline contemplated in the 

NEPA analysis of this Supplemental EIS. This unavailable information may be relevant to adverse 

effects and possible long-term effects because air emissions could have reached land or dispersed 

throughout the WPA before oil-spill response was activated. BOEM used reasonably accepted scientific 

methodologies to extrapolate from available information on air quality measurements taken by Federal 

agencies in completing the relevant analysis to determine air impacts (USEPA, 2010a; de Gouw et al., 

2011; Auburn University, Samuel Ginn College of Engineering, 2012; Mulagabal et al., 2013). Limited 

data released to the public and obtained from USEPA, NOAA, and other agencies indicating that air 

impacts tended to be minor and below USEPA’s health-based standards were extrapolated to come to the 

conclusion that air quality impacts in the WPA resulting from the Deepwater Horizon explosion, oil spill, 

and response were minor because of its distance from the WPA. Data obtained from USEPA, NOAA, 

and other agencies do not reveal reasonably foreseeable significant adverse impacts in the WPA, and 

because there are no continuing sources of air pollution related to the Deepwater Horizon explosion, oil 

spill, and response, BOEM would not expect any additional measurements or information to alter the 

conclusions from currently existing data. Therefore, BOEM has determined that the information is not 

essential to a reasoned choice among alternatives.

In addition, as noted in Appendix A of the WPA 238/246/248 Supplemental EIS, there are a number 

of competing methods and available models for estimating and tracking potential air emissions and 

impacts. Each of these methods and models has inherent limitations, particularly with regard to the 

offshore environment in which the WPA proposed action would take place. BOEM’s Offshore and 

Coastal Dispersion Model, which was used for this environmental impact assessment (Appendix A of the 

WPA 238/246/248 Supplemental EIS), has limitations such that it is a short-range dispersion model and it 

does not involve the reactive gases, which include ozone (O3), carbon monoxide (CO), volatile organic 

compounds (VOCs), oxidised nitrogen compounds (NOx), and sulphur dioxide (SO2). In 

acknowledgement of these limitations, BOEM’s subject-matter experts, using their best professional 

judgment and experience, have developed conservative assumptions and modeling parameters so as to 

ensure that the impact conclusions herein are reasonable and not underestimated (refer to Appendix A of 

the WPA 238/246/248 Supplemental EIS for the modeling analysis). The modeling that was conducted 

was conservative. All of the emissions during 1 year for the entire WPA, which would actually be 

dispersed throughout the WPA, were modeled as if they originated in a single block, East Breaks Block 

446. This block was selected because it represented a location where the water is deep enough that a 
4-12 Western Planning Area Lease Sale 248 Supplemental EIS

dynamically positioned drillship would be used and where hydrocarbons are reasonably expected to be

present. Although there are limitations in air quality modeling, the evidence currently available and that 

was used to develop conservative assumptions supports past analyses and does not indicate severe adverse 

impacts to air quality. Therefore, BOEM has determined that the incomplete information is not essential 

to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for air quality presented in the prior 2012-2017 Gulf of Mexico 

EISs based on the additional information presented above. Emissions of pollutants into the atmosphere 

from the routine and accidental activities associated with the WPA proposed action are projected to have 

minimal impacts to onshore air quality, and emissions of pollutants into the atmosphere from activities 

associated with the OCS Program are also not projected to have significant effects on onshore air quality. 

The non-OCS oil- and gas-related emission sources of intercontinental origin may have the potential to 

impact onshore air quality and human health. However, the new information does not alter previous 

impact conclusions for air quality. The analysis and potential impacts detailed and updated in the prior 

2012-2017 Gulf of Mexico EISs still apply for proposed WPA Lease Sale 248. 

4.1.1.2. Water Quality

4.1.1.2.1. Coastal Waters

Coastal waters within the WPA, as defined by BOEM, include all the bays and estuaries from the Rio 

Grande River to the Louisiana/Texas border. BOEM has reexamined the analysis for coastal water 

quality presented in the prior 2012-2017 Gulf of Mexico EISs based on the additional information 

presented below. No new information was discovered that would alter the impact conclusion for coastal 

water quality presented in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential 

impacts detailed and updated in those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of coastal water quality, along with the full analyses of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.2.1 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.2.1 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below. 

The routine activities associated with proposed WPA Lease Sale 248 that could impact water and 

associated sediment quality include the following: discharges during drilling of exploration and 

development wells; structure installation and removal; discharges during production; installation of 

pipelines; workovers of wells; maintenance dredging of existing navigational canals; service-vessel 

discharges; and nonpoint-source runoff from platforms and OCS Program-related vessels. The primary 

impacting sources affecting water quality in coastal waters are point-source and storm-water discharges 

from support facilities, vessel discharges, and nonpoint-source runoff. The impacts to coastal water 

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

distance to shore of most routine activities, USEPA and USCG regulations that regulate the discharge of 

pollutants, and the few, if any, new pipeline landfalls or onshore facilities that would be constructed as a 

result of the WPA proposed action. 

Accidental events associated with the WPA proposed action that could impact coastal water quality

include spills of oil and refined hydrocarbons, releases of natural gas and condensate, spills of chemicals 

or drilling fluids, loss of well control, pipeline failures, vessel collisions, or other malfunctions that would 

result in such spills. Oil, gas, and chemical releases may degrade water quality and reduce oxygen in the 

water column. Pipeline breaks and vessel collisions in bays and estuaries would be the greatest risk for 

delivering concentrated contaminants to coastal waters. For coastal spills (those that occur in bays and 

estuaries), two additional factors that must be considered for the impacts of water quality on habitats are 

the shallowness of the area where the oil spill occurred and the proximity of the spill to shore because 

these spills are less likely to be diluted before they reach the shore and can impact sediment quality. 
Description of the Environment and Impact Analysis 4-13

However, spills from vessel collisions in coastal waters are not expected to be significant because vessel 

collisions occur infrequently. Those spills occurring in OCS waters would be diluted before they reached 

the bays and estuaries, and natural degradation processes will also decrease the concentration of spilled 

oil over time. Although response efforts to accidental releases may decrease the amount of oil in the 

environment, the response efforts may also impact the environment through, for example, increased 

vessel traffic, hydromodification (e.g., dredging, berm building, boom deployment, etc.), and application 

of dispersants. Chemicals spills are not a significant risk because the chemicals used by the OCS oil and 

gas industry are either nontoxic, used in minor quantities, or only used on a noncontinuous basis. 

Therefore, the impact of routine OCS oil- and gas-related activities on coastal water quality from smaller 

accidental spills is expected to be minimal.

Coastal waters are vulnerable to the cumulative impacts from OCS oil- and gas-related activities, 

including erosion and runoff, sediment disturbance and turbidity from dredging, vessel discharges, and 

accidental releases of oil, gas, or chemicals. Erosion and runoff may degrade water quality; however, 

OCS oil- and gas-related activities are not the leading source of contaminants that impair coastal water 

quality. The leading source of contaminants that impair coastal water quality is urban runoff, which is 

discussed in the next paragraph. Increased turbidity and discharge from the WPA proposed action would 

be temporary in nature and minimized by regulations and mitigation. Accidental oil, gas, and chemical 

spills in bays and estuaries can result in degraded water quality in the coastal environment. Water and 

sediment quality degradation would be greater for spills that occurred in the bays and estuaries than those 

that occurred in OCS waters and traveled to the bays and estuaries because the spills traveling from OCS 

waters would be dispersed or diluted before they reached the coastal waters. A catastrophic OCS 

Program-related accident, which is not part of the proposed action, would be rare and not expected to 

occur in coastal waters. An oil spill as a result of a low-probability catastrophic event, which is not part 

of the WPA proposed action and not likely expected to occur, is discussed in Appendix A. 

Coastal waters are vulnerable to impacts from non-OCS oil- and gas-related activities or activities not 

related to the WPA proposed action or the OCS Program, including State oil and gas activities, alternative 

energy activities, alternate use programs for platforms (e.g., aquaculture), sand borrowing, the activities 

of other Federal agencies (including the military), natural events or processes, and activities related to the 

direct or indirect use of land and waterways by the human population and industry. These activities may 

result in runoff, sediment disturbance and turbidity, vessel discharges, and accidental releases of oil, gas, 

or chemicals. Many of these factors have a major impact on water quality, but the greatest threat to 

coastal water quality is urban runoff.

The impacts resulting from the WPA proposed action would not significantly contribute to the 

cumulative impacts on the coastal waters of the GOM because non-OCS oil- and gas-related activities, 

including vessel traffic, erosion, and nonpoint source runoff, are cumulatively responsible for the majority 

of coastal water impacts. Additionally, a catastrophic OCS Program-related accident is not expected to 

occur in coastal waters. Furthermore, the impact on coastal water quality resulting from smaller 

accidental spills is expected to be minimal in comparison to the cumulative impacts from other sources. 

Therefore, the incremental contribution of the routine activities associated with the WPA proposed action 

to the cumulative impacts on coastal water quality is not expected to be significant.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

Various Internet sources were examined and literature searches conducted in order to assess the 

availability of new information regarding the water quality and sediment quality in coastal waters that 

may be pertinent to the WPA proposed action. The searches included, but were not limited to, Google, 

Google Scholar, and several USEPA websites. New information was found on the affected environment 

in relation to coastal sediment hydrocarbon concentrations and the Louisiana-Texas hypoxic zone. 

Sammarco et al. (2013) conducted a regional study using approximately 70 sediment samples in 

coastal waters from Galveston, Texas, to the Florida Keys. Sediment total petroleum hydrocarbon and 

total polycyclic aromatic hydrocarbon (PAH) concentrations peaked in samples near Pensacola, Florida, 

and Galveston, Texas, and were lower in other sample locations along the coast. The sediment samples 

collected between May 17, 2010, and November 8, 2010, exhibited a mean total petroleum hydrocarbon 

concentration of 39,400 milligrams/kilogram (mg/kg) and a mean total PAH concentration of 178 mg/kg, 
4-14 Western Planning Area Lease Sale 248 Supplemental EIS

indicating that PAHs make up less than 1 percent of the total hydrocarbon concentration. Sammarco et al. 

(2013) did not conclude a definitive source(s) of the oil impacts, but the study describes a baseline for 

hydrocarbons in coastal sediments.

Louisiana Universities Marine Consortium (LUMCON) generally forecasts the seasonal maximum 

size of the Louisiana-Texas hypoxic zone based on nitrogen loading in the Mississippi River as measured 

in May of each year, and the actual size reported is based on cruise data collected by LUMCON in July of 

each year. The most recent 2014 GOM dead zone covered 13,080 km2 (5,052 mi2

), smaller than the 2013 

hypoxic zone (15,120 km2 or 5,800 mi2

). The 2014 hypoxic zone was smaller than the 5-year average 

(14,352 km2 or 5,543 mi2

) but larger than the Action Plan Goal of 5,000 km2 or 1,991 mi2 (LUMCON, 

2014). This information is an update to previous evaluations of the hypoxic zone, which is not considered 

to be related to OCS oil- and gas-related activities, but it is discussed as a potential cumulative effect on 

coastal water quality. The dissolved oxygen conditions in the hypoxic zone are sufficiently low so that 

they are considered an impact-producing factor for marine species in the area. While limited in area, the 

hypoxic zone produces more significant impacts than OCS oil- and gas-related activities, which may 

consume dissolved oxygen but which are smaller in geographic extent due to dilution. 

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is 

still incomplete or unavailable information. As discussed in this Supplemental EIS, as well as in Chapter 

4.1.1.2 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete or unavailable 

information that may be relevant to reasonably foreseeable impacts on coastal water quality. Much of this 

information relates to the Deepwater Horizon explosion, oil spill, and response and is continuing to be 

collected and developed through the NRDA process. These research projects may be years from 

completion. It is not possible for BOEM to obtain this information and incorporate it within the timeline 

contemplated in the NEPA analysis of this Supplemental EIS regardless of the costs or resources needed. 

Few conclusions have been released to the public to date, though, extensive datasets have now been 

released to the public (refer to USDOC, NOAA, 2013), and peer-reviewed academic research has been 

and continues to be published relevant to this topic. The Federal Government’s reports and peer-reviewed 

journal articles that are available at this time have been discussed in Chapters 4.1.1.2.1 and 4.2.1.2.1 of 

the prior 2012-2017 Gulf of Mexico EISs. BOEM extrapolated existing information using reasonably 

accepted scientific methodologies to come to the conclusion that oil from the spill did not reach the water 

and sediment in the WPA. The NOAA has estimated that the westernmost extent of visible sheens related 

to oil from the Deepwater Horizon explosion and oil spill extended no farther than Cameron Parish, 

Louisiana, which is to the east of the WPA boundary (Figure 1-2 of the 2012-2017 WPA/CPA Multisale 

EIS), and data collected by the Operational Science Advisory Team (OSAT) indicate that the Deepwater 

Horizon oil spill did not reach WPA waters or sediments (OSAT, 2010). Given the available data on 

coastal sediments and water quality that have been released and evaluated, as described above and in 

Chapters 4.1.1.2.1 and 4.2.1.2.1 of the prior 2012-2017 Gulf of Mexico EISs, as well as the distance of 

the WPA from the Macondo well, water and sediment quality within the WPA were likely not affected to 

any discernible degree by the Deepwater Horizon explosion, oil spill, and response. Therefore, BOEM 

believes that this incomplete or unavailable information is not essential to a reasoned choice among 

alternatives for the reasons stated herein and in the prior 2012-2017 Gulf of Mexico EISs. 

Summary and Conclusion

BOEM has reexamined the analysis for coastal water quality presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented above. No new information was discovered 

that would alter the impact conclusion for coastal water quality presented in the prior 2012-2017 Gulf of 

Mexico EISs. The analysis and potential impacts detailed and updated in the prior 2012-2017 Gulf of 

Mexico EISs still apply for proposed WPA Lease Sale 248.

4.1.1.2.2. Offshore Waters

Offshore waters within the WPA, as defined by BOEM, include both Texas offshore waters and 

Federal OCS waters, which includes everything outside any barrier islands to the Exclusive Economic 
Description of the Environment and Impact Analysis 4-15

Zone. BOEM has reexamined the analysis for offshore water quality presented in the prior 2012-2017 

Gulf of Mexico EISs based on the additional information presented below. No new information was 

discovered that would alter the impact conclusion for offshore water quality presented in the prior 2012-

2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in those 

NEPA documents still apply for proposed WPA Lease Sale 248. 

A detailed description of offshore water quality, along with the full analyses of the potential impacts 

of routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.2.2 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.2.2 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description incorporated from the prior 2012-

2017 Gulf of Mexico EISs. Any new information that has become available since those NEPA

documents were published is presented below. 

The routine activities associated with proposed WPA Lease Sale 248 that would impact offshore 

water quality may include the following: discharges during drilling of exploration and development 

wells; structure installation and removal; discharges during production; installation of pipelines; 

workovers of wells; service-vessel discharges; and nonpoint-source runoff. During exploratory activities, 

the primary impacting sources affecting offshore water quality are discharges of drilling fluids and 

cuttings. During platform installation and removal activities, the primary impacting sources affecting

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 toxicity of the discharge components, the levels of incidental contaminants in these discharges, and in 

some cases, the discharge rates and discharge locations. Pipeline installation can also affect water quality 

by sediment disturbance and increased turbidity. Service-vessel discharges might include water with an 

oil concentration of approximately 15 parts per million. Impacts to offshore waters from routine activities 

associated with the WPA proposed action should be minimal due to regulations that limit the pollutant 

concentrations and toxicity of discharges.

Accidental events associated with the WPA proposed action that could impact offshore water quality

include spills of oil and refined hydrocarbons, releases of natural gas and condensate, spills of chemicals 

or drilling fluids, loss of well control, pipeline failures, collisions, or other malfunctions that would result 

in such spills. Oil, gas, and chemical releases may degrade water quality and reduce oxygen in the water 

column, which may affect the health of marine biota. Spills from platforms and pipelines would be the 

greatest risk for delivering concentrated contaminants to offshore waters. Overall, since major losses of 

well control are rare events, potential impacts to offshore water quality are not expected to be significant. 

Spills from collisions are not expected to be significant since these offshore spills occur relatively 

infrequently and often disperse and degrade prior to reaching shore. Although response efforts may 

decrease the amount of oil in the environment, the response efforts may also impact the environment 

through, for example, increased vessel traffic and the application of dispersants. Natural degradation 

processes in both surface and subsurface waters would decrease the amount of spilled oil over time 

through natural processes that can physically, chemically, and biologically degrade oil (NRC, 2003). 

Chemicals used in the oil and gas industry are not a significant risk to water quality because they have 

low toxicity, and spill risk is reduced because the chemicals are used in minor quantities or are only used 

on a noncontinuous basis. Therefore, the impact of accidental (noncatastrophic) events is expected to be 

small.

Offshore waters are vulnerable to cumulative impacts from OCS oil- and gas-related activities 

including sediment disturbance and turbidity, vessel discharges, discharges from exploration and 

production activities, and accidental releases of oil, gas, or chemicals. Routine activities that increase 

turbidity and discharges are temporary in nature and are regulated; therefore, these activities would not 

have a lasting adverse impact on water quality. In the case of an offshore oil spill, degradation processes 

in both surface and subsurface waters would decrease the concentration of spilled oil over time. An oil 

spill as a result of a low-probability catastrophic event, which is not part of the WPA proposed action and 

is not likely expected to occur, could impact offshore water quality. Low-probability catastrophic spills

are discussed in Appendix A. The impacts resulting from the WPA proposed action are a small addition 

to the cumulative impacts on the offshore waters of the Gulf of Mexico.
4-16 Western Planning Area Lease Sale 248 Supplemental EIS

Offshore waters are also vulnerable to impacts from activities not related to the WPA proposed action 

or the OCS Program, including State oil and gas activities, alternative uses of platforms (e.g., 

aquaculture), sand borrowing, renewable energy activities, the activities of other Federal agencies 

(including the military), natural events or processes, permitted ocean disposal of wastes, and activities 

related to the direct or indirect use of land and waterways by the human population (e.g., urbanization, 

agricultural practices, coastal industry, and municipal wastes). These activities may result in erosion and 

runoff, sediment disturbance and turbidity, vessel discharges, natural releases of oil and gas (e.g., seeps), 

and accidental releases of oil, gas, or chemicals. Although some of these impacts are likely to affect 

coastal areas to a greater degree than offshore waters, coastal pollutants that are transported away from 

shore will also affect offshore environments. Offshore sediments and water quality may also be directly 

impacted by the disposal of wastes, some of which may have a greater impact on the offshore 

environment than OCS oil- and gas-related activities. Many of the above factors not related to the WPA 

proposed action or the OCS Program may have a major impact on water quality. 

The impacts resulting from the WPA proposed action would be a small addition to the cumulative 

impacts on the offshore waters of the Gulf when compared with inputs from natural hydrocarbon inputs 

(seeps), coastal factors (such as erosion and runoff), and other non-OCS oil- and gas-related industrial 

discharges. Since a catastrophic accident is rare, and not part of the proposed action, the probability of 

impact from such accidents is expected to be small. Also, accidental events in offshore waters allow 

more opportunity to mitigate impacts before the spill enters coastal waters where it could pose a higher 

risk of harm. The incremental contribution of the routine activities associated with the WPA proposed 

action to the cumulative impacts on offshore water quality is not expected to be significant.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

Various Internet sources were examined and literature searches conducted in order to assess the 

availability of new information regarding the water quality and sediment quality in offshore waters that 

may be pertinent to the WPA. The searches included, but were not limited to, Google, Google Scholar, 

and several USEPA websites. New information was found in relation to historic non-OCS oil- and gasrelated activities that constitute a potential cumulative effect on the offshore environment.

Between 1940 and 1970, certain offshore locations of the United States were used for the disposal of 

various industrial wastes and low-level radioactive wastes, these activities being large, unrecorded, and 

unregulated (USDOC, NOAA, 2015). 

The Marine Protection, Research, and Sanctuaries Act of 1972 (also known as the Ocean Dumping 

Act) was promulgated to regulate ocean dumping and set aside certain areas as national marine 

sanctuaries. Section 101 (33 U.S.C. § 1411) of the Act prohibited ocean dumping, except as authorized 

by permit issued by the USEPA pursuant to Section 102 (33 U.S.C. § 1412). 

In 1973, the USEPA permitted, through Section 102 (33 U.S.C. § 1412), two interim chemical 

disposal sites in the Gulf of Mexico, the charting of which has been maintained by NOAA. Disposal 

Site A, located within the WPA, is situated on the upper part of the Texas-Louisiana continental shelf, 

approximately 125 mi (201 km) southwest of Galveston, Texas. Disposal Site B is located in the CPA off 

the western side of the Mississippi Delta, approximately 60 mi (7 km) south of the mouth of the 

Mississippi River.

BOEM recently became aware of the report, Assessing Potential Ocean Pollutants, which was 

published by the National Academy of Sciences (NAS, 1975). This report provided a new understanding 

of the disposal site conditions. 

At Site A, uncontained wastes were discharged through a submerged pipe into the turbulent wake of a 

barge. At Site B, waste materials were placed in barrels before discharge. Chemical wastes discharged at 

these sites reportedly had various concentrations of chlorinated hydrocarbons, calcium and sodium 

metals, formaldehyde, cyanide, and other metals (i.e., antimony, mercury, arsenic, zinc, manganese, and 

iron). Seven permits issued by the USEPA in 1973 allowed for the disposal of 84,500 tons of 

uncontained waste at Site A and 208,500 waste barrels at Site B, of which approximately 55,000 barrels 

contained chlorinated hydrocarbons. Chlorinated hydrocarbons were used during the Vietnam War to 

produce pesticides and defoliants (e.g., Agent Orange). 
Description of the Environment and Impact Analysis 4-17

Site B is discussed in the Information to Lessees and Operators (ITL), “Central Planning Area, Oil 

and Gas Lease Sale 213, Section (t), Commercial Waste Disposal Areas” (February 12, 2010). In the 

ITL, lessees are advised that the blocks associated with the disposal site and the adjacent blocks 

associated with the disposal site that were included in CPA Lease Sale 213 should be considered 

potentially hazardous. Drilling and platform/pipeline placement may require precautions such as 

avoidance upon identification and any other appropriate precautions. No such ITL currently exists for 

Site A.

These chemical waste disposal sites are pertinent to this impact analysis because they constitute a 

potential cumulative effect on offshore water and sediment quality, and they may expose benthic 

organisms to contaminants. Some of the constituents listed in the NAS report are carcinogenic, and 

others may bioaccumulate in marine ecosystems. As of this writing, barrels dumped at Site B in 1973 

have been under water for 42 years and may have started to release their contents. As such, the potential 

impacts from Sites A and B must be considered in marine environmental assessments of the Gulf of 

Mexico.

This new information indicates that some of the wastes disposed of on the OCS may have a greater 

environmental impact than offshore OCS oil- and gas-related activity. Chlorinated hydrocarbons are 

denser than seawater and may sink into sediments if released from the waste barrels. These compounds 

may also dissolve in water and will form a persistent, localized contaminant plume in the water column as 

long as the source remains. In contrast, petroleum hydrocarbon compounds originating from OCS oiland gas- related activities are considered degradable and do not persist in the water column after the 

source is removed.

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. As discussed in this Supplemental EIS and in Chapter 4.1.1.2 of 

the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete or unavailable information 

that may be relevant to reasonably foreseeable impacts on offshore water quality. Much of this 

information relates to the Deepwater Horizon explosion, oil spill, and response and is continuing to be 

collected and developed through the NRDA process. These research projects may be years from 

completion. Few conclusions have been released to the public to date, and peer-reviewed academic 

research has been and continues to be published relevant to this topic. The Federal Government’s reports 

and peer-reviewed journal articles that are available at this time have been discussed in the prior 2012-

2017 Gulf of Mexico EISs. BOEM extrapolated existing information using reasonably accepted scientific 

methodologies to conclude that oil did not reach the water and sediment in the WPA. The NOAA has 

estimated that the westernmost extent of visible sheens related to oil from the Deepwater Horizon

explosion and oil spill extended no farther than Cameron Parish, Louisiana, which is to the east of the 

WPA boundary (Figure 1-2 of the 2012-2017 WPA/CPA Multisale EIS), and data collected by OSAT 

indicate that the Deepwater Horizon oil spill did not reach WPA waters or sediments (OSAT, 2010). 

Given the available data on offshore sediments and water quality that have been released and evaluated, 

as well as the distance of the WPA from the Macondo well, water and sediment quality within the WPA 

were likely not affected to any discernible degree by the Deepwater Horizon explosion, oil spill, and 

response. Therefore, BOEM believes that this incomplete or unavailable information is not essential to a 

reasoned choice among alternatives for the reasons stated herein and in the prior 2012-2017 Gulf of 

Mexico EISs.

Summary and Conclusion

BOEM has reexamined the analysis for offshore water quality presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information presented above. No new information was 

discovered that would alter the impact conclusion for offshore water quality presented in the prior 2012-

2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and updated in the prior 2012-

2017 Gulf of Mexico EISs still apply for proposed WPA Lease Sale 248.
4-18 Western Planning Area Lease Sale 248 Supplemental EIS

4.1.1.3. Coastal Barrier Beaches and Associated Dunes

BOEM has reexamined the analysis for coastal barrier beaches and associated dunes presented in the 

prior 2012-2017 Gulf of Mexico EISs based on the additional information presented below. No new 

information was discovered that would alter the impact conclusion for coastal barrier beaches and 

associated dunes previously presented in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis 

and potential impacts detailed and updated in those NEPA documents still apply for proposed WPA Lease 

Sale 248. 

A detailed description of coastal barrier beaches and associated dunes, along with the full analyses of 

the potential impacts of routine activities, accidental events, and cumulative impacts associated with the 

WPA proposed action, are presented in Chapter 4.1.1.3 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.3 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has 

become available since those NEPA documents were published is presented below. 

The major routine impact-producing factors associated with the WPA proposed action that could 

affect coastal barrier beaches and associated dunes include navigational traffic, maintenance dredging of 

navigational canals, pipeline emplacements/landfalls, and construction and expansion of navigational 

canals and port facilities. Effects on coastal barrier beaches and associated dunes from pipeline 

emplacements, navigation channel use and dredging, and construction or continued use of infrastructure

in support of the WPA proposed action are expected to be restricted to temporary and localized 

disturbances such as land loss and erosion. The 0-1 pipeline landfalls projected in support of the WPA 

proposed action are not expected to cause significant impacts to barrier beaches because of the use of 

nonintrusive installation methods and regulations. Impacts could be reduced or eliminated through 

modern techniques, such as horizontal directional (trenchless) drilling, to avoid damages to these sensitive 

beach habitats. Any new gas processing facilities would not be expected to be constructed on barrier 

beaches. The WPA proposed action may contribute to the continued use of gas processing facilities that 

already exist. Existing pipelines, in particular those that are parallel and landward of beaches and that had 

been placed on barrier islands using older techniques that left canals or shore protection structures, have 

caused and could continue to cause barrier beaches to narrow and breach.

Maintenance dredging of barrier inlets and bar channels is expected to occur, which, when combined 

with channel jetties, generally causes minor and localized impacts on adjacent barrier beaches downdrift 

of the channel. Navigational channels that support the OCS Program are listed in Table 3-11 of the WPA 

238/246/248 Supplemental EIS. Dredging activities in these channels for both vessel traffic and pipeline

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

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

of the dredged material for wetland and beach construction and restoration. Permit requirements further 

mitigate dredged material placement in approved disposal areas by requiring the dredged material to be 

placed in such a manner that it neither disrupts hydrology nor changes elevation in the surrounding marsh. 

Because these impacts occur whether the WPA proposed action is implemented or not, the WPA 

proposed action would only account for a small percentage of such impacts. The WPA proposed action is 

not expected to adversely alter barrier beach configurations much beyond existing, ongoing impacts in 

localized areas downdrift of artificially jettied and maintained channels.

Accidental disturbances resulting from the WPA proposed action, including oil spills, have the 

potential to impact coastal barrier beaches and associated dunes of the WPA. Potential impacts from oil 

spills to barrier islands seaward of the barrier-dune system are discussed below, while potential impacts to 

barrier islands landward of the barrier-dune system are considered in the wetlands analysis (refer to 

Chapter 4.1.1.4). Due to the proximity of spills in a river, bay, or estuary to barrier islands and beaches, 

these spills pose the greatest threat because of the concentration and lack of weathering of the oil by the 

time it hits the shore and because dispersants applied to such spills are not an effective means of spill 

response because they do not break the oil down sufficiently before it hits the shoreline. Such spills may 

result from either vessel collisions that release fuel and lubricants or from pipelines that rupture. Crude 

oil from a spill that occurs in OCS waters would be lessened in toxicity if it reaches the coastal 

environments due to its distance from shore, weathering, the time oil remains offshore, and possibly the 
Description of the Environment and Impact Analysis 4-19

dispersant used, if any. Equipment and personnel used in cleanup efforts can generate the greatest direct 

impacts to an oiled area. Close monitoring and restrictions on the use of bottom-disturbing equipment 

would be needed to avoid or minimize impacts. The cleanup impacts of these spills could result in a 

short-term (up to 2 years) adjustment in beach profiles and configurations during cleanup operations. 

Some impact as a result of physical 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 further erosion, particularly if oil is carried onto dunes by 

hurricanes. 

Currently available information suggests that impacts on barrier islands and beaches from accidental 

events associated with the WPA proposed action would be minimal due to the projected spill rates, small 

additional risk from the proposed WPA lease sale, distance of most activity from shore, and anticipated 

weathering of oil spilled in OCS waters before it reaches shore. Should a spill other than a lowprobability catastrophic spill contact a barrier beach, oiling is expected to be light and sand removal 

during cleanup activities minimized. No significant long-term impacts to the physical shape and structure 

of barrier beaches and associated dunes are expected to occur as a result of the WPA proposed action. 

Therefore, the WPA proposed action would not pose a significant increase in risk to barrier island or 

beach resources.

Specific OCS oil- and gas-related impact-producing factors considered in this cumulative analysis 

include dredging, construction and expansion of navigational canals and port facilities, pipeline

emplacement/landfalls, vessel traffic, oil spills, and oil-spill response and cleanup activities. Under the 

cumulative scenario, 0-1 OCS oil- and gas-related 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. Impacts from existing infrastructure could continue to cause barrier beaches to narrow and 

breach. The impacts of oil spills from OCS oil- and gas-related sources to the Texas coast should not 

result in long-term alteration of landforms if the beaches are cleaned using techniques that do not 

significantly remove sand from the beach or dunes. Barrier beaches in the region around Galveston have 

the greatest risks of sustaining impacts from oil-spill landfalls because of the high concentrations of oil 

production near that coast and the high volume of oil transported by ships in that area. Oil spills as a 

result of a low-probability catastrophic event, which are not part of the proposed action and not likely 

expected to occur, are discussed in Appendix A. 

Non-OCS oil- and gas-related impacts include non-OCS oil- and gas-related vessel traffic, beach 

protection and stabilization projects, sea-level rise, subsidence, development and urbanization, tourism, 

recreational activities, and potential for nearshore salinity modifications (such as preparation of salt 

domes for oil storage). In addition, oil spills and oil-spill response and cleanup activities can originate 

from non-OCS oil- and gas-related activities, e.g., international tankers or oil and gas exploration in State 

waters. River channelization, sediment deprivation, tropical and extra-tropical storm activity, sea-level 

rise, and rapid submergence have resulted in erosion of most of the barrier and shoreline landforms along 

the Louisiana coast. The Texas coast has experienced land loss due to a decrease in the volume of 

sediment delivered to the coast because of channelization and damming of 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. Storm-induced changes in hydrology have, in some cases, changed the 

current regime responsible for stabilizing the barrier islands. Some beach stabilization projects are 

considered by coastal geomorphologists and engineers to accelerate coastal erosion. The beneficial use of 

maintenance dredged materials and other restoration techniques could be required to mitigate some of 

these impacts. Recreational use of many barrier beaches in the WPA is intense due to their accessibility 

by roads (refer to Chapter 4.1.1.18). These activities can cause changes to the beach landscapes. There 

are ongoing restoration efforts to minimize damages to beaches from both natural and human impacts. 

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 severe local impacts and accelerate the 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 

(Texas), and county governments have made efforts through the Texas Coastal Erosion Planning and 
4-20 Western Planning Area Lease Sale 248 Supplemental EIS

Response Act program and Coastal Management Plan program to restore or protect the sensitive and 

vulnerable barrier islands and mainland beaches.

The WPA proposed action is not expected to adversely alter barrier beach configurations 

significantly. The WPA proposed action is not expected to increase the probabilities of oil spills beyond 

the current estimates. 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 the WPA proposed action to the cumulative impacts on coastal barrier 

beaches and associated dunes is expected to be small.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search was conducted for information published on barrier beaches and dunes, and various sources 

were examined to determine any recent information regarding barrier beaches and dunes. Sources 

investigated include BOEM; the U.S. Department of the Interior, Geological Survey (USGS); National 

Wetlands Research Center; the USGS Gulf of Mexico Integrated Science Data Information Management 

System; Gulf of Mexico Alliance; and USEPA. Scientific publication databases (including Science 

Direct, Elsevier, the NOAA Central Library National Oceanographic Data Center, and JSTOR) were 

checked for new information using general Internet searches based on major themes. New information 

has been found on oiled beaches following the Deepwater Horizon explosion, oil spill, and response, as 

well as on the effect of extreme storms on dunes, which provides additional baseline information for the 

affected environment.

Snyder et al. (2014) found that PAH contamination on beaches can be monitored using Coquina 

clams and that PAH levels in the clams found adjacent to beach habitats in Florida decreased 

continuously to below detection limits within 2 years of deposition of oil from the Deepwater Horizon oil 

spill on the beaches. The study showed that surf zone molluscs can be used to monitor pollutant exposure 

along beach shorelines.

Additionally, Boufadel et al. (2014) used simulations of the Deepwater Horizon explosion and oil 

spill to estimate that the mass of oil that reached the shorelines was between 10,000 and 30,000 tons 

(55,000 and 165,000 bbl), with an expected amount of 22,000 tons (121,000 bbl). The model found that 

over approximately 96 percent of the oil deposition occurred on Louisiana shorelines. 

With respect to storm events and recovery of coastal beach and dune habitats, Long et al. (2014) 

compared characteristics of four extreme storms with resulting impacts to dune elevations and found that 

dune elevation may be more affected from lower water levels where waves drive sediment over the dune 

compared with surge-dominated flooding events. In a study of beaches in the aftermath of hurricanes, 

Houser et al. (2015) quantified the recovery rate of beaches and dunes in Texas and Florida and found 

that dune heights took approximately 6-10 years to return to pre-storm heights. 

These studies serve to expand our understanding of the baseline environment following the

Deepwater Horizon explosion, oil spill, and response. They also provide information about the 

continuing impacts in the years following oil contamination of beaches, as well as providing information 

on bioindicators of the beach’s health and recovery. These new data also show the resiliency of beaches 

after hurricanes. However, these studies do not change the conclusions of the above-referenced NEPA

documents because the WPA proposed action has a low probability of resulting in a catastrophic oil spill 

and because the WPA proposed action would only result in a small, incremental increase in the 

cumulative impacts to coastal barrier beaches and associated dunes. 

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is 

still incomplete or unavailable information. As identified in the resource analyses in this Supplemental 

EIS and in the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete or unavailable 

information on impacts to beaches from the Deepwater Horizon explosion, oil spill, and response. This 

incomplete or unavailable information may be relevant to reasonably foreseeable significant adverse 

effects because recent events such as the Deepwater Horizon explosion, oil spill, and response may have 
Description of the Environment and Impact Analysis 4-21

caused changes to baseline conditions for coastal barrier beaches and associated dunes of the Gulf of 

Mexico. A large body of information regarding impacts of the Deepwater Horizon explosion, oil spill, 

and response upon coastal beaches and associated dunes is being developed through the NRDA process, 

but this information is not yet available. BOEM used existing information and reasonably accepted 

scientific methodologies to extrapolate from available information in completing the relevant analysis. 

The following information updates or adds to the understanding of incomplete or unavailable information 

for this resource.

As part of its analysis, BOEM evaluated numerous studies that increase our understanding of how 

bacterial communities present in coastal beaches gradually degraded the oil that was stranded on these 

beaches (Urbano et al., 2013; Newton et. al., 2013; Bik et al 2012; Kostka et al., 2011). Daylander (2014) 

provided additional information about weathering and the mobility of tarballs on and adjacent to the oiled 

beaches. In addition, studies show that the oil that was stranded on beaches and bioaccumulated by clams 

following the Deepwater Horizon explosion and oil spill is gradually being degraded (Snyder et al., 2014; 

Boufadel et al., 2014). The reduction of PAHs in clams found on Florida beaches affected by oil from the 

Deepwater Horizon explosion and oil spill indicate that a similar reduction would likely be found in 

clams on the most heavily oiled beaches of Louisiana.

None of the sources identify any reasonably foreseeable impacts that are significantly greater to 

coastal beaches and associated dunes with the implementation of an Action alternative as compared with 

the impacts of the No Action alternative. The WPA is an active oil and gas region with ongoing 

exploration, drilling, and production activities. In addition, non-OCS energy-related factors will continue 

to occur in the WPA irrespective of the WPA proposed action (i.e., development, urbanization, 

recreational activities, etc.). The potential for effects from changes to the affected environment (postDeepwater Horizon), routine activities, accidental events (as well as low-probability catastrophic spills), 

and cumulative impacts remains whether or not the No Action or an Action alternative is chosen under 

this Supplemental EIS. Impacts on coastal barrier beaches and associated dunes from either smaller 

accidental events or low-probability catastrophic events will remain nearly the same. Although the body 

of available information is incomplete, the evidence currently available supports past analyses and does 

not indicate severe adverse impacts to coastal barrier beaches and associated dunes as a result of the WPA 

proposed action. Therefore, BOEM has determined that the incomplete information is not essential to a 

reasoned choice among alternatives.

There are also data gaps regarding the future restoration efforts being planned, such as what projects 

will ultimately be constructed and how successful they may be. The extent of other impacts to beaches in 

the future from coastal development is likewise unknown. This information will not be available until 

such projects are constructed, which is not within the timeline contemplated in the NEPA analysis of this 

Supplemental EIS. However, BOEM used existing information regarding the effects of past projects, the 

plans for restoration projects currently being considered under the RESTORE Act, and past effects of 

coastal development on coastal beaches to anticipate the benefit of restoration projects in the WPA (Gulf 

Coast Ecosystem Restoration Council, 2014; Texas Commission on Environmental Quality, 2014b; State 

of Louisiana, Coastal Protection and Restoration Authority, 2014; State of Mississippi, Dept. of 

Environmental Quality, 2014; Alabama Gulf Coast Recovery Council, 2014; State of Florida, Dept. of 

Environmental Protection, 2014). BOEM has determined that the scope of the planned restoration 

projects would likely only partially restore what was present historically along the Gulf Coast, although 

any restoration of coastal barrier beaches and associated dunes would reduce the land loss rates. 

However, BOEM has determined that the incomplete information is not essential to a reasoned choice 

among alternatives because the scope of the planned restoration projects would likely only partially 

restore what was present historically along the Gulf Coast, and BOEM can extrapolate the effects of the 

WPA proposed action based on the effects of past lease sales on earlier baselines.

Summary and Conclusion

BOEM has reexamined the analysis for coastal barrier beaches and associated dunes presented in the 

prior 2012-2017 Gulf of Mexico EISs based on the additional information presented above. No new 

information was discovered that would alter the impact conclusion for beaches and dunes. The analysis 

and potential impacts detailed and updated in the prior 2012-2017 Gulf of Mexico EISs still apply for 

proposed WPA Lease Sale 248. 
4-22 Western Planning Area Lease Sale 248 Supplemental EIS

4.1.1.4. Wetlands

BOEM has reexamined the analysis for wetlands presented in the prior 2012-2017 Gulf of Mexico 

EISs based on the additional information presented below. No new information was discovered that 

would alter the impact conclusion for wetlands previously presented in the prior 2012-2017 Gulf of 

Mexico EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents 

still apply for proposed WPA Lease Sale 248.

A detailed description of wetlands, along with the full analyses of the potential impacts of routine 

activities, accidental events, and cumulative impacts associated with the WPA proposed action, are 

presented in Chapter 4.1.1.4 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.4 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below. 

The primary routine impact-producing activities associated with the WPA proposed action that could 

affect wetlands and marshes include pipeline emplacement, channel maintenance and construction, 

disposal of OCS oil- and gas-related wastes, increased vessel traffic, and the use and construction of 

support infrastructure in these coastal areas. Potential impacts from these factors include land and wake 

erosion from pipeline emplacement, channel dredging, and navigation traffic, and additional onshore 

development encouraged by increased capacities of navigation channels. The WPA proposed action is 

projected to contribute to the construction of 0-1 new onshore pipelines. If new pipelines are needed, 

impacts to wetlands are reduced by modern construction techniques and mitigating measures, which 

would result in zero to negligible impacts on wetland habitats. Modern construction techniques avoid 

wetlands through the use of directional drilling to eliminate additional trenching in wetlands. Regulations 

require the avoidance of wetlands through selective emplacement in existing corridors and the restoration 

and revegetation of the impacted areas. In addition, the potential impacts from the WPA proposed action 

would be reduced through the continued use of armored channels and modern erosion-control techniques. 

If channel dredging is required, the dredged material will require disposal. However, it may be 

beneficially used for marsh creation to mitigate for land loss. Creation of OCS wastes and drilling byproducts would require disposal, but they should be delivered to existing facilities. Because of existing 

facility capacity, no additional facility expansion into wetland areas is expected. Secondary impacts to 

wetlands caused by existing pipeline and vessel traffic corridors will continue to cause land loss because 

pipelines canals were constructed before modern techniques were implemented and many reaches of 

current vessel traffic corridors are not armored. However, because of permit requirements, modern 

construction techniques, and mitigation, routine OCS oil- and gas-related activities associated with the 

WPA proposed action are expected to cause negligible impacts to wetlands.

The main accidental impact-producing factor that would affect wetlands is oil spills, which could 

result in the physical oiling of wetlands. The most likely cause of a spill ≥1,000 bbl is a pipeline break at 

the seafloor; other possible sources include platform or vessel accidents. Wetland impacts from spills

originating on the OCS would be minimized due to the distance of wells and production facilities from 

the coastal wetlands and the protection provided by the barrier islands, peninsulas, sand spits, and 

currents. These factors, combined with the potential for only highly-weathered or treated oil reaching the 

shoreline, greatly minimize or eliminate the impacts of spills originating on the OCS. However, if an oil 

spill related to the WPA proposed action occurs in a river, bay, or estuary, some impact to wetland habitat 

could be expected. Although the probability of occurrence is low, the greatest threat of an oil spill to 

wetland habitat is from an oil spill in a river, bay, or estuary as a result of a vessel accident or pipeline 

rupture. Wetlands in the northern Gulf of Mexico are in moderate- to high-energy environments, and 

tidal movement should reduce the chances of oil persisting in these areas. Vegetation stress tends to be 

highest at the shoreline and decreasing with distance from the water. Revegetation can occur to some 

extent within a year, with the poorest recovery adjacent to shorelines, in the most heavily oiled areas 

(Khanna et al., 2013).

While a resulting oil slick may cause minor impacts to wetland habitat, the equipment and personnel 

used to clean up the spill can generate the greatest impacts to the area. Associated foot traffic can work 

oil farther into the sediment than would otherwise occur. Close monitoring and restrictions on cleanup 
Description of the Environment and Impact Analysis 4-23

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

Overall, impacts to wetland habitats from an oil spill associated with activities related to the WPA 

proposed action would be expected to be minimal and temporary because of the distance of most of the 

activity from shore, the weathering of spilled oil, and the ability of vegetation to recover from exposure to 

crude oil (Khanna et al., 2013). 

The cumulative analysis considers the effects of impact-producing factors related to the WPA 

proposed action, prior and future OCS lease sales in the Gulf of Mexico, and non-OCS oil- and gasrelated activities such as State oil and gas activities, other governmental and private projects and 

activities, and natural processes that may affect wetlands. Several OCS oil- and gas-related cumulative 

impact-producing factors could potentially impact wetland resources, including the following: oil spills

and cleanup activity; OCS oil- and gas-related vessel traffic; construction of OCS oil- and gas-related 

infrastructure and support structure (including pipelines); and waste disposal. 

The primary impact-producing factors attributable to the WPA proposed action are pipeline landfalls, 

canal widening, and maintenance dredging of navigation canals because they result in land loss. 

However, modern construction techniques and regulations reduce impacts to wetlands as a result of these 

activities. In addition, because the increase in pipelines, dredging, and vessel traffic from the WPA 

proposed action are predicted to be minimal, impacts related to these factors are also expected to be 

minimal. The possibility of physical oiling of wetlands from the WPA proposed action as a result of an 

oil spill originating in OCS waters is minimal compared with an oil spill that is closer to the wetlands and 

that could occur in State waters or in rivers, bays, or estuaries. The effects from a spill have the highest 

probability of occurring in Galveston and Matagorda Counties, Texas. These are the primary areas where 

oil produced in the WPA is transported and distributed, while oil produced in the CPA is handled in 

Lafourche, Cameron, Plaquemines, and St. Bernard Parishes, Louisiana. If any oil spills occur in rivers, 

bays, or estuaries from pipelines or vessels, they will likely be small and at service bases or other support 

facilities, and these small-scale local spills would not be expected to severely affect wetlands, in contrast 

to a larger scale spill. Accidental spills as a result of a low-probability catastrophic event, which are not 

part of the proposed action and are not likely expected to occur, may have impacts on wetlands. Lowprobability catastrophic events are discussed in Appendix A. 

Non-OCS oil- and gas-related cumulative impact-producing factors that could potentially impact 

wetland resources include the following: State oil and gas; non-OCS oil- and gas-related vessel traffic; 

coastal infrastructure and development; maintenance of navigation canals; natural processes (including 

hurricane and tropical storms); and sea-level rise. Non-OCS oil- and gas-related impacts from residential, 

commercial, agricultural, and silvicultural (forest expansion) developments are expected to continue in 

coastal regions around the Gulf of Mexico. Wetlands are vulnerable to oil spills that may occur in State 

waters or in rivers, bays, or estuaries due to their proximity, although the impacts would be primarily 

localized in nature. Many such spills are from non-OCS oil- and gas-related sources, such as State oil and 

gas activities, and which can include vessel collisions, pipeline breaks, and shore-based transfer, refining, 

and production facilities. Insignificant adverse impacts upon wetlands from maintenance dredging are 

expected because the large majority of the material would be placed in existing disposal areas or used 

beneficially for marsh restoration or creation. Hurricanes and tropical storms can cause extensive damage 

to wetlands, including conversion of large acreages of wetlands to open water. Marine vegetation 

deposited by storms can rest on wetland plants, resulting in mortality. One benefit of storms is that they 

can be capable of delivering sediment from offshore or interior bays into wetland areas, partially 

offsetting erosion. Sea-level rise can affect coastal wetlands by the drowning of plants. Relative sealevel rise, which includes local factors such as subsidence, can increase salinity and flooding, resulting in 

reduced productivity of wetland plants (Spalding and Hester, 2007). 

Development pressures in the coastal regions of Texas have been primarily the result of tourism and 

residential beachside development in the Galveston and Bolivar Peninsula areas. In Galveston, recreation 

and tourist developments have been particularly destructive. Development pressures in the coastal 

regions of Louisiana, Mississippi, Alabama, and Florida have caused the destruction of large areas of 

wetlands. In coastal Louisiana, the most destructive developments have been the inland oil and gas 

industry projects, which have resulted in the dredging of huge numbers of access channels. Agricultural, 

residential, and commercial developments have caused the most destruction of wetlands in Mississippi, 

Alabama, and Florida. In Florida, recreational and tourist developments have been particularly 

destructive. Groundwater extraction, vessel traffic, the drainage of wetland soils, and the construction of 

buildings, roads, and levees have also caused the loss of wetlands. The cumulative effects of human and 
4-24 Western Planning Area Lease Sale 248 Supplemental EIS

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 land loss; therefore, wetland loss is 

expected to continue.

The WPA proposed action represents a small portion of the OCS oil- and gas-related impacts that will 

occur over the 40-year analysis period. Impacts associated with the WPA proposed action are a minimal 

part of the overall OCS oil- and gas-related impacts. The incremental contribution of the WPA proposed 

action to the cumulative impacts to coastal wetlands is minimal compared with the impacts associated 

with non-OCS oil- and gas-related activities in the GOM.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search was conducted for information published on northern Gulf of Mexico wetland communities, 

and various sources were examined to determine any recent information regarding these communities. 

Sources investigated include BOEM, the USGS National Wetlands Research Center, the USGS Gulf of 

Mexico Integrated Science Data Information Management System, Gulf of Mexico Alliance, and USEPA. 

Other scientific publication databases (including Science Direct, Elsevier, the NOAA Central Library 

National Oceanographic Data Center, and JSTOR) were checked for new information using general 

Internet searches based on major themes. New information was found on the affected environment, 

including information on the impacts and recovery from the Deepwater Horizon explosion, oil spill, and 

response as well as information on the impacts of oil on marsh sediments, new technology for sorbent 

barriers for oil, canal backfilling for restoration, and storm surge reduction for wetlands. 

Studies have been published regarding indirect impacts of the Deepwater Horizon explosion, oil spill, 

and response. For example, Middleton et al. (2015) found that the pulse of river water from the Davis 

Pond freshwater diversion, conducted by the State of Louisiana in an attempt to reduce influx of spilled 

oil into the Barataria estuary, resulted in an increase in primary productivity of downstream cypress 

swamps. This study added to our knowledge of the impacts of spill responses to wetlands following the 

Deepwater Horizon explosion, oil spill, and response. 

Other studies used mesocosms to examine responses of wetland soil to oil and dispersants. Shi and 

Yu (2014) exposed marsh sediment to crude oil, with and without the dispersant Corexit EC 9500A. 

They found that the dispersant decreased denitrification but stimulated organic matter mineralization. 

This result suggests that the loss of organic matter from the marsh could threaten its stability, and the 

more reducing conditions observed would tend to preserve the oil in the ecosystem for a longer time by 

decreasing its degradation. Batubara et al. (2014) exposed wetland soil to phenanthrene, comparing 

degradation rates at intertidal and subtidal simulations. They found degradation occurred more rapidly in 

the intertidal setting, mirroring earlier field experiments (on beaches) by others (Elango et al., 2014; 

Lemelle, 2012). These studies can be used to better understand possible impacts to marshes following an 

oiling event. 

Curtis (2014) described the use of synthetic eelgrass as a floating, sorbent barrier for use in capturing 

and sequestering floating oil. This promising product is oleophilic and hydroscopic, and can be re-used 

once the oil is squeezed out of it. Its use in potential future oil spills could aid in protecting wetland

shorelines from oil contamination. 

Pate (2014) used the Geographic Information System (GIS) analysis to investigate feasibility, cost, 

and benefits of canal backfilling as a restoration technique, in concert with approved projects in 

Louisiana’s coastal marshes. He found that, using conservative estimates, over 26,000 ac (10,522 ha)

could be backfilled at a significant savings using this approach. 

Hu et al. (2015) modeled the effect of wetlands on reducing storm surge in the Breton Sound Basin of 

Louisiana. Stem height and to a lesser extent stem density increased the maximum surge reduction and 

maximum surge reduction rate. The maximum surge reduction decreased significantly with increased 

wind intensity, and the maximum surge reduction rate was the highest with a fast-moving weak storm. 

This study provides insight into how much storm protection may be provided by coastal wetlands to 

vulnerable communities.
Description of the Environment and Impact Analysis 4-25

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined the new information does not 

change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. As identified in the resource analyses in this Supplemental EIS 

and in Chapter 4.1.1.4 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete or 

unavailable information regarding wetlands in the WPA. The information below updates or adds to the 

understanding of incomplete or unavailable information for this resource. This incomplete or unavailable 

information may be relevant to this analysis because recent events such as the Deepwater Horizon

explosion, oil spill, and response may have caused changes to baseline conditions for coastal wetlands of 

the Gulf of Mexico. A large body of information regarding impacts of the Deepwater Horizon explosion, 

oil spill, and response upon coastal wetlands is being developed through the NRDA process, but this 

information is not yet available. Other unknowns are future benefits from restoration projects and future 

impacts of sea-level rise. BOEM used existing information and reasonably accepted scientific 

methodologies to extrapolate from available information in completing the relevant analysis, e.g., 

Middleton et al. (2015), Batubara et al. (2014), Michel and Rutherford (2014), Zengel et al. (2014), Judy 

et al. (2014), Khanna et al. (2013), Moody et al. (2013), and Staszak and Armitage (2013). 

These studies provide insight into the extent of impacts and potential recovery that could be expected 

from a low-probability catastrophic oil spill, which is not part of the WPA proposed action and not likely 

expected to occur. However, none of these sources reveals reasonably foreseeable significantly greater 

adverse impacts from an Action alternative or the No Action alternative because the WPA is an active oil 

and gas region with ongoing exploration, drilling, and production activities. In addition, non-OCS 

energy-related factors will continue to occur in the WPA irrespective of the WPA proposed action (e.g., 

commercial development, subsidence, and hurricanes). The potential for effects from changes to the 

affected environment (post-Deepwater Horizon), routine activities, accidental spills (including lowprobability catastrophic spills), and cumulative effects remains whether or not the No Action or an Action 

alternative is chosen under this Supplemental EIS. Impacts on wetlands from either smaller accidental 

events or low-probability catastrophic events will remain the same. Therefore, BOEM has determined 

that the information is not essential to a reasoned choice among alternatives.

There are also data gaps regarding the future restoration efforts being planned in coastal states, such 

as what projects will ultimately be constructed and how successful they may be. This information will 

not be available until such projects are constructed, which is not within the timeline contemplated in the 

NEPA analysis of this Supplemental EIS. However, BOEM used existing information regarding the 

effects of past projects, the plans for restoration projects currently being considered under the RESTORE 

Act, and past effects of coastal development on coastal wetlands to anticipate the benefit of restoration 

projects in the WPA (Pate, 2014; Gulf Coast Ecosystem Restoration Council, 2014; Texas Commission 

on Environmental Quality, 2014b; State of Louisiana, Coastal Protection and Restoration Authority, 

2014; State of Mississippi, Dept. of Environmental Quality, 2014; Alabama Gulf Coast Recovery 

Council, 2014; State of Florida, Dept. of Environmental Protection, 2014; Pate, 2014). BOEM has 

determined that the scope of the planned restoration projects would likely only partially restore what was 

present historically along the Gulf Coast, although any restoration of wetlands would reduce the land loss 

rates. However, BOEM has determined that the incomplete information is not essential to a reasoned 

choice among alternatives because BOEM can extrapolate the effects of the WPA proposed action based 

on the effects of past lease sales on earlier baselines and can reasonably use the extrapolation in current 

analyses.

The rate of future sea-level rise is unknown (Hausfather, 2013), but BOEM has used studies of the 

effects of sea-level rise on wetland plants, as well as a study that used a likely range of projections of sealevel rise (Glick et al., 2013) to assess the likely impacts of sea-level rise to the baseline environment. 

BOEM used this existing information to determine possible impacts of a natural non-OCS oil- and gasrelated activity on an altered coast and compare it with the possible impacts of a WPA proposed action. 

BOEM has determined that the incomplete information is not essential to a reasoned choice among 

alternatives because BOEM can extrapolate the effects of the WPA proposed action on expected reduced 

future acreages of wetlands based on the effects of past lease sales on earlier baselines.
4-26 Western Planning Area Lease Sale 248 Supplemental EIS

Summary and Conclusion

BOEM has reexamined the analysis for wetlands presented in the prior 2012-2017 Gulf of Mexico 

EISs based on the additional information presented above. No new information was discovered that 

would alter the impact conclusion for wetlands presented in the prior 2012-2017 Gulf of Mexico EISs. 

The analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248. 

4.1.1.5. Seagrass Communities

BOEM has reexamined the analysis for seagrass communities presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information presented below. No new information was 

discovered that would alter the impact conclusion for seagrass communities presented in the prior 2012-

2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in those 

NEPA documents still apply for proposed WPA Lease Sale 248. 

A detailed description of seagrass communities, as well as the full analyses of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.5 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.5 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. BOEM has found no significant new information that 

has become available since those NEPA documents were published. 

The potential routine impact-producing factors on seagrass communities of the WPA include the 

construction of pipelines, canals, navigation channels, and onshore facilities; maintenance dredging; and 

vessel traffic (e.g., propeller scars). These factors could result in submerged vegetation beds being 

uprooted, scarred, or lost; decreased oxygen in the water; turbidity; and the burial of plants from 

suspended sediment. However, routine OCS oil- and gas-related activities in the WPA that may affect 

seagrasses are not predicted to significantly increase in occurrence and range in the near future. A 

maximum of one potential new pipeline landfall is expected as a result of the WPA proposed action. 

Requirements of other Federal and State programs, such as avoidance of seagrass and submerged 

vegetation communities or the use of turbidity curtains, reduce undesirable effects on submerged 

vegetation beds from potentially harmful activities. Local programs decrease the occurrence of prop 

scarring in grass beds and, generally, channels used by OCS oil- and gas-related vessels are away from 

exposed submerged vegetation beds. Because of these requirements and implemented programs, along 

with the beneficial effects of natural flushing (e.g., from winds and currents), any potential effects from 

routine OCS oil- and gas-related activities on submerged vegetation in the WPA are expected to be short 

term, localized, and not significantly adverse.

Accidental disturbances resulting from the WPA proposed action, including oil spills, have the 

potential to change community structure, decrease growth rates, cause death, or cause a decline in 

ecological services by seagrass communities of the WPA if an accidental event was to occur in close 

proximity to these habitats. The greatest threat to inland, submerged vegetation communities would be 

from an inland spill resulting from a vessel accident or pipeline rupture. However, because pipelines can 

be shut off, ships carry limited amounts of oil, and response vessels can more easily access nearshore 

areas, it is expected that the resulting spill would be small and short in duration, resulting in short-term 

and localized impacts. There is also the remote possibility of a small offshore spill to reach submerged 

vegetation beds, and this would have similar effects as an inshore spill. The resulting impacts to seagrass 

from contacting oil could range from the sloughing of epiphytes to plant death. Further, an offshore spill 

could result in more sinking oil (e.g., tarballs and patties) than an inshore spill, and oil could become 

entrained within seagrass root and leaf complex near the seafloor. Because prevention and cleanup 

measures can have negative effects on submerged vegetation, close monitoring and restrictions on the use 

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

nature of nondispersed crude oil, the regional microtidal range, the dynamic climate with mild 

temperatures, and the amount of microorganisms that consume oil would alleviate prolonged effects on 

submerged vegetation communities. Also, safety and spill-prevention technologies are expected to 
Description of the Environment and Impact Analysis 4-27

continue to improve and will minimize effects to submerged vegetation from the WPA proposed action. 

Impacts to submerged vegetation from an accidental event related to the WPA proposed action are 

expected to be negligible.

The cumulative OCS oil- and gas-related activities that present the greatest threat of impacts to 

submerged vegetation communities are dredging, oil spills, and pipeline installation. In general, the WPA 

proposed action would cause a minor incremental contribution to impacts on submerged vegetation from 

related dredging, pipeline installations, and oil spills. Of those mentioned, dredging generates the greatest 

overall risk to submerged vegetation by uprooting and burying plants, decreasing oxygen in the water, 

and reducing water clarity in an area. A low-probability catastrophic spill, which is not part of the WPA 

proposed action and not likely expected to occur, could also impact seagrass communities. Refer to 

Appendix A for more details on the impacts of a low-probability catastrophic spill. Further, non-OCS 

oil- and gas-related dredging and vessel traffic, boat scarring, changes in salinity and nutrient inputs 

(Waycott et al., 2009; Orth et al., 2006), changes to natural flow regimes from constructed structures, and 

storm events could continue to cause direct damage to seagrass beds by physical destruction, increased 

turbidity and burial of plants, and reduction in favorable environmental conditions for seagrass bed 

growth. However, the incremental contribution of stress from the WPA proposed action to submerged 

vegetation is reduced by the implementation of proposed lease stipulations, mitigating measures currently 

in place, and the small probability of an oil spill.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of various printed and Internet sources was conducted for any recent information published 

regarding submerged vegetation. Sources investigated include BOEM, USDOC/NOAA, the USGS 

National Wetlands Research Center, the USGS Gulf of Mexico Integrated Science Data Information 

Management System, Seagrass Watch, Gulf of Mexico Alliance, State environmental agencies, USEPA, 

and coastal universities. Other websites from scientific publication databases (including Science Direct, 

Elsevier, CSA Illumina now ProQuest, and JSTOR) were checked for new information using general 

Internet searches based on major themes. No new information that would add to the analyses or change 

the conclusions was discovered since publication of the prior 2012-2017 Gulf of Mexico EISs. 

Incomplete or Unavailable Information 

After evaluating the information above, BOEM has determined that the previous conclusions from the 

prior 2012-2017 Gulf of Mexico EISs are still valid because no new information on seagrass communities

pertinent to the WPA proposed action has been published since the prior 2012-2017 Gulf of Mexico EISs. 

With regards to the Deepwater Horizon oil spill, BOEM extrapolated existing information using 

reasonably accepted scientific methodologies to come to the conclusion that oil did not reach the seagrass 

communities in the WPA. The NOAA has estimated that the westernmost extent of visible sheens related 

to oil from the Deepwater Horizon explosion and oil spill extended no farther than Cameron Parish, 

Louisiana, which is to the east of the WPA boundary (Figure 1-2 of the 2012-2017 WPA/CPA Multisale 

EIS), and that data collected by OSAT indicate that the Deepwater Horizon oil spill did not reach WPA 

waters or sediments (OSAT, 2010). In addition, BOEM has not identified any other data gaps in its 

evaluation of seagrasses and impacts to seagrasses as a result of the WPA proposed action. Therefore, 

BOEM has determined that there is no incomplete or unavailable information for seagrasses at this time.

Summary and Conclusion

BOEM has reexamined the analysis for seagrass communities presented in the prior 2012-2017 Gulf 

of Mexico EISs with the understanding that no new information on seagrass communities has been 

published since the publication of those NEPA documents. Therefore, no new information was 

discovered that would alter the previously presented impact conclusion for seagrass communities 

presented in prior 2012-2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and 

updated in those NEPA documents still apply for proposed WPA Lease Sale 248. 
4-28 Western Planning Area Lease Sale 248 Supplemental EIS

4.1.1.6. Topographic Features

BOEM has reexamined the analysis for topographic features (high relief features that provide habitat 

for corals and other hard bottom communities) presented in the prior 2012-2017 Gulf of Mexico EISs 

based on the additional information presented below. No new information was discovered that would 

alter the impact conclusion for topographic features presented in the prior 2012-2017 Gulf of Mexico 

EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents still 

apply for proposed WPA Lease Sale 248. 

A detailed description of topographic features, along with the full analysis of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.6 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.6 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below.

Because of the recognized importance of the topographic features, BOEM proposes attaching the 

Topographic Features Stipulation (as described in NTL 2009-G39) to OCS oil and gas leases within the 

Topographic Feature Stipulation blocks. When applied, this stipulation would prevent most of the 

potential impacts on the protected areas of the topographic features from bottom-disturbing activities 

(structure removal and emplacement) and operational discharges associated with the WPA proposed 

action through avoidance. In addition, it would distance all or parts of the protected topographic features 

from possible accidental events. The stipulation would require that bottom-disturbing activities be 

located at least 152 m (500 ft) from a topographic feature’s No Activity Zone and that drill cuttings and 

fluids from wells within designated shunting zones must be shunted to the seafloor, although shunting 

requirements can vary among features.

The potential routine impact-producing factors on topographic features of the WPA could include 

bottom-disturbing activities such as anchoring, infrastructure emplacement or removal, and drillingeffluent and produced-water discharges. These factors could result in crushing and/or smothering of 

sensitive organisms and exposure to concentrated discharges. If the Topographic Features Stipulation is 

applied, it will minimize the potential impacts to the topographic features by distancing bottom-disturbing 

activities from the sensitive habitat. The distancing eliminates the possibility of anchors, pipelines, and 

structures being placed on top of the features, and structure-removal activity will be distanced enough to 

minimize impacts to topographic features. If any contaminants reach topographic features, they would be 

diluted from their original concentration, and impacts that may occur should be minimal. In addition to 

the mitigations, discharges or activities that could harm topographic features are regulated by other 

agencies, including discharge permit restrictions from USEPA and essential fish habitat restrictions from 

NOAA. Furthermore, the high-energy environment and prevailing water currents associated with 

topographic features would help protect the features by enabling rapid turnover of the water column. 

Adverse effects from accidental disturbances resulting from the WPA proposed action could include 

surface and subsurface oil spills and turbidity and sedimentation from loss of well control without release 

of substantial quantities of oil. Each has the potential to disrupt and alter the environmental, commercial, 

recreational, and aesthetic values of topographic features of the WPA through oiling and sedimentation. 

The proposed Topographic Features Stipulation would assist in preventing most of the possible accidental 

impacts on the protected areas of the topographic feature communities by increasing the distance of such 

events from the topographic features. It is expected that the majority of oil released during an accidental 

event would rise rapidly to the surface and that the sediments in the water column would likely be 

deposited on the seafloor before reaching the topographic features. In the event that diluted oil from a 

spill did reach the biota of a topographic feature, the effects would be primarily sublethal and impacts 

would be at the community level. Any turbidity, sedimentation, and oil adsorbed to sediment particles 

would also be at low concentrations by the time the topographic features were reached, likely resulting in 

sublethal impacts. Overall, impacts from a surface oil spill on topographic features would be lessened by 

the distance of the spill to the features, the depth of the features, and the prevailing water currents that 

sweep around the features.
Description of the Environment and Impact Analysis 4-29

The cumulative impact from routine OCS oil- and gas-related operations includes effects resulting 

from the WPA proposed action and those resulting from past and future OCS leasing. These operations 

include anchoring, structure emplacement, muds and cuttings discharge, effluent discharge, turbidity and 

sedimentation from loss of well control without substantial releases of oil, oil spills, and structure 

removals. Without mitigation, these factors could result in the crushing and/or smothering of organisms 

on topographic features or exposure to concentrated discharges of oil. Low-probability catastrophic spills 

could also potentially cause damage to benthic biota (refer to Appendix A for more details).

Potential non-OCS oil- and gas-related factors include vessel anchoring, SCUBA diving, treasurehunting activities, import tankering, heavy storms and hurricanes, the collapse of the tops of the 

topographic features due to dissolution of the underlying salt structure, and fishing activities. Many of 

these non-OCS oil- and gas-related factors may result in the death of the biota, as well as physical damage 

to topographic features. 

The OCS and non-OCS oil- and gas-related activities causing mechanical disturbance represent the 

greatest threat to the topographic features. Impacts from OCS oil- and gas-related activities to the 

protected areas would be mitigated by the continued application of the proposed Topographic Features 

Stipulation. Adherence to this stipulation would preclude mechanical damage caused by oil and gas 

leaseholders from impacting the benthic communities of the topographic features and would protect them 

from operational discharges by establishing a buffer around the features. As such, little impact would be 

incurred by the biota of the topographic features as a result of OCS oil- and gas-related activities. The 

USEPA discharge regulations and permits would further reduce discharge-related impacts. With the 

application of stipulations and regulations, the incremental contribution of the WPA proposed action to 

the cumulative impact is negligible when compared with non-OCS oil- and gas-related impacts.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of Internet information sources (e.g., the NOAA Gulf Spill Restoration Publications 

website; the Environmental Response Management Application [ERMA] Gulf Response website; 

NOAA’s Deepwater Horizon Archive Publications and Factsheets; the Gulf of Mexico Sea Grant 

Deepwater Horizon Oil Spill Research and Monitoring Activities Database; RestoreTheGulf.gov website; 

and the Deepwater Horizon Oil Spill Portal) and public search engines to search published journal 

articles, Federal documents, and research reports was conducted to determine the availability of recent 

information on topographic features. The search revealed new information on the affected environment 

that is pertinent to this Supplemental EIS.

The most relevant new information for this Supplemental EIS was the publication of data related to 

the die-off, and lack of subsequent recovery (as of 2013), of seaweeds and rhodoliths on several 

topographic features (Sackett and Ewing Banks) that occurred coincidentally with the Deepwater Horizon 

explosion, oil spill, and response (Felder et al., 2014; Fredericq et al., 2014). Although these banks are 

not in the WPA, they are identical to the many banks found in the CPA that could be impacted by OCS 

oil- and gas-related activities. This research documents a significant reduction in diversity and abundance 

of benthic species at Ewing Bank and a significant reduction in abundance of benthic species at Sackett 

Bank. Although there was little in situ recovery, they found that the rhodoliths are potentially functioning 

as a “seed bank” for these habitats. When placed in the laboratory, the benthic algal community grew to 

pre-spill abundance and diversity. This suggests that there is an unknown environmental variable in-place 

that may be preventing in situ conditions required for germination and subsequent recovery. The authors 

are forthcoming about their work being speculative to this point, as no direct evidence is presented that 

implicates the Deepwater Horizon oil spill or subsequent response activities as the trigger for these 

changes. Felder et al. (2014) and Fredericq et al. (2014) spend a considerable amount of effort making a 

circumstantial case that their observations are directly related to the Deepwater Horizon oil spill. 

However, Sackett and Ewing Banks are 115 and 270 km (74 and 168 mi), respectively, to the west of the 

Deepwater Horizon well site and only experienced intermittent spill-related exposure (Sackett Bank) or 

sporadic exposure (Ewing). Felder et al. (2014) and Fredericq et al. (2014) make little effort to explain 

how other ecosystem-level events that occurred during this same time period may have contributed to 

these patterns. For example, these banks are located in areas highly influenced by the outfall of the 

Mississippi River. Between 2009 and 2012, the Mississippi River outfall was highly irregular compared 
4-30 Western Planning Area Lease Sale 248 Supplemental EIS

with normal outfall patterns (Pollak, 2013). From late 2009 to late 2010, the Mississippi River 

maintained an exceptionally high flow rate with an abnormal seasonal pattern. Additionally, in 2011, a 

near-record outfall event occurred, followed by record low outfall levels in 2012. In addition to the 

anomalous flow, these areas were subjected to differing levels of hypoxia, with major hypoxia events 

occurring in the vicinity of Ewing Bank in the summers of 2009, 2010, and 2011 (LUMCON, 2010 and 

USDOC, NOAA, NCDDC, 2015). Although there were many hypoxic events prior to 2009, these 

occurred during periods of river outfall patterns exhibiting a more “normal” seasonal pattern. Finally, and 

coincidentally, the banks of the northern Gulf of Mexico also experienced exponential population growth 

of the invasive lionfish (Pterois volitans) during this same time period (USDOI, GS, 2015; Johnston, 

2013). This fish is known to drive down diversity and abundance of benthic organisms, especially crabs, 

demersal fishes, and shrimps (Green et al., 2012). This population expansion could be directly 

responsible for the rapid decline in decapods and the increase in decapod injuries observed by Felder et al.

(2014) and Fredericq et al. (2014). This decline would be exacerbated by the loss of seaweed, regardless 

of the cause. Overall, it is a more reasonable conclusion that the possible ecosystem-level changes are the 

result of the cumulative impacts of many factors (Karnauskas et al., 2015) rather than a single causeeffect relationship (i.e., Deepwater Horizon explosion, oil spill, and response), especially with respect to 

recovery. This analysis does not suggest that oil or dispersants did not have a role in the change, just that 

it has yet to be documented and that the theories put forth by Felder et al. (2014) and Fredericq 

et al.(2014) are speculative (by the authors’ own admissions) and lacking in rigorous quantitative data. 

The authors did provide evidence that, given the correct environmental conditions, recovery of the benthic 

community is plausible to pre-2010 levels. 

Additionally, the FWS has identified 20 species of corals as threatened. Three of these corals are 

present in the WPA and all are in the Genus Orbicella (Federal Register, 2014b). In the WPA, these 

species are considered threatened because they are habitat limited and naturally rare. The monitored 

populations that are present in the WPA have shown little change in abundance since the 1980’s 

(Johnston et al., 2015). 

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change the conclusions found in the prior 2012-2017 Gulf of Mexico EISs. However, working in 

deep marine systems is complex and requires substantial resources; as such, research on these features has 

been limited. Thus, there is a substantial amount of information that remains unknown about these 

features. All analyses discussed in this Supplemental EIS, as well as in Chapter 4.1.1.6 of the prior 2012-

2017 Gulf of Mexico EISs, are based on incomplete information. Because topographic features are not 

unique to the WPA, information collected throughout the GOM has been used in this analysis. For 

example, our understanding of the possible impacts of surface oil spills to topographic features in the 

GOM was determined by combining research on the depth and concentration of the physical mixing of 

surface oil with the known depths of WPA topographic features. These results suggest that, although oil 

measurements were not collected at every feature under every condition, topographic features exist at 

depths deeper than lethal concentrations of oil would be expected (Lange, 1985; McAuliffe et al., 1975 

and 1981; Tkalich and Chan, 2002; Rezak et al., 1983; Wyers et al., 1986). Additionally, continuous 

monitoring of the Flower Garden Banks since the 1970’s for impacts related to OCS oil- and gas-related 

development suggests that BOEM’s Topographic Features Stipulation may achieve the stated objective of 

minimizing damage to topographic features from OCS oil- and gas-related activities (refer to Johnston et 

al., 2013, and references therein). At the Flower Garden Banks, corals have flourished while OCS oiland gas-related development has occurred and, in some cases, activities have taken place just outside the 

No Activity Zone. Since corals are generally considered to be more fragile than most other organisms 

found in the WPA, it is reasonable to conclude that topographic features in the WPA with more resilient 

organisms than the Flower Garden Banks have not been negatively impacted by OCS oil- and gas-related 

development in the GOM. 

With respect to unavailable information in relation to the Deepwater Horizon explosion, oil, spill, and 

response, the majority of this information cannot be obtained because it has not been released. Relevant 

data on the status of topographic features may take years to acquire and analyze. This unavailable 

information may be relevant to adverse effects because the Deepwater Horizon explosion, oil spill, and 

response may have caused changes to baseline conditions for topographic features in the Gulf of Mexico. 
Description of the Environment and Impact Analysis 4-31

While outstanding reports are not expected to reveal reasonably foreseeable significant effects, BOEM 

nonetheless determined that additional information could not be timely acquired and incorporated into the 

current analysis. BOEM has used existing information and reasonably accepted scientific methodologies 

to extrapolate from available information in completing this analysis and formulating the conclusions 

presented here. For example, if sampling techniques show that oil concentration were greater at 

topographic features in the CPA than previously reported (Sammarco, 2013), then it is possible that more 

oil reached the topographic features in the WPA than previously reported. However, until this 

information is made available, it is impossible to make this determination. Although the body of 

available information is incomplete, the currently available evidence supports past analyses and does not 

indicate severe adverse impacts directly linked to Deepwater Horizon explosion, oil, spill, and response

for topographic features. Therefore, BOEM has determined that the incomplete or unavailable 

information is not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for topographic features presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information provided above. The new information presented here 

would not alter the previous impact conclusion for topographic features presented in the prior 2012-2017 

Gulf of Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA documents 

still apply for proposed WPA Lease Sale 248.

4.1.1.7. Sargassum Communities

BOEM has reexamined the analysis for Sargassum communities presented in the prior 2012-2017 

Gulf of Mexico EISs based on the additional information presented below. No new information was 

discovered that would alter the impact conclusion for Sargassum communities presented in the prior 

2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in 

those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of Sargassum communities, along with the full analyses of the potential 

impacts of routine activities, accidental events, and cumulative impacts associated with the WPA 

proposed action, are presented in Chapter 4.1.1.7 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.7 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. BOEM has found no significant 

new information that has become available since those NEPA documents were published. 

Impact-producing factors associated with routine events for the WPA proposed action that could 

affect Sargassum may include the following: drilling discharges (muds and cuttings); produced water and 

well treatment chemicals; operational discharges (deck drainage, sanitary and domestic water, bilge and 

ballast water); and physical disturbance from vessel traffic and the presence of exploration and production 

structures (i.e., rigs, platforms, and MODUs). Because Sargassum, a pelagic algae, is widely distributed 

in the upper water column near the sea surface, it may be contacted by routine discharges from oil and gas 

operations, including drilling discharges, produced water, and operational discharges (e.g., deck runoff, 

bilge water, sanitary effluent, etc., from service vessels, working platforms, and drillships). However, the 

quantity and volume of these discharges are relatively small compared with the volume of water in the 

WPA (115,645 km2

; 44,651 mi2), and the discharges are highly regulated as well as diluted with distance 

from the source, therefore reducing possible toxicity. Transiting vessels may pass through Sargassum

mats, producing slight impacts to the Sargassum community from propellers and possible impingement 

on cooling water intakes. However, because patches break up and reform naturally and regularly, impacts 

from vessels are expected to be minor. None of these impacts associated with the WPA proposed action 

is expected to have more than minor localized effects to Sargassum mats and limited effects to the 

Sargassum community as a whole. Sargassum would be resilient to the minor effects predicted because it

has a yearly cycle that promotes quick recovery from impacts. No measurable impacts are expected to the 

overall population of the Sargassum community. 
4-32 Western Planning Area Lease Sale 248 Supplemental EIS

Impact-producing factors associated with accidental events that may be associated with the WPA 

proposed action that could affect Sargassum and its associated communities include surface oil and fuel 

spills, turbidity and sedimentation from loss of well control without a release of substantial quantities of 

oil spills, spill-response, spill-response activities, and chemical spills. These impact-producing factors 

would have varied effects depending on the intensity of the spill and the presence of Sargassum in the 

area of the spill. All types of spills, including oil and fuel spills, underwater oil spills, and chemical 

spills, could potentially contact Sargassum algae. The quantity and volume of most of these spills would 

be relatively small compared with the pelagic waters of the WPA (115,645 km2

; 44,651 mi2). Therefore, 

most spills would only contact a very small portion of the Sargassum population. Accidental spills would 

likely be diluted by the Gulf water and, therefore, concentrations of toxic components that could 

potentially contaminate or kill Sargassum tissues would also be reduced in this scenario. The impacts to 

Sargassum that are associated with the WPA proposed action are expected to have only minor effects to a 

small portion of the Sargassum community. In the case of a very large spill, the Sargassum algae 

community could result in the death of a large number of plants across a geographically large area in the 

northern Gulf. The Sargassum community lives in pelagic waters with generally high water quality and is 

expected to show good resilience to the predicted effects of spills. It has a yearly cycle that promotes 

quick recovery from impacts. No measurable impacts are expected to the overall population of the 

Sargassum community as a result of accidental events associated with a WPA proposed action.

The cumulative impact from routine oil and gas operations includes effects resulting from the WPA 

proposed action, as well as those resulting from past and future OCS leasing. The OCS oil- and gasrelated impact-producing factors that can affect Sargassum include impingement by structures and marine 

vessels, oil and gas drilling discharges, operational discharges, and accidental spills. Of the possible 

factors, impingement, routine discharges, and accidental spills are the primary pathway that populations 

could be affected from OCS oil- and gas-related activities. However, because Sargassum communities 

are scattered, patchy, and mobile with a widespread distribution, many activities associated with the WPA 

proposed action should only result in localized and short-term effects. A low-probability catastrophic 

spill, which is not part of the WPA proposed action and not likely expected to occur, may also cause 

mortality to Sargassum communities (refer to Appendix A for more details).

Potential non-OCS oil- and gas-related factors include impingement or destruction from shipping 

traffic , hurricanes, and coastal water quality. Shipping traffic would be the largest non-OCS oil- and gasrelated activity to impact Sargassum. However, given the ephemeral nature of Sargassum at any given 

location, it is expected that habitat changes from ships are limited because patches break up and reform 

naturally and regularly. Destruction by ships is also not expected to result in death as Sargassum plants 

do not rely on root systems and can exist as fragments. The incremental contribution of the WPA 

proposed action to the overall cumulative impacts on Sargassum communities that would result from the 

OCS Program, environmental factors, and non-OCS oil- and gas-related activities is expected to be 

minimal.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of Internet information sources (e.g., the NOAA Gulf Spill Restoration Publications website, 

the Environmental Response Management Application [ERMA] Gulf Response website, NOAA’s 

Deepwater Horizon Archive Publications and Factsheets, the Gulf of Mexico Sea Grant Deepwater 

Horizon Oil Spill Research and Monitoring Activities Database, RestoreTheGulf.gov website, and the 

Deepwater Horizon Oil Spill Portal) and public search engines to search published journal articles, 

Federal documents, and research reports was conducted to determine the availability of recent information 

on Sargassum. The search revealed no new information on Sargassum. 

Incomplete or Unavailable Information 

After evaluating the information above, BOEM has determined that the previous conclusions from the 

prior 2012-2017 Gulf of Mexico EISs are still valid because no new information on Sargassum

communities pertinent to the WPA proposed action have been published since publication of the abovereferenced NEPA documents. As discussed in this Supplemental EIS and in Chapter 4.1.1.7 of the prior 
Description of the Environment and Impact Analysis 4-33

2012-2017 Gulf of Mexico EISs, BOEM has identified unavailable information regarding Sargassum in 

the WPA. This incomplete or unavailable information includes information on the effects of in situ oil 

exposure and the movement patterns of Sargassum. BOEM used existing information and reasonably 

accepted scientific methodologies to extrapolate in completing this analysis. BOEM determined there are 

few foreseeable significant adverse impacts to the Sargassum population associated with routine or 

accidental OCS events using publications such as Gower and King (2011), Gower et al. (2013), and 

Powers et al. (2013). Gower and King (2011) and Gower et al. (2013) suggest that Sargassum is 

continually present in the west-central GOM and that it moves in a general west to east pattern during the 

growing season; however, movements at a finer temporal or spatial scale are more difficult to predict. 

Liu et al. (2014) noted that the toxicity or the presence of oil across the surface waters of the GOM was 

also variable at any given time, suggesting that it is difficult to predict the effects of coming in contact 

with surface oil. Additionally, Lindo-Atichati (2012) suggested that patterns of larval fish in the surface 

currents in the northern GOM were not consistent spatially or temporally and that they were highly 

dependent on mesoscale current structures like the Loop Current and associated eddies. Combined, these 

studies suggest that, as Sargassum is passively moved in the surface waters, its presence at any given 

location or at given any time is difficult to predict, especially as the population grows exponentially 

during the growing season. Powers et al. (2013) also suggest that there were adverse effects to 

Sargassum under the proper conditions, but the spatial or temporal extent of those effects remains 

unknown. It is expected that, for routine or accidental events, the probability of enough Sargassum 

coming in contact with oil and dying as a result of this contact are low, given that oil and Sargassum are 

each controlled by surface currents in differential manners. Ultimately, the cosmopolitan nature across 

the northern GOM and the reproductive capabilities of Sargassum provide a life history that is resilient 

towards localized or short-term deleterious effects, like those expected associated with routine OCS 

events and noncatastrophic spills. Therefore, BOEM has determined that the incomplete information on 

Sargassum is not essential to a reasoned choice among alternatives and the information used in lieu of the 

missing information is acceptable for this analysis.

BOEM recognizes that the incomplete information with respect to possible impacts to Sargassum in 

the WPA as a result of the Deepwater Horizon explosion, oil spill, and response may be relevant to the 

evaluation of impacts. Because of this, BOEM’s subject-matter experts have used available scientifically 

credible evidence in this analysis and applied it using accepted scientific methods and approaches to 

extrapolate in completing this analysis. Sargassum communities within the WPA were likely not 

significantly affected by the Deepwater Horizon explosion, oil spill, and response, based on the best 

available information and the WPA’s distance from the Macondo well. Additional information related to 

the possible adverse impacts to Sargassum in the WPA as a result of the Deepwater Horizon explosion, 

oil spill, and response cannot be obtained during the timeline contemplated in the NEPA analysis of this 

Supplemental EIS because data related to research and monitoring related to the Deepwater Horizon oil 

spill have yet to be completed and made publicly available. During the Deepwater Horizon oil spill and 

response, Powers et al. (2013) documented a four-fold increase in Sargassum in the north-central GOM in 

the years following the spill; however, it is unknown if this was due to natural or anthropogenic causes. It 

is expected that, although this study was completed outside of the WPA, Sargassum in the WPA would 

respond similarly. Therefore, since there are no indicators that would suggest significant adverse effects 

on the Sargassum communities regardless of the alternative selected, BOEM has determined that the 

incomplete information is not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for Sargassum communities presented in the prior 2012-2017 

Gulf of Mexico EISs based on the additional information presented above. BOEM has found no 

significant new information that would alter the previous impact conclusion for Sargassum communities 

presented in the prior 2012-2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and 

updated in those NEPA documents still apply for proposed WPA Lease Sale 248.

4.1.1.8. Chemosynthetic Deepwater Benthic Communities

BOEM has reexamined the analysis for chemosynthetic deepwater benthic communities (e.g., 

tubeworms, mussels, and clams that depend on seep-associated chemoautotrophic bacteria) presented in 
4-34 Western Planning Area Lease Sale 248 Supplemental EIS

the prior 2012-2017 Gulf of Mexico EISs based on the additional information presented below. No new 

information was discovered that would alter the impact conclusion for chemosynthetic communities

presented in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts 

detailed and updated in those NEPA documents still apply for proposed WPA Lease Sale 248. 

A detailed description of chemosynthetic communities, along with the full analyses of the potential 

impacts of routine activities, accidental events, and cumulative impacts associated with the WPA 

proposed action, are presented in Chapter 4.1.1.8 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.8 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has 

become available since those NEPA documents were published is presented below. 

Considerable mechanical damage could be inflicted upon sensitive chemosynthetic deepwater benthic 

communities by routine activities associated with the WPA proposed action if mitigations are not applied 

to permits. Mitigations are based on protective measures described by NTL 2009-G40, “Deepwater

Benthic Communities,” and include distancing requirements for wells (610 m; 2,000 ft) as well as

anchors, chains, and pipelines (76 m; 250 ft) from sensitive habitats. This distancing also helps prevent 

sedimentation on deepwater benthic communities as a result of an accidental, but rare, seafloor loss of 

well control without a release of substantial quantities of oil. BOEM reviews exploration and production 

plans and pipeline applications and applies mitigations to permits to prevent impacts to sensitive seafloor 

habitats from routine OCS oil- and gas-related activities. Impacts from bottom-disturbing activities are 

expected to be rare because of the application of mitigations.

The potential routine impact-producing factors on chemosynthetic deepwater benthic communities of 

the WPA are bottom-disturbing activities associated with anchoring, structure emplacement, pipelaying, 

and structure removal, as well as discharges of drill cuttings, muds, and produced water. Discharges of 

produced waters on the sea surface are regulated, and chemical spills and deck runoff would be diluted in 

surface waters, having little to no effect on seafloor habitats. If a high-density community is subjected to 

direct impacts by bottom-disturbing activities, potentially severe or catastrophic impacts could occur due 

to raking of the sea bottom by anchors and anchor chains, and partial or complete burial by muds and 

cuttings. The severity of such an impact is such that there would be incremental losses of productivity, 

reproduction, community relationships, and overall ecological functions of the local community, and 

there would be incremental damage to ecological relationships with the surrounding benthos. However, 

impacts from bottom-disturbing activities directly on chemosynthetic communities are expected to be 

extremely rare because of the application of the required protective measures described by NTL 2009-

G40, “Deepwater Benthic Communities,” which distances bottom-disturbing activities from sensitive 

deepwater benthic communities. Because of the avoidance policies described in NTL 2009-G40, the risk 

of these physical impacts is greatly reduced by requiring the avoidance of potential chemosynthetic 

communities. 

Accidental events that could affect chemosynthetic communities are primarily limited to turbidity and 

sedimentation from loss of well control without a release of substantial quantities of oil, which are rare 

occurrences, and subsea oil spills. A loss of well control at the seafloor could create a crater and could 

resuspend and disperse large quantities of bottom sediments. This could bury organisms located within 

that distance to some degree, possibly eliminating some communities and preventing recolonization, 

depending on bottom-current conditions. The application of avoidance criteria for chemosynthetic 

communities described in NTL 2009-G40 precludes the placement of a well within 610 m (2,000 ft) of 

any suspected chemosynthetic community location. Chemosynthetic communities are therefore distanced 

from heavy sedimentation resulting from a possible loss of well control, with only light sediment 

components able to reach the communities in small quantities. Accidental impacts associated with the 

WPA proposed action would likely result in only minimal impacts to chemosynthetic communities due to 

the dilution of oil with distance from the spill source. One exception would be in the case of a subsea oil 

spill combined with the application of dispersant or high-pressure ejection of oil. If dispersants are 

applied to an oil spill at depth or if oil is ejected under high pressure, oil could mix into the water column, 

could be carried by underwater currents, and could eventually contact the seafloor in some form, either 

concentrated (near the source), associated with particulate material (marine snow), or decayed (farther 

from the source), where it may impact patches of chemosynthetic community habitat in its path. Oil near 
Description of the Environment and Impact Analysis 4-35

the surface can also become associated with plankton and other particulate material and eventually sink to 

the bottom at greater distances. The possible impacts, however, will be localized due to the directional 

movement of oil plumes by the water currents and because the sensitive habitats have a scattered, patchy 

distribution. Oil plumes that remain in the water column for longer periods would disperse and decay, 

having only minimal effect. The farther the dispersed oil travels, the more diluted the oil will become as 

it mixes with surrounding water. Therefore, accidental impacts associated with the WPA proposed action 

would likely result in only minimal impacts to chemosynthetic communities with adherence to the 

proposed biological stipulation and the guidelines described in NTL 2009-G40. 

Cumulative factors considered to impact the deepwater benthic communities (>300 m; 984 ft) of the 

Gulf of Mexico include both OCS oil- and gas-related and non-OCS oil- and gas-related activities. 

Cumulative OCS oil- and gas-related impacts to deepwater communities in the Gulf of Mexico are 

considered negligible because of the application of BOEM’s avoidance criteria as described in NTL 

2009-G40. 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 oil- and gas-related activities associated with 

pipelaying, anchoring, structure emplacement, and seafloor loss of well control without a release of 

substantial quantities of oil. Drilling discharges and resuspended sediments have the potential to cause 

minor, mostly sublethal impacts to chemosynthetic communities, but substantial sediment accumulations 

could result in more serious impacts. Possible low-probability catastrophic oil spills (Appendix A) due 

to seafloor loss of well control have the potential to devastate localized deepwater benthic habitats. 

However, these events are rare, are not part of the WPA proposed action and not likely expected to occur, 

and would only affect a small portion of the sensitive benthic habitat in the Gulf of Mexico. 

The non-OCS oil- and gas-related impact-producing factors include activities such as commercial 

fishing, trawling, storm impacts, massive sediment movement, and climate change. Fishing and trawling 

could potentially crush, topple, and remove chemosynthetic communities in the path of the gear. Because 

of the water depths where chemosynthetic communities live (>300 m; 984 ft) and because of the low 

density of potentially commercially valuable fishery species, these activities are not expected to 

substantially impact deepwater benthic communities. However, if trawling were to occur over a 

chemosynthetic community, the community could be devastated. Regional 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. This is because changes to water 

temperature and pH from the CO2 would not reach extremes at the water depths where chemosynthetic 

communities occur. Massive sediment flows can be caused by hurricanes and other forces, and could 

potentially bury chemosynthetic communities. Such flows are not common enough that impacts to 

chemosynthetic communities Gulfwide are expected to be widespread. Therefore, impacts from non-OCS 

oil- and gas-related activities to chemosynthetic communities are expected to be negligible. The 

incremental contribution of the 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 the guidelines described in NTL 2009-G40. 

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A broad search for relevant new information and scientific journal articles made available since 

publication of the prior 2012-2017 Gulf of Mexico EISs was conducted using a publicly available search 

engine. The websites for Federal and State agencies, as well as other organizations, were reviewed for 

newly released information. Sources investigated include the NOAA Ocean Exploration website, the 

Gulf of Mexico Alliance, USEPA, and USGS. 

Valentine et al. (2014) found evidence of an area of approximately 3,200 km2 (1,236 mi2

) around the 

Macondo well contaminated by ~1,800 kg (±1,000 kg) of excess hopane (a tracer for crude oil), reflecting 

deposition of oil from the Deepwater Horizon explosion and oil spill. Maps of the contaminated area in 

Valentine et al. (2014) were compared with BOEM’s seismic water-bottom anomaly database, and it 

appears that some chemosynthetic communities may be within the contamination footprint, although 

damage to chemosynthetic communities in the vicinity of the Macondo well has not been reported to date 
4-36 Western Planning Area Lease Sale 248 Supplemental EIS

(Shedd, official communication, 2015). This study provides evidence that there could have been spill 

impacts to chemosynthetic communities that have yet to be documented, but it does not change the 

conclusions of prior 2012-2017 Gulf of Mexico EISs. 

Incomplete or Unavailable Information 

After evaluating the information above, BOEM has determined that the previous conclusions from the 

prior 2012-2017 Gulf of Mexico EISs are still valid because new information on chemosynthetic 

deepwater benthic communities that has been published since the publication of the prior 2012-2017 Gulf 

of Mexico EISs does not indicate that there would be more than minor impacts from the WPA proposed 

action; nevertheless, there is still incomplete or unavailable information. As discussed in this 

Supplemental EIS, as well as in Chapter 4.1.1.8 of the prior 2012-2017 Gulf of Mexico EISs, there 

remains incomplete or unavailable information on the location of chemosynthetic communities in the 

GOM, as well as the effects of the Deepwater Horizon explosion, oil spill, and response on 

chemosynthetic communities that could potentially be relevant to this analysis. The below information 

updates or adds to the understanding of incomplete or unavailable information for this resource. 

BOEM has identified incomplete or unavailable information regarding the abundance and distribution 

of chemosynthetic communities in the GOM. To fill that data gap, BOEM’s subject-matter experts 

extrapolated existing data using accepted scientific methodologies. BOEM’s subject-matter experts use a 

database of 3D seismic data to interpret the relationship between reflectivity of the seafloor (an indicator 

of hard substrate for attachment) and the occurrence of potential habitat for chemosynthetic communities. 

Similarly, sidescan-sonar data are also used to determine the presence of likely habitat. These surveys are 

used when deepwater exploration and development plans are reviewed to ensure that chemosynthetic 

communities are not impacted by OCS oil- and gas-related activities as described in NTL 2009-G40. 

This information is sufficient in assisting BOEM in identifying areas that should be avoided for OCS oiland gas-related activities because it is likely habitat for chemosynthetic communities. BOEM has been 

able to accurately predict (via reflectivity or sidescan-sonar data) areas likely to have habitat for 

chemosynthetic communities, and in many cases the presence of such communities has been confirmed 

by video or photographs. This indicates that BOEM is currently able to effectively protect these 

communities from OCS oil- and gas-related activities. Therefore, BOEM has determined that the 

information is not essential to a reasoned choice among alternatives because BOEM reviews plans on a 

case-by-case basis to reduce the possibility of impacting chemosynthetic communities and because 

existing information has shown that current survey interpretation provides for an appropriate means for 

protecting these communities. 

BOEM has also identified incomplete or unavailable information regarding impacts to 

chemosynthetic communities from the Deepwater Horizon explosion, oil spill, and response. Information 

on possible impacts to chemosynthetic communities in the WPA may be relevant to the affected 

environment because recent events such as the Deepwater Horizon explosion, oil spill, and response may 

have caused changes to baseline conditions for such communities in the Gulf of Mexico. Information 

regarding impacts of the Deepwater Horizon explosion, oil spill, and response on deepwater 

chemosynthetic communities is being developed through the NRDA process, but this information is not 

yet available and cannot reasonably be obtained within the timeline contemplated in the NEPA analysis of 

this Supplemental EIS. In lieu of this incomplete information, BOEM extrapolated existing information 

using scientifically accepted methodologies. Even though there is evidence of contamination around the 

Macondo well in the CPA (Valentine et al., 2014), existing information suggests that chemosynthetic 

communities in the WPA did not experience significant adverse impacts from the Deepwater Horizon

explosion, oil spill, and response. Numerous cruises using research ships, submersibles, and drift cameras 

investigated the seafloor in the area surrounding the well site (USDOC, NOAA, 2011a and 2011b). 

Damage to chemosynthetic communities in the vicinity of the Macondo well has not been reported to date 

(Shedd, 2015). Furthermore, due to the distance of chemosynthetic communities within the WPA from 

the Macondo well, they were likely not affected to any discernible degree by the Deepwater Horizon

explosion, oil spill, and response. Based on available information, it has not been demonstrated that the 

Deepwater Horizon explosion, oil spill, and response impacted or changed the baseline for 

chemosynthetic communities in the WPA. Therefore, based on the distance of the chemosynthetic 

communities in the WPA from the Macondo well and the data from surveys post-Macondo that do not 
Description of the Environment and Impact Analysis 4-37

show impacts to chemosynthetic communities, BOEM has determined that the incomplete information is 

not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for chemosynthetic communities presented in the prior 2012-

2017 Gulf of Mexico EISs based on the additional information presented above. No new information was 

discovered that would alter the impact conclusion for chemosynthetic communities presented in the prior 

2012-2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA

documents still apply for proposed WPA Lease Sale 248. 

4.1.1.9. Nonchemosynthetic Deepwater Benthic Communities

BOEM has reexamined the analysis for nonchemosynthetic deepwater benthic communities presented 

in the prior 2012-2017 Gulf of Mexico EISs based on the additional information presented below. No 

new information was discovered that would alter the impact conclusion for nonchemosynthetic 

communities presented in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential 

impacts detailed and updated in those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of nonchemosynthetic communities, along with the full analyses of the 

potential impacts of routine activities, accidental events, and cumulative impacts associated with the 

WPA proposed action, are presented in Chapter 4.1.1.9 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.9 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has 

become available since those NEPA documents were published is also presented below. 

Considerable mechanical damage could be inflicted upon sensitive nonchemosynthetic deepwater 

benthic communities by routine OCS oil- and gas-related activities associated with the WPA proposed 

action if mitigations are not applied to permits. Mitigations are based on the protective measures 

described by NTL 2009-G40, “Deepwater Benthic Communities,” and include distancing requirements 

for wells (610 m; 2,000 ft), anchors, chains, and pipelines (76 m; 250 ft) from sensitive habitat. This 

distancing also helps prevent sedimentation and deposition of oil on deepwater benthic communities as a 

result of an accidental, but rare, seafloor loss of well control without a release of substantial quantities of 

oil. BOEM reviews exploration and production plans and pipeline applications, and applies mitigations 

to permits to prevent impacts to sensitive seafloor habitats from routine OCS oil- and gas-related 

activities. Impacts from routine and accidental events are expected to be rare because of the application 

of mitigations.

Routine bottom-disturbing activities (i.e., anchoring, structure and pipeline emplacement, and drill 

cuttings discharges) associated with the WPA proposed action could crush or smother deepwater benthic 

communities. Drilling discharges could bury sessile organisms. Structure and pipeline emplacement 

could destroy carbonate substrates crucial for the attachment of sessile organisms. However, these 

activities are expected to cause little to no damage to the ecological function or biological productivity of 

deepwater benthic communities due to the consistent application of BOEM’s protection policies as 

described in NTL 2009-G40. Information included in required hazards surveys for OCS oil- and gasrelated activities depicts areas that could potentially support nonchemosynthetic communities. Use of 

these data in plan reviews ensures adequate distancing of drilling and associated bottom-disturbing 

activities from areas conducive to the growth of sensitive hard bottom communities. The same 

geophysical conditions associated with the potential presence of chemosynthetic communities (refer to 

Chapter 4.1.1.8) can also result in the occurrence of hard carbonate substrate and associated deepwater 

benthic communities. Because of the distancing requirements for bottom-disturbing activities (i.e., 

anchoring, structure and pipeline emplacement, and drill cuttings discharges) described in the NTL 

2009-G40 guidelines, these communities are generally avoided in exploration and development planning. 

Therefore, impacts on sensitive deepwater communities from routine OCS oil- and gas-related activities 

associated with the WPA proposed action would be minimal to none. 
4-38 Western Planning Area Lease Sale 248 Supplemental EIS

Accidental events that could impact nonchemosynthetic deepwater benthic communities are primarily 

limited to the turbidity and sedimentation associated with seafloor loss of well control, which are rare 

occurrences, and resultant subsea oil spills. A loss of well control at the seafloor could create a crater and 

could resuspend and disperse large quantities of bottom sediments within a 300-m (984-ft) radius from 

the blowout site. This could destroy any organisms located within that distance by burial or modification 

of narrow habitat quality requirements, depending on bottom-current conditions, and possibly prevent 

reestablishment. Rapid burial in sediment could be lethal for all benthic organisms. Subsea oil spills

caused by a loss of well control could devastate local patches of habitat where a subsea oil plume 

physically contacts the seafloor. Any possible impacts would be localized due to the directional 

movement of an oil plume by the water currents and because the sensitive habitats have a scattered, 

patchy distribution. It is also possible that some corals may have some tolerance to limited oil exposure 

and may recover after exposure (Quattrini et al., 2013). However, the application of avoidance criteria for 

deepwater coral communities described in NTL 2009-G40 precludes the placement of a well within 

610 m (2,000 ft) of any suspected site of a deepwater coral community, therefore distancing the 

deepwater coral community from sedimentation.

Cumulative factors considered to impact the deepwater benthic communities (>300 m; 984 ft) of the 

Gulf of Mexico include both OCS oil- and gas-related and non-OCS oil- and gas-related activities. The 

OCS oil- and gas-related activities associated with pipelaying, anchoring, structure emplacement, drilling 

discharges, and seafloor loss of well control have the potential to impact nonchemosynthetic deepwater 

benthic communities. The most serious, impact-producing factor threatening nonchemosynthetic 

communities is physical disturbance of the seafloor, which could destroy the organisms of these 

communities. Such disturbance would most likely come from those OCS oil- and gas-related activities 

associated with pipelaying, anchoring, and structure emplacement. Anchoring and pipeline and structure 

emplacement have the potential to crush deepwater benthic communities. Drilling discharges and 

resuspended sediments have a potential to cause minor, mostly sublethal impacts to nonchemosynthetic 

communities, but substantial accumulations could result in more serious impacts. Possible effects of an 

oil spill could be no discernible effect (for well-dispersed oil undergoing biodegradation), lack of growth, 

interruption of reproductive cycles, loss of gamete viability, tissue damage, death of affected organisms, 

and a reduction in the areas of distribution of species, depending on the amount and duration of 

contamination. Major impacts to localized benthic habitat are possible in the event of a low-probability 

catastrophic blowout on the seafloor (refer to Appendix A for more details). However, a low-probability 

catastrophic oil spill is not part of the WPA proposed action and is not expected to occur. Therefore, 

cumulative impacts to deepwater communities in the Gulf of Mexico are considered negligible because of 

the application of the avoidance criteria described in NTL 2009-G40, which distances bottom-disturbing 

activities from sensitive habitats.

Non-OCS oil- and gas-related activities include fishing and trawling at a relatively small scale; largescale factors include storm impacts and climate change, CO2 build-up, and proposed methods to sequester 

carbon in the deep sea. Bottom-tending (bottom-contacting) fishing gear such as trawling, crab traps, and 

hook-and-line recreational fishing can impact nonchemosynthetic deepwater benthic communities by 

dislodging or crushing organisms attached to the bottom (Hourigan, 2014). Fishing and trawling are not 

expected to severely impact nonchemosynthetic deepwater benthic communities because the water depths 

(>300 m; 984 ft) make the royal red shrimp fishery costly, and the relatively small area occupied by 

potentially commercially and recreationally valuable fishery species in areas associated with these 

communities make the fishery efforts small. Regional and even global impacts from climate change, 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, although such impacts could 

become more severe over time. Storms generally cause little to no impacts at the depths (>300 m; 984 ft) 

where nonchemosynthetic communities occur. A storm could potentially cause some type of accident 

that could then cause secondary impacts, such as shipwrecks or equipment lost overboard that could crush 

nonchemosynthetic communities, but such occurrences would be rare. A hurricane could cause slumping 

of a mass of sediment at the deep seafloor, damaging a platform and causing an oil leak. Slumping with 

this impact can also be caused by the force of gravity acting on a steep slope. State oil and gas activities 

are not expected to impact deepwater benthic communities due to the great distance between such 

activities and water depths of >300 m (984 ft). 

The OCS oil- and gas-related cumulative impacts on deepwater benthic communities are expected to 

be negligible and to cause little damage to their overall ecological function or biological productivity 
Description of the Environment and Impact Analysis 4-39

because of BOEM’s biological review process and the policies described in NTL 2009-G40, which 

physically distances OCS oil- and gas-producing activities from sensitive deepwater benthic communities. 

The incremental contribution of the WPA proposed action to cumulative impacts, such as possible 

impacts caused by physical disturbance of the seafloor and minor impacts from sediment resuspension or 

drill cutting discharges, is expected to be negligible. Adverse impacts will be limited but not completely 

eliminated by adherence to the guidelines described in NTL 2009-G40. Localized impacts from turbidity 

and sedimentation associated with the loss of well control still may occur, but are rare.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

Internet websites visited included four Federal agencies (USEPA, USGS, NOAA [including 

Deepwater Horizon Bibliography], and BOEM), five coastal universities or universities with coastal 

divisions (University of Louisiana at Lafayette, Louisiana State University, Texas A&M University, 

University of Texas at Austin Marine Science Institute College of Natural Sciences, and Florida State 

University), several various stakeholders (Sierra Club, National Fish and Wildlife Foundation, Nature 

Conservancy, Gulf of Mexico Alliance, and Gulf of Mexico Program), and Louisiana Universities Marine 

Consortium (“Effects of Offshore Oil and Gas Development: A Current Awareness Bibliography”). 

Where applicable, websites of subdivisions of many of these agencies, universities, and stakeholders were 

also searched. Environmental journal articles were also located online using two search engines (Google 

Advanced Scholar Search and Google Advanced Book Search). These search engines collectively 

searched all of the ecology journals of six major publishers (John Wiley and Sons, Springer, Elsevier 

Science, Taylor and Francis Group, Cambridge University Press, and Oxford University Press). New 

information was found on the resilience of deepwater corals, as well as information on impacts from 

sedimentation. Doughty et al. (2014) demonstrated that Paramuricia spp., one of the most common 

deepwater corals in the Gulf of Mexico, may have low recruitment rates. This finding could apply more 

broadly to other gorgonians and deepwater coral. This aspect of deepwater coral population dynamics 

could result in slow recovery from anthropogenic impacts such as those from an oil spill. Paramuricia 

spp., and possibly other gorgonians and deepwater coral, may also be impacted by naturally occurring 

sedimentation, and by extrapolation, they could also be impacted by anthropogenic sedimentation such as 

that from drilling discharges and turbidity and from sedimentation from a loss of well control event 

(Doughty et al., 2014). These results reaffirm the necessity for distancing wells from deepwater coral 

habitats to protect them from accumulating drill cutting sediments.

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined the new information does not 

change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. As discussed in this Supplemental EIS, as well as in Chapter 

4.1.1.9 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete information for 

impacts related to the location of deepwater corals in the GOM, toxicity of oil to deepwater corals, 

impacts on deepwater fish communities due to impacts on nonchemosynthetic deepwater benthic 

communities, and impacts from the Deepwater Horizon explosion, oil spill, and response. The below 

information updates or adds to the understanding of incomplete or unavailable information for this 

resource. At present, the best available information does not provide data for a complete understanding of 

these four data gaps. BOEM used reasonably accepted scientific methodologies to extrapolate from 

existing information in completing this analysis and formulating the conclusions presented here.

BOEM’s database of confirmed deepwater benthic communities is used when reviewing deepwater 

exploration and development plans to help ensure that known locations of deepwater coral are not 

impacted by OCS oil- and gas-related activities. This confirmed locations database is not comprehensive 

of all deepwater benthic communities. Therefore, in order to help fill this data gap, BOEM’s subjectmatter experts also make use of other available datasets to identify probable habitat that could support 

deepwater benthic communities. One such dataset is BOEM’s publicly available database of 3D seismic 

water bottom anomalies, which provides the locations of ~28,000 features that could potentially represent 

such suitable habitat for deepwater benthic communities (USDOI BOEM 2015b). BOEM’s subject-
4-40 Western Planning Area Lease Sale 248 Supplemental EIS

matter experts also evaluated the available data that operators are required to provide in site-specific 

hazards surveys such as sidescan sonar, multibeam echo sounder bathymetry, and 3D seismic anomalies. 

In addition, as described in the WPA 246/248 Supplemental EIS, available information may not be of 

sufficient resolution to identify small areas of scattered hard substrate that may support deepwater benthic

habitat, as discussed by Quattrini et al. (2013). Small patches of shell and rubble substrate are commonly 

observed in soft bottoms near active and inactive seep sites, which frequently occur in areas targeted for 

OCS oil- and gas-related activities. If data are sparse or indicate additional detail is warranted, this data 

gap may be addressed through the use of site-specific video or photographic surveys. Subject-matter 

expert analysis of these various datasets during plan reviews helps ensure adequate distancing from 

drilling and associated OCS oil-and gas-related activities. However, even with the continued additions of 

observation records, the majority of deepwater coral communities are not going to be directly observed 

and documented because of the inherent logistical difficulties that limit the spatial extent of deepwater 

research and data collection and because some communities may still be impacted if seafloor surveys do 

not indicate the presence of deepwater benthic habitat. However, new data are being collected that will 

help BOEM fill some of those data gaps in the future. 

The NOAA’s Deep Sea Coral Research and Technology Program and NOAA’s National Centers for 

Coastal Ocean Science have been compiling a detailed national database of known observations of 

deepwater corals and sponges (USDOC, NOAA, National Centers for Coastal Ocean Science, 2015), and 

it is expected to be released in the summer of 2015 once properly vetted by reviewers. It is available to 

the public; however, it is not yet finalized. If it is finalized by the time the Final Supplemental EIS is 

prepared, it will be included in that Supplemental EIS. When finalized, this database will increase the 

number of confirmed observed deepwater coral and sponge records available to BOEM for plan reviews. 

In addition, BOEM is helping fund work by NOAA’s National Centers for Coastal Ocean Science to 

improve previous predictive habitat suitability modeling (Kinlan et al., 2013) of actual and potential 

distribution of deepwater coral and chemosynthetic biota in the Gulf of Mexico. New datasets and 

models, once they are complete, available, and vetted, could provide ancillary information to further assist 

these site-specific evaluations. However, BOEM has determined that the incomplete information is not 

essential to a reasoned choice among alternatives because BOEM reviews plans on a case-by-case basis 

using BOEM’s 3D seismic water bottom anomaly database and requests follow-up surveys as necessary 

to ensure adequate distancing from drilling and associated OCS oil-and gas-related activities to reduce the 

possibility of impacting deepwater benthic habitat. 

Information on the toxic impacts of oil on deepwater corals is unavailable. An investigation of 

several deepwater octocorals and their association with naturally occurring oil seeps indicated that one 

species was found in association with them. The results of this study indicate that this coral could 

“possess mechanisms for dealing with natural levels of exposure to hydrocarbons” (Quattrini et al. 2013). 

Such an adaptation could result in resilience after exposure to oil from a blowout. It is possible that, if 

this coral species is tolerant of some oil exposure, others may or may not be; however, that information is 

not known at this time. BOEM has determined that information regarding the potential tolerance of 

deepwater corals to some oil exposure is not essential to a reasoned choice among alternatives because 

BOEM requires that OCS oil- and gas-related activities are sufficiently distanced from deepwater corals 

and because exposure from accidental events is unlikely.

Nonchemosynthetic deepwater benthic communities within the WPA were likely not affected to any 

discernible degree by the Deepwater Horizon explosion, oil spill, and response because of the WPA’s 

distance from the Macondo well. Information on possible impacts to nonchemosynthetic communities in 

the WPA may be relevant to the affected environment because recent events such as the Deepwater 

Horizon explosion, oil spill, and response may have caused changes to baseline conditions for such 

communities in the Gulf of Mexico. Studies in the CPA have indicated that deepwater corals 7 mi 

(11 km) southeast of the spill location may have been damaged following the Deepwater Horizon

explosion, oil spill, and response, based on information collected about 4-5 months after the well was 

capped (White et al., 2012). Damage to corals at the same site, possibly due to the spill, declined over a 

period of about 20 months after the well was capped (Hsing et al., 2013). Subsea oil spills caused by a 

loss of well control could devastate local patches of habitat where a subsea oil plume physically contacts 

the seafloor. If dispersant is used in deep water at a wellhead or a loss of well control occurs at high 

pressure (as happened with the Deepwater Horizon explosion), microdroplets of oil can be transported to 

greater distances impacting benthic communities (White et al., 2012). Oil near the surface can also

become associated with plankton, bacteria and related mucus, and other particulate material to form 
Description of the Environment and Impact Analysis 4-41

Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) and eventually sink to the 

bottom at greater distances (Passow, 2014). However, dispersants likely will inhibit formation of oilrelated marine snow from oil at the sea surface (Passow, 2014). Deepwater corals could be more 

susceptible due to mucus associated with tissues trapping oiled particulate material. Any possible impacts 

would be localized because of the directional movement of an oil plume by the water currents and 

because the sensitive habitats have a scattered, patchy distribution. The mucus-rich character of microbial 

oil-related marine snow is consistent with the material found covering corals (Hsing et al., 2013; White 

et al., 2012), and the patchy distribution of this material on corals is consistent with sinking marine snow 

(Passow, 2014). It is also possible that some corals may have some tolerance to limited oil exposure and 

may recover after exposure (Quattrini et al., 2013). Additional information regarding impacts of the 

Deepwater Horizon explosion, oil spill, and response on deepwater nonchemosynthetic communities is 

being developed through the NRDA process, but this information is not yet available and cannot 

reasonably be obtained within the timeline contemplated in the NEPA analysis of this Supplemental EIS 

and because the overall costs in time and money to collect these data are exorbitant. BOEM recognizes 

that the incomplete information with respect to long-term effects may be relevant to the evaluation of 

impacts on nonchemosynthetic deepwater benthic communities. However, the distance of the WPA from 

the Deepwater Horizon explosion, oil spill, and response and the lack of published information from this 

in the WPA makes it likely that the Deepwater Horizon explosion, oil spill, and response had negligible 

impacts to the WPA. In addition, BOEM used reasonably accepted scientific methodologies to 

extrapolate from existing information in completing this analysis and formulating the conclusions 

presented here. Therefore, BOEM has determined that the incomplete information is not essential to a 

reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for nonchemosynthetic communities presented in the prior 2012-

2017 Gulf of Mexico EISs based on the additional information presented above. No new information was 

discovered that would alter the impact conclusion for nonchemosynthetic deepwater benthic communities

presented in the prior 2012-2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and 

updated in those NEPA documents still apply for proposed WPA Lease Sale 248. Regarding incomplete 

information and the existing information used in its place, BOEM has determined that the incomplete 

information is not essential to a reasoned choice among alternatives.

4.1.1.10.Soft Bottom Benthic Communities

BOEM has reexamined the analysis for soft bottom benthic communities presented in the prior 2012-

2017 Gulf of Mexico EISs based on the information presented below. No new information was 

discovered that would alter the impact conclusion for soft bottom benthic communities presented in the 

prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in 

those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of soft bottom benthic communities, along with the full analysis of the 

potential impacts of routine activities, accidental events, and cumulative impacts associated with the 

WPA proposed action, are presented in Chapter 4.1.1.10 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.10 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has 

become available since those NEPA documents were published is presented below. 

A majority of the oil and gas exploration in the GOM is conducted on soft seafloor sediments, 

directly impacting soft bottom benthic communities. Routine OCS oil- and gas-related activities result in 

a number of impact-producing factors, including seafloor disturbances (e.g., anchoring, trenching, 

infrastructure emplacement, and infrastructure removal), waste discharge (e.g., drilling muds and cuttings 

from oil and gas operations), and resuspension of sediments (e.g., pipeline burial and decommissioning

operations). Disturbances of soft bottom benthic communities cause localized disruptions to benthic 

community composition and an alteration in food sources for some large invertebrate and finfish species. 
4-42 Western Planning Area Lease Sale 248 Supplemental EIS

Analysis of these routine activities has identified only localized and short-term impacts to soft bottom 

benthic communities. Any activity that may affect the soft bottom communities would only impact a 

small portion of the overall area of the seafloor of the Gulf of Mexico. Because soft bottom substrate is 

ubiquitous throughout the Gulf of Mexico, there are no lease stipulations to avoid these communities; 

however, other routine practices restrict detrimental activities that could cause undue harm to benthic 

habitats (e.g., discharge restrictions, debris regulations, and National Pollutant and Discharge Elimination 

System [NPDES] permits).

Accidental oil spills associated with OCS oil- and gas-related activities can disturb infaunal 

communities. Because of the proportionately small area that OCS oil- and gas-related activities occupy 

on the seafloor, only a very small portion of the Gulf of Mexico’s soft bottom benthic communities would 

experience impacts as a result of an oil spill. The greatest impacts would likely occur closest to the 

source of the spill, and impacts would rapidly decrease with increased distance from the source. Contact 

with spilled oil outside the vicinity of the event would likely cause sublethal to negligible effects to 

benthic invertebrates and finfishes. Oil deposited on sediment communities could result in changes to 

local community structure. The organic enrichment of impacted sediments may result in altered sediment 

communities as bacteria degrade deposited organic matter. This response can lead to hypoxic conditions 

and a series of altered community structures until the organic matter is depleted and surface sediments 

return to an oxygenated state (Neff, 2005). Although an oil spill may have some detrimental impacts, 

especially closest to the occurrence of the spill, the impacts may be no greater than natural fluctuations 

(Clark, 1982), and impacts would affect a relatively small portion of the seafloor.

The cumulative analysis considers activities that have occurred, are currently occurring, and could 

occur and adversely affect the soft bottoms of the Gulf of Mexico for the years 2012-2051. Long-term 

OCS oil- and gas- related activities are not expected to adversely impact the entire soft bottom 

environment of the GOM because the locally impacted areas are small in comparison with the entire area 

of the GOM. The OCS impacts from seafloor disturbances, the discharge of drilling muds and cuttings, 

and the resuspension of sediments may have locally devastating impacts, but impacted communities are 

repopulated relatively quickly and the cumulative effect on the overall seafloor and benthic communities 

would be negligible. The incremental contribution of the WPA proposed action to the cumulative impact 

is expected to be negligible.

Non-OCS oil- and gas-related activities such as anchoring, trawling, sand mining, State oil and gas 

activities, import tankering, and storms are likely to impact the soft bottom communities more frequently 

than do OCS oil- and gas-related activities. These activities could cause temporary damage to soft bottom 

communities. Anchoring on soft bottoms could crush underlying organisms, and activities such as 

commercial shrimping regularly disturb large areas of the continental shelf. Sand mining could affect 

benthic organisms through both turbidity and sedimentation, and import tankering could result in nonOCS oil- and gas-related oil spills. During severe storms, such as hurricanes, bottom sediments may be 

disturbed, causing increased turbidity and reintroduction of contaminants to the water column. In some 

areas, soft bottom benthic communities remain in an early successional stage due to the frequency of 

natural and anthropogenic disturbances. However, overall impacts from non-OCS oil- and gas-related 

activities to soft bottom benthic communities are minimal due to the fact that the effects are temporary, 

soft bottom habitat is ubiquitous throughout the GOM, and impacted soft bottom benthic communities 

can recruit quickly from neighboring areas. 

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

BOEM has examined newly available information for findings that may impact analyses of routine, 

accidental, and cumulative OCS activities and potentially alter previous conclusions. A search of Internet 

information sources and scientific journals was conducted to determine the availability of recent 

information (including NMFS databases, the NOAA Gulf Spill Restoration Publications website, the Gulf 

of Mexico Fishery Management Council (GMFMC) website, Science Direct, EBSCO, Elsevier, PLoS 

ONE, JSTOR, and BioOne). Since publication of the prior 2012-2017 Gulf of Mexico EISs, no new 

information relevant to an analysis of the potential impacts of OCS oil- and gas-related activities on soft 

bottom benthic communities has been published. 
Description of the Environment and Impact Analysis 4-43

Incomplete or Unavailable Information 

BOEM has determined that there is still incomplete or unavailable information regarding the potential 

impacts to soft bottom benthic habitat from OCS oil- and gas-related activities. As discussed in Chapter 

4.1.1.10 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete information for 

impacts related to the distribution and abundance of deepwater corals in areas of predominantly soft 

bottom habitat; the long-term effects of persistent PAHs (Kimes et al., 2013; Liu and Liu, 2013; Mason 

et al., 2014), and the long-term effects of episodic sedimentation events (Allers et al., 2013; Kimes et al., 

2013; Liu and Liu, 2013; Mason et al., 2014). 

Although the distribution and abundance of deepwater corals in areas of predominantly soft bottom

habitat is not well known, BOEM uses reasonably accepted scientific methodologies to extrapolate from 

existing information when locating communities and suitable substrates potentially impacted by proposed 

OCS oil- and gas-related activities. Data produced using several seafloor survey methods are analyzed to 

identify potential deepwater coral habitat. Refer to Chapter 4.1.1.9 for more detail on these surveys and 

reviews. BOEM has determined the incomplete information is not essential to a reasoned choice among 

alternatives because BOEM reviews plans and surveys on a case-by-case basis to reduce the possibility of 

impacting deepwater coral habitat.

The cumulative impacts of OCS oil and gas exploration and development may result in locally 

significant impacts to soft bottom benthic communities. However, soft bottom communities are abundant 

throughout the GOM and the area of the seafloor impacted by OCS oil- and gas-related activities is very 

small in comparison with the overall area of soft bottom habitat in the GOM. BOEM used reasonably 

accepted scientific methodologies to conduct an analysis of available information on the degradation of 

hydrocarbons in sediments following oil spills and did not identify any reasonably foreseeable impacts 

extending beyond localized responses to persistent PAHs or sedimentation events among soft bottom 

inhabitants (Kimes et al., 2013; Liu and Liu, 2013; Mason et al., 2014). Therefore, BOEM has 

determined that the incomplete information is not essential to a reasoned choice among alternatives 

because the affected areas are small and most impacts are short term.

Soft bottom benthic communities within the WPA were likely not affected to any discernible degree 

by the Deepwater Horizon explosion, oil spill, and response because of the WPA’s distance from the 

Macondo well. Although information on possible impacts to soft bottom benthic communities in the 

WPA may be relevant to the baseline conditions of the affected environment, incomplete information and 

other relevant data regarding the status and function of soft bottom benthic communities, including that 

being developed through the NRDA process, may take years to acquire and analyze and cannot be 

obtained in the timeline contemplated in the NEPA analysis of this Supplemental EIS. BOEM used 

reasonably accepted scientific methodologies to extrapolate from existing information in completing the 

analysis of impacts to soft bottom benthic communities and subsequent recovery. Published data indicate 

that microbial communities transition rapidly when exposed to changing environmental conditions and 

demonstrate significant resiliency (Kimes et al., 2013; Liu and Liu, 2013; Mason et al., 2014). Although 

the body of available information is incomplete and long-term effects cannot yet be known, the evidence 

currently available supports past analyses and does not indicate severe adverse impacts to the soft bottom 

benthic communities of the WPA or entire GOM as a result of OCS oil- and gas-related activities. 

Therefore, BOEM has determined that the incomplete information is not essential to a reasoned choice 

among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for soft bottom benthic communities based on the information 

provided above. The accumulated data used in this and previous analyses do not indicate significant 

population-level impacts to soft bottom benthic communities. No new information was discovered that 

would alter the impact conclusion for soft bottom benthic communities presented in the prior 2012-2017 

Gulf of Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA documents 

still apply for proposed WPA Lease Sale 248.

4.1.1.11.Marine Mammals

BOEM has reexamined the analysis for marine mammals presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented below. No new information was discovered 
4-44 Western Planning Area Lease Sale 248 Supplemental EIS

that would alter the impact conclusion for marine mammals presented in the prior 2012-2017 Gulf of 

Mexico EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents 

still apply for proposed WPA Lease Sale 248.

A detailed description of marine mammals, along with the full analyses of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.11 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.11 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below. 

Operators must adhere to certain NTLs while conducting OCS oil- and gas-related activities in order 

to reduce impacts to marine mammals. The operator’s reaffirmed compliance with NTL 2012-JOINTG01 (“Vessel Strike Avoidance and Injured/Dead Protected Species Reporting”) and NTL 2012-BSEEG01 (“Marine Trash and Debris Awareness and Elimination”), as well as the limited scope, timing, and 

geographic location of the WPA proposed action, would result in negligible effects from the proposed 

drilling activities on marine mammals. In addition, NTL 2012-JOINT-G02, “Implementation of Seismic 

Survey Mitigation Measures and Protected Species Observer Program,” minimizes the potential of harm 

from seismic operations to marine mammals. These mitigations include onboard observers, airgun shutdowns for whales in the exclusion zone, ramp-up procedures, and the use of a minimum sound source. 

The routine activities associated with proposed WPA Lease Sale 248 that could potentially affect 

marine mammals include the following: the degradation of water quality from operational discharges; 

noise generated by aircraft, vessels, operating platforms, and drillships; vessel traffic; explosive structure 

removals; seismic surveys; and marine debris from service vessels and OCS structures. Some routine 

activities related to the WPA proposed action have the potential to have adverse, but not significant, 

impacts to marine mammal populations in the Gulf of Mexico. Impacts from vessel traffic, structure 

removals, and seismic activity could negatively impact marine mammals and have the potential to harm 

or harass marine mammal species by increasing noise levels. These activities, when mitigated as required 

by BOEM and NMFS (through the requirements of ESA consultations; refer to Chapter 5.6 for more 

information), are not expected to have long-term impacts on the size and productivity of any marine 

mammal species or population. Mitigation reduces the risk of harassing or harming marine mammal 

species. Other routine activities such as aircraft activity, drilling and production noise, discharges, and 

marine debris are expected to have negligible effects.

Impact-producing factors associated with accidental events that may be associated with the WPA 

proposed action that could affect marine mammals include oil spills and spill-response activities. 

Accidental events related to the WPA proposed action have the potential to have adverse, but not 

significant, impacts to marine mammal populations 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. Oil spills may cause chronic (long-term lethal or sublethal oil-related injuries) and 

acute (spill-related deaths occurring during a spill) effects on marine mammals. Long-term effects 

include decreases in prey availability and abundance because of increased mortality rates, change in ageclass population structure because certain year-classes were impacted more by oil, decreased reproductive 

rate, and increased rate of disease or neurological problems from exposure to oil (Harvey and Dahlheim, 

1994). 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 physiological and toxic effects.

Even after an oil spill is stopped, oiling or deaths of marine mammals could still occur due to oil and 

dispersants persisting in the water, past marine mammal/oil or dispersant interactions, and ingestion of 

contaminated prey. The animals’ exposure to hydrocarbons persisting in the sea may result in sublethal 

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

and some soft tissue irritation, respiratory stress from inhalation of toxic fumes, food reduction or 

contamination, direct ingestion of oil and/or tar, and temporary displacement from preferred habitats. 

The cumulative impact analysis considers the effects of impact-producing factors related to OCS oiland gas-related impacts, along with non-OCS oil- and gas-related impacts of other commercial, military, 
Description of the Environment and Impact Analysis 4-45

recreational, offshore, and coastal activities that may occur and adversely affect marine mammals in the 

same general area of the WPA proposed action. The major impact-producing factors resulting from 

cumulative OCS oil- and gas-related activities associated with the WPA proposed action that may affect 

marine mammals and their habitats include ingestion and entanglement in marine debris; contaminant 

spills and spill-response activities; vessel strikes; and noise from multiple sources including seismic 

surveys and explosive structure removals. Noise in the ocean has become a worldwide topic of concern, 

particularly in the last two decades. Noises originate from a broad range of sources, both natural and 

anthropogenic (Richardson et al., 1995). Virtually all of the marine mammal species in the GOM have 

been exposed to OCS industrial noise due to the rapid advancement into GOM deep oceanic waters by the 

oil and gas industry in recent years (which may have led to marine mammals becoming habituated to the 

activity); 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. Most marine mammal species in the GOM, 

and particularly the deepwater mammals, rely on echolocation for basic and vital life processes, including 

feeding, navigation, and interspecific and conspecific communication. Noise levels that interfere with 

these basic marine mammal capabilities could have impacts on individuals as well as marine mammal 

populations. The OCS oil and gas industry’s operations contribute noise to the marine environment from 

several different operations, including G&G surveys, vessel noise, drilling, and explosive removals. 

Cumulative impacts on marine mammals are expected to result in some potentially chronic as well as 

sublethal effects (i.e., behavioral effects and nonfatal exposure to or intake of OCS oil- and gas-related 

contaminants or discarded debris) that may stress and/or weaken individuals of a local group or 

population and that may make them more vulnerable to parasites or diseases (Harvey and Dahlheim, 

1994). The net result of any disturbance will depend upon the size and percentage of the population 

likely to be affected, the ecological importance of the disturbed area, the environmental and biological 

parameters that influence an animal’s sensitivity to disturbance and stress, or the accommodation time in 

response to prolonged disturbance (Geraci and St. Aubin, 1980). As discussed in Chapter 1.2, the 

proposed WPA lease sale area encompasses virtually all of the WPA’s approximately 28.58 million acres 

(ac). This area begins 3 marine leagues (9 nmi; 10.36 mi; 16.67 km) offshore Texas and extends seaward 

to the limits of the United States’ jurisdiction over the continental shelf (often the Exclusive Economic 

Zone) in water depths up to approximately 3,346 m (10,978 ft). The disturbance would be dependent on 

the size of the area that is leased, surveyed, and developed, and the number of animals there at the time. 

An additional description of the species expected to be present and the impacts to those species are 

discussed in Chapter 4.1.1.11 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.11 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. Further, as discussed in Appendix A, a lowprobability, large-scale catastrophic event could also have population-level effects on marine mammals.

The effects of the WPA proposed action, when viewed in light of the effects associated with other 

past, present, and reasonably foreseeable future activities may result in more significant impacts to marine 

mammals, as compared with effects before the Deepwater Horizon explosion, oil spill, and response; 

however, the magnitude of those effects cannot yet be determined. Nonetheless, operators are required to 

follow all applicable lease stipulations and regulations, as clarified by NTLs (i.e., NTL 2012-JOINT-G01, 

NTL 2012-BSEE-G01, and NTL 2012-JOINT-G02), to minimize these potential interactions and impacts. 

Even when taking into consideration the potential effects of the Deepwater Horizon explosion, oil spill, 

and response and the minimization of impacts through lease stipulations and regulations, no significant 

cumulative impacts to marine mammals would be expected as a result of the proposed exploration 

activities when added to the impacts of past, present, or reasonably foreseeable oil and gas development 

in the area, as well as other ongoing activities in the area.

Non-OCS oil- and gas-related activities that may affect marine mammal populations include vessel 

traffic and related noise (including from commercial shipping and research vessels), State oil and gas 

activities, military operations, commercial fishing, pollution, scientific research, and natural phenomena. 

Groups such as the military (i.e., U.S. Navy and USCG) and other Federal agencies (i.e., USEPA, COE, 

National Science Foundation, USGS, and NMFS), dredging companies, commercial fishermen, and 

recreational boaters operate vessels and aircraft and contribute to the overall noise level in the GOM. 

Pollution in the ocean comes from many point and nonpoint sources, including the drainage of the 

Mississippi River being discharged into the GOM. Tropical storms and hurricanes are normal 

occurrences in the GOM and along the Gulf Coast. Generally, the impacts from these storms have been 
4-46 Western Planning Area Lease Sale 248 Supplemental EIS

localized and infrequent. The actual impacts of these storms on the animals in the GOM, and the listed 

species and critical habitat in particular, have not yet been determined and, for the most part, may remain 

difficult to quantify.

An unusual mortality event (UME) is defined under the MMPA as “a stranding that is unexpected; 

involves a significant die-off of any marine mammal population; and demands immediate response.” 

Infections, biotoxins, human interactions, and malnutrition are considered major factors in UMEs. A 

UME for bottlenose dolphins occurred off the coast of Texas in 2011-2012 when 126 dolphins were 

stranded. There is no confirmed cause for the strandings; however, findings include infected lungs, poor 

body condition, discoloration of the teeth, and substance in the stomach in four of the animals (USDOC, 

NMFS, 2014a). Further, a UME for cetaceans that encompasses the entire northern GOM began in 

February 2010 and has continued. This UME is defined by the Florida panhandle west to the LouisianaTexas border (USDOC, NMFS, 2014a). A recent study provided information regarding details on 

histopathology reports from bottlenose dolphins affected by the northern Gulf of Mexico UME 

(Venn-Watson et al., 2015a). For more details, refer to the “New Information Available” section below. 

Continued research will provide a better understanding about the relationship of these UMEs to the 

Deepwater Horizon explosion, oil spill, and response, which is still under investigation (refer to the 

“Incomplete or Unavailable Information” section below).

The incremental contribution of the WPA proposed action to the cumulative impact is expected to be 

negligible. There are existing leases in the WPA with either ongoing or the potential for exploration, 

drilling, and production activities. In addition, non-OCS oil- and gas-related activities discussed herein 

will continue to occur in the WPA irrespective of the WPA proposed action. The potential for effects 

from changes to the affected environment (post-Deepwater Horizon), routine activities, accidental events, 

low-probability catastrophic spills (refer to Appendix A), which are not part of the WPA proposed action

and not reasonably expected to occur, and cumulative impacts remains whether or not the No Action or an 

Action alternative is chosen under this Supplemental EIS. Impacts on marine mammals from either 

smaller accidental events or low-probability catastrophic events would remain the same.

Within the WPA, there is a long-standing and well-developed OCS Program (more than 50 years); 

existing available data do not suggest that activities from the preexisting OCS Program are significantly 

impacting marine mammal populations. Therefore, in light of the WPA proposed action and its impacts, 

the incremental effect of the WPA proposed action on marine mammal populations is not expected to be 

significant when compared with non-OCS oil- and gas-related activities.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of Internet information sources (NOAA’s website and the RestoreTheGulf.gov website), as 

well as recently published journal articles, was conducted to determine the availability of recent 

information on marine mammals. 

On December 13, 2010, NMFS declared an UME for cetaceans (whales and dolphins) in the Gulf of 

Mexico. Evidence of the UME was first noted by NMFS as early as February 2010, before the 

Deepwater Horizon explosion, oil spill, and response occurred. The NMFS frequently updates the 

number of marine mammals stranded as a result of the UME; this information can be found on its website 

(USDOC, NMFS, 2015). As of April 12, 2015, a total of 1,370 cetaceans (6% stranded alive and 94% 

stranded dead) have stranded since the start of the UME, with a vast majority of these strandings between 

Franklin County, Florida, and the Louisiana/Texas border (Table 4-1; USDOC, NMFS, 2015). In 

addition to investigating all other potential causes, scientists are investigating what role the bacterium 

Brucella plays in the northern Gulf of Mexico UME. As of November 25, 2014, 54 out of 177 dolphins 

tested were positive or suspected positive for Brucella (USDOC, NMFS, 2014b).

A new study, which was published on February 11, 2015, indicates that the current multiyear marine 

mammal UME in the northern Gulf of Mexico has multiple groupings of high bottlenose dolphin 

mortalities and may be due to different contributing factors, including the Deepwater Horizon oil spill

(Venn-Watson et al., 2015b). Identification of spatial, temporal, and demographic groupings within the 

UME suggest that this mortality event may involve different contributing factors varying by location and 

time, including a potential contributing role of the Deepwater Horizon oil spill, which will be better 

discerned by incorporating diagnostic information including histopathology and other tissue analysis. 
Description of the Environment and Impact Analysis 4-47

A related study provided information regarding details on histopathology reports from bottlenose 

dolphins affected by the northern Gulf of Mexico UME (Venn-Watson et al., 2015a). This study 

confirmed that adrenal disease was prevalent in dolphins that stranded between 2010 and 2012, and it 

may offer insight to contributing factors for the UME. Results from this study also parsed out a subset of 

dolphins from Barataria Bay, Louisiana, and showed adrenal atrophy was more prevalent in that isolated 

cluster. Bacterial pneumonia was identified from dolphins before and during the UME but was detected 

more in the UME dolphins. Continued research will provide a better understanding about the relationship 

of these UMEs to the Deepwater Horizon explosion, oil spill, and response, which is still under 

investigation (refer to the “Incomplete or Unavailable Information” section below).

More detail on the UME can be found on NMFS’s website (USDOC, NMFS, 2014a). It is still 

unclear at this time whether the increase in strandings is related partially, wholly, or not at all to the

Deepwater Horizon explosion, oil spill, and response. 

Incomplete or Unavailable Information 

After evaluating the information above, BOEM has determined that the new information does not 

change the conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. As discussed in this Supplemental EIS, as well as in Chapter 

4.1.1.11 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete information for 

impacts on marine mammals from the Deepwater Horizon explosion, oil spill, and response. The final 

determinations on damages to marine mammal resources from the Deepwater Horizon explosion, oil spill, 

and response will ultimately be made through the NRDA process. The Deepwater Horizon explosion, oil 

spill, and response will ultimately allow a better understanding of any realized effects from a lowprobability catastrophic spill, which is not part of the WPA proposed action and not likely expected to 

occur. However, even with recent publications such as Schwacke et al. (2013) and Venn-Watson et al. 

(2015a and 2015b), all of which described health issues of bottlenose dolphins in Barataria Bay, 

Louisiana, following the spill, the best available information on impacts to marine mammals does not yet 

provide a complete understanding of the effects of the oil spill and active response/cleanup activities from 

the Deepwater Horizon explosion, oil spill, and response on marine mammals as a whole in the GOM and 

whether these impacts reach a population level. As identified above, unavailable information such as the 

anthropogenic impacts following an oil-spill response and population variation due to naturally occurring 

events such as hurricanes and UMEs provide challenges in understanding the baseline conditions and 

changes within marine mammal populations. 

Here, BOEM concludes that the unavailable information from these events may be relevant but not 

necessarily essential to reasonably foreseeable significant adverse impacts to marine mammals from the 

Deepwater Horizon explosion, oil spill, and response. In some specific cases, such as with bottlenose 

dolphins as noted above, the unavailable information may also be relevant to a reasoned choice among the 

alternatives based on the discussion below. The cost of obtaining data on the effects from the UME 

and/or Deepwater Horizon explosion, oil spill, and response are exorbitant, are duplicative of efforts 

already being undertaken as part of the UME and NRDA, and would likewise take years to acquire and 

analyze through the existing NRDA and UME processes. The NMFS has jurisdiction for the 

investigation of marine mammal strandings and has only released raw data on stranding numbers to date. 

Therefore, it is not possible for BOEM to obtain this information within the timeline contemplated in the 

NEPA analysis of this Supplemental EIS, regardless of the cost or resources needed. In light of the 

incomplete or unavailable information, BOEM’s subject-matter experts have used available scientifically 

credible evidence, such as the scientific research evaluated in the 2012-2017 WPA/CPA Multisale EIS as 

well as new information on the Deepwater Horizon explosion, oil spill, and response, such as the 

Schwacke et al. (2013) paper, in this analysis and applied it using accepted scientific methods and 

approaches. The majority of oil-spill effect data derived from the Exxon Valdez oil spill and limited 

exposure treatments (i.e., Waring et al., 2011; Geraci and St. Aubin, 1980; St. Aubin and Lounsbury, 

1990) suggests that localized populations/species in the WPA are unlikely to have been affected. Wider 

ranging species may have been exposed to the spill but they are unlikely to have experienced populationlevel effects due to their wide-ranging distributions and behavior (i.e., Davis et al., 2000; Jochens et al., 

2008). Further, impacts from the Deepwater Horizon explosion, oil spill, and response may be difficult 

or impossible to discern from other factors. For example, even 20 years after the Exxon Valdez spill, 

long-term impacts to marine mammal populations were still being investigated (Matkin et al., 2008). 
4-48 Western Planning Area Lease Sale 248 Supplemental EIS

Therefore, it is not possible for BOEM to obtain this information within the timeline contemplated in the 

NEPA analysis of this Supplemental EIS regardless of the cost or resources needed. In light of the 

incomplete or unavailable information, BOEM’s subject-matter experts have used available scientifically 

credible evidence in this analysis and applied it using accepted scientific methods and approaches. 

Nevertheless, a complete understanding of the missing information is not essential to a reasoned choice 

among alternatives for this Supplemental EIS (including the No Action and Action alternatives) for the 

three main reasons listed below.

(1) The WPA is an active oil and gas region with ongoing (or the potential for) 

exploration, drilling, and production activities. In addition, non-OCS oil- and gasrelated activities will continue to occur in the WPA irrespective of the WPA 

proposed action (i.e., fishing, military activities, and scientific research). The 

potential for effects from changes to the affected environment (post-Deepwater

Horizon), routine activities, accidental spills (including low-probability catastrophic 

spills), and cumulative effects remains whether or not the No Action or an Action 

alternative is chosen under this Supplemental EIS. Impacts on marine mammals

from either smaller accidental events or low-probability catastrophic events will 

remain the same.

(2) Some marine mammal populations in the WPA do not generally travel throughout 

areas affected by spilled oil from the Deepwater Horizon explosion, and they would 

not be subject to a changed baseline or cumulative effects from the Deepwater 

Horizon explosion, oil spill, and response (e.g., coastal bottlenose dolphins that are 

resident in the WPA). Other marine mammals, such as Bryde’s whales and 

manatees, although potentially affected by the Deepwater Horizon explosion, oil 

spill, and response do not typically occur in the WPA. 

(3) Other wide-ranging populations of marine mammals (e.g., sperm whales and killer 

whales) that may occur in the WPA and within areas affected by the spill are unlikely 

to have experienced population-level effects from the Deepwater Horizon explosion, 

oil spill, and response given their wide-ranging distribution and behaviors. 

Summary and Conclusion

BOEM has reexamined the analysis for marine mammals presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented above. The information discovered does not 

alter the impact conclusion for marine mammals presented in the prior 2012-2017 Gulf of Mexico EISs. 

The analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248. 

4.1.1.12.Sea Turtles

BOEM has reexamined the analysis for sea turtles presented in the prior 2012-2017 Gulf of Mexico 

EISs based on the additional information presented below. Sea turtle species in the GOM include the 

loggerhead (Caretta caretta), Kemp’s ridley (Lepidochelys kempi), hawksbill (Eretmochelys imbricata), 

green (Chelonia mydas), and leatherback (Dermochelys coriacea) sea turtles. The information discovered 

does not alter the impact conclusion for sea turtles presented in the prior 2012-2017 Gulf of Mexico EISs. 

Further, the analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248. 

A detailed description of sea turtles, along with the full analyses of the potential impacts of routine 

activities, accidental events, and cumulative impacts associated with the WPA proposed action, are 

presented in Chapter 4.1.1.12 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.12 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 
Description of the Environment and Impact Analysis 4-49

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below. 

In order to minimize potential interactions and impacts to sea turtles, operators are required to follow 

all applicable lease stipulations and regulations, as clarified by NTLs. The operator’s reaffirmed 

compliance with NTL 2012-JOINT-G01 (“Vessel-Strike Avoidance and Injured/Dead Protected Species 

Reporting”) and NTL 2012-BSEE-G01 (“Marine Trash and Debris Awareness Elimination”), as well as 

the limited scope, timing, and geographic location of the WPA proposed action, would result in negligible 

effects from the WPA proposed action on sea turtles. In addition, NTL 2012-JOINT-G02, 

“Implementation of Seismic Survey Mitigation Measures and Protected Species Observer Program,” 

minimizes the potential of harm from seismic operations to sea turtles and marine mammals; these 

mitigating measures include onboard observers, airgun shut-downs for whales in the exclusion zone, 

ramp-up procedures, the use of a minimum sound source, and delayed use of explosives when turtles or 

marine mammals are observed in the exclusion zone. 

The routine activities associated with proposed WPA Lease Sale 248 that could potentially affect sea 

turtles include the following: the degradation of water quality resulting from operational discharges; 

noise generated by helicopter and vessel traffic, platforms, drillships, and seismic exploration; noise and 

impact from explosive structure removals; vessel strikes; and marine debris generated by service vessels 

and OCS facilities. Noise disturbance and/or exposure to sublethal levels of toxins and anthropogenic 

contaminants may stress animals, weaken their immune systems, and make them more vulnerable to 

parasites and diseases that normally would not be fatal during their life cycle. Because of the mitigations

(e.g., BOEM- and BSEE-proposed compliance with NTLs) as described in the 2012-2017 WPA/CPA 

Multisale EIS and summarized above, routine activities (e.g., operational discharges, noise, vessel traffic, 

and marine debris) related to the WPA proposed action are not expected to have long-term adverse effects 

on the size and productivity of any sea turtle species or populations in the northern Gulf of Mexico. With 

the mitigations, few deaths are expected from chance collisions with OCS service vessels, ingestion of 

plastic material, and pathogens. To minimize impacts to sea turtles and marine mammals from explosive 

structure removal, the use of explosives is delayed when turtles or marine mammals are observed in the 

exclusion zone. In addition, while little is known about sea turtle hearing, the best available scientific 

information indicates that sea turtles do not rely on acoustics; therefore, vessel noise and noise from 

related activities (i.e., drilling, seismic exploration, and explosive structure removals) would have limited 

effect. Most routine OCS oil- and gas-related activities are expected to have sublethal effects that are not 

expected to rise to the level of significance.

Accidental events including marine debris generated by service vessels and OCS facilities, oil spills, 

contaminant spills, and spill-response activities that may be associated with the WPA proposed action 

have the potential to impact small to large numbers of sea turtles in the GOM, depending on the 

magnitude and frequency of accidents, the ability to respond to accidents, the location and time of year 

the accidents occur, and various meteorological and hydrological factors. Impacts from smaller 

accidental events may affect individual sea turtles in the area, but impacts are unlikely to rise to the level 

of population effects (or significance) given the size and scope of such spills. Population-level impacts 

are not anticipated based on the best available information. Further, the potential remains for smaller 

accidental spills to occur in a WPA proposed action area, regardless of any alternative selected under this 

Supplemental EIS, given that it is an active oil and gas region with either ongoing or the potential for 

exploration, drilling, and production activities. 

The cumulative analysis considers the effects of impact-producing factors related to OCS oil- and 

gas-related activities along with non-OCS oil- and gas-related impacts of other commercial, military, 

recreational, offshore, and coastal activities that may occur and adversely affect sea turtles in the same 

general area of the WPA proposed action. The major impact-producing factors resulting from cumulative 

OCS oil- and gas-related activities associated with the WPA proposed action that may affect sea turtles 

and their habitats include marine debris, contaminant spills and spill-response activities, vessel strikes, 

noise, seismic surveys, and explosive structure removals. Most routine impacts are minimized by the 

operator’s requirement to follow all applicable lease stipulations and regulations, as clarified by NTLs. 

Lease stipulations and regulations are in place to reduce vessel strike mortalities, as well as impacts from 

marine trash and debris and seismic surveys. In addition, most OCS oil- and gas-related impacts are 

expected to be sublethal and occur on an individual level (i.e., behavioral effects and nonfatal exposure to 

or intake of OCS oil- and gas-related contaminants or discarded debris) and not impact the GOM sea 

turtle population as a whole. However, as discussed in Appendix A, a low-probability, large-scale 
4-50 Western Planning Area Lease Sale 248 Supplemental EIS

catastrophic event, which is not reasonably foreseeable and not part of the WPA proposed action, could 

have population-level effects on sea turtles. The net result of any disturbance depends upon the size and 

percentage of the population likely to be affected, the ecological importance of the disturbed area, the 

environmental and biological parameters that influence an animal’s sensitivity to disturbance and stress, 

or the accommodation time in response to prolonged disturbance (Geraci and St. Aubin, 1980). 

Non-OCS oil- and gas-related activities that may affect sea turtle populations include noise related to 

vessels (including commercial shipping and research vessels) and State drilling operations, military 

operations, commercial and recreational fishing, pollution, historic overexploitation (which led to listing 

of the species), coastal infrastructure and habitat loss, dredging, vessel strikes, pathogens, increased 

runoff, and natural phenomena. Direct population effects are due to mortality, and indirect effects can be 

from failed reproduction, inability to nest, or weakened immunity due to stress. 

The effects of the WPA proposed action, when viewed in light of the effects associated with other 

past, present, and reasonably foreseeable future OCS oil- and gas-related activities, may result in more 

significant impacts to sea turtles than before the Deepwater Horizon explosion, oil spill, and response; 

however, the magnitude of those effects cannot yet be determined. Nonetheless, despite the lack of 

information, BOEM is able to make a reasoned choice among alternatives because operators are required 

to follow all applicable lease stipulations and regulations, as clarified by NTLs, to minimize these 

potential interactions and impacts. The operator’s reaffirmed compliance with NTL 2012-JOINT-G01 

(“Vessel-Strike Avoidance and Injured/Dead Protected Species Reporting”) and NTL 2012-BSEE-G01 

(“Marine Trash and Debris Awareness Elimination”), as well as the limited scope, timing, and geographic 

location of the WPA proposed action, would result in negligible effects from the proposed drilling 

activities on sea turtles. In addition, NTL 2012-JOINT-G02, “Implementation of Seismic Survey 

Mitigation Measures and Protected Species Observer Program,” minimizes the potential of harm from 

seismic operations to sea turtles. These mitigations include onboard observers, airgun shut-downs for 

whales in the exclusion zone, ramp-up procedures, the use of a minimum sound source, and delayed use 

of explosives when turtles are observed in the exclusion zone. No significant cumulative impacts to sea 

turtles would be expected as a result of the WPA proposed action. The potential for impacts is mainly 

focused on the individual, and population-level impacts are not anticipated. The incremental contribution 

of the WPA proposed action would not be likely to result in a significant increase of impacts to sea turtles 

within the WPA; in comparison, non-OCS oil- and gas-related activities, such as overexploitation, 

commercial fishing, and pollution, have historically proved to be a greater threat to sea turtles. Even 

when taking into consideration the potential effects of the Deepwater Horizon explosion, oil spill, and 

response and the minimization of impacts through lease stipulations and regulations, no significant 

cumulative impacts to sea turtles would be expected as a result of the proposed exploration activities 

when added to the impacts of past, present, or reasonably foreseeable oil and gas development in the area, 

as well as other ongoing activities in the area.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of Internet information sources (NOAA’s and FWS’s websites, Gulf of Mexico coastal State 

government websites, and the RestoreTheGulf.gov website), as well as recently published, peer-reviewed 

journal articles was conducted to determine the availability of recent information on sea turtles. New 

information for the affected environment was discovered, including information on sea turtle strandings 

and nests.

The NMFS and FWS have proposed a rule (80 FR 15271; Docket No. 120425024-5022-02) to 

remove the current range-wide listing for green sea turtles and to replace it with eight Distinct Population 

Segments (DPSs) as threatened and three as endangered; to include application of existing protective 

regulations to the DPSs. Green sea turtles found in the GOM are part of the North Atlantic DPS, which 

includes the Florida breeding population. The North Atlantic DPS is proposed for listing as threatened 

(Federal Register, 2015c).

Stranding and nest data are used by scientists to estimate overall populations in the GOM and can be 

used to examine general population trends over time. In 2013 and 2014, loggerhead sea turtle nest counts 

on Florida’s beaches were close to the average of the previous 5 years, totaling 77,975 and 86,870 nests 

(9,952 and 11,050 west coast), respectively (State of Florida, Fish and Wildlife Conservation 
Description of the Environment and Impact Analysis 4-51

Commission, 2015a). Green sea turtle nest counts have increased exponentially from 267 nests in 1989 to 

25,553 nests (207 west coast) in 2013 on Florida index beaches, peaking in 2013. Green nesting patterns 

show biennial fluctuation and, therefore, were lower in 2014, totaling 5,895 nests (73 west coast). 

Leatherback nests in 2013 were recorded on beaches in Florida, totaling 896 nests all on the east coast 

(State of Florida, Fish and Wildlife Conservation Commission, 2014a). Similar to the nest counts for 

green turtles, leatherback nest counts have been increasing exponentially on Florida index beaches (State 

of Florida, Fish and Wildlife Conservation Commission, 2014b), with a record high of 641 nests on index 

beaches in 2014 (State of Florida, Fish and Wildlife Conservation Commission, 2015b). The Alabama 

Gulf Coast turtle nesting in 2012 was a success with a record-breaking 149 nests and in 2013, there was a 

total of 81 nests (Share the Beach, 2014a). The 2013 Share the Beach season along the Alabama coastline 

resulted in a total of 8,265 eggs in the sand with over 4,950 hatchlings entering the Gulf of Mexico. As of 

April 7, 2015, 80 nests were identified for the 2014 Alabama nesting season; however, there were some 

late nests found at several locations, so the season was extended until October 2014 and those data are not 

yet available (Share the Beach, 2015). The Texas coastline had a documented 153 Kemp’s ridley, 

13 loggerhead, and 15 green sea turtle nests in 2013 (Shaver, official communication, 2014). In 2014, 

119 Kemp’s ridley and 2 loggerhead nests were documented (data are still preliminary) (USDOI, NPS, 

2015). 

The new information presented in this chapter provides additional details on the baseline affected 

environment for sea turtles and does not change BOEM’s conclusions about the potential effects of a 

WPA proposed action on sea turtles. 

Incomplete or Unavailable Information 

After evaluating the information above, BOEM has determined that the new information does not 

change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. As discussed above, as well as in Chapter 4.2.1.12 of the prior 

2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete information regarding impacts of the 

Deepwater Horizon explosion, oil spill, and response on sea turtles in the WPA. BOEM used existing 

information and reasonably accepted scientific methodologies to extrapolate from available information 

in completing the relevant analysis of potential oil exposure impacts to sea turtles using studies 

investigating evidence of oil and impacts stemming from exposure to oil (Witham, 1978; Vargo et al., 

1986; Lutz and Lutcavage, 1989; Lutcavage et al., 1995; Plotkin and Amos, 1988). In addition, BOEM 

used information published on sea turtle nests and strandings to draw conclusions about sea turtle 

populations following the Deepwater Horizon explosion, oil spill, and response (USDOC, NMFS, 2014c 

and 2014d; State of Florida, Fish and Wildlife Conservation Commission, 2014b; Share the Beach, 2014a 

and 2014b). Unavailable information on the effects to sea turtles from the Deepwater Horizon explosion, 

oil spill, and response (and thus changes to the sea turtle baseline in the affected environment) makes an 

understanding of the cumulative effects less clear. A large body of information is being developed 

though the NRDA process, but it is not yet available. Relevant data on the status of sea turtle populations 

after the Deepwater Horizon explosion, oil spill, and response and increased sea turtle GOM strandings 

may take years to acquire and analyze, and impacts from the Deepwater Horizon explosion, oil spill, and 

response may be difficult or impossible to discern from other factors. BOEM used existing information 

and reasonably accepted scientific methodologies to extrapolate from available information on sea turtle 

nests and strandings in completing the relevant analysis of sea turtle populations. None of these sources 

reveals reasonably foreseeable significant adverse impacts. Therefore, although BOEM concludes that 

the unavailable information from these events may be relevant to foreseeable significant adverse impacts 

to sea turtles because the full extent of impacts on sea turtles is not known, BOEM nevertheless has 

determined that the information is not essential to a reasoned choice among alternatives for this 

Supplemental EIS (including the No Action and Action alternatives) for the two main reasons listed 

below: 

(1) The WPA is an active oil and gas region with ongoing (or the potential for) 

exploration, drilling, and production activities. In addition, non-OCS oil- and gasrelated activities will continue to occur in the WPA irrespective of the WPA 

proposed action (i.e., fishing, military activities, scientific research, and shoreline 

development). The potential for effects from changes to the affected environment 
4-52 Western Planning Area Lease Sale 248 Supplemental EIS

(post-Deepwater Horizon), routine activities, accidental spills (including lowprobability catastrophic spills), and cumulative effects remains whether or not the No 

Action or an Action alternative is chosen under this Supplemental EIS. Impacts on 

sea turtles from either smaller accidental events or low-probability catastrophic 

events will remain the same.

(2) All wide-ranging populations of sea turtles that may occur in the WPA and within 

areas affected by the spill are unlikely to have experienced population-level effects 

from the Deepwater Horizon explosion, oil spill, and response given their wideranging distribution and behaviors. 

Summary and Conclusion

BOEM has reexamined the analysis for sea turtles presented in the prior 2012-2017 Gulf of Mexico 

EISs based on the additional information presented above. No new information was discovered that 

would alter the impact conclusion for sea turtles presented in the prior 2012-2017 Gulf of Mexico EISs. 

The analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248. 

4.1.1.13.Diamondback Terrapins

BOEM has reexamined the analysis for the Texas diamondback terrapin (Malaclemys terrapin 

littoralis) and Mississippi diamondback terrapin (Malaclemys terrapin pileata) (referred to as 

diamondback terrapins in this Supplemental EIS) presented in the prior 2012-2017 Gulf of Mexico EISs 

based on the additional information presented below. No new information was discovered that would 

alter the impact conclusion for diamondback terrapins presented in the prior 2012-2017 Gulf of Mexico 

EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents still 

apply for proposed WPA Lease Sale 248. 

A detailed description of diamondback terrapins, along with the full analyses of the potential impacts 

of routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.13 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.13 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. BOEM has found no significant new information that 

has become available since those NEPA documents were published. 

The national and subnational conservation status rank of diamondback terrapins is “vulnerable,” or at 

a moderate risk of extirpation in the jurisdiction due to a fairly restricted range, relatively few populations 

or occurrences, recent and widespread declines, threats, or other factors. “Species of concern” is an 

informal term that refers to those species that might be in need of concentrated conservation actions. 

Such conservation actions vary depending on the health of the populations and the degree and types of 

threats. At one extreme, there may only need to be periodic monitoring of populations and threats to the 

species and its habitat. At the other extreme, a species may need to be listed as a federally threatened or 

endangered species under the Endangered Species Act. Species of concern receive no legal protection 

above those already afforded the species under other laws, and the use of the term does not necessarily 

mean that the species will eventually be proposed for listing as a threatened or endangered species. At the 

present time, the diamondback terrapin is neither a listed species nor a candidate for listing under the 

Endangered Species Act.

The following routine activities associated with proposed WPA Lease Sale 248 could potentially 

affect diamondback terrapins: ingestion of beach trash and debris generated by service vessels and OCS 

oil- and gas-related facilities; and injury from vessel traffic (boat propellers) with associated loss of 

habitat (coastal marsh) due to erosion. Adverse impacts due to routine activities resulting from the WPA 

proposed action are possible but unlikely. Because of the greatly improved handling of waste and trash 

by industry and because of the annual awareness training required by the marine debris mitigations, the 

plastics in the ocean are decreasing and the devastating effects on offshore and coastal marine life are 

minimized. Collisions with OCS oil- and gas-related vessel traffic is minimized by NTL 2012-JOINT-
Description of the Environment and Impact Analysis 4-53

G01, “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting,” which provides 

guidelines on monitoring procedures related to vessel strike avoidance measures. Erosion to marshes can 

be indirectly attributed to OCS oil- and gas-related service traffic and onshore development, but it is 

expected to cause little to no damage to the physical integrity, species diversity, or biological productivity 

of terrapin habitat. Due to the distance from shore, most OCS oil- and gas-related impacts are not 

expected to reach terrapins or their habitat. Impacts that may occur from routine OCS oil- and gas-related 

activities of the WPA proposed action are unlikely to have significant adverse effects on the size and 

recovery of any terrapin species or population in the Gulf of Mexico because most routine, OCS oil- and 

gas-related activities are expected to have sublethal effects. Sublethal effects such as behavioral effects, 

nonfatal exposure to or intake of OCS oil- and gas-related contaminants, or discarded debris may stress 

and/or weaken individuals of a local group or population and predispose them to infection from natural or 

anthropogenic sources. These effects are not expected to rise to the level of significance to the 

populations. 

Impact-producing factors associated with accidental events that may be associated with the WPA 

proposed action that could affect diamondback terrapins include offshore and coastal oil spills and spillresponse activities. Behavioral effects and nonfatal exposure to or intake of OCS oil- and gas-related 

contaminants may stress and/or weaken individuals of a local group or population and predispose them to 

infection from natural or anthropogenic sources. Even after oil is no longer visible, terrapins may still be 

exposed while they forage in the salt marshes lining the edges of estuaries where oil may have 

accumulated under sediments and within the food chain (Burger, 1994; Roosenburg et al., 1999). 

Reproductive success may be reduced if nests are disturbed or destroyed by cleanup efforts. Hatching 

success studies at various oiled nesting sites of the Northern diamondback terrapin suggest that spills may 

result in a reduction in nest size and increased mortality of spring emergers at the oiled sites (Wood and 

Hales, 2001). However, research on PAH exposure and toxicology of eggs in the vicinity of a spill site 

found no correlation to substrate PAHs when compared with egg toxicology. The level of PAHs found in 

eggs may be the result of maternal transfer and represent the exposure level of the nesting female rather 

than environmental exposure to PAHs from oil at the site of the nest (Holliday et al., 2008). Impacts on 

diamondback terrapins from smaller accidental events are likely to affect individual diamondback 

terrapins in the spill area, but they are unlikely to rise to the level of population effects (or a level of 

significance) given the probable size and scope of such spills. Further, the potential remains for smaller 

accidental spills to occur in the WPA proposed action area, regardless of any alternative selected under 

this Supplemental EIS, given that it is an active oil and gas region with either ongoing activities or the 

potential for exploration, drilling, and production activities. 

The major cumulative OCS oil- and gas-related impact-producing factors that may affect the 

diamondback terrapin include vessel traffic, exposure or intake of OCS oil- and gas-related contaminates 

or debris, and oil spills and spill response. To mitigate the potential impacts from OCS oil- and gasrelated activities, operators are required to follow all applicable lease stipulations and regulations, as 

clarified by NTLs, to minimize these potential interactions and impacts. The operator’s reaffirmed 

compliance with NTL 2012-BSEE-G01 (“Marine Trash and Debris Awareness and Elimination”) and 

NTL 2012-JOINT-G01 (“Vessel Strike Avoidance and Injured/Dead Protected Species Reporting”), as 

well as the limited scope, timing, and geographic location of the WPA proposed action, would result in 

minimal effects from the proposed drilling activities on diamondback terrapins. Most spills related to the 

WPA proposed action, as well as low-probability catastrophic spills (which are not part of the WPA 

proposed action and not likely expected to occur [refer to Appendix A for more information]) and oil 

spills stemming from tankering and prior and future lease sales, are not expected to contact terrapins or 

their habitats. Most routine and accidental, OCS oil- and gas-related activities are expected to have 

sublethal effects, such as behavioral effects, that are not expected to rise to the level of significance to the 

populations as a whole. Therefore, the incremental contribution of the WPA proposed action to 

cumulative impacts on terrapins is expected to be minimal.

Activities posing the greatest potential harm to terrapins are non-OCS oil- and gas-related factors, 

including habitat destruction, overharvesting and crab pot fishing, vessel traffic and road mortality, nest 

depredation, State oil- and gas-related activity, and natural processes. Spending most of their lives within 

their limited home ranges at the aquatic-terrestrial boundary in estuaries, terrapins are susceptible to 

habitat destruction (i.e., urban development, subsidence/sea-level rise, direct oil contact from non-OCS 

oil- and gas-related leasing program activities, and associated cleanup efforts). Habitat destruction, road 

construction, nest depredation, and drowning in crab traps are the most recent threats to diamondback 
4-54 Western Planning Area Lease Sale 248 Supplemental EIS

terrapins. In the 1800’s, populations declined due to overharvesting for meat (Hogan, 2003). Tropical 

storms, hurricanes, and beach erosion threaten their preferred nesting habitats. Characteristics of terrapin 

life history render this species especially vulnerable to overharvesting and habitat loss. These 

characteristics include low reproductive rates, low survivorship, limited population movements, and nest 

site fidelity year after year. Inshore oil spills from non-OCS oil- and gas-related sources are potential 

threats to terrapins in their brackish coastal marshes.

The incremental contribution of the WPA proposed action is expected to be minimal compared with 

non-OCS oil- and gas-related activities. The major impact-producing factors resulting from the 

cumulative activities associated with the WPA proposed action that may affect diamondback terrapins

include oil spills and spill-response activities, alteration and reduction of habitat, and consumption of 

trash and debris. Overall, within the WPA, there is a long-standing and well-developed OCS Program 

(more than 50 years); there are no data to suggest that activities from the preexisting OCS Programs are 

significantly impacting diamondback terrapin populations. Due to the extended distance from shore, 

impacts associated with activities occurring in the OCS Program are not expected to impact terrapins or 

their habitat. Non-OCS oil- and gas-related activities will continue to occur in the WPA irrespective of a 

proposed WPA lease sale (i.e., crabbing, fishing, military activities, scientific research, and shoreline 

development). Therefore, in light of the above analysis of the WPA proposed action and its impacts, the 

incremental effect of the WPA proposed action on diamondback terrapin populations is not expected to be 

significant when compared with historic and current non-OCS oil- and gas-related activities, such as 

habitat loss, overharvesting, crabbing, and fishing. 

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of Internet information sources (NOAA’s and FWS’s websites, and the RestoreTheGulf.gov 

website and NatureServe.org), as well as recently published journal articles was conducted to determine

the availability of recent information on diamondback terrapins. The search revealed no new information 

pertinent to this Supplemental EIS. No new information was found at this time that would alter the 

overall conclusions of the prior 2012-2017 Gulf of Mexico EISs that impacts on diamondback terrapins 

associated with the WPA proposed action are expected to be minimal.

Incomplete or Unavailable Information 

After evaluating the information above, BOEM has determined that the previous conclusions from the 

prior 2012-2017 Gulf of Mexico EISs are still valid because no new information on diamondback 

terrapins pertinent to the proposed action has been published since the publication of the prior 2012-2017 

Gulf of Mexico EISs; nevertheless, there is still incomplete or unavailable information on possible 

impacts to diamondback terrapins as a result of the Deepwater Horizon explosion, oil spill, and response.

Diamondback terrapins within the WPA were likely not affected to any discernible degree by the 

Deepwater Horizon explosion, oil spill, and response, based on the best available information and the 

WPA’s distance from the Macondo well. However, BOEM has identified incomplete information 

regarding impacts of the Deepwater Horizon explosion, oil spill, and response on diamondback terrapins 

in the WPA because little information about the Deepwater Horizon explosion, oil spill, and response has 

been released as of the publication of this Supplement EIS. Through the NRDA process, ongoing 

research and analysis of the presence of contaminants in terrapin eggs following the Deepwater Horizon

oil spill is being conducted (USDOC, NOAA, 2012), but the results are not yet available. Relevant data 

on the status of diamondback terrapin populations after the Deepwater Horizon explosion, oil spill, and 

response may take years to acquire and analyze, and impacts may be difficult or impossible to discern 

from other factors. This incomplete information may be relevant to evaluating adverse effects because

the full extent of potential impacts on terrapins is not known. In place of the missing information, BOEM 

used existing information and reasonably accepted scientific methodologies to extrapolate from available 

information in completing the relevant analysis, such as studies investigating evidence of oil and impacts 

stemming from exposure to oil (Burger, 1994; Roosenburg et al., 1999; Holliday et al., 2008, Wood and 

Hales, 2001). The results of these studies indicate that impacts resulting from the Deepwater Horizon oil 

spill have been largely indistinguishable from natural fluctuations or variability due to other 
Description of the Environment and Impact Analysis 4-55

anthropogenic activities. Although the body of available information is incomplete and long-term effects 

cannot yet be known, past analyses are not indicative of significant population-level responses. BOEM 

has thus determined that the incomplete or unavailable information is not essential to a reasoned choice 

among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for diamondback terrapins presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information presented above. No new information was 

discovered that would alter the impact conclusion for diamondback terrapins presented in the prior 2012-

2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA

documents still apply for proposed WPA Lease Sale 248. 

4.1.1.14.Coastal and Marine Birds

BOEM has reexamined the analysis for coastal and marine birds presented in the prior 2012-2017 

Gulf of Mexico EISs based on the additional information presented below. No new information was 

discovered that would alter the impact conclusion for coastal and marine birds presented in the prior 

2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in 

those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of coastal and marine birds, along with the full analyses of the potential 

impacts of routine activities, accidental events, and cumulative impacts that may be associated with the 

WPA proposed action, are presented in Chapter 4.1.1.14. of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.14 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has 

become available since those NEPA documents were published is presented below. 

The majority of the effects resulting from routine activities of the WPA proposed action (Tables 3-2 

through 3-4) on threatened or endangered (Table 4-1 of the WPA 233/CPA 231 Supplemental EIS) and 

nonthreatened and nonendangered coastal and marine birds are expected to be sublethal, primarily 

disturbance-related effects (Chapter 4.1.1.12.1 of the 2012-2017 WPA/CPA Multisale EIS). Major 

potential impact-producing factors resulting from routine activities for marine birds in the offshore 

environment include the following:

• habitat loss and fragmentation from coastal facility construction and development 

and pipeline landfalls (Fahrig, 1997 and 1998); 

• behavioral effects primarily due to disturbance from OCS helicopter and servicevessel traffic and associated noise (Habib et al., 2007; Bayne et al., 2008);

• mortality due to exposure and intake of OCS oil- and gas-related contaminants, e.g., 

produced waters (Wiese et al., 2001; Fraser et al., 2006);

• impacts from discarded debris (Robards et al., 1995);

• sublethal, chronic effects from air emissions (Newman, 1979; Newman and 

Schreiber, 1988); and 

• mortality and energetic costs associated with structure presence and associated light 

(Russell, 2005; Montevecchi, 2006). 

The major impact-producing factors resulting from the accidental events associated with the WPA 

proposed action that may affect the coastal and marine birds include oil spills, regardless of size, and oilspill cleanup activities, including the release of rehabilitated birds. Oil spills (and disturbance impacts 

associated with cleanup activities) have the greatest impact on coastal and marine birds. Sometimes, the 

rehabilitation of birds may have benefits beyond wild bird condition because of veterinary care that wild 
4-56 Western Planning Area Lease Sale 248 Supplemental EIS

birds do not receive. However, the handling of birds during rehabilitation may sometimes stress birds. 

Depending on the timing and location of the spill, even small spills can result in major avian mortality 

events (Piatt et al., 1990a and 1990b; Castège et al., 2007; Wilhelm et al., 2007). Small amounts of oil 

can affect birds, and mortality from oil spills is often related to numerous symptoms of toxicity (Burger 

and Gochfeld, 2001; Albers, 2006). Data from actual spills strongly suggest that impacts to a bird 

species’ food supply are typically delayed after initial impacts from direct oiling (e.g., Esler et al., 2002; 

Velando et al., 2005; Zabala et al., 2010). Sublethal, long-term effects of oil on birds have previously 

been documented (Esler et al., 2000; Alonso-Alvarez et al., 2007), including changes to sexual signaling 

(Pérez et al., 2010). 

Oil-spill impacts on birds from the WPA proposed action are expected to be adverse, but not 

significant, given the number and relatively small size of spills expected over the 40-year life of the WPA 

proposed action (Table 3-12 of the 2012-2017 WPA/CPA Multisale EIS). Impacts of oil-spill cleanup 

from the WPA proposed action are also expected to be adverse, but not significant, and may be negligible 

depending on the scope and scale of efforts.

Cumulative impacts to coastal and marine birds include both OCS oil- and gas-related and non-OCS 

oil- and gas-related activities. The OCS oil- and gas-related cumulative impact-producing factors that 

could potentially impact coastal and marine birds include the following: 

• air pollution;

• pollution of coastal and offshore waters resulting from OCS oil- and gas-related 

activities, including platform and pipeline oil spills, produced waters, and any spillresponse activities;

• structure presence and lighting (e.g., OCS platforms);

• aircraft and vessel traffic and oil-spill cleanup associated noise and disturbance 

impacts, including OCS helicopter and service-vessels;

• habitat loss, alteration, and fragmentation resulting from coastal facility construction 

and development; 

• habitat loss from OCS pipeline landfalls; and 

• trash and debris.

The incremental contribution of the WPA proposed action to the cumulative impact is considered 

adverse but not significant because the effects of the most probable impacts, such as lease sale-related 

operational discharges, air pollution, or trash and debris and helicopter and service-vessel noise and 

traffic, are expected to be sublethal; and some displacement of local individuals or flocks to other habitat 

may occur, if habitat is available. Overall carrying capacity may be reduced temporarily or permanently 

in habitats disturbed by OCS oil- and gas-related activities. These activities produce a net effect of 

habitat loss from oil spills, OCS pipeline landfalls, and maintenance and use of navigation waterways, as 

well as habitat loss and modification resulting from coastal facility construction and development. 

Nocturnal circulation events at platforms due to platform lighting have unknown impacts on migrating 

bird populations. Offshore oil and gas platform-related avian mortality, though representing an additional 

source of human-induced mortality, represents a small fraction compared with other sources of humaninduced mortality (Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS). Impacts may occur to coastal 

and marine birds from a low-probability catastrophic oil spill; however, this is not part of the WPA 

proposed action and not likely to occur. For additional information on a low-probability catastrophic 

spill, refer to Appendix A. 

Non-OCS oil- and gas-related cumulative impact-producing factors that could potentially impact 

coastal and marine birds include the following:

• air pollution;

• pollution of coastal waters resulting from municipal, industrial, and agricultural 

runoff and discharge; 
Description of the Environment and Impact Analysis 4-57

• tanker oil spills and spills related to oil and gas activities in State coastal waters and 

any spill-response activities;

• aircraft and military activities, including jet training overflights and sonic booms;

• nonconsumptive recreation, including bird-watching activities, all-terrain vehicle use, 

walking and jogging with pets, and other beach use;

• maintenance and use of navigation waterways;

• habitat loss, alteration, and fragmentation associated with commercial and residential 

development; 

• collisions of coastal and marine birds with various anthropogenic structures (e.g., 

buildings, power lines, cell phone towers, etc.); 

• diseases;

• climate change and related impacts, including sea-level rise;

• storms and floods;

• fisheries interactions;

• predation; 

• hunting; 

• trash and debris; 

• renewable energy; and 

• alternate use conversion. 

Impacts from non-OCS oil- and gas-related resources (including impacts from the State oil and gas 

program and associated structure collisions and spills, waste and debris, water pollution, and air pollution) 

on habitat and bird behavior operate in a way similar to the OCS oil- and gas-related impacts on each 

resource discussed previously in this chapter. Avian habitat loss, alteration, and fragmentation associated 

with commercial and residential development, and maintenance and use of navigation waterways is 

almost certainly occurring at a much faster pace and on a spatial scale far exceeding that compared with 

OCS oil- and gas-related activities, especially when compiled with the associated effects of climate 

change (including sea-level rise and the frequency and intensity of tropical storms). Overall mortality 

caused by collision with tall buildings is considerable (Drewitt and Langston, 2008), and window strikes 

may be the greatest cause of anthropogenic mortality in the United States (Table 4-7 of the 2012-2017 

WPA/CPA Multisale EIS), at least an order of magnitude greater than strikes with wind turbines, 

communication towers, tall buildings, and power lines (excluding distribution lines to residences and 

businesses) (Klem, 2009; Manville, 2005 and 2009). Mortality as a result of long migrations may also 

impact coastal and marine bird populations. Various passerine forest birds include a substantial migration 

(approximately tens of kilometers; Gauthreaux, 1975) over land at the end of their spring nonstop transGulf flight. Such a flight over land may also occur before crossing the Gulf itself. The mortality rates of 

species during nonstop flight due to exhaustion of energy reserves are unknown. However, the overall 

greatest mortality to birds (anthropogenic and non-anthropogenic) is considered predation by house cats 

(Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS). House cat predation is a threat mostly for 

passerines, which comprise most of the trans-Gulf migrants. Despite the number of waterfowl killed 

annually under Federal hunting laws, their populations remain strong. Sublethal effects on birds may also 

include interactions with commercial fisheries and noise disturbance from non-OCS oil- and gas-related 

air and vessel traffic.

A myriad of different anthropogenic (both OCS oil- and gas-related and non-OCS oil- and gasrelated) and natural (e.g., disease, predation, exhaustion, and weather) mortality factors (Table 4-7 of the 

2012-2017 WPA/CPA Multisale EIS) can negatively affect individuals of populations comprising the 

seven avian species groups found in the Gulf of Mexico (Tables 4-9, 4-10, and 4-11 of the 2012-2017 
4-58 Western Planning Area Lease Sale 248 Supplemental EIS

WPA/CPA Multisale EIS). Of the OCS oil- and gas-related activities identified previously (Chapters 

4.1.1.14.2 and 4.1.1.14.3 of the 2012-2017 WPA/CPA Multisale EIS), several are relevant to the 

discussion of their potential cumulative effects: habitat loss, alteration, or fragmentation; disturbancerelated effects (e.g., support vessels and helicopters); attraction to and collision with offshore platforms; 

nocturnal circulation (night flights) around them and the potential associated energetic demands; 

discharge of produced waters; oil spills; and chronic oil pollution. All but the latter two factors are 

associated with routine OCS oil- and gas-related activities. However, the incremental contribution of the 

WPA proposed action to the cumulative impact is considered adverse but not significant because the

effects of the most probable impacts, such as lease sale-related operational discharges and helicopters and 

service-vessel noise and traffic, are expected to be sublethal, and some displacement of local individuals 

or flocks may occur to other habitat, if habitat is available. Collision mortality has been estimated at 

200,000-321,000 bird deaths/year over the entire platform archipelago, but offshore oil and gas platformrelated avian mortality, though representing an additional source of human-induced mortality, represents a 

small fraction compared with other sources of human-induced mortality. Of the various factors to 

consider for avian resources in the GOM associated with climate change (Møller et al., 2004; North 

American Bird Conservation Initiative, 2010), the factor with the greatest potential net negative impact, at 

least for the coastal breeding avian assemblage, would be sea-level rise (Galbraith et al., 2002; Erwin 

et al., 2006). Saltmarsh obligate species are extremely sensitive to loss of saltmarsh habitat from sealevel rise. Routine impacts, accidental impacts, and the incremental contribution of the WPA proposed 

action to the cumulative impact (which is considered in comparison with the impacts of non-OCS oil- and 

gas-related factors) is considered adverse but not significant.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A broad Internet search for relevant new information was performed. These include nonprofit 

organizations, consortias, and administrators of funds that are penalties resulting from the Deepwater

Horizon explosion, oil spill, and response. Environmental journal articles were also located online using 

three search engines and the websites of six major journal publishers. New information was found for the 

affected environment regarding maximizing wetland coastal habitat.

A search of Internet information sources, including published journal articles, was conducted to 

determine the availability of recent information on coastal and marine birds. Internet websites visited 

included 4 Federal agencies (USEPA, USGS, NOAA [including Deepwater Horizon Bibliography], and 

BOEM); 12 State agencies (Texas Commission on Environmental Quality; Texas Parks and Wildlife 

Department; Louisiana Department of Wildlife and Fisheries; Louisiana Department of Natural 

Resources; Louisiana Department of Environmental Quality; Mississippi Department of Environmental 

Quality; Mississippi Department of Wildlife, Fisheries, and Parks; Alabama Department of Conservation 

and Natural Resources; Alabama Department of Environmental Management; Alabama Wildlife and 

Freshwater Fisheries Division; Florida Department of Environmental Protection; and Florida Fish and 

Wildlife Conservation Commission); 5 coastal universities or universities with coastal divisions 

(University of Louisiana at Lafayette, Louisiana State University, Texas A&M University, University of 

Texas at Austin Marine Science Institute College of Natural Sciences, and Florida State University); 

several various stakeholders (Sierra Club, National Fish and Wildlife Foundation, Nature Conservancy, 

Gulf of Mexico Alliance, Gulf of Mexico Program, Barataria-Terrebonne National Estuary Program, 

National Audubon Society, Gulf Coast Ecosystem Task Force, and Gulf Coast Ecosystem Restoration 

Council), and Louisiana Universities Marine Consortium (Effects of Offshore Oil and Gas Development: 

A Current Awareness Bibliography). Where applicable, websites of subdivisions of many of these 

organizations were also consulted. Environmental journal articles were also located online using four 

search engines (JSTOR, EBSCO, Google Advanced Scholar Search, and Google Advanced Book Search). 

Three of the search engines collectively searched all of the ecology journals of six major publishers (John 

Wiley and Sons, Springer, Elsevier Science, Taylor and Francis Group, Cambridge University Press, and 

Oxford University Press). The search resulted in new information on the mortality of coastal and marine 

birds due to the Deepwater Horizon explosion, oil spill, and response. 

Total seabird mortality from the Deepwater Horizon explosion, oil spill, and response is useful 

knowledge because it gives an indication of baseline shift in population sizes. Total seabird mortality 
Description of the Environment and Impact Analysis 4-59

(not a per annum estimate but instead accounting for all bird deaths) seaward of 40 km (25 mi) from shore 

due to the Deepwater Horizon explosion, oil spill, and response was estimated at 200,000 birds (Haney 

et al., 2014a). Estimates of breeding population sizes for eight of the analyzed species were 

60,000-15,000,000 for four procellariiforms; 9,000 for one pelecaniform; and 96,000-500,000 for three 

charadriiforms (Haney et al., 2014a). Broad ranges for these species make the total seabird mortality 

estimate look either high or low. Total bird mortality (not a per annum estimate but instead accounting 

for all bird deaths) shoreward of 40 km (25 mi) from shore was estimated by two models, culminating in 

estimates of 600,000 birds using one model and 800,000 birds using the other (Haney et al., 2014b). In 

perspective, in three analyzed species of seabirds, estimated losses due to the Deepwater Horizon

explosion, oil spill, and response were 12 percent or more of the total population estimated present in the 

northern Gulf of Mexico (Haney et al., 2014b). The 40-km (25-mi) boundary was chosen for several 

reasons (Haney et al., 2014a and 2014b), including its likelihood of being the maximum distance from 

shore inhabited routinely by coastal seabirds. This new information estimates a small negative shift in 

baseline numbers due to the calculated mortality of hundreds of thousands of Gulf of Mexico seabirds 

after the Deepwater Horizon explosion, oil spill, and response. No data are yet available on any recovery 

since the analysis by Haney et al. (2014a and 2014b), but the initial negative shift was insufficient to 

cause a change in the expected impacts to seabirds from proposed WPA Lease Sale 248.

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is 

still incomplete or unavailable information. As discussed above, as well as in Chapter 4.1.1.14 of the 

prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete information on avian mortality 

rates during migration, from both exhaustion and collisions with platforms. Various passerine forest birds 

include a substantial migration (approximately tens of kilometers; Gauthreaux, 1975) over land at the end 

of their spring nonstop trans-Gulf flight. Such a flight over land may also occur before crossing the Gulf 

itself unless substantial forests are located near the shoreline. The mortality rates of species during 

nonstop flight due to exhaustion of energy reserves are unknown. This information may be relevant to the 

evaluation of adverse impacts from OCS oil- and gas-related activities because, at the present time, there 

is no way to discern if annual or long-term mortality from such activities, due mostly to collisions with 

platforms (over the life of newly installed platforms) for any of the affected trans-Gulf migrant species 

considered herein results in major population-level impacts (Russell, 2005, Chapters 17 and 18). Annual 

mortality may cause major impacts because it has been estimated at 200,000 (Russell, 2005). However, 

in lieu of this data gap, BOEM extrapolated existing information using accepted scientific methodologies 

to complete this analysis. Studies indicate that the numbers of birds successfully migrating across the 

Gulf in spring are so great (on the order of magnitude of hundreds of millions; Russell, 2005) that any 

mortality associated with exhaustion from migration or collision with platforms would likely not 

exacerbate any cumulative impacts of other mortality factors. Birds suffering from exhaustion would 

typically be sick or weak, and their mortality would be a case of natural selection where the populations 

would be strengthened (made more fit). The potential range of a bird adapted to fatten up enough to cross 

extensive barriers like the open ocean or Gulf of Mexico may be approximated by data on shorebirds, 

which may be an accurate proxy for the maximum possible flight range of forest songbirds that may 

traverse the GOM. The computed maximum nonstop range of a bar-tailed godwit leaving Alaska (based 

on a model of fuel load) was all the way to the South Pole (Pennycuick and Battley, 2003). Given what 

we know about the life history characteristics of many of these species (e.g., age at first reproduction, 

clutch size, and nest success), as well as the estimate of maximum nonstop flight range, the potential for 

such major population-level impacts as a result of migration mortality seems relatively low (Arnold and 

Zink, 2011, page 2). Additionally, the focus within this Supplemental EIS is on major (population- and 

ecosystem-level) impacts to bird management, protection, and conservation, as well as ecoregions and 

landscapes over the long term rather than impacts to individual birds and small sites over a short time. 

Therefore, although the body of available information on migratory mortality is incomplete and long-term 

effects are unknown, the evidence currently available supports past analyses. The evidence does not 

indicate severe adverse impacts to coastal and marine bird populations as a result of migration mortality 

from collisions with platforms. Therefore, BOEM has determined that the incomplete information is not 

essential to a reasoned choice among alternatives.
4-60 Western Planning Area Lease Sale 248 Supplemental EIS

Summary and Conclusion

BOEM has reexamined the analysis for coastal and marine birds presented in the prior 2012-2017 

Gulf of Mexico EISs based on the additional information provided above. No new information was 

discovered that would alter the impact conclusion for coastal and marine birds presented in the prior 

2012-2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA

documents still apply for proposed WPA Lease Sale 248. 

4.1.1.15.Fish Resources and Essential Fish Habitat

BOEM has reexamined the analysis for fish resources and essential fish habitat (EFH) presented in 

the prior 2012-2017 Gulf of Mexico EISs based on the additional information presented below. No new 

information was discovered that would alter the impact conclusion for fish resources and EFH presented 

in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and 

updated in those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of fish resources and EFH, along with the full analyses of the potential impacts 

of routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

can be found in Chapter 4.1.1.15 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.15 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. Also, EFH is discussed in various chapters of 

this Supplemental EIS, including water quality (Chapters 4.1.1.2.1 and 4.1.1.2.2), wetlands (Chapter 

4.1.1.4), seagrass communities (Chapter 4.1.1.5), topographic features (Chapter 4.1.1.6), Sargassum

communities (Chapter 4.1.1.7), chemosynthetic deepwater benthic communities (Chapter 4.1.1.8), 

nonchemosynthetic deepwater benthic communities (Chapter 4.1.1.9), and soft bottom benthic 

communities (Chapter 4.1.1.10). An additional analysis of reasonably foreseeable cumulative impacts 

can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. The following information is a 

summary of the resource description and impact analysis incorporated from the prior 2012-2017 Gulf of 

Mexico EISs. Any new information that has become available since those NEPA documents were 

published is presented below. 

Effects on fish resources and EFH from routine oil and gas activities associated with the WPA 

proposed action could result in coastal and marine environmental degradation as a result of construction 

activities (onshore facilities to well-site construction activities, including board roads, ring levees, and 

impoundments), pipeline trenching, offshore discharges of drilling muds and produced waters, anchor and 

anchor chain placement, and structure emplacement and removal. The OCS oil- and gas-related activities 

(e.g., anchoring and using anchor chains) could physically destroy live bottom fish habitat, but alternately 

the emplacement of structures and artificial reefs can have a positive effect by providing habitat and/or 

food for reef fishes. Explosive structure removals can be detrimental to fish because blasts can kill or 

injure fish in close proximity. The removal of the structures would eliminate habitat in areas where 

natural hard bottom is rare, except when decommissioned platforms are used as artificial reef material. 

This practice is expected to increase over time. A more detailed discussion of decommissioning and the 

impacts of these activities on marine fishes can be found in Chapters 3.1.1.10 and 4.1.1.16 of the 2012-

2017 WPA/CPA Multisale EIS, respectively. Environmental degradation may also result from turbidity 

associated with pipeline emplacement. With the number of pipelines estimated for the OCS Program 

(0-1), sediment would potentially be resuspended in the localized areas. Discharges from OCS oil- and 

gas-related activities, such as drill mud and produced water, also have an incremental effect on offshore 

water quality. 

Since the majority of economically important fish species within the WPA are estuary dependent, any 

modification of the coastal environment resulting from the WPA proposed action has the potential to 

adversely affect EFH and fish resources through the loss of nursery habitat or functional impairment of 

existing habitat through decreased water quality by vessel traffic and routine dredging (Chambers, 1992; 

Stroud, 1992). Although there is potential for coastal and marine environmental degradation from the 

WPA proposed action, any possible degradation would have little effect on fish resources or EFH because 

many of the offshore EFHs are protected under stipulations, regulations currently set in place, and caseby-case reviews of permit applications to prevent impacts to sensitive fish habitats. Bottom-disturbing 

activities (i.e., anchoring and structure emplacement) are mitigated by BOEM to prevent habitat loss, all 

discharges (drilling muds and produced waters) are regulated by USEPA or State agencies, and 
Description of the Environment and Impact Analysis 4-61

regulations enforced for structure removal help to prevent loss of fish habitat. Because of the mitigations, 

regulations, and permit reviews, the WPA proposed action is expected to result in a minimal decrease in 

fish resources and/or standing stocks or in EFH. 

Accidental events associated with the WPA proposed action that could impact fish resources and EFH

include oil and chemical spills. If oil or chemical spills due to the WPA proposed action were to occur in 

open waters of the OCS proximate to mobile adult finfish, the effects would likely be nonfatal and the 

extent of damage would be reduced because adult fish have the ability to move away from a spill, 

metabolize hydrocarbons, and excrete both metabolites and parent compounds. Fish and shellfish eggs 

and larvae would be unable to avoid spills, and early development stages may be at greater risk. Fish 

populations may be impacted by an oil spill, but they will be primarily affected if the oil reaches the 

coastal and estuarine areas because these are the most productive areas and because many species reside 

in estuaries for at least part of their life cycle or are dependent on the nutrients exported from the estuaries 

to the shelf region. Weathered crude oil has been shown in laboratory experiments and field research to 

cause a range of sublethal effects, including malformation, genetic damage, and physiological impairment 

in different life history stages of different fish species (Carls et al., 1999; Whitehead et al., 2011; 

Incardona, 2014). Oil can be lethal to fish, especially in larval and egg stages, depending on the time of 

the year that the event happened. The effect of oil spills that may be associated with the WPA proposed 

action on fish resources is expected to cause a minimal decrease in standing stocks of any population 

because the most common spill events would be small in scale and localized; therefore, they would affect 

generally only a small portion of fish populations. Historically, there have been no oil spills of any size in 

the GOM that have had a long-term impact on fishery populations. 

There are widespread anthropogenic and natural factors that impact EFH and fish populations in the 

GOM. These include OCS oil- and gas-related and non-OCS oil- and gas-related factors. The OCS oiland gas-related activities that could impact fish resources and EFH include construction, pipeline and 

structure emplacement, anchor and anchor chain placement, drilling and produced water discharges, 

structure removal, and oil spills. The routine OCS oil- and gas-related activities have the potential to 

impact fish and degrade EFH, but the activities would probably only have a minimal effect on fish 

resources and EFH because of the regulations, mitigations, and permit reviews that are applied for OCS 

oil- and gas-related activities. Oil spills, although considered rare events, can affect seagrass beds 

through physical oiling and destruction from oil spill cleanup. Low-probability catastrophic spills, which 

are not part of the WPA proposed action and not likely expected to occur, are analyzed in Appendix A. 

Overall, the incremental contribution of the impacts from OCS oil- and gas-related activities on fish 

populations and EFH is small due to regulations, mitigations, and permit reviews. 

Non-OCS oil- and gas-related factors that can impact fisheries and EFH include State oil and gas 

activity, inshore pollutants, dredging, coastal development, human population expansion, commercial and 

recreational fishing, overfishing, and natural phenomena. Inshore inputs of pollutants to estuaries from 

runoff and industry are contributors to wetland loss and degradation of water quality. Fish are known to 

avoid any area of adverse water quality, such as hypoxia (Wannamaker and Rice, 2000; Craig and 

Bosman, 2013). Canal dredging primarily accommodates commercial, residential, and recreational 

development, and increased population and commercial pressures on the Gulf Coast are also causing the 

expansion of ports and marinas. Resource management agencies, both State and Federal, set restrictions 

and issue permits in an effort to mitigate the effects of development projects and industry activities. The 

Federal and State governments are also funding research and coastal restoration projects; however, it may 

take decades of monitoring to ascertain the feasibility and the long-term effectiveness of these coastal 

restoration efforts.

Overfishing (including bycatch) has contributed to population effects seen with GOM fishes. The 

Magnuson-Stevens Fishery Conservation and Management Act and its amendments address sustainable 

fisheries and set guidelines for protecting marine resources and habitat from fishing- and nonfishingrelated activities. Under this Act, fisheries management plans, including limits on catch and fishing 

seasons, are developed and proposed by the regional fisheries management councils for approval and 

implementation by NMFS. State agencies regulate inshore fishing seasons and limits.

Some natural phenomena can impact fish resources and EFHs. Nearshore habitat can be affected 

through events such as severe storms and floods. These events can accelerate wetland loss or damage to 

oyster reef habitat. Offshore resources such as biologically sensitive underwater features may be 

damaged or buried by events like storms or turbidity flows, potentially affecting fish resources. 

Additionally, variability in spawning success and juvenile survival directly affect Gulf of Mexico fish 
4-62 Western Planning Area Lease Sale 248 Supplemental EIS

populations. These natural phenomena are all continual, integral elements of the ecosystem, and impacts 

attributed to these events are often exacerbated by anthropogenic activities.

While all of these events and activities cause some sort of effect on the different EFHs and fish 

resources, many anthropogenic inputs, including the WPA proposed action, are now monitored, regulated, 

and mitigated by the permitting agency or State. The WPA proposed action would add a minimal amount 

to the overall cumulative effects.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

Various printed and Internet sources (including NMFS databases, the GMFMC website, EBSCO, 

Elsevier, PLoS ONE, and BioOne) were examined to assess recent information regarding this resource, 

information that may be pertinent to the WPA. New information relevant to an analysis of the potential 

impacts of OCS oil- and gas-related activities on fishes has been published. The following studies 

provide additional information on the potential impacts associated with the Deepwater Horizon explosion, 

oil spill, and response, while reaffirming conclusions reached by earlier assessments.

Murawski et al. (2014) investigated the prevalence of external skin lesions on fishes in the northern 

GOM in 2011 and 2012, finding the rate of incidence decreased significantly over time. However, 

analyses indicated the prevalence of lesions correlated positively with concentrations of PAHs found in 

sampled fishes captured in the vicinity of the Macondo well. The marked decrease in incidence of skin 

lesions from 2011 to 2012 suggests that the occurrence of lesions was potentially influenced by acute 

exposure to oil; long-term effects are still unknown.

Following a review of available literature, Fodrie et al. (2014) suggested that a range of factors could 

be acting to obscure (i.e., spatiotemporal variability, fishery closures, and off-setting effects) or dampen 

(i.e., avoidance behavior, dilution, and compensatory processes) potential population-level effects to fish 

following the Deepwater Horizon explosion, oil spill, and response. In order for future assessments to 

better discern potential population-level impacts, the authors recommend that information be developed to 

address gaps in the following: long-term environmental baseline data; population level genomic, 

physiological and demographic responses; and early life-history and ecology of estuarine fishes (Fodrie 

et al., 2014). 

Incomplete or Unavailable Information 

As discussed in Chapter 4.2.1.15 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified

incomplete information regarding impacts of the Deepwater Horizon explosion, oil spill, and response on 

fish resources and EFH in the Gulf of Mexico. The below information updates or adds to the 

understanding of incomplete or unavailable information for this resource. A large body of information is 

being developed through the NRDA process and is not yet available. Few studies have been released 

showing impacts following the Deepwater Horizon explosion, oil spill, and response. This information 

cannot be obtained by BOEM because the overall costs are exorbitant. This incomplete information may 

be relevant to evaluating adverse effects because the full extent of potential impacts on fish resources and 

EFH are not known. BOEM thus used existing information and reasonably accepted scientific 

methodologies to extrapolate from available information in completing the relevant analysis such as 

studies investigating evidence of oil and impacts stemming from exposure to oil among pelagic fishes, 

coastal fishes, and marsh-associated nekton (Atlantic Bluefin Tuna Status Review Team, 2011; Fodrie 

and Heck, 2011; Soniat et al., 2011; Carmichael et al., 2012; Moody et al., 2013; Rooker et al., 2013; 

Fodrie et al., 2014). These references discuss the effects of PAHs on different species and life history 

stages of fishes, as well as population distributions and status. These references found that, following the 

Deepwater Horizon explosion, oil spill, and response, there were no short-term effects on species 

compositions in marsh fishes; oysters did not contain PAHs that would be passed to higher trophic levels; 

fish larvae, eggs, and adults were found throughout the GOM; and the populations status of bluefin tuna is 

still at a point where they do not need to be listed as threatened or endangered. However, Fodrie et al. 

(2014) suggested that a range of factors could be acting to obscure or dampen potential population-level 

effects, and these data gaps need to be addressed in order for future assessments to better discern potential 

population level impacts. Further, BOEM analyzed impacts based on the most conservative outcomes; 
Description of the Environment and Impact Analysis 4-63

therefore, while there are detailed studies regarding fish larvae and eggs and nonlethal impacts from 

PAHs, BOEM assumed lethal results if larvae and eggs contacted oil. The results of these recent studies 

of fish resources (species and communities) indicate impacts resulting from the Deepwater Horizon oil 

spill have been largely indistinguishable from natural fluctuations or variability due to other 

anthropogenic activities. Although the body of available information is incomplete and long-term effects 

cannot yet be known, these early results support past analyses and are not indicative of significant 

population-level responses.

Summary and Conclusion

BOEM has reexamined the analysis for fish resources and EFH presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information provided above. Various printed and Internet sources 

(including NMFS databases, the GMFMC website, EBSCO, Elsevier, PLoS ONE, and BioOne) were 

examined to assess recent information regarding this resource that may be pertinent to the WPA. No new 

information was discovered that would alter the impact conclusion for fish resources and EFH presented 

in the prior 2012-2017 Gulf of Mexico EISs. The analysis and potential impacts detailed in those NEPA

documents still apply for proposed WPA Lease Sale 248. 

4.1.1.16.Commercial Fisheries

BOEM has reexamined the analysis for commercial fisheries presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented below. No new information was discovered 

that would alter the impact conclusion for commercial fisheries presented in the prior 2012-2017 Gulf of 

Mexico EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents 

still apply for proposed WPA Lease Sale 248.

A detailed description of commercial fisheries, along with a full analysis of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action are 

presented in Chapter 4.1.1.16 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.16 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below. 

Impact-producing factors with the potential to affect commercial fisheries in the WPA include 

seafloor-disturbing activities (e.g., pipeline installation, infrastructure emplacement, and dredging); waste 

discharge (e.g., drilling muds, cuttings, and produced waters); explosive severance operations (e.g., 

decommissioning and structure removal); and space-use conflicts (e.g., seismic surveys and structure 

emplacement). Some of these factors have the potential to indirectly impact commercial fisheries through 

degradation or loss of habitat. Healthy fish stocks depend on EFH, which is defined in the Sustainable 

Fisheries Act as “those waters and substrate necessary to fish for spawning, breeding, feeding, and/or 

growth to maturity.” Since the majority of commercially harvested species within the WPA are estuarydependent, coastal environmental degradation resulting from the WPA proposed action has the potential 

to adversely affect EFH and commercially valuable fishes. However, analysis of routine oil and gas 

activities, such as pipeline trenching, maintenance dredging, canal construction, and OCS discharge of 

drilling muds and produced water, has identified only short-term localized disturbances that minimally 

impact commercially valuable fish species and associated EFH. Resuspended sediments and offshore 

discharges settle or dissipate rapidly, limiting both the area affected and the duration of the effect. 

Additionally, regulations, mitigations, and current practices reduce the undesirable effects of construction 

and operational activities on coastal and offshore habitats. At the expected level of impact, the resultant 

influence on fish resources would be indistinguishable from natural fluctuations and other anthropogenic 

influences.

Fish mortality as a result of decommissioning operations is an example of routine OCS oil- and gasrelated activities directly impacting fishes. However, a study of structure removals employing explosive 

severance methods found that associated mortality for three commercially important fishes did not 

significantly alter projected stocks (Gitschlag et al., 2000). To account for inherent variations in species 
4-64 Western Planning Area Lease Sale 248 Supplemental EIS

composition and abundance among platforms (e.g., Stanley and Wilson, 1997; Gitschlag et al., 2000; 

Stanley and Wilson, 2000; Wilson et al., 2003), mortality estimates were doubled and stock estimates 

were recalculated. Although the study was limited and cannot be directly applied to all species or 

habitats, it is reasonable to assume that other commercially important fishes could respond similarly. At 

the projected rate of removal, these activities are not expected to have a substantial negative impact on 

stocks of commercially important fishes or, by extension, the associated fisheries. 

Space-use conflicts could result directly from routine OCS oil- and gas-related activities that restrict 

or prevent other users from accessing OCS resources. For example, seismic surveys and structure 

emplacement represent short-term and semi-permanent obstructions, respectively. Although studies have 

shown that airguns can produce behavioral responses in fishes, possibly even resulting in species- or gearspecific effects on catch rate (Popper and Hastings, 2009; Fewtrell and McCauley, 2012; Lokkeborg 

et al., 2012), there is insufficient data to consistently predict responses and important variables, such as 

the duration of exposure and repeated exposure, have not been fully addressed. In addition, the current 

paradigm posits these structures act as both fish-attracting and production-enhancing devices, depending 

upon the species (Carr and Hixon, 1997; Gallaway et al., 2009; Shipp and Bortone, 2009). The resultant 

assemblages frequently include commercially valuable fishes, such as tunas (Thunnus spp.), red snapper 

(Lutjanus campechanus) and wahoo (Acanthocybium solanderi). Therefore, OCS structures may either 

enhance or obstruct commercial fishing, depending upon gear type (e.g., hydraulic reel, greenstick, trawl 

and long-line) and target species. Overall, the OCS structures present a minor space-use conflict when 

compared with the area available for commercial fishing.

Accidental OCS oil- and gas-related events that could impact commercial fisheries are very limited. 

Oil spills on the OCS that are >1 bbl due to the WPA proposed action are highly unlikely (Table 3-12 of 

the 2012-2017 WPA/CPA Multisale EIS). If oil spills due to the WPA proposed action were to occur in 

open waters of the OCS proximate to mobile adult finfish, the effects would likely be nonfatal, and the 

extent of damage would be reduced because adult fish have the ability to avoid adverse water conditions. 

This behavioral mechanism allows mobile fishes to move away from the source of the hydrocarbons, 

thereby minimizing exposure. Although larval and juvenile life stages are typically more vulnerable than 

adults, species-specific response, duration of exposure, and hydrocarbon concentration are critical factors 

in determining short- and long-term effects. If a spill were to occur in coastal waters, oil could potentially 

impact critical nursery habitat. However, the great majority of coastal spills would be very small, would 

require a shorter response time than more remote incidents, and would be expected to affect a highly 

localized area with low-level impacts. The probability of an offshore spill impacting nearshore 

environments is low, and spilled oil would generally be volatilized or dispersed by currents in the 

offshore environment prior to impacting inshore nursery habitat. The expected impact to populations of 

commercially important fishes is negligible.

The cumulative analysis considers activities that have occurred, are currently occurring, and could 

occur and adversely affect commercial fisheries by harming fishes and affecting landings, or the value of 

those landings, for the years 2012-2051. The OCS oil- and gas-related activities include the effects of the 

OCS Program (proposed action and prior and future OCS lease sales) resulting from pipeline installation, 

channel dredging, waste discharge, decommissioning operations, seismic surveys, structure emplacement, 

and oil spills. Some of these factors have the potential to indirectly impact commercial fisheries through 

degradation or loss of habitat. The impacts, however, are generally short-term localized disturbances that 

minimally impact commercially valuable fish species and associated EFH. In addition, regulations, 

mitigations, and current practices reduce the undesirable effects of construction and operational activities 

on coastal and offshore habitats. In recent years, decommissioning operations have exceeded structure 

emplacements, resulting in a decrease in the total number of OCS platforms. BOEM expects this trend to 

continue throughout the OCS Program years, further reducing the potential for impacts to commercial 

fisheries through space-use conflicts. Although the decommissioning process frequently employs 

explosive severance methods that result in localized mortality of fishes, the cumulative impact to 

commercially valuable stocks is expected to be indistinguishable from natural fluctuations and the effects 

of commercial and recreational fishing activity. Factors outside the scope of OCS oil- and gas-related 

activities include State oil and gas activity; wetland loss from coastal, commercial, residential, and 

agricultural development; levees; river channelization; pollution from runoff; natural phenomena; and 

commercial and recreational fishing. Wetland loss as a result of State oil and gas activity, land 

development, levees, and river channelization results in habitat loss for larval and juvenile fish, as well as 

contributing to the intrusion of saltwater into oyster-producing waters, increasing oyster mortality through 
Description of the Environment and Impact Analysis 4-65

disease and predation. Inshore inputs of pollutants to estuaries from runoff and industry are also 

contributors to wetland loss. Overfishing (including bycatch) has contributed to the decline of some 

populations of Gulf of Mexico commercial fish species. State and Federal agencies regulate fishing 

activity and many of the anthropogenic factors potentially impacting fish resources in the Gulf of Mexico. 

However, there are also natural factors that cannot be regulated, such as flooding, drought, extreme 

temperatures, and natural fluctuations in fish populations as a result of variability in spawning success and 

juvenile survival that may affect commercial fisheries. Overall, the commercial fish and shellfish 

populations have remained viable in the Gulf of Mexico even with ongoing anthropogenic and natural 

disturbances. An analysis of both OCS oil- and gas-related activities and non-OCS oil- and gas-related 

activities suggests that the non-OCS oil- and gas-related impacts have a greater impact on commercial 

fisheries than the OCS oil- and gas-related impacts.

Although some OCS oil- and gas-related activities contribute incrementally to the degradation and 

loss of wetland habitat (Chapter 4.1.1.4), the cumulative impact is small in comparison with the 

combined effect of habitat loss from State oil and gas activities, coastal development, and river 

channelization. The cumulative impact of OCS oil- and gas-related activities to commercial fisheries is 

negligible.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

BOEM has examined newly available information for findings that may impact the analyses of 

routine, accidental, and cumulative OCS oil- and gas-related activities and potentially alter previous 

conclusions. A search of Internet information sources and scientific journals was conducted to determine 

the availability of recent information (including NMFS databases, the NOAA Gulf Spill Restoration 

Publications website, the GMFMC website, Science Direct, EBSCO, Elsevier, PLoS ONE, JSTOR, and 

BioOne). Since publication of the prior 2012-2017 Gulf of Mexico EISs, new information relevant to an 

analysis of the potential impacts of OCS oil- and gas-related activities on commercial fisheries has been 

published. The following studies provide additional information on the potential impacts associated with 

the Deepwater Horizon explosion and oil spill, while reaffirming conclusions reached by earlier 

assessments.

Murawski et al. (2014) investigated the prevalence of external skin lesions on fishes in the northern 

GOM in 2011 and 2012, finding the rate of incidence decreased significantly over time. However, 

analyses indicated the prevalence of lesions correlated positively with concentrations of PAHs found in 

sampled fishes captured in the vicinity of the Macondo well. The marked decrease in incidence from 

2011 to 2012 suggests that the occurrence of lesions was potentially influenced by acute exposure to oil; 

the long-term effects are still unknown.

Following a review of available literature, Fodrie et al. (2014) suggested that a range of factors could 

be acting to obscure (i.e., spatiotemporal variability, fishery closures, and off-setting effects) or dampen 

(i.e., avoidance behavior, dilution, and compensatory processes) potential population level effects to fish 

following the Deepwater Horizon explosion, oil spill, and response. In order for future assessments to 

better discern potential population level impacts, Fodrie et al. (2014) recommend that information be 

developed to address gaps in the following: long-term environmental baseline data; population level 

genomic, physiological, and demographic responses; and early life-history and ecology of estuarine 

fishes.

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is 

still incomplete or unavailable information related to impacts to fishes resulting from explosive structure 

removal, seismic surveys, and exposure to oil, which are not fully addressed in the available literature. 

The information below updates or adds to the understanding of incomplete or unavailable information for 

this resource. In lieu of this missing information, BOEM used reasonably accepted scientific 

methodologies to extrapolate from existing information in completing this analysis and formulating the 

conclusions presented here, as discussed in the paragraphs below.
4-66 Western Planning Area Lease Sale 248 Supplemental EIS

Fish mortality resulting from explosive structure removal has not been studied across the entire range 

of water depths and environmental conditions in which these activities occur. However, as stated above, 

existing information (e.g., Gitschlag et al., 2000) is sufficient for the purpose of analyzing the potential 

impacts of anticipated decommissioning activities because studies have shown that the results of 

calculations on the impacts of decommissioning activities on fish did not significantly alter projected 

stocks. Specific responses by fishes to seismic survey activities cannot be predicted and are unknowable 

due to the many possible interactions among variables (e.g., species, environmental conditions, exposure 

history and duration, spawning status, presence of prey or predators, etc.) that could influence the 

response to sound. However, available information (Popper and Hastings, 2009; Fewtrell and McCauley, 

2012; Lokkeborg et al., 2012) is sufficient, within the context of historical landings and with knowledge 

of anticipated survey frequency and distribution, to extrapolate an overall expectation of negligible impact 

from seismic survey activities to commercial fisheries. 

Finally, as noted above, a number of data gaps need to be addressed in order for future assessments to 

better discern potential population level impacts (Fodrie et al., 2014). However, this information cannot 

reasonably be obtained or may, in some cases, be unobtainable (e.g., past environmental baselines), and 

the overall costs in time and money to determine this are exorbitant. BOEM recognizes that the 

incomplete information with respect to long-term effects may be relevant to the evaluation of impacts on 

commercial fisheries and that, despite the current absence of detectable long-term effects, some impacts 

may not yet be detectable.

Although the body of available information is incomplete and long-term effects cannot yet be known, 

the evidence currently available and derived using accepted scientific methodologies supports past 

analyses and does not indicate severe adverse impacts to commercial fisheries. Therefore, BOEM has 

determined that the incomplete information is not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for commercial fisheries presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented above. The new information does not alter 

previous impact conclusions for commercial fisheries presented in the prior 2012-2017 Gulf of Mexico 

EISs. The analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248. 

4.1.1.17.Recreational Fishing

BOEM has reexamined the analysis for recreational fishing presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented below. No new information was discovered 

that would alter the impact conclusion for recreational fishing presented in the prior 2012-2017 Gulf of 

Mexico EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents 

still apply for proposed WPA Lease Sale 248.

A detailed description of recreational fishing, along with the full analyses of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action are 

presented in Chapter 4.1.1.17 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.17 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. New information that has become available since 

publication of those NEPA documents is also discussed below. 

Routine activities during the initial phases of the WPA proposed action, such as seismic surveying 

operations and other forms of vessel traffic, may lead to some minor space-use conflicts with recreational 

fishermen. Vessel traffic during subsequent infrastructure emplacement and production operations could 

also lead to some space-use conflicts with recreational fishing activities. The OCS oil- and gas-related 

activities could also affect the aesthetics of fishing in a particular location, which could dissuade anglers 

from fishing in specific locations. However, according to data provided by the Texas Parks and Wildlife 

Department, less than 2 percent of the annual recreational fishing effort occurs in waters of the Exclusive 
Description of the Environment and Impact Analysis 4-67

Economic Zone and the majority of recreational fishing targets species not closely associated with 

offshore oil and gas infrastructure (Fisher, official communication, 2014). 

Proposed WPA Lease Sale 248 may also lead to low-level environmental degradation of fish habitat 

(Chapter 4.1.1.15), e.g., construction activities and offshore discharges of drilling muds and produced 

waters, which could negatively impact recreational fishing activity. However, these minor negative 

effects would likely be outweighed by the beneficial role that oil platforms serve as artificial reefs for fish 

populations. The degree to which oil platforms will become a part of a particular State’s Rigs-to-Reefs 

program will be an important determinant of the degree to which the WPA proposed action may impact 

recreational fishing activity in the long term. As structures are scheduled for decommissioning, a higher 

level of a State’s participation in the Rigs-to-Reefs program may benefit fishermen through the retention 

of complex habitat and potentially enhanced production for some recreationally desirable species, 

although the extent to which structures have overall population effects is unclear. However, structure 

removals (particularly those employing explosive severance techniques) can negatively impact the 

recreational activity that depends on any particular platform. However, the vast majority of recreational 

fishing activity in the WPA occurs in non-Federal waters and thus would not be impacted by structure 

removals. In aggregate, the impacts of the WPA proposed action on recreational fishing activity are 

expected to be minor. 

Recreational fishing could also be impacted by accidental events, such as oil spills. Oil spills can 

arise from accidents with respect to vessels, pipelines, drilling operations, or production operations. An 

oil spill would likely lead to recreational fishing closures in the vicinity of the oil spill. Small-scale spills 

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

sites in neighboring regions. The longer-term effects of an oil spill will be determined by its effects on 

fish populations (Chapter 4.1.1.15), as well as by its effects on people and firms that support recreational 

fishing activity. For example, an oil spill could impact people’s perceptions of the aesthetics of 

recreational fishing in an area, which could impact tourism. However, the impacts of most spills that 

could arise from the WPA proposed action would be fairly small.

The cumulative analysis considers the effects of the impact-producing factors related to OCS oil- and 

gas-related activity, along with non-OCS oil- and gas-related impacts, that may occur and adversely affect 

recreational fishing in the same general area of the WPA proposed action. The impacts of proposed WPA 

Lease Sale 248 will contribute to the impacts of the broader OCS Program. This includes the space-use 

impacts arising from vessel traffic and construction operations, as well as the low-level environmental 

degradation to fish habitats that could occur. The proposed WPA lease sale will also incrementally add to 

the probabilities of oil spills, which could affect recreational fishing activity in the short term. Lowprobability catastrophic oil spills, which are not part of the WPA proposed action and not reasonably 

expected to occur, could also impact recreational fishing and are described in Appendix A. Proposed 

WPA Lease Sale 248 could also have positive impacts to recreational fishing activity since OCS 

platforms often attract recreationally valuable fishes, although only a small percentage of recreational 

fishing in Texas occurs in Federal waters. Although removal of platforms could have negative impacts on 

recreational fishing activity, these potentially negative effects could be partially offset by deployment of 

some platforms as artificial reef substrate within a State-approved artificial reef program.

Recreational fishing activity could also be influenced by a number of non-OCS oil- and gas-related 

factors, such as commercial, military, recreational, and industrial activities; natural processes; wetlands

loss; hypoxia events; fish kills; water quality degradation; fisheries management plans; hurricanes; State 

oil and gas activities; State artificial reef program; tourism (refer to Chapter 4.1.1.18); and other 

economic factors (refer to Chapter 4.1.1.20.3). Many of these impacts will be determined by the 

cumulative impacts to fish populations, which are discussed in Chapter 4.1.1.15. However, recreational 

fishing activity is driven by unique economic and tourism trends (refer to Chapters 4.1.1.18 and 

4.1.1.20.3). It can also be influenced by the quality of fishing grounds, such as wetland areas, which can 

be degraded by hurricanes. However, it is likely that Fisheries Management Plans of the Federal and 

State governments would serve to keep overall recreational fishing activity reasonably stable through 

time.

The WPA proposed action and the broader OCS Program have varied effects on recreational fishing

activity. The OCS Program has generally enhanced recreational fishing opportunities due to the role of 

oil platforms as artificial reefs. This effect is influenced by the decommissioning rate and the extent to 

which decommissioned platforms are redeployed as artificial reefs through participation in the States’ 

Rigs-to-Reefs programs. However, oil spills can have important negative consequences on recreational 
4-68 Western Planning Area Lease Sale 248 Supplemental EIS

fishing activity due to the resultant fishing closures and longer-term effects oil spills can have on fish 

populations. These are discrete and rare events, however, and recreational fishing activity is largely 

driven by broader economic and tourism trends. Recreational fishing activity is also influenced by a 

number of non-OCS oil- and gas-related activities, such as economic and tourism trends, the quality of 

fishing grounds, hurricanes, and Fisheries Management Plans of Federal and State governments. The 

incremental contribution of the WPA proposed action to these positive and negative cumulative effects 

would be minimal because of the relatively small amount of activity expected with the WPA proposed 

action. 

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

BOEM examined a variety of Internet sources, as well as known data providers, for new information 

regarding the impacts of the WPA proposed action on recreational fishing. The primary new data source 

is an annual update to recreational fishing data in Texas (Fisher, official communication, 2015), which 

provides information regarding the affected environment. This update provides data on both the species 

caught and the amount of angler effort in 2014 (the data for prior years are unchanged). Table 4-2

provides data on the number of recreational fishing trips in Texas bays, State waters, and the Exclusive 

Economic Zone during each season of 2009-2014. Texas has historically divided its data into two fishing 

seasons: Season A (November 21-May 14) and Season B (May 15-November 20). The number of angler 

trips decreased from 1,149,597 in 2013 to 1,069,125 in 2014. While there were declines in 2014 in most 

categories, the declines were most pronounced in Season A and in the Exclusive Economic Zone. 

Table 4-3 provides data regarding the individual species caught by anglers in Texas during 2009-2014. 

Panel A presents overall catch data in Texas, while Panels B, C, and D present catch data for Texas bays, 

State waters, and the Exclusive Economic Zone. Landings of all species except king mackerel declined 

from 2013 to 2014. The declines in landings were most pronounced for Atlantic croaker, sheepshead, and 

spotted seatrout.

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is 

still incomplete or unavailable information. The information below updates or adds to the understanding 

of incomplete or unavailable information for recreational fishing. As discussed in this Supplemental EIS, 

as well as in Chapter 4.1.1.17 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified 

incomplete or unavailable information related to recreational fishing. This information relates to the 

ultimate impacts of the Deepwater Horizon oil spill on fish populations that support recreational fishing 

activity. An analysis of this incomplete or unavailable information is presented in Chapter 4.1.1.18. As 

discussed in that chapter, this incomplete or unavailable information is being developed through the 

NRDA process and is not yet available. There is also uncertainty regarding the extent to which 

recreational fishing is dependent upon OCS platforms. BOEM is planning to undertake a study project to 

examine this issue, although the results from this study project will not be released in the timeline 

contemplated in the NEPA analysis of this Supplemental EIS. In lieu of this incomplete or unavailable 

information, BOEM used existing information and reasonably accepted scientific methodologies to 

extrapolate from available information in completing the relevant analysis as described above. For 

example, BOEM has used data on recreational fishing activity provided by the Texas Parks and Wildlife 

Department (Fisher, official communication, 2015) to examine trends in recreational fishing activity off 

Texas over time. BOEM does not expect the incomplete or unavailable information to significantly 

change its estimates of the impacts of the OCS Program on recreational fishing activity because BOEM 

still has enough baseline data to reasonably estimate impacts. Therefore, BOEM has determined that the 

incomplete or unavailable information is not essential to a reasoned choice among alternatives.
Description of the Environment and Impact Analysis 4-69

Summary and Conclusion

BOEM has reexamined the analysis for recreational fishing presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented above. No new information was discovered 

that would alter the impact conclusion for recreational fishing presented in the prior 2012-2017 Gulf of 

Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA documents still 

apply for proposed WPA Lease Sale 248. 

4.1.1.18.Recreational Resources

BOEM has reexamined the analysis for recreational resources presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information presented below. No new information was 

discovered that would alter the impact conclusion for recreational resources presented in the prior 2012-

2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in those 

NEPA documents still apply for proposed WPA Lease Sale 248. 

A detailed description of recreational resources, along with the full analyses of the potential impacts 

of routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.18 of the 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.18 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. New information that has become available since 

publication of those NEPA documents is presented below. 

Routine OCS oil- and gas-related activities in the WPA have the potential to directly and indirectly 

impact recreational resources along the coasts of Texas and Louisiana. Marine debris, OCS oil and gas 

vessel noise, and visible OCS oil- and gas-related infrastructure can noticeably affect the aesthetic value 

of coastal areas, particularly beaches. Additionally, OCS oil- and gas-related vessel traffic can cause 

space-use conflicts with recreational activities such as boating, and the presence of OCS oil and gas 

platforms can enhance some recreational activities such as fishing and diving. Although, the long-term 

impacts of platforms depend on the nature of the decommissioning of the platform. The OCS oil- and 

gas-related activities can also change the composition of local economies through changes in 

employment, land use, and the demand for activities related to recreation and tourism. Despite these 

potential impacts, the small scale of the WPA proposed action relative to the scale of the existing OCS oil 

and gas industry suggests that the impacts on recreational resources are likely to be minimal.

Accidental spills most likely to result from the WPA proposed action will be small, of short duration, 

and not likely to impact Gulf Coast recreational resources. Should an oil spill occur and contact a beach 

area or other recreational resource, it will cause some disruption due to the physical oiling impact and 

cleanup phases of the spill. Beaches, nature parks, and wetland areas could be impacted during these 

phases of an oil spill. These disruptions could also have impacts on businesses and consumers that 

depend on the use of these resources. Media coverage and public perception regarding the extent of the 

oil damage can also influence the ultimate economic impacts of a spill (Chapter 4.1.1.20). However, all 

of these effects would likely be small in scale and of short duration.

The cumulative analysis considers the effects of impact-producing factors related to OCS oil- and 

gas-related activity along with non-OCS oil- and gas-related impacts of other commercial, military, 

offshore and coastal activities, and natural processes that may occur and adversely affect recreational 

resources in the same general area of the WPA proposed action.

The WPA proposed action would contribute to the aesthetic impacts and space-use conflicts that arise 

due to the broader OCS Program. This includes impacts from vessel traffic, marine debris, and the 

presence or absence of OCS infrastructure. Vessel traffic can cause space-use conflicts with recreational 

activities such as boating. Marine debris can degrade the recreational value of resources such as beaches. 

The presence or absence of OCS oil- and gas-related infrastructure could impact activities such as 

recreational fishing or diving. Oil spills could also contribute to the overall degradation of beach and 

wetland-based recreational resources. Most accidental spills are not likely to impact Gulf Coast 

recreational resources because they are expected to be small and of short duration. If oil resulting from a 

spill were to contact a beach area or other recreational resource, disruption could occur from oiling and oil 
4-70 Western Planning Area Lease Sale 248 Supplemental EIS

cleanup. However, these effects are also likely to be small in scale and of short duration. The impacts of 

a low-probability catastrophic oil spill, which is not part of the WPA proposed action and not likely 

expected to occur, on recreational resources are discussed in Appendix A. 

Recreational resources along the Gulf Coast can also be impacted by similar non-OCS oil- and gasrelated aesthetic and space-use conflicts, as well as a variety of non-OCS oil- and gas-related factors, such 

as State oil and gas activities, coastal erosion, beach disruptions, military activities, and economic factors. 

Coastal erosion negatively impacts recreational activities that depend on wetland and beach resources. 

Beach disruptions would arise from degradations of air and water quality, as well as by natural processes 

such as red tides. Military activities could cause aesthetic impacts and space-use conflicts with 

recreational activities. Recreational activities will also correlate with regional and national economic 

trends.

The incremental contribution of the WPA proposed action is expected to be minimal in light of all 

OCS oil- and gas-related and non-OCS oil- and gas-related activities. This is because of the small scale 

of the WPA proposed action, as well as the fact that most impacts to recreational resources will be 

temporary. 

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

BOEM conducted a search of Internet sources and known data providers for new information 

regarding the impacts of the WPA proposed action on recreational resources. Eastern Research Group, 

Inc. (2014a) conducted a study of the impacts of the Deepwater Horizon explosion, oil spill, and response 

on tourism activities in the Gulf region. Eastern Research Group, Inc. analyzed Deepwater Horizon

claims data, reviewed newspaper accounts of the spill, analyzed county-level employment data, and 

conducted interviews with people involved in the tourism industry. These various methodologies paint a 

rich picture of the impacts of the Deepwater Horizon explosion, oil spill, and response, and they revealed 

some broad conclusions. First, the Deepwater Horizon explosion, oil spill, and response had a broad 

geographic reach, partially due to public perceptions of the nature and scope of the spill. In addition, 

restaurants and hotels were particularly impacted by the Deepwater Horizon explosion, oil spill, and 

response, which led areas with more diversified tourism economies to endure better in the spill’s 

aftermath. Also, tourism generally rebounded strongly after the initial decline. Indeed, employment that 

supported the recovery held up well in most counties following the Deepwater Horizon explosion, oil 

spill, and response. Finally, the impacts of the spill on tourism were shaped by the damage payment 

system, cleanup processes, and lessons learned from prior disasters. Eastern Research Group, Inc. 

(2014a) has improved BOEM’s understanding of the impacts of oil spills; the study has also clarified the 

affected environment for recreational resources subsequent to the Deepwater Horizon explosion, oil spill, 

and response. Eastern Research Group, Inc. conducted related studies that provided additional details 

regarding the methods used to measure tourism employment (Eastern Research Group, Inc. 2014a and 

2014b). Eastern Research Group, Inc. (2014b) created measures of tourism and recreation that weigh 

various industries by estimates of the extent to which each industry is dependent on tourism and 

recreation. This study improves BOEM’s understanding of the affected environment for recreational 

resources following the Deepwater Horizon explosion, oil spill, and response.

Cullinane-Thomas et al. (2015) provide estimates of the number of visitors, amount of spending, 

number of jobs, and amount of income in 2013 supported by each national park along the Gulf Coast 

This information improves BOEM’s knowledge of the affected environment for recreational resources. 

The parks closest to the WPA proposed action are Padre Island National Seashore (Texas) 

(515,831 visitors; $20,967,000 in spending) and Jean Lafitte National Historical Park and Preserve 

(Louisiana) (400,128 visitors; $22,055,000 in spending). Visitor numbers and spending were less at both 

parks in 2013 than in 2012. 

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is 

still incomplete or unavailable information. The information below updates or adds to the understanding 
Description of the Environment and Impact Analysis 4-71

of incomplete or unavailable information for recreational resources. This incomplete information may be 

relevant because the full extent of potential adverse impacts on recreational resources as a result of the 

WPA proposed action is not known. In particular, standard data sources do not disclose employment data 

for certain tourism-related industries in certain counties, often to prevent disclosure of confidential 

information. In light of the incomplete or unavailable information, BOEM used existing data sources and 

standard methods to estimate the impacts of the WPA proposed action on recreational resources. In 

particular, BOEM used data from the Bureau of Labor Statistics, using broader industry categories to 

estimate the scale of recreation-related activities in recent years. BOEM also used data from CullianeThomas et al. (2015) to estimate the baseline environment for recreational resources. These data provide 

sufficient baseline information from which to estimate the impacts of the OCS Program, particularly since 

the available data suggest that most recreational areas have recovered from the impacts of the Deepwater

Horizon explosion, oil spill, and response. Therefore, BOEM has determined that the incomplete or 

unavailable information is not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for recreational resources presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information presented above. No new information was 

discovered that would alter the impact conclusion for recreational resources presented in the prior 2012-

2017 Gulf of Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA

documents still apply for proposed WPA Lease Sale 248.

4.1.1.19.Archaeological Resources

4.1.1.19.1. Historic Archaeological Resources

Historic archaeological resources on the OCS consist of historic shipwrecks and a single historic 

lighthouse, the Ship Shoal Light. A historic shipwreck is defined as a submerged or buried vessel or its 

associated components, at least 50 years old, that has foundered, stranded, or wrecked and that is 

currently lying on or is embedded in the seafloor. Ships are known to have traversed the waters of the 

WPA as early as Captain Alonso Alverez de Piñeda’s expedition in 1519. Alvar Nuñez Cabeza de Vaca 

is likely to have the dubious distinction of being the first European to be shipwrecked along the Texas 

coast, as early as 1528 (Francaviglia, 1998). 

BOEM has reexamined the analysis for historic archaeological resources presented in the prior 2012-

2017 Gulf of Mexico EISs based on the information presented below. No new information was 

discovered that would alter the impact conclusion for historic archaeological resources presented in the 

prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in 

those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of historic archaeological resources, along with the full analyses of the 

potential impacts of routine activities, accidental events, and cumulative impacts associated with the 

WPA proposed action, are presented in Chapter 4.1.1.19 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.19 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. BOEM has found no significant 

new information that has become available since those NEPA documents were published. 

Damage to archaeological resources as a result of offshore oil and gas activity can be minimized by 

pre-seabed-disturbance archaeological surveys. Archaeological surveys, where required prior to an 

operator beginning OCS oil and gas activities on a lease, are expected to be effective at identifying 

possible archaeological sites. The technical requirements of the archaeological resource reports are 

detailed in NTL 2005-G07, “Archaeological Resource Surveys and Reports.” Under 30 CFR § 

550.194(c), lessees are required to immediately notify BOEM’s Regional Director of the discovery of any 

potential archaeological resources. Under 30 CFR § 250.194(c) and 30 CFR § 250.1010(c), lessees are 

also required to immediately notify BSEE’s Regional Director of the discovery of any potential 

archaeological resources. In addition, archaeological resources in the coastal environment are protected 
4-72 Western Planning Area Lease Sale 248 Supplemental EIS

through Federal, State, and local agency permit review as well as Section 106 of the National Historic 

Preservation Act (54 U.S.C. § 306108). 

Routine impact-producing factors associated with the WPA proposed action that could affect historic 

archaeological resources include direct physical contact with a shipwreck site from the following: the 

placement of drilling rigs and production systems on the seafloor; pile driving associated with platform 

emplacement; pipeline installation; dredging of new channels, as well as maintenance dredging of 

existing channels; anchoring activities; and post-decommissioning trawling clearance. Additionally, 

industry-related debris may mask the location of archaeological resources during remote-sensing surveys 

or may create false positives. The greatest potential impact to an archaeological resource as a result of the 

WPA proposed action would result from direct contact between an offshore activity (i.e., platform or 

pipeline installation, drilling rig emplacement, dredging, and post-decommissioning trawling) and a 

historic site because of incomplete knowledge on the location of these sites in the Gulf of Mexico. The 

risk of contact to archaeological resources is greater in instances where archaeological survey data are 

inadequate or unavailable. Such an event could result in the disturbance or destruction of important 

archaeological information. Archaeological surveys provide the necessary information to develop 

avoidance strategies that reduce the potential for impacts on archaeological resources. Except for the 

projected 0-1 new gas processing facilities and 0-1 new pipeline landfalls, the 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.

Impacts to documented and undocumented historic archaeological resources could occur as a result of 

an accidental oil spill and the associated cleanup operations. Detailed risk analyses of offshore oil spills

ranging from <1,000 bbl to ≥1,000 bbl and coastal spills associated with the WPA proposed action are 

provided in Chapters 3.2.1.5, 3.2.1.6, and 3.2.1.7 of this Supplemental EIS and Chapters 3.2.1.5, 3.2.1.6, 

and 3.2.1.7 of the 2012-2017 WPA/CPA Multisale EIS. When oil is spilled in offshore areas, much of the 

oil volatilizes or is dispersed by currents, so it has a low probability of contacting coastal areas. However, 

should a spill contact a historic archaeological site (including submerged sites), damage might include 

contamination of materials, direct impact from oil-spill cleanup equipment, and/or looting during onsite 

impact mitigation. An additional major effect from an oil spill could be viewshed pollution of a historic 

coastal site, such as a fort or lighthouse. Although such effects may be temporary and reversible, cleaning 

oil from historic structures can be a complex, time-consuming, and expensive process, and the use of 

dispersants may result in long-term chemical contamination of submerged cultural heritage sites (e.g., 

Chin and Church, 2010). As of this writing, there are no published studies documenting or analyzing the 

long-term effects of oil or dispersant contamination on submerged archaeological sites. It is expected, 

however, that any spill cleanup operations would be considered a Federal undertaking for the purposes of 

Section 106 of the National Historic Preservation Act (54 U.S.C. § 306108) and would be conducted in 

such a way as to minimize impacts to historic archaeological resources.

Several OCS oil- and gas-related cumulative impact-producing factors could potentially impact 

historic archaeological resources, including the following: (1) OCS Program routine and accidental 

impacts; (2) artificial rigs-to-reefs development; and (3) renewable energy and alternative use 

conversions. A detailed impact analysis of the cumulative impacts of OCS oil- and gas-related activities 

associated with proposed WPA Lease Sale 248 on historic archaeological resources can be found in 

Chapter 4.1.1.19.1.4 of the 2012-2017 WPA/CPA Multisale EIS and Appendix D of the WPA 

238/246/248 Supplemental EIS. Historic archaeological resources on the OCS are vulnerable to the 

above OCS oil- and gas-related cumulative impact-producing factors due to the associated bottomdisturbing activities. An impact could result from direct physical contact between historic shipwrecks 

located on the OCS and OCS Program oil and gas activities (i.e., pipeline and platform installations, 

drilling rig emplacement and operation, site decommissioning, rigs-to-reefs development, dredging, and 

anchoring activities). Permitting OCS oil- and gas-related development prior to requiring archaeological 

surveys has been documented to have impacted wrecks containing significant or unique historic 

information (Church and Warren, 2008; Melancon and Blackmon, 2011). Impacts may be reduced when 

preconstruction surveys are required by BOEM or the permitting agency prior to these activities. Impacts 

to historic resources may still occur in areas where a remote-sensing survey fails to resolve the location of

partially or completely buried resources or when no pre-disturbance survey is required. Impacts to 

documented and undocumented historic archaeological resources could occur as a result of an accidental 

oil spill and the associated cleanup operations; however, the potential for spills is low, the effects would 
Description of the Environment and Impact Analysis 4-73

generally be localized, and the cleanup efforts would be regulated. Low-probability catastrophic spills, 

which are not part of the WPA proposed action and not likely expected to occur, are discussed in 

Appendix A. 

Non-OCS oil- and gas-related cumulative impact-producing factors that could potentially impact 

historic archaeological resources include the following: (1) State oil and gas activity; (2) offshore LNG 

projects; (3) new channel dredging and maintenance dredging; (4) State renewable energy and alternative 

use conversions; (5) State artificial reefs and rigs-to-reefs development; (6) commercial fishing; (7) sport 

diving and commercial treasure hunting; and (8) natural processes, including wave action and hurricanes. 

As with the OCS oil- and gas-related cumulative impact-producing factors, risks from the above non-OCS 

oil- and gas-related cumulative impact-producing factors are related to their associated bottom-disturbing 

activities. An impact could result from direct physical contact between historic shipwrecks and Staterelated oil and gas activities, sand borrowing, renewable energy activities, LNG facility construction,

artificial reef creation, new channel dredging, and maintenance dredging. With the exception of 

maintenance dredging, preconstruction archaeological surveys may be required for these activities. 

Impacts to historic resources may still occur in areas where a remote-sensing survey fails to resolve the 

location of partially or completely buried resources or when no pre-disturbance survey is required.

The effects of the various impact-producing factors discussed in this analysis have likely resulted in 

the localized loss of significant or unique archaeological information. In the case of factors related to past 

OCS Program activities within the cumulative activity area, it is reasonable to assume that most impacts 

would have occurred where development took place prior to any archaeological survey requirements. 

When surveys are not required, it is impossible to anticipate what might be embedded in or lying directly 

on the seafloor, and impacts to these sites are likely to be significant. When surveys are required, there is 

still the possibility of an unanticipated interaction between bottom-disturbing activity (i.e., rig 

emplacement, pipeline trenching, anchoring, and other ancillary activities) and a historic shipwreck, 

despite diligence in BOEM’s survey review process. However, the incremental contribution of the WPA 

proposed action is expected to be very small due to the efficacy of the remote-sensing survey and 

archaeological reporting requirements within the proposed lease sale area. Future OCS Program activity, 

including the bottom-disturbing activity permitted by BOEM and other agencies, may require 

preconstruction archaeological surveys that, when completed, are highly effective in identifying bottom 

anomalies that can be either avoided or investigated before bottom-disturbing activities begin.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/ CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

Various Internet sources were examined to assess recent information regarding impacts to 

archaeological resources or potential new threats to archaeological resources that may be pertinent to the 

WPA. These Internet sources included various online indexes to periodical literature, such as JSTOR, the 

National Technical Information Service’s National Technical Reports Library, and ScienceDirect. This 

search did not identify any new information that would be pertinent to the analysis of the potential 

impacts of OCS oil- and gas-related activities on historic archaeological resources.

Incomplete or Unavailable Information 

BOEM has determined that previous conclusions from the prior 2012-2017 Gulf of Mexico EISs are 

still valid because no new information on historic archaeological resources pertinent to the WPA 

proposed action has been published since the publication of those NEPA documents. Nevertheless, there 

is still incomplete or unavailable information regarding the long-term effects of oil and/or dispersant

contamination on, and the location of, historic archaeological resources in the WPA. As discussed above, 

there are currently no published studies on the long-term effects to historic archaeological resources 

exposed to oil or dispersant contamination. Such information is unlikely to be available prior to proposed 

WPA Lease Sale 248; however, considering the low probability of an accidental oil spill contacting an 

archaeological site as a result of the WPA proposed action, BOEM has determined that the information is 

not essential to a reasoned choice among alternatives.

Additionally, the locations of historic archaeological resources in the WPA cannot be determined 

because the overall costs of obtaining that information through survey of the entire WPA are exorbitant. 
4-74 Western Planning Area Lease Sale 248 Supplemental EIS

This incomplete information may be relevant to adverse effects because the locations and integrity of 

many historic archaeological resources remain unknown. Nevertheless, this incomplete information is not 

likely to be available within the timeline contemplated in this NEPA analysis of this Supplemental EIS. It 

would take several years before data confirming the presence (or lack thereof) of historic archaeological 

resources, and the status of each, could be investigated, analyzed, and compiled. Historic archaeological 

sites within the WPA region have the potential to be buried, embedded in, or laying on the seafloor. The 

WPA covers an area of approximately 28.58 million acres and ranges in water depths from an estimated 

10 to 3,420 m (33 to 11,220 ft). It includes highly variable bathymetric and geophysical regimes, which 

differentially affect the ease and ability to identify, ground truth, and evaluate historic archaeological 

sites. This fact, combined with the scope of the acreage within the WPA, results in the aforementioned 

exorbitant costs and time factors. 

BOEM used existing information and reasonably accepted scientific theories on archaeological site 

potential in the Gulf of Mexico to extrapolate from available information in completing the relevant 

analysis. In addition, future site-specific, remote-sensing surveys of the seafloor are required when 

deemed appropriate to establish the presence of potential resources (NTL 2005-G07). The results of these 

surveys are reviewed in tandem with credible scientific evidence from previously identified sites, regional 

sedimentology, and physical oceanography that is relevant to evaluating the adverse impacts on historic 

resources that are a part of the human environment. The required surveys are analyzed by industry and 

BOEM archaeologists prior to the authorization of any new or significant bottom-disturbing impacts and, 

if necessary, avoidance of potential archaeological resources is prescribed. Archaeological surveys are 

expected to be highly effective in identifying resources to allow for protection of the resource during OCS 

oil- and gas-related activities. The WPA proposed action is not expected to have a reasonably foreseeable 

significant impact because BOEM’s evaluation of such impacts is based upon pre-disturbance and sitespecific surveys, the results of which BOEM uses to require substantial avoidance of any potential 

historic resource that could be impacted by the proposed activity. Therefore, BOEM has determined that 

the information is not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for historic archaeological resources presented in the prior 2012-

2017 Gulf of Mexico EISs. No new information was discovered that would alter the impact conclusion 

for historic archaeological resources presented in the prior 2012-2017 Gulf of Mexico EISs. The analysis 

and potential impacts detailed and updated in those NEPA documents still apply for proposed WPA Lease 

Sale 248. 

4.1.1.19.2. Prehistoric Archaeological Resources

Prehistoric archaeological resources are any material remains of human life or activities associated 

with the earliest inhabitants of the Gulf Coast, predating European discovery and exploration of the area. 

Available evidence suggests that the first Americans arrived on the Gulf Coast as much as 12,000 years 

before present (B.P.) during a time when the continental shelf was exposed above sea level and open to 

habitation (Pearson et al., 1986). 

BOEM has reexamined the analysis for prehistoric archaeological resources presented in the prior 

2012-2017 Gulf of Mexico EISs based on the additional information presented below. No new 

information was discovered that would alter the impact conclusion for prehistoric archaeological 

resources presented in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential 

impacts detailed and updated in those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of prehistoric archaeological resources, along with the full analyses of the 

potential impacts of routine activities, accidental events, and cumulative impacts associated with the 

WPA proposed action, are presented in Chapter 4.1.1.19.2 of the 2012-2017 WPA/CPA Multisale EIS, 

and updated information is provided in Chapter 4.1.1.19.2 of the WPA 233/CPA 231 Supplemental EIS, 

WPA 238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. BOEM has found no significant 

new information that has become available since those NEPA documents were published. 
Description of the Environment and Impact Analysis 4-75

Prehistoric archaeological sites are thought to be preserved shoreward of the 45-m (148-ft) 

bathymetric contour, where the Gulf of Mexico continental shelf was subaerially exposed during the Late 

Pleistocene. Archaeological surveys, where required prior to an operator beginning OCS oil- and gasrelated activities on a lease, are expected to be somewhat effective at identifying submerged landforms 

that could support possible prehistoric archaeological sites. The NTL 2005-G07 recommends a 300-m 

(984-ft) maximum line spacing for remote-sensing surveys of leases within areas having a high potential 

for prehistoric sites. While surveys provide a reduction in the potential for a damaging interaction 

between an impact-producing factor and a prehistoric archaeological site, there is still a possibility of an 

OCS oil- and gas-related activity contacting an archaeological site. Should such impacts occur, there 

could be damage to or loss of significant and/or unique archaeological information.

Routine impact-producing factors associated with the WPA proposed action that could affect 

prehistoric archaeological resources include direct physical contact associated with the following: the 

placement of drilling rigs and production systems on the seafloor; pile driving associated with platform 

emplacement; pipeline installation; dredging of new channels, as well as maintenance dredging of 

existing channels; anchoring activities; and post-decommissioning trawling clearance. 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 contexts for North America, 

Central America, South America, and the Caribbean. The risk of contact to archaeological resources is 

greater in instances where archaeological survey data are inadequate or unavailable. Archaeological 

surveys provide the necessary information to develop avoidance strategies that reduce the potential for 

impacts on archaeological resources. Except for the projected 0-1 new gas processing facilities and 

0-1 new pipeline landfalls, the WPA proposed action would require no new oil and gas coastal 

infrastructure. It is expected that the protection of archaeological resources would be maximized through 

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

offshore activities.

Impacts to documented (onshore) and undocumented (onshore and offshore) prehistoric 

archaeological resources could occur as a result of an accidental oil spill and the associated cleanup 

operations. Oil spills in the WPA and related spill-response activities have the potential to impact cultural 

resources near the spill site and landfall areas. Detailed risk analyses of offshore oil spills ranging from 

<1,000 bbl to ≥1,000 bbl and of coastal spills that may be associated with the WPA proposed action are 

provided in Chapters 3.2.1.5, 3.2.1.6, and 3.2.1.7 of this Supplemental EIS and Chapters 3.2.1.5, 3.2.1.6, 

and 3.2.1.7 of the 2012-2017 WPA/CPA Multisale EIS. Should a spill contact a prehistoric 

archaeological site, damage might include loss of radiocarbon-dating potential, direct impact from oilspill cleanup equipment, and/or looting. There is currently no published information documenting or 

analyzing the long-term effects of oil or dispersant contamination on prehistoric archaeological sites. 

However, when oil is spilled in offshore areas, much of the oil volatilizes or is dispersed by currents, so it 

has a low probability of contacting coastal and barrier island prehistoric sites as a result of the WPA 

proposed action. The WPA proposed action, therefore, is not expected to result in impacts to prehistoric 

archaeological sites.

Several OCS oil- and gas-related cumulative impact-producing factors that could potentially impact 

prehistoric archaeological resources include the following: (1) OCS Program routine and accidental 

impacts; (2) renewable energy and alternative use conversion; and (3) artificial rigs-to-reefs development. 

A detailed impact analysis of the cumulative impacts of OCS oil- and gas-related activities associated 

with proposed WPA Lease Sale 248 on prehistoric archaeological resources can be found in Chapter 

4.1.1.19.2.4 of the 2012-2017 WPA/CPA Multisale EIS and Appendix D of the WPA 238/246/248 

Supplemental EIS. 

The OCS oil- and gas-related activities that could impact prehistoric archaeological sites located on 

the OCS through contact include pipeline and platform installations, drilling rig emplacement and 

operation, site decommissioning, rigs-to-reefs development, dredging, and anchoring activities. 

Preconstruction surveys may be required by BOEM or the lead permitting agency prior to these activities. 

Impacts to prehistoric resources may still occur in areas where a remote-sensing survey fails to resolve the 

location of partially or completely buried resources or when no pre-disturbance survey is required. 

Development onshore as a result of the WPA proposed action could result in the direct physical contact 

between a prehistoric site and pipeline trenching. It is assumed that archaeological investigations prior to 

construction will serve to mitigate these potential impacts. Oil spills have the potential to impact coastal 
4-76 Western Planning Area Lease Sale 248 Supplemental EIS

prehistoric sites directly or indirectly by physical impacts caused by oil-spill cleanup operations. The 

number and most likely spill sizes to occur in coastal waters in the future are expected to resemble the 

patterns that have occurred in the past, as long as the level of oil- and gas-related commercial and 

recreational activities remain the same. Low-probability catastrophic spills, which are not part of the 

proposed action and not likely expected to occur, could also contact coastal prehistoric sites, and the 

effects of a spill that size would likely result in longer-lasting impacts that take longer to mitigate. 

Accidental spills as a result of a low-probability catastrophic spill are discussed in Appendix A. 

Non-OCS oil- and gas-related cumulative impact-producing factors that could potentially impact 

prehistoric archaeological resources including the following: (1) State oil and gas activity; (2) new 

channel dredging and maintenance dredging; (3) State renewable energy and alternative use conversions; 

(4) State artificial reefs and rigs-to-reefs development; (5) OCS sand borrowing; (6) offshore LNG 

projects; (7) commercial fishing; and (8) natural processes, including wave action and hurricanes. 

These impact-producing factors all create associated bottom disturbances that may threaten 

prehistoric archaeological resources. An impact could result from contact between prehistoric resources 

and permitted activities such as State oil and gas activities, renewable energy activities, artificial reef

creation, new channel dredging, and maintenance dredging. With the exception of maintenance dredging, 

preconstruction archaeological surveys may be required for these activities. Impacts to prehistoric 

resources may still occur in areas where a remote-sensing survey fails to resolve the location of partially 

or completely buried resources or when no pre-disturbance survey is required. Oil and gas program wells, 

structures, and pipelines existing entirely in State waters are not under the jurisdiction of BOEM with 

respect to the archaeological resource protection requirements of the National Historic Preservation Act 

and would be the responsibility of the State and the permitting Federal agency. Prehistoric sites in 

shallow waters and on coastal beaches are exposed to the destructive effects of wave action and scouring 

currents. Overall, loss of data from prehistoric sites has probably occurred, and will continue to occur, in 

the northwestern Gulf from the effects of tropical storms. 

The effects of the various impact-producing factors discussed in this analysis have likely resulted in 

localized losses of significant or unique prehistoric 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 where development took place prior to any archaeological survey 

requirements. The incremental contribution of the WPA proposed action is expected to be very small due 

to the efficacy of the required remote-sensing survey and concomitant archaeological report and 

clearance.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/ CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

Various Internet sources were examined to assess recent information regarding impacts to 

archaeological resources or potential new threats to archaeological resources that may be pertinent to the 

WPA. These Internet sources included various online indexes to periodical literature, such as JSTOR, the 

National Technical Information Service’s National Technical Reports Library, and ScienceDirect. This 

search did not identify any new information that would be pertinent to the analysis of the potential 

impacts of OCS oil- and gas-related activities on prehistoric archaeological resources.

Incomplete or Unavailable Information 

BOEM has determined that previous conclusions from the prior 2012-2017 Gulf of Mexico EISs are 

still valid because no new information on prehistoric archaeological resources pertinent to the WPA 

proposed action has been published since the publication of those NEPA documents. Nevertheless, there 

is still incomplete or unavailable information regarding the long-term effects of oil and/or dispersant

contamination on, and the location of, prehistoric archaeological resources in the WPA. As discussed 

above, there are currently no published studies on the long-term effects to prehistoric archaeological 

resources exposed to oil or dispersant contamination. Such information is unlikely to be available prior to 

proposed WPA Lease Sale 248; however, considering the low probability of an accidental oil spill

contacting a submerged or coastal prehistoric archaeological site as a result of the WPA proposed action, 

BOEM has determined that the information is not essential to a reasoned choice among alternatives.
Description of the Environment and Impact Analysis 4-77

Additionally, the locations of prehistoric archaeological resources in the WPA cannot be determined 

because the overall costs of obtaining that information through survey of the entire WPA are exorbitant. 

This incomplete information may be relevant to adverse effects because the locations and integrity of 

many prehistoric archaeological resources remain unknown. Nevertheless, this incomplete information is 

not likely to be available within the timeline contemplated by the NEPA analysis of this Supplemental 

EIS. It would take many years before data confirming the presence of prehistoric archaeological 

resources in a given location, and the status of each could be investigated, analyzed, and compiled. Most 

prehistoric sites within the WPA region are likely buried and would therefore be difficult to identify, 

resulting in the largest portion of aforementioned exorbitant costs and time factors.

BOEM used existing information and reasonably accepted scientific theories on prehistoric 

archaeological site potential in the Gulf of Mexico to extrapolate from available information in 

completing the relevant analysis. In place of the incomplete or unavailable information, BOEM used 

archaeological investigations, such as subbottom sonar survey, that are required for all areas shoreward of 

the 196-ft (60-m) bathymetric contour (NTL 2005-G07), which is understood to represent the Pleistocene 

shoreline when human beings migrated into the Gulf Coast. These surveys are reviewed in tandem with 

existing credible scientific evidence of site types, material remains and preservation potential from 

terrestrial archaeological sites (Rees, 2010, CEI, 1977), geology, and physical oceanography that is 

relevant to evaluating the adverse impacts on prehistoric archaeological resources. The required surveys 

are analyzed by industry and BOEM archaeologists prior to the authorization of any new or significant 

bottom-disturbing impacts and, if necessary, avoidance of potential archaeological resources is 

prescribed. The WPA proposed action is not expected to have a reasonably foreseeable significant impact 

because BOEM’s evaluation of such impacts includes analysis of pre-disturbance and site-specific survey, 

the results of which BOEM uses to require substantial avoidance of any potential prehistoric resource that 

could be impacted by the proposed activity. Therefore, BOEM has determined that the information is not 

essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for prehistoric archaeological resources presented in the prior 

2012-2017 Gulf of Mexico EISs. No new information was discovered that would alter the impact 

conclusion for prehistoric archaeological resources presented in the prior 2012-2017 Gulf of Mexico 

EISs. The analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248. 

4.1.1.20.Human Resources and Land Use

4.1.1.20.1. Land Use and Coastal Infrastructure

BOEM has reexamined the analysis for land use and coastal infrastructure presented in the prior 

2012-2017 Gulf of Mexico EISs based on the additional information presented below. No new 

information was discovered that would alter the impact conclusion for land use and coastal infrastructure

presented in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts 

detailed and updated in those NEPA documents still apply for proposed WPA Lease Sale 248. 

A detailed description of land use and coastal infrastructure, along with the full analyses of the 

potential impacts of routine activities, accidental events, and cumulative impacts associated with a WPA 

proposed action, are presented in Chapter 4.1.1.20.1 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.20.1 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246 and 248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has 

become available since those NEPA documents were published is presented below. 

Impact-producing factors associated with the WPA proposed action that could affect land use and 

coastal infrastructure include the construction of new or the expansion of existing gas processing 

facilities, pipeline landfalls, service bases, offshore supply vessel (OSV) day rates, navigation channels, 

and waste disposal facilities to the current infrastructure. Activities relating to the OCS Program are 
4-78 Western Planning Area Lease Sale 248 Supplemental EIS

expected to minimally affect the current land use of the analysis area because most subareas have strong 

industrial bases and designated industrial parks to accommodate future growth in oil and gas businesses. 

There would be only minor infrastructure changes in the Texas, Louisiana, Mississippi, Alabama, and 

Florida Economic Impact Areas (EIAs). This is primarily because the demand would be met with the 

existing infrastructure and facilities. Since the infrastructure is mature and not subject to rapid 

fluctuations and because BOEM only projects 0-1 new gas processing facilities and 0-1 new pipeline 

landfalls for the WPA proposed action, the impacts of routine events associated with the WPA proposed 

action are expected to remain at historic activity levels. There may be a new increased demand for waste 

disposal services as a result of the WPA proposed action; however, the effects on land use and 

infrastructure would be limited, would occur on lands designated for such purposes, and would have 

minimal impacts to land use and coastal infrastructure. Because the projected addition to infrastructure is 

near zero, the routine activities associated with the WPA proposed action would have little effect on land 

use and existing coastal infrastructure, and there would be minimal impacts from any expansion of 

existing infrastructure.

Accidental events associated with the WPA proposed action that could affect land use and coastal 

infrastructure include oil spills, vessel collisions, and chemical/drilling-fluid spills. Accidental events 

associated with the WPA proposed action could occur at differing levels of severity, based in part on the 

location, timing/season, and size of the event. Spills can occur in coastal waters at shoreline storage, 

processing, and transport facilities supporting the OCS oil and gas industry. Coastal spills occur in State 

offshore waters and in navigation channels, rivers, and bays from barges and pipelines carrying OCSproduced oil. Refer to Chapter 3.2.1 for a detailed discussion of past OCS oil spills, oil-spill risk 

analysis, oil-spill response, and their impacts. Issues discussed in Chapter 3.2.1 that are related to spill 

response include offshore response, containment, and cleanup technology; and onshore response and 

cleanup. Typically, the impact of small-scale oil spills, vessel collisions, and chemical/drilling fluid spills 

are not likely to last long enough to adversely affect overall land use or coastal infrastructure in the 

analysis area.

The cumulative analysis considers both existing land use patterns and the effects of impact-producing 

factors from OCS oil- and gas-related and non-OCS oil- and gas-related activities. Impact-producing 

factors associated with OCS oil- and gas-related activities that could affect land use and coastal 

infrastructure include the construction of new or the expansion of existing gas processing facilities, 

pipeline landfalls, service bases, navigation channels, and waste disposal facilities, plus the occurrence of 

oil spills, vessel collisions, and chemical/drilling-fluid spills. Any service base expansion in the 

cumulative case would be limited, would occur on lands designated for such purposes, and would have 

minimal effects on land use and infrastructure. Impacts resulting from chemical or oil spills and vessel 

collisions can vary in location and severity, but they are not likely to last long enough to adversely affect 

overall land use or coastal infrastructure in the analysis area. A low-probability catastrophic spill, which 

is not part of the WPA proposed action and not reasonably expected to occur, can result in impacts to land 

use and coastal infrastructure. For more information on a low-probability catastrophic spill event, which 

is not part of the WPA proposed action and not likely expected to occur, refer to Appendix A. Therefore, 

the incremental contribution of the WPA proposed action to the cumulative impacts on land use and 

coastal infrastructure is also expected to be minor. 

The non-OCS oil- and gas-related factors that can impact coastal infrastructure and land use consist of 

previous, current, and future State lease sales, as well as housing and other residential developments; 

macro and microeconomic trends; coastal land loss and subsidence; the establishment of private and 

publicly owned recreational facilities; the construction and maintenance of industrial facilities and 

transportation systems; urbanization; city planning and zoning; changes to public facilities such as water, 

sewer, educational, and health facilities; changes to military bases and reserves; changes in population 

density; changes in State and Federal land use regulations; changes in non-OCS oil- and gas-related 

demands for water transportation systems and ports; and natural processes. The Gulf of Mexico OCS 

leasing program exists within a highly industrialized and economically diverse coastal region, which is 

itself the aggregate of past and present community, government, and business actions. How land has been 

traditionally used or will be used in the future is determined irrespective of the WPA proposed action. 

Coastal infrastructure associated with the OCS oil and gas industry is also utilized by State oil and gas as 

well as other industries. This short summary of land uses and land use categories is by no means 

comprehensive, but it should illustrate that OCS coastal land use and infrastructure comprises only a 
Description of the Environment and Impact Analysis 4-79

percentage of the total land use and allows us a bird’s eye view of the program within context of other 

impact-producing factors. 

Land use categories are tied to existing infrastructure and historic uses and, for the purpose of this 

analysis, include the Economic Research Service’s own land-use inventories categories: State oil and gas 

activities; agriculture; forest, parks, and special use areas; urban areas; miscellaneous areas; and inland 

navigable waterways and ports. Land use patterns vary greatly by region, reflecting differences in soils, 

climate, topography, and patterns of population settlement. Changes in land use will largely depend upon 

local zoning and economic trends. For example, State oil and gas activities are expected to have similar 

impacts to OCS oil- and gas-related activities on land use and coastal infrastructure. State oil and gas 

activities and associated impacts will occur based on State leasing programs, geologic plays, economic 

trends, and local regulatory regimes. Non-OCS oil- and gas-related vessel collisions and rail car oil spills

can contribute substantially to the cumulative impacts to land use and coastal infrastructure (Lipinski, 

2014; Tate, 2014). As another example, agricultural land use may result in pesticide and nutrient runoff, 

competition for water consumption, and changes in hydrology and soil quality. Urbanization can lead to 

habitat fragmentation, transit choices, and air and water pollution. Urban areas are influenced by 

economics (Chapter 4.1.1.20.3), demographics (Chapter 4.1.1.20.2), and local ordinances and zoning. 

For more details on the cumulative impacts of non-OCS oil- and gas-related impacts on land use and 

coastal infrastructure, refer to the Chapter 4.1.1.20.1 of the 2012-2017 Multisale EIS and Appendix D of 

the WPA 238/246/248 Supplemental EIS. 

The OCS oil- and gas-related support activities occur within a context of a well-established populated 

Texas coastal region, which is home to a diverse and robust economy. Many local and national 

industries, such as agricultural and industrial, utilize the same transportation systems and ports used by 

the OCS oil and gas industry. The OCS oil- and gas-related demands on land use are typically relegated 

to coastal or inland waterway industrial zones and represent a small fraction of how existing residential, 

recreational, agricultural, military, and industrial uses utilize and impact land use and coastal 

infrastructure. Because the vast majority of coastal infrastructure supports OCS and State offshore and 

land-based oil and gas production, as well as other land-based industrial uses, the coastal infrastructure 

supporting the WPA proposed action represents only a small portion of the coastal land use and 

infrastructure throughout the WPA and Gulf of Mexico, and because this is a shared resource, the 

incremental contribution of the WPA proposed action is expected to have minimal impact overall. With 

20 percent of the State’s land use devoted to cropland and 61 percent devoted to grassland pasture and 

range, 15 military bases, more than 10,000 mi (16,093 km) of railroad tracks, an interstate system with 

79,696 centerline miles (128,258 km) (miles traveled in a one-way direction regardless of the number of 

lanes) of road that carries about 74 percent of the State’s vehicular traffic, and 4 percent of the State land 

area used for high population areas, non-OCS oil- and gas-related factors contribute significantly to the 

cumulative impacts on land use (Lubowski et al., 2006; State of Texas, Dept. of Agriculture, 2013; 

MilitaryBases.com, 2013a and 2013b; State of Texas, Comptroller of Public Accounts, 2013). 

Meanwhile, OCS oil- and gas-related coastal infrastructure and land use represent only an incremental 

contribution to total land use, and the cumulative impacts as a result of the WPA proposed action and the 

OCS Program as a whole on land use and coastal infrastructure are also expected to be minor.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

Additional research was conducted to investigate the availability of recent information affecting land 

use and coastal infrastructure since publication of the prior 2012-2017 Gulf of Mexico EISs. Various 

Internet sources were examined, including the websites of numerous Federal and State agencies (USDHS, 

Federal Emergency Management Agency; USDOC, Bureau of the Census; USDOC, NOAA; USDOE, 

Energy Information Administration; USDOT, Maritime Administration; USDOI, FWS; 

RestoreTheGulf.gov website; Deepwater Horizon Oil Spill Portal; USEPA; Louisiana Department of 

Environmental Quality; Texas Commission on Environmental Quality; Louisiana Recovery Authority; 

and Louisiana Office of Community Development). Further information was sought from other 

organizations, recently published journal articles, and trade publications such as The Greater Lafourche 

Port Commission, LA1 Coalition, The Oil Drum, Rigzone, Oil and Gas Journal, Offshore magazine, 

TOLLROAD News, and The Energy Journal. New information was found on the status of the affected 
4-80 Western Planning Area Lease Sale 248 Supplemental EIS

environment and growing markets related to OCS oil- and gas-related activities, as well as the impacts 

from non-OCS oil- and gas-related activities.

The U.S. Dept. of Energy’s Energy Information Administration has released its 2015 Annual Energy 

Outlook (U.S. Dept. of Energy, Energy Information Administration, 2015i). In its reference scenario, 

shallow-water Gulf oil production is forecast to decrease from 197,000 barrels per day in 2015 to 

129,000 barrels per day in 2040. Deepwater Gulf oil production is forecast to increase from 1.34 MMbbl 

per day in 2015 to 1.85 MMbbl per day in 2040. In recent months, energy prices have fallen 

dramatically, with the average monthly spot price of West Texas Intermediate crude oil falling from 

$106 per barrel in June 2014 to $51 per barrel in February 2015, a drop of 52 percent (U.S. Dept. of 

Energy, Energy Information Administration, 2015j). Deepwater projects tend to operate on a longer time 

scale and projects in the middle of execution would not cease mid-operations because of the downturn. 

Despite the drop in commodity prices, offshore supply vessel utilization and day rates have remained 

relatively flat with almost complete 100 percent utilization of all supply vessel size type from the end of 

2014 to the beginning of 2015 (WorkBoat.com, 2015). While ongoing projects continue to progress on 

schedule, it is likely that longer term planning for both shipyards and exploration and production 

companies has scaled back until commodity price forecasts are more favorable.

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined the new information does not 

change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. As discussed in this Supplemental EIS, as well as in Chapter 

4.1.1.20.1 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete information 

regarding the potential impacts of coastal land loss on land use and coastal infrastructure. It is not 

completely known how current subsidence and erosion is impacting industry or whether industry is 

making plans to mitigate current or future impacts. BOEM has proposed a study to evaluate these 

potential effects by surveying industry on current impacts and potential adaptation strategies, but as of the 

publication of this Supplemental EIS, it is unfunded and would take several years before data could be 

available. Therefore, this incomplete information is not likely to be available within the timeline 

contemplated by the NEPA analysis of this Supplemental EIS. Although this incomplete information 

may be relevant to adverse effects because a comprehensive understanding of the potential impacts of 

coastal land loss on coastal infrastructure and land use remains unknown. BOEM used reasonably 

accepted scientific methodologies to extrapolate from existing information on dredged material use to 

mitigate for land loss in completing its analysis and formulating the conclusions presented here. For 

example, in the case of Port Fourchon, dredged material from navigation slips is used to fill in property 

and mitigation habitat areas for wildlife and to act as a barrier to protect Port Fourchon from storm surges 

(Volz, 2013). Like any industrial infrastructure improvements, future adaptations will likely occur on an 

as-needed basis or as new technologies become available. While coastal infrastructure is subject to the 

impacts of coastal land loss and routine tropical storm activity, there is still considerable investment to 

expand, improve, and protect existing infrastructure. Although BOEM does not know when industrial 

infrastructure improvements, such as mitigation for land loss, may occur, the Port Fourchon example 

shows that industry may mitigate as necessary to protect existing and growing infrastructure. Therefore, 

while not completely known, current and future industry adaptation plans for coastal land loss are not 

essential to a reasoned choice among alternatives for this Supplemental EIS (including the No Action and 

an Action alternative). Therefore, given the extensive existing coastal infrastructure, BOEM has 

determined that the unknown information about specific future improvements and adaptations is not 

essential to a reasoned choice among alternatives. 

Summary and Conclusion

BOEM has reexamined the analysis for land use and coastal infrastructure presented in the prior 

2012-2017 Gulf of Mexico EISs based on the additional information presented above. BOEM has 

determined that the new information does not alter the impact conclusion for land use and coastal 

infrastructure presented in the prior 2012-2017 Gulf of Mexico EISs. The analysis and potential impacts 

detailed and updated in those NEPA documents still apply for proposed WPA Lease Sale 248. 
Description of the Environment and Impact Analysis 4-81

4.1.1.20.2. Demographics

BOEM has reexamined the analysis for demographics presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented below. No new information was discovered 

that would alter the impact conclusion for demographics presented in the prior 2012-2017 Gulf of Mexico 

EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents still 

apply for proposed WPA Lease Sale 248. 

A detailed description of demographics, along with the full analyses of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.20.2 of 2012-2017 WPA/CPA Multisale EIS, and updated information is 

provided in Chapter 4.1.1.20.2 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. New information that has become available since 

publication of those NEPA documents is also presented below. 

In general, impact-producing factors that cause employment impacts, such as exploration and 

delineation activities, development and production activities, and coastal infrastructure development, can 

have some impacts on the demographic characteristics of a particular area. However, routine activities 

associated with the WPA proposed action are projected to minimally affect the demography of the 

analysis area. The projected impacts to population arising from a proposed lease sale are calculated by 

multiplying the employment estimates from the mathematical model MAG-PLAN (MMS Alaska-GOM 

Model Using IMPLAN) by an estimate of the number of members in a typical family. The projected 

population increases arising from a proposed lease sale are then divided by the population forecasts in 

Woods & Poole Economics, Inc. (2015), which yields the percentage impacts to population of a proposed 

lease sale. Population impacts from the WPA proposed action are projected to be minimal (<1% of the 

total population) for any EIA in the Gulf of Mexico region. This methodology yields estimates of the 

percent of the population of each EIA that will be dependent on the OCS Program in low-case and highcase scenarios for OCS oil- and gas-related activities. The baseline population patterns and distributions, 

as projected and described in Chapter 4.1.1.20.2.1 of the 2012-2017 WPA/CPA Multisale EIS, are 

unlikely to change as a result of the WPA 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 inmigration projected to occur in focal areas such as Port Fourchon, Louisiana. 

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

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

communities. This is because accidental events typically cause only short-term population movements as 

individuals seek employment related to the event or have their existing employment displaced during the 

event. For a detailed discussion on the employment and demographic impacts of a low-probability 

catastrophic spill, which is not part of the WPA proposed action and not reasonably expected to occur, 

refer to Appendix A. 

The cumulative analysis considers the effects of impact-producing factors related to OCS oil- and 

gas-related activities along with non-OCS oil- and gas-related impact-producing factors. The OCS oiland gas-related factors that could impact the demographics of any area consist of routine activities and 

accidental events arising from prior, current, and future OCS lease sales, including impact-producing 

factors that cause employment impacts (i.e., exploration and delineation activities, development and 

production activities, and coastal infrastructure development), as well as oil spills, rare occurrence 

blowouts, and vessel collisions. The impacts to population arising from the WPA proposed action are 

projected to be minimal (<1% of the total population) for any EIA in the Gulf of Mexico region based on 

the employment estimates from the mathematical model MAG-PLAN for low-case and high-case 

scenarios for OCS oil- and gas-related activities. Accidental events should not have long-term effects on 

the demographic characteristics of the Gulf coastal communities because population movements are 

typically short-term. For a detailed discussion on the employment and demographic impacts of a lowprobability catastrophic spill, which is not part of the WPA proposed action and not reasonably expected

to occur, refer to Appendix A. 

There are numerous non-OCS oil- and gas-related factors that could impact demographics, including 

fluctuations in workforce, net migration, relative income, oil and gas activity in State waters, offshore 
4-82 Western Planning Area Lease Sale 248 Supplemental EIS

LNG activity, trends in tourism activities (refer to Chapter 4.1.1.18), and other economic factors (refer to 

Chapter 4.1.1.20.3). Common approaches in analyzing cumulative effects begin by assembling a list of 

other projects and actions that will likely be associated with the WPA proposed action. However, no such 

list of future projects and actions could be assembled that would be sufficiently current and 

comprehensive to support a cumulative analysis for all 132 of the coastal counties and parishes in the 

analysis area over a 40-year period. Instead, this analysis uses the economic and demographic projections 

from Woods & Poole Economics, Inc. (2015) as a reasonable approximation to define the contributions of 

other likely projects, actions, and trends to the cumulative case.

The WPA proposed action would contribute to the population impacts arising from the overall OCS 

Program. The Economic Impact Areas TX-3, TX-1, LA-2, and LA-3 are projected to have some 

increases in the levels of their populations as a result of an increase in demand for OCS labor from both 

the WPA proposed action and from the overall OCS Program. The WPA proposed action is projected to 

have an incremental contribution of less than 1 percent to the population level in any of the EIAs, in 

comparison to other factors influencing population growth, such as the status of the overall economy, 

fluctuations in workforce, net migration, health trends, and changes in income. Given both the low levels 

of population growth and industrial expansion associated with the WPA proposed action, it is expected 

that the baseline age and racial distribution patterns will continue through the analysis period. 

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

BOEM conducted a search of Internet resources and known data sources related to demographics. 

The primary source of new information is Woods & Poole Economics, Inc. (2015), which is an annual 

update of the data that were used in the WPA 238/246/248 Supplemental EIS and WPA 246/248 

Supplemental EIS. Woods & Poole Economics, Inc. (2015) provides projections of economic and 

demographic variables at the county level, which improves BOEM’s knowledge of the affected 

environment. Table 4-4 presents Woods & Poole Economics, Inc.’s data for BOEM’s Economic Impact 

Areas in 2015. In terms of population and employment, the largest EIAs are TX-3, FL-3, and FL-4; the 

smallest EIAs are LA-1 and MS-1. Table 4-5 presents Woods & Poole Economics, Inc.’s forecasts for 

the EIAs in 2050; the fastest population and employment growth through 2050 is forecast in the Texas 

EIAs, while the slowest growth is forecast in LA-1, LA-4, and MS-1. In general, the projections of 

demographic variables have not changed noticeably from the projections in the prior 2012-2017 Gulf of 

Mexico EISs.

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined the new information does not 

change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. The information below updates or adds to the understanding of 

incomplete or unavailable information for this resource. As discussed in this Supplemental EIS, as well 

as in Chapter 4.1.1.20.2 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete or 

unavailable information regarding demographics in the WPA. This incomplete or unavailable 

information relates to translating employment impacts of OCS oil- and gas-related activities into 

estimated population impacts. This information cannot be obtained at this time due to data limitations 

and the complexity of methodologies needed to accurately estimate population impacts arising from OCS 

oil- and gas-related activities. BOEM plans to initiate a study project to analyze population impacts more 

fully, although this potential study project will not be completed in the timeline contemplated in the 

NEPA analysis of this Supplemental EIS. BOEM used existing information and reasonably accepted 

scientific methodologies to extrapolate from available information in completing the relevant analysis as 

described above. In place of the incomplete or unavailable information, BOEM used the mathematical 

model MAG-PLAN and population forecasts in Woods & Poole Economics, Inc. (2015) to project the 

employment impacts and resulting impacts to population arising from a proposed lease sale. This 

incomplete or unavailable information is unlikely to significantly impact BOEM’s estimates of the 

impacts of OCS lease sales on demographics because MAG-PLAN forecasts fairly limited population 

impacts and the nature of the employment associated with the WPA proposed action is similar to that of 
Description of the Environment and Impact Analysis 4-83

the existing OCS Program. In addition, increases in population arising from lease sales are generally 

positive, not adverse, impacts. Therefore, BOEM has determined that the incomplete or unavailable 

information is not essential to a reasoned choice among alternatives.

Summary and Conclusion

BOEM has reexamined the analysis for demographics presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented above. No new information was discovered 

that would alter the impact conclusion for demographics presented in the prior 2012-2017 Gulf of Mexico 

EISs. The analysis and potential impacts detailed and updated in those NEPA documents still apply for 

proposed WPA Lease Sale 248. 

4.1.1.20.3. Economic Factors

BOEM has reexamined the analysis for economic factors presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented below. No new information was discovered 

that would alter the impact conclusion for economic factors presented in the prior 2012-2017 Gulf of 

Mexico EISs. Further, the analysis and potential impacts detailed and updated in those NEPA documents 

still apply for proposed WPA Lease Sale 248.

A detailed description of economic factors, along with the full analyses of the potential impacts of 

routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.20.3 of the 2012-2017 WPA/CPA Multisale EIS, and updated information 

is provided in Chapter 4.1.1.20.3 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below.

Impact-producing factors such as exploration and delineation activities, development and production 

activities, and coastal infrastructure development can have some impacts on the economic characteristics, 

such as employment, of a particular area. The expected economic impacts of the OCS oil and gas 

industry are estimated using the mathematical model MAG-PLAN. The MAG-PLAN estimates the 

direct, indirect, and induced employment arising from a particular scenario for oil and gas exploration and 

development activities; these scenarios include estimates of activities such as drilling, platform 

installations, and structure removals. As a result of proposed WPA Lease Sale 248, there would be only 

minor economic changes in the Texas, Louisiana, Mississippi, Alabama, and Florida EIAs. This is partly 

because the demand would be met primarily with the existing population and labor force. Most of the 

employment related to proposed WPA Lease Sale 248 is expected to occur in Texas (primarily in the EIA 

TX-3) and in the coastal areas of Louisiana. The WPA proposed action, irrespective of whether one 

analyzes the high-case or low-case production scenario, would not cause employment effects of 

>0.1 percent in any EIA along the Gulf Coast. 

Accidental events associated with the WPA proposed action, such as an oil spill, can cause a number 

of disruptions to local economies. Many of these effects are due to industries that depend on damaged 

resources. However, the impacts of an oil spill can be somewhat broader if companies further along 

industry supply chains are affected. These effects depend on issues such as the duration, methods, and 

logistics of the cleanup operations and the responses of policymakers to a spill. However, the impacts of 

small- to medium-sized spills should be localized and temporary.

The cumulative analysis considers the effects of OCS oil- and gas-related impact-producing factors 

along with non-OCS oil- and gas-related impact-producing factors that may occur and adversely affect 

economic factors in the same general area of the WPA proposed action. The expected economic impacts 

of the OCS oil and gas industry were estimated using the mathematical model MAG-PLAN to determine 

the direct, indirect, and induced employment arising from a particular scenario for oil and gas exploration 

and development activities (i.e., drilling, platform installations, and structure removals). The WPA 

proposed action would not cause employment effects of >0.1 percent in any EIA along the Gulf Coast. 

Oil spills can cause a number of disruptions to local economies; however, small- to medium-sized spills

should have localized, temporary impacts. A low-probability catastrophic spill, which is not part of the 
4-84 Western Planning Area Lease Sale 248 Supplemental EIS

WPA proposed action and not likely expected to occur, would have more noticeable impacts to the 

economy. However, the likelihood of another spill of this scale is quite low. A detailed analysis of a 

low-probability catastrophic spill can be found in Appendix A. 

Non-OCS oil- and gas-related impact-producing factors that can affect economic trends in economic 

areas in the Gulf of Mexico region include State oil and gas activities, commercial, military, 

recreation/tourism (refer to Chapter 4.1.1.18), and numerous other offshore and coastal activities . To 

estimate the cumulative impacts to economic factors from non-OCS oil- and gas-related impact-producing 

factors, BOEM employs the economic and demographic projections from Woods & Poole Economics, 

Inc. (2015); these projections are discussed in Chapter 4.1.1.20.2. 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 oil- and gas-related leasing activity, as well as the continuation of trends in 

other industries important to the region. For example, these forecasts include the contributions of State 

oil and gas activities, renewable energy activities, coastal land use, and tourism-related activities.

The cumulative impacts of the WPA proposed action would be determined by the expected path of 

the economy and by the expected progression of the OCS oil and gas industry in upcoming years. The 

expected path of the overall economy is projected using the data provided by Woods & Poole Economics, 

Inc. (2015). The expected economic impacts of the OCS oil and gas industry in upcoming years are 

estimated using the mathematical model MAG-PLAN. The cumulative impacts of the WPA proposed 

action to the economies along the Gulf Coast are expected to be relatively small.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

BOEM conducted a search of Internet sources and known data sources regarding economic factors. 

Table 4-6 presents updated data from The Office of Natural Resources Revenue (2015) regarding sales 

volumes, sales values, and government revenues received from Federal offshore energy activities in the 

Gulf of Mexico. Panel A of Table 4-6 presents annual data regarding the quantities of royalty-bearing 

and nonroyalty-bearing sales volumes (i.e., sales from offshore operators to firms further along the supply 

chain) for natural gas, natural gas liquids (NGLs), and oil. In FY 2014, royalty-bearing natural gas sales 

continued on a long-term downward trend, falling from 953 million Mcf (thousand cubic feet) in FY 2013 

to 900 million Mcf in FY 2014. Sales volumes of royalty-bearing NGLs increased from 1.511 billion 

gallons in FY 2013 to 1.68 billion gallons in FY 2014, while sales volumes on nonroyalty-bearing NGLs 

decreased from 383 million gallons in FY 2013 to 312 million gallons in FY 2014. Sales volumes of 

royalty-bearing oil increased from 358 million barrels in FY 2013 to 396 million barrels in FY 2014, 

while sales volumes on nonroyalty-bearing oil decreased from 100 million barrels in FY 2013 to 

87 million barrels in FY 2014. Panel B of Table 4-6 presents the sales values of gas, NGLs, and oil 

produced in Federal areas in the Gulf of Mexico. Sales values of oil, natural gas, and NGLs all increased 

in FY 2014 compared with FY 2013. Panel C of Table 4-6 presents data on Federal Government 

revenues received from rental payments, royalty payments, lease sale bonus bids, and other revenue 

sources due to offshore energy activities in the Gulf of Mexico. The Federal Government received 

$7.3 billion in revenues from all sources combined during FY 2014, which was a decline from the 

$8.8 billion received in FY 2013. This decline arose primarily due to the decline in bonus bid revenues. 

In recent months, energy prices have fallen dramatically, which has impacted the affected 

environment for economic factors. In particular, the average monthly spot price of West Texas 

Intermediate crude oil fell from $106 per barrel in June 2014 to $51 per barrel in February 2015, a drop of 

52 percent (USDOE, Energy Information Administration, 2015j). Average spot natural gas prices fell 

37 percent over the same time period. While energy prices are determined by various forces affecting 

supply and demand, the dramatic expansion of domestic onshore energy production has been one of the 

key factors affecting prices. In particular, U.S. crude oil production increased from 7.5 million barrels per 

day in 2013 to 8.7 million barrels per day in 2014, the largest volume increase on record (USDOE, 

Energy Information Administration, 2015k). This oil production growth was driven by growth in the 

Permian region (in Texas and New Mexico), the Eagle Ford region (in Texas), and the Bakken region (in 

North Dakota and Montana) (USDOE, Energy Information Administration, 2015l). 
Description of the Environment and Impact Analysis 4-85

The fall in oil prices has led to lower gasoline prices, which provides consumers with additional 

disposable income. Lower natural gas prices also help certain consumers, as well as manufacturing firms 

that use natural gas as a production input. However, lower energy prices cause various negative 

economic effects, and these effects tend to be more concentrated than the positive effects. First, lower 

prices lower energy firms’ profits. Between the fourth quarters of 2013 and 2014, profits of energy firms 

in the S&P 500 fell 28 percent, and profits are expected to fall farther in 2015 (Silverblatt, 2015). Lower 

energy prices have also led to layoffs (Kell, 2015) and declines in capital investment (USDOE, Energy 

Information Administration, 2015m). The number of active drilling rigs in the U.S. fell to 1,028 in the 

week of April 2, 2015, compared with 1,818 in the same week in 2014 (Baker Hughes, 2015). Offshore 

energy production in the Gulf of Mexico has held up reasonably well in response to lower energy prices, 

in part due to the long life cycle of offshore oil and gas investment projects (Larino, 2015). A number of 

new energy projects in the Gulf have recently come online, which should support offshore production in 

the near term (USDOE, Energy Information Administration, 2015n). However, the number of contracted 

drilling rigs fell from 81 in April 2014 to 62 in April 2015 (IHS Petrodata, 2015). WorkBoat.com (2015) 

reports that day rates and utilization rates for supply boats were roughly comparable in February 2015 

compared with a year earlier, although day rates and utilization rates for small crewboats fell noticeably 

over the same time period. The longer-term effects of the recent declines in energy prices will depend on 

the extent to which they persist. 

The U.S. Department of Energy’s Energy Information Administration has released its 2015 Annual 

Energy Outlook (USDOE, Energy Information Administration, 2015o). This report provides forecasts 

regarding a wide variety of issues related to energy markets. For example, this report provides forecasts 

of the levels of oil and gas production and prices that will occur in Federal Gulf offshore waters through 

2040. In its reference scenario, shallow-water Gulf oil production is forecast to decrease from 

197,000 barrels per day in 2015 to 129,000 barrels per day in 2040. Deepwater Gulf oil production is 

forecast to increase from 1.34 million barrels per day in 2015 to 1.85 million barrels per day in 2040. 

Wellhead oil prices in the Gulf are forecast to gradually increase from an average of $57 per barrel in 

2015 to $141 per barrel in 2040. Shallow-water Gulf natural gas production is forecast to decrease from 

0.395 Tcf in 2015 to 0.283 Tcf in 2019, and then to increase to 0.414 Tcf in 2040. Deepwater Gulf 

natural gas production is forecast to increase from 1.075 Tcf in 2015 to 2.172 Tcf in 2040. The price of 

Gulf natural gas is forecast to gradually increase from 3.29/Mcf in 2015 to 7.80/Mcf in 2040. This report 

also notes the uncertainties associated with these forecasts and presents results for various scenarios that 

make different assumptions regarding energy prices, oil and gas resources, and the path of the overall 

economy. 

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change previous conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is 

still incomplete or unavailable information. The information below updates or adds to the understanding 

of incomplete or unavailable information for economic factors. As discussed in this Supplemental EIS, as 

well as in Chapter 4.1.1.20.3 of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified 

incomplete or unavailable information regarding economic factors in the WPA. This information 

primarily relates to the onshore geographic distributions of economic impacts arising from the OCS 

Program. This information is difficult to obtain since most data sources do not adequately differentiate 

between onshore and offshore oil and gas activities. However, BOEM used existing information and 

reasonably accepted scientific methodologies to extrapolate from available information in completing the 

relevant analysis as described above. In particular, BOEM used the most recent version of the MAGPLAN to estimate the impacts of the WPA proposed action and the OCS Program. BOEM also used the 

economic and demographic projections from Woods & Poole Economics, Inc. (2015). In addition, 

BOEM has launched a study project to explore new avenues for improving BOEM’s information 

regarding onshore distributions, although this project will take time to pursue. However, any new 

information regarding onshore distributions of economic impacts is unlikely to significantly change 

BOEM’s estimates of the impacts of the OCS Program. In addition, the economic impacts arising from 

the OCS Program are generally positive, not adverse. Therefore, BOEM has determined that the 

incomplete or unavailable information is not essential to a reasoned choice among alternatives.
4-86 Western Planning Area Lease Sale 248 Supplemental EIS

Summary and Conclusion

BOEM has reexamined the analysis for economic factors presented in the prior 2012-2017 Gulf of 

Mexico EISs based on the additional information presented above. No new information was discovered 

that would alter the impact conclusion for economic factors presented in the prior 2012-2017 Gulf of 

Mexico EISs. The analysis and potential impacts detailed and updated in those NEPA documents still 

apply for proposed WPA Lease Sale 248. 

4.1.1.20.4. Environmental Justice

BOEM has reexamined the analysis for environmental justice presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information presented below. No new information was 

discovered that would alter the impact conclusion for environmental justice presented in the prior 2012-

2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and updated in those 

NEPA documents still apply for proposed WPA Lease Sale 248. 

A detailed description of environmental justice, along with the full analyses of the potential impacts 

of routine activities, accidental events, and cumulative impacts associated with the WPA proposed action, 

are presented in Chapter 4.1.1.20.4 of the 2012-2017 WPA/CPA Multisale EIS, and updated information 

is provided in Chapter 4.1.1.20.4 of the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 

Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of reasonably 

foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 Supplemental EIS. 

The following information is a summary of the resource description and impact analysis incorporated 

from the prior 2012-2017 Gulf of Mexico EISs. Any new information that has become available since 

those NEPA documents were published is presented below. 

The oil and gas industry and its associated support sectors are interlinked and widely distributed along 

the Gulf Coast. Offshore OCS oil- and gas-related industry operations within the WPA may utilize 

onshore facilities located within the WPA, CPA, or both. This analysis focuses on the potential impacts 

to low-income and minority populations living onshore. BOEM conducts a county-level analysis to 

determine the concentration of minority and low-income populations located in the same counties as oiland gas- related onshore coastal infrastructure (refer to Chapter 4.2.1.23.4.1 and Figures 4-26 through 

4-35 of the 2012-2017 WPA/CPA Multisale EIS).

BOEM provides numerous opportunities for public input during the NEPA process. Minority and 

low-income populations are provided the same opportunities as other populations to engage in the 

decisionmaking process. Some of the numerous avenues for public outreach employed by BOEM 

include specific types of notices that are (1) mailed to public libraries; interest groups; industry; ports and 

docks; local, State, and Federal agencies; and federally recognized Indian Tribes; (2) published in local 

newspapers; (3) posted on the Internet; and (4) published in the Federal Register. These notices reflect 

the stages of the NEPA process and include the Notice of Intent to Prepare a Supplemental EIS (NOI) and 

Notice of Availability (NOA) for the Draft and Final Supplemental EISs. A series of specified time 

periods after the NOI and NOA allow for public comments, all of which are considered and addressed. 

The formal scoping process is initiated by the NOI, and public scoping meetings are held in several 

geographically separate cities to allow the public to submit comments and to identify all stakeholders’ 

concerns. All public comments and responses to comments are published in the Draft and Final 

Supplemental EISs. A detailed discussion of the complete scoping process can be found in Chapter 1.4. 

A summary of the scoping comments for this Supplemental EIS can be found in Chapter 5.3.2. 

The following routine activities associated with proposed WPA Lease Sale 248 could potentially 

affect vulnerable communities: potential infrastructure changes/expansions including fabrication yards, 

support bases, and onshore disposal sites for offshore waste; increased commuter and truck traffic; and 

employment changes and immigration. Because of the existing extensive and widespread support system 

for OCS oil- and gas-related industry and associated labor force, the effects of routine events related to 

the WPA proposed action are expected to be widely distributed and to have little impact. Routine 

activities related to a single WPA lease sale are not expected to significantly change the existing 

conditions, such as traffic or the amount of infrastructure. Impacts related to the WPA proposed action on 

minority and low-income populations are expected to be primarily economic in nature and to have a 

limited but positive effect because the WPA proposed action would contribute to the sustainability of 

current industry, related support services, and associated employment, especially in Louisiana where an 
Description of the Environment and Impact Analysis 4-87

extensive concentration of OCS oil- and gas-related infrastructure is located, e.g., Port Fourchon in 

Lafourche Parish. BOEM’s county-level analysis found that, given the existing extensive distribution of 

the industry, associated widespread support system and the limited concentrations of minority and lowincome peoples adjacent to oil and gas infrastructure, the WPA proposed action is not expected to have a 

disproportionate effect on these populations.

Accidental events with impact-producing factors that may be associated with the WPA proposed 

action and that could affect environmental justice include, but are not limited to, oil spills, vessel 

collisions, and chemical/drilling-fluid spills. These factors could negatively affect minority and lowincome populations through direct exposure to oil, dispersants, degreasers, and other chemicals that can 

affect human health; temporary interference with subsistence activities due to temporary waterway 

closures; decreased access to natural resources due to environmental damages, fisheries closures, or 

wildlife contamination; and proximity to onshore disposal sites used in support of oil and chemical spill 

cleanup efforts. Oil, chemical, and drilling fluid spills may be associated with exploration, production, or 

transportation activities that result from the WPA proposed action. Low-income and minority 

populations might be more sensitive to spills in coastal waters than is the general population because of 

their potentially higher dietary reliance on wild coastal resources, reliance on these resources for other 

subsistence purposes such as sharing and bartering, limited flexibility in substituting wild resources with 

purchased ones, and likelihood of participating in cleanup efforts and other mitigating activities. 

As studies of past oil spills have highlighted, different cultural groups can possess varying capacities 

to cope with these types of events (Palinkas et al., 1992). Some low-income and/or minority groups may 

be more reliant on natural resources and/or less equipped to substitute contaminated or inaccessible 

natural resources with private market offerings than higher income level and/or nonminority groups. 

Because lower-income and/or minority populations may live near and may be directly involved with spill 

cleanup efforts, the vectors of exposure can be higher for them than for the general population, increasing 

the potential risks of long-term health effects. Accidental events that could result from a proposed WPA 

action may affect low-income and/or minority populations more than the general population, at least in 

the shorter term. These higher-risk groups may lack financial or social resources and may be more 

sensitive and less equipped to cope with the disruption that these events pose. However, in the long-term, 

these smaller events are not likely to significantly affect minority and low-income populations because of 

their small scale and size. Therefore, the impacts of accidental oil spills, vessel collisions, and 

chemical/drilling fluid spills are not likely to be of sufficient duration to have adverse and 

disproportionate long-term effects for low-income and minority communities in the analysis area. 

The cumulative analysis considers the effects of impact-producing factors related to OCS oil and gas 

activities along with non-OCS oil- and gas-related activities that may occur and adversely affect minority 

and low-income populations in the same general area of the WPA proposed action. 

The OCS oil- and gas-related impact-producing factors that could affect environmental justice issues 

include OCS leasing, exploration, development, and production activities. These impact-producing 

factors may result in potential infrastructure changes/expansions, including fabrication yards, support 

bases, and onshore disposal sites for offshore waste; increased commuter and truck traffic; and 

employment changes and immigration. Accidental events arising from these OCS oil- and gas-related 

activities (i.e., oil spills, vessel collisions, and chemical/drilling-fluid spills), as well as the resultant 

cleanup may temporarily impact low-income populations who may experience direct exposure to 

contaminants through subsistence and cleanup activities. However, this exposure is expected to be small 

scale and short term and not result in disproportionate long-term effects because of the small scale and 

size of these events. A low-probability catastrophic spill, which is not part of the WPA proposed action 

and not likely expected to occur, may also impact minority and low-income populations. A detailed 

analysis of a low-probability catastrophic event can be found in Appendix A. In general, the cumulative 

OCS oil- and gas-related effects are expected to be economic, widely distributed, and to have a limited 

but positive effect on low-income and minority populations. In Louisiana, these positive economic 

effects are expected to be greater because of the existence of an extensive and widespread support system 

for OCS oil- and gas-related activities and the associated labor force, especially in Lafourche Parish 

where Port Fourchon is located. Given the existing distribution of the OCS oil- and gas-related industry 

and the limited concentrations of minority and low-income populations near oil and gas infrastructure and 

based on the county-level analysis, the WPA proposed action and the cumulative OCS Program are not 

expected to have disproportionate high/adverse environmental or health effects on minority or lowincome populations. 
4-88 Western Planning Area Lease Sale 248 Supplemental EIS

Non-OCS oil- and gas-related impact-producing factors cover a wide range of potential impactproducing factors including all human activities, natural events, and processes that are not related to OCS 

oil- and gas-related activities in Federal waters. Some of the human activities that may disproportionately 

affect minority and low-income populations include, but are not limited to, the following: State oil and 

gas activities onshore and in State waters; urbanization; pollution (air, light, noise, garbage dumping, and 

contaminated runoff); commercial/residential/agricultural development; zoning ordinances; community 

development strategies (multi-purpose, single-use); expansions to the Federal, State, and local highway 

systems; expansions to regional port facilities; military activities; demographic shifts (in-migration, outmigration); economic shifts on the national, State and local levels (job creation and job losses); military 

activities; educational systems (quality, availability, expansions, or contractions); family support systems 

(availability, proximity and quality of mental health services, foster care, charity hospital systems, 

addictive disorders rehabilitation centers, family planning services, early-learning programs, etc.); 

governmental functions (municipal waterworks systems, sewage systems, tax structures, revenue 

collection, law enforcement, fire protection, traffic control, voting processes, legislative processes, court 

procedures and processes, real estate property assessments, construction permits, environmental 

protection services, land-use permits, etc.); contraction or expansion of the tourism industry; financial 

system (banking and investment services); State renewable energy activities; river channelization; 

dredging of waterways; State oil and gas activity; and existing infrastructure associated with downstream 

activities such as petrochemical processing; and public health.

While human activities are extensive and nearly all-encompassing, there are a substantial number of 

natural events and processes that may be classified as non-OCS oil- and gas-related impact-producing 

factors that may disproportionally affect low-income and minority populations, including the following: 

oyster reef degradation; saltwater intrusion; sedimentation of rivers; sediment deprivation; barrier island 

migration and erosion; fish kills; red tide; beach strandings; coastal erosion/subsidence; sea-level rise; and 

coastal storms. Both human-induced and natural factors, unrelated to OCS oil- and gas-related activities, 

could affect minority and low-income populations through exposure to high levels of pollution, job loss, 

reduced social services, adverse infrastructure siting, decreased tourism, public health issues, coastal 

erosion, land loss and erosion, reduced opportunities for subsistence activities, and vulnerability of coastal 

communities to name a few. For a detailed discussion of these non-OCS oil- and gas-related impacts to 

low income populations, see Appendix D of the WPA 238/246/248 Supplemental EIS. 

To summarize, cumulative effects will be concentrated in coastal areas, particularly in Louisiana. 

Most OCS Program effects are expected to make a positive contribution to minority and low-income 

populations by helping to maintain current employment levels and contributing to economic stimulation. 

The contribution of the cumulative OCS Program to the cumulative impacts of all factors affecting 

environmental justice is expected to be minor; therefore, the incremental contribution of the WPA 

proposed action to the cumulative impacts would also be minor. State offshore leasing programs have 

similar, although more limited, effects due to their smaller scale. Cumulative effects from onshore 

infrastructure, including waste facilities, are also expected to be minor because existing infrastructure is 

regulated, because little new infrastructure is expected to result in the cumulative case, and because any 

new infrastructure will be subject to relevant permitting requirements. Other human activities and natural 

events and processes, as noted above, also may raise environmental justice issues, as described in 

Appendix D of the WPA 238/246/246 Supplemental EIS. When added to existing State and Federal 

leasing programs, the associated onshore infrastructure, and all of the non-OCS oil- and gas-related 

impact-producing factors, a single WPA lease sale will make only minor contributions to the cumulative 

effects on environmental justice issues.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of various information sources and trade publications (U.S. Department of Health and 

Human Services, National Institutes of Health; USEPA; USDOC, Bureau of the Census and Bureau of 

Labor Statistics; USDHS, Federal Emergency Management Agency; RestoreTheGulf.gov website; 

Deepwater Horizon Claims Center; Deepwater Horizon Oil Spill Portal; Louisiana Department of 

Environmental Quality; Texas Commission on Environmental Quality; Louisiana Recovery Authority; 

Louisiana Office of Community Development; The Greater Lafourche Port Commission; LA1 Coalition; 
Description of the Environment and Impact Analysis 4-89

Rigzone; Oil and Gas Journal; and The Oil Drum), as well as recently published journal articles, was 

conducted to determine the availability of recent information on environmental justice. The search 

revealed the following new information on claims and human health impacts from the Deepwater Horizon

explosion, oil spill, and response. This information is important because it expands our knowledge of the 

baseline environment following the Deepwater Horizon explosion, oil spill, and response.

The remaining Deepwater Horizon medical claims that were on appeal before the U.S. Court of 

Appeals for the Fifth Circuit were dismissed on February 11, 2014, and the effective date of the 

Deepwater Horizon Medical Benefits Settlement is February 12, 2014. The effective date of the 

Deepwater Horizon Economic & Property Damages Settlement is December 8, 2014. The final deadline 

to submit a claim in the Economic & Property Damages Settlement, other than Seafood Compensation 

Program Claims, was June 8, 2015. Seafood claims are handled separately from other economic and 

property claims through the Seafood Compensation Program. The Seafood Compensation Program 

includes $2.3 billion available for seafood claims (Deepwater Horizon Claims Center, 2014). 

Incomplete or Unavailable Information 

Even after evaluating the information above, BOEM has determined that the new information does 

not change the conclusions from the prior 2012-2017 Gulf of Mexico EISs; nevertheless, there is still 

incomplete or unavailable information. As discussed in this Supplemental EIS and in the prior 2012-2017 

Gulf of Mexico EISs, BOEM has identified unavailable information regarding the impacts of the 

Deepwater Horizon explosion, oil spill, and response to environmental justice. This information cannot 

be obtained because long-term health impact studies, subsistence studies, and the NRDA process are 

ongoing, and data from these efforts will be unavailable and unobtainable until the studies and NRDA 

process are complete. In its place, BOEM’s subject-matter experts have used credible existing 

information and applied it using accepted socioeconomic methodologies. In order to fill this data gap, 

BOEM used existing information and reasonably accepted scientific methodologies to extrapolate from 

available information in completing the relevant analysis including limited information that has been 

released after the Deepwater Horizon explosion, oil spill, and response and studies of past oil spills which 

indicate that a low-probability, catastrophic oil spill, which is not part of the WPA proposed action or 

likely expected to occur, may have significant adverse impacts on lower-income and minority 

communities. To date, there has been little concrete evidence that subsistence effects have occurred 

(Brown et al., 2011; Dickey, 2012; King and Gibbons, 2011; Middlebrook et al., 2011; U.S. Dept. of 

Labor, OSHA, 2010a and 2010b), although there is some dispute in the scientific community about 

proper risk assessment standards in seafood contamination research (Rotkin-Ellman et al., 2012; RotkinEllman and Soloman, 2012). In addition, some studies have shown that different cultural groups can 

possess varying levels of coping capacities (Palinkas, 1992), and impacts to social cohesion, including 

increased distrust in government and other institutions, contributed to community anxiety (Tuler et al., 

2009). Also, because lower-income and/or minority populations may live near and be involved directly 

with spill cleanup efforts, the vectors of exposure can be higher for them than for the general population, 

increasing the potential risks of long-term health effects. Therefore, because long-term health impacts to 

low-income and minority populations are unknown, this information may be relevant to the evaluation of 

impacts from the Deepwater Horizon explosion, oil spill, and response to environmental justice. 

However, long-term health studies are pending and will not be available within the timeline contemplated 

in the NEPA analysis of this Supplemental EIS. BOEM will continue to seek additional information as it 

becomes available and bases the previous analysis on the best information currently available. Although 

long-term health impacts to low-income and minority populations may be relevant to this analysis, 

BOEM has determined that the incomplete information is not essential to a reasoned choice among 

alternatives based on the information discussed above. 

Summary and Conclusion

BOEM has reexamined the analysis for environmental justice presented in the prior 2012-2017 Gulf 

of Mexico EISs based on the additional information presented above. BOEM has determined that the 

additional information does not alter the impact conclusion because the information is currently 

inconclusive with regard to environmental justice issues and will remain so for an indefinite period of 
4-90 Western Planning Area Lease Sale 248 Supplemental EIS

time. Therefore, the analysis and potential impacts detailed and updated in the prior 2012-2017 Gulf of 

Mexico EISs still apply for proposed WPA Lease Sale 248. 

4.1.1.21.Species Considered due to U.S. Fish and Wildlife Concerns

BOEM has reexamined the analysis for species considered due to FWS concerns presented in the 

prior 2012-2017 Gulf of Mexico EISs based on the additional information presented below. The species 

considered are the Gulf Coast jaguarundi (Herpailurus yagouaroundi cacomitli), ocelot (Leopardus 

pardalis), South Texas ambrosia (Ambrosia cheiranthifolia), Texas prairie dawn-flower (Hymenoxys 

texana), Texas ayenia (Ayenia limitaris), black lace cactus (Echinocereus reichenbachii), and slender 

rush-pea (Hoffmannseggia tenella). BOEM has only focused on species within coastal counties because 

those are the species that could be potentially impacted by oil and gas development activities, including 

an accidental OCS oil spill. Some species considered due to FWS concerns are discussed in other 

chapters of this Supplemental EIS. The conclusions for the following species can be found in their 

respective chapters: West Indian manatee (Chapter 4.1.1.11 of the prior 2012-2017 Gulf of Mexico 

EISs); green, hawksbill, Kemp’s ridley, leatherback, and loggerhead sea turtles (refer to Chapter 4.1.1.12

of this Supplemental EIS and Chapter 4.1.1.12 of the prior 2012-2017 Gulf of Mexico EISs); and red knot 

(Calidris canutus rufa), Attwater’s greater prairie-chicken (Tympanuchus cupido attwateri), northern 

aplomado falcon (Falco femoralis), piping plover (Charadrius melodus), whooping crane (Grus 

Americana), and mountain plover (Charadrius montanus) (refer to Chapter 4.1.1.14 of this Supplemental 

EIS and Chapter 4.1.1.14 of the prior 2012-2017 Gulf of Mexico EISs). No new information was 

discovered that would alter the impact conclusion for species considered due to FWS concerns presented 

in the prior 2012-2017 Gulf of Mexico EISs. Further, the analysis and potential impacts detailed and 

updated in those NEPA documents still apply for proposed WPA Lease Sale 248.

A detailed description of species considered due to FWS concerns, along with the full analyses of the 

potential impacts of routine activities, accidental events, and cumulative impacts associated with the 

WPA proposed action, can be found in Chapter 4.1.1.21 of the 2012-2017 WPA/CPA Multisale EIS, and 

updated information is provided in Chapter 4.1.1.21 of the WPA 233/CPA 231 Supplemental EIS, WPA 

238/246/248 Supplemental EIS, and WPA 246/248 Supplemental EIS. An additional analysis of 

reasonably foreseeable cumulative impacts can be found in Appendix D of the WPA 238/246/248 

Supplemental EIS. The following information is a summary of the resource description and impact 

analysis incorporated from the prior 2012-2017 Gulf of Mexico EISs. BOEM has found no significant 

new information that has become available since publication of those NEPA documents. 

Adverse impacts due to routine activities resulting from the WPA proposed action, such as 

operational discharges, noise, and marine debris, are possible but unlikely. Lethal effects could occur 

from ingestion of released plastic materials from OCS oil- and gas-related vessels and facilities. 

However, there have been no reports to date on such incidences. Because of the mitigating measures that 

may be implemented (Chapter 2.3.1.3), routine activities (e.g., operational discharges, noise, and marine 

debris) related to the WPA proposed action are not expected to have long-term adverse effects on the size 

and productivity of any of the above-mentioned species or populations (2 mammal species and 5 plant 

species) in the Gulf of Mexico. Greatly improved handling of waste and trash by industry and annual 

awareness training required by the marine debris mitigations are reducing the amount of plastics in the 

ocean, and therefore minimizing the devastating effects on offshore and coastal marine life. The routine 

activities of the WPA proposed action are unlikely to have significant adverse effects on the size and 

recovery of any of the above-mentioned species or population in the GOM due to the distance of most 

activities, the heavy regulation of infrastructure and pipelines, and permitting and siting requirements. 

Accidental oil spills, and spill-response activities resulting from the WPA proposed action have the 

potential to impact small to large areas in the Gulf of Mexico with physical oiling and habitat destruction, 

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 (including tropical storms). 

Adverse impacts due to accidental events are also likely to be minimal because the habitats for the abovementioned species are far from OCS oil- and gas-related activities and are inland. Therefore, the WPA 

proposed action would be expected to have little or no effect on these species of concern. 

The cumulative analysis considers activities that have occurred, are currently occurring, and could 

occur and adversely affect species considered due to FWS concerns. The OCS oil- and gas-related 

activities that could impact species considered due to FWS concerns include operational discharges, 
Description of the Environment and Impact Analysis 4-91

noise, marine debris, oil spills, and spill-response activities. However, as discussed above, these routine 

activities are not anticipated to impact these species because of the mitigations and regulations 

implemented by BOEM, and accidental events are expected to be minimal to these species because these 

habitats are far from OCS oil- and gas-related activities and are inland. A low-probability catastrophic 

spill, which is not part of a WPA proposed action and not likely expected to occur, could impact species 

considered due to FWS concerns and is discussed in Appendix A. 

Non-OCS oil- and gas-related activity that could impact species considered due to FWS concerns

include State oil and gas activities, other governmental and private projects and activities, hurricanes, and 

natural processes and events that may occur that adversely affect wetland habitat. Non-OCS oil- and gasrelated activities posing the greatest potential harm to species considered due to FWS concerns are factors 

such as habitat loss and competition. Impacts may also occur to these species if a hurricane passes over 

an oil spill or causes spills itself. However, at this time, there is no known record of a hurricane crossing 

the path of a large oil spill; the impacts of such have yet to be determined. The experience from 

Hurricanes Katrina and Rita in 2005 was that the oil released during the storms widely dispersed as far as 

the surge reached, reducing impacts from concentrated oil exposure (USDOC, NOAA, 2010). 

Activities outside of OCS oil- and gas-related activity (i.e., non-OCS oil- and gas-related activity) 

have a greater potential to impact species considered in this chapter than the OCS oil- and gas-related 

activities, especially those factors that contribute to habitat loss. Because the species considered due to 

FWS concerns rely on terrestrial habitats to carry out their life-history functions at a considerable distance 

from the GOM, the activities of the WPA proposed action are unlikely to have significant adverse effects 

on the size and recovery of any of the above-mentioned mammal and plant species or populations in 

Texas. Therefore, the incremental contribution of the WPA proposed action would not be likely to result 

in a significant incremental impact on these mammal and plant species within the WPA.

New Information Available Since Publication of the 2012-2017 WPA/CPA Multisale EIS, 

WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental EIS, and WPA 

246/248 Supplemental EIS 

A search of Internet information sources (FWS’s website), as well as recently published journal 

articles, was conducted to determine the availability of recent information on species considered due to 

FWS concerns. The search revealed no new information pertinent to this Supplemental EIS.

Incomplete or Unavailable Information 

After evaluating the information above, BOEM has determined that the previous conclusions from the 

prior 2012-2017 Gulf of Mexico EISs are still valid because no new information on species considered 

due to FWS concerns has been published since the publication of the prior 2012-2017 Gulf of Mexico 

EISs; nevertheless, there is still incomplete or unavailable information. As discussed in Chapter 4.1.1.21 

of the prior 2012-2017 Gulf of Mexico EISs, BOEM has identified incomplete information on the impacts 

to species considered due to FWS concerns as a result of the Deepwater Horizon explosion, oil spill, and 

response because little data have been released to the public. As data continue to be gathered and impact 

assessments completed, a better characterization of the full scope of impacts to populations in the GOM 

from the Deepwater Horizon explosion, oil spill, and response will be available. Relevant data on the 

status of populations after the Deepwater Horizon explosion, oil spill, and response may take years to 

acquire and analyze, and impacts from the Deepwater Horizon explosion, oil spill, and response may be 

difficult or impossible to discern from other factors. Therefore, it is not possible for BOEM to obtain this 

information within the timeline contemplated in the NEPA analysis of this Supplemental EIS, regardless 

of the cost or resources needed. In light of the incomplete or unavailable information, BOEM’s subjectmatter experts have extrapolated available scientifically credible evidence in this analysis. Based on life 

histories of these species and the fact that they live inland, BOEM has determined that the two mammal 

species and five plant species within the WPA were not likely affected to any discernible degree by the 

Deepwater Horizon explosion, oil spill, and response. Although the body of available information is 

incomplete, the information extrapolated from the life history of the species and the distance of the 

Macondo well from their habitats was sufficient to draw reasonable conclusions that these species would 

not have been impacted by the Deepwater Horizon explosion, oil spill, and response; therefore, BOEM 

has determined that the incomplete information is not essential to a reasoned choice among alternatives.
4-92 Western Planning Area Lease Sale 248 Supplemental EIS

Summary and Conclusion

BOEM has reexamined the analysis for species considered due to FWS concerns presented in the 

prior 2012-2017 Gulf of Mexico EISs based on the additional information presented above. No new 

information was discovered that would alter the impact conclusion for species considered due to FWS 

concerns presented in the prior 2012-2017 Gulf of Mexico EISs. The analysis and potential impacts 

detailed and updated in those NEPA documents still apply for proposed WPA Lease Sale 248. 

4.1.2. Alternative B—Exclude the Unleased Blocks Subject to the Topographic 

Features Stipulation

Description of the Alternative

Alternative B differs from Alternative A (the proposed action) by not offering unleased blocks that 

are possibly affected by the proposed Topographic Features Stipulation and which will be offered under 

Alternative A (Chapter 2.3.1.3.1 of this Supplemental EIS and Chapter 2.3.1.3.1 of the 2012-2017 

WPA/CPA Multisale EIS). Blocks subject to the Topographic Features Stipulation include any unleased 

block in which a No Activity Zone or Shunting Zone surrounding a topographic feature is located. There 

are 160 blocks (812,615 ac) in the WPA in which the Topographic Features Stipulation may be applied 

(Figure 2-2). These unleased blocks will not be available for lease under Alternative B. The number of 

unleased blocks that would not be offered under Alternative B represents only a small percentage of the 

total number of blocks to be offered under Alternative A; therefore, it is assumed that the levels of 

activity for Alternative B would be essentially the same as those projected for the WPA proposed action 

(refer to Chapter 2.3.2 for further details). The estimated amount of resources projected to be developed 

under Alternative B is within the same scenario range as for Alternative A, i.e., 0.116-0.200 BBO and 

0.538-0.938 Tcf of gas. 

All of the assumptions, including the four other potential mitigating measures (i.e., the Military Areas 

Stipulation, Protected Species Stipulation, United Nations Convention on the Law of the Sea Royalty 

Payment Stipulation, and the Stipulation on the Agreement between the United States of America and the 

United Mexican States Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico, as 

described in Chapter 2.2.1.3), are the same as for the WPA proposed action (Alternative A). A 

description of Alternative A is presented in Chapter 2.3.1.1. The Topographic Features Stipulation 

would not be applicable with Alternative B because the blocks that could be affected by the Topographic 

Features Stipulation would not be offered for lease. 

Because the incremental contribution of Alternative A (the Proposed Action) to the cumulative 

impacts on topographic features is expected to be slight and because 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, Alternative A is not expected to result in 

adverse impacts greater than Alternative B. Therefore, since both Alternatives A and B minimize the 

potential for adverse impacts to Topographic Features, but since Alternative A better meets the purpose 

and need by providing a greater level of flexibility when considering oil and gas exploration, 

development, and production activities, Alternative A is BOEM’s preferred alternative. 

Effects of the Alternative

The following analyses are based on the scenario for the WPA proposed action (Alternative A). The 

scenario provides assumptions and estimates on the amounts, locations, and timing for OCS oil and gas 

exploration, development, and production operations and facilities, both offshore and onshore. These are 

estimates only and not predictions of what would happen as a result of holding proposed WPA Lease Sale

248. A detailed discussion of the scenario and related impact-producing factors is presented in 

Chapter 3.1 of this Supplemental EIS and Chapter 3.1 of the prior 2012-2017 Gulf of Mexico EISs. 

The analyses of impacts to the various resources under Alternative B are similar to those for 

Alternative A. The reader should refer to the appropriate discussions under Alternative A for 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 the WPA proposed 

action (Chapter 4.1.1) for the following resources: 
Description of the Environment and Impact Analysis 4-93

— Air Quality

— Water Quality

— Coastal Barrier Beaches and Associated

Dunes 

— Wetlands

— Seagrass Communities

— Sargassum Communities 

— Chemosynthetic and Nonchemosynthetic

Deepwater Benthic Communities

— Soft Bottom Benthic Communities

— Marine Mammals

— Sea Turtles

— Diamondback Terrapins 

— Coastal and Marine Birds 

— Fish Resources and Essential Fish Habitat

— Commercial Fisheries

— Recreational Fishing 

— Recreational Resources

— Archaeological Resources

— Human Resources and Land Use

The impacts to some Gulf of Mexico resources under Alternative B would be slightly different from 

the impacts expected under the WPA proposed action (Alternative A). These impacts are described 

below. 

Impacts on Topographic Features 

The potential routine impact-producing factors to the topographic features of the WPA are anchoring 

and structure emplacement or removal, and drilling-effluent and produced-water discharges. Under 

Alternative A, impacts associated with routine OCS oil- and gas-related activity are minimized by the 

application of the Topographic Features Stipulation, which distances bottom-disturbing activity (e.g., the 

drilling of wells, anchor and ground tackle placement, and pipeline emplacement) from topographic 

features. Distancing bottom-disturbing activity from topographic features also minimizes impacts from 

discharges by allowing for dispersion and because the discharges are restricted through USEPA permits. 

The possible accidental impact-producing factors to the topographic features of the WPA are surface and 

subsurface oil spills. The application of the Topographic Features Stipulation under Alternative A 

distances the topographic features from possible oil spills, allowing for dilution as well as allowing for 

any oil released below the water’s surface to float to the surface, reducing the possibility of physical 

contact. A more detailed discussion of these potential impact-producing factors and the appropriate 

mitigating measures that are applied under Alternative A to prevent routine impacts to the topographic 

features is presented in Chapters 2.3.1.3.1 and 4.1.1.6 of this Supplemental EIS; in Chapters 2.3.1.3.1 

and 4.1.1.6 of the prior 2012-2017 Gulf of Mexico EISs; and in Appendix A (“Commonly Applied 

Mitigating Measures”) of the WPA 246/248 Supplemental EIS, which is hereby incorporated by 

reference.

Under Alternative B, the routine impacts associated with OCS oil- and gas-related activity would be 

farther distanced from topographic features because the blocks to which the Topographic Features 

Stipulation could be applied would not be offered for lease. There are 160 blocks (812,615 ac) in the 

WPA in which the Topographic Features Stipulation may be applied (Figure 2-2). All bottom-disturbing 

activity associated with OCS oil- and gas-related activity under Alternative B would occur outside of the 

blocks in which the Topographic Features Stipulation could be applied under Alternative A. The blocks 

in which the Topographic Features Stipulation could be applied would be any block in which a 

topographic feature, a No Activity Zone surrounding a topographic feature, or a shunting zone (i.e., 

1,000-Meter, 1-Mile, 3-Mile, and/or 4-Mile Zone) surrounding a topographic feature is located. Routine 

impacts from OCS oil- and gas-related activities would be eliminated because no activity would occur in 

blocks in which topographic features are located. Accidental impacts would be minimized by allowing 

for greater distance for oil to disperse before possibly reaching a topographic feature.

The reduction of impacts to topographic features associated with Alternative B is essentially the same 

as the reduction of impacts associated with Alternative A. While the unleased blocks subject to the 

Topographic Features Stipulation would not be leased under Alternative B, and therefore all potential 

routine impacts would be completely removed and potential accidental impacts would be further 

distanced from any topographic feature, the application of the Topographic Features Stipulation under 

Alternative A also sufficiently minimizes the potential impacts of routine OCS oil- and gas-related 

activities by requiring bottom-disturbing activity to be distanced from topographic features in order to 

diminish physical impacts to them. 
4-94 Western Planning Area Lease Sale 248 Supplemental EIS

Impacts of Routine and Accidental Events

All 21 protected topographic features of the WPA are located within water depths less than 200 m 

(656 ft) and occupy a small portion of the WPA. Of the potential impact-producing factors that may 

affect the topographic features, anchoring and structure emplacement or removal would be eliminated by 

the adoption of this alternative. Effluent discharge would not be a significant threat to the topographic 

features because blocks near enough to the banks for these events to have an impact on the biota of the 

banks would have been excluded from leasing under this alternative. Thus, the only impact-producing 

factors remaining would be oil spills that could occur from operations in blocks other than those blocks 

excluded from leasing under Alternative B. The potential impacts from oil spills are summarized below 

and are discussed further in Chapters 3.2.1 and 4.1.1.6 of this Supplemental EIS and in Chapters 3.2.1 

and 4.1.1.6 of the prior 2012-2017 Gulf of Mexico EISs. 

Topographic features should be protected from surface oil because the crests of the features are 

deeper than the physical mixing ability of surface oil (Lange, 1985; McAuliffe et al., 1975 and 1981; 

Tkalich and Chan, 2002; Rezak et al., 1983). Topographic features would be unaffected by subsurface 

spills unless they come into contact with the oil. Oil from a subsurface spill is expected to rise to the sea 

surface, based on the specific gravity of GOM oil. An exception to this could occur if oil is released at 

the seafloor under high pressure, having the effect of atomizing the oil into micro-droplets that have very 

little buoyancy. Under these conditions, a subsea oil plume could form and travel laterally with the 

prevailing currents. This can also happen if chemical dispersants are used underwater, forming a plume. 

If a subsea oil plume does form, the oil is expected to be swept clear of the banks because prevailing 

currents travel around the banks rather than over them (Rezak et al., 1983). As the oil travels in the water 

column, it will become diluted from its original concentration. Transient concentrations of oil below 

20 parts per million are not expected to result in lasting harm to a coral reef (Shigenaka, 2001). In 

addition, any subsea oil plume that formed in deep water would not be expected to impact topographic 

features because deepwater currents do not typically transit from deep water up onto the shelf (Pond and 

Pickard, 1983; Inoue et al., 2008). The fact that the topographic features are widely dispersed in the 

WPA, combined with the random nature of spill events, would serve to limit the likelihood of a spill 

occurring near a topographic feature. In addition, the exclusion of blocks subject to the Topographic 

Features Stipulation (i.e., those blocks in which a topographic feature, No Activity Zone surrounding a 

topographic feature, or shunting zone [i.e., 1,000-Meter, 1-Mile, 3-Mile, and/or 4-Mile]) surrounding a 

topographic feature are located) from the proposed WPA lease sale would further distance potential spills 

from the habitat. Chapter 4.1.1.6.3 of the 2012-2017 WPA/CPA Multisale EIS discusses the risk of spills 

interacting with topographic features, especially the Flower Garden Banks, in more detail, and updated 

information is provided in the WPA 233/CPA 231 Supplemental EIS, WPA 238/246/248 Supplemental 

EIS, and WPA 246/248 Supplemental EIS. The currents that move around the banks would likely steer 

any spilled oil around the banks rather than directly upon them, lessening impact severity. In the unlikely 

event that oil from a subsurface spill does reach the biota of a topographic feature, the effects should be 

sublethal for most of the adult sessile biota. Lethal effects would probably be limited to a few coral 

colonies (CSA, 1992 and 1994). If oil from a subsurface spill contacted a coral-covered area, the areal 

extent of coral mortality would be limited, but long-lasting sublethal effects may be incurred by 

organisms surviving the initial effects of a spill (Jackson et al., 1989). Overall, the effects of oil contact 

would be primarily sublethal and impacts would be at the community level. 

Cumulative Impacts

With the exception of the topographic features, the cumulative impacts of Alternative B on the 

environmental and socioeconomic resources of the WPA would be identical to Alternative A. The 

incremental contribution of a WPA proposed action to the cumulative impacts on topographic features is 

expected to be slight, and negative impacts should be restricted by the implementation of the Topographic 

Features Stipulation and site-specific mitigations, the depths of the features, and water currents in the 

topographic feature area.

Summary and Conclusion

Alternative B, if adopted, would prevent any OCS oil- and gas-related activity in blocks subject to the 

Topographic Features Stipulation (i.e., those blocks containing topographic features or their surrounding 
Description of the Environment and Impact Analysis 4-95

protective zones); thus, it would eliminate any potential direct impacts to the biota of those blocks from 

routine oil and gas activities, which otherwise would be conducted within the blocks according to lease 

stipulations. 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 could occur upon oil contacting coral colonies; however, the impacts would be at the 

community level. 

The environmental impacts of Alternative B would be almost indistinguishable from Alternative A 

with the Topographic Features Stipulation in place. There would be an economic impact to the extent that 

economic returns from the excluded lease blocks would not be realized. While the unleased blocks 

subject to the Topographic Features Stipulation would not be leased under Alternative B, and therefore all 

potential routine impacts would be completely removed and potential accidental impacts would be further 

distanced from any topographic feature, the application of the Topographic Features Stipulation under 

Alternative A also sufficiently minimizes the potential impacts of routine OCS oil- and gas-related 

activities by requiring bottom-disturbing activity to be distanced from topographic features in order to 

diminish physical impacts to them. 

4.1.3. Alternative C—No Action

Description of the Alternative

Alternative C is the cancellation of a single proposed WPA lease sale. If this alternative is chosen, 

the opportunity for development of the estimated 0.116-0.200 BBO and 0.538-0.938 Tcf of gas that could 

have resulted from the proposed WPA lease sale would not occur as tentatively scheduled, but it could 

again be contemplated as part of another proposed lease sale in the future Five-Year Program. Proposed 

WPA Lease Sale 248 is the last WPA lease sale in the current Five-Year Program. Typically, in past 

programs, there were planning area lease sales, with one WPA lease sale per year. However, the new 

Five-Year Program may have two Gulfwide lease sales each year, and future lease sales will be dependent 

on decisions made in the next Five-Year Program, as determined in the Final Program document. The No 

Action alternative encompasses the same potential impacts as a decision to delay the proposed WPA lease 

sale to a later scheduled lease sale under the future Five-Year Program, when another decision on whether 

to hold that future lease sale is made. Delay of a proposed WPA lease sale was not considered as a 

separate alternative from Alternative C because the potential impacts are the same, namely that most 

impacts related to Alternative A would not occur as described below. Any potential environmental 

impacts resulting from the proposed WPA lease sale would not occur or would be postponed to a future 

lease sale decision.

Effects of the Alternative

BOEM’s predecessor agency published a report that examined previous exploration and development 

activity scenarios (USDOI, MMS, 2007). The report 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 oiland gas-related activities. In 2006, leases from 92 different lease 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 lease 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 lease sales 

contributed to wells drilled in the Gulf of Mexico, while an average WPA lease sale contributed to 

6 percent of the wells drilled in the WPA.

As in the past, the proposed WPA lease sale would contribute to maintaining the present level of OCS 

oil- and gas-related activity in the Gulf of Mexico. Exploration and development activity, including 

service-vessel trips, helicopter trips, and construction, that would result from the proposed WPA lease 

sale would replace activity resulting from existing leases that have reached, or are near the end of, their 

economic life.

In the short term, however, it is important to note that activities under previous lease sales would 

continue in the Gulf of Mexico, including exploration, development, production, and decommissioning

activities. As a decision on the proposed WPA lease sale will not affect those preexisting leases and 
4-96 Western Planning Area Lease Sale 248 Supplemental EIS

activities related to them, there may still be environmental impacts occurring in the Gulf in the short term, 

even if the proposed WPA lease sale is cancelled.

Environmental Impacts

If the proposed WPA lease sale were to be cancelled, the resulting development of oil and gas would 

most likely be postponed to a future lease 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 the proposed WPA 

lease sale would not significantly change the environmental impacts of overall OCS oil- and gas-related

activity in the long term. The environmental impacts expected to result from the WPA proposed action, 

which are described above, would not occur in the short term, but they would likely be postponed to any 

future lease sale decision.

Economic Impacts 

Although environmental impacts may be reduced or postponed by cancelling the proposed WPA lease 

sale, the economic impacts of cancelling a scheduled lease sale should be given consideration. Chapter 

4.1.1.20.3 of this Supplemental EIS and Chapter 4.1.1.20.3 of the prior 2012-2017 Gulf of Mexico EISs

discuss the potential economic impacts of the WPA proposed action. In the event that the proposed WPA

lease sale is cancelled or postponed, there may be impacts to employment along the Gulf Coast, but these 

impacts are not expected to be significant (e.g., less than 1% of total employment) or long term given the 

existing OCS infrastructure. 

Federal, State, and local governments would have to forgo the revenue that would have been received 

from the proposed WPA lease sale. There could be minor impacts on global energy prices from 

cancelling the proposed WPA lease sale, along with minor changes in energy consumption patterns that 

would result from these price changes.

Other factors may minimize or exacerbate the economic impacts of cancelling the proposed WPA 

lease sale. For example, the longer-term economic impacts of cancelling the proposed WPA lease sale 

could be minimized if they were offset by a larger lease sale at a later date. The economic impacts may 

be exacerbated if additional lease sales are cancelled. The OCS oil and gas industry is dependent on high 

capital investment costs and there may be long lags between the lease sale and the majority of production 

activities. Therefore, firms’ investment and spending decisions are dependent on their confidence that the 

OCS Program will be maintained in the future. In addition, while firms in the OCS oil and gas industry 

are generally likely to be able to weather the cancellation of a single lease sale, the cancellation of 

multiple lease sales could lead to broader damage to firms and workers in the industry or to decisions to 

operate in areas other than the Gulf. These economic impacts would be particularly damaging to the 

coastal counties/parishes in Texas and Louisiana for which the OCS industry as a whole is an important 

component of their economies. 

Summary and Conclusion

Cancelling the proposed WPA lease sale may eliminate the effects described for Alternatives A and B 

(Chapter 4.1.1); however, any single lease sale accounts for only a small percentage of the total OCS oiland gas-related activities. If the proposed WPA lease sale were to be cancelled, the resulting 

development of oil and gas would most likely be postponed to a future lease sale; therefore, the overall 

level of OCS oil- and gas-related activity in the WPA would only be reduced by a small percentage, if 

any. Therefore, the cancellation of the proposed WPA lease sale would not significantly change the 

environmental impacts of overall OCS oil- and gas-related activity in the long term.

Federal, State, and local governments would have to forgo the revenue that would have been received 

from the proposed WPA lease sale. There could be minor impacts on global energy prices from 

cancelling the proposed WPA lease sale, along with minor changes in energy consumption patterns that 

would result from these price changes. Other factors may minimize or exacerbate the economic impacts 

of cancelling the proposed WPA lease sale.
Description of the Environment and Impact Analysis 4-97

4.2. UNAVOIDABLE ADVERSE IMPACTS OF THE PROPOSED ACTION

Unavoidable adverse impacts associated with the WPA proposed action are expected to be primarily 

short term and localized in nature and are summarized below. Adverse impacts from low-probability 

catastrophic events, which are not part of the proposed action and not likely expected to occur, could be 

of longer duration and extend beyond the local area. All OCS oil- and gas-related activities involve 

temporary and exclusive use of relatively small areas of the OCS over the lifetimes of specific projects. 

Lifetimes for these activities can be days, as in the case of seismic surveys; or decades, as in the case of a 

production structure or platform. No activities in the OCS Program involve the permanent or temporary 

use or “taking” of large areas of the OCS on a semicontinuous basis. Cumulatively, however, a multitude 

of individual projects results in a major use of OCS space.

Air Quality: Unavoidable short-term impacts on air quality could occur after large oil spills because 

of evaporation and volatilization of the lighter components of crude oil, combustion from surface burning, 

and aerial spraying of dispersant chemicals. Mitigation of long-term effects from offshore engine 

combustion during routine operations would be accomplished through existing regulations and the 

development of new control emission technology. Short-term effects from spill events are uncontrollable 

and are likely to be aggravated or mitigated by the time of year the spills take place.

Water Quality: Routine offshore operations would cause some unavoidable adverse impacts to 

varying degrees on the quality of the surrounding water. Drilling, construction, overboard discharges of 

drilling mud and cuttings, and pipelaying activities would cause an increase in the turbidity of the affected 

waters for the duration of the activity periods. This, however, would only affect water in the immediate 

vicinity of the construction activity or in the vicinity of offshore structures, rigs, and platforms. 

Accidental spills from platforms and the discharge of produced waters could result in increases of 

hydrocarbon levels and trace metal concentrations in the water column in the vicinity of the platforms. 

Spilled oil from a tanker collision would affect the water surface in combination with dispersant

chemicals used during spill response. A subsurface spill would subject the surface, water column, and 

near-bottom environment to spilled oil and gas released from solution, dispersant chemicals, or emulsions 

of dispersed oil droplets and dispersant chemicals.

Unavoidable impacts to onshore water quality would occur as a result of chronic point- and nonpointsource discharges such as runoff and effluent discharges from existing onshore infrastructure used in 

support of lease sale activities. Vessel traffic contributes to the degradation of water quality by chronic 

low-quantity oil leakage, treated sanitary and domestic waste, bilge water, and contaminants known to 

exist in ship paints. Regulatory requirements of the State and Federal water authorities and some local 

jurisdictions would be applicable to point-source discharges from support facilities such as refineries and 

marine terminals.

Sensitive Coastal Habitats: If an oil spill contacts beaches or barrier islands, the removal of beach 

sand during cleanup activities could result in adverse impacts if the sand is not replaced, and a beach 

could experience several years of small surface residue balls (also called tarballs) washing ashore over 

time, causing an aesthetic impact. Sand borrowing on the OCS for coastal restorations involves the 

taking of a quantity of sand from the OCS and depositing it onshore, essentially moving small products of 

the deltaic system to another location. If sand is left where it is, it would eventually be lost to the deltaic 

system by redeposition or burial by younger sediments; if transported onshore, it would be lost to burial 

and submergence caused by subsidence and sea-level rise.

If an oil spill contacts coastal wetlands, adverse impacts could be high in localized areas. In more 

heavily oiled areas, wetland vegetation could experience suppressed productivity for several years; in 

more lightly oiled areas, wetland vegetation could experience die-back for one season. Epibionts 

(organisms growing) on wetland vegetation and grasses in the tidal zone could be killed, and the 

productivity of tidal marshes for the vertebrates and invertebrates that use them to spawn and develop 

could be impaired. Much of the wetland vegetation would recover over time, but some wetland areas 

could be converted to open water. Some unavoidable impacts could occur during pipeline and other 

related coastal construction, but regulations are in place to avoid and minimize these impacts to the 

maximum extent practicable. Unavoidable impacts resulting from dredging, wake erosion, and other 

secondary impacts related to channel use and maintenance would occur as a result of the WPA proposed 

action. 

Sensitive Coastal and Offshore Biological Habitats: Unavoidable adverse impacts would take place 

if an oil spill occurred and contacted sensitive coastal and offshore biological habitats, such as Sargassum 
4-98 Western Planning Area Lease Sale 248 Supplemental EIS

at the surface; fish, turtles, and marine mammals in the water column; or benthic habitats on the bottom. 

There could be some adverse impacts on organisms contacted by oil, dispersant chemicals, or emulsions 

of dispersed oil droplets and dispersant chemicals that, at this time, are not completely understood, 

particularly in subsurface environments.

Threatened and Endangered Species: Because the proposed WPA lease sale does not in and of itself 

make any irreversible or irretrievable commitment of resources that would foreclose the development or 

implementation of any reasonable and prudent measures to comply with the Endangered Species Act, 

BOEM may proceed with publication of this Supplemental EIS and finalize a decision among these 

alternatives even if consultation is not complete, as described in Section 7(d) of the ESA (also refer to 

Chapter 5.7). Irreversible loss of individuals that are ESA-listed species may occur after a large oil spill

from the acute impact of being oiled or the chronic impact of oil having eliminated, reduced, or rendered 

suboptimal the food species upon which they were dependent. 

Nonendangered and Nonthreatened Marine Mammals: Unavoidable adverse impacts to 

nonendangered and nonthreatened marine mammals would be those that also affect endangered and 

threatened marine mammal species. Routine operation impacts (such as seismic surveys, water quality

and habitat degradation, helicopter disturbance, vessel collision, and discarded trash and debris) would be 

negligible or minor to a population, but they could be lethal to individuals as in the case of a vessel 

collision. A large oil spill would temporarily degrade habitat if spilled oil, dispersant chemicals, or 

emulsions of dispersed oil droplets and dispersant chemicals contact free-ranging pods or spawning 

grounds. 

Coastal and Marine Birds: Unavoidable adverse impacts from routine operations on coastal birds 

could result from helicopter and OCS service-vessel traffic, facility lighting, and floating trash and debris. 

Marine birds could be affected by noise, platform lighting, aircraft disturbances, and trash and debris 

associated with offshore activities. Cross-Gulf migrating species could be affected by lighted platforms, 

helicopter and vessel traffic, and floating trash and debris. If a large oil spill occurs and contacts coastal 

or marine bird habitats, some birds could experience lethal and sublethal impacts from oiling, and birds 

feeding or resting in the water could be oiled and die. Coastal birds coming into contact with oil may 

migrate more deeply into marsh habitats, out of reach from spill responders seeking to count them or 

collect them for rehabilitation. Oil spills and oil-spill cleanup activities could also affect the food species 

for coastal, marine, and migratory bird species. Depending on the time of year, large oil spills could 

decrease the nesting success of species that concentrate nests in coastal environments due to direct effects 

of the spill and also disruption from oil-spill cleanup activities.

Fish Resources, Essential Fish Habitat, Commercial Fisheries, and Recreational Fishing: 

Unavoidable adverse impacts from routine operations are loss of open ocean or bottom areas desired for 

fishing by the presence or construction of OCS oil- and gas-related facilities and pipelines. Loss of gear 

could occur from bottom obstructions around platforms and subsea production systems. Routine 

discharges from vessels and platforms are minor given the available area for fish habitat. If a large oil 

spill occurs, the oil, dispersant chemicals, or emulsions of oil droplets and dispersant chemicals could 

temporarily displace mobile fish species on a population or local scale. There could also be impacts on 

prey and sublethal effects on fish. It is unlikely that fishermen would want, or be permitted, to harvest 

fish in the area of an oil spill, as spilled oil could coat or contaminate commercial fish species, rendering 

them unmarketable.

Recreational Beaches: Unavoidable adverse impacts from routine operations may result in the 

accidental loss overboard of some floatable debris that may eventually come ashore on frequented 

recreational beaches. A large oil spill could make landfall on recreational beaches, leading to local or 

regional economic losses and stigma effects, causing potential users to avoid the area after acute impacts 

have been removed. Some recreational beaches become temporarily soiled by weathered crude oil, and 

small surface residue balls (also called tarballs) may come ashore long after stranded oil has been cleaned 

from shoreline areas. Impacts on recreational beaches from a large oil spill may, at the time, seem 

irreversible, but the impacts are generally temporary. Beaches fouled by a large oil spill would be 

temporarily unavailable to the people who would otherwise frequent them, but only during the period 

between landfall and cleanup of the oil, followed by an indefinite lag period during which stigma effects 

recede from public consciousness.

Archaeological Resources: Unavoidable adverse impacts from routine operations could lead to the 

loss of unique or significant archaeological information if unrecognized at the time an area is disturbed. 

Required archaeological surveys significantly reduce the potential for this loss by identifying potential 
Description of the Environment and Impact Analysis 4-99

archaeological sites prior to an interaction occurring, thereby making avoidance or mitigation of impacts 

possible. A large oil spill could make landfall on or near protected archaeological landmarks to cause 

temporary aesthetic or cosmetic impacts until the oil is cleaned or degrades.

Economic Activity: Net economic, political, and social benefits to the U.S. accrue from the 

production of hydrocarbon resources. Once these benefits become routine, unavoidable adverse impacts 

from routine operations follow trends in supply and demand based on the commodity prices for oil, gas, 

and refined hydrocarbon products. Declines in oil and gas prices can lead to activity ramp downs by 

operators until prices rise. A large oil spill would cause temporary increases in economic activity 

associated with spill-response activity. An increase in economic activity from the response to a large spill 

could be offset by temporary work stoppages that are associated with spill-cause investigations and would 

involve a transfer or displacement of demand to different skill sets. Routine operations affected by new 

regulations that are incremental would not have much effect on the baseline of economic activity; 

however, temporary work stoppages or the introduction of several new requirements at one time, which 

are costly to implement, could cause a drop-off of activity as operators adjust to new expectations or use 

the opportunity to move resources to other basins where they have interests.

4.3. IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES

Irreversible or irretrievable commitment of resources refers to impacts or losses to resources that 

cannot be reversed or recovered. Examples are when a species becomes extinct or when wetlands are 

permanently converted to open water. In either case, the loss is permanent.

Wetlands: An irreversible or irretrievable loss of wetlands and associated biological resources could 

occur if wetlands are permanently lost because of impacts caused by dredging and construction activities 

that displace existing wetlands or from oil spills severe enough to cause permanent die-back of vegetation 

and conversion to open water. Construction and emplacement of onshore pipelines in coastal wetlands 

displace coastal wetlands in disturbed areas that are then subject to indirect impacts like saltwater 

intrusion or erosion of the marsh soils along navigation channels and canals. Ongoing natural and 

anthropogenic processes in the coastal zone, only one of which is OCS oil- and gas-related activity, can 

result in direct and indirect loss of wetlands. Natural losses as a consequence of the coastal area 

becoming hydrologically isolated from the Mississippi River that built it, sea-level rise, and subsidence of 

the delta platform in the absence of new sediment added to the delta plain appear to be much more 

dominant processes impacting coastal wetlands.

Sensitive Nearshore and Offshore Biological Resources: An irreversible loss or degradation of 

ecological habitat caused by cumulative activity tends to be incremental over the short term. Irretrievable 

loss may not occur unless or until a critical threshold is reached. It can be difficult or impossible to 

identify when that threshold is, or would be, reached. Oil spills and chronic low-level pollution can injure 

and kill organisms at virtually all trophic levels. Mortality of individual organisms can be expected to 

occur, and possibly a reduction or even elimination of a few small or isolated populations. The proposed 

biological stipulations, however, are expected to eliminate most of these risks.

Threatened and Endangered Species: Irreversible loss of individuals that are protected species may 

occur after a large oil spill from the acute impact of being oiled or the chronic impact of oil having 

eliminated, reduced, or rendered suboptimal the food species upon which they were dependent. 

Fish Resources, Benthic Invertebrates, and Commercial Fisheries: Irreversible loss of fish and coral

resources, including commercial and recreational species, are caused by structure removal using 

explosives. Fish in proximity to an underwater explosion can be killed. Without the structure to serve as 

habitat area, sessile, attached invertebrates and the fish that live among them are absent. Removing 

structures eliminates these special and local habitats and the organisms living there, including such 

valuable species as red snapper. Continued structure removal, regardless of the technique used, would 

reduce the net benefits to commercial fishing due to the presence of these structures. 

Archaeological Resources: Irreversible loss of a prehistoric or historic archaeological resource can 

occur if bottom-disturbing activity takes place without the surveys, where required, to demonstrate its 

absence before work proceeds. A resource can be completely destroyed, severely damaged, or the 

scientific context badly impaired by well drilling, subsea completions, and platform and pipeline

installation, or sand borrowing. 

Oil and Gas Development: Leasing and subsequent development and extraction of hydrocarbons as a 

result of a WPA proposed action represents an irreversible and irretrievable commitment by the removal 
4-100 Western Planning Area Lease Sale 248 Supplemental EIS

and consumption of nonrenewable oil and gas resources. The estimated amount of resources to be 

recovered as a result of the WPA proposed action is presented in Table 3-1. 

Loss of Human and Animal Life: The OCS oil and gas exploration, development, production, and 

transportation are carried out under comprehensive, state-of-the-art, enforced regulatory procedures 

designed to ensure public and work place safety and environmental protection. Nevertheless, some loss 

of human and animal life may be inevitable from unpredictable and unexpected acts of man and nature 

(i.e., unavoidable accidents, accidents caused by human negligence or misinterpretation, human error, 

willful noncompliance, and adverse weather conditions). Some normal and required operations, such as 

structure removal, can kill sea life in proximity to explosive charges or by removal of the structure that 

served as the framework for invertebrates living on it and the fish that lived with it.

4.4. RELATIONSHIP BETWEEN THE SHORT-TERM USE OF MAN’S ENVIRONMENT 

AND THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY

The short-term effects on various components of the environment in the vicinity of the WPA 

proposed action are related to long-term effects and the maintenance and enhancement of long-term 

productivity. 

Short-Term Use

Short-term refers to the total duration of oil and gas exploration and production activities. Extraction 

and consumption of offshore oil and natural gas is a short-term benefit. Discovering and producing 

domestic oil and gas now reduces the Nation’s dependency on foreign imports. Depleting a 

nonrenewable resource now removes these domestic resources from being available for future use. The 

production of offshore oil and natural gas as a result of the WPA proposed action would provide shortterm energy, and as it delays the increase in the Nation’s dependency on foreign imports, it can also allow 

additional time for ramp-up and development of long-term renewable energy sources or substitutes for 

nonrenewable oil and gas. Economic, political, and social benefits would accrue from the availability of 

these natural resources.

The principle short-term use of the leased areas in the Gulf of Mexico would be for the production of 

0.116-0.200 BBO and 0.538-0.938 Tcf of gas from a typical WPA proposed action. The cumulative 

impacts scenario in this Supplemental EIS extends approximately from 2012 to 2051. The 40-year time 

period is used because it is the approximate longest life span of activities conducted on an individual 

lease. The 40 years following the proposed WPA lease sale is the period of time during which the 

activities and impacting factors that follow as a consequence of the proposed WPA lease sale would be 

influencing the environment. 

The specific impacts of the WPA proposed action vary in kind, intensity, and duration according to 

the activities occurring at any given time (Chapter 3). Initial activities, such as seismic surveying and 

exploration drilling, result in short-term, localized impacts. Development drilling and well workovers 

occur sporadically throughout the life of the WPA proposed action but also result in short-term, localized 

impacts. Activities during the production life of a platform may result in chronic impacts over a longer 

period of time (over 25 years), potentially punctuated by more severe impacts as a result of accidental 

events or a spill. Platform removal is also a short-term activity with localized impacts, including removal 

of the habitat for encrusting invertebrates and fish living among them. Many of the effects on physical, 

biological, and socioeconomic resources discussed in Chapter 4.1.1 are considered to be short term 

(being greatest during the construction, exploration, and early production phases). These impacts would 

be further reduced by the mitigating measures discussed in Chapter 2.2.2. 

The OCS development off Texas and Louisiana 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 WPA proposed action 

could increase these incidental benefits of offshore development. Offshore fishing and diving have 

gradually increased in the past three decades, with offshore structures and platforms becoming the focus 

of much of that activity. As mineral resources become depleted, platform removals would occur and may 

result in a decline in these activities.
Description of the Environment and Impact Analysis 4-101

The short-term exploitation of hydrocarbons for the OCS Program in the Gulf of Mexico may lead to 

long-term impacts on biologically sensitive coastal and offshore resources and areas if a large oil spill

occurs. A spill and spill-response activity could temporarily interfere with commercial and recreational 

fishing, beach use, and tourism in the area where the spill makes landfall and in a wider area based on 

stigma effects. The proposed leasing may also result in onshore development and population increases 

that could cause very short-term adverse impacts to local community infrastructure, particularly in areas 

of low population and minimal existing industrial infrastructure (Chapter 4.1.1.20.1 of the prior 2012-

2017 Gulf of Mexico EISs). 

Relationship to Long-Term Productivity

Long-term refers to an indefinite period beyond the termination of oil and gas production. Over a 

period of time after peak oil production has occurred in the Gulf of Mexico, a gradual easing of the 

specific impacts caused by oil and gas exploration and production would occur as the productive 

reservoirs in the Gulf have been discovered and produced, and have become depleted. The Oil Drum 

(2009) showed a graphic demonstrating that peak oil production in the Gulf occurred in June 2002 at 

1.73 MMbbl/day. Whether or not this date is correct can only be known in hindsight and only after a 

period of years while production continues. At this time, however, the trend is fairly convincing (The Oil 

Drum, 2009). There is disagreement on what future production trends may be in the Gulf of Mexico after 

several operators, British Petroleum among them, announced discoveries over the last 5 years (Oil and 

Gas Journal, 2009) in the Lower Tertiary in ultra-deepwater (>5,000 ft; 1,524 m) with large projected 

reserves. These claims are as yet unproven and there are questions as to the difficulties that may be 

encountered producing these prospects because of their geologic age; burial depth and high-temperature, 

high-pressure in-situ conditions; lateral continuity of reservoirs; and the challenges of producing from 

ultra-deepwater water depths.

The Gulf of Mexico’s large marine ecosystem is considered a Class II, moderately productive 

ecosystem (mean phytoplankton primary production 150-300 gChlorophyll a/m2

-yr [The Encyclopedia of 

Earth, 2008]) based on Sea-viewing Wide Field-of-view Sensor (SeaWiFS) global primary productivity 

estimates (USDOC, NASA, 2003). After the completion of oil and gas production, a gradual ramp-down 

to economic conditions without OCS oil- and gas-related activity would be experienced, while the marine 

environment is generally expected to remain at or return to its normal long-term productivity levels that, 

in recent years, has been described as stressed (The Encyclopedia of Earth, 2008). The Gulf of Mexico’s 

large marine ecosystem shows signs of ecosystem stress in bays, estuaries, and coastal regions (Birkett 

and Rapport, 1999). There is shoreline alteration, pollutant discharge, oil and gas development, and 

nutrient loading. The overall condition for the U.S. section of this large marine ecosystem, according to 

USEPA’s seven primary indicators (Jackson et al., 2000), is good dissolved oxygen, fair water quality, 

poor coastal wetlands, poor eutrophic condition, and poor sediment, benthos, and fish tissue (The 

Encyclopedia of Earth, 2008). 

To help sustain the long-term productivity of the Gulf of Mexico ecosystem, the OCS Program 

provides structures to be used as site-specific artificial reefs and fish-attracting devices for the benefit of 

commercial and recreational fishermen and for sport divers and spear fishers. Approximately 10 percent 

of the oil and gas structures removed from the OCS are eventually used for State artificial reef programs. 

Additionally, the OCS Program continues to improve the knowledge and mitigation practices used in 

offshore development to enhance the safe and environmentally responsible development of OCS oil and 

gas resources.

CHAPTER 5 

CONSULTATION AND COORDINATION

Consultation and Coordination 5-3 

5. CONSULTATION AND COORDINATION

5.1. DEVELOPMENT OF THE PROPOSED ACTION

This Supplemental EIS addresses one proposed Federal OCS oil and gas lease sale, i.e., Lease 

Sale 248 in the WPA of the Gulf of Mexico OCS, as scheduled in the Five-Year Program (USDOI, 

BOEM, 2012a). BOEM conducted early coordination with appropriate Federal and State agencies and 

other concerned parties to discuss and coordinate the prelease process for the proposed WPA lease sale 

and this Supplemental EIS. Key agencies and organizations included the National Oceanic and 

Atmospheric Administration, NOAA’s National Marine Fisheries Service, FWS, U.S. Coast Guard, 

U.S. Department of Defense, USEPA, State governors’ offices, federally recognized Indian Tribes, 

industry, and nongovernmental organizations. 

5.2. CALL FOR INFORMATION AND NOTICE OF INTENT TO PREPARE A 

SUPPLEMENTAL EIS 

On July 9, 2012, the Call for Information (Call) for proposed WPA Lease Sales 233, 238, 246, and 

248 was published in the Federal Register (2012b). The comment period closed on August 8, 2012. 

BOEM received two comment letters in response to the Call. These comments are summarized below in 

Chapter 5.3.1. 

On March 30, 2015, the Notice of Intent to Prepare a Supplemental EIS (NOI) for the proposed WPA 

lease sale was published in the Federal Register (2014a). Additional public notices were distributed via 

the U.S. Postal Service, local newspapers, and the Internet. A 30-day comment period was provided; it 

closed on April 28, 2015. Federal, State, and local governments, federally recognized Indian Tribes, 

nongovernmental organizations, and other interested parties were invited to send written comments to the 

Gulf of Mexico OCS Region on the scope of the Supplemental EIS. BOEM received four comment 

letters in response to the NOI. These comments are summarized below in Chapter 5.3.2. 

5.3. DEVELOPMENT OF THE DRAFT SUPPLEMENTAL EIS 

Scoping for the Draft Supplemental EIS was conducted in accordance with CEQ regulations for 

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 BOEM an opportunity to 

update the Gulf of Mexico OCS Region’s environmental and socioeconomic information base. Public 

scoping meetings were held in Texas and Louisiana on the following dates and at the times and locations 

indicated below: 

Tuesday, April 14, 2015

1:00 p.m. CDT

Hilton Garden Inn

 Houston/Bush Intercontinental Airport

15400 John F. Kennedy Boulevard

Houston, Texas 77032

0 registered attendees

0 speakers

0 verbal comments received

0 written comments received

Thursday, April 16, 2015

1:00 p.m. CDT

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

1201 Elmwood Park Boulevard

New Orleans, Louisiana 70123

1 registered attendee

0 speakers

0 verbal comments received

0 written comments received

5.3.1. Summary of Comments Received in Response to the Call for Information

In response to the Call, BOEM received two comment letters: one letter from the Louisiana 

Department of Natural Resources and one letter from the American Petroleum Institute. The Louisiana 

Department of Natural Resources hopes that BOEM will be more attentive to the State of Louisiana’s 

comments during the prelease planning phase, believes that a better appraisal of coastal effects is 
5-4 Western Planning Area Lease Sale 248 Supplemental EIS

necessary, and believes that BOEM must more efficiently revisit reviews of earlier OCS lease sales to 

determine whether the models and predictive techniques used were accurate. The American Petroleum 

Institute states that annual, predictable lease sales in these planning areas are needed to help ensure 

continued offshore exploration and production in the future because production from lease sales will take 

many years to develop. The American Petroleum Institute further encourages BOEM to pursue 

legislation that will allow the entry into force of the “Agreement between the United States of America 

and the United Mexican States Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of 

Mexico” (Agreement). This Agreement, which was signed after issuance of the Call and entered into 

force on July 18, 2014, governs the development of reservoirs of petroleum and natural gas straddling the 

U.S.-Mexico maritime and continental shelf boundary in the Gulf of Mexico. 

5.3.2. Summary of Scoping Comments

In response to the NOI, four comments were received from Federal agencies, interest groups, 

industry, and the general public on the scope of the Supplemental EIS, significant issues that should be 

addressed, alternatives that should be considered, and mitigating measures. All appropriate scoping 

comments for a lease sale NEPA document were considered in the preparation of the Draft Supplemental 

EIS. The following is a summary of the comments that were provided during the scoping process. 

Choctaw Nation of Oklahoma (email dated April 27, 2015) 

• The Choctaw Nation of Oklahoma stated that archaeological deposits affiliated with 

their Tribe are unlikely to be encountered in the WPA, and they deferred comment to 

other Tribes.

Louisiana Department of Natural Resources, Office of Coastal Management (letter dated 

April 29, 2015) 

• The State of Louisiana urges more thorough documentation of methods and sources 

in the Bureau of Ocean Energy Management’s EISs.

• The Louisiana Office of Coastal Management requests that BOEM revisit specific 

predictions made for earlier lease sales and collect data to evaluate the accuracy of 

models and predictive techniques. 

• The Louisiana Office of Coastal Management is also concerned that indirect and 

cumulative impacts to Louisiana’s coastal resources are not adequately assessed or 

addressed and that Louisiana’s coastal wetlands are disproportionately bearing the 

impacts from OCS oil- and gas-related activities.

• The State of Louisiana supports the expansion of exploration and development of 

Gulf of Mexico energy resources. 

Conoco Philips (letter dated April 28, 2015) 

• Conoco Philips supports BOEM’s efforts to update analyses using best available 

science and supports increased access for oil and gas exploration and development. 

• Conoco Philips recommends that BOEM apply its analysis to operating scenarios that 

accurately reflect actual OCS oil- and gas-related activities that occur on a day-to-day 

basis.

Jean Public (email dated March 30, 2015) 

• Jean Public opposes the proposed action due to the risk of oil spills. 
Consultation and Coordination 5-5 

5.3.3. Additional Scoping Opportunities

Although the scoping process is formally initiated by the publication of the NOI and Call, scoping 

efforts and other coordination meetings continued throughout this NEPA process. Scoping and 

coordination opportunities were also available during BOEM’s requests for information, comments, 

input, and review of its other NEPA documents, including the following: 

• scoping for and draft review of the Five-Year Program EIS;

• scoping for and draft review of the 2012-2017 WPA/CPA Multisale EIS; 

• scoping for and draft review of the WPA 233/CPA 231 Supplemental EIS; 

• scoping for and draft review of the WPA 238/246/248 Supplemental EIS; and 

• scoping for and draft review of the WPA 246/248 Supplemental EIS. 

5.3.4. Cooperating Agency

According to Part 516 of the DOI Departmental Manual, BOEM must invite eligible government 

entities to participate as cooperating agencies when developing an EIS in accordance with the 

requirements of NEPA and CEQ regulations. BOEM must also consider any requests by eligible 

government entities to participate as a cooperating agency with respect to a particular EIS, and then to 

either accept or deny such requests.

The NOI, which was published on March 30, 2015, included an invitation to other Federal and State 

agencies, federally recognized Indian Tribes, and local governments to consider becoming cooperating 

agencies in the preparation of this Supplemental EIS. No Federal, State, or local government agencies or 

federally recognized Indian Tribes requested to participate as a cooperating agency.

5.4. DISTRIBUTION OF THE DRAFT SUPPLEMENTAL EIS FOR REVIEW AND 

COMMENT

BOEM will send copies of the Draft Supplemental EIS to the government, public, and private 

agencies and groups listed below. Local libraries along the Gulf Coast will be provided copies of this 

document; a list of these libraries is available on BOEM’s website at http://www.boem.gov/nepaprocess/. 

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 Oceanic and Atmospheric 

Administration

National Marine Fisheries Service

Department of Defense 

Department of the Air Force 

Department of the Army 

Corps of Engineers 

Department of the Navy

Naval Mine and Anti-Submarine 

Warfare Command

Department of Energy

Strategic Petroleum Reserve PMD

Department of Homeland Security 

U.S. Coast Guard

Department of State

Bureau of Oceans and International 

Environmental and Scientific Affairs

Department of the Interior 

Bureau of Ocean Energy Management

Bureau of Safety and Environmental 

Enforcement 

Fish and Wildlife Service 

Geological Survey

National Park Service

Office of Environmental Policy and 

Compliance 

Office of the Solicitor

Department of Transportation

Pipeline and Hazardous Materials Safety 

Administration

Office of Pipeline Safety
5-6 Western Planning Area Lease Sale 248 Supplemental EIS

Environmental Protection Agency

Region 4 

Region 6 

Marine Mammal Commission

State and Local Agencies 

Louisiana 

Governor’s Office

City of Grand Isle 

City of Morgan City 

City of New Orleans

Department of Culture, Recreation, and 

Tourism

Department of Environmental Quality 

Department of Natural Resources 

Department of Transportation and 

Development 

Department of Wildlife and Fisheries

Houma-Terrebonne Chamber of Commerce 

Jefferson Parish Director

Jefferson Parish President

Lafourche Parish CZM

Lafourche Parish Water District #1

Louisiana Geological Survey 

South Lafourche Levee District 

St. Bernard Planning Commission 

State House of Representatives, Natural 

Resources Committee

State Legislature, Natural Resources 

Committee

Texas

Governor’s Office

Aransas Pass Public Library

Attorney General of Texas

Chambers County Library System

City of Lake Jackson

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 Sea Grant

Texas State Library and Archives

Texas Water Development Board

Federally Recognized Indian Tribes

Alabama-Coushatta Tribe of Texas

Caddo Nation of Oklahoma

Chitimacha Tribe of Louisiana

Choctaw Nation of Oklahoma 

Coushatta Tribe of Louisiana 

Jena Band of Choctaw Indians 

Miccosukee Tribe of Indians of Florida 

Mississippi Band of Choctaw Indians 

Poarch Band of Creek Indians

Seminole Tribe of Florida

Seminole Nation of Oklahoma 

Tunica-Biloxi Indian Tribe of Louisiana 

Industry 

American Petroleum Institute

Area Energy LLC

Baker Atlas

Chevron U.S.A. Inc. 

Coastal Conservation Association

Coastal Environments, Inc. 

Continental Shelf Associates, Inc.

Ecology and Environment 

Energy Partners, Ltd. 

EOG Resources, Inc.

Exxon Mobil Production Company 

Freeport-McMoRan, Inc.

Gulf of Mexico Newsletter

Horizon Marine, Inc. 

Industrial Vehicles International, Inc. 

J. Connor Consultants 

John Chance Land Surveys, Inc. 

Marine Safety Office

Newfield Exploration Company 

Seneca Resources Corporation

Shell Exploration & Production Company 

Stone Energy Corporation 

Strategic Management Services-USA

T. Baker Smith, Inc. 

Texas Geophysical Company, Inc.

The Washington Post 

W & T Offshore, Inc. 

WEAR-TV

Special Interest Groups

American Cetacean Society

Audubon Louisiana Nature Center 

Capital Region Planning Commission 

Center for Marine Conservation

Clean Gulf Associates

Coalition to Restore Coastal Louisiana 
Consultation and Coordination 5-7 

Coastal Conservation Association

Concerned Shrimpers of America

Earthjustice

Gulf and South Atlantic Fisheries 

Foundation, Inc.

Gulf Restoration Network

Houma-Terrebonne Chamber of Commerce

LA 1 Coalition, Inc. 

Louisiana Wildlife Federation

Marine Mammal Commission

Natural Resources Defense Council

Nature Conservancy

Offshore Operators Committee

Restore or Retreat

Roffers Ocean Fishing Forecast Service

Ports/Docks

Louisiana 

Abbeville Harbor and Terminal District

Grand Isle Port Commission

Greater Baton Rouge Port Commission 

Greater Lafourche Port Commission

Lake Charles Harbor and Terminal 

District

Plaquemines Port, Harbor and Terminal 

District

Port of Baton Rouge 

Port of Iberia District

Port of New Orleans

Twin Parish Port Commission 

St. Bernard Port, Harbor and Terminal 

District

West Cameron Port Commission

Texas

Brownsville Navigation District—Port of 

Brownsville 

Port Freeport 

Port Mansfield/Willacy County 

Navigation District

Port of Beaumont 

Port of Corpus Christi Authority 

Port of Galveston

Port of Houston Authority 

Port of Isabel—San Benito Navigation 

District

Port of Port Arthur Navigation District

Educational Institutions/Research Laboratories 

Abilene Christian University

Louisiana Sea Grant College Program

Louisiana State University

Louisiana Tech University

Louisiana Universities Marine Consortium 

Loyola University

McNeese State University

Nicholls State University

Tulane University

University of New Orleans

University of Texas at Arlington

University of Texas at Austin

University of Texas Law School

University of Texas Libraries

5.5. COASTAL ZONE MANAGEMENT ACT

If a Federal agency’s activities or development projects within or outside of the coastal zone will have 

reasonably foreseeable coastal effects in the coastal zone, then the activity is subject to a Federal CD. A 

consistency review will be performed pursuant to the CZMA and CDs will be prepared for each CZMA 

State prior to each of the proposed WPA lease sales. To prepare the CDs, BOEM reviews each CZMA 

State’s Coastal Management Plan and analyzes the potential impacts as outlined in this Supplemental EIS, 

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

CZMA requires that Federal actions that are reasonably likely to affect any land or water use or natural 

resource of the coastal zone be “consistent to the maximum extent practicable” with relevant enforceable 

policies of the State’s federally approved coastal management program (15 CFR part 930 subpart C).

Based on these and other analyses, BOEM’s Gulf of Mexico OCS Region’s Regional Director makes 

an assessment of consistency, which is then sent to the States of Louisiana and Texas for proposed WPA 

lease sales. If a State concurs, BOEM can proceed with the proposed lease sale. A State’s concurrence 

may be presumed when a State does not provide a response within the 60-day review period. A State may 

request an extension of time to review the CD within the 60-day period, which the Federal agency shall 

approve for an extension of 15 days or less. If a State objects, it must do the following under the CZMA: 
5-8 Western Planning Area Lease Sale 248 Supplemental EIS

(1) indicate how BOEM’s prelease proposal is inconsistent with the State’s CMP and 

suggest alternative measures to bring BOEM’s proposal into consistency with the 

State’s CMP; or 

(2) describe the need for additional information that would allow a determination of 

consistency. In the event of an objection, the Federal and State agencies should use 

the remaining portion of the 90-day review period to attempt to resolve their 

differences (15 CFR § 930.43(b)).

At the end of the 90-day review period, the Federal agency shall not proceed with the activity over a 

State agency’s objection unless the Federal agency concludes that, under the “consistent to the maximum 

extent practicable” standard described in 15 CFR § 930.32, consistency with the enforceable policies of 

the CMP is prohibited by existing law applicable to the Federal agency and the Federal agency has clearly 

described, in writing, to the State agency the legal impediments to full consistency; or, the Federal agency 

has concluded that its proposed action is fully consistent with the enforceable policies of the CMP, though 

the State agency objects. 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 prelease activities. 

In the event that there is a serious disagreement between BOEM and a State, either agency may request 

mediation. Mediation is voluntary, and the Secretary of Commerce 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 prelease consistency process. Each Gulf State’s CMP is described in Appendix F of the 

2012-2017 WPA/CPA Multisale EIS.

5.6. ENDANGERED SPECIES ACT

The Endangered Species Act of 1973 (16 U.S.C. §§ 1531 et seq.) establishes a national policy 

designed to protect and conserve threatened and endangered species and the ecosystems upon which they 

depend. BOEM and BSEE are currently in consultation with NMFS and FWS regarding the OCS oil and 

gas program in the Gulf of Mexico, including as it relates to a WPA proposed action. BOEM is acting as 

the lead agency in the ongoing consultation, with BSEE’s assistance and involvement. The programmatic 

consultation, which was reinitiated in 2010, was expanded in scope after the reinitiation of consultation 

by BOEM following the Deepwater Horizon explosion and oil spill, and it will include both existing and 

future OCS oil and gas leases in the Gulf of Mexico over a 10-year period. This consultation also 

considers any changes in baseline environmental conditions following the Deepwater Horizon explosion, 

oil spill, and response. The programmatic consultation will also include postlease activities associated 

with OCS oil- and gas-related activities in the Gulf of Mexico, including G&G and decommissioning

activities. While the programmatic Biological Opinion is in development, BOEM and NMFS have 

agreed to interim consultations on postlease approvals. 

With consultation ongoing, BOEM and BSEE will continue to comply with all reasonable and 

prudent measures and the terms and conditions under the existing consultations, along with implementing 

the current BOEM- and BSEE-required mitigation, monitoring, and reporting requirements. Based on the 

most recent and best available information at the time, BOEM and BSEE will also continue to closely 

evaluate and assess risks to listed species and designated critical habitat in upcoming environmental 

compliance documentation under NEPA and other statutes.

5.7. MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT ACT

Pursuant to Section 305(b) of the Magnuson-Stevens Fishery Conservation and Management Act, 

Federal agencies are required to consult with NMFS on any action that may result in adverse effects to 

EFH. The NMFS published the final rule implementing the EFH provisions of the Magnuson-Stevens 

Fisheries Conservation and Management Act (50 CFR part 600) on January 17, 2002. Certain OCS oiland gas-related activities authorized by BOEM may result in adverse effects to EFH, and therefore, 

require EFH consultation. 

Following the Deepwater Horizon explosion, oil spill, and response, NMFS requested a 

comprehensive review of the existing EFH consultation in a response letter dated September 24, 2010. In 

light of this request, Regional staff of BOEM and NMFS agreed on procedures that would incorporate a 
Consultation and Coordination 5-9 

new programmatic EFH consultation into each prepared Five-Year Program EIS and that began with the 

2012-2017 Five-Year Program. BOEM has an EFH Assessment (Appendix D of the 2012-2017 

WPA/CPA Multisale EIS) that describes the OCS proposed activities, analyzes the effects of the proposed 

activities on EFH, and identifies proposed mitigating measures. The programmatic EFH consultation, 

which covers proposed WPA Lease Sales 246 and 248, was initiated with the distribution and review of 

the 2012-2017 WPA/CPA Multisale EIS and with the subsequent written communications between 

BOEM and NMFS. These documents formalized the conservation recommendations put forth by NMFS 

and by BOEM’s acceptance and response to these recommendations. While the necessary components of 

the EFH consultation are complete (as per BOEM’s June 8, 2012, response letter to NMFS), there is 

ongoing coordination among NMFS, BOEM, and BSEE. This coordination includes annual reports from 

BOEM to NMFS, meetings with Regional staff, and discussions of mitigation and relevant topics. All 

agencies will continue to communicate for the duration of the Five-Year Program.

5.8. NATIONAL HISTORIC PRESERVATION ACT

In accordance with the National Historic Preservation Act (54 U.S.C. § 300101 et seq.), Federal 

agencies are required to consider the effect of their undertakings on historic properties. The 

implementing regulations for Section 106 of the National Historical Preservation Act, issued by the 

Advisory Council on Historic Preservation (36 CFR part 800), specify the required review process. 

Because of the extensive geographic area analyzed in this Supplemental EIS and because there will be no 

adverse effects to historic properties as a result of a proposed WPA lease sale, BOEM will complete its 

Section 106 review process once BOEM has performed the necessary site-specific analysis of postlease 

permitted or approved activities. Additional consultations with the Advisory Council on Historic Places, 

State historic preservation offices, federally recognized Indian tribes, and other consulting parties may 

take place at that time, if appropriate. Refer to Chapter 4.1.1.19 for more information on this review 

process.

As an early planning effort, BOEM initiated a request for comment on the NOI for proposed WPA 

Lease Sale 248 via a formal letter on April 1, 2015. That letter was addressed to each of the affected Gulf 

Coast States (Texas and Louisiana) and federally recognized Indian Tribes, including the AlabamaCoushatta Tribe of Texas, Caddo Nation of Oklahoma, Chitimacha Tribe of Louisiana, Choctaw Nation 

of Oklahoma, Coushatta Tribe of Louisiana, Jena Band of Choctaw Indians, Miccosukee Tribe of Indians 

of Florida, Mississippi Band of Choctaw Indians, Poarch Band of Creek Indians, Seminole Tribe of 

Florida, Seminole Nation of Oklahoma, and Tunica-Biloxi Indian Tribe of Louisiana. A 30-day comment 

period was provided. The Choctaw Nation of Oklahoma responded via email on April 27, 2015, stating 

that the WPA lies outside of their Tribe’s area of historic interest and that they deferred comment under 

the National Historic Preservation Act to the other tribes that had been contacted. No further responses 

were received beyond the 30-day scoping period timeline for the NOI, and no requests for consultation 

were received. BOEM will continue to impose mitigating measures and monitoring and reporting 

requirements to ensure that historic properties are not affected by the proposed undertakings. BOEM will 

reinitiate the consultation process with the affected parties should such circumstances warrant further 

consultation. 

Historic Preservation Fund

In 1977 the Historic Preservation Fund (54 U.S.C. §§ 303101-303103) was established to assist State 

and Tribal Historic Preservation Officers in their efforts to protect and preserve historic properties as set 

forth in the requirements of the National Historic Preservation Act. The Historic Preservation Fund is 

authorized at $150 million per year, fully funded from OCS oil and gas revenues payable to the United 

States under Section 9 of the OCSLA (43 U.S.C. § 1338). However, these funds are available for 

expenditure only when appropriated by Congress, which has never fully appropriated the available funds. 

Since inception, approximately $3.3 billion of the Historic Preservation Fund remains unappropriated 

(National Conference of State Historic Preservation Officers, 2015). 

The Historic Preservation Funds’ monies may be used directly by State Historic Preservation 

Officers/Tribal Historic Preservation Officers or passed on as subgrants and contracts to public and 

private agencies, nonprofit organizations, educational institutions, and individuals. Eligible preservation 

projects include historic properties’ survey and inventory, National Register of Historic Places’ 
5-10 Western Planning Area Lease Sale 248 Supplemental EIS

nominations, preservation education, architectural planning, historic structure reports, community 

preservation planning, and brick and mortar repairs to buildings (USDOI, NPS, 2014). These historic 

preservation programs can further catalyze community and neighborhood revitalization, job creation, and 

economic development, primarily through heritage tourism and the rehabilitation of historic properties 

through the Federal Rehabilitation Tax Credit, which is administered by State Historic Preservation 

Officers. Since the Historic Preservation Fund was implemented in 1977, the Federal Rehabilitation Tax 

Credit program nationwide has rehabilitated nearly 39,000 buildings, created 2.4 million jobs, created 

140,000 low- and moderate-income housing units, and leveraged $109 billion in non-Federal investment 

(National Conference of State Historic Preservation Officers, 2014; USDOI, NPS, 2014). In FY 2015, 

Congress allocated a total of $56.41 million from the Historic Preservation Fund, of which $46.925 

million was awarded to State Historic Preservation Officers and $8.985 million was awarded to Tribal 

Historical Preservation Officerss. An additional $500,000 was awarded for projects that will increase 

diversity in the National Register of Historic Places and the National Historic Landmarks programs 

(National Conference of State Historic Preservation Officers, 2015). 

5.9. GOVERNMENT-TO-GOVERNMENT

In accordance with Executive Order 13175, “Consultation and Coordination with Indian Tribal 

Governments,” Federal agencies are required to establish regular and meaningful consultation and 

collaboration with Tribal officials in the development of Federal policies that have Tribal implications, to 

strengthen the United States’ government-to-government relationships with Indian tribes, and to reduce 

the imposition of unfunded mandates upon Indian tribes. BOEM initiated a request for comment on the 

NOI for proposed WPA Lease Sale 248 via a formal letter on April 1, 2015. That letter was addressed to 

each of the affected Gulf Coast States (Texas and Louisiana) and federally recognized Indian Tribes, 

including the Alabama-Coushatta Tribe of Texas, Caddo Nation of Oklahoma, Chitimacha Tribe of 

Louisiana, Choctaw Nation of Oklahoma, Coushatta Tribe of Louisiana, Jena Band of Choctaw Indians, 

Miccosukee Tribe of Indians of Florida, Mississippi Band of Choctaw Indians, Poarch Band of Creek 

Indians, Seminole Tribe of Florida, Seminole Nation of Oklahoma, and Tunica-Biloxi Indian Tribe of 

Louisiana. A 30-day comment period was provided. The Choctaw Nation of Oklahoma responded via 

email on April 27, 2015, stating that the WPA lies outside of their Tribe’s area of historic interest and that 

they deferred comment under the National Historic Preservation Act to the other tribes that had been 

contacted. No other responses were received.

On March 4, 2015, BOEM also sent a formal letter to each of the above-mentioned tribes notifying 

them of the development of the 2017-2022 Outer Continental Shelf Oil and Gas Leasing Draft Proposed 

Program and the Gulf of Mexico Geological and Geophysical Activities Programmatic EIS. This letter 

was intended to be the first step of a long-term and broad consultation effort between BOEM and the 

Gulf-area tribes, inclusive of all BOEM activities that may occur under the Draft Proposed Program, as 

well as ongoing activities including, but not limited to, WPA Lease Sale 248. As of this writing, no 

formal responses have been received in response to the March 4, 2015, letter; however, informal 

discussions with designated Tribal representatives are ongoing to determine if any of the individual tribes 

desire continued consultations on these issues. 

The Poarch Band of Creek Indians has indicated that they do not have any specific concerns with 

BOEM’s activities on the OCS, but they would like to continue to receive notifications on BOEM’s

activities (McCullers, official communication, 2015). Additionally, the Jena Band of Choctaw has 

indicated a general concern over adverse effects to documented or undocumented prehistoric and historic 

sites in the lease sale area and requests to be notified should such effects occur, as well as to continue 

being notified on BOEM’s activities (Shively, official communication, 2015a and 2015b).

BOEM has also analyzed environmental justice issues for minority and low-income populations, 

which is broadly applicable to federally recognized Indian Tribes. Further information on that analysis 

can be found in Chapter 4.1.1.20.4. 
CHAPTER 6 

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6-22 Western Planning Area Lease Sale 248 Supplemental EIS

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gas lease sales: 2014-2016; Western Planning Area Lease Sales 238, 246, and 248—final 

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CHAPTER 7 

PREPARERS

Preparers 7-3 

7. PREPARERS

Gary D. Goeke, Chief, Environmental Assessment Section

Lissa Lyncker, Unit Supervisor, Environmental Protection Specialist 

Tershara Matthews, Unit Supervisor, Environmental Protection Specialist

Michelle K. Nannen, NEPA Coordinator, Environmental Scientist

Ariel White, NEPA Co-Coordinator, Environmental Scientist 

Ross Del Rio, NEPA Co-Coordinator, Environmental Scientist

Tim Holder, Headquarters’ Coordinator, Environmental Protection Specialist

Pat Adkins, Information Management Specialist 

Kenneth Ashworth, Environmental Scientist 

Bruce Baird, Biologist 

Mark Belter, Marine Biologist

Darice K. Breeding, Environmental Protection Specialist 

Brian Cameron, Environmental Scientist

Alicia Caporaso, Marine Archaeologist

Sindey Chaky, Environmental Protection Specialist 

Leonard Coates, Supervisor, Mapping and Automation Section 

Kasey Couture, Program Analyst 

Thierry DeCort, Chief, Geological and Geophysical Section 

Chris DuFore, Oceanographer

Stephanie Gambino, Chief, Biological/Social Sciences Section 

Donald (Tre) W. Glenn III, Protected Species Biologist 

Mike Gravois, Geographer

Allison Hernandez, Protected Species Biologist 

Jose Hernandez, Physical Scientist

Chin (Chester) Hua Huang, Meteorologist 

Jack Irion, Unit Supervisor, Marine Archaeologist 

Mark Jensen, Economist

Matthew Johnson, Marine Biologist

Douglas Jones, Senior Marine Archaeologist

Agatha-Marie Kaller, Unit Supervisor, Marine Biologist

Paula (Kaye) London, Protected Species Biologist

Christopher Lopinto, Data Quality Analyst 

Charles (Jay) McCreery, Physical Scientist

Margaret Metcalf, Chief, Physical/Chemical Sciences Section

Deborah Miller, Technical Editor

Megan Biven, Economist 

Michael Miner, Geologist

David P. Moran, Biologist 

Mark Mueller, Marine Ecologist

Christopher Oos, Geographer 

S. Erin O’Reilly, Physical Scientist

Catherine Rosa, Environmental Assessment Program Specialist

Shane Stradley, Geographer 

Toby Wraye, Information Management Specialist 

CHAPTER 8 

GLOSSARY

Glossary 8-3 

8. GLOSSARY 

Acute—Sudden, short term, severe, critical, 

crucial, intense, but usually of short duration. 

Anaerobic—Capable of growing in the absence of 

molecular oxygen.

Annular preventer—A component of the 

pressure control system in the BOP that forms 

a seal in the annular space around any object 

in the wellbore or upon itself, enabling well 

control operations to commence.

Anthropogenic—Coming from human sources, 

relating to the effect of humankind on nature. 

API gravity—A standard adopted by the 

American Petroleum Institute for expressing 

the specific weight of oil.

Aromatic—Class of organic compounds 

containing benzene rings or benzenoid 

structures.

Attainment area—An area that is shown by 

monitored data or by air-quality modeling 

calculations to be in compliance with primary 

and secondary ambient air quality standards 

established by USEPA. 

Barrel (bbl)—A volumetric unit used in the 

petroleum industry; equivalent to 42 U.S. 

gallons or 158.99 liters. 

Benthic—On or in the bottom of the sea. 

Biological Opinion—The FWS or NMFS 

evaluation of the impact of a proposed action 

on endangered and threatened species, in 

response to formal consultation under 

Section 7 of the Endangered Species Act.

Block—A geographical area portrayed on official 

BOEM protraction diagrams or leasing maps 

that contains approximately 2,331 ha (9 mi2

).

Blowout—An uncontrolled flow of fluids below 

the mudline from appurtenances on a wellhead 

or from a wellbore.

Blowout preventer (BOP)—One of several 

valves installed at the wellhead to prevent the 

escape of pressure either in the annular space 

between the casing and drill pipe or in open 

hole (i.e., hole with no drill pipe) during 

drilling completion operations. Blowout 

preventers on jackup or platform rigs are 

located at the water’s surface; on floating 

offshore rigs, BOPs are located on the 

seafloor.

Bottom kill—A wild well-control procedure 

involving the intersection of an uncontrolled 

well with a relief well for the purpose of 

pumping heavy mud or cement into the wild 

well to stanch the flow of oil or gas (the wellcontrol strategy for the Macondo spill 

deployed in mid-July 2010 that resulted in the 

successful capping of the well).

Cetacean—Aquatic mammal of the order Cetacea, 

such as whales, dolphins, and porpoises. 

Chemosynthetic—Organisms that obtain their 

energy from the oxidation of various inorganic 

compounds rather than from light 

(photosynthetic). 

Coastal waters—Waters within the geographical 

areas defined by each State’s Coastal Zone 

Management Program.

Coastal wetlands—forested and nonforested 

habitats, mangroves, and marsh islands 

exposed to tidal activity. These areas directly 

contribute to the high biological productivity 

of coastal waters by input of detritus and 

nutrients, by providing nursery and feeding 

areas for shellfish and finfish, and by serving 

as habitat for birds and other animals.

Coastal zone—The coastal waters (including the 

lands therein and thereunder) and the adjacent 

shorelands (including the waters therein and 

thereunder) strongly influenced by each other 

and in proximity to the shorelines of several 

coastal states; the zone includes islands, 

transitional and intertidal areas, salt marshes, 

wetlands, and beaches, and it extends seaward 

to the outer limit of the United States 

territorial sea. The zone extends inland from 

the shorelines only to the extent necessary to 

control shorelands, the uses of which have a 

direct and significant impact on the coastal 

waters. Excluded from the coastal zone are 

lands the use of which is by law subject to the 

discretion of or which is held in trust by the 

Federal Government, its officers, or agents

(also refer to State coastal zone boundaries). 

Completion—Conversion of a development well 

or an exploration well into a production well. 

Condensate—Liquid hydrocarbons produced with 

natural gas; they are separated from the gas by 

cooling and various other means. Condensates 

generally have an API gravity of 50°-120°. 
8-4 Western Planning Area Lease Sale 248 Supplemental EIS

Continental margin —The ocean floor that lies 

between the shoreline and the abyssal ocean 

floor, includes the continental shelf, 

continental slope, and continental rise.

Continental shelf—General term used by 

geologists to refer to the continental margin 

province that lies between the shoreline and 

the abrupt change in slope called the shelf 

edge, which generally occurs in the Gulf of 

Mexico at about the 200-m (656-ft) water 

depth. The continental shelf is characterized 

by a gentle slope (about 0.1°). This is 

different from the juridical term used in 

Article 76 of the United Nations Convention 

on the Law of the Sea Royalty Payment (refer 

to the definition of Outer Continental Shelf). 

Continental slope—The continental margin 

province that lies between the continental 

shelf and continental rise, characterized by a 

steep slope (about 3°-6°).

Critical habitat—Specific areas essential to the 

conservation of a protected species and that 

may require special management 

considerations or protection. 

Crude oil—Petroleum in its natural state as it 

emerges from a well or after it passes through 

a gas-oil separator, but before refining or 

distillation. An oily, flammable, bituminous 

liquid that is essentially a complex mixture of 

hydrocarbons of different types with small 

amounts of other substances.

Delineation well—A well that is drilled for the 

purpose of determining the size and/or volume 

of an oil or gas reservoir.

Demersal—Living at or near the bottom of the 

sea.

Development—Activities that take place 

following discovery of economically 

recoverable mineral resources, including 

geophysical surveying, drilling, platform 

construction, operation of onshore support 

facilities, and other activities that are for the 

purpose of ultimately producing the resources. 

Development and Production Plan (DPP)—A 

document that must be prepared by the 

operator and submitted to BOEM for approval 

before any development and production 

activities are conducted on a lease or unit in 

any OCS area other than the western Gulf of 

Mexico.

Development Operations Coordination 

Document (DOCD)—A document that must 

be prepared by the operator and submitted to 

BOEM for approval before any development 

or production activities are conducted on a 

lease in the western Gulf of Mexico.

Development well—A well drilled to a known 

producing formation to extract oil or gas; a 

production well; distinguished from a wildcat 

or exploration well and from an offset well. 

Direct employment—Consists of those workers 

involved in the primary industries of oil and 

gas exploration, development, and production 

operations (Standard Industrial Classification 

Code 13—Oil and Gas Extraction). 

Discharge—Something that is emitted; flow rate 

of a fluid at a given instant expressed as 

volume per unit of time. 

Dispersant—A suite of chemicals and solvents 

used to break up an oil slick into small 

droplets, which increases the surface area of 

the oil and hastens the processes of weathering 

and microbial degradation. 

Dispersion—A suspension of finely divided 

particles in a medium. 

Drilling mud—A mixture of clay, water or 

refined oil, and chemical additives pumped 

continuously downhole through the drill pipe 

and drill bit, and back up the annulus between 

the pipe and the walls of the borehole to a 

surface pit or tank. The mud lubricates and 

cools the drill bit, lubricates the drill pipe as it 

turns in the wellbore, carries rock cuttings to 

the surface, serves to keep the hole from 

crumbling or collapsing, and provides the 

weight or hydrostatic head to prevent 

extraneous fluids from entering the well bore 

and to downhole pressures; also called drilling 

fluid.

Economically recoverable resources—An 

assessment of hydrocarbon potential that takes 

into account the physical and technological 

constraints on production and the influence of 

costs of exploration and development and 

market price on industry investment in OCS 

exploration and production. 

Effluent—The liquid waste of sewage and 

industrial processing. 

Effluent limitations—Any restriction established 

by a State or the USEPA on quantities, rates, 

and concentrations of chemical, physical, 
Glossary 8-5 

biological, and other constituents discharged 

from point sources into U.S. waters, including 

schedules of compliance.

Epifaunal—Animals living on the surface of hard 

substrate.

Essential habitat—Specific areas crucial to the 

conservation of a species and that may 

necessitate special considerations.

Estuary—Coastal semienclosed body of water 

that has a free connection with the open sea 

and where freshwater meets and mixes with 

seawater.

Eutrophication—Enrichment of nutrients in the 

water column by natural or artificial methods 

accompanied by an increase of respiration, 

which may create an oxygen deficiency.

Exclusive Economic Zone—The maritime region 

extending 200 nmi (230 mi; 370 km) from the 

baseline of the territorial sea, in which the 

United States has exclusive rights and 

jurisdiction over living and nonliving natural 

resources.

Exploration Plan (EP)—A plan that must be 

prepared by the operator and submitted to 

BOEM for approval before any exploration or 

delineation drilling is conducted on a lease.

Exploration well—A well drilled in unproven or 

semi-proven territory to determining whether 

economic quantities of oil or natural gas 

deposit are present.

False crawls—Refers to when a female sea turtle 

crawls up on the beach to nest (perhaps) but 

does not and returns to the sea without laying 

eggs.

Field—An accumulation, pool, or group of pools 

of hydrocarbons in the subsurface. A 

hydrocarbon field consists of a reservoir in a 

shape that will trap hydrocarbons and that is 

covered by an impermeable, sealing rock.

Floating production, storage, and offloading 

(FPSO) system—A tank vessel used as a 

production and storage base; produced oil is 

stored in the hull and periodically offloaded to 

a shuttle tanker for transport to shore.

Gathering lines—A pipeline system used to bring 

oil or gas production from a number of 

separate wells or production facilities to a 

central trunk pipeline, storage facility, or 

processing terminal. 

Geochemical—Of or relating to the science 

dealing with the chemical composition of and 

the actual or possible chemical changes in the 

crust of the earth.

Geophysical survey—A method of exploration in 

which geophysical properties and relationships 

are measured remotely by one or more 

geophysical methods.

Habitat—A specific type of environment that is 

occupied by an organism, a population, or a 

community. 

Hermatypic coral—Reef-building corals that 

produce hard, calcium carbonate skeletons and 

that possess symbiotic, unicellular algae 

within their tissues.

Harassment—An intentional or negligent act or 

omission that creates the likelihood of injury 

to wildlife by annoying it to such an extent as 

to significantly disrupt normal behavior 

patterns that include, but are not limited to, 

feeding or sheltering.

Hydrocarbons—Any of a large class of organic 

compounds containing primarily carbon and 

hydrogen. Hydrocarbon compounds are 

divided into two broad classes: aromatic and 

aliphatics. They occur primarily in petroleum, 

natural gas, coal, and bitumens. 

Hypoxia—Depressed levels of dissolved oxygen 

in water, usually resulting in decreased 

metabolism.

Incidental take—Takings that result from, but are 

not the purpose of, carrying out an otherwise 

lawful activity (e.g., fishing) conducted by a 

Federal agency or applicant (refer to Taking).

Indirect employment—Secondary or supporting 

oil- and gas-related industries, such as the 

processing of crude oil and gas in refineries, 

natural gas plants, and petrochemical plants. 

Induced employment—Tertiary industries that 

are created or supported by the expenditures of 

employees in the primary or secondary 

industries (direct and indirect employment), 

including consumer goods and services such 

as food, clothing, housing, and entertainment. 

Infrastructure—The facilities associated with oil 

and gas development, e.g., refineries, gas 

processing plants, etc.

Jack-up rig—A barge-like, floating platform with 

legs at each corner that can be lowered to the 
8-6 Western Planning Area Lease Sale 248 Supplemental EIS

sea bottom to raise the platform above the 

water.

Kick—A deviation or imbalance, typically sudden

or unexpected, between the downward 

pressure exerted by the drilling fluid and the 

upward pressure of in-situ formation fluids or 

gases.

Landfall—The site where a marine pipeline 

comes to shore.

Lease—Authorization that is issued under 

Section 8 or maintained under Section 6 of the 

Outer Continental Shelf Lands Act and that 

authorizes exploration for, and development 

and production of, minerals. 

Lease sale—The competitive auction of leases 

granting companies or individuals the right to 

explore for and develop certain minerals under 

specified conditions and periods of time.

Lease term—The initial period for oil and gas 

leases, usually a period of 5, 8, or 10 years 

depending on water depth or potentially 

adverse conditions. 

Lessee—A party authorized by a lease, or an 

approved assignment thereof, to explore for 

and develop and produce the leased deposits in 

accordance with regulations at 30 CFR part 

250 and 30 CFR part 550. 

Lower marine riser package—The head 

assembly of a subsurface well at the point 

where the riser connects to a blowout 

preventer. 

Macondo—Prospect name given by BP to the 

Mississippi Canyon Block 252 exploration 

well that the Deepwater Horizon rig was 

drilling when a blowout occurred on April 20, 

2010. 

Macondo spill—The name given to the oil spill 

that resulted from the explosion and sinking of 

the Deepwater Horizon rig from the period 

between April 24, 2010, when search and 

recovery vessels on site reported oil at the sea 

surface, and September 19, 2010, when the 

uncontrolled flow from the Macondo well was 

capped.

Marshes—Persistent, emergent, nonforested 

wetlands characterized by predominantly 

cordgrasses, rushes, and cattails.

Military warning area—An area established by 

the U.S. Department of Defense within which 

military activities take place.

Minerals—As used in this document, minerals 

include oil, gas, sulphur, and associated 

resources, and all other minerals authorized by 

an Act of Congress to be produced from 

public lands as defined in Section 103 of the 

Federal Land Policy and Management Act of 

1976. 

Naturally occurring radioactive materials 

(NORM)—naturally occurring material that 

emits low levels of radioactivity, originating 

from processes not associated with the 

recovery of radioactive material. The 

radionuclides of concern in NORM are 

Radium-226, Radium-228, and other isotopes 

in the radioactive decay chains of uranium and 

thorium. 

Nepheloid—A layer of water near the bottom that 

contains significant amounts of suspended 

sediment.

Nonattainment area—An area that is shown by 

monitoring data or by air-quality modeling 

calculations to exceed primary or secondary 

ambient air quality standards established by 

USEPA.

Nonhazardous oil-field wastes (NOW)—Wastes 

generated by exploration, development, or 

production of crude oil or natural gas that are 

exempt from hazardous waste regulation under 

the Resource Conservation and Recovery Act 

(Regulatory Determination for Oil and Gas 

and Geothermal Exploration, Development 

and Production Wastes, dated June 29, 1988, 

53 FR 25446; July 6, 1988). These wastes 

may contain hazardous substances.

Offloading—Unloading liquid cargo, crude oil, or 

refined petroleum products. 

Operational discharge—Any incidental 

pumping, pouring, emitting, emptying, or 

dumping of wastes generated during routine 

offshore drilling and production activities. 

Operator—An individual, partnership, firm, or 

corporation having control or management of 

operations on a leased area or portion thereof. 

The operator may be a lessee, designated 

agent of the lessee, or holder of operating 

rights under an approved operating agreement. 

Organic matter—Material derived from living 

plants or animals.

Outer Continental Shelf (OCS)—All submerged 

lands that comprise the continental margin 
Glossary 8-7 

adjacent to the United States and seaward of 

State offshore lands.

Pelagic—Of or pertaining to the open sea; 

associated with open water beyond the direct 

influence of coastal systems.

Plankton—Passively floating or weakly motile 

aquatic plants (phytoplankton) and animals 

(zooplankton). 

Platform—A steel or concrete structure from 

which offshore development wells are drilled. 

Play—A prospective subsurface area for 

hydrocarbon accumulation that is 

characterized by a particular structural style or 

depositional relationship. 

Primary production—Organic material produced 

by photosynthetic or chemosynthetic 

organisms.

Prior 2012-2017 Gulf of Mexico EISs—Gulf of 

Mexico OCS Oil and Gas Lease Sales: 

2012-2017; Western Planning Area Lease 

Sales 229, 233, 238, 246, and 248; Central 

Planning Area Lease Sales 227, 231, 235, 241, 

and 247, Final Environmental Impact 

Statement (2012-2017 WPA/CPA Multisale 

EIS); Gulf of Mexico OCS Oil and Gas Lease 

Sales: 2013-2014; Western Planning Area 

Lease Sale 233; Central Planning Area Lease 

Sale 231, Final Supplemental Environmental 

Impact Statement (WPA 233/CPA 231 

Supplemental EIS); Gulf of Mexico OCS Oil 

and Gas Lease Sales: 2014-2016; Western 

Planning Area Lease Sales 238, 246, and 248, 

Final Supplemental Environmental Impact 

Statement (WPA 238/246/248 Supplemental 

EIS); and Gulf of Mexico OCS Oil and Gas 

Lease Sales: 2015 and 2016; and Western 

Planning Area Lease Sales 246 and 248, Final 

Supplemental Environmental Impact 

Statement (WPA 246/248 Supplemental EIS)

Produced water—Total water discharged from 

the oil and gas extraction process; production 

water or production brine. 

Production—Activities that take place after the 

successful completion of any means for the 

extraction of resources, including bringing the 

resource to the surface, transferring the 

produced resource to shore, monitoring 

operations, and drilling additional wells or 

workovers.

Province—A spatial entity with common geologic 

attributes. A province may include a single 

dominant structural element such as a basin or 

a fold belt, or a number of contiguous related 

elements.

Ram—The main component of a blowout 

preventer designed to shear casing and tools in 

a wellbore or to seal an empty wellbore. A 

blind shear ram accomplishes the former and a 

blind ram the latter.

Recoverable reserves—The portion of the 

identified hydrocarbon or mineral resource 

that can be economically extracted under 

current technological constraints.

Recoverable resource estimate—An assessment 

of hydrocarbon or mineral resources that takes 

into account the fact that physical and 

technological constraints dictate that only a 

portion of resources can be brought to the 

surface.

Recreational beaches—Frequently visited, sandy 

areas along the Gulf of Mexico shorefront that 

support multiple recreational activities at the 

land-water interface. Included are National 

Seashores, State Park and Recreational Areas, 

county and local parks, urban beachfronts, and 

private resorts.

Refining—Fractional distillation of petroleum, 

usually followed by other processing (e.g., 

cracking).

Relief—The difference in elevation between the 

high and low points of a surface. 

Reserves—Proved oil or gas resources.

Rig—A structure used for drilling an oil or gas 

well.

Riser insertion tube tool—A “straw” and gasket 

assembly improvised during the Macondo spill 

response that was designed to siphon oil and 

gas from the broken riser of the Deepwater 

Horizon rig lying on the sea bottom (an early 

recovery strategy for the Macondo spill in 

May 2010). 

Royalty—A share of the minerals produced from 

a lease paid in either money or “in-kind” to the 

landowner by the lessee.

Saltwater intrusion—Saltwater invading a body 

of freshwater.

Sciaenids—Fishes belonging to the croaker family 

(Sciaenidae).

Seagrass beds—More or less continuous mats of 

submerged, rooted, marine, flowering vascular 
8-8 Western Planning Area Lease Sale 248 Supplemental EIS

plants occurring in shallow tropical and 

temperate waters. Seagrass beds provide 

habitat, including breeding and feeding 

grounds, for adults and/or juveniles of many 

of the economically important shellfish and 

finfish.

Sediment—Material that has been transported and 

deposited by water, wind, glacier, 

precipitation, or gravity; a mass of deposited 

material.

Seeps (hydrocarbon)—Gas or oil that reaches the 

surface along bedding planes, fractures, 

unconformities, or fault planes. 

Sensitive area—An area containing species, 

populations, communities, or assemblages of 

living resources, that is susceptible to damage 

from normal OCS oil- and gas-related 

activities. Damage includes interference with 

established ecological relationships.

Shear ram—The component in a BOP that cuts, 

or shears, through the drill pipe and forms a 

seal against well pressure. Shear rams are 

used in floating offshore drilling operations to 

provide a quick method of moving the rig 

away from the hole when there is no time to 

trip the drill stem out of the hole.

Shoreline Cleanup and Assessment Team—The 

on-the-scene responders for post-spill 

shoreline protection who established priorities, 

standardized procedures, and terminology. 

Spill of National Significance—Designation by 

the USEPA Administrator under 40 CFR § 

300.323 for discharges occurring in the inland 

zone and the Commandant of the U.S. Coast 

Guard for discharges occurring in the coastal 

zone, authorizing the appointment of a 

National Incident Commander for spillresponse activity.

State coastal zone boundary—The State coastal 

zone boundaries for each CZMA-affected 

State are defined at http://

coastalmanagement.noaa.gov/mystate/docs/

StateCZBoundaries.pdf. 

Structure—Any OCS facility that extends from 

the seafloor to above the waterline; in 

petroleum geology, any arrangement of rocks 

that may hold an accumulation of oil or gas. 

Subarea—A discrete analysis area.

Subsea isolation device—An emergency 

disconnection and reconnection assembly for 

the riser at the seafloor.

Supply vessel—A boat that ferries food, water, 

fuel, and drilling supplies and equipment to an 

offshore rig or platform and returns to land 

with refuse that cannot be disposed of at sea.

Taking—To harass, harm, pursue, hunt, shoot, 

wound, kill, trap, capture, or collect any 

endangered or threatened species, or to 

attempt to engage in any such conduct 

(including actions that induce stress, adversely 

impact critical habitat, or result in adverse 

secondary or cumulative impacts). 

Harassments are the most common form of 

taking associated with OCS Program 

activities.

Tension-leg platform (TLP)—A production 

structure that consists of a buoyant platform 

tethered to concrete pilings on the seafloor 

with flexible cable.

Total dissolved solids—The total amount of 

solids that are dissolved in water.

Total suspended particulate matter—The total 

amount of suspended solids in water. 

Total suspended solids—The total amount of 

suspended solids in water. 

Trunkline—A large-diameter pipeline receiving 

oil or gas from many smaller tributary 

gathering lines that serve a large area; 

common-carrier line; main line.

Turbidity—Reduced water clarity due to the 

presence of suspended matter. 

Volatile organic compound (VOC)—Any 

organic compound that is emitted to the 

atmosphere as a vapor.

Water test areas—Areas within the eastern Gulf 

where U.S. Department of Defense research, 

development, and testing of military planes, 

ships, and weaponry take place.

Weathering (of oil)—The aging of oil due to its 

exposure to the atmosphere, causing marked 

alterations in its physical and chemical 

makeup. 
FIGURES

Figures Figures-3

Figure 1-1. Gulf of Mexico Planning Areas, Proposed WPA Lease Sale Area, and Locations of Major Cities.
Figures-4 Western Planning Area Lease Sale 248 Supplemental EIS

Figure 2-1. Location of Proposed Stipulations and Deferrals.
Figures Figures-5

Figure 2-2. Military Warning Areas and Eglin Water Test Areas in the Gulf of Mexico.
Figures-6 Western Planning Area Lease Sale 248 Supplemental EIS

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

Tables Tables-3 

Table 3-1

Projected Oil and Gas in the Gulf of Mexico OCS

Typical Lease Sale OCS Cumulative

(2012-2051)

Western Planning Area

 Reserve/Resource Production

 Oil (BBO) 0.116-0.200 2.510-3.696

 Gas (Tcf) 0.538-0.938 12.539-18.434

Central Planning Area

 Reserve/Resource Production

 Oil (BBO) 0.460-0.894 15.825-21.733

 Gas (Tcf) 1.939-3.903 63.347-92.691

Eastern Planning Area

 Reserve/Resource Production

 Oil (BBO) 0-0.071 0-0.211

 Gas (Tcf) 0-0.162 0.0502

BBO = billion barrels of oil.

Tcf = trillion cubic feet. 
Tables-4 Western Planning Area Lease Sale 248 Supplemental EIS

Table 3-2

Offshore Scenario Information Related to a Typical Lease Sale in the Western Planning Area

Offshore Subareas1

Total WPA2

0-60 m 60-200 m 200-800 m 800-1,600 m 1,600-2,400 m >2,400 m

Wells Drilled

Exploration and Delineation Wells 23-38 7-12 9-16 8-13 3-5 3-5 53-89

 Development and Production Wells 30-49 11-17 13-21 11-18 6-8 6-8 77-121

 Producing Oil Wells 4-6 2 8-13 7-11 3-4 3-4 27-40

 Producing Gas Wells 22-37 7-12 3-5 2-4 1-2 1-2 36-62

Production Structures

 Installed 10-17 1-2 1 1 1 1 15-23

 Removed Using Explosives 7-12 1 0 0 0 0 7-13

 Total Removed 9-16 1-2 1 1 1 1 14-22

Method of Transportation3

 Percent Piped >99% >99% >99% >99% 83->99% 94->99%

 Percent Barged <1% 0% 0% 0% 0% <1%

 Percent Tankered4 0% 0% 0% 0% 0-17% 0-5%

Length of Installed Pipelines (km)5 71-182 NA NA NA NA NA 237-554

Service-Vessel Trips (1,000’s round trips) 21-33 2-3 2-3 17 16-17 16-17 64-75

Helicopter Operations (1,000’s operations) 194-448 19-54 19-24 19-24 19-24 19-24 290-605

1 Refer to Figure 3-1. 2 Subareas totals may not add up to the planning area total because of rounding. 3 100% of gas is assumed to be piped. 4 Tankering is forecasted to occur only in water depths >1,600 m. 5 Projected length of pipelines does not include length in State waters.

NA = not available.
Tables Tables-5

Table 3-3

Offshore Scenario Information Related to OCS Program Activities

in the Gulf of Mexico (WPA, CPA, and EPA) for 2012-2051

Offshore Subareas1

Total OCS2

0-60 m 60-200 m 200-800 m 800-1,600 m 1,600-2,400 m >2,400 m

Wells Drilled

 Exploration and Delineation Wells 2,730-3,900 990-1,390 920-1,350 700-960 770-1,030 790-1,170 6,910-9,827

 Development and Production Wells 3,380-4,820 1,240-1,730 1,130-1,670 860-1,190 950-1,280 970-1,450 8,530-12,180

 Producing Oil Wells 520-701 215-278 704-1,030 574-783 663-873 620-915 3,296-4,605

 Producing Gas Wells 2,510-3,629 885-1,272 306-470 196-287 187-267 250-385 4,334-6,320

Production Structures

 Installed 1,210-1,720 110-160 26-40 25-30 32-33 32-38 1,435-2,026

 Removed Using Explosives 796-1,139 69-104 3-4 0 0 0 868-1,247

 Total Removed 1,090-1,560 100-150 24-34 20-28 23-30 22-33 1,279-1,837

Method of Transportation3

 Percent Piped >99% >99% >99% >99% 87->99% 92->99%

 Percent Barged <1% 0% 0% 0% 0% <1%

 Percent Tankered4 0% 0% 0% 0% 0-13% 0-7%

Length of Installed Pipelines (km)5 10,482-21,121 NA NA NA NA NA 30,428-69,749

Service-Vessel Trips (1,000’s round trips) 1,366-1,942 196-280 111-162 466-619 584-626 587-719 3,310-4,382

Helicopter Operations (1,000’s operations) 24,221-47,322 2,297-4,444 595-1,174 574-1,111 676-1,287 888-1,738 28,710-55,605

1 Refer to Figure 3-1. 2 Subareas totals may not add up to the planning area total because of rounding. 3 100% of gas is assumed to be piped. 4 Tankering is forecasted to occur only in water depths >1,600 m. 5 Projected length of pipelines does not include length in State waters.

NA = not available.
Tables-6 Western Planning Area Lease Sale 248 Supplemental EIS

Table 3-4

Offshore Scenario Information Related to OCS Program Activities

in the Western Planning Area for 2012-2051

Offshore Subareas1

Total WPA2

0-60 m 60-200 m 200-800 m 800-1,600 m 1,600-2,400 m >2,400 m

Wells Drilled

Exploration and Delineation Wells 500-740 170-230 220-320 160-230 70-90 60-80 1,180-1,690

 Development and Production Wells 620-920 220-290 270-400 190-290 80-120 70-100 1,450-2,120

 Producing Oil Wells 74-109 27-38 170-255 125-191 54-77 45-67 495-737

 Producing Gas Wells 476-711 163-222 70-105 45-69 16-23 15-23 785-1,153

Production Structures

 Installed 220-330 20-30 6-10 5-8 2-3 2-3 255-384

 Removed Using Explosives 146-219 14-21 1 0 0 0 160-240

 Total Removed 200-300 20-30 6-8 4-7 2-3 1-2 233-350

Method of Transportation3

 Percent Piped >99% >99% >99% >99% 50->99% 84->99%

 Percent Barged <1% 0% 0% 0% 0% <1%

 Percent Tankered4 0% 0% 0% 0% 0-50% 0-15%

Length of Installed Pipelines (km)5 1,967-4,128 NA NA NA NA NA 5,224-12,339

Service-Vessel Trips (1,000’s round trips) 249-372 35-50 26-36 95-150 38-57 38-56 481-720

Helicopter Operations (1,000’s operations) 4,489-8,987 418-836 125-272 104-209 42-84 42-84 5,220-10,450

1 Refer to Figure 3-1. 2 Subareas totals may not add up to the planning area total because of rounding. 3 100% of gas is assumed to be piped. 4 Tankering is forecasted to occur only in water depths >1,600 m. 5 Projected length of pipelines does not include length in State waters.

NA = not available.
Tables Tables-7 

Table 3-5 

Annual Volume of Produced Water Discharged by Depth

(millions of bbl)

Year Shelf

0-60 m

Shelf

60-200 m

Slope

200-400 m

Deepwater

400-800 m

Deepwater

800-1,600 m

UltraDeepwater

1,601-2,400 m

UltraDeepwater

>2,400 m

Total

2000 370.6 193.1 35.5 25.6 12.2 0.0 0.0 637.0

2001 364.2 185.2 35.0 32.0. 16.6 0.0 0.0 633.0

2002 344.7 180.4 32.5 35.1 21.4 0.0 0.0 614.1

2003 359.4 182.9 31.2 39.0 35.5 0.2 0.0 648.2

2004 346.7 160.5 29.3 36.9 39.2 1.8 0.0 614.4

2005 270.0 113.5 23.1 33.5 43.0 5.8 0.0 488.9

2006 260.3 99.6 20.6 35.1 61.6 12.4 0.0 489.6

2007 307.0 139.3 22.2 40.0 70.6 15.5 0.1 594.7

2008 252.7 118.6 15.9 32.7 60.2 16.1 0.1 496.3

2009 265.2 109.2 19.9 39.2 65.6 25.0 0.1 524.2

2010 278.4 115.7 20.9 40.7 56.8 32.5 0.1 545.1

2011 273.7 117.0 20.7 39.7 67.7 32.2 0.1 551.1

2012 240.7 108.9 20.8 35.0 71.4 32.3 0.1 509.2

2013 248.8 104.2 20.0 33.1 75.9 36.9 0.3 519.2

2014 226.6 91.9 17.1 32.0 72.1 45.0 0.9 485.0

Source: Gonzales, official communication, 2015.

Table 4-1 

Unusual Mortality Event Cetacean Data for the Northern Gulf of Mexico

Cetaceans Stranded Phase of Oil-Spill Response Dates

114 cetaceans stranded Prior to the response phase for the 

oil spill

February 1, 2010-April 29, 2010

121 cetaceans stranded or 

were reported dead offshore

During the initial response phase to 

the oil spill

April 30, 2010-November 2, 2010

1,135 cetaceans stranded* After the initial response phase 

ended

November 3, 2010-April 12, 2015**

Note: Numbers are preliminary and may be subject to change. As of April 12, 2015, the unusual mortality event 

involves 1,370 cetacean “strandings” in the northern Gulf of Mexico (USDOC, NMFS, 2015).

 * This number includes nine dolphins that were killed incidental to fish-related scientific data collection and one 

dolphin that was killed incidental to trawl relocation for a dredging project.

** The initial response phase ended for all four states on November 2, 2010, but then reopened for eastern and 

central Louisiana on December 3, 2010, and closed again on May 25, 2011.
Tables-8 Western Planning Area Lease Sale 248 Supplemental EIS

Table 4-2 

Number of Angler Trips in 2009-2014

2009

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 291,400 33,256 324,655 573,978 82,242 656,220 865,377 115,498 980,875

TTS 3,804 431 4,235 29,060 2,394 31,454 32,864 2,825 35,689

EEZ 252 0 252 20,874 3,336 24,211 21,127 3,336 24,463

Total 295,456 33,687 329,143 623,912 87,972 711,885 919,368 121,659 1,041,027

2010

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 255,995 23,570 279,565 567,522 93,650 661,171 823,517 117,220 940,737

TTS 3,250 2,187 5,437 22,837 2,052 24,888 26,087 4,239 30,326

EEZ 744 0 744 14,129 1,602 15,731 14,873 1,602 16,475

Total 259,989 25,758 285,747 604,487 97,303 701,791 864,476 123,061 987,537

2011

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 330,461 29,842 360,303 576,735 122,855 699,590 907,196 152,697 1,059,893

TTS 14,830 4,779 19,609 24,372 2,988 27,360 39,202 7,767 46,969

EEZ 1,424 850 2,274 15,138 1,126 16,264 16,562 1,976 18,538

Total 346,715 35,471 382,186 616,245 126,969 743,214 962,960 162,440 1,125,400

2012

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 331,889 87,696 419,585 563,656 134,502 698,158 895,545 222,198 1,117,743

TTS 7,563 1,172 8,735 15,375 1,622 16,997 22,938 2,794 25,732

EEZ 1,270 0 1,270 12,668 1,774 14,442 13,938 1,774 15,712

Total 340,722 88,868 429,590 591,699 137,898 729,597 932,421 226,766 1,159,187

2013

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 350,918 39,054 389,972 613,508 101,135 714,643 964,426 140,189 1,104,615

TTS 5,193 111 5,304 18,559 2,269 20,828 23,752 2,380 26,132

EEZ 989 575 1,564 15,695 1,592 17,286 16,684 2,166 18,850

Total 357,100 39,740 396,840 647,761 104,996 752,757 1,004,861 144,735 1,149,597

2014

Season A Season B Annual Total

Area Private Charter Total Private Charter Total Private Charter Total

Bay 292,988 30,722 323,710 605,314 101,802 707,116 898,302 132,524 1,030,826

TTS 3,550 127 3,677 18,886 2,664 21,550 22,436 2,791 25,227

EEZ 510 0 510 10,403 2,159 12,562 10,913 2,159 13,072

Total 297,048 30,849 327,897 634,603 106,625 741,228 931,651 137,474 1,069,125
Tables Tables-9 

Table 4-2. Number of Angler Trips in 2009-2014 (continued).

Notes: (1) Season A is November 21 - May 14 and Season B is May 15 - November 20. Therefore, the annual 

data reflect the combined catch for Seasons A and B. For example, the catch data for 2013 reflect catch 

from November 21, 2012, to November 20, 2013.

(2) These data are presented in terms of person-trips. This means that, if multiple people go fishing at the 

same time on the same boat, it is counted as multiple trips.

EEZ = Exclusive Economic Zone.

TTS = Texas Territorial Sea.

Source: Fisher, official communication, 2015.

Table 4-3

Top Species Landed by Recreational Fishermen

Panel A: Total Landings Panel B: Landings in Bays

Species 2009 2010 2011 2012 2013 2014 Species 2009 2010 2011 2012 2013 2014

Atlantic Croaker 117 124 156 157 152 117 Atlantic Croaker 117 124 154 156 151 117

Black Drum 98 165 129 256 150 139 Black Drum 97 164 127 256 150 139

King Mackerel 16 6 9 9 10 13 King Mackerel -- -- -- -- -- --

Red Drum 285 264 347 323 269 246 Red Drum 277 261 344 321 266 245

Red Snapper 31 33 36 34 47 40 Red Snapper -- -- -- -- -- --

Sand Seatrout 111 127 226 177 151 146 Sand Seatrout 108 126 220 169 150 145

Sheepshead 34 49 57 143 84 39 Sheepshead 34 49 57 143 84 39

Southern 

Flounder 47 30 92 96 92 71 Southern Flounder 47 30 92 96 92 71

Spotted Seatrout 810 732 1137 810 795 590 Spotted Seatrout 789 721 1119 798 789 585

Panel C: Landings in State Waters Panel D: Landings in EEZ

Species 2009 2010 2011 2012 2013 2014 Species 2009 2010 2011 2012 2013 2014

Atlantic Croaker -- -- 2 1 -- -- Atlantic Croaker -- -- -- -- 1 --

Black Drum 1 -- 2 -- -- -- Black Drum -- 1 -- -- -- --

King Mackerel 7 5 5 4 4 6 King Mackerel 9 1 4 5 6 7

Red Drum 8 -- 3 2 2 1 Red Drum 1 3 -- -- 1 --

Red Snapper 13 12 22 21 30 33 Red Snapper 19 21 14 13 17 7

Sand Seatrout 2 1 5 8 1 1 Sand Seatrout 1 1 1 -- -- --

Sheepshead -- -- -- -- -- -- Sheepshead -- -- -- -- -- --

Southern 

Flounder -- -- -- -- -- -- Southern Flounder -- -- -- -- -- --

Spotted Seatrout 14 -- 18 11 6 5 Spotted Seatrout 8 10 -- 1 -- --

Notes: (1) Fish landings are presented in thousands of fish.

(2) The Texas Parks and Wildlife Department presents data in terms of two seasons: Season A is November 21 - May 14 and 

Season B is May 15 - November 20. Therefore, the annual data reflect the combined catch for Seasons A and B. For 

example, the catch data for 2013 reflect catch from November 21, 2012, to November 20, 2013.

EEZ = Exclusive Economic Zone.

Source: Fisher, official communication, 2015.
Tables-10 Western Planning Area Lease Sale 248 Supplemental EIS

Table 4-4

 

Demographic and Employment Baseline Conditions in 2015 in All Economic Impact Areas

TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

Total Population (in thousands) 1,916 665 6,764 351 607 811 1,297 499 748 942 680 3,810 6,614

Age under 19 years 33.5% 28.3% 29.3% 27.6% 28.0% 27.8% 25.0% 26.5% 25.7% 23.9% 23.2% 22.2% 21.9%

Age 20 to 34 20.9% 18.8% 21.8% 21.3% 21.1% 20.6% 21.4% 20.1% 19.0% 22.0% 25.1% 19.2% 18.8%

Age 35 to 49 18.2% 19.1% 20.4% 18.3% 18.2% 19.1% 18.9% 18.8% 18.3% 17.6% 17.6% 17.9% 19.2%

Age 50 to 64 15.2% 19.5% 17.9% 18.9% 19.5% 19.5% 20.6% 19.9% 20.5% 20.5% 19.0% 20.7% 20.3%

Age 65 and over 12.2% 14.3% 10.6% 13.8% 13.2% 13.0% 14.1% 14.6% 16.5% 16.1% 15.1% 20.1% 19.8%

Median Age of Population (years) 35 41 39 37 36 37 38 34 41 40 40 44 47

White Population (in thousands) 14.8% 50.9% 39.3% 72.3% 66.8% 70.0% 53.3% 72.4% 64.7% 75.8% 63.6% 67.7% 40.2%

Black Population (in thousands) 1.2% 10.8% 17.6% 21.6% 28.0% 23.0% 34.9% 20.2% 29.6% 14.2% 27.9% 12.5% 17.1%

Native American Population (in thousands) 0.1% 0.3% 0.3% 0.9% 0.4% 1.5% 0.4% 0.5% 1.1% 0.8% 0.5% 0.3% 0.2%

Asian and Pacific Islander Population

(in thousands) 1.1% 3.9% 7.3% 1.4% 1.5% 1.2% 3.0% 2.2% 1.5% 3.0% 1.9% 3.5% 2.4%

Hispanic or Latino Population (in thousands) 82.7% 34.1% 35.5% 3.9% 3.3% 4.2% 8.4% 4.7% 3.1% 6.1% 6.2% 16.0% 40.1%

Male Population (percentage) 49.1% 50.3% 49.9% 50.2% 48.9% 49.3% 48.6% 49.8% 48.4% 50.6% 51.3% 48.6% 48.8%

Total Employment (in thousands of jobs) 903 343 4,127 186 358 448 793 248 394 512 334 1,997 3,804

Farm Employment 1.4% 6.1% 0.5% 1.7% 1.5% 0.9% 0.3% 1.2% 1.4% 0.5% 2.8% 1.1% 0.5%

Forestry, Fishing, Related Activities 1.1% 1.0% 0.2% 0.9% 0.6% 1.0% 0.5% 0.8% 1.0% 0.5% 1.4% 0.5% 0.4%

Mining 3.0% 4.4% 3.8% 1.2% 8.7% 4.1% 1.5% 0.3% 0.6% 0.4% 0.4% 0.2% 0.2%

Utilities 0.3% 0.9% 0.5% 0.4% 0.2% 0.3% 0.4% 0.7% 0.4% 0.5% 0.3% 0.3% 0.2%

Construction 6.3% 9.0% 7.5% 9.2% 6.1% 8.5% 6.7% 7.7% 6.2% 5.6% 4.6% 5.2% 5.1%

Manufacturing 3.0% 8.9% 7.0% 6.4% 6.7% 8.9% 4.4% 8.3% 7.9% 2.8% 3.5% 4.0% 2.6%

Wholesale Trade 2.7% 2.9% 4.6% 2.2% 3.4% 2.7% 3.3% 1.4% 3.2% 2.0% 1.9% 3.2% 4.3%

Retail Trade 11.6% 10.5% 9.3% 10.2% 10.9% 10.8% 9.7% 10.5% 11.8% 11.7% 10.1% 11.3% 11.3%

Transportation and Warehousing 3.5% 2.8% 4.1% 2.8% 3.1% 6.5% 4.2% 2.1% 3.6% 1.8% 2.1% 2.4% 3.9%

Information Employment 0.9% 0.7% 1.1% 0.8% 1.1% 0.8% 1.4% 0.9% 0.9% 1.2% 1.5% 1.8% 1.6%

Finance and Insurance 3.9% 4.3% 5.2% 3.1% 3.7% 3.6% 4.4% 2.9% 4.0% 4.3% 3.8% 6.9% 5.9%

Real Estate/Rental and Lease 3.3% 4.1% 4.5% 3.2% 4.5% 5.1% 4.4% 3.4% 4.9% 6.4% 3.6% 5.1% 7.5%

Professional and Technical Services 3.2% 4.1% 7.9% 4.3% 5.5% 4.1% 6.6% 3.9% 4.7% 5.7% 5.8% 7.3% 6.9%
Tables Tables-11

Table 4-4. Demographic and Employment Baseline Conditions in 2015 in All Economic Impact Areas (continued).

TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

Management 0.3% 0.4% 0.9% 0.7% 1.3% 0.8% 1.2% 0.5% 0.4% 0.5% 0.3% 1.5% 0.8%

Administrative and Waste Services 5.9% 4.4% 7.6% 5.0% 4.6% 6.2% 6.6% 6.9% 7.0% 6.6% 5.2% 7.2% 8.0%

Educational Services 1.0% 0.9% 1.6% 1.1% 1.2% 1.1% 3.6% 0.9% 1.8% 1.2% 1.3% 1.8% 2.2%

Health Care and Social Assistance 17.2% 8.3% 9.2% 10.4% 12.5% 8.4% 9.5% 7.2% 10.0% 10.4% 10.0% 12.5% 10.5%

Arts, Entertainment, and Recreation 1.1% 1.3% 1.5% 1.5% 1.8% 1.6% 2.7% 2.4% 1.5% 2.1% 1.4% 2.5% 2.5%

Accommodation and Food Services 7.7% 6.5% 7.0% 8.1% 6.4% 6.0% 9.8% 11.0% 8.2% 10.6% 7.4% 7.5% 8.2%

Other Services, except Public Administration 6.3% 5.9% 6.1% 5.8% 5.9% 6.8% 6.3% 5.8% 7.7% 5.8% 6.0% 5.9% 7.9%

Federal Civilian Government 1.8% 0.3% 0.7% 1.9% 0.4% 0.3% 1.6% 3.7% 0.8% 3.7% 1.2% 1.4% 0.9%

Federal Military 0.9% 0.4% 0.4% 5.7% 0.8% 0.9% 1.2% 4.6% 1.1% 7.1% 0.4% 0.7% 0.4%

State and Local Government 13.6% 11.7% 8.9% 13.2% 9.2% 10.7% 9.8% 12.6% 10.9% 8.5% 24.6% 9.8% 8.1%

Total Earnings (in millions of 2005 dollars) 35,091 14,554 278,228 8,700 17,684 21,107 40,501 10,690 15,905 21,430 13,430 90,924 166,613

Farm 0.8% 1.3% 0.0% 0.5% 1.9% 0.6% 0.1% 0.3% 1.0% 0.2% 1.6% 0.4% 0.5%

Forestry, Fishing, Related Activities 0.6% 0.5% 0.1% 0.7% 0.3% 0.3% 0.2% 0.5% 1.0% 0.2% 1.3% 0.2% 0.2%

Mining 8.1% 7.6% 13.2% 1.4% 15.8% 8.2% 4.3% 0.3% 0.7% 0.2% 0.3% 0.3% 0.1%

Utilities 0.6% 2.3% 1.5% 0.9% 0.4% 0.5% 1.0% 1.8% 1.0% 1.0% 0.6% 0.9% 0.4%

Construction 7.8% 12.0% 8.4% 11.2% 7.8% 9.1% 8.1% 8.6% 6.7% 5.1% 4.2% 4.7% 5.5%

Manufacturing 4.8% 18.1% 10.5% 13.4% 8.6% 15.3% 8.0% 15.5% 13.9% 4.2% 4.8% 5.6% 3.3%

Wholesale Trade 4.1% 4.3% 6.9% 2.6% 4.7% 3.3% 5.3% 1.8% 5.0% 2.7% 2.6% 5.0% 7.5%

Retail Trade 8.1% 7.7% 4.6% 5.8% 6.6% 6.4% 5.9% 6.6% 8.2% 7.5% 6.7% 7.8% 8.4%

Transportation and Warehousing 4.5% 3.5% 6.0% 3.4% 3.6% 11.8% 5.2% 2.3% 5.9% 1.9% 1.6% 2.1% 4.3%

Information 1.0% 0.6% 1.1% 1.0% 1.0% 0.8% 1.3% 0.9% 1.2% 1.5% 2.0% 2.9% 2.9%

Finance and Insurance 2.9% 3.1% 4.6% 2.4% 2.8% 2.7% 4.7% 2.6% 4.5% 4.1% 3.9% 8.2% 6.9%

Real Estate/Rental and Lease 1.4% 1.9% 1.9% 1.8% 4.6% 4.8% 2.4% 1.5% 2.4% 2.1% 1.1% 1.9% 2.8%

Professional and Technical Services 3.7% 4.1% 11.4% 5.0% 6.6% 3.6% 9.8% 4.8% 6.0% 7.8% 7.8% 10.3% 9.6%

Management 0.3% 0.5% 1.4% 0.7% 2.0% 1.0% 1.8% 0.9% 0.6% 0.8% 0.7% 2.9% 1.8%

Administrative and Waste Services 3.5% 2.7% 4.7% 3.2% 2.6% 3.7% 4.1% 4.1% 3.8% 4.2% 2.8% 4.9% 5.1%

Educational Services 0.6% 0.4% 1.1% 0.8% 0.8% 0.5% 2.7% 0.6% 1.1% 0.8% 0.6% 1.3% 1.9%

Health Care and Social Assistance 15.9% 7.7% 7.1% 10.6% 11.6% 6.9% 9.2% 7.0% 11.1% 12.3% 11.3% 14.4% 12.2%

Arts, Entertainment, and Recreation 0.4% 0.4% 0.6% 0.6% 0.5% 0.4% 1.6% 1.3% 0.5% 0.7% 0.4% 1.8% 1.7%
Tables-12 Western Planning Area Lease Sale 248 Supplemental EIS

Table 4-4. Demographic and Employment Baseline Conditions in 2015 in All Economic Impact Areas (continued).

TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

Accommodation and Food Services 3.5% 2.7% 2.3% 3.8% 2.6% 2.3% 4.8% 6.4% 3.8% 5.5% 3.2% 3.8% 5.0%

Other Services, except Public Administration 4.3% 4.5% 3.4% 3.7% 4.2% 4.5% 4.0% 3.7% 5.3% 4.1% 5.1% 3.8% 4.8%

Federal Civilian Government 4.5% 0.6% 1.2% 3.2% 0.8% 0.5% 2.9% 7.4% 1.9% 7.4% 2.8% 2.9% 2.1%

Federal Military 1.6% 0.3% 0.2% 9.6% 0.5% 0.6% 1.1% 7.0% 1.1% 14.9% 0.4% 1.1% 0.5%

State and Local Government 16.8% 13.3% 7.9% 13.7% 9.8% 12.2% 11.4% 14.3% 13.4% 11.0% 34.2% 12.7% 12.4%

Total Personal Income per Capita 

(in 2005 dollars) 27,829 40,086 49,491 35,792 40,906 38,883 42,649 32,613 32,880 37,736 31,190 37,643 42,190

Woods & Poole Economics Wealth Index 

(U.S. = 100) 82.5 91.4 93.2 80.9 85.1 88.2 87.4 60.8 70.6 87.1 65.1 76.2 108.9

Persons per Household (in number of people) 3.1 2.7 2.8 2.5 2.5 2.6 2.5 2.6 2.5 2.5 2.5 2.3 2.5

Mean Household Total Personal Income

(in 2005 dollars) 86,864 108,235 137,764 91,039 102,622 102,494 107,299 84,351 81,371 94,604 79,168 87,596 107,076

Number of Households (in thousands) 614 246 2,430 138 242 308 516 193 302 376 268 1,637 2,606

Income < $10,000 

(thousands of households, 2000$) 13.5% 6.8% 7.2% 9.3% 11.3% 8.7% 10.4% 9.2% 11.3% 7.4% 12.5% 8.5% 8.6%

Income $10,000 to $19,999 17.0% 11.8% 10.6% 13.8% 15.4% 13.7% 13.2% 13.7% 14.2% 11.8% 13.8% 13.0% 12.4%

Income $20,000 to $29,999 13.4% 10.7% 10.7% 13.2% 11.6% 10.9% 11.9% 12.5% 12.8% 11.4% 12.6% 13.0% 12.0%

Income $30,000 to $44,999 16.2% 14.0% 14.6% 15.7% 14.8% 14.4% 14.7% 16.1% 15.3% 17.2% 16.8% 17.1% 16.0%

Income $45,000 to $59,999 11.3% 13.0% 12.0% 12.5% 11.9% 11.9% 11.9% 13.3% 12.9% 13.5% 12.2% 13.6% 12.8%

Income $60,000 to $74,999 8.6% 10.0% 9.8% 9.8% 9.0% 10.3% 9.3% 10.5% 9.9% 11.4% 9.7% 9.8% 9.9%

Income $75,000 to $99,999 8.7% 12.1% 12.2% 11.3% 11.1% 13.0% 11.2% 11.5% 10.7% 12.2% 10.1% 10.7% 10.9%

Income $100,000 or more 11.2% 21.7% 22.9% 14.4% 15.0% 17.2% 17.4% 13.1% 13.0% 15.0% 12.4% 14.3% 17.4%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; persons per household calculated using total population/number of households for the EIA.

Source: Woods & Poole Economics, Inc., 2015. 
Tables Tables-13

Table 4-5

Demographic and Employment Baseline Conditions in 2050 in all Economic Impact Areas

TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

Total Population (in thousands) 3,169 1,052 11,621 417 806 1,196 1,465 603 966 1,308 960 5,794 9,661

Age under 19 years 28.2% 27.4% 27.2% 26.1% 26.0% 25.2% 23.6% 25.2% 24.1% 22.1% 20.9% 21.7% 19.8%

Age 20 to 34 19.6% 20.0% 21.3% 19.3% 19.3% 18.5% 18.7% 18.9% 17.5% 18.8% 20.4% 18.4% 16.8%

Age 35 to 49 17.8% 18.9% 20.2% 17.3% 18.1% 18.7% 18.5% 18.3% 17.5% 18.0% 17.4% 18.1% 17.8%

Age 50 to 64 16.4% 16.0% 16.0% 17.2% 17.4% 17.8% 18.6% 18.0% 18.4% 18.5% 19.4% 18.2% 18.1%

Age 65 and over 18.0% 17.7% 15.3% 20.0% 19.2% 19.9% 20.6% 19.6% 22.5% 22.6% 21.9% 23.6% 27.5%

Medium Age of Population (years) 40 38 40 39 40 42 41 36 45 43 45 46 50

White Population (in thousands 8.1% 29.2% 20.2% 66.4% 60.5% 63.4% 43.8% 64.3% 59.3% 69.3% 55.5% 49.7% 26.8%

Black Population (in thousands 1.2% 13.7% 14.5% 23.9% 31.6% 25.0% 35.6% 24.3% 31.2% 17.0% 34.9% 15.7% 18.7%

Native American Population (in thousands) 0.1% 0.3% 0.3% 1.1% 0.4% 1.5% 0.4% 0.4% 1.2% 0.6% 0.4% 0.2% 0.1%

Asian and Pacific Islander Population 

(in thousands) 1.2% 6.3% 12.4% 2.2% 2.1% 1.9% 4.2% 2.5% 2.4% 3.8% 2.4% 7.1% 4.0%

Hispanic or Latino Population (in thousands) 89.4% 50.5% 52.6% 6.4% 5.3% 8.2% 16.0% 8.5% 5.8% 9.2% 6.7% 27.3% 50.4%

Male Population (percentage) 49.6% 50.6% 50.2% 50.3% 49.1% 49.4% 49.0% 49.8% 48.3% 52.2% 52.7% 49.2% 49.1%

Total Employment (in thousands of jobs) 1,568 583 7,496 246 565 723 1,045 323 596 774 487 3,230 6,223

Farm Employment 0.6% 3.9% 0.3% 1.5% 1.0% 0.6% 0.2% 1.1% 0.9% 0.4% 2.2% 0.7% 0.4%

Forestry, Fishing, Related Activities 0.7% 0.8% 0.1% 1.0% 0.5% 0.9% 0.6% 0.8% 0.9% 0.5% 1.3% 0.4% 0.3%

Mining 2.2% 4.2% 3.2% 1.0% 8.4% 3.4% 1.3% 0.3% 0.7% 0.4% 0.5% 0.2% 0.2%

Utilities 0.3% 0.6% 0.3% 0.3% 0.2% 0.2% 0.4% 0.7% 0.3% 0.6% 0.3% 0.2% 0.1%

Construction 5.2% 7.8% 6.4% 9.7% 5.8% 6.3% 6.1% 8.3% 5.3% 4.6% 4.2% 5.3% 5.4%

Manufacturing 1.7% 6.2% 4.5% 4.1% 5.1% 5.7% 2.6% 5.8% 4.5% 1.4% 2.4% 2.5% 1.6%

Wholesale Trade 2.0% 2.9% 4.5% 1.9% 2.8% 2.5% 3.4% 1.2% 2.7% 1.6% 1.5% 2.7% 3.8%

Retail Trade 11.5% 8.8% 8.5% 9.8% 11.4% 9.7% 10.0% 10.1% 10.6% 10.7% 8.9% 11.1% 11.2%

Transportation and Warehousing 3.8% 2.4% 3.1% 2.8% 3.1% 6.2% 3.3% 1.9% 2.8% 1.6% 2.5% 2.1% 3.6%

Information Employment 1.0% 0.4% 0.8% 0.7% 1.1% 0.7% 1.4% 0.7% 0.8% 1.1% 1.1% 1.5% 1.3%

Finance and Insurance 4.2% 5.9% 5.8% 3.2% 3.5% 3.5% 3.9% 2.9% 3.6% 4.9% 4.6% 6.9% 5.4%

Real Estate/Rental and Lease 3.3% 6.6% 5.3% 4.1% 4.7% 5.3% 4.9% 4.1% 5.3% 7.3% 4.1% 5.3% 7.3%

Professional and Technical Services 3.6% 4.3% 8.4% 4.9% 6.1% 5.0% 7.0% 4.0% 4.9% 7.6% 6.0% 8.2% 7.6%

Management 0.7% 0.7% 1.5% 0.7% 1.1% 0.7% 0.8% 0.6% 0.5% 0.5% 0.4% 2.9% 0.9%
Tables-14 Western Planning Area Lease Sale 248 Supplemental EIS

Table 4-5. Demographic and Employment Baseline Conditions in 2050 in all Economic Impact Areas (continued).

TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

Administrative and Waste Services 8.1% 4.9% 8.4% 6.5% 4.9% 8.2% 6.8% 9.0% 9.4% 6.5% 5.5% 6.7% 8.1%

Educational Services 1.3% 1.3% 1.8% 1.0% 1.2% 1.6% 4.7% 1.8% 1.9% 1.5% 1.8% 2.6% 2.5%

Health Care and Social Assistance 20.5% 11.8% 11.8% 13.8% 15.2% 11.1% 11.2% 10.3% 12.3% 12.1% 12.5% 13.9% 12.4%

Arts, Entertainment, and Recreation 1.2% 1.4% 1.5% 1.1% 2.0% 1.9% 2.7% 2.2% 1.4% 2.8% 1.5% 2.5% 2.6%

Accommodation and Food Services 8.3% 9.1% 8.4% 8.2% 6.1% 6.6% 9.5% 8.8% 10.8% 13.2% 9.4% 7.3% 7.6%

Other Services, except Public Administration 7.1% 5.8% 7.2% 6.9% 7.0% 10.3% 8.1% 7.3% 9.9% 6.5% 6.6% 6.6% 9.6%

Federal Civilian Government 1.5% 0.2% 0.4% 1.3% 0.3% 0.2% 1.5% 3.1% 0.6% 2.7% 1.0% 1.1% 0.6%

Federal Military 0.5% 0.3% 0.2% 4.4% 0.5% 0.6% 0.9% 3.6% 0.7% 4.8% 0.3% 0.4% 0.3%

State and Local Government 10.9% 9.8% 7.7% 11.1% 8.0% 8.5% 8.6% 11.3% 8.8% 6.8% 21.4% 8.7% 7.1%

Total Earnings (in millions of 2005 dollars) 78,627 32,565 681,613 14,675 36,848 41,704 67,735 17,574 29,548 41,492 24,698 198,635 357,642

Farm 0.3% 0.8% 0.0% 0.4% 1.2% 0.4% 0.1% 0.2% 0.7% 0.1% 1.2% 0.2% 0.3%

Forestry, Fishing, Related Activities 0.4% 0.3% 0.0% 0.8% 0.2% 0.3% 0.2% 0.5% 1.0% 0.2% 1.1% 0.2% 0.2%

Mining 6.3% 7.9% 11.4% 1.3% 16.1% 7.8% 4.0% 0.3% 0.8% 0.2% 0.4% 0.3% 0.1%

Utilities 0.6% 1.7% 1.0% 0.7% 0.3% 0.4% 1.0% 1.8% 0.9% 1.4% 0.6% 0.6% 0.4%

Construction 5.6% 8.9% 6.0% 10.3% 6.2% 6.3% 6.4% 8.3% 5.1% 3.6% 3.4% 3.9% 4.9%

Manufacturing 3.0% 13.3% 7.0% 9.2% 7.6% 11.3% 5.2% 12.0% 9.9% 2.4% 3.7% 3.8% 2.2%

Wholesale Trade 3.0% 4.7% 7.0% 2.3% 3.9% 3.3% 5.6% 1.5% 4.4% 2.1% 2.0% 4.0% 6.6%

Retail Trade 6.7% 5.4% 3.4% 4.7% 5.6% 5.1% 5.1% 5.3% 6.4% 5.7% 5.0% 6.1% 6.8%

Transportation and Warehousing 4.5% 2.9% 4.3% 3.2% 3.2% 11.0% 3.4% 1.9% 4.4% 1.6% 1.8% 1.6% 3.6%

Information 1.4% 0.6% 1.0% 0.9% 1.2% 1.1% 1.5% 0.9% 1.4% 1.6% 1.7% 2.8% 3.0%

Finance and Insurance 3.6% 5.0% 6.0% 2.7% 2.8% 3.2% 4.7% 3.1% 4.7% 5.1% 5.3% 8.7% 6.6%

Real Estate/Rental and Lease 1.3% 3.2% 2.2% 2.2% 4.6% 4.9% 2.8% 1.8% 2.6% 2.3% 1.2% 1.8% 2.5%

Professional and Technical Services 5.1% 5.6% 15.0% 6.7% 8.6% 5.8% 12.3% 5.7% 7.6% 12.1% 9.5% 12.8% 12.3%

Management 1.0% 1.1% 3.4% 0.9% 2.3% 1.1% 1.6% 1.4% 1.2% 0.9% 0.9% 7.1% 2.6%

Administrative and Waste Services 4.6% 3.2% 5.2% 4.3% 2.7% 5.4% 4.2% 5.4% 5.3% 4.1% 3.1% 4.2% 5.1%

Educational Services 0.9% 0.6% 1.2% 0.7% 0.8% 0.9% 3.7% 1.2% 1.2% 1.0% 0.8% 1.8% 2.1%

Health Care and Social Assistance 23.3% 14.0% 11.0% 16.7% 15.8% 10.9% 12.7% 11.2% 16.2% 16.4% 16.3% 17.4% 16.3%

Arts, Entertainment, and Recreation 0.4% 0.4% 0.5% 0.4% 0.5% 0.4% 1.6% 1.1% 0.5% 0.9% 0.4% 1.6% 1.6%

Accommodation and Food Services 3.6% 3.7% 2.6% 3.7% 2.3% 2.5% 4.5% 4.9% 5.0% 6.6% 3.8% 3.2% 4.4%
Tables Tables-15

Table 4-5. Demographic and Employment Baseline Conditions in 2050 in all Economic Impact Areas (continued).

TX-1 TX-2 TX-3 LA-1 LA-2 LA-3 LA-4 MS-1 AL-1 FL-1 FL-2 FL-3 FL-4 

Other Services, except Public Administration 4.6% 4.2% 3.8% 4.3% 4.6% 6.6% 4.9% 4.4% 6.6% 4.3% 5.3% 3.8% 5.5%

Federal Civilian Government 4.2% 0.5% 0.7% 2.4% 0.5% 0.5% 3.2% 7.1% 1.6% 6.0% 2.4% 2.3% 1.6%

Federal Military 1.2% 0.2% 0.1% 9.5% 0.4% 0.5% 1.1% 7.1% 1.0% 12.8% 0.3% 0.8% 0.4%

State and Local Government 14.2% 11.8% 7.1% 11.6% 8.4% 10.3% 10.3% 13.0% 11.4% 8.8% 29.8% 10.8% 10.9%

Total Personal Income per Capita

(in 2005 dollars) 41,892 60,891 76,078 52,187 62,530 54,926 64,347 46,583 50,023 55,156 43,321 55,649 65,518

Woods & Poole Economics Wealth Index 

(U.S. = 100) 88.9 102.0 93.5 79.8 86.4 87.1 85.4 58.5 70.7 84.9 61.6 75.2 113.8

Person per Household (in number of people) 3.2 2.8 2.9 2.5 2.5 2.6 2.5 2.6 2.5 2.5 2.6 2.5 2.7

Mean Household Total Personal Income

(in 2005 dollars) 133,708 170,417 223,022 131,902 154,037 143,237 161,080 121,826 124,100 139,287 112,215 137,546 174,681

Number of Households (in thousands) 993 376 3,964 165 327 458 585 231 390 518 370 2,344 3,624

Income < $10,000 

(thousands of households, 2000$) 6.4% 3.4% 3.9% 5.1% 5.8% 4.6% 5.1% 4.6% 5.0% 3.4% 6.9% 4.1% 4.3%

Income $10,000 to $19,999 7.9% 5.8% 5.8% 7.5% 7.8% 7.3% 6.8% 6.9% 6.5% 5.5% 7.5% 6.2% 6.3%

Income $20,000 to $29,999 6.3% 5.4% 5.9% 7.2% 6.1% 5.8% 6.3% 6.1% 6.2% 5.4% 6.9% 6.2% 6.2%

Income $30,000 to $44,999 9.3% 7.3% 8.1% 8.6% 8.1% 8.0% 8.3% 7.9% 7.9% 8.2% 9.9% 8.2% 8.3%

Income $45,000 to $59,999 12.0% 8.0% 7.4% 9.8% 9.3% 8.1% 8.8% 9.6% 9.7% 8.2% 11.9% 9.6% 8.4%

Income $60,000 to $74,999 16.5% 9.1% 8.9% 13.6% 12.2% 11.4% 10.7% 14.1% 13.4% 12.5% 15.9% 13.3% 11.6%

Income $75,000 to $99,999 18.3% 18.4% 18.3% 21.1% 21.1% 23.1% 19.7% 23.7% 22.5% 24.2% 18.4% 22.6% 20.8%

Income $100,000 or more 23.3% 42.5% 41.6% 27.1% 29.5% 31.8% 34.1% 27.1% 28.8% 32.5% 22.6% 30.0% 34.1%

Notes: Median Age and The Wealth Index are defined using averages of the original Woods & Poole values for the counties in the EIA; income per capita calculated using personal income/total 

population for the EIA; persons per household calculated using total population/number of households for the EIA.

Source: Woods & Poole Economics, Inc., 2015.
Tables-16 Western Planning Area Lease Sale 248 Supplemental EIS

Table 4-6 

Sales Volumes, Sales Values, and Revenues

Fiscal Year

2008 2009 2010 2011 2012 2013 2014

Panel A: Sales Volumes

Gas (royalty) (Mcf) 2,143,219,978 1,730,441,404 1,687,273,215 1,377,976,860 1,118,510,486 952,559,046 900,114,993

Gas (non-royalty) (Mcf) 316,986,987 461,373,909 371,665,155 297,608,514 241,687,280 232,010,830 157,147,262

NGL (royalty) (gal) 2,045,051,035 1,742,817,905 2,035,398,162 1,792,231,834 1,572,031,308 1,511,350,358 1,680,356,769

NGL (non-royalty) (gal) 162,010,065 155,451,086 384,637,321 387,625,746 304,409,194 382,776,628 312,189,029

Oil (royalty) (bbl) 274,782,936 393,146,795 414,283,323 358,715,537 336,361,314 357,651,947 395,806,007

Oil (non-royalty) (bbl) 162,506,924 127,353,025 179,566,357 152,390,468 121,890,202 99,945,768 86,737,322

Panel B: Sales Values

Gas ($) 19,784,563,673 7,906,066,513 7,901,285,172 5,901,378,985 3,254,881,856 3,527,244,352 3,984,226,004

NGL ($) 3,067,671,727 1,267,858,373 2,075,764,329 2,747,520,920 1,748,239,028 1,309,742,071 1,538,883,909

Oil ($) 29,410,660,793 21,108,193,437 31,085,489,576 35,371,471,285 36,870,071,043 38,027,551,056 39,477,254,223

Other Products ($) 423,743 173,955 86,350 60,125 48,228 66,780 41,563

Total Sales Value ($) 52,263,319,935 30,282,292,277 41,062,625,426 44,020,431,314 41,873,240,156 42,864,604,259 45,000,405,699

Panel C: Revenues

Gas Royalties ($) 2,873,174,184 1,109,453,399 1,111,565,590 833,964,068 455,003,075 498,454,983 553,674,802

NGL Royalties ($) 286,514,305 119,772,432 244,216,684 280,309,056 217,352,432 157,910,822 184,978,637

Oil Royalties ($) 4,056,267,707 2,767,151,995 4,091,755,677 4,800,678,071 5,026,388,805 5,185,254,716 5,316,466,639

Other Royalties ($) 43,812 14,947 4,095 3,307 3,927 4,384 2,273

Rents ($) 231,475,837 228,538,775 238,240,338 217,625,357 218,147,551 236,321,909 232,376,449

Bonus ($) 6,817,546,915 1,174,069,762 986,997,466 37,054,282 606,446,360 2,732,922,142 967,365,328

Other Revenues ($) 3,325,433 -29,904,061 46,809,265 3,951,382 5,045,519 34,753,295 43,014,645

Total Revenues ($) 14,268,348,192 5,369,097,248 6,719,589,116 6,173,585,523 6,528,387,669 8,845,622,251 7,297,878,773

Note: This table presents the sales volumes, sales values, and revenues received based on offshore oil and gas activities in the Gulf of Mexico. Data in this 

table refer to the years in which sales occurred (not to the years in which government revenues were received).

bbl = barrel; gal = gallon; Mcf = thousand cubic feet; NGL = natural gas liquids

Source: USDOI, Office of Natural Resources Revenue, 2015.
Tables Tables-17

References

Fisher, M. 2015. Official communication. Email regarding fishing data. Texas Parks and Wildlife 

Department, Rockport Marine Laboratory, Rockport, TX. March 31, 2015. 

Gonzales, S. 2015. Official communication. Email regarding updated produced-water data through 

2014. February 5, 2015. 

U.S. Dept. of Commerce. National Marine Fisheries Service. 2015. Cetacean unusual mortality event in 

northern Gulf of Mexico (2010-present). Internet website: http://www.nmfs.noaa.gov/pr/health/

mmume/cetacean_gulfofmexico2010.htm. Accessed April 14, 2015. 

U.S. Dept. of the Interior. Office of Natural Resources Revenue. 2015. Statistical information online 

query. Internet website: http://statistics.onrr.gov/ReportTool.aspx. Accessed April 8, 2015. 

Woods & Poole Economics, Inc. 2015. The 2015 complete economic and demographic data source 

(CEDDS) on CD-ROM.

APPENDIX A 

 

CATASTROPHIC SPILL EVENT ANALYSIS: 

HIGH-VOLUME, EXTENDED-DURATION OIL SPILL

RESULTING FROM LOSS OF WELL CONTROL 

ON THE GULF OF MEXICO OUTER CONTINENTAL SHELF

Catastrophic Spill Event Analysis A-iii

TABLE OF CONTENTS

Page

A. CATASTROPHIC SPILL EVENT ANALYSIS: HIGH-VOLUME, EXTENDED-DURATION 

OIL SPILL RESULTING FROM LOSS OF WELL CONTROL ON THE GULF OF MEXICO 

OUTER CONTINENTAL SHELF .................................................................................................... A-1

A.1. Introduction ............................................................................................................................. A-1

A.1.1. What is a Catastrophic Event? .................................................................................. A-1

A.1.2. Methodology ............................................................................................................ A-2

A.1.2.1. Geographic Scope ................................................................................... A-3

A.1.2.2. Impact-Producing Factors and Scenario ................................................. A-3

A.1.2.3. OSRA Catastrophic Run ......................................................................... A-3

A.1.2.4. Environmental and Socioeconomic Impacts ........................................... A-3

A.1.3. How to Use This Analysis ........................................................................................ A-3

A.2. Impact-Producing Factors and Scenario (Phases 1-4) ............................................................ A-4

A.2.1. Phase 1—Initial Event .............................................................................................. A-4

A.2.2. Phase 2—Offshore Spill ........................................................................................... A-4

A.2.2.1. Duration of Spill ...................................................................................... A-4

A.2.2.1.1. Shallow Water ...................................................................... A-5

A.2.2.1.2. Deep Water ........................................................................... A-5

A.2.2.2. Area of Spill ............................................................................................ A-5

A.2.2.3. Volume of Spill ....................................................................................... A-5

A.2.2.3.1. Shallow Water ...................................................................... A-6

A.2.2.3.2. Deep Water ........................................................................... A-6

A.2.2.4. Oil in the Environment: Properties and Persistence ............................... A-6

A.2.2.5. Release of Natural Gas ............................................................................ A-7

A.2.2.6. Deepwater Subsea Containment ............................................................. A-7

A.2.2.7. Offshore Cleanup Activities .................................................................... A-9

A.2.2.7.1. Shallow Water ...................................................................... A-9

A.2.2.7.2. Deep Water ......................................................................... A-10

A.2.2.7.3. Vessel Decontamination Stations ....................................... A-10

A.2.2.8. Severe Weather ..................................................................................... A-11

A.2.3. Phase 3—Onshore Contact ..................................................................................... A-11

A.2.3.1. Duration ................................................................................................ A-11

A.2.3.1.1. Shallow Water .................................................................... A-12

A.2.3.1.2. Deep Water ......................................................................... A-12

A.2.3.2. Volume of Oil Contacting Shore ........................................................... A-12

A.2.3.3. Length of Shoreline Contacted .............................................................. A-12

A.2.3.3.1. Shallow Water .................................................................... A-13

A.2.3.3.2. Deep Water ......................................................................... A-13

A.2.3.4. Severe Weather ..................................................................................... A-13

A.2.3.5. Onshore Cleanup Activities .................................................................. A-14

A.2.3.5.1. Shallow Water .................................................................... A-14

A.2.3.5.2. Deep Water ......................................................................... A-14

A.2.3.5.3. Response Considerations for Sand Beaches for Both 

Shallow-Water and Deepwater Spills ................................. A-14

A.2.3.5.4. Response Considerations for Marshes for Both 

Shallow-Water and Deepwater Spills ................................. A-15
A-iv Western Planning Area Lease Sale 248 Supplemental EIS

A.2.3.5.5. Response Considerations for Nearshore Waters 

for Both Shallow-Water and Deepwater Spills .................. A-15

A.2.4. Phase 4—Post-Spill, Long-Term Recovery ........................................................... A-15

A.2.4.1. Response Considerations for Sand Beaches, Marshes, and 

Nearshore Waters for both Shallow-Water and Deepwater Spills ........ A-16

A.3. Description of the Environment and Impact Analysis .......................................................... A-17

A.3.1. Long Duration—Large Volume Spill within the Gulf of Mexico .......................... A-17

A.3.1.1. Air Quality ............................................................................................ A-17

A.3.1.2. Water Quality ........................................................................................ A-19

A.3.1.3. Coastal Barrier Beaches and Associated Dunes .................................... A-24

A.3.1.4. Wetlands ................................................................................................ A-25

A.3.1.5. Seagrass Communities .......................................................................... A-28

A.3.1.6. Topographic Features ............................................................................ A-30

A.3.1.7. Sargassum Communities ....................................................................... A-36

A.3.1.8. Chemosynthetic Deepwater Benthic Communities ............................... A-39

A.3.1.9. Nonchemosynthetic Deepwater Benthic Communities ......................... A-42

A.3.1.10. Soft Bottom Benthic Communities ....................................................... A-46

A.3.1.11. Marine Mammals .................................................................................. A-52

A.3.1.12. Sea Turtles ............................................................................................. A-55

A.3.1.13. Diamondback Terrapins ........................................................................ A-59

A.3.1.14. Coastal, Marine, and Migratory Birds ................................................... A-61

A.3.1.15. Fish Resources and Essential Fish Habitat ............................................ A-67

A.3.1.16. Commercial Fisheries............................................................................ A-70

A.3.1.17. Recreational Fishing.............................................................................. A-72

A.3.1.18. Recreational Resources ......................................................................... A-73

A.3.1.19. Archaeological Resources ..................................................................... A-75

A.3.1.20. Land Use and Coastal Infrastructure ..................................................... A-78

A.3.1.21. Demographics ....................................................................................... A-79

A.3.1.22. Economic Factors .................................................................................. A-80

A.3.1.23. Environmental Justice ........................................................................... A-81

A.3.1.24. Species Considered due to U.S. Fish and Wildlife Service Concerns .. A-85

A.4. Preparers ............................................................................................................................... A-86

A.5. References ............................................................................................................................. A-87
Catastrophic Spill Event Analysis A-v 

FIGURES

Page

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

Study Area. ..................................................................................................................... A-114

Figure A-2. Spatial Frequency (%) of the Watermass Associated with the Loop Current 

in the Eastern Gulf of Mexico based on Data for the Period 1976-2003. ....................... A-115

Figure A-3. Summary of Avian Species Collected by Date Obtained from the U.S. Fish and 

Wildlife Service as Part of the Deepwater Horizon Post-Spill Monitoring and 

Collection Process through May 12, 2011. ..................................................................... A-116

TABLES

Page

Table A-1. Blowout Scenarios and Key Differences in Impacts, Response, and/or Intervention ..... A-117

Table A-2. Properties and Persistence by Oil Component Group ..................................................... A-118

Table A-3. Annual Volume of Produced Water Discharged by Depth (millions of barrels) ............ A-119

Table A-4. Description of the Scenario for a Catastrophic Spill Event Occurring in Shallow 

Water or Deep Water ...................................................................................................... A-120

Table A-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: 

Post-Deepwater Horizon Explosion, Oil Spill, and Response in the Gulf of Mexico .... A-123

Table A-6. Federally Listed Avian Species Considered by State and Associated Planning Area 

in the Gulf of Mexico ...................................................................................................... A-130

Catastrophic Spill Event Analysis A-1 

A. CATASTROPHIC SPILL EVENT ANALYSIS: HIGH-VOLUME, 

EXTENDED-DURATION OIL SPILL RESULTING FROM LOSS 

OF WELL CONTROL ON THE GULF OF MEXICO OUTER 

CONTINENTAL SHELF

A.1. INTRODUCTION

In 1986, the Council on Environmental Quality (CEQ) regulations were amended to rescind the 

requirement to prepare a “worst-case analysis” for an environmental impact statement (EIS) (refer to 

40 CFR § 1502.22(b)(4)). The regulation, as amended, states that catastrophic, low-probability impacts 

must be analyzed if the analysis is “supported by credible scientific evidence, is not based on pure 

conjecture, and is within the rule of reason.” 

The August 16, 2010, CEQ report, prepared following the Deepwater Horizon explosion, oil spill, 

and response in the Gulf of Mexico, recommended that the Bureau of Ocean Energy Management 

(BOEM), formerly the Minerals Management Service (MMS) and Bureau of Ocean Energy Management, 

Regulation and Enforcement (BOEMRE), should “ensure that National Environmental Policy Act 

(NEPA) documents provide decisionmakers with a robust analysis of reasonably foreseeable impacts, 

including an analysis of reasonably foreseeable impacts associated with low-probability catastrophic 

spills for oil and gas activities on the Outer Continental Shelf” (CEQ, 2010). This evaluation is a robust 

analysis of the impacts from low-probability catastrophic spills and will be made available to all 

applicable decisionmakers including, but not limited to, the Secretary of the Department of the Interior 

(USDOI) for the National Five-Year Program, the Assistant Secretary of Land and Minerals Management 

for an oil and gas lease sale, and the Regional Supervisors of the Gulf of Mexico OCS Region’s Office of 

Environment and Office of Leasing and Plans. 

It should be noted that the analysis presented here is intended to be a general overview of the 

potential effects of a catastrophic spill in the Gulf of Mexico. As such, the Catastrophic Spill Event 

Analysis should be read with the understanding that further detail about accidental oil impacts on a 

particular resource may be found in the Gulf of Mexico OCS Oil and Gas Lease Sales: 2016, Western 

Planning Area Lease Sale 248, Final Supplemental Environmental Impact Statement (WPA 248 

Supplemental EIS) analysis or previous relevant NEPA analyses (e.g., the Gulf of Mexico OCS Oil and 

Gas Lease Sales: 2012-2017; Western Planning Area Lease Sales 229, 233, 238, 246, and 248; Central 

Planning Area Lease Sales 227, 231, 235, 241, and 247, Final Environmental Impact Statement [2012-

2017 WPA/CPA Multisale EIS; USDOI, BOEM, 2012]; the Gulf of Mexico OCS Oil and Gas Lease 

Sales: 2013-2014; Western Planning Area Lease Sale 233; Central Planning Area Lease Sale 231, Final 

Supplemental Environmental Impact Statement [WPA 233/CPA 231 Supplemental EIS; USDOI, BOEM, 

2013a]; the Gulf of Mexico OCS Oil and Gas Lease Sales: 2014 and 2016, Eastern Planning Area Lease 

Sales 225 and 226, Final Environmental Impact Statement [EPA 225/226 EIS; USDOI, BOEM, 2013b]; 

Gulf of Mexico OCS Oil and Gas Lease Sales: 2014-2016; Western Planning Area Lease Sales 238, 246, 

and 248, Final Supplemental Environmental Impact Statement [WPA 238/246/248 Supplemental EIS; 

USDOI, BOEM, 2014]; and Gulf of Mexico OCS Oil and Gas Lease Sales: 2015 and 2016; Western 

Planning Area Lease Sales 246 and 248, Final Supplemental Environmental Impact Statement

[WPA 246/248 Supplemental EIS; USDOI, BOEM, 2015]).

A.1.1. What is a Catastrophic Event?

As applicable to NEPA, Eccleston (2008) defines a catastrophic event as “large-scale damage 

involving destruction of species, ecosystems, infrastructure, or property with long-term effects, and/or 

major loss of human life.” For oil and gas activities on the Outer Continental Shelf (OCS), a catastrophic 

event is a high-volume, extended-duration oil spill regardless of the cause, whether natural disaster (i.e., 

hurricane) or manmade (i.e., human error and terrorism). This high-volume, extended-duration oil spill, 

or catastrophic spill, has been further defined by the National Oil and Hazardous Substances Pollution 

Contingency Plan as a “spill of national significance” or “a spill which, because of its severity, size, 

location, actual or potential impact on the public health and welfare or the environment, or the necessary 
A-2 Western Planning Area Lease Sale 248 Supplemental EIS

response effort, is so complex that it requires extraordinary coordination of Federal, State, local, and 

responsible party resources to contain and cleanup the discharge” (40 CFR part 300, Appendix E). 

Each oil-spill event is unique; its outcome depends on several factors, including time of year and 

location of release relative to winds, currents, land, and sensitive resources; specifics of the well (i.e., 

flow rates, hydrocarbon characteristics, and infrastructure damage); and response effort (i.e., speed and 

effectiveness). For this reason, the severity of impacts from an oil spill cannot be predicted based on 

volume alone, although a minimum volume of oil must be spilled to reach catastrophic impacts. 

Though large spills may result from a pipeline rupture, such events will not result in a catastrophic 

spill because the ability to detect leaks and shut off pipelines limits the amount of the spill to the contents 

of the pipeline. The largest, non-blowout-related spill on the Gulf of Mexico OCS occurred in 1967, a 

result of internal pipeline corrosion following initial damage by an anchor. In 13 days, 160,638 barrels 

(bbl) of oil leaked (USDOI, BSEE, 2013); however, no significant environmental impacts were recorded 

as a result of this spill.

Although loss of well control is defined as the uncontrolled flow of reservoir fluid that may result in 

the release of gas, condensate, oil, drilling fluids, sand, or water, it is a broad term that includes very 

minor well control incidents as well as the most severe well control incidents. Historically, loss of well 

control incidents occurred during development drilling operations, but loss of well control incidents can 

occur during exploratory drilling, production, well completions, or workover operations. These losses of 

well control incidents may occur between formations penetrated in the wellbore or at the seafloor.

Prior to the Deepwater Horizon explosion, oil spill, and response, the two largest spills resulting from 

a loss of well control in U.S. waters of the Gulf of Mexico occurred in 1970 and released 30,000 and 

53,000 bbl of oil, respectively (USDOI, BSEE, 2013). These incidents resulted in four human fatalities. 

Although these incidents occurred 8-14 miles (mi) (13-26 kilometers [km]) from shore, there was minor 

shoreline contact with oil (USDOC, NOAA, Office of Response and Restoration, 2010a and 2010b). In

1987, a blowout of the Mexican exploratory oil well, YUM II, resulted in a spill of 58,640 bbl and 75 mi 

(121 km) of impacted shoreline (USDOC, NOAA, Hazardous Materials Response and Assessment 

Division, 1992). However, none of these spills met the previously described definitions of a catastrophic 

event or spill.

A blowout is a more severe loss of well control incident that creates a greater risk of a large oil spill 

and serious human injury. Two blowouts that resulted in catastrophic spills have occurred in U.S. and 

Mexican waters of the Gulf of Mexico. On June 3, 1979, the Ixtoc I well blowout in shallow water (water 

depth of 164 feet [ft] [50 meters [m]] and 50 mi [80 km] offshore in the Bay of Campeche, Mexico) 

spilled 3.5 million barrels (MMbbl) of oil in 10 months (USDOC, NOAA, Office of Response and 

Restoration, 2010c; USDOC, NOAA, Hazardous Materials Response and Assessment Division, 1992; 

ERCO, 1982). On April 20, 2010, the Macondo well blowout (Deepwater Horizon explosion, oil spill, 

and response) in deep water (4,992 ft; 1,522 m) 48 mi (77 km) offshore in Mississippi Canyon Block 252, 

spilled an estimated 4.9 MMbbl of oil until it was capped approximately 3 months later. Due to being 

classified as catastrophic, the Ixtoc I and Macondo well blowouts and spills were utilized to develop the 

catastrophic spill event scenario in this analysis.

A.1.2. Methodology

Two general approaches are utilized to analyze a catastrophic event under NEPA. The first approach 

is a bounding analysis for each individual resource category (e.g., marine mammals and sea turtles). A 

bounding analysis involves selecting and evaluating a different set of factors and scenarios for each 

resource in the context of a worst-case analysis. The second approach involves the selection of a single 

set of key circumstances that, when combined, result in catastrophic consequences. The second approach 

is used for a site-specific analysis and, consequently, its possible application is more limited. 

Accordingly, this analysis combines the two approaches, relying on a generalized scenario while 

identifying site-specific severity factors for individual resources. This combined approach allows for the 

scientific investigation of a range of possible, although not necessarily probable, consequences of a 

catastrophic blowout and oil spill in the Gulf of Mexico.
Catastrophic Spill Event Analysis A-3 

A.1.2.1. Geographic Scope

The Gulf of Mexico is a semi-enclosed basin with an extensive history of oil and gas activities and 

unique environmental conditions and hydrocarbon reservoir properties; consequently, this analysis is only 

applicable to the Gulf of Mexico OCS and is not intended for other OCS regions. 

A.1.2.2. Impact-Producing Factors and Scenario

A hypothetical, yet feasible, scenario (Chapter A.2) was developed to provide a framework for 

identifying the impacts of an extended oil spill from an uncontrolled blowout. Unless noted, this scenario 

is based on the large magnitude, blowout-related oil spills that have occurred in the Gulf of Mexico, i.e., 

Ixtoc I and Macondo well blowouts and spills (discussed in Chapter A.1.1). As noted above, because 

each spill event is unique, its outcome depends on many factors. Therefore, the specific impacts from 

future spills cannot be predicted based on this scenario.

A.1.2.3. OSRA Catastrophic Run

A special Oil-Spill Risk Analysis (OSRA) model run was conducted to estimate the impacts of a 

possible future catastrophic or high-volume, extended-duration oil spill. This analysis emphasized 

modeling a spill that continued for 90 consecutive days by launching spills on each of 90 consecutive 

days, with each trajectory tracked for up to 60 days. The OSRA was conducted for only the trajectories 

of oil spills from hypothetical spill locations to various onshore and offshore environmental resources. 

Data from two hypothetical spill locations located in the Western Planning Area (WPA) (Figure A-1) 

were included and are intended for use as examples of this type of exercise. Information on previous 

catastrophic OSRA runs for the WPA can be found in Appendix C of the WPA 238/246/248 

Supplemental EIS. 

The probability of an oil spill contacting a specific resource within a given time of travel from a spill 

point is termed a conditional probability; the condition being that a spill is assumed to have occurred. 

Each trajectory was allowed to continue for as long as 60 days. However, once a hypothetical spill 

contacts land, the spill trajectory is terminated and the contact is recorded. Although, overall OSRA is 

designed for use as a risk-based assessment, for this analysis, only the conditional probability, the 

probability of contact to the resource, was calculated. The probability of a catastrophic spill occurring 

was not calculated; thus, the combination of the probability of a spill and the probability of contact to the 

resources from the hypothetical spill locations were not calculated. Results from this trajectory analysis 

provide input to the final product by estimating where spills might travel on the ocean’s surface and what 

environmental resources might be contacted if and when another catastrophic spill occurs, but they do not 

provide input on the probability of another catastrophic spill occurring. Further detail on this catastrophic 

OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental EIS.

A.1.2.4. Environmental and Socioeconomic Impacts

This analysis evaluates the impacts to the Gulf of Mexico’s biological, physical, and socioeconomic 

resources from a catastrophic blowout, oil spill, and associated cleanup activities.

Although the most recent EISs prepared by this Agency for oil and gas lease sales in the Gulf of 

Mexico analyze the potential impacts from smaller oil spills that are more reasonably foreseeable 

(USDOI, MMS, 2007 and 2008), this analysis focuses on the most likely and most significant impacts 

created by a high-volume, extended-duration spill. Because catastrophic consequences may not occur for 

all resources, factors affecting the severity of impacts are identified by the individual resource.

A.1.3. How to Use This Analysis

The purpose of this technical analysis is to assist BOEM in meeting CEQ requirements that require a 

discussion of impacts from catastrophic events. This analysis, based on credible scientific evidence, 

identifies the most likely and most significant impacts from a high-volume blowout and oil spill that 

continues for an extended period of time. The scenario and impacts discussed in Chapters A.2 and A.3

should not be confused with the scenario and impacts anticipated to result from routine activities or the 

more reasonably foreseeable accidental events of a WPA proposed action.
A-4 Western Planning Area Lease Sale 248 Supplemental EIS

Chapter A.2 is intended to clearly describe the scenario presented for all four phases of a 

catastrophic blowout event and identify the impact-producing factors associated with each phase. 

Chapter A.3 is intended to analyze the impacts of each phase of a catastrophic blowout on various 

environmental resources. These chapters can be used to differentiate the conditions of a catastrophic spill 

from the routine activities and accidental events described in this Supplemental EIS. 

This technical analysis is designed to be incorporated by reference in future NEPA documents and 

consultations. Therefore, factors that affect the severity of impacts of a high-volume, extended-duration 

spill on individual resources are highlighted for use in subsequent site-specific analyses.

To analyze a hypothetical catastrophic event in an area such as the Gulf of Mexico, several 

assumptions and generalizations were made. However, future project-specific analyses should also 

consider specific details such as potential flow rates for the specific proposed activity, the properties of 

the targeted reservoir, and the proximity to environmental resources of the proposed activities. 

A.2. IMPACT-PRODUCING FACTORS AND SCENARIO (PHASES 1-4)

For the purposes of this analysis, an event similar to the Ixtoc I well blowout and spill that occurred in 

1979 in 160-ft (50-m) water depth will be used as the basis for a shallow water spill and an event similar 

to the Macondo well blowout and spill that occurred in 2010 in the Mississippi Canyon area in 5,000-ft 

(1,524-m) water depth will be used to represent a deepwater spill.

A.2.1. Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout incident. While most of the 

environmental and socioeconomic impacts of a catastrophic blowout would occur during the ensuing 

high-volume, extended-duration spill (refer to Chapter A.3), it is important to acknowledge the deadly 

events that could occur in the initial phase of a catastrophic blowout. The following scenario was 

developed to provide a framework for identifying the most likely and most significant impacts during the 

initial phase.

Impacts, response, and intervention depend on the spatial location of the blowout and release. While 

there are several points where a blowout could occur, four major distinctions that are important to the 

analysis of impacts are described in Table A-1. 

For this analysis, an explosion and subsequent fire are assumed to occur. If a blowout associated with 

the drilling of a single exploratory well occurs, a fire could result that would burn for 1 or 2 days. If a 

blowout occurs on a production platform, other wells could feed the fire, allowing it to burn for over a 

month (USDOC, NOAA, Office of Response and Restoration, 2010b). The drilling rig or platform may 

sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. For example, when the drilling rig Deepwater Horizon sank, it landed 1,500 ft (457 m) 

away on the seafloor. Regardless of water depth, the immediate response would be from search and 

rescue vessels and aircraft, such as U.S. Coast Guard (USCG) cutters, helicopters, and rescue planes.

A.2.2. Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters.

A.2.2.1. Duration of Spill

The duration of the offshore spill from a blowout depends on the time needed for intervention and the 

time the remaining oil persists offshore. If a blowout occurs and the damaged surface facilities preclude 

well reentry operations, a relief well may be needed to regain control. The time required to drill the relief 

well depends on the complexity of the intervention, the location of a suitable rig, the type of operation 

that must be terminated to release the rig (e.g., casing may need to be run before releasing the rig), and the 

logistics in mobilizing personnel and equipment to the location. A blown-out well may also be 

successfully capped prior to completion of relief wells, as occurred in the Macondo well blowout. In 

terms of persistence of spilled oil on surface waters, oil from the Macondo well blowout did not persist 

for more than 30 days (OSAT, 2010). However, based on BOEM’s weathering modeling (refer to 
Catastrophic Spill Event Analysis A-5 

Appendix C of the WPA 238/246/248 Supplemental EIS), it is assumed that oil could persist on surface 

waters for as long as 1-2 months, depending on the season and year. 

A.2.2.1.1. Shallow Water

If a blowout occurs in shallow water, it is estimated that the entire well intervention effort, including 

drilling relief wells, if deemed necessary, could take 2 weeks to 3 months. This estimate would include 

1-3 weeks to transport the drilling rig to the well site. Spilled surface oil is not expected to persist more 

than 1-2 months (depending upon the season and environmental conditions) after the flow is stopped. 

Spilled oil is more likely to persist in the offshore environment during colder weather and during wind 

and hydrodynamic conditions that keep the oil offshore. Therefore, the estimated spill duration resulting 

from a shallow water blowout is 11⁄2-5 months (approximately 2 weeks to 3 months for active spillage and 

1-2 months for oil persistence in the environment). 

A.2.2.1.2. Deep Water

If a blowout occurs in deep water, it is estimated that it would take 2-4 weeks to remove debris and to 

install a capping stack or a cap and flow system on a well, if conditions allow this type of intervention. 

The entire intervention effort, if it required drilling relief wells, could take 3-4 months (USDOI, MMS, 

2000; Regg, 2000). This includes 2-4 weeks to transport the drilling rig to the well site. Spilled surface 

oil is not expected to persist more than 1-2 months (depending upon the season and environmental 

conditions) after the flow is stopped. Spilled oil is more likely to persist in the offshore environment 

during colder weather and during wind and hydrodynamic conditions that keep the oil offshore. 

Therefore, the estimated spill duration from a deepwater blowout is 11⁄2-6 months (approximately 2 weeks 

to 4 months for active spillage and 1-2 months for oil persistence in the environment). 

A.2.2.2. Area of Spill

When oil reaches the sea surface, it spreads. The speed and extent of spreading depends on the type 

and volume of oil that is spilled. However, a catastrophic spill would likely spread to hundreds of square 

miles. Also, the oil slick may break into several smaller slicks, depending on local wind patterns that 

drive the surface currents in the spill area.

Subsurface oil observed during both the Ixtoc I and Macondo well blowouts and spills could also 

spread to significant distances depending on environmental conditions (such as hydrodynamics), oil 

chemistry and weathering, and the application of subsea dispersants or mechanical conditions at the 

release point that would diffuse the oil.

A.2.2.3. Volume of Spill

After 50 years of oil and gas exploration and development activity on the continental shelf of the Gulf 

of Mexico, most of the largest oil and natural gas reservoirs thought to exist in shallow-water areas of the 

GOM at drill depths less than 15,000 ft (4,572 m) subsea have been identified. Large undiscovered 

hydrocarbon reservoirs are still thought to exist in shallow-water areas. However, results taken from 

BOEM’s most recent resource assessment study and a review of the more recent shallow-water drilling 

and leasing activity suggest that future discoveries of large reservoirs in the shallow-water areas of the 

GOM are likely to exist greater than 15,000 ft (4,572 m) below sea level where geologic conditions are 

more favorable for natural gas reservoirs to exist than oil reservoirs. In contrast to the shallow-water 

areas of the GOM where the discovery of a new, large, prolific oil reservoir is considered a lowprobability event, the results from BOEM’s resource assessment study pertaining to the deeper water 

areas of the GOM suggest that there is a high probability that many large oil and gas reservoirs have yet 

to be discovered in deep water. BOEM’s forecast for deep water has support from other public and 

private sector resource studies. The forecast is also supported by the results of BOEM’s analysis of 

deepwater leasing and drilling activity, which indicates that the industry is leasing acreage in deepwater 

areas of the GOM where large prospects can be identified and where the majority of exploration and 

development drilling activity targets potentially thick oil reservoirs capable of achieving the high 

production rates necessary to offset the high costs associated with deep water oil development in the 

GOM.
A-6 Western Planning Area Lease Sale 248 Supplemental EIS

A.2.2.3.1. Shallow Water

For this analysis, an uncontrolled flow rate of 30,000 bbl per day is assumed for a catastrophic 

blowout in shallow water. This assumption is based upon the results of well tests in shallow water and 

the maximum flow rate from the 1979 Ixtoc I well blowout, which occurred in shallow water. Using this 

flow rate, the total volume of oil spilled from a catastrophic blowout in shallow water is estimated at 

900,000 bbl to 3 MMbbl from spillage occurring over 1-3 months. In addition to the flow rate, it is 

assumed that any remaining diesel fuel from a sunken drilling rig or platform would also leak. 

A.2.2.3.2. Deep Water

For the purposes of this analysis, an uncontrolled flow rate of 30,000-60,000 bbl per day is assumed 

for a catastrophic blowout in deep water. This flow rate is based on the assumption in Chapter A.2.2.3.1

above, well test results, and the maximum flow rate estimated for the Macondo well blowout and spill 

that occurred in deep water. Therefore, the total volume of oil spilled is estimated to be 0.9-7.2 MMbbl 

over 1-4 months. In addition, deepwater drilling rigs or platforms hold a large amount of diesel fuel 

(10,000-20,000 bbl). Therefore, it is assumed that any remaining diesel fuel from a sunken structure 

would also leak and add to the spill. 

A.2.2.4. Oil in the Environment: Properties and Persistence

The fate of oil in the environment depends on many factors, such as the source and composition of the 

oil, as well as its persistence (NRC, 2003). Persistence can be defined and measured in different ways 

(Davis et al., 2004), but the National Research Council (NRC) generally defines persistence as how long 

oil remains in the environment (NRC, 2003, page 89). Once oil enters the environment, it begins to 

change through physical, chemical, and biological weathering processes (NRC, 2003). These processes 

may interact and affect the properties and persistence of the oil through the following: 

• evaporation (volatilization);

• emulsification (the formation of a mousse); 

• dissolution;

• oxidation (including respiration); and

• transport processes (NRC, 2003; Scholz et al., 1999). 

Horizontal transport takes place via spreading, advection, dispersion, and entrainment while vertical 

transport takes place via dispersion, entrainment, Langmuir circulation, sinking, overwashing, 

partitioning, and sedimentation (NRC, 2003). The persistence of an oil slick is influenced by the 

effectiveness of oil-spill response efforts and affects the resources needed for oil recovery (Davis et al., 

2004). The persistence of an oil slick may also affect the severity of environmental impacts as a result of 

the spilled oil. 

Crude oils are not a single chemical, but instead are complex mixtures with varied compositions. 

Thus, the behavior of the oil and the risk the oil poses to natural resources depends on the composition of 

the specific oil encountered (Michel, 1992). Generally, oils can be divided into three groups of 

compounds: (1) light-weight; (2) medium-weight; and (3) heavy-weight components. On average, these

groups are characterized as outlined in Table A-2. 

Of the oil reservoirs sampled in the Gulf of Mexico OCS, the majority fall within the light-weight 

category, while less than one quarter are considered medium-weight and a small portion are considered 

heavy-weight. Oil with an American Petroleum Institute (API) gravity of 10.0 or less would sink and has 

not been encountered in the Gulf of Mexico OCS; therefore, it is not analyzed in this Appendix (USDOI, 

BOEMRE, 2010a).

Heavy-weight oil may persist in the environment longer than the other two types of oil, but the 

medium-weight components within oil present the greatest risks to organisms because, with the exception 

of the alkanes, these medium-weight components are persistent, bioavailable, and toxic (Michel, 1992). 
Catastrophic Spill Event Analysis A-7 

Previous studies (e.g., Johansen et al., 2001) supported the theory that most, if not all, released oil 

would reach the surface of the water column. However, data and observations from the Macondo well 

blowout and spill challenge that theory. While analyses are in their preliminary stages, it appears that 

measurable amounts of hydrocarbons (dispersed or otherwise) were detected in the water column as 

subsurface “plumes” and on the seafloor in the vicinity of the release. While not all of these 

hydrocarbons have been definitively traced back to releases from the Macondo well, these early 

measurements and results warrant a reassessment of previous theories of the ultimate fate of hydrocarbons 

from unintended subsurface releases. It is important to note that the North Sea experiment (Johansen 

et al., 2001) did not include the use of dispersants at or near the source of the subsea oil discharge.

A.2.2.5. Release of Natural Gas

The quality and quantity of components in natural gas vary widely by the field, reservoir, or location 

from which the natural gas is produced. Although there is not a “typical” makeup of natural gas, it is 

primarily composed of methane (NaturalGas.org, 2012). Thus, if natural gas were to leak into the 

environment, methane may be released into the environment. Limited research is available for the 

biogeochemistry of hydrocarbon gases in the marine environment (Patin, 1999, page 233). Theoretically, 

methane could stay in the marine environment for long periods of time (Patin, 1999, page 237) as 

methane is highly soluble in seawater at the high pressures and cold temperatures found in deepwater 

environments (NRC, 2003, page 108). Methane diffusing through the water column would likely be 

oxidized in the aerobic zone and would rarely reach the air-water interface (Mechalas, 1974, page 23). 

Methane is a carbon source and its introduction into the marine environment could result in diminished 

dissolved oxygen concentrations due to microbial degradation. 

The Macondo well blowout and spill resulted in the emission of an estimated 9.14 x 109

 to 1.29 x 1010

moles of methane from the wellhead (Kessler et al., 2011; Valentine et al., 2010) with maximum 

subsurface methane concentrations of 183-315 micromoles measured in May/June 2010 (Valentine et al., 

2010; Joye et al., 2011). This methane release corresponded to a measurable decrease in oxygen in the 

subsurface plume due to respiration by a community of methanotrophic bacteria. During the Macondo

well blowout and spill, methane and oxygen distributions were measured at 207 stations throughout the 

affected region (Kessler et al., 2011). Based on these measurements, it was concluded that within 

~120 days from the onset of release ~3.0 x 1010 to 3.9 x 1010 moles of oxygen were respired, primarily by 

methanotrophs, and left behind a residual microbial community containing methanotrophic bacteria. The 

researchers further suggested that a vigorous deepwater bacterial bloom respired nearly all the released 

methane within this time and that by analogy, large-scale releases of methane from hydrates in the deep 

ocean are likely to be met by a similarly rapid methanotrophic response. However, hypoxic conditions 

were never reached (OSAT, 2010). Hypoxic conditions are generally agreed to occur when dissolved 

oxygen falls below 2 milligrams/liter (1.4 milliliter/liter) (OSAT, 2010). Note that methane released from 

the Macondo well blowout and spill was generally confined to the subsurface, with minimal amounts 

reaching the atmosphere (Kessler et al., 2011; Ryerson et al., 2011).

A.2.2.6. Deepwater Subsea Containment

The NTL 2010-N10 requires that offshore operators address containment system expectations to be 

able to rapidly contain a spill as a result of a loss of well control from a subsea well. This resulted in the 

development of rapid response containment systems that are available through either the Marine Well 

Containment Company (MWCC) or Helix Well Ops in the Gulf of Mexico. In addition, industry has a 

multitude of vendors available within the GOM region that can provide the services and supplies 

necessary for debris removal capability, dispersant injection capability, and top-hat deployment 

capability. Many of these vendors are already cited for use by MWCC and Helix Well OPs. The Bureau 

of Safety and Environmental Enforcement (BSEE) has indicated to BOEM that it will not allow an 

operator to begin drilling operations until adequate subsea containment and collection equipment, as well 

as subsea dispersant capability, is determined by BSEE to be available to the operator and is sufficient for 

use in response to a potential incident from the proposed well(s). 
A-8 Western Planning Area Lease Sale 248 Supplemental EIS

Marine Well Containment Company

The Marine Well Containment Company’s (MWCC’s) containment system includes two modular 

capture vessels (MCVs); enhanced subsea umbilicals, risers, and flowlines (SURF) equipment; three 

capping stacks; and additional ancillary equipment. The capping stack is uniquely designed to shut off 

the flow of fluid from the well or to provide a conduit to safely flow well fluids to the two MCVs. The 

processing equipment on the MCVs can separate sand and process liquids and gases flowed from a 

damaged subsea well. The MWCC Containment System is built for use in the deepwater U.S. Gulf of 

Mexico, defined as water depths from 500-1,000 ft to 10,000 ft (152-305 m to 3,048 m), in temperatures 

up to 350 °F (177 °C), and under pressure up to 15,000 pounds per square inch (psi). The MWCC’s suite 

of containment equipment enables the company to mobilize and deploy the most appropriate well 

containment technology based upon the unique well control incident and equipment requirements. The 

system has the capacity to contain up to 100,000 bbl of liquid per day (4.2 million gallons/day) and 

handle up to 200 million standard cubic feet of gas per day. The containment system combines 

equipment from the company’s previous interim containment system and the expanded containment 

system. This system is designed to fully contain oil flow in the event of a potential future underwater 

blowout and to address a variety of scenarios. It is envisioned that this system could be fully operational 

within days to weeks after a spill event occurs (MWCC, 2015). 

The Marine Well Containment Company’s SURF equipment, which is used to flow fluid from the 

capping stack to the MCVs, as well as to provide dispersant and hydrate mitigation injection, is staged in 

Theodore, Alabama. The MWCC houses, stores, and tests the processing equipment for the two MCVs, 

as well as its capping stacks in Ingleside, Texas. The companies that originated this system have formed 

a nonprofit organization, the Marine Well Containment Company (MWCC), to operate and maintain the 

system (MWCC, 2015). The MWCC will provide fully trained crews to operate the system, will ensure 

the equipment is operational and ready for rapid response, and will conduct research on new containment 

technologies (MWCC, 2015). 

In the summer of 2012, a full-scale deployment of the MWCC’s critical well-control equipment to 

exercise the oil and gas industry’s response to a potential subsea blowout in the deepwater of the Gulf of 

Mexico was conducted by BSEE. The MWCC’s 15,000 psi capping stack system, a 30-ft (9-m) tall, 

100-ton piece of equipment similar to the one that stopped the flow of oil from the Macondo well 

following the Deepwater Horizon explosion in 2010, was successfully tested during this deployment drill. 

During this exercise, the capping stack was deployed from its storage location in Ingleside, Texas, to an 

area in the Gulf of Mexico nearly 200 mi (322 km) from shore. Once on site, the system was lowered to a 

simulated wellhead (a pre-set parking pile) on the ocean floor in nearly 7,000 ft (2,134 m) of water, 

connected to the wellhead, and then pressurized to 10,000 psi. 

Helix Well Ops

Another option for source control and containment in the Gulf of Mexico is through Helix Well Ops. 

Helix Well Ops contracted the equipment that it found useful in the Deepwater Horizon explosion, oil 

spill, and response and offered it to oil and gas producers for use beginning January 1, 2011. This system 

focused on the utilization of the Helix Producer I and the Q4000 vessels. Each of these vessels played a 

role in the Deepwater Horizon explosion, oil spill, and response and was continually working in the Gulf

of Mexico. Helix Well Ops’ system, which is referred to as the Helix Fast Response System (HFRS), 

currently has the ability to fully operate in up to 10,000 ft (3,048 m) of water and has intervention 

equipment to cap and contain a well with the mechanical integrity to be shut-in. The HFRS also has the 

ability to capture and process 57,000 bbl of oil per day, 72,000 bbl of liquid per day, and 120 million 

standard cubic feet per day at 10,000 psi (Helix Energy Solutions Group, 2015). 

In April-May 2013, a full-scale deployment of Helix Well Ops’ critical well-control equipment to 

exercise the oil and gas industry’s response to a potential subsea blowout in the deepwater of the Gulf of 

Mexico was conducted by BSEE. Helix Well Ops’ capping stack system is a 20-ft (6-m) tall, 

146,000-pound piece of equipment similar to the one that stopped the flow of oil from the Macondo well 

following the Deepwater Horizon explosion in 2010. It was successfully tested during this unannounced 

deployment drill. The capping stack was deployed from its storage location and once onsite, the system 

was lowered to a simulated wellhead (a pre-set parking pile) on the ocean floor in nearly 5,000 ft 

(1,524 m) of water, connected to the wellhead, and then pressurized to 8,400 psi. 
Catastrophic Spill Event Analysis A-9 

A.2.2.7. Offshore Cleanup Activities

As demonstrated by the Ixtoc I and Macondo well blowouts and spills, a large-scale response effort is 

certain to follow a catastrophic blowout. The number of vessels and responders would steadily increase 

as the spill continued. In the event of a spill, particularly a loss of well control, there is no single method 

of containment and removal that would be 100 percent effective. Removal and containment efforts to 

respond to an ongoing spill offshore would likely require multiple technologies, including source 

containment, mechanical cleanup, in-situ burning of the slick, and chemical dispersants. Even with the 

deployment of all of these spill-response technologies, it is likely that, with the operating limitations of 

today’s spill-response technology, not all of the oil could be contained and removed offshore. 

A.2.2.7.1. Shallow Water

The following are estimates for the deployment of equipment and personnel during a shallow-water 

spill response. Within the first week of an oil spill originating in shallow water, 25 vessels are estimated 

to respond, which would steadily increase to over 3,000 by the end of the spill. This includes about 

25 skimmers in the vicinity of the well at any given time. In addition, recovered oil may be barged to 

shore from recovery vessels. Within the first week, over 500 responders are estimated to be deployed to a 

spill originating in shallow water, which would steadily increase up to 25,000 before the well is capped or 

killed within 2-4 months. Up to 25 planes and 50 helicopters are estimated to respond per day by the end 

of a shallow-water spill. Response to an oil spill in shallow water is expected to involve over 10,000 ft 

(3,048 m) of boom within the first week and would steadily increase up to 5 million feet (~950 mi; 

~1,520 km) for use offshore and nearshore; the amount is dependent upon the location of the potentially 

impacted shoreline, environmental considerations, and agreed upon protection strategies involving the 

local potentially impacted communities.

Dispersant use must be in accordance with the Regional Response Team’s (RRT) Preapproved

Dispersant Use Manual and with any conditions outlined within an RRT’s site-specific, dispersant 

approval given after a spill event. Consequently, dispersant use would be in accordance with the 

restrictions for specific water depths, distances from shore, and monitoring requirements. At this time, 

this manual does not give preapproval for the application of dispersant use subsea. Aerial dispersants 

would likely be applied from airplanes as a mist, which settles on the oil on the water’s surface. Along 

the Gulf Coast, surface dispersants are presently preapproved for use greater than 3 nautical miles (nmi) 

(3.5 mi; 5.6 km) from shore and in water depths greater than 33 ft (10 m), with the exception of Florida 

(U.S. Dept. of Homeland Security, CG, 2010). At this time, pursuant to a letter from the Florida 

Department of Environmental Protection dated May 5, 2011, sent to USCG, preapproval for dispersant 

use is not approved for any Florida State waters. However, the U.S. Environmental Protection Agency 

(USEPA) is presently revisiting these RRT preapprovals in light of the dispersant issues, such as subsea 

application that arose during the Macondo well blowout and spill response. In addition, revisions are 

presently being made to the RRT IV and VI’s Preapproved Dispersant Use Manuals. The USEPA issued 

a letter dated December 2, 2010, that provided interim guidance on the use of dispersants for major spills 

that are continuous and uncontrollable for periods greater than 7 days and for expedited approval of 

subsurface applications. This letter outlined the following exceptions to the current preapprovals until 

they are updated:

• dispersants may not be applied to major spills that are continuous in nature and 

uncontrollable for a period greater than 7 days; 

• additional dispersant monitoring protocols and sampling plans may be developed that 

meet the unique needs of the incident; and 

• subsurface dispersants may be approved on an incident-specific basis as requested by 

the USCG On-Scene Commander.

More robust documentation of dispersant usage may be required. This documentation would include 

daily reports that contain the products used, the specific time and locations of application, equipment used 

for each application, spotter aircraft reports, photographs, vessel data, and analytical data. In addition to 
A-10 Western Planning Area Lease Sale 248 Supplemental EIS

dispersants, controlled burns may also occur. It is estimated that 5-10 controlled burns would be 

conducted per day in suitable weather. About 500 burns in all would remove 5-10 percent of the oil.

A.2.2.7.2. Deep Water

The following are estimates for the deployment of equipment and personnel during a deepwater spill 

response. Within the first week of an oil spill originating in deep water, 50 vessels are estimated to 

respond, which would steadily increase to over 7,000 by the end of the spill. This includes about 

25 skimmers in the vicinity of the well at a time. In addition, recovered oil may be shuttle tankered to 

shore from recovery vessels. For an oil spill in deep water, over 1,000 responders are estimated to be 

deployed within the first week, which would steadily increase up to 50,000 before capping or killing the 

well within 4-5 months. Over 20,000 ft (6,096 m) of boom is estimated to be deployed within the first 

week of a deepwater spill, which would steadily increase up to 13.5 million feet (~2,257 mi; ~4,115 km) 

offshore and nearshore. The amount of boom would be dependent upon the location of the potentially 

impacted shoreline, environmental considerations, and agreed upon protection strategies involving the 

local potentially impacted communities. Up to 50 planes and 100 helicopters are estimated to respond per 

day by the end of a deepwater spill.

With the exception of special Federal management areas or designated exclusion areas, dispersants 

have been preapproved in the vicinity of a deepwater blowout (U.S. Dept. of Homeland Security, CG, 

2010). However, USEPA is presently examining these preapprovals, and restrictions are anticipated 

regarding the future use of dispersants as a result. No preapproval presently exists for the use of subsea 

dispersants, and approval must be obtained before each use of this technology. The use of subsea 

dispersants depends on the location of the blowout, as discussed in Table A-1. Aerial dispersants are 

usually applied from airplanes as a mist, which settles on the oil on the water’s surface. Major spills that 

are continuous and uncontrollable for periods greater than 7 days and the approval of subsurface 

dispersant application are presently subject to the guidance outlined in USEPA’s letter dated December 2, 

2010. This letter provides interim guidance on the use of dispersants for major spills and outlines 

exceptions to the current preapprovals until they are updated, as discussed more fully in Chapter 

A.2.2.7.1. For a deepwater spill, dispersant application may be a preferred response in the open-water 

environment to prevent oil from reaching a coastal area, in addition to mechanical response. However, 

the window of opportunity for successful dispersant application may be somewhat narrower for some 

deepwater locations depending on the physical and chemical properties of the oil, which tend to be 

somewhat heavier or more likely to emulsify than those found closer to shore. A significant reduction in 

the window of opportunity for dispersant application may render this response option ineffective. 

In addition to dispersants, controlled burns may also occur. It is estimated that 5-10 controlled burns 

would be conducted per day in suitable weather. About 500 burns in all would remove 5-10 percent of 

the oil.

A.2.2.7.3. Vessel Decontamination Stations

To avoid contaminating inland waterways, multiple vessel decontamination stations may be 

established offshore in Federal and State waters. The selected locations to conduct decontamination of 

oiled vessels will, due to the unique aspects of each spill response, be decided by the Unified Command

during the spill response effort. Since the Unified Command includes representatives of the affected 

state(s), the states will have a prominent voice regarding whether a location in State waters will be 

acceptable.

Vessels responding to the spill and commercial and recreational vessels passing through the spill 

would anchor, awaiting inspection. If decontamination is required, work boats would use fire hoses to 

clean oil from the sides of the vessels. This could result in some oiling of otherwise uncontaminated 

waters. While these anchorage areas would be surveyed for buried pipelines that could be ruptured by 

ship anchors, they may not be surveyed adequately for benthic communities or archaeological sites. 

Therefore, some damage to benthic communities or archaeological sites may occur because of vessel 

decontamination activities associated with an oil spill (Alabama State Port Authority, 2010; State of 

Florida, Office of the Governor, 2010; Nodar, 2010; Unified Incident Command, 2010a-c; USDOC, 

NOAA, 2010a; USEPA, 2012).
Catastrophic Spill Event Analysis A-11

A.2.2.8. Severe Weather

A hurricane could accelerate biodegradation, increase the area affected by the spill, and slow or stop 

the response effort. The movement of oil would depend on the track, wind speed, and size of a hurricane. 

The official Atlantic hurricane season runs from June 1st through November 30th, with a peak of 

hurricane probability in September. In an average Atlantic season, there are 11 named storms, 

6 hurricanes, and 2 Category 3 or higher storms (USDOC, NOAA, National Weather Service, 2010). As 

a result of a hurricane, high winds and seas would mix and weather the oil from an oil spill. This can help 

accelerate the biodegradation process (USDOC, NOAA, National Weather Service, 2012). The high 

winds may distribute oil over a wider area (USDOC, NOAA, National Weather Service, 2012). 

Weather has been recognized as one of the most important factors in predicting oil-spill fate and 

behavior and in predicting the success of an oil-spill response. During an oil spill, booms, skimmers, oil 

burn, and the use of dispersants have been used to remove oil from the water surface. Adverse weather 

conditions will affect the use, performance, and effectiveness of booms and skimmers. Skimmers work 

best in calm wind; for wave heights greater than 1 m (3 ft), some skimmers will not work effectively. 

Conventional booms will not work at a current velocity of 0.5 meters per second (m/sec) (1.6 feet per 

second [ft/sec]) or greater. For oil burn, ignition cannot be carried out at wind speeds greater than 

10 m/sec (33 ft/sec). The minimum wind speed for dispersant use is about 5 m/sec (16 ft/sec), and the 

maximum wind speed for the limit of dispersant applications is about 12-14 m/sec (39-46 ft/sec) (Fingas, 

2004). 

There are tradeoffs in deciding where and when to place boom because, once deployed, boom is time 

consuming to tend and to relocate. As previously noted, booming operations are sensitive to wind, wave, 

and currents, and those sections of boom need to be tethered and secured to keep them from moving. 

Furthermore, it was discovered during the Deepwater Horizon explosion, oil spill, and response that hard 

boom often did more damage than anticipated in the marsh it was intended to protect after weather 

conditions ended up stranding the boom back into the marsh. Due to time constraints prior to a hurricane 

event, it is therefore unlikely that much effort could be expended to move large amounts of deployed 

boom, particularly given the effort that would be required to move skimming equipment to safer locations 

inland and to move large numbers of response personnel to safer areas. However, since the conditions for 

each spill response are unique, these considerations would be examined and a site-specific hurricane 

response plan developed during the actual spill response effort by the Unified Command at the beginning 

of the official hurricane season.

In addition, adverse weather would reduce ability to respond to the spill and could result in delayed 

transport and placement of the capping stack. The action of wind on the water surface will generate 

waves. Typically, waves greater than 3 ft (1 m) will prevent smaller vessels from skimming in offshore 

waters; waves greater than 5 ft (1.5 m) will prevent even the larger vessels from getting offshore to skim. 

The new high-speed skimmers under development are very promising; some skimmers have recovered oil 

with wave heights of up to 10 ft (3 m) with corresponding winds of up to 15 m/sec (49 ft/sec). 

In the event of a hurricane, vessels would evacuate the area, delaying response efforts, including the 

drilling of relief wells and any well capping or collection efforts. Severe weather, such as a hurricane, 

would delay the transport and placement of the capping stack. If a cap is applied and oil is flowed to a 

collection vessel, severe weather would cause the collection vessel to vacate its location and the oil would 

flow until the collection vessel could return and resume collection. Severe weather could also require that 

response assets be relocated inland. The response would be delayed because following the severe weather 

event the assets would need to be transported back to the staging areas. The speed with which the assets 

could be brought back to the locations would depend upon on the condition of the roads and bridges for 

traffic resumption and the amount of debris potentially blocking the roads. 

A.2.3. Phase 3—Onshore Contact

A.2.3.1. Duration

The duration of shoreline oiling is measured from initial shoreline contact until the well is capped or 

killed and the remaining oil dissipates offshore. The time needed to cap or kill a well may vary, 

depending on, among other things, the well’s water depth, its location, the well and geologic formation 

characteristics, and the associated debris. Depending on the spill’s location in relation to winds and 

currents and the well’s distance to shore, oil could reach the coast within 1 week to 1 month, based on 
A-12 Western Planning Area Lease Sale 248 Supplemental EIS

evidence from previous spills in the Gulf of Mexico OCS (e.g., it was nearly 4 weeks after the Macondo

well blowout and spill). While it is assumed that the majority of spilled oil would dissipate offshore

within 30-60 days of stopping the flow, some oil may remain in coastal areas for some time after a spill, 

as was observed along the Gulf Coast following the Macondo well blowout and spill. 

A.2.3.1.1. Shallow Water

Due to the distance from shore, oil spilled as a result of a blowout in shallow water could reach shore 

within 1-3 weeks and could continue until the well is killed or capped and the oil dissipates offshore. 

Therefore, it is estimated that initial shoreline oiling would likely occur for 2-5 months following a 

catastrophic blowout. Some shoreline areas could be re-oiled during this timeframe dependent upon the 

weather conditions at the time of the spill as well as the persistence of the spilled oil.

A.2.3.1.2. Deep Water

Intervention is more difficult and would take longer in deeper water, in part, because at these water 

depths these intervention efforts are conducted by remotely operated vehicles. In general, most of the 

deep water in the Gulf of Mexico is located farther from shore and, therefore, it is assumed that oil would 

reach shore within 2-4 weeks. However, for the few deepwater areas that are located closer to shore, such 

as in the Mississippi Canyon Area, the amount of estimated time until shoreline contact could be the same 

as the shallow-water scenario above (1-3 weeks). The length of shoreline oiled would continue to 

increase and previously oiled areas could be re-oiled until the well is killed or capped (3-4 months) and 

the oil dissipates offshore (1-2 months). Therefore, initial shoreline oiling could occur from 3 months up 

to 6 months following a catastrophic blowout. Persistent shoreline oiling is discussed in Chapter A.2.4

(Phase 4) below.

A.2.3.2. Volume of Oil Contacting Shore

In the event of a catastrophic spill, not all of the oil spilled would contact shore. The amount of oil 

recovered and chemically or naturally dispersed would vary. For example, the following are recovery and 

cleanup rates from previous high-volume, extended spills:

• 10-40 percent of oil recovered or cleaned up (including burned, chemically dispersed, 

and skimmed); 

• 25-40 percent of oil naturally dispersed, evaporated, or dissolved; and 

• 20-65 percent of the oil remains available for offshore or inshore contact. 

In the case of the Macondo well blowout and spill, the “expected” scenario, developed by the Oil 

Budget Calculator Science and Engineering Team of The Federal Interagency Solutions Group, suggests 

that more than one quarter (29%) was naturally or chemically dispersed into Gulf waters, while burning,

skimming, and direct recovery from the wellhead removed one quarter (25%) of the oil released. Less 

than one quarter (23%) of the total oil naturally evaporated or dissolved. The residual amount, just under 

one quarter (23%), remained in the Gulf of Mexico as a light sheen or as tarballs that have washed ashore 

or are buried in sand and other sediments (Federal Interagency Solutions Group, 2010). 

For planning purposes, USCG estimates that 5-30 percent of oil will reach shore in the event of an 

offshore spill (33 CFR part 154, Appendix C, Table 2). Using the USCG assumptions, a catastrophic spill 

could result in a large amount of oil reaching shore. 

A.2.3.3. Length of Shoreline Contacted

While larger spill volumes increase the chance of oil reaching the coast, other factors that influence 

the length and location of shoreline contacted include the duration of the spill and the well’s location in 

relation to winds, currents, and the shoreline. Depending upon winds and currents throughout the spill 

event, already impacted areas could be re-oiled. As seen with the Deepwater Horizon oil spill, as the spill 

continued, the length of oiled shoreline at any one time increased by orders of magnitude as follows: 
Catastrophic Spill Event Analysis A-13

Duration of Spill Length of Shoreline Oiled1

 30 days 0-50 miles

 60 days 50-100 miles

 90 days 100-1,000 miles

120 days >1,000 miles2

1 Not cumulative.

2 Length was extrapolated.

Source: USDOC, NOAA, 2011a.

A.2.3.3.1. Shallow Water

While a catastrophic spill from a shallow-water blowout is expected to be lower in volume than a 

deepwater blowout, as explained in Chapter A.2.2.3, the site would typically be closer to shore, allowing 

less time for oil to be weathered, dispersed, and recovered. This could result in a more concentrated and 

toxic oiling of the shoreline. 

A.2.3.3.2. Deep Water

While a catastrophic spill from a deepwater blowout is expected to have a much greater volume than 

a shallow-water blowout (refer to Chapter A.2.2.3), the site would typically be farther from shore, 

allowing more time for oil to be weathered, dispersed, and recovered. This could result in broader, 

patchier oiling of the shoreline.

Translocation of the spilled oil via winds and currents is also a factor in the length of shoreline 

contacted. For example, oil could enter the Loop Current and then the Gulf Stream. However, the longer 

it takes oil to travel, the more it would degrade, disperse, lose toxicity, and break into streamers and 

tarballs (USDOC, NOAA, Office of Response and Restoration, 2010d). 

A.2.3.4. Severe Weather

The official Atlantic hurricane season runs from June 1st through November 30th, with a peak in 

hurricane probability in September. In an average Atlantic season, there are 11 named storms, 

6 hurricanes, and 2 Category 3 or higher storms (USDOC, NOAA, National Weather Service, 2010). In 

the event of a hurricane, vessels would evacuate the area, delaying response efforts, including the drilling 

of relief wells. The storm surge may push oil to the coastline and inland as far as the surge reaches, or the 

storm surge may remove the majority of oil from shore, as seen in some of the previous spills reviewed.

Movement of oil during a hurricane would depend greatly on the track of the hurricane in relation to 

the slick. A hurricane’s winds rotate counter-clockwise. In general, a hurricane passing to the west of the 

slick could drive oil to the coast, while a hurricane passing to the east of the slick could drive the oil away 

from the coast.

Severe weather may distribute spilled oil over a wide area. Storm surge may carry oil into the coastal 

and inland waters and shore. Debris resulting from severe weather may be contaminated by oil. Thus, 

the responders need to take proper precautions if weathered oil is present. Weather that results in waves 

greater than 3 ft (1 m) prevents skimming in coastal waters so there is greater likelihood of contact with 

the shoreline. Severe weather would also displace or destroy shoreline boom so that oil could come into 

contact with the shoreline until responders put the boom back in place. Severe weather could require that 

assets be relocated inland. The response would be delayed because following the severe weather event 

the assets would need to be transported back to the staging areas. The speed with which the assets could 

be brought back to the locations would depend upon on the condition of the roads and bridges for traffic 

resumption and the amount of debris potentially blocking the roads. 

The USEPA, USCG, other Federal response agencies, and applicable State agencies would work 

together to address oil spills reported to the National Response Center or reported by emergency 

responders before, during, or after a hurricane occurs. Response personnel will cleanup significant spills 

and take other actions appropriate to protect public health and the environment. This response would 

cover any OCS spills that may occur as a result of the hurricane or preexisting at the time of the 
A-14 Western Planning Area Lease Sale 248 Supplemental EIS

hurricane. Response activities may be interrupted or complicated during a hurricane event. Oil from an 

ongoing OCS spill event may be washed ashore during a hurricane event; could be weathered, diluted, or 

washed farther inland; and could be mixed with other contaminants from other sources released during a 

hurricane event (e.g., heating oil or industrial chemicals). For example, onshore sources account for most 

of the oil spilled during the past few hurricane seasons that has resulted in oiled property. After 

Hurricane Sandy, some oil heating tanks flooded and caused oiling of a property owner’s own building(s). 

As such, depending on circumstances, a hurricane event during an OCS spill event could complicate and 

exacerbate spill impacts and response operations, but could also increase weathering and dilution. 

A.2.3.5. Onshore Cleanup Activities

A large-scale response effort would be expected for a catastrophic blowout. The number of vessels 

and responders would increase steadily as the spill continued. In addition to the response described in 

Chapter A.2.2.7, the following response is also estimated to occur once the spill contacts the shore.

A.2.3.5.1. Shallow Water

• There would be 5-10 staging areas established.

• Weather permitting, about 200-300 skimmers could be deployed near shore to protect 

coastlines.

A.2.3.5.2. Deep Water

• There would be 10-20 staging areas established.

• Weather permitting, about 500-600 skimmers could be deployed near shore to protect 

coastlines. As seen in Louisiana following the Macondo well blowout and spill, a 

few hundred coastal skimmers could still be in operation a few months after the well 

is capped or killed (State of Louisiana, 2010).

A.2.3.5.3. Response Considerations for Sand Beaches for Both Shallow-Water and 

Deepwater Spills

• No mechanical techniques allowed in some areas.

• Surface residence balls (SRBs), also commonly known as tarballs, and surface 

residence patties (SRPs) are subject to smearing during the day; therefore, much of 

the beach cleanup can be expected to be conducted at night, if the weather is warm.

• There are marked differences in the sediments on the central Louisiana coast as 

compared with the Gulf beaches of Alabama, Florida, and Mississippi; therefore, no 

single technique will be universally applicable for cleaning sand beaches.

• Typically, sand sieving, shaking, and sifting beach cleaning machines will be 

utilized. The depth of cut below the sand surface can be expected to typically range 

from 0 to 12 inches (in) (0 to 30 centimeters [cm]) when using this equipment. 

• It is anticipated that the responders will be instructed that no disturbance will be 

allowed below 18 in (46 cm). However, oil can be expected down to a depth of 

24-26 in (61-66 cm) below the sand surface. 

• Repetitive tilling and mixing may be used at beaches such as Grand Isle, using 

agriculture plows and discs in combination with beach cleaning machines. Sand 

washing treatment also may take place at beaches such as Grand Isle’s beach. Sand 

washing includes a sand sieve/shaker to remove debris and large oil particles and a 

heated washing system. Average daily throughput for these systems would be 
Catastrophic Spill Event Analysis A-15

290 cubic yards per day. Sand treated in this manner is typically treated by sediment 

relocation, which is where the sand is moved to an active intertidal zone 

A.2.3.5.4. Response Considerations for Marshes for Both Shallow-Water and 

Deepwater Spills

• Lightly oiled marsh may be allowed to recover naturally; the oil may be allowed to 

degrade in place or to be removed by tidal or wave action. 

• Moderately or heavily oiled marsh could be cleaned by vacuuming or skimming from 

boats in conjunction with flushing to enhance oil recovery rates, low pressure 

flushing (with water comparable to marsh type), manual removal by hand or 

mechanized equipment, or vegetation cutting.

• In some heavily oiled areas, in-situ burning may be an option if water covers the 

sediment surface. This technique is only considered when the source is contained 

due to potential re-oiling of the area. Surface washing agents are also a technique 

that might be utilized.

• Bioremediation may be utilized but mostly as a secondary treatment after bulk 

removal.

A.2.3.5.5. Response Considerations for Nearshore Waters for Both Shallow-Water 

and Deepwater Spills

• Nearshore submerged oil is difficult to recover and hard to locate; vacuums and 

snares could be used.

• In the vicinity of marsh areas, skimming techniques with flushing could be utilized 

where warranted. In areas too shallow to use skimmers, oil removal could be 

accomplished using vacuum systems, in conjunction with flushing as needed. 

Booming could also be used to temporarily contain mobile slicks until they are 

recovered.

A.2.4. Phase 4—Post-Spill, Long-Term Recovery

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been 

capped or killed and that cleanup activities are concluding. While it is assumed that the majority of 

spilled oil floating on surface waters would be dissipated within 30-60 days of stopping the flow, oil has 

the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill dependent upon the affected environment (USDOI, FWS, 2004). On sandy beaches, 

oil can sink deep into the sediments. In tidal flats and salt marshes, oil may seep into the muddy bottoms 

(USDOI, FWS, 2010a). 

The multiple-year response required for the Deepwater Horizon explosion, oil spill, and response

provided one example of a long-term recovery to a catastrophic spill in the Gulf of Mexico. After the 

Deepwater Horizon explosion, oil spill, and response, a multi-agency Operational Science Advisory 

Team (OSAT), under the direction of the USCG, was convened to provide information to help guide 

response activities and to provide a better understanding of the potential environmental and health risks 

after the Deepwater Horizon explosion, oil spill, and response. A summary of the OSAT findings include

the following: 

• OSAT, issued in December 2010, concluded that no recoverable Macondo oil 

remained in the water column. In addition, none of the roughly 17,000 water samples 

collected and analyzed exceeded the USEPA’s benchmarks for protection of human 

health. 
A-16 Western Planning Area Lease Sale 248 Supplemental EIS

• OSAT-2, issued in February 2011, found that residual oil in nearshore and sandy 

shoreline areas was highly weathered, and concentrations of constituents of concern 

were well below levels of concern for human health (OSAT-2, 2011). 

• The OSAT Ecotoxicity Addendum, issued in July 2011, found that, with respect to 

the indicators considered in the OSAT (2010) report, the results discussed in this 

addendum are consistent with the OSAT conclusions that “no exceedances of the 

USEPA’s dispersant benchmarks were observed” and that “since 3 August 2010 (last 

day with potentially recoverable oil on the ocean surface), <1% of water samples and 

~1% of sediment samples exceeded EPA’s aquatic life benchmarks for polycyclic 

aromatic hydrocarbons (PAHs).” In addition, results of the toxicity tests support the 

conclusions of the OSAT report regarding the distribution of actionable (i.e., 

amenable to removal actions) oil and dispersant-related constituents (OSAT 

Addendum, 2011). 

• OSAT-3, finalized in early 2014, used a sophisticated scientific approach to identify 

potential discrete pockets of subsurface material. The OSAT-3 information was used 

to locate and recover potential subsurface material (British Petroleum, 2014a). The 

OSAT-3 report also identified actions to be taken for reducing the potential 

recurrence of oil along the northeastern shores of the Gulf of Mexico. In addition, 

the report evaluated the feasibility of each action taken to recover or remove 

Macondo oil and the net environmental benefit of employing each recovery technique 

recommended. This scientific support was provided to the Federal On-Scene 

Coordinator with shoreline segment-specific information to facilitate the operational 

decisionmaking process to recover residual Macondo oil (OSAT-3, 2013). 

If a shoreline is oiled, the selection of the type of shoreline remediation to be used will depend on the 

following: (1) the type and amount of oil on the shore; (2) the nature of the affected coastline; (3) the 

depth of oil penetration into the sediments; (4) the accessibility and the ability of vehicles to travel along 

the shoreline; (5) the possible ecological damage of the treatment to the shoreline environment; 

(6) weather conditions; (7) the current state of the oil; and (8) jurisdictional considerations. To determine 

which cleanup method is most appropriate during a spill response, decisionmakers must assess the 

severity and nature of the injury using Shoreline Cleanup and Assessment Team survey observations. 

These onsite decisionmakers must also estimate the time it will take for an area to recover in the absence 

of cleanup (typically considering short term to be 1-3 years, medium term to be 3-5 years, and long term 

greater than 5 years) (National Response Team, 2010).

A.2.4.1. Response Considerations for Sand Beaches, Marshes, and Nearshore 

Waters for both Shallow-Water and Deepwater Spills

Once oiled, it can be expected that the shoreline response techniques employed in the initial phase of 

a response will become more extensive and continue for some time (Chapters A.2.3.5.3, A.2.3.5.4, and 

A.2.3.5.5). For example, spill response post-Macondo continued for years in some of the more heavily 

oiled areas in Louisiana and in other areas, such as Florida, Mississippi, and Alabama, which experienced 

periodic re-oiling from submerged oil mats that lie in the inshore surf zone in troughs between the sand 

bars or from buried oil onshore that resurfaces. The three types of oil residue that were identified as 

challenging or potentially damaging to the environment if removed include the following: (1) supra-tidal 

buried oil (buried below the 6-in [15-cm] surface cleaning depth restriction near sensitive habitats); 

(2) small surface residual balls, which are oil residue left behind after beaches are cleaned; and (3) surf 

zone submerged oil mats. Active shoreline cleanup ended in June 2013 for the States of Florida, 

Mississippi, and Alabama. Active shoreline cleanup for Louisiana ended on April 15, 2014 (British 

Petroleum, 2014a). However, efforts will continue to clean up any reported re-oiled shoreline in the 

GOM area as it is reported to the USCG. Although the re-oiling of some areas was anticipated to 

sporadically continue, it was determined that a better and more efficient long-term cleanup effort at this 

stage could be handled through the USCG. As of April 15, 2014, aerial reconnaissance flights were flown 

across approximately 14,000 mi (22,531 km) of shoreline during this spill response effort. Nearly 

4,400 mi (7,081 km) were ground-surveyed, with teams identifying 1,104 mi (1,777 km) that experienced 
Catastrophic Spill Event Analysis A-17

some level of oiling and 778 mi (1,252 km) that required some measure of cleaning (British Petroleum, 

2014a). 

Amenity beaches were generally cleaned to depths of up to 5 ft (1.5 m) using mechanical equipment 

that sifts out residual oil and other debris from below the beach surface while returning clean sand to the 

beach. Nonrecreational beaches and environmentally sensitive areas were generally hand-cleaned to 

depths of up to 6 in (15 cm), but they were cleaned deeper if it was ecologically safe and approved by the 

USCG, stakeholders, and others. Multiple techniques were used to treat oiled marsh areas, with the goal 

of promoting natural attenuation without causing further damage. A scientific effort was launched in 

mid-2012 to locate and remove potential pockets of subsurface material in Louisiana. During this effort, 

more than 40,000 holes and pits were excavated across seven barrier islands. The vast majority either had 

no visible oil or levels so low that treatment was not appropriate or required. For example, just 3 percent 

of the more than 16,000 auger holes had oiling levels that required cleanup and less than 2 percent of the 

over 24,000 pits had heavy or moderate oiling. Assessment teams continuously surveyed the shoreline 

and recommended treatment options. More than 100,000 tons of material were collected from the 

cleanup efforts. The total consists of not only the mixed residual material, which was typically 

10-15 percent residual oil and 85-90 percent sand, shells, and water, but, during the first year of 

operations, it also included other solid material such as debris and protective clothing (British Petroleum, 

2014a). Additional information regarding shoreline response considerations can be found in Chapter 

3.2.1.9. 

A.3. DESCRIPTION OF THE ENVIRONMENT AND IMPACT ANALYSIS

A.3.1. Long Duration—Large Volume Spill within the Gulf of Mexico

The following resource descriptions and impact analyses examined only the applicable portions of the 

scenario (described fully in Chapter 3 and summarized in Table A-4).

A.3.1.1. Air Quality

Phase 1—Initial Event

A catastrophic blowout close to the water surface would initially emit large amounts of methane and 

other gases into the atmosphere. If high concentrations of sulfur are present in the produced gas, 

hydrogen sulfide (H2S) could present a hazard to personnel. The natural gas H2S concentrations in the 

Gulf of Mexico OCS are generally low; however, there are areas such as the Norphlet formation in the 

northeastern Gulf of Mexico, for example, that contain levels of H2S up to 9 percent. Ignition of the 

blowout gas and subsequent fire would result in emissions of nitrogen oxides (NOx), sulfur oxides (SOx), 

carbon monoxide (CO), volatile organic compounds (VOCs), particulate matter (PM10), and fine 

particulate matter (PM2.5). The fire could also produce PAHs, which are known to be hazardous to human 

health. The pollutant concentrations would decrease with downwind distance. A large plume of black 

smoke would be visible at the source and may extend a considerable distance downwind. However, with 

increasing distance from the fire, the gaseous pollutants would undergo chemical reactions, resulting in 

the formation of fine particulate matter (PM2.5) that includes nitrates, sulfates, and organic matter. The 

PM2.5 concentrations in the plume would have the potential to temporarily degrade visibility in any 

affected Prevention of Significant Deterioration (PSD) Class I areas (i.e., National Wilderness Areas and 

National Parks) and other areas where visibility is of significant value. Organic aerosols formed 

downwind from the Macondo well blowout and spill (de Gouw et al., 2011), during which the lightest 

compounds, the VOCs, in the oil from the Macondo well blowout and spill evaporated within hours and 

during which the heavier compounds took longer to evaporate, contributing to the formation of air 

pollution particles downwind.

Phase 2—Offshore Spill

In the Gulf of Mexico, evaporation from the oil spill would result in concentrations of VOCs in the 

atmosphere, including chemicals that are classified as being hazardous. The VOC concentrations would 

occur anywhere where there is an oil slick, but they would be highest at the source of the spill because the 

rate of evaporation depends on the volume of oil present at the surface. The VOC concentrations would 
A-18 Western Planning Area Lease Sale 248 Supplemental EIS

decrease with distance as the layer of oil gets thinner. The lighter compounds of VOCs would be most 

abundant in the immediate vicinity of the spill site. The heavier compounds would be emitted over a 

longer period of time and over a larger area. Some of the compounds emitted could be hazardous to 

workers in close vicinity of the spill site. The hazard to workers can be reduced by monitoring and using 

protective gear, including respirators, as well as limiting exposure through limited work shifts, rotating 

workers out of high exposure areas, and pointing vessels into the wind. During the Macondo well 

blowout and spill, air samples collected by individual offshore workers of British Petroleum (BP), the 

Occupational Safety and Health Administration (OSHA), and USCG showed levels of benzene, toluene, 

ethylbenzene, and xylene that were mostly under detection levels. All samples had concentrations below 

the OSHA permissible exposure limits and the more stringent ACGIH (American Conference of 

Governmental Industrial Hygienists) threshold limit values (U.S. Dept. of Labor, OSHA, 2010a). 

The VOC emissions that result from the evaporation of oil contribute to the formation of particulate 

matter (PM2.5) in the atmosphere. In addition, VOCs could cause an increase in ozone levels, especially if 

the release were to occur on a hot, sunny day with sufficient concentrations of NOx present in the lower 

atmosphere. However, because of the distance of the proposed WPA lease sale area from shore, the oil 

slick would not likely have any effects on onshore ozone concentrations; however, if there were any 

effects to onshore ozone concentrations, they would likely only be temporary in nature and last at most 

the length of time of the spill duration.

It is assumed that response efforts would include hundreds of in-situ or controlled burns, which would 

remove an estimated 5-10 percent of the volume of oil spilled. This could be as much as 720,000 bbl of 

oil for a spill of 60,000 bbl per day for 90 days. In-situ burning would result in ambient concentrations of 

CO, NOx, SO2, PM10, and PM2.5 very near the site of the burn and would generate a plume of black 

smoke. The levels of PM2.5 could be a hazard to personnel working in the area, but this could be 

effectively mitigated through monitoring and relocating vessels to avoid areas of highest concentrations. 

In an experiment of an in-situ burn off Newfoundland, it was found that CO, SO2, and NO2 were 

measured only at background levels and were frequently below detection levels (Fingas et al., 1995). 

Limited amounts of formaldehyde and acetaldehyde were measured, but concentrations were close to 

background levels. Measured values of dioxins and dibenzofurans were at background levels. 

Measurements of PAHs in the crude oil, the residues, and the air indicated that the PAHs in the crude oil 

are largely destroyed during combustion (Fingas et al., 1995). 

While containment operations may be successful in capturing some of the escaping oil and gas, 

recovery vessels may not be capable of storing the crude oil or may not have sufficient storage capacity. 

In this case, excess oil would be burned; captured gas cannot be stored or piped to shore so it would be 

flared. For example, in the Macondo well blowout and spill, gas was flared at the rate of 100-200 million 

cubic feet per day and oil burned at the rate of 10,000-15,000 bbl per day. The estimated NOx emissions 

are about 13 tons per day. The SO2 emissions would be dependent on the sulfur content of the crude oil. 

For crude oil with a sulfur content of 0.5 percent, the estimated SO2 emissions are about 16 tons per day. 

Particulate matter in the plume would also affect visibility. Flaring or burning activities upwind of a PSD 

Class I area, e.g., the Breton National Wilderness Area, could adversely affect air quality there because of 

increased levels of SO2, PM10, and PM2.5, and because of reduced visibility. 

Phase 3—Onshore Contact

As the spill nears shore, there would be low-level concentrations of odor-causing pollutants 

associated with evaporative emissions from the oil spill. These may cause temporary eye, nose, or throat 

irritation, nausea, or headaches, but the doses are not thought to be high enough to cause long-term harm 

(USEPA, 2010a). However, responders could be exposed to levels higher than OSHA occupational 

permissible exposure levels (U.S. Dept. of Labor, OSHA, 2010b). During the Deepwater Horizon

explosion, oil spill, and response, USEPA took air samples at various onshore locations along the length 

of the Gulf coastline. All except three measurements of benzene were below 3 parts per billion (ppb). 

The highest level was 91 ppb. Emissions of benzene to the atmosphere result from gasoline vapors, auto 

exhaust, and chemical production and user facilities. Ambient concentrations of benzene up to and 

greater than 5 ppb have been measured in industrial areas such as Houston, Texas; in various urban areas 

during rush hour; and inside the homes of smokers (U.S. Dept. of Health and Human Services, 2007). 

The following daily median benzene air concentrations were reported in the Volatile Organic Compound 

National Ambient Database (1975-1985): remote (0.16 ppb); rural (0.47 ppb); suburban (1.8 ppb); urban 
Catastrophic Spill Event Analysis A-19

(1.8 ppb); indoor air (1.8 ppb); and workplace air (2.1 ppb). The outdoor air data represent 300 cities in 

42 states, while the indoor air data represent 30 cities in 16 states (Shah and Singh, 1988). 

During the Deepwater Horizon explosion, oil spill, and response, air samples collected by BP, 

OSHA, and USCG near shore showed levels of benzene, toluene, ethylbenzene, and xylene that were 

mostly under detection levels. Among the 28,000 personal benzene samples taken by BP, there was only 

1 sample where benzene exceeded the OSHA occupational permissible exposure limits, and 6 additional 

validated constituents were in excess of the ACGIH threshold limit value. All other sample 

concentrations were below the more stringent ACGIH threshold limit values (U.S. Dept. of Labor, 

OSHA, 2010a). All measured concentrations of toluene, ethylbenzene, and xylene were well within the 

OSHA occupational permissible exposure levels and ACGIH threshold limit values.

Phase 4—Post-Spill, Long-Term Recovery and Response

There would be some residual air quality impacts after the well is capped or killed. As most of the oil 

would have been burned, evaporated, or weathered over time, air quality would return to pre-oil spill 

conditions. While impacts to air quality are expected to be localized and temporary, adverse effects that 

may occur from the exposure of humans and wildlife to air pollutants could have long-term consequences.

Overall Summary and Conclusion (Phases 1-4) 

The OCS oil- and gas-related catastrophic event could include the release of oil, condensate, or 

natural gas or chemicals used offshore or pollutants from the burning of these products. The air pollutants 

include criteria National Ambient Air Quality Standards (NAAQS) pollutants, volatile and semi-volatile 

organic compounds, H2S, and methane. If a fire was associated with the event, it would produce a broad 

array of pollutants, including all NAAQS-regulated primary pollutants, including NO2, CO, SOx, VOC, 

PM10, and PM2.5. Response activities that could impact air quality include in-situ burning, the use of 

flares to burn gas and oil, and the use of dispersants applied from aircraft. Measurements taken during an 

in-situ burning show that a major portion of compounds was consumed in the burn; therefore, pollutant 

concentrations would be expected to be within the NAAQS. In a recent analysis of air in coastal 

communities, low levels of dispersant components, which are also used in everyday household products, 

were identified. These response activities are temporary in nature and occur offshore; therefore, there are 

little expected impacts from these actions to onshore air quality. Catastrophic events involving high 

concentrations of H2S could result in deaths as well as environmental damage. Regulations and NTLs 

mandate safeguards and protective measures, which are in place, to protect workers from H2S releases. 

Other emissions of pollutants into the atmosphere from catastrophic events are not projected to have 

significant impacts on onshore air quality because of the prevailing atmospheric conditions, emissions 

height, emission rates, and the distance of these emissions from the coastline.

Overall, since loss of well-control events, blowouts, and fires are rare events and of short duration, 

potential impacts to air quality are not expected to be significant except in the rare case of a catastrophic 

event. To date, air monitoring conducted following the Macondo well blowout and spill, has not found 

any pollutants at levels expected to cause long-term harm (USEPA, 2010b). 

A.3.1.2. Water Quality

Phase 1—Initial Event

Offshore Water Quality

During the initial phase of a catastrophic blowout, water quality impacts include the disturbance of 

sediments and the release and suspension of oil and natural gas (primarily methane) into the water 

column. These potential impacts are discussed below. As this chapter deals with the immediate effects of 

a blowout that would be located at least 3 nmi (3.5 mi; 5.6 km) from shore, it is assumed that there would

be no impacts on coastal water quality during this initial stage.
A-20 Western Planning Area Lease Sale 248 Supplemental EIS

Disturbance of Sediments

A catastrophic blowout below the seafloor, outside the wellbore (Table A-1) has the potential to 

resuspend sediments and disperse potentially large quantities of bottom sediments. Some sediment could 

travel several kilometers, depending on particle size and subsea current patterns. In the deep Gulf of 

Mexico, surficial sediments are mostly composed of silt and clay, and, if resuspended, could stay in the 

water column for several hours to days. Bottom current measurements in the deep Gulf of Mexico were 

synthesized as part of the MMS Deepwater Reanalysis study and have been measured to reach 

90 centimeters/second (cm/sec) (35.4 inches/second [in/sec]) with mean flows of 0.4-21 cm/sec 

(0.2-8.3 in/sec) (Nowlin et al., 2001). At these mean flow rates, resuspended sediment could be 

transported 0.3-18 km per day (0.2-11 mi per day). 

Sediment resuspension can lead to a temporary change in the oxidation-reduction chemistry in the 

water column, including a localized and temporal release of any formally sorbed metals, as well as 

nutrient recycling (Caetano et al., 2003; Fanning et al., 1982). Sediments also have the potential to 

become contaminated with oil components.

A subsea release also has the potential to destabilize the sediments and create slumping or larger scale 

sediment movements along depth gradients. These types of events would have the potential to move 

and/or damage any infrastructure in the affected area.

Release and Suspension of Oil into the Water Column 

A subsea release of hydrocarbons at a high flow rate has the potential to disperse and suspend plumes 

of oil droplets (chemically dispersed or otherwise) within the water column and to induce large patches of 

sheen and oil on the surface. These dispersed hydrocarbons may adsorb onto marine detritus (marine 

snow), suspended sediments, or may be mixed with drilling mud and deposited near the source. 

Mitigation efforts such as burning may introduce hydrocarbon byproducts into the marine environment, 

which would be distributed by surface currents. The acute and chronic sublethal effects of these dilute 

suspended “plumes” are not well understood and require future research efforts.

As a result of the Macondo well blowout and spill, a subsurface oil and gas plume was discovered in 

deep waters between ~1,100 and 1,300 m (3,609 and 4,265 ft) (e.g., Diercks et al., 2010) in addition to the 

surface slick. Measurable amounts of hydrocarbons (dispersed or otherwise) were detected in the 

subsurface plumes and on the seafloor in the vicinity of the release (e.g., Diercks et al., 2010; OSAT, 

2010). In the Macondo well blowout and spill subsurface plume, half-lives were estimated for petroleum 

hydrocarbons and n-alkanes on the order of 1 month and several days, respectively, indicating the impacts 

of various weathering processes (Reddy et al., 2011 and references therein). After the Ixtoc I well 

blowout and spill in 1979, which was located 50 mi (80 km) offshore in the Bay of Campeche, Mexico, 

some subsurface oil was also observed dispersed within the water column (Boehm and Fiest, 1982); 

however, the scientific investigations were limited (Reible, 2010). The water quality of offshore waters 

would be affected by the dissolved components and oil droplets that are small enough that they do not rise 

to the surface or are mixed down by surface turbulence. In the case of subsurface oil plumes, it is 

important to remember that these plumes would be affected by subsurface currents, dilution, and natural 

physical, chemical, and biological degradation processes including weathering.

Large quantities of oil put into offshore water may alter the chemistry of the sea with unforeseeable 

results. The properties and persistence of oil, including oil in the Gulf of Mexico, are further discussed in 

Chapter A.2.2.4. The VOCs, including benzene, toluene, ethylbenzene, and xylenes (also referred to as 

BTEX), are highly soluble and can have acutely toxic effects; however, VOCs are light-weight oil 

components and tend to evaporate rather than persist in the environment (Michel, 1992). Middle-weight 

organic components tend to pose the greatest risk in the environment because they are more persistent in 

the environment, are more bioavailable, and include PAHs, which have high toxicities (Michel, 1992). 

To determine the overall toxicity of PAHs in water or sediment, the contributions of every individual 

PAH compound in the petroleum mixture must be included (USEPA, 2011). This approach was used

during the Macondo well blowout, spill and response in determining the potential risk of PAHs in both 

water and sediment to humans or animals in the environment (OSAT, 2010). Heavier components of 

crude oil tend to pose less risk of toxicity because they are not very soluble in water and therefore are less 

bioavailable.
Catastrophic Spill Event Analysis A-21

The oil that entered the Gulf of Mexico from the Macondo well blowout and spill was a South 

Louisiana sweet crude oil (i.e., low in sulfur) (USDOC, NOAA, 2010b). This oil is less toxic than other 

crude oils in general because this oil is lower in PAHs than many other crude oils. Studies indicate that 

the oil contained approximately 3.9 percent PAHs by weight, which results in an estimated release of 

2.1 x 1010 grams of PAHs (Reddy et al., 2011; Reddy, official communication, 2012). The oil was also 

fairly high in alkanes (organic compounds containing only carbon and hydrogen and single bonds, 

sometimes called paraffin or aliphatic compounds) (USDOC, NOAA, 2010b). Because alkanes are 

simple hydrocarbons, these oils are likely to undergo biodegradation more easily (USDOC, NOAA, 

2010b). 

Release of Natural Gas (Methane) into the Water Column 

A catastrophic blowout could release natural gas into the water column; the amount of gas released is 

dependent upon the water depth, the natural gas content of the formation being drilled, and its pressure. 

Methane is the primary component of natural gas. Methane may stay in the marine environment for long 

periods of time (Patin, 1999, page 237), as methane is highly soluble in seawater at the high pressures and 

cold temperatures found in deepwater environments (NRC, 2003, page 108). However, methane 

diffusing through the water column would likely be oxidized in the aerobic zone and would rarely reach 

the air-water interface (Mechalas, 1974, page 23). In addition to methane, natural gas contains smaller 

percentages of other gases such as ethane, propane, and to a much lesser degree H2S (NaturalGas.org, 

2012), which can be toxic in the environment. The majority of natural gas components including methane 

are carbon sources, and their introduction into the marine environment could result in reducing the 

dissolved oxygen levels because of microbial degradation potentially creating hypoxic or “dead” zones. 

Unfortunately, little is known about methane toxicity in the marine environment, but there is concern as to 

how methane in the water column might affect fish. Further discussion of natural gas released during the 

Macondo well blowout and spill is given in Chapter A.2.2.5.

Phase 2—Offshore Spill

Offshore Water Quality

The water offshore of the Gulf’s coasts can be divided into two regions: the continental shelf and 

slope (<1,000 ft; 305 m) and deep water (>1,000 ft; 305 m). Waters on the continental shelf and slope are 

heavily influenced by the Mississippi and Atchafalaya Rivers, the primary sources of freshwater, 

sediment, nutrients, and pollutants from a huge drainage basin encompassing 55 percent of the continental 

U.S. (Murray, 1998). Lower salinities are characteristic nearshore where freshwater from the rivers mixes 

with Gulf waters. The presence or extent of a nepheloid layer, a body of suspended sediment at the sea 

bottom (Kennett, 1982, page 524), affects water quality on the shelf and slope. Deep waters east of the 

Mississippi River are affected by the Loop Current and associated warm-core (anti-cyclonic) eddies, 

which flush the area with clear, low-nutrient water (Muller-Karger et al., 2001) (Figure A-2). However, 

cold-core cyclonic eddies (counter-clockwise rotating) also form at the edge of the Loop Current and are 

associated with upwelling and nutrient-rich, high-productivity waters, although the extent of this flushing 

can vary seasonally.

While response efforts would decrease the fraction of oil remaining in Gulf waters, significant 

amounts of oil would remain. Natural processes will physically, chemically, and biologically aid the 

degradation of oil (NRC, 2003). The physical processes involved include evaporation, emulsification, 

and dissolution, while the primary chemical and biological degradation processes include photo-oxidation 

and biodegradation (i.e., microbial oxidation). Water quality would not only be impacted by the oil, gas, 

and their respective components, but also to some degree, from cleanup and mitigation efforts, such as 

from increased vessel traffic and the addition of dispersants and methanol to the marine environment. 

In the case of a catastrophic subsea blowout in deep water, it is assumed that large quantities of 

subsea dispersants would be used. The positive effect of using dispersants is that the oil, once dispersed, 

may be more available to be degraded (however, we note that contrary findings for beached oil were 

presented by Hamdan and Fulmer, 2011). The negative effect is that the oil, once dispersed, is also more 

bioavailable to have toxic effects to microorganisms as well. The toxicity of dispersed oil in the 

environment would depend on many factors, including the effectiveness of the dispersion, temperature, 

salinity, degree of weathering, type of dispersant, and degree of light penetration in the water column 
A-22 Western Planning Area Lease Sale 248 Supplemental EIS

(NRC, 2005). The toxicity of dispersed oil is primarily because of the toxic components of the oil itself 

(Australian Maritime Safety Authority, 2010). 

As a result of the use of dispersants, it would be more likely for clouds or plumes of dispersed oil to 

occur near the blowout site as was seen during the Macondo well blowout and spill. Dissolved oxygen 

levels are a concern with any release of a carbon source, such as oil and natural gas, and became a 

particular concern during the Macondo well blowout and spill since dispersants were used in deep waters 

for the first time. In areas where plumes of dispersed oil were previously found, dissolved oxygen levels 

decreased by about 20 percent from long-term average values in the GOM of ~6.9 milligrams/liter (spring 

climatological mean at 1,500-m [4,921 -ft] depth); however, scientists reported that these levels stabilized 

and were not low enough to be considered hypoxic (Joint Analysis Group, 2010; USDOC, NOAA, 

2010c). The drop in oxygen, which did not continue over time, has been attributed to microbial 

degradation of the oil.

Phase 3—Onshore Contact

Coastal Water Quality 

Water quality governs the suitability of waters for plant, animal, and human use. Water quality is 

important in the bays, estuaries, and nearshore coastal waters of the Gulf because these waters provide 

feeding, breeding, and/or nursery habitat for many invertebrates and fishes, as well as sea turtles, birds, 

and marine mammals. A catastrophic spill would significantly impact coastal water quality in the Gulf of 

Mexico. Water quality prior to the Macondo well blowout and spill was rated as fair while sediment 

quality was rated as poor (USEPA, 2008). In addition, the coastal habitat index, a rating of wetlands 

habitat loss, was also rated as poor. Both the sediment quality and the coastal habitat index affect water 

quality. 

Though response efforts would decrease the amount of oil remaining in Gulf waters and reduce the 

amount of oil contacting the coastline, significant amounts of oil would remain. Coastal water quality 

would be impacted not only by the oil, gas, and their respective components but also to some degree from 

cleanup and mitigation efforts. Increased vessel traffic, hydromodification, and the addition of 

dispersants and methanol in an effort to contain, mitigate, or clean up the oil may also tax the 

environment. 

The use of dispersants as a response tool involves a tradeoff. The purpose of chemical dispersants is 

to facilitate the movement of oil into the water column in order to encourage weathering and biological 

breakdown of the oil (i.e., biodegradation) (NRC, 2005; Australian Maritime Safety Authority, 2010). 

Thus, the tradeoff is generally considered to be oiling of the shoreline and surface of the water versus the 

water column and benthic resources (NRC, 2005). If the oil moves into the water column and is not on 

the surface of the water, it is less likely to reach sensitive shore areas (USEPA, 2010a). Since sea birds 

are often on the surface of the water or in shore areas, dispersants are also considered to be very effective 

in reducing the exposure of sea birds to oil (Australian Maritime Safety Authority, 2010). In addition to 

dispersion being enhanced by artificial processes, oil may also be dispersed from natural processes 

including both (bio)chemical and physical processes. For instance, microbial metabolism of crude oil 

results in the dispersion of oil (Bartha and Atlas, 1983), and conditions at the source of the oil/gas leak 

(e.g., orifice size and shape) may cause physical dispersion of the oil. Dispersion has both positive and 

negative effects. The positive effect is that the oil, once dispersed, is more available to be degraded. The 

negative effect is that the oil, once dispersed, is also more bioavailable to have toxic effects to 

microorganisms as well. For example, a recent study using mesocosm experiments suggested that 

dispersed oil could disrupt coastal microbial foodwebs in the northern Gulf of Mexico, reducing the flow 

of carbon to higher trophic levels (Ortmann et al., 2012). The toxicity of dispersed oil in the environment 

will depend on many factors, including the effectiveness of the dispersion, temperature, salinity, the 

degree of weathering, type of dispersant, and the degree of light penetration in the water column (NRC, 

2005). The toxicity of dispersed oil is primarily because of the toxic components of the oil itself 

(Australian Maritime Safety Authority, 2010). 

Oxygen and nutrient concentrations in coastal waters vary seasonally. The zone of hypoxia (depleted 

oxygen) on the Louisiana-Texas shelf occurs seasonally and is affected by the timing of freshwater 

discharges from the Mississippi and Atchafalaya Rivers. The hypoxic conditions continue until local 

wind-driven circulation mixes the water again. The 2010 hypoxic zone could not be linked to the 
Catastrophic Spill Event Analysis A-23

Macondo well blowout and spill in either a positive or a negative manner (Louisiana Universities Marine 

Consortium, 2010). Nutrients from the Mississippi River nourished phytoplankton and contributed to the 

formation of the hypoxic zone.

Phase 4—Post-Spill, Long-Term Recovery and Response 

The leading source of contaminants that impairs coastal water quality in the Gulf of Mexico is urban 

runoff. It can include suspended solids, heavy metals, pesticides, oil, grease, and nutrients (such as from 

lawn fertilizer). Urban runoff increases with population growth, and the Gulf Coast region has 

experienced a 109 percent population growth since 1970, with an additional expected 15 percent increase 

expected by 2020 (USDOC, NOAA, 2011b). Other pollutant source categories include (1) agricultural 

runoff, (2) municipal point sources, (3) industrial sources, (4) hydromodification (e.g., dredging), and 

(5) vessel sources (e.g., shipping, fishing, and recreational boating). The NRC (2003, Table I-4, 

page 237) estimated that, on average, approximately 26,324 bbl of oil per year entered Gulf waters from 

petrochemical and oil refinery industries in Louisiana and Texas. The Mississippi River introduced 

approximately 3,680,938 bbl per year (NRC, 2003, Table I-9, page 242) into the waters of the Gulf. 

Hydrocarbons also enter the Gulf of Mexico through natural seeps in the Gulf at a rate of approximately 

980,392 bbl per year (a range of approximately 560,224-1,400,560 bbl per year) (NRC, 2003, page 191). 

Produced water (formation water) is, by volume, the largest waste stream from the oil and gas industry 

that enters Gulf waters (e.g., Table A-3). The NRC has estimated the quantity of oil in produced water 

entering the Gulf per year to be 473,000 bbl (NRC, 2003, page 200, Table D-8).1

 These sources total 

about 5.5 MMbbl of oil per year that routinely enters Gulf of Mexico waters. In comparison, a 

catastrophic spill of 30,000-60,000 bbl per day for 90-120 days would spill a total of 2.7-7.2 MMbbl of 

oil. When added to the other sources of oil listed above, this would result in a 48- to 129-percent increase 

in the volume of oil entering the water during the year of the spill. In addition, the oil from a catastrophic 

spill will be much more concentrated in some locations than the large number of other activities that 

release oil into the Gulf of Mexico. Chapter A.2.2.4 discusses the properties and persistence of oil in the 

environment. 

Overall Summary and Conclusion (Phases 1-4) 

During Phase 1 of the catastrophic blowout scenario, impacts are not expected to coastal water 

quality. Instead, the initial impacts will include degradation of offshore water quality, disturbance and 

degradation of sediments, and the release and suspension of oil and natural gas into the water column, 

including the possible formation of plumes. Fine sediments could be transported away from the spill site.

As the spill continues during Phase 2, response efforts and natural degradation processes would 

decrease the amount of oil in the Gulf, but significant amounts of oil would remain to impact water and 

sediment quality. Water and sediment quality would not only be impacted by the oil, gas, and their 

respective components but also to some degree from cleanup and mitigation efforts. The use of 

dispersants as a response tool may make the oil more available to degradation, but it can also make the oil 

more bioavailable to have toxic effects on microorganisms as well. Furthermore, dispersed oil is more 

likely to form a plume.

Onshore contact is made during Phase 3, so coastal sediment and water quality will be significantly 

impacted during this phase despite response efforts. Response efforts may even tax the coast to some 

degree. Natural and chemical dispersion may reduce the contact of oil with the shoreline but result in 

more oil in the water column and greater bioavailability of the dispersed oil.

The long-term recovery (Phase 4) of the water and sediment quality of the Gulf will depend on the 

properties and persistence of the oil as noted in Chapter A.2.2.4. Though the spill will increase the 

amount of oil entering the Gulf of Mexico, oil regularly enters the Gulf through sources such as oil 

refineries, the Mississippi River, produced water, and natural seeps. However, oil from a spill will be 

more concentrated than the oil input from these other sources. 

 1 These numbers were generated from converting the units reported in the noted reference and do not imply any 

level of significance.
A-24 Western Planning Area Lease Sale 248 Supplemental EIS

A.3.1.3. Coastal Barrier Beaches and Associated Dunes

Phase 1—Initial Event

There would likely be no adverse impacts to coastal barrier beaches and associated dunes as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 1 of a 

catastrophic spill event because these resources would not be contacted until the oil reached the shoreline.

Phase 2—Offshore Spill

There would likely be no adverse impacts to coastal barrier beaches and associated dunes as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 2 of a 

catastrophic spill event because these resources would not be contacted until the oil reached the shoreline.

Phase 3—Onshore Contact

Barrier islands make up more than two-thirds of the northern Gulf of Mexico shore. Each of the 

barrier islands is either high profile or low profile, depending on the elevations and morphology of the 

island (Morton et al., 2004). The distinguishing characteristics of the high- and low-profile barriers relate 

to the width of the islands along with the continuity of the frontal dunes. Low-profile barriers are narrow 

with discontinuous frontal dunes easily overtopped by storm surge, which makes the island susceptible to 

over wash and erosion. This over wash can create channels to bring sand onto the island or into lagoons 

formed on these islands. High-profile barrier islands are generally wider than the low-profile islands and 

have continuous, vegetated, frontal dunes with elevations high enough to prevent over wash from major 

storm surge and, therefore, are less susceptible to erosion. The sand stored in these high-profile dunes 

allows the island to withstand prolonged erosion and therefore prevents breaching, which could result in 

damaging the island core.

The effects from oil spills depend on the geographic location, volume, and rate of the spill; type of 

oil; oil-slick characteristics; oceanic conditions and season at the time of the spill; and response and 

cleanup efforts. The effects could include changes in plant species diversity that could result in changes 

in forage areas for species using microfauna as a food base (Teal and Howarth, 1984). Further detail on 

this catastrophic OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental EIS.

As a result of a catastrophic spill, many of the barrier islands and beaches would receive varying 

degrees of oiling. Oil disposal on sand and vegetated sand dunes was shown in experiments by Webb 

(1988) to have little deleterious effects on the existing vegetation or on the recolonization of the oiled 

sands by plants. However, other studies have documented toxic effects of oil on barrier beach vegetation 

(Ko and Day, 2004). The depth of oiling would be variable, based on the wave environment and 

sediment source at a particular beach head. Layering of oil and sand could occur if it was not cleaned 

before another tidal cycle. However, most areas of oiling are expected to be light, and sand removal 

during cleanup activities should be minimized. The severity of oiling dictates the appropriate cleanup 

method to be utilized (refer to Table A-4).

In areas designated as natural wilderness areas (e.g., Breton National Wildlife Refuge and Gulf 

Islands National Seashore), land managers may require little to no disruption of the natural system. In 

these environments, it is preferred to let the oil degrade naturally without aggressive and intrusive cleanup 

procedures. Manual rather than mechanized removal techniques would be used in these areas and only if

heavy oiling has occurred. Thus, these areas may not be treated as thoroughly as other shorelines. Oil 

would remain in place longer, weathering gradually while continuing to contaminate habitat, though 

mechanical disturbance would be minimized. 

Once oil has reached the beaches and barrier islands and becomes buried or sequestered, it becomes 

difficult to treat. During wave events when the islands and beaches erode, the oil can become 

remobilized and transported. Thus, the fate of oil is not as simple as either reaching land, becoming 

sequestered, or being treated; but, it must be considered in terms of a continuing process of sequestration, 

remobilization, and transport.

For spilled oil to move onto beaches or across dunes, strong southerly winds must persist for an 

extended time prior to or immediately after the spill to elevate water levels. Strong winds, however, 

could reduce the impact severity at a landfall site by accelerating the processes of oil-slick dispersal, spill 

spreading, and oil weathering.
Catastrophic Spill Event Analysis A-25

Bik et al. (2012) found that, despite the disappearance of visible surface oil on heavily oiled Gulf 

beaches impacted by the Macondo well blowout and spill, microbial communities showed significant 

changes in community structure, with a decrease in diversity and a shift toward dominance by fungal taxa, 

particularly known hydrocarbon-degrading genera. Likewise, nematode communities showed decreased 

diversity and increased dominance by predatory and scavenger taxa alongside an increased abundance of 

juveniles.

Due to the distance of beaches from deepwater blowouts and the combination of weathering and 

dispersant treatment of the oil offshore, the toxicity and quantity of the oil reaching shore should be 

greatly reduced, thereby minimizing the chances of irreversible damage to the impacted areas. A blowout 

in shallower waters near shore may have equal or greater impacts because of a shorter period of 

weathering and dispersion prior to shoreline contact, even though a smaller volume of spilled oil would 

be expected.

Vessel traffic in close proximity to barrier islands has been shown to move considerably more bottom 

sediment than tidal currents, thus increasing coastal and barrier island erosion rates. If staging areas for 

cleanup of a catastrophic spill are in close proximity to these islands, recovery time of the barrier islands 

could be greatly extended because of the large number of response vessels.

Phase 4—Post-Spill, Long-Term Recovery and Response 

Oil or its components that remain in the sand after cleanup may be (1) released periodically when 

storms and high tides resuspend or flush beach sediments, (2) decomposed by biological activity, or 

(3) volatilized and dispersed. While it is assumed that the majority of spilled oil would be dissipated 

offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil has the 

potential to persist in the environment long after a spill event. For example on sandy beaches, oil can sink 

deep into the sediments. As stranded oil weathers, some oil may become buried through natural beach 

processes and appear as surface residual balls (SRBs; <10 cm [4 in]) or as surface residual patties (SRPs; 

10 cm to 1 m [4 in to 3 ft]) (Table A-4). Such balls continue to provide a source of contamination with 

accompanying toxic effects.

The cleanup impacts of a catastrophic spill could result in short-term (up to 2 years) adjustments in 

beach profiles and configurations as a result of sand removal and disturbance during cleanup operations. 

Some oil contact to lower areas of sand dunes is expected. This contact 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 (Ko and Day, 2004).

The protection once afforded to inland marshes by coastal barrier beaches has been greatly reduced 

because of decreased elevations and the continued effect of subsidence, sea-level rise, and saltwater 

intrusion. A catastrophic spill has the potential to contribute to this reduction through increased erosion 

as a result of plant dieback and cleanup efforts.

Overall Summary and Conclusion (Phases 1-4) 

As a result of a catastrophic spill, many of the barrier islands and beaches would receive varying 

degrees of oiling. However, most areas of oiling are expected to be lightly oiled, and sand removal 

during cleanup activities should be minimal. 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. 

A.3.1.4. Wetlands

Phase 1—Initial Event

There would likely be no adverse impacts to wetlands as a result of the events and the potential 

impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event because these 

resources would not be contacted until the oil reached the shoreline.
A-26 Western Planning Area Lease Sale 248 Supplemental EIS

Phase 2—Offshore Spill

There would likely be no adverse impacts to wetlands as a result of the events and the potential 

impact-producing factors that could occur throughout Phase 2 of a catastrophic spill event because these 

resources would not be contacted until the oil reached the shoreline.

Phase 3—Onshore Contact

Coastal wetland habitats in the Gulf of Mexico occur as bands around waterways; broad expanses of 

saline, brackish, and freshwater marshes; mud and sand flats; and forested wetlands of cypress-tupelo 

swamps and bottomland hardwoods. Offshore oil spills would have a low probability of contacting and 

damaging any wetlands along the Gulf Coast, except in the case of a catastrophic event. This is because 

of the distance of the spill to the coast, the likely weathered condition of oil (through evaporation, 

dilution, and biodegradation) should it reach the coast, and because wetlands are generally protected by 

barrier islands, peninsulas, sand spits, and offshore currents. 

While a catastrophic spill from a shallow-water blowout is expected to be lower in volume than a 

deepwater blowout, a potential shallow-water site could be closer to shore, allowing less time for oil to be 

weathered, dispersed, and recovered before it impacted coastal resources. A spill from a catastrophic 

blowout could oil a few to several hundred acres of wetlands depending on the depth of inland penetration 

(Burdeau and Collins, 2010). This would vary from moderate to heavy oiling. One study of the impacts 

of the Deepwater Horizon explosion, oil spill, and response to salt marshes in Louisiana estimated the 

area affected to be between 350 and 400 km2

 (135 and 154 mi2) (Mishra et al., 2012). Further detail on 

the catastrophic OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental EIS.

The NOAA Environmental Sensitivity Index (ESI) ranks shorelines according to their sensitivity to 

oil, the natural persistence of oil, and the expected ease of cleanup after an oil spill. These factors cause 

oil to persist in coastal and estuarine areas (USDOI, MMS, 2010). According to the ESI, the most 

sensitive shoreline types (i.e., sheltered tidal flats, vegetated low banks, salt/brackish-water marshes, 

freshwater marshes/swamps, and scrub-shrub wetlands) tend to accumulate oil and are difficult to clean, 

thus causing oil to persist in these coastal and estuarine areas (USDOI, MMS, 2010).

In the case of catastrophic spills in the GOM, preemptive oil-response strategies would be initiated 

and include the deployment of oil booms, skimmer ships, and barge barriers to protect the beaches and 

adjacent wetlands. Boom deployment must also include plans for monitoring and maintaining the 

protective boom systems to assure that these systems are installed and functioning properly and that they 

are not damaging the wetlands they are trying to protect. In most cases, the beach face would take the 

most oil; however, in areas where the marsh is immediately adjacent to the beach face or embayments, or 

in the case of small to severe storms, marshes would be oiled. For example, in Alabama, Mississippi, and 

Florida, severe weather could push oil into the tidal pools and back beach areas that support tidal marsh 

vegetation.

The primary factors that affect vegetation responses to oil are toxicity of the oil and extent of plant 

coverage, amount of contact with and penetration of the soil, plant species affected, oiling frequency, 

season, and cleanup activities (Mendelssohn et al., 2012). Previous studies of other large spills have 

shown that, when oil has a short residence time in the marsh and it is not incorporated into the sediments, 

the marsh vegetation has a high probability of survival, even though aboveground die-off of marsh 

vegetation may occur (Lin et al., 2002). However, if re-oiling occurs after the new shoots from an initial 

oiling are produced, such that the new shoots are killed, then the marsh plants may not have enough 

stored energy to produce a second round of new shoots. Other studies noted the utilization of dispersants 

in the proper dosages results in a reduction in marsh damage from oiling (Lin and Mendelssohn, 2009). 

The works of several investigators (Webb et al., 1981 and 1985; Alexander and Webb, 1983 and 1987; 

Lytle, 1975; Delaune et al., 1979; Fischel et al., 1989) evaluated the effects of potential spills to area 

wetlands. For wetlands along the central Louisiana coast, the critical oil concentration is assumed to be 

0.025 gallons per ft2 (1.0 liter per m2

) of marsh. Concentrations less than this may cause diebacks for one 

growing season or less, depending upon the concentration and the season during which contact occurs. 

The duration and magnitude of a spill resulting from a catastrophic blowout could result in concentrations 

above this critical level and would result in longer term effects to wetland vegetation, including some 

plant mortality and loss of land. 
Catastrophic Spill Event Analysis A-27

Due to the distance of deep water from shore, the possibility of a spill from a deepwater blowout 

reaching coastal wetlands with the toxicity to significantly impact the coastal wetlands is low because of 

the response procedures implemented during a catastrophic spill. (It is assumed that oil would reach 

shore within 2-4 weeks.) Therefore, a spill from a shallow-water blowout is more likely to contribute to 

wetland damage. However, for the few deepwater areas that are located closer to shore, such as in the 

Mississippi Canyon Area, the amount of time before shoreline contact could occur could be estimated to 

be the same as the estimate given for the shallow-water scenario, i.e., 1-3 weeks.

Offshore skimming, burning, and dispersal treatments for the oil near the spill site would result in 

capture, detoxification, and dilution of the majority of oil spilled. The utilization of nearshore booming 

protection for beaches and wetlands could also help to reduce oiling of these resources, if done correctly. 

Booms deployed adjacent to marsh shorelines can be lifted by wave action onto marsh vegetation, 

resulting in plant mortality under the displaced booms. The activity of oil cleanup can result in additional 

impacts on wetlands if not done properly. During the Deepwater Horizon explosion, oil spill, and 

response, aggressive onshore and marsh cleanup methods (such as the removal by mechanized equipment, 

in-situ burning, etc.) were not extensively utilized. The severity of oiling is the main factor that dictates 

the appropriate marsh cleanup method to be utilized (refer to Table A-4).

Phase 4—Post-Spill, Long-Term Recovery and Response 

Wetlands serve a number of important ecological functions. For example, Louisiana’s coastal 

wetlands support more than two-thirds of the wintering waterfowl population of the Mississippi Flyway 

(State of Louisiana, Dept. of Wildlife and Fisheries, 2012). Therefore, loss of wetlands would also 

impact a significant portion of the waterfowl population. Another important ecological function of 

wetlands is their use as a nursery for estuarine-dependent species of fish and shellfish. Wetland loss 

would reduce the available nursery habitat. 

The duration and magnitude of a spill resulting from a catastrophic blowout could result in high 

concentrations of oil that would result in long-term effects to wetland vegetation, including some plant 

mortality and loss of land. Silliman et al. (2012) found that after the Macondo well blowout and spill, oil 

coverage of Louisiana salt marshes was primarily concentrated on their seaward edges. Oil-driven plant 

death on the edges of these marshes more than doubled the rates of shoreline erosion, further driving 

marsh platform loss that is likely to be permanent. Eighteen months after the Macondo well blowout and 

spill, in previously oiled, noneroded areas, marsh grasses had largely recovered, and the elevated 

shoreline retreat rates observed at oiled sites had decreased to levels at reference marsh sites. Studies of 

impacted wetlands have demonstrated that wetlands can recover from the impacts of oil spills, but the 

recovery process varies from extremely slow in mangrove swamps (Burns et al., 1993 and 1994) to 

relatively rapid in grass-dominated marshes subject to in-situ burning of oil (Baustian et al., 2010). 

Land loss caused by the oiling of wetlands would add to continuing impacts of other factors, such as 

hurricanes, subsidence, saltwater intrusion, and sea-level rise. The wetlands along the Gulf Coast have 

already been severely damaged by the 2005 and 2008 hurricane seasons, leaving the mainland less 

protected. It was estimated in 2000 that coastal Louisiana would continue to lose land at a rate of 

approximately 2,672 hectares/year (10 mi2

/year) over the next 50 years. Further, it was estimated that an 

additional net loss of 132,794 hectares (512 mi2

) may occur by 2050, which is almost 10 percent of 

Louisiana’s remaining coastal wetlands (Barras et al., 2003). Barras (2006) indicated an additional 

562 km2 (217 mi2

) of land lost during the 2005 hurricane season. A catastrophic spill occurring nearshore 

would contribute further to this landloss. Following Hurricanes Katrina and Rita, another series of 

hurricanes (Gustav and Ike) made landfall along the Louisiana and Texas coasts in September 2008. 

Hurricane Gustav made landfall as a Category 2 storm near Cocodrie, Louisiana, pushing large surges of 

saline water into the fresh marshes and coastal swamps of Louisiana from Grand Isle westward. While 

Hurricane Gustav did not impact the quantity of wetlands that Hurricanes Katrina and Rita impacted, it 

did have a severe and continuing effect on the coastal barrier islands and the wetlands associated with 

backshore (back of the island) and foreshore (front of the island). While Hurricane Gustav affected the 

eastern portion of the Louisiana coast closer to Grand Isle and Houma, Hurricane Ike concentrated on 

Louisiana’s western coast. The Texas coast received the brunt of Hurricane Ike where it made landfall 

slightly east of Galveston. The storm surge heavily eroded the dune systems and significantly lowered 

the beach elevations along the eastern portion of the Texas coast near Galveston and the Bolivar 

Peninsula. The erosion and wash-over associated with Hurricane Ike’s tidal surge breeched beach ridges 
A-28 Western Planning Area Lease Sale 248 Supplemental EIS

and opened the inland freshwater ponds and their associated wetlands to the sea. As a result of the four 

successive storms, the Louisiana and Texas coasts have lost protective elevations, barrier islands, and 

wetlands, and they now have the potential for transitioning to a less productive salt-marsh system in areas 

where fresh-marsh systems once existed. In addition, the loss of these protective elevations has increased 

the vulnerability of coastal wetlands to catastrophic oil-spill events.

A poorly executed oil cleanup can result in additional impacts. Aggressive onshore and marsh 

cleanup methods (such as removal by mechanized equipment, in-situ burning, marsh cutting, and foot 

entry into the marsh for manual removal) probably would not be initiated until the oil spill has been 

stopped. Depending on the marsh remediation methods used, further impacts to the wetlands may occur 

from cleanup activities. Boat traffic in marsh areas from the thousands of response vessels associated 

with a catastrophic spill would produce an incremental increase in erosion rates, sediment resuspension, 

and turbidity (i.e., an adverse but not significant impact to coastal wetland and seagrass habitats).

Overall Summary and Conclusion (Phases 1-4) 

A spill from a catastrophic blowout could impact a few to several hundred square kilometers of 

wetlands depending on the depth of inland penetration (Burdeau and Collins, 2010; Mishra et al., 2012). 

This would vary from moderate to heavy oiling. Impacts to wetlands would vary according to the 

severity of the oiling. The duration and magnitude of the spill could result in severe oiling of wetlands in 

some areas, causing long-term effects to wetland vegetation, including some plant mortality and loss of 

land. 

A.3.1.5. Seagrass Communities

Phase 1—Initial Event

There would likely be no adverse impacts to submerged vegetation as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event 

because of the likely distance from the spill event to the nearest submerged vegetation beds.

Phase 2—Offshore Spill

There would likely be no adverse impacts to submerged vegetation as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 2 of a catastrophic spill because of 

the likely distance from the spill event to the nearest submerged vegetation beds.

Phase 3—Onshore Contact

According to the most recent and comprehensive data available, approximately 500,000 hectares 

(1.25 million acres; 505,857 hectares) of submerged seagrass beds are estimated to exist in exposed, 

shallow coastal waters and embayments of the northern Gulf of Mexico, and over 80 percent of this area 

is in Florida Bay and Florida coastal waters (calculated from Handley et al., 2007). Submerged 

vegetation distribution and composition depend on an interrelationship among a number of environmental 

factors that include water temperature, depth, turbidity, salinity, turbulence, and substrate suitability 

(Kemp, 1989; Onuf, 1996; Short et al., 2001). Marine seagrass beds generally occur in shallow, relatively 

clear, protected waters with predominantly sand bottoms (Short et al., 2001). Freshwater submerged 

aquatic vegetation (SAV) species occur in the low-salinity waters of coastal estuaries (Castellanos and 

Rozas, 2001). Seagrasses and freshwater SAVs provide important nursery and permanent habitat for 

sunfish, killifish, immature shrimp, crabs, drum, trout, flounder, and several other nekton species, and 

they provide a food source for species of wintering waterfowl and megaherbivores (Rozas and Odum, 

1988; Rooker et al., 1998; Castellanos and Rozas, 2001; Heck et al., 2003; Orth et al., 2006). Further 

detail on this catastrophic OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental 

EIS.

If oil comes into areas with submerged beds, increased water turbulence from waves, storms, or 

vessel traffic could break apart the surface oil sheen and disperse some oil into the water column or mix 

oil with sediments that would settle and coat an entire plant. Coating of the plat from the oil and sediment 

mixture would cause reduced chlorophyll production and could lead to a decrease in vegetation (Teal and 
Catastrophic Spill Event Analysis A-29

Howarth, 1984; Burns et al., 1994; Erftemeijer and Lewis, 2006). This coating situation also happens 

when oil is treated with dispersants because the dispersants break down the oil and it sinks into the water 

column (Thorhaug et al., 1986; Runcie et al., 2004). However, as reviewed in Runcie et al. (2004), oil 

mixed with dispersants has shown an array of effects on seagrass depending on the species and dispersant 

used. With a greater distance from shore, there is a greater chance of the oil being weathered by natural 

and mechanical processes by the time it reaches the nearshore habitat.

Depending on the species and environmental factors (e.g., temperature and wave action), seagrasses 

may exhibit minimal impacts, such as localized loss of pigmentation, from a spill; however, communities 

residing within the beds could accrue greater negative outcomes (den Hartog and Jacobs, 1980; Jackson 

et al., 1989; Kenworthy et al., 1993; Taylor et al., 2006). Community effects could range from either 

direct mortality due to smothering or indirect mortality from loss of food sources and habitat to a decrease 

in ecological performance of the entire system depending on the severity and duration of the spill event 

(Zieman et al., 1984). 

Prevention and cleanup efforts could also affect the health of submerged vegetation communities 

(Zieman et al., 1984). Many physical prevention methods such as booms, barrier berms, and diversions 

can alter hydrology, specifically changing salinity and water clarity. These changes would harm certain 

species of submerged vegetation because they are tolerant to specific salinities and light levels (Zieman 

et al., 1984; Kenworthy and Fonseca, 1996; Frazer et al., 2006). With cleanup, there is increased boat and 

human traffic in these sensitive areas that generally are protected from this degree of human disturbance 

prior to the response. Increased vessel traffic would lead to elevated water turbidity and increased 

propeller scarring. While the elevated levels of water turbidity from vessels would be short-term and the 

possible damages from propellers could be longer, both events would be localized during the prevention 

and cleanup efforts (Zieman, 1976; Dawes et al., 1997). 

Phase 4—Post-Spill, Long-Term Recovery and Response 

According to the most recent and comprehensive data available, approximately 500,000 hectares 

(1.25 million acres; 505,857 hectares) of submerged seagrass beds are estimated to exist in exposed, 

shallow coastal waters and embayments of the northern Gulf of Mexico, and over 80 percent of this area 

is in Florida Bay and Florida coastal waters (calculated from Handley et al., 2007). Submerged 

vegetation distribution and composition depend on an interrelationship among a number of environmental 

factors that include water temperature, depth, turbidity, salinity, turbulence, and substrate suitability 

(Kemp, 1989; Onuf, 1996; Short et al., 2001). Seagrasses and freshwater SAVs provide important 

nursery and permanent habitat for sunfish, killifish, immature shrimp, crabs, drum, trout, flounder, and 

several other nekton species, and they provide a food source for species of wintering waterfowl and 

megaherbivores (Rozas and Odum, 1988; Rooker et al., 1998; Castellanos and Rozas, 2001; Heck et al., 

2003; Orth et al., 2006).

A source of potential long-term impacts to submerged beds from a catastrophic spill event is the 

possibility of buried or sequestered oil becoming resuspended after a disturbance, which would have 

similar effects as the original oiling event. This could occur in the event of hurricane impacts, which 

exacerbate the problem with numerous other short-terms stresses, such as turbidity, abrasion, breakage, 

uprooting SAV and seagrasses, and the alteration of bottom profiles and hydrology. Because different 

species have different levels of sensitivity to oil, it is difficult to compare studies and extrapolate what 

variables caused the documented differences in vegetation and community health (Thorhaug et al., 1986; 

Runcie et al., 2004). In general, studied seagrasses did not show significant negative effects from an oil 

spill (den Hartog and Jacobs, 1980; Kenworthy et al., 1993; Taylor et al., 2006 and 2007). 

If bays and estuaries accrue oil, there is an assumption that there would be a decrease in seagrass 

cover and negative community impacts. Submerged vegetation serves important ecological functions. 

For example, seagrasses and freshwater SAVs provide important habitat and are a food source for a wide 

range of species in multiple life history stages (Castellanos and Rozas, 2001; Short and Coles, 2001; 

Caldwell, 2003). Therefore, loss of submerged vegetation would adversely impact these species with a 

loss of valuable habitat and food. 
A-30 Western Planning Area Lease Sale 248 Supplemental EIS

Overall Summary and Conclusion (Phases 1-4) 

Because of the likely distance of an initial catastrophic spill event to submerged vegetation 

communities, there would be no adverse impacts to submerged vegetation resulting from the initial event 

(Phase 1). Also, with regards to an offshore spill event, there would likely be no adverse impacts to 

submerged vegetation before the spill reaches shore (Phase 2). An estimated probability of oil contacting 

its coastline from the WPA example OSRA run can be found in Appendix C of the WPA 238/246/248 

Supplemental EIS (Phase 3). It is assumed when these coastlines are contacted with oil, all associated 

habitat are considered oiled. If oil comes into areas with submerged beds, oil mixed with sediments or 

with dispersants could settle and coat an entire plant and could cause reduced chlorophyll production and 

could lead to a decrease in vegetation. Depending on the species and environmental factors (e.g., 

temperature and wave action), seagrasses may exhibit minimal impacts, such as localized loss of 

pigmentation, from an oil spill; however, communities residing within the beds could accrue greater 

negative outcomes. Increased vessel traffic from cleanup efforts would lead to elevated water turbidity 

and increased propeller scarring. A source of potential long-term impacts to submerged beds from a 

catastrophic spill event is the possibility of buried or sequestered oil becoming resuspended after a 

disturbance, which would have similar effects as the original oiling event (Phase 4). While there are 

impacts on submerged vegetation from an oiling event, the probabilities of an event to occur and contact 

coastlines are generally low and any impacts that can occur depend on a variety of factors (e.g., plant 

species, oil type, current environmental conditions, etc.). In general, studied seagrasses did not show 

significant negative effects from a spill (den Hartog and Jacobs, 1980; Kenworthy et al., 1993; Taylor 

et al., 2006 and 2007). 

A.3.1.6. Topographic Features

The Gulf of Mexico has a series of topographic features (banks or seamounts) on the continental shelf 

in water depths less than 300 m (984 ft). Topographic features are isolated areas of moderate to high 

relief that provide habitat for hard bottom communities of high biomass and moderate diversity. These 

features support prolific algae, invertebrate, and fish communities, and they provide shelter and food for 

large numbers of commercially and recreationally important fish. There are 37 named topographic 

features in the Gulf of Mexico with specific BOEM protections, including the Flower Garden Banks. 

BOEM has created “No Activity Zones” around topographic features in order to protect these habitats 

from disruption by oil and gas activities. A “No Activity Zone” is a protective perimeter drawn around 

each feature that is associated with a specific isobath (depth contour) surrounding the feature in which 

structures, drilling rigs, pipelines, and anchoring are not allowed. These “No Activity Zones” are areas 

where activity is prohibited based on BOEM’s policy. NTL 2009-G39 recommends that drilling should 

not occur within 152 m (500 ft) of a “No Activity Zone” of a topographic feature. 

Potentially sensitive biological features (PSBFs) are features that have moderate to high relief (8 ft 

[2 m] or higher), provide hard surface for sessile invertebrates, and attract fish, but they are not located 

within the “No Activity Zone” of topographic features. These features are frequently located near 

topographic features. No bottom-disturbing activities that may cause impact to these features are 

permitted. 

Phase 1—Initial Event

A blowout from an oil well could result in a catastrophic spill event. A catastrophic blowout would 

result in released oil rapidly rising to the sea surface because all known reserves in the GOM have 

specific gravity characteristics that would preclude oil from sinking immediately after release at a 

blowout site. The oil would surface almost directly over the source location. However, if the oil is 

ejected under high pressure, micro-droplets of oil may form and become entrained in the water column 

(Boehm and Fiest, 1982; Adcroft et al., 2010). The upward movement of the oil may be reduced if 

methane mixed with the oil is dissolved into the water column, reducing the oil’s buoyancy and slowing 

its rise to the surface (Adcroft et al., 2010). Large oil droplets would rise to the sea surface, but smaller 

droplets, formed by vigorous turbulence in the plume or the injection of dispersants, may remain neutrally 

buoyant in the water column, creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 

2010). Dispersed oil in the water column begins to biodegrade and may flocculate with particulate 
Catastrophic Spill Event Analysis A-31

matter, promoting sinking of the particles. Subsea plumes or sinking oil on particulates may contact 

topographic features.

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. Fine sediment could travel up to a few thousand 

meters before redeposition, negatively impacting a localized area of benthic communities. If a blowout 

were to occur near a topographic feature, suspended sediment may impact the organisms living on the 

lower levels of the topographic feature (since water currents flow around the banks rather than traveling 

uphill). 

A catastrophic blowout that occurs above the seabed (at the rig, along the riser between the seafloor 

and sea surface, or through leak paths on the BOP/wellhead) would not disturb the sediment. 

The use of subsea dispersants would increase the exposure of offshore benthic habitats to dispersed 

oil droplets in the water column, as well as the chemicals used in the dispersants. The use of subsea 

dispersants is not likely to occur for seafloor blowouts outside the well casing. 

Impacts to Topographic Features 

Impacts that occur to benthic organisms on topographic features as a result of a blowout would 

depend on the type of blowout, distance from the blowout, relief of the biological feature, and 

surrounding physical characteristics of the environment (e.g., turbidity). The NTL 2009-G39 

recommends the use of buffers to prevent blowouts in the immediate vicinity of a topographic feature or 

its associated biota. Much of the oil released from a blowout would rise to the sea surface, therefore 

minimizing the impact to benthic communities by direct oil exposure. However, small droplets of oil that 

are entrained in the water column for extended periods of time may migrate into No Activity Zones that 

surround the topographic feature. In addition, they may come in contact with PSBFs. Although these 

small oil droplets will not sink themselves, they may attach to suspended particles in the water column 

and then be deposited on the seafloor (McAuliffe et al., 1975). The resultant long-term impacts, such as 

reduced recruitment success, reduced growth, and reduced coral cover as a result of impaired recruitment, 

are discussed in Phase 4 (Post-Spill, Long-Term Recovery and Response). Also, if the blowout were to 

occur beneath the seabed, suspension and subsequent deposition of disturbed sediment may smother 

localized areas of benthic communities, possibly including organisms within No Activity Zones or on 

PSBFs.

Benthic communities on a topographic feature or PSBF exposed to large amounts of resuspended and 

deposited sediments following a catastrophic, subsurface blowout could be subject to sediment 

suffocation, exposure to resuspended toxic contaminants, and reduced light availability. Impacts to corals 

as a result of sedimentation would vary based on coral species, the height to which the coral grows, 

degree of sedimentation, length of exposure, burial depth, and the coral’s ability to clear the sediment. 

Impacts may range from sublethal effects such as reduced growth, alteration in form, and reduced 

recruitment and productivity to slower growth or death (Rogers, 1990). Corals may also experience 

discoloration or bleaching as a result of sediment exposure, although recovery from such exposure may 

occur within 1 month (Wesseling et al., 1999). 

The initial blowout impact would be greatest to communities located in clear waters with little 

suspended sediment that experience heavy sedimentation as a result of the blowout. Reef-building corals 

are sensitive to turbidity and may be killed by heavy sedimentation (Rogers, 1990; Rice and Hunter, 

1992). However, it is unlikely that reef-building corals would experience heavy sedimentation as a result 

of a blowout because drilling activity is not allowed near sensitive organisms in the No Activity Zones 

based on the lease stipulations as described in NTL 2009-G39. The most sensitive organisms are also 

typically elevated above soft sediments, making them less likely to be buried. The lower levels of 

topographic banks and the PSBFs, which are generally small features with only a few meters of relief, 

typically experience turbid conditions. Vigorous bottom currents (often generated by storms) frequently 

resuspend bottom sediments and bathe these features in turbid waters, which results in sedimentation. As 

a result, the organisms that live in this environment near the seafloor are those adapted to frequent 

sedimentation. 

Initial impacts would be much less extreme in a turbid environment (Rogers, 1990). For example, the 

South Texas Banks exist in a relatively turbid environment (the Nepheloid Zone). They generally have 

lower relief than the farther offshore banks at the shelf edge, may have a sediment cover, and exhibit 
A-32 Western Planning Area Lease Sale 248 Supplemental EIS

reduced biota. Sediment from a blowout, if it occurred nearby, may have a reduced impact on these 

communities compared with an open-water reef community, as these organisms are more tolerant of 

suspended sediment (Gittings et al., 1992). Many of the organisms that predominate in this community 

also grow tall enough to withstand the sedimentation that results from their turbid environment or have 

flexible structures that enable the passive removal of sediments (Gittings et al., 1992).

A portion or the entire rig may sink to the seafloor as a result of a blowout. The benthic features and 

communities upon which the rig settles would be destroyed or smothered. Encrusting organisms would 

be crushed by a rig if it lands on a topographic feature or PSBF. A settling rig may suspend sediments, 

which may smother nearby benthic communities if the sediment is redeposited on sensitive features. The 

habitats beneath the rig may be permanently lost; however, the rig itself may become an artificial reef 

upon which epibenthic organisms may settle. The surrounding benthic communities that were smothered 

by sediment would repopulate from nearby stocks through spawning recruitment and immigration if the 

hard substrate upon which they live was not physically destroyed. 

Phase 2—Offshore Spill

A spill from a shallow-water blowout could impact benthic communities on the continental shelf 

because of the blowout’s proximity to these habitats. The scenario (Table A-4) for a catastrophic spill on 

the continental shelf is assumed to last 2-5 months and to release 30,000 bbl per day. A total volume of 

0.9-3.0 MMbbl of South Louisiana midrange paraffinic sweet crude oil could be released, which will float 

(APIo >10). An anticipated 35,000 bbl of dispersant may be applied to the surface waters. 

A spill from a deepwater blowout could also impact shelf communities if surface oil is transported to

these areas. The scenario (Table A-4) for a catastrophic spill in deep water is assumed to last 4-6 months 

and to release 30,000-60,000 bbl per day. A total volume of 2.7-7.2 MMbbl of South Louisiana midrange 

paraffinic sweet crude oil will be released, which will float (APIo >10). Oil properties may change as it 

passes up the well and through the water column, and it may become emulsified. An anticipated 

33,000 bbl of dispersant may be applied to the surface waters and 16,500 bbl may be applied subsea. 

Weathering and dilution of the oil will also occur as it travels from its release point. It is unlikely that a 

subsurface plume from a deepwater blowout would impact shelf communities. The oil is anticipated to 

remain in deep water and be directed by water currents in the deep water. These currents do not typically 

transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 2008). 

Impacts to Topographic Features 

Impacts from Surface Oil

Sensitive reef communities flourish on topographic features and PSBFs in the Gulf of Mexico. Their 

depth below the sea surface helps to protect these habitats from a surface oil spill. Rough seas may mix 

the oil into subsurface water layers, where it may impact sessile biota. The longer the amount of time the 

seas are rough, the greater the amount of oil from a surface slick would be mixed into the water column. 

Measurable amounts of oil have been documented to mix from the surface down to a 10-m (33-ft) water 

depth, although modeling exercises have indicated such oil may reach a water depth of 20 m (66 ft). At 

this depth, however, the oil is found at concentrations several orders of magnitude lower than the amount 

shown to have an effect on corals (Lange, 1985; McAuliffe et al., 1975 and 1981a; Knap et al., 1985). 

None of the topographic features or PSBFs in the GOM is shallower than 10 m (33 ft), and only the 

Flower Garden Banks are shallower than 20 m (66 ft). Further detail on this catastrophic OSRA run is 

contained in Appendix C of the WPA238/246/248 Supplemental EIS. 

Impacts from Subsurface Oil

The presence of a subsurface oil plume on the continental shelf from a shallow-water blowout may 

affect benthic communities on topographic features and PSBFs. A majority of the oil released is expected 

to rise rapidly to the sea surface above the release point because of the specific gravity characteristics of 

the oil reserves in the GOM, thus not impacting sensitive benthic communities. If the oil is ejected under 

high pressure, oil droplets may become entrained in the water column (Boehm and Fiest, 1982; Adcroft 

et al., 2010). The upward movement of the oil may be reduced if methane mixed with the oil is dissolved 

into the water column, reducing the oil’s buoyancy and slowing its rise to the surface (Adcroft et al., 
Catastrophic Spill Event Analysis A-33

2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by vigorous 

turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the water column, 

creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). Dispersed oil in the water 

column begins to biodegrade and may flocculate with particulate matter, promoting sinking of the 

particles. Subsurface plumes generated by high-pressure dissolution of oil may come in contact with 

topographic features and PSBFs. A sustained spill would continuously create surface slicks and possibly 

subsurface spill plumes. Some of the oil in the water column will become diluted or evaporated over 

time, reducing any localized transport to the seafloor (Vandermeulen, 1982). In addition, microbial 

degradation of the oil occurs in the water column so that the oil would be less toxic as it travels from the 

source (Hazen et al., 2010). However, a sustained spill may result in elevated exposure concentrations to 

benthic communities if the plume reaches them. The longer the spill takes to stop, the longer the 

exposure time and higher the exposure concentration may be. 

The PSBFs have a greater chance of being impacted by subsea plumes than topographic features 

because currents tend to sweep around topographic features (Rezak et al., 1983; McGrail, 1982). The 

lower relief PSBFs may fall in the path of the plume because the feature is not large enough to divert a 

current. Low-level exposures of corals to oil from a subsea plume may result in chronic or temporary 

impacts. For example, feeding activity or reproductive ability may be reduced when coral is exposed to 

low levels of oil; however, impacts may be temporary or unable to be measured over time. Experimental 

simulations of exposure indicated that normal feeding activity of Porites porites and Madracis asperula

were reduced when exposed to 50 ppm oil (Lewis, 1971). In addition, reefs of Siderastrea siderea that 

were oiled in a spill produced smaller gonads than unoiled reefs, resulting in reproductive stress (Guzmán 

and Holst, 1993). 

Elevated concentrations of oil may be necessary to measure reduced photosynthesis or growth in 

corals. Photosynthesis of the zooxanthellae in Diplora strigosa exposed to approximately 18-20 ppm 

crude oil for 8 hours was not measurably affected, although other experiments indicate that 

photosynthesis may be impaired at higher concentrations (Cook and Knap, 1983). Measurable growth of 

Diploria strigosa exposed to oil concentrations up to 50 ppm for 6-24 hours did not show any reduced 

growth after 1 year (Dodge et al., 1984). 

Corals exposed to subsea oil plumes may incorporate petroleum hydrocarbons into their tissue. 

Records indicate that Siderastrea siderea, Diploria strigosa, and Montastrea annularis accumulate oil 

from the water column and incorporate petroleum hydrocarbons into their tissues (Burns and Knap, 1989; 

Knap et al., 1982; Kennedy et al., 1992). Most of the petroleum hydrocarbons are incorporated into the 

coral tissues, not their mucus (Knap et al., 1982). However, hydrocarbon uptake may also modify lipid 

ratios of coral (Burns and Knap, 1989). If lipid ratios are modified, mucus synthesis may be impacted, 

adversely affecting the coral’s ability to protect itself from oil through mucus production (Burns and 

Knap, 1989). 

It is unlikely that a subsurface plume from a deepwater blowout would impact shelf communities. 

The oil is anticipated to remain in deep water and be directed by water currents in the deep water. These 

currents do not typically transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 

2008). 

Impacts from Dispersed Oil 

If dispersants are used at the sea surface, oil may mix into the water column, or if applied subsea, they 

can travel with currents through the water and may contact or settle on sensitive features. Note that, as 

indicated above, a deepwater plume would not travel onto the continental shelf, but a plume formed on

the continental shelf could impact topographic features and PSBFs. If located near the source, the 

dispersed oil could be concentrated enough to harm the community. If the oil remains suspended for a 

longer period of time, it would be more dispersed and exist at lower concentrations. Reports on 

dispersant usage on surface oil indicate that a majority of the dispersed oil remains in the top 10 m (33 ft) 

of the water column, with 60 percent of the oil in the top 2 m (6 ft) (McAuliffe et al., 1981a). Dispersant 

usage also reduces the oil’s ability to stick to particles in the water column, minimizing oil adhering to 

sediments and traveling to the seafloor (McAuliffe et al., 1981a). However, after the Deepwater Horizon

oil spill, there was the formation of a dense layer of marine snow that aggregated and collected everything 

that it came in contact with it as it fell through the water column and settled on the seafloor (Passow et al., 

2012). 
A-34 Western Planning Area Lease Sale 248 Supplemental EIS

Dispersed oil reaching the topographic features and PSBFs in the Gulf of Mexico would be expected 

to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a). Such concentrations would not be 

life threatening to larval or adult stages at the depth of the features based on experiments conducted with 

coral. Any dispersed oil in the water column that comes in contact with corals may evoke short-term 

negative responses by the organisms (Wyers et al., 1986; Cook and Knap, 1983; Dodge et al., 1984). 

Reductions in feeding and photosynthesis could occur in coral exposed to dispersed oil. Short-term, 

sublethal responses of Diploria strigosa were reported after exposure to dispersed oil at a concentration of 

20 ppm for 24 hours. Although concentrations in this experiment were higher than what is anticipated for 

dispersed oil at depth, effects exhibited included mesenterial filament extrusion, extreme tissue 

contraction, tentacle retraction, and localized tissue rupture (Wyers et al., 1986). Normal behavior 

resumed within 2 hours to 4 days after exposure (Wyers et al., 1986). Diploria strigosa exposed to 

dispersed oil (20:1, oil:dispersant) showed an 85 percent reduction in zooxanthellae photosynthesis after 

8 hours of exposure to the mixture (Cook and Knap, 1983). However, the response was short term, as 

recovery occurred between 5 and 24 hours after exposure and return to clean seawater. Investigations 

1 year after Diploria strigosa was exposed to concentrations of dispersed oil between 1 and 50 ppm for 

periods between 6 and 24 hours did not reveal any impacts to growth (Dodge et al., 1984). 

Historical studies indicate dispersed oil to be more toxic to coral species than oil or dispersant alone. 

The greater toxicity may be a result of an increased number of oil droplets caused by the use of 

dispersant, resulting in greater contact area between oil, dispersant, and water (Elgershuizen and 

De Kruijf, 1976). The dispersant causes a higher water-soluble amount of oil to contact the cell 

membranes of the coral (Elgershuizen and De Kruijf, 1976). The mucus produced by coral, however, can 

protect the organism from oil. Both hard and soft corals have the ability to produce mucus, and mucus 

production has been shown to increase when corals are exposed to crude oil (Mitchell and Chet, 1975; 

Ducklow and Mitchell, 1979). Dispersed oil, however, which has very small oil droplets, does not appear 

to adhere to coral mucus, and larger untreated oil droplets may become trapped by the mucus barrier 

(Knap, 1987; Wyers et al., 1986). However, entrapment of the larger oil droplets may increase the coral’s 

long-term exposure to oil if the mucus is not shed in a timely manner (Knap, 1987; Bak and Elgershuizen, 

1976). Additionally, more recent field studies, using more realistic concentrations of dispersants, did not 

result in the toxicity historically reported (Yender and Michel, 2010).

Although historical studies indicated dispersed oil may be more toxic than untreated oil to corals 

during exposure experiments, untreated oil may remain in the ecosystem for long periods of time, while 

dispersed oil does not (Baca et al., 2005; Ward et al., 2003). Twenty years after an experimental oil spill 

in Panama, oil and impacts from untreated oil were still observed at oil treatment sites, but no oil or 

impacts were observed at dispersed oil or reference sites (Baca et al., 2005). Long-term recovery of the 

coral at the dispersed oil site had already occurred as reported in a 10-year monitoring update, and the site 

was not significantly different from the reference site (Ward et al., 2003).

Impacts from Oil Adhering to Sediments

BOEM’s policy, as described in NTL 2009-G39, prevents wells from being placed immediately 

adjacent to sensitive communities. In the event of a seafloor blowout, however, some oil could be carried 

to topographic features or PSBFs as a result of oil droplets adhering to suspended particles in the water 

column. Oiled sediment that settles to the seafloor may affect organisms attached to hard bottom 

substrates. Impacts may include reduced recruitment success, reduced growth, and reduced coral cover as 

a result of impaired recruitment. Experiments have shown that the presence of oil on available substrate 

for larval coral settlement has inhibited larval metamorphosis and larval settlement in the area. An 

increase in the number of deformed polyps after metamorphosis also took place because of exposure to oil 

(Kushmaro et al., 1997). 

The majority of organisms exposed to sedimented oil are expected to experience low-level 

concentrations because as the oiled sediments settle to the seafloor they are widely distributed. Coral may 

also be able to protect itself from low concentrations of sedimented oil that settles from the water column. 

Coral mucus may not only act as a barrier to protect coral from the oil in the water column, but it has also 

been shown to aid in the removal of oiled sediment on coral surfaces (Bak and Elgershuizen, 1976). 

Coral may use a combination of increased mucus production and the action of cilia to rid themselves of 

oiled sediment (Bak and Elgershuizen, 1976). 
Catastrophic Spill Event Analysis A-35

Impacts from Oil-Spill-Response Activity

Oil-spill-response activity may also impact sessile benthic features. Booms anchored to the seafloor 

are sometimes used to control the movement of oil at the water surface. Boom anchors can physically 

impact corals and other sessile benthic organisms, especially when booms are moved around by waves 

(USDOC, NOAA, 2010d). Vessel anchorage and decontamination stations set up during response efforts 

may also break or kill PSBFs if their location is unmapped and anchors are set on the features. Injury to 

coral reefs as a result of anchor impact may result in long-lasting damage or failed recovery (Rogers and 

Garrison, 2001). Effort should be made to keep vessel anchorage areas as far from sensitive benthic 

features as possible to minimize impact.

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 

buried. Based on stipulations as described in NTL 2009-G39, a well should be far enough away from a 

topographic feature to prevent extruded drilling muds from smothering sensitive benthic communities. 

However, if drilling muds were to travel far enough or high enough in the water column to contact a 

sensitive community, the fluid would smother the existing community. Experiments indicate that corals 

perish faster when buried beneath drilling mud than when buried beneath carbonate sediments 

(Thompson, 1980). Burial may lead to the elimination of a live bottom community. 

Phase 3—Onshore Contact

There would likely be no adverse impacts to topographic features and PSBFs as a result of the events 

and the potential impact-producing factors that could occur throughout Phase 3 of a catastrophic spill 

because the topographic features and PSBFs are located offshore.

Phase 4—Post-Spill, Long-Term Recovery and Response 

Topographic features and PSBFs exposed to large amounts of resuspended sediments following a 

catastrophic, subsurface blowout could be subject to sediment suffocation, exposure to resuspended toxic 

contaminants, and reduced light penetration. The greatest impacts would occur to communities that exist 

in clear water with very low turbidity. The consequences of a blowout along, directly on, or near one of 

these features could be long lasting, although the occurrence of a blowout near such sensitive 

communities is unlikely because of stipulations described in NTL 2009-G39, which prevents drilling 

activity near sensitive hard bottom habitats. Impacts to a community in more turbid waters, such as the 

South Texas Banks, would be greatly reduced, as the species on these features are tolerant of suspended 

sediments, and recovery would occur quicker. 

Impacts may also occur from low-level or long-term oil exposure. This type of exposure has the 

potential to impact reef communities, resulting in impaired health. Recovery may be fairly rapid from 

brief, low-level exposures, but it could be much longer with acute concentrations or long-term exposure 

to oil, such as in observations from Panama where untreated oil remained in the ecosystem for long 

periods of time, inhibiting coral recovery (Baca et al., 2005; Ward et al., 2003). Recovery time would 

therefore depend on recruitment from outside populations that were not affected by oiling and residence 

time of oil in an ecosystem.

Overall Summary and Conclusion (Phases 1-4) 

A catastrophic spill on the continental shelf would have a greater impact on topographic features and 

PSBFs than a deepwater spill. Surface oil from a deepwater spill would be weathered and diluted by the 

time it reaches the surface waters over topographic features and PSBFs (if it ever reaches them), and it 

would be unlikely that it would mix to the depth of active growth in concentrations that could cause 

toxicity. Subsea plumes formed in deepwater would not travel onto the continental shelf because deepsea currents do not travel up a slope. 

A catastrophic blowout and spill on the continental shelf has a greater chance to impact topographic 

features and PSBFs. If the blowout occurs close enough to sensitive features, the organisms may be 

smothered by settling sediment that was displaced by the blowout. The farther the feature is from the 

blowout, the less its chance of being covered with settling sediment or sediment upon which oil adhered. 
A-36 Western Planning Area Lease Sale 248 Supplemental EIS

In addition, distancing oil and gas activities from topographic features prevents the settlement of a sinking 

rig on top of a topographic feature, although it may destroy a PSBF. 

In most cases, impacts from oil would be sublethal. Surface oil is not expected to mix to the zone of 

active growth, and any oil components that do reach that depth would be in sublethal concentrations. 

Subsea plumes may contact the features; however, because currents tend to travel around, instead of over, 

topographic features, the topographic features should be protected from subsea plumes, while lower relief 

PSBFs may be impacted. Overall impacts of dispersed oil would be similar to subsea plumes. Spill 

response activity should not impact topographic features because it is unlikely that vessels would anchor 

on the features, but they could anchor on unmapped, lower relief PSBFs. 

Overall, a catastrophic spill would have a low probability of impacting topographic features because 

of the distancing requirements included in leases, as described in NTL 2009-G39, of oil and gas activities 

from topographic features, the depth of mixing of surface oil compared with the depth of the active 

growing zone, currents that sweep around the topographic features, and the weathering and dispersion of 

oil that would occur with distance from the source as it travels toward the features. The PSBFs could 

have greater impacts from a blowout as oil and gas activities are not as far distanced from them as 

topographic features; they have a lower relief than topographic features, which would not divert currents; 

and the locations of these features are not all known so accidental anchor impacts may result in breakage 

of the features and possibly destruction. The PSBFs would, however, have similar protection as for 

topographic features from surface oil.

A.3.1.7. Sargassum Communities

Pelagic Sargassum algae is a floating brown algae that occurs in all parts of the GOM throughout the 

year. It has a seasonal cycle so that its abundance greatly increases spring through fall, when it is carried 

by water currents around the south of Florida and then up the east coast (Gower and King, 2011). It 

occurs in patches, floating on and near the sea surface. Wind and water currents commonly drive it into 

long lines or windrows; when conditions are turbulent, it becomes more scattered and mixed into the 

upper water column. A key to understanding impacts to Sargassum is that the algae is ubiquitous and 

occurs in scattered patches in the very top part of the water column. Sargassum also provides habitat for 

pelagic species, including fish, invertebrates, and sea turtles.

Phase 1—Initial Event

During the initial phase of a catastrophic blowout, impacts may include disturbance of sediments, 

destruction of the drilling rig, release of oil and natural gas (methane), and emergency response efforts. 

This chapter deals with the immediate effects of a blowout that would be located at least 3 nmi (3.5 mi; 

5.6 km) from shore. 

Since Sargassum is a floating pelagic (open ocean) algae, it would only be affected by impacts that 

occur in the top-most part of the water column. In deep water (≥ 300 m, 984 ft), sediment disturbed by 

the blowout would not affect Sargassum because the sediment would not reach the surface waters. 

However, in shallow water, sediment from a blowout could have minor effects on Sargassum algae in the 

immediate vicinity. The sediment would have little effect on the algae itself, producing only slight, 

temporary silting that could reduce photosynthesis. If the sediment is contaminated with oil, then the oil 

could have adverse effects on the algae. Depending on the severity of oiling, the algae could be damaged 

or destroyed; but this would only affect the algae in the local vicinity of the blowout. Sediment and oil 

would have a more acute effect on the associated invertebrate, fish, and sea turtle community that utilizes 

the habitat of the Sargassum. Impacts to these organisms may include “changes in respiration rate, 

abrasion and puncturing of structures, reduced feeding, reduced water filtration rates, smothering, delayed 

or reduced hatching of eggs, reduced larval growth or development, abnormal larval development, or 

reduced response to physical stimulus” (Anchor Environmental CA, L.P., 2003). 

Destruction of the oil drilling rig and associated equipment could have an acute effect on patches of 

Sargassum algae that happen to be caught in the structure (if it sinks) or destroyed by fuel leaks and 

possible fire on the sea surface. This could destroy local patches of Sargassum, but it would have no 

measurable effect on the Sargassum community as a whole. 

The release of oil during the initial blowout event would be expected to cover local patches of 

Sargassum algae with oil, destroying the algae and associated organisms. Methane gas may also bathe 
Catastrophic Spill Event Analysis A-37

local patches of algae as it rises through the sea surface; it would have little effect on the algae itself but 

may poison associated organisms. The initiation of oil and gas release (as defined for this phase) at the 

site of the blowout event would affect only local patches of Sargassum, but it would have no measurable 

effect on the Sargassum community as a whole.

Emergency response activities would have minor impacts to Sargassum algae that comes in contact 

with vessels. This is mostly the simple impingement of the algae on the ships’ water intake screens, 

including water that may be pumped in fire-fighting efforts. This minor and local effect would have no 

measurable effect on the Sargassum community as a whole. 

Phase 2—Offshore Spill

During the second phase of a catastrophic blowout, the major impact of concern is the release of oil 

and methane over time. Response efforts may produce additional minor impacts to Sargassum. This 

chapter deals with the growing effects of a blowout that releases oil and methane into the offshore 

environment. 

Since Sargassum is a floating pelagic (open ocean) algae, it would be affected by impacts that occur 

in the top-most part of the water column. This makes Sargassum habitat particularly susceptible to 

damage from offshore oil spills. Oceanographic processes that concentrate Sargassum into mats and rafts 

would also concentrate toxic substances. Therefore, it may be assumed that Sargassum would be found in 

areas where oil, dispersants, and other chemicals have accumulated following a catastrophic spill. Oil 

spreads on the sea surface to form extremely thin layers (0.01-0.1 micrometers) that cover large areas 

(MacDonald et al., 1996). Since Sargassum is ubiquitous in surface waters of the GOM, oil spreading on 

the sea surface can be expected to coincide with floating mats of the algae. The larger the quantity of 

spill and the longer it flows, the larger the area of sea surface it would cover. A catastrophic spill would 

cover a large area and result in impacts to a large quantity of Sargassum algae. For example, Macondo

well oil spill covered up to one-third of the northern GOM (McCrea-Strub and Pauly, 2011; USDOC, 

NMFS, 2011a) and may have affected about one-third of the Sargassum algae in the northern GOM at the 

time.

The severity of oiling to Sargassum depends largely on physical conditions. Factors include the 

quantity of oil at a particular launch point and its physical state, distance from the source, weather 

conditions, and the possible use of dispersants. Further detail on this catastrophic OSRA run is contained 

in Appendix C of the WPA 238/246/248 Supplemental EIS. 

Obviously, more oil leads to increased oiling, but the physical state of the oil changes as it weathers, 

biodegrades, dissipates, and emulsifies over time and distance. Storms can mix oil into the water column

(expected maximum of 10-20 m [33-66 ft]; Lange, 1985; McAuliffe et al., 1975 and 1981a; Knap et al., 

1985; Scarlett et al., 2005; Hemmer et al., 2010; George-Ares and Clark, 2000), possibly increasing its 

contact with Sargassum as it also mixes the Sargassum into the water column. However, when storms are 

not mixing the oil, they are also not mixing the Sargassum, so the Sargassum would float near the sea 

surface, just as the oil would. Convergence zones, places in the ocean where strong opposing currents 

meet, would collect both oil and Sargassum. Sea turtles, especially post-hatchlings and juveniles, use 

these areas for food and cover. Witherington et al. (2012) surveyed sea turtles in the eastern Gulf of 

Mexico and Atlantic Ocean off Florida and found that 89 percent of the turtles documented were observed 

within 1 m (3 ft) of floating Sargassum. The use of dispersants on surface oil slicks could increase the 

exposure of Sargassum to oil by promoting mixing of oil into the upper few meters of the water column. 

This also promotes the dispersion of oil, speeding its decline toward low concentrations that would be less 

toxic. Regardless, any exposure that is enough to cause visible oiling can be expected to have significant 

detrimental effects on the organisms associated with Sargassum and, likely, effects on the Sargassum

itself. Heavy oiling of Sargassum near the source of the spill would destroy the affected algae. Very 

light exposure far from the oil source may have little effect.

The specific effects of oil on Sargassum depend on the severity of oiling. High to moderate levels of 

oiling would likely cause complete mortality. Low levels of exposure may result in a range of sublethal 

effects to the algae and its associated community. Powers et al. (2013) suggest that exposure to oil and/or 

dispersants can result in direct, sublethal, and indirect effects to Sargassum, resulting in death or a 

decrease in Sargassum-related ecosystem services. Sublethal responses in organisms associated with 

Sargassum may occur at concentrations as low as 1-10 ppb (Hyland and Schneider, 1976). Rogers (1990) 

documented impacts such as reduced growth, alteration in form, and reduced recruitment and 
A-38 Western Planning Area Lease Sale 248 Supplemental EIS

productivity. Other sublethal impacts may include reduced feeding rates, reduced ability to detect food, 

erratic movement, ciliary inhibition, tentacle retraction, reduced movement, decreased aggression, and 

altered respiration (Scarlett et al., 2005; Suchanek, 1993). Embryonic life stages of organisms may 

experience toxicity at lower levels than the adult stages (Fucik et al., 1995; Suchanek, 1993; Beiras and 

Saco-Álvarez, 2006; Byrne, 1989). The algae itself would be less sensitive than many of its associates, 

since the algae produces oils of its own and has a waxy coating that may protect it from physical oiling. 

Response efforts aimed at removing oil from the affected area would have minor impacts on 

Sargassum algae as well. Response vessels would impinge a small amount of the algae on their 

propellers and cooling-water intakes. Cleanup processes such as booming, skimming, and in-situ burning 

would also trap and destroy patches of Sargassum; however, these activities would take place in areas of 

high concentration of surface oil, where Sargassum would likely be destroyed by oil contamination even 

if the cleanup activity were absent.

Phase 3—Onshore Contact

This third phase of a catastrophic blowout focuses on the approach of oil to the shoreline. This 

involves the possible oiling of coastal resources including beaches, wetlands, SAV and seagrasses, the 

shallow seafloor, and any resources drifting in the water column (e.g., Sargassum). Response efforts can 

produce additional serious impacts.

There would likely be little additional impact to pelagic Sargassum algae as oil approaches a 

shoreline. Since both the algae and surface oil approaching shore would be guided by the same forces 

(wind and water currents), they would likely be already traveling together, with the algae already 

contaminated. Once it is onshore, the Sargassum would die, regardless of oil contamination. Sargassum

that washes ashore has some value to the ecosystem as it provides food and shelter for some organisms as 

it decays. This value would be mostly lost if the Sargassum is oiled when it reaches shore.

Phase 4—Post-Spill, Long-Term Recovery and Response 

The final phase of a catastrophic blowout is the long-term response of the ecosystem and its recovery. 

Both, the natural rate of recovery and the persistence of oil in natural habitats over time determine the 

long-term effects. Contaminants biodegrade over time, but they may become sequestered as inert forms 

(e.g., buried in sediment) until disturbed (by storms) and re-activated, producing renewed impacts.

Sargassum algae has a yearly seasonal cycle of growth and a yearly cycle of migration from the GOM 

to the western Atlantic. A catastrophic spill could affect a large portion of the annual crop of the algae. 

A large event, such as the Macondo well blowout and spill, could reduce the standing crop of Sargassum

in the GOM and subsequently in the western Atlantic if it coincided with a period when Sargassum

distribution was limited to the northwest GOM in an area known to be a nursery area. This could have a 

cascading effect down current (in the Atlantic) that would stress the cycles of other organisms that depend 

on the Sargassum habitat. However, the effect can be expected to diminish with remoteness from the 

direct impacts of the spill, i.e., the algae community itself would be most affected, with lesser effects on 

organisms that utilize the habitat as a nursery, for feeding, as shelter, or other purposes.

While a large spill event could affect a large portion of the standing crop of Sargassum, several 

factors contribute to the quick recovery of the habitat. Sargassum algae is predominately found in the 

open-ocean pelagic habitat. Once the spill event subsides, the pelagic habitat would quickly regain its 

typically very high water quality. The pelagic habitat far from shore is also far from land-based sources 

of pollution. Only part of the Sargassum stocks would be affected; algae not affected by the spill event 

would continue to grow normally and repopulate the habitat. Since Sargassum has a seasonal cycle of 

growth in the summer and reduction in the winter, populations in the winter following a catastrophic 

event may be similar to populations of any other year. Relatively small populations survive each winter, 

subsequently repopulating the habitat each year. With this pattern, recovery from the effects of a 

catastrophic event is expected within 1-2 growing seasons. 

Overall Summary and Conclusion (Phases 1-4) 

Pelagic Sargassum algae is one of the most likely habitats to be affected by a catastrophic offshore oil 

spill; however, because of its ubiquitous distribution and seasonal cycle, recovery is expected within 

1-2 years. Sargassum algae floats on and near the sea surface and occurs in patches that can be collated 
Catastrophic Spill Event Analysis A-39

into windrows by wind and water currents. Oil from a spill offshore would accumulate in the same 

waters, making it inevitable that some patches of Sargassum would be severely affected.

The initial catastrophic event (Phase 1) could destroy Sargassum patches in the immediate vicinity of 

the accident. Impingement, fire, and the initial concentrated spillage of oil and fuels would destroy local 

patches. Sediments disturbed by the accident would only affect Sargassum if the event occurred in 

shallow waters.

The duration of the spill event (Phase 2) would have the most effect on floating Sargassum algae. 

Patches of algae within the entire coverage of the oil slick would be subject to severe damage and death. 

Algae in areas farther from the spill, receiving lower level impacts, may still suffer damage, especially the 

sensitive invertebrate and fish communities associated with the habitat. Efforts to remove the oil could 

gather Sargassum with the oil, but these algae patches would likely be destroyed by the oil anyway since 

the collection activities would occur in areas of concentrated oil.

As oil approaches shore (Phase 3), impacts to floating Sargassum algae would not increase much, as 

the algae would likely already be exposed to the oil since wind and water currents drive both the algae 

and the oil. 

The recovery of floating Sargassum algae (Phase 4) may occur within 1-2 years because the algae has 

a yearly cycle of subsidence and re-growth. As long as the nursery grounds are not completely saturated 

with oil, the pelagic habitat would quickly regain its high level of water quality after the cessation of a 

spill. Not all of the Sargassum habitat would be affected, even by a catastrophic spill; healthy algae 

would continue to grow and replenish the population. Within 1-2 years, the Sargassum algae community 

may have completely recovered from the impacts of a catastrophic spill.

A.3.1.8. Chemosynthetic Deepwater Benthic Communities

Deepwater benthic communities of the Gulf of Mexico include soft bottom, chemosynthetic, and 

coral habitats. Deep water, for ecology in the GOM, is defined as water depths over 300 m (984 ft) 

because chemosynthetic communities and Lophelia coral habitats have not been found in waters 

shallower than these depths. The possible impacts to these benthic communities from a catastrophic 

blowout depend on the location and the nature of the event.

Phase 1—Initial Event

During the initial phase of a catastrophic blowout, impacts may include the disturbance of sediments, 

destruction of the drilling rig, release of oil and natural gas (methane), and emergency response efforts. 

This chapter deals with the immediate effects of a blowout located at least 3 nmi (3.5 mi; 5.6 km) from 

shore. 

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. Some fine sediment could travel up to a few 

thousand meters before redeposition, negatively impacting a localized area of benthic communities. If a 

blowout were to occur close enough to a chemosynthetic community, suspended sediment may impact the 

organisms. Restrictions described in NTL 2009-G40 require drilling to be removed at least 610 m 

(2,000 ft) from possible chemosynthetic communities. During a blowout, sediment may become 

contaminated with oil and subsequently deposit that oil down-current from the source. The highest 

concentrations of contamination would be nearest the well, and concentrations would diminish with 

distance. A catastrophic blowout that occurs above the seabed (at the rig, along the riser between the 

seafloor and sea surface, or through leak paths on the BOP/wellhead) would not disturb the sediment.

Destruction of the oil drilling rig and associated equipment could have an acute effect on any 

chemosynthetic communities caught under the direct impact of the equipment when it falls to the seafloor. 

However, the restrictions described in NTL 2009-G40 require drilling locations to be 610 m (2,000 ft) 

from any possible indications of chemosynthetic communities, reducing the possibility that a rig would 

settle directly on sensitive habitat.

A catastrophic blowout would likely result in released oil rapidly rising to the sea surface because 

typical reserves in the GOM have specific gravity characteristics that are much lighter than water (refer to 

Chapter 3.2.1.3 of this Supplemental EIS; Environment Canada, 2011; Trudel et al., 2001). The oil 

would surface almost directly over the source location. Oil floating to the sea surface would be 
A-40 Western Planning Area Lease Sale 248 Supplemental EIS

effectively removed from affecting chemosynthetic communities on the seafloor. Even oil treated with 

chemical dispersants on the sea surface would not be expected to have widespread impacts to deepwater 

communities. Reports on dispersant usage on surface oil indicate that a majority of the dispersed oil 

remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (6 ft) 

(McAuliffe et al., 1981a; Lewis and Aurand, 1997). Lubchenco et al. (2010) reports that chemically 

dispersed surface oil from the Macondo well blowout and oil spill remained in the top 6 m (20 ft) of the 

water column where it mixed with surrounding waters and biodegraded. However, if the oil is ejected 

under high pressure, micro-droplets of oil may form and become entrained in the water column (Boehm 

and Fiest, 1982; Adcroft et al., 2010). Upward movement of oil may also be reduced if methane mixed 

with the oil is dissolved into the water column, reducing the buoyancy of the oil/gas stream (Adcroft 

et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by vigorous 

turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the water column, 

creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). It is unlikely that any 

chemosynthetic community would be affected by the initial stage of a catastrophic event due to the 

required separation of drilling activities from sensitive habitats, because released oil would rise rapidly to 

a level above the habitat, and because surface oil would not mix to the depths of the chemosynthetic 

communities. The required separation distance would also allow for a subsea plume to mix with the 

surrounding water and become diluted before it reached a deepwater community. 

Phase 2—Offshore Spill

During the second phase of a catastrophic blowout, the major impact of concern is the release of oil 

and methane over time. Response efforts may produce additional impacts. This chapter deals with the 

growing effects of a blowout that releases oil and methane into the offshore environment.

A spill resulting from a catastrophic blowout in deep water has the potential to impact offshore 

benthic communities; however, it is not likely that deepwater benthic communities would be affected by a 

spill from a shallow-water blowout. Although subsurface plumes can be generated when oil is ejected 

under high pressure or dispersants are used subsea, a majority of the oil originating from a seafloor 

blowout in deep water is expected to rise rapidly to the sea surface. Upward movement of the oil may 

also be reduced if methane mixed with the oil is dissolved into the water (Adcroft et al., 2010). A 

sustained spill would continuously create surface slicks and possibly subsurface spill plumes. Some of 

the oil in the water column would become diluted over time, reducing transport to the seafloor 

(Vandermeulen, 1982). Concentrations of dispersed and dissolved oil in the Macondo well blowout and 

spill subsea plume were reported to be in the part per million range or less and were generally lower away 

from the water’s surface and away from the wellhead (Adcroft et al., 2010; Haddad and Murawski, 2010; 

Joint Analysis Group, 2010; Lubchenco et al., 2010). In addition, microbial degradation of oil occurs in 

the water column rendering oil less toxic when it contacts the seafloor (Hazen et al., 2010). Oil can 

precipitate to the seafloor by adhering to other particles, much like rainfall (Kingston et al., 1995; 

International Tanker Owners Pollution Federation Limited, 2011). Oil would also reach the seafloor 

through planktonic consumption and associated excretion, which is distributed over the seafloor 

(International Tanker Owners Pollution Federation Limited, 2011). These mechanisms would result in a 

wide distribution of small amounts of oil. Throughout these processes, oil would be biodegraded from 

bacterial action, which would continue on the seafloor, resulting in scattered microhabitats with an 

enriched carbon environment (Hazen et al., 2010). 

A sustained spill may result in elevated exposure concentrations to chemosynthetic features if a 

subsea oil plume contacts them directly. Dispersed oil is mixed with water, and its movement is then 

dictated by water currents and the physical, chemical, and biodegradation pathways. BOEM’s policy 

(refer to NTL 2009-G39) prevents wells from being placed immediately adjacent to sensitive 

communities; however, in the event of a seafloor blowout, some oil could be carried to chemosynthetic 

communities by subsea plumes. Impacts may include reduced recruitment success, reduced growth, and 

reduced biological cover as a result of impaired recruitment. Concentrated oil plumes reaching 

chemosynthetic communities could cause oiling of organisms, resulting in the death of entire populations 

on localized sensitive habitats. The longer the oil remains suspended in the water column, the more 

dispersed, less concentrated, and more biodegraded it would become. Depending on how long oil 

remained suspended in the water column, it may be thoroughly degraded by biological action before 

contacting the seafloor (Hazen et al., 2010; Valentine et al., 2010). Biodegradation rates in cold, 
Catastrophic Spill Event Analysis A-41

deepwater environments are not well understood at this time. In general, potential impacts to 

chemosynthetic communities would be localized due to the directional movement of oil plumes by the 

water currents and because the sensitive habitats have a scattered, patchy distribution. While a few patch 

habitats may be affected, the Gulfwide ecosystem of chemosynthetic communities would be expected to 

suffer no significant effects.

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 

buried. Based on stipulations as described in NTL 2009-G40, a well should be far enough away from a 

chemosynthetic community to prevent extruded drilling muds from smothering sensitive benthic 

communities. 

Phase 3—Onshore Contact

The third phase of a catastrophic blowout focuses on the approach of oil to the shoreline. This 

involves the possible oiling of coastal resources including beaches, wetlands, SAV and seagrasses, the 

shallow seafloor, and any resources drifting in the water column. Response efforts can produce additional 

serious impacts. There would be no additional adverse impacts to chemosynthetic communities in deep 

water as a result of the events and the potential impact-producing factors that could occur throughout 

Phase 3 of a catastrophic spill because the chemosynthetic communities are located offshore in deep 

water (>300 m, 610 ft). 

Phase 4— Post-Spill, Long-Term Recovery and Response 

The final phase of a catastrophic blowout is the long-term response of the ecosystem and its recovery. 

Both the natural rate of recovery and the persistence of oil in natural habitats over time determine what 

long-term effects may occur. Contaminants degrade over time but may become sequestered as inert 

forms (e.g., buried in sediment) until disturbed and reactivated, producing renewed impacts. 

If oil is ejected under high pressure or dispersants are applied at the source near the seafloor, oil 

would mix into the water column, be carried by underwater currents, and eventually contact the seafloor 

in some form, either concentrated (near the source) or dispersed and decayed (farther from the source). 

The oil could then impact patches of chemosynthetic community habitat in its path. The farther the 

dispersed oil travels, the more diluted it would become as it mixes with surrounding water. 

Chemosynthetic communities located at more than 610 m (2,000 ft) away from a blowout could 

experience minor impacts from suspended sediments that travel with currents, although the sediment 

concentration would be diluted with distance from the well. Studies indicate that periods of decades to 

hundreds of years are required to reestablish a seep community once it has disappeared (depending on the 

community type) (Powell, 1995; Fisher, 1995). There is evidence that substantial impacts on these 

communities could permanently prevent reestablishment, particularly if hard substrate required for 

recolonization is buried by resuspended sediments from a blowout. A catastrophic spill combined with 

the application of dispersant has the potential to cause devastating effects on local patches of habitat in 

the path of subsea plumes where they physically contact the seafloor. Sublethal effects are possible for 

communities that receive a lower level of impact. Examples of these effects could include temporary lack 

of feeding, expenditure of energy to remove the oil, loss of gametes and reproductive delays, and loss of 

tissue mass. Oil plumes that remain in the water column for longer periods would disperse and decay, 

having only minimal effect. Depending on how long it remains in the water column, oil may be 

thoroughly degraded by biological action before contacting the seafloor. Water currents can carry a 

plume to contact the seafloor directly but a more likely scenario would be for oil to adhere to other 

particles and precipitate to the seafloor, much like rainfall (Kingston et al., 1995; International Tanker 

Owners Pollution Federation Limited, 2011). Oil would also reach the seafloor through planktonic 

consumption and associated excretion, which is distributed over the seafloor (International Tanker 

Owners Pollution Federation Limited, 2011). These mechanisms would result in a wide distribution of 

small amounts of oil (or oil by-products). This oil would be in the process of biodegradation from 

bacterial action, which would continue on the seafloor, resulting in scattered microhabitats with an 

enriched carbon environment (Hazen et al., 2010). Habitats directly under the path of the oil plume as it 
A-42 Western Planning Area Lease Sale 248 Supplemental EIS

disperses and “rains” down to the seafloor may experience minor effects, but since the oil would be 

deposited in a widely scattered and decayed state, little effect is anticipated.

Overall Summary and Conclusion (Phases 1-4) 

Chemosynthetic communities would potentially be subject to detrimental effects from a catastrophic 

seafloor blowout. Sediment and oiled sediment from the initial event (Phase 1) are not likely to reach 

chemosynthetic communities in heavy amounts because of requirements described in NTL 2009-G40. 

Fine sediment from a blowout may reach the location of sensitive habitats, producing sublethal effects. 

The initial accident could result in the drilling rig and equipment falling on a sensitive seafloor habitat if 

the structure travels more than 610 m (2,000 ft) from the well site. 

The ongoing spill event (Phase 2) would have the most effect on chemosynthetic communities. 

Chemosynthetic communities are at risk from subsea oil plumes that could directly contact localized 

patches of sensitive habitat. Oil plumes reaching chemosynthetic communities could cause oiling of 

organisms, resulting in the death of entire populations on localized sensitive habitats. However, potential 

impacts would be localized due to the directional movement of oil plumes by the water currents and 

because the sensitive habitats have a scattered, patchy distribution. The more likely scenario would be 

exposure to widely dispersed, biodegraded particles that “rain” down from a passing oil plume. While a 

few patch habitats may be affected, the Gulfwide ecosystem of chemosynthetic communities would be 

expected to suffer no significant effects. 

As oil approaches shore (Phase 3), there would be no additional adverse impacts to chemosynthetic 

communities because the chemosynthetic communities are located offshore in deep water (>300 m; 

610 ft).

The recovery of chemosynthetic communities (Phase 4) depends on the severity of initial impacts. A 

catastrophic spill combined with the application of dispersant has the potential to cause devastating 

effects on local patches of habitat in the path of subsea plumes where they physically contact the seafloor. 

Studies indicate that periods from decades to hundreds of years are required to reestablish a seep 

community once it has disappeared (depending on the community type) (Powell, 1995; Fisher, 1995). 

The burial of hard substrate could permanently prevent recovery. Sublethal effects are possible for 

communities that receive a lower level of impact. Examples of these effects could include temporary lack 

of feeding, expenditure of energy to remove the oil, loss of gametes and reproductive delays, and loss of 

tissue mass. However, most chemosynthetic community habitats are expected to experience no impacts 

from a catastrophic seafloor blowout because of the directional movement of oil plumes by the water 

currents and because the sensitive habitats have a scattered, patchy distribution.

A.3.1.9. Nonchemosynthetic Deepwater Benthic Communities

Deepwater benthic communities of the Gulf of Mexico include soft bottom, chemosynthetic, and live 

bottom communities (mostly deepwater coral communities). Deep water, for ecology in the GOM, is 

defined as water depths over 300 m (984 ft) because nonchemosynthetic communities and Lophelia coral 

habitats have not been found in waters shallower than these depths. The possible impacts to 

nonchemosynthetic deepwater benthic communities from a catastrophic blowout depend on the location 

and the nature of the event. 

Phase 1—Initial Event

During the initial phase of a catastrophic blowout, impacts may include disturbance of sediments, 

destruction of the drilling rig, release of oil and natural gas (methane), and emergency response efforts. 

This phase deals with the immediate effects of a blowout located at least 3 nmi (3.5 mi; 5.6 km) from 

shore. 

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. A blowout that occurs outside the well casing 

can rapidly deposit 30 cm (12 in) or more of sediment within a few hundred meters and may smother 

much of the soft bottom community in a localized area. Some fine sediment could travel up to a few 

thousand meters before redeposition, negatively impacting a localized area of benthic communities. 

Many of the organisms on soft bottoms live within the sediment and have the ability to migrate upward in 
Catastrophic Spill Event Analysis A-43

response to burial by sedimentation. In situations where soft bottom infaunal communities are negatively 

impacted, recolonization by populations from neighboring soft bottom substrate would be expected over a 

relatively short period of time for all size ranges of organisms, in a matter of days for bacteria and 

probably less than 1 year for most macrofauna and megafauna species. Recolonization could take longer 

for areas affected by direct contact of concentrated oil. 

If a blowout were to occur close enough to a sensitive deepwater live bottom community, suspended 

sediment may impact the organisms. Restrictions described in NTL 2009-G40 require drilling to be 

removed at least 610 m (2,000 ft) from possible live bottom communities. During a blowout, suspended 

sediment may become contaminated with oil and subsequently deposit that oil down-current from the 

source. The highest concentrations of contamination would be nearest the well, and concentrations would 

diminish with distance. A catastrophic blowout that occurs above the seabed (at the rig, along the riser 

between the seafloor and sea surface, or through leak paths on the BOP/wellhead) would not disturb the 

sediment.

Destruction of the oil drilling rig and associated equipment could have an acute effect on any 

nonchemosynthetic communities caught under the direct impact of the equipment when it falls to the 

seafloor. However, the restrictions described in NTL 2009-G40 require drilling locations to be 610 m 

(2,000 ft) from any possible indications of sensitive live bottom communities, reducing the possibility 

that a rig would settle directly on sensitive habitat.

A catastrophic blowout would likely result in released oil rapidly rising to the sea surface because 

typical reserves in the GOM have specific gravity characteristics that are much lighter than water (refer to 

Chapter 3.2.1.3 of this Supplemental EIS; Environment Canada, 2011; Trudel et al., 2001). The oil 

would surface almost directly over the source location. Oil floating to the sea surface would be 

effectively removed from affecting nonchemosynthetic communities on the seafloor. Even oil treated 

with chemical dispersants on the sea surface would not be expected to have widespread impacts to 

deepwater communities. Reports on dispersant usage on surface oil indicate that a majority of the 

dispersed oil remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m

(6 ft) (McAuliffe et al., 1981a; Lewis and Aurand, 1997). Lubchenco et al. (2010) report that chemically 

dispersed surface oil from the Macondo well blowout and oil spill remained in the top 6 m (20 ft) of the 

water column where it mixed with surrounding waters and biodegraded. However, if the oil is ejected 

under high pressure, micro-droplets of oil may form and become entrained in the water column (Boehm 

and Fiest, 1982; Adcroft et al., 2010). Upward movement of the oil may also be reduced if methane 

mixed with the oil is dissolved into the water column, reducing the buoyancy of the oil/gas stream 

(Adcroft et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by 

vigorous turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the 

water column, creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). It is 

unlikely that any deepwater live bottom community would be affected by the initial stage of a 

catastrophic event due to the required separation of drilling activities from sensitive habitats, because 

released oil would rapidly rise to a level above the habitat, and because surface oil would not mix to the 

depths of such communities. The required separation distance would also allow for a subsea plume to 

mix with the surrounding water and become diluted before it reached a deepwater community. 

Phase 2—Offshore Spill

During the second phase of a catastrophic blowout, the major impact of concern is the release of oil 

and methane over time. Response efforts may produce additional impacts. This chapter deals with the 

growing effects of a blowout that releases oil and methane into the offshore environment.

A spill resulting from a catastrophic blowout in deep water has the potential to impact offshore 

benthic communities; however, it is not likely that deepwater benthic communities would be affected by a 

spill from a shallow-water blowout. Although subsurface plumes can be generated when oil is ejected 

under high pressure or when dispersants are used subsea, a majority of the oil originating from a seafloor 

blowout in deep water is expected to rise rapidly to the sea surface. Oil and chemical spills that originate 

at the sea surface are not considered to be a potential source of measurable impacts on deepwater, live 

bottom communities because of the water depths at which these communities are located. Oil spills at the 

surface would tend not to sink, and the risk of weathered components of a surface slick reaching the 

benthos in any measurable concentration would be very small. Surface oil also could not physically mix 
A-44 Western Planning Area Lease Sale 248 Supplemental EIS

to depths of deepwater communities under natural conditions (Lange, 1985; McAuliffe et al., 1975 and 

1981a; Tkalich and Chan, 2002). 

Upward movement of the oil may also be reduced if methane mixed with the oil is dissolved into the 

water (Adcroft et al., 2010). A sustained spill would continuously create surface slicks and possibly 

subsurface spill plumes. One deepwater coral site at a depth of 1,370 m (4,495 ft) has been reported as 

severely damaged following the Macondo well blowout and oil spill. The site is in Mississippi Canyon 

Block 294, 11 km (7 mi) southwest of the spill location. The site includes hard substrate supporting coral 

in an area approximately 10 x 12 m (33 x 39 ft) (White et al., 2012). The published results document 

damage to the coral community. Forty-three coral colonies were analyzed via close-up imagery: 

86 percent exhibited signs of impact; 46 percent exhibited impact to at least 50 percent of the colony; and 

23 percent of the colonies sustained impact to more than 90 percent of the colony (White et al., 2012). 

Many other associated invertebrates also exhibited signs of stress. This appears to be an exceptional case, 

since the numerous other communities investigated since the spill remained healthy (White et al., 2012). 

Some of the oil in the water column would become diluted over time, reducing transport to the seafloor 

(Vandermeulen, 1982). Concentrations of dispersed and dissolved oil in the Macondo well blowout and 

spill subsea plume were reported to be in the part per million range or less and were generally lower away 

from the water’s surface and away from the wellhead (Adcroft et al., 2010; Haddad and Murawski, 2010; 

Joint Analysis Group, 2010; Lubchenco et al., 2010). In addition, microbial degradation of the oil occurs 

in the water, rendering the oil less toxic when it contacts the seafloor (Hazen et al., 2010). However, as 

evidenced by the report of White et al. (2012), subsea plumes can still retain toxic concentrations over a 

distance of at least 11 km (7 mi). Oil in a plume can adhere to other particles and precipitate to the

seafloor, much like rainfall (Kingston et al., 1995; International Tanker Owners Pollution Federation 

Limited, 2011). Oil also would reach the seafloor through consumption by plankton, with excretion 

distributed over the seafloor (International Tanker Owners Pollution Federation Limited, 2011). These 

mechanisms would result in a wide distribution of small amounts of oil. Throughout these processes, oil 

would be biodegraded from bacterial action, which would continue on the seafloor, resulting in scattered 

microhabitats with an enriched carbon environment (Hazen et al., 2010). 

A sustained spill may result in elevated exposure concentrations to live bottom features if a subsea oil 

plume contacts them directly. Dispersed oil is mixed with water, and its movement is then dictated by 

water currents and the physical, chemical, and biological degradation pathways. BOEM’s policy (refer to 

NTL 2009-G40) prevents wells from being placed immediately adjacent to sensitive communities; 

however, in the event of a seafloor blowout, some oil could be carried to live bottom communities by 

subsea plumes. Impacts may include reduced recruitment success, reduced growth, and reduced 

biological cover as a result of impaired recruitment. Concentrated oil plumes reaching live bottom 

communities could cause oiling of organisms, resulting in the death of entire populations on localized 

sensitive habitats. The longer the oil remains suspended in the water column the more dispersed, less 

concentrated, and more degraded it would become. Depending on how long oil remained suspended in 

the water column, it may be thoroughly degraded by biological action before contacting the seafloor 

(Hazen et al., 2010; Valentine et al., 2010). Biodegradation rates in cold, deepwater environments are not 

well understood at this time. In general, the potential impacts to deepwater live bottom communities 

would be localized due to the directional movement of oil plumes by the water currents and because the 

sensitive habitats have a scattered, patchy distribution. While a few patch habitats may be affected, the 

Gulfwide ecosystem of deepwater live bottom communities would be expected to suffer no significant 

effects.

Drilling muds comprised primarily of barite may be pumped into a well to stop a blowout. If a “kill” 

is not successful, the mud (possibly tens of thousands of barrels) may be forced out of the well and 

deposited on the seafloor near the well site. Any organisms beneath the extruded drilling mud would be 

buried. Based on stipulations as described in NTL 2009-G40, a well should be far enough away from 

sensitive live bottom communities to prevent extruded drilling muds from smothering them. 

Phase 3—Onshore Contact

The third phase of a catastrophic blowout focuses on the approach of oil to the shoreline. This 

involves the possible oiling of coastal resources including beaches, wetlands, SAV and seagrasses, the 

shallow seafloor, and any resources drifting in the water column. Response efforts can produce additional 

serious impacts. There would be no adverse impacts to nonchemosynthetic benthic communities in deep 
Catastrophic Spill Event Analysis A-45

water as a result of the events and the potential impact-producing factors that could occur throughout 

Phase 3 of a catastrophic spill because the communities are located offshore in deep water (>300 m; 

610 ft).

Phase 4—Post-Spill, Long-Term Recovery and Response 

The final phase of a catastrophic blowout is the long-term response of the ecosystem and its recovery. 

Both the natural rate of recovery and the persistence of oil in natural habitats over time determine what 

long-term effects may occur. Contaminants degrade over time, but they may become sequestered as inert 

forms (e.g., buried in sediment) until disturbed and re-activated, producing renewed impacts.

Although deepwater coral and other live bottom communities often live in close association with 

hydrocarbon seeps (since the carbonate substrate is precipitated by chemosynthetic communities), this 

does not mean they are necessarily tolerant to the effects of oil contamination. Natural seepage is very 

constant and at very low rates as compared with the potential volume of oil released from a catastrophic 

event (blowout or pipeline rupture). In addition, live bottom organisms, such as Lophelia pertusa, inhabit 

areas around the perimeter of seeps and sites where hydrocarbon seepage has reduced its flow or stopped. 

Typical Gulf of Mexico oil is light and floats rapidly to the surface rather than being carried horizontally 

across benthic communities by water currents (Johansen et al., 2001; MacDonald et al., 1995; Trudel 

et al., 2001). So, although deepwater live bottom communities are found near oil seeps, they are not 

typically exposed to concentrated oil.

If oil is ejected under high pressure or dispersants are applied at the source near the seafloor, oil 

would mix into the water column, be carried by underwater currents, and eventually contact the seafloor 

in some form, either concentrated (near the source) or dispersed and decayed (farther from the source). 

The oil could then impact patches of live bottom community habitat in its path. The farther the dispersed 

oil travels, the more diluted it would become as it mixes with surrounding water. Sensitive live bottom 

communities located at more than 610 m (2,000 ft) away from a blowout could experience minor impacts 

from suspended sediments that travel with currents, although the sediment concentration would be diluted 

with distance from the well.

There have been no experiments showing the response of deepwater corals to oil exposure. 

Experiments with shallow tropical corals indicate that corals have a high tolerance to oil exposure. The 

mucus layers on coral resist penetration of oil and slough off the contaminant. Longer exposure times and 

areas of tissue where oil adheres to the coral are more likely to result in tissue damage and death of 

polyps. Corals with branching growth forms appear to be more susceptible to damage from oil exposure 

(Shigenaka, 2001). The most common deepwater coral, Lophelia pertusa, is a branching species. Tests 

with shallow tropical gorgonians indicate relatively low toxic effects to the coral (Cohen et al., 1977), 

suggesting deepwater gorgonians may have a similar response. Depending on the level of exposure, the 

response of deepwater coral to oil from a catastrophic spill would vary. Exposure to widely dispersed oil 

adhering to organic detritus and partially degraded by bacteria may be expected to result in little effect. 

Direct contact with plumes of relatively fresh dispersed oil droplets in the vicinity of the incident could 

cause the death of affected coral polyps through exposure and potential feeding on oil droplets by polyps. 

Median levels of exposure to dispersed oil in a partly degraded condition may result in effects similar to 

those of shallow tropical corals, with often no discernible effects other than temporary contraction and 

some sloughing. The health of corals may be degraded by the necessary expenditure of energy as the 

corals respond to oiling (Shigenaka, 2001). Communities exposed to more concentrated oil may 

experience detrimental effects, including death of affected organisms, tissue damage, lack of growth, 

interruption of reproductive cycles, and loss of gametes. Many invertebrates associated with deepwater 

coral communities, particularly the crustaceans, would likely be more susceptible to damage from oil 

exposure. The recolonization of severely damaged or destroyed communities could take years or decades. 

Burial of hard substrate could permanently prevent recovery. However, because of the scarcity of 

deepwater hard bottoms, their comparatively low surface area, and the distancing requirements set by 

BOEM in NTL 2009-G40, it is unlikely that a sensitive habitat would be located adjacent to a seafloor 

blowout or that concentrated oil would contact the site. 

A catastrophic spill combined with the application of dispersant has the potential to cause devastating 

effects on local patches of habitat in the path of subsea plumes where they physically contact the seafloor. 

Sublethal effects are possible for communities that receive a lower level of impact. Examples of these 

effects could include temporary lack of feeding, expenditure of energy to remove the oil, loss of gametes 
A-46 Western Planning Area Lease Sale 248 Supplemental EIS

and reproductive delays, and loss of tissue mass. Oil plumes that remain in the water column for longer 

periods would disperse and decay, having only minimal effect. Depending on how long it remains in the 

water column, oil may be thoroughly degraded by biological action before contacting the seafloor. Water 

currents can carry a plume to contact the seafloor directly, but a more likely scenario would be for oil to 

adhere to other particles and precipitate to the seafloor, much like rainfall (Kingston et al., 1995; 

International Tanker Owners Pollution Federation Limited, 2011). Oil also would reach the seafloor 

through consumption by plankton with excretion distributed over the seafloor (International Tanker 

Owners Pollution Federation Limited, 2011). These mechanisms would result in a wide distribution of 

small amounts of oil (or oil by-products). This oil would be in the process of biodegradation from 

bacterial action, which would continue on the seafloor, resulting in scattered microhabitats with an 

enriched carbon environment (Hazen et al., 2010). Habitats directly under the path of the oil plume as it 

disperses and “rains” down to the seafloor may experience minor effects, but since the oil would be 

deposited in a widely scattered and decayed state, little effect is anticipated.

Overall Summary and Conclusion (Phases 1-4) 

Nonchemosynthetic communities would potentially be subject to detrimental effects from a 

catastrophic seafloor blowout. Sediment and oiled sediment from the initial event (Phase 1) are not likely 

to reach sensitive live bottom communities in heavy amounts because of requirements described in NTL 

2009-G40. Fine sediment from a blowout may reach the location of sensitive habitats, producing 

sublethal effects. The initial accident could result in the drilling rig and equipment falling on a sensitive 

seafloor habitat if the structure travels more than 610 m (2,000 ft) from the well site. 

The ongoing spill event (Phase 2) would have the most effect on nonchemosynthetic communities. 

Deepwater live bottom communities are at risk from subsea oil plumes that could directly contact 

localized patches of sensitive habitat. Oil plumes reaching live bottom communities could cause oiling of 

organisms, resulting in the death of entire populations on localized sensitive habitats. However, the 

potential impacts would be localized due to the directional movement of oil plumes by the water currents 

and because the sensitive habitats have a scattered, patchy distribution. The more likely result would be 

exposure to widely dispersed, biodegraded particles that “rain” down from a passing oil plume. While a 

few patch habitats may be affected, the Gulfwide ecosystem of live bottom communities would be 

expected to suffer no significant effects. 

As oil approaches shore (Phase 3), there would be no adverse impacts to nonchemosynthetic 

communities because the communities are located offshore in deep water (>300 m; 610 ft). 

The recovery of nonchemosynthetic communities (Phase 4) depends on the severity of initial impacts. 

A catastrophic spill combined with the application of dispersant has the potential to cause devastating 

effects on local patches of sensitive habitat in the path of subsea plumes where they physically contact the 

seafloor. The recolonization of severely damaged or destroyed communities could take years or decades. 

Burial of hard substrate could permanently prevent recovery. Sublethal effects are possible for 

communities that receive a lower level of impact. Examples of these effects could include temporary lack 

of feeding, expenditure of energy to remove the oil, loss of gametes and reproductive delays, and loss of 

tissue mass. However, most live bottom community habitats are expected to experience no impacts from 

a catastrophic seafloor blowout because of the directional movement of oil plumes by the water currents 

and because the sensitive habitats have a scattered, patchy distribution.

A.3.1.10. Soft Bottom Benthic Communities

The seafloor on the continental shelf in the Gulf of Mexico consists primarily of muddy to sandy 

sediments. Benthic organisms found on the seafloor include infauna (animals that live in the substrate, 

including mostly burrowing worms, crustaceans, and mollusks) and epifauna (animals that live on or are 

attached to the substrate; mostly crustaceans, as well as echinoderms, mollusks, hydroids, sponges, soft 

and hard corals, and demersal fishes). Infauna is comprised of meiofauna, small organisms (63-500 μm)

that live among the grains of sediment; and macroinfauna, slightly larger organisms (>0.5 mm; 0.02 in) 

that live in the sediment (Dames and Moore, Inc., 1979). Shrimp and demersal fish are closely associated 

with the benthic community. The most abundant organisms on the continental shelf are the depositfeeding polychaetes. The slope and deep sea consist of vast areas of primarily fine sediments that support 
Catastrophic Spill Event Analysis A-47

benthic communities with lower densities and biomass but higher diversity than the continental shelf 

(Rowe and Kennicutt, 2001). 

Phase 1—Initial Event

A blowout from an oil well could result in a catastrophic spill event. A catastrophic blowout would 

result in released oil rapidly rising to the sea surface because all known reserves in the GOM have 

specific gravity characteristics that would preclude oil from sinking immediately after release at a 

blowout site. The oil would surface almost directly over the source location. However, if the oil is 

ejected under high pressure, micro-droplets of oil may form and become entrained in the water column 

(Boehm and Fiest, 1982; Adcroft et al., 2010). The upward movement of the oil may be reduced if 

methane mixed with the oil is dissolved into the water column, reducing the oil’s buoyancy (Adcroft 

et al., 2010). Large oil droplets would rise to the sea surface, but smaller droplets, formed by vigorous 

turbulence in the plume or the injection of dispersants, may remain neutrally buoyant in the water column, 

creating a subsurface plume (Adcroft et al., 2010; Joint Analysis Group, 2010). Dispersed oil in the water 

column begins to biodegrade and may flocculate with particulate matter, promoting sinking of the 

particles. Subsea plumes or sinking oil on particulates may contact portions of the seafloor. 

A catastrophic blowout outside the well casing and below the seafloor or at the seafloor-water 

interface could resuspend large quantities of bottom sediments and create a large crater, destroying many 

organisms within a few hundred meters of the wellhead. Some fine sediment could travel up to a few 

thousand meters before redeposition, negatively impacting a localized area of benthic communities. The 

localized seafloor habitat around which a seafloor blowout occurs would be impacted by suspended and 

redeposited sediment.

A catastrophic blowout that occurs above the seabed (at the rig, along the riser between the seafloor 

and sea surface, or through leak paths on the BOP/wellhead) would not disturb the sediment. 

The use of subsea dispersants would increase the exposure of offshore benthic habitats to dispersed 

oil droplets in the water column, as well as the chemicals used in the dispersants. The use of subsea 

dispersants is not likely to occur for seafloor blowouts outside the well casing. 

Impacts to Soft Bottom Benthic Communities

Impacts that occur to benthic organisms as a result of a blowout would depend on the type of blowout 

and their distance from the blowout. Also, if the blowout were to occur beneath the seabed, soft sediment 

habitat would be destroyed by the formation of a crater, and the suspension and subsequent deposition of 

disturbed sediment would smother localized areas of benthic communities. A blowout that occurs outside 

the well casing can rapidly deposit 30 cm (12 in) or more of sediment within a few hundred meters and 

may smother much of the soft bottom community in a localized area. Benthic communities exposed to 

large amounts of resuspended and deposited sediments following a catastrophic, subsurface blowout 

could be subject to smothering, sediment suffocation, and exposure to resuspended toxic contaminants. 

Impacts to organisms as a result of sedimentation would vary based on species tolerance, degree of 

sedimentation, length of exposure, burial depth, and vertical migration ability through sediment.

A portion or the entire rig may sink to the seafloor as a result of a blowout. The benthic features and 

communities upon which the rig settles would be destroyed or smothered. A settling rig may suspend 

sediments, which may smother nearby benthic communities. The habitats beneath the rig may be 

permanently lost; however, the rig itself may become an artificial reef upon which epibenthic organisms 

may settle. The surrounding benthic communities that were smothered by sediment would repopulate 

from nearby stocks through spawning recruitment and immigration if the hard substrate upon which they 

live was not physically destroyed.

Phase 2—Offshore Spill

A spill from a shallow-water blowout could impact benthic communities on the continental shelf. 

The scenario (Table A-4) for a catastrophic spill on the continental shelf is assumed to last 2-5 months 

and to release 30,000 bbl per day. A total volume of 0.9-3.0 MMbbl of South Louisiana midrange 

paraffinic sweet crude oil could be released, which would float (APIo >10). An anticipated 35,000 bbl of 

dispersant may be applied to the surface waters.
A-48 Western Planning Area Lease Sale 248 Supplemental EIS

A spill from a deepwater blowout could also impact shelf communities and deepwater communities. 

The scenario (Table A-4) for a catastrophic spill in deep water is assumed to last 4-6 months and to 

release 30,000-60,000 bbl per day. A total volume of 2.7-7.2 MMbbl of South Louisiana midrange 

paraffinic sweet crude oil could be released, which would float (APIo >10). Oil properties may change as 

it passes up the well and through the water column, and it may become emulsified. An anticipated 

33,000 bbl of dispersant may be applied to the surface waters and 16,500 bbl may be applied subsea. 

Weathering and dilution of the oil would also occur as it travels from its launch point. It is unlikely that a 

subsurface plume from a deepwater blowout would impact shelf communities. The oil is anticipated to 

remain in deep water and be directed by water currents in the deep water. These currents do not typically 

transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 2008). 

Impacts to Soft Bottom Benthic Communities

Impacts from Surface Oil

Surface oil slicks can spread over a large area; however, the majority of the slick is comprised of a 

very thin surface layer of oil moved by winds and currents (Lewis and Aurand, 1997). The potential of 

surface oil slicks to affect benthic habitats is limited by its ability to mix into the water column. Soft 

bottom benthic communities below 10-m (33-ft) water depth are protected from surface oil because of its 

lack of ability to mix with water (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich and Chan, 

2002). Benthic organisms would not become physically coated or smothered by surface oil. However, if 

this surface oil makes its way into the water column through physical mixing, the use of dispersants, or 

the sedimenting to particles in the water column, benthic communities may be impacted. These scenarios 

are discussed in later sections.

Disturbance of the sea surface by storms can mix surface oil into the water column, but the effects are 

generally limited to the upper 10-20 m (33-66 ft) (Lange, 1985; McAuliffe et al., 1975 and 1981a; Tkalich 

and Chan, 2002). Therefore, soft bottom benthic communities located in shallow water have the potential 

to be fouled by oil that is floating on shallow water and mixes to the depth of the seafloor. Nearshore oil 

deposits that occur in sheltered areas, such as bays, may remain in the sediment and impact organisms for 

long periods. Oil in nearshore sediments was found in high concentrations 8 years following the Exxon 

Valdez spill (Dean and Jewett, 2001). Benthic communities located in deeper water would not be 

impacted by oil physically mixed into the water column. However, if dispersants are used, they would 

enable oil to mix into the water column and possibly impact organisms in deeper water. Dispersants are 

discussed later in this chapter. Further detail on this catastrophic OSRA run is contained in Appendix C 

of the WPA 238/246/248 Supplemental EIS. 

Impacts from Subsurface Oil

The presence of a subsurface oil plume on the continental shelf from a shallow-water blowout may 

affect soft bottom benthic communities. A majority of the oil released is expected to rise rapidly to the 

sea surface above the launch point because of the specific gravity characteristics of the oil reserves in the 

GOM, thus not directly sinking to the seafloor and smothering benthic communities. If the oil is ejected 

under high pressure, oil droplets may become entrained in the water column (Boehm and Fiest, 1982; 

Adcroft et al., 2010). The upward movement of the oil may be reduced if methane mixed with the oil is 

dissolved into the water column, reducing the oil’s buoyancy (Adcroft et al., 2010). Large oil droplets 

would rise to the sea surface, but smaller droplets, formed by vigorous turbulence in the plume or the 

injection of dispersants, may remain neutrally buoyant in the water column, creating a subsurface plume 

(Adcroft et al., 2010; Joint Analysis Group, 2010). Dispersed oil in the water column begins to 

biodegrade and may flocculate with particulate matter, promoting sinking of the particles. Subsurface 

plumes generated by high-pressure dissolution of oil may come in contact with portions of the seafloor as 

it travels from the source. A sustained spill would continuously create surface slicks and possibly 

subsurface plumes. Some of the oil in the water column will become diluted or evaporated over time, 

reducing any localized transport to the seafloor (Vandermeulen, 1982). In addition, microbial degradation 

of the oil occurs in the water column so that the oil would be less toxic as it travels from the source 

(Hazen et al., 2010). However, a sustained spill may result in elevated exposure concentrations to benthic 

communities if the plume reaches them. The longer the spill takes to stop, the longer the exposure time 

and higher the exposure concentration may be. 
Catastrophic Spill Event Analysis A-49

Soft bottom infaunal communities that come into direct contact with oil may experience sublethal 

and/or lethal effects. The greatest effects of oil exposure would occur close to the well and impacts 

would decrease with distance. A subsurface plume that contacts the seafloor may result in acute toxicity. 

The water accommodated fraction (WAF) or water soluble fraction (WSF) of oil that dissolves in water 

may be the most toxic to organisms, especially larvae and embryos in the water column or at the water 

sediment interface. Lethal effects for marine invertebrates have been reported at exposures between 

0.10 ppm to 100 ppm WSF of oil (Suchanek, 1993). The WSF of petroleum hydrocarbons was reportedly 

highly toxic to the embryos of oysters and sea urchins, while sediment containing weathered fuel was not 

toxic to the same species (Beiras and Saco-Álvarez, 2006). Quahog clam embryos and larvae also 

experienced toxicity and deformation of several different crude oils at WSF concentrations between 

0.10 ppm and 10 ppm (Byrne and Calder, 1977). An experiment indicated that the WSF of No. 2 fuel oil 

at a concentration of 5 ppm disrupted the cellular development of 270 out of 300 test organisms within 

3 hours of exposure (Byrne, 1989). After 48 hours exposure, all of the test organisms died and the 

48-hour LC50 (lethal concentration for 50% of the test population) was calculated to be 0.59 ppm (Byrne, 

1989). Another experiment indicated that a WSF of 0.6 ppm and greater of No. 2 fuel oil depressed 

respiration, reduced mobility of sperm, interfered with cell fertilization and embryonic cleavage, and 

retarded larval development of sand dollar eggs (Nicol et al., 1977). Experiments that exposed sea urchin 

embryos to 10-30 ppm WSF of diesel oil for 15-45 days resulted in defective embryonic development and 

nonviable offspring (Vashchenko, 1980). Therefore, any dissolved petroleum hydrocarbon constituents 

that reach larval benthic organisms may cause acute toxicity and other developmental effects to this life 

stage. The WAF and WSF, however, should be considered “worst-case scenario” values as they are 

based on a closed system at equilibrium with the contaminant and, due to its size and complexity, the 

GOM will not reach equilibrium with released oil. 

Oil in the water column may impact pelagic eggs and larvae of invertebrates. Toxicity tests indicated 

that eggs of many species were killed by diesel oil in seawater, and in general, the smaller eggs died 

earlier (Chia, 1973). Bivalve fertilization and sperm fertility were depressed with exposure to crude oil 

(Renzoni, 1975). The WSF of crude oil was also highly toxic to gametes, embryos, and larvae of bivalves 

(Renzoni, 1975). Oil concentrations of 0.1 and 1 ppm caused a decrease in fertilization, development of 

embryos, survival or larvae, and larval growth in the bivalves Crassostrea virginica and Mulinia lateralis

(Renzoni, 1975). Another experiment, however, calculated the LC50 for a 6-hour exposure of the 

gametes, eggs, and larvae of three bivalves (Crassostrea angulata, Crassostrea gigas, and Mytilus 

galloprovincialis) to be 1,000 ppm oil and 1,000 ppm oil plus dispersant (Renzoni, 1973). Toxicity varies 

widely among species and oil types.

Sublethal responses of marine invertebrates may result in population level changes (Suchanek, 1993). 

Such sublethal responses may occur at concentrations as low as 1-10 ppb (Hyland and Schneider, 1976). 

Sublethal impacts may include reduced feeding rates, reduced ability to detect food, ciliary inhibition, 

reduced movement, decreased aggression, and altered respiration (Suchanek, 1993).

The farther a subsea plume travels, the more physical and biological changes occur to the oil before it 

reaches benthic organisms. Oil would become diluted as it physically mixes with the surrounding water, 

and significant evaporation occurs from surface slicks. The most toxic compounds of oil are lost within 

the first 24 hours of a spill, leaving the heavier, less toxic compounds in the system (Ganning et al., 

1984). An even greater component of the lighter fuel oils dissipates through evaporation. Water currents 

could carry a plume to contact the seafloor directly, but a likely scenario would be for the oil to adhere to 

other particles and precipitate to the seafloor, much like rainfall (International Tanker Owners Pollution 

Federation Limited, 2011; Kingston et al., 1995). Oil also would reach the seafloor through consumption 

by plankton, with excretion distributed over the seafloor (International Tanker Owners Pollution 

Federation Limited, 2011). The longer and farther a subsea plume travels in the sea, the more dilute the 

oil would be (Vandermeulen, 1982; Tkalich and Chan, 2002). In addition, microbial degradation of the 

oil occurs in the water column, reducing toxicity (Hazen et al., 2010; McAuliffe et al., 1981b). The oil 

would move in the direction of prevailing currents (S.L. Ross Environmental Research Ltd., 1997) and, 

although the oil would weather with the distance it travels, low levels of oil transported in subsea plumes 

would impact benthic communities. These mechanisms would result in a wide distribution of small 

amounts of oil. This oil would be in the process of biodegradation from bacterial action, which would 

continue on the seafloor, resulting in scattered microhabitats with an enriched carbon environment (Hazen 

et al., 2010). 
A-50 Western Planning Area Lease Sale 248 Supplemental EIS

Localized areas of lethal effects would be recolonized by populations from neighboring soft bottom 

substrate once the oil in the sediment has been sufficiently reduced to a level able to support marine life 

(Sanders et al., 1980; Lu and Wu, 2006; Ganning et al., 1984; Gómez Gesteira and Dauvin, 2000; Dean 

and Jewett, 2001). This initial recolonization process may be fairly rapid, but full recovery may take up 

to 10 years depending on the species present, substrate in the area, toxicity of oil spilled, concentration 

and dispersion of oil spilled, and other localized environmental factors that may affect recruitment 

(Kingston et al., 1995; Gómez Gesteira and Dauvin, 2000; Sanders et al., 1980; Conan, 1982). 

Opportunistic species would take advantage of the barren sediment, repopulating impacted areas first. 

These species may occur within the first recruitment cycle of the surrounding populations or from species 

immigration from surrounding stocks and may maintain a stronghold in the area until community 

succession begins (Rhodes and Germano, 1982; Sanders et al., 1980). 

It is unlikely that a subsurface plume from a deepwater blowout would impact shelf communities. 

The oil is anticipated to remain in deep water and be directed by water currents in the deep water. These 

currents do not typically transit from deep water up onto the shelf (Pond and Pickard, 1983; Inoue et al., 

2008). However, the impacts to deepwater soft bottom benthic communities as a result of a blowout 

would be similar to those on the continental shelf.

Impacts from Dispersed Oil

If dispersants are used at the sea surface, oil may mix into the water column, and if they are applied 

subsea, dispersed oil can travel with currents and contact the seafloor. Chemically dispersed oil from a 

surface slick is not anticipated to result in lethal exposures to organisms on the seafloor. The chemical 

dispersion of oil may increase the weathering process and allow surface oil to be diluted by greater 

amounts of water. Reports on dispersant usage on surface plumes indicate that a majority of the dispersed 

oil remains in the top 10 m (33 ft) of the water column, with 60 percent of the oil in the top 2 m (6 ft) 

(McAuliffe et al., 1981a). Dispersant usage also reduces the oil’s ability to stick to particles in the water 

column, minimizing oiled sediments from traveling to the seafloor (McAuliffe et al., 1981a). If applied, 

subsea benthic communities near the source could be exposed to dispersed oil that is concentrated enough 

to harm the benthic community. If the oil remains suspended for a longer period of time, it would be 

more dispersed and less concentrated. There is very little information on the behavior of subsea 

dispersants. 

Dispersed oil used at the sea surface reaching the benthic communities in the Gulf of Mexico would 

be expected to be at very low concentrations (<1 ppm) (McAuliffe et al., 1981a). Such concentrations 

would not be life threatening to larval or adult stages on the seafloor based on experiments conducted 

with benthic and pelagic species (Scarlett et al., 2005; Hemmer et al., 2010; George-Ares and Clark, 

2000). Any dispersed oil in the water column that comes in contact with benthic communities may evoke 

short-term negative responses by the organisms (Scarlett et al., 2005). Sublethal responses may include 

reduced feeding rate, erratic movement, and tentacle retraction (Scarlett et al., 2005). In addition, 

although dispersants were detected in waters off Louisiana after the Macondo well blowout and spill, they 

were below USEPA benchmarks of chronic toxicity (OSAT, 2010). The rapid dilution of dispersants in 

the water column and lack of transport to the seafloor were also reported by OSAT (2010) where no 

dispersants were detected in sediment on the Gulf floor following the Macondo well blowout and spill. 

Impacts from Oil Adhering to Sediments

Oiled sediment that settles to the seafloor may affect organisms upon which it settles. The greatest 

impacts would be closest to the well where organisms may become smothered by particles and exposed to 

hydrocarbons. High concentrations of suspended sediment in the water column may lend to large 

quantities of oiled sediment (Moore, 1976). Deposition of oiled sediment is anticipated to begin 

occurring within days or weeks of the spill and may be fairly deep near the source (Ganning et al., 1984; 

Gómez Gesteira and Dauvin, 2000). Oily sand layers were reported to be 10 cm (4 in) deep on the 

seafloor near the Amoco Cadiz spill (Gómez Gesteira and Dauvin, 2000). Acute toxicity may occur near 

the spill, eliminating benthic communities. 

Much of the oil released from a blowout would rise to the sea surface, therefore dispersing the 

released oil before it makes its way back to the seafloor through flocculation, by deposition from 

organisms that pass it through their systems with food, and by adhering to sinking particles in the water 
Catastrophic Spill Event Analysis A-51

column. In addition, small droplets of oil that are entrained in the water column for extended periods of 

time may migrate a great distance from their point of release and may attach to suspended particles in the 

water column and later be deposited on the seafloor (McAuliffe et al., 1975). The majority of organisms 

exposed to oiled sediment are anticipated to experience low-level concentrations because as the oiled 

sediments settle to the seafloor they are widely dispersed. Impacts may include reduced recruitment 

success, reduced growth, and altered community composition as a result of impaired recruitment.

Impacts from Oil-Spill-Response Activity

Continued localized disturbance of soft bottom communities may occur during oil-spill response 

efforts. Anchors used to set booms to contain oil or vessel anchors in decontamination zones may affect 

infaunal communities in the response activity zone. Infaunal communities may be altered in the anchor 

scar, and deposition of suspended sediment may result from the setting and resetting of anchors. The 

disturbed benthic community should begin to repopulate from the surrounding communities during their 

next recruitment event and through immigration of organisms from surrounding stocks. Any 

decontamination activities, such as cleaning vessel hulls of oil, may also contaminate the sediments of the 

decontamination zone, as some oil may settle to the seabed, impacting the underlying benthic community.

If a blowout occurs at the seafloor, drilling muds (primarily barite) may be pumped into a well in 

order to “kill” it. If a kill is not successful, the mud (possibly tens of thousands of barrels) may be forced 

out of the well and deposited on the seafloor near the well site. Any organisms beneath heavy layers of 

the extruded drilling mud would be buried. Base fluids of drilling muds are designed to be low in toxicity 

and biodegradable in offshore marine sediments (Neff et al., 2000). However, as bacteria and fungi break 

down the drilling fluids, the sediments may temporarily become anoxic (Neff et al., 2000). Benthic 

macrofaunal recovery would occur when drilling mud concentrations are reduced to levels that enable the 

sediment to become re-oxygenated (Neff et al., 2000). Complete community recovery from drilling mud 

exposure may take 3-5 years, although microbial degradation of drilling fluids, followed by an influx of 

tolerant opportunistic species, is anticipated to begin almost immediately (Neff et al., 2000). In addition, 

the extruded mud may bury hydrocarbons from the well, making them a hazard to the infaunal species 

and difficult to remove. 

Phase 3—Onshore Contact

There would likely be no additional adverse impacts to soft bottom benthic communities as a result of 

events and the potential impact producing factors that could occur throughout Phase 3 of a catastrophic 

spill because these soft bottom benthic communities are located below the water line.

Phase 4—Post-Spill, Long-Term Recovery and Response 

Benthic Habitats

In situations where soft bottom infaunal communities are negatively impacted, recolonization by 

populations from neighboring soft bottom substrate would be expected over a relatively short period. 

Recolonization would begin with recruitment and immigration of opportunistic species from surrounding 

stocks. More complex communities would follow with time. Repopulation could take longer for areas 

affected by direct oil contact in higher concentrations. 

Many of the organisms on soft bottoms live within the sediment and have the ability to migrate 

upward in response to burial by sedimentation. A blowout that occurs outside the well casing can rapidly 

deposit 30 cm (12 in) or more of sediment within a few hundred meters and may smother much of the soft 

bottom community in a localized area. In situations where soft bottom infaunal communities are 

negatively impacted, recolonization by populations from neighboring soft bottom substrate would be 

expected over a relatively short period of time for all size ranges of organisms, in a matter of days for 

bacteria, and probably less than 1 year for most macrofauna and megafauna species. Recolonization 

could take longer for areas affected by direct contact of concentrated oil. Initial repopulation from nearby 

stocks of pioneering species, such as tube-dwelling polychaetes or oligochaetes, may begin with the next 

recruitment event (Rhodes and Germano, 1982). Full recovery would follow as later stages of 

successional communities overtake the pioneering species (Rhodes and Germano, 1982). The time it 

takes to reach a climax community may vary depending on the species and degree of impact. Full benthic 
A-52 Western Planning Area Lease Sale 248 Supplemental EIS

community recovery may take years to decades if the benthic habitat is heavily oiled (Gómez Gesteira 

and Dauvin, 2000; Sanders et al., 1980; Conan, 1982). A slow recovery rate would result in a community 

with reduced biological diversity and possibly a lesser food value for predatory species.

Localized areas of lethal effects would be recolonized by populations from neighboring soft bottom 

substrate once the oil in the sediment has been sufficiently reduced to a level able to support marine life 

(Sanders et al., 1980; Lu and Wu, 2006; Ganning et al., 1984; Gómez Gesteira and Dauvin, 2000; Dean 

and Jewett, 2001). This initial recolonization process may be fairly rapid, but full recovery may take up 

to 10 years depending on the species present, substrate in the area, toxicity of oil spilled, concentration 

and dispersion of oil spilled, and other localized environmental factors that may affect recruitment 

(Kingston et al., 1995; Gómez Gesteira and Dauvin, 2000; Sanders et al., 1980; Conan, 1982). 

Opportunistic species would take advantage of the barren sediment, repopulating impacted areas first. 

These species may occur within the first recruitment cycle of the surrounding populations or from species 

immigration from surrounding stocks and may maintain a stronghold in the area until community 

succession begins (Rhodes and Germano, 1982; Sanders et al., 1980). 

Overall Summary and Conclusion (Phases 1-4) 

A catastrophic blowout and spill would have the greatest impact on the soft bottom benthic 

communities in the immediate vicinity of the spill. Turbidity, sedimentation, and oiling would be

heaviest closest to the source, and decrease with distance from the source. Complete loss of benthic 

populations may occur with heavy sedimentation and oil deposition. Farther from the well, a less thick 

layer of sediment would be deposited and oil would be dispersed from the source, resulting in sublethal 

impacts. The recovery of benthic populations would begin with recruitment from surrounding areas fairly 

rapidly. 

A.3.1.11. Marine Mammals

Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout event. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and 

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1 or 2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. 

Potential impacts reflect the explosion, subsequent fire for 1-30 days, and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well. 

Depending on the type of blowout, the pressure waves and noise generated by the eruption of gases 

and fluids would likely be significant enough to harass, injure, or kill marine mammals, depending on the 

proximity of the animal to the blowout. A high concentration of response vessels could result in 

harassment or displacement of individuals and could place marine mammals at a greater risk of vessel 

collisions, which would likely cause fatal injuries.

The scenarios for each phase, including cleanup methods, can be found in Table A-4. 

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. Potential 

impacts reflect spill and response in Federal and State offshore waters. Season and temperature variations 

can result in different resource impacts due to variations in oil persistence and oil and dispersant toxicity 

and because of differences in potential exposure of the resources throughout various life cycle stages.

An oil spill and related spill-response activities can impact marine mammals that come into contact 

with oil and remediation efforts. The marine mammals’ exposure to hydrocarbons persisting in the sea 
Catastrophic Spill Event Analysis A-53

may result in sublethal impacts (e.g., decreased health, reproductive fitness, longevity, and increased 

vulnerability to disease), some soft tissue irritation, respiratory stress from inhalation of toxic fumes, food 

reduction or contamination, direct ingestion of oil and/or tar, and temporary displacement from preferred 

habitats or migration routes. More detail on the potential range of effects to marine mammals from 

contact with spilled oil can be found in Geraci and St. Aubin (1990). The best available information does 

not provide a complete understanding of the effects of the spilled oil and active response/cleanup 

activities on marine mammals. For example, it is expected that the large amount of chemical dispersants 

being used on the oil may act as an irritant on the marine mammals’ tissues and sensitive membranes.

The increased human presence after an oil spill (e.g., vessels) would likely add to changes in behavior 

and/or distribution, thereby potentially stressing marine mammals further and perhaps making them more 

vulnerable to various physiologic and toxic effects. In addition, the large number of response vessels 

could place marine mammals at a greater risk of vessel collisions, which could cause fatal injuries.

The potential biological removal (PBR) level is defined by the Marine Mammal Protection Act as the 

maximum number of animals, not including natural mortalities that may be removed from a marine 

mammal stock while allowing that stock to reach or maintain its optimum sustainable population. 

However, in the Gulf of Mexico, many marine mammal species have unknown PBRs or PBRs with 

outdated abundance estimates, which are considered undetermined. The biological significance of any 

injury or mortality would depend, in part, on the size and reproductive rates of the affected stocks, as well 

as the number, age, and size of the marine mammals affected.

The Deepwater Horizon explosion, oil spill, and response in Mississippi Canyon Block 252 

(including use of dispersants) have impacted marine mammals that have come into contact with oil and 

remediation efforts. According to the “Dolphins and Whales of the Gulf of Mexico Oil Spill” website, 

within the designated Deepwater Horizon explosion, oil spill, and response area, 171 marine mammals 

(89% of which were deceased) were reported. This includes 155 bottlenose dolphins, 2 Kogia spp., 

2 melon-headed whales, 6 spinner dolphins, 2 sperm whales, and 4 unknown species (USDOC, NMFS, 

2011b). All marine mammals collected either alive or dead were found east of the Louisiana/Texas 

border through Apalachicola, Florida. The highest concentration of strandings has occurred off eastern 

Louisiana, Mississippi, and Alabama, with a significantly lesser number off western Louisiana and 

western Florida (USDOC, NMFS, 2011b). Due to known low-detection rates of carcasses, it is possible

that the number of deaths of marine mammals is underestimated (Williams et al., 2011). It is also 

important to note that evaluations have not yet confirmed the cause of death, and it is possible that many, 

some, or no carcasses collected were related to the Deepwater Horizon explosion, oil spill, and response. 

These stranding numbers are significantly greater than reported in past years; though it should be further 

noted that stranding coverage (i.e., effort in collecting strategies) has increased considerably due to the 

Deepwater Horizon explosion, oil spill, and response. Further detail on this catastrophic OSRA run is 

contained in Appendix C of the WPA 238/246/248 Supplemental EIS. 

Phase 3—Onshore Contact

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response and oil initially reaching the shoreline during the spill event or while the oil still persists in the 

offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. Re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 

contacted shore. Potential impacts reflect the spill and response in very shallow coastal waters and once 

along the shoreline. Season and temperature variations can result in different resource impacts due to 

variations in oil persistence and oil and dispersant toxicity and because of differences in potential 

exposure of the resources throughout various life cycle stages.

A high-volume oil spill lasting 90 days could directly impact over 22 species of marine mammals. As 

a spill enters coastal waters, manatees and coastal and estuarine dolphins would be the most likely to be 

affected.

Manatees primarily inhabit open coastal (shallow nearshore) areas and estuaries, and they are also 

found far up in freshwater tributaries. Florida manatees have been divided into four distinct regional 

management units: the Atlantic Coast Unit that occupies the east coast of Florida, including the Florida 
A-54 Western Planning Area Lease Sale 248 Supplemental EIS

Keys and the lower St. Johns River north of Palatka, Florida; the Southwest Unit that occurs from Pasco 

County, Florida, south to Whitewater Bay in Monroe County, Florida; the Upper St. Johns River Unit that 

occurs in the river south of Palatka, Florida; and the Northwest Unit that occupies the Florida Panhandle 

south to Hernando County, Florida (Waring et al., 2012). Manatees from the Northwest Unit are more 

likely to be seen in the northern GOM, and they can be found as far west as Texas; however, most 

sightings are in the eastern GOM (Fertl et al., 2005).

During warmer months (June to September), manatees are common along the Gulf Coast of Florida 

from the Everglades National Park northward to the Suwannee River in northwestern Florida. Although 

manatees are less common farther westward, manatee sightings increase during the warmer summer 

months. Winter habitat use is primarily influenced by water temperature as animals congregate at natural 

(springs) and/or artificial (power plant outflows) warm water sources (Alves-Stanley et al., 2010). 

Manatees are infrequently found as far west as Texas (Powell and Rathbun, 1984; Rathbun et al., 1990; 

Schiro et al., 1998). If a catastrophic oil spill reached the Florida coast when manatees were in or near 

coastal waters, the spill could have population-level effects.

It is possible that manatees could occur in coastal areas where vessels traveling to and from the spill 

site could affect them. A manatee present where there is vessel traffic could be injured or killed by a 

vessel strike (Wright et al., 1995). Due to the large number of vessels responding to a catastrophic spill 

both in coastal waters and traveling through coastal waters to the offshore site, manatees would have an 

increased risk of collisions with boats. Vessel strikes are the primary cause of death of manatees.

The best available count of Florida manatees is 4,824 animals, based on a January 2014 aerial survey 

of warm water refuges (Florida Fish and Wildlife Conservation Commission, 2014a). By February 2014, 

there were 114 manatee carcasses collected in Florida, 20 of these animals died of human causes (Florida 

Fish and Wildlife Conservation Commission, 2014b). Human causes included water control structures, 

entanglement in and ingestion of marine debris, entrapment in pipes/culverts, and collisions with 

watercraft. Seventy percent of the manatees that died of human causes were killed by watercraft (Florida 

Fish and Wildlife Conservation Commission, 2014b). Therefore, if a catastrophic spill and response 

vessel traffic occurred near manatee habitats in the eastern Gulf of Mexico, population-level impacts 

could occur because the possibility exists for the number of mortalities to exceed the potential biological 

removal.

There have been no experimental studies and only a few observations suggesting that oil impacts have 

harmed any manatees (St. Aubin and Lounsbury, 1990). Types of impacts to manatees and dugongs from 

contact with oil include (1) asphyxiation because of inhalation of hydrocarbons, (2) acute poisoning 

because of contact with fresh oil, (3) lowering of tolerance to other stress because of the incorporation of 

sublethal amounts of petroleum components into body tissues, (4) nutritional stress through damage to 

food sources, and (5) inflammation or infection and difficulty eating because of oil sticking to the sensory 

hairs around their mouths (Preen, 1989, in Sadiq and McCain, 1993; Australian Maritime Safety 

Authority, 2003). For a population whose environment is already under great pressure, even a localized 

incident could be significant (St. Aubin and Lounsbury, 1990). Spilled oil might affect the quality or 

availability of aquatic vegetation, including seagrasses, upon which manatees feed.

Bottlenose dolphins were the most affected species of marine mammals from the Deepwater Horizon

explosion, oil spill, and response. Bottlenose dolphins can be found throughout coastal waters in the Gulf 

of Mexico. Like manatees, dolphins could be affected, possibly to population level, by a catastrophic oil 

spill if it reaches the coast (as well as affecting them in the open ocean), through direct contact, 

inhalation, ingestion, and stress, as well as through collisions with cleanup vessels.

Phase 4—Post-Spill, Long-Term Recovery and Response 

Phase 4 focuses on long-term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 

killed and cleanup activities are concluding. While it is assumed that the majority of spilled oil would be 

dissipated offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil 

has the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt 

marshes, oil may seep into the muddy bottoms. Potential impacts reflect long-term persistence of oil in 

the environment and residual and long-term, clean-up efforts.
Catastrophic Spill Event Analysis A-55

Even after the spill is stopped, oilings or deaths of marine mammals would still likely occur because 

of oil and dispersants persisting in the water, past marine mammal/oil or dispersant interactions, and 

ingestion of contaminated prey. The animals’ exposure to hydrocarbons persisting in the sea may result 

in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased 

vulnerability to disease) and some soft tissue irritation, respiratory stress from inhalation of toxic fumes, 

food reduction or contamination, direct ingestion of oil and/or tar, and temporary displacement from 

preferred habitats or migration routes. A catastrophic oil spill could lead to increased mortalities, 

resulting in potential population-level effects for some species/populations (USDOC, NMFS, 2010a). 

On December 13, 2010, NMFS declared an unusual mortality event (UME) for cetaceans (whales and 

dolphins) in the Gulf of Mexico. An UME is defined under the Marine Mammal Protect Act as a 

“stranding that is unexpected, involves a significant die-off of any marine mammal population, and 

demands immediate response.” Evidence of the UME was first noted by NMFS as early as February 1, 

2010, before the Deepwater Horizon explosion, oil spill, and response. The NMFS updates the number of 

marine mammals stranded as a result of the UME weekly; this information can be found on its website 

(USDOC, NMFS, 2015). As of April 12, 2015, a total of 1,370 cetaceans (6% stranded alive and 94% 

stranded dead) have stranded since the start of the UME, with a vast majority of these strandings between 

Franklin County, Florida, and the Louisiana/Texas border. After the initial response phase ended, there 

were nine dolphins killed during a fish-related scientific study and one dolphin killed incidental to trawl 

relocation for a dredging project. More detail on the UME can be found on NMFS’s website (USDOC, 

NMFS, 2014). 

On May 9, 2012, NOAA declared an UME for bottlenose dolphins in five Texas counties. The cause 

of this UME is unknown and cannot be attributed directly to the Deepwater Horizon explosion, oil spill, 

and response. The strandings were coincident with a harmful algal bloom of Karenia brevis that started 

in September 2011 in southern Texas, but researchers have not determined that was the cause of the 

event. The UME lasted from November 2011-March 2012, when 126 bottlenose dolphins stranded in 

Aransas, Calhoun, Kleberg, Galveston, and Brazoria Counties in Texas. Of the 126 animals stranded, 

only 4 were found alive. Preliminary findings included infection in the lung, poor body condition, 

discoloration of the teeth, and in four animals, a black/grey, thick mud-like substance in the stomachs was 

found. Currently, there are no red tide blooms occurring in the region, and stranding rates have returned 

to normal levels (USDOC, NMFS, 2013). 

Overall Summary and Conclusion (Phases 1-4) 

Accidental events related to a WPA proposed action have the potential to have adverse, but not 

significant impacts to marine mammal populations in the GOM. Accidental blowouts, oil spills, and 

spill-response activities may impact marine mammals in the GOM. 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.

A.3.1.12. Sea Turtles

Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout incident. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and 

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1-2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. 

Potential impacts reflect the explosion, subsequent fire for 1-30 days, and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well. 

Five species of sea turtles are found in the waters of the Gulf of Mexico: green, leatherback, 

hawksbill, Kemp’s ridley, and loggerhead. All species are protected under the Endangered Species Act 

(ESA), and all are listed as endangered except the loggerhead turtle, which is listed as threatened. 
A-56 Western Planning Area Lease Sale 248 Supplemental EIS

Depending on the type of blowout, an eruption of gases and fluids may generate significant pressure 

waves and noise that may harass, injure, or kill sea turtles, depending on their proximity to the accident. 

A high concentration of response vessels could place sea turtles at a greater risk of fatal injuries from 

vessel collisions. All sea turtle species and life stages are vulnerable to the harmful effects of oil through 

direct contact or by fouling of their habitats and prey.

Further, mitigation by burning puts turtles at risk because they tend to be gathered up in the corralling 

process necessary to concentrate the oil in preparation for the burning. Trained observers should be 

required during any mitigation efforts that include burning. The scenarios for each phase, including 

cleanup methods, can be found in Table A-4. 

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. Potential 

impacts reflect spill and response in Federal and State offshore waters. Season and temperature variations 

can result in different resource impacts due to variations in oil persistence and oil and dispersant toxicity 

and because of differences in potential exposure of the resources throughout various life cycle stages.

Sea turtles are more likely to be affected by a catastrophic spill in shallow water than in deep water 

because not all sea turtles occupy a deepwater habitat. For example, Kemp’s ridley sea turtles are 

unlikely to be in water depths of 160 ft (49 m) or greater. Hawksbill sea turtles are commonly associated 

with coral reefs, ledges, caves, rocky outcrops, and high energy shoals. Green sea turtles are commonly 

found in coastal benthic feeding grounds, although they may also be found in the convergence zones of 

the open ocean. Convergence zones are areas that also may collect oil. Leatherback sea turtles are 

commonly pelagic and are the sea turtle species most likely to be affected by a deepwater oil spill. As the 

spilled oil moves toward land, additional species of sea turtles are more likely to be affected.

The Deepwater Horizon explosion, oil spill, and response in Mississippi Canyon Block (including use 

of dispersants) have impacted sea turtles that have come into contact with oil and remediation efforts. For 

the latest available information on oiled or affected sea turtles documented in the area, refer to NMFS’s 

“Sea Turtles and the Gulf of Mexico Oil Spill” website (USDOC, NMFS, 2011c). 

According to this NMFS website, 1,146 sea turtles have been collected (537 alive, 609 deceased) as 

of February 15, 2011. Of these, 201 were greens, 16 hawksbills, 809 Kemp’s ridleys, 88 loggerheads, 

and the remaining 32 unknown (USDOC, NMFS, 2011c). Individuals were documented either through 

strandings or directed offshore captures. Due to low detection rates of carcasses in prior events, it is 

possible that the number of deaths of sea turtles is underestimated (Epperly et al., 1996). It is also 

important to note that evaluations have not yet confirmed the cause of death, and it is possible that not all 

carcasses were related to the Deepwater Horizon explosion, oil spill, and response. Over the last 2 years, 

NOAA has documented increased numbers of sea turtle strandings in the northern GOM. Many of the 

stranded turtles were reported from Mississippi and Alabama waters, and very few showed signs of 

external oiling (believed to be related to the Deepwater Horizon explosion, oil spill, and response). 

Necropsy results from many of the stranded turtles indicate mortality due to forced submergence, which is 

commonly associated with fishery interactions. In May 2012, NMFS published the Draft EIS to reduce 

incidental bycatch and mortality of sea turtles in the southeastern U.S. shrimp fishery (Federal Register, 

2012). Further detail on this catastrophic OSRA run is contained in Appendix C of the WPA 

238/246/248 Supplemental EIS.

The Ixtoc I well blowout and spill in the Bay of Campeche, Mexico, on June 3, 1979, resulted in the 

release of 500,000 metric tons (140 million gallons) of oil and the transport of this oil into the Gulf of 

Mexico (ERCO, 1982). Three million gallons of oil impacted Texas beaches (ERCO, 1982). According 

to the ERCO study, “Whether or not hypoxic conditions could, in fact, be responsible for areawide 

reductions in [invertebrate] faunal abundance is unclear, however.” Of the three sea turtles found dead in 

the U.S., all had petroleum hydrocarbons in the tissues examined, and there was selective elimination of 

portions of this oil, indicating chronic exposure (Hall et al., 1983). Therefore, the effects of the Ixtoc I

well blowout and spill on sea turtles in waters off Texas are still unknown.
Catastrophic Spill Event Analysis A-57

Phase 3—Onshore Contact

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response, and on oil initially reaching the shoreline during the spill event or while the oil still persists in 

the offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. The re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 

contacted shore. Potential impacts reflect the spill and response in very shallow coastal waters and once 

along the shoreline. Season and temperature variations can result in different resource impacts due to 

variations in oil persistence and oil and dispersant toxicity and because of differences in potential 

exposure of the resources throughout various life cycle stages.

Out of the five species of sea turtle that occur in the Gulf of Mexico, only four nest in the GOM. The 

largest nesting location for the Kemp’s ridley sea turtle is in Rancho Nuevo, Mexico, but they also nest in 

Texas and Alabama. Loggerhead sea turtles nest in all states around the Gulf of Mexico. Green sea 

turtles have been cited nesting in Texas, Alabama, and Florida. Leatherback sea turtles mostly nest on the 

east coast of Florida but are recorded in Texas. Kemp’s ridley, loggerhead, and green sea turtles are 

therefore most likely to be affected by a catastrophic oil spill when there is onshore and/or offshore 

contact. 

Several recent reports are available concerning Gulf of Mexico loggerheads’ nesting habitats and 

movements (Hart et al., 2013), post-nesting behavior (Foley et al., 2013), foraging sites (Foley et al., 

2014), and body size effects on growth rates (Bjorndal et al., 2013). These reports confirm the 

importance of Gulf of Mexico beaches, specifically for loggerheads. On September 22, 2011, NMFS 

issued the final rule to list nine Distinct Population Segments (DPSs) of loggerhead sea turtles under the 

ESA and designated the GOM as the Northwest Atlantic Ocean DPS (Federal Register, 2011).

Female sea turtles seasonally emerge during the warmer summer months to nest on beaches. 

Thousands of sea turtles nest along the Gulf Coast, and turtles could build nests on oiled beaches. Nests 

could also be disturbed or destroyed by cleanup efforts. Untended booms could wash ashore and become 

a barrier to sea turtle adults and hatchlings (USDOC, NOAA, 2010c). Hatchlings, with a naturally high 

mortality rate, could traverse the beach through oiled sand and swim through oiled water to reach 

preferred habitats of Sargassum floats. Response efforts could include mass movement of eggs from 

hundreds of nests or thousands of hatchlings from Gulf Coast beaches to the east coast of Florida or to the 

open ocean to prevent hatchlings entering oiled waters (Jernelöv and Lindén, 1981; USDOI, FWS, 

2010b). Due to poorly understood mechanisms that guide female sea turtles back to the beaches where 

they hatched, it is uncertain if relocated hatchlings would eventually return to the Gulf Coast to nest 

(Florida Fish and Wildlife Conservation Commission, 2010). Therefore, shoreline oiling and response 

efforts may affect future population levels and reproduction (USDOI, NPS, 2010). Sea turtle hatchling 

exposure to, fouling by, or consumption of tarballs persisting in the sea following the dispersal of an oil 

slick would likely be fatal. 

As a preventative measure during the Deepwater Horizon explosion, oil spill, and response, NMFS 

and FWS translocated a number of sea turtle nests and eggs that were located on beaches affected or 

potentially affected by spilled oil. The NMFS stranding network website (USDOC, NMFS, 2011c) 

translocated a total of 274 nests from GOM beaches to the east coast of Florida. These nests were mainly 

for hatchlings that would enter waters off Alabama and Florida’s northwest Gulf Coast. Of these, 4 were 

from green turtles, 5 from Kemp’s ridley, and 265 were loggerheads. The translocation effort ended 

August 19, 2010, at the time when biologists determined that risks to hatchlings emerging from beaches 

and entering waters off Alabama and Florida’s northwest Gulf Coast had diminished significantly and that 

the risks of translocating nests during late incubation to the east coast of Florida outweighed the risks of 

letting hatchlings emerge into the Gulf of Mexico. The hatchlings resulting from the translocations were 

all released as of September 9, 2010.

In addition to the impacts from direct contact with hydrocarbons, spill-response activities could 

adversely affect sea turtle habitat and cause displacement from suitable habitat to inadequate areas. 

Factors that could have an effect might include artificial lighting from night operations, booms, machine 

and human activity, equipment on beaches and in intertidal areas, sand removal and cleaning, and 

changed beach landscape and composition. Some of the resulting impacts from cleanup could include 
A-58 Western Planning Area Lease Sale 248 Supplemental EIS

interrupted or deterred nesting behavior, crushed nests, entanglement in booms, and increased mortality of 

hatchlings because of predation during the increased time required to reach the water (Newell, 1995; 

Lutcavage et al., 1997). The strategy for cleanup operations should vary, depending on the season. 

Phase 4—Post-Spill, Long-Term Recovery and Response 

Phase 4 focuses on long-term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 

killed and that cleanup activities are concluding. While it is assumed that the majority of spilled oil 

would be dissipated offshore within 1-2 months (depending on season and temperature) of stopping the 

flow, oil has the potential to persist in the environment long after a spill event and has been detected in 

sediment 30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and 

salt marshes, oil may seep into the muddy bottoms. Potential impacts reflect long-term persistence of oil 

in the environment and residual and long-term cleanup efforts.

Sea turtles take many years to reach sexual maturity. Green sea turtles reach maturity between 20 and 

50 years of age; loggerheads may be 35 years old before they are able to reproduce; and hawksbill sea 

turtles typically reach lengths of 27 in (69 cm) for males and 31 in (79 cm) for females before they can 

reproduce (USDOC, NMFS, 2010a). Declines in the food supply for sea turtles, which include 

invertebrates and sponge populations, could also affect sea turtle populations. While all of the pathways 

for an oil spill or the use of dispersants to affect sea turtles are poorly understood, some pathways may 

include the following: (1) oil or dispersants on the sea turtle’s skin and body can cause skin irritation, 

chemical burns, and infections; (2) inhalation of volatile petroleum compounds or dispersants can damage 

the respiratory tract and lead to diseases; (3) ingesting oil or dispersants may cause injury to the 

gastrointestinal tract; and (4) chemicals that are inhaled or ingested may damage internal organs. In most 

foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick 

would result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity and increased 

vulnerability to disease) to sea turtles. Other possible internal impacts might include harm to the liver, 

kidney, and brain function, as well as causing anemia and immune suppression, or they could lead to 

reproductive failure or death. The deaths of subadult and adult sea turtles may also drastically reduce the 

population. 

Since January 1, 2011, a notable increase in sea turtle strandings has occurred in the northern GOM, 

primarily in Mississippi. While turtle strandings in this region typically increase in the spring, the recent 

increase is a cause for concern. The Sea Turtle Stranding and Salvage Network is monitoring and 

investigating this increase. The network encompasses the coastal areas of the 18 states from Maine 

through Texas and includes portions of the U.S. Caribbean. There are many possible reasons for the 

increase in strandings in the northern GOM, both natural and human caused (USDOC, NMFS, 2012a). 

One sea turtle had a small amount of tar from the Deepwater Horizon explosion, oil spill, and response on 

its shell. No visible external or internal oil was observed in any other animals. These sea turtle species 

include loggerhead, green, Kemp’s ridley, leatherback, hawksbill, and unidentified. The NMFS has also 

identified strandings in Texas (upper Texas coast—Zone 18). Refer to Chapter 4.1.1.12 for updated 

turtle stranding data for the Gulf of Mexico. 

Over the last 2 years, NOAA has documented necropsy results from many of the stranded turtles, 

indicating mortality due to forced submergence, which is commonly associated with fishery interactions, 

and acute toxicosis. On May 10, 2012, NMFS published the Draft EIS to reduce incidental bycatch and 

mortality of sea turtles in the southeastern U.S. shrimp fishery (Federal Register, 2012). 

Overall Summary and Conclusion (Phases 1-4) 

Accidental blowouts, oil spills, and spill-response activities resulting from a WPA proposed action 

have the potential to impact small to large numbers of sea turtles in the GOM, depending on the 

magnitude and frequency of accidents, the ability to respond to accidents, the location and date of 

accidents, and various meteorological and hydrological factors. Impacts on sea turtles from smaller 

accidental events are likely to affect individual sea turtles in the spill area, but they are unlikely to rise to 

the level of population effects (or significance) given the size and scope of such spills.
Catastrophic Spill Event Analysis A-59

Unavailable information on the effects to sea turtles from the Deepwater Horizon explosion, oil spill, 

and response and increased stranding events (and thus changes to the sea turtle baseline in the affected 

environment) make an understanding of the effects less clear.

For low-probability catastrophic spills, this analysis concludes that there is a potential for a lowprobability catastrophic event to result in significant, population-level effects on affected sea turtle 

species.

A.3.1.13. Diamondback Terrapins

Phase1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout event. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and 

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1-2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. 

Potential impacts reflect the explosion, subsequent fire for 1-30 days and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well. 

The scenarios for each phase, including cleanup methods, can be found in Table A-4. 

There would likely be no adverse impacts to diamondback terrapins as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event 

because these species exclusively inhabit estuarine waters and salt marshes. 

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. Potential 

impacts reflect spill and response in Federal and State offshore waters. Season and temperature variations 

can result in different resource impacts due to variations in oil persistence and oil and dispersant toxicity 

and because of differences in potential exposure of the resources throughout various life cycle stages.

There would likely be no adverse impacts to diamondback terrapins as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 2 of a catastrophic spill event 

because these species exclusively inhabit estuarine waters and salt marshes. 

Phase 3—Onshore Contact

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response and on oil initially reaching the shoreline during the spill event or while the oil still persists in 

the offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. The re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 

contacted shore. Potential impacts reflect the spill and response in very shallow coastal waters and once 

along the shoreline. Season and temperature variations can result in different resource impacts due to 

variations in oil persistence and oil and dispersant toxicity and because of differences in the potential 

exposure of the resources throughout various life cycle stages.

The major impact-producing factors resulting from the low-probability catastrophic event that may 

affect the five terrapin subspecies that occur in the WPA and CPA include offshore and coastal oil spills 

and spill-response activities.

Terrapins inhabit brackish waters including coastal marshes, tidal flats, creeks, and lagoons behind 

barrier beaches (Hogan, 2003). Their diet consists of fish, snails, worms, clams, crabs, and marsh plants 
A-60 Western Planning Area Lease Sale 248 Supplemental EIS

(Cagle, 1952). Courtship and mating occur in March and April, and the nesting season extends through 

July, with possibly multiple clutches (U.S. Dept. of the Army, COE, 2002; Butler et al., 2006). Terrapins 

nest on dunes, beaches, sandy edges of marshes, islands, and dike roads (Roosenburg, 1994). The 

common factor for proper egg development is sandy soil, which does not clog eggshell pores, thus 

allowing sufficient gas exchange between the developing embryo and the environment (Roosenburg, 

1994). Nesting occurs primarily in the daytime during high tide on high sand dunes with gentle slopes 

and minimal vegetation (Burger, 1977). Clutch size ranges from 4 to 22 eggs, and incubation time ranges 

from 61 to 104 days (Butler et al., 2006; Burger, 1977). Female terrapins may nest 2-3 times in the same 

nesting season. Gender determination is temperature dependent. Hatching occurs from July through 

October in northeastern Florida (Butler et al., 2004). 

Spending most of their lives at the aquatic-terrestrial boundary in estuaries, terrapins are susceptible 

to habitat destruction from oil-spill cleanup efforts as well as direct contact with oil. However, most 

impacts cannot be quantified at this time. Even after oil is no longer visible, terrapins may still be 

exposed while they forage in the salt marshes lining the edges of estuaries, where oil may have 

accumulated under the sediments and within the food chain. Terrapin nests can also be disturbed or 

destroyed by cleanup efforts. The range of the possible chronic effects from contact with oil and 

dispersants include lethal or sublethal oil-related injuries that may include skin irritation from the oil or 

dispersants, respiratory problems from the inhalation of volatile petroleum compounds or dispersants, 

gastrointestinal problems caused by the ingestion of oil or dispersants, and damage to other organs 

because of the ingestion or inhalation of these chemicals.

Accidental blowouts, oil spills, and spill-response activities resulting from a WPA proposed action 

have the potential to impact small to large numbers of terrapins within their habitat, depending on the 

magnitude and frequency of accidents, the ability to respond to accidents, the location and date of 

accidents, and various meteorological and hydrological factors. Populations of terrapins in the Gulf may 

be exposed to residuals of oils spilled as a result of a WPA proposed action during their lifetimes. 

Chronic or acute exposure may result in the harassment, harm, or mortality to terrapins occurring in the 

GOM. In the most likely scenarios, exposure to hydrocarbons persisting within the wetlands following 

the dispersal of an oil slick could result in sublethal impacts (e.g., decreased health, reproductive fitness, 

and longevity; and increased vulnerability to disease). Terrapin hatchling exposure to, fouling by, or 

consumption of tarballs persisting inland following the dispersal of an oil slick could likely be fatal but 

unlikely. Impacts from the dispersants are unknown, but they may have similar irritants to tissues and 

sensitive membranes as are known to occur in seabirds and sea turtles (NRC, 2005). The impacts to 

diamondback terrapins from chemical dispersants could include nonlethal injury (e.g., tissue irritation and 

inhalation), long-term exposure through bioaccumulation, and potential shifts in distribution from some 

habitats. 

Burger (1994) described the behavior of 11 female diamondback terrapins that were oiled during the 

January 1990 spill of No. 2 fuel oil in Arthur Kill, New York. The terrapins were hibernating at the time 

of the spill, and when they emerged from hibernation, they were found to be oiled. The terrapins voided 

oil from their digestive tracks for 2 weeks in rehabilitation. At 3 weeks, the terrapins scored low on 

strength tests and were slow to right themselves when placed on their backs. At 4 weeks, they developed 

edema and appetite suppression. Eight of the 11 died; these animals had traces of oil in their tissues and 

exhibited lesions in their digestive tract consistent with oil exposure (Burger, 1994). Further detail on this 

catastrophic OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental EIS. 

The Deepwater Horizon explosion, oil spill, and response may have potentially impacted the terrapin 

community. Impacts from a catastrophic spill may impact terrapin communities. Impacts can be either 

direct (mortality or injury) or indirect (e.g., reduced prey availability); however, most impacts cannot be 

quantified at this time. The best available information does not provide a complete understanding of the 

effects of the spilled oil and active response/cleanup activities on the potentially affected terrapin 

environment. Current available information includes photographic evidence of one terrapin found oiled

on Grand Terre Island, Louisiana, on June 8, 2010 (State of Louisiana, Coastal Protection and 

Restoration, 2012). 

Phase 4—Post-Spill, Long-Term Recovery and Response 

Phase 4 focuses on long-term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 
Catastrophic Spill Event Analysis A-61

killed and cleanup activities are concluding. While it is assumed that the majority of spilled oil would be 

dissipated offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil 

has the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt 

marshes, oil may seep into the muddy bottoms. Potential impacts reflect long-term persistence of oil in 

the environment and residual and long-term cleanup efforts.

The Deepwater Horizon explosion, oil spill, and response and associated oil spill may have impacted 

the terrapin community and associated brackish habitats. According to OSAT-2 (2011), possible 

environmental effects from the Deepwater Horizon explosion, oil spill, and response could occur within 

terrapin marsh habitat via food or to nesting habitat since no active intervention (natural remediation) is 

the preferred protocol.

Behavioral effects and nonfatal exposure to or intake of OCS oil- and gas-related contaminants or 

discarded debris may stress and/or weaken individuals of a local group or population and predispose them 

to infection from natural or anthropogenic sources. Even after the oil is no longer visible, terrapins may 

still be exposed while they forage in the salt marshes lining the edges of estuaries where oil may have 

accumulated under the sediments and within the food chain (Burger, 1994; Roosenburg et al., 1999). 

Nests can also be disturbed or destroyed by cleanup efforts. Through NRDA, ongoing research and 

analysis of the presence of contaminants in terrapin eggs following the Deepwater Horizon oil spill are 

being conducted (USDOC, NOAA, 2012a). Hatching success studies at various oiled nesting sites of the 

northern diamondback terrapin suggest that spills may result in a reduction in nest size and increased 

mortality of spring emergers (hatched turtles) at the oiled sites (Wood and Hales, 2001). However, 

research on the PAH exposure and toxicology of eggs in the vicinity of a spill site found no correlation to 

substrate PAHs when compared with egg toxicology. The level of PAHs found in the eggs may be the 

result of maternal transfer and represent the exposure level of the nesting female rather than 

environmental exposure to PAHs from oil at the site of the nest (Holliday et al., 2008). 

Habitat destruction, road construction, drowning in crab traps, and nest predation are the most recent 

threats to diamondback terrapins. Tropical storms, hurricanes, and beach erosion threaten their preferred 

nesting habitats. Destruction of the remaining habitat because of a catastrophic spill and response efforts 

could drastically affect future population levels and reproduction. 

Overall Summary and Conclusion (Phases 1-4) 

Impacts on diamondback terrapins from smaller accidental events are likely to affect individual 

diamondback terrapins in the spill area, as described above, but are unlikely to rise to the level of 

population effects (or significance) given the probable size and scope of such spills. Possible catastrophic 

environmental effects from an oil spill and cleanup could occur within terrapin marsh habitat via food or 

to the nesting habitat. Since terrapins do not move far from where they are hatched, it is possible that 

entire subpopulations could incur high mortality rates and community disruptions, though this would be 

highly localized depending on the time, place, and size of the spill. 

The OSRA analyses in this Supplemental EIS conclude that there is a low probability for catastrophic 

spills but that there is a potential for a low-probability catastrophic event to result in significant, 

population-level effects on affected diamondback terrapin species. However, it is unlikely that a 

catastrophic event would result in significant impacts due to the distance of most terrapin habitat from 

offshore OCS energy-related activities.

A.3.1.14. Coastal, Marine, and Migratory Birds

Phase 1—Initial Event

Some migratory birds use offshore platforms or rigs as potential stopover sites during their longdistance migrations across the GOM during the spring and fall (Russell, 2005). In addition, it has been 

well documented that seabirds are attracted to offshore platforms and rigs for a myriad of reasons; i.e., 

concentrations of baitfish, roost sites, etc. (Tasker et al., 1986; Wiese et al., 2001; Burke et al., 2012). 

The numbers of birds present at a platform or rig tend to be greater on platforms or rigs closer to shore, 

particularly during drilling operations (Baird, 1990). Birds resting on the drilling rig or platform during a 

catastrophic blowout at the surface (similar to the Deepwater Horizon explosion, oil spill, and response) 

are more likely to be killed by the explosion. While it is assumed that most birds in trans-Gulf migration 
A-62 Western Planning Area Lease Sale 248 Supplemental EIS

would likely avoid the fire and smoke plume during the day, it is possible that the light from the fire could 

interfere with nocturnal migration, especially during poor visibility conditions, i.e., fog or low clouds. It 

has been documented that seabirds are attracted to natural gas flares at rigs and platforms (Russell, 2005; 

Wiese et al., 2001); therefore, additional bird fatalities could result from the fire following the blowout. 

Though different species migrate differentially throughout the year, the largest number of species 

migrates through the proposed area from mid-April through mid-May (spring migration back north) and 

from mid-August through early November (fall migration south) (Russell, 2005, Table 6.12; Farnsworth 

and Russell, 2007). A blowout during this time would potentially result in a greater number of bird 

fatalities (see below).

Of the four phases considered herein, avian mortality associated with this Phase is certainly expected 

to be much lower than avian mortality associated with either Phase 2 or Phase 3. However, this 

anticipated result is highly dependent on the location of the platform and the timing of the event. The 

only scenario considered is the case where a blowout and explosion occurred at the surface (Table A-4). 

If the catastrophic event, in this case a blowout and explosion at the surface (refer to Table A-4), occurs 

more proximal to the coast during the breeding season or during a peak migration period (late March to 

late May and mid-August to early November), then the level of avian mortality is expected to be higher. 

In comparison, a blowout and explosion at the surface on a platform more distant from the coast (greater 

than or equal to the distance of the Macondo well from the coast) would result in much lower avian 

mortality, particularly if the event did not overlap temporally with either the breeding season or either of 

the trans-Gulf migrations.

While the species composition and species-specific mortality estimates are unknown and would be 

dependent on the blowout location and time of year, the initial mortalities would almost certainly not 

result in population-level impacts for species present at the time of the blowout and resulting fire (Arnold 

and Zink, 2011; also refer to Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS). If the event occurred 

during the breeding season or wintering period, species of seabirds or diving birds would have the 

greatest potential to be affected, whereas if the event occurred during either the spring or fall migration, 

species of passerines would most likely have the greatest potential to be affected due to the diversity and 

sheer numbers of individuals in this avian species group (Rappole and Ramos, 1994; Lincoln et al., 1998; 

Russell, 2005; also refer to Chapter 4.1.1.14 of this Supplemental EIS, Chapter 4.1.1.14.1 of the 2012-

2017 WPA/CPA Multisale EIS, and Chapter 4.1.1.14 of the WPA 233/CPA 231 Supplemental EIS). 

Phase 2—Offshore Spill

During Phase 2 of a catastrophic spill, the primary concern for marine and migratory birds would be 

their vulnerability to oiling or ingesting oil, which is primarily a function of their behavior and diets. 

Wading birds (e.g., herons, egrets, etc.) and species that feed by plunge-diving into the water to catch 

small fish (e.g., pelicans, gannets, terns, gulls, and pelagic birds) and those that use water as a primary 

means of locomotion, foraging (e.g., black skimmers), or resting and preening (e.g., diving ducks, 

cormorants, pelicans, etc.) are highly vulnerable to becoming oiled and also to ingesting oil (Table A-5 of 

this Supplemental EIS; also refer to Table 4-13 and Figure 4-13 of the 2012-2017 WPA/CPA Multisale 

EIS). Seabirds, in particular, tend to feed and concentrate in convergence zones, eddies, upwellings, and 

near Sargassum mats (Haney, 1986a-c; Moser and Lee, 2012). In addition to concentrating prey, these 

areas are also known to aggregate oil (Unified Incident Command, 2010d). Oiling interferes with the 

birds’ ability to fly (thus to obtain food) and compromises the insulative characteristics of down and 

contour feathers, making it difficult to regulate body temperature. Attempts by oiled birds to remove the 

oil via preening can cause them to ingest oil and may result in mortality. In addition, the ingestion of 

contaminated prey can result in physiological impairment and even death. Refer to Chapter 4.1.1.14.3 of 

the 2012-2017 WPA/CPA Multisale EIS for additional detailed information on oiling effects to birds.

Though several species or species groups are mentioned above, the most vulnerable species to spilled 

oil in the offshore environment in the GOM during Phase 2 would be representatives of the diving bird 

(≤10 species) and seabird (≥20 species) groups (King and Sanger, 1979; Ribic et al., 1997; Davis et al., 

2000). Unlike Phase 1, where passerines may be affected depending on the timing of the catastrophic 

event, timing or seasonal effects would be less important under the Phase 2 scenario (Table A-4) due to 

the spilled oil being restricted to the offshore environment, thereby limiting the potential impacts to the 

several avian species groups relegated to the coastal and nearshore environment (Table A-5 of this 

Supplemental EIS; also refer to Chapter 4.1.1.14 of this Supplemental EIS, Chapter 4.1.1.14.1 of the 
Catastrophic Spill Event Analysis A-63

2012-2017 WPA/CPA Multisale EIS, and Chapter 4.1.1.14 of the WPA 233/CPA 231 Supplemental EIS). 

However, it is highly probable that representative species of diving birds and seabirds would differentially 

be impacted (Table A-5 of this Supplemental EIS; also refer to Table 4-12 of the 2012-2017 WPA/CPA 

Multisale EIS). Table 4-12 of the 2012-2017 WPA/CPA Multisale EIS shows the actual number of birds 

identified to the species level for each of the species groups. This number is fairly representative of the 

suite of species available to be oiled. However, this number is dependent on efforts to correctly assign 

species to unidentified birds or unknowns, which is also a function of search effort. Search effort likely 

declined dramatically once the Macondo well was plugged/capped. The species composition and speciesspecific mortality estimates associated with a Phase 2 catastrophic event are unknown and would be 

dependent primarily on the blowout location, as well as the distribution, coverage, and proximity to the 

shoreline of spilled oil. Overall, avian mortalities for this Phase would probably not result in populationlevel impacts for species present at the time of the blowout (refer to Table A-5 of this Supplemental EIS 

and to Figure 4-13 of the 2012-2017 WPA/CPA Multisale EIS). However, it should be clear that many 

species of seabirds and diving birds have life-history strategies that do not allow subpopulations to 

recover quickly from major mortality events or perturbations (Ricklefs, 1983 and 1990; Russell, 1999; 

Saether et al., 2004; also refer to Table 4-13 and Figure 4-18 of the 2012-2017 WPA/CPA Multisale EIS). 

Some discussion of available information provided from the Deepwater Horizon explosion, oil spill, 

and response is relevant here with respect to temporal aspects of oiled birds (Figure A-3). The first oiled 

bird (northern gannet, a seabird) recovered after the Macondo well event was collected just 10 days postblowout. While gannets breed in coastal colonies in the Canadian North Atlantic, the population, 

including a major concentration in the northern GOM, over-winters in the deeper waters of the offshore 

environment. Belanger et al. (2010) provided some interesting results relative to live versus dead birds 

collected based on the actual date each bird was collected. Interestingly, they documented a dramatic and 

statistically significant decline in the number of live birds collected after 110 days compared with live 

birds collected during the first 72 days. These authors also documented a dramatic and statistically 

significant increase in the number of dead birds collected after 110 days (Belanger et al., 2010, Figures 2 

and 3). As a temporal reference, oil reached the shoreline near Venice, Louisiana, approximately 10 days 

post-blowout, covering a distance of approximately 90 mi (145 km) (Oil Spill Commission, 2011; also 

refer to Chapter 4.2.1.3.1 of the 2012-2017 WPA/CPA Multisale EIS and Chapter 4.2.1.3 of the WPA 

233/CPA 231 Supplemental EIS) (Figure A-3). It should be understood that, for the Phase 2 scenario 

considered here, it is assumed that spilled oil will not contact the shoreline. 

Overall, avian mortality estimates are unknown and are difficult to predict given the uncertainty 

(Conroy et al., 2011, pages 1209-1210; Williams, 2011, page 1348) associated with the scenario and 

specific characteristics associated with the spill (refer to Appendix C of the WPA 238/246/248 

Supplemental EIS), as well as environmental conditions that are probably a function of spill location and 

timing. Even recognizing the uncertainty associated with the scenario, spill characteristics, and the 

environmental conditions at the time of the spill, Phase 2 would likely be second only to Phase 3 in total 

avian mortality. Phase 3 would include much greater avian species diversity and abundance due to the oil 

reaching nearshore, coastal beach/dune, salt- and brackish marsh habitats (Table A-5 of this 

Supplemental EIS; also refer to Table 4-12 of the 2012-2017 WPA/CPA Multisale EIS). 

Phase 3—Onshore Contact

Gulf coastal habitats are essential to the annual cycles of many species of breeding, wintering, and 

migrating diving birds, seabirds, shorebirds, passerines, marsh- and wading birds, and waterfowl (refer to 

Chapter 4.1.1.14 of this Supplemental EIS, Chapter 4.1.1.14.1 of the 2012-2017 WPA/CPA Multisale 

EIS, and Chapter 4.1.1.14 of the WPA 233/CPA 231 Supplemental EIS). For example, the northern Gulf 

Coast supports a large proportion of populations of several beach-nesting bird species (USDOI, FWS, 

2010c). During Phase 3, oil is expected to contact not only the beach but also other important habitats 

used by a diverse and abundant assemblage of avian species. Habitats potentially impacted by a 

catastrophic spill would also likely include the nearshore environment, as well as the salt- and brackish 

marsh habitats. Potential impacts and total avian mortality from Phase 3 would be greater than any of the 

other phases considered herein due to (1) avian diversity and abundance in the nearshore environment 

(Table A-5 of this Supplemental EIS; also refer to Tables 4-9 through 4-11 of the 2012-2017 WPA/CPA 

Multisale EIS) and (2) the dispersion of oil from a catastrophic spill, which would reach the shoreline and 

enter the salt- and brackish marsh environments. Similar to Phases 1 and 2, the timing and location of the 
A-64 Western Planning Area Lease Sale 248 Supplemental EIS

spill are important factors in determining the severity of impacts to the avian community. In addition, the 

duration of potential oil exposure to various species of birds would also be important. 

As the Macondo well blowout and spill is the only historic catastrophic oil spill to occur in U.S. 

waters in the GOM, the information obtained from the Deepwater Horizon explosion, oil spill, and 

response relative to avian mortality may be reasonably relevant for any future catastrophic spills, 

recognizing of course the variation and uncertainty associated with individual oil spills. At present, the 

estimates of avian mortality associated with the Exxon Valdez oil spill far exceed current estimates of 

avian mortality associated with the Deepwater Horizon explosion, oil spill, and response even though the 

Deepwater Horizon spill volume/size far exceed those of the Exxon Valdez (refer to Table 4-15 of the 

2012-2017 WPA/CPA Multisale EIS). Based on data from the Deepwater Horizon explosion, oil spill, 

and response, a similar catastrophic spill would probably result in >10,000 carcasses collected 

(Deepwater Horizon explosion, oil spill, and response = 7,258 collected) representing >100 potentially 

impacted species (Deepwater Horizon explosion, oil spill, and response = 104 species identified) (refer to 

Table A-5, superscript 1 and also superscript b). It should be recognized that the number of avian 

carcasses collected post-spill represents some unknown fraction or proportion of the total modeled 

estimate of realized mortality (Flint et al., 1999; Byrd et al., 2009; Ford and Zafonte, 2009); the number 

of avian carcasses collected is biased low (Piatt et al., 1990a-b; Piatt and Ford, 1996; Castège et al., 

2007). Figure 4-13 of the 2012-2017 WPA/CPA Multisale EIS should provide reasonable estimates of 

oiling rates for the seven avian species groups in the northern Gulf of Mexico if another catastrophic spill 

were to occur and the timing, oil spill characteristics, and spill behavior were similar to the Deepwater 

Horizon explosion, oil spill, and response. It should be noted that the top five most impacted (based on 

number collected) avian species from the Deepwater Horizon explosion, oil spill, and response were all 

representatives of the seabird group: laughing gull (n = 2,981, 40% oiling rate); brown pelican (n = 826, 

41% oiling rate); northern gannet (n = 475, 63% oiling rate); royal tern (n = 289, 52% oiling rate); and 

black skimmer (n = 253, 22% oiling rate) (Table A-5 of this Supplemental EIS and Figure 4-13 of the 

2012-2017 WPA/CPA Multisale EIS).

Additional information is provided herein from an OSRA catastrophic oil-spill analysis (refer to 

Appendix C of the WPA 238/246/248 Supplemental EIS, Tables C-4 and C-5). 

It should be noted that oil from the Deepwater Horizon explosion and oil spill reached the shoreline 

less than 14 days after the blowout occurred (Oil Spill Commission, 2011). The OSRA does not take into 

account or consider the following with respect to avian resources and their habitats: (1) species-specific 

densities; (2) species-specific habitat preferences, food habits, or behavior; (3) relative vulnerabilities to 

oiling among the avian species groups or among species within each of the groups (Table A-5 of this 

Supplemental EIS and Figure 4-13 of the 2012-2017 WPA/CPA Multisale EIS; also refer to Williams 

et al., 1995; Camphuysen, 2006); and (4) it does not take into account or consider species-specific lifehistory strategies, their demography, or a species’ recovery potential (refer to Table 4-13 and Figures 4-18 

and 4-19 of the 2012-2017 WPA/CPA Multisale EIS).

In summary, Phase 3 of a catastrophic oil spill has the greatest potential for negative impacts (i.e., 

direct mortality) to avian resources due to its contact with the shoreline and inundation of other habitats 

occupied by a much greater diversity and abundance of birds, particularly during the breeding season. 

Avian mortality estimates are presently unknown and are difficult to predict with any level of precision 

given the uncertainty associated with the scenario, specific characteristics associated with the spill, spatial 

and temporal variation in environmental conditions, and recognition that the avian resources (both species 

diversity and abundance) available to be oiled will also vary temporally and spatially. A worst-case 

scenario in the event of a catastrophic oil spill that reached the nearshore environment would occur in the 

presence of a hurricane with strength or magnitude similar to Hurricanes Katrina, Rita, or Ike during the 

breeding season. Such an overlap of two low-probability events during the breeding season could 

potentially push spilled oil even farther inland and also distribute oil vertically into the vegetation. Such 

an event would not only negatively impact diving birds, seabirds, shorebirds, marsh- and wading birds, 

and waterfowl but also the more terrestrial avian species groups including passerines and raptors. Such 

effects would most likely be long-term (due to direct mortality of individuals, but also due to major 

habitat loss) and could potentially result in population-level impacts to a number of avian species. 

Threatened and endangered avian species would likely be the most severely impacted by such an event 

depending on the spatial and temporal aspects of both the spill and the hurricane. 
Catastrophic Spill Event Analysis A-65

Endangered and Threatened Birds 

A detailed discussion of threatened and endangered species is provided in Chapter 4.1.1.14.1 of the 

2012-2017 WPA/CPA Multisale EIS. Of the 17 species considered, 12 species are known to occur in the 

WPA (Table A-6). However, only the piping plover (Charadrius melodus), roseate tern (Sterna dougallii 

dougallii), wood stork (Mycteria americana), whooping crane (Grus americana), Mississippi sandhill 

crane (Grus canadensis pulla), bald eagle (Haliaeetus leucocephalus), eastern brown pelican (Pelecanus 

occidentalis), and red knot (Calidris canutus rufa) were analyzed and are considered further here. 

Phase 3 would likely result in the greatest net negative impacts (primarily direct mortality) to threatened 

and endangered avian species due to contact with the shoreline and potential movement of spilled oil 

inland to other habitats during this phase (Table A-4). In addition, the presence of spilled oil would 

result in indirect and potentially long-term effects to threatened and endangered avian species’ habitats 

and their preferred foods. Phases 1 and 2 would likely result in very limited impacts, if any, due to the 

scenarios as defined with oil restricted to the offshore environment. 

In general, the potential direct impact (i.e., mortality) to any or all of these threatened or endangered 

(including recently delisted and candidate) species is directly a function of their presence at the time of a 

catastrophic oil spill. Indirect effects from a catastrophic oil spill could negatively affect the quality and 

functional availability of their habitats and the availability, distribution, and energetic benefits of their 

preferred foods in the absence of a given species. Of the species listed, the wood stork, Mississippi 

sandhill crane, bald eagle, eastern brown pelican, and Cape Sable seaside sparrows are year-round 

residents, whereas the piping plover, roseate tern, whooping crane, and red knot represent either wintering 

species or transients that utilize coastal habitats in the GOM as staging areas during migration. There are 

“resident” whooping cranes considered as “nonessential, experimental flocks” within the Gulf Coast 

States of Alabama, Louisiana, Mississippi, and Florida. These birds would be considered as “resident,” 

whereas the component of the ESA-listed species occurring primarily as a wintering flock in Texas (i.e., 

the Aransas National Wildlife Refuge) is considered a migratory flock. It is important to recognize these 

differences relative to whether or not individuals of a given species would be present and available to be 

oiled should a catastrophic oil spill event occur. Similarly, species-specific differences in habitat use and 

behavior would further separate which species would be most vulnerable to a spill given the timing of the 

spill, spill distribution, and other spill-related characteristics.

Of the species considered, probably only the eastern brown pelican and possibly the bald eagle 

(ingestion of contaminated fish and birds) would potentially be impacted during Phases 1 and 2. The 

other species are restricted to the nearshore, coastal, salt- and brackish, and upland habitats, which would 

not be impacted during these phases given the scenario (Table A-4). Phase 4 impacts to threatened and 

endangered avian species would probably be limited to short-term disturbance-related effects and 

potential impacts to habitats including destruction, alteration, or fragmentation from associated recovery 

activities (American Bird Conservancy, 2010; National Audubon Society, Inc., 2010). 

As the Macondo well blowout and spill is the only historic catastrophic oil spill to occur in U.S. 

waters in the GOM, the information obtained from the Deepwater Horizon explosion, oil spill, and 

response relative to avian mortality may be reasonably relevant for any future catastrophic spills, 

recognizing of course the variation and uncertainty associated with individual oil spills. Of the threatened 

and endangered avian species considered, only a single, unoiled piping plover was collected as part of the 

post-Deepwater Horizon explosion, oil spill, and response monitoring program (Table A-5). There were 

106 least terns (Sterna antillarum) collected (n = 106, 46% oiling rate), but these individuals were 

considered as members of the coastal breeding population and not the ESA-listed population (Interior or 

noncoastal population). Of the species considered, only the eastern brown pelican was impacted by the 

Deepwater Horizon explosion, oil spill, and response (n = 826, 41% oiling rate); this species was delisted 

on November 17, 2009 (Federal Register, 2009). No other carcasses of threatened and endangered 

species were collected as part of the post-Deepwater Horizon explosion, oil spill, and response

monitoring efforts (Table A-5; USDOI, FWS, 2011a). 

Additional information is provided herein from an OSRA catastrophic oil-spill analysis (refer to 

Appendix C of the WPA 238/246/248 Supplemental EIS, Tables C-4 and C-5). 

Caveats regarding the OSRA catastrophic run with respect to avian resources were addressed above 

and would also apply to threatened and endangered avian resources considered here.
A-66 Western Planning Area Lease Sale 248 Supplemental EIS

Phase 4—Post-Spill, Long-Term Recovery and Response 

There is a high probability of underestimating the impacts of oil spills on avian species potentially 

encountering oil. Despite being oiled, some birds are capable of flight and may later succumb to the 

oiling for a myriad of reasons (refer to Chapter 4.1.1.14 of the 2012-2017 WPA/CPA Multisale EIS for 

additional detailed information). Often overlooked and understudied are the long-term, sublethal, chronic 

effects due to sublethal exposure to oil (Butler et al., 1988; Alonso-Alvarez et al., 2007; Pérez et al., 

2010). Also, individuals having been oiled in the Gulf of Mexico as the result of a catastrophic oil spill 

during the overwinter period or while staging in the GOM could exhibit carry-over effects to the northern 

breeding grounds. Affected individuals in poor body condition may arrive at their breeding grounds later 

than nonaffected individuals, which could, in turn, negatively affect habitat-use decisions, territory 

establishment, pairing success, and ultimately lead to reduced reproductive success (Norris, 2005; Norris 

et al., 2006; Harrison et al., 2011). Some oiled individuals may forego breeding altogether (Zabala et al., 

2010). If oil-affected, long-distance migrants represent important prey items for various species of 

raptors, then the ingestion of affected individuals could also negatively affect individual birds of prey 

(Zuberogoitia et al., 2006). Refer to Henkel et al. (2012) for a review of potential carry-over effects to 

shorebirds potentially impacted by the Deepwater Horizon explosion, oil spill, and response. 

The long-term impacts of potential food-induced stress for bird species from an altered ecosystem due 

to a catastrophic spill are unknown, but disturbances to the ecosystem can cause long-term sublethal 

impacts, including reduced food intake, prey switching, increased energy expenditures, decreased 

reproductive success, and decreased survival. Decreases in either reproductive success or survival (or 

both) could result in population-level effects as was observed for certain avian species more than 10 years 

after the Exxon Valdez catastrophic spill (Esler et al., 2002 and 2010; Golet et al., 2002). Long-term, 

sublethal, chronic effects may exceed immediate losses (i.e., direct mortality of oiled birds) if residual 

effects influence a significant proportion of the population or disproportionately impact an important 

aspect of the population demographic, i.e., breeding-age females (Croxall and Rothery, 1991; Oro et al., 

2004). Depending on the effects and the life-history strategy of impacted species, some populations could 

take years or decades before reaching pre-spill population numbers and age-sex structure; some 

populations for some species may never recover (refer to Figure 4-13 of the 2012-2017 WPA/CPA 

Multisale EIS; refer to Peterson et al., 2003, but also to Wiens et al., 2010). 

In general, potential effects associated with Phase 4 should be limited to short-term disturbance 

effects (personnel and equipment) and potential indirect effects to various avian species groups due to 

habitat loss, alteration, or fragmentation from restoration efforts. There may be cases whereby incubating 

individuals are flushed from nests exposing their eggs or young to either weather-related mortality or 

depredation by avian or mammalian predators (American Bird Conservancy, 2010; National Audubon 

Society, Inc., 2010). However, efforts to minimize potential effects of post-oil spill monitoring and 

restoration efforts, particularly during the breeding season, should be sufficient to protect nesting birds as 

a function of oversight by Federal and State agencies charged with the conservation of migratory bird 

resources.

Limited information available to date with respect to avian impacts from the Deepwater Horizon

explosion, oil spill, and response suggests much lower mortality than would have been predicted by the 

spill size or volume alone (Belanger et al., 2010), though spill volume or size tends to be a poor predictor 

of avian mortality (Burger, 1993; Tan et al., 2010). The final modeled estimates of avian mortality will 

greatly exceed the number of avian carcasses collected (n = 7,258; Table A-5), but overall, the 

Deepwater Horizon explosion, oil spill, and response appears to have directly resulted in far fewer dead, 

oiled birds than the Exxon Valdez catastrophic spill (refer to Table 4-15 of the 2012-2017 WPA/CPA 

Multisale EIS). It should be recognized that the avian-related mortality associated with the Deepwater 

Horizon explosion, oil spill, and response (considered a catastrophic event) represents a small fraction of 

birds killed when compared with collisions with offshore oil and gas platforms. Russell (2005, page 304) 

states, “an average Gulf platform may cause 50 deaths by collision [only] per year,” so using this number, 

the number of deaths the Deepwater Horizon rig would have caused through collisions had it remained 

intact for its 40-year term would be about 2,000. That is about 5,258 fewer than the number of avian 

carcasses collected after the Deepwater Horizon explosion, oil spill, and response just given above. In the 

GOM, an estimated 200,000-321,000 avian deaths occur annually; primarily due to collisions with 

platforms (Table 4-7 of the 2012-2017 WPA/CPA Multisale EIS; also refer to Russell, 2005). Over the 

life of the GOM platform archipelago, the estimated total avian mortality is on the order of 7-12 million 
Catastrophic Spill Event Analysis A-67

birds (refer to Figure 4-15 of the 2012-2017 WPA/CPA Multisale EIS). Oil spills, regardless of size, are 

but one of a myriad of anthropogenic avian mortality sources. Even the cumulative total avian mortality 

associated with all the North American oil spills to date is only a small fraction when compared with 

estimates of annual avian mortality attributed to collisions with buildings and windows, predation by 

housecats, and collisions with powerlines and communication towers (Klem, 2009; Manville, 2009; Table 

4-7 of the 2012-2017 WPA/CPA Multisale EIS).

Overall Summary and Conclusion (Phases 1-4) 

While the species composition and species-specific mortality estimates are unknown and would be 

dependent on the blowout location and time of year, the mortalities for the initial event (Phase 1) would 

almost certainly not result in population-level impacts for species present at the time of the blowout and 

resulting fire. Seabirds are highly vulnerable to becoming oiled and also to ingesting oil during Phase 2 

(the offshore spill). Even recognizing the uncertainty associated with the scenario, spill characteristics, 

and the environmental conditions at the time of the spill, Phase 2 would likely be second only to Phase 3 

(onshore contact) in total avian mortality. Phase 3 would include impacts to much greater avian species’ 

richness and abundance (particularly during the breeding season) due to oil reaching habitats, including 

the nearshore, coastal beaches and dunes, and salt and brackish marshes. In general, the potential effects 

associated with Phase 4 (long-term recovery and response) should be limited to short-term disturbance 

effects (by cleanup personnel and equipment) and potential indirect effects to various bird species groups 

from habitat loss, alteration, or fragmentation from restoration efforts. 

Phases 1 (initial event) and 2 (offshore spill) would likely result in very limited impacts to threatened 

and endangered bird species because the two scenarios have oil restricted to the offshore environment. 

Phase 3 (onshore contact) would likely result in the greatest net negative impacts to threatened and 

endangered bird species due to contact with the shoreline and potential movement of spilled oil inland to 

other habitats during this phase. 

A.3.1.15. Fish Resources and Essential Fish Habitat

Phase 1—Initial Event

Depending on the type of blowout and the proximity of marine life to it (Table A-1), an eruption of 

gases and fluids may generate not only a toxic effect but also pressure waves and noise significant enough 

to injure or kill local biota. Within a few thousand meters of the blowout, resuspended sediments may 

clog fish gills and interfere with respiration. Settlement of resuspended sediments may, in turn, smother 

invertebrates or interfere with their respiration. Essential fish habitat (EFH) in the vicinity of the blowout 

could have adverse effects from the event. These EFH resources are discussed in the water quality 

(Chapter A.3.1.2), topographic features (Chapter A.3.1.6), Sargassum communities (Chapter A.3.1.7), 

chemosynthetic and nonchemosynthetic deepwater benthic communities (Chapters A.3.1.8 and A.3.1.9, 

respectively), and soft bottom benthic communities (Chapter A.3.1.10) chapters.

Phase 2—Offshore Spill

With the initiation of a catastrophic blowout incident, an explosion and subsequent fire are assumed 

to occur. If a blowout associated with the drilling of a single exploratory well occurs, this could result in 

a fire that would burn for 1 or 2 days, but if a blowout occurs on a production platform and other wells 

feed the fire, it could burn for over a month. The drilling rig or platform may sink, and if this occurs in 

shallow water, the sinking rig or platform may land in the immediate vicinity. If the blowout occurs in 

deep water, the rig or platform could land a great distance away and could be beyond avoidance zones. 

Regardless of water depth, the immediate response would be from search and rescue vessels and aircraft, 

such as USCG cutters, helicopters, rescue planes, and firefighting vessels.

Early life stages of animals are usually more sensitive to oil than adults (Boesch and Rabalais, 1987; 

NRC, 2005). Weathered crude oil has been shown in laboratory experiments to cause malformation, 

genetic damage, and even mortality at low levels in fish embryos of Pacific herring (Carls et al., 1999). 

Because natural crude oil found in the Gulf of Mexico would generally float on the surface, fish species 

whose eggs and larvae are found at or near the water surface are most at risk from an offshore spill. 
A-68 Western Planning Area Lease Sale 248 Supplemental EIS

Species whose spawning periods coincide with the timing of the highest oil concentrations would be at 

greatest risk.

Adult fish may be less at risk than earlier life stages, in part because they are less likely to concentrate 

at the surface and may avoid contact with floating oil. The effects of oil on organisms can include direct 

lethal toxicity, sublethal disruption of physiological processes (internal lesions), the effects from direct 

coating by oil (suffocation by coating gills), incorporation of hydrocarbons in organisms (tainting or 

accumulation in the food chain), and changes in biological habitat (decreased dissolved oxygen) (Moore 

and Dwyer, 1974). The extent of the impacts of the oil would depend on the properties of the oil and the 

time of year of the event.

If there is a subsea catastrophic blowout, it is assumed dispersants would be used. Then there could 

be effects on multiple life history stages and trophic levels. There is limited knowledge of the toxicity of 

dispersants mixed with oil to specific species or life stages of ichthyoplankton and the likely extent of 

mortality because the combination of factors is difficult to determine. The combined toxic effects of the 

oil and any dispersants that may be used would not be apparent unless a significant portion of a year-class 

is absent from next year’s fishery (e.g., shrimps, crabs, snapper, and tuna). 

An example of a catastrophic event in the WPA was modeled using OSRA (Appendix C of the WPA 

238/246/248 Supplemental EIS, Tables C-4 and C-5). Because fish occur throughout the GOM, it is 

assumed that some individuals would be contacted with oil. Specific habitats that are discussed with 

regards to the Western Planning Area OSRA example and in the Appendix are water quality (Chapter 

A.3.1.2), wetlands (Chapter A.3.1.4), seagrass communities (Chapter A.3.1.5), topographic features 

(Chapter A.3.1.6), Sargassum communities (Chapter A.3.1.7), chemosynthetic and nonchemosynthetic 

deepwater communities (Chapters A.3.1.8 and A.3.1.9, respectively), and soft bottom benthic 

communities (Chapter A.3.1.10).

Studies by USEPA, Office of Research and Development (2010) using representative species provide 

some indication of the relative toxicity of Louisiana sweet crude oil, dispersants, and oil/dispersant mixes. 

Bioassays were conducted using two Gulf species—a mysid shrimp (Amercamysis bahia) and a small 

estuarine fish, the inland silverside (Menidia beryllinina)—to evaluate the acute toxic effects of oil, eight 

dispersants, and oil/dispersant mixtures. In addition, USEPA used standard in vitro techniques using the 

same dispersants to (1) evaluate the acute toxicity on three cell lines over a range of concentrations and 

(2) evaluate the effects of these dispersants on androgen and estrogen function using human cell lines (to 

see if they are likely to disrupt hormonal systems). All dispersants showed cytotoxicity in at least one cell 

type at concentrations between 10 and 110 ppm. Results of the in vitro toxicity tests were similar to the 

whole animal tests. For all eight dispersants, for both species, the dispersants alone were less toxic than 

the dispersant/oil mixture. Louisiana sweet crude oil alone was determined to be more toxic to both the 

mysid shrimp and silverside fish than the dispersants alone. The results of the testing for disruption of 

androgen and estrogen function indicate that the dispersants do not show biologically significant 

endocrine activity via androgen or estrogen pathways (USEPA, Office of Research and Development, 

2010). 

The GOM waters out to 100 fathoms (182 m; 600 ft) have EFHs described and identified for managed 

species (GMFMC, 2005; USDOC, NOAA, 2009). There are Fisheries Management Plans for shrimp, red 

drum, reef fishes, coastal migratory pelagics, spiny lobsters, coral and coral reefs, and highly migratory 

species (GMFMC, 2004; USDOC, NOAA, 2009). These species could use the GOM for EFH at different 

life history stages. The Highly Migratory Species Fisheries Management Plan was recently amended to 

update EFH and Habitat Areas of Particular Concerns for the Atlantic bluefin tuna spawning area 

(USDOC, NOAA, 2009).

These EFHs in the Gulf of Mexico are discussed in various chapters of this Appendix: water column 

(Chapter A.3.1.2); wetlands (Chapter A.3.1.4); seagrass communities (Chapter A.3.1.5); topographic 

features (Chapter A.3.1.6); Sargassum communities (Chapter A.3.1.7); chemosynthetic and 

nonchemosynthetic deepwater benthic communities (Chapters A.3.1.8 and A.3.1.9, respectively), and 

soft bottom benthic communities (Chapter A.3.1.10); these EFHs are also summarized in Appendix D of 

the 2012-2017 WPA/CPA Multisale EIS. There are current NTLs (NTL 2009-G39 and NTL 2009-G40) 

and stipulations that provide guidance and clarification of the regulations with respect to many of these 

biologically sensitive underwater features and areas and benthic communities, which are considered EFH. 
Catastrophic Spill Event Analysis A-69

Plankton 

Open-water organisms, such as phytoplankton and zooplankton, are essential to the marine food web. 

They play an important role in regulating climate, contribute to marine snow, and are an important source 

of nutrients for mesopelagic and benthic habitats. Also, monthly ichthyoplankton collections over the 

years 2004-2006 offshore of Alabama have confirmed that peak seasons for ichthyoplankton 

concentrations on the shelf are spring and summer (Hernandez et al., 2010). If a catastrophic blowout 

occurs in the spring and summer, it could cause greater harm to fish populations and not just individual 

fish. Therefore, an offshore oil spill would not only have an impact on these populations but also on the 

species that depend on them. 

The microbial community can also be affected by an offshore oil spill. The microbial loop is an 

essential part of the marine ecosystem. Changes in the microbial community because of an oil spill could 

have significant impacts on the rest of the marine ecosystem. However, several laboratory and field 

experiments and observations have shown that impacts to planktonic and marine microbial populations 

are generally short lived and do not affect all groups evenly, and in some cases stimulate growth of 

important species (Gonzalez et al., 2009; Graham et al., 2010; Hing et al., 2011). 

Phase 3—Onshore Contact

It is estimated that shoreline oiling would last 1-5 months from a shallow-water catastrophic spill 

event and 3-4 months from a deepwater catastrophic spill. It is estimated that there would be contact to 

the shoreline within 30 days of the spill for both shallow-water and deepwater spill locations. Though 

response methods would be monitored, there would also be some impact from these efforts on contacted 

coastal habitats. Further detail on this catastrophic OSRA run is contained in Appendix C of the WPA 

238/246/248 Supplemental EIS.

The life history of estuarine-dependent species involves spawning on the continental shelf; the 

transportation of eggs, larvae, or juveniles back to the estuary nursery grounds; and migration of the 

adults back to the sea for spawning (Deegan, 1989; Beck et al., 2001). Estuaries in the Gulf of Mexico 

are extremely important nursery areas and are considered EFH for fish and other aquatic life (Beck et al., 

2001). Oiling of these areas, depending on the severity, can destroy nutrient-rich marshes and erode 

coastlines that have been significantly damaged by recent hurricanes.

The Gulf of Mexico supports a wide variety of finfish, and most of the commercial finfish resources 

are linked either directly or indirectly to the estuaries that ring the Gulf of Mexico. Darnell et al. (1983) 

observed that the density distribution of fish resources in the Gulf was highest nearshore off of the central 

Gulf Coast. For all seasons, the greatest abundance occurred between Galveston Bay and the mouth of 

the Mississippi River. Oyster beds could be damaged by freshwater diversions that release tens of 

thousands of cubic feet of freshwater per second for months in an effort to keep oil out of the marshes. 

Adult oysters survive well physiologically in salinities from those of estuarine waters (about 7.5 parts per 

thousand sustained) to full strength seawater (Davis, 1958). While oysters may tolerate small changes in 

salinity for a few weeks, a rapid decrease in salinity over months would kill oysters. In the event of a 

catastrophic oil spill, at least 1 year’s oyster production in the area receiving fresh water would be lost 

because of exposure to freshwater and/or oil.

Phase 4—Post-Spill, Long-Term Recovery and Response 

In addition to possible small fish kills because of direct impacts (as described under Phases 2 and 3), a 

catastrophic spill could affect fish populations in the long term. Due to a catastrophic spill, a significant 

portion of a year class of fish could be absent from the following year’s fishery, reducing overall 

population numbers. However, sublethal impacts, especially for long-lived species (e.g., snapper and 

grouper), could be masked by reduced fishing pressure because of closures. In addition, healthy fish 

resources and fishery stocks depend on ideal habitat (EFH) for spawning, breeding, feeding, and growth 

to maturity. There could be long-term effects to coastal habitats from buried or sequestered oil becoming 

resuspended after a disturbance. Thus, a catastrophic spill that affects these areas could result in longterm impacts, including destruction to a portion of their natural habitats. 
A-70 Western Planning Area Lease Sale 248 Supplemental EIS

Overall Summary and Conclusion (Phases 1-4) 

Depending on the type of blowout and the proximity of marine life to it, an eruption of gases and 

fluids may generate not only a toxic effect but also pressure waves and noise significant enough to injure 

or kill local biota and destroy habitat in the immediate vicinity (Phase 1). Adult fish may be less at risk 

than earlier life stages, in part because they are less likely to concentrate at the surface and may avoid 

contact with floating oil. Effects of oil on organisms can include direct lethal toxicity, sublethal 

disruption of physiological processes (internal lesions), the effects from direct coating by oil (suffocation 

by coating gills), incorporation of hydrocarbons in organisms (tainting or accumulation in the food chain), 

and changes in biological habitat (decreased dissolved oxygen) (Phase 2). Estuaries in the Gulf of 

Mexico are extremely important nursery areas and are considered EFH for fish and other aquatic life 

(Beck et al., 2001). Oiling of these areas, depending on the severity, can destroy nutrient-rich marshes 

and erode coastlines that have been significantly damaged by recent hurricanes (Phase 3). Due to a 

catastrophic spill, a significant portion of a year class of fish could be absent from the following year’s 

fishery, reducing overall population numbers. However, sublethal impacts, especially for long-lived 

species (e.g., snapper and grouper), could be masked by reduced fishing pressure because of closures 

(Phase 4). 

A.3.1.16. Commercial Fisheries

Phase 1—Initial Event

The initial explosion and fire could endanger commercial fishermen in the immediate vicinity of the 

blowout. Although commercial fishing vessels in the area would likely aid in initial search-and-rescue 

operations, the subsequent fire could burn for over a month, during which time commercial vessels would 

be expected to avoid the area so as to not interfere with response activities. This could impact the 

livelihood and income of these commercial fishermen. The extent of the economic impact on the fishing 

community would depend largely on the season during which the blowout occurred, the depth of water in 

which it occurred, and its distance from shore.

Phase 2—Offshore Spill

The Gulf of Mexico is one of the largest producers of seafood in the continental United States. In 

2010 the Gulf of Mexico provided 40 percent of the commercial fishery landings in the continental U.S. 

(excluding Alaska), with over 1.5 billion pounds valued at nearly $670 million (USDOC, NMFS, 2012b). 

Various commercial species are fished from State waters through the Exclusive Economic Zone and are 

found throughout the water column as well as at the surface and near the seafloor. Commercial species 

occupy many different habitats throughout the area, and many commercial species occupy different 

habitats during different life stages. Most commercial species spend at least part of their life cycles in the 

productive shelf and estuarine habitat. In the event of a catastrophic offshore spill, it is assumed that a 

large quantity of oil would be released daily whether this spill occurred in State or Federal waters. 

Although the oil would generally float, it is also assumed that dispersants would be used preventing much 

of the oil from reaching the surface. 

As an example of the areas that could be affected by such a catastrophic oil spill in the WPA, two 

OSRA model runs were performed using two different launch points as described in Chapter A.1.2.3. 

The resulting tables show conditional probabilities (expressed as percent chance) of an oil spill contacting 

resources in the GOM for each launch point and for each season, the condition being that a spill is 

assumed to have occurred at the given location. Because the commercial species are so widespread over 

the GOM, all of the tables are referenced (Appendix C of the WPA 238/246/248 Supplemental EIS, 

Tables C-4 and C-5). 

Oil that is not volatilized, dispersed, or emulsified by dispersants has the potential to affect finfish 

through direct ingestion of hydrocarbons or ingestion of contaminated prey. Finfish are, however, mobile 

and generally avoid adverse conditions. Less mobile species or planktonic larval stages are more 

susceptible to the effects of oil and dispersants.

Actual effects of any oil that is released and comes in contact with populations of commercially 

important species will depend on the API gravity of the oil, its ability to be metabolized by 

microorganisms, and the time of year of the spill. The effects on the populations will be at a maximum 
Catastrophic Spill Event Analysis A-71

during the spawning season of any commercially important population, exposing larvae and juveniles to 

oil. The effects on commercial species may also include tainting of flesh or the perception of tainting in 

the market. This can, depending on the extent and duration of the spill, affect marketability of 

commercial species.

Even though sensory testing may show no detectable oil or dispersant odors or flavors and the 

chemical test results could be well below the known levels of concern, NOAA Fisheries would be 

expected to close large portions of the Gulf of Mexico during a high-volume spill. This would be done as 

a precautionary measure to ensure public safety and to assure consumer confidence in Gulf seafood 

(USDOC, NMFS, 2010b). Up to 30-40 percent of the Gulf of Mexico’s Exclusive Economic Zone could 

be closed to commercial fishing as the spill continues and expands (USDOC, NMFS, 2010c). This area 

could represent 50-75 percent of the Gulf’s seafood production (Flynn, 2010). The size of the closure 

area may peak about 50 days into the spill and could persist another 2-3 months until the well is killed or 

capped and the remaining oil is recovered or dissipates. During this period, portions or all of individual 

State waters would also be closed to commercial fishing.

The economic impacts of closures on commercial fishing are difficult to predict because they are 

dependent on the season and would vary by fishery. If fishers cannot make up losses throughout the 

remainder of the season, a substantial part of their annual income would be lost. In some cases, 

commercial fishers will leave the industry and some may move to areas still open to fishing, but at a 

greater cost because of longer transit times. Marketing issues are also possible; even if the catch is 

uncontaminated, the public may lack confidence in the product. The duration of the public’s perception 

of seafood tainting is also difficult to predict and depends to some extent on the duration of the spill and 

public awareness of the spill.

Phase 3—Onshore Contact

Shoreline contact of oil is estimated to persist from 1 to 5 months in the event of a shallow-water 

catastrophic spill and for up to 6 months from a deepwater catastrophic spill. The OSRA probability 

tables show the conditional probabilities (expressed as percent chance) for a shoreline contact for each 

season, the condition being that a spill is assumed to have occurred at the given location. Further detail 

on this catastrophic OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental EIS. 

This scenario, depending on the season of occurrence, would cause disruption in commercial fishing 

activity because many commercial fishermen operate inshore in State waters.

In addition to closures in Federal waters, portions of individual State waters would also be closed to 

commercial fishing. The economic impacts of closures on commercial fishing are complicated to predict 

because they are dependent on season and would vary by fishery. If fishers cannot make up losses in the 

remainder of the season, a substantial part of their annual income will be lost. In some cases, commercial 

fishers may move to areas still open to fishing, but at a greater cost because of longer transit times and, in 

some instances, additional license costs. Some commercial fishermen may also augment their income by 

aiding in the cleanup effort and/or renting the boats as vessels of opportunity. 

Phase 4—Post-Spill, Long-Term Recovery and Response 

The Gulf of Mexico is an important biological and economic area in terms of commercial seafood 

production and recreational fishing. Commercial fishermen in the Gulf of Mexico harvested over 

1.5 billion pounds of finfish and shellfish in 2010 (USDOC, NMFS, 2012b). The economic impacts of 

closures on commercial fishing are complicated to predict because the economic effects are dependent on 

season and would vary by fishery. If fishermen cannot make up losses by fishing the remainder of the 

season or by participating as contractors in the cleanup, a substantial part of their annual income could be 

lost and may force them out of the industry. While the commercial fishing industry of Texas did not 

sustain measurable direct or indirect economic effects following the 1979 Ixtoc I blowout and spill 

(Restrepo et al., 1982), there is a documented phenomenon that, long after an incident, the perception of 

tainted fish and shellfish from the impacted area persists (Keithly and Diop, 2001). Data regarding the 

duration of the negative perception of Gulf seafood following the Deepwater Horizon explosion, oil spill, 

and response are not yet available. It is reasonable to assume that a negative perception could impact the 

value of commercial fish resources for several seasons.
A-72 Western Planning Area Lease Sale 248 Supplemental EIS

Overall Summary and Conclusion (Phases 1-4) 

The Gulf of Mexico is one of the largest producers of seafood in the continental United States. 

Various commercial species are fished from State waters through the Exclusive Economic Zone and are 

found throughout the water column. The primary economic impacts of oil spill on commercial fisheries 

are the closure of State or Federal waters to fishing and the perception of seafood tainting by the market. 

Both of these factors are difficult to predict. Closures depend on the size, timing, depth of water, and 

location of the spill as well as the fishery involved. Perception depends on length of the spill and public 

perception. Both of these factors could affect the livelihood of the fishing community. 

A.3.1.17. Recreational Fishing

Phase 1—Initial Phase

About 20 percent of the recreational fishing activity in the Gulf of Mexico occurs within 300 ft 

(91 m) of oil and gas structures (Hiett and Milon, 2002). Therefore, an explosion and fire could endanger 

recreational fishermen and divers in the immediate vicinity of the blowout, especially if the blowout is 

located close to shore. Recreational vessels in the area would likely aid in initial search-and-rescue 

operations but they would also be in danger during the explosion and subsequent fire. The subsequent 

fire could burn for up to a month, during which recreational vessels would be expected to avoid the area 

and to not interfere with response activities. It is also possible that recreational fishing could be impacted 

in areas beyond the immediate area of the event due to the perceptions of the public. 

Phase 2—Offshore Spill

If a catastrophic spill were to occur, a substantial portion of ocean waters could be closed. For 

example, 88,522 square miles (mi2

) (229,271 square kilometers [km2]) were closed to recreational fishing 

activity at the peak of the Macondo well oil spill. However, the majority of recreational fishing activity 

occurs fairly close to shore. Therefore, while the spill remains offshore, the impacts would be particularly 

felt with respect to fishing of offshore species such as king mackerel and red snapper (the impacts of a 

catastrophic spill on fish populations are discussed in Chapter A.3.1.15). The NOAA’s Center for 

Coastal Monitoring and Assessment (USDOC, NOAA, Center for Coastal Monitoring and Assessment, 

2012) provides a set of maps that display the locations in the Gulf of Mexico where certain fish species 

are prevalent. However, even while the spill remains offshore, there could be impacts to inshore 

recreational fishing due to misperceptions regarding the extent of the spill or due to concerns regarding 

the tainting of fish species. These misperceptions could also reduce tourism activity, which would impact 

tourism-based recreational fishing activity.

In 2011, the percent of each Gulf Coast State’s recreational fishing activity that occurred in State and 

Federal ocean waters combined (i.e., not inland waters) were as follows: Texas (6%); Louisiana (5%); 

Mississippi (2%); Alabama (42%); and West Florida (34%) (USDOC, NMFS, 2012c and 2012d; Texas 

Parks and Wildlife Department, 2012). Chapter 4.1.1.17 of this Supplemental EIS provides a further 

breakdown of recreational fishing activity by state. Further detail on this catastrophic OSRA run is 

contained in Appendix C of the WPA 238/246/248 Supplemental EIS. 

Phase 3—Onshore Contact

If a catastrophic spill were to reach shore, there would likely be noticeable impacts to recreational 

fishing activity. Since most recreational fishing activity occurs fairly close to shore, there would be a 

number of direct impacts to angler activity due to the fishing closures that would likely arise. This is 

particularly true since anglers would find it more difficult to find substitute fishing sites in the case of a 

catastrophic spill. In 2011, the percent of each Gulf State’s recreational fishing activity that occurred 

inland was as follows: Texas (94%); Louisiana (95%); Mississippi (98%); Alabama (58%); and West 

Florida (66%) (USDOC, NMFS, 2012c and 2012d; Texas Parks and Wildlife Department, 2012). The 

impacts to recreational fishing would also depend on the time of year of the spill. In 2011, 31 percent of 

angler trips in the Gulf occurred between January and April, 41 percent of angler trips occurred between 

May and August, and 28 percent of angler trips occurred between September and December (USDOC, 

NMFS, 2012c and 2012d). In addition, fishing tournaments are often scheduled for the summer months 
Catastrophic Spill Event Analysis A-73

and would be difficult to reschedule in the aftermath of a catastrophic spill. Further detail on this 

catastrophic OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental EIS.

There would also be various economic impacts along the recreational fishing supply chain. Gentner 

Consulting Group (2010) estimates that recreational fishing activity supports $9.8 million in direct 

expenditures and $23 million in total sales per day in the Gulf of Mexico. There could be further impacts 

if the fishing closures persisted long enough to affect purchases of boats and other durable fishing 

equipment. There could also be further impacts if the loss of opportunities for recreational fishing 

activity exacerbated the fall in tourism activity that would arise due to the spill.

Phase 4—Post-Spill, Long-Term Recovery and Response 

The long-term impacts of a catastrophic spill on recreational fishing activity would primarily depend 

on the extent to which fish populations recover (refer to Chapter A.3.1.15 for more information). 

However, the longer term impacts of a spill on recreational fishing activity would also depend on the 

extent to which public perceptions of fish tainting can be assuaged. In addition, the longer-term impacts 

would depend on the extent to which the various firms that serve the recreational fishing industry would 

be able to weather the downturn in activity resulting from the spill. 

Overall Summary and Conclusion (Phases 1-4) 

Recreational fishing activity could be noticeably impacted in the event of a catastrophic spill. This is 

particularly the case if the spill reached shore or if the spill occurred during peak times and places of 

recreational fishing activity. The long-term impacts of a catastrophic spill would depend on the extent to 

which fish populations recover and the length of time it would take to convince the public that it was 

again safe to fish in the affected areas.

A.3.1.18. Recreational Resources

Phase 1—Initial Event

The most immediate impacts of a catastrophic spill would be on the recreational fishing and 

recreational diving activity in the vicinity of the blowout. About 20 percent of the recreational fishing 

activity and 90 percent of the recreational diving activity in the Gulf of Mexico from Alabama to Texas 

occurs within 300 ft (91 m) of oil and gas structures (Hiett and Milon, 2002). The impacts on recreational 

fishing and recreational diving would be greater the closer the blowout occurred to shore. The immediate 

response activities could also impact ocean-based recreational activity. Finally, there could be impacts to 

tourism activity since a catastrophic spill would likely receive a large amount of media attention.

Phase 2—Offshore Spill

While the spill is still offshore, there could be some ocean-dependent recreation that is affected (e.g., 

fishing, diving, and boating), as discussed above. In addition, there may be some effects due either to 

perceived damage to onshore recreational resources that has not yet materialized or to general hesitation 

on the part of travelers to visit the overall region because of the spill. A Congressional hearing into this 

matter (U.S. House of Representatives, 2010) provides a broad overview of some of the effects that were 

felt along the Gulf Coast subsequent to the Deepwater Horizon explosion, oil spill, and response. For 

example, a representative of Pinellas County estimated that this area had lost roughly $70 million in hotel 

revenue even though beaches in this area did not receive any oil damage. This type of effect could be due 

to misperceptions about the spill, uncertainty about the future of the spill, or concerns about whether a 

tourism experience will be affected even if the destination is only within close proximity to a spill.

As previously mentioned, recreational diving is one offshore recreational activity that would be 

particularly affected by a catastrophic oil spill. Further detail on this catastrophic OSRA run is contained 

in Appendix C of the WPA 238/246/248 Supplemental EIS. 
A-74 Western Planning Area Lease Sale 248 Supplemental EIS

Phase 3—Onshore Contact

A catastrophic spill has the potential to noticeably impact the Gulf Coast recreation and tourism 

industries. The water-dependent and beach-dependent components of these industries would be 

particularly vulnerable. Environmental Sensitivity Indexes (ESIs) provide overall measures of the 

sensitivity of a particular coastline to a potential oil spill. The ESIs rank coastlines from 1 (least 

sensitive) to 10 (most sensitive). Marshes and swamps are examples of resources that have ESIs of 10 

due to the extreme difficulty of removing oil from these areas; marsh and swamp areas are particularly 

prevalent in Louisiana. The ESIs for beach areas generally range from 3 to 6, depending on the type of 

sand and the extent to which gravel is mixed into the beach area; beach areas are particularly prevalent in 

Texas, Mississippi, Alabama, and Florida. The ESI maps for any coastline along the Gulf of Mexico can 

be viewed using the National Oceanic and Atmospheric Administration’s ERMA mapping system 

(USDOC, NOAA, 2012b; USDOC, NOAA, Office of Response and Restoration, 2014). The ESI maps 

also provide point indicators for recreational resources.

A catastrophic spill would also raise a number of issues regarding recreational activity that is based 

on tourism. One important point is that a spill of the Deepwater Horizon’s dimensions can influence a 

much broader range of individuals and firms than can a smaller spill. For example, a small, localized spill 

may lead some travelers to seek substitute recreational opportunities in nearby areas. However, a large 

spill is more likely to dissuade travelers from visiting a broader economic region. Similarly, small- and 

mid-sized restaurant chains and hotels may be able to find other customers or to simply weather a smaller 

spill. However, a spill the size of the Deepwater Horizon is more likely to affect these types of firms 

since they are less able to diversify their customer base. These effects can be seen in the makeup of those 

who filed damage claims with BP (Gulf Coast Claims Facility, 2012); the Gulf Coast Claims Facility 

closed in early 2012 subsequent to preliminary court approval of a settlement program. For example, the 

bulk of the claims by individuals have been made in the food, beverage, and lodging sector and in the 

retail, sales, and service sector. Claims have also been made by individuals and firms in a broad range of 

geographic regions, many of which were not directly impacted by oil. 

Murtaugh (2010) provides data on the change in hotel and sales tax receipts for individual Gulf Coast 

counties in the months immediately following the Deepwater Horizon explosion, oil spill, and response. 

During the summer of 2010, the spill caused substantial declines in hotel receipts in the following 

counties: Baldwin, Alabama (33.2% decline); Santa Rosa, Florida (24.8% decline); Okaloosa, Florida 

(24.1% decline); Walton, Florida (12.3% decline); and Bay, Florida (7.4% decline). However, coastal 

counties west of Baldwin, Alabama (as far west as St. Mary, Louisiana), generally experienced noticeable 

increases in hotel receipts. This was particularly true in Mobile, Alabama; Jackson, Mississippi; and in 

the coastal parishes of Louisiana. For example, in Louisiana, St. Mary, Terrebonne, and Lafourche 

Parishes each reported increases in hotel tax receipts of over 80 percent in the summer of 2010. These 

effects are likely due to the influx of oil-spill relief workers to these areas in the immediate aftermath of 

the Deepwater Horizon explosion, oil spill, and response. Overall sales tax receipts in counties from 

Baldwin, Alabama, eastward also generally fell during 2010, although to a lesser extent than hotel tax 

receipts. Sales tax receipts in counties and parishes west of Baldwin, Alabama, did not show as clear a 

pattern as did hotel tax receipts. For example, overall sales tax receipts fell by 12.5 percent in Hancock 

County (Mississippi), receipts were almost unchanged in Harrison County (Mississippi), and receipts 

increased by 8.3 percent in Orleans Parish (Louisiana). These results suggest that the impacts of a future 

catastrophic spill will be influenced by the structure of a particular county/parish’s recreational economy, 

as well as by the extent to which oil-spill-response activities will mitigate some of the negative impacts of 

the spill in certain areas.

There could also be effects on tourist activities in areas far away from the areas directly affected by 

oil. For example, in Texas subsequent to the Deepwater Horizon explosion, oil spill, and response, some 

tourists may have stayed away from Texas Gulf Coast beaches due to misperceptions regarding the extent 

to which these beaches were damaged due to the spill. Conversely, there may have been some 

substitution of beach visitation away from beaches in the eastern Gulf towards the beaches in Texas, 

which were farther from the spill. While it is difficult to quantify these effects, some anecdotal evidence 

regarding this substitution effect can be found in Pack (2010). Hotel occupancy data suggest that these 

two effects may have largely offset each other. Source Strategies Inc. (2010) reports that total hotel 

occupancy in the three metro regions in Texas closest to the Gulf Coast increased just 1.9 percent during 
Catastrophic Spill Event Analysis A-75

the third quarter of 2010 compared with the third quarter of 2009. Further detail on this catastrophic 

OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental EIS. 

Phase 4—Post-Spill, Long-Term Recovery and Response 

The longer-term implications of a catastrophic event on tourism would depend on the extent to which 

any structural/ecological damage can be repaired and the extent to which economic mitigation actions 

would occur. The long-term implications of a catastrophic spill would also depend on the extent to which 

public confidence in the various components of the recreational and tourism economies can be restored. 

For example, restaurants in the region would be impacted to the extent to which they are perceived to use 

seafood products caught or raised in contaminated waters. Similarly, although beaches can be 

decontaminated not long after a spill has been stopped, lingering perceptions can be expected to 

negatively impact tourism even after a spill has ended.

Oxford Economics (2010) attempt to quantify these effects by analyzing the impacts of recent 

catastrophic events on recreational economies. For example, they analyzed the Ixtoc I well blowout and 

spill of 1979, the scale and nature of which was reasonably similar to the Macondo well blowout and spill 

of 2010. In this example, it took approximately 3 years for beaches to be cleaned and for recreational 

activity to return to similar levels as before the spill. They also looked at the Prestige oil spill of 2002 off 

the coast of Spain. Given the nature and size of that spill, recreational activity was able to return to prespill levels in approximately 1 year. Alaska’s tourism economy took approximately 2 years to recover 

from the Exxon Valdez spill.

Overall Summary and Conclusion (Phases 1-4) 

A catastrophic spill can cause noticeable impacts to recreational resources such as beaches. A 

catastrophic spill can also have complex effects on recreational activity that depends on tourism. The 

longer-term implications of a catastrophic oil spill on tourism would depend on the extent to which any 

structural/ecological damage can be repaired, the extent to which economic mitigation actions would 

occur, and the speed at which public confidence in the various components of the affected recreational 

and tourism economies would be restored. 

A.3.1.19. Archaeological Resources

Phase 1—Initial Event

Offshore Archaeological Resources

BOEM protects all identified and potentially historic and prehistoric archaeological resources on the 

OCS by requiring appropriate avoidance criteria as well as directives to investigate these resources. 

Onshore archaeological resources, prehistoric and historic sites, would not be immediately impacted 

during the initial phase of a catastrophic blowout because the distance of a blowout site from shore is at 

least 3 nmi (3.5 mi; 5.6 km). However, offshore catastrophic blowouts, when compared with spills of 

lesser magnitude, may initially impact multiple archaeological resources. Resources adjacent to a 

catastrophic blowout could be damaged by the high volume of escaping gas, buried by large amounts of 

dispersed sediments, crushed by the sinking of the rig or platform, destroyed during emergency relief well 

drilling, or contaminated by the hydrocarbons. 

Based on historical information, over 2,100 potential shipwreck locations have been identified on the 

Gulf of Mexico OCS (USDOI, MMS, 2007). This number is a conservative estimate and is heavily 

weighted toward post-19th century, nearshore shipwrecks, where historic records documenting the loss of 

the vessels were generated more consistently. BOEM currently has confirmed locational data for 

approximately 380 potential wreck sites, although the historic significance for the majority of these sites 

has not been determined. 

BOEM’s Regional Director may require the preparation of an archaeological report to accompany the 

exploration plan, development operations coordination document, or development and production plan, 

under 30 CFR § 550.194, and BSEE’s Regional Director may do likewise under 30 CFR § 250.194 if a 

potential wreck is encountered during operations. As part of the environmental reviews conducted for 

postlease activities, available information is evaluated regarding the potential presence of archaeological 
A-76 Western Planning Area Lease Sale 248 Supplemental EIS

resources within a WPA proposed action area to determine if additional archaeological resource surveys 

and mitigations are warranted. Having complete knowledge of seafloor resources before a spill occurs 

would enable responders to quickly plan countermeasures in a way that would minimize adverse effects 

occurring from the spill response. 

Phase 2—Offshore Spill

Offshore Archaeological Resources

Due to the response methods (i.e., subsea dispersants) and magnitude of the response (i.e., thousands 

of vessels), a catastrophic blowout and spill have a greater potential to impact offshore archaeological 

resources than other accidental events. 

Deep Water

In contrast to smaller spills or spills in shallow water, large quantities of subsea dispersants could be 

used for a catastrophic subsea blowout in deep water. This could result in currently unknown effects from 

dispersed oil droplets settling to the seafloor. Though information on the actual impacts to submerged 

cultural resources is inconclusive at this time, oil settling to the seafloor could come in contact with 

archaeological resources. At present, there is no evidence of this having occurred. A recent experimental 

study has suggested that, while the degradation of wood in terrestrial environments is initially retarded by 

contamination with crude oil, at later stages, the biodeterioration of wood is accelerated (Ejechi, 2003). 

While there are different environmental constraints that affect the degradation of wood in terrestrial and 

waterlogged environments, soft-rot fungal activity, one of the primary wood degrading organisms in 

submerged environments, was shown to be increased in the presence of crude oil (Ejechi, 2003). There is 

a possibility that oil from a catastrophic blowout could come in contact with wooden shipwrecks and 

artifacts on the seafloor and accelerate their deterioration.

Ancillary damages from vessels associated with oil-spill-response activities (e.g., anchoring) in deep 

water are unlikely because of the use of dynamically positioned vessels responding to a deepwater 

blowout. If response and support vessels were to anchor near a deepwater blowout site, the potential to 

damage undiscovered vessels in the area would be high because of the required number and the size of 

anchors and the length of mooring chains needed to safely secure vessels. Additionally, multiple offshore 

vessel decontamination stations would likely be established in shallow water outside of ports or entrances 

to inland waterways, as seen for the Deepwater Horizon explosion, oil spill, and response. The anchoring 

of vessels could result in damage to both known and undiscovered archaeological sites; the potential to 

impact archaeological resources increases as the density of anchoring activities in these areas increases. 

Shallow Water

The potential for damaging archaeological resources increases as the oil spill and related response 

activities progress landward. In shallower waters, most of the damage would be associated with oil 

cleanup and response activities. Thousands of vessels would respond to a shallow-water blowout and 

would likely anchor, potentially damaging both known and undiscovered archaeological sites. Additional 

anchoring would be associated with offshore vessel decontamination stations, as described above. As the 

spill moves into the intertidal zone, the chance of direct contact between the oil and archaeological 

resources increases. As discussed above, this could result in increased degradation of wooden shipwrecks 

and artifacts.

Additionally, in shallow waters, shipwrecks often act as a substrate to corals and other organisms, 

becoming an essential component of the marine ecosystem. These organisms often form a protective 

layer over the shipwreck, virtually encasing the artifacts and hull remains. If these fragile ecosystems 

were destroyed as a result of the oil spill and if the protective layer was removed, the shipwreck would 

then be exposed to increased degradation until it reaches a new level of relative stasis with its 

surroundings. 

Regardless of water depth, because oil is a hydrocarbon, heavy oiling could contaminate organic 

materials associated with archaeological sites, resulting in erroneous dates from standard radiometric 

dating techniques (e.g., 14C-dating). Interference with the accuracy of 14C-dating would result in the loss 

of valuable data necessary to understand and interpret the sites.
Catastrophic Spill Event Analysis A-77

Phase 3—Onshore Contact

Onshore Archaeological Resources

Regardless of the water depth in which the catastrophic blowout occurs, it is assumed that more than 

1,000 mi (1,609 km) of shoreline could be oiled to some degree. Onshore prehistoric and historic sites 

would be impacted to some extent by a high-volume spill from a catastrophic blowout that reaches shore. 

Sites on barrier islands could suffer the heaviest impact, and prehistoric sites located inland from the 

coastline, in the marsh, and along bayous could also experience some light oiling. Impacts would include 

the loss of ability to accurately date organic material from archaeological sites because of contamination 

or increased research costs to clean samples for analysis. Efforts to prevent coastal cultural resources 

from becoming contaminated by oil would likely be overwhelmed in the event of a hurricane and by the 

magnitude of shoreline impacted. 

The most significant damage to archaeological sites could be related to cleanup and response efforts. 

Fortunately, important lessons were learned from the Exxon Valdez spill in Alaska in 1989, in which the 

greatest damage to archaeological sites was related to cleanup activities and looting by cleanup crews 

rather than from the oil itself (Bittner, 1996). As a result, cultural resources were recognized as 

significant early in the Deepwater Horizon response and cleanup. Archaeologists were embedded in 

Shoreline Cleanup Assessment Teams (SCAT) and consulted with cleanup crews. Historic preservation 

representatives were present at both the Joint Incident Command as well as each Area Command under 

the general oversight of the National Park Service to coordinate response efforts (Odess, official 

communication, 2010). Despite these efforts, some archaeological sites suffered damage from looting or 

from spill cleanup activities, most notably the parade ground at Fort Morgan, Alabama (Odess, official 

communication, 2011). 

Phase 4—Post-Spill, Long-Term Recovery and Response

Onshore Archaeological Resources

Regardless of the water depth in which the catastrophic blowout occurs, it is assumed that more than 

1,000 mi (1,609 km) of shoreline could be oiled to some degree. Onshore prehistoric and historic sites 

would be impacted to some extent by a high-volume spill from a catastrophic blowout that reaches shore. 

A few prehistoric sites in Louisiana, located inland from the coastline in the marsh and along bayous, 

could experience some light oiling. As discussed above, impacts would include the permanent loss of 

ability to accurately date organic material from archaeological sites because of contamination. The most 

significant damage to archaeological sites would be related to cleanup and response efforts. Long-term 

recovery would prove difficult if not impossible. Historic structures such as coastal forts that are exposed 

to oiling are generally constructed of brick or other porous, friable materials that are difficult to clean 

without causing further damage (Chin and Church, 2010). Funding for any sort or archaeological 

recovery is problematic outside of Federal lands because of existing laws and regulations (Varmer, 2014). 

Most coastal prehistoric sites in Louisiana, for example, are on private lands where there is no mechanism 

to recover damages. Section 106 of the National Historic Preservation Act is triggered by a Federal 

undertaking, which in the case of a spill, would be the response and not the actual spill. The Natural 

Resource Damage Assessment (NRDA) process codified by the Oil Pollution Act of 1990 is a legal 

process to determine the type and amount of restoration needed to compensate the public for harm to 

natural resources that occurs as a result of an oil spill, but it does not cover cultural, archaeological, or 

historic properties. 

Overall Summary and Conclusion (Phases 1-4) 

Archaeological resources are finite, unique, irreplaceable, nonrenewable records of mankind’s past, 

which, once destroyed or damaged, are gone forever. In the event of a catastrophic oil spill, the most 

likely source of irreversible impact is, from the spill response, and the danger increases dramatically as 

the response approaches the shoreline. This damage can, to a large extent, be mitigated by the early 

integration of archaeologists and State and Tribal historic preservation officers in the response to protect 

sites from impact. Mitigation of impacts from the oil itself is likely to meet with varied success 

depending upon the type of site and availability of funding. 
A-78 Western Planning Area Lease Sale 248 Supplemental EIS

A.3.1.20. Land Use and Coastal Infrastructure

Phase 1—Initial Event

There would likely be no adverse impacts to land use and coastal infrastructure as a result of the 

events and the potential impact-producing factors that could occur throughout Phase 1 of a catastrophic 

spill event because of the long distance (>3 nmi; 3.5 mi; 5.6 km) from shore and the short duration of the 

initial event, fire, and/or explosion. 

Phase 2—Offshore Spill

Impacts to tourism and recreational resources are addressed in Chapter A.3.1.18. Possible fisheries 

closures are addressed in Chapters A.3.1.16 and A.3.1.17. As cleanup and remediation efforts evolve, 

there would be increased activity at ports and coastal cities, leading to increased traffic on road 

infrastructure and at port facilities. This follows from consideration of BOEM’s scenario estimates of up 

to 3,000 vessels, 25-50 planes/helicopters, and up to 25,000 workers for a shallow-water event and up to 

7,000 vessels, 50-100 planes/helicopters, and up to 50,000 workers for a deepwater event. Waste disposal 

activities associated with boom deployment and retrieval would increase demand at waste disposal 

facilities. BOEM’s scenario estimates 5 million feet (1.5 million meters) of boom deployment and 

35,000 bbl of dispersant applied at the surface for a shallow-water event or 11 million feet (3.4 million 

meters) of boom deployment and 33,000 bbl of dispersant applied at the surface and 16,500 bbl of 

dispersant applied subsea for a deepwater event. Also, vessel decontamination sites would be set up 

offshore and the staffing/maintenance of these sites would contribute to increased activity at port facilities 

and traffic congestion on coastal waterways and highways.

Phase 3—Onshore Contact

In the event of a catastrophic spill, impacts on land use and infrastructure would be temporary and 

variable in nature. The scale of impact would depend on the nature of the event and whether it occurs in 

shallow or deep water. These impacts would include land use in staging areas, waste disposal locations 

and capacities, and potential delays because of vessel decontamination stations near ports, as described 

below. 

For a shallow-water event, BOEM estimates 5-10 staging areas and 200-300 skimmers. For a 

deepwater event, scenario estimates call for 10-20 staging areas and 500-600 skimmers. Given these 

estimates and the several thousand responders that would be involved in the effort, BOEM expects a 

further increase in traffic congestion and some possible competing land-use issues near the staging areas, 

depending on the real estate market at the time of the event. Some infrastructure categories, such as 

vessels, ports, docks and wharves, would likely become very engaged in response activities and this could 

result in a shortage of space and functionality at infrastructure facilities if ongoing drilling activities were 

simultaneously occurring. However, if drilling were to be suspended, conflicting demands on 

infrastructure facilities would likely fail to materialize.

In the category of waste disposal, the impacts would be more visible as thousands of tons of oily 

liquid and solid wastes from the oil-spill cleanup would be disposed of in onshore landfills. As was the 

case in the Deepwater Horizon explosion, oil spill, and response, USEPA, in consultation with USCG, 

would likely issue solid-waste management directives to address the issue of contaminated materials and 

solid or liquid wastes that are recovered as a result of cleanup operations (USEPA, 2010c and 2010d). 

For navigation and port use, there would also be the potential for delays in cargo handling and slow 

vessel traffic because of decontamination operations at various sites along the marine transportation 

system (USDOT, 2010). However, vessel decontamination activities most likely would be complete 

within a year of the event, so impacts would be expected to be limited in duration. 

Phase 4—Post-Spill, Long-Term Recovery and Response 

Based on the rapid recovery of infrastructure that was heavily damaged by the catastrophic 2005 

hurricane season and the region’s experience in the few years since the Deepwater Horizon explosion, oil 

spill, and response, BOEM would not expect any long-term impacts to land use and coastal infrastructure 

as a result of a catastrophic oil-spill event. However, if a catastrophic oil spill were to occur, BOEM 
Catastrophic Spill Event Analysis A-79

would (as it is currently with regard to the Deepwater Horizon explosion, oil spill, and response) monitor 

the post-spill, long-term recovery phase of the event for any changes that indicate otherwise. A 

catastrophic spill could generate several thousand tons of oil-impacted solid materials disposed in 

landfills along the Gulf Coast. This waste may contain debris, beach, or marsh material (sand/silt/clay), 

vegetation, and personal protection equipment collected during cleanup activities. BOEM does not 

expect that landfill capacity would be an issue at any phase of the oil-spill event or the long-term 

recovery. In the case of the Deepwater Horizon explosion, oil spill, and response, USEPA reported that 

existing landfills receiving oil-spill waste had plenty of capacity to handle waste volumes; the Deepwater 

Horizon explosion, oil spill, and response’s waste that was disposed of in landfills represented less than 

7 percent of the total daily waste normally accepted at these landfills (USEPA, 2012).

It is not expected that any long-term, land-use impacts would arise from properties that are utilized 

for restoration activities and would somehow have their future economic use compromised. The rise or 

fall of property values would not be solely a function of some kind of economic impact from a 

catastrophic oil-spill event. There are many other factors that influence the value of property and its best 

economic use. To date, it is not clear from past experiences whether vegetation loss or erosion created by 

a spill could result in changes in land use. The amount and location of erosion and vegetation loss could 

be influenced by the time of year the spill occurs, its location, and weather patterns, including hurricane 

landfalls.

Overall Summary and Conclusion (Phases 1-4) 

There would likely be no adverse impacts to land use and coastal infrastructure throughout Phase 1 of 

a catastrophic spill event. Response efforts in Phases 2 and 3 would require considerable mobilization of 

equipment and people. While these efforts might temporarily displace traditional users of coastal land 

and infrastructure, these interruptions would not be long lasting. The post-spill, long-term recovery and 

response efforts during Phase 4 could generate several thousand tons of oil-impacted solid materials 

disposed in landfills along the Gulf Coast, but this likely would account for no more than 7 percent of the 

total daily waste normally accepted in these landfills. It is also not expected that any properties utilized 

for restoration activities throughout Phase 3 would suffer any long-term land use or economic impacts. 

A.3.1.21. Demographics

Phase 1—Initial Event

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter A.3.1.22). Since the impacts of a catastrophic spill on employment 

would take time to evolve, the initial impacts on demographics would be minimal. Therefore, there 

would likely be no adverse impacts to demographics as a result of the events and the potential impactproducing factors that could occur throughout Phase 1 of a catastrophic spill event.

Phase 2—Offshore Spill

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter A.3.1.22). For example, there could be some suspension of oil/gas 

activities in the immediate aftermath of the spill. This could cause some workers to seek employment 

outside of the OCS industry, for example in onshore oil/gas extraction or on overseas offshore projects. 

However, since the OCS oil and gas industry would likely eventually recover, the long-term impacts on 

demographics would be small. There could also be impacts on demographics if employment in 

recreation, tourism, or fishing industries were affected, due to either actual or perceived impacts of the 

spill. However, the impacts on these industries would become more acute if the spill were to reach shore.

Phase 3—Onshore Contact

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter A.3.1.22). For example, impacts to recreation/tourism and recreational 

and commercial fishing activities would become more acute if the spill were to reach shore. There would 

also be a larger presence of cleanup workers in some areas if the spill were to reach shore. For example, 
A-80 Western Planning Area Lease Sale 248 Supplemental EIS

48,200 workers were employed in response activities at the peak of the response effort following the 

Macondo well blowout and spill (RestoreTheGulf.gov, 2011). However, these impacts would be 

temporary and would be governed by the dynamics of the particular spill. There could also be impacts to 

demographics if there were impacts on the response workers’ health or if the demographics of the 

response workers were noticeably different from the local population.

Phase 4—Post-Spill, Long-Term Recovery and Response 

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter A.3.1.22). The spill’s impacts on employment, and therefore 

demographics, would primarily be felt in the oil/gas, recreational fishing, commercial fishing, and 

recreation/tourism industries. However, it is unlikely that a catastrophic spill would cause substantial 

long-term changes to a region’s demographics. For example, the demographics data in Woods and Poole 

Economics, Inc. (2011) did not suggest large demographic changes to any Gulf regions subsequent to the 

Deepwater Horizon explosion, oil spill, and response. 

Overall Summary and Conclusion (Phases 1-4) 

The impacts of a catastrophic spill on demographics would primarily be driven by the spill’s impacts 

on employment (refer to Chapter A.3.1.22). These impacts would likely be temporary and would be 

governed by the particular dynamics of the spill. 

A.3.1.22. Economic Factors

Phase 1—Initial Event

The most immediate economic impacts of a catastrophic spill would be on the oil/gas production and 

employment associated with the area of the spill. There could also be impacts on commercial fishing 

(Chapter A.3.1.16), recreational fishing (Chapter A.3.1.17), and recreational resources (Chapter 

A.3.1.18). However, the primary economic impacts of a catastrophic spill would depend on how the spill 

evolves, which is discussed in subsequent sections.

Phase 2—Offshore Spill

In contrast to a less severe accidental event, suspension of some oil and gas activities would be likely 

following a catastrophic event. Depending on the duration and magnitude, this could impact hundreds of 

oil-service companies that supply the steel tubing, engineering services, drilling crews, and marine supply 

boats critical to offshore exploration. An interagency economic report estimated that the suspension 

arising from the Deepwater Horizon explosion, oil spill, and response may have directly and indirectly 

resulted in up to 8,000-12,000 fewer jobs along the Gulf Coast (USDOC, Economics and Statistics 

Administration, 2010). Greater New Orleans, Inc. (2012) provides an overview of the impacts of 

decreased oil and gas industry operations subsequent to the Deepwater Horizon explosion, oil spill, and 

response. This report provides survey evidence regarding the various economic strains felt by businesses 

in Louisiana due to the Deepwater Horizon explosion, oil spill, and response. For example, this report 

found that 41 percent of the respondents were not making a profit due to the slowdown in operations. The 

economic impacts of a catastrophic spill would likely be more heavily concentrated in smaller businesses 

than in the larger companies due to their difficulty in finding substitute revenue sources. Much of the 

employment loss would be concentrated in coastal oil-service parishes in Louisiana (St. Mary, 

Terrebonne, Lafourche, Iberia, and Plaquemines Parishes) and counties/parishes where drilling-related 

employment is most concentrated (Harris County, Texas, in which Houston is located, and Lafayette 

Parish, Louisiana). There could also be economic impacts due to the impacts on commercial fishing 

(Chapter A.3.1.16), recreational fishing (Chapter A.3.1.17), and recreational resources (Chapter 

A.3.1.18).
Catastrophic Spill Event Analysis A-81

Phase 3—Onshore Contact

By the end of a catastrophic spill, a large number of personnel (up to 25,000 in the event of a shallowwater spill and up to 50,000 in the event of a deepwater spill) would be expected to have responded to 

protect the shoreline and wildlife and to cleanup vital coastlines. The degree to which new cleanup jobs 

offset job losses would vary greatly from county to county (or parish to parish). However, these new jobs 

would not make up for lost jobs, in terms of dollar revenue. In most cases, cleanup personnel are paid 

less (e.g., $15-$18 per hour compared with roughly $45 per hour on a drilling rig), resulting in consumers 

in the region having reduced incomes overall and thus, spending less money in the economy (Aversa, 

2010). In addition, the economic impacts of relief workers would likely vary by county or parish, causing 

noticeable positive economic impacts to some counties or parishes while having fairly small positive 

impacts in other counties or parishes (Murtaugh, 2010). However, the influx of relief workers could also 

cause some negative impacts if it disrupted some of the normal functioning of economies. In addition, if 

the spill reaches shore, the impacts to commercial fishing (Chapter A.3.1.16), recreational fishing 

(Chapter A.3.1.17), and recreational resources (Chapter A.3.1.18) would likely be greater.

In the unfortunate event of a future disaster, the creation of a large financial claims administration 

process, similar to the Gulf Coast Claims Facility, would be likely. This administrative body would be 

responsible for distributing funds made available by the responsible party to parties financially hurt by the 

disaster. As demonstrated by the actions of Gulf Coast Claims Facility recipients following the 

Deepwater Horizon explosion, oil spill, and response, funds will likely be used by individuals to pay for 

necessities such as mortgages or groceries, while businesses who receive funds will likely use them to 

maintain payroll and current payments on equipment. As of March 2012, over $6 billion had been paid 

through the Gulf Coast Claims Facility, which mitigated some of the economic impacts of the Deepwater 

Horizon explosion, oil spill, and response (Gulf Coast Claims Facility, 2012). 

Phase 4—Post-Spill, Long-Term Recovery and Response 

While a catastrophic spill could immediately impact several Gulf Coast States for several months 

through fishing closures, loss of tourism, and any suspension of oil and gas activities, anticipating the 

long-term economic and employment impacts in the Gulf of Mexico is a difficult task. Many of the 

potentially affected jobs, like fishing charters, are self-employed. Thus, they would not necessarily file 

for unemployment and would not be included in business establishment surveys used to estimate State 

unemployment levels. In addition, unemployment numbers in states are based on nonagricultural jobs, 

and the fishing industry is considered within the agriculture category. On the other side, it is also a 

challenge to estimate how many of these displaced workers have been hired to clean up the spill. For 

example, while thousands of vessels of opportunity would be active in the spill response, not all of these 

would be displaced commercial fishermen from the affected areas. The positive employment impacts 

related to response activities are likely to be shorter term than the negative impacts discussed above. 

However, the long-term economic impacts of a catastrophic spill will likely depend on the speed at which 

the oil/gas, commercial fishing, recreational fishing, and recreational industries recover.

Overall Summary and Conclusion (Phases 1-4) 

There would be a number of economic impacts that would arise from a catastrophic oil spill. The 

most direct effects would be on the recreation/tourism, commercial fishing, and recreational fishing 

industries that depend on damaged resources. There could also be substantial negative effects on the 

oil/gas industry due to moratoriums or rule changes that would arise. Finally, there could be substantial 

impacts due to the relief operations and economic mitigation activities that would occur in the aftermath 

of a catastrophic spill.

A.3.1.23. Environmental Justice

Phase 1—Initial Event

There would likely be no adverse impacts to environmental justice as a result of the events and the 

potential impact-producing factors that could occur throughout Phase 1 of a catastrophic spill event 
A-82 Western Planning Area Lease Sale 248 Supplemental EIS

because of the long distance (>3 nmi; 3.5 mi; 5.6 km) from shore and the short duration of the initial 

event, fire, and/or explosion. 

Phase 2—Offshore Spill

The environmental justice policy, based on Executive Order 12898 of February 11, 1994, directs 

agencies to incorporate into NEPA documents an analysis of potentially disproportionate and detrimental 

environmental and health effects of their proposed actions on minorities and low-income populations and 

communities. While the spill is still offshore, the primary environmental justice concern would be large 

commercial fishing closures disproportionately impacting minority fishers. In the event of a catastrophic 

spill, Federal and State agencies would be expected to close substantial portions of the Gulf to 

commercial and recreational fishing (USDOC, NOAA, 2010e). While oystering occurs “onshore,” oyster 

beds are also likely to be closed to harvests during Phase 2 of a catastrophic spill because of concerns 

about oil contamination and increased freshwater diversions to mitigate oil intrusion into the marshes. 

These closures would directly impact commercial fishermen and oystermen, and indirectly impact such 

downstream activities as shrimp processing facilities and oyster shucking houses. The mostly AfricanAmerican communities of Phoenix, Davant, and Point a la Hache in Plaquemines Parish, Louisiana, are 

home to families with some of the few black-owned oyster leases. Just as these leases have been 

threatened by freshwater diversion projects for coastal restoration, they could be threatened by Phase 2 of 

a catastrophic spill (Mock, 2010). 

The Gulf Coast hosts multiple minority and low-income groups whose use of natural resources of the 

offshore and coastal environments make them vulnerable to fishing closures. While not intended as an 

inventory of the area’s diversity, we have identified several Gulf Coast populations of particular concern. 

An estimated 20,000 Vietnamese American fishermen and shrimpers live along the Gulf Coast; by 1990, 

over 1 in 20 Louisiana fishers and shrimpers had roots in Southeast Asia even though they comprised less 

than half a percent of the State’s workforce (Bankston and Zhou, 1996). Vietnamese Americans account 

for about one-third of all the fishermen in the central Gulf of Mexico (Ravitz, 2010). Islaños, African 

Americans, and Native American groups are also engaged in commercial fishing and oystering. 

Historically, Vietnamese Americans and African Americans have worked in the fish processing and 

oyster shucking industries. Shucking houses particularly, have provided an avenue into the mainstream 

economy for minority groups. 

Therefore, fishing closures during Phase 2 of a catastrophic spill impacting the central Gulf of 

Mexico may disproportionately affect such minority groups as the Vietnamese Americans, Native 

Americans, African Americans, and Islaños (Hemmerling and Colten, 2003). 

Phase 3—Onshore Contact

While most coastal populations along the Gulf Coast are not generally minority or low income, 

several communities on the coasts of St. Mary, Lafourche, Terrebonne, St. Bernard, and Plaquemines 

Parishes, Louisiana, have minority or low-income population percentages that are higher than their state 

average. These minority populations are predominately Native American, Islaños, or African American. 

For example, a few counties or parishes along the Gulf Coast have more than a 2-percent Native 

American population (USDOI, MMS, 2007); about 2,250 Houma Indians (a State of Louisiana 

recognized tribe) are concentrated in Lafourche Parish, Louisiana, comprising 2.4 percent of the parish’s 

population, and about 800 Chitimacha (a federally recognized tribe) make up 1.6 percent of St. Mary 

Parish’s population. While these are not significant numbers on their own, viewed in the context of 

Louisiana’s overall 0.6 percent Native American average, these communities take on greater 

environmental justice importance.

Gulf Coast minority and low-income groups are particularly vulnerable to the coastal impacts of a 

catastrophic oil spill due to their greater than average dependence on the natural resources in the offshore 

and coastal environments. Besides their economic reliance on commercial fishing and oystering, coastal 

low-income and minority groups rely heavily on these fisheries and other traditional subsistence fishing, 

hunting, trapping, and gathering activities to augment their diets and household incomes (refer to 

Hemmerling and Colton, 2003, for an evaluation of environmental justice considerations for south 

Lafourche Parish). Regular commuting has continued this reliance on the natural resources of the coastal 
Catastrophic Spill Event Analysis A-83

environments even when populations have been forced to relocate because of landloss and the destruction 

from hurricane events.

State fishery closures because of a catastrophic oil spill could disproportionately affect minority and 

low-income groups. Shoreline impacts could generate additional subsistence-related effects. Therefore, 

these minority groups may be disproportionately affected if these coastal areas were impacted by a 

catastrophic spill and the resulting response.

Phase 4—Post-Spill, Long-Term Recovery and Response

After the spill is stopped, the primary environmental justice concerns relate to possible long-term 

health impacts to cleanup workers, a predominately minority population, and to possible disposal of oilimpacted solid waste in predominantly minority areas.

An analysis of socioeconomic characteristics shows that people of Cajun ethnicity in the Gulf Coast 

States are often found to be of a comparatively low socioeconomic status and to work jobs in the textile 

and oil industries (Henry and Bankston, 1999). Past studies suggest that a healthy offshore petroleum 

industry also indirectly benefits low-income and minority populations (Tolbert, 1995). One BOEMfunded study in Louisiana found income inequality decreased during the oil boom of the 1980’s and 

increased with the decline (Tolbert, 1995). If there is a suspension of oil and gas activities in response to 

a catastrophic spill, many oil- and gas-related service industries would attempt to avoid massive layoffs 

by cutting costs and deferring maintenance during the recovery. This was the case with the Deepwater 

Horizon explosion, oil spill, and response, and the long-term impacts are still not fully understood.

Onshore and Offshore Cleanup Workers 

By the end of a catastrophic spill, up to 25,000 (shallow water) or 50,000 (deepwater) personnel 

would be expected to be responding to the spill. The majority of these would be field responders (United 

Incident Command, 2010e). As seen by the Deepwater Horizon explosion, oil spill, and response, the 

racial composition of cleanup crews was so conspicuous that Ben Jealous, the president of the National 

Association for the Advancement of Colored People, sent a public letter to BP Chief Operations Officer 

Tony Hayward on July 9, 2010, demanding to know why African Americans were over-represented in 

“the most physically difficult, lowest paying jobs, with the most significant exposure to toxins” (National 

Association for the Advancement of Colored People, 2010). While regulations require the wearing of 

protective gear and only a small percentage of cleanup workers suffer immediate illness and injuries 

(Center for Disease Control and Prevention, 2010), exposure could have long-term health impacts (e.g., 

increased rates of some types of cancer) (Savitz and Engel, 2010; Kirkeleit et al., 2008). Aguilera et al. 

(2010) compiled and reviewed existing studies on the repercussions of spilled oil exposure on human 

health for patterns of health effects and found evidence of the relationship between exposure and “acute 

physical, psychological, genotoxic, and endocrine effects in the exposed individuals.” Acute symptoms 

from exposure to oil, dispersants, and degreasers include headaches, nausea, vomiting, diarrhea, sore 

eyes, runny nose, sore throat, cough, nose bleeds, rash, blisters, shortness of breath, and dizziness 

(Sathiakumar, 2010). The USEPA’s monitoring data have not shown that the use of dispersants during 

the Deepwater Horizon explosion, oil spill, and response resulted in a presence of chemicals that 

surpassed human health benchmarks (Trapido, 2010). The potential for the long-term human health 

effects are largely unknown. However, the National Institute of Environmental Health Sciences is 

conducting a study known as the “Gulf Long-Term Follow-Up Study” that should provide a better 

understanding of the long-term and cumulative health impacts, such as the consequences of working close 

to a spill and of consuming contaminated seafood. The “Gulf Long-Term Follow-up Study” will monitor 

oil-spill cleanup workers for 10 years and represents a national effort to determine if the Gulf oil spill led 

to physical or mental health problems (U.S. Dept. of Health and Human Services, NIEHS, 2010). The 

study has a target goal of 55,000 participants. As of October 2012, the National Institute of 

Environmental Health Sciences announced that over 29,000 cleanup workers and volunteers have 

enrolled in the “Gulf Long-Term Follow-up Study” (U.S. Dept. of Health and Human Services, NIEHS, 

2012). Prior research on post-spill cleanup efforts found that the duration of cleaning work was a risk 

factor for acute toxic symptoms and that seamen had the highest occurrence of toxic symptoms compared 

with volunteers or paid workers. Therefore, participants in the “Vessels of Opportunity” program, which 

recruited local boat owners (including Cajun, Houma Indian, and Vietnamese American fishermen) to 
A-84 Western Planning Area Lease Sale 248 Supplemental EIS

assist in cleanup efforts, would likely be one of the most exposed groups. African Americans are thought 

to have made up a high percentage of the cleanup workforce. The Occupational Safety and Health 

Administration (OSHA) released two matrices of gear requirements for onshore and offshore Gulf 

operations that were organized by task (U.S. Dept. of Labor, OSHA, 2010a). Of past oil-spill workers, 

uninformed and poorly informed workers were at more risk of exposure and symptoms, demonstrating the 

importance of education and proper training of workers (Sathiakumar, 2010). Therefore, a catastrophic 

spill may disproportionately affect seamen and onshore workers such as Cajuns, Vietnamese Americans, 

Houma Indian, and African Americans. 

Solid-Waste Disposal 

Following a catastrophic spill, environmental justice concerns arise related to the disposal of cleanuprelated wastes near minority and/or low-income communities (Schleifstein, 2010). It is estimated that a 

catastrophic spill could generate several thousand tons of oil-impacted solid materials that would be 

disposed in landfills along the Gulf Coast. While no new landfills would be built because of a 

catastrophic spill, the use of existing landfills might exacerbate existing environmental justice issues. For 

example, Mobile, Alabama, and Miami, Florida, are majority minority urban centers with a majority of 

minority residents living within a 1-mi (1.6-km) radius of chosen landfills or liquid processing centers. 

While only a small percentage of Deepwater Horizon explosion, oil spill, and response waste was sent to 

these facilities—13 percent of the liquid waste to Liquid Environmental Solutions in Mobile and only 

0.28 percent of the total liquid waste to Cliff Berry in Miami—they may receive more from potential 

future spills. Disposal procedures for the Deepwater Horizon explosion, oil spill, and response involved 

sorting waste materials into standard “waste stream types” at small, temporary stations, and then sending 

each type to existing facilities that were licensed to dispose of them. The location of temporary sorting 

stations was linked to the location of containment and cleanup operations. Hence, future locations of any 

sorting stations are not predictable since they would be determined by the needs of cleanup operations. 

However, waste disposal locations were determined by the specializations of existing facilities and by 

contractual relationships between them and the cleanup and containment firms. Louisiana received about 

82 percent of the Deepwater Horizon explosion, oil spill, and response liquid waste recovered; of this, 

56 percent was manifested to mud facilities located in Venice in Plaquemines Parish, Louisiana, and to 

Port Fourchon in Lafourche Parish, Louisiana, and then transferred to a processing facility in Port Arthur, 

Texas. The waste remaining after processing was sent to deep well injection landfills located in Fannett 

and Big Hill, Texas. The sites located in Venice and Port Fourchon, Louisiana, and in Port Arthur, 

Fannett, and Big Hill, Texas, have low-minority populations, but a few of these areas have substantial 

poverty rates relative to State and parish/county means.

Overall Summary and Conclusion (Phases 1-4) 

For Phase 1 (Initial Event) of a catastrophic spill, there would likely be no adverse impacts to 

minority and low-income communities because of the long distance (>3 nmi; 3.5 mi; 5.6 km) from shore, 

as well as the short duration of the initial event, fire, and/or explosion. The primary environmental justice 

concerns during Phase 2 (Offshore Spill) would be large-scale fishing closures, oyster bed contamination 

and closures, and subsequent impacts to downstream activities such as shrimp processing facilities and 

oyster shucking houses. These may disproportionately affect such minority groups as the Vietnamese 

Americans, Native Americans, African Americans, and Islaños. Phase 3 (Onshore Contact), depending 

on the location, could result in disproportional impacts to those groups that rely heavily on oystering, 

commercial fishing, and other traditional subsistence fishing, hunting, trapping, and gathering activities to 

augment their diets and household incomes. During Phase 4 (Post-Spill, Long-Term Recovery and 

Response), the primary environmental justice concerns relate to possible long-term health impacts to 

cleanup workers, a predominately minority population, and to the possible disposal of oil-impacted solid 

waste in predominantly minority areas. As in the case of the Deepwater Horizon explosion, oil spill, and 

response, understanding long-term impacts would be dependent on the outcome of ongoing research by 

various interested parties, such as the National Institutes of Health and BOEM. Overall, depending on a 

number of mainly geographic variables such as the location of fisheries closures and oyster bed 

contamination and closures, as well as the demographic composition of cleanup workers, and if waste 
Catastrophic Spill Event Analysis A-85

disposal was not distributed across the region at many different facilities, a catastrophic oil-spill event 

may have disproportionate effects on minority and low-income populations. 

A.3.1.24. Species Considered due to U.S. Fish and Wildlife Service Concerns

Phase 1—Initial Event

Phase 1 of the scenario is the initiation of a catastrophic blowout incident. Impacts, response, and 

intervention depend on the spatial location of the blowout and leak. For this analysis, an explosion and 

subsequent fire are assumed to occur. If a blowout associated with the drilling of a single exploratory 

well occurs, this could result in a fire that would burn for 1 or 2 days. If a blowout occurs on a production 

platform, other wells could feed the fire, allowing it to burn for over a month. The drilling rig or platform 

may sink. If the blowout occurs in shallow water, the sinking rig or platform may land in the immediate 

vicinity; if the blowout occurs in deep water, the rig or platform could land a great distance away, beyond 

avoidance zones. Regardless of water depth, the immediate response would be from search and rescue 

vessels and aircraft, such as USCG cutters, helicopters, and rescue planes, and firefighting vessels. The 

potential impacts reflect the explosion, subsequent fire for 1-30 days, and the sinking of the platform in 

the immediate vicinity and up to 1 mi (1.6 km) from the well. 

The scenarios for each phase, including cleanup methods, can be found Table A-4. 

BOEM has only focused on species within coastal counties and parishes because those are the species 

that could be potentially impacted by oil and gas development activities, including a potential OCS spill. 

There would likely be no adverse impacts to the species considered due to FWS concerns as a result of

the events and the potential impact-producing factors that could occur throughout Phase 1 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements. 

Phase 2—Offshore Spill

Phase 2 of the analysis focuses on the spill and response in Federal and State offshore waters. A 

catastrophic spill would likely spread hundreds of square miles. Also, the oil slick may break into several 

smaller slicks, depending on local wind patterns that drive the surface currents in the spill area. The 

potential impacts reflect spill and response in Federal and State offshore waters. Season and temperature 

variations can result in different resource impacts due to variations in oil persistence and oil and 

dispersant toxicity and because of differences in potential exposure of the resources throughout various 

life cycle stages.

There would likely be no adverse impacts to the species considered due to FWS concerns as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 2 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements. 

Phase 3—Onshore Contact

Phase 3 focuses on nearshore (e.g., inside bays and in close proximity to shoreline) and onshore spill 

response and oil initially reaching the shoreline during the spill event or while the oil still persists in the 

offshore environment once the spillage has been stopped. It is likely that Phases 2 and 3 could occur 

simultaneously. The duration of the initial shoreline oiling is measured from initial shoreline contact until 

the well is capped or killed and the remaining oil dissipates offshore. Re-oiling of already cleaned or 

previously impacted areas could be expected during Phase 3. In addition to the response described in 

Phase 2, nearshore and onshore efforts would be introduced in Phase 3 as oil entered coastal areas and 

contacted shore. The potential impacts reflect the spill and response in very shallow coastal waters and 

once along the shoreline. Season and temperature variations can result in different resource impacts due 

to variations in oil persistence and oil and dispersant toxicity and because of differences in potential 

exposure of the resources throughout various life cycle stages.

The FWS has explicitly communicated interest in specific species within State boundaries along the 

Gulf Coast. The species within Louisiana, Mississippi, Alabama, and Florida have been designated as 

endangered, threatened, candidate, listed with critical habitat, proposed nonessential experimental 

population, or distinct vertebrate population. The greatest threats to the majority of these species are the 
A-86 Western Planning Area Lease Sale 248 Supplemental EIS

loss of and/or modification to suitable habitat caused by urban and agricultural development. Further 

detail on this catastrophic OSRA run is contained in Appendix C of the WPA 238/246/248 Supplemental 

EIS.

At this time, there is no known record of a hurricane crossing the path of a large oil spill; the impacts 

of such have yet to be determined. The experience from Hurricanes Katrina and Rita in 2005 was that the 

oil released during the storms widely dispersed as far as the surge reached (USDOC, NOAA, National 

Weather Service, 2012). Due to their reliance on terrestrial habitats to carry out their life-history 

functions at a considerable distance from the GOM, the activities of a WPA proposed action are unlikely 

to have significant adverse effects on the size and recovery of any of the FWS-mentioned species or 

populations in Texas, Louisiana, Mississippi, Alabama, and Florida. 

There would likely be no adverse impacts to the species considered due to FWS concerns as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 3 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements. 

Phase 4—Post-Spill, Long-Term Recovery and Response 

Phase 4 focuses on long-term recovery once the well has been capped and the spill has stopped. 

During the final phase of a catastrophic blowout and spill, it is presumed that the well has been capped or 

killed and cleanup activities are concluding. While it is assumed that the majority of spilled oil would be 

dissipated offshore within 1-2 months (depending on season and temperature) of stopping the flow, oil 

has the potential to persist in the environment long after a spill event and has been detected in sediment 

30 years after a spill. On sandy beaches, oil can sink deep into the sediments. In tidal flats and salt 

marshes, oil may seep into the muddy bottoms. The potential impacts reflect long-term persistence of oil 

in the environment and residual and long-term cleanup efforts.

There would likely be no adverse impacts to the species considered due to FWS concerns as a result 

of the events and the potential impact-producing factors that could occur throughout Phase 4 of a 

catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure and 

pipelines, and permitting and siting requirements. 

Overall Summary and Conclusion (Phases 1-4) 

Blowouts, oil spills, and spill-response activities resulting from a catastrophic event have the potential 

to impact small to large areas in the GOM, depending on the location and date of the accident, the ability 

to respond to the accident, and various meteorological and hydrological factors (including tropical 

storms). Species within coastal areas could be potentially impacted by a catastrophic spill; however, there 

would likely be no adverse impacts to the species considered due to FWS concerns throughout all phases 

of a catastrophic spill event due to the distance of most activities, the heavy regulation of infrastructure 

and pipelines, and permitting and siting requirements; in comparison, non-OCS oil- and gas-related 

activities, such as habitat loss and competition, have historically proved to be of greater threat to the 

FWS-mentioned species. 

A.4. PREPARERS

Pat Adkins, Information Management Specialist 

Bruce Baird, Biologist 

Mark Belter, Marine Biologist

Darice K. Breeding, Environmental Protection Specialist 

Alicia Caporaso, Marine Archaeologist

Sindey Chaky, Environmental Protection Specialist 

Chris DuFore, Oceanographer

Stephanie Gambino, Chief, Biological/Social Sciences Section 

Donald (Tre) W. Glenn III, Protected Species Biologist 

Gary D. Goeke, Chief, Environmental Assessment Section

Allison Hernandez, Protected Species Biologist 

Jose Hernandez, Physical Scientist
Catastrophic Spill Event Analysis A-87

Chester Huang, Meteorologist 

Jack Irion, Unit Supervisor, Marine Archaeologist, Social Sciences Unit

Mark D. Jensen, Economist

Matthew Johnson, Marine Biologist

Douglas Jones, Senior Marine Archaeologist

Arie R. Kaller, Unit Supervisor, Environmental Scientist, Biological Sciences Unit 

Lissa Lyncker, Unit Supervisor, Environmental Scientist, Environmental Assessment Section 

Paula (Kaye) London, Protected Species Biologist

Charles (Jay) McCreery, Physical Scientist

Tershara Matthews, Unit Supervisor, Environmental Scientist, Environmental Assessment Section

Margaret Metcalf, Chief, Physical/Chemical Sciences Unit

Deborah H. Miller, Technical Editor

Megan Biven, Economist 

David P. Moran, Biologist 

Mark Mueller, Marine Ecologist

Catherine A. Rosa, Environmental Assessment Program Specialist

Toby Wraye, Information Management Specialist 

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Wiese, F.K. and I.L. Jones. 2001. Experimental support for a new drift block design to assess seabird 

mortality from oil pollution. Auk 118:1062-1068. 

Wiese, F.K., W.A. Montevecchi, G.K. Davoren, F. Huettman, A.W. Diamond, and J. Linke. 2001. 

Seabirds at risk around offshore oil platforms in the Northwest Atlantic. Marine Pollution Bulletin 

42:1285-1290. 

Wilhelm, S.I., G.J. Robertson, P.C. Ryan, and D.C. Schneider. 2007. Comparing an estimate of seabirds 

at risk to a mortality estimate from the November 2004 Terra Nova FPSO oil spill. Marine Pollution 

Bulletin 54:537-544. 

Williams, B.K. 2011. Adaptive management of natural resources-framework and issues. Journal of 

Environmental Management 92:1346-1353. 

Williams, J.M., M.L. Tasker, I.C. Carter, and A. Webb. 1995. A method of assessing seabird 

vulnerability to surface pollutants. Ibis 137:S147-S152. 

Williams, R., S. Gero, L. Bejder, J. Calambokidis, S. Kraus, D. Lusseau, A. Read, and J. Robbins. 2011. 

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Wood, R.C. and L.S. Hales. 2001. Comparison of northern diamondback terrapin (Malaclemys terrapin

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(CEDDS) on CD-ROM.

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and H.F. Percival, eds. Population biology of the Florida manatee. National Biological Service 

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Catastrophic Spill Event Analysis A-113

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of chemically dispersed oil and subsequent recovery in Diploria strigosa. Marine Ecology 7:23-42. 

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default/files/Oil_Spill_Coral.pdf. Accessed December 16, 2011. 

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reduce the negative effects of acute pollution on adult survival by skipping breeding? A study with 

European storm petrels (Hydrobates pelagicus) during the Prestige oil-spill. Marine Pollution 

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ecosystems. In: Cairns, J., Jr. and A.L. Buikema, Jr., eds. Restoration of habitats impacted by oil 

spills. Boston, MA: Butterworth Publishers. 

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Pollution Bulletin 52:1176-1181. 
A-114 Western Planning Area Lease Sale 248 Supplemental EIS

Figure A-1. Location of Five Hypothetical Oil-Spill Launch Points for OSRA within the Study Area. (Spatial 

variability of the Loop Current is from Vukovich [2007] and is shown as percent of time that the Loop 

Current watermass is associated with a particular location.)
Catastrophic Spill Event Analysis A-115

Figure A-2. Spatial Frequency (%) of the Watermass Associated with the Loop Current in the Eastern Gulf of 

Mexico based on Data for the Period 1976-2003 (Vukovich, 2005).
A-116 Western Planning Area Lease Sale 248 Supplemental EIS

Figure A-3. Summary of Avian Species Collected by Date Obtained from the U.S. Fish and Wildlife Service as 

Part of the Deepwater Horizon Post-Spill Monitoring and Collection Process through May 12, 2011 

(USDOI, FWS, 2011a). (This figure represents the date the data were released and reported and does 

not represent the actual date individual birds were collected. Data on the Y-axis reflect the 

cumulative # of individual birds collected, identified, and summarized by date; data on the Z-axis 

reflect proportional change from one reporting date to the next. The data used in this figure are 

verified as per FWS’s QA/QC processes. The mean # of birds collected between intervals is 

184.4 + 89.3 SE [-807 min, 526 max for 13 collection intervals] and the mean % change between 

intervals is 3.0 + 1.3% [-11.12% min., 8.27% max]. We have no data on change in search effort 

temporally (or spatially) and also lack data prior to September 14, 2010; therefore, data at that point 

represent the baseline or “0” for determining interval differences. Disclaimer: All data should be 

considered provisional, incomplete, and subject to change. For more information, refer to FWS’s 

Weekly Bird Impact Data and Consolidated Wildlife Reports [USDOI, FWS, 2011a]; for additional 

information on the chronological change in number of birds collected, refer to Belanger et al., 2010).
Catastrophic Spill Event Analysis A-117

Table A-1

Blowout Scenarios and Key Differences in Impacts, Response, and/or Intervention

Location of Blowout and Leak Key Differences in Impacts, Response, and/or Intervention

Blowout occurs at the sea surface 

(i.e., at the rig)

Offers the least chance for oil recovery because of the restricted access to the 

release point; therefore, greater impacts to coastal ecosystems. In addition to 

relief wells, there is potential for other intervention measures such as capping 

and possible manual activation of blowout-preventer (BOP) rams.

Blowout occurs along the riser 

anywhere from the seafloor to the 

sea surface. However, a severed 

riser would likely collapse, 

resulting in a leak at the seafloor.

In deep water, the use of subsea dispersants, if approved, may reduce impacts 

to coastal ecosystems; however, their use may increase exposure of deepwater 

marine resources to dispersed oil. There is a possibility for limited recovery of 

oil at the source. In addition to relief wells, there is potential for other 

intervention measures, such as capping and possible manual activation of BOP 

rams.

At the seafloor, through leak paths 

on the BOP/wellhead

In deep water, the use of subsea dispersant, if approved, may reduce impacts to 

coastal ecosystems; however, their use may increase exposure of deepwater 

marine resources to dispersed oil.

With an intact subsea BOP, intervention may involve the use of drilling mud to 

kill the well. If the BOP and well stack are heavily compromised, the only 

intervention method may be relief wells. Greatest possibility for recovery of 

oil at the source, until the well is capped or killed.

Below the seafloor, outside the 

wellbore (i.e., broached)

Disturbance of a large amount of sediments resulting in the burial of benthic 

resources in the immediate vicinity of the blowout. The use of subsea 

dispersants would likely be more difficult (PCCI Marine and Environmental 

Engineering, 1999). Stopping this kind of blowout would probably involve 

relief wells. Any recovery of oil at the seabed would be very difficult.
A-118 Western Planning Area Lease Sale 248 Supplemental EIS

Table A-2

Properties and Persistence by Oil Component Group

Properties and 

Persistence Light-Weight Medium-Weight Heavy-Weight

Hydrocarbon 

Compounds

Up to 10 carbon atoms 10-22 carbon atoms >20 carbon atoms

API o >31.1o 31.1o-22.3o <22.3o

Evaporation Rate Rapid (within 1 day) and 

complete

Up to several days; not 

complete at ambient 

temperatures

Negligible

Solubility in Water High Low (at most a few 

milligrams/liter)

Negligible

Acute Toxicity High because of 

monoaromatic 

hydrocarbons (BTEX) 

Moderate because of 

diaromatic hydrocarbons 

(naphthalenes—2 ring 

PAHs)

Low except because of 

smothering (i.e., heavier oils 

may sink)

Chronic Toxicity None, does not persist 

because of evaporation

PAH components (e.g., 

naphthalenes—2 ring 

PAHs)

PAH components (e.g., 

phenanthrene, anthracene—

3 ring PAHs)

Bioaccumulation 

Potential

None, does not persist 

because of evaporation

Moderate Low, may bioaccumulate 

through sediment sorption

Compositional 

Majority

Alkanes and cycloalkanes Alkanes that are readily 

degraded

Waxes, asphaltenes, and 

polar compounds (not 

significantly bioavailable or 

toxic)

Persistence Low because of 

evaporation

Alkanes readily degrade, 

but the diaromatic 

hydrocarbons are more 

persistent

High; very low degradation 

rates and can persist in 

sediments as tarballs or 

asphalt pavements

API = American Petroleum Institute.

BTEX = benzene, ethylbenzene, toluene, and xylene

PAH = polycyclic aromatic hydrocarbon

Sources: Michel, 1992; Canadian Center for Energy Information, 2010.
Catastrophic Spill Event Analysis A-119

Table A-3

Annual Volume of Produced Water Discharged by Depth

(millions of barrels)

Year Shelf

0-60 m

Shelf

60-200 m

Slope

200-400 m

Deepwater

400-800 m

Deepwater

800-1,600 m

UltraDeepwater

1,601-2,400 m

UltraDeepwater

>2,400 m

Total

2000 370.6 193.1 35.5 25.6 12.2 0.0 0.0 637.0

2001 364.2 185.2 35.0 32.0 16.6 0.0 0.0 633.0

2002 344.6 180.4 32.5 35.2 21.4 0.0 0.0 614.1

2003 359.4 182.9 31.2 39.0 35.5 0.2 0.0 648.2

2004 346.7 160.5 29.3 36.9 39.2 1.9 0.0 614.5

2005 270.1 113.5 23.1 33.5 43.0 5.8 0.0 489.0

2006 260.3 99.7 20.6 35.1 61.5 12.4 0.0 489.6

2007 307.0 139.4 22.2 40.0 70.3 15.5 0.1 594.5

2008 252.7 118.6 15.9 32.7 60.1 16.5 0.1 496.6

2009 263.9 108.3 19.9 39.2 65.3 25.0 0.1 521.7

Source: USDOI, BOEMRE, 2010b.
 A-120 Western Planning Area Lease Sale 248 Supplemental EIS

Table A-4 

Description of the Scenario for a Catastrophic Spill Event Occurring in Shallow Water or Deep Water 

(assumptions are described in detail in the text)

Scenario Shallow-Water Location Deepwater Location

Phase 1. Initial Event

Vertical Location of Blowout 4 possible locations including sea surface, along 

the riser, at the seafloor, and below the seafloor

4 possible locations including sea surface, along the riser, at 

the seafloor, and below the seafloor

Duration of Uncontrolled Fire 1-30 days 1-30 days

Phase 2. Offshore Spill

Duration of Spill 2-5 months 4-6 months

Rate of Spill 30,000 bbl per day* 30,000-60,000 bbl per day

Total Volume of Spill (1) 0.9-3.0 MMbbl crude oil 2.7-7.2 MMbbl crude oil

10,000-20,000 bbl diesel fuel 

APIo Gravity Fresh oil will float (APIo >10) Fresh oil will float (APIo >10)

Characteristics of Oil Released Typical South Louisiana midrange paraffinic 

sweet crude oil

Typical South Louisiana midrange paraffinic sweet crude 

oil; crude properties changed after oil traveled up the 

wellbore and passed through the water column, undergoing 

rapid depressurization and turbulence. Oil reached the 

surface as an emulsion stripped of many of its volatile 

components.

Response

Number of Vessels Up to 3,000 Up to 7,000

Number of Workers Up to 25,000 Up to 50,000

Number of Planes/Helicopters 25/50 50/100

Boom (million feet) 5 13.5

Dispersant Application

(surface application) (2)

35,000 bbl 33,000-bbl surface application and 16,500-bbl subsea 

application 

Number of Miles of Shoreline 

Requiring Some Measure of 

Mechanical or Manual Cleaning

778 778

In-situ Burn Yes, will occur Yes, will occur

Vessel Decontamination Stations Yes Yes

Severe Weather The potential for severe weather is noted, which 

could temporarily halt containment and response 

efforts.

The potential for severe weather is noted, which could 

temporarily halt containment and response efforts.

Fisheries Closure During the peak, anticipate approximately 37% or 

88,522 mi2 (229,270 km2) closed to recreational 

and commercial fishing.

During the peak, anticipate approximately 37% or 

88,522 mi2 (229,270 km2) closed to recreational and 

commercial fishing.
Catastrophic Spill Event Analysis

A-121

Table A-4. Description of the Scenario for a Catastrophic Spill Event Occurring in Shallow Water or Deep Water (continued).

Scenario Shallow-Water Location Deepwater Location

Phase 3. Onshore Contact

Shoreline Oiling Duration 1-5 months 3-6 months

Response

Number of Staging areas 5-10 10-20

Number of Skimmers 200-300 500-600

Length of Shoreline Contacted

30 days1 = 0-50 miles2 30 days1 = 0-50 miles2

60 days = 50-100 miles 60 days = 50-100 miles

90 days = 100-1,000 miles 90 days = 100-1,000 miles

120 days = >1,000 miles 120 days = >1,000 miles 1 Not cumulative.

2 Length was extrapolated.

Oil Characteristics and Appearance —Essentially stable emulsions mixed with sand.

—Typically initially stranded as surface layers and 

as discrete droplets/summer 2010.

—Essentially stable emulsions mixed with sand.

—Typically initially stranded as surface layers and as 

discrete droplets/summer 2010.

Response Considerations for Sand 

Beaches

—No mechanical techniques allowed in some 

areas.

—Much of the beach cleanup conducted at night.

—Typically sand sieving, shaking, and sifting 

beach cleaning machines.

—Repetitive tilling and mixing using agriculture 

plows and discs in combination with beach 

cleaning machines.

—Sand washing treatment—sand sieve/shaker to 

remove debris and large oil particles and heated 

washing systems.

—Nearshore submerged oil difficult to recover 

and hard to locate; vacuums and snares could be 

used.

—No mechanical techniques allowed in some areas.

—Much of the beach cleanup conducted at night.

—Typically sand sieving, shaking, and sifting beach 

cleaning machines.

—Repetitive tilling and mixing using agriculture plows and 

discs in combination with beach cleaning machines.

—Sand washing treatment—sand sieve/shaker to remove 

debris and large oil particles and heated washing systems.

—Nearshore submerged oil difficult to recover and hard to 

locate; vacuums and snares could be used.

Response Considerations for Marshes —Lightly oiled—allowed to recover naturally; 

degrade in place or removed by tidal or wave 

action.

—Moderately/heavily oiled—vacuumed or 

skimmed from boats possibly in conjunction with 

flushing; low-pressure flushing (with water 

comparable to marsh type); manual removal by 

—Lightly oiled—allowed to recover naturally; degrade in 

place or removed by tidal or wave action.

—Moderately or heavily oiled—vacuumed or skimmed 

from boats possibly in conjunction with flushing; lowpressure flushing (with water comparable to marsh type); 

manual removal by hand or mechanized equipment; and 

vegetation cutting.
 A-122 Western Planning Area Lease Sale 248 Supplemental EIS

Table A-4. Description of the Scenario for a Catastrophic Spill Event Occurring in Shallow Water or Deep Water (continued).

hand or mechanized equipment; and vegetation 

cutting.

—Heavily oiled areas—in-situ burning may be an 

option if water covers the sediment surface.

—Bioremediation may be utilized but mostly as a 

secondary treatment after bulk removal. 

—Heavily oiled areas—in-situ burning may be an option if 

water covers the sediment surface.

—Bioremediation may be utilized but mostly as a 

secondary treatment after bulk removal.

Response Considerations for 

Nearshore Waters

Marsh areas—skimming and vacuum (in areas too 

shallow to use skimmers) systems used in 

conjunction with flushing, and booming to 

temporarily contain mobile slicks.

Marsh areas—skimming and vacuum (in areas too shallow 

to use skimmers) systems used in conjunction with flushing, 

and booming to temporarily contain mobile slicks.

Phase 4. Recovery Phase

Response

Number of Vessels 

– 24-36 months post-spill/greater 

than 36 months

Fewer than 10/0 designated—called up only if 

new residual oil reported 

Fewer than 10/0 designated—called up only if new residual 

oil reported

Number of Workers 

– 24-36 months post-spill/greater 

than 36 months

230/0 designated—called up only if new residual 

oil reported 

230/0 designated—called up only if new residual oil 

reported

Miles of Shoreline Undergoing 

Regular Patrolling and 

Maintenance 

– 30-36 months post-spill/greater 

than 36 months

Fewer than 20/0 Fewer than 20/0

End Date for Dispersant 

Application

No dispersant usage 2 weeks after spillage ends No dispersant usage 2 weeks after spillage ends

Remaining Sources of Unrecoverable 

Weathered Oil

Buried or in surface pockets in coastal sand, 

sediment, or muddy bottoms and in pockets on the 

seafloor.

Buried or in surface pockets in coastal sand, sediment, or 

muddy bottoms and in pockets on the seafloor.

Oil Characteristics and Appearance As stranded oil weathered, some became buried 

through natural beach processes and appeared as 

surface residual balls (SRB) <10 cm (4 in) or as 

patties (SRP) 10 cm-1 m (4 in-3 ft).

As stranded oil weathered, some became buried through 

natural beach processes and appeared as surface residual 

balls (SRB) <10 cm (4 in) or as patties (SRP) 10 cm-1 m 

(4 in-3 ft).

Response Considerations for Sand 

Beaches, Marshes, and Nearshore 

Waters

See Phase 3 above. See Phase 3 above.

(1) A blowout may contain crude oil, natural gas, and condensate. Because the majority of environmental damage is due to the release of oil, this text 

assumes the spill to be an oil spill. However, a natural gas release would result in a less visible and less persistent adverse impact than an oil release.

(2) Subsea dispersal application must be individually approved.

Source: British Petroleum, 2014b.
Catastrophic Spill Event Analysis

A-123

Table A-5 

Birds Collected and Summarized by the U.S. Fish and Wildlife Service: 

Post-Deepwater Horizon Explosion, Oil Spill, and Response in the Gulf of Mexico1, 2

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4 Dead Alive Total Dead Alive Total Dead Alive Total

Amer. Coot Marsh/Wading 3 2 2 2 0 0 0 1 0 1 0.67

Amer. Oystercatcher Shorebird 13 7 3 7 3 0 3 1 3 3 0.54

Amer. Redstart Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Amer. White Pelican Seabird 19 5 3 8 4 0 4 4 8 7 0.42

Audubon’s Shearwater Seabird 36 1 1 1 35 0 35 0 2 0 0.03

Barn Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Barn Swallow Passerine 1 1 0 1 0 0 0 0 0 0 1.00

Belted Kingfisher Passerine 1 0 0 0 1 0 1 0 1 0 0.00

Bl.-crown. Night Heron Marsh/Wading 18 6 3 8 7 0 7 1 4 3 0.44

Black Skimmer Seabird 253 51 16 55 153 0 153 40 14 45 0.22

Black Tern Seabird 9 1 0 1 7 0 7 1 3 1 0.11

Bl.-bell. Whistl. Duck Waterfowl 2 0 0 0 0 0 0 0 2 2 0.00

Black-necked Stilt Shorebird 3 0 0 0 3 0 3 0 0 0 0.00

Blue-winged Teal Waterfowl 6 0 0 0 6 0 6 0 0 0 0.00

Boat-tailed Grackle Passerine 1 0 0 0 1 0 1 0 1 0 0.00

Broad-winged Hawk Raptor 1 0 0 0 1 0 1 0 1 0 0.00

Brown Pelican Seabird 826 152 227 339 248 0 248 177 149 239 0.41

Brown-headed Cowbird Passerine 1 0 0 0 0 0 0 0 1 1 0.00

Bufflehead Waterfowl 1 0 1 1 0 0 0 0 0 0 1.00

Canada Goose Waterfowl 4 0 1 1 1 0 1 1 2 2 0.25

Caspian Tern Seabird 17 7 3 8 4 0 4 2 6 5 0.47

Cattle Egret Marsh/Wading 36 4 4 7 25 0 25 3 4 4 0.19

Clapper Rail Marsh/Wading 120 27 5 29 64 0 64 20 14 27 0.24
 A-124 Western Planning Area Lease Sale 248 Supplemental EIS

Table A-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

Common Loon Diving 75 33 27 39 24 0 24 4 20 12 0.52

Common Moorhen Marsh/Wading 4 1 0 1 3 0 3 0 0 0 0.25

Common Nighthawk Passerine 1 0 0 0 0 0 0 0 1 1 0.00

Common Tern Seabird 25 15 12 16 9 0 9 0 0 0 0.64

Common Yellowthroat Passerine 2 0 0 0 2 0 2 0 0 0 0.00

Cooper’s Hawk Raptor 1 0 0 0 1 0 1 0 1 0 0.00

Cory’s Shearwater Seabird 4 0 0 0 3 0 3 0 1 1 0.00

Dbl-crest. Cormorant Diving 23 2 1 2 17 0 17 2 7 4 0.09

Eastern Kingbird Passerine 2 1 0 1 1 0 1 0 0 0 0.50

Eastern Meadowlark Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Eur. Collared-dove Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Eur. Starling Passerine 2 0 1 1 1 0 1 0 0 0 0.50

Forster’s Tern Seabird 40 17 8 20 12 0 12 6 7 8 0.50

Fulvous Whistl. Duck Waterfowl 1 0 0 0 0 0 0 0 1 1 0.00

Glossy Ibis Marsh/Wading 2 1 1 1 1 0 1 0 0 0 0.50

Great Blue Heron Marsh/Wading 42 5 3 6 26 0 26 4 16 10 0.14

Great Cormorant Diving 1 0 0 0 1 0 1 0 0 0 0.00

Great Egret Marsh/Wading 31 6 6 7 15 0 15 8 3 9 0.23

Great-horned Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Greater Shearwater Seabird 89 7 4 7 55 0 55 27 4 27 0.08

Green Heron Marsh/Wading 16 2 0 2 8 0 8 1 6 6 0.13

Gull-billed Tern Seabird 4 0 0 0 2 0 2 2 4 2 0.00

Herring Gull Seabird 31 10 11 13 10 0 10 2 13 8 0.42

House Sparrow Passerine 2 0 0 0 2 0 2 0 1 0 0.00

Killdeer Shorebird 3 0 0 0 3 0 3 0 0 0 0.00
Catastrophic Spill Event Analysis

A-125

Table A-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

King rail Marsh/Wading 1 0 0 0 0 0 0 0 1 1 0.00

Laughing Gull Seabird 2,981 1,025 355 1,182 1,390 0 1,390 304 371 409 0.40

Leach’s Storm-petrel Seabird 1 1 0 1 0 0 0 0 1 0 1.00

Least Bittern Marsh/Wading 4 0 0 0 4 0 4 0 2 0 0.00

Least Tern Seabird 106 46 7 49 43 0 43 12 3 14 0.46

Less. Bl.-backed Gull Seabird 4 1 1 1 1 0 1 1 2 2 0.25

Less. Scaup Waterfowl 1 0 0 0 0 0 0 1 0 1 0.00

Little Blue Heron Marsh/Wading 5 0 0 0 4 0 4 1 1 1 0.00

Long-bill. Dowitcher Shorebird 1 0 0 0 0 0 0 0 1 1 0.00

Magnif. Frigatebird Seabird 8 3 3 4 2 0 2 1 2 2 0.50

Mallard Waterfowl 26 5 4 6 16 0 16 0 7 4 0.23

Manx Shearwater Seabird 6 1 0 1 5 0 5 0 0 0 0.17

Masked Booby Seabird 9 4 3 4 1 0 1 0 4 4 0.44

Mottled Duck Waterfowl 6 0 0 0 5 0 5 1 1 1 0.00

Mourning Dove Passerine 15 3 1 3 8 0 8 0 6 4 0.20

Muscovy Duck Waterfowl 1 0 0 0 1 0 1 0 1 0 0.00

Neotropic Cormorant Diving 5 0 0 0 2 0 2 3 0 3 0.00

Northern Cardinal Passerine 3 0 0 0 3 0 3 0 0 0 0.00

Northern Gannet Seabird 475 225 189 297 99 0 99 30 107 79 0.63

Northern Mockingbird Passerine 5 0 0 0 4 0 4 0 2 1 0.00

Osprey Raptor 11 2 1 3 6 0 6 0 3 2 0.27

Pied-billed Grebe Diving 32 18 24 24 7 0 7 1 3 1 0.75

Piping Plover Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Purple Gallinule Marsh/Wading 2 0 0 0 2 0 2 0 0 0 0.00

Purple Martin Passerine 5 1 0 1 3 0 3 0 1 1 0.20
 A-126 Western Planning Area Lease Sale 248 Supplemental EIS

Table A-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

Red-breasted Merg. Waterfowl 2 1 1 1 1 0 1 0 1 0 0.50

Reddish Egret Marsh/Wading 2 1 1 1 1 0 1 0 1 0 0.50

Red-shouldered Hawk Raptor 1 0 0 0 0 0 0 0 1 1 0.00

Red-tailed Hawk Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Red-winged Blackbird Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Ring-billed Gull Seabird 2 0 1 1 1 0 1 0 0 0 0.50

Rock Dove (pigeon) Passerine 16 2 2 3 4 0 4 2 10 9 0.19

Roseate Spoonbill Marsh/Wading 15 7 3 7 3 0 3 5 1 5 0.47

Royal Tern Seabird 289 116 66 149 104 0 104 19 47 36 0.52

Ruddy Duck Waterfowl 1 1 0 1 0 0 0 0 0 0 1.00

Ruddy Turnstone Shorebird 13 1 3 3 8 0 8 1 5 2 0.23

Sanderling Shorebird 26 4 2 4 20 0 20 1 6 2 0.15

Sandwich Tern Seabird 70 28 20 34 25 0 25 8 14 11 0.49

Seaside Sparrow Passerine 9 4 0 4 5 0 5 0 0 0 0.44

Semipalm. Sandpiper Shorebird 3 2 1 3 0 0 0 0 0 0 1.00

Short-bill. Dowitcher Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Snowy Egret Marsh/Wading 22 12 9 14 6 0 6 2 3 2 0.64

Sooty Shearwater Seabird 1 0 0 0 0 0 0 0 1 1 0.00

Sooty Tern Seabird 3 0 1 1 2 0 2 0 1 0 0.33

Sora Marsh/Wading 5 2 1 2 1 0 1 2 0 2 0.40

Spotted Sandpiper Shorebird 1 0 0 0 1 0 1 0 0 0 0.00

Surf Scoter Waterfowl 1 1 1 1 0 0 0 0 0 0 1.00

Tri-colored Heron Marsh/Wading 31 9 5 11 7 0 7 11 2 13 0.35

Virginia Rail Marsh/Wading 3 0 0 0 3 0 3 0 1 0 0.00

White Ibis Marsh/Wading 7 1 1 1 4 0 4 2 3 2 0.14
Catastrophic Spill Event Analysis

A-127

Table A-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

White-tail. Tropicbird Seabird 1 0 0 0 1 0 1 0 0 0 0.00

White-wing. Dove Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Willet Shorebird 13 2 1 3 8 0 8 1 3 2 0.23

Wilson’s Plover Shorebird 3 0 0 0 2 0 2 1 0 1 0.00

Yellow-billed Cuckoo Passerine 2 2 0 2 0 0 0 0 0 0 1.00

Yel.-cr. Night Heron Marsh/Wading 9 1 0 1 7 0 7 0 3 1 0.11

Unid. Blackbird Passerine 1 0 0 0 0 0 0 0 1 1 0.00

Unid. Booby Seabird 1 0 0 0 1 0 1 0 1 0 0.00

Unid. Cormorant Diving 14 3 0 3 10 0 10 1 0 1 0.21

Unid. Dowitcher Shorebird 2 1 0 1 1 0 1 0 1 0 0.50

Unid. Duck Waterfowl 2 0 0 0 1 0 1 1 0 1 0.00

Unid. Egret Marsh/Wading 15 2 0 2 11 0 11 2 1 2 0.13

Unid. Flycatcher Passerine 1 1 0 1 0 0 0 0 0 0 1.00

Unid. Grebe Diving 4 2 1 2 2 0 2 0 0 0 0.50

Unid. Gull Seabird 248 79 1 80 134 0 134 33 4 34 0.32

Unid. Hawk Raptor 2 0 0 0 2 0 2 0 0 0 0.00

Unid. Heron Marsh/Wading 15 5 0 5 8 0 8 1 1 2 0.33

Unid. Loon Diving 7 2 2 4 3 0 3 0 1 0 0.57

Unid. Mockingbird Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Owl Raptor 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Passerine Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Pelican Seabird 25 5 1 5 15 0 15 4 1 5 0.20

Unid. Pigeon Passerine 14 2 1 3 6 0 6 1 6 5 0.21

Unid. Rail Marsh/Wading 4 1 0 1 3 0 3 0 0 0 0.25

Unid. Raptor Raptor 1 0 0 0 1 0 1 0 0 0 0.00
 A-128 Western Planning Area Lease Sale 248 Supplemental EIS

Table A-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

Common Name Species 

Group3

Grand 

Total

Visibly Oiled Not Visibly Oiled Unknown Oiling Oiling 

Rate4

Dead Alive Total Dead Alive Total Dead Alive Total

Unid. Sandpiper Shorebird 2 0 0 0 2 0 2 0 2 0 0.00

Unid. Shearwater Seabird 6 0 0 0 5 0 5 1 0 1 0.00

Unid. Shorebird Shorebird 3 2 0 2 0 0 0 1 0 1 0.67

Unid. Skimmer Seabird 6 0 0 0 5 0 5 1 0 1 0.00

Unid. Sparrow Passerine 3 0 0 0 1 0 1 2 0 2 0.00

Unid. Swallow Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unid. Tern Seabird 132 38 1 39 79 0 79 13 2 14 0.30

Unid. Warbler Passerine 1 0 0 0 1 0 1 0 0 0 0.00

Unknown spp. 593 51 2 53 451 0 451 88 1 89 0.09

Other 106 31 3 34 52 0 52 7 14 20 0.32

Column Totals 7,258 2,121 2,642 3,387 3,387 873 1,229 0.24 1 Data obtained from the U.S. Fish and Wildlife Service (FWS) as part of the Deepwater Horizon post-spill monitoring and collection process are summarized for May 12, 

2011 (USDOI, FWS, 2011a). The data used in this table are verified as per FWS’s QA/QC processes. Disclaimer: All data should be considered provisional, incomplete, 

and subject to change (USDOI, FWS, 2011a). For more information, refer to the Weekly Bird Impact Data and Consolidated Wildlife Reports. Numbers in this table have 

been verified against the original data from FWS’s website (USDOI, FWS, 2011a). 2 As of May 12, 2011, 104 avian species had been collected and identified through the Deepwater Horizon post-spill monitoring and collection process (USDOI, FWS, 

2011a). Note: Though the process was triggered by the Deepwater Horizon explosion and oil spill, not all birds recovered were oiled (36% = oiled, 47% = unoiled, 17% = 

unknown), suggesting that “search effort” alone accounted for a large proportion of the total (n = 7,258) birds collected (Piatt et al., 1990a, page 127). Some of the live 

birds collected may have been incapable of flight due to age or molt, and some of the dead birds collected may have died due to natural mortality, predation, or other 

anthropogenic sources of mortality. The overall oiling rate across species including “others” and “unknowns” was 0.24 versus 0.25 for individuals identified to species. 

The oiling rate for the Top 5 (see bold rows in table) most-affected avian species was 0.43 and included representatives only from the seabird group. These are listed in 

descending order based on the number collected: laughing gull (2,981 collected, 0.40 oiling rate); brown pelican (826 collected, 0.41 oiling rate); northern gannet 

(475 collected, 0.63 oiling rate); royal tern (289 collected, 0.52 oiling rate); and black skimmer (253 collected, 0.22 oiling rate). Note: There is a difference between the 

table structure here compared with the original table on FWS’s website. Herein, columns for live birds that later died were not included. Totals associated with each larger 

grouping are correct and sum to those column totals for the May 12, 2011, Collection Report values. Six new species or rows were added and 3 species were removed 

between the December 14, 2010, Collection Report (USDOI, FWS, 2010d) and the May 12, 2011, Collection Report (USDOI, FWS, 2011a). The major difference in 

number (-807) between the more recent and older versions was due to an ~10% overestimate in the previous report representing live birds that later died, as these individuals 

were counted twice in the December 14, 2010, Collection Report (USDOI, FWS, 2010d). 3 For additional information on oiling rates by Species Group and additional statistics, refer to Table 4-12 of the 2012-2017 WPA/CPA Multisale EIS.
Catastrophic Spill Event Analysis

A-129

Table A-5. Birds Collected and Summarized by the U.S. Fish and Wildlife Service: Post-Deepwater Horizon Explosion, Oil Spill, and Response in the 

Gulf of Mexico1, 2 (continued).

4 Oiling Rate: For each species, an oiling rate was calculated by dividing the “total” number of oiled individuals (∑ alive + dead) /∑ of total individuals collected for a given 

species/row. In general, it has been well documented that the number of birds collected after a spill event represents a small fraction of the total oiled population (direct 

mortality) due to various factors: species-specific differences in vulnerability to spilled oil, species-specific differences in distribution, habitat use and behavior; speciesspecific differences in abundance; species-specific differences in carcass deposition rates, persistence rates, and detection probabilities; overall search effort and temporal 

and spatial variation in search effort; and carcass loss due to predation, habitat, weather, tides, and currents (Piatt et al., 1990a and 1990b; Ford et al., 1996; Piatt and Ford, 

1996; Fowler and Flint, 1997; Flint and Fowler, 1998; Flint et al., 1999; Hampton and Zafonte, 2005; Ford, 2006; Castège et al., 2007; Ford and Zafonte, 2009; Byrd et al., 

2009; Flint et al., 2010). For example, Piatt and Ford (1996, Table 1) estimated a mean carcass recovery rate of only 17% for a number of previous oil-bird impact studies. 

Burger (1993) and Wiese and Jones (2001) estimated recovery rates of 20% with the latter study based on a drift-block design to estimate carcass recovery rate from 

beached-bird surveys. Due to the fact that the coastline directly inshore of the well blowout location is primarily marsh and not sandy beaches, due to the distance from the 

blowout location to the coast, and due to predominant currents and wind directions during the event, the number of birds collected will likely represent a recovery estimate 

in the lower ranges of those provided in the literature to date (≤10%). A range of mortality estimates given the total number of dead birds collected through May 12, 2011, 

of 7,258 birds x recovery rates from the literature (0-59% in Piatt and Ford, 1996, Table 1) suggests a lower range of 12,302 birds* (59% recovery rate), an upper range of 

725,800 birds* (0% recovery rate), and 42,694 birds based on the 17% mean recovery rate from Piatt and Ford (1996). The lower range of estimates (i.e., high carcass 

recovery rates) is likely biased low because it assumes no search effort after May 2011 (i.e., no more birds were collected after that date) and does not account for any of the 

detection probability parameters that are currently unknown. The actual avian mortality estimate will likely not be available until the NRDA process has been completed; 

this should include a combination of carcass drift experiments, drift-block experiments, corrections for carcass deposition and persistence rates, scavenger rates, and 

detection probability with additional modeling to more precisely derive an estimate. For additional information on oiling rates by Species Group and additional statistics, 

refer to Table 4-12 of the 2012-2017 WPA/CPA Multisale EIS. Note: Spill volume tends to be a poor predictor of bird mortality associated with an oil spill (Burger, 1993), 

though it should be considered for inclusion in any models to estimate total bird mortality, preferably with some metric of species composition and abundance (preferably 

density) pre-spill (Wilhelm et al., 2007). 

* Corrected values are based on revisiting the original calculations after publication of the 2012-2017 WPA/CPA Multisale EIS. An additional estimate for total mortality 

based on Piatt and Ford (1996) is also provided.
 A-130 Western Planning Area Lease Sale 248 Supplemental EIS

Table A-6 

Federally Listed Avian Species Considered by State and Associated Planning Area in the Gulf of Mexico1

Species Status Critical Habitat IUCN Red List

Status2 States Planning Area

Red-cockaded Woodpecker Endangered No rules published Vulnerable AL, FL, LA, MS, TX WPA, CPA, EPA

Least Tern3 Endangered No rules published Least Concern AL, LA, TX (FL, MS) WPA, CPA, EPA

Piping Plover Threatened Designated Near Threatened AL, FL, LA, MS, TX WPA, CPA, EPA

Roseate Tern Threatened No rules published Least Concern FL only EPA

Wood Stork Endangered No rules published Least Concern AL, FL, MS CPA, EPA

Whooping Crane Endangered Designated Endangered TX, LA4, FL4 WPA, CPA, EPA

Mississippi Sandhill Crane Endangered Designated Not Yet Assessed MS only CPA

Attwater’s Prairie Chicken Endangered No rules published Not Yet Assessed TX only WPA

N. Aplomado Falcon Endangered No rules published Not Yet Assessed TX only WPA

Everglades Snail Kite Endangered Designated Not Yet Assessed FL only EPA

Cape Sable Seaside Sparrow Endangered Designated Not Yet Assessed FL only EPA

Audubon’s Crested Caracara Threatened No rules published Not Yet Assessed FL only EPA

Sprague’s Pipit Candidate NA – Priority 2 Vulnerable LA, TX WPA, CPA

Bald Eagle Delisted No rules published Least Concern AL, FL, LA, MS, TX WPA, CPA, EPA

Peregrine Falcon Delisted Designated Least Concern AL, FL, LA, MS, TX WPA, CPA, EPA

Eastern Brown Pelican Delisted No rules published Least Concern AL, FL, LA, MS, TX WPA, CPA, EPA

Red Knot5 Proposed 

Threatened

NA – proposed threatened Least Concern FL, LA, TX WPA, CPA, EPA

1 Information contained in this table was obtained via an email attachment from the U.S. Fish and Wildlife Service (FWS) on April 6, 2012 (USDOI, FWS, 2012) and from 

FWS’s “Endangered Species” website and associated queries for “species” available from FWS’s website (USDOI, FWS, 2011b). Additional information for each species 

can be found at NatureServe Explorer (2011). Note: All species listed in this table are considered, but only the piping plover, roseate tern, whooping crane, wood stork, 

Mississippi sandhill crane, bald eagle, eastern brown pelican, and red knot will be analyzed. 2 International Union for Conservation of Nature (IUCN) – The Red List classifies species as imperiled (Critically Endangered, Endangered, or Vulnerable), not imperiled 

(Near Threatened or Least Concern), extinct (Extinct, Extinct in the Wild), or Data Deficient (Butchart et al., 2004 and 2005; Harris et al., 2012). If species meet the 

quantitative thresholds of any of the following criteria, they will be added to the Red List: (1) decline in population size; (2) small geographic range; (3) small population 

size plus decline; (4) very small population size; or (5) quantitative analysis. 3 The Interior population of the least tern was listed as endangered on May 28, 1985 (Federal Register, 1985) throughout much of its breeding range in the Midwest. This 

designation does not provide or extend Endangered Species Act (ESA) protection to the breeding population of Gulf Coast “population” of least terns. Similarly, ESA 

protection for breeding least terns only applies to certain segments or areas (inland rivers and lakes ~50 mi [80 km] inland) of Louisiana, Mississippi, and Texas. 4 The whooping crane is considered endangered throughout its range in the U.S. except where nonessential, experimental flocks have been established. More recently, a 

release site (White Lake Wetlands Conservation Area, Vermilion Parish) was added in Louisiana (Table 4-14 of the 2012-2017 WPA/CPA Multisale EIS) with a release of 

10 birds on February 22, 2011. To date, only 3 of the original 10 released cranes remain; an additional release of 16 cranes occurred on December 1, 2011. The Gulf Coast 

States that have these nonessential, experimental flocks include Alabama, Louisiana, Mississippi, and Florida; as well, wild whooping cranes may rarely occur as transients 

in Mississippi and Alabama, but they are not known to breed in either state. 5 The red knot is currently a proposed threatened species as of September 30, 2013 (Federal Register, 2013).
KEYWORD INDEX

Keyword Index Keywords-3 

KEYWORD INDEX

Air Quality, x, 1-14, 2-6, 2-7, 2-8, 3-10, 3-13, 4-6, 4-9, 4-10, 4-11, 4-12, 4-55, 4-93, 4-97 

Alternate Use, 4-13, 4-57 

Alternative Energy, 4-13 

Archaeological Resources, x, xiv, 1-14, 2-6, 2-7, 2-8, 3-6, 4-8, 4-71, 4-72, 4-73, 4-74, 4-75, 4-76, 4-77, 

4-93, 4-98, 4-99 

Artificial Reefs, xiii, 1-14, 2-6, 3-28, 3-30, 3-31, 4-60, 4-67, 4-72, 4-73, 4-75, 4-76, 4-101 

Blowout Preventer, 3-25 

Blowouts, 1-8, 3-25, 4-9, 4-38, 4-40, 4-81 

Catastrophic Spill, 2-9, 3-18, 3-19, 4-3, 4-6, 4-7, 4-8, 4-9, 4-13, 4-15, 4-16, 4-19, 4-20, 4-21, 4-23, 4-25, 

4-27, 4-29, 4-32, 4-34, 4-35, 4-38, 4-45, 4-46, 4-47, 4-48, 4-50, 4-52, 4-53, 4-56, 4-61, 4-67, 4-70, 

4-73, 4-76, 4-78, 4-81, 4-83, 4-87, 4-89, 4-91, 4-97 

Chemosynthetic Communities, xii, 1-14, 2-6, 3-11, 4-34, 4-35, 4-36, 4-37 

Chemosynthetic Deepwater Benthic Communities, 2-8, 4-33, 4-34, 4-36, 4-60 

Coastal and Marine Birds, x, xiii, 2-7, 2-8, 2-9, 4-5, 4-55, 4-56, 4-57, 4-58, 4-59, 4-60, 4-93, 4-98 

Coastal Barrier Beaches, x, xi, 2-7, 2-8, 4-18, 4-20, 4-21, 4-93 

Coastal Infrastructure, xiv, 2-7, 2-9, 3-3, 3-15, 3-16, 3-27, 4-8, 4-23, 4-50, 4-72, 4-75, 4-77, 4-78, 4-79, 

4-80, 4-81, 4-83, 4-86 

Coastal Spills, 3-14, 3-20, 3-21, 4-12, 4-64, 4-72, 4-75, 4-78 

Coastal Zone Management, x, 1-6, 1-11, 1-14, 4-4, 5-7 

Collisions, viii, xi, xiv, 3-25, 3-26, 3-33, 4-12, 4-15, 4-18, 4-23, 4-49, 4-52, 4-57, 4-58, 4-59, 4-78, 4-79, 

4-81, 4-87, 4-97, 4-98 

Commercial Fisheries, x, xiii, 2-7, 2-9, 4-57, 4-63, 4-64, 4-65, 4-66, 4-93, 4-98, 4-99 

Commercial Fishing, x, xii, xiii, 2-5, 4-35, 4-45, 4-50, 4-64, 4-73, 4-76, 4-99, 4-100 

Consultation and Coordination, viii, 1-6, 1-7, 2-5, 3-18, 5-10 

Cumulative Activities, viii, xiii, 3-26, 3-27, 3-28, 3-29, 3-30, 3-31, 4-3, 4-54 

Cumulative Impacts, viii, x, 1-5, 3-27, 3-28, 3-32, 4-3, 4-4, 4-9, 4-10, 4-12, 4-13, 4-15, 4-16, 4-18, 4-19, 

4-20, 4-21, 4-22, 4-24, 4-26, 4-28, 4-30, 4-31, 4-32, 4-34, 4-35, 4-37, 4-38, 4-41, 4-43, 4-44, 4-45, 

4-46, 4-48, 4-50, 4-52, 4-53, 4-55, 4-56, 4-59, 4-60, 4-63, 4-66, 4-67, 4-69, 4-71, 4-72, 4-74, 4-75, 

4-77, 4-78, 4-79, 4-81, 4-83, 4-84, 4-86, 4-88, 4-90, 4-92, 4-94, 4-100, 5-4 

Decommissioning, 1-14, 2-6, 3-14, 3-15, 3-25, 3-30, 3-32, 4-28, 4-29, 4-34, 4-41, 4-44, 4-45, 4-49, 4-60, 

4-61, 4-63, 4-64, 4-65, 4-66, 4-67, 4-69, 4-72, 4-75, 4-83, 4-95, 4-99, 4-100, 5-8 

Deepwater, x, xii, xiii, xiv, 1-7, 1-10, 2-4, 2-5, 2-7, 2-8, 3-7, 3-13, 3-14, 3-16, 3-18, 3-19, 3-20, 3-23, 

3-24, 3-25, 3-26, 3-29, 3-31, 4-4, 4-5, 4-6, 4-7, 4-8, 4-10, 4-11, 4-14, 4-17, 4-20, 4-21, 4-24, 4-25, 4-27, 

4-29, 4-30, 4-32, 4-33, 4-34, 4-35, 4-36, 4-37, 4-38, 4-39, 4-40, 4-43, 4-45, 4-46, 4-47, 4-48, 4-50, 

4-51, 4-52, 4-54, 4-58, 4-62, 4-65, 4-68, 4-70, 4-71, 4-79, 4-80, 4-85, 4-88, 4-89, 4-91, 4-93, 4-94, 

4-101, 5-8 

Deepwater Horizon, x, xiii, xiv, 1-7, 1-10, 2-8, 3-18, 3-19, 3-20, 3-23, 3-24, 3-25, 3-29, 4-4, 4-5, 4-6, 4-7, 

4-8, 4-10, 4-11, 4-14, 4-17, 4-20, 4-21, 4-24, 4-25, 4-27, 4-29, 4-30, 4-32, 4-33, 4-35, 4-36, 4-39, 4-40, 

4-43, 4-45, 4-46, 4-47, 4-48, 4-50, 4-51, 4-52, 4-54, 4-58, 4-62, 4-65, 4-68, 4-70, 4-71, 4-79, 4-88, 

4-89, 4-91, 5-8 
Keywords-4 Western Planning Area Lease Sale 248 Supplemental EIS

Demographics, xiv, 2-7, 2-9, 4-8, 4-79, 4-81, 4-82, 4-83 

Diamondback Terrapins, x, xii, 4-52, 4-53, 4-54, 4-55 

Discharges, x, xi, xiii, 2-9, 3-10, 3-12, 3-14, 3-17, 3-24, 4-12, 4-13, 4-15, 4-16, 4-28, 4-29, 4-31, 4-32, 

4-34, 4-35, 4-37, 4-38, 4-39, 4-44, 4-49, 4-56, 4-58, 4-60, 4-61, 4-63, 4-67, 4-90, 4-93, 4-97, 4-98 

Dispersants, xi, 3-20, 3-24, 4-9, 4-13, 4-15, 4-18, 4-24, 4-30, 4-34, 4-40, 4-44, 4-72, 4-73, 4-75, 4-76, 

4-87, 4-94, 4-97, 4-98 

Dunes, x, xi, 2-7, 2-8, 4-18, 4-19, 4-20, 4-21, 4-93 

Economic Factors, xiv, 2-7, 2-9, 4-8, 4-67, 4-70, 4-82, 4-83, 4-84, 4-85, 4-86 

Employment, xiv, 4-69, 4-70, 4-71, 4-81, 4-82, 4-83, 4-84, 4-86, 4-87, 4-88, 4-96 

Endangered Species Act, 1-6, 2-10, 3-14, 4-4, 4-5, 4-7, 4-44, 4-52, 4-98, 5-8 

Environmental Justice, x, xiv, 1-7, 2-7, 2-9, 4-8, 4-86, 4-87, 4-88, 4-89, 5-10 

Essential Fish Habitat, x, xiii, 1-6, 2-7, 2-9, 4-5, 4-28, 4-60, 4-61, 4-62, 4-63, 4-64, 4-93, 4-98, 5-8 

Explosive Removals, 4-45 

Fish Resources, x, xiii, 2-7, 2-9, 4-60, 4-61, 4-62, 4-63, 4-65, 4-93, 4-98, 4-99 

Fisheries, xiii, 1-10, 1-14, 2-5, 2-8, 4-5, 4-57, 4-58, 4-61, 4-63, 4-64, 4-66, 4-67, 4-68, 4-87, 5-3, 5-5, 5-6, 

5-7, 5-8 

Flaring, 1-9, 1-14, 4-9 

Flower Garden Banks, ix, 2-4, 2-6, 2-7, 2-10, 2-11, 4-3, 4-30, 4-94 

Human Resources, 2-7, 2-9, 4-77, 4-93 

Hurricanes, x, 1-10, 3-33, 4-10, 4-19, 4-20, 4-23, 4-25, 4-29, 4-32, 4-35, 4-38, 4-42, 4-45, 4-47, 4-54, 

4-67, 4-68, 4-73, 4-76, 4-91

Income, xiv, 4-70, 4-81, 4-82, 4-85, 4-86, 4-87, 4-88, 4-89, 5-10 

Infrastructure, vii, x, xi, xii, xiii, xiv, 1-10, 1-12, 2-6, 3-3, 3-4, 3-11, 3-12, 3-15, 3-16, 3-25, 3-27, 3-28, 

3-31, 3-32, 3-33, 4-18, 4-19, 4-22, 4-23, 4-28, 4-41, 4-63, 4-66, 4-69, 4-77, 4-78, 4-79, 4-80, 4-86, 

4-87, 4-88, 4-90, 4-96, 4-97, 4-101 

Land Use, x, xiv, 2-7, 2-9, 3-15, 4-8, 4-69, 4-77, 4-78, 4-79, 4-80, 4-84, 4-88, 4-93

Live Bottoms, 1-7, 4-28, 4-30, 4-38, 4-39, 4-40, 4-43, 4-94, 4-95, 4-99 

Loss of Well Control, vii, xi, 3-24, 3-25, 4-12, 4-15, 4-28, 4-29, 4-32, 4-34, 4-35, 4-37, 4-38, 4-39, 4-40 

Macondo, 4-6, 4-7, 4-14, 4-17, 4-33, 4-35, 4-36, 4-40, 4-43, 4-54, 4-62, 4-65, 4-91

Marine Mammals, x, xii, 1-6, 1-14, 2-6, 2-7, 2-9, 4-4, 4-6, 4-43, 4-44, 4-45, 4-46, 4-47, 4-48, 4-49, 4-93, 

4-98, 5-6, 5-7 

Mercury, 4-16 

Meteorological Conditions, 3-23 

Mitigating Measures, vii, ix, xi, xii, 1-10, 1-11, 1-14, 2-3, 2-4, 2-5, 2-6, 2-9, 2-11, 4-5, 4-6, 4-8, 4-22, 

4-27, 4-49, 4-90, 4-92, 4-93, 4-100, 5-4, 5-9 

Mitigation, 1-11, 1-12, 1-14, 2-4, 2-5, 2-6, 4-6, 4-8, 4-13, 4-22, 4-28, 4-29, 4-34, 4-37, 4-44, 4-49, 4-50, 

4-52, 4-61, 4-63, 4-64, 4-72, 4-80, 4-90, 4-91, 4-92, 4-94, 4-97, 4-99, 4-101, 5-8, 5-9 

NEPA, viii, ix, 1-3, 1-4, 1-5, 1-6, 1-10, 1-11, 1-12, 1-14, 2-3, 2-4, 2-5, 2-7, 4-3, 4-4, 4-5, 4-6, 4-7, 4-8, 

4-9, 4-11, 4-12, 4-14, 4-15, 4-18, 4-20, 4-21, 4-22, 4-25, 4-26, 4-27, 4-28, 4-31, 4-32, 4-33, 4-34, 4-36, 

4-37, 4-41, 4-43, 4-44, 4-47, 4-48, 4-49, 4-52, 4-55, 4-60, 4-63, 4-66, 4-68, 4-69, 4-71, 4-73, 4-74, 

4-76, 4-77, 4-80, 4-81, 4-82, 4-83, 4-86, 4-89, 4-90, 4-91, 4-92, 5-3, 5-4, 5-5, 5-8 
Keyword Index Keywords-5 

Noise, xiii, 3-6, 3-10, 3-13, 4-44, 4-45, 4-49, 4-50, 4-55, 4-56, 4-57, 4-58, 4-69, 4-88, 4-90, 4-91, 4-98 

Nonchemosynthetic Deepwater Benthic Communities, xii, 2-9, 4-37, 4-38, 4-39, 4-40, 4-41, 4-60 

Offshore Spills, xiii, 3-14, 3-20, 3-21, 3-22, 3-24, 4-15, 4-26, 4-64 

Oil Spills, vii, x, xi, xiii, xiv, 1-7, 1-10, 1-14, 2-8, 2-9, 2-10, 3-14, 3-17, 3-18, 3-19, 3-20, 3-21, 3-22, 

3-23, 3-24, 3-25, 3-33, 4-3, 4-4, 4-5, 4-6, 4-7, 4-8, 4-10, 4-11, 4-12, 4-13, 4-14, 4-15, 4-17, 4-18, 4-19, 

4-20, 4-21, 4-22, 4-23, 4-24, 4-25, 4-26, 4-27, 4-28, 4-29, 4-30, 4-32, 4-33, 4-34, 4-35, 4-36, 4-38, 

4-39, 4-40, 4-42, 4-43, 4-44, 4-45, 4-46, 4-47, 4-48, 4-49, 4-50, 4-51, 4-52, 4-53, 4-54, 4-55, 4-56, 

4-57, 4-58, 4-61, 4-62, 4-64, 4-65, 4-67, 4-68, 4-69, 4-70, 4-71, 4-72, 4-73, 4-75, 4-76, 4-78, 4-79, 

4-81, 4-83, 4-87, 4-88, 4-89, 4-90, 4-91, 4-93, 4-94, 4-97, 4-98, 4-99, 4-101, 5-4, 5-8 

OSRA, 1-10, 3-19, 3-20, 3-22 

Physical Oceanography, 1-9, 3-33, 4-74, 4-77 

Pipelines, x, 1-9, 1-14, 2-5, 2-6, 3-11, 3-13, 3-14, 3-15, 3-18, 3-20, 3-21, 3-23, 3-25, 3-27, 3-28, 3-29, 

3-31, 4-9, 4-12, 4-15, 4-17, 4-18, 4-19, 4-22, 4-23, 4-26, 4-27, 4-28, 4-34, 4-37, 4-38, 4-41, 4-55, 4-56, 

4-60, 4-61, 4-63, 4-64, 4-67, 4-72, 4-73, 4-75, 4-76, 4-77, 4-78, 4-90, 4-93, 4-97, 4-98, 4-99, 5-5 

Port Fourchon, xiv, 3-24, 4-80, 4-81, 4-87 

Produced Waters, 3-12, 4-34, 4-55, 4-56, 4-58, 4-60, 4-63, 4-67, 4-97 

Public Services, x

Recreational Fishing, x, xiii, 2-7, 2-9, 4-8, 4-38, 4-50, 4-61, 4-64, 4-66, 4-67, 4-68, 4-69, 4-93, 4-98, 

4-100, 4-101 

Recreational Resources, x, xiii, 2-7, 2-9, 4-8, 4-69, 4-70, 4-71, 4-93 

Renewable Energy, 1-4, 1-13, 3-28, 3-31, 4-16, 4-57, 4-72, 4-73, 4-75, 4-76, 4-84, 4-88, 4-100 

Resource Estimates, 3-3, 3-4 

Sargassum, x, xii, 2-7, 2-8, 4-31, 4-32, 4-33, 4-60, 4-93, 4-97 

Sea Turtles, x, xii, 1-14, 2-6, 2-7, 2-9, 4-6, 4-48, 4-49, 4-50, 4-51, 4-52, 4-90, 4-93

Seagrass Communities, x, xi, 2-7, 2-8, 4-26, 4-27, 4-60, 4-61, 4-93 

Service Base, 3-15, 3-16, 4-23, 4-77, 4-78 

Site Clearance, xiv, 1-14, 2-5 

Soft Bottoms, x, xii, 2-7, 2-8, 3-30, 4-6, 4-40, 4-41, 4-42, 4-43, 4-60, 4-93 

Spill Response, 1-4, 1-14, 3-17, 3-22, 3-23, 3-24, 4-7, 4-11, 4-18, 4-19, 4-24, 4-47, 4-53, 4-78, 4-97 

Spills, viii, xi, xii, xiii, xiv, 1-14, 2-12, 3-14, 3-17, 3-18, 3-19, 3-20, 3-21, 3-22, 3-23, 3-25, 3-26, 3-33, 

4-4, 4-12, 4-13, 4-15, 4-18, 4-19, 4-22, 4-23, 4-25, 4-27, 4-32, 4-33, 4-34, 4-38, 4-40, 4-44, 4-45, 4-48, 

4-49, 4-52, 4-53, 4-55, 4-56, 4-57, 4-61, 4-64, 4-67, 4-68, 4-69, 4-70, 4-72, 4-75, 4-76, 4-78, 4-81, 

4-83, 4-87, 4-89, 4-91, 4-93, 4-94, 4-97, 4-98 

Stipulation, 1-6, 1-14, 2-3, 2-4, 2-5, 2-9, 2-10, 2-11, 3-30, 4-5, 4-6, 4-8, 4-27, 4-28, 4-29, 4-30, 4-35, 

4-42, 4-45, 4-49, 4-50, 4-53, 4-60, 4-92, 4-93, 4-94, 4-95, 4-99 

Submerged Vegetation, 4-26, 4-27 

Synthetic-Based Drilling Fluids, 3-26 

Topographic Features, ix, x, xi, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-11, 3-11, 4-6, 4-28, 4-29, 4-30, 4-31, 4-60, 

4-92, 4-93, 4-94, 4-95 

Tourism, x, 1-9, 1-10, 4-19, 4-23, 4-67, 4-68, 4-69, 4-70, 4-71, 4-82, 4-84, 4-88, 4-101, 5-6, 5-10 

Trash, x, 3-17, 4-44, 4-49, 4-50, 4-52, 4-53, 4-54, 4-56, 4-57, 4-90, 4-98 
Keywords-6 Western Planning Area Lease Sale 248 Supplemental EIS

Waste Disposal, 4-17, 4-23, 4-77, 4-78 

Wastes, xi, 2-6, 3-10, 3-12, 3-13, 3-17, 3-28, 4-16, 4-17, 4-22 

Water Quality, x, xi, xii, 1-10, 2-6, 2-7, 2-8, 3-15, 4-6, 4-12, 4-13, 4-14, 4-15, 4-16, 4-17, 4-32, 4-44, 

4-49, 4-60, 4-61, 4-67, 4-70, 4-93, 4-97, 4-98, 4-101 

Wetlands, x, xi, 1-7, 2-6, 2-7, 2-8, 3-32, 4-5, 4-6, 4-18, 4-20, 4-22, 4-23, 4-24, 4-25, 4-26, 4-27, 4-58, 

4-60, 4-61, 4-64, 4-65, 4-67, 4-69, 4-70, 4-91, 4-93, 4-97, 4-99, 4-101, 5-4 


The Department of the Interior Mission

As the Nation’s principal conservation agency, the Department of the Interior 

has responsibility for most of our nationally owned public lands and natural 

resources. This includes fostering the sound use of our land and water 

resources; protecting our fish, wildlife, and biological diversity; preserving the 

environmental and cultural values of our national parks and historical places; 

and providing for the enjoyment of life through outdoor recreation. The 

Department assesses our energy and mineral resources and works to ensure 

that their development is in the best interests of all our people by encouraging 

stewardship and citizen participation in their care. The Department also has a 

major responsibility for American Indian reservation communities and for 

people who live in island communities. 

The Bureau of Ocean Energy Management Mission 

The Bureau of Ocean Energy Management (BOEM) promotes energy 

independence, environmental protection, and economic development through 

responsible, science-based management of offshore conventional and 

renewable energy.